Re: [RFC PATCH 2/9] audit,io_uring,io-wq: add some basic audit support to io_uring

Richard Guy Briggs
2021-06-02T15:46:54Z

On 2021-06-02 09:26, Pavel Begunkov wrote:
> On 5/28/21 5:02 PM, Paul Moore wrote:
> > On Wed, May 26, 2021 at 4:19 PM Paul Moore <paul@paul-moore.com> wrote:
> >> ... If we moved the _entry
> >> and _exit calls into the individual operation case blocks (quick
> >> openat example below) so that only certain operations were able to be
> >> audited would that be acceptable assuming the high frequency ops were
> >> untouched? My initial gut feeling was that this would involve >50% of
> >> the ops, but Steve Grubb seems to think it would be less; it may be
> >> time to look at that a bit more seriously, but if it gets a NACK
> >> regardless it isn't worth the time - thoughts?
> >>
> >> case IORING_OP_OPENAT:
> >> audit_uring_entry(req->opcode);
> >> ret = io_openat(req, issue_flags);
> >> audit_uring_exit(!ret, ret);
> >> break;
> >
> > I wanted to pose this question again in case it was lost in the
> > thread, I suspect this may be the last option before we have to "fix"
> > things at the Kconfig level. I definitely don't want to have to go
> > that route, and I suspect most everyone on this thread feels the same,
> > so I'm hopeful we can find a solution that is begrudgingly acceptable
> > to both groups.
>
> May work for me, but have to ask how many, and what is the
> criteria? I'd think anything opening a file or manipulating fs:
>
> IORING_OP_ACCEPT, IORING_OP_CONNECT, IORING_OP_OPENAT[2],
> IORING_OP_RENAMEAT, IORING_OP_UNLINKAT, IORING_OP_SHUTDOWN,
> IORING_OP_FILES_UPDATE
> + coming mkdirat and others.
>
> IORING_OP_CLOSE? IORING_OP_SEND IORING_OP_RECV?
>
> What about?
> IORING_OP_FSYNC, IORING_OP_SYNC_FILE_RANGE,
> IORING_OP_FALLOCATE, IORING_OP_STATX,
> IORING_OP_FADVISE, IORING_OP_MADVISE,
> IORING_OP_EPOLL_CTL
>
>
> Another question, io_uring may exercise asynchronous paths,
> i.e. io_issue_sqe() returns before requests completes.
> Shouldn't be the case for open/etc at the moment, but was that
> considered?

This would be why audit needs to monitor a thread until it wraps up, to
wait for the result code. My understanding is that both sync and async
parts of an op would be monitored.

> I don't see it happening, but would prefer to keep it open
> async reimplementation in a distant future. Does audit sleep?

Some parts do, some parts don't depending on what they are interacting
with in the kernel. It can be made to not sleep if needed.

> Pavel Begunkov

- RGB

--
Richard Guy Briggs <rgb@redhat.com>
Sr. S/W Engineer, Kernel Security, Base Operating Systems
Remote, Ottawa, Red Hat Canada
IRC: rgb, SunRaycer
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