From patchwork Sun Oct 11 08:29:34 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Lokesh Gidra X-Patchwork-Id: 11830711 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 9EFE3697 for ; Sun, 11 Oct 2020 08:30:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8329220776 for ; Sun, 11 Oct 2020 08:30:02 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="HliAs1+f" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729273AbgJKI3t (ORCPT ); Sun, 11 Oct 2020 04:29:49 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44808 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729233AbgJKI3p (ORCPT ); Sun, 11 Oct 2020 04:29:45 -0400 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 5ED87C0613D0 for ; Sun, 11 Oct 2020 01:29:43 -0700 (PDT) Received: by mail-yb1-xb49.google.com with SMTP id m62so10424624ybb.6 for ; Sun, 11 Oct 2020 01:29:43 -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=3XBsUbGDo1OR/q9g0ZauJ6lbqskxCel9Wx4PuO8x8CQ=; b=HliAs1+fMB4DTlcdtD45ZSY0OwIXP/oFjh0uwWLIen+LshhoP7zBQihZRXv2eCYipe MGGfL9KR+xjFyHIEGETwzLYyqZuVtDaB+uNrNtd7WnlmGL5idWaWP4Qq+suP54a5ZHZq Pm3E5NC9gzAx/bCLnZ9KT1zWrethGkLOAMglgc0PTgBBcj0vR/Xat/HWqs0GT5Ob/HSl pZpDE8tTZAjmSkHZx+jLolnwPi4nWMOtv0qWvjY6xbIvP7TGu2/Gu5TUGU7/qTWxLHAD ksg9CXbzuab2LzO064Rj+SsT5+KGiwnE7fWemnUBWktF9hOsvuFnAAuJ3/aNUJjaNI9B VyJQ== 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=3XBsUbGDo1OR/q9g0ZauJ6lbqskxCel9Wx4PuO8x8CQ=; b=myZAnSqo0kimNiYXGgvdMbhMK9KTBXxcA4i/CbL9ZorJ9Do0H6LdmbRUmGCH2Rp0Et 6d4wqejOibPaWTd+qc9wHlidrSi80uxzvmYb+u8UPw8H/NzjKKa6ezZsf+qwYGyKmEiD DWocmXl1p1Nf/8rTmGcHVtP+2Fq9dxQPD2sReNgfmQ+ndf2pbORmyXV+eC7XHonm7NwB UsY0HTy1aqpt++rLXbEqt4yETJ76bqYzG1KfJCynJtLO7jeL2WvWB/GFre3EhhFYF9i/ 2lsJIk1Io5BYMKM4Wq0KDTOAZas8RvxBzSnwkkJGH9apYnUuL/dhhijlBOPgE1ZK71tw OTyQ== X-Gm-Message-State: AOAM531QRWm91pi7KwaGakIp8TvHxovgMDqgg/n/qaScsgXPqTrTnLPz YpD/Sfidr/kYR7m6E2AqEo33fzDcK+SFPCsYWA== X-Google-Smtp-Source: ABdhPJzd55GvvouyGwIwqmwUVdeD8X7YAZWtMuewUKtvXWi8GhPYa5auMeVAezgkZ2/93TyW1bHHnJL/zCPUAVHUmQ== 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:a25:854d:: with SMTP id f13mr25590940ybn.210.1602404982474; Sun, 11 Oct 2020 01:29:42 -0700 (PDT) Date: Sun, 11 Oct 2020 01:29:34 -0700 In-Reply-To: <20201011082936.4131726-1-lokeshgidra@google.com> Message-Id: <20201011082936.4131726-2-lokeshgidra@google.com> Mime-Version: 1.0 References: <20201011082936.4131726-1-lokeshgidra@google.com> X-Mailer: git-send-email 2.28.0.1011.ga647a8990f-goog Subject: [PATCH v10 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 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 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 | 148 +++++++++++++++++++++++++--------- 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, 145 insertions(+), 40 deletions(-) diff --git a/fs/anon_inodes.c b/fs/anon_inodes.c index 89714308c25b..a3fe08fcaa52 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 +176,46 @@ 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() creates a new file, but by hooking it to a new anon + * inode, rather than to the same singleton inode. Also adds the @context_inode + * argument to allow security modules to control creation of the new file. Once + * the security module makes the decision, the context_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) From patchwork Sun Oct 11 08:29:35 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Lokesh Gidra X-Patchwork-Id: 11830713 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 D342E1744 for ; Sun, 11 Oct 2020 08:30:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AC01320776 for ; Sun, 11 Oct 2020 08:30:02 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="i2nS5xZN" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729288AbgJKI3w (ORCPT ); Sun, 11 Oct 2020 04:29:52 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44820 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729264AbgJKI3r (ORCPT ); Sun, 11 Oct 2020 04:29:47 -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 395EEC0613D2 for ; Sun, 11 Oct 2020 01:29:46 -0700 (PDT) Received: by mail-qk1-x74a.google.com with SMTP id y8so1748867qki.12 for ; Sun, 11 Oct 2020 01:29:46 -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=DS8C9e64g1Tr1aD0/k+FxGXbkI0cBOsw5SM2h09qao8=; b=i2nS5xZN3nfP8mH5SMaFmKcZCLgNl6jV+ckgmOf/deX6W0Kz6oMqcAxTPqavTJEEI9 RfzCeiIdGXN5cW+Fa/g/uFhHb1LEiDDDvs0rnzKWJJTjfM+3yJQjtX2WRhABwBs/jSS8 gWUxuaeadJPIqV/QHGrNmqPFGqQMdWgidPtW/9s3rqjAx4R86Wv67I8GmbUN/RsoBIk0 0mb4AlqbThZzEot/APR+ZNF7IgaEO/KBN2MNGsSv5F+soTQkJwIFl2RotUHwAcSi/vSP iC4Jw4c5FsCqiqfW0sWaDT5POrJW/yS437Cq+wDRAxjAsCw7YEn96KEKVFuWyj78eyCU H07A== 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=DS8C9e64g1Tr1aD0/k+FxGXbkI0cBOsw5SM2h09qao8=; b=ZydAibdmFGoHDKJKa/7VSKDzYBcFoXW97nkGJSBpi7S5fqpQOZVwSXci4lV286JFWB 9KR+DEG0CBXq1QiDpV6vLeviq53YLtCWubfhT4Ee6vvJgXVUWa3BPNBI1Nm01j7NFPrZ XaYrDHhzbQu+H3TNmANjUaj5PDKTzMsUYt+A3zKxtGEZLJPpThuttCP0odSiPyPhlJYA 23U+pGKQxE0NT2hrC3tSSlh70wfAdg2CRoMQWEPFstd5FPpfE/x520AlWjycDh6q7+k4 DtqJ4xDUPVXUPB80Xjj9YKuhC4m7sV0tfpHsJRiRH3E8C6yKXU9giUXIeHwZF9b47w9r agPw== X-Gm-Message-State: AOAM533WPMIUsLIciAvPEUPNhjUTwJX3t4vMo1qJeaYy964C+O8h6t8W xk/w6iL7Lup7FaNFrMTIYHhvWDeAq0RWbsMKFw== X-Google-Smtp-Source: ABdhPJweVCr7OFutmOdfDAQOrbBi84e9nImH7UgnOhqphktYvH4DEV/w/MNQu7Fv49hqtoqVck/QvxtNmDKDRi05Og== 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:a0c:8d08:: with SMTP id r8mr13787480qvb.35.1602404985271; Sun, 11 Oct 2020 01:29:45 -0700 (PDT) Date: Sun, 11 Oct 2020 01:29:35 -0700 In-Reply-To: <20201011082936.4131726-1-lokeshgidra@google.com> Message-Id: <20201011082936.4131726-3-lokeshgidra@google.com> Mime-Version: 1.0 References: <20201011082936.4131726-1-lokeshgidra@google.com> X-Mailer: git-send-email 2.28.0.1011.ga647a8990f-goog Subject: [PATCH v10 2/3] Teach SELinux about anonymous inodes 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 , Andrew Morton 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 patch 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 Cc: Al Viro Cc: Andrew Morton --- security/selinux/hooks.c | 53 +++++++++++++++++++++++++++++ security/selinux/include/classmap.h | 2 ++ 2 files changed, 55 insertions(+) diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c index a340986aa92e..7b22c3112583 100644 --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -2926,6 +2926,58 @@ 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); + 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, + FILE__CREATE, + &ad); +} + static int selinux_inode_create(struct inode *dir, struct dentry *dentry, umode_t mode) { return may_create(dir, dentry, SECCLASS_FILE); @@ -6987,6 +7039,7 @@ 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 Sun Oct 11 08:29:36 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Lokesh Gidra X-Patchwork-Id: 11830719 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 6124D109B for ; Sun, 11 Oct 2020 08:30:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3C4A620776 for ; Sun, 11 Oct 2020 08:30:03 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="hBpVS7uF" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729123AbgJKI35 (ORCPT ); Sun, 11 Oct 2020 04:29:57 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44832 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729274AbgJKI3u (ORCPT ); Sun, 11 Oct 2020 04:29:50 -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 12D9DC0613CE for ; Sun, 11 Oct 2020 01:29:49 -0700 (PDT) Received: by mail-qk1-x74a.google.com with SMTP id m23so10537958qkh.10 for ; Sun, 11 Oct 2020 01:29:49 -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=5MfBywdxMmsLRrplRDwjfeuNu4Dz7M8KwUBLUxZj6xM=; b=hBpVS7uF0dFqV+usm5krJoTk8tnGXulcNhG8ZJQffqmJqiN/AvtuYAFH4gdM7krAf4 5Ib1hQdSL0DUZPWL/z++LUKJy8IxhRA2w+QAOv+LfPQ+YYpRjzQJCwvNAhRpalFO4xOi G1z50NqD9K8274QcDS0hen8+XCV+tHgIznVBklGHdqiIPwoQxL5C0i7MkxNIwkRG22U6 Ij6bvdO2B1/sNNhUACdwbsUxlVO81o2w0f/1AnH0QaUZztaPK6x/m8VnhMqW9Z1mKI0J BpTIQ9S8uKzPLmbXjTbUkvX2IRP7yrhbXvxq1icfcGr1nkiWu5ZAhEt7iMG4AaDY3q2/ VvUg== 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=5MfBywdxMmsLRrplRDwjfeuNu4Dz7M8KwUBLUxZj6xM=; b=rrX1/zL2FaOzpAH39Yw1P8OtF8iLpBh/dxIs3LnMr/Iy37xgjQlKs+7PESfmMcB8Xa mMAm5+k+b/+ka8DpvFcjqRS5PsrXwBF2Vsj5jsaYAHIsCbXG9fEvyIz9TNJ/ox9/pRLt bV6aBwk/ypGoa+7o+JBhJP4qUdx8iJ/oerTvdL6v3s1lEJ59cx1D1G1JE9n722ZTlg5j BMkMtJphcfTbZdUGH8PsL8yQVHcRtX2XcFBTzC1O8sMTNkeHUeesWH65VnpbBehrNqIq EzfZmIXVzJg3qEWi+SIzLJCYrv2XbFepLEAn68Bl2bIWoNnQsiVb957AtNRVZtnOC5K5 i7cQ== X-Gm-Message-State: AOAM532N7D6OEX+Doeo0BjEUTaxW//fAWfCv/MBmKKzVzY2A5ELqa9AX YbqB3ikqZb0O5wtaKoMU/d5+5rmfYp/ZjC5VJQ== X-Google-Smtp-Source: ABdhPJyXMlomivJVMqBM7X/DtGr65xVnyJaAqT/5gaTPmnqZk1jHkrChs/crGvAIfh7DexwBcSTGjZePaDlyt9H15Q== 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:a0c:b6d7:: with SMTP id h23mr20732427qve.17.1602404988144; Sun, 11 Oct 2020 01:29:48 -0700 (PDT) Date: Sun, 11 Oct 2020 01:29:36 -0700 In-Reply-To: <20201011082936.4131726-1-lokeshgidra@google.com> Message-Id: <20201011082936.4131726-4-lokeshgidra@google.com> Mime-Version: 1.0 References: <20201011082936.4131726-1-lokeshgidra@google.com> X-Mailer: git-send-email 2.28.0.1011.ga647a8990f-goog Subject: [PATCH v10 3/3] Use secure anon inodes for userfaultfd 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 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 0e4a3837da52..918535b49475 100644 --- a/fs/userfaultfd.c +++ b/fs/userfaultfd.c @@ -978,14 +978,14 @@ 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; @@ -995,7 +995,7 @@ 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); @@ -1106,7 +1106,7 @@ 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)) { /* @@ -1166,6 +1166,7 @@ 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; @@ -1173,7 +1174,7 @@ 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))) @@ -1995,8 +1996,8 @@ 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);