On 8/26/2022 8:15 AM, Paul Moore wrote:
> On Tue, Aug 23, 2022 at 8:07 PM Jens Axboe <axboe@xxxxxxxxx> wrote:
>> On 8/23/22 6:05 PM, Paul Moore wrote:
>>> On Tue, Aug 23, 2022 at 7:46 PM Casey Schaufler <casey@xxxxxxxxxxxxxxxx> 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@xxxxxxxxxxxxxxxx>
>>>> --
>>>> 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.
