From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794050004; b=pj9k1JZ3tV0HknBb8Jn+3gUj0AFKaY/X/BlEM0pddbc5tff79XX32KSUPRxQD+kaVsKw gmALtLUhXDPP5Y3D4fGoPjysA+7oll/G3XIXnyDq+aBQe6C1ujykdkBHHsDoUX/md0gSs ItbZPljrneemP5COFZI9t277fJlA1adSarCtDj2ZwXagLHaRQMtJMGdFQfzHdyf4+QEUs 0H5Fo8w4V2STO6jm3ptLn2DZyCRI0LLAPWiIWDihVctOIjE3KA9kCWrb1RF2IsSWH0GOk qUrKIhDYanq7Rqy3J3OQx1QFfmckibfLvsviDPD/V5volaR27wWNRktva2BxG27njqA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794050004; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: MIME-Version:Content-Type:Content-Transfer-Encoding; bh=atQUjQAqecxrTPTKvFOeZa4T7rBwBHRlRzqkdvvUVKo=; b=sJgbT/5SX+cYk6/Wr3rCP5gaIVIJiqH91V/xP8F/yQufduIysiEVxGaZ/3h9yrjPrPTl a0yBJntUG3drP5ukZ9BjY2yUTns4z48EUdNp/bEzpD7vm0AFOgfFaMtNVRJWvhvuBAbcw ae23XJg5PcNzRie8kG1YRwJ4yhAMP1vTsMnESdpBAc1ctWD6aeHLcXxgqUjBrcdj75LIj sz+aJ6d8/C5kz2g0LKIpTw1EslHZ+jFuJZJNCE0iMOf0hZMX7lJGVfMSRzwhPfNT1FIsR lnonB5mz1rs2aUYgorG2unOgI4MAie5K9ty5xOE7IbnLEZIR9l/V2ZTgf+sQWcMZELw== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=BWbJFqEQ; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 82106606A326 for ; Sat, 7 Nov 2026 11:13:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=BWbJFqEQ Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0181B1F0089F; Sat, 7 Nov 2026 11:13:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794050004; bh=atQUjQAqecxrTPTKvFOeZa4T7rBwBHRlRzqkdvvUVKo=; h=From:To:Cc:Subject:Date; b=BWbJFqEQ2WHa+F+RXPCEvIXahVWePuZjktXwd4ltyrMw3/4KN+a/L1LApK7gG1ebf Ryub5TB5Qv2sAVBhQJ2qas02nwDqeF6uVWjb53L2eUAbS85MHbjTBtlTzIhtY0feJ1 tZsQrRIYGxclASFEWiQgCOMkxoYnOiqB1RO6ZayaI0TWrYnQY/WWjWc5R1/kSJx1F+ y8q3kQdcigN38DABCgxs6Trl8Dac7/ZjXCn15lY6tOfpRIGj1Wqu2MkpQnXPdEcYc7 urOQfR9Wa71gp+mtTk6PxhKwdSiBa6z+5yyRe10mr2mHhXHbOvBxhPlUaCSDqtCB5w ficcvZ+vzvasQ== From: Sasha Levin To: ebiggers@kernel.org, aalbersh@kernel.org Cc: stable@vger.kernel.org Subject: FAILED: patch "[PATCH] fsverity: Explicitly require FMODE_READ to retrieve hashes" failed to apply to 5.15-stable tree Date: Sat, 7 Nov 2026 06:13:22 -0500 Message-ID: <20261107061322-failed-5.15-1acb4fd2d011@kernel.org> X-Mailer: git-send-email 2.53.0 X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The patch below does not apply to the 5.15-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y git checkout FETCH_HEAD git cherry-pick -x 1acb4fd2d011c4bd6cc961095ae17361c71ff61a # git commit -s git send-email --to '' --in-reply-to '20261107061322-failed-5.15-1acb4fd2d011@kernel.org' --subject-prefix 'PATCH 5.15.y' 'HEAD^..' Thanks, Sasha ------------------ original commit in Linus's tree ------------------ >From 1acb4fd2d011c4bd6cc961095ae17361c71ff61a Mon Sep 17 00:00:00 2001 From: Eric Biggers Date: Thu, 22 Oct 2026 21:15:22 +0000 Subject: [PATCH] fsverity: Explicitly require FMODE_READ to retrieve hashes The comment in fsverity_ioctl_read_metadata(), which justifies not checking for FMODE_READ, doesn't consider that the nonstandard access mode 3 (ioctl-only) exists. Opening an ioctl-only fd generally requires read (and write) permission. However, there are gaps with certain LSMs: an ioctl-only fd requests read (and write) permission via security_inode_permission, but not security_file_open. With certain LSMs relying on the latter, such as Landlock and AppArmor, an ioctl-only fd can be opened without the LSM granting read (and write) permission. Since FS_IOC_READ_VERITY_METADATA returns hashes of file contents blocks, it should require read permission. This also applies to FS_IOC_MEASURE_VERITY, which returns a hash for the whole file. Meanwhile, ioctl-only fds are a rarely-used feature, not known to be used with either ioctl. Therefore, just disallow these ioctls on ioctl-only file descriptors, similar to what was already done with FS_IOC_ENABLE_VERITY. More specifically, explicitly check for FMODE_READ. This also covers write-only fds to non-verity files which otherwise would have failed with ENODATA. This change in error code for write-only fds should be fine too, as these ioctls cannot be usefully used with write-only fds anyway, but it's worth noting as another technicality. Fixes: 4dd893d832cf ("fs-verity: implement FS_IOC_MEASURE_VERITY ioctl") Fixes: e17fe6579de0 ("fs-verity: add FS_IOC_READ_VERITY_METADATA ioctl") Cc: stable@vger.kernel.org Reviewed-by: Andrey Albershteyn Link: https://patch.msgid.link/20261022211522.1489943-1-ebiggers@kernel.org Signed-off-by: Eric Biggers --- Documentation/filesystems/fsverity.rst | 3 +++ fs/verity/measure.c | 10 ++++++++++ fs/verity/read_metadata.c | 14 ++++++++++---- 3 files changed, 23 insertions(+), 4 deletions(-) diff --git a/Documentation/filesystems/fsverity.rst b/Documentation/filesystems/fsverity.rst index 22b49b295d1f9..e5d38439bf585 100644 --- a/Documentation/filesystems/fsverity.rst +++ b/Documentation/filesystems/fsverity.rst @@ -170,6 +170,7 @@ fatal signal), no changes are made to the file. FS_IOC_ENABLE_VERITY can fail with the following errors: - ``EACCES``: the process does not have write access to the file +- ``EBADF``: the file descriptor is not open for reading - ``EBADMSG``: the builtin signature is malformed - ``EBUSY``: this ioctl is already running on the file - ``EEXIST``: the file already has verity enabled @@ -232,6 +233,7 @@ regardless of the size of the file. FS_IOC_MEASURE_VERITY can fail with the following errors: +- ``EBADF``: the file descriptor is not open for reading - ``EFAULT``: the caller provided inaccessible memory - ``ENODATA``: the file is not a verity file - ``ENOTTY``: this type of filesystem does not implement fs-verity @@ -310,6 +312,7 @@ blocks from disk without actually verifying the path to the root node. FS_IOC_READ_VERITY_METADATA can fail with the following errors: +- ``EBADF``: the file descriptor is not open for reading - ``EFAULT``: the caller provided inaccessible memory - ``EINTR``: the ioctl was interrupted before any data was read - ``EINVAL``: reserved fields were set, or ``offset + length`` diff --git a/fs/verity/measure.c b/fs/verity/measure.c index 68dfccb697720..0c75616dca011 100644 --- a/fs/verity/measure.c +++ b/fs/verity/measure.c @@ -31,6 +31,16 @@ int fsverity_ioctl_measure(struct file *filp, void __user *_uarg) const struct fsverity_hash_alg *hash_alg; struct fsverity_digest arg; + /* + * This ioctl returns a hash of the file contents, so it should require + * read permission. Disallow it on ioctl-only (i.e., nonstandard access + * mode 3) fds, which can in some cases be acquired without passing all + * LSM read-permission checks. Also disallow write-only fds, which can + * refer only to non-verity files which would fail with ENODATA anyway. + */ + if (!(filp->f_mode & FMODE_READ)) + return -EBADF; + vi = fsverity_get_info(inode); if (!vi) return -ENODATA; /* not a verity file */ diff --git a/fs/verity/read_metadata.c b/fs/verity/read_metadata.c index b4c0892430cde..6694149f7b467 100644 --- a/fs/verity/read_metadata.c +++ b/fs/verity/read_metadata.c @@ -166,13 +166,19 @@ int fsverity_ioctl_read_metadata(struct file *filp, const void __user *uarg) int length; void __user *buf; + /* + * This ioctl returns file contents block hashes, so it should require + * read permission. Disallow it on ioctl-only (i.e., nonstandard access + * mode 3) fds, which can in some cases be acquired without passing all + * LSM read-permission checks. Also disallow write-only fds, which can + * refer only to non-verity files which would fail with ENODATA anyway. + */ + if (!(filp->f_mode & FMODE_READ)) + return -EBADF; + vi = fsverity_get_info(inode); if (!vi) return -ENODATA; /* not a verity file */ - /* - * Note that we don't have to explicitly check that the file is open for - * reading, since verity files can only be opened for reading. - */ if (copy_from_user(&arg, uarg, sizeof(arg))) return -EFAULT; -- 2.53.0