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 A0A2B2DC34C; Tue, 8 Jul 2025 16:45:20 +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=1751993120; cv=none; b=qqShQ7VGmrhDCkyn3R6HcgCaMoOBvTCy9cbDZS0ryKwZL3OMe0EcRDjqO9VXB956ZfdgGb1I0Eep+ydHT12Oktuz+oBVdsxK7mOV2jlfGMULRQNHQCiMTh152kbF2PiYVCPdZ0DWfdg5hdm4aRAfKcSm6Y7kmbmbGnkf2AC82Kc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751993120; c=relaxed/simple; bh=lqyDJ3feoC4OumPcZJ2+4jBLLd8ThJDbsivB4ixX7f8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=lWTo9reDj1DZF/5eYwSE1hwBMheSvgCW766u5nqotVAowWXydPizhl2dqy+6IGw6MgxNj9jmF/7Fpejg5aOeFGGNiwupCPlqCBQRWbEZZCyt9wEpFVbTnpXheV5knRG4R7plzE0Qtg8W7kp1H8wDx+P7GToU546UBDQbpUmCWFI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=YxqVvDqa; 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="YxqVvDqa" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1495EC4CEED; Tue, 8 Jul 2025 16:45:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1751993120; bh=lqyDJ3feoC4OumPcZJ2+4jBLLd8ThJDbsivB4ixX7f8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=YxqVvDqaTpeH21OSQGzruJP1RMn9OUhbxs9pVbHi0g8dYHF3s+crY3lQ4/fwM+Gqj haQnWeVuJ6UL3OAKVqzwd4VVkJtA696DX5gawBBMALak3oKwOa//D7Ue93w3AErDv+ +40MmKCn9oCuQrwjZCX5POdpjEET4/fk+qCxF8IE= 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 6.12 193/232] fs: export anon_inode_make_secure_inode() and fix secretmem LSM bypass Date: Tue, 8 Jul 2025 18:23:09 +0200 Message-ID: <20250708162246.485897385@linuxfoundation.org> X-Mailer: git-send-email 2.50.0 In-Reply-To: <20250708162241.426806072@linuxfoundation.org> References: <20250708162241.426806072@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 6.12-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 583ac81669c24..35f765610802a 100644 --- a/fs/anon_inodes.c +++ b/fs/anon_inodes.c @@ -55,14 +55,25 @@ 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; @@ -74,6 +85,7 @@ 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, @@ -88,7 +100,8 @@ 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 b98f128c9afa7..a6de8d93838d1 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -3407,6 +3407,8 @@ 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