Re: [PATCH 8/8] ima: Differentiate auditing policy rules from "audit" actions

Steve Grubb
2018-05-30T15:15:37Z

On Wednesday, May 30, 2018 9:54:00 AM EDT Stefan Berger wrote:
> On 05/29/2018 05:30 PM, Steve Grubb wrote:
> > Hello,
> >
> > On Thursday, May 24, 2018 4:11:05 PM EDT Stefan Berger wrote:
> >> The AUDIT_INTEGRITY_RULE is used for auditing IMA policy rules and
> >> the IMA "audit" policy action. This patch defines
> >> AUDIT_INTEGRITY_POLICY_RULE to reflect the IMA policy rules.
> >>
> >> With this change we now call integrity_audit_msg_common() to get
> >> common integrity auditing fields. This now produces the following
> >> record when parsing an IMA policy rule:
> >>
> >> type=UNKNOWN[1806] msg=audit(1527004216.690:311): action=dont_measure \
> >>
> >> fsmagic=0x9fa0 pid=1613 uid=0 auid=0 ses=2 \
> >> subj=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 \
> >> op=policy_update cause=parse_rule comm="echo" exe="/usr/bin/echo" \
> >> tty=tty2 res=1
> >
> > Since this is a new event, do you mind moving the tty field to be between
> > auid= and ses= ? That is the more natural place for it.
>
> 6/8 refactors the code so that the integrity audit records produced by
> IMA follow one format in terms of ordering of the fields, with fields
> like inode optional, though, and AUDIT_INTEGRITY_RULE in the end being
> the only one with a different format. Do we really want to change that
> order just for 1806?
>
> 5/8 now produces the following:
>
> type=INTEGRITY_PCR msg=audit(1527685075.941:502): pid=2431 \
> uid=0 auid=1000 ses=5 \
> subj=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 \
> op=invalid_pcr cause=open_writers comm="grep" \
> name="/var/log/audit/audit.log" dev="dm-0" ino=1962494 \
> exe="/usr/bin/grep" tty=pts0 res=1
>
> Comparing the two:
>
> 1806: action, fsmagic, pid, uid, auid, ses, subj, op, cause,
> comm, exe, tty, res
> INTEGRITY_PCR: pid, uid, auid, ses, subj, op, cause,
> comm, name, dev, ino, exe, tty, res

OK. I guess go with it as is. It passes testing.

-Steve

> > Also, it might be more natural for the op= and cause= fields to be before
> > the pid= portion. This doesn't matter as much to me because those are
> > not searchable fields and they are skipped right over. But moving the
> > tty field is the main comment from me.
>
> With the refactoring in 6/8 we at least have consistency among the
> INTEGRITY_* records, with the only exception being AUDIT_INTEGRITY_RULE
> that has its own format:
>
> https://elixir.bootlin.com/linux/latest/source/security/integrity/ima/ima_a
> pi.c#L324
>
> The other ones currently all format using integrity_audit_msg().
>
> > Thanks,
> > -Steve
> >
> >> Signed-off-by: Stefan Berger<stefanb@linux.vnet.ibm.com>
> >> ---
> >>
> >> include/uapi/linux/audit.h | 3 ++-
> >> security/integrity/ima/ima_policy.c | 5 +++--
> >> 2 files changed, 5 insertions(+), 3 deletions(-)
> >>
> >> diff --git a/include/uapi/linux/audit.h b/include/uapi/linux/audit.h
> >> index 4e61a9e05132..776e0abd35cf 100644
> >> --- a/include/uapi/linux/audit.h
> >> +++ b/include/uapi/linux/audit.h
> >> @@ -146,7 +146,8 @@
> >>
> >> #define AUDIT_INTEGRITY_STATUS 1802 /* Integrity enable status */
> >> #define AUDIT_INTEGRITY_HASH 1803 /* Integrity HASH type */
> >> #define AUDIT_INTEGRITY_PCR 1804 /* PCR invalidation msgs */
> >>
> >> -#define AUDIT_INTEGRITY_RULE 1805 /* policy rule */
> >> +#define AUDIT_INTEGRITY_RULE 1805 /* IMA "audit" action policy msgs
> >> */ +#define AUDIT_INTEGRITY_POLICY_RULE 1806 /* IMA policy rules */
> >>
> >> #define AUDIT_KERNEL 2000 /* Asynchronous audit record. NOT A
> >
> > REQUEST. */
> >
> >> diff --git a/security/integrity/ima/ima_policy.c
> >> b/security/integrity/ima/ima_policy.c index 3aed25a7178a..a8ae47a386b4
> >> 100644
> >> --- a/security/integrity/ima/ima_policy.c
> >> +++ b/security/integrity/ima/ima_policy.c
> >> @@ -634,7 +634,7 @@ static int ima_parse_rule(char *rule, struct
> >> ima_rule_entry *entry) int result = 0;
> >>
> >> ab = integrity_audit_log_start(NULL, GFP_KERNEL,
> >>
> >> - AUDIT_INTEGRITY_RULE);
> >> + AUDIT_INTEGRITY_POLICY_RULE);
> >>
> >> entry->uid = INVALID_UID;
> >> entry->fowner = INVALID_UID;
> >>
> >> @@ -926,7 +926,8 @@ static int ima_parse_rule(char *rule, struct
> >> ima_rule_entry *entry) temp_ima_appraise |= IMA_APPRAISE_FIRMWARE;
> >>
> >> else if (entry->func == POLICY_CHECK)
> >>
> >> temp_ima_appraise |= IMA_APPRAISE_POLICY;
> >>
> >> - audit_log_format(ab, "res=%d", !result);
> >> + integrity_audit_msg_common(ab, NULL, NULL,
> >> + "policy_update", "parse_rule", result);
> >>
> >> audit_log_end(ab);
> >> return result;
> >>
> >> }