From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 278D22DFA22; Tue, 8 Jul 2025 16:50:43 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751993443; cv=none; b=N2oETJs6lCGzArFxJIP0z1lM2KCnWmYW7rNc9nynfAOkDVO2zJOPXG9U5tMEYmlNwMknLrscEoTshomuf1cx/HokjcoF0N1HklTWx/R5Md73cFijUCb7xqJU8Xel//AkHaFPtVRvsQXQshB65rHTkfzN4ZnFm9t5maYGRCUktbo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751993443; c=relaxed/simple; bh=tV+mMAAWlvRD/3fESGFsOqpiTy09Oo2JwT4McET0OoY=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=NAoB5CqjIgO0mEY73C9j9RDIRIVkYdoPj7+Ziih9YLI70i0TQdytbhQDkVtR3FiRdKcLO8TQ+7JMmYCbb6a4Wuu4P/3BN4zFN1usqViSVjHpx2xDeVmcVICKnrOS5ftL4xh/+aFz8nOn5A4RXHnJFcn+74PIS6nwFgFSBqzi44A= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=KABz33j8; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="KABz33j8" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A3F66C4CEED; Tue, 8 Jul 2025 16:50:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1751993443; bh=tV+mMAAWlvRD/3fESGFsOqpiTy09Oo2JwT4McET0OoY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=KABz33j8qcjdAP+d3Tvs1UDpCFuI9X5npgzrKxHLHf7dUEtNqpSrUML4r0gm5ywdY WtEQ85cdiaJKcYOu3F9+KpfXQCkk6Bel+ioaruHvBGwsJPG+pnRW9SAEMYvaZrSfUt glmHAjOBrFWBof3fFPXMVfDs5saIZOQAYli+E1ME= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, David Hildenbrand , Mike Rapoport , Shivank Garg , Christian Brauner , Sasha Levin Subject: [PATCH 6.15 046/178] fs: export anon_inode_make_secure_inode() and fix secretmem LSM bypass Date: Tue, 8 Jul 2025 18:21:23 +0200 Message-ID: <20250708162237.889805541@linuxfoundation.org> X-Mailer: git-send-email 2.50.0 In-Reply-To: <20250708162236.549307806@linuxfoundation.org> References: <20250708162236.549307806@linuxfoundation.org> User-Agent: quilt/0.68 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Shivank Garg [ Upstream commit cbe4134ea4bc493239786220bd69cb8a13493190 ] Export anon_inode_make_secure_inode() to allow KVM guest_memfd to create anonymous inodes with proper security context. This replaces the current pattern of calling alloc_anon_inode() followed by inode_init_security_anon() for creating security context manually. This change also fixes a security regression in secretmem where the S_PRIVATE flag was not cleared after alloc_anon_inode(), causing LSM/SELinux checks to be bypassed for secretmem file descriptors. As guest_memfd currently resides in the KVM module, we need to export this symbol for use outside the core kernel. In the future, guest_memfd might be moved to core-mm, at which point the symbols no longer would have to be exported. When/if that happens is still unclear. Fixes: 2bfe15c52612 ("mm: create security context for memfd_secret inodes") Suggested-by: David Hildenbrand Suggested-by: Mike Rapoport Signed-off-by: Shivank Garg Link: https://lore.kernel.org/20250620070328.803704-3-shivankg@amd.com Acked-by: "Mike Rapoport (Microsoft)" Signed-off-by: Christian Brauner Signed-off-by: Sasha Levin --- fs/anon_inodes.c | 23 ++++++++++++++++++----- include/linux/fs.h | 2 ++ mm/secretmem.c | 9 +-------- 3 files changed, 21 insertions(+), 13 deletions(-) diff --git a/fs/anon_inodes.c b/fs/anon_inodes.c index e51e7d88980a2..1d847a939f29a 100644 --- a/fs/anon_inodes.c +++ b/fs/anon_inodes.c @@ -98,14 +98,25 @@ static struct file_system_type anon_inode_fs_type = { .kill_sb = kill_anon_super, }; -static struct inode *anon_inode_make_secure_inode( - const char *name, - const struct inode *context_inode) +/** + * anon_inode_make_secure_inode - allocate an anonymous inode with security context + * @sb: [in] Superblock to allocate from + * @name: [in] Name of the class of the newfile (e.g., "secretmem") + * @context_inode: + * [in] Optional parent inode for security inheritance + * + * The function ensures proper security initialization through the LSM hook + * security_inode_init_security_anon(). + * + * Return: Pointer to new inode on success, ERR_PTR on failure. + */ +struct inode *anon_inode_make_secure_inode(struct super_block *sb, const char *name, + const struct inode *context_inode) { struct inode *inode; int error; - inode = alloc_anon_inode(anon_inode_mnt->mnt_sb); + inode = alloc_anon_inode(sb); if (IS_ERR(inode)) return inode; inode->i_flags &= ~S_PRIVATE; @@ -118,6 +129,7 @@ static struct inode *anon_inode_make_secure_inode( } return inode; } +EXPORT_SYMBOL_GPL_FOR_MODULES(anon_inode_make_secure_inode, "kvm"); static struct file *__anon_inode_getfile(const char *name, const struct file_operations *fops, @@ -132,7 +144,8 @@ static struct file *__anon_inode_getfile(const char *name, return ERR_PTR(-ENOENT); if (make_inode) { - inode = anon_inode_make_secure_inode(name, context_inode); + inode = anon_inode_make_secure_inode(anon_inode_mnt->mnt_sb, + name, context_inode); if (IS_ERR(inode)) { file = ERR_CAST(inode); goto err; diff --git a/include/linux/fs.h b/include/linux/fs.h index ef41a8213a6fa..1fe7bf10d442c 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -3552,6 +3552,8 @@ extern int simple_write_begin(struct file *file, struct address_space *mapping, extern const struct address_space_operations ram_aops; extern int always_delete_dentry(const struct dentry *); extern struct inode *alloc_anon_inode(struct super_block *); +struct inode *anon_inode_make_secure_inode(struct super_block *sb, const char *name, + const struct inode *context_inode); extern int simple_nosetlease(struct file *, int, struct file_lease **, void **); extern const struct dentry_operations simple_dentry_operations; diff --git a/mm/secretmem.c b/mm/secretmem.c index 1b0a214ee5580..4662f2510ae5f 100644 --- a/mm/secretmem.c +++ b/mm/secretmem.c @@ -195,18 +195,11 @@ static struct file *secretmem_file_create(unsigned long flags) struct file *file; struct inode *inode; const char *anon_name = "[secretmem]"; - int err; - inode = alloc_anon_inode(secretmem_mnt->mnt_sb); + inode = anon_inode_make_secure_inode(secretmem_mnt->mnt_sb, anon_name, NULL); if (IS_ERR(inode)) return ERR_CAST(inode); - err = security_inode_init_security_anon(inode, &QSTR(anon_name), NULL); - if (err) { - file = ERR_PTR(err); - goto err_free_inode; - } - file = alloc_file_pseudo(inode, secretmem_mnt, "secretmem", O_RDWR, &secretmem_fops); if (IS_ERR(file)) -- 2.39.5