From: peter enderborg <peter.enderborg@sony.com>
To: Paul Moore <paul@paul-moore.com>
Cc: <linux-kernel@vger.kernel.org>,
SElinux list <selinux@vger.kernel.org>,
Steven Rostedt <rostedt@goodmis.org>,
Stephen Smalley <stephen.smalley.work@gmail.com>
Subject: Re: [RFC PATCH] selinux: Add denied trace with permssion filter
Date: Wed, 26 Aug 2020 17:06:11 +0200 [thread overview]
Message-ID: <59fa190f-37c0-79f3-ea46-8f821d820e1c@sony.com> (raw)
In-Reply-To: <CAHC9VhRGaE4FwE8iXo_zeAPdimE9ryMR+r4Jcq=ZpF_2aTJxzQ@mail.gmail.com>
On 8/26/20 4:45 PM, Paul Moore wrote:
> On Wed, Aug 26, 2020 at 10:34 AM peter enderborg
> <peter.enderborg@sony.com> wrote:
>> On 8/26/20 3:42 PM, Paul Moore wrote:
>>> On Mon, Aug 24, 2020 at 9:23 AM Peter Enderborg
>>> <peter.enderborg@sony.com> wrote:
>>>> This adds tracing of all denies. They are grouped with trace_seq for
>>>> each audit.
>>>>
>>>> A filter can be inserted with a write to it's filter section.
>>>>
>>>> echo "permission==\"entrypoint\"" > events/avc/selinux_denied/filter
>>>>
>>>> A output will be like:
>>>> runcon-1046 [002] .N.. 156.351738: selinux_denied:
>>>> trace_seq=2 result=-13
>>>> scontext=system_u:system_r:cupsd_t:s0-s0:c0.
>>>> c1023 tcontext=system_u:object_r:bin_t:s0
>>>> tclass=file permission=entrypoint
>>>>
>>>> Signed-off-by: Peter Enderborg <peter.enderborg@sony.com>
>>>> ---
>>>> include/trace/events/avc.h | 37 +++++++++++++++++++++++++++++++++++++
>>>> security/selinux/avc.c | 27 +++++++++++++++++++++++++--
>>>> 2 files changed, 62 insertions(+), 2 deletions(-)
>>> My most significant comment is that I don't think we want, or need,
>>> two trace points in the avc_audit_post_callback() function. Yes, I
>>> understand they are triggered slightly differently, but from my
>>> perspective there isn't enough difference between the two tracepoints
>>> to warrant including both. However, while the tracepoints may be
>> We tried that but that was problematic too.
> My apologies if I was on that thread, but can you remind me why it was
> a problem? Why can't we use a single tracepoint to capture the AVC
> information?
The problem is parsing the event.
https://lkml.org/lkml/2020/8/18/842
https://lkml.org/lkml/2020/8/21/526
and the "single list" version
https://lkml.org/lkml/2020/8/17/1346
With this patch we follow standard message format so no plugin should be needed.
>> Having partly overlapping traces is not unheard off. Check
>> compaction.c where we have a trace_mm_compaction_begin
>> and a more detailed trace_mm_compaction_migratepages.
>> (And a trace_mm_compaction_end)
> It may not be unique to SELinux, but that doesn't mean I like it :)
>
> One of my concerns with adding tracepoints is that the code would get
> littered with tracepoints; I accepted that it the AVC decision
> codepath was an obvious place for one, so we added a tracepoint.
> Having two tracepoints here is getting awfully close to my original
> fears.
>
>>> redundant in my mind, this new event does do the permission lookup in
>>> the kernel so that the contexts/class/permissions are all available as
>>> a string which is a good thing.
>>>
>>> Without going into the details, would the tracing folks be okay with
>>> doing something similar with the existing selinux_audited tracepoint?
>>> It's extra work in the kernel, but since it would only be triggered
>>> when the tracepoint was active it seems bearable to me.
>> I think the method for expanding lists is what we tried first on
>> suggestion from Steven Rostedt. Maybe we can do a trace_event
>> from a TP_prink but that would be recursive.
> Wait, why would you be adding a trace event to a trace event, or am I
> misunderstanding you?
>
> All I was talking about was adding the permission resolution code to
> the already existing SELinux AVC tracepoint.
>
next prev parent reply other threads:[~2020-08-26 15:06 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-17 17:07 [PATCH v3 0/3] selinux: add detailed tracepoint on audited events Thiébaud Weksteen
2020-08-17 17:07 ` [PATCH v3 1/3] selinux: add " Thiébaud Weksteen
2020-08-18 14:31 ` Stephen Smalley
2020-08-17 17:07 ` [PATCH v3 2/3] selinux: add basic filtering for audit trace events Thiébaud Weksteen
2020-08-18 14:36 ` Stephen Smalley
2020-08-17 17:07 ` [PATCH v3 3/3] selinux: add permission names to trace event Thiébaud Weksteen
2020-08-17 20:13 ` Stephen Smalley
2020-08-17 20:29 ` Steven Rostedt
2020-08-18 16:09 ` Steven Rostedt
2020-08-19 13:11 ` Stephen Smalley
2020-08-21 2:31 ` Steven Rostedt
2020-08-21 12:29 ` Stephen Smalley
2020-08-21 13:19 ` Paul Moore
2020-08-21 13:39 ` peter enderborg
[not found] ` <CA+zpnLfNjDwxgoG2p3W8YfXxYVQDum4Eh_MJQvKP4rGLqsqACA@mail.gmail.com>
2020-08-21 13:46 ` Paul Moore
2020-08-17 20:16 ` Stephen Smalley
2020-08-18 8:11 ` peter enderborg
2020-08-18 12:13 ` Stephen Smalley
2020-08-21 2:22 ` Paul Moore
2020-08-21 5:53 ` peter enderborg
2020-08-21 12:14 ` Stephen Smalley
2020-08-21 13:10 ` Paul Moore
[not found] ` <20200824132252.31261-1-peter.enderborg@sony.com>
2020-08-24 13:22 ` [RFC PATCH] selinux: Add denied trace with permssion filter Peter Enderborg
2020-08-26 13:42 ` Paul Moore
2020-08-26 14:34 ` peter enderborg
2020-08-26 14:45 ` Paul Moore
2020-08-26 15:06 ` peter enderborg [this message]
2020-08-27 13:30 ` Paul Moore
2020-08-27 14:04 ` peter enderborg
2020-08-31 14:16 ` Paul Moore
2020-08-31 14:19 ` Robert Judy
2020-08-31 14:24 ` Paul Moore
2020-08-31 15:34 ` peter enderborg
2020-09-01 15:31 ` Paul Moore
2020-09-01 17:18 ` peter enderborg
2020-09-18 1:47 ` Steven Rostedt
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