From patchwork Thu Nov 12 01:53:56 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Lokesh Gidra X-Patchwork-Id: 11898989 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 E43DB15E6 for ; Thu, 12 Nov 2020 05:38:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B9F8321534 for ; Thu, 12 Nov 2020 05:38:22 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="SQyRpCsk" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729475AbgKLFiU (ORCPT ); Thu, 12 Nov 2020 00:38:20 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55482 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728152AbgKLByJ (ORCPT ); Wed, 11 Nov 2020 20:54:09 -0500 Received: from mail-yb1-xb4a.google.com (mail-yb1-xb4a.google.com [IPv6:2607:f8b0:4864:20::b4a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 49395C061A53 for ; Wed, 11 Nov 2020 17:54:09 -0800 (PST) Received: by mail-yb1-xb4a.google.com with SMTP id a126so4265256ybb.11 for ; Wed, 11 Nov 2020 17:54:09 -0800 (PST) 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=c9Og5DC1k1cUQRw8CGbu3hvhZccACMgaVukw9TXsnBk=; b=SQyRpCskDDQyjOj6Y7KQvyf3aH7p5CeESVkOzrwBVOw1wcZF5i6plpZZMnli4dRCk7 KoIwO3P2UyZnp6UypXtHWy5M2Dap/44fsRQwyPpwXGdkVenFWanSIFIsv8SGfQcvEbdD o3eZGOw8xs9KPTNqy27mnkEv64rarQjcTaWJnxSDIWKqLGZwr5qem3oI89F0v3cxeyAU j/PhrDuI/dRIqJ5zGSIoLc1kEtTjSQdSW91Q0HjlOPZvrgj3pxvwZiNTwhAZwfq7bafH 2sxTzHwcbexnyW7lTYQKJQZnTscocjiFdeH1tr0iAXvu/jrYNsRGNcaV10CkQ6IUrf/I 8iBA== 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=c9Og5DC1k1cUQRw8CGbu3hvhZccACMgaVukw9TXsnBk=; b=qLYadVjj8jUIj9/i5UXT1ra4uh/g8bclrIHr8Y2ZzpPaUQGTste0GAotybqYxnfEz/ JzZYR3BZMPKVp254Jn/efCraw4pYzcCjMN3xYgD6OAVMf1Sznk27x3+0ydXD0pISHErG +jMMhl7TuCh3ENsk0gScTlZrPsnhcmAMOsuUDgBzLiAeVAJu+QOwvl5jq2bU0PaCFTdn jmjHK9Yn+RXtkV/q6UjTheU48YcJRK8RXMj0M6wqP/ttYtJUE9eZWByGWY5Qx6sTVXrZ 7YfLTKd856rpGQlZ6Ot6E3RWeCQ8o7DKMEuY1hzTKpwnbPkGFN4rRTkcXeBkuJetQy14 Zzlw== X-Gm-Message-State: AOAM533sLMpau8uOtQLQRf0/3PeuTfzklq24eMDyy7ptJDuGnLxrA4fe /gN9AiMs8WHWqRmZirki0P3ThuF1ayzUT3ZEag== X-Google-Smtp-Source: ABdhPJwbEExJZLbWaATpLGAop1r2dI05u8VEsbPmkQZCo1UtYBTDWpESrtyVB/fsRM0ZspxgBdPVqcsf9LpufrRfvw== Sender: "lokeshgidra via sendgmr" X-Received: from lg.mtv.corp.google.com ([2620:15c:211:202:f693:9fff:fef4:29dd]) (user=lokeshgidra job=sendgmr) by 2002:a25:5702:: with SMTP id l2mr38652087ybb.184.1605146048341; Wed, 11 Nov 2020 17:54:08 -0800 (PST) Date: Wed, 11 Nov 2020 17:53:56 -0800 In-Reply-To: <20201112015359.1103333-1-lokeshgidra@google.com> Message-Id: <20201112015359.1103333-2-lokeshgidra@google.com> Mime-Version: 1.0 References: <20201112015359.1103333-1-lokeshgidra@google.com> X-Mailer: git-send-email 2.29.2.299.gdc1121823c-goog Subject: [PATCH v13 1/4] security: add inode_init_security_anon() LSM hook From: Lokesh Gidra To: Andrea Arcangeli , Alexander Viro , James Morris , Stephen Smalley , Casey Schaufler , Eric Biggers , Paul Moore Cc: "Serge E. Hallyn" , Eric Paris , Lokesh Gidra , Daniel Colascione , Kees Cook , "Eric W. Biederman" , KP Singh , David Howells , 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, jeffv@google.com, kernel-team@android.com, linux-mm@kvack.org, Andrew Morton , hch@infradead.org, Eric Biggers Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org This change adds a new LSM hook, inode_init_security_anon(), that will be used while creating secure anonymous inodes. The hook allows/denies its creation and assigns a security context to the inode. The new hook 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. This context_inode's security_context can also be used to initialize the newly created anon-inode's security_context. Signed-off-by: Lokesh Gidra Reviewed-by: Eric Biggers --- include/linux/lsm_hook_defs.h | 2 ++ include/linux/lsm_hooks.h | 9 +++++++++ include/linux/security.h | 10 ++++++++++ security/security.c | 8 ++++++++ 4 files changed, 29 insertions(+) diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h index 32a940117e7a..435a2e22ff95 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 c503f7ab8afb..3af055b7ee1f 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, -EACCES 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 bc2725491560..7494a93b9ed9 100644 --- a/include/linux/security.h +++ b/include/linux/security.h @@ -323,6 +323,9 @@ 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); @@ -737,6 +740,13 @@ 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 a28045dc9e7f..8989ba6af4f6 100644 --- a/security/security.c +++ b/security/security.c @@ -1058,6 +1058,14 @@ 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) From patchwork Thu Nov 12 01:53:57 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Lokesh Gidra X-Patchwork-Id: 11899035 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 CDA49139F for ; Thu, 12 Nov 2020 05:40:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9971C208FE for ; Thu, 12 Nov 2020 05:40:47 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="pdFjGdzJ" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729479AbgKLFiV (ORCPT ); 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Wed, 11 Nov 2020 17:54:11 -0800 (PST) Date: Wed, 11 Nov 2020 17:53:57 -0800 In-Reply-To: <20201112015359.1103333-1-lokeshgidra@google.com> Message-Id: <20201112015359.1103333-3-lokeshgidra@google.com> Mime-Version: 1.0 References: <20201112015359.1103333-1-lokeshgidra@google.com> X-Mailer: git-send-email 2.29.2.299.gdc1121823c-goog Subject: [PATCH v13 2/4] fs: add LSM-supporting anon-inode interface From: Lokesh Gidra To: Andrea Arcangeli , Alexander Viro , James Morris , Stephen Smalley , Casey Schaufler , Eric Biggers , Paul Moore Cc: "Serge E. Hallyn" , Eric Paris , Lokesh Gidra , Daniel Colascione , Kees Cook , "Eric W. Biederman" , KP Singh , David Howells , 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, jeffv@google.com, kernel-team@android.com, linux-mm@kvack.org, Andrew Morton , hch@infradead.org, Daniel Colascione , Eric Biggers Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@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 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 [Delete obsolete comments to alloc_anon_inode()] [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 Reviewed-by: Eric Biggers --- fs/anon_inodes.c | 150 ++++++++++++++++++++++++++---------- fs/libfs.c | 5 -- include/linux/anon_inodes.h | 5 ++ 3 files changed, 115 insertions(+), 45 deletions(-) diff --git a/fs/anon_inodes.c b/fs/anon_inodes.c index 89714308c25b..023337d65a03 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 +176,48 @@ 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 creates a new !S_PRIVATE anon inode rather than + * reuse the singleton anon inode, and calls the inode_init_security_anon() LSM + * hook. This allows the inode to have its own security context and for a LSM + * to reject creation of the inode. An optional @context_inode argument is + * also added to provide the logical relationship with the new inode. The LSM + * may use @context_inode in inode_init_security_anon(), but a 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/fs/libfs.c b/fs/libfs.c index fc34361c1489..51c19c72e563 100644 --- a/fs/libfs.c +++ b/fs/libfs.c @@ -1212,11 +1212,6 @@ static int anon_set_page_dirty(struct page *page) return 0; }; -/* - * A single inode exists for all anon_inode files. Contrary to pipes, - * anon_inode inodes have no associated per-instance data, so we need - * only allocate one of them. - */ struct inode *alloc_anon_inode(struct super_block *s) { static const struct address_space_operations anon_aops = { diff --git a/include/linux/anon_inodes.h b/include/linux/anon_inodes.h index d0d7d96261ad..71881a2b6f78 100644 --- a/include/linux/anon_inodes.h +++ b/include/linux/anon_inodes.h @@ -10,12 +10,17 @@ #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(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); #endif /* _LINUX_ANON_INODES_H */ From patchwork Thu Nov 12 01:53:58 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Lokesh Gidra X-Patchwork-Id: 11898991 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 55EEE15E6 for ; Thu, 12 Nov 2020 05:38:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2B5EF21534 for ; Thu, 12 Nov 2020 05:38:29 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="Mz0/RepG" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727933AbgKLFiX (ORCPT ); Thu, 12 Nov 2020 00:38:23 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55218 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730011AbgKLByg (ORCPT ); Wed, 11 Nov 2020 20:54:36 -0500 Received: from mail-yb1-xb49.google.com (mail-yb1-xb49.google.com [IPv6:2607:f8b0:4864:20::b49]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 50748C040208 for ; Wed, 11 Nov 2020 17:54:15 -0800 (PST) Received: by mail-yb1-xb49.google.com with SMTP id v13so9057ybe.18 for ; Wed, 11 Nov 2020 17:54:15 -0800 (PST) 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=EKdfgxKmgqyWOrEoFelO0xo4xUprR4kVgmmY5QtMneA=; b=Mz0/RepGCaX9VPHW6LKYUdkGuWwDxdRh602UW+erQ9khnSph5lnBFq+8u9tT4GDxaS ckxAoj4jIZb/X+96/D7EN4p3mRLqrhrRnE3AxR4nd3qOi6FK1e/Z6XUKmdBv0V52oHoi fnRSEC7tE+8O3CSNKd8dbNMYYBVswtN2GpJKmuRoeXfgAY2LAq6yldLOmIxmMhutphYm j4fhBnd140Pi1Ckyo33E5c9jKyWfJ37HDd6ORnuKewANEJvZfovjkYwOABiS+IlQOpEn QIjD4OMXTdg/iDGYGT+UyppMyuf4rtDyeeBOjhzp9egpqH7d6TWO6igQsuhW95l5hcfa uSuw== 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=EKdfgxKmgqyWOrEoFelO0xo4xUprR4kVgmmY5QtMneA=; b=IbxP6lR52gzlogGfMcwNadTZj8sSknXiz510kUPP2koGTzMmrG+k702+GwMV4tXx9n aOptnvdIGn2tEHmfxLC2A6ZWhyxbD8OvLHQybyGqCIHjW62d4sR0jpJbu4qud/v+SQo2 qX6Rxi12h2Qlz9/am5TFT4rCqRwT5CS9/EGO4Pidg7TBoiVXdphi0b2LuBut3grxyLk9 TK/x+HceHgV/KV6hAAX8OZ4WHo7jyDlQ7vptSvxiMc4Rvr1zEMUyUnahv3DP56ABTfmv 7bCI3ZrhkR+s9wpga6ETt7hMpC4GKfKUZPqeuFZx5LG+gr4KPjnCRxQ2SiYdXtqwcOq1 PcTQ== X-Gm-Message-State: AOAM533n2h2b2XLL2+/WyGYl/AE8yFKIq0Urv73dPDj5HKqMaGZTPvXy xi1jIuqU4uArDGH58n8A6BLbHpIWZp9rc38mww== X-Google-Smtp-Source: ABdhPJzFSv/Xdn7GGdy2MUG7BhSbdefjZ9hVJ+MOvRURjTp6rSFxYr2XLTCAi7JOZcqE2J6h4zH58KP3k6BneY9sdA== Sender: "lokeshgidra via sendgmr" X-Received: from lg.mtv.corp.google.com ([2620:15c:211:202:f693:9fff:fef4:29dd]) (user=lokeshgidra job=sendgmr) by 2002:a25:bc42:: with SMTP id d2mr6737406ybk.461.1605146054397; Wed, 11 Nov 2020 17:54:14 -0800 (PST) Date: Wed, 11 Nov 2020 17:53:58 -0800 In-Reply-To: <20201112015359.1103333-1-lokeshgidra@google.com> Message-Id: <20201112015359.1103333-4-lokeshgidra@google.com> Mime-Version: 1.0 References: <20201112015359.1103333-1-lokeshgidra@google.com> X-Mailer: git-send-email 2.29.2.299.gdc1121823c-goog Subject: [PATCH v13 3/4] selinux: teach SELinux about anonymous inodes From: Lokesh Gidra To: Andrea Arcangeli , Alexander Viro , James Morris , Stephen Smalley , Casey Schaufler , Eric Biggers , Paul Moore Cc: "Serge E. Hallyn" , Eric Paris , Lokesh Gidra , Daniel Colascione , Kees Cook , "Eric W. Biederman" , KP Singh , David Howells , 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, jeffv@google.com, kernel-team@android.com, linux-mm@kvack.org, Andrew Morton , hch@infradead.org, Daniel Colascione Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org From: Daniel Colascione This change uses the anon_inodes and LSM infrastructure introduced in the previous patches to give SELinux the ability to control anonymous-inode files that are created using the new anon_inode_getfd_secure() function. A SELinux policy author detects and controls these anonymous inodes by adding a name-based type_transition rule that assigns a new security type to anonymous-inode files created in some domain. The name used for the name-based transition is the name associated with the anonymous inode for file listings --- e.g., "[userfaultfd]" or "[perf_event]". Example: type uffd_t; type_transition sysadm_t sysadm_t : anon_inode uffd_t "[userfaultfd]"; allow sysadm_t uffd_t:anon_inode { create }; (The next patch in this series is necessary for making userfaultfd support this new interface. The example above is just for exposition.) Signed-off-by: Daniel Colascione Signed-off-by: Lokesh Gidra --- security/selinux/hooks.c | 56 +++++++++++++++++++++++++++++ security/selinux/include/classmap.h | 2 ++ 2 files changed, 58 insertions(+) diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c index 6b1826fc3658..d092aa512868 100644 --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -2927,6 +2927,61 @@ static int selinux_inode_init_security(struct inode *inode, struct inode *dir, return 0; } +static int selinux_inode_init_security_anon(struct inode *inode, + const struct qstr *name, + const struct inode *context_inode) +{ + const struct task_security_struct *tsec = selinux_cred(current_cred()); + struct common_audit_data ad; + struct inode_security_struct *isec; + int rc; + + if (unlikely(!selinux_initialized(&selinux_state))) + return 0; + + isec = selinux_inode(inode); + + /* + * We only get here once per ephemeral inode. The inode has + * been initialized via inode_alloc_security but is otherwise + * untouched. + */ + + if (context_inode) { + struct inode_security_struct *context_isec = + selinux_inode(context_inode); + if (context_isec->initialized != LABEL_INITIALIZED) + return -EACCES; + + isec->sclass = context_isec->sclass; + isec->sid = context_isec->sid; + } else { + isec->sclass = SECCLASS_ANON_INODE; + rc = security_transition_sid( + &selinux_state, tsec->sid, tsec->sid, + isec->sclass, name, &isec->sid); + if (rc) + return rc; + } + + isec->initialized = LABEL_INITIALIZED; + + /* + * Now that we've initialized security, check whether we're + * allowed to actually create this type of anonymous inode. + */ + + ad.type = LSM_AUDIT_DATA_INODE; + ad.u.inode = inode; + + return avc_has_perm(&selinux_state, + tsec->sid, + isec->sid, + isec->sclass, + ANON_INODE__CREATE, + &ad); +} + static int selinux_inode_create(struct inode *dir, struct dentry *dentry, umode_t mode) { return may_create(dir, dentry, SECCLASS_FILE); @@ -6992,6 +7047,7 @@ static struct security_hook_list selinux_hooks[] __lsm_ro_after_init = { LSM_HOOK_INIT(inode_free_security, selinux_inode_free_security), LSM_HOOK_INIT(inode_init_security, selinux_inode_init_security), + LSM_HOOK_INIT(inode_init_security_anon, selinux_inode_init_security_anon), LSM_HOOK_INIT(inode_create, selinux_inode_create), LSM_HOOK_INIT(inode_link, selinux_inode_link), LSM_HOOK_INIT(inode_unlink, selinux_inode_unlink), diff --git a/security/selinux/include/classmap.h b/security/selinux/include/classmap.h index 40cebde62856..ba2e01a6955c 100644 --- a/security/selinux/include/classmap.h +++ b/security/selinux/include/classmap.h @@ -249,6 +249,8 @@ struct security_class_mapping secclass_map[] = { {"open", "cpu", "kernel", "tracepoint", "read", "write"} }, { "lockdown", { "integrity", "confidentiality", NULL } }, + { "anon_inode", + { COMMON_FILE_PERMS, NULL } }, { NULL } }; From patchwork Thu Nov 12 01:53:59 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Lokesh Gidra X-Patchwork-Id: 11898993 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 B349E1391 for ; Thu, 12 Nov 2020 05:38:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 89216208FE for ; Thu, 12 Nov 2020 05:38:30 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="KHw/IjNn" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728464AbgKLFi2 (ORCPT ); Thu, 12 Nov 2020 00:38:28 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55408 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728270AbgKLBzp (ORCPT ); Wed, 11 Nov 2020 20:55:45 -0500 Received: from mail-yb1-xb4a.google.com (mail-yb1-xb4a.google.com [IPv6:2607:f8b0:4864:20::b4a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 24C4FC0401C3 for ; Wed, 11 Nov 2020 17:54:18 -0800 (PST) Received: by mail-yb1-xb4a.google.com with SMTP id g129so4253734ybf.20 for ; Wed, 11 Nov 2020 17:54:18 -0800 (PST) DKIM-Signature: v=1; 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Wed, 11 Nov 2020 17:54:17 -0800 (PST) Date: Wed, 11 Nov 2020 17:53:59 -0800 In-Reply-To: <20201112015359.1103333-1-lokeshgidra@google.com> Message-Id: <20201112015359.1103333-5-lokeshgidra@google.com> Mime-Version: 1.0 References: <20201112015359.1103333-1-lokeshgidra@google.com> X-Mailer: git-send-email 2.29.2.299.gdc1121823c-goog Subject: [PATCH v13 4/4] userfaultfd: use secure anon inodes for userfaultfd From: Lokesh Gidra To: Andrea Arcangeli , Alexander Viro , James Morris , Stephen Smalley , Casey Schaufler , Eric Biggers , Paul Moore Cc: "Serge E. Hallyn" , Eric Paris , Lokesh Gidra , Daniel Colascione , Kees Cook , "Eric W. Biederman" , KP Singh , David Howells , 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, jeffv@google.com, kernel-team@android.com, linux-mm@kvack.org, Andrew Morton , hch@infradead.org, Daniel Colascione , Eric Biggers Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org From: Daniel Colascione This change gives userfaultfd file descriptors a real security context, allowing policy to act on them. Signed-off-by: Daniel Colascione [Remove owner inode from userfaultfd_ctx] [Use anon_inode_getfd_secure() instead of anon_inode_getfile_secure() in userfaultfd syscall] [Use inode of file in userfaultfd_read() in resolve_userfault_fork()] Signed-off-by: Lokesh Gidra Reviewed-by: Eric Biggers --- fs/userfaultfd.c | 19 ++++++++++--------- 1 file changed, 10 insertions(+), 9 deletions(-) diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c index 000b457ad087..dd78daf06de6 100644 --- a/fs/userfaultfd.c +++ b/fs/userfaultfd.c @@ -972,14 +972,14 @@ 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, +static int resolve_userfault_fork(struct userfaultfd_ctx *new, + struct inode *inode, struct uffd_msg *msg) { int fd; - fd = anon_inode_getfd("[userfaultfd]", &userfaultfd_fops, new, - O_RDWR | (new->flags & UFFD_SHARED_FCNTL_FLAGS)); + fd = anon_inode_getfd_secure("[userfaultfd]", &userfaultfd_fops, new, + O_RDWR | (new->flags & UFFD_SHARED_FCNTL_FLAGS), inode); if (fd < 0) return fd; @@ -989,7 +989,7 @@ static int resolve_userfault_fork(struct userfaultfd_ctx *ctx, } static ssize_t userfaultfd_ctx_read(struct userfaultfd_ctx *ctx, int no_wait, - struct uffd_msg *msg) + struct uffd_msg *msg, struct inode *inode) { ssize_t ret; DECLARE_WAITQUEUE(wait, current); @@ -1100,7 +1100,7 @@ static ssize_t userfaultfd_ctx_read(struct userfaultfd_ctx *ctx, int no_wait, spin_unlock_irq(&ctx->fd_wqh.lock); if (!ret && msg->event == UFFD_EVENT_FORK) { - ret = resolve_userfault_fork(ctx, fork_nctx, msg); + ret = resolve_userfault_fork(fork_nctx, inode, msg); spin_lock_irq(&ctx->event_wqh.lock); if (!list_empty(&fork_event)) { /* @@ -1160,6 +1160,7 @@ static ssize_t userfaultfd_read(struct file *file, char __user *buf, ssize_t _ret, ret = 0; struct uffd_msg msg; int no_wait = file->f_flags & O_NONBLOCK; + struct inode *inode = file_inode(file); if (ctx->state == UFFD_STATE_WAIT_API) return -EINVAL; @@ -1167,7 +1168,7 @@ static ssize_t userfaultfd_read(struct file *file, char __user *buf, for (;;) { if (count < sizeof(msg)) return ret ? ret : -EINVAL; - _ret = userfaultfd_ctx_read(ctx, no_wait, &msg); + _ret = userfaultfd_ctx_read(ctx, no_wait, &msg, inode); if (_ret < 0) return ret ? ret : _ret; if (copy_to_user((__u64 __user *) buf, &msg, sizeof(msg))) @@ -1985,8 +1986,8 @@ SYSCALL_DEFINE1(userfaultfd, int, flags) /* prevent the mm struct to be freed */ mmgrab(ctx->mm); - fd = anon_inode_getfd("[userfaultfd]", &userfaultfd_fops, ctx, - O_RDWR | (flags & UFFD_SHARED_FCNTL_FLAGS)); + fd = anon_inode_getfd_secure("[userfaultfd]", &userfaultfd_fops, ctx, + O_RDWR | (flags & UFFD_SHARED_FCNTL_FLAGS), NULL); if (fd < 0) { mmdrop(ctx->mm); kmem_cache_free(userfaultfd_ctx_cachep, ctx);