From patchwork Fri Jan 8 05:32:57 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Lokesh Gidra X-Patchwork-Id: 12005787 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-26.6 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT,USER_IN_DEF_DKIM_WL autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 03DDCC43332 for ; Fri, 8 Jan 2021 05:34:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DAB8F2343B for ; Fri, 8 Jan 2021 05:34:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728033AbhAHFeX (ORCPT ); Fri, 8 Jan 2021 00:34:23 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56610 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728025AbhAHFeW (ORCPT ); Fri, 8 Jan 2021 00:34:22 -0500 Received: from mail-pf1-x449.google.com (mail-pf1-x449.google.com [IPv6:2607:f8b0:4864:20::449]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A9D85C0612A0 for ; Thu, 7 Jan 2021 21:33:05 -0800 (PST) Received: by mail-pf1-x449.google.com with SMTP id y187so5876883pfc.7 for ; Thu, 07 Jan 2021 21:33:05 -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=98Z4ectXH1REB58k02Mn1amE7f3KfVW7xatcwz+e4fE=; b=Gr8ToxvYwY22MpaSPnvv+xNTlF/MwvGK1jay3/KQp6rUMoMTvKtxUxD+fc0e3NyuJ8 o+cKsoUpxojpTgUHAomzIjQbNqfHVgzRePkld2+cs3rxMTsLKygVVuDBTGTVTkv/7RUH A8cpF9U6c3PRllLLLAn3+rq892JeKIN7FGREU7e9y/RdFftBINpJBgXteA+zKow1enF5 LiYwKQ9Yqv9yh2E1d/xtg7uonuUqM6Ob/TcInfIIyoUzagaRIPp12hiiGc16g7fPqtGc /UI3GE1GT62eFxi/gDJtYKPs+7OXz85Vsmzqzg6OykKSj1TQbbo+WMZTNm0z45ZRAoIs T7Og== 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=98Z4ectXH1REB58k02Mn1amE7f3KfVW7xatcwz+e4fE=; b=aHEImFE1778ugqDsh5OF40Cso92EArEYaKZQYgZz30H5vkxIlciDUs7MQEpaETW2qW tj8NgJ1udO8874rPKuu5z/JAHYLj7tQoZ6E7JT8xRTFKddo16/8Tnjwh2CXocGKQSmD4 wLXHOJ6ulI0K6wh46GPsUBbqYLpRDV+eOrRKc0FDr/rJ+4vUFiKi0L3iM3s16JRGZdrv PUf7U+JePkLYv34sT2N97edGXEID9pz6JQJQ7Kctm65Uyxnlc9+mAGuneWgbBjI2gjiP RoxgV1GuzDtrxZj1ssFqPyHX9jH6TP//N0UIfp650t3M8TOIHbCQlbzIv9CCNcsr4eID +Plw== X-Gm-Message-State: AOAM532hVPrx791XNl2c3s+1AgId83964BaAmnYcR26KvFJBlUM8qG0q Q4H7vXes6agRBe6TguzYNiSDFgeMgWOw/cCxEw== X-Google-Smtp-Source: ABdhPJxfehStPEkJ3pUnpGoIAn6powT/fnb9r1MZcIuc+Bkv40QUK2XLdEFie9F8fMw6kxFJ4XcRsrnRfBWhIxZZAw== 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:a62:1a56:0:b029:19d:b6eb:291a with SMTP id a83-20020a621a560000b029019db6eb291amr2047387pfa.10.1610083985027; Thu, 07 Jan 2021 21:33:05 -0800 (PST) Date: Thu, 7 Jan 2021 21:32:57 -0800 In-Reply-To: <20210108053259.726613-1-lokeshgidra@google.com> Message-Id: <20210108053259.726613-3-lokeshgidra@google.com> Mime-Version: 1.0 References: <20210108053259.726613-1-lokeshgidra@google.com> X-Mailer: git-send-email 2.30.0.284.gd98b1dd5eaa7-goog Subject: [PATCH v14 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 , Randy Dunlap , "Joel Fernandes (Google)" , YueHaibing , Christian Brauner , Alexei Starovoitov , 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 Precedence: bulk List-ID: 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 [LG: Delete obsolete comments to alloc_anon_inode()] [LG: Add context_inode description in comments to anon_inode_getfd_secure()] [LG: Remove definition of anon_inode_getfile_secure() as there are no callers] [LG: Make __anon_inode_getfile() static] [LG: Use correct error cast in __anon_inode_getfile()] [LG: 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 d1c3bade9f30..e52818fb276a 100644 --- a/fs/libfs.c +++ b/fs/libfs.c @@ -1214,11 +1214,6 @@ 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 */