[PATCH 1/1] audit: add missing fields to AUDIT_CONFIG_CHANGE event
Steve Grubb
sgrubb at redhat.com
Thu Oct 12 22:13:28 UTC 2017
On Thursday, October 12, 2017 5:04:41 PM EDT Paul Moore wrote:
> On Thu, Oct 12, 2017 at 3:57 PM, Steve Grubb <sgrubb at redhat.com> wrote:
> > There are very important fields necessary to understand who is adding
> > audit rules and a little more context about the environment in which
> > its happening. This adds pid, uid, tty, subj, comm, and exe
> > information to the event. These are required fields.
> >
> > Signed-off-by: sgrubb <sgrubb at redhat.com>
> > ---
> >
> > kernel/audit_watch.c | 23 +++++++++++++++++++----
> > kernel/auditfilter.c | 18 +++++++++++++++---
> > 2 files changed, 34 insertions(+), 7 deletions(-)
> >
> > diff --git a/kernel/audit_watch.c b/kernel/audit_watch.c
> > index 9eb8b3511636..63abc2ba1372 100644
> > --- a/kernel/audit_watch.c
> > +++ b/kernel/audit_watch.c
> > @@ -239,14 +239,29 @@ static struct audit_watch *audit_dupe_watch(struct
> > audit_watch *old)>
> > static void audit_watch_log_rule_change(struct audit_krule *r, struct
> > audit_watch *w, char *op) {
> >
> > if (audit_enabled) {
> >
> > + struct tty_struct *tty;
> > + const struct cred *cred;
> >
> > struct audit_buffer *ab;
> >
> > + char comm[sizeof(current->comm)];
> > +
> >
> > ab = audit_log_start(NULL, GFP_NOFS, AUDIT_CONFIG_CHANGE);
> > if (unlikely(!ab))
> >
> > return;
> >
> > - audit_log_format(ab, "auid=%u ses=%u op=%s",
> > - from_kuid(&init_user_ns,
> > audit_get_loginuid(current)), -
> > audit_get_sessionid(current), op); - audit_log_format(ab, "
> > path=");
> > +
> > + tty = audit_get_tty(current);
> > + cred = current_cred();
> > + audit_log_format(ab, "pid=%d uid=%u auid=%u tty=%s
> > ses=%u",
> > + task_tgid_nr(current),
> > + from_kuid(&init_user_ns, cred->uid),
> > + from_kuid(&init_user_ns,
> > + audit_get_loginuid(current)),
> > + tty ? tty_name(tty) : "(none)",
> > + audit_get_sessionid(current));
>
> Another reminder that in general I'm not going to accept patches that
> shuffle the fields or insert fields in the middle of a record; if you
> want to add new fields to a record, add them at the end. I see no
> reason to break with the rule for this patch.
This has never been a rule. There are times I've suggested adding things at
the end because I looked at the parsers and saw that was the best solution.
But that is an informed decision based on looking at the code. Besides, there
are 9 places where AUDIT_CONFIG_CHANGE is logged and we'll have to parse it 9
different ways if we simply add things at the end. That said, I did some
testing. Here's a sample event:
type=CONFIG_CHANGE msg=audit(1507836246.134:98): pid=576 uid=0 auid=4294967295
tty=(none) ses=4294967295 subj=system_u:system_r:unconfined_service_t:s0
comm="auditctl" exe="/usr/sbin/auditctl" op=add_rule key="modules" list=4
res=1
and a current event:
type=CONFIG_CHANGE msg=audit(1507827262.547:6): audit_enabled=1 old=1
auid=4294967295 ses=4294967295 subj=system_u:system_r:unconfined_service_t:s0
op=add_rule key="sched" list=4 res=1
So, the old event has auid, session, and subj. Testing ausearch with those
fields on the new event yields this:
[root at f26-audit ~]# ausearch --start boot -m config_change --loginuid
4294967295 >/dev/null
[root at f26-audit ~]# echo $?
0
[root at f26-audit ~]# ausearch --start boot -m config_change --session
4294967295 >/dev/null
[root at f26-audit ~]# echo $?
0
[root at f26-audit ~]# ausearch --start boot -m config_change --subject service_t
>/dev/null
[root at f26-audit ~]# echo $?
0
So, ausearch still finds all the fields its supposed to. Does it find anything
it doesn't know about?
[root at f26-audit ~]# ausearch --start boot -m config_change -ui 0 >/dev/null
<no matches>
So, a current or older ausearch is not harmed by any of these changes. It
maintains the exact same behavior. The only time we have a problem is when
there are changes introduced that are not coordinated or tested. This has been
tested. This patch closes the last big hole that the auparse_normalizer sees
on boot.
-Steve
> > + audit_log_task_context(ab);
> > + audit_log_format(ab, " comm=");
> > + audit_log_untrustedstring(ab, get_task_comm(comm,
> > current)); + audit_log_d_path_exe(ab, current->mm);
> > + audit_log_format(ab, "op=%s path=", op);
> >
> > audit_log_untrustedstring(ab, w->path);
> > audit_log_key(ab, r->filterkey);
> > audit_log_format(ab, " list=%d res=1", r->listnr);
> >
> > diff --git a/kernel/auditfilter.c b/kernel/auditfilter.c
> > index 0b0aa5854dac..5e2a953da29a 100644
> > --- a/kernel/auditfilter.c
> > +++ b/kernel/auditfilter.c
> > @@ -1065,17 +1065,29 @@ static void audit_list_rules(int seq, struct
> > sk_buff_head *q)>
> > static void audit_log_rule_change(char *action, struct audit_krule *rule,
> > int res) {
> >
> > struct audit_buffer *ab;
> >
> > - uid_t loginuid = from_kuid(&init_user_ns,
> > audit_get_loginuid(current)); - unsigned int sessionid =
> > audit_get_sessionid(current);
> > + struct tty_struct *tty;
> > + const struct cred *cred;
> > + char comm[sizeof(current->comm)];
> >
> > if (!audit_enabled)
> >
> > return;
> >
> > + tty = audit_get_tty(current);
> > + cred = current_cred();
> > +
> >
> > ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE);
> > if (!ab)
> >
> > return;
> >
> > - audit_log_format(ab, "auid=%u ses=%u" ,loginuid, sessionid);
> > + audit_log_format(ab, "pid=%d uid=%u auid=%u tty=%s ses=%u",
> > + task_tgid_nr(current),
> > + from_kuid(&init_user_ns, cred->uid),
> > + from_kuid(&init_user_ns,
> > audit_get_loginuid(current)), + tty ? tty_name(tty)
> > : "(none)",
> > + audit_get_sessionid(current));
> >
> > audit_log_task_context(ab);
> >
> > + audit_log_format(ab, " comm=");
> > + audit_log_untrustedstring(ab, get_task_comm(comm, current));
> > + audit_log_d_path_exe(ab, current->mm);
> >
> > audit_log_format(ab, " op=%s", action);
> > audit_log_key(ab, rule->filterkey);
> > audit_log_format(ab, " list=%d res=%d", rule->listnr, res);
> >
> > --
> > 2.13.6
> >
> >
> > --
> > Linux-audit mailing list
> > Linux-audit at redhat.com
> > https://www.redhat.com/mailman/listinfo/linux-audit
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