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/integrity > > > _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. > Stefan > > > -Steve > > > > > https://elixir.bootlin.com/linux/latest/source/kernel/auditsc.c#L2433 > > > > > > > that. The reason why you can do that is those additional fields are not > > > > required to be searchable by common criteria. > > > > > > > > -Steve - RGB -- Richard Guy Briggs <rgb@xxxxxxxxxx> 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
