linux-ext4 - [RFC v2 2/4] xfs: add verifier check for symlink with append/immutable flags

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20180510231359.16899-3-mcgrof@kernel.org>
Date:   Thu, 10 May 2018 16:13:57 -0700
From:   "Luis R. Rodriguez" <mcgrof@...nel.org>
To:     viro@...iv.linux.org.uk, darrick.wong@...cle.com, tytso@....edu,
        adilger.kernel@...ger.ca, clm@...com, jbacik@...com,
        dsterba@...e.com
Cc:     sandeen@...deen.net, dhowells@...hat.com, fliu@...e.com,
        jack@...e.cz, jeffm@...e.com, nborisov@...e.com,
        jake.norris@...e.com, mtk.manpages@...il.com,
        linux-api@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        linux-xfs@...r.kernel.org, linux-ext4@...r.kernel.org,
        linux-btrfs@...r.kernel.org, linux-kernel@...r.kernel.org,
        "Luis R. Rodriguez" <mcgrof@...nel.org>
Subject: [RFC v2 2/4] xfs: add verifier check for symlink with append/immutable flags

The Linux VFS does not allow a way to set append/immuttable attributes
to symlinks, this is just not possible. If this is detected we can
correct this with xfs_repair, so inform the user.

Signed-off-by: Luis R. Rodriguez <mcgrof@...nel.org>
---
 fs/xfs/libxfs/xfs_symlink_remote.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/fs/xfs/libxfs/xfs_symlink_remote.c b/fs/xfs/libxfs/xfs_symlink_remote.c
index 5ef5f354587e..42dd81ede3d6 100644
--- a/fs/xfs/libxfs/xfs_symlink_remote.c
+++ b/fs/xfs/libxfs/xfs_symlink_remote.c
@@ -242,5 +242,10 @@ xfs_symlink_shortform_verify(
 	/* We /did/ null-terminate the buffer, right? */
 	if (*endp != 0)
 		return __this_address;
+
+	/* Immutable and append flags are not allowed on symlinks */
+	if (ip->i_d.di_flags & (XFS_DIFLAG_APPEND | XFS_DIFLAG_IMMUTABLE))
+		return __this_address;
+
 	return NULL;
 }
-- 
2.17.0