From patchwork Thu Mar 26 18:14:54 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Daniel Colascione X-Patchwork-Id: 11460775 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 9B01715AB for ; Thu, 26 Mar 2020 18:15:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7CE852073E for ; Thu, 26 Mar 2020 18:15:19 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="DIe/HSz3" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727939AbgCZSPS (ORCPT ); Thu, 26 Mar 2020 14:15:18 -0400 Received: from mail-vk1-f201.google.com ([209.85.221.201]:47735 "EHLO mail-vk1-f201.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727919AbgCZSPS (ORCPT ); Thu, 26 Mar 2020 14:15:18 -0400 Received: by mail-vk1-f201.google.com with SMTP id j140so2404180vke.14 for ; Thu, 26 Mar 2020 11:15:17 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=zFlM70MP3VetVuidGZ5oQERxbIVr8cobPoAE2yMCfNg=; b=DIe/HSz3irSSjaq32QsfyjZI/YZ3Y7vKLJPlkid+ENQBy0og6XLoK/vsn393qwwoTa QFd3ZB1IxgsRAm3ncm8AX3wTCR3ToobhMfvuvW0NwQezsbkcGhDoa6HoGpnGxb9kA4+T q9V45m609izFt/ZOBtAtAx/fcsEUEMCXq+NqRB4gy+4tfEZO+e03R9/7sAk7hH8qSYU6 QBsvcJH+C+HWowVgYv64k+YM1aZ3PD+ANsYurxvBnUS/cv+mesubXbYxu1FqlDMHllJn DQJthAmCQS+80bo/ZN7lAE2DRzq7gpXjB0BJaFB+me2ciOnEr8QlKDb69nWPXOheNANn eE5Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=zFlM70MP3VetVuidGZ5oQERxbIVr8cobPoAE2yMCfNg=; b=jM8aGkUgDGCHUEtg4PTjX9GUodxUJUmveiblhV8g9J56BksroJPzEwqGkrBasSkted FOvw6Cjgl56l7aT36UozN0wdFq5LlmJP3AtLRfjNroFBSrT23EvGzSqvboko4BuC6z8B poV9blecLfNadCawjeZDZF7aaBD18SUPnXl9qOl1NKMvyq8f/RQsaDZPSBy7Igx5AytG /FeSQZha2xRMVqe93k7160jselrEx7YYeLjpDovm39SN9Az/+ZDIJU5bnXabF1KQglrc xuPLGGSAwVSVNv9xTX/ZD585LPcDDp9EkQAJsrv3xdB/S1Qfc7KEy0ZqaS+v5Aecz/5v iqkg== X-Gm-Message-State: ANhLgQ1FHjfQzXi9P4BHBwbvFKVlT1IR6qgJOUucIpHfablzQSyQ0Lsq AW2XBsxjQfrbsfAO9WbZclPts0TWSCI= X-Google-Smtp-Source: ADFU+vtOQynXnyAgy9V5Y3E9NRdRmPltZtqWbmU5iARuCklYCp+PHmqraq7XO7in4i4C6bM9MYUrjhTH4s0= X-Received: by 2002:a67:f953:: with SMTP id u19mr8213724vsq.8.1585246516747; Thu, 26 Mar 2020 11:15:16 -0700 (PDT) Date: Thu, 26 Mar 2020 11:14:54 -0700 In-Reply-To: <20200326181456.132742-1-dancol@google.com> Message-Id: <20200326181456.132742-2-dancol@google.com> Mime-Version: 1.0 References: <20200214032635.75434-1-dancol@google.com> <20200326181456.132742-1-dancol@google.com> X-Mailer: git-send-email 2.25.1.696.g5e7596f4ac-goog Subject: [PATCH v3 1/3] Add a new LSM-supporting anonymous inode interface From: Daniel Colascione To: timmurray@google.com, selinux@vger.kernel.org, linux-security-module@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, viro@zeniv.linux.org.uk, paul@paul-moore.com, nnk@google.com, sds@tycho.nsa.gov, lokeshgidra@google.com, jmorris@namei.org Cc: Daniel Colascione Sender: selinux-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: selinux@vger.kernel.org This change adds two new functions, anon_inode_getfile_secure and anon_inode_getfd_secure, that create anonymous-node files with individual non-S_PRIVATE inodes 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 functions accept an optional context_inode parameter that callers can use to provide additional contextual information to security modules, e.g., indicating that one anonymous struct file is a logical child of another, allowing a security model to propagate security information from one to the other. Signed-off-by: Daniel Colascione --- fs/anon_inodes.c | 196 ++++++++++++++++++++++++++++-------- fs/userfaultfd.c | 4 +- include/linux/anon_inodes.h | 13 +++ include/linux/lsm_hooks.h | 9 ++ include/linux/security.h | 4 + security/security.c | 10 ++ 6 files changed, 191 insertions(+), 45 deletions(-) diff --git a/fs/anon_inodes.c b/fs/anon_inodes.c index 89714308c25b..114a04fc1db4 100644 --- a/fs/anon_inodes.c +++ b/fs/anon_inodes.c @@ -55,75 +55,135 @@ 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, + const struct file_operations *fops) +{ + 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 ERR_PTR(PTR_ERR(inode)); + inode->i_flags &= ~S_PRIVATE; + error = security_inode_init_security_anon( + inode, &qname, fops, context_inode); + if (error) { + iput(inode); + return ERR_PTR(error); + } + return inode; +} + +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 (IS_ERR(anon_inode_inode)) - return ERR_PTR(-ENODEV); + if (secure) { + inode = anon_inode_make_secure_inode( + name, context_inode, fops); + if (IS_ERR(inode)) + return ERR_PTR(PTR_ERR(inode)); + } else { + inode = anon_inode_inode; + if (IS_ERR(inode)) + return ERR_PTR(-ENODEV); + /* + * We know the anon_inode inode count is always + * greater than zero, so ihold() is safe. + */ + ihold(inode); + } - if (fops->owner && !try_module_get(fops->owner)) - return ERR_PTR(-ENOENT); + if (fops->owner && !try_module_get(fops->owner)) { + file = ERR_PTR(-ENOENT); + goto err; + } - /* - * 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, + file = alloc_file_pseudo(inode, anon_inode_mnt, name, flags & (O_ACCMODE | O_NONBLOCK), fops); if (IS_ERR(file)) goto err; - file->f_mapping = anon_inode_inode->i_mapping; + file->f_mapping = inode->i_mapping; file->private_data = priv; return file; err: - iput(anon_inode_inode); + iput(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_secure - creates a new file instance by hooking + * it up to a new anonymous inode and a + * dentry that describe the "class" of the + * file. Make it possible to use security + * modules to control access to the + * new 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 + * @flags: [in] flags for the file + * @anon_inode_flags: [in] flags for anon_inode* + * + * Creates a new file by hooking it on an unspecified 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_secure() will have distinct inodes, avoiding + * code duplication for the file/inode/dentry setup. Returns the + * newly created file* or an error pointer. + */ +struct file *anon_inode_getfile_secure(const char *name, + const struct file_operations *fops, + void *priv, int flags, + const struct inode *context_inode) +{ + return _anon_inode_getfile( + name, fops, priv, flags, context_inode, true); +} +EXPORT_SYMBOL_GPL(anon_inode_getfile_secure); + +/** + * 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 for the file * - * Creates a new file by hooking it on a single inode. This is useful for files + * Creates a new file by hooking it on an unspecified 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 +193,8 @@ 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; @@ -146,6 +207,57 @@ int anon_inode_getfd(const char *name, const struct file_operations *fops, put_unused_fd(fd); return error; } + +/** + * anon_inode_getfd_secure - creates a new file instance by hooking it + * up to a new anonymous inode and a dentry + * that describe the "class" of the file. + * Make it possible to use security modules + * to control access to the new 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 an unspecified 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_secure() will have distinct inodes, avoiding + * code duplication for the file/inode/dentry setup. Returns a newly + * created file descriptor or an error code. + */ +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); + +/** + * 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 an unspecified 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 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); static int __init anon_inode_init(void) diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c index 37df7c9eedb1..07b0f6e03849 100644 --- a/fs/userfaultfd.c +++ b/fs/userfaultfd.c @@ -1014,8 +1014,6 @@ static __poll_t userfaultfd_poll(struct file *file, poll_table *wait) } } -static const struct file_operations userfaultfd_fops; - static int resolve_userfault_fork(struct userfaultfd_ctx *ctx, struct userfaultfd_ctx *new, struct uffd_msg *msg) @@ -1920,7 +1918,7 @@ static void userfaultfd_show_fdinfo(struct seq_file *m, struct file *f) } #endif -static const struct file_operations userfaultfd_fops = { +const struct file_operations userfaultfd_fops = { #ifdef CONFIG_PROC_FS .show_fdinfo = userfaultfd_show_fdinfo, #endif diff --git a/include/linux/anon_inodes.h b/include/linux/anon_inodes.h index d0d7d96261ad..67bd85d92dca 100644 --- a/include/linux/anon_inodes.h +++ b/include/linux/anon_inodes.h @@ -10,12 +10,25 @@ #define _LINUX_ANON_INODES_H struct file_operations; +struct inode; + +struct file *anon_inode_getfile_secure(const char *name, + const struct file_operations *fops, + void *priv, int flags, + const struct inode *context_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_hooks.h b/include/linux/lsm_hooks.h index 20d8cf194fb7..de5d37e388df 100644 --- a/include/linux/lsm_hooks.h +++ b/include/linux/lsm_hooks.h @@ -215,6 +215,10 @@ * 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 a secure anonymous inode. + * Returns 0 on success. Returns -EPERM if the security module denies + * the creation of this inode. * @inode_create: * Check permission to create a regular file. * @dir contains inode structure of the parent of the new file. @@ -1552,6 +1556,10 @@ union security_list_options { const struct qstr *qstr, const char **name, void **value, size_t *len); + int (*inode_init_security_anon)(struct inode *inode, + const struct qstr *name, + const struct file_operations *fops, + const struct inode *context_inode); int (*inode_create)(struct inode *dir, struct dentry *dentry, umode_t mode); int (*inode_link)(struct dentry *old_dentry, struct inode *dir, @@ -1884,6 +1892,7 @@ struct security_hook_heads { struct hlist_head inode_alloc_security; struct hlist_head inode_free_security; struct hlist_head inode_init_security; + struct hlist_head inode_init_security_anon; struct hlist_head inode_create; struct hlist_head inode_link; struct hlist_head inode_unlink; diff --git a/include/linux/security.h b/include/linux/security.h index 64b19f050343..8ea76af0be7a 100644 --- a/include/linux/security.h +++ b/include/linux/security.h @@ -320,6 +320,10 @@ 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 file_operations *fops, + 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); diff --git a/security/security.c b/security/security.c index 565bc9b67276..d06f3969c030 100644 --- a/security/security.c +++ b/security/security.c @@ -1033,6 +1033,16 @@ 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 file_operations *fops, + const struct inode *context_inode) +{ + return call_int_hook(inode_init_security_anon, 0, inode, name, + fops, 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)