[PATCH] audit: add containerid support for IMA-audit

Steve Grubb sgrubb at redhat.com
Tue May 22 14:12:10 UTC 2018


On Tuesday, May 22, 2018 9:43:46 AM EDT Richard Guy Briggs wrote:
> On 2018-05-21 17:57, Stefan Berger wrote:
> > On 05/21/2018 02:30 PM, Steve Grubb wrote:
> > > Hello Stefan,
> > > 
> > > On Monday, May 21, 2018 1:53:04 PM EDT Stefan Berger wrote:
> > > > On 05/21/2018 12:58 PM, Steve Grubb wrote:
> > > > > On Thursday, May 17, 2018 10:18:13 AM EDT Stefan Berger wrote:
> > > > > > > audit_log_container_info() then releasing the local context. 
> > > > > > > This
> > > > > > > version of the record has additional concerns covered here:
> > > > > > > https://github.com/linux-audit/audit-kernel/issues/52
> > > > > > 
> > > > > > Following the discussion there and the concern with breaking user
> > > > > > space,
> > > > > > how can we split up the AUDIT_INTEGRITY_RULE that is used in
> > > > > > ima_audit_measurement() and ima_parse_rule(), without 'breaking
> > > > > > user
> > > > > > space'?
> > > > > > 
> > > > > > A message produced by ima_parse_rule() looks like this here:
> > > > > > 
> > > > > > type=INTEGRITY_RULE msg=audit(1526566213.870:305):
> > > > > > action="dont_measure"
> > > > > > fsmagic="0x9fa0" res=1
> > > > > 
> > > > > Why is action and fsmagic being logged as untrusted strings?
> > > > > Untrusted
> > > > > strings are used when an unprivileged user can affect the contents
> > > > > of the
> > > > > field such as creating a file with space or special characters in
> > > > > the
> > > > > name.
> > > > > 
> > > > > Also, subject and object information is missing. Who loaded this
> > > > > rule?
> > > > > 
> > > > > > in contrast to that an INTEGRITY_PCR record type:
> > > > > > 
> > > > > > type=INTEGRITY_PCR msg=audit(1526566235.193:334): pid=1615 uid=0
> > > > > > auid=0
> > > > > > ses=2 subj=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023
> > > > > > op="invalid_pcr" cause="open_writers" comm="scp"
> > > > > > name="/var/log/audit/audit.log" dev="dm-0" ino=1962625 res=1
> > > > > 
> > > > > Why is op & cause being logged as an untrusted string? This also
> > > > > has
> > > > > incomplete subject information.
> > > > 
> > > > It's calling audit_log_string() in both cases:
> > > > 
> > > > https://elixir.bootlin.com/linux/latest/source/security/integrity/int
> > > > egrity _audit.c#L48
> > > 
> > > I see. Looking things over, I see that it seems like it should do the
> > > right thing. But the original purpose for this function is here:
> > > 
> > > https://elixir.bootlin.com/linux/latest/source/kernel/audit.c#L1944
> > > 
> > > This is where it is logging an untrusted string and has to decide to
> > > encode it or just place it in quotes. If it has quotes, that means
> > > it's an untrusted string but has no control characters in it. I think
> > > you want to use audit_log_format() for any string that is trustworthy.
> > 
> > Replacing all occurrences (in IMA) of audit_log_string() with
> > audit_log_format().
> > 
> > > As an aside, I wonder why audit_log_string() is in the API when it is a
> > > helper to audit_log_untrustedstring() ?  Without understanding the
> > > rules of untrusted strings, it can't be used correctly without
> > > re-inventing audit_log_untrustedstring() by hand.
> > > 
> > > > > > Should some of the fields from INTEGRITY_PCR also appear in
> > > > > > INTEGRITY_RULE? If so, which ones?
> > > > > 
> > > > > pid, uid, auid, tty, session, subj, comm, exe, res.  <- these are
> > > > > required to be searchable
> > > > > 
> > > > > > We could probably refactor the current  integrity_audit_message()
> > > > > > and
> > > > > > have ima_parse_rule() call into it to get those fields as well. I
> > > > > > suppose adding new fields to it wouldn't be considered breaking
> > > > > > user
> > > > > > space?
> > > > > 
> > > > > The audit user space utilities pretty much expects those fields in
> > > > > that
> > > > > order for any IMA originating events. You can add things like op or
> > > > > cause before
> > > > 
> > > > We will call into audit_log_task, which will put the parameters into
> > > > correct order:
> > > > 
> > > > auid uid gid ses subj pid comm exe
> > > 
> > > I'm telling you what the correct order is.  :-)  A long time ago, the
> > > IMA
> > :
> > :-) Thanks. Was getting confused.
> > :
> > > system had audit events with the order I'm mentioning. For example,
> > > here's
> > > one from a log I collected back in 2013:
> > > 
> > > type=INTEGRITY_PCR msg=audit(1327409021.813:21): pid=1 uid=0
> > > auid=4294967295 ses=4294967295 subj=kernel op="add_template_measure"
> > > cause="hash_added" comm="init" name="01parse-kernel.sh" dev=rootfs
> > > ino=5413 res=0
> > > 
> > > it was missing "tty" and "exe", but the order is as I mentioned. The
> > > expectation is that INTEGRITY events maintain this established order
> > > across all events.
> > 
> > I am *appending* exe= and tty= now:
> > 
> > type=INTEGRITY_PCR msg=audit(1526939047.809:305): pid=1609 uid=0 auid=0
> > ses=2 subj=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023
> > op="invalid_pcr" cause="open_writers" comm="ssh"
> > name="/var/lib/sss/mc/passwd" dev="dm-0" ino=1962679 res=1
> > exe="/usr/bin/ssh" tty=tty2
> 
> This isn't necessary since they already covered in the already
> connected SYSCALL record which duplicates even more information than is
> already.

My logs don't show any syscall record being attached. Nor should it. This is 
a simple event that should stand on its own.

-Steve





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