Commit 0354b48f authored Dec 16, 2011 by Florian Westphal Committed by Pablo Neira Ayuso Dec 23, 2011

netfilter: xt_connbytes: handle negation correctly



"! --connbytes 23:42" should match if the packet/byte count is not in range.

As there is no explict "invert match" toggle in the match structure,
userspace swaps the from and to arguments
(i.e., as if "--connbytes 42:23" were given).

However, "what <= 23 && what >= 42" will always be false.

Change things so we use "||" in case "from" is larger than "to".

This change may look like it breaks backwards compatibility when "to" is 0.
However, older iptables binaries will refuse "connbytes 42:0",
and current releases treat it to mean "! --connbytes 0:42",
so we should be fine.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

parent 3f1e6d3f

net/netfilter/xt_connbytes.c

+3 −3

Original line number	Diff line number	Diff line
		@@ -87,10 +87,10 @@ connbytes_mt(const struct sk_buff skb, struct xt_action_param par)
		break;
		}

		if (sinfo->count.to)
		if (sinfo->count.to >= sinfo->count.from)
		return what <= sinfo->count.to && what >= sinfo->count.from;
		else
		return what >= sinfo->count.from;
		else /* inverted */
		return what < sinfo->count.to \|\| what > sinfo->count.from;
		}

		static int connbytes_mt_check(const struct xt_mtchk_param *par)