Re: [PATCH ghak25 v4 3/3] audit: add subj creds to NETFILTER_CFG record to cover async unregister

On Wed, Apr 22, 2020 at 5:40 PM Richard Guy Briggs <rgb(a)redhat.com&gt; wrote: > Some table unregister actions seem to be initiated by the kernel to > garbage collect unused tables that are not initiated by any userspace > actions. It was found to be necessary to add the subject credentials to > cover this case to reveal the source of these actions. A sample record: > > type=NETFILTER_CFG msg=audit(2020-03-11 21:25:21.491:269) : table=nat family=bridge entries=0 op=unregister pid=153 uid=root auid=unset tty=(none) ses=unset subj=system_u:system_r:kernel_t:s0 comm=kworker/u4:2 exe=(null) [I'm going to comment up here instead of in the code because it is a bit easier for everyone to see what the actual impact might be on the records.] Steve wants subject info in this case, okay, but let's try to trim out some of the fields which simply don't make sense in this record; I'm thinking of fields that are unset/empty in the kernel case and are duplicates of other records in the userspace/syscall case. I think that means we can drop "tty", "ses", "comm", and "exe" ... yes? While "auid" is a potential target for removal based on the dup-or-unset criteria, I think it falls under Steve's request for subject info here, even if it is garbage in this case.

> Signed-off-by: Richard Guy Briggs <rgb(a)redhat.com&gt; > --- > kernel/auditsc.c | 18 ++++++++++++++++++ > 1 file changed, 18 insertions(+) > > diff --git a/kernel/auditsc.c b/kernel/auditsc.c > index d281c18d1771..d7a45b181be0 100644 > --- a/kernel/auditsc.c > +++ b/kernel/auditsc.c > @@ -2557,12 +2557,30 @@ void __audit_log_nfcfg(const char *name, u8 af, unsigned int nentries, > enum audit_nfcfgop op) > { > struct audit_buffer *ab; > + const struct cred *cred; > + struct tty_struct *tty; > + char comm[sizeof(current->comm)]; > > ab = audit_log_start(audit_context(), GFP_KERNEL, AUDIT_NETFILTER_CFG); > if (!ab) > return; > audit_log_format(ab, "table=%s family=%u entries=%u op=%s", > name, af, nentries, audit_nfcfgs[op].s); > + > + cred = current_cred(); > + tty = audit_get_tty(); > + audit_log_format(ab, " pid=%u uid=%u auid=%u tty=%s ses=%u", > + task_pid_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_put_tty(tty); > + audit_log_task_context(ab); /* subj= */ > + audit_log_format(ab, " comm="); > + audit_log_untrustedstring(ab, get_task_comm(comm, current)); > + audit_log_d_path_exe(ab, current->mm); /* exe= */ > + > audit_log_end(ab); > } > EXPORT_SYMBOL_GPL(__audit_log_nfcfg); paul moore