Re: [PATCH] Smack: Provide read control for io_uring_cmd

[Paul Moore <paul@paul-moore.com>]

On Fri, Aug 26, 2022 at 3:04 PM Casey Schaufler <casey@schaufler-ca.com> wrote:
> On 8/26/2022 11:59 AM, Paul Moore wrote:
> > On Fri, Aug 26, 2022 at 12:53 PM Casey Schaufler <casey@schaufler-ca.com> wrote:
> >> On 8/26/2022 8:15 AM, Paul Moore wrote:
> >>> On Tue, Aug 23, 2022 at 8:07 PM Jens Axboe <axboe@kernel.dk> wrote:
> >>>> On 8/23/22 6:05 PM, Paul Moore wrote:
> >>>>> On Tue, Aug 23, 2022 at 7:46 PM Casey Schaufler <casey@schaufler-ca.com> wrote:
> >>>>>> Limit io_uring "cmd" options to files for which the caller has
> >>>>>> Smack read access. There may be cases where the cmd option may
> >>>>>> be closer to a write access than a read, but there is no way
> >>>>>> to make that determination.
> >>>>>>
> >>>>>> Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
> >>>>>> --
> >>>>>>  security/smack/smack_lsm.c | 32 ++++++++++++++++++++++++++++++++
> >>>>>>  1 file changed, 32 insertions(+)
> >>>>>>
> >>>>>> diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
> >>>>>> index 001831458fa2..bffccdc494cb 100644
> >>>>>> --- a/security/smack/smack_lsm.c
> >>>>>> +++ b/security/smack/smack_lsm.c
> >>>>> ...
> >>>>>
> >>>>>> @@ -4732,6 +4733,36 @@ static int smack_uring_sqpoll(void)
> >>>>>>         return -EPERM;
> >>>>>>  }
> >>>>>>
> >>>>>> +/**
> >>>>>> + * smack_uring_cmd - check on file operations for io_uring
> >>>>>> + * @ioucmd: the command in question
> >>>>>> + *
> >>>>>> + * Make a best guess about whether a io_uring "command" should
> >>>>>> + * be allowed. Use the same logic used for determining if the
> >>>>>> + * file could be opened for read in the absence of better criteria.
> >>>>>> + */
> >>>>>> +static int smack_uring_cmd(struct io_uring_cmd *ioucmd)
> >>>>>> +{
> >>>>>> +       struct file *file = ioucmd->file;
> >>>>>> +       struct smk_audit_info ad;
> >>>>>> +       struct task_smack *tsp;
> >>>>>> +       struct inode *inode;
> >>>>>> +       int rc;
> >>>>>> +
> >>>>>> +       if (!file)
> >>>>>> +               return -EINVAL;
> >>>>> Perhaps this is a better question for Jens, but ioucmd->file is always
> >>>>> going to be valid when the LSM hook is called, yes?
> >>>> file will always be valid for uring commands, as they are marked as
> >>>> requiring a file. If no valid fd is given for it, it would've been
> >>>> errored early on, before reaching f_op->uring_cmd().
> >>> Hey Casey, where do things stand with this patch?  To be specific, did
> >>> you want me to include this in the lsm/stable-6.0 PR for Linus or are
> >>> you planning to send it separately?  If you want me to send it up, are
> >>> you planning another revision?
> >>>
> >>> There is no right or wrong answer here as far as I'm concerned, I'm
> >>> just trying to make sure we are all on the same page.
> >> I think the whole LSM fix for io_uring looks better the more complete
> >> it is. I don't see the Smack check changing until such time as there's
> >> better information available to make decisions upon. If you send it along
> >> with the rest of the patch set I think we'll have done our best.
> > Okay, will do.  Would you like me to tag the patch with the 'Fixes:'
> > and stable tags, similar to the LSM and SELinux patches?
>
> Yes, I think that's best.

Done and merged to lsm/stable-6.0.  I'm going to let the automated
stuff do it's thing and assuming no problems I'll plan to send it to
Linus on Monday ... sending stuff like this last thing on a Friday is
a little too risky for my tastes.

-- 
paul-moore.com