From 99f07e91bef34db0fc8b1a224096e97f02dc0d56 Mon Sep 17 00:00:00 2001 From: Changli Gao Date: Tue, 21 Sep 2010 17:49:20 +0200 Subject: [PATCH] netfilter: save the hash of the tuple in the original direction for latter use Since we don't change the tuple in the original direction, we can save it in ct->tuplehash[IP_CT_DIR_REPLY].hnode.pprev for __nf_conntrack_confirm() use. __hash_conntrack() is split into two steps: hash_conntrack_raw() is used to get the raw hash, and __hash_bucket() is used to get the bucket id. In SYN-flood case, early_drop() doesn't need to recompute the hash again. Signed-off-by: Changli Gao Signed-off-by: Patrick McHardy --- net/netfilter/nf_conntrack_core.c | 112 +++++++++++++++++++++--------- 1 file changed, 78 insertions(+), 34 deletions(-) diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c index 4c0ad9b4dba0..1eacf8d9966a 100644 --- a/net/netfilter/nf_conntrack_core.c +++ b/net/netfilter/nf_conntrack_core.c @@ -67,29 +67,40 @@ EXPORT_PER_CPU_SYMBOL(nf_conntrack_untracked); static unsigned int nf_conntrack_hash_rnd __read_mostly; -static u_int32_t __hash_conntrack(const struct nf_conntrack_tuple *tuple, - u16 zone, unsigned int size, unsigned int rnd) +static u32 hash_conntrack_raw(const struct nf_conntrack_tuple *tuple, u16 zone) { unsigned int n; - u_int32_t h; /* The direction must be ignored, so we hash everything up to the * destination ports (which is a multiple of 4) and treat the last * three bytes manually. */ n = (sizeof(tuple->src) + sizeof(tuple->dst.u3)) / sizeof(u32); - h = jhash2((u32 *)tuple, n, - zone ^ rnd ^ (((__force __u16)tuple->dst.u.all << 16) | - tuple->dst.protonum)); + return jhash2((u32 *)tuple, n, zone ^ nf_conntrack_hash_rnd ^ + (((__force __u16)tuple->dst.u.all << 16) | + tuple->dst.protonum)); +} + +static u32 __hash_bucket(u32 hash, unsigned int size) +{ + return ((u64)hash * size) >> 32; +} + +static u32 hash_bucket(u32 hash, const struct net *net) +{ + return __hash_bucket(hash, net->ct.htable_size); +} - return ((u64)h * size) >> 32; +static u_int32_t __hash_conntrack(const struct nf_conntrack_tuple *tuple, + u16 zone, unsigned int size) +{ + return __hash_bucket(hash_conntrack_raw(tuple, zone), size); } static inline u_int32_t hash_conntrack(const struct net *net, u16 zone, const struct nf_conntrack_tuple *tuple) { - return __hash_conntrack(tuple, zone, net->ct.htable_size, - nf_conntrack_hash_rnd); + return __hash_conntrack(tuple, zone, net->ct.htable_size); } bool @@ -291,20 +302,20 @@ static void death_by_timeout(unsigned long ul_conntrack) * OR * - Caller must lock nf_conntrack_lock before calling this function */ -struct nf_conntrack_tuple_hash * -__nf_conntrack_find(struct net *net, u16 zone, - const struct nf_conntrack_tuple *tuple) +static struct nf_conntrack_tuple_hash * +____nf_conntrack_find(struct net *net, u16 zone, + const struct nf_conntrack_tuple *tuple, u32 hash) { struct nf_conntrack_tuple_hash *h; struct hlist_nulls_node *n; - unsigned int hash = hash_conntrack(net, zone, tuple); + unsigned int bucket = hash_bucket(hash, net); /* Disable BHs the entire time since we normally need to disable them * at least once for the stats anyway. */ local_bh_disable(); begin: - hlist_nulls_for_each_entry_rcu(h, n, &net->ct.hash[hash], hnnode) { + hlist_nulls_for_each_entry_rcu(h, n, &net->ct.hash[bucket], hnnode) { if (nf_ct_tuple_equal(tuple, &h->tuple) && nf_ct_zone(nf_ct_tuplehash_to_ctrack(h)) == zone) { NF_CT_STAT_INC(net, found); @@ -318,7 +329,7 @@ begin: * not the expected one, we must restart lookup. * We probably met an item that was moved to another chain. */ - if (get_nulls_value(n) != hash) { + if (get_nulls_value(n) != bucket) { NF_CT_STAT_INC(net, search_restart); goto begin; } @@ -326,19 +337,27 @@ begin: return NULL; } + +struct nf_conntrack_tuple_hash * +__nf_conntrack_find(struct net *net, u16 zone, + const struct nf_conntrack_tuple *tuple) +{ + return ____nf_conntrack_find(net, zone, tuple, + hash_conntrack_raw(tuple, zone)); +} EXPORT_SYMBOL_GPL(__nf_conntrack_find); /* Find a connection corresponding to a tuple. */ -struct nf_conntrack_tuple_hash * -nf_conntrack_find_get(struct net *net, u16 zone, - const struct nf_conntrack_tuple *tuple) +static struct nf_conntrack_tuple_hash * +__nf_conntrack_find_get(struct net *net, u16 zone, + const struct nf_conntrack_tuple *tuple, u32 hash) { struct nf_conntrack_tuple_hash *h; struct nf_conn *ct; rcu_read_lock(); begin: - h = __nf_conntrack_find(net, zone, tuple); + h = ____nf_conntrack_find(net, zone, tuple, hash); if (h) { ct = nf_ct_tuplehash_to_ctrack(h); if (unlikely(nf_ct_is_dying(ct) || @@ -356,6 +375,14 @@ begin: return h; } + +struct nf_conntrack_tuple_hash * +nf_conntrack_find_get(struct net *net, u16 zone, + const struct nf_conntrack_tuple *tuple) +{ + return __nf_conntrack_find_get(net, zone, tuple, + hash_conntrack_raw(tuple, zone)); +} EXPORT_SYMBOL_GPL(nf_conntrack_find_get); static void __nf_conntrack_hash_insert(struct nf_conn *ct, @@ -408,8 +435,11 @@ __nf_conntrack_confirm(struct sk_buff *skb) return NF_ACCEPT; zone = nf_ct_zone(ct); - hash = hash_conntrack(net, zone, &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple); - repl_hash = hash_conntrack(net, zone, &ct->tuplehash[IP_CT_DIR_REPLY].tuple); + /* reuse the hash saved before */ + hash = *(unsigned long *)&ct->tuplehash[IP_CT_DIR_REPLY].hnnode.pprev; + hash = hash_bucket(hash, net); + repl_hash = hash_conntrack(net, zone, + &ct->tuplehash[IP_CT_DIR_REPLY].tuple); /* We're not in hash table, and we refuse to set up related connections for unconfirmed conns. But packet copies and @@ -566,10 +596,11 @@ static noinline int early_drop(struct net *net, unsigned int hash) return dropped; } -struct nf_conn *nf_conntrack_alloc(struct net *net, u16 zone, - const struct nf_conntrack_tuple *orig, - const struct nf_conntrack_tuple *repl, - gfp_t gfp) +static struct nf_conn * +__nf_conntrack_alloc(struct net *net, u16 zone, + const struct nf_conntrack_tuple *orig, + const struct nf_conntrack_tuple *repl, + gfp_t gfp, u32 hash) { struct nf_conn *ct; @@ -585,6 +616,9 @@ struct nf_conn *nf_conntrack_alloc(struct net *net, u16 zone, get_random_bytes(&rand, sizeof(rand)); } while (!rand); cmpxchg(&nf_conntrack_hash_rnd, 0, rand); + + /* recompute the hash as nf_conntrack_hash_rnd is initialized */ + hash = hash_conntrack_raw(orig, zone); } /* We don't want any race condition at early drop stage */ @@ -592,8 +626,7 @@ struct nf_conn *nf_conntrack_alloc(struct net *net, u16 zone, if (nf_conntrack_max && unlikely(atomic_read(&net->ct.count) > nf_conntrack_max)) { - unsigned int hash = hash_conntrack(net, zone, orig); - if (!early_drop(net, hash)) { + if (!early_drop(net, hash_bucket(hash, net))) { atomic_dec(&net->ct.count); if (net_ratelimit()) printk(KERN_WARNING @@ -623,7 +656,8 @@ struct nf_conn *nf_conntrack_alloc(struct net *net, u16 zone, ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple = *orig; ct->tuplehash[IP_CT_DIR_ORIGINAL].hnnode.pprev = NULL; ct->tuplehash[IP_CT_DIR_REPLY].tuple = *repl; - ct->tuplehash[IP_CT_DIR_REPLY].hnnode.pprev = NULL; + /* save hash for reusing when confirming */ + *(unsigned long *)(&ct->tuplehash[IP_CT_DIR_REPLY].hnnode.pprev) = hash; /* Don't set timer yet: wait for confirmation */ setup_timer(&ct->timeout, death_by_timeout, (unsigned long)ct); write_pnet(&ct->ct_net, net); @@ -650,6 +684,14 @@ out_free: return ERR_PTR(-ENOMEM); #endif } + +struct nf_conn *nf_conntrack_alloc(struct net *net, u16 zone, + const struct nf_conntrack_tuple *orig, + const struct nf_conntrack_tuple *repl, + gfp_t gfp) +{ + return __nf_conntrack_alloc(net, zone, orig, repl, gfp, 0); +} EXPORT_SYMBOL_GPL(nf_conntrack_alloc); void nf_conntrack_free(struct nf_conn *ct) @@ -671,7 +713,7 @@ init_conntrack(struct net *net, struct nf_conn *tmpl, struct nf_conntrack_l3proto *l3proto, struct nf_conntrack_l4proto *l4proto, struct sk_buff *skb, - unsigned int dataoff) + unsigned int dataoff, u32 hash) { struct nf_conn *ct; struct nf_conn_help *help; @@ -685,7 +727,8 @@ init_conntrack(struct net *net, struct nf_conn *tmpl, return NULL; } - ct = nf_conntrack_alloc(net, zone, tuple, &repl_tuple, GFP_ATOMIC); + ct = __nf_conntrack_alloc(net, zone, tuple, &repl_tuple, GFP_ATOMIC, + hash); if (IS_ERR(ct)) { pr_debug("Can't allocate conntrack.\n"); return (struct nf_conntrack_tuple_hash *)ct; @@ -762,6 +805,7 @@ resolve_normal_ct(struct net *net, struct nf_conn *tmpl, struct nf_conntrack_tuple_hash *h; struct nf_conn *ct; u16 zone = tmpl ? nf_ct_zone(tmpl) : NF_CT_DEFAULT_ZONE; + u32 hash; if (!nf_ct_get_tuple(skb, skb_network_offset(skb), dataoff, l3num, protonum, &tuple, l3proto, @@ -771,10 +815,11 @@ resolve_normal_ct(struct net *net, struct nf_conn *tmpl, } /* look for tuple match */ - h = nf_conntrack_find_get(net, zone, &tuple); + hash = hash_conntrack_raw(&tuple, zone); + h = __nf_conntrack_find_get(net, zone, &tuple, hash); if (!h) { h = init_conntrack(net, tmpl, &tuple, l3proto, l4proto, - skb, dataoff); + skb, dataoff, hash); if (!h) return NULL; if (IS_ERR(h)) @@ -1314,8 +1359,7 @@ int nf_conntrack_set_hashsize(const char *val, struct kernel_param *kp) ct = nf_ct_tuplehash_to_ctrack(h); hlist_nulls_del_rcu(&h->hnnode); bucket = __hash_conntrack(&h->tuple, nf_ct_zone(ct), - hashsize, - nf_conntrack_hash_rnd); + hashsize); hlist_nulls_add_head_rcu(&h->hnnode, &hash[bucket]); } } -- 2.39.5