Re: [PATCH 5/6] NetLabel: rework the Netlink attribute handling (part 2)

Thomas Graf wrote:

* Paul Moore [off-list ref] 2006-09-25 10:13

quoted

quoted

quoted

-	ret_val = netlbl_netlink_snd(ans_skb, info->snd_pid);
+	switch (doi_def->type) {
+	case CIPSO_V4_MAP_STD:
+		nla_a = nla_nest_start(ans_skb, NLBL_CIPSOV4_A_MLSLVLLST);
+		if (nla_a == NULL) {
+			ret_val = -ENOMEM;
+			goto list_failure_lock;
+		}
+		for (iter = 0;
+		     iter < doi_def->map.std->lvl.local_size;
+		     iter++) {
+			if (doi_def->map.std->lvl.local[iter] ==
+			    CIPSO_V4_INV_LVL)
+				continue;

Can you estimate the number of entries being dumped here and in the cat
list below?

It's too hard to come up with a reasonable estimate without going
through the entire list before hand, which in previous messages (might
of been off-list) you pointed out as a bad thing.  If you would prefer I
can go back to doing it that way?

 
Sorry, I didn't make myself clear. I didn't mean to estimate the
size of the message. The way you're doing it right now is perfectly
fine. I'm interested in a estimate on how many items are being dumped
in practice. Less than 1K or a couple of K?

High order allocations are likely to fail if under pressure while
using dumpit() allows to reuse memory ressources.

It's hard to get a good idea of the likely usage scenario as I'm not
sure how users will want to configure NetLabel.  However, there is a
possibility of this growing larger than NLMSG_GOODSIZE, which makes
things a bit more difficult.  From what I can see dumpit() requires the
message be within NLMSG_GOODSIZE while a doit() response can be of
arbitrary length; this is why I chose a doit() response.  Even if the
system is under memory pressure I think a failure here is okay as this
is not what I would consider a critical message.

-- 
paul moore
linux security @ hp