From d9fbc7f6431fc0e5c0ddedf72206d7c5175c5c9a Mon Sep 17 00:00:00 2001 From: Peter Oskolkov Date: Wed, 12 Dec 2018 13:15:35 -0800 Subject: [PATCH] net: tcp: prefer listeners bound to an address A relatively common use case is to have several IPs configured on a host, and have different listeners for each of them. We would like to add a "catch all" listener on addr_any, to match incoming connections not served by any of the listeners bound to a specific address. However, port-only lookups can match addr_any sockets when sockets listening on specific addresses are present if so_reuseport flag is set. This patch eliminates lookups into port-only hashtable, as lookups by (addr,port) tuple are easily available. In addition, compute_score() is tweaked to _not_ match addr_any sockets to specific addresses, as hash collisions could result in the unwanted behavior described above. Tested: the patch compiles; full test in the last patch in this patchset. Existing reuseport_* selftests also pass. Suggested-by: Eric Dumazet Signed-off-by: Peter Oskolkov Signed-off-by: David S. Miller --- net/ipv4/inet_hashtables.c | 60 +++++--------------------------------- 1 file changed, 8 insertions(+), 52 deletions(-) diff --git a/net/ipv4/inet_hashtables.c b/net/ipv4/inet_hashtables.c index 13890d5bfc34..cd03ab42705b 100644 --- a/net/ipv4/inet_hashtables.c +++ b/net/ipv4/inet_hashtables.c @@ -234,24 +234,16 @@ static inline int compute_score(struct sock *sk, struct net *net, const int dif, const int sdif, bool exact_dif) { int score = -1; - struct inet_sock *inet = inet_sk(sk); - bool dev_match; - if (net_eq(sock_net(sk), net) && inet->inet_num == hnum && + if (net_eq(sock_net(sk), net) && sk->sk_num == hnum && !ipv6_only_sock(sk)) { - __be32 rcv_saddr = inet->inet_rcv_saddr; - score = sk->sk_family == PF_INET ? 2 : 1; - if (rcv_saddr) { - if (rcv_saddr != daddr) - return -1; - score += 4; - } - dev_match = inet_sk_bound_dev_eq(net, sk->sk_bound_dev_if, - dif, sdif); - if (!dev_match) + if (sk->sk_rcv_saddr != daddr) + return -1; + + if (!inet_sk_bound_dev_eq(net, sk->sk_bound_dev_if, dif, sdif)) return -1; - score += 4; + score = sk->sk_family == PF_INET ? 2 : 1; if (sk->sk_incoming_cpu == raw_smp_processor_id()) score++; } @@ -307,26 +299,12 @@ struct sock *__inet_lookup_listener(struct net *net, const __be32 daddr, const unsigned short hnum, const int dif, const int sdif) { - unsigned int hash = inet_lhashfn(net, hnum); - struct inet_listen_hashbucket *ilb = &hashinfo->listening_hash[hash]; - bool exact_dif = inet_exact_dif_match(net, skb); struct inet_listen_hashbucket *ilb2; - struct sock *sk, *result = NULL; - int score, hiscore = 0; + struct sock *result = NULL; unsigned int hash2; - u32 phash = 0; - - if (ilb->count <= 10 || !hashinfo->lhash2) - goto port_lookup; - - /* Too many sk in the ilb bucket (which is hashed by port alone). - * Try lhash2 (which is hashed by port and addr) instead. - */ hash2 = ipv4_portaddr_hash(net, daddr, hnum); ilb2 = inet_lhash2_bucket(hashinfo, hash2); - if (ilb2->count > ilb->count) - goto port_lookup; result = inet_lhash2_lookup(net, ilb2, skb, doff, saddr, sport, daddr, hnum, @@ -335,34 +313,12 @@ struct sock *__inet_lookup_listener(struct net *net, goto done; /* Lookup lhash2 with INADDR_ANY */ - hash2 = ipv4_portaddr_hash(net, htonl(INADDR_ANY), hnum); ilb2 = inet_lhash2_bucket(hashinfo, hash2); - if (ilb2->count > ilb->count) - goto port_lookup; result = inet_lhash2_lookup(net, ilb2, skb, doff, - saddr, sport, daddr, hnum, + saddr, sport, htonl(INADDR_ANY), hnum, dif, sdif); - goto done; - -port_lookup: - sk_for_each_rcu(sk, &ilb->head) { - score = compute_score(sk, net, hnum, daddr, - dif, sdif, exact_dif); - if (score > hiscore) { - if (sk->sk_reuseport) { - phash = inet_ehashfn(net, daddr, hnum, - saddr, sport); - result = reuseport_select_sock(sk, phash, - skb, doff); - if (result) - goto done; - } - result = sk; - hiscore = score; - } - } done: if (unlikely(IS_ERR(result))) return NULL; -- 2.30.2