[PATCH v1 1/2] landlock: Handle weird files

Mickaël Salaün
2025-01-10T15:39:28Z

A corrupted filesystem (e.g. bcachefs) might return weird files.
Instead of throwing a warning and allowing access to such file, treat
them as regular files.

Cc: Dave Chinner <david@fromorbit.com>
Cc: Günther Noack <gnoack@google.com>
Cc: Kent Overstreet <kent.overstreet@linux.dev>
Cc: Paul Moore <paul@paul-moore.com>
Reported-by: syzbot+34b68f850391452207df@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/r/000000000000a65b35061cffca61@google.com
Reported-by: syzbot+360866a59e3c80510a62@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/r/67379b3f.050a0220.85a0.0001.GAE@google.com
Reported-by: Ubisectech Sirius <bugreport@ubisectech.com>
Closes: https://lore.kernel.org/r/c426821d-8380-46c4-a494-7008bbd7dd13.bugreport@ubisectech.com
Fixes: cb2c7d1a1776 ("landlock: Support filesystem access-control")
Signed-off-by: Mickaël Salaün <mic@digikod.net>
---
security/landlock/fs.c | 11 +++++------
1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/security/landlock/fs.c b/security/landlock/fs.c
index e31b97a9f175..7adb25150488 100644
--- a/security/landlock/fs.c
+++ b/security/landlock/fs.c
@@ -937,10 +937,6 @@ static access_mask_t get_mode_access(const umode_t mode)
switch (mode & S_IFMT) {
case S_IFLNK:
return LANDLOCK_ACCESS_FS_MAKE_SYM;
- case 0:
- /* A zero mode translates to S_IFREG. */
- case S_IFREG:
- return LANDLOCK_ACCESS_FS_MAKE_REG;
case S_IFDIR:
return LANDLOCK_ACCESS_FS_MAKE_DIR;
case S_IFCHR:
@@ -951,9 +947,12 @@ static access_mask_t get_mode_access(const umode_t mode)
return LANDLOCK_ACCESS_FS_MAKE_FIFO;
case S_IFSOCK:
return LANDLOCK_ACCESS_FS_MAKE_SOCK;
+ case S_IFREG:
+ case 0:
+ /* A zero mode translates to S_IFREG. */
default:
- WARN_ON_ONCE(1);
- return 0;
+ /* Treats weird files as regular files. */
+ return LANDLOCK_ACCESS_FS_MAKE_REG;
}
}

--
2.47.1