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From: Paul Moore <paul@paul-moore.com>
To: Richard Guy Briggs <rgb@redhat.com>
Cc: linux-security-module@vger.kernel.org, selinux@vger.kernel.org,
	linux-audit@redhat.com, io-uring@vger.kernel.org,
	linux-fsdevel@vger.kernel.org, Jens Axboe <axboe@kernel.dk>,
	Pavel Begunkov <asml.silence@gmail.com>,
	Kumar Kartikeya Dwivedi <memxor@gmail.com>
Subject: Re: [PATCH v4 2/8] audit,io_uring,io-wq: add some basic audit support to io_uring
Date: Thu, 16 Sep 2021 10:02:35 -0400	[thread overview]
Message-ID: <CAHC9VhSEj8b7+jH9Atkj3FH+SOdc5iwytxhS3_O1HmTahdj3dQ@mail.gmail.com> (raw)
In-Reply-To: <20210916133308.GP490529@madcap2.tricolour.ca>

On Thu, Sep 16, 2021 at 9:33 AM Richard Guy Briggs <rgb@redhat.com> wrote:
> On 2021-09-15 12:49, Paul Moore wrote:
> > This patch adds basic auditing to io_uring operations, regardless of
> > their context.  This is accomplished by allocating audit_context
> > structures for the io-wq worker and io_uring SQPOLL kernel threads
> > as well as explicitly auditing the io_uring operations in
> > io_issue_sqe().  Individual io_uring operations can bypass auditing
> > through the "audit_skip" field in the struct io_op_def definition for
> > the operation; although great care must be taken so that security
> > relevant io_uring operations do not bypass auditing; please contact
> > the audit mailing list (see the MAINTAINERS file) with any questions.
> >
> > The io_uring operations are audited using a new AUDIT_URINGOP record,
> > an example is shown below:
> >
> >   type=UNKNOWN[1336] msg=audit(1630523381.288:260):
> >     uring_op=19 success=yes exit=0 items=0 ppid=853 pid=1204
> >     uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0
> >     subj=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023
> >     key=(null)
> >     AUID="root" UID="root" GID="root" EUID="root" SUID="root"
> >     FSUID="root" EGID="root" SGID="root" FSGID="root"
> >
> > Thanks to Richard Guy Briggs for review and feedback.
>
> I share Steve's concerns about the missing auid and ses.  The userspace
> log interpreter conjured up AUID="root" from the absent auid=.
>
> Some of the creds are here including ppid, pid, a herd of *id and subj.
> *Something* initiated this action and then delegated it to iouring to
> carry out.  That should be in there somewhere.  You had a concern about
> shared queues and mis-attribution.  All of these creds including auid
> and ses should be kept together to get this right.

Look, there are a lot of things about io_uring that frustrate me from
a security perspective - this is one of them - but I've run out of
ways to say it's not possible to reliably capture the audit ID or
session ID here.  With io_uring it is possible to submit an io_uring
operation, and capture the results, by simply reading and writing to a
mmap'd buffer.  Yes, it would be nice to have that information, but I
don't believe there is a practical way to capture it.  If you have any
suggestions on how to do so, please share, but please make it
concrete; hand wavy solutions aren't useful at this stage.

As for the userspace mysteriously creating an AUID out of thin air,
that was my mistake: I simply removed the "auid=" field from the
example and didn't remove the additional fields, e.g. AUID, that
auditd appends to the end of the record.  I've updated the commit
description with a freshly generated record and removed the auditd
bonus bits as those probably shouldn't be shown in an example of a
kernel generated audit record.  I'm not going to repost the patchset
just for this small edit to the description, but I have force-pushed
the update to the selinux/working-io_uring branch.

-- 
paul moore
www.paul-moore.com

  reply	other threads:[~2021-09-16 14:03 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-15 16:49 [PATCH v4 0/8] Add LSM access controls and auditing " Paul Moore
2021-09-15 16:49 ` [PATCH v4 1/8] audit: prepare audit_context for use in calling contexts beyond syscalls Paul Moore
2021-09-15 16:49 ` [PATCH v4 2/8] audit,io_uring,io-wq: add some basic audit support to io_uring Paul Moore
2021-09-16 13:33   ` Richard Guy Briggs
2021-09-16 14:02     ` Paul Moore [this message]
2021-09-16 14:19       ` Richard Guy Briggs
2021-09-16 14:47         ` Paul Moore
2021-09-15 16:49 ` [PATCH v4 3/8] audit: add filtering for io_uring records Paul Moore
2021-09-15 21:48   ` Richard Guy Briggs
2021-09-15 16:49 ` [PATCH v4 4/8] fs: add anon_inode_getfile_secure() similar to anon_inode_getfd_secure() Paul Moore
2021-09-15 16:49 ` [PATCH v4 5/8] io_uring: convert io_uring to the secure anon inode interface Paul Moore
2021-09-15 16:49 ` [PATCH v4 6/8] lsm,io_uring: add LSM hooks to io_uring Paul Moore
2021-09-15 16:50 ` [PATCH v4 7/8] selinux: add support for the io_uring access controls Paul Moore
2021-09-15 16:50 ` [PATCH v4 8/8] Smack: Brutalist io_uring support Paul Moore
2021-09-20  2:44 ` [PATCH v4 0/8] Add LSM access controls and auditing to io_uring Paul Moore

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