Commit 3b24d854 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller

tcp/dccp: do not touch listener sk_refcnt under synflood

When a SYNFLOOD targets a non SO_REUSEPORT listener, multiple
cpus contend on sk->sk_refcnt and sk->sk_wmem_alloc changes.

By letting listeners use SOCK_RCU_FREE infrastructure,
we can relax TCP_LISTEN lookup rules and avoid touching sk_refcnt

Note that we still use SLAB_DESTROY_BY_RCU rules for other sockets,
only listeners are impacted by this change.

Peak performance under SYNFLOOD is increased by ~33% :

On my test machine, I could process 3.2 Mpps instead of 2.4 Mpps

Most consuming functions are now skb_set_owner_w() and sock_wfree()
contending on sk->sk_wmem_alloc when cooking SYNACK and freeing them.
Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 3a5d1c0e
......@@ -66,13 +66,15 @@ static inline struct sock *__inet6_lookup(struct net *net,
const __be16 sport,
const struct in6_addr *daddr,
const u16 hnum,
const int dif)
const int dif,
bool *refcounted)
{
struct sock *sk = __inet6_lookup_established(net, hashinfo, saddr,
sport, daddr, hnum, dif);
*refcounted = true;
if (sk)
return sk;
*refcounted = false;
return inet6_lookup_listener(net, hashinfo, skb, doff, saddr, sport,
daddr, hnum, dif);
}
......@@ -81,17 +83,19 @@ static inline struct sock *__inet6_lookup_skb(struct inet_hashinfo *hashinfo,
struct sk_buff *skb, int doff,
const __be16 sport,
const __be16 dport,
int iif)
int iif,
bool *refcounted)
{
struct sock *sk = skb_steal_sock(skb);
*refcounted = true;
if (sk)
return sk;
return __inet6_lookup(dev_net(skb_dst(skb)->dev), hashinfo, skb,
doff, &ipv6_hdr(skb)->saddr, sport,
&ipv6_hdr(skb)->daddr, ntohs(dport),
iif);
iif, refcounted);
}
struct sock *inet6_lookup(struct net *net, struct inet_hashinfo *hashinfo,
......
......@@ -100,14 +100,10 @@ struct inet_bind_hashbucket {
/*
* Sockets can be hashed in established or listening table
* We must use different 'nulls' end-of-chain value for listening
* hash table, or we might find a socket that was closed and
* reallocated/inserted into established hash table
*/
#define LISTENING_NULLS_BASE (1U << 29)
struct inet_listen_hashbucket {
spinlock_t lock;
struct hlist_nulls_head head;
struct hlist_head head;
};
/* This is for listening sockets, thus all sockets which possess wildcards. */
......@@ -304,14 +300,20 @@ static inline struct sock *__inet_lookup(struct net *net,
struct sk_buff *skb, int doff,
const __be32 saddr, const __be16 sport,
const __be32 daddr, const __be16 dport,
const int dif)
const int dif,
bool *refcounted)
{
u16 hnum = ntohs(dport);
struct sock *sk = __inet_lookup_established(net, hashinfo,
saddr, sport, daddr, hnum, dif);
struct sock *sk;
return sk ? : __inet_lookup_listener(net, hashinfo, skb, doff, saddr,
sport, daddr, hnum, dif);
sk = __inet_lookup_established(net, hashinfo, saddr, sport,
daddr, hnum, dif);
*refcounted = true;
if (sk)
return sk;
*refcounted = false;
return __inet_lookup_listener(net, hashinfo, skb, doff, saddr,
sport, daddr, hnum, dif);
}
static inline struct sock *inet_lookup(struct net *net,
......@@ -322,10 +324,13 @@ static inline struct sock *inet_lookup(struct net *net,
const int dif)
{
struct sock *sk;
bool refcounted;
sk = __inet_lookup(net, hashinfo, skb, doff, saddr, sport, daddr,
dport, dif);
dport, dif, &refcounted);
if (sk && !refcounted && !atomic_inc_not_zero(&sk->sk_refcnt))
sk = NULL;
return sk;
}
......@@ -333,17 +338,20 @@ static inline struct sock *__inet_lookup_skb(struct inet_hashinfo *hashinfo,
struct sk_buff *skb,
int doff,
const __be16 sport,
const __be16 dport)
const __be16 dport,
bool *refcounted)
{
struct sock *sk = skb_steal_sock(skb);
const struct iphdr *iph = ip_hdr(skb);
*refcounted = true;
if (sk)
return sk;
else
return __inet_lookup(dev_net(skb_dst(skb)->dev), hashinfo, skb,
doff, iph->saddr, sport,
iph->daddr, dport, inet_iif(skb));
return __inet_lookup(dev_net(skb_dst(skb)->dev), hashinfo, skb,
doff, iph->saddr, sport,
iph->daddr, dport, inet_iif(skb),
refcounted);
}
u32 sk_ehashfn(const struct sock *sk);
......
......@@ -764,6 +764,7 @@ static int dccp_v4_rcv(struct sk_buff *skb)
{
const struct dccp_hdr *dh;
const struct iphdr *iph;
bool refcounted;
struct sock *sk;
int min_cov;
......@@ -801,7 +802,7 @@ static int dccp_v4_rcv(struct sk_buff *skb)
lookup:
sk = __inet_lookup_skb(&dccp_hashinfo, skb, __dccp_hdr_len(dh),
dh->dccph_sport, dh->dccph_dport);
dh->dccph_sport, dh->dccph_dport, &refcounted);
if (!sk) {
dccp_pr_debug("failed to look up flow ID in table and "
"get corresponding socket\n");
......@@ -830,6 +831,7 @@ lookup:
goto lookup;
}
sock_hold(sk);
refcounted = true;
nsk = dccp_check_req(sk, skb, req);
if (!nsk) {
reqsk_put(req);
......@@ -886,7 +888,8 @@ discard_it:
return 0;
discard_and_relse:
sock_put(sk);
if (refcounted)
sock_put(sk);
goto discard_it;
}
......
......@@ -642,6 +642,7 @@ discard:
static int dccp_v6_rcv(struct sk_buff *skb)
{
const struct dccp_hdr *dh;
bool refcounted;
struct sock *sk;
int min_cov;
......@@ -670,7 +671,7 @@ static int dccp_v6_rcv(struct sk_buff *skb)
lookup:
sk = __inet6_lookup_skb(&dccp_hashinfo, skb, __dccp_hdr_len(dh),
dh->dccph_sport, dh->dccph_dport,
inet6_iif(skb));
inet6_iif(skb), &refcounted);
if (!sk) {
dccp_pr_debug("failed to look up flow ID in table and "
"get corresponding socket\n");
......@@ -699,6 +700,7 @@ lookup:
goto lookup;
}
sock_hold(sk);
refcounted = true;
nsk = dccp_check_req(sk, skb, req);
if (!nsk) {
reqsk_put(req);
......@@ -752,7 +754,8 @@ discard_it:
return 0;
discard_and_relse:
sock_put(sk);
if (refcounted)
sock_put(sk);
goto discard_it;
}
......
......@@ -775,13 +775,12 @@ void inet_diag_dump_icsk(struct inet_hashinfo *hashinfo, struct sk_buff *skb,
for (i = s_i; i < INET_LHTABLE_SIZE; i++) {
struct inet_listen_hashbucket *ilb;
struct hlist_nulls_node *node;
struct sock *sk;
num = 0;
ilb = &hashinfo->listening_hash[i];
spin_lock_bh(&ilb->lock);
sk_nulls_for_each(sk, node, &ilb->head) {
sk_for_each(sk, &ilb->head) {
struct inet_sock *inet = inet_sk(sk);
if (!net_eq(sock_net(sk), net))
......
......@@ -198,13 +198,13 @@ static inline int compute_score(struct sock *sk, struct net *net,
}
/*
* Don't inline this cruft. Here are some nice properties to exploit here. The
* BSD API does not allow a listening sock to specify the remote port nor the
* Here are some nice properties to exploit here. The BSD API
* does not allow a listening sock to specify the remote port nor the
* remote address for the connection. So always assume those are both
* wildcarded during the search since they can never be otherwise.
*/
/* called with rcu_read_lock() : No refcount taken on the socket */
struct sock *__inet_lookup_listener(struct net *net,
struct inet_hashinfo *hashinfo,
struct sk_buff *skb, int doff,
......@@ -212,37 +212,27 @@ struct sock *__inet_lookup_listener(struct net *net,
const __be32 daddr, const unsigned short hnum,
const int dif)
{
struct sock *sk, *result;
struct hlist_nulls_node *node;
unsigned int hash = inet_lhashfn(net, hnum);
struct inet_listen_hashbucket *ilb = &hashinfo->listening_hash[hash];
int score, hiscore, matches = 0, reuseport = 0;
bool select_ok = true;
int score, hiscore = 0, matches = 0, reuseport = 0;
struct sock *sk, *result = NULL;
u32 phash = 0;
begin:
result = NULL;
hiscore = 0;
sk_nulls_for_each_rcu(sk, node, &ilb->head) {
sk_for_each_rcu(sk, &ilb->head) {
score = compute_score(sk, net, hnum, daddr, dif);
if (score > hiscore) {
result = sk;
hiscore = score;
reuseport = sk->sk_reuseport;
if (reuseport) {
phash = inet_ehashfn(net, daddr, hnum,
saddr, sport);
if (select_ok) {
struct sock *sk2;
sk2 = reuseport_select_sock(sk, phash,
skb, doff);
if (sk2) {
result = sk2;
goto found;
}
}
result = reuseport_select_sock(sk, phash,
skb, doff);
if (result)
return result;
matches = 1;
}
result = sk;
hiscore = score;
} else if (score == hiscore && reuseport) {
matches++;
if (reciprocal_scale(phash, matches) == 0)
......@@ -250,24 +240,6 @@ begin:
phash = next_pseudo_random32(phash);
}
}
/*
* if the nulls value we got at the end of this lookup is
* not the expected one, we must restart lookup.
* We probably met an item that was moved to another chain.
*/
if (get_nulls_value(node) != hash + LISTENING_NULLS_BASE)
goto begin;
if (result) {
found:
if (unlikely(!atomic_inc_not_zero(&result->sk_refcnt)))
result = NULL;
else if (unlikely(compute_score(result, net, hnum, daddr,
dif) < hiscore)) {
sock_put(result);
select_ok = false;
goto begin;
}
}
return result;
}
EXPORT_SYMBOL_GPL(__inet_lookup_listener);
......@@ -508,7 +480,8 @@ int __inet_hash(struct sock *sk, struct sock *osk,
if (err)
goto unlock;
}
__sk_nulls_add_node_rcu(sk, &ilb->head);
hlist_add_head_rcu(&sk->sk_node, &ilb->head);
sock_set_flag(sk, SOCK_RCU_FREE);
sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
unlock:
spin_unlock(&ilb->lock);
......@@ -535,20 +508,25 @@ void inet_unhash(struct sock *sk)
{
struct inet_hashinfo *hashinfo = sk->sk_prot->h.hashinfo;
spinlock_t *lock;
bool listener = false;
int done;
if (sk_unhashed(sk))
return;
if (sk->sk_state == TCP_LISTEN)
if (sk->sk_state == TCP_LISTEN) {
lock = &hashinfo->listening_hash[inet_sk_listen_hashfn(sk)].lock;
else
listener = true;
} else {
lock = inet_ehash_lockp(hashinfo, sk->sk_hash);
}
spin_lock_bh(lock);
if (rcu_access_pointer(sk->sk_reuseport_cb))
reuseport_detach_sock(sk);
done = __sk_nulls_del_node_init_rcu(sk);
if (listener)
done = __sk_del_node_init(sk);
else
done = __sk_nulls_del_node_init_rcu(sk);
if (done)
sock_prot_inuse_add(sock_net(sk), sk->sk_prot, -1);
spin_unlock_bh(lock);
......@@ -684,9 +662,8 @@ void inet_hashinfo_init(struct inet_hashinfo *h)
for (i = 0; i < INET_LHTABLE_SIZE; i++) {
spin_lock_init(&h->listening_hash[i].lock);
INIT_HLIST_NULLS_HEAD(&h->listening_hash[i].head,
i + LISTENING_NULLS_BASE);
}
INIT_HLIST_HEAD(&h->listening_hash[i].head);
}
}
EXPORT_SYMBOL_GPL(inet_hashinfo_init);
......
......@@ -628,6 +628,7 @@ static void tcp_v4_send_reset(const struct sock *sk, struct sk_buff *skb)
net = sk ? sock_net(sk) : dev_net(skb_dst(skb)->dev);
#ifdef CONFIG_TCP_MD5SIG
rcu_read_lock();
hash_location = tcp_parse_md5sig_option(th);
if (sk && sk_fullsock(sk)) {
key = tcp_md5_do_lookup(sk, (union tcp_md5_addr *)
......@@ -646,16 +647,18 @@ static void tcp_v4_send_reset(const struct sock *sk, struct sk_buff *skb)
ntohs(th->source), inet_iif(skb));
/* don't send rst if it can't find key */
if (!sk1)
return;
rcu_read_lock();
goto out;
key = tcp_md5_do_lookup(sk1, (union tcp_md5_addr *)
&ip_hdr(skb)->saddr, AF_INET);
if (!key)
goto release_sk1;
goto out;
genhash = tcp_v4_md5_hash_skb(newhash, key, NULL, skb);
if (genhash || memcmp(hash_location, newhash, 16) != 0)
goto release_sk1;
goto out;
}
if (key) {
......@@ -698,11 +701,8 @@ static void tcp_v4_send_reset(const struct sock *sk, struct sk_buff *skb)
TCP_INC_STATS_BH(net, TCP_MIB_OUTRSTS);
#ifdef CONFIG_TCP_MD5SIG
release_sk1:
if (sk1) {
rcu_read_unlock();
sock_put(sk1);
}
out:
rcu_read_unlock();
#endif
}
......@@ -1538,11 +1538,12 @@ EXPORT_SYMBOL(tcp_prequeue);
int tcp_v4_rcv(struct sk_buff *skb)
{
struct net *net = dev_net(skb->dev);
const struct iphdr *iph;
const struct tcphdr *th;
bool refcounted;
struct sock *sk;
int ret;
struct net *net = dev_net(skb->dev);
if (skb->pkt_type != PACKET_HOST)
goto discard_it;
......@@ -1588,7 +1589,7 @@ int tcp_v4_rcv(struct sk_buff *skb)
lookup:
sk = __inet_lookup_skb(&tcp_hashinfo, skb, __tcp_hdrlen(th), th->source,
th->dest);
th->dest, &refcounted);
if (!sk)
goto no_tcp_socket;
......@@ -1609,7 +1610,11 @@ process:
inet_csk_reqsk_queue_drop_and_put(sk, req);
goto lookup;
}
/* We own a reference on the listener, increase it again
* as we might lose it too soon.
*/
sock_hold(sk);
refcounted = true;
nsk = tcp_check_req(sk, skb, req, false);
if (!nsk) {
reqsk_put(req);
......@@ -1665,7 +1670,8 @@ process:
bh_unlock_sock(sk);
put_and_return:
sock_put(sk);
if (refcounted)
sock_put(sk);
return ret;
......@@ -1688,7 +1694,8 @@ discard_it:
return 0;
discard_and_relse:
sock_put(sk);
if (refcounted)
sock_put(sk);
goto discard_it;
do_time_wait:
......@@ -1712,6 +1719,7 @@ do_time_wait:
if (sk2) {
inet_twsk_deschedule_put(inet_twsk(sk));
sk = sk2;
refcounted = false;
goto process;
}
/* Fall through to ACK */
......@@ -1845,17 +1853,17 @@ EXPORT_SYMBOL(tcp_v4_destroy_sock);
*/
static void *listening_get_next(struct seq_file *seq, void *cur)
{
struct inet_connection_sock *icsk;
struct hlist_nulls_node *node;
struct sock *sk = cur;
struct inet_listen_hashbucket *ilb;
struct tcp_iter_state *st = seq->private;
struct net *net = seq_file_net(seq);
struct inet_listen_hashbucket *ilb;
struct inet_connection_sock *icsk;
struct sock *sk = cur;
if (!sk) {
get_head:
ilb = &tcp_hashinfo.listening_hash[st->bucket];
spin_lock_bh(&ilb->lock);
sk = sk_nulls_head(&ilb->head);
sk = sk_head(&ilb->head);
st->offset = 0;
goto get_sk;
}
......@@ -1863,28 +1871,20 @@ static void *listening_get_next(struct seq_file *seq, void *cur)
++st->num;
++st->offset;
sk = sk_nulls_next(sk);
sk = sk_next(sk);
get_sk:
sk_nulls_for_each_from(sk, node) {
sk_for_each_from(sk) {
if (!net_eq(sock_net(sk), net))
continue;
if (sk->sk_family == st->family) {
cur = sk;
goto out;
}
if (sk->sk_family == st->family)
return sk;
icsk = inet_csk(sk);
}
spin_unlock_bh(&ilb->lock);
st->offset = 0;
if (++st->bucket < INET_LHTABLE_SIZE) {
ilb = &tcp_hashinfo.listening_hash[st->bucket];
spin_lock_bh(&ilb->lock);
sk = sk_nulls_head(&ilb->head);
goto get_sk;
}
cur = NULL;
out:
return cur;
if (++st->bucket < INET_LHTABLE_SIZE)
goto get_head;
return NULL;
}
static void *listening_get_idx(struct seq_file *seq, loff_t *pos)
......
......@@ -120,6 +120,7 @@ static inline int compute_score(struct sock *sk, struct net *net,
return score;
}
/* called with rcu_read_lock() */
struct sock *inet6_lookup_listener(struct net *net,
struct inet_hashinfo *hashinfo,
struct sk_buff *skb, int doff,
......@@ -127,38 +128,27 @@ struct sock *inet6_lookup_listener(struct net *net,
const __be16 sport, const struct in6_addr *daddr,
const unsigned short hnum, const int dif)
{
struct sock *sk;
const struct hlist_nulls_node *node;
struct sock *result;
int score, hiscore, matches = 0, reuseport = 0;
bool select_ok = true;
u32 phash = 0;
unsigned int hash = inet_lhashfn(net, hnum);
struct inet_listen_hashbucket *ilb = &hashinfo->listening_hash[hash];
int score, hiscore = 0, matches = 0, reuseport = 0;
struct sock *sk, *result = NULL;
u32 phash = 0;
begin:
result = NULL;
hiscore = 0;
sk_nulls_for_each(sk, node, &ilb->head) {
sk_for_each(sk, &ilb->head) {
score = compute_score(sk, net, hnum, daddr, dif);
if (score > hiscore) {
hiscore = score;
result = sk;
reuseport = sk->sk_reuseport;
if (reuseport) {
phash = inet6_ehashfn(net, daddr, hnum,
saddr, sport);
if (select_ok) {
struct sock *sk2;
sk2 = reuseport_select_sock(sk, phash,
skb, doff);
if (sk2) {
result = sk2;
goto found;
}
}
result = reuseport_select_sock(sk, phash,
skb, doff);
if (result)
return result;
matches = 1;
}
result = sk;
reuseport = sk->sk_reuseport;
} else if (score == hiscore && reuseport) {
matches++;
if (reciprocal_scale(phash, matches) == 0)
......@@ -166,24 +156,6 @@ begin:
phash = next_pseudo_random32(phash);
}
}
/*
* if the nulls value we got at the end of this lookup is
* not the expected one, we must restart lookup.
* We probably met an item that was moved to another chain.
*/
if (get_nulls_value(node) != hash + LISTENING_NULLS_BASE)
goto begin;
if (result) {
found:
if (unlikely(!atomic_inc_not_zero(&result->sk_refcnt)))
result = NULL;
else if (unlikely(compute_score(result, net, hnum, daddr,
dif) < hiscore)) {
sock_put(result);
select_ok = false;
goto begin;
}
}
return result;
}
EXPORT_SYMBOL_GPL(inet6_lookup_listener);
......@@ -195,10 +167,12 @@ struct sock *inet6_lookup(struct net *net, struct inet_hashinfo *hashinfo,
const int dif)
{
struct sock *sk;
bool refcounted;
sk = __inet6_lookup(net, hashinfo, skb, doff, saddr, sport, daddr,
ntohs(dport), dif);
ntohs(dport), dif, &refcounted);
if (sk && !refcounted && !atomic_inc_not_zero(&sk->sk_refcnt))
sk = NULL;
return sk;
}
EXPORT_SYMBOL_GPL(inet6_lookup);
......
......@@ -858,6 +858,7 @@ static void tcp_v6_send_reset(const struct sock *sk, struct sk_buff *skb)
return;
#ifdef CONFIG_TCP_MD5SIG
rcu_read_lock();
hash_location = tcp_parse_md5sig_option(th);
if (sk && sk_fullsock(sk)) {
key = tcp_v6_md5_do_lookup(sk, &ipv6h->saddr);
......@@ -875,16 +876,15 @@ static void tcp_v6_send_reset(const struct sock *sk, struct sk_buff *skb)
th->source, &ipv6h->daddr,
ntohs(th->source), tcp_v6_iif(skb));
if (!sk1)
return;
goto out;
rcu_read_lock();
key = tcp_v6_md5_do_lookup(sk1, &ipv6h->saddr);
if (!key)
goto release_sk1;
goto out;
genhash = tcp_v6_md5_hash_skb(newhash, key, NULL, skb);
if (genhash || memcmp(hash_location, newhash, 16) != 0)
goto release_sk1;
goto out;
}
#endif
......@@ -898,11 +898,8 @@ static void tcp_v6_send_reset(const struct sock *sk, struct sk_buff *skb)
tcp_v6_send_response(sk, skb, seq, ack_seq, 0, 0, 0, oif, key, 1, 0, 0);
#ifdef CONFIG_TCP_MD5SIG
release_sk1:
if (sk1) {
rcu_read_unlock();
sock_put(sk1);
}
out:
rcu_read_unlock();
#endif
}
......@@ -1351,6 +1348,7 @@ static int tcp_v6_rcv(struct sk_buff *skb)
{
const struct tcphdr *th;
const struct ipv6hdr *hdr;
bool refcounted;
struct sock *sk;
int ret;
struct net *net = dev_net(skb->dev);
......@@ -1381,7 +1379,8 @@ static int tcp_v6_rcv(struct sk_buff *skb)
lookup:
sk = __inet6_lookup_skb(&tcp_hashinfo, skb, __tcp_hdrlen(th),
th->source, th->dest, inet6_iif(skb));
th->source, th->dest, inet6_iif(skb),
&refcounted);
if (!sk)
goto no_tcp_socket;
......@@ -1404,6 +1403,7 @@ process:
goto lookup;
}
sock_hold(sk);
refcounted = true;
nsk = tcp_check_req(sk, skb, req, false);
if (!nsk) {
reqsk_put(req);
......@@ -1460,7 +1460,8 @@ process:
bh_unlock_sock(sk);
put_and_return:
sock_put(sk);
if (refcounted)
sock_put(sk);
return ret ? -1 : 0;
no_tcp_socket:
......@@ -1483,7 +1484,8 @@ discard_it:
return 0;
discard_and_relse:
sock_put(sk);
if (refcounted)
sock_put(sk);
goto discard_it;
do_time_wait:
......@@ -1514,6 +1516,7 @@ do_time_wait:
inet_twsk_deschedule_put(tw);
sk = sk2;
tcp_v6_restore_cb(skb);
refcounted = false;
goto process;
}
/* Fall through to ACK */
......
......@@ -120,9 +120,9 @@ xt_socket_get_sock_v4(struct net *net, struct sk_buff *skb, const int doff,
{
switch (protocol) {
case IPPROTO_TCP:
return __inet_lookup(net, &tcp_hashinfo, skb, doff,
saddr, sport, daddr, dport,
in->ifindex);
return inet_lookup(net, &tcp_hashinfo, skb, doff,
saddr, sport, daddr, dport,
in->ifindex);
case IPPROTO_UDP:
return udp4_lib_lookup(net, saddr, sport, daddr, dport,
in->ifindex);
......
Markdown is supported
0% or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment