Re: [LTP] [PATCH] ioctl_ficlone03: fix capabilities on immutable files

[Petr Vorel <pvorel@suse.cz>]

Hi Kent,

> On Wed, Mar 26, 2025 at 02:47:49PM +0100, Petr Vorel wrote:
> > Hi all,

> > [ Cc Kent and other filesystem folks to be sure we don't hide a bug ]

> I'm missing context here, and the original thread doesn't seem to be on
> lore?

I'm sorry, to put more info: this is an attempt to fix of LTP test
ioctl_ficlone03.c [1], which is failing on 32 bit compatibility mode:

# ./ioctl_ficlone03
tst_test.c:1833: TINFO: === Testing on bcachefs ===
..
ioctl_ficlone03.c:74: TBROK: ioctl .. failed: ENOTTY (25)
ioctl_ficlone03.c:89: TWARN: ioctl ..  failed: ENOTTY (25)
ioctl_ficlone03.c:91: TWARN: ioctl ..  failed: ENOTTY (25)
ioctl_ficlone03.c:98: TWARN: close(-1) failed: EBADF (9)

Original thread of this is on LTP ML [2].

Kind regards,
Petr

[1] https://github.com/linux-test-project/ltp/tree/master/testcases/kernel/syscalls/ioctl/ioctl_ficlone03.c
[2] https://lore.kernel.org/ltp/20250326-fix_ioctl_ficlone03_32bit_bcachefs-v1-1-554a0315ebf5@suse.com/

> > > From: Andrea Cervesato <andrea.cervesato@suse.com>

> > > Make sure that capabilities requirements are satisfied when accessing
> > > immutable files. On OpenSUSE Tumbleweed 32bit bcachefs fails with the
> > > following error due to missing capabilities:

> > > tst_test.c:1833: TINFO: === Testing on bcachefs ===
> > > ..
> > > ioctl_ficlone03.c:74: TBROK: ioctl .. failed: ENOTTY (25)
> > > ioctl_ficlone03.c:89: TWARN: ioctl ..  failed: ENOTTY (25)
> > > ioctl_ficlone03.c:91: TWARN: ioctl ..  failed: ENOTTY (25)
> > > ioctl_ficlone03.c:98: TWARN: close(-1) failed: EBADF (9)

> > > Introduce CAP_LINUX_IMMUTABLE capability to make sure that test won't
> > > fail on other systems as well.

> > > Signed-off-by: Andrea Cervesato <andrea.cervesato@suse.com>
> > > ---
> > >  testcases/kernel/syscalls/ioctl/ioctl_ficlone03.c | 6 +++++-
> > >  1 file changed, 5 insertions(+), 1 deletion(-)

> > > diff --git a/testcases/kernel/syscalls/ioctl/ioctl_ficlone03.c b/testcases/kernel/syscalls/ioctl/ioctl_ficlone03.c
> > > index 6a9d270d9fb56f3a263f0aed976f62c4576e6a5f..6716423d9c96d9fc1d433f28e0ae1511b912ae2c 100644
> > > --- a/testcases/kernel/syscalls/ioctl/ioctl_ficlone03.c
> > > +++ b/testcases/kernel/syscalls/ioctl/ioctl_ficlone03.c
> > > @@ -122,5 +122,9 @@ static struct tst_test test = {
> > >  	.bufs = (struct tst_buffers []) {
> > >  		{&clone_range, .size = sizeof(struct file_clone_range)},
> > >  		{},
> > > -	}
> > > +	},
> > > +	.caps = (struct tst_cap []) {
> > > +		TST_CAP(TST_CAP_REQ, CAP_LINUX_IMMUTABLE),
> > > +		{}
> > > +	},

> > Reviewed-by: Petr Vorel <pvorel@suse.cz>

> > LGTM, obviously it is CAP_LINUX_IMMUTABLE related.

> > This looks like fs/bcachefs/fs-ioctl.c

> > static int bch2_inode_flags_set(struct btree_trans *trans,
> > 				struct bch_inode_info *inode,
> > 				struct bch_inode_unpacked *bi,
> > 				void *p)
> > {
> > 	...
> > 	if (((newflags ^ oldflags) & (BCH_INODE_append|BCH_INODE_immutable)) &&
> > 	    !capable(CAP_LINUX_IMMUTABLE))
> > 		return -EPERM;


> > We don't test on vfat and exfat. If I try to do it fail the same way (bcachefs,
> > fat, exfat and ocfs2 use custom handler for FAT_IOCTL_SET_ATTRIBUTES).

> > I wonder why it does not fail for generic VFS fs/ioctl.c used by Btrfs and XFS:

> > /*
> >  * Generic function to check FS_IOC_FSSETXATTR/FS_IOC_SETFLAGS values and reject
> >  * any invalid configurations.
> >  *
> >  * Note: must be called with inode lock held.
> >  */
> > static int fileattr_set_prepare(struct inode *inode,
> > 			      const struct fileattr *old_ma,
> > 			      struct fileattr *fa)
> > {
> > 	int err;

> > 	/*
> > 	 * The IMMUTABLE and APPEND_ONLY flags can only be changed by
> > 	 * the relevant capability.
> > 	 */
> > 	if ((fa->flags ^ old_ma->flags) & (FS_APPEND_FL | FS_IMMUTABLE_FL) &&
> > 	    !capable(CAP_LINUX_IMMUTABLE))
> > 		return -EPERM;


> > Kind regards,
> > Petr

> > >  };

> > > ---
> > > base-commit: 753bd13472d4be44eb70ff183b007fe9c5fffa07
> > > change-id: 20250326-fix_ioctl_ficlone03_32bit_bcachefs-2ec15bd6c0c6

> > > Best regards,