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authorAl Viro <viro@zeniv.linux.org.uk>2006-12-12 00:29:52 -0800
committerDavid S. Miller <davem@sunset.davemloft.net>2006-12-13 16:48:23 -0800
commite1b4b9f3986b80d5785d91dbd8d72cfaf9fd1117 (patch)
tree96732395f387104b7af0641a5127352dc0d6124d /net/ipv6
parenta96be24679198469df28976c809575423e70d843 (diff)
[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>
Diffstat (limited to 'net/ipv6')
-rw-r--r--net/ipv6/netfilter/ip6_tables.c5
1 files changed, 3 insertions, 2 deletions
diff --git a/net/ipv6/netfilter/ip6_tables.c b/net/ipv6/netfilter/ip6_tables.c
index 4eec4b3988b8..99502c5da4c4 100644
--- a/net/ipv6/netfilter/ip6_tables.c
+++ b/net/ipv6/netfilter/ip6_tables.c
@@ -413,6 +413,7 @@ mark_source_chains(struct xt_table_info *newinfo,
unsigned int pos = newinfo->hook_entry[hook];
struct ip6t_entry *e
= (struct ip6t_entry *)(entry0 + pos);
+ int visited = e->comefrom & (1 << hook);
if (!(valid_hooks & (1 << hook)))
continue;
@@ -433,11 +434,11 @@ mark_source_chains(struct xt_table_info *newinfo,
|= ((1 << hook) | (1 << NF_IP6_NUMHOOKS));
/* Unconditional return/END. */
- if (e->target_offset == sizeof(struct ip6t_entry)
+ if ((e->target_offset == sizeof(struct ip6t_entry)
&& (strcmp(t->target.u.user.name,
IP6T_STANDARD_TARGET) == 0)
&& t->verdict < 0
- && unconditional(&e->ipv6)) {
+ && unconditional(&e->ipv6)) || visited) {
unsigned int oldpos, size;
if (t->verdict < -NF_MAX_VERDICT - 1) {