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>
diff --git a/net/netfilter/xt_connbytes.c b/net/netfilter/xt_connbytes.c
index 5b13850..9ddf1c3 100644
--- a/net/netfilter/xt_connbytes.c
+++ b/net/netfilter/xt_connbytes.c
@@ -87,10 +87,10 @@
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)