Re: [RFC PATCH ghak59 V1 1/6] audit: give a clue what CONFIG_CHANGE op was involved

[Paul Moore]

On Thu, Jun 14, 2018 at 4:23 PM Richard Guy Briggs <rgb@xxxxxxxxxx> wrote:
> The failure to add an audit rule due to audit locked gives no clue
> what CONFIG_CHANGE operation failed.
> Similarly the set operation is the only other operation that doesn't
> give the "op=" field to indicate the action.
> All other CONFIG_CHANGE records include an op= field to give a clue as
> to what sort of configuration change is being executed.
>
> Since these are the only CONFIG_CHANGE records that that do not have an
> op= field, add them to bring them in line with the rest.

Normally this would be an immediate reject because this patch inserts
a field into an existing record, but the CONFIG_CHANGE record is so
variable (supposedly bad in its own right) that I don't this really
matters.

With that out of the way, I think this patch is fine, but I don't
think it is complete.  At the very least there is another
CONFIG_CHANGE record in audit_watch_log_rule_change() that doesn't
appear to include an "op" field.  If we want to make sure we have an
"op" field in every CONFIG_CHANGE record, let's actually add them all
:)

There appears to be another one in audit_mark_log_rule_change() ...
and one more in audit_receive_msg().  There may be more.

> Old records:
> type=CONFIG_CHANGE msg=audit(1519812997.781:374): pid=610 uid=0 auid=0 ses=1 subj=... audit_enabled=2 res=0
> type=CONFIG_CHANGE msg=audit(2018-06-14 14:55:04.507:47) : audit_enabled=1 old=1 auid=unset ses=unset subj=... res=yes
>
> New records:
> type=CONFIG_CHANGE msg=audit(1520958477.855:100): pid=610 uid=0 auid=0 ses=1 subj=... op=add_rule audit_enabled=2 res=0
>
> type=CONFIG_CHANGE msg=audit(2018-06-14 14:55:04.507:47) : op=set audit_enabled=1 old=1 auid=unset ses=unset subj=... res=yes
>
> See: https://github.com/linux-audit/audit-kernel/issues/59
> Signed-off-by: Richard Guy Briggs <rgb@xxxxxxxxxx>
> ---
>  kernel/audit.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/kernel/audit.c b/kernel/audit.c
> index e7478cb..ad54339 100644
> --- a/kernel/audit.c
> +++ b/kernel/audit.c
> @@ -403,7 +403,7 @@ static int audit_log_config_change(char *function_name, u32 new, u32 old,
>         ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE);
>         if (unlikely(!ab))
>                 return rc;
> -       audit_log_format(ab, "%s=%u old=%u", function_name, new, old);
> +       audit_log_format(ab, "op=set %s=%u old=%u", function_name, new, old);
>         audit_log_session_info(ab);
>         rc = audit_log_task_context(ab);
>         if (rc)
> @@ -1365,7 +1365,9 @@ static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
>                         return -EINVAL;
>                 if (audit_enabled == AUDIT_LOCKED) {
>                         audit_log_common_recv_msg(&ab, AUDIT_CONFIG_CHANGE);
> -                       audit_log_format(ab, " audit_enabled=%d res=0", audit_enabled);
> +                       audit_log_format(ab, " op=%s_rule audit_enabled=%d res=0",
> +                                        msg_type == AUDIT_ADD_RULE ? "add" : "remove",
> +                                        audit_enabled);
>                         audit_log_end(ab);
>                         return -EPERM;
>                 }
> --
> 1.8.3.1

-- 
paul moore
www.paul-moore.com