From patchwork Thu Aug 27 06:35:20 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Lokesh Gidra X-Patchwork-Id: 11740019 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 938EF1731 for ; Thu, 27 Aug 2020 06:36:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6F4A422B47 for ; Thu, 27 Aug 2020 06:36:05 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=google.com header.i=@google.com header.b="EePMABCa" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727924AbgH0GgD (ORCPT ); Thu, 27 Aug 2020 02:36:03 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40130 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727883AbgH0Gfb (ORCPT ); Thu, 27 Aug 2020 02:35:31 -0400 Received: from mail-qk1-x74a.google.com (mail-qk1-x74a.google.com [IPv6:2607:f8b0:4864:20::74a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 93603C061265 for ; Wed, 26 Aug 2020 23:35:30 -0700 (PDT) Received: by mail-qk1-x74a.google.com with SMTP id a19so2522914qka.15 for ; Wed, 26 Aug 2020 23:35:30 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=sender:date:in-reply-to:message-id:mime-version:references:subject :from:to:cc; bh=q7k4YlygUXBnUpaNryf76XmtLPOUkh9dzPAGPuEoNlE=; b=EePMABCaiFWi+k7qQJvi/38gq8HYgxG7MEIpXiDuwihmGdMt4dzeXcnjUdAJFdxgYf dTOWDCetNdOeOeOlcZ94ZT8v5DTDYEA4imPvM3wahPvuxPiaud5Q+tz690/LYiXbEJIk +vO3CiogiLV+6UJQPXWgDYkKDorIsmEGS0CkgWoW2OqVNUZbaP761EAJOOaf6kCsqijd NNoQAT3Kl/89R8wAIDPTf/BfMPtAY64oEqyLA2kIlnJvwR7Hsra50vLIDOVI3BNJ/E+n 9Ur8++z2wYlPH4UqnRr9G1N2sw9c1pmoF0nN7hwciKyzhNU579/Qkyq0NQbvnTDYT71q pxzQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=q7k4YlygUXBnUpaNryf76XmtLPOUkh9dzPAGPuEoNlE=; b=UbW+S/WoW/doyUDOkh5DL+YFCw9jAtXkU3Vt8FwdsryAiT/uhb4SFmORUCyTFCruRt EtJczYK1MWK1kN7azZt2Huj2aJhGLEH25cXH4fe/27sFcfJX8rzbpYiepfPFST+RGBaP Qbz8/xZMGLw57oMbT0sVjhfDQTJF26Ee4y6KvkwNLn9xTD/8J26HilDwh8g3GcvRVLph 5ITfOKJP0iqHus+vrsDfQl4tFfX4eOwTCJKXurECsaWCK+55bMVPyNCcwBEkIbUYycz9 c6Jf2WT35cHO6T3Cegdq9uk2i9rZt/Byq5ublA2MoZDzX+dwYV+v3yrrpXAIGHHzInsh Pjcg== X-Gm-Message-State: AOAM533mMmH+UiQ11gul75sdjk5ZiD1z1hD2oA4TCeXY6X0fcn7rgBIS FP7wxBljd9vxwY5Uq6UQhFRqvDvM3xj24cLozQ== X-Google-Smtp-Source: ABdhPJz8wlk4ZeGbCzOGE2qcvaAMhji0L2Kri9CBUljFRsZViaSrhlSkbag5KOgV41BwCcM4wJZq433QAbh+KfxZXg== X-Received: from lg.mtv.corp.google.com ([100.89.4.209]) (user=lokeshgidra job=sendgmr) by 2002:a05:6214:8a:: with SMTP id n10mr17547100qvr.13.1598510129699; Wed, 26 Aug 2020 23:35:29 -0700 (PDT) Date: Wed, 26 Aug 2020 23:35:20 -0700 In-Reply-To: <20200827063522.2563293-1-lokeshgidra@google.com> Message-Id: <20200827063522.2563293-2-lokeshgidra@google.com> Mime-Version: 1.0 References: <20200827063522.2563293-1-lokeshgidra@google.com> X-Mailer: git-send-email 2.28.0.297.g1956fa8f8d-goog Subject: [PATCH v8 1/3] Add a new LSM-supporting anonymous inode interface From: Lokesh Gidra To: Alexander Viro , James Morris , Stephen Smalley , Casey Schaufler , Eric Biggers Cc: "Serge E. Hallyn" , Paul Moore , Eric Paris , Lokesh Gidra , Daniel Colascione , Kees Cook , "Eric W. Biederman" , KP Singh , David Howells , Thomas Cedeno , Anders Roxell , Sami Tolvanen , Matthew Garrett , Aaron Goidel , Randy Dunlap , "Joel Fernandes (Google)" , YueHaibing , Christian Brauner , Alexei Starovoitov , Alexey Budankov , Adrian Reber , Aleksa Sarai , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org, selinux@vger.kernel.org, kaleshsingh@google.com, calin@google.com, surenb@google.com, nnk@google.com, jeffv@google.com, kernel-team@android.com, Daniel Colascione Sender: selinux-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: selinux@vger.kernel.org From: Daniel Colascione This change adds a new function, anon_inode_getfd_secure, that creates anonymous-node file with individual non-S_PRIVATE inode to which security modules can apply policy. Existing callers continue using the original singleton-inode kind of anonymous-inode file. We can transition anonymous inode users to the new kind of anonymous inode in individual patches for the sake of bisection and review. The new function accepts an optional context_inode parameter that callers can use to provide additional contextual information to security modules for granting/denying permission to create an anon inode of the same type. For example, in case of userfaultfd, the created inode is a 'logical child' of the context_inode (userfaultfd inode of the parent process) in the sense that it provides the security context required during creation of the child process' userfaultfd inode. Signed-off-by: Daniel Colascione [Fix comment documenting return values of inode_init_security_anon()] [Add context_inode description in comments to anon_inode_getfd_secure()] [Remove definition of anon_inode_getfile_secure() as there are no callers] [Make _anon_inode_getfile() static] [Use correct error cast in _anon_inode_getfile()] [Fix error handling in _anon_inode_getfile()] Signed-off-by: Lokesh Gidra --- fs/anon_inodes.c | 147 +++++++++++++++++++++++++--------- include/linux/anon_inodes.h | 8 ++ include/linux/lsm_hook_defs.h | 2 + include/linux/lsm_hooks.h | 9 +++ include/linux/security.h | 10 +++ security/security.c | 8 ++ 6 files changed, 144 insertions(+), 40 deletions(-) diff --git a/fs/anon_inodes.c b/fs/anon_inodes.c index 89714308c25b..c3f16deda211 100644 --- a/fs/anon_inodes.c +++ b/fs/anon_inodes.c @@ -55,61 +55,79 @@ static struct file_system_type anon_inode_fs_type = { .kill_sb = kill_anon_super, }; -/** - * anon_inode_getfile - creates a new file instance by hooking it up to an - * anonymous inode, and a dentry that describe the "class" - * of the file - * - * @name: [in] name of the "class" of the new file - * @fops: [in] file operations for the new file - * @priv: [in] private data for the new file (will be file's private_data) - * @flags: [in] flags - * - * Creates a new file by hooking it on a single inode. This is useful for files - * that do not need to have a full-fledged inode in order to operate correctly. - * All the files created with anon_inode_getfile() will share a single inode, - * hence saving memory and avoiding code duplication for the file/inode/dentry - * setup. Returns the newly created file* or an error pointer. - */ -struct file *anon_inode_getfile(const char *name, - const struct file_operations *fops, - void *priv, int flags) +static struct inode *anon_inode_make_secure_inode( + const char *name, + const struct inode *context_inode) { - struct file *file; + struct inode *inode; + const struct qstr qname = QSTR_INIT(name, strlen(name)); + int error; + + inode = alloc_anon_inode(anon_inode_mnt->mnt_sb); + if (IS_ERR(inode)) + return inode; + inode->i_flags &= ~S_PRIVATE; + error = security_inode_init_security_anon(inode, &qname, context_inode); + if (error) { + iput(inode); + return ERR_PTR(error); + } + return inode; +} - if (IS_ERR(anon_inode_inode)) - return ERR_PTR(-ENODEV); +static struct file *_anon_inode_getfile(const char *name, + const struct file_operations *fops, + void *priv, int flags, + const struct inode *context_inode, + bool secure) +{ + struct inode *inode; + struct file *file; if (fops->owner && !try_module_get(fops->owner)) return ERR_PTR(-ENOENT); - /* - * We know the anon_inode inode count is always greater than zero, - * so ihold() is safe. - */ - ihold(anon_inode_inode); - file = alloc_file_pseudo(anon_inode_inode, anon_inode_mnt, name, + if (secure) { + inode = anon_inode_make_secure_inode(name, context_inode); + if (IS_ERR(inode)) { + file = ERR_CAST(inode); + goto err; + } + } else { + inode = anon_inode_inode; + if (IS_ERR(inode)) { + file = ERR_PTR(-ENODEV); + goto err; + } + /* + * We know the anon_inode inode count is always + * greater than zero, so ihold() is safe. + */ + ihold(inode); + } + + file = alloc_file_pseudo(inode, anon_inode_mnt, name, flags & (O_ACCMODE | O_NONBLOCK), fops); if (IS_ERR(file)) - goto err; + goto err_iput; - file->f_mapping = anon_inode_inode->i_mapping; + file->f_mapping = inode->i_mapping; file->private_data = priv; return file; +err_iput: + iput(inode); err: - iput(anon_inode_inode); module_put(fops->owner); return file; } -EXPORT_SYMBOL_GPL(anon_inode_getfile); /** - * anon_inode_getfd - creates a new file instance by hooking it up to an - * anonymous inode, and a dentry that describe the "class" - * of the file + * anon_inode_getfile - creates a new file instance by hooking it up to an + * anonymous inode, and a dentry that describe the "class" + * of the file * * @name: [in] name of the "class" of the new file * @fops: [in] file operations for the new file @@ -118,12 +136,23 @@ EXPORT_SYMBOL_GPL(anon_inode_getfile); * * Creates a new file by hooking it on a single inode. This is useful for files * that do not need to have a full-fledged inode in order to operate correctly. - * All the files created with anon_inode_getfd() will share a single inode, + * All the files created with anon_inode_getfile() will share a single inode, * hence saving memory and avoiding code duplication for the file/inode/dentry - * setup. Returns new descriptor or an error code. + * setup. Returns the newly created file* or an error pointer. */ -int anon_inode_getfd(const char *name, const struct file_operations *fops, - void *priv, int flags) +struct file *anon_inode_getfile(const char *name, + const struct file_operations *fops, + void *priv, int flags) +{ + return _anon_inode_getfile(name, fops, priv, flags, NULL, false); +} +EXPORT_SYMBOL_GPL(anon_inode_getfile); + +static int _anon_inode_getfd(const char *name, + const struct file_operations *fops, + void *priv, int flags, + const struct inode *context_inode, + bool secure) { int error, fd; struct file *file; @@ -133,7 +162,8 @@ int anon_inode_getfd(const char *name, const struct file_operations *fops, return error; fd = error; - file = anon_inode_getfile(name, fops, priv, flags); + file = _anon_inode_getfile(name, fops, priv, flags, context_inode, + secure); if (IS_ERR(file)) { error = PTR_ERR(file); goto err_put_unused_fd; @@ -146,8 +176,45 @@ int anon_inode_getfd(const char *name, const struct file_operations *fops, put_unused_fd(fd); return error; } + +/** + * anon_inode_getfd - creates a new file instance by hooking it up to + * an anonymous inode and a dentry that describe + * the "class" of the file + * + * @name: [in] name of the "class" of the new file + * @fops: [in] file operations for the new file + * @priv: [in] private data for the new file (will be file's private_data) + * @flags: [in] flags + * + * Creates a new file by hooking it on a single inode. This is + * useful for files that do not need to have a full-fledged inode in + * order to operate correctly. All the files created with + * anon_inode_getfd() will use the same singleton inode, reducing + * memory use and avoiding code duplication for the file/inode/dentry + * setup. Returns a newly created file descriptor or an error code. + */ +int anon_inode_getfd(const char *name, const struct file_operations *fops, + void *priv, int flags) +{ + return _anon_inode_getfd(name, fops, priv, flags, NULL, false); +} EXPORT_SYMBOL_GPL(anon_inode_getfd); +/** + * Like anon_inode_getfd(), but adds the @context_inode argument to + * allow security modules to control creation of the new file. Once the + * security module makes the decision, this inode is no longer needed + * and hence reference to it is not held. + */ +int anon_inode_getfd_secure(const char *name, const struct file_operations *fops, + void *priv, int flags, + const struct inode *context_inode) +{ + return _anon_inode_getfd(name, fops, priv, flags, context_inode, true); +} +EXPORT_SYMBOL_GPL(anon_inode_getfd_secure); + static int __init anon_inode_init(void) { anon_inode_mnt = kern_mount(&anon_inode_fs_type); diff --git a/include/linux/anon_inodes.h b/include/linux/anon_inodes.h index d0d7d96261ad..6ab840ee93bc 100644 --- a/include/linux/anon_inodes.h +++ b/include/linux/anon_inodes.h @@ -10,12 +10,20 @@ #define _LINUX_ANON_INODES_H struct file_operations; +struct inode; struct file *anon_inode_getfile(const char *name, const struct file_operations *fops, void *priv, int flags); + +int anon_inode_getfd_secure(const char *name, + const struct file_operations *fops, + void *priv, int flags, + const struct inode *context_inode); + int anon_inode_getfd(const char *name, const struct file_operations *fops, void *priv, int flags); + #endif /* _LINUX_ANON_INODES_H */ diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h index 2a8c74d99015..35ff75c43de4 100644 --- a/include/linux/lsm_hook_defs.h +++ b/include/linux/lsm_hook_defs.h @@ -113,6 +113,8 @@ LSM_HOOK(void, LSM_RET_VOID, inode_free_security, struct inode *inode) LSM_HOOK(int, 0, inode_init_security, struct inode *inode, struct inode *dir, const struct qstr *qstr, const char **name, void **value, size_t *len) +LSM_HOOK(int, 0, inode_init_security_anon, struct inode *inode, + const struct qstr *name, const struct inode *context_inode) LSM_HOOK(int, 0, inode_create, struct inode *dir, struct dentry *dentry, umode_t mode) LSM_HOOK(int, 0, inode_link, struct dentry *old_dentry, struct inode *dir, diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h index 9e2e3e63719d..586186f1184b 100644 --- a/include/linux/lsm_hooks.h +++ b/include/linux/lsm_hooks.h @@ -233,6 +233,15 @@ * Returns 0 if @name and @value have been successfully set, * -EOPNOTSUPP if no security attribute is needed, or * -ENOMEM on memory allocation failure. + * @inode_init_security_anon: + * Set up the incore security field for the new anonymous inode + * and return whether the inode creation is permitted by the security + * module or not. + * @inode contains the inode structure + * @name name of the anonymous inode class + * @context_inode optional related inode + * Returns 0 on success, -EACCESS if the security module denies the + * creation of this inode, or another -errno upon other errors. * @inode_create: * Check permission to create a regular file. * @dir contains inode structure of the parent of the new file. diff --git a/include/linux/security.h b/include/linux/security.h index 0a0a03b36a3b..7c6b3dcf4721 100644 --- a/include/linux/security.h +++ b/include/linux/security.h @@ -322,6 +322,9 @@ void security_inode_free(struct inode *inode); int security_inode_init_security(struct inode *inode, struct inode *dir, const struct qstr *qstr, initxattrs initxattrs, void *fs_data); +int security_inode_init_security_anon(struct inode *inode, + const struct qstr *name, + const struct inode *context_inode); int security_old_inode_init_security(struct inode *inode, struct inode *dir, const struct qstr *qstr, const char **name, void **value, size_t *len); @@ -732,6 +735,13 @@ static inline int security_inode_init_security(struct inode *inode, return 0; } +static inline int security_inode_init_security_anon(struct inode *inode, + const struct qstr *name, + const struct inode *context_inode) +{ + return 0; +} + static inline int security_old_inode_init_security(struct inode *inode, struct inode *dir, const struct qstr *qstr, diff --git a/security/security.c b/security/security.c index 70a7ad357bc6..2c4b121a01b9 100644 --- a/security/security.c +++ b/security/security.c @@ -1057,6 +1057,14 @@ int security_inode_init_security(struct inode *inode, struct inode *dir, } EXPORT_SYMBOL(security_inode_init_security); +int security_inode_init_security_anon(struct inode *inode, + const struct qstr *name, + const struct inode *context_inode) +{ + return call_int_hook(inode_init_security_anon, 0, inode, name, + context_inode); +} + int security_old_inode_init_security(struct inode *inode, struct inode *dir, const struct qstr *qstr, const char **name, void **value, size_t *len)