[NETFILTER]: {ip,ip6,arp}_tables: fix exponential worst-case search for loops
If we come to node we'd already marked as seen and it's not a part of path
(i.e. we don't have a loop right there), we already know that it isn't a
part of any loop, so we don't need to revisit it.
That speeds the things up if some chain is refered to from several places
and kills O(exp(table size)) worst-case behaviour (without sleeping,
at that, so if you manage to self-LART that way, you are SOL for a long
time)...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/netfilter/ip_tables.c b/net/ipv4/netfilter/ip_tables.c
index 83ebbeb..09696f1 100644
--- a/net/ipv4/netfilter/ip_tables.c
+++ b/net/ipv4/netfilter/ip_tables.c
@@ -384,6 +384,7 @@
for (;;) {
struct ipt_standard_target *t
= (void *)ipt_get_target(e);
+ int visited = e->comefrom & (1 << hook);
if (e->comefrom & (1 << NF_IP_NUMHOOKS)) {
printk("iptables: loop hook %u pos %u %08X.\n",
@@ -394,11 +395,11 @@
|= ((1 << hook) | (1 << NF_IP_NUMHOOKS));
/* Unconditional return/END. */
- if (e->target_offset == sizeof(struct ipt_entry)
+ if ((e->target_offset == sizeof(struct ipt_entry)
&& (strcmp(t->target.u.user.name,
IPT_STANDARD_TARGET) == 0)
&& t->verdict < 0
- && unconditional(&e->ip)) {
+ && unconditional(&e->ip)) || visited) {
unsigned int oldpos, size;
if (t->verdict < -NF_MAX_VERDICT - 1) {