[PATCH ghak25 v6] audit: add subj creds to NETFILTER_CFG record to cover async unregister

[Richard Guy Briggs]

On 2020-05-20 12:51, Richard Guy Briggs 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:
> 
> The uid, auid, tty, ses and exe fields have not been included since they
> are in the SYSCALL record and contain nothing useful in the non-user
> context.
> 
>   type=NETFILTER_CFG msg=audit(2020-03-11 21:25:21.491:269) : table=nat family=bridge entries=0 op=unregister pid=153 subj=system_u:system_r:kernel_t:s0 comm=kworker/u4:2
> 
> Signed-off-by: Richard Guy Briggs <rgb at redhat.com>

Self-NACK.  I forgot to remove cred and tty declarations.

> ---
> Changelog:
> v6
> - remove uid, auid fields as duplicates or unset
> 
> v5
> - rebase on upstreamed ghak28 on audit/next v5.7-rc1
> - remove tty, ses and exe fields as duplicates or unset
> - drop upstreamed patches 1&2 from set
> 
> v4
> - rebase on audit/next v5.7-rc1
> - fix checkpatch.pl errors/warnings in 1/3 and 2/3
> 
> v3
> - rebase on v5.6-rc1 audit/next
> - change audit_nf_cfg to audit_log_nfcfg
> - squash 2,3,4,5 to 1 and update patch descriptions
> - add subject credentials to cover garbage collecting kernel threads
> 
> v2
> - Rebase (audit/next 5.5-rc1) to get audit_context access and ebt_register_table ret code
> - Split x_tables and ebtables updates
> - Check audit_dummy_context
> - Store struct audit_nfcfg params in audit_context, abstract to audit_nf_cfg() call
> - Restore back to "table, family, entries" from "family, table, entries"
> - Log unregistration of tables
> - Add "op=" at the end of the AUDIT_NETFILTER_CFG record
> - Defer nsid patch (ghak79) to once nsid patchset upstreamed (ghak32)
> - Add ghak refs
> - Ditch NETFILTER_CFGSOLO record
> 
>  kernel/auditsc.c | 9 +++++++++
>  1 file changed, 9 insertions(+)
> 
> diff --git a/kernel/auditsc.c b/kernel/auditsc.c
> index cfe3486e5f31..e646055adb0b 100644
> --- a/kernel/auditsc.c
> +++ b/kernel/auditsc.c
> @@ -2557,12 +2557,21 @@ 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();
> +	audit_log_format(ab, " pid=%u", task_pid_nr(current));
> +	audit_log_task_context(ab); /* subj= */
> +	audit_log_format(ab, " comm=");
> +	audit_log_untrustedstring(ab, get_task_comm(comm, current));
>  	audit_log_end(ab);
>  }
>  EXPORT_SYMBOL_GPL(__audit_log_nfcfg);
> -- 
> 1.8.3.1
> 
> --
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- RGB

--
Richard Guy Briggs <rgb at redhat.com>
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