On Fri, Jan 10, 2025 at 05:37:26PM +0100, Günther Noack wrote: > 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? I guess it depends on the filesystem implementation. For instance, XFS returns an error if a weird file is detected [1], whereas bcachefs ignores it (which is considered a bug, but not fixed yet) [2]. [1] https://lore.kernel.org/all/Zpc46HEacI%2Fwd7Rg@xxxxxxxxxxxxxxxxxxx/ [2] https://lore.kernel.org/all/4hohnthh54adx35lnxzedop3oxpntpmtygxso4iraiexfdlt4d@6m7ssepvjyar/ > > –Günther >
