From: Richard Guy Briggs <rgb@redhat.com>
To: Paul Moore <paul@paul-moore.com>
Cc: nhorman@tuxdriver.com, linux-api@vger.kernel.org,
containers@lists.linux-foundation.org,
LKML <linux-kernel@vger.kernel.org>,
dhowells@redhat.com,
Linux-Audit Mailing List <linux-audit@redhat.com>,
netfilter-devel@vger.kernel.org, ebiederm@xmission.com,
simo@redhat.com, netdev@vger.kernel.org,
linux-fsdevel@vger.kernel.org, Eric Paris <eparis@parisplace.org>,
mpatel@redhat.com, Serge Hallyn <serge@hallyn.com>
Subject: Re: [PATCH ghak90 V8 07/16] audit: add contid support for signalling the audit daemon
Date: Thu, 23 Jan 2020 15:04:12 -0500 [thread overview]
Message-ID: <20200123200412.j2aucdp3cvk57prw@madcap2.tricolour.ca> (raw)
In-Reply-To: <CAHC9VhTusiQoudB8G5jjDFyM9WxBUAjZ6_X35ywJ063Jb75dQA@mail.gmail.com>
On 2020-01-23 12:09, Paul Moore wrote:
> On Thu, Jan 23, 2020 at 11:29 AM Richard Guy Briggs <rgb@redhat.com> wrote:
> > On 2020-01-22 16:28, Paul Moore wrote:
> > > On Tue, Dec 31, 2019 at 2:50 PM Richard Guy Briggs <rgb@redhat.com> wrote:
> > > >
> > > > Add audit container identifier support to the action of signalling the
> > > > audit daemon.
> > > >
> > > > Since this would need to add an element to the audit_sig_info struct,
> > > > a new record type AUDIT_SIGNAL_INFO2 was created with a new
> > > > audit_sig_info2 struct. Corresponding support is required in the
> > > > userspace code to reflect the new record request and reply type.
> > > > An older userspace won't break since it won't know to request this
> > > > record type.
> > > >
> > > > Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
> > > > ---
> > > > include/linux/audit.h | 7 +++++++
> > > > include/uapi/linux/audit.h | 1 +
> > > > kernel/audit.c | 35 +++++++++++++++++++++++++++++++++++
> > > > kernel/audit.h | 1 +
> > > > security/selinux/nlmsgtab.c | 1 +
> > > > 5 files changed, 45 insertions(+)
> > >
> > > ...
> > >
> > > > diff --git a/kernel/audit.c b/kernel/audit.c
> > > > index 0871c3e5d6df..51159c94041c 100644
> > > > --- a/kernel/audit.c
> > > > +++ b/kernel/audit.c
> > > > @@ -126,6 +126,14 @@ struct auditd_connection {
> > > > kuid_t audit_sig_uid = INVALID_UID;
> > > > pid_t audit_sig_pid = -1;
> > > > u32 audit_sig_sid = 0;
> > > > +/* Since the signal information is stored in the record buffer at the
> > > > + * time of the signal, but not retrieved until later, there is a chance
> > > > + * that the last process in the container could terminate before the
> > > > + * signal record is delivered. In this circumstance, there is a chance
> > > > + * the orchestrator could reuse the audit container identifier, causing
> > > > + * an overlap of audit records that refer to the same audit container
> > > > + * identifier, but a different container instance. */
> > > > +u64 audit_sig_cid = AUDIT_CID_UNSET;
> > >
> > > I believe we could prevent the case mentioned above by taking an
> > > additional reference to the audit container ID object when the signal
> > > information is collected, dropping it only after the signal
> > > information is collected by userspace or another process signals the
> > > audit daemon. Yes, it would block that audit container ID from being
> > > reused immediately, but since we are talking about one number out of
> > > 2^64 that seems like a reasonable tradeoff.
> >
> > I had thought that through and should have been more explicit about that
> > situation when I documented it. We could do that, but then the syscall
> > records would be connected with the call from auditd on shutdown to
> > request that signal information, rather than the exit of that last
> > process that was using that container. This strikes me as misleading.
> > Is that really what we want?
>
> ???
>
> I think one of us is not understanding the other; maybe it's me, maybe
> it's you, maybe it's both of us.
>
> Anyway, here is what I was trying to convey with my original comment
> ... When we record the audit container ID in audit_signal_info() we
> take an extra reference to the audit container ID object so that it
> will not disappear (and get reused) until after we respond with an
> AUDIT_SIGNAL_INFO2. In audit_receive_msg() when we do the
> AUDIT_SIGNAL_INFO2 processing we drop the extra reference we took in
> audit_signal_info(). Unless I'm missing some other change you made,
> this *shouldn't* affect the syscall records, all it does is preserve
> the audit container ID object in the kernel's ACID store so it doesn't
> get reused.
This is exactly what I had understood. I hadn't considered the extra
details below in detail due to my original syscall concern, but they
make sense.
The syscall I refer to is the one connected with the drop of the
audit container identifier by the last process that was in that
container in patch 5/16. The production of this record is contingent on
the last ref in a contobj being dropped. So if it is due to that ref
being maintained by audit_signal_info() until the AUDIT_SIGNAL_INFO2
record it fetched, then it will appear that the fetch action closed the
container rather than the last process in the container to exit.
Does this make sense?
> (We do need to do some extra housekeeping in audit_signal_info() to
> deal with the case where nobody asks for AUDIT_SIGNAL_INFO2 -
> basically if audit_sig_cid is not NULL we should drop a reference
> before assigning it a new object pointer, and of course we would need
> to set audit_sig_cid to NULL in audit_receive_msg() after sending it
> up to userspace and dropping the extra ref.)
>
> paul moore
- RGB
--
Richard Guy Briggs <rgb@redhat.com>
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
next prev parent reply other threads:[~2020-01-23 20:04 UTC|newest]
Thread overview: 102+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-31 19:48 [PATCH ghak90 V8 00/16] audit: implement container identifier Richard Guy Briggs
2019-12-31 19:48 ` [PATCH ghak90 V8 01/16] audit: collect audit task parameters Richard Guy Briggs
2019-12-31 19:48 ` [PATCH ghak90 V8 02/16] audit: add container id Richard Guy Briggs
2020-01-22 21:28 ` Paul Moore
2020-01-30 17:53 ` Richard Guy Briggs
2019-12-31 19:48 ` [PATCH ghak90 V8 03/16] audit: read container ID of a process Richard Guy Briggs
2019-12-31 19:48 ` [PATCH ghak90 V8 04/16] audit: convert to contid list to check for orch/engine ownership Richard Guy Briggs
2020-01-22 21:28 ` Paul Moore
2020-02-04 22:51 ` Richard Guy Briggs
2020-02-05 22:40 ` Paul Moore
2019-12-31 19:48 ` [PATCH ghak90 V8 05/16] audit: log drop of contid on exit of last task Richard Guy Briggs
2020-01-22 21:28 ` Paul Moore
2020-02-04 23:02 ` Richard Guy Briggs
2019-12-31 19:48 ` [PATCH ghak90 V8 06/16] audit: log container info of syscalls Richard Guy Briggs
2019-12-31 19:48 ` [PATCH ghak90 V8 07/16] audit: add contid support for signalling the audit daemon Richard Guy Briggs
2020-01-22 21:28 ` Paul Moore
2020-01-23 16:29 ` Richard Guy Briggs
2020-01-23 17:09 ` Paul Moore
2020-01-23 20:04 ` Richard Guy Briggs [this message]
2020-01-23 21:35 ` Paul Moore
2020-02-04 23:14 ` Richard Guy Briggs
2020-02-05 22:50 ` Paul Moore
2020-02-12 22:38 ` Steve Grubb
2020-02-13 0:09 ` Paul Moore
2020-02-13 21:44 ` Paul Moore
2020-03-12 19:30 ` Richard Guy Briggs
2020-03-13 16:29 ` Paul Moore
2020-03-13 18:59 ` Richard Guy Briggs
2020-03-18 20:56 ` Paul Moore
2020-03-18 21:26 ` Richard Guy Briggs
2020-03-18 21:42 ` Paul Moore
2020-03-18 21:55 ` Richard Guy Briggs
2020-03-18 22:06 ` Paul Moore
2020-03-19 22:02 ` Richard Guy Briggs
2020-03-24 0:16 ` Paul Moore
2020-03-24 21:01 ` Richard Guy Briggs
2020-03-29 3:11 ` Paul Moore
2020-03-30 13:47 ` Richard Guy Briggs
2020-03-30 14:26 ` Paul Moore
2020-03-30 16:21 ` Richard Guy Briggs
2020-03-30 17:34 ` Paul Moore
2020-03-30 17:49 ` Richard Guy Briggs
2020-03-30 19:55 ` Paul Moore
2020-04-16 20:33 ` Eric W. Biederman
2020-04-16 21:53 ` Paul Moore
2020-04-17 22:23 ` Eric W. Biederman
2020-04-22 17:24 ` Paul Moore
2020-06-08 18:03 ` Richard Guy Briggs
2020-06-17 21:33 ` Paul Moore
2020-06-19 15:22 ` Richard Guy Briggs
2020-03-12 20:27 ` Richard Guy Briggs
2020-03-13 16:42 ` Paul Moore
2020-03-13 16:45 ` Steve Grubb
2020-03-13 16:49 ` Paul Moore
2020-03-13 19:23 ` Richard Guy Briggs
2020-03-18 21:01 ` Paul Moore
2020-03-18 21:41 ` Richard Guy Briggs
2020-03-18 21:47 ` Paul Moore
2020-03-19 21:47 ` Richard Guy Briggs
2020-03-20 21:56 ` Paul Moore
2020-03-25 12:29 ` Richard Guy Briggs
2020-03-29 3:17 ` Paul Moore
2020-03-30 15:23 ` Richard Guy Briggs
2019-12-31 19:48 ` [PATCH ghak90 V8 08/16] audit: add support for non-syscall auxiliary records Richard Guy Briggs
2019-12-31 19:48 ` [PATCH ghak90 V8 09/16] audit: add containerid support for user records Richard Guy Briggs
2019-12-31 19:48 ` [PATCH ghak90 V8 10/16] audit: add containerid filtering Richard Guy Briggs
2019-12-31 19:48 ` [PATCH ghak90 V8 11/16] audit: add support for containerid to network namespaces Richard Guy Briggs
2020-01-22 21:28 ` Paul Moore
2020-02-04 23:42 ` Richard Guy Briggs
2020-02-05 22:51 ` Paul Moore
2019-12-31 19:48 ` [PATCH ghak90 V8 12/16] audit: contid check descendancy and nesting Richard Guy Briggs
2020-01-22 21:29 ` Paul Moore
2020-01-23 21:02 ` Richard Guy Briggs
2020-01-23 21:47 ` Paul Moore
2019-12-31 19:48 ` [PATCH ghak90 V8 13/16] audit: track container nesting Richard Guy Briggs
2020-01-22 21:29 ` Paul Moore
2020-01-30 19:27 ` Richard Guy Briggs
2020-02-05 23:05 ` Paul Moore
2020-02-05 23:50 ` Richard Guy Briggs
2020-02-13 21:49 ` Paul Moore
2020-03-12 20:51 ` Richard Guy Briggs
2020-03-13 16:47 ` Paul Moore
2020-03-14 22:42 ` Richard Guy Briggs
2020-03-17 18:28 ` Richard Guy Briggs
2020-03-18 21:08 ` Paul Moore
2020-01-31 14:50 ` Steve Grubb
2020-02-04 13:19 ` Richard Guy Briggs
2020-02-04 15:47 ` Steve Grubb
2020-02-04 15:52 ` Paul Moore
2020-02-04 18:12 ` Steve Grubb
2020-02-05 22:57 ` Paul Moore
2019-12-31 19:48 ` [PATCH ghak90 V8 14/16] audit: check contid depth and add limit config param Richard Guy Briggs
2020-01-22 21:29 ` Paul Moore
2019-12-31 19:48 ` [PATCH ghak90 V8 15/16] audit: check contid count per netns and add config param limit Richard Guy Briggs
2020-01-22 21:29 ` Paul Moore
2019-12-31 19:48 ` [PATCH ghak90 V8 16/16] audit: add capcontid to set contid outside init_user_ns Richard Guy Briggs
2020-01-22 21:29 ` Paul Moore
2020-02-05 0:39 ` Richard Guy Briggs
2020-02-05 22:56 ` Paul Moore
2020-02-06 12:51 ` Richard Guy Briggs
2020-02-13 21:58 ` Paul Moore
2020-03-12 21:58 ` Richard Guy Briggs
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