From patchwork Thu Nov 1 22:52:19 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Eric Biggers X-Patchwork-Id: 10664639 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 798AC1751 for ; Thu, 1 Nov 2018 22:55:44 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 6BEA42C104 for ; Thu, 1 Nov 2018 22:55:44 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 6024A2C108; Thu, 1 Nov 2018 22:55:44 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.0 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 6CB8D2C143 for ; Thu, 1 Nov 2018 22:55:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728150AbeKBIAc (ORCPT ); Fri, 2 Nov 2018 04:00:32 -0400 Received: from mail.kernel.org ([198.145.29.99]:52106 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727802AbeKBH7Q (ORCPT ); Fri, 2 Nov 2018 03:59:16 -0400 Received: from ebiggers-linuxstation.kir.corp.google.com (unknown [104.132.51.88]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 442C020820; Thu, 1 Nov 2018 22:54:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1541112856; bh=R4PUenXPuedKWQiz0Wk1RCRSiiLRC7ql+6ApGKumO0Q=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=josggMRG/QDeDnvPYFwTgfKpPWu4UgGvj0/RCHGGErPJ4a8JEh61WGWtttqTB80dS BvK+w4QOV1Bv/ntG2fHVI9feGXX1fbc7Wco2rn8WnsrnenITAaKrWAb+tU3dT6J/zk 3K+GVbDhotJdBLKb3W1lA2dd81KIigFvIVvt5jes= From: Eric Biggers To: linux-fscrypt@vger.kernel.org Cc: linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-integrity@vger.kernel.org, linux-kernel@vger.kernel.org, "Theodore Y . Ts'o" , Jaegeuk Kim , Victor Hsieh , Chandan Rajendra Subject: [PATCH v2 01/12] fs-verity: add a documentation file Date: Thu, 1 Nov 2018 15:52:19 -0700 Message-Id: <20181101225230.88058-2-ebiggers@kernel.org> X-Mailer: git-send-email 2.19.1.568.g152ad8e336-goog In-Reply-To: <20181101225230.88058-1-ebiggers@kernel.org> References: <20181101225230.88058-1-ebiggers@kernel.org> MIME-Version: 1.0 Sender: linux-fscrypt-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fscrypt@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Eric Biggers Add a documentation file for fs-verity, covering: - Introduction - Use cases - Metadata format - Merkle tree - fs-verity descriptor - fsveritysetup format - Filesystem support - ext4 - f2fs - User API - FS_IOC_ENABLE_VERITY - FS_IOC_MEASURE_VERITY - Access semantics - In-kernel policies - Built-in signature verification - Implementation details - I/O path design - Userspace utility - Tests Signed-off-by: Eric Biggers --- Documentation/filesystems/fsverity.rst | 583 +++++++++++++++++++++++++ Documentation/filesystems/index.rst | 11 + 2 files changed, 594 insertions(+) create mode 100644 Documentation/filesystems/fsverity.rst diff --git a/Documentation/filesystems/fsverity.rst b/Documentation/filesystems/fsverity.rst new file mode 100644 index 0000000000000..d633fc0567bd5 --- /dev/null +++ b/Documentation/filesystems/fsverity.rst @@ -0,0 +1,583 @@ +======================================================== +Read-only file-based authenticity protection (fs-verity) +======================================================== + +Introduction +============ + +fs-verity (``fs/verity/``) is a library that filesystems can hook into +to support transparent integrity and authenticity protection of +read-only files. Currently, it is supported by the ext4 and f2fs +filesystems. Similar to fscrypt, not too much filesystem-specific +code is needed to support fs-verity. + +fs-verity is similar to `dm-verity +`_ +but works on files rather than block devices. On supported +filesystems, userspace can append a Merkle tree (hash tree) to a file, +then use an ioctl to enable fs-verity on it. Then, the filesystem +transparently verifies all data read from the file against the Merkle +tree; reads that fail verification will fail. The filesystem also +hides or moves the Merkle tree, and forbids changes to the file's +contents via the syscall interface. + +Essentially, fs-verity is a way of efficiently hashing a file, subject +to the caveat that the enforcement of that hash happens on-demand as +reads occur. The file hash that fs-verity computes is called the +"file measurement"; this is the hash of the Merkle tree's root hash +and certain other fs-verity metadata, and it takes constant time to +compute regardless of the size of the file. Note: the value of the +fs-verity file measurement will differ from a regular hash of the +file, even when they use the same hash algorithm, e.g. SHA-256; +however, they achieve the same purpose. + +Use cases +========= + +In general, fs-verity does not replace or obsolete dm-verity. +dm-verity should still be used when it is possible to authenticate the +full block device, i.e. when the device is read-only. fs-verity is +intended for use on read-write filesystems where dm-verity cannot be +used. + +fs-verity is most useful for hashing large files where only a small +portion may be accessed. For example, it's useful on Android +application package (APK) files, which typically contain many +translations, classes, and other resources that are infrequently or +even never accessed on a particular device. It would be wasteful to +hash the entire file before starting the application. + +Unlike an ahead-of-time hash, fs-verity also re-verifies data each +time it's paged in, which ensures the file measurement remains +correctly enforced even if the file contents are modified from +underneath the filesystem, e.g. by malicious disk firmware. + +fs-verity can support various use cases, such as: + +- Integrity protection (detecting accidental corruption) +- Auditing (logging file hashes before use) +- Authenticity protection (detecting malicious modification) + +Note that the latter two are not features of fs-verity per se, but +rather fs-verity is a tool for supporting these use cases. For +example, for the overall system to actually provide authenticity +protection, the file measurement itself must still be authenticated, +e.g. by comparing it with a known good value or by verifying a digital +signature of it. + +This can be userspace driven, in which case fs-verity will only be +used (essentially) as a fast way of hashing the file contents, via the +`FS_IOC_MEASURE_VERITY`_ ioctl. For authenticity protection, trusted +userspace code [#]_ still must verify the relevant portions of the +untrusted filesystem state before it is used in a security-critical +way, such as executing code from it. + +For example, the trusted userspace code might verify that the file +located at ``/foo/bar/baz`` has an fs-verity file measurement of +``sha256:a83d5cd722ef0d070b23353c2d9f316c38425114da8bd007cb9e8499371a97b3``, +or that all security-critical files (e.g. executable code) have stored +alongside them a valid digital signature (signed by a known, trusted +public key) of their fs-verity file measurement, potentially combined +with other important file metadata such as path and SELinux label. + +However, for ease of use, a subset of this policy logic (but not all +of it!) is also supported in the kernel by the `Built-in signature +verification`_ mechanism. Support for fs-verity file hashes in IMA +(Integrity Measurement Architecture) policies is also planned. + +.. [#] For example, on Android, "trusted userspace code" would be code + running from the system or vendor partitions, which are + read-only partitions authenticated by dm-verity tied into + Verified Boot, as opposed to the userdata partition which is + read-write. + +Metadata format +=============== + +Merkle tree +----------- + +fs-verity uses the same Merkle tree (hash tree) format as dm-verity; +the only difference is that fs-verity's Merkle tree is built over the +contents of a regular file rather than a block device. + +Briefly, the file contents is divided into blocks, where the blocksize +is configurable but usually 4096 bytes. The last block is zero-padded +if needed. Each block is then hashed, producing the first level of +hashes. Then, the hashes in this first level are grouped into +'blocksize'-byte blocks (zero-padding the ends as needed) and these +blocks are hashed, producing the second level of hashes. This +proceeds up the tree until only a single block remains. The hash of +this block is called the "Merkle tree root hash". Note: if the entire +file contents fit in one block, then there are no hash blocks and the +"Merkle tree root hash" is simply the hash of the data block. + +The blocks of the Merkle tree are stored on-disk starting from the +root level and then proceeding to store each level down to the "first" +(the level that gives the hashes of the data blocks). + +The hash algorithm is configurable. The default is SHA-256, but +SHA-512 is also supported. The non-cryptographic checksum CRC-32C is +also supported for integrity-only use cases such as detecting bit +errors in read-only backup files. A non-cryptographic checksum must +not be used if authenticity protection is desired. + +In the recommended configuration of SHA-256 and 4K blocks, 128 hash +values fit in each block. Thus, each level of the hash tree is 128 +times smaller than the previous, and for large files the Merkle tree's +size converges to approximately 1/129 of the original file size. +However, for small files, the padding to a block boundary is +significant, making the space overhead proportionally more. + +fs-verity descriptor +-------------------- + +For each file, fs-verity also uses an additional on-disk metadata +structure called the *fs-verity descriptor*. This contains the +properties of the Merkle tree and some other information. It begins +with a header in the following format:: + + struct fsverity_descriptor { + __u8 magic[8]; + __u8 major_version; + __u8 minor_version; + __u8 log_data_blocksize; + __u8 log_tree_blocksize; + __le16 data_algorithm; + __le16 tree_algorithm; + __le32 flags; + __le32 reserved1; + __le64 orig_file_size; + __le16 auth_ext_count; + __u8 reserved2[30]; + }; + +This structure contains: + +- ``magic`` is the ASCII bytes "FSVerity". +- ``major_version`` is 1. +- ``minor_version`` is 0. +- ``log_data_blocksize`` and ``log_tree_blocksize`` are the log base 2 + of the block size (in bytes) of data blocks and Merkle tree blocks, + respectively. Currently, in both cases the kernel only supports + page-sized blocks, i.e. on most architectures, 4096-byte blocks. + Thus, usually both of these fields must be 12. +- ``data_algorithm`` and ``tree_algorithm`` are the hash algorithms + used to hash data blocks and Merkle tree blocks, respectively. + Currently the kernel requires these to have the same value. The + recommended value is FS_VERITY_ALG_SHA256. See + ``include/uapi/linux/fsverity.h`` for the list of allowed values. +- ``orig_file_size`` is the original size of the file in bytes. This + means the size excluding the verity metadata and padding. +- ``auth_ext_count`` is the number of authenticated extensions that + follow. +- All other fields are zeroed. + +Following the ``struct fsverity_descriptor``, there is a list of +"authenticated extensions". Each extension is a variable-length +structure that begins with the following header:: + + struct fsverity_extension { + __le32 length; + __le16 type; + __le16 reserved; + }; + +This structure contains: + +- ``length`` is the length of this extension in bytes, including the + header. +- ``type`` is the extension number. See + ``include/uapi/linux/fsverity.h`` for the allowed values. +- ``reserved`` must be 0. + +Each extension begins on an 8-byte aligned boundary. When an +extension's length is not a multiple of 8, it must be zero-padded to +the next 8-byte boundary, even if it is the last extension. This zero +padding is not counted in the ``length`` field. + +This first list of extensions is "authenticated", meaning that they +are included in the file measurement. Currently, the following +authenticated extensions are supported. Except where otherwise +indicated, extensions are optional and cannot be given multiple times: + +- FS_VERITY_EXT_ROOT_HASH: This is mandatory. It gives the root hash + of the Merkle tree, as a byte array. +- FS_VERITY_EXT_SALT: A salt to salt the hashes with, given as a byte + array. The salt is prepended to every block that is hashed. Any + length salt is supported. Note that using a unique salt for every + file should make it more difficult for fs-verity to be attacked + across many files. However, in principle this is unnecessary since + simply choosing a strong cryptographic hash algorithm such as + SHA-256 or SHA-512 should be sufficient. + +Following the authenticated extensions, there is a list of +unauthenticated extensions. These are *not* included in the file +measurement. This list begins with a header:: + + __le16 unauth_ext_count; + __le16 padding[3]; + +``unauth_ext_count`` is the number of unauthenticated extensions. +This may be 0. + +Like authenticated extensions, each unauthenticated extension begins +with the header ``struct fsverity_extension`` from above. + +The following types of unauthenticated extensions are supported: + +- FS_VERITY_EXT_PKCS7_SIGNATURE. This is a DER-encoded PKCS#7 message + containing the signed file measurement. See `Built-in signature + verification`_ for details. + +fsveritysetup format +-------------------- + +When enabling fs-verity on a file via the `FS_IOC_ENABLE_VERITY`_ +ioctl, the kernel requires that the verity metadata has been appended +to the file contents. Specifically, the file must be arranged as: + +#. Original file contents +#. Zero-padding to next block boundary +#. `Merkle tree`_ +#. `fs-verity descriptor`_ +#. fs-verity footer + +We call this file format the "fsveritysetup format". It is not +necessarily the on-disk format actually used by the filesystem, since +the filesystem is free to move things around during the ioctl. +However, the easiest way to implement fs-verity is to just keep this +arrangement in-place, as ext4 and f2fs do; see `Filesystem support`_. + +Note that "block" here means the fs-verity block size, which is not +necessarily the same as the filesystem's block size. For example, on +ext4, fs-verity can use 4K blocks on top of a filesystem formatted to +use a 1K block size. + +The fs-verity footer is a structure of the following format:: + + struct fsverity_footer { + __le32 desc_reverse_offset; + __u8 magic[8]; + }; + +``desc_reverse_offset`` is the distance in bytes from the end of the +fs-verity footer to the beginning of the fs-verity descriptor; this +allows software to find the fs-verity descriptor. ``magic`` is the +ASCII bytes "FSVerity"; this allows software to quickly identify a +file as being in the "fsveritysetup" format as well as find the +fs-verity footer if zeroes have been appended. + +The kernel cannot handle fs-verity footers that cross a page boundary. +Padding must be prepended as needed to meet this constaint. + +Filesystem support +================== + +ext4 +---- + +ext4 supports fs-verity since kernel version TODO. + +CONFIG_EXT4_FS_VERITY must be enabled in the kernel config. Also, the +filesystem must have been formatted with ``-O verity``, or had +``tune2fs -O verity`` run on it. These require e2fsprogs v1.44.4-2 or +later. This e2fsprogs version is also required for e2fsck to +understand the verity feature. Since "verity" is an RO_COMPAT +feature, once enabled earlier kernels will be unable to mount the +filesystem for writing, and earlier versions of e2fsck will be unable +to check the filesystem. + +ext4 only allows fs-verity on extent-based files. + +The EXT4_VERITY_FL flag in the inode is used to indicate that the +inode uses fs-verity. This bit cannot be set directly; it can only be +set indirectly via `FS_IOC_ENABLE_VERITY`_. + +When enabling verity on an inode, ext4 leaves the verity metadata +in-place in the `fsveritysetup format`_. However, it changes the +on-disk i_size to the original file size, which allows the verity +feature to be RO_COMPAT rather than INCOMPAT. Later, the fs-verity +footer is found by scanning backwards from the end of the last extent +rather than from i_size. + +f2fs +---- + +f2fs supports fs-verity since kernel version TODO. + +CONFIG_F2FS_FS_VERITY must be enabled in the kernel config. Also, the +filesystem must have been formatted with ``-O verity``. This requires +f2fs-tools v1.11.0 or later. + +The FADVISE_VERITY_BIT flag in the inode is used to indicate that the +inode uses fs-verity. This bit cannot be set directly; it can only be +set indirectly via `FS_IOC_ENABLE_VERITY`_. + +When enabling verity on an inode, f2fs leaves the verity metadata +in-place in the `fsveritysetup format`_. It leaves the on-disk i_size +as the full file size; however, the in-memory i_size is overridden +with the original size. + +User API +======== + +FS_IOC_ENABLE_VERITY +-------------------- + +The FS_IOC_ENABLE_VERITY ioctl enables fs-verity on a regular file. +Userspace must have already appended verity metadata to the file, +using the file format described in `fsveritysetup format`_. +Additionally, the filesystem must support fs-verity. + +The argument parameter for this ioctl is reserved and must be NULL. + +This ioctl checks for write access to the inode; no capability is +required. However, it must be executed on an O_RDONLY file +descriptor, and no processes may have the file open for writing. +(This is necessary to prevent various race conditions.) + +On success, this ioctl returns 0, and the file becomes a verity file. +This means that: + +- The filesystem marks the file as a verity file both in-memory and + on-disk, e.g. by setting a bit in the inode. +- All later reads from the file are verified against the Merkle tree. +- The verity metadata at the end of the file is hidden or moved. +- Opening the file for writing or truncating it is no longer allowed. +- There is no way to disable verity on the file, other than by + deleting it and replacing it with a copy. + +If this ioctl fails, then no changes are made to the file. The +reasons it might fail include: + +- ``EACCES``: the process does not have write access to the file +- ``EBADMSG``: the file's fs-verity metadata is invalid +- ``EEXIST``: the file already has fs-verity enabled +- ``EINVAL``: a value was specified for the reserved argument + parameter, or the file descriptor refers to neither a regular file + nor a directory +- ``EIO``: an I/O error occurred +- ``EISDIR``: the file descriptor refers to a directory, not a regular + file +- ``ENOTTY``: this type of filesystem does not implement fs-verity +- ``EOPNOTSUPP``: the kernel was not configured with fs-verity support + for this filesystem, or the filesystem superblock has not had the + 'verity' feature enabled on it. (See `Filesystem support`_.) +- ``EPERM``: the file is append-only +- ``EROFS``: the filesystem is read-only +- ``ETXTBSY``: the file is open for writing. Note that this can be + the caller's file descriptor, or another open file descriptor, or + the file reference held by a writable memory map. + +FS_IOC_MEASURE_VERITY +--------------------- + +The FS_IOC_MEASURE_VERITY ioctl retrieves the fs-verity measurement of +a regular file. This is a digest that cryptographically summarizes +the file contents that are being enforced on reads. The file must +have fs-verity enabled. + +This ioctl takes in a pointer to a variable-length structure:: + + struct fsverity_digest { + __u16 digest_algorithm; + __u16 digest_size; /* input/output */ + __u8 digest[]; + }; + +``digest_size`` is an input/output field. On input, it must be +initialized to the number of bytes allocated for the variable-length +``digest`` field. + +On success, 0 is returned and the kernel fills in the structure as +follows: + +- ``digest_algorithm`` will be the hash algorithm used for the file + measurement. It will match the algorithm used in the Merkle tree, + e.g. FS_VERITY_ALG_SHA256. See ``include/uapi/linux/fsverity.h`` + for the list of possible values. +- ``digest_size`` will be the size of the digest in bytes, e.g. 32 + for SHA-256. (This can be redundant with ``digest_algorithm``.) +- ``digest`` will be the actual bytes of the digest. + +This ioctl is guaranteed to be very fast. Due to fs-verity's use of a +Merkle tree, its running time is independent of the file size. + +This ioctl can fail with the following errors: + +- ``EFAULT``: invalid buffer was specified +- ``ENODATA``: the file is not a verity file +- ``ENOTTY``: this type of filesystem does not implement fs-verity +- ``EOPNOTSUPP``: the kernel was not configured with fs-verity support + for this filesystem, or the filesystem superblock has not had the + 'verity' feature enabled on it. (See `Filesystem support`_.) +- ``EOVERFLOW``: the file measurement is longer than the specified + ``digest_size`` bytes. Try providing a larger buffer. + +Access semantics +================ + +fs-verity only implements reads, not writes. Therefore, after it is +enabled on a given file, regardless of the mode bits filesystems will +forbid opening the file for writing as well as changing the size of +the file via truncate(). The error code received for this is EPERM. + +However, fs-verity does not measure metadata such as owner, mode, +timestamps, and xattrs. Therefore, changes to these are still +allowed. + +For read-only access, fs-verity is intended to be transparent; no +changes to userspace applications should be needed. However, astute +users may notice some slight differences in behavior: + +- Direct I/O is not supported on verity files. Attempts to use direct + I/O on such files will fall back to buffered I/O. + +- DAX (Direct Access) is not supported on verity files. + +Note: read-only mmaps are supported, as is combining fs-verity and +fscrypt. + +Verity files can be sparse; holes are still verified. + +In-kernel policies +================== + +Built-in signature verification +------------------------------- + +With CONFIG_FS_VERITY_BUILTIN_SIGNATURES=y, fs-verity supports putting +a portion of an authentication policy (see `Use cases`_) in the +kernel. Specifically, it adds support for: + +1. At fs-verity module initialization time, a keyring ".fs-verity" is + created. The root user can add trusted X.509 certificates to this + keyring using the add_key() system call, then (when done) + optionally use keyctl_restrict_keyring() to prevent additional + certificates from being added. + +2. When a PKCS7_SIGNATURE extension containing a signed file + measurement is found in a file's verity metadata, the kernel will + verify this signature against the certificates in the ".fs-verity" + keyring, and verify that it matches the actual file measurement. + The extension must contain the PKCS#7 formatted signature in DER + format, where the signed data is the file measurement as a ``struct + fsverity_digest`` as described for `FS_IOC_MEASURE_VERITY`_ except + that all fields must be little-endian rather than native endian. + +3. A new sysctl "fs.verity.require_signatures" is made available. + When set to 1, the kernel requires that all fs-verity files have a + correctly signed file measurement as described in (2). + +This is meant as a relatively simple mechanism that can be used to +provide some level of authenticity protection for fs-verity files, as +an alternative to doing the signature verification in userspace or +using IMA-appraisal. However, with this mechanism, userspace programs +still need to check that the fs-verity bit is set, and there is no +protection against fs-verity files being swapped around. + +Implementation details +====================== + +I/O path design +--------------- + +To support fs-verity, the filesystem's ``->readpage()`` and +``->readpages()`` methods are modified to verify the data pages before +they are marked Uptodate. Merely hooking ``->read_iter()`` would be +insufficient, since ``->read_iter()`` is not used for memory maps. +fs-verity exposes functions to verify data: + +- ``fsverity_verify_page()`` verifies an individual page +- ``fsverity_verify_bio()`` verifies all pages in a bio + +Currently, fs-verity only supports the case where data blocks, hash +blocks, and pages all have the same size (usually 4096 bytes). + +Filesystems that use bios call ``fsverity_verify_bio()`` after each +read bio completes. To do this while also continuing to support +encryption (fscrypt), filesystems allocate a "post-read context" for +each bio and store it in ``->bi_private``:: + + struct bio_post_read_ctx { + struct bio *bio; + struct work_struct work; + unsigned int cur_step; + unsigned int enabled_steps; + }; + +``enabled_steps`` is a bitmask of the post-read steps that are +enabled. The available steps are STEP_DECRYPT and STEP_VERITY. These +steps can be enabled together, independently, or not at all. If both +are enabled, then decryption is done first. Since bio completion +callbacks cannot sleep, each post-read step is done by enqueueing the +struct on a workqueue, and then actual work happens in the work item. +Different workqueues are needed for encryption and verity because +verity work may require decrypting metadata pages from the file. + +The bio completion callback sets PG_error for each page if either +decryption or verification failed. Finally, after the work item(s) +complete, pages without PG_error are set Uptodate, and all pages are +unlocked. + +A data page being set Uptodate and unlocked implies that it has been +verified, and such pages become visible to userspace via read(), +mmap(), etc. Otherwise, the page is left in the PG_error && !Uptodate +state which results in the read() family of syscalls failing with EIO, +and accesses to the data via a memory map raising SIGBUS. Note that +even if some pages in a file fail verification, pages that pass +verification can still be read. + +To verify a data page, fs-verity reads the required hash page(s) +starting at the leaves and ascending to the root; then, the pages are +verified descending from the root. Filesystems that store the verity +metadata past EOF implement reading hash pages using their usual +``->readpage{,s}()`` methods, with modifications: + +- Verification is skipped for pages beyond ``i_size``. +- When checking whether a page is in the implicit hole beyond EOF, + the full file size (including the verity metadata) is used rather + than the original data i_size. Note that this does not allow + userspace to read or mmap the verity metadata. + +The hash pages are also cached in the inode's address_space, similar +to data pages. However, to simplify the verification logic, a hash +page being Uptodate doesn't imply that it has been verified; instead, +the PG_checked bit is used for this purpose. Hash pages aren't locked +while being verified, so multiple threads may race to set PG_checked, +but this doesn't matter. + +Thus, when ascending the tree reading hash pages, fs-verity can stop +as soon as it finds an already-checked hash page. This optimization, +which is also used by dm-verity, results in excellent sequential read +performance since usually the deepest needed hash page will already be +cached and checked. However, random reads perform worse. + +Files may contain holes. Normally, the filesystem's +``->readpage{,s}()`` methods will zero pages in holes and set them +Uptodate without issuing any bios. To prevent this from being abused +to bypass fs-verity, filesystems call ``fsverity_verify_page()`` on +hole pages. + +Like fscrypt, filesystems also disable direct I/O on verity files, +since direct I/O bypasses the normal read paths. + +Userspace utility +================= + +This document focuses on the kernel, but a userspace utility for +fs-verity can be found at: + + https://git.kernel.org/pub/scm/linux/kernel/git/ebiggers/fsverity-utils.git + +See the README.md file in the fsverity-utils source tree for details, +including examples of setting up fs-verity protected files. + +Tests +===== + +To test fs-verity, use xfstests. For example, using `kvm-xfstests +`_:: + + kvm-xfstests -c ext4,f2fs -g verity diff --git a/Documentation/filesystems/index.rst b/Documentation/filesystems/index.rst index 46d1b1be3a510..818390c32be63 100644 --- a/Documentation/filesystems/index.rst +++ b/Documentation/filesystems/index.rst @@ -359,3 +359,14 @@ encryption of files and directories. :maxdepth: 2 fscrypt + +Verity API +========== + +A library which filesystems can hook into to support transparent +authentication of read-only files. + +.. toctree:: + :maxdepth: 2 + + fsverity From patchwork Thu Nov 1 22:52:20 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Eric Biggers X-Patchwork-Id: 10664627 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id B949D17DB for ; Thu, 1 Nov 2018 22:55:26 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id AB8CB2C104 for ; Thu, 1 Nov 2018 22:55:26 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 9FC302C4D2; Thu, 1 Nov 2018 22:55:26 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.0 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 730162C108 for ; Thu, 1 Nov 2018 22:55:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728331AbeKBIAU (ORCPT ); Fri, 2 Nov 2018 04:00:20 -0400 Received: from mail.kernel.org ([198.145.29.99]:52110 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728004AbeKBH7Q (ORCPT ); Fri, 2 Nov 2018 03:59:16 -0400 Received: from ebiggers-linuxstation.kir.corp.google.com (unknown [104.132.51.88]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 6E09820831; Thu, 1 Nov 2018 22:54:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1541112856; bh=mSdD+tMBt0/5h/Fvp6b9krMKfbGfSCB5C/EwootHXqA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Vr+6FjaLIInJVCdUhIkFCrdsVmtHlg1fd3+/BRbUI/+xrHyhpN3Lpyrx7aAKUKvYu jOkB2i3YHguV3+i47arJK0iby13/vNmI7P2jV1FXIKuME9EQd1jZ/dMAgKU1MQKeyh bXzW/4Ujk7JJpfDhuj2j67VY2iwp9zbNWw6c3cdA= From: Eric Biggers To: linux-fscrypt@vger.kernel.org Cc: linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-integrity@vger.kernel.org, linux-kernel@vger.kernel.org, "Theodore Y . Ts'o" , Jaegeuk Kim , Victor Hsieh , Chandan Rajendra Subject: [PATCH v2 02/12] fs-verity: add setup code, UAPI, and Kconfig Date: Thu, 1 Nov 2018 15:52:20 -0700 Message-Id: <20181101225230.88058-3-ebiggers@kernel.org> X-Mailer: git-send-email 2.19.1.568.g152ad8e336-goog In-Reply-To: <20181101225230.88058-1-ebiggers@kernel.org> References: <20181101225230.88058-1-ebiggers@kernel.org> MIME-Version: 1.0 Sender: linux-fscrypt-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fscrypt@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Eric Biggers Add the beginnings of fs-verity support, including: - The fs-verity Kconfig option (CONFIG_FS_VERITY) - The fs-verity UAPI declarations (uapi/linux/fsverity.h) - The internal API header for filesystems to use (linux/fsverity.h) - The "setup" code which parses the fs-verity descriptor to create an fsverity_info structure that is attached to the in-memory inode; this structure describes the Merkle tree properties and contains the file measurement. This is called from the ->open() and ->getattr() hooks. - Hash algorithm management; initially supporting SHA-256 only. The actual ->readpages() data verification, the ioctl implementations, ext4 and f2fs support, and other functionality comes in later patches. For more information about fs-verity, see the documentation file Documentation/filesystems/fsverity.rst. Signed-off-by: Eric Biggers --- Documentation/ioctl/ioctl-number.txt | 1 + fs/Kconfig | 2 + fs/Makefile | 1 + fs/verity/Kconfig | 35 ++ fs/verity/Makefile | 3 + fs/verity/fsverity_private.h | 98 ++++ fs/verity/hash_algs.c | 106 ++++ fs/verity/setup.c | 823 +++++++++++++++++++++++++++ include/linux/fs.h | 9 + include/linux/fsverity.h | 62 ++ include/uapi/linux/fsverity.h | 86 +++ 11 files changed, 1226 insertions(+) create mode 100644 fs/verity/Kconfig create mode 100644 fs/verity/Makefile create mode 100644 fs/verity/fsverity_private.h create mode 100644 fs/verity/hash_algs.c create mode 100644 fs/verity/setup.c create mode 100644 include/linux/fsverity.h create mode 100644 include/uapi/linux/fsverity.h diff --git a/Documentation/ioctl/ioctl-number.txt b/Documentation/ioctl/ioctl-number.txt index af6f6ba1fe804..e9ab862adbf90 100644 --- a/Documentation/ioctl/ioctl-number.txt +++ b/Documentation/ioctl/ioctl-number.txt @@ -224,6 +224,7 @@ Code Seq#(hex) Include File Comments 'f' 00-0F fs/ext4/ext4.h conflict! 'f' 00-0F linux/fs.h conflict! 'f' 00-0F fs/ocfs2/ocfs2_fs.h conflict! +'f' 81-8F linux/fsverity.h 'g' 00-0F linux/usb/gadgetfs.h 'g' 20-2F linux/usb/g_printer.h 'h' 00-7F conflict! Charon filesystem diff --git a/fs/Kconfig b/fs/Kconfig index ac474a61be379..ddadc4e999429 100644 --- a/fs/Kconfig +++ b/fs/Kconfig @@ -105,6 +105,8 @@ config MANDATORY_FILE_LOCKING source "fs/crypto/Kconfig" +source "fs/verity/Kconfig" + source "fs/notify/Kconfig" source "fs/quota/Kconfig" diff --git a/fs/Makefile b/fs/Makefile index 293733f61594b..10b37f651ffde 100644 --- a/fs/Makefile +++ b/fs/Makefile @@ -32,6 +32,7 @@ obj-$(CONFIG_USERFAULTFD) += userfaultfd.o obj-$(CONFIG_AIO) += aio.o obj-$(CONFIG_FS_DAX) += dax.o obj-$(CONFIG_FS_ENCRYPTION) += crypto/ +obj-$(CONFIG_FS_VERITY) += verity/ obj-$(CONFIG_FILE_LOCKING) += locks.o obj-$(CONFIG_COMPAT) += compat.o compat_ioctl.o obj-$(CONFIG_BINFMT_AOUT) += binfmt_aout.o diff --git a/fs/verity/Kconfig b/fs/verity/Kconfig new file mode 100644 index 0000000000000..102c46ebe275f --- /dev/null +++ b/fs/verity/Kconfig @@ -0,0 +1,35 @@ +config FS_VERITY + tristate "FS Verity (read-only file-based authenticity protection)" + select CRYPTO + # SHA-256 is selected as it's intended to be the default hash algorithm. + # To avoid bloat, other wanted algorithms must be selected explicitly. + select CRYPTO_SHA256 + help + This option enables fs-verity. fs-verity is the dm-verity + mechanism implemented at the file level. On supported + filesystems, userspace can append a Merkle tree (hash tree) to + a file, then enable fs-verity on the file. The filesystem + will then transparently verify any data read from the file + against the Merkle tree. The file is also made read-only. + + This serves as an integrity check, but the availability of the + Merkle tree root hash also allows efficiently supporting + various use cases where normally the whole file would need to + be hashed at once, such as: (a) auditing (logging the file's + hash), or (b) authenticity verification (comparing the hash + against a known good value, e.g. from a digital signature). + + fs-verity is especially useful on large files where not all + the contents may actually be needed. Also, fs-verity verifies + data each time it is paged back in, which provides better + protection against malicious disks vs. an ahead-of-time hash. + + If unsure, say N. + +config FS_VERITY_DEBUG + bool "FS Verity debugging" + depends on FS_VERITY + help + Enable debugging messages related to fs-verity by default. + + Say N unless you are an fs-verity developer. diff --git a/fs/verity/Makefile b/fs/verity/Makefile new file mode 100644 index 0000000000000..39e123805c827 --- /dev/null +++ b/fs/verity/Makefile @@ -0,0 +1,3 @@ +obj-$(CONFIG_FS_VERITY) += fsverity.o + +fsverity-y := hash_algs.o setup.o diff --git a/fs/verity/fsverity_private.h b/fs/verity/fsverity_private.h new file mode 100644 index 0000000000000..acc29825a0ed7 --- /dev/null +++ b/fs/verity/fsverity_private.h @@ -0,0 +1,98 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * fs-verity: read-only file-based authenticity protection + * + * Copyright 2018 Google LLC + */ + +#ifndef _FSVERITY_PRIVATE_H +#define _FSVERITY_PRIVATE_H + +#ifdef CONFIG_FS_VERITY_DEBUG +#define DEBUG +#endif + +#define pr_fmt(fmt) "fs-verity: " fmt + +#include +#define __FS_HAS_VERITY 1 +#include + +/* + * Maximum depth of the Merkle tree. Up to 64 levels are theoretically possible + * with a very small block size, but we'd like to limit stack usage during + * verification, and in practice this is plenty. E.g., with SHA-256 and 4K + * blocks, a file with size UINT64_MAX bytes needs just 8 levels. + */ +#define FS_VERITY_MAX_LEVELS 16 + +/* + * Largest digest size among all hash algorithms supported by fs-verity. This + * can be increased if needed. + */ +#define FS_VERITY_MAX_DIGEST_SIZE SHA256_DIGEST_SIZE + +/* A hash algorithm supported by fs-verity */ +struct fsverity_hash_alg { + struct crypto_ahash *tfm; /* allocated on demand */ + const char *name; + unsigned int digest_size; + bool cryptographic; +}; + +/** + * fsverity_info - cached verity metadata for an inode + * + * When a verity file is first opened, an instance of this struct is allocated + * and stored in ->i_verity_info. It caches various values from the verity + * metadata, such as the tree topology and the root hash, which are needed to + * efficiently verify data read from the file. Once created, it remains until + * the inode is evicted. + * + * (The tree pages themselves are not cached here, though they may be cached in + * the inode's page cache.) + */ +struct fsverity_info { + const struct fsverity_hash_alg *hash_alg; /* hash algorithm */ + u8 block_bits; /* log2(block size) */ + u8 log_arity; /* log2(hashes per hash block) */ + u8 depth; /* num levels in the Merkle tree */ + u8 *hashstate; /* salted initial hash state */ + loff_t data_i_size; /* original file size */ + loff_t metadata_end; /* offset to end of verity metadata */ + u8 root_hash[FS_VERITY_MAX_DIGEST_SIZE]; /* Merkle tree root hash */ + u8 measurement[FS_VERITY_MAX_DIGEST_SIZE]; /* file measurement */ + bool have_root_hash; /* have root hash from disk? */ + + /* Starting blocks for each tree level. 'depth-1' is the root level. */ + u64 hash_lvl_region_idx[FS_VERITY_MAX_LEVELS]; +}; + +/* hash_algs.c */ +extern struct fsverity_hash_alg fsverity_hash_algs[]; +const struct fsverity_hash_alg *fsverity_get_hash_alg(unsigned int num); +void __init fsverity_check_hash_algs(void); +void __exit fsverity_exit_hash_algs(void); + +/* setup.c */ +struct page *fsverity_read_metadata_page(struct inode *inode, pgoff_t index); +struct fsverity_info *create_fsverity_info(struct inode *inode, bool enabling); +void free_fsverity_info(struct fsverity_info *vi); + +static inline struct fsverity_info *get_fsverity_info(const struct inode *inode) +{ + /* pairs with cmpxchg_release() in set_fsverity_info() */ + return smp_load_acquire(&inode->i_verity_info); +} + +static inline bool set_fsverity_info(struct inode *inode, + struct fsverity_info *vi) +{ + /* Make sure the in-memory i_size is set to the data i_size */ + i_size_write(inode, vi->data_i_size); + + /* pairs with smp_load_acquire() in get_fsverity_info() */ + return cmpxchg_release(&inode->i_verity_info, NULL, vi) == NULL; +} + +#endif /* _FSVERITY_PRIVATE_H */ diff --git a/fs/verity/hash_algs.c b/fs/verity/hash_algs.c new file mode 100644 index 0000000000000..9c19c9553f120 --- /dev/null +++ b/fs/verity/hash_algs.c @@ -0,0 +1,106 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * fs/verity/hash_algs.c: fs-verity hash algorithm management + * + * Copyright 2018 Google LLC + * + * Written by Eric Biggers. + */ + +#include "fsverity_private.h" + +#include + +/* The list of hash algorithms supported by fs-verity */ +struct fsverity_hash_alg fsverity_hash_algs[] = { + [FS_VERITY_ALG_SHA256] = { + .name = "sha256", + .digest_size = 32, + .cryptographic = true, + }, +}; + +/* + * Translate the given fs-verity hash algorithm number into a struct describing + * the algorithm, and ensure it has a hash transform ready to go. The hash + * transforms are allocated on-demand firstly to not waste resources when they + * aren't needed, and secondly because the fs-verity module may be loaded + * earlier than the needed crypto modules. + */ +const struct fsverity_hash_alg *fsverity_get_hash_alg(unsigned int num) +{ + struct fsverity_hash_alg *alg; + struct crypto_ahash *tfm; + int err; + + if (num >= ARRAY_SIZE(fsverity_hash_algs) || + !fsverity_hash_algs[num].digest_size) { + pr_warn("Unknown hash algorithm: %u\n", num); + return ERR_PTR(-EINVAL); + } + alg = &fsverity_hash_algs[num]; +retry: + /* pairs with cmpxchg_release() below */ + tfm = smp_load_acquire(&alg->tfm); + if (tfm) + return alg; + /* + * Using the shash API would make things a bit simpler, but the ahash + * API is preferable as it allows the use of crypto accelerators. + */ + tfm = crypto_alloc_ahash(alg->name, 0, 0); + if (IS_ERR(tfm)) { + if (PTR_ERR(tfm) == -ENOENT) + pr_warn("Algorithm %u (%s) is unavailable\n", + num, alg->name); + else + pr_warn("Error allocating algorithm %u (%s): %ld\n", + num, alg->name, PTR_ERR(tfm)); + return ERR_CAST(tfm); + } + + err = -EINVAL; + if (WARN_ON(alg->digest_size != crypto_ahash_digestsize(tfm))) + goto err_free_tfm; + + pr_info("%s using implementation \"%s\"\n", alg->name, + crypto_hash_alg_common(tfm)->base.cra_driver_name); + + /* pairs with smp_load_acquire() above */ + if (cmpxchg_release(&alg->tfm, NULL, tfm) != NULL) { + crypto_free_ahash(tfm); + goto retry; + } + + return alg; + +err_free_tfm: + crypto_free_ahash(tfm); + return ERR_PTR(err); +} + +void __init fsverity_check_hash_algs(void) +{ + int i; + + /* + * Sanity check the digest sizes (could be a build-time check, but + * they're in an array) + */ + for (i = 0; i < ARRAY_SIZE(fsverity_hash_algs); i++) { + struct fsverity_hash_alg *alg = &fsverity_hash_algs[i]; + + if (!alg->digest_size) + continue; + BUG_ON(alg->digest_size > FS_VERITY_MAX_DIGEST_SIZE); + BUG_ON(!is_power_of_2(alg->digest_size)); + } +} + +void __exit fsverity_exit_hash_algs(void) +{ + int i; + + for (i = 0; i < ARRAY_SIZE(fsverity_hash_algs); i++) + crypto_free_ahash(fsverity_hash_algs[i].tfm); +} diff --git a/fs/verity/setup.c b/fs/verity/setup.c new file mode 100644 index 0000000000000..925970fbe084d --- /dev/null +++ b/fs/verity/setup.c @@ -0,0 +1,823 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * fs/verity/setup.c: fs-verity module initialization and descriptor parsing + * + * Copyright 2018 Google LLC + * + * Originally written by Jaegeuk Kim and Michael Halcrow; + * heavily rewritten by Eric Biggers. + */ + +#include "fsverity_private.h" + +#include +#include +#include +#include +#include +#include +#include + +static struct kmem_cache *fsverity_info_cachep; + +static void dump_fsverity_descriptor(const struct fsverity_descriptor *desc) +{ + pr_debug("magic = %.*s\n", (int)sizeof(desc->magic), desc->magic); + pr_debug("major_version = %u\n", desc->major_version); + pr_debug("minor_version = %u\n", desc->minor_version); + pr_debug("log_data_blocksize = %u\n", desc->log_data_blocksize); + pr_debug("log_tree_blocksize = %u\n", desc->log_tree_blocksize); + pr_debug("data_algorithm = %u\n", le16_to_cpu(desc->data_algorithm)); + pr_debug("tree_algorithm = %u\n", le16_to_cpu(desc->tree_algorithm)); + pr_debug("flags = %#x\n", le32_to_cpu(desc->flags)); + pr_debug("orig_file_size = %llu\n", le64_to_cpu(desc->orig_file_size)); + pr_debug("auth_ext_count = %u\n", le16_to_cpu(desc->auth_ext_count)); +} + +/* Precompute the salted initial hash state */ +static int set_salt(struct fsverity_info *vi, const u8 *salt, size_t saltlen) +{ + struct crypto_ahash *tfm = vi->hash_alg->tfm; + struct ahash_request *req; + unsigned int reqsize = sizeof(*req) + crypto_ahash_reqsize(tfm); + struct scatterlist sg; + DECLARE_CRYPTO_WAIT(wait); + u8 *saltbuf; + int err; + + vi->hashstate = kmalloc(crypto_ahash_statesize(tfm), GFP_KERNEL); + if (!vi->hashstate) + return -ENOMEM; + /* On error, vi->hashstate is freed by free_fsverity_info() */ + + /* + * Allocate a hash request buffer. Also reserve space for a copy of + * the salt, since the given 'salt' may point into vmap'ed memory, so + * sg_init_one() may not work on it. + */ + req = kmalloc(reqsize + saltlen, GFP_KERNEL); + if (!req) + return -ENOMEM; + saltbuf = (u8 *)req + reqsize; + memcpy(saltbuf, salt, saltlen); + sg_init_one(&sg, saltbuf, saltlen); + + ahash_request_set_tfm(req, tfm); + ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP | + CRYPTO_TFM_REQ_MAY_BACKLOG, + crypto_req_done, &wait); + ahash_request_set_crypt(req, &sg, NULL, saltlen); + + err = crypto_wait_req(crypto_ahash_init(req), &wait); + if (err) + goto out; + err = crypto_wait_req(crypto_ahash_update(req), &wait); + if (err) + goto out; + err = crypto_ahash_export(req, vi->hashstate); +out: + kfree(req); + return err; +} + +/* + * Copy in the root hash stored on disk. + * + * Note that the root hash could be computed by hashing the root block of the + * Merkle tree. But it works out a bit simpler to store the hash separately; + * then it gets included in the file measurement without special-casing it, and + * the root block gets verified on the ->readpages() path like the other blocks. + */ +static int parse_root_hash_extension(struct fsverity_info *vi, + const void *hash, size_t size) +{ + const struct fsverity_hash_alg *alg = vi->hash_alg; + + if (vi->have_root_hash) { + pr_warn("Multiple root hashes were found!\n"); + return -EINVAL; + } + if (size != alg->digest_size) { + pr_warn("Wrong root hash size; got %zu bytes, but expected %u for hash algorithm %s\n", + size, alg->digest_size, alg->name); + return -EINVAL; + } + memcpy(vi->root_hash, hash, size); + vi->have_root_hash = true; + pr_debug("Root hash: %s:%*phN\n", alg->name, + alg->digest_size, vi->root_hash); + return 0; +} + +static int parse_salt_extension(struct fsverity_info *vi, + const void *salt, size_t saltlen) +{ + if (vi->hashstate) { + pr_warn("Multiple salts were found!\n"); + return -EINVAL; + } + return set_salt(vi, salt, saltlen); +} + +/* The available types of extensions (variable-length metadata items) */ +static const struct extension_type { + int (*parse)(struct fsverity_info *vi, const void *_ext, + size_t extra_len); + size_t base_len; /* length of fixed-size part of payload, if any */ + bool unauthenticated; /* true if not included in file measurement */ +} extension_types[] = { + [FS_VERITY_EXT_ROOT_HASH] = { + .parse = parse_root_hash_extension, + }, + [FS_VERITY_EXT_SALT] = { + .parse = parse_salt_extension, + }, +}; + +static int do_parse_extensions(struct fsverity_info *vi, + const struct fsverity_extension **ext_hdr_p, + const void *end, int count, bool authenticated) +{ + const struct fsverity_extension *ext_hdr = *ext_hdr_p; + int i; + int err; + + for (i = 0; i < count; i++) { + const struct extension_type *type; + u32 len, rounded_len; + u16 type_code; + + if (end - (const void *)ext_hdr < sizeof(*ext_hdr)) { + pr_warn("Extension list overflows buffer\n"); + return -EINVAL; + } + type_code = le16_to_cpu(ext_hdr->type); + if (type_code >= ARRAY_SIZE(extension_types) || + !extension_types[type_code].parse) { + pr_warn("Unknown extension type: %u\n", type_code); + return -EINVAL; + } + type = &extension_types[type_code]; + if (authenticated != !type->unauthenticated) { + pr_warn("Extension type %u must be %sauthenticated\n", + type_code, type->unauthenticated ? "un" : ""); + return -EINVAL; + } + if (ext_hdr->reserved) { + pr_warn("Reserved bits set in extension header\n"); + return -EINVAL; + } + len = le32_to_cpu(ext_hdr->length); + if (len < sizeof(*ext_hdr)) { + pr_warn("Invalid length in extension header\n"); + return -EINVAL; + } + rounded_len = round_up(len, 8); + if (rounded_len == 0 || + rounded_len > end - (const void *)ext_hdr) { + pr_warn("Extension item overflows buffer\n"); + return -EINVAL; + } + if (len < sizeof(*ext_hdr) + type->base_len) { + pr_warn("Extension length too small for type\n"); + return -EINVAL; + } + err = type->parse(vi, ext_hdr + 1, + len - sizeof(*ext_hdr) - type->base_len); + if (err) + return err; + ext_hdr = (const void *)ext_hdr + rounded_len; + } + *ext_hdr_p = ext_hdr; + return 0; +} + +/* + * Parse the extension items following the fixed-size portion of the fs-verity + * descriptor. The fsverity_info is updated accordingly. + * + * Return: On success, the size of the authenticated portion of the descriptor + * (the fixed-size portion plus the authenticated extensions). + * Otherwise, a -errno value. + */ +static int parse_extensions(struct fsverity_info *vi, + const struct fsverity_descriptor *desc, + int desc_len) +{ + const struct fsverity_extension *ext_hdr = (const void *)(desc + 1); + const void *end = (const void *)desc + desc_len; + u16 auth_ext_count = le16_to_cpu(desc->auth_ext_count); + int auth_desc_len; + int err; + + /* Authenticated extensions */ + err = do_parse_extensions(vi, &ext_hdr, end, auth_ext_count, true); + if (err) + return err; + auth_desc_len = (void *)ext_hdr - (void *)desc; + + /* + * Unauthenticated extensions (optional). Careful: an attacker able to + * corrupt the file can change these arbitrarily without being detected. + * Thus, only specific types of extensions are whitelisted here -- + * namely, the ones containing a signature of the file measurement, + * which by definition can't be included in the file measurement itself. + */ + if (end - (void *)ext_hdr >= 8) { + u16 unauth_ext_count = le16_to_cpup((__le16 *)ext_hdr); + + ext_hdr = (void *)ext_hdr + 8; + err = do_parse_extensions(vi, &ext_hdr, end, + unauth_ext_count, false); + if (err) + return err; + } + + return auth_desc_len; +} + +/* + * Parse an fs-verity descriptor, loading information into the fsverity_info. + * + * Return: On success, the size of the authenticated portion of the descriptor + * (the fixed-size portion plus the authenticated extensions). + * Otherwise, a -errno value. + */ +static int parse_fsverity_descriptor(struct fsverity_info *vi, + const struct fsverity_descriptor *desc, + int desc_len) +{ + unsigned int alg_num; + unsigned int hashes_per_block; + int desc_auth_len; + int err; + + BUILD_BUG_ON(sizeof(*desc) != 64); + + /* magic */ + if (memcmp(desc->magic, FS_VERITY_MAGIC, sizeof(desc->magic))) { + pr_warn("Wrong magic bytes\n"); + return -EINVAL; + } + + /* major_version */ + if (desc->major_version != 1) { + pr_warn("Unsupported major version (%u)\n", + desc->major_version); + return -EINVAL; + } + + /* minor_version */ + if (desc->minor_version != 0) { + pr_warn("Unsupported minor version (%u)\n", + desc->minor_version); + return -EINVAL; + } + + /* data_algorithm and tree_algorithm */ + alg_num = le16_to_cpu(desc->data_algorithm); + if (alg_num != le16_to_cpu(desc->tree_algorithm)) { + pr_warn("Unimplemented case: data (%u) and tree (%u) hash algorithms differ\n", + alg_num, le16_to_cpu(desc->tree_algorithm)); + return -EINVAL; + } + vi->hash_alg = fsverity_get_hash_alg(alg_num); + if (IS_ERR(vi->hash_alg)) + return PTR_ERR(vi->hash_alg); + + /* log_data_blocksize and log_tree_blocksize */ + if (desc->log_data_blocksize != PAGE_SHIFT) { + pr_warn("Unsupported log_blocksize (%u). Need block_size == PAGE_SIZE.\n", + desc->log_data_blocksize); + return -EINVAL; + } + if (desc->log_tree_blocksize != desc->log_data_blocksize) { + pr_warn("Unimplemented case: data (%u) and tree (%u) block sizes differ\n", + desc->log_data_blocksize, desc->log_data_blocksize); + return -EINVAL; + } + vi->block_bits = desc->log_data_blocksize; + hashes_per_block = (1 << vi->block_bits) / vi->hash_alg->digest_size; + if (!is_power_of_2(hashes_per_block)) { + pr_warn("Unimplemented case: hashes per block (%u) isn't a power of 2\n", + hashes_per_block); + return -EINVAL; + } + vi->log_arity = ilog2(hashes_per_block); + + /* flags */ + if (desc->flags) { + pr_warn("Unsupported flags (%#x)\n", le32_to_cpu(desc->flags)); + return -EINVAL; + } + + /* reserved fields */ + if (desc->reserved1 || + memchr_inv(desc->reserved2, 0, sizeof(desc->reserved2))) { + pr_warn("Reserved bits set in fsverity_descriptor\n"); + return -EINVAL; + } + + /* orig_file_size */ + vi->data_i_size = le64_to_cpu(desc->orig_file_size); + if (vi->data_i_size <= 0) { + pr_warn("Original file size is 0 or negative; this is unsupported\n"); + return -EINVAL; + } + + /* extensions */ + desc_auth_len = parse_extensions(vi, desc, desc_len); + if (desc_auth_len < 0) + return desc_auth_len; + + if (!vi->have_root_hash) { + pr_warn("Root hash wasn't found!\n"); + return -EINVAL; + } + + /* Use an empty salt if no salt was found in the extensions list */ + if (!vi->hashstate) { + err = set_salt(vi, "", 0); + if (err) + return err; + } + + return desc_auth_len; +} + +/* + * Calculate the depth of the Merkle tree, then create a map from level to the + * block offset at which that level's hash blocks start. Level 'depth - 1' is + * the root and is stored first. Level 0 is the level directly "above" the data + * blocks and is stored last, just before the fsverity_descriptor. + */ +static int compute_tree_depth_and_offsets(struct fsverity_info *vi) +{ + unsigned int hashes_per_block = 1 << vi->log_arity; + u64 blocks = ((u64)vi->data_i_size + (1 << vi->block_bits) - 1) >> + vi->block_bits; + u64 offset = blocks; /* assuming Merkle tree past EOF */ + int depth = 0; + int i; + + while (blocks > 1) { + if (depth >= FS_VERITY_MAX_LEVELS) { + pr_warn("Too many tree levels (max is %d)\n", + FS_VERITY_MAX_LEVELS); + return -EINVAL; + } + blocks = (blocks + hashes_per_block - 1) >> vi->log_arity; + vi->hash_lvl_region_idx[depth++] = blocks; + } + vi->depth = depth; + + for (i = depth - 1; i >= 0; i--) { + u64 next_count = vi->hash_lvl_region_idx[i]; + + vi->hash_lvl_region_idx[i] = offset; + pr_debug("Level %d is [%llu..%llu] (%llu blocks)\n", + i, offset, offset + next_count - 1, next_count); + offset += next_count; + } + return 0; +} + +/* Arbitrary limit, can be increased if needed */ +#define MAX_DESCRIPTOR_PAGES 16 + +/* + * Compute the file's measurement by hashing the first 'desc_auth_len' bytes of + * the fs-verity descriptor (which includes the Merkle tree root hash as an + * authenticated extension item). + * + * Note: 'desc' may point into vmap'ed memory, so it can't be passed directly to + * sg_set_buf() for the ahash API. Instead, we pass the pages directly. + */ +static int compute_measurement(const struct fsverity_info *vi, + const struct fsverity_descriptor *desc, + int desc_auth_len, + struct page *desc_pages[MAX_DESCRIPTOR_PAGES], + int nr_desc_pages, u8 *measurement) +{ + struct ahash_request *req; + DECLARE_CRYPTO_WAIT(wait); + struct scatterlist sg[MAX_DESCRIPTOR_PAGES]; + int offset, len, remaining; + int i; + int err; + + req = ahash_request_alloc(vi->hash_alg->tfm, GFP_KERNEL); + if (!req) + return -ENOMEM; + + sg_init_table(sg, nr_desc_pages); + offset = offset_in_page(desc); + remaining = desc_auth_len; + for (i = 0; i < nr_desc_pages && remaining; i++) { + len = min_t(int, PAGE_SIZE - offset, remaining); + sg_set_page(&sg[i], desc_pages[i], len, offset); + remaining -= len; + offset = 0; + } + + ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP | + CRYPTO_TFM_REQ_MAY_BACKLOG, + crypto_req_done, &wait); + ahash_request_set_crypt(req, sg, measurement, desc_auth_len); + err = crypto_wait_req(crypto_ahash_digest(req), &wait); + ahash_request_free(req); + return err; +} + +static struct fsverity_info *alloc_fsverity_info(void) +{ + return kmem_cache_zalloc(fsverity_info_cachep, GFP_NOFS); +} + +void free_fsverity_info(struct fsverity_info *vi) +{ + if (!vi) + return; + kfree(vi->hashstate); + kmem_cache_free(fsverity_info_cachep, vi); +} + +/** + * find_fsverity_footer - find the fsverity_footer in the last page of metadata + * + * Allow the fs-verity footer to be padded with zeroes. This is needed by ext4, + * which stores the fs-verity metadata beyond EOF but sets i_size = data_i_size. + * Then, the fs-verity footer must be found implicitly via the last extent. + * + * Return: pointer to the footer if found, else NULL + */ +static const struct fsverity_footer * +find_fsverity_footer(const u8 *last_virt, size_t last_validsize) +{ + const u8 *p = last_virt + last_validsize; + const struct fsverity_footer *ftr; + + /* Find the last nonzero byte, which should be ftr->magic[7] */ + do { + if (p <= last_virt) + return NULL; + } while (*--p == 0); + + BUILD_BUG_ON(sizeof(ftr->magic) != 8); + BUILD_BUG_ON(offsetof(struct fsverity_footer, magic[8]) != + sizeof(*ftr)); + if (p - last_virt < offsetof(struct fsverity_footer, magic[7])) + return NULL; + ftr = container_of(p, struct fsverity_footer, magic[7]); + if (memcmp(ftr->magic, FS_VERITY_MAGIC, sizeof(ftr->magic))) + return NULL; + return ftr; +} + +struct page *fsverity_read_metadata_page(struct inode *inode, pgoff_t index) +{ + /* + * For now we assume that the verity metadata is stored in the same data + * stream as the actual file contents (as ext4 and f2fs do), so we read + * the metadata directly from the inode's page cache. If any + * filesystems need to do things differently, this should be replaced + * with a method fsverity_operations.read_metadata_page(). + */ + return read_mapping_page(inode->i_mapping, index, NULL); +} + +/** + * map_fsverity_descriptor - map an inode's fs-verity descriptor into memory + * + * If the descriptor fits in one page, we use kmap; otherwise we use vmap. + * unmap_fsverity_descriptor() must be called later to unmap it. + * + * It's assumed that the file contents cannot be modified concurrently. + * (This is guaranteed by either deny_write_access() or by the verity bit.) + * + * Return: the virtual address of the start of the descriptor, in virtually + * contiguous memory. Also fills in desc_pages and returns in *desc_len the + * length of the descriptor including all extensions, and in *desc_start the + * offset of the descriptor from the start of the file, in bytes. + */ +static const struct fsverity_descriptor * +map_fsverity_descriptor(struct inode *inode, loff_t metadata_end, + struct page *desc_pages[MAX_DESCRIPTOR_PAGES], + int *nr_desc_pages, int *desc_len, loff_t *desc_start) +{ + const int last_validsize = ((metadata_end - 1) & ~PAGE_MASK) + 1; + const pgoff_t last_pgoff = (metadata_end - 1) >> PAGE_SHIFT; + struct page *last_page; + const void *last_virt; + const struct fsverity_footer *ftr; + pgoff_t first_pgoff; + u32 desc_reverse_offset; + pgoff_t pgoff; + const void *desc_virt; + int i; + int err; + + *nr_desc_pages = 0; + *desc_len = 0; + *desc_start = 0; + + last_page = fsverity_read_metadata_page(inode, last_pgoff); + if (IS_ERR(last_page)) { + pr_warn("Error reading last page: %ld\n", PTR_ERR(last_page)); + return ERR_CAST(last_page); + } + last_virt = kmap(last_page); + + ftr = find_fsverity_footer(last_virt, last_validsize); + if (!ftr) { + pr_warn("No verity metadata found\n"); + err = -EINVAL; + goto err_out; + } + metadata_end -= (last_virt + last_validsize - sizeof(*ftr)) - + (void *)ftr; + + desc_reverse_offset = le32_to_cpu(ftr->desc_reverse_offset); + if (desc_reverse_offset < + sizeof(struct fsverity_descriptor) + sizeof(*ftr) || + desc_reverse_offset > metadata_end) { + pr_warn("Unexpected desc_reverse_offset: %u\n", + desc_reverse_offset); + err = -EINVAL; + goto err_out; + } + *desc_start = metadata_end - desc_reverse_offset; + if (*desc_start & 7) { + pr_warn("fs-verity descriptor is misaligned (desc_start=%lld)\n", + *desc_start); + err = -EINVAL; + goto err_out; + } + + first_pgoff = *desc_start >> PAGE_SHIFT; + if (last_pgoff - first_pgoff >= MAX_DESCRIPTOR_PAGES) { + pr_warn("fs-verity descriptor is too long (%lu pages)\n", + last_pgoff - first_pgoff + 1); + err = -EINVAL; + goto err_out; + } + + *desc_len = desc_reverse_offset - sizeof(__le32); + + if (first_pgoff == last_pgoff) { + /* Single-page descriptor; use the already-kmapped last page */ + desc_pages[0] = last_page; + *nr_desc_pages = 1; + return last_virt + (*desc_start & ~PAGE_MASK); + } + + /* Multi-page descriptor; map the additional pages into memory */ + + for (pgoff = first_pgoff; pgoff < last_pgoff; pgoff++) { + struct page *page; + + page = fsverity_read_metadata_page(inode, pgoff); + if (IS_ERR(page)) { + err = PTR_ERR(page); + pr_warn("Error reading descriptor page: %d\n", err); + goto err_out; + } + desc_pages[(*nr_desc_pages)++] = page; + } + + desc_pages[(*nr_desc_pages)++] = last_page; + kunmap(last_page); + last_page = NULL; + + desc_virt = vmap(desc_pages, *nr_desc_pages, VM_MAP, PAGE_KERNEL_RO); + if (!desc_virt) { + err = -ENOMEM; + goto err_out; + } + + return desc_virt + (*desc_start & ~PAGE_MASK); + +err_out: + for (i = 0; i < *nr_desc_pages; i++) + put_page(desc_pages[i]); + if (last_page) { + kunmap(last_page); + put_page(last_page); + } + return ERR_PTR(err); +} + +static void +unmap_fsverity_descriptor(const struct fsverity_descriptor *desc, + struct page *desc_pages[MAX_DESCRIPTOR_PAGES], + int nr_desc_pages) +{ + int i; + + if (is_vmalloc_addr(desc)) { + vunmap((void *)((unsigned long)desc & PAGE_MASK)); + } else { + WARN_ON(nr_desc_pages != 1); + kunmap(desc_pages[0]); + } + for (i = 0; i < nr_desc_pages; i++) + put_page(desc_pages[i]); +} + +/* Read the file's fs-verity descriptor and create an fsverity_info for it */ +struct fsverity_info *create_fsverity_info(struct inode *inode, bool enabling) +{ + struct fsverity_info *vi; + const struct fsverity_descriptor *desc = NULL; + struct page *desc_pages[MAX_DESCRIPTOR_PAGES]; + int nr_desc_pages; + int desc_len; + loff_t desc_start; + int desc_auth_len; + int err; + + vi = alloc_fsverity_info(); + if (!vi) + return ERR_PTR(-ENOMEM); + + if (enabling) { + /* file is in fsveritysetup format */ + vi->metadata_end = i_size_read(inode); + } else { + /* verity metadata may be in a filesystem-specific location */ + err = inode->i_sb->s_vop->get_metadata_end(inode, + &vi->metadata_end); + if (err) + goto out; + } + + desc = map_fsverity_descriptor(inode, vi->metadata_end, desc_pages, + &nr_desc_pages, &desc_len, &desc_start); + if (IS_ERR(desc)) { + err = PTR_ERR(desc); + desc = NULL; + goto out; + } + + dump_fsverity_descriptor(desc); + desc_auth_len = parse_fsverity_descriptor(vi, desc, desc_len); + if (desc_auth_len < 0) { + err = desc_auth_len; + goto out; + } + if (vi->data_i_size > i_size_read(inode)) { + pr_warn("Bad data_i_size: %llu\n", vi->data_i_size); + err = -EINVAL; + goto out; + } + + err = compute_tree_depth_and_offsets(vi); + if (err) + goto out; + err = compute_measurement(vi, desc, desc_auth_len, desc_pages, + nr_desc_pages, vi->measurement); +out: + if (desc) + unmap_fsverity_descriptor(desc, desc_pages, nr_desc_pages); + if (err) { + free_fsverity_info(vi); + vi = ERR_PTR(err); + } + return vi; +} + +/* Ensure the inode has an ->i_verity_info */ +static int setup_fsverity_info(struct inode *inode) +{ + struct fsverity_info *vi = get_fsverity_info(inode); + + if (vi) + return 0; + + vi = create_fsverity_info(inode, false); + if (IS_ERR(vi)) + return PTR_ERR(vi); + + if (!set_fsverity_info(inode, vi)) + free_fsverity_info(vi); + return 0; +} + +/** + * fsverity_file_open - prepare to open a verity file + * @inode: the inode being opened + * @filp: the struct file being set up + * + * When opening a verity file, deny the open if it is for writing. Otherwise, + * set up the inode's ->i_verity_info (if not already done) by parsing the + * verity metadata at the end of the file. + * + * When combined with fscrypt, this must be called after fscrypt_file_open(). + * Otherwise, we won't have the key set up to decrypt the verity metadata. + * + * Return: 0 on success, -errno on failure + */ +int fsverity_file_open(struct inode *inode, struct file *filp) +{ + if (filp->f_mode & FMODE_WRITE) { + pr_debug("Denying opening verity file (ino %lu) for write\n", + inode->i_ino); + return -EPERM; + } + + return setup_fsverity_info(inode); +} +EXPORT_SYMBOL_GPL(fsverity_file_open); + +/** + * fsverity_prepare_setattr - prepare to change a verity inode's attributes + * @dentry: dentry through which the inode is being changed + * @attr: attributes to change + * + * Verity files are immutable, so deny truncates. This isn't covered by the + * open-time check because sys_truncate() takes a path, not a file descriptor. + * + * Return: 0 on success, -errno on failure + */ +int fsverity_prepare_setattr(struct dentry *dentry, struct iattr *attr) +{ + if (attr->ia_valid & ATTR_SIZE) { + pr_debug("Denying truncate of verity file (ino %lu)\n", + d_inode(dentry)->i_ino); + return -EPERM; + } + return 0; +} +EXPORT_SYMBOL_GPL(fsverity_prepare_setattr); + +/** + * fsverity_prepare_getattr - prepare to get a verity inode's attributes + * @inode: the inode for which the attributes are being retrieved + * + * This only needs to be called by filesystems that set the on-disk i_size of + * verity files to something other than the data size, as then this is needed to + * override i_size so that stat() shows the correct size. + * + * When the filesystem supports fscrypt too, it must make sure to set up the + * inode's encryption key (if needed) before calling this. + * + * Return: 0 on success, -errno on failure + */ +int fsverity_prepare_getattr(struct inode *inode) +{ + return setup_fsverity_info(inode); +} +EXPORT_SYMBOL_GPL(fsverity_prepare_getattr); + +/** + * fsverity_cleanup_inode - free the inode's verity info, if present + * + * Filesystems must call this on inode eviction to free ->i_verity_info. + */ +void fsverity_cleanup_inode(struct inode *inode) +{ + free_fsverity_info(inode->i_verity_info); + inode->i_verity_info = NULL; +} +EXPORT_SYMBOL_GPL(fsverity_cleanup_inode); + +/** + * fsverity_full_i_size - get the full file size + * + * If the file has fs-verity set up, return the full file size including the + * verity metadata. Otherwise just return i_size. This is only meaningful when + * the filesystem stores the verity metadata past EOF. + */ +loff_t fsverity_full_i_size(const struct inode *inode) +{ + struct fsverity_info *vi = get_fsverity_info(inode); + + if (vi) + return vi->metadata_end; + + return i_size_read(inode); +} +EXPORT_SYMBOL_GPL(fsverity_full_i_size); + +static int __init fsverity_module_init(void) +{ + fsverity_info_cachep = KMEM_CACHE(fsverity_info, SLAB_RECLAIM_ACCOUNT); + if (!fsverity_info_cachep) + return -ENOMEM; + + fsverity_check_hash_algs(); + + pr_debug("Initialized fs-verity\n"); + return 0; +} + +static void __exit fsverity_module_exit(void) +{ + kmem_cache_destroy(fsverity_info_cachep); + fsverity_exit_hash_algs(); +} + +module_init(fsverity_module_init) +module_exit(fsverity_module_exit); +MODULE_LICENSE("GPL v2"); +MODULE_DESCRIPTION("fs-verity: read-only file-based authenticity protection"); diff --git a/include/linux/fs.h b/include/linux/fs.h index 8252df30b9a16..bcfc400627574 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -61,6 +61,8 @@ struct workqueue_struct; struct iov_iter; struct fscrypt_info; struct fscrypt_operations; +struct fsverity_info; +struct fsverity_operations; extern void __init inode_init(void); extern void __init inode_init_early(void); @@ -702,6 +704,10 @@ struct inode { struct fscrypt_info *i_crypt_info; #endif +#if IS_ENABLED(CONFIG_FS_VERITY) + struct fsverity_info *i_verity_info; +#endif + void *i_private; /* fs or device private pointer */ } __randomize_layout; @@ -1400,6 +1406,9 @@ struct super_block { const struct xattr_handler **s_xattr; #if IS_ENABLED(CONFIG_FS_ENCRYPTION) const struct fscrypt_operations *s_cop; +#endif +#if IS_ENABLED(CONFIG_FS_VERITY) + const struct fsverity_operations *s_vop; #endif struct hlist_bl_head s_roots; /* alternate root dentries for NFS */ struct list_head s_mounts; /* list of mounts; _not_ for fs use */ diff --git a/include/linux/fsverity.h b/include/linux/fsverity.h new file mode 100644 index 0000000000000..c9422a579c160 --- /dev/null +++ b/include/linux/fsverity.h @@ -0,0 +1,62 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * fs-verity: read-only file-based authenticity protection + * + * Copyright 2018 Google LLC + */ + +#ifndef _LINUX_FSVERITY_H +#define _LINUX_FSVERITY_H + +#include +#include + +/* + * fs-verity operations for filesystems + */ +struct fsverity_operations { + int (*set_verity)(struct inode *inode, loff_t data_i_size); + int (*get_metadata_end)(struct inode *inode, loff_t *metadata_end_ret); +}; + +#if __FS_HAS_VERITY + +/* setup.c */ +extern int fsverity_file_open(struct inode *inode, struct file *filp); +extern int fsverity_prepare_setattr(struct dentry *dentry, struct iattr *attr); +extern int fsverity_prepare_getattr(struct inode *inode); +extern void fsverity_cleanup_inode(struct inode *inode); +extern loff_t fsverity_full_i_size(const struct inode *inode); + +#else /* !__FS_HAS_VERITY */ + +/* setup.c */ + +static inline int fsverity_file_open(struct inode *inode, struct file *filp) +{ + return -EOPNOTSUPP; +} + +static inline int fsverity_prepare_setattr(struct dentry *dentry, + struct iattr *attr) +{ + return -EOPNOTSUPP; +} + +static inline int fsverity_prepare_getattr(struct inode *inode) +{ + return -EOPNOTSUPP; +} + +static inline void fsverity_cleanup_inode(struct inode *inode) +{ +} + +static inline loff_t fsverity_full_i_size(const struct inode *inode) +{ + return i_size_read(inode); +} + +#endif /* !__FS_HAS_VERITY */ + +#endif /* _LINUX_FSVERITY_H */ diff --git a/include/uapi/linux/fsverity.h b/include/uapi/linux/fsverity.h new file mode 100644 index 0000000000000..55b9f32676220 --- /dev/null +++ b/include/uapi/linux/fsverity.h @@ -0,0 +1,86 @@ +/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */ +/* + * fs-verity (file-based verity) support + * + * Copyright (C) 2018 Google LLC + */ +#ifndef _UAPI_LINUX_FSVERITY_H +#define _UAPI_LINUX_FSVERITY_H + +#include +#include +#include + +/* ========== Ioctls ========== */ + +struct fsverity_digest { + __u16 digest_algorithm; + __u16 digest_size; /* input/output */ + __u8 digest[]; +}; + +#define FS_IOC_ENABLE_VERITY _IO('f', 133) +#define FS_IOC_MEASURE_VERITY _IOWR('f', 134, struct fsverity_digest) + +/* ========== On-disk format ========== */ + +#define FS_VERITY_MAGIC "FSVerity" + +/* Supported hash algorithms */ +#define FS_VERITY_ALG_SHA256 1 + +/* Metadata stored near the end of verity files, after the Merkle tree */ +/* This structure is 64 bytes long */ +struct fsverity_descriptor { + __u8 magic[8]; /* must be FS_VERITY_MAGIC */ + __u8 major_version; /* must be 1 */ + __u8 minor_version; /* must be 0 */ + __u8 log_data_blocksize;/* log2(data-bytes-per-hash), e.g. 12 for 4KB */ + __u8 log_tree_blocksize;/* log2(tree-bytes-per-hash), e.g. 12 for 4KB */ + __le16 data_algorithm; /* hash algorithm for data blocks */ + __le16 tree_algorithm; /* hash algorithm for tree blocks */ + __le32 flags; /* flags */ + __le32 reserved1; /* must be 0 */ + __le64 orig_file_size; /* size of the original file data */ + __le16 auth_ext_count; /* number of authenticated extensions */ + __u8 reserved2[30]; /* must be 0 */ +}; +/* followed by list of 'auth_ext_count' authenticated extensions */ +/* + * then followed by '__le16 unauth_ext_count' padded to next 8-byte boundary, + * then a list of 'unauth_ext_count' (may be 0) unauthenticated extensions + */ + +/* Extension types */ +#define FS_VERITY_EXT_ROOT_HASH 1 +#define FS_VERITY_EXT_SALT 2 + +/* Header of each extension (variable-length metadata item) */ +struct fsverity_extension { + /* + * Length in bytes, including this header but excluding padding to next + * 8-byte boundary that is applied when advancing to the next extension. + */ + __le32 length; + __le16 type; /* Type of this extension (see codes above) */ + __le16 reserved; /* Reserved, must be 0 */ +}; +/* followed by the payload of 'length - 8' bytes */ + +/* Extension payload formats */ + +/* + * FS_VERITY_EXT_ROOT_HASH payload is just a byte array, with size equal to the + * digest size of the hash algorithm given in the fsverity_descriptor + */ + +/* FS_VERITY_EXT_SALT payload is just a byte array, any size */ + + +/* Fields stored at the very end of the file */ +struct fsverity_footer { + __le32 desc_reverse_offset; /* distance to fsverity_descriptor */ + __u8 magic[8]; /* FS_VERITY_MAGIC */ +} __packed; + +#endif /* _UAPI_LINUX_FSVERITY_H */ From patchwork Thu Nov 1 22:52:21 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Eric Biggers X-Patchwork-Id: 10664575 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id F311C157A for ; Thu, 1 Nov 2018 22:54:18 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id D188C2B5FE for ; Thu, 1 Nov 2018 22:54:18 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id C34552BFF2; Thu, 1 Nov 2018 22:54:18 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.0 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 30BD02B5FE for ; Thu, 1 Nov 2018 22:54:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728065AbeKBH7P (ORCPT ); Fri, 2 Nov 2018 03:59:15 -0400 Received: from mail.kernel.org ([198.145.29.99]:52120 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728026AbeKBH7P (ORCPT ); Fri, 2 Nov 2018 03:59:15 -0400 Received: from ebiggers-linuxstation.kir.corp.google.com (unknown [104.132.51.88]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 9A71F20843; Thu, 1 Nov 2018 22:54:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1541112856; bh=5dFvn0a0cZzK4zkgBvSDnx756GXifXzBj9YpcPwAp1U=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=cCkFb2KNpSVaGURe7suITelAU3hJT1U5Ep1+KZaEW34rAzeumWJGw9eR5ssIYFGMW TmANFxPDbD8k8bJDIRkdZ5jSwIzQgsFvEJEUCZXGfzrtHjzBu1NN+3q/QImforISq8 htCpJGN28CBK0c0aqUSwosVC5ooTpw/ou0ovVAjE= From: Eric Biggers To: linux-fscrypt@vger.kernel.org Cc: linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-integrity@vger.kernel.org, linux-kernel@vger.kernel.org, "Theodore Y . Ts'o" , Jaegeuk Kim , Victor Hsieh , Chandan Rajendra Subject: [PATCH v2 03/12] fs-verity: add MAINTAINERS file entry Date: Thu, 1 Nov 2018 15:52:21 -0700 Message-Id: <20181101225230.88058-4-ebiggers@kernel.org> X-Mailer: git-send-email 2.19.1.568.g152ad8e336-goog In-Reply-To: <20181101225230.88058-1-ebiggers@kernel.org> References: <20181101225230.88058-1-ebiggers@kernel.org> MIME-Version: 1.0 Sender: linux-fscrypt-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fscrypt@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Eric Biggers I'm volunteering to maintain fs-verity. It's been suggested to take fs-verity changes through the fscrypt git tree, but as these are logically independent features I suggest having a separate git tree for fs-verity. But I left the mailing list as linux-fscrypt for now. Signed-off-by: Eric Biggers --- MAINTAINERS | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/MAINTAINERS b/MAINTAINERS index 690c2f68a401f..72fef7c44bfba 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -6052,6 +6052,17 @@ S: Maintained F: fs/notify/ F: include/linux/fsnotify*.h +FSVERITY: READ-ONLY FILE-BASED AUTHENTICITY PROTECTION +M: Eric Biggers +L: linux-fscrypt@vger.kernel.org +Q: https://patchwork.kernel.org/project/linux-fscrypt/list/ +T: git git://git.kernel.org/pub/scm/linux/kernel/git/ebiggers/fsverity.git +S: Supported +F: fs/verity/ +F: include/linux/fsverity.h +F: include/uapi/linux/fsverity.h +F: Documentation/filesystems/fsverity.rst + FUJITSU LAPTOP EXTRAS M: Jonathan Woithe L: platform-driver-x86@vger.kernel.org From patchwork Thu Nov 1 22:52:22 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Eric Biggers X-Patchwork-Id: 10664649 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id E682C17DB for ; Thu, 1 Nov 2018 22:55:53 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id DA57A2C104 for ; Thu, 1 Nov 2018 22:55:53 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id CE62E2C48C; Thu, 1 Nov 2018 22:55:53 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.0 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id F101C2C104 for ; Thu, 1 Nov 2018 22:55:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727802AbeKBIAn (ORCPT ); Fri, 2 Nov 2018 04:00:43 -0400 Received: from mail.kernel.org ([198.145.29.99]:52130 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728027AbeKBH7Q (ORCPT ); Fri, 2 Nov 2018 03:59:16 -0400 Received: from ebiggers-linuxstation.kir.corp.google.com (unknown [104.132.51.88]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id C541A20848; Thu, 1 Nov 2018 22:54:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1541112856; bh=W1m7Bgf2hZhfyKrMZQZ7gDJSPg/+1UByIHYrJNU12ko=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=fV8WOVrgXmwhyMdb/JcLlyTnDoWB74jt3NMy2GPELFyCzDEh5kDUeCvfz2YtPIQGm KCy8017oCHYdVSZAIwuutAt6o2IvYgBWujD/+Wye7il4zlCJo0vLtfEV5Ms8lLLLcf u2UOtaQRh2MZL1Kvfb7NnWqKNoDPjHR2nsL3jq88= From: Eric Biggers To: linux-fscrypt@vger.kernel.org Cc: linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-integrity@vger.kernel.org, linux-kernel@vger.kernel.org, "Theodore Y . Ts'o" , Jaegeuk Kim , Victor Hsieh , Chandan Rajendra Subject: [PATCH v2 04/12] fs-verity: add data verification hooks for ->readpages() Date: Thu, 1 Nov 2018 15:52:22 -0700 Message-Id: <20181101225230.88058-5-ebiggers@kernel.org> X-Mailer: git-send-email 2.19.1.568.g152ad8e336-goog In-Reply-To: <20181101225230.88058-1-ebiggers@kernel.org> References: <20181101225230.88058-1-ebiggers@kernel.org> MIME-Version: 1.0 Sender: linux-fscrypt-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fscrypt@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Eric Biggers Add functions that verify data pages that have been read from a fs-verity file, against that file's Merkle tree. These will be called from filesystems' ->readpage() and ->readpages() methods. Since data verification can block, a workqueue is provided for these methods to enqueue verification work from their bio completion callback. Signed-off-by: Eric Biggers --- fs/verity/Makefile | 2 +- fs/verity/fsverity_private.h | 3 + fs/verity/setup.c | 26 ++- fs/verity/verify.c | 298 +++++++++++++++++++++++++++++++++++ include/linux/fsverity.h | 33 ++++ 5 files changed, 360 insertions(+), 2 deletions(-) create mode 100644 fs/verity/verify.c diff --git a/fs/verity/Makefile b/fs/verity/Makefile index 39e123805c827..a6c7cefb61ab7 100644 --- a/fs/verity/Makefile +++ b/fs/verity/Makefile @@ -1,3 +1,3 @@ obj-$(CONFIG_FS_VERITY) += fsverity.o -fsverity-y := hash_algs.o setup.o +fsverity-y := hash_algs.o setup.o verify.o diff --git a/fs/verity/fsverity_private.h b/fs/verity/fsverity_private.h index acc29825a0ed7..dfdbac3874d74 100644 --- a/fs/verity/fsverity_private.h +++ b/fs/verity/fsverity_private.h @@ -95,4 +95,7 @@ static inline bool set_fsverity_info(struct inode *inode, return cmpxchg_release(&inode->i_verity_info, NULL, vi) == NULL; } +/* verify.c */ +extern struct workqueue_struct *fsverity_read_workqueue; + #endif /* _FSVERITY_PRIVATE_H */ diff --git a/fs/verity/setup.c b/fs/verity/setup.c index 925970fbe084d..184bdc96abe51 100644 --- a/fs/verity/setup.c +++ b/fs/verity/setup.c @@ -801,18 +801,42 @@ EXPORT_SYMBOL_GPL(fsverity_full_i_size); static int __init fsverity_module_init(void) { + int err; + + /* + * Use an unbound workqueue to allow bios to be verified in parallel + * even when they happen to complete on the same CPU. This sacrifices + * locality, but it's worthwhile since hashing is CPU-intensive. + * + * Also use a high-priority workqueue to prioritize verification work, + * which blocks reads from completing, over regular application tasks. + */ + err = -ENOMEM; + fsverity_read_workqueue = alloc_workqueue("fsverity_read_queue", + WQ_UNBOUND | WQ_HIGHPRI, + num_online_cpus()); + if (!fsverity_read_workqueue) + goto error; + + err = -ENOMEM; fsverity_info_cachep = KMEM_CACHE(fsverity_info, SLAB_RECLAIM_ACCOUNT); if (!fsverity_info_cachep) - return -ENOMEM; + goto error_free_workqueue; fsverity_check_hash_algs(); pr_debug("Initialized fs-verity\n"); return 0; + +error_free_workqueue: + destroy_workqueue(fsverity_read_workqueue); +error: + return err; } static void __exit fsverity_module_exit(void) { + destroy_workqueue(fsverity_read_workqueue); kmem_cache_destroy(fsverity_info_cachep); fsverity_exit_hash_algs(); } diff --git a/fs/verity/verify.c b/fs/verity/verify.c new file mode 100644 index 0000000000000..e308f22475e8d --- /dev/null +++ b/fs/verity/verify.c @@ -0,0 +1,298 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * fs/verity/verify.c: fs-verity data verification functions, + * i.e. hooks for ->readpages() + * + * Copyright 2018 Google LLC + * + * Originally written by Jaegeuk Kim and Michael Halcrow; + * heavily rewritten by Eric Biggers. + */ + +#include "fsverity_private.h" + +#include +#include +#include +#include +#include + +struct workqueue_struct *fsverity_read_workqueue; + +/** + * hash_at_level() - compute the location of the block's hash at the given level + * + * @vi: (in) the file's verity info + * @dindex: (in) the index of the data block being verified + * @level: (in) the level of hash we want (0 is leaf level) + * @hindex: (out) the index of the hash block containing the wanted hash + * @hoffset: (out) the byte offset to the wanted hash within the hash block + */ +static void hash_at_level(const struct fsverity_info *vi, pgoff_t dindex, + unsigned int level, pgoff_t *hindex, + unsigned int *hoffset) +{ + pgoff_t position; + + /* Offset of the hash within the level's region, in hashes */ + position = dindex >> (level * vi->log_arity); + + /* Index of the hash block in the tree overall */ + *hindex = vi->hash_lvl_region_idx[level] + (position >> vi->log_arity); + + /* Offset of the wanted hash (in bytes) within the hash block */ + *hoffset = (position & ((1 << vi->log_arity) - 1)) << + (vi->block_bits - vi->log_arity); +} + +/* Extract a hash from a hash page */ +static void extract_hash(struct page *hpage, unsigned int hoffset, + unsigned int hsize, u8 *out) +{ + void *virt = kmap_atomic(hpage); + + memcpy(out, virt + hoffset, hsize); + kunmap_atomic(virt); +} + +static int fsverity_hash_page(const struct fsverity_info *vi, + struct ahash_request *req, + struct page *page, u8 *out) +{ + struct scatterlist sg; + DECLARE_CRYPTO_WAIT(wait); + int err; + + sg_init_table(&sg, 1); + sg_set_page(&sg, page, PAGE_SIZE, 0); + + ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP | + CRYPTO_TFM_REQ_MAY_BACKLOG, + crypto_req_done, &wait); + ahash_request_set_crypt(req, &sg, out, PAGE_SIZE); + + err = crypto_ahash_import(req, vi->hashstate); + if (err) + return err; + + return crypto_wait_req(crypto_ahash_finup(req), &wait); +} + +static inline int compare_hashes(const u8 *want_hash, const u8 *real_hash, + int digest_size, struct inode *inode, + pgoff_t index, int level, const char *algname) +{ + if (memcmp(want_hash, real_hash, digest_size) == 0) + return 0; + + pr_warn_ratelimited("VERIFICATION FAILURE! ino=%lu, index=%lu, level=%d, want_hash=%s:%*phN, real_hash=%s:%*phN\n", + inode->i_ino, index, level, + algname, digest_size, want_hash, + algname, digest_size, real_hash); + return -EBADMSG; +} + +/* + * Verify a single data page against the file's Merkle tree. + * + * In principle, we need to verify the entire path to the root node. But as an + * optimization, we cache the hash pages in the file's page cache, similar to + * data pages. Therefore, we can stop verifying as soon as a verified hash page + * is seen while ascending the tree. + * + * Note that unlike data pages, hash pages are marked Uptodate *before* they are + * verified; instead, the Checked bit is set on hash pages that have been + * verified. Multiple tasks may race to verify a hash page and mark it Checked, + * but it doesn't matter. The use of the Checked bit also implies that the hash + * block size must equal PAGE_SIZE (for now). + */ +static bool verify_page(struct inode *inode, const struct fsverity_info *vi, + struct ahash_request *req, struct page *data_page) +{ + pgoff_t index = data_page->index; + int level = 0; + u8 _want_hash[FS_VERITY_MAX_DIGEST_SIZE]; + const u8 *want_hash = NULL; + u8 real_hash[FS_VERITY_MAX_DIGEST_SIZE]; + struct page *hpages[FS_VERITY_MAX_LEVELS]; + unsigned int hoffsets[FS_VERITY_MAX_LEVELS]; + int err; + + /* The page must not be unlocked until verification has completed. */ + if (WARN_ON_ONCE(!PageLocked(data_page))) + return false; + + /* + * Filesystems shouldn't ask to verify pages beyond the end of the + * original data (e.g. pages of the Merkle tree itself, if it's stored + * beyond EOF), but to be safe check for it here too. + */ + if (index >= (vi->data_i_size + PAGE_SIZE - 1) >> PAGE_SHIFT) { + pr_debug("Page %lu is beyond data region\n", index); + return true; + } + + pr_debug_ratelimited("Verifying data page %lu...\n", index); + + /* + * Starting at the leaves, ascend the tree saving hash pages along the + * way until we find a verified hash page, indicated by PageChecked; or + * until we reach the root. + */ + for (level = 0; level < vi->depth; level++) { + pgoff_t hindex; + unsigned int hoffset; + struct page *hpage; + + hash_at_level(vi, index, level, &hindex, &hoffset); + + pr_debug_ratelimited("Level %d: hindex=%lu, hoffset=%u\n", + level, hindex, hoffset); + + hpage = fsverity_read_metadata_page(inode, hindex); + if (IS_ERR(hpage)) { + err = PTR_ERR(hpage); + goto out; + } + + if (PageChecked(hpage)) { + extract_hash(hpage, hoffset, vi->hash_alg->digest_size, + _want_hash); + want_hash = _want_hash; + put_page(hpage); + pr_debug_ratelimited("Hash page already checked, want %s:%*phN\n", + vi->hash_alg->name, + vi->hash_alg->digest_size, + want_hash); + break; + } + pr_debug_ratelimited("Hash page not yet checked\n"); + hpages[level] = hpage; + hoffsets[level] = hoffset; + } + + if (!want_hash) { + want_hash = vi->root_hash; + pr_debug("Want root hash: %s:%*phN\n", vi->hash_alg->name, + vi->hash_alg->digest_size, want_hash); + } + + /* Descend the tree verifying hash pages */ + for (; level > 0; level--) { + struct page *hpage = hpages[level - 1]; + unsigned int hoffset = hoffsets[level - 1]; + + err = fsverity_hash_page(vi, req, hpage, real_hash); + if (err) + goto out; + err = compare_hashes(want_hash, real_hash, + vi->hash_alg->digest_size, + inode, index, level - 1, + vi->hash_alg->name); + if (err) + goto out; + SetPageChecked(hpage); + extract_hash(hpage, hoffset, vi->hash_alg->digest_size, + _want_hash); + want_hash = _want_hash; + put_page(hpage); + pr_debug("Verified hash page at level %d, now want %s:%*phN\n", + level - 1, vi->hash_alg->name, + vi->hash_alg->digest_size, want_hash); + } + + /* Finally, verify the data page */ + err = fsverity_hash_page(vi, req, data_page, real_hash); + if (err) + goto out; + err = compare_hashes(want_hash, real_hash, vi->hash_alg->digest_size, + inode, index, -1, vi->hash_alg->name); +out: + for (; level > 0; level--) + put_page(hpages[level - 1]); + if (err) { + pr_warn_ratelimited("Error verifying page; ino=%lu, index=%lu (err=%d)\n", + inode->i_ino, data_page->index, err); + return false; + } + return true; +} + +/** + * fsverity_verify_page - verify a data page + * + * Verify a page that has just been read from a file against that file's Merkle + * tree. The page is assumed to be a pagecache page. + * + * Return: true if the page is valid, else false. + */ +bool fsverity_verify_page(struct page *data_page) +{ + struct inode *inode = data_page->mapping->host; + const struct fsverity_info *vi = get_fsverity_info(inode); + struct ahash_request *req; + bool valid; + + req = ahash_request_alloc(vi->hash_alg->tfm, GFP_KERNEL); + if (unlikely(!req)) + return false; + + valid = verify_page(inode, vi, req, data_page); + + ahash_request_free(req); + + return valid; +} +EXPORT_SYMBOL_GPL(fsverity_verify_page); + +#ifdef CONFIG_BLOCK +/** + * fsverity_verify_bio - verify a 'read' bio that has just completed + * + * Verify a set of pages that have just been read from a file against that + * file's Merkle tree. The pages are assumed to be pagecache pages. Pages that + * fail verification are set to the Error state. Verification is skipped for + * pages already in the Error state, e.g. due to fscrypt decryption failure. + * + * This is a helper function for filesystems that issue bios to read data + * directly into the page cache. Filesystems that work differently should call + * fsverity_verify_page() on each page instead. fsverity_verify_page() is also + * needed on holes! + */ +void fsverity_verify_bio(struct bio *bio) +{ + struct inode *inode = bio_first_page_all(bio)->mapping->host; + const struct fsverity_info *vi = get_fsverity_info(inode); + struct ahash_request *req; + struct bio_vec *bv; + int i; + + req = ahash_request_alloc(vi->hash_alg->tfm, GFP_KERNEL); + if (unlikely(!req)) { + bio_for_each_segment_all(bv, bio, i) + SetPageError(bv->bv_page); + return; + } + + bio_for_each_segment_all(bv, bio, i) { + struct page *page = bv->bv_page; + + if (!PageError(page) && !verify_page(inode, vi, req, page)) + SetPageError(page); + } + + ahash_request_free(req); +} +EXPORT_SYMBOL_GPL(fsverity_verify_bio); +#endif /* CONFIG_BLOCK */ + +/** + * fsverity_enqueue_verify_work - enqueue work on the fs-verity workqueue + * + * Enqueue verification work for asynchronous processing. + */ +void fsverity_enqueue_verify_work(struct work_struct *work) +{ + queue_work(fsverity_read_workqueue, work); +} +EXPORT_SYMBOL_GPL(fsverity_enqueue_verify_work); diff --git a/include/linux/fsverity.h b/include/linux/fsverity.h index c9422a579c160..15478fe7d55aa 100644 --- a/include/linux/fsverity.h +++ b/include/linux/fsverity.h @@ -28,6 +28,16 @@ extern int fsverity_prepare_getattr(struct inode *inode); extern void fsverity_cleanup_inode(struct inode *inode); extern loff_t fsverity_full_i_size(const struct inode *inode); +/* verify.c */ +extern bool fsverity_verify_page(struct page *page); +extern void fsverity_verify_bio(struct bio *bio); +extern void fsverity_enqueue_verify_work(struct work_struct *work); + +static inline bool fsverity_check_hole(struct inode *inode, struct page *page) +{ + return inode->i_verity_info == NULL || fsverity_verify_page(page); +} + #else /* !__FS_HAS_VERITY */ /* setup.c */ @@ -57,6 +67,29 @@ static inline loff_t fsverity_full_i_size(const struct inode *inode) return i_size_read(inode); } +/* verify.c */ + +static inline bool fsverity_verify_page(struct page *page) +{ + WARN_ON(1); + return false; +} + +static inline void fsverity_verify_bio(struct bio *bio) +{ + WARN_ON(1); +} + +static inline void fsverity_enqueue_verify_work(struct work_struct *work) +{ + WARN_ON(1); +} + +static inline bool fsverity_check_hole(struct inode *inode, struct page *page) +{ + return true; +} + #endif /* !__FS_HAS_VERITY */ #endif /* _LINUX_FSVERITY_H */ From patchwork Thu Nov 1 22:52:23 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Eric Biggers X-Patchwork-Id: 10664577 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id EEA57157A for ; Thu, 1 Nov 2018 22:54:20 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id DF8AE2B5FE for ; Thu, 1 Nov 2018 22:54:20 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id D30D02C06B; Thu, 1 Nov 2018 22:54:20 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.0 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 4B5AD2B5FE for ; Thu, 1 Nov 2018 22:54:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728176AbeKBH7R (ORCPT ); Fri, 2 Nov 2018 03:59:17 -0400 Received: from mail.kernel.org ([198.145.29.99]:52158 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728072AbeKBH7R (ORCPT ); Fri, 2 Nov 2018 03:59:17 -0400 Received: from ebiggers-linuxstation.kir.corp.google.com (unknown [104.132.51.88]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id EFBAE2084C; Thu, 1 Nov 2018 22:54:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1541112857; bh=b3QHRP8YQqlEGz0tStooS8qoUx6+xZnHbUaWpaBLfuw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=hAPcJtF3Hzy88pY/EPlY6QG8e40f21qSv7o1jvok3nWI9vAt/Rj8d+2k+a+B0CsgH rlUcL0W5z23YgF2OikvUnIkvArKLODb54l4L+LK6kWfSkF5j+sbWfIaBMEZYWjywtq Gy/Jwi5EajAGtsDvBxJbL7/S9lmiIpY7qL7QtFS4= From: Eric Biggers To: linux-fscrypt@vger.kernel.org Cc: linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-integrity@vger.kernel.org, linux-kernel@vger.kernel.org, "Theodore Y . Ts'o" , Jaegeuk Kim , Victor Hsieh , Chandan Rajendra Subject: [PATCH v2 05/12] fs-verity: implement FS_IOC_ENABLE_VERITY ioctl Date: Thu, 1 Nov 2018 15:52:23 -0700 Message-Id: <20181101225230.88058-6-ebiggers@kernel.org> X-Mailer: git-send-email 2.19.1.568.g152ad8e336-goog In-Reply-To: <20181101225230.88058-1-ebiggers@kernel.org> References: <20181101225230.88058-1-ebiggers@kernel.org> MIME-Version: 1.0 Sender: linux-fscrypt-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fscrypt@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Eric Biggers Add a function for filesystems to call to implement the FS_IOC_ENABLE_VERITY ioctl. This ioctl enables fs-verity on a file, after userspace has appended verity metadata to it. This ioctl is documented in Documentation/filesystem/fsverity.rst; see there for more information. Signed-off-by: Eric Biggers --- fs/verity/Makefile | 2 +- fs/verity/ioctl.c | 117 +++++++++++++++++++++++++++++++++++++++ include/linux/fsverity.h | 11 ++++ 3 files changed, 129 insertions(+), 1 deletion(-) create mode 100644 fs/verity/ioctl.c diff --git a/fs/verity/Makefile b/fs/verity/Makefile index a6c7cefb61ab7..6450925e3a8b7 100644 --- a/fs/verity/Makefile +++ b/fs/verity/Makefile @@ -1,3 +1,3 @@ obj-$(CONFIG_FS_VERITY) += fsverity.o -fsverity-y := hash_algs.o setup.o verify.o +fsverity-y := hash_algs.o ioctl.o setup.o verify.o diff --git a/fs/verity/ioctl.c b/fs/verity/ioctl.c new file mode 100644 index 0000000000000..c5f0022cb3bef --- /dev/null +++ b/fs/verity/ioctl.c @@ -0,0 +1,117 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * fs/verity/ioctl.c: fs-verity ioctls + * + * Copyright 2018 Google LLC + * + * Originally written by Jaegeuk Kim and Michael Halcrow; + * heavily rewritten by Eric Biggers. + */ + +#include "fsverity_private.h" + +#include +#include +#include + +/** + * fsverity_ioctl_enable - enable fs-verity on a file + * + * Enable fs-verity on a file. Verity metadata must have already been appended + * to the file. See Documentation/filesystems/fsverity.rst, section + * 'FS_IOC_ENABLE_VERITY' for details. + * + * Return: 0 on success, -errno on failure + */ +int fsverity_ioctl_enable(struct file *filp, const void __user *arg) +{ + struct inode *inode = file_inode(filp); + struct fsverity_info *vi; + int err; + + err = inode_permission(inode, MAY_WRITE); + if (err) + return err; + + if (IS_APPEND(inode)) + return -EPERM; + + if (arg) /* argument is reserved */ + return -EINVAL; + + if (S_ISDIR(inode->i_mode)) + return -EISDIR; + + if (!S_ISREG(inode->i_mode)) + return -EINVAL; + + err = mnt_want_write_file(filp); + if (err) + goto out; + + /* + * Temporarily lock out writers via writable file descriptors or + * truncate(). This should stabilize the contents of the file as well + * as its size. Note that at the end of this ioctl we will unlock + * writers, but at that point the verity bit will be set (if the ioctl + * succeeded), preventing future writers. + */ + err = deny_write_access(filp); + if (err) /* -ETXTBSY */ + goto out_drop_write; + + /* + * fsync so that the verity bit can't be persisted to disk prior to the + * data, causing verification errors after a crash. + */ + err = vfs_fsync(filp, 1); + if (err) + goto out_allow_write; + + /* Serialize concurrent use of this ioctl on the same inode */ + inode_lock(inode); + + if (get_fsverity_info(inode)) { /* fs-verity already enabled? */ + err = -EEXIST; + goto out_unlock; + } + + /* Validate the verity metadata */ + vi = create_fsverity_info(inode, true); + if (IS_ERR(vi)) { + err = PTR_ERR(vi); + if (err == -EINVAL) /* distinguish "invalid metadata" case */ + err = -EBADMSG; + goto out_unlock; + } + + /* + * Ask the filesystem to mark the file as a verity file, e.g. by setting + * the verity bit in the inode. + */ + err = inode->i_sb->s_vop->set_verity(inode, vi->data_i_size); + if (err) + goto out_free_vi; + + /* Invalidate all cached pages, forcing re-verification */ + truncate_inode_pages(inode->i_mapping, 0); + + /* + * Set ->i_verity_info, unless another task managed to do it already + * between ->set_verity() and here. + */ + if (set_fsverity_info(inode, vi)) + vi = NULL; + err = 0; +out_free_vi: + free_fsverity_info(vi); +out_unlock: + inode_unlock(inode); +out_allow_write: + allow_write_access(filp); +out_drop_write: + mnt_drop_write_file(filp); +out: + return err; +} +EXPORT_SYMBOL_GPL(fsverity_ioctl_enable); diff --git a/include/linux/fsverity.h b/include/linux/fsverity.h index 15478fe7d55aa..5de50b52ccc70 100644 --- a/include/linux/fsverity.h +++ b/include/linux/fsverity.h @@ -21,6 +21,9 @@ struct fsverity_operations { #if __FS_HAS_VERITY +/* ioctl.c */ +extern int fsverity_ioctl_enable(struct file *filp, const void __user *arg); + /* setup.c */ extern int fsverity_file_open(struct inode *inode, struct file *filp); extern int fsverity_prepare_setattr(struct dentry *dentry, struct iattr *attr); @@ -40,6 +43,14 @@ static inline bool fsverity_check_hole(struct inode *inode, struct page *page) #else /* !__FS_HAS_VERITY */ +/* ioctl.c */ + +static inline int fsverity_ioctl_enable(struct file *filp, + const void __user *arg) +{ + return -EOPNOTSUPP; +} + /* setup.c */ static inline int fsverity_file_open(struct inode *inode, struct file *filp) From patchwork Thu Nov 1 22:52:24 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Eric Biggers X-Patchwork-Id: 10664623 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 7DF1117DB for ; Thu, 1 Nov 2018 22:55:17 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 572A82C0F7 for ; Thu, 1 Nov 2018 22:55:17 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 4B0842C108; Thu, 1 Nov 2018 22:55:17 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.0 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id E4FA42C0F7 for ; Thu, 1 Nov 2018 22:55:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728030AbeKBIAC (ORCPT ); Fri, 2 Nov 2018 04:00:02 -0400 Received: from mail.kernel.org ([198.145.29.99]:52160 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728078AbeKBH7R (ORCPT ); Fri, 2 Nov 2018 03:59:17 -0400 Received: from ebiggers-linuxstation.kir.corp.google.com (unknown [104.132.51.88]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 263BE20854; Thu, 1 Nov 2018 22:54:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1541112857; bh=QPS4+r14xY2PLU7NQtFjdCO+Df3ZTP2DJA3gQxzR+Ug=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=RtuV9AasuSrml0A8JPztrOq51+O31GY8UFxL1dpwNTLtz5Ja43fuK5UofVxQIsC0w AZHrv+NsYXyqX3gyQwUT5ZzP28k5EjfArzA1xPd5GXH3UuPggB5gM+PAUSDpON41Tn xolj8djUxEZ/ybxzHhX0aZEpu8Cf0RRvK9a17wDY= From: Eric Biggers To: linux-fscrypt@vger.kernel.org Cc: linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-integrity@vger.kernel.org, linux-kernel@vger.kernel.org, "Theodore Y . Ts'o" , Jaegeuk Kim , Victor Hsieh , Chandan Rajendra Subject: [PATCH v2 06/12] fs-verity: implement FS_IOC_MEASURE_VERITY ioctl Date: Thu, 1 Nov 2018 15:52:24 -0700 Message-Id: <20181101225230.88058-7-ebiggers@kernel.org> X-Mailer: git-send-email 2.19.1.568.g152ad8e336-goog In-Reply-To: <20181101225230.88058-1-ebiggers@kernel.org> References: <20181101225230.88058-1-ebiggers@kernel.org> MIME-Version: 1.0 Sender: linux-fscrypt-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fscrypt@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Eric Biggers Add a function for filesystems to call to implement the FS_IOC_MEASURE_VERITY ioctl. This ioctl retrieves the file measurement hash that fs-verity calculated for the given file and is enforcing for reads; i.e., reads that don't match this hash will fail. This ioctl can be used for logging or authentication of file hashes in userspace. This ioctl is documented in Documentation/filesystem/fsverity.rst; see there for more information. Signed-off-by: Eric Biggers --- fs/verity/ioctl.c | 47 ++++++++++++++++++++++++++++++++++++++++ fs/verity/setup.c | 4 +++- include/linux/fsverity.h | 6 +++++ 3 files changed, 56 insertions(+), 1 deletion(-) diff --git a/fs/verity/ioctl.c b/fs/verity/ioctl.c index c5f0022cb3bef..640aa78e1c00c 100644 --- a/fs/verity/ioctl.c +++ b/fs/verity/ioctl.c @@ -115,3 +115,50 @@ int fsverity_ioctl_enable(struct file *filp, const void __user *arg) return err; } EXPORT_SYMBOL_GPL(fsverity_ioctl_enable); + +/** + * fsverity_ioctl_measure - get a verity file's measurement + * + * Retrieve the file measurement that the kernel is enforcing for reads from a + * verity file. See Documentation/filesystems/fsverity.rst, section + * 'FS_IOC_MEASURE_VERITY' for details. + * + * Return: 0 on success, -errno on failure + */ +int fsverity_ioctl_measure(struct file *filp, void __user *_uarg) +{ + const struct inode *inode = file_inode(filp); + struct fsverity_digest __user *uarg = _uarg; + const struct fsverity_info *vi; + const struct fsverity_hash_alg *hash_alg; + struct fsverity_digest arg; + + vi = get_fsverity_info(inode); + if (!vi) + return -ENODATA; /* not a verity file */ + hash_alg = vi->hash_alg; + + /* + * The user specifies the digest_size their buffer has space for; we can + * return the digest if it fits in the available space. We write back + * the actual size, which may be shorter than the user-specified size. + */ + + if (get_user(arg.digest_size, &uarg->digest_size)) + return -EFAULT; + if (arg.digest_size < hash_alg->digest_size) + return -EOVERFLOW; + + memset(&arg, 0, sizeof(arg)); + arg.digest_algorithm = hash_alg - fsverity_hash_algs; + arg.digest_size = hash_alg->digest_size; + + if (copy_to_user(uarg, &arg, sizeof(arg))) + return -EFAULT; + + if (copy_to_user(uarg->digest, vi->measurement, hash_alg->digest_size)) + return -EFAULT; + + return 0; +} +EXPORT_SYMBOL_GPL(fsverity_ioctl_measure); diff --git a/fs/verity/setup.c b/fs/verity/setup.c index 184bdc96abe51..e0b39c518b890 100644 --- a/fs/verity/setup.c +++ b/fs/verity/setup.c @@ -819,7 +819,9 @@ static int __init fsverity_module_init(void) goto error; err = -ENOMEM; - fsverity_info_cachep = KMEM_CACHE(fsverity_info, SLAB_RECLAIM_ACCOUNT); + fsverity_info_cachep = KMEM_CACHE_USERCOPY(fsverity_info, + SLAB_RECLAIM_ACCOUNT, + measurement); if (!fsverity_info_cachep) goto error_free_workqueue; diff --git a/include/linux/fsverity.h b/include/linux/fsverity.h index 5de50b52ccc70..c30c4f6ed411c 100644 --- a/include/linux/fsverity.h +++ b/include/linux/fsverity.h @@ -23,6 +23,7 @@ struct fsverity_operations { /* ioctl.c */ extern int fsverity_ioctl_enable(struct file *filp, const void __user *arg); +extern int fsverity_ioctl_measure(struct file *filp, void __user *arg); /* setup.c */ extern int fsverity_file_open(struct inode *inode, struct file *filp); @@ -51,6 +52,11 @@ static inline int fsverity_ioctl_enable(struct file *filp, return -EOPNOTSUPP; } +static inline int fsverity_ioctl_measure(struct file *filp, void __user *arg) +{ + return -EOPNOTSUPP; +} + /* setup.c */ static inline int fsverity_file_open(struct inode *inode, struct file *filp) From patchwork Thu Nov 1 22:52:25 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Eric Biggers X-Patchwork-Id: 10664609 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id DCB0E17DB for ; Thu, 1 Nov 2018 22:54:56 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id CE7802C0D8 for ; Thu, 1 Nov 2018 22:54:56 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id C25AA2C104; Thu, 1 Nov 2018 22:54:56 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.0 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 7AC4D2C0D8 for ; Thu, 1 Nov 2018 22:54:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728150AbeKBH7R (ORCPT ); Fri, 2 Nov 2018 03:59:17 -0400 Received: from mail.kernel.org ([198.145.29.99]:52162 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728081AbeKBH7Q (ORCPT ); Fri, 2 Nov 2018 03:59:16 -0400 Received: from ebiggers-linuxstation.kir.corp.google.com (unknown [104.132.51.88]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 4E98F20866; Thu, 1 Nov 2018 22:54:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1541112857; bh=GU3tCBUJ8zIG8Ivryy6fFaMUuIw2pxPwqQtzuo7iW/0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Q+BRq6OCbxF+9/cLhbFrN9807OQMQGG0XKP3YOqwngFsWbePmDcwMzbYNTqkXuhIl GeDN+KeB/AVZv5hkZ+6HTG+rWbEzXE5oLCUWOLN/8nIThRruGayC29einhihCvchzZ ynM8mya8E8+xSdI6kDAgniGI8k3jiW3mybxTwwGg= From: Eric Biggers To: linux-fscrypt@vger.kernel.org Cc: linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-integrity@vger.kernel.org, linux-kernel@vger.kernel.org, "Theodore Y . Ts'o" , Jaegeuk Kim , Victor Hsieh , Chandan Rajendra Subject: [PATCH v2 07/12] fs-verity: add SHA-512 support Date: Thu, 1 Nov 2018 15:52:25 -0700 Message-Id: <20181101225230.88058-8-ebiggers@kernel.org> X-Mailer: git-send-email 2.19.1.568.g152ad8e336-goog In-Reply-To: <20181101225230.88058-1-ebiggers@kernel.org> References: <20181101225230.88058-1-ebiggers@kernel.org> MIME-Version: 1.0 Sender: linux-fscrypt-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fscrypt@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Eric Biggers Add SHA-512 support to fs-verity. This is primarily a demonstration of the (small) changes needed to support a new hash algorithm; it's anticipated that most users will still prefer SHA-256 due to the smaller space required to store the hashes, though some may prefer SHA-512. Signed-off-by: Eric Biggers --- fs/verity/fsverity_private.h | 2 +- fs/verity/hash_algs.c | 5 +++++ include/uapi/linux/fsverity.h | 1 + 3 files changed, 7 insertions(+), 1 deletion(-) diff --git a/fs/verity/fsverity_private.h b/fs/verity/fsverity_private.h index dfdbac3874d74..c3a261a598557 100644 --- a/fs/verity/fsverity_private.h +++ b/fs/verity/fsverity_private.h @@ -30,7 +30,7 @@ * Largest digest size among all hash algorithms supported by fs-verity. This * can be increased if needed. */ -#define FS_VERITY_MAX_DIGEST_SIZE SHA256_DIGEST_SIZE +#define FS_VERITY_MAX_DIGEST_SIZE SHA512_DIGEST_SIZE /* A hash algorithm supported by fs-verity */ struct fsverity_hash_alg { diff --git a/fs/verity/hash_algs.c b/fs/verity/hash_algs.c index 9c19c9553f120..3174a0c08785d 100644 --- a/fs/verity/hash_algs.c +++ b/fs/verity/hash_algs.c @@ -18,6 +18,11 @@ struct fsverity_hash_alg fsverity_hash_algs[] = { .digest_size = 32, .cryptographic = true, }, + [FS_VERITY_ALG_SHA512] = { + .name = "sha512", + .digest_size = 64, + .cryptographic = true, + }, }; /* diff --git a/include/uapi/linux/fsverity.h b/include/uapi/linux/fsverity.h index 55b9f32676220..67ed830ae2ece 100644 --- a/include/uapi/linux/fsverity.h +++ b/include/uapi/linux/fsverity.h @@ -28,6 +28,7 @@ struct fsverity_digest { /* Supported hash algorithms */ #define FS_VERITY_ALG_SHA256 1 +#define FS_VERITY_ALG_SHA512 2 /* Metadata stored near the end of verity files, after the Merkle tree */ /* This structure is 64 bytes long */ From patchwork Thu Nov 1 22:52:26 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Eric Biggers X-Patchwork-Id: 10664617 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id A668414E2 for ; Thu, 1 Nov 2018 22:55:14 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 9812D2C0D8 for ; Thu, 1 Nov 2018 22:55:14 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 8C94E2C108; Thu, 1 Nov 2018 22:55:14 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.0 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 421C72C0D8 for ; Thu, 1 Nov 2018 22:55:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728176AbeKBIAC (ORCPT ); Fri, 2 Nov 2018 04:00:02 -0400 Received: from mail.kernel.org ([198.145.29.99]:52164 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728083AbeKBH7Q (ORCPT ); Fri, 2 Nov 2018 03:59:16 -0400 Received: from ebiggers-linuxstation.kir.corp.google.com (unknown [104.132.51.88]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 76AD02086D; Thu, 1 Nov 2018 22:54:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1541112857; bh=6aWfDT8BFa0Xa9diw5+HNmJhJldqF+mtmBKHTyX1P4Q=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=N6iKpHLIFP/bsmTWDW9CXDlwyhBA33HpZ0VjIMCloQzhOzbz3hG1MOdiS+DbqxI1E /Jxo0o7CX2QZfIWbY7Zo5vPEROBH3BAujEzaFs8fzlNH+9UkK33AaER6yOZOYP9D4g XCutFPCjcy1XmnMdjb2PQt59Iz0oq9LmCrgzksxw= From: Eric Biggers To: linux-fscrypt@vger.kernel.org Cc: linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-integrity@vger.kernel.org, linux-kernel@vger.kernel.org, "Theodore Y . Ts'o" , Jaegeuk Kim , Victor Hsieh , Chandan Rajendra Subject: [PATCH v2 08/12] fs-verity: add CRC-32C support Date: Thu, 1 Nov 2018 15:52:26 -0700 Message-Id: <20181101225230.88058-9-ebiggers@kernel.org> X-Mailer: git-send-email 2.19.1.568.g152ad8e336-goog In-Reply-To: <20181101225230.88058-1-ebiggers@kernel.org> References: <20181101225230.88058-1-ebiggers@kernel.org> MIME-Version: 1.0 Sender: linux-fscrypt-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fscrypt@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Eric Biggers Add CRC-32C support to fs-verity, to provide a faster alternative to SHA-256 for users who want integrity-only (not authenticity), i.e. who want to detect only accidental corruption, not malicious changes. CRC-32C is chosen over CRC-32 because the CRC-32C polynomial is believed to provide slightly better error-detection properties; and CRC-32C is just as fast (or can be just as fast) as CRC-32, or even faster e.g. on some x86 processors that have a CRC-32C instruction but not CRC-32. We use "crc32c" from the crypto API, so the polynomial convention is bitwise little-endian, the digest is bytewise little-endian, and the CRC bits are inverted at the beginning and end (which is desirable). Signed-off-by: Eric Biggers --- fs/verity/hash_algs.c | 4 ++++ include/uapi/linux/fsverity.h | 1 + 2 files changed, 5 insertions(+) diff --git a/fs/verity/hash_algs.c b/fs/verity/hash_algs.c index 3174a0c08785d..109afeec60fc9 100644 --- a/fs/verity/hash_algs.c +++ b/fs/verity/hash_algs.c @@ -23,6 +23,10 @@ struct fsverity_hash_alg fsverity_hash_algs[] = { .digest_size = 64, .cryptographic = true, }, + [FS_VERITY_ALG_CRC32C] = { + .name = "crc32c", + .digest_size = 4, + }, }; /* diff --git a/include/uapi/linux/fsverity.h b/include/uapi/linux/fsverity.h index 67ed830ae2ece..a96bbf87077de 100644 --- a/include/uapi/linux/fsverity.h +++ b/include/uapi/linux/fsverity.h @@ -29,6 +29,7 @@ struct fsverity_digest { /* Supported hash algorithms */ #define FS_VERITY_ALG_SHA256 1 #define FS_VERITY_ALG_SHA512 2 +#define FS_VERITY_ALG_CRC32C 3 /* for integrity only */ /* Metadata stored near the end of verity files, after the Merkle tree */ /* This structure is 64 bytes long */ From patchwork Thu Nov 1 22:52:27 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Eric Biggers X-Patchwork-Id: 10664605 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id B2C321751 for ; Thu, 1 Nov 2018 22:54:51 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id A5CDB2C0D8 for ; Thu, 1 Nov 2018 22:54:51 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 997252C0F7; Thu, 1 Nov 2018 22:54:51 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.0 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id C863B2C104 for ; Thu, 1 Nov 2018 22:54:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728179AbeKBH7S (ORCPT ); Fri, 2 Nov 2018 03:59:18 -0400 Received: from mail.kernel.org ([198.145.29.99]:52178 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728026AbeKBH7R (ORCPT ); Fri, 2 Nov 2018 03:59:17 -0400 Received: from ebiggers-linuxstation.kir.corp.google.com (unknown [104.132.51.88]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id A10482081B; Thu, 1 Nov 2018 22:54:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1541112857; bh=I+Wr8wthYyLzUWFR1SkRMOzj2VjxaFstApgMh678HsY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=MvRR1f6Pamld4Jyac0YAUCpf2tKBY6xg9Mq78bHFGMIWC1VVBWQE5PcEwYIV2LaU+ qZ2Hb8+NIrzRZ5V4Jni5AleTx6RBDKHlttzkiFP9YBqMNMJmrvUDlzMJr0gCemr5V8 FzoJBOGYewFc+1O7vv4v5VSfYCsOZAue2IpT2GQQ= From: Eric Biggers To: linux-fscrypt@vger.kernel.org Cc: linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-integrity@vger.kernel.org, linux-kernel@vger.kernel.org, "Theodore Y . Ts'o" , Jaegeuk Kim , Victor Hsieh , Chandan Rajendra Subject: [PATCH v2 09/12] fs-verity: support builtin file signatures Date: Thu, 1 Nov 2018 15:52:27 -0700 Message-Id: <20181101225230.88058-10-ebiggers@kernel.org> X-Mailer: git-send-email 2.19.1.568.g152ad8e336-goog In-Reply-To: <20181101225230.88058-1-ebiggers@kernel.org> References: <20181101225230.88058-1-ebiggers@kernel.org> MIME-Version: 1.0 Sender: linux-fscrypt-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fscrypt@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Eric Biggers For ease of use, add optional support for having fs-verity handle a portion of the authentication policy in the kernel. A ".fs-verity" keyring is created to which trusted X.509 certificates can be added; then a sysctl 'fs.verity.require_signatures' can be set to cause the kernel to enforce that all fs-verity files contain a signature of their file measurement, signed by a key in this keyring. See Documentation/filesystem/fsverity.rst for more information, namely the "Built-in file signatures" section. Signed-off-by: Eric Biggers --- fs/verity/Kconfig | 17 ++++ fs/verity/Makefile | 2 + fs/verity/fsverity_private.h | 34 +++++++ fs/verity/setup.c | 63 +++++++++++- fs/verity/signature.c | 187 ++++++++++++++++++++++++++++++++++ include/uapi/linux/fsverity.h | 10 ++ 6 files changed, 311 insertions(+), 2 deletions(-) create mode 100644 fs/verity/signature.c diff --git a/fs/verity/Kconfig b/fs/verity/Kconfig index 102c46ebe275f..a7470a2e4892f 100644 --- a/fs/verity/Kconfig +++ b/fs/verity/Kconfig @@ -33,3 +33,20 @@ config FS_VERITY_DEBUG Enable debugging messages related to fs-verity by default. Say N unless you are an fs-verity developer. + +config FS_VERITY_BUILTIN_SIGNATURES + bool "FS Verity builtin signature support" + depends on FS_VERITY + select SYSTEM_DATA_VERIFICATION + help + Support verifying signatures of verity files against the X.509 + certificates that have been loaded into the ".fs-verity" + kernel keyring. + + This is meant as a relatively simple mechanism that can be + used to provide an authenticity guarantee for verity files, as + an alternative to IMA appraisal. Userspace programs still + need to check that the verity bit is set in order to get an + authenticity guarantee. + + If unsure, say N. diff --git a/fs/verity/Makefile b/fs/verity/Makefile index 6450925e3a8b7..d293ea2a1b393 100644 --- a/fs/verity/Makefile +++ b/fs/verity/Makefile @@ -1,3 +1,5 @@ obj-$(CONFIG_FS_VERITY) += fsverity.o fsverity-y := hash_algs.o ioctl.o setup.o verify.o + +fsverity-$(CONFIG_FS_VERITY_BUILTIN_SIGNATURES) += signature.o diff --git a/fs/verity/fsverity_private.h b/fs/verity/fsverity_private.h index c3a261a598557..4b39d0a5544ba 100644 --- a/fs/verity/fsverity_private.h +++ b/fs/verity/fsverity_private.h @@ -63,6 +63,7 @@ struct fsverity_info { u8 root_hash[FS_VERITY_MAX_DIGEST_SIZE]; /* Merkle tree root hash */ u8 measurement[FS_VERITY_MAX_DIGEST_SIZE]; /* file measurement */ bool have_root_hash; /* have root hash from disk? */ + bool have_signed_measurement; /* have measurement from signature? */ /* Starting blocks for each tree level. 'depth-1' is the root level. */ u64 hash_lvl_region_idx[FS_VERITY_MAX_LEVELS]; @@ -95,6 +96,39 @@ static inline bool set_fsverity_info(struct inode *inode, return cmpxchg_release(&inode->i_verity_info, NULL, vi) == NULL; } +/* signature.c */ +#ifdef CONFIG_FS_VERITY_BUILTIN_SIGNATURES +extern int fsverity_require_signatures; + +int fsverity_parse_pkcs7_signature_extension(struct fsverity_info *vi, + const void *raw_pkcs7, + size_t size); + +int __init fsverity_signature_init(void); + +void __exit fsverity_signature_exit(void); +#else /* CONFIG_FS_VERITY_BUILTIN_SIGNATURES */ + +#define fsverity_require_signatures 0 + +static inline int +fsverity_parse_pkcs7_signature_extension(struct fsverity_info *vi, + const void *raw_pkcs7, size_t size) +{ + pr_warn("PKCS#7 signatures not supported in this kernel build!\n"); + return -EINVAL; +} + +static inline int fsverity_signature_init(void) +{ + return 0; +} + +static inline void fsverity_signature_exit(void) +{ +} +#endif /* !CONFIG_FS_VERITY_BUILTIN_SIGNATURES */ + /* verify.c */ extern struct workqueue_struct *fsverity_read_workqueue; diff --git a/fs/verity/setup.c b/fs/verity/setup.c index e0b39c518b890..08b609127531b 100644 --- a/fs/verity/setup.c +++ b/fs/verity/setup.c @@ -132,6 +132,10 @@ static const struct extension_type { [FS_VERITY_EXT_SALT] = { .parse = parse_salt_extension, }, + [FS_VERITY_EXT_PKCS7_SIGNATURE] = { + .parse = fsverity_parse_pkcs7_signature_extension, + .unauthenticated = true, + }, }; static int do_parse_extensions(struct fsverity_info *vi, @@ -429,6 +433,54 @@ static int compute_measurement(const struct fsverity_info *vi, return err; } +/* + * Compute the file's measurement; then, if a signature was present, verify that + * the signed measurement matches the actual one. + */ +static int +verify_file_measurement(struct fsverity_info *vi, + const struct fsverity_descriptor *desc, + int desc_auth_len, + struct page *desc_pages[MAX_DESCRIPTOR_PAGES], + int nr_desc_pages) +{ + u8 measurement[FS_VERITY_MAX_DIGEST_SIZE]; + int err; + + err = compute_measurement(vi, desc, desc_auth_len, desc_pages, + nr_desc_pages, measurement); + if (err) { + pr_warn("Error computing fs-verity measurement: %d\n", err); + return err; + } + + if (!vi->have_signed_measurement) { + pr_debug("Computed measurement: %s:%*phN (used desc_auth_len %d)\n", + vi->hash_alg->name, vi->hash_alg->digest_size, + measurement, desc_auth_len); + if (fsverity_require_signatures) { + pr_warn("require_signatures=1, rejecting unsigned file!\n"); + return -EBADMSG; + } + memcpy(vi->measurement, measurement, vi->hash_alg->digest_size); + return 0; + } + + if (!memcmp(measurement, vi->measurement, vi->hash_alg->digest_size)) { + pr_debug("Verified measurement: %s:%*phN (used desc_auth_len %d)\n", + vi->hash_alg->name, vi->hash_alg->digest_size, + measurement, desc_auth_len); + return 0; + } + + pr_warn("FILE CORRUPTED (actual measurement mismatches signed measurement): " + "want %s:%*phN, real %s:%*phN (used desc_auth_len %d)\n", + vi->hash_alg->name, vi->hash_alg->digest_size, vi->measurement, + vi->hash_alg->name, vi->hash_alg->digest_size, measurement, + desc_auth_len); + return -EBADMSG; +} + static struct fsverity_info *alloc_fsverity_info(void) { return kmem_cache_zalloc(fsverity_info_cachep, GFP_NOFS); @@ -674,8 +726,8 @@ struct fsverity_info *create_fsverity_info(struct inode *inode, bool enabling) err = compute_tree_depth_and_offsets(vi); if (err) goto out; - err = compute_measurement(vi, desc, desc_auth_len, desc_pages, - nr_desc_pages, vi->measurement); + err = verify_file_measurement(vi, desc, desc_auth_len, + desc_pages, nr_desc_pages); out: if (desc) unmap_fsverity_descriptor(desc, desc_pages, nr_desc_pages); @@ -825,11 +877,17 @@ static int __init fsverity_module_init(void) if (!fsverity_info_cachep) goto error_free_workqueue; + err = fsverity_signature_init(); + if (err) + goto error_free_info_cache; + fsverity_check_hash_algs(); pr_debug("Initialized fs-verity\n"); return 0; +error_free_info_cache: + kmem_cache_destroy(fsverity_info_cachep); error_free_workqueue: destroy_workqueue(fsverity_read_workqueue); error: @@ -840,6 +898,7 @@ static void __exit fsverity_module_exit(void) { destroy_workqueue(fsverity_read_workqueue); kmem_cache_destroy(fsverity_info_cachep); + fsverity_signature_exit(); fsverity_exit_hash_algs(); } diff --git a/fs/verity/signature.c b/fs/verity/signature.c new file mode 100644 index 0000000000000..e13b25becbc6f --- /dev/null +++ b/fs/verity/signature.c @@ -0,0 +1,187 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * fs/verity/signature.c: verification of builtin signatures + * + * Copyright 2018 Google LLC + * + * Written by Eric Biggers. + */ + +#include "fsverity_private.h" + +#include +#include +#include + +/* + * /proc/sys/fs/verity/require_signatures + * If 1, all verity files must have a valid builtin signature. + */ +int fsverity_require_signatures; + +/* + * Keyring that contains the trusted X.509 certificates. + * + * Only root (kuid=0) can modify this. Also, root may use + * keyctl_restrict_keyring() to prevent any more additions. + */ +static struct key *fsverity_keyring; + +static int extract_measurement(void *ctx, const void *data, size_t len, + size_t asn1hdrlen) +{ + struct fsverity_info *vi = ctx; + const struct fsverity_digest_disk *d; + const struct fsverity_hash_alg *hash_alg; + + if (len < sizeof(*d)) { + pr_warn("Signed file measurement has unrecognized format\n"); + return -EBADMSG; + } + d = (const void *)data; + + hash_alg = fsverity_get_hash_alg(le16_to_cpu(d->digest_algorithm)); + if (IS_ERR(hash_alg)) + return PTR_ERR(hash_alg); + + if (le16_to_cpu(d->digest_size) != hash_alg->digest_size) { + pr_warn("Wrong digest_size in signed measurement: wanted %u for algorithm %s, but got %u\n", + hash_alg->digest_size, hash_alg->name, + le16_to_cpu(d->digest_size)); + return -EBADMSG; + } + + if (len < sizeof(*d) + hash_alg->digest_size) { + pr_warn("Signed file measurement is truncated\n"); + return -EBADMSG; + } + + if (hash_alg != vi->hash_alg) { + pr_warn("Signed file measurement uses %s, but file uses %s\n", + hash_alg->name, vi->hash_alg->name); + return -EBADMSG; + } + + memcpy(vi->measurement, d->digest, hash_alg->digest_size); + vi->have_signed_measurement = true; + return 0; +} + +/** + * fsverity_parse_pkcs7_signature_extension - verify the signed file measurement + * + * Verify a signed fsverity_measurement against the certificates in the + * fs-verity keyring. The signature is given as a PKCS#7 formatted message, and + * the signed data is included in the message (not detached). + * + * Return: 0 if the signature checks out and the signed measurement is + * well-formed and uses the expected hash algorithm; -EBADMSG on signature + * verification failure or malformed data; else another -errno code. + */ +int fsverity_parse_pkcs7_signature_extension(struct fsverity_info *vi, + const void *raw_pkcs7, size_t size) +{ + int err; + + if (vi->have_signed_measurement) { + pr_warn("Found multiple PKCS#7 signatures\n"); + return -EBADMSG; + } + + if (!vi->hash_alg->cryptographic) { + /* Might as well check this... */ + pr_warn("Found signed %s file measurement, but %s isn't a cryptographic hash algorithm.\n", + vi->hash_alg->name, vi->hash_alg->name); + return -EBADMSG; + } + + err = verify_pkcs7_signature(NULL, 0, raw_pkcs7, size, fsverity_keyring, + VERIFYING_UNSPECIFIED_SIGNATURE, + extract_measurement, vi); + if (err) + pr_warn("PKCS#7 signature verification error: %d\n", err); + + return err; +} + +#ifdef CONFIG_SYSCTL +static int zero; +static int one = 1; +static struct ctl_table_header *fsverity_sysctl_header; + +static const struct ctl_path fsverity_sysctl_path[] = { + { .procname = "fs", }, + { .procname = "verity", }, + { } +}; + +static struct ctl_table fsverity_sysctl_table[] = { + { + .procname = "require_signatures", + .data = &fsverity_require_signatures, + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = proc_dointvec_minmax, + .extra1 = &zero, + .extra2 = &one, + }, + { } +}; + +static int __init fsverity_sysctl_init(void) +{ + fsverity_sysctl_header = register_sysctl_paths(fsverity_sysctl_path, + fsverity_sysctl_table); + if (!fsverity_sysctl_header) { + pr_warn("sysctl registration failed!"); + return -ENOMEM; + } + return 0; +} + +static void __exit fsverity_sysctl_exit(void) +{ + unregister_sysctl_table(fsverity_sysctl_header); +} +#else /* CONFIG_SYSCTL */ +static inline int fsverity_sysctl_init(void) +{ + return 0; +} + +static inline void fsverity_sysctl_exit(void) +{ +} +#endif /* !CONFIG_SYSCTL */ + +int __init fsverity_signature_init(void) +{ + struct key *ring; + int err; + + ring = keyring_alloc(".fs-verity", KUIDT_INIT(0), KGIDT_INIT(0), + current_cred(), + ((KEY_POS_ALL & ~KEY_POS_SETATTR) | + KEY_USR_VIEW | KEY_USR_READ | + KEY_USR_WRITE | KEY_USR_SEARCH | KEY_USR_SETATTR), + KEY_ALLOC_NOT_IN_QUOTA, NULL, NULL); + if (IS_ERR(ring)) + return PTR_ERR(ring); + + err = fsverity_sysctl_init(); + if (err) + goto error_put_ring; + + fsverity_keyring = ring; + return 0; + +error_put_ring: + key_put(ring); + return err; +} + +void __exit fsverity_signature_exit(void) +{ + key_put(fsverity_keyring); + fsverity_sysctl_exit(); +} diff --git a/include/uapi/linux/fsverity.h b/include/uapi/linux/fsverity.h index a96bbf87077de..b030589b8fd93 100644 --- a/include/uapi/linux/fsverity.h +++ b/include/uapi/linux/fsverity.h @@ -56,6 +56,7 @@ struct fsverity_descriptor { /* Extension types */ #define FS_VERITY_EXT_ROOT_HASH 1 #define FS_VERITY_EXT_SALT 2 +#define FS_VERITY_EXT_PKCS7_SIGNATURE 3 /* Header of each extension (variable-length metadata item) */ struct fsverity_extension { @@ -78,6 +79,15 @@ struct fsverity_extension { /* FS_VERITY_EXT_SALT payload is just a byte array, any size */ +/* + * FS_VERITY_EXT_PKCS7_SIGNATURE payload is a DER-encoded PKCS#7 message + * containing the signed file measurement in the following format: + */ +struct fsverity_digest_disk { + __le16 digest_algorithm; + __le16 digest_size; + __u8 digest[]; +}; /* Fields stored at the very end of the file */ struct fsverity_footer { From patchwork Thu Nov 1 22:52:28 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Eric Biggers X-Patchwork-Id: 10664591 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 83B9117DB for ; Thu, 1 Nov 2018 22:54:42 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 779602C0D8 for ; Thu, 1 Nov 2018 22:54:42 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 6B9492C104; Thu, 1 Nov 2018 22:54:42 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.0 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 9F2B82C0F7 for ; Thu, 1 Nov 2018 22:54:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728215AbeKBH7T (ORCPT ); Fri, 2 Nov 2018 03:59:19 -0400 Received: from mail.kernel.org ([198.145.29.99]:52180 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728107AbeKBH7R (ORCPT ); Fri, 2 Nov 2018 03:59:17 -0400 Received: from ebiggers-linuxstation.kir.corp.google.com (unknown [104.132.51.88]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id D1F322087A; Thu, 1 Nov 2018 22:54:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1541112857; bh=n9hZk1wanpnMssUh6Qf0oVX570dKrYXQk6/Gh1rS2ws=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=q1zehUWd43b4ulcjayqnNVAR+5OaASEdnKo5Wkh8isTw6v2S9c5Obin+UlvYH2KIa wCV2WNmPLx/gXDYUhgILT/dVwXxj4xiqFi+slasBa7hhTUemEHIQDSP4JOEnLj0Bja YTUFgRnKst+EO7v6lUpAnAs0GG6sgi1eRYX+JYkQ= From: Eric Biggers To: linux-fscrypt@vger.kernel.org Cc: linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-integrity@vger.kernel.org, linux-kernel@vger.kernel.org, "Theodore Y . Ts'o" , Jaegeuk Kim , Victor Hsieh , Chandan Rajendra Subject: [PATCH v2 10/12] ext4: add basic fs-verity support Date: Thu, 1 Nov 2018 15:52:28 -0700 Message-Id: <20181101225230.88058-11-ebiggers@kernel.org> X-Mailer: git-send-email 2.19.1.568.g152ad8e336-goog In-Reply-To: <20181101225230.88058-1-ebiggers@kernel.org> References: <20181101225230.88058-1-ebiggers@kernel.org> MIME-Version: 1.0 Sender: linux-fscrypt-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fscrypt@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Eric Biggers Add basic fs-verity support to ext4. fs-verity is a filesystem feature that enables transparent integrity protection and authentication of read-only files. It uses a dm-verity like mechanism at the file level: a Merkle tree is used to verify any block in the file in log(filesize) time. It is implemented mainly by helper functions in fs/verity/. See Documentation/filesystems/fsverity.rst for details. This patch adds everything except the data verification hooks that will needed in ->readpages(). On ext4, enabling fs-verity on a file requires that the filesystem has the 'verity' feature, e.g. that it was formatted with 'mkfs.ext4 -O verity' or had 'tune2fs -O verity' run on it. This requires e2fsprogs 1.44.4-2 or later. In ext4, we choose to retain the fs-verity metadata past the end of the file rather than trying to move it into an external inode xattr, since in practice keeping the metadata in-line actually results in the simplest and most efficient implementation. One non-obvious advantage of keeping the verity metadata in-line is that when fs-verity is combined with fscrypt, the verity metadata naturally gets encrypted too; this is actually necessary because it contains hashes of the plaintext. We also choose to keep the on-disk i_size equal to the original file size, in order to make the 'verity' feature a RO_COMPAT feature. Thus, ext4 has to find the fsverity_footer by looking in the last extent. Co-developed-by: Theodore Ts'o Signed-off-by: Theodore Ts'o Signed-off-by: Eric Biggers --- fs/ext4/Kconfig | 20 +++++++++++ fs/ext4/ext4.h | 20 ++++++++++- fs/ext4/file.c | 6 ++++ fs/ext4/inode.c | 8 +++++ fs/ext4/ioctl.c | 12 +++++++ fs/ext4/super.c | 91 +++++++++++++++++++++++++++++++++++++++++++++++++ fs/ext4/sysfs.c | 6 ++++ 7 files changed, 162 insertions(+), 1 deletion(-) diff --git a/fs/ext4/Kconfig b/fs/ext4/Kconfig index a453cc87082b5..5a76125ac0f8a 100644 --- a/fs/ext4/Kconfig +++ b/fs/ext4/Kconfig @@ -111,6 +111,26 @@ config EXT4_FS_ENCRYPTION default y depends on EXT4_ENCRYPTION +config EXT4_FS_VERITY + bool "Ext4 Verity" + depends on EXT4_FS + select FS_VERITY + help + This option enables fs-verity for ext4. fs-verity is the + dm-verity mechanism implemented at the file level. Userspace + can append a Merkle tree (hash tree) to a file, then enable + fs-verity on the file. ext4 will then transparently verify + any data read from the file against the Merkle tree. The file + is also made read-only. + + This serves as an integrity check, but the availability of the + Merkle tree root hash also allows efficiently supporting + various use cases where normally the whole file would need to + be hashed at once, such as auditing and authenticity + verification (appraisal). + + If unsure, say N. + config EXT4_DEBUG bool "EXT4 debugging support" depends on EXT4_FS diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h index 12f90d48ba613..e5475a629ed80 100644 --- a/fs/ext4/ext4.h +++ b/fs/ext4/ext4.h @@ -43,6 +43,9 @@ #define __FS_HAS_ENCRYPTION IS_ENABLED(CONFIG_EXT4_FS_ENCRYPTION) #include +#define __FS_HAS_VERITY IS_ENABLED(CONFIG_EXT4_FS_VERITY) +#include + #include /* Until this gets included into linux/compiler-gcc.h */ @@ -405,6 +408,7 @@ struct flex_groups { #define EXT4_TOPDIR_FL 0x00020000 /* Top of directory hierarchies*/ #define EXT4_HUGE_FILE_FL 0x00040000 /* Set to each huge file */ #define EXT4_EXTENTS_FL 0x00080000 /* Inode uses extents */ +#define EXT4_VERITY_FL 0x00100000 /* Verity protected inode */ #define EXT4_EA_INODE_FL 0x00200000 /* Inode used for large EA */ #define EXT4_EOFBLOCKS_FL 0x00400000 /* Blocks allocated beyond EOF */ #define EXT4_INLINE_DATA_FL 0x10000000 /* Inode has inline data. */ @@ -472,6 +476,7 @@ enum { EXT4_INODE_TOPDIR = 17, /* Top of directory hierarchies*/ EXT4_INODE_HUGE_FILE = 18, /* Set to each huge file */ EXT4_INODE_EXTENTS = 19, /* Inode uses extents */ + EXT4_INODE_VERITY = 20, /* Verity protected inode */ EXT4_INODE_EA_INODE = 21, /* Inode used for large EA */ EXT4_INODE_EOFBLOCKS = 22, /* Blocks allocated beyond EOF */ EXT4_INODE_INLINE_DATA = 28, /* Data in inode. */ @@ -517,6 +522,7 @@ static inline void ext4_check_flag_values(void) CHECK_FLAG_VALUE(TOPDIR); CHECK_FLAG_VALUE(HUGE_FILE); CHECK_FLAG_VALUE(EXTENTS); + CHECK_FLAG_VALUE(VERITY); CHECK_FLAG_VALUE(EA_INODE); CHECK_FLAG_VALUE(EOFBLOCKS); CHECK_FLAG_VALUE(INLINE_DATA); @@ -1654,6 +1660,7 @@ static inline void ext4_clear_state_flags(struct ext4_inode_info *ei) #define EXT4_FEATURE_RO_COMPAT_METADATA_CSUM 0x0400 #define EXT4_FEATURE_RO_COMPAT_READONLY 0x1000 #define EXT4_FEATURE_RO_COMPAT_PROJECT 0x2000 +#define EXT4_FEATURE_RO_COMPAT_VERITY 0x8000 #define EXT4_FEATURE_INCOMPAT_COMPRESSION 0x0001 #define EXT4_FEATURE_INCOMPAT_FILETYPE 0x0002 @@ -1742,6 +1749,7 @@ EXT4_FEATURE_RO_COMPAT_FUNCS(bigalloc, BIGALLOC) EXT4_FEATURE_RO_COMPAT_FUNCS(metadata_csum, METADATA_CSUM) EXT4_FEATURE_RO_COMPAT_FUNCS(readonly, READONLY) EXT4_FEATURE_RO_COMPAT_FUNCS(project, PROJECT) +EXT4_FEATURE_RO_COMPAT_FUNCS(verity, VERITY) EXT4_FEATURE_INCOMPAT_FUNCS(compression, COMPRESSION) EXT4_FEATURE_INCOMPAT_FUNCS(filetype, FILETYPE) @@ -1797,7 +1805,8 @@ EXT4_FEATURE_INCOMPAT_FUNCS(encrypt, ENCRYPT) EXT4_FEATURE_RO_COMPAT_BIGALLOC |\ EXT4_FEATURE_RO_COMPAT_METADATA_CSUM|\ EXT4_FEATURE_RO_COMPAT_QUOTA |\ - EXT4_FEATURE_RO_COMPAT_PROJECT) + EXT4_FEATURE_RO_COMPAT_PROJECT |\ + EXT4_FEATURE_RO_COMPAT_VERITY) #define EXTN_FEATURE_FUNCS(ver) \ static inline bool ext4_has_unknown_ext##ver##_compat_features(struct super_block *sb) \ @@ -2293,6 +2302,15 @@ static inline bool ext4_encrypted_inode(struct inode *inode) return ext4_test_inode_flag(inode, EXT4_INODE_ENCRYPT); } +static inline bool ext4_verity_inode(struct inode *inode) +{ +#ifdef CONFIG_EXT4_FS_VERITY + return ext4_test_inode_flag(inode, EXT4_INODE_VERITY); +#else + return false; +#endif +} + #ifdef CONFIG_EXT4_FS_ENCRYPTION static inline int ext4_fname_setup_filename(struct inode *dir, const struct qstr *iname, diff --git a/fs/ext4/file.c b/fs/ext4/file.c index 69d65d49837bb..cb4b69ef01a22 100644 --- a/fs/ext4/file.c +++ b/fs/ext4/file.c @@ -444,6 +444,12 @@ static int ext4_file_open(struct inode * inode, struct file * filp) if (ret) return ret; + if (ext4_verity_inode(inode)) { + ret = fsverity_file_open(inode, filp); + if (ret) + return ret; + } + /* * Set up the jbd2_inode if we are opening the inode for * writing and the journal is present diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index 05f01fbd9c7fb..c624c83bbad26 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -4723,6 +4723,8 @@ static bool ext4_should_use_dax(struct inode *inode) return false; if (ext4_encrypted_inode(inode)) return false; + if (ext4_verity_inode(inode)) + return false; return true; } @@ -5505,6 +5507,12 @@ int ext4_setattr(struct dentry *dentry, struct iattr *attr) if (error) return error; + if (ext4_verity_inode(inode)) { + error = fsverity_prepare_setattr(dentry, attr); + if (error) + return error; + } + if (is_quota_modification(inode, attr)) { error = dquot_initialize(inode); if (error) diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c index 0edee31913d1f..9bb6cc1ae8ceb 100644 --- a/fs/ext4/ioctl.c +++ b/fs/ext4/ioctl.c @@ -1020,6 +1020,16 @@ long ext4_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) case EXT4_IOC_GET_ENCRYPTION_POLICY: return fscrypt_ioctl_get_policy(filp, (void __user *)arg); + case FS_IOC_ENABLE_VERITY: + if (!ext4_has_feature_verity(sb)) + return -EOPNOTSUPP; + return fsverity_ioctl_enable(filp, (const void __user *)arg); + + case FS_IOC_MEASURE_VERITY: + if (!ext4_has_feature_verity(sb)) + return -EOPNOTSUPP; + return fsverity_ioctl_measure(filp, (void __user *)arg); + case EXT4_IOC_FSGETXATTR: { struct fsxattr fa; @@ -1138,6 +1148,8 @@ long ext4_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg) case EXT4_IOC_SET_ENCRYPTION_POLICY: case EXT4_IOC_GET_ENCRYPTION_PWSALT: case EXT4_IOC_GET_ENCRYPTION_POLICY: + case FS_IOC_ENABLE_VERITY: + case FS_IOC_MEASURE_VERITY: case EXT4_IOC_SHUTDOWN: case FS_IOC_GETFSMAP: break; diff --git a/fs/ext4/super.c b/fs/ext4/super.c index a221f1cdf7046..c4a66b64ea604 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -1144,6 +1144,7 @@ void ext4_clear_inode(struct inode *inode) EXT4_I(inode)->jinode = NULL; } fscrypt_put_encryption_info(inode); + fsverity_cleanup_inode(inode); } static struct inode *ext4_nfs_get_inode(struct super_block *sb, @@ -1315,6 +1316,93 @@ static const struct fscrypt_operations ext4_cryptops = { }; #endif +#ifdef CONFIG_EXT4_FS_VERITY +static int ext4_set_verity(struct inode *inode, loff_t data_i_size) +{ + int err; + handle_t *handle; + struct ext4_iloc iloc; + + err = ext4_convert_inline_data(inode); + if (err) + return err; + + if (!ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)) { + ext4_warning_inode(inode, + "fs-verity is only allowed on extent-based files"); + return -EINVAL; + } + + /* Remove extents past EOF; see ext4_get_verity_full_size() */ + err = ext4_truncate(inode); + if (err) + return err; + + handle = ext4_journal_start(inode, EXT4_HT_INODE, 1); + if (IS_ERR(handle)) + return PTR_ERR(handle); + err = ext4_reserve_inode_write(handle, inode, &iloc); + if (err == 0) { + ext4_set_inode_flag(inode, EXT4_INODE_VERITY); + EXT4_I(inode)->i_disksize = data_i_size; + err = ext4_mark_iloc_dirty(handle, inode, &iloc); + } + ext4_journal_stop(handle); + + return err; +} + +/* + * Retrieve the offset, in bytes, to the end of the verity metadata. Ext4 + * stores the verity metadata beyond EOF, but sets the on-disk i_size to the + * original data size in order to make verity an RO_COMPAT filesystem feature. + * Therefore, it has to compute the end offset implicitly via the end of the + * last extent. Trailing zeroes after the footer are tolerated. + */ +static int ext4_get_metadata_end(struct inode *inode, loff_t *metadata_end_ret) +{ + struct ext4_ext_path *path; + struct ext4_extent *last_extent; + u32 end_lblk; + int err; + + if (ext4_has_inline_data(inode)) { + EXT4_ERROR_INODE(inode, "verity file has inline data"); + return -EFSCORRUPTED; + } + + if (!ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)) { + EXT4_ERROR_INODE(inode, "verity file doesn't use extents"); + return -EFSCORRUPTED; + } + + path = ext4_find_extent(inode, EXT_MAX_BLOCKS - 1, NULL, 0); + if (IS_ERR(path)) + return PTR_ERR(path); + + last_extent = path[path->p_depth].p_ext; + if (!last_extent) { + EXT4_ERROR_INODE(inode, "verity file has no extents"); + err = -EFSCORRUPTED; + goto out_drop_path; + } + + end_lblk = le32_to_cpu(last_extent->ee_block) + + ext4_ext_get_actual_len(last_extent); + *metadata_end_ret = (loff_t)end_lblk << inode->i_blkbits; + err = 0; +out_drop_path: + ext4_ext_drop_refs(path); + kfree(path); + return err; +} + +static const struct fsverity_operations ext4_verityops = { + .set_verity = ext4_set_verity, + .get_metadata_end = ext4_get_metadata_end, +}; +#endif /* CONFIG_EXT4_FS_VERITY */ + #ifdef CONFIG_QUOTA static const char * const quotatypes[] = INITQFNAMES; #define QTYPE2NAME(t) (quotatypes[t]) @@ -4146,6 +4234,9 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent) #ifdef CONFIG_EXT4_FS_ENCRYPTION sb->s_cop = &ext4_cryptops; #endif +#ifdef CONFIG_EXT4_FS_VERITY + sb->s_vop = &ext4_verityops; +#endif #ifdef CONFIG_QUOTA sb->dq_op = &ext4_quota_operations; if (ext4_has_feature_quota(sb)) diff --git a/fs/ext4/sysfs.c b/fs/ext4/sysfs.c index 9212a026a1f12..8e86087c2f039 100644 --- a/fs/ext4/sysfs.c +++ b/fs/ext4/sysfs.c @@ -227,6 +227,9 @@ EXT4_ATTR_FEATURE(meta_bg_resize); #ifdef CONFIG_EXT4_FS_ENCRYPTION EXT4_ATTR_FEATURE(encryption); #endif +#ifdef CONFIG_EXT4_FS_VERITY +EXT4_ATTR_FEATURE(verity); +#endif EXT4_ATTR_FEATURE(metadata_csum_seed); static struct attribute *ext4_feat_attrs[] = { @@ -235,6 +238,9 @@ static struct attribute *ext4_feat_attrs[] = { ATTR_LIST(meta_bg_resize), #ifdef CONFIG_EXT4_FS_ENCRYPTION ATTR_LIST(encryption), +#endif +#ifdef CONFIG_EXT4_FS_VERITY + ATTR_LIST(verity), #endif ATTR_LIST(metadata_csum_seed), NULL, From patchwork Thu Nov 1 22:52:29 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Eric Biggers X-Patchwork-Id: 10664587 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id A33EF17DB for ; Thu, 1 Nov 2018 22:54:40 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 9664D2C0F7 for ; Thu, 1 Nov 2018 22:54:40 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 8A5312C0D8; Thu, 1 Nov 2018 22:54:40 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.0 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id EAD8A2C0F7 for ; Thu, 1 Nov 2018 22:54:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728225AbeKBH7T (ORCPT ); Fri, 2 Nov 2018 03:59:19 -0400 Received: from mail.kernel.org ([198.145.29.99]:52184 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728113AbeKBH7R (ORCPT ); Fri, 2 Nov 2018 03:59:17 -0400 Received: from ebiggers-linuxstation.kir.corp.google.com (unknown [104.132.51.88]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 0738D2085A; Thu, 1 Nov 2018 22:54:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1541112858; bh=TUEwmUl1dUMxTUx3pF7JGkgR9zZ14j2UdpFPtX2Jriw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=gH/A4o030rLxerL58+AHPganbY+6S5cWg/UtyH/aTdvVooVKRbTPamC0PpmAKnxVe DCmAzMtiOUhLQzHn8kuDUUKogDSKIMUH45/rK/I2F1a3k8ydQuxdvRRiwd4KGDBg4S cY7ThmVSef7AkbDl7wi4RvMdcDZWCHNyu/XYL17U= From: Eric Biggers To: linux-fscrypt@vger.kernel.org Cc: linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-integrity@vger.kernel.org, linux-kernel@vger.kernel.org, "Theodore Y . Ts'o" , Jaegeuk Kim , Victor Hsieh , Chandan Rajendra Subject: [PATCH v2 11/12] ext4: add fs-verity read support Date: Thu, 1 Nov 2018 15:52:29 -0700 Message-Id: <20181101225230.88058-12-ebiggers@kernel.org> X-Mailer: git-send-email 2.19.1.568.g152ad8e336-goog In-Reply-To: <20181101225230.88058-1-ebiggers@kernel.org> References: <20181101225230.88058-1-ebiggers@kernel.org> MIME-Version: 1.0 Sender: linux-fscrypt-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fscrypt@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Eric Biggers Make ext4_mpage_readpages() verify data as it is read from fs-verity files, using the helper functions from fs/verity/. To be compatible with fscrypt, like in the corresponding f2fs patch this required refactoring the decryption workflow into a generic "post-read processing" workflow, which can do decryption, verification, or both. Co-developed-by: Theodore Ts'o Signed-off-by: Theodore Ts'o Signed-off-by: Eric Biggers --- fs/ext4/ext4.h | 2 + fs/ext4/inode.c | 3 + fs/ext4/readpage.c | 209 ++++++++++++++++++++++++++++++++++++++------- fs/ext4/super.c | 9 +- 4 files changed, 191 insertions(+), 32 deletions(-) diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h index e5475a629ed80..80957f9d3cbef 100644 --- a/fs/ext4/ext4.h +++ b/fs/ext4/ext4.h @@ -3101,6 +3101,8 @@ static inline void ext4_set_de_type(struct super_block *sb, extern int ext4_mpage_readpages(struct address_space *mapping, struct list_head *pages, struct page *page, unsigned nr_pages, bool is_readahead); +extern int __init ext4_init_post_read_processing(void); +extern void ext4_exit_post_read_processing(void); /* symlink.c */ extern const struct inode_operations ext4_encrypted_symlink_inode_operations; diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index c624c83bbad26..d7019f5dca6f1 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -3884,6 +3884,9 @@ static ssize_t ext4_direct_IO(struct kiocb *iocb, struct iov_iter *iter) return 0; #endif + if (ext4_verity_inode(inode)) + return 0; + /* * If we are doing data journalling we don't support O_DIRECT */ diff --git a/fs/ext4/readpage.c b/fs/ext4/readpage.c index f461d75ac049f..d3dd1ff745db8 100644 --- a/fs/ext4/readpage.c +++ b/fs/ext4/readpage.c @@ -47,6 +47,11 @@ #include "ext4.h" +#define NUM_PREALLOC_POST_READ_CTXS 128 + +static struct kmem_cache *bio_post_read_ctx_cache; +static mempool_t *bio_post_read_ctx_pool; + static inline bool ext4_bio_encrypted(struct bio *bio) { #ifdef CONFIG_EXT4_FS_ENCRYPTION @@ -56,6 +61,124 @@ static inline bool ext4_bio_encrypted(struct bio *bio) #endif } +/* postprocessing steps for read bios */ +enum bio_post_read_step { + STEP_INITIAL = 0, + STEP_DECRYPT, + STEP_VERITY, +}; + +struct bio_post_read_ctx { + struct bio *bio; + struct work_struct work; + unsigned int cur_step; + unsigned int enabled_steps; +}; + +static void __read_end_io(struct bio *bio) +{ + struct page *page; + struct bio_vec *bv; + int i; + + bio_for_each_segment_all(bv, bio, i) { + page = bv->bv_page; + + /* PG_error was set if any post_read step failed */ + if (bio->bi_status || PageError(page)) { + ClearPageUptodate(page); + SetPageError(page); + } else { + SetPageUptodate(page); + } + unlock_page(page); + } + if (bio->bi_private) + mempool_free(bio->bi_private, bio_post_read_ctx_pool); + bio_put(bio); +} + +static void bio_post_read_processing(struct bio_post_read_ctx *ctx); + +static void decrypt_work(struct work_struct *work) +{ + struct bio_post_read_ctx *ctx = + container_of(work, struct bio_post_read_ctx, work); + + fscrypt_decrypt_bio(ctx->bio); + + bio_post_read_processing(ctx); +} + +static void verity_work(struct work_struct *work) +{ + struct bio_post_read_ctx *ctx = + container_of(work, struct bio_post_read_ctx, work); + + fsverity_verify_bio(ctx->bio); + + bio_post_read_processing(ctx); +} + +static void bio_post_read_processing(struct bio_post_read_ctx *ctx) +{ + /* + * We use different work queues for decryption and for verity because + * verity may require reading metadata pages that need decryption, and + * we shouldn't recurse to the same workqueue. + */ + switch (++ctx->cur_step) { + case STEP_DECRYPT: + if (ctx->enabled_steps & (1 << STEP_DECRYPT)) { + INIT_WORK(&ctx->work, decrypt_work); + fscrypt_enqueue_decrypt_work(&ctx->work); + return; + } + ctx->cur_step++; + /* fall-through */ + case STEP_VERITY: + if (ctx->enabled_steps & (1 << STEP_VERITY)) { + INIT_WORK(&ctx->work, verity_work); + fsverity_enqueue_verify_work(&ctx->work); + return; + } + ctx->cur_step++; + /* fall-through */ + default: + __read_end_io(ctx->bio); + } +} + +static struct bio_post_read_ctx *get_bio_post_read_ctx(struct inode *inode, + struct bio *bio, + pgoff_t index) +{ + unsigned int post_read_steps = 0; + struct bio_post_read_ctx *ctx = NULL; + + if (ext4_encrypted_inode(inode) && S_ISREG(inode->i_mode)) + post_read_steps |= 1 << STEP_DECRYPT; +#ifdef CONFIG_EXT4_FS_VERITY + if (inode->i_verity_info != NULL && + (index < ((i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT))) + post_read_steps |= 1 << STEP_VERITY; +#endif + if (post_read_steps) { + ctx = mempool_alloc(bio_post_read_ctx_pool, GFP_NOFS); + if (!ctx) + return ERR_PTR(-ENOMEM); + ctx->bio = bio; + ctx->enabled_steps = post_read_steps; + bio->bi_private = ctx; + } + return ctx; +} + +static bool bio_post_read_required(struct bio *bio) +{ + return bio->bi_private && !bio->bi_status; +} + /* * I/O completion handler for multipage BIOs. * @@ -70,30 +193,31 @@ static inline bool ext4_bio_encrypted(struct bio *bio) */ static void mpage_end_io(struct bio *bio) { - struct bio_vec *bv; - int i; + if (bio_post_read_required(bio)) { + struct bio_post_read_ctx *ctx = bio->bi_private; - if (ext4_bio_encrypted(bio)) { - if (bio->bi_status) { - fscrypt_release_ctx(bio->bi_private); - } else { - fscrypt_enqueue_decrypt_bio(bio->bi_private, bio); - return; - } + ctx->cur_step = STEP_INITIAL; + bio_post_read_processing(ctx); + return; } - bio_for_each_segment_all(bv, bio, i) { - struct page *page = bv->bv_page; + __read_end_io(bio); +} - if (!bio->bi_status) { - SetPageUptodate(page); - } else { - ClearPageUptodate(page); - SetPageError(page); - } - unlock_page(page); +static inline loff_t ext4_readpage_limit(struct inode *inode) +{ +#ifdef CONFIG_EXT4_FS_VERITY + if (ext4_verity_inode(inode)) { + if (inode->i_verity_info) + /* limit to end of metadata region */ + return fsverity_full_i_size(inode); + /* + * fsverity_info is currently being set up and no user reads are + * allowed yet. It's easiest to just not enforce a limit yet. + */ + return inode->i_sb->s_maxbytes; } - - bio_put(bio); +#endif + return i_size_read(inode); } int ext4_mpage_readpages(struct address_space *mapping, @@ -140,7 +264,8 @@ int ext4_mpage_readpages(struct address_space *mapping, block_in_file = (sector_t)page->index << (PAGE_SHIFT - blkbits); last_block = block_in_file + nr_pages * blocks_per_page; - last_block_in_file = (i_size_read(inode) + blocksize - 1) >> blkbits; + last_block_in_file = (ext4_readpage_limit(inode) + + blocksize - 1) >> blkbits; if (last_block > last_block_in_file) last_block = last_block_in_file; page_block = 0; @@ -217,6 +342,8 @@ int ext4_mpage_readpages(struct address_space *mapping, zero_user_segment(page, first_hole << blkbits, PAGE_SIZE); if (first_hole == 0) { + if (!fsverity_check_hole(inode, page)) + goto set_error_page; SetPageUptodate(page); unlock_page(page); goto next_page; @@ -240,19 +367,15 @@ int ext4_mpage_readpages(struct address_space *mapping, bio = NULL; } if (bio == NULL) { - struct fscrypt_ctx *ctx = NULL; + struct bio_post_read_ctx *ctx; - if (ext4_encrypted_inode(inode) && - S_ISREG(inode->i_mode)) { - ctx = fscrypt_get_ctx(inode, GFP_NOFS); - if (IS_ERR(ctx)) - goto set_error_page; - } bio = bio_alloc(GFP_KERNEL, min_t(int, nr_pages, BIO_MAX_PAGES)); - if (!bio) { - if (ctx) - fscrypt_release_ctx(ctx); + if (!bio) + goto set_error_page; + ctx = get_bio_post_read_ctx(inode, bio, page->index); + if (IS_ERR(ctx)) { + bio_put(bio); goto set_error_page; } bio_set_dev(bio, bdev); @@ -293,3 +416,27 @@ int ext4_mpage_readpages(struct address_space *mapping, submit_bio(bio); return 0; } + +int __init ext4_init_post_read_processing(void) +{ + bio_post_read_ctx_cache = KMEM_CACHE(bio_post_read_ctx, 0); + if (!bio_post_read_ctx_cache) + goto fail; + bio_post_read_ctx_pool = + mempool_create_slab_pool(NUM_PREALLOC_POST_READ_CTXS, + bio_post_read_ctx_cache); + if (!bio_post_read_ctx_pool) + goto fail_free_cache; + return 0; + +fail_free_cache: + kmem_cache_destroy(bio_post_read_ctx_cache); +fail: + return -ENOMEM; +} + +void ext4_exit_post_read_processing(void) +{ + mempool_destroy(bio_post_read_ctx_pool); + kmem_cache_destroy(bio_post_read_ctx_cache); +} diff --git a/fs/ext4/super.c b/fs/ext4/super.c index c4a66b64ea604..fb4e060f28ecb 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -6070,6 +6070,10 @@ static int __init ext4_init_fs(void) return err; err = ext4_init_pending(); + if (err) + goto out7; + + err = ext4_init_post_read_processing(); if (err) goto out6; @@ -6111,8 +6115,10 @@ static int __init ext4_init_fs(void) out4: ext4_exit_pageio(); out5: - ext4_exit_pending(); + ext4_exit_post_read_processing(); out6: + ext4_exit_pending(); +out7: ext4_exit_es(); return err; @@ -6129,6 +6135,7 @@ static void __exit ext4_exit_fs(void) ext4_exit_sysfs(); ext4_exit_system_zone(); ext4_exit_pageio(); + ext4_exit_post_read_processing(); ext4_exit_es(); ext4_exit_pending(); } From patchwork Thu Nov 1 22:52:30 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Eric Biggers X-Patchwork-Id: 10664597 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 1D49A14E2 for ; Thu, 1 Nov 2018 22:54:50 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 100D52C0D8 for ; Thu, 1 Nov 2018 22:54:50 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 0266F2C0F7; Thu, 1 Nov 2018 22:54:49 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.0 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 123EF2C0F7 for ; Thu, 1 Nov 2018 22:54:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728185AbeKBH7S (ORCPT ); Fri, 2 Nov 2018 03:59:18 -0400 Received: from mail.kernel.org ([198.145.29.99]:52192 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727645AbeKBH7S (ORCPT ); Fri, 2 Nov 2018 03:59:18 -0400 Received: from ebiggers-linuxstation.kir.corp.google.com (unknown [104.132.51.88]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 305F320880; Thu, 1 Nov 2018 22:54:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1541112858; bh=CpZV8zS2T/gVWNAj7g+e6IJ2U2OuHceoNoGOH2syyTY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=yjOkhhuhjaH7mB73i2ymVonYr30Nu2BH9lf6io01Rk2bS1KnMtVMw1urnceqXq33N b2IaNu0p3dw3QjcqLgnvf50Ps6gfPnzaYE3TrwszFRK3lrovJKMFBP6w/nsq8tSd4f p6O5ZAlJE8OMpu4mei8bfUwV9wxq4PZWHA1zrp5g= From: Eric Biggers To: linux-fscrypt@vger.kernel.org Cc: linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net, linux-integrity@vger.kernel.org, linux-kernel@vger.kernel.org, "Theodore Y . Ts'o" , Jaegeuk Kim , Victor Hsieh , Chandan Rajendra Subject: [PATCH v2 12/12] f2fs: fs-verity support Date: Thu, 1 Nov 2018 15:52:30 -0700 Message-Id: <20181101225230.88058-13-ebiggers@kernel.org> X-Mailer: git-send-email 2.19.1.568.g152ad8e336-goog In-Reply-To: <20181101225230.88058-1-ebiggers@kernel.org> References: <20181101225230.88058-1-ebiggers@kernel.org> MIME-Version: 1.0 Sender: linux-fscrypt-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fscrypt@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Eric Biggers Add fs-verity support to f2fs. fs-verity is a filesystem feature that enables transparent integrity protection and authentication of read-only files. It uses a dm-verity like mechanism at the file level: a Merkle tree is used to verify any block in the file in log(filesize) time. It is implemented mainly by helper functions in fs/verity/. See Documentation/filesystems/fsverity.rst for details. In f2fs, the main change is to the I/O path: ->readpage() and ->readpages() now verify data as it is read from verity files. Pages that fail verification are set to PG_error && !PG_uptodate, causing applications to see an I/O error. Hooks are also added to several other f2fs filesystem operations: * ->open(), to deny opening verity files for writing and to set up the fsverity_info to prepare for I/O * ->getattr() to set up the fsverity_info to make stat() show the original data size of verity files * ->setattr() to deny truncating verity files * update_inode() to write out the full file size rather than the original data size, since for verity files the in-memory ->i_size is overridden with the original data size. Finally, the FS_IOC_ENABLE_VERITY and FS_IOC_MEASURE_VERITY ioctls are wired up. On f2fs, these ioctls require that the filesystem has the 'verity' feature, i.e. it was created with 'mkfs.f2fs -O verity'. Like we did in ext4, in f2fs we choose to retain the fs-verity metadata past the end of the file rather than move it into an xattr, since in practice this results in the simplest and most efficient implementation. For example, it avoids needing to add support for external inode xattrs and for xattr encryption. Signed-off-by: Eric Biggers --- fs/f2fs/Kconfig | 20 +++++++++++++++++ fs/f2fs/data.c | 43 +++++++++++++++++++++++++++++++----- fs/f2fs/f2fs.h | 17 ++++++++++++--- fs/f2fs/file.c | 58 +++++++++++++++++++++++++++++++++++++++++++++++++ fs/f2fs/inode.c | 3 ++- fs/f2fs/super.c | 30 +++++++++++++++++++++++++ fs/f2fs/sysfs.c | 11 ++++++++++ 7 files changed, 173 insertions(+), 9 deletions(-) diff --git a/fs/f2fs/Kconfig b/fs/f2fs/Kconfig index 9a20ef42fadde..c8396c7220f2a 100644 --- a/fs/f2fs/Kconfig +++ b/fs/f2fs/Kconfig @@ -81,6 +81,26 @@ config F2FS_FS_ENCRYPTION efficient since it avoids caching the encrypted and decrypted pages in the page cache. +config F2FS_FS_VERITY + bool "F2FS Verity" + depends on F2FS_FS + select FS_VERITY + help + This option enables fs-verity for f2fs. fs-verity is the + dm-verity mechanism implemented at the file level. Userspace + can append a Merkle tree (hash tree) to a file, then enable + fs-verity on the file. f2fs will then transparently verify + any data read from the file against the Merkle tree. The file + is also made read-only. + + This serves as an integrity check, but the availability of the + Merkle tree root hash also allows efficiently supporting + various use cases where normally the whole file would need to + be hashed at once, such as auditing and authenticity + verification (appraisal). + + If unsure, say N. + config F2FS_IO_TRACE bool "F2FS IO tracer" depends on F2FS_FS diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c index b293cb3e27a22..09d9fc1676a7e 100644 --- a/fs/f2fs/data.c +++ b/fs/f2fs/data.c @@ -73,6 +73,7 @@ static enum count_type __read_io_type(struct page *page) enum bio_post_read_step { STEP_INITIAL = 0, STEP_DECRYPT, + STEP_VERITY, }; struct bio_post_read_ctx { @@ -119,8 +120,23 @@ static void decrypt_work(struct work_struct *work) bio_post_read_processing(ctx); } +static void verity_work(struct work_struct *work) +{ + struct bio_post_read_ctx *ctx = + container_of(work, struct bio_post_read_ctx, work); + + fsverity_verify_bio(ctx->bio); + + bio_post_read_processing(ctx); +} + static void bio_post_read_processing(struct bio_post_read_ctx *ctx) { + /* + * We use different work queues for decryption and for verity because + * verity may require reading metadata pages that need decryption, and + * we shouldn't recurse to the same workqueue. + */ switch (++ctx->cur_step) { case STEP_DECRYPT: if (ctx->enabled_steps & (1 << STEP_DECRYPT)) { @@ -130,6 +146,14 @@ static void bio_post_read_processing(struct bio_post_read_ctx *ctx) } ctx->cur_step++; /* fall-through */ + case STEP_VERITY: + if (ctx->enabled_steps & (1 << STEP_VERITY)) { + INIT_WORK(&ctx->work, verity_work); + fsverity_enqueue_verify_work(&ctx->work); + return; + } + ctx->cur_step++; + /* fall-through */ default: __read_end_io(ctx->bio); } @@ -566,7 +590,8 @@ void f2fs_submit_page_write(struct f2fs_io_info *fio) } static struct bio *f2fs_grab_read_bio(struct inode *inode, block_t blkaddr, - unsigned nr_pages, unsigned op_flag) + unsigned nr_pages, unsigned op_flag, + pgoff_t first_idx) { struct f2fs_sb_info *sbi = F2FS_I_SB(inode); struct bio *bio; @@ -585,6 +610,11 @@ static struct bio *f2fs_grab_read_bio(struct inode *inode, block_t blkaddr, if (f2fs_encrypted_file(inode)) post_read_steps |= 1 << STEP_DECRYPT; +#ifdef CONFIG_F2FS_FS_VERITY + if (inode->i_verity_info != NULL && + (first_idx < ((i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT))) + post_read_steps |= 1 << STEP_VERITY; +#endif if (post_read_steps) { ctx = mempool_alloc(bio_post_read_ctx_pool, GFP_NOFS); if (!ctx) { @@ -603,7 +633,7 @@ static struct bio *f2fs_grab_read_bio(struct inode *inode, block_t blkaddr, static int f2fs_submit_page_read(struct inode *inode, struct page *page, block_t blkaddr) { - struct bio *bio = f2fs_grab_read_bio(inode, blkaddr, 1, 0); + struct bio *bio = f2fs_grab_read_bio(inode, blkaddr, 1, 0, page->index); if (IS_ERR(bio)) return PTR_ERR(bio); @@ -1540,8 +1570,8 @@ static int f2fs_mpage_readpages(struct address_space *mapping, block_in_file = (sector_t)page->index; last_block = block_in_file + nr_pages; - last_block_in_file = (i_size_read(inode) + blocksize - 1) >> - blkbits; + last_block_in_file = (fsverity_full_i_size(inode) + + blocksize - 1) >> blkbits; if (last_block > last_block_in_file) last_block = last_block_in_file; @@ -1582,6 +1612,8 @@ static int f2fs_mpage_readpages(struct address_space *mapping, goto set_error_page; } else { zero_user_segment(page, 0, PAGE_SIZE); + if (!fsverity_check_hole(inode, page)) + goto set_error_page; if (!PageUptodate(page)) SetPageUptodate(page); unlock_page(page); @@ -1600,7 +1632,8 @@ static int f2fs_mpage_readpages(struct address_space *mapping, } if (bio == NULL) { bio = f2fs_grab_read_bio(inode, block_nr, nr_pages, - is_readahead ? REQ_RAHEAD : 0); + is_readahead ? REQ_RAHEAD : 0, + page->index); if (IS_ERR(bio)) { bio = NULL; goto set_error_page; diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h index 1e031971a466c..dadb5f468f20e 100644 --- a/fs/f2fs/f2fs.h +++ b/fs/f2fs/f2fs.h @@ -27,6 +27,9 @@ #define __FS_HAS_ENCRYPTION IS_ENABLED(CONFIG_F2FS_FS_ENCRYPTION) #include +#define __FS_HAS_VERITY IS_ENABLED(CONFIG_F2FS_FS_VERITY) +#include + #ifdef CONFIG_F2FS_CHECK_FS #define f2fs_bug_on(sbi, condition) BUG_ON(condition) #else @@ -149,7 +152,7 @@ struct f2fs_mount_info { #define F2FS_FEATURE_QUOTA_INO 0x0080 #define F2FS_FEATURE_INODE_CRTIME 0x0100 #define F2FS_FEATURE_LOST_FOUND 0x0200 -#define F2FS_FEATURE_VERITY 0x0400 /* reserved */ +#define F2FS_FEATURE_VERITY 0x0400 #define F2FS_FEATURE_SB_CHKSUM 0x0800 #define F2FS_HAS_FEATURE(sb, mask) \ @@ -623,7 +626,7 @@ enum { #define FADVISE_ENC_NAME_BIT 0x08 #define FADVISE_KEEP_SIZE_BIT 0x10 #define FADVISE_HOT_BIT 0x20 -#define FADVISE_VERITY_BIT 0x40 /* reserved */ +#define FADVISE_VERITY_BIT 0x40 #define FADVISE_MODIFIABLE_BITS (FADVISE_COLD_BIT | FADVISE_HOT_BIT) @@ -643,6 +646,8 @@ enum { #define file_is_hot(inode) is_file(inode, FADVISE_HOT_BIT) #define file_set_hot(inode) set_file(inode, FADVISE_HOT_BIT) #define file_clear_hot(inode) clear_file(inode, FADVISE_HOT_BIT) +#define file_is_verity(inode) is_file(inode, FADVISE_VERITY_BIT) +#define file_set_verity(inode) set_file(inode, FADVISE_VERITY_BIT) #define DEF_DIR_LEVEL 0 @@ -3449,13 +3454,18 @@ static inline void f2fs_set_encrypted_inode(struct inode *inode) #endif } +static inline bool f2fs_verity_file(struct inode *inode) +{ + return file_is_verity(inode); +} + /* * Returns true if the reads of the inode's data need to undergo some * postprocessing step, like decryption or authenticity verification. */ static inline bool f2fs_post_read_required(struct inode *inode) { - return f2fs_encrypted_file(inode); + return f2fs_encrypted_file(inode) || f2fs_verity_file(inode); } #define F2FS_FEATURE_FUNCS(name, flagname) \ @@ -3473,6 +3483,7 @@ F2FS_FEATURE_FUNCS(flexible_inline_xattr, FLEXIBLE_INLINE_XATTR); F2FS_FEATURE_FUNCS(quota_ino, QUOTA_INO); F2FS_FEATURE_FUNCS(inode_crtime, INODE_CRTIME); F2FS_FEATURE_FUNCS(lost_found, LOST_FOUND); +F2FS_FEATURE_FUNCS(verity, VERITY); F2FS_FEATURE_FUNCS(sb_chksum, SB_CHKSUM); #ifdef CONFIG_BLK_DEV_ZONED diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c index 88b124677189b..87794b2a45ff8 100644 --- a/fs/f2fs/file.c +++ b/fs/f2fs/file.c @@ -491,6 +491,12 @@ static int f2fs_file_open(struct inode *inode, struct file *filp) if (err) return err; + if (f2fs_verity_file(inode)) { + err = fsverity_file_open(inode, filp); + if (err) + return err; + } + filp->f_mode |= FMODE_NOWAIT; return dquot_file_open(inode, filp); @@ -695,6 +701,22 @@ int f2fs_getattr(const struct path *path, struct kstat *stat, struct f2fs_inode *ri; unsigned int flags; + if (f2fs_verity_file(inode)) { + /* + * For fs-verity we need to override i_size with the original + * data i_size. This requires I/O to the file which with + * fscrypt requires that the key be set up. But, if the key is + * unavailable just continue on without the i_size override. + */ + int err = fscrypt_require_key(inode); + + if (!err) { + err = fsverity_prepare_getattr(inode); + if (err) + return err; + } + } + if (f2fs_has_extra_attr(inode) && f2fs_sb_has_inode_crtime(inode->i_sb) && F2FS_FITS_IN_INODE(ri, fi->i_extra_isize, i_crtime)) { @@ -778,6 +800,12 @@ int f2fs_setattr(struct dentry *dentry, struct iattr *attr) if (err) return err; + if (f2fs_verity_file(inode)) { + err = fsverity_prepare_setattr(dentry, attr); + if (err) + return err; + } + if (is_quota_modification(inode, attr)) { err = dquot_initialize(inode); if (err) @@ -2954,6 +2982,30 @@ static int f2fs_ioc_precache_extents(struct file *filp, unsigned long arg) return f2fs_precache_extents(file_inode(filp)); } +static int f2fs_ioc_enable_verity(struct file *filp, unsigned long arg) +{ + struct inode *inode = file_inode(filp); + + f2fs_update_time(F2FS_I_SB(inode), REQ_TIME); + + if (!f2fs_sb_has_verity(inode->i_sb)) { + f2fs_msg(inode->i_sb, KERN_WARNING, + "Can't enable fs-verity on inode %lu: the fs-verity feature is disabled on this filesystem.\n", + inode->i_ino); + return -EOPNOTSUPP; + } + + return fsverity_ioctl_enable(filp, (const void __user *)arg); +} + +static int f2fs_ioc_measure_verity(struct file *filp, unsigned long arg) +{ + if (!f2fs_sb_has_verity(file_inode(filp)->i_sb)) + return -EOPNOTSUPP; + + return fsverity_ioctl_measure(filp, (void __user *)arg); +} + long f2fs_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) { if (unlikely(f2fs_cp_error(F2FS_I_SB(file_inode(filp))))) @@ -3010,6 +3062,10 @@ long f2fs_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) return f2fs_ioc_set_pin_file(filp, arg); case F2FS_IOC_PRECACHE_EXTENTS: return f2fs_ioc_precache_extents(filp, arg); + case FS_IOC_ENABLE_VERITY: + return f2fs_ioc_enable_verity(filp, arg); + case FS_IOC_MEASURE_VERITY: + return f2fs_ioc_measure_verity(filp, arg); default: return -ENOTTY; } @@ -3117,6 +3173,8 @@ long f2fs_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg) case F2FS_IOC_GET_PIN_FILE: case F2FS_IOC_SET_PIN_FILE: case F2FS_IOC_PRECACHE_EXTENTS: + case FS_IOC_ENABLE_VERITY: + case FS_IOC_MEASURE_VERITY: break; default: return -ENOIOCTLCMD; diff --git a/fs/f2fs/inode.c b/fs/f2fs/inode.c index 91ceee0ed4c40..ddef483ad689d 100644 --- a/fs/f2fs/inode.c +++ b/fs/f2fs/inode.c @@ -509,7 +509,7 @@ void f2fs_update_inode(struct inode *inode, struct page *node_page) ri->i_uid = cpu_to_le32(i_uid_read(inode)); ri->i_gid = cpu_to_le32(i_gid_read(inode)); ri->i_links = cpu_to_le32(inode->i_nlink); - ri->i_size = cpu_to_le64(i_size_read(inode)); + ri->i_size = cpu_to_le64(fsverity_full_i_size(inode)); ri->i_blocks = cpu_to_le64(SECTOR_TO_BLOCK(inode->i_blocks) + 1); if (et) { @@ -732,6 +732,7 @@ void f2fs_evict_inode(struct inode *inode) } out_clear: fscrypt_put_encryption_info(inode); + fsverity_cleanup_inode(inode); clear_inode(inode); } diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c index af58b2cc21b81..adf38c1b64141 100644 --- a/fs/f2fs/super.c +++ b/fs/f2fs/super.c @@ -2197,6 +2197,33 @@ static const struct fscrypt_operations f2fs_cryptops = { }; #endif +#ifdef CONFIG_F2FS_FS_VERITY +static int f2fs_set_verity(struct inode *inode, loff_t data_i_size) +{ + int err; + + err = f2fs_convert_inline_inode(inode); + if (err) + return err; + + file_set_verity(inode); + f2fs_mark_inode_dirty_sync(inode, true); + return 0; +} + +static int f2fs_get_metadata_end(struct inode *inode, loff_t *metadata_end_ret) +{ + /* f2fs on-disk size is the full file size including verity metadata */ + *metadata_end_ret = i_size_read(inode); + return 0; +} + +static const struct fsverity_operations f2fs_verityops = { + .set_verity = f2fs_set_verity, + .get_metadata_end = f2fs_get_metadata_end, +}; +#endif /* CONFIG_F2FS_FS_VERITY */ + static struct inode *f2fs_nfs_get_inode(struct super_block *sb, u64 ino, u32 generation) { @@ -3118,6 +3145,9 @@ static int f2fs_fill_super(struct super_block *sb, void *data, int silent) sb->s_op = &f2fs_sops; #ifdef CONFIG_F2FS_FS_ENCRYPTION sb->s_cop = &f2fs_cryptops; +#endif +#ifdef CONFIG_F2FS_FS_VERITY + sb->s_vop = &f2fs_verityops; #endif sb->s_xattr = f2fs_xattr_handlers; sb->s_export_op = &f2fs_export_ops; diff --git a/fs/f2fs/sysfs.c b/fs/f2fs/sysfs.c index b777cbdd796ba..5599c9ac4426d 100644 --- a/fs/f2fs/sysfs.c +++ b/fs/f2fs/sysfs.c @@ -117,6 +117,9 @@ static ssize_t features_show(struct f2fs_attr *a, if (f2fs_sb_has_lost_found(sb)) len += snprintf(buf + len, PAGE_SIZE - len, "%s%s", len ? ", " : "", "lost_found"); + if (f2fs_sb_has_verity(sb)) + len += snprintf(buf + len, PAGE_SIZE - len, "%s%s", + len ? ", " : "", "verity"); if (f2fs_sb_has_sb_chksum(sb)) len += snprintf(buf + len, PAGE_SIZE - len, "%s%s", len ? ", " : "", "sb_checksum"); @@ -337,6 +340,7 @@ enum feat_id { FEAT_QUOTA_INO, FEAT_INODE_CRTIME, FEAT_LOST_FOUND, + FEAT_VERITY, FEAT_SB_CHECKSUM, }; @@ -354,6 +358,7 @@ static ssize_t f2fs_feature_show(struct f2fs_attr *a, case FEAT_QUOTA_INO: case FEAT_INODE_CRTIME: case FEAT_LOST_FOUND: + case FEAT_VERITY: case FEAT_SB_CHECKSUM: return snprintf(buf, PAGE_SIZE, "supported\n"); } @@ -439,6 +444,9 @@ F2FS_FEATURE_RO_ATTR(flexible_inline_xattr, FEAT_FLEXIBLE_INLINE_XATTR); F2FS_FEATURE_RO_ATTR(quota_ino, FEAT_QUOTA_INO); F2FS_FEATURE_RO_ATTR(inode_crtime, FEAT_INODE_CRTIME); F2FS_FEATURE_RO_ATTR(lost_found, FEAT_LOST_FOUND); +#ifdef CONFIG_F2FS_FS_VERITY +F2FS_FEATURE_RO_ATTR(verity, FEAT_VERITY); +#endif F2FS_FEATURE_RO_ATTR(sb_checksum, FEAT_SB_CHECKSUM); #define ATTR_LIST(name) (&f2fs_attr_##name.attr) @@ -499,6 +507,9 @@ static struct attribute *f2fs_feat_attrs[] = { ATTR_LIST(quota_ino), ATTR_LIST(inode_crtime), ATTR_LIST(lost_found), +#ifdef CONFIG_F2FS_FS_VERITY + ATTR_LIST(verity), +#endif ATTR_LIST(sb_checksum), NULL, };