On Fri, Jan 10, 2025 at 04:39:13PM +0100, Mickaël Salaün wrote: > 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@xxxxxxxxxxxxx> > Cc: Günther Noack <gnoack@xxxxxxxxxx> > Cc: Kent Overstreet <kent.overstreet@xxxxxxxxx> > Cc: Paul Moore <paul@xxxxxxxxxxxxxx> > Reported-by: syzbot+34b68f850391452207df@xxxxxxxxxxxxxxxxxxxxxxxxx > Closes: https://lore.kernel.org/r/000000000000a65b35061cffca61@xxxxxxxxxx > Reported-by: syzbot+360866a59e3c80510a62@xxxxxxxxxxxxxxxxxxxxxxxxx > Closes: https://lore.kernel.org/r/67379b3f.050a0220.85a0.0001.GAE@xxxxxxxxxx > Reported-by: Ubisectech Sirius <bugreport@xxxxxxxxxxxxxx> > Closes: https://lore.kernel.org/r/c426821d-8380-46c4-a494-7008bbd7dd13.bugreport@xxxxxxxxxxxxxx > Fixes: cb2c7d1a1776 ("landlock: Support filesystem access-control") > Signed-off-by: Mickaël Salaün <mic@xxxxxxxxxxx> > --- > 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 > Reviewed-by: Günther Noack <gnoack3000@xxxxxxxxx> Makes sense to me, since this is enforcing a stronger check than before and can only happen in the case of corruption. I do not have a good intuition about what happens afterwards when the file system is in such a state. I imagine that this will usually give an error shortly afterwards, as the opening of the file continues? Is that right? –Günther
