Re: [PATCH ghak90 V9 05/13] audit: log container info of syscalls

On 2020-08-21 15:15, Paul Moore wrote: > On Wed, Jul 29, 2020 at 3:41 PM Richard Guy Briggs <rgb(a)redhat.com&gt; wrote: > > On 2020-07-05 11:10, Paul Moore wrote: > > > On Sat, Jun 27, 2020 at 9:22 AM Richard Guy Briggs <rgb(a)redhat.com&gt; wrote: > > ... > > > > > diff --git a/kernel/auditsc.c b/kernel/auditsc.c > > > > index f03d3eb0752c..9e79645e5c0e 100644 > > > > --- a/kernel/auditsc.c > > > > +++ b/kernel/auditsc.c > > > > @@ -1458,6 +1466,7 @@ static void audit_log_exit(void) > > > > struct audit_buffer *ab; > > > > struct audit_aux_data *aux; > > > > struct audit_names *n; > > > > + struct audit_contobj *cont; > > > > > > > > context->personality = current->personality; > > > > > > > > @@ -1541,7 +1550,7 @@ static void audit_log_exit(void) > > > > for (aux = context->aux_pids; aux; aux = aux->next) { > > > > struct audit_aux_data_pids *axs = (void *)aux; > > > > > > > > - for (i = 0; i < axs->pid_count; i++) > > > > + for (i = 0; i < axs->pid_count; i++) { > > > > if (audit_log_pid_context(context, axs->target_pid[i], > > > > axs->target_auid[i], > > > > axs->target_uid[i], > > > > @@ -1549,14 +1558,20 @@ static void audit_log_exit(void) > > > > axs->target_sid[i], > > > > axs->target_comm[i])) > > > > call_panic = 1; > > > > + audit_log_container_id(context, axs->target_cid[i]); > > > > + } > > > > > > It might be nice to see an audit event example including the > > > ptrace/signal information. I'm concerned there may be some confusion > > > about associating the different audit container IDs with the correct > > > information in the event. > > > > This is the subject of ghat81, which is a test for ptrace and signal > > records. > > > > This was the reason I had advocated for an op= field since there is a > > possibility of multiple contid records per event. > > I think an "op=" field is the wrong way to link audit container ID to > a particular record. It may be convenient, but I fear that it would > be overloading the field too much. Ok, after looking at the field dictionary how about item, rel, ref or rec? Item perhaps could be added to the OBJ_PID records, but that might be overloading a field that is already used in PATH records. "rel" for relates-to, "ref" for reference to, "rec" for record... Perhaps pid= would be enough to tie this record to the OBJ_PID record or the SYSCALL record, but in the case of network events, the pid may refer to a kernel thread. > Like I said above, I think it would be good to see an audit event > example including the ptrace/signal information. This way we can talk > about it on-list and hash out the various solutions if it proves to be > a problem. See the list posting from 2020-09-29 "auditing signals" pointing to ghat81 test case about testing ptrace and signals from 18 months ago. I think I have a way to generate a signal to multiple targets in one syscall... The added challenge is to also give those targets different audit container identifiers.

> > > > @@ -1575,6 +1590,14 @@ static void audit_log_exit(void) > > > > > > > > audit_log_proctitle(); > > > > > > > > + rcu_read_lock(); > > > > + cont = _audit_contobj_get(current); > > > > + rcu_read_unlock(); > > > > + audit_log_container_id(context, cont); > > > > + rcu_read_lock(); > > > > + _audit_contobj_put(cont); > > > > + rcu_read_unlock(); > > > > > > Do we need to grab an additional reference for the audit container > > > object here? We don't create any additional references here that > > > persist beyond the lifetime of this function, right? > > > > Why do we need another reference? There's one for each pointer pointing > > to it and so far we have just one from this task. Or are you thinking > > of the contid hash list, which is only added to when a task points to it > > and gets removed from that list when the last task stops pointing to it. > > Later that gets more complicated with network namespaces and nested > > container objects. For now we just needed it while generating the > > record, then it gets freed. > > I don't think we need to grab an additional reference here, that is > why I asked the question. The code above grabs a reference for the > audit container ID object associated with the current task and then > drops it before returning; if the current task, and it's associated > audit container ID object, disappears in the middle of the function > we've got much bigger worries :) I misunderstood your question previously thinking you wanted yet another reference taken in this case, when in fact it was the opposite and you thought the one taken here was superfluous. I don't *need* to grab the additional references here, but those are the accessor functions that exist, so I either create sub-accessor functions without the refcount manipulations that called from the primary accessor functions or open code a reduncancy... The locking has been updated to protect the _put by a spin-lock. Now that I look at it, the 4th to 7th lines could be bypassed by a cont == NULL check. It is somewhat hidden now since this sequence of 7 commands has been abstracted into another function that is called from a second location. > paul moore - RGB