diff options
| -rw-r--r-- | net/netfilter/xt_hashlimit.c | 25 |
1 files changed, 21 insertions, 4 deletions
diff --git a/net/netfilter/xt_hashlimit.c b/net/netfilter/xt_hashlimit.c index 26a668a84aa2..cc430f926a85 100644 --- a/net/netfilter/xt_hashlimit.c +++ b/net/netfilter/xt_hashlimit.c @@ -157,11 +157,22 @@ dsthash_find(const struct xt_hashlimit_htable *ht, /* allocate dsthash_ent, initialize dst, put in htable and lock it */ static struct dsthash_ent * dsthash_alloc_init(struct xt_hashlimit_htable *ht, - const struct dsthash_dst *dst) + const struct dsthash_dst *dst, bool *race) { struct dsthash_ent *ent; spin_lock(&ht->lock); + + /* Two or more packets may race to create the same entry in the + * hashtable, double check if this packet lost race. + */ + ent = dsthash_find(ht, dst); + if (ent != NULL) { + spin_unlock(&ht->lock); + *race = true; + return ent; + } + /* initialize hash with random val at the time we allocate * the first hashtable entry */ if (unlikely(!ht->rnd_initialized)) { @@ -585,6 +596,7 @@ hashlimit_mt(const struct sk_buff *skb, struct xt_action_param *par) unsigned long now = jiffies; struct dsthash_ent *dh; struct dsthash_dst dst; + bool race = false; u32 cost; if (hashlimit_init_dst(hinfo, &dst, skb, par->thoff) < 0) @@ -593,13 +605,18 @@ hashlimit_mt(const struct sk_buff *skb, struct xt_action_param *par) rcu_read_lock_bh(); dh = dsthash_find(hinfo, &dst); if (dh == NULL) { - dh = dsthash_alloc_init(hinfo, &dst); + dh = dsthash_alloc_init(hinfo, &dst, &race); if (dh == NULL) { rcu_read_unlock_bh(); goto hotdrop; + } else if (race) { + /* Already got an entry, update expiration timeout */ + dh->expires = now + msecs_to_jiffies(hinfo->cfg.expire); + rateinfo_recalc(dh, now, hinfo->cfg.mode); + } else { + dh->expires = jiffies + msecs_to_jiffies(hinfo->cfg.expire); + rateinfo_init(dh, hinfo); } - dh->expires = jiffies + msecs_to_jiffies(hinfo->cfg.expire); - rateinfo_init(dh, hinfo); } else { /* update expiration timeout */ dh->expires = now + msecs_to_jiffies(hinfo->cfg.expire); |