From patchwork Sun Jul 24 00:53:53 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sweet Tea Dorminy X-Patchwork-Id: 12927399 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 18689C43334 for ; Sun, 24 Jul 2022 00:54:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239412AbiGXAyz (ORCPT ); Sat, 23 Jul 2022 20:54:55 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38708 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239330AbiGXAyn (ORCPT ); Sat, 23 Jul 2022 20:54:43 -0400 Received: from box.fidei.email (box.fidei.email [IPv6:2605:2700:0:2:a800:ff:feba:dc44]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 56F3614D3B; Sat, 23 Jul 2022 17:54:40 -0700 (PDT) Received: from authenticated-user (box.fidei.email [71.19.144.250]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)) (No client certificate requested) by box.fidei.email (Postfix) with ESMTPSA id A854E807A4; Sat, 23 Jul 2022 20:54:39 -0400 (EDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=dorminy.me; s=mail; t=1658624080; bh=H09wRzRdnVbe5aQ6GhHltPGBSjyeA7RClzHlhNEwV60=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=cber+TG8gZXbPOdexIZP/4rMr/R033ZlB96fEUBt0RgF7NbgtPahm8ezHXSjRwDJH K+PrnuX7j9psDkXrGxSvfXj5TC+gxkw0EVF7yWAhCMhRd6zVjKSZai+e+T1ks5ibL8 vagnFol/fwuofq8KsAPR5blDoyYOaLcu5v9mxRhItiao7EWbklu6I4udwZ4zO1lAZ+ Q/U9Il/u8O3b+1kr5tC1AIptljJbGsZMjG1p0WYUKMW6XZ1zQyaSLlr2kdA8hui1gI t3smedM6WcwiF+St2y7iOepUkGfjF3RZMa1QLv8G+RTG4zdpLtIUxElAugO9s0VPSP GfApMwUiDGkkw== From: Sweet Tea Dorminy To: Chris Mason , Josef Bacik , David Sterba , linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org, osandov@osandov.com, kernel-team@fb.com Cc: Sweet Tea Dorminy Subject: [PATCH RFC v2 08/16] btrfs: add a subvolume flag for whole-volume encryption Date: Sat, 23 Jul 2022 20:53:53 -0400 Message-Id: <17d05cf8a58bd2afc5c0ea7c3b9ebeb069aa57c8.1658623319.git.sweettea-kernel@dorminy.me> In-Reply-To: References: MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org From: Omar Sandoval In many cases, we will want to encrypt all of a subvolume; adding a subvolume flag allows this. However, since an unencrypted subvolume would be unable to read encrypted data, encrypted subvolumes should only be snapshottable to other encrypted subvolumes. Signed-off-by: Omar Sandoval Signed-off-by: Sweet Tea Dorminy --- fs/btrfs/ctree.h | 3 + fs/btrfs/fscrypt.c | 160 ++++++++++++++++++++++++++++++++ fs/btrfs/inode.c | 38 ++++++++ fs/btrfs/ioctl.c | 10 +- fs/btrfs/tree-checker.c | 1 + include/uapi/linux/btrfs_tree.h | 10 ++ 6 files changed, 221 insertions(+), 1 deletion(-) diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h index ac6b8973a273..cb7ded64fee6 100644 --- a/fs/btrfs/ctree.h +++ b/fs/btrfs/ctree.h @@ -33,6 +33,7 @@ #include "extent-io-tree.h" #include "extent_io.h" #include "extent_map.h" +#include "fscrypt.h" #include "async-thread.h" #include "block-rsv.h" #include "locking.h" @@ -1586,6 +1587,7 @@ do { \ #define BTRFS_INODE_NOATIME (1U << 9) #define BTRFS_INODE_DIRSYNC (1U << 10) #define BTRFS_INODE_COMPRESS (1U << 11) +#define BTRFS_INODE_FSCRYPT_CONTEXT (1U << 12) #define BTRFS_INODE_ROOT_ITEM_INIT (1U << 31) @@ -1602,6 +1604,7 @@ do { \ BTRFS_INODE_NOATIME | \ BTRFS_INODE_DIRSYNC | \ BTRFS_INODE_COMPRESS | \ + BTRFS_INODE_FSCRYPT_CONTEXT | \ BTRFS_INODE_ROOT_ITEM_INIT) #define BTRFS_INODE_RO_VERITY (1U << 0) diff --git a/fs/btrfs/fscrypt.c b/fs/btrfs/fscrypt.c index 9829d280a6bc..0e92acdac6d7 100644 --- a/fs/btrfs/fscrypt.c +++ b/fs/btrfs/fscrypt.c @@ -3,8 +3,13 @@ * Copyright (C) 2020 Facebook */ +#include #include "ctree.h" +#include "btrfs_inode.h" +#include "disk-io.h" #include "fscrypt.h" +#include "transaction.h" +#include "xattr.h" /* fscrypt_match_name() but for an extent_buffer. */ bool btrfs_fscrypt_match_name(const struct fscrypt_name *fname, @@ -31,5 +36,160 @@ bool btrfs_fscrypt_match_name(const struct fscrypt_name *fname, return !memcmp(digest, nokey_name->sha256, sizeof(digest)); } +static int btrfs_fscrypt_get_context(struct inode *inode, void *ctx, size_t len) +{ + struct btrfs_root *root = BTRFS_I(inode)->root; + struct inode *put_inode = NULL; + struct btrfs_key key; + struct btrfs_path *path; + struct extent_buffer *leaf; + unsigned long ptr; + int ret; + + if (S_ISREG(inode->i_mode) && + (btrfs_root_flags(&root->root_item) & BTRFS_ROOT_SUBVOL_FSCRYPT)) { + /* TODO: maybe cache the item */ + inode = btrfs_iget(inode->i_sb, BTRFS_FIRST_FREE_OBJECTID, + root); + if (IS_ERR(inode)) + return PTR_ERR(inode); + put_inode = inode; + } + + path = btrfs_alloc_path(); + if (!path) + return -ENOMEM; + + key = (struct btrfs_key) { + .objectid = btrfs_ino(BTRFS_I(inode)), + .type = BTRFS_FSCRYPT_CTXT_ITEM_KEY, + .offset = 0, + }; + + ret = btrfs_search_slot(NULL, BTRFS_I(inode)->root, &key, path, 0, 0); + if (ret) { + len = -EINVAL; + goto out; + } + + leaf = path->nodes[0]; + ptr = btrfs_item_ptr_offset(leaf, path->slots[0]); + /* fscrypt provides max context length, but it could be less */ + len = min_t(size_t, len, btrfs_item_size(leaf, path->slots[0])); + read_extent_buffer(leaf, ctx, ptr, len); + +out: + btrfs_free_path(path); + iput(put_inode); + return len; +} + +static int btrfs_fscrypt_set_context(struct inode *inode, const void *ctx, + size_t len, void *fs_data) +{ + struct btrfs_root *root = BTRFS_I(inode)->root; + struct btrfs_trans_handle *trans; + int is_subvolume = inode->i_ino == BTRFS_FIRST_FREE_OBJECTID; + int ret; + struct btrfs_path *path; + struct btrfs_key key = { + .objectid = btrfs_ino(BTRFS_I(inode)), + .type = BTRFS_FSCRYPT_CTXT_ITEM_KEY, + .offset = 0, + }; + + /* + * If the whole subvolume is encrypted, we can get the policy for + * regular files from the root inode. + */ + if (S_ISREG(inode->i_mode) && + (btrfs_root_flags(&root->root_item) & BTRFS_ROOT_SUBVOL_FSCRYPT)) + return 0; + + if (fs_data) { + /* + * We are setting the context as part of an existing + * transaction. This happens when we are inheriting the context + * for a new inode. + */ + trans = fs_data; + } else { + /* + * 1 for the inode item + * 1 for the root item if the inode is a subvolume + */ + trans = btrfs_start_transaction(root, 1 + is_subvolume); + if (IS_ERR(trans)) + return PTR_ERR(trans); + } + + path = btrfs_alloc_path(); + if (!path) + return -ENOMEM; + ret = btrfs_search_slot(trans, BTRFS_I(inode)->root, &key, path, 0, 1); + if (ret == 0) { + struct extent_buffer *leaf = path->nodes[0]; + unsigned long ptr = btrfs_item_ptr_offset(leaf, path->slots[0]); + len = min_t(size_t, len, btrfs_item_size(leaf, path->slots[0])); + write_extent_buffer(leaf, ctx, ptr, len); + btrfs_mark_buffer_dirty(leaf); + btrfs_free_path(path); + goto out; + } else if (ret < 0) { + goto out; + } + btrfs_free_path(path); + + ret = btrfs_insert_item(trans, BTRFS_I(inode)->root, &key, (void *) ctx, len); + if (ret) + goto out; + + BTRFS_I(inode)->flags |= BTRFS_INODE_FSCRYPT_CONTEXT; + btrfs_sync_inode_flags_to_i_flags(inode); + if (!fs_data) { + inode_inc_iversion(inode); + inode->i_ctime = current_time(inode); + ret = btrfs_update_inode(trans, root, BTRFS_I(inode)); + if (ret) + goto out; + /* + * For new subvolumes, the root item is already initialized with + * the BTRFS_ROOT_SUBVOL_FSCRYPT flag. + */ + if (is_subvolume) { + u64 root_flags = btrfs_root_flags(&root->root_item); + + btrfs_set_root_flags(&root->root_item, + root_flags | + BTRFS_ROOT_SUBVOL_FSCRYPT); + ret = btrfs_update_root(trans, root->fs_info->tree_root, + &root->root_key, + &root->root_item); + } + } +out: + if (fs_data) + return ret; + + if (ret) + btrfs_abort_transaction(trans, ret); + else + btrfs_end_transaction(trans); + return ret; +} + +static bool btrfs_fscrypt_empty_dir(struct inode *inode) +{ + /* + * We don't care about turning on encryption on a non-empty directory + * so we always return true. + */ + return true; +} + const struct fscrypt_operations btrfs_fscrypt_ops = { + .key_prefix = "btrfs:", + .get_context = btrfs_fscrypt_get_context, + .set_context = btrfs_fscrypt_set_context, + .empty_dir = btrfs_fscrypt_empty_dir, }; diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 638943ea3471..4f1382de515c 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c @@ -6281,6 +6281,34 @@ int btrfs_new_inode_prepare(struct btrfs_new_inode_args *args, struct inode *inode = args->inode; int ret; + if (fscrypt_is_nokey_name(args->dentry)) + return -ENOKEY; + + if (IS_ENCRYPTED(dir) && + !(BTRFS_I(dir)->flags & BTRFS_INODE_FSCRYPT_CONTEXT)) { + struct inode *root_inode; + bool encrypt; + + root_inode = btrfs_iget(inode->i_sb, BTRFS_FIRST_FREE_OBJECTID, + BTRFS_I(dir)->root); + if (IS_ERR(root_inode)) + return PTR_ERR(root_inode); + /* + * TODO: perhaps instead of faking making a new dir to get a + * new context, it would be better to expose + * fscrypt_setup_encryption_info() for our use. + */ + ret = fscrypt_prepare_new_inode(root_inode, dir, &encrypt); + if (!ret) { + ret = fscrypt_set_context(dir, NULL); + if (ret) + fscrypt_put_encryption_info(dir); + } + iput(root_inode); + if (ret) + return ret; + } + if (!args->orphan) { ret = fscrypt_setup_filename(dir, &args->dentry->d_name, 0, &args->fname); @@ -6314,6 +6342,8 @@ int btrfs_new_inode_prepare(struct btrfs_new_inode_args *args, if (dir->i_security) (*trans_num_items)++; #endif + if (args->encrypt) + (*trans_num_items)++; /* 1 to add fscrypt item */ if (args->orphan) { /* 1 to add orphan item */ (*trans_num_items)++; @@ -6567,6 +6597,14 @@ int btrfs_create_new_inode(struct btrfs_trans_handle *trans, } } + if (args->encrypt) { + ret = fscrypt_set_context(inode, trans); + if (ret) { + btrfs_abort_transaction(trans, ret); + goto discard; + } + } + inode_tree_add(inode); trace_btrfs_inode_new(inode); diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c index 10b8db56edda..8f5b65c43c8d 100644 --- a/fs/btrfs/ioctl.c +++ b/fs/btrfs/ioctl.c @@ -658,7 +658,8 @@ static noinline int create_subvol(struct user_namespace *mnt_userns, fs_info->nodesize); btrfs_set_stack_inode_mode(inode_item, S_IFDIR | 0755); - btrfs_set_root_flags(root_item, 0); + btrfs_set_root_flags(root_item, new_inode_args.encrypt ? + BTRFS_ROOT_SUBVOL_FSCRYPT : 0); btrfs_set_root_limit(root_item, 0); btrfs_set_stack_inode_flags(inode_item, BTRFS_INODE_ROOT_ITEM_INIT); @@ -787,6 +788,13 @@ static int create_snapshot(struct btrfs_root *root, struct inode *dir, return -ETXTBSY; } + if ((btrfs_root_flags(&root->root_item) & BTRFS_ROOT_SUBVOL_FSCRYPT) && + !IS_ENCRYPTED(dir)) { + btrfs_warn(fs_info, + "cannot snapshot encrypted volume to unencrypted destination"); + return -EXDEV; + } + pending_snapshot = kzalloc(sizeof(*pending_snapshot), GFP_KERNEL); if (!pending_snapshot) return -ENOMEM; diff --git a/fs/btrfs/tree-checker.c b/fs/btrfs/tree-checker.c index f861cc52be41..6f8e53d0cd6e 100644 --- a/fs/btrfs/tree-checker.c +++ b/fs/btrfs/tree-checker.c @@ -1124,6 +1124,7 @@ static int check_root_item(struct extent_buffer *leaf, struct btrfs_key *key, struct btrfs_fs_info *fs_info = leaf->fs_info; struct btrfs_root_item ri = { 0 }; const u64 valid_root_flags = BTRFS_ROOT_SUBVOL_RDONLY | + BTRFS_ROOT_SUBVOL_FSCRYPT | BTRFS_ROOT_SUBVOL_DEAD; int ret; diff --git a/include/uapi/linux/btrfs_tree.h b/include/uapi/linux/btrfs_tree.h index 428ae75b9f73..da44d3355385 100644 --- a/include/uapi/linux/btrfs_tree.h +++ b/include/uapi/linux/btrfs_tree.h @@ -144,6 +144,8 @@ #define BTRFS_VERITY_DESC_ITEM_KEY 36 #define BTRFS_VERITY_MERKLE_ITEM_KEY 37 +#define BTRFS_FSCRYPT_CTXT_ITEM_KEY 41 + #define BTRFS_ORPHAN_ITEM_KEY 48 /* reserve 2-15 close to the inode for later flexibility */ @@ -633,6 +635,8 @@ struct btrfs_dir_item { } __attribute__ ((__packed__)); #define BTRFS_ROOT_SUBVOL_RDONLY (1ULL << 0) +/* Top-level subvolume directory is encrypted with fscrypt. */ +#define BTRFS_ROOT_SUBVOL_FSCRYPT (1ULL << 1) /* * Internal in-memory flag that a subvolume has been marked for deletion but @@ -788,6 +792,12 @@ enum { BTRFS_NR_FILE_EXTENT_TYPES = 3, }; +enum { + BTRFS_ENCRYPTION_NONE, + BTRFS_ENCRYPTION_FSCRYPT, + BTRFS_NR_ENCRYPTION_TYPES, +}; + struct btrfs_file_extent_item { /* * transaction id that created this extent