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

On 2021-06-02 09:26, Pavel Begunkov wrote:

On 5/28/21 5:02 PM, Paul Moore wrote:

quoted

On Wed, May 26, 2021 at 4:19 PM Paul Moore [off-list ref] wrote:

quoted

... 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 [off-list ref]
Sr. S/W Engineer, Kernel Security, Base Operating Systems
Remote, Ottawa, Red Hat Canada
IRC: rgb, SunRaycer
Voice: +1.647.777.2635, Internal: (81) 32635