landlock: Handle weird files

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: 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")
Reviewed-by: Günther Noack <gnoack3000@gmail.com>
Link: https://lore.kernel.org/r/20250110153918.241810-1-mic@digikod.net
Signed-off-by: Mickaël Salaün <mic@digikod.net>

diff --git a/security/landlock/fs.c b/security/landlock/fs.c
index e31b97a9f175aad782517d52b92aa03dc66736c6..7adb25150488fc07f349e0a690e10e85c5c10a52 100644 (file)
--- 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;
        }
 }