From d1e37288c9146dccff830e3253e403af8705b51f Mon Sep 17 00:00:00 2001 From: "Su, Xuemin" Date: Mon, 13 Jun 2016 11:02:50 +0800 Subject: [PATCH] udp reuseport: fix packet of same flow hashed to different socket There is a corner case in which udp packets belonging to a same flow are hashed to different socket when hslot->count changes from 10 to 11: 1) When hslot->count <= 10, __udp_lib_lookup() searches udp_table->hash, and always passes 'daddr' to udp_ehashfn(). 2) When hslot->count > 10, __udp_lib_lookup() searches udp_table->hash2, but may pass 'INADDR_ANY' to udp_ehashfn() if the sockets are bound to INADDR_ANY instead of some specific addr. That means when hslot->count changes from 10 to 11, the hash calculated by udp_ehashfn() is also changed, and the udp packets belonging to a same flow will be hashed to different socket. This is easily reproduced: 1) Create 10 udp sockets and bind all of them to 0.0.0.0:40000. 2) From the same host send udp packets to 127.0.0.1:40000, record the socket index which receives the packets. 3) Create 1 more udp socket and bind it to 0.0.0.0:44096. The number 44096 is 40000 + UDP_HASH_SIZE(4096), this makes the new socket put into the same hslot as the aformentioned 10 sockets, and makes the hslot->count change from 10 to 11. 4) From the same host send udp packets to 127.0.0.1:40000, and the socket index which receives the packets will be different from the one received in step 2. This should not happen as the socket bound to 0.0.0.0:44096 should not change the behavior of the sockets bound to 0.0.0.0:40000. It's the same case for IPv6, and this patch also fixes that. Signed-off-by: Su, Xuemin Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- net/ipv4/udp.c | 73 +++++++++++--------------------------------------- net/ipv6/udp.c | 71 +++++++++++------------------------------------- 2 files changed, 32 insertions(+), 112 deletions(-) diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c index ba0d8b8b7690..ca5e8ea29538 100644 --- a/net/ipv4/udp.c +++ b/net/ipv4/udp.c @@ -391,9 +391,9 @@ int udp_v4_get_port(struct sock *sk, unsigned short snum) return udp_lib_get_port(sk, snum, ipv4_rcv_saddr_equal, hash2_nulladdr); } -static inline int compute_score(struct sock *sk, struct net *net, - __be32 saddr, unsigned short hnum, __be16 sport, - __be32 daddr, __be16 dport, int dif) +static int compute_score(struct sock *sk, struct net *net, + __be32 saddr, __be16 sport, + __be32 daddr, unsigned short hnum, int dif) { int score; struct inet_sock *inet; @@ -434,52 +434,6 @@ static inline int compute_score(struct sock *sk, struct net *net, return score; } -/* - * In this second variant, we check (daddr, dport) matches (inet_rcv_sadd, inet_num) - */ -static inline int compute_score2(struct sock *sk, struct net *net, - __be32 saddr, __be16 sport, - __be32 daddr, unsigned int hnum, int dif) -{ - int score; - struct inet_sock *inet; - - if (!net_eq(sock_net(sk), net) || - ipv6_only_sock(sk)) - return -1; - - inet = inet_sk(sk); - - if (inet->inet_rcv_saddr != daddr || - inet->inet_num != hnum) - return -1; - - score = (sk->sk_family == PF_INET) ? 2 : 1; - - if (inet->inet_daddr) { - if (inet->inet_daddr != saddr) - return -1; - score += 4; - } - - if (inet->inet_dport) { - if (inet->inet_dport != sport) - return -1; - score += 4; - } - - if (sk->sk_bound_dev_if) { - if (sk->sk_bound_dev_if != dif) - return -1; - score += 4; - } - - if (sk->sk_incoming_cpu == raw_smp_processor_id()) - score++; - - return score; -} - static u32 udp_ehashfn(const struct net *net, const __be32 laddr, const __u16 lport, const __be32 faddr, const __be16 fport) @@ -492,11 +446,11 @@ static u32 udp_ehashfn(const struct net *net, const __be32 laddr, udp_ehash_secret + net_hash_mix(net)); } -/* called with read_rcu_lock() */ +/* called with rcu_read_lock() */ static struct sock *udp4_lib_lookup2(struct net *net, __be32 saddr, __be16 sport, __be32 daddr, unsigned int hnum, int dif, - struct udp_hslot *hslot2, unsigned int slot2, + struct udp_hslot *hslot2, struct sk_buff *skb) { struct sock *sk, *result; @@ -506,7 +460,7 @@ static struct sock *udp4_lib_lookup2(struct net *net, result = NULL; badness = 0; udp_portaddr_for_each_entry_rcu(sk, &hslot2->head) { - score = compute_score2(sk, net, saddr, sport, + score = compute_score(sk, net, saddr, sport, daddr, hnum, dif); if (score > badness) { reuseport = sk->sk_reuseport; @@ -554,17 +508,22 @@ struct sock *__udp4_lib_lookup(struct net *net, __be32 saddr, result = udp4_lib_lookup2(net, saddr, sport, daddr, hnum, dif, - hslot2, slot2, skb); + hslot2, skb); if (!result) { + unsigned int old_slot2 = slot2; hash2 = udp4_portaddr_hash(net, htonl(INADDR_ANY), hnum); slot2 = hash2 & udptable->mask; + /* avoid searching the same slot again. */ + if (unlikely(slot2 == old_slot2)) + return result; + hslot2 = &udptable->hash2[slot2]; if (hslot->count < hslot2->count) goto begin; result = udp4_lib_lookup2(net, saddr, sport, - htonl(INADDR_ANY), hnum, dif, - hslot2, slot2, skb); + daddr, hnum, dif, + hslot2, skb); } return result; } @@ -572,8 +531,8 @@ begin: result = NULL; badness = 0; sk_for_each_rcu(sk, &hslot->head) { - score = compute_score(sk, net, saddr, hnum, sport, - daddr, dport, dif); + score = compute_score(sk, net, saddr, sport, + daddr, hnum, dif); if (score > badness) { reuseport = sk->sk_reuseport; if (reuseport) { diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c index f421c9f23c5b..005dc82c2138 100644 --- a/net/ipv6/udp.c +++ b/net/ipv6/udp.c @@ -115,11 +115,10 @@ static void udp_v6_rehash(struct sock *sk) udp_lib_rehash(sk, new_hash); } -static inline int compute_score(struct sock *sk, struct net *net, - unsigned short hnum, - const struct in6_addr *saddr, __be16 sport, - const struct in6_addr *daddr, __be16 dport, - int dif) +static int compute_score(struct sock *sk, struct net *net, + const struct in6_addr *saddr, __be16 sport, + const struct in6_addr *daddr, unsigned short hnum, + int dif) { int score; struct inet_sock *inet; @@ -162,54 +161,11 @@ static inline int compute_score(struct sock *sk, struct net *net, return score; } -static inline int compute_score2(struct sock *sk, struct net *net, - const struct in6_addr *saddr, __be16 sport, - const struct in6_addr *daddr, - unsigned short hnum, int dif) -{ - int score; - struct inet_sock *inet; - - if (!net_eq(sock_net(sk), net) || - udp_sk(sk)->udp_port_hash != hnum || - sk->sk_family != PF_INET6) - return -1; - - if (!ipv6_addr_equal(&sk->sk_v6_rcv_saddr, daddr)) - return -1; - - score = 0; - inet = inet_sk(sk); - - if (inet->inet_dport) { - if (inet->inet_dport != sport) - return -1; - score++; - } - - if (!ipv6_addr_any(&sk->sk_v6_daddr)) { - if (!ipv6_addr_equal(&sk->sk_v6_daddr, saddr)) - return -1; - score++; - } - - if (sk->sk_bound_dev_if) { - if (sk->sk_bound_dev_if != dif) - return -1; - score++; - } - - if (sk->sk_incoming_cpu == raw_smp_processor_id()) - score++; - - return score; -} - -/* called with read_rcu_lock() */ +/* called with rcu_read_lock() */ static struct sock *udp6_lib_lookup2(struct net *net, const struct in6_addr *saddr, __be16 sport, const struct in6_addr *daddr, unsigned int hnum, int dif, - struct udp_hslot *hslot2, unsigned int slot2, + struct udp_hslot *hslot2, struct sk_buff *skb) { struct sock *sk, *result; @@ -219,7 +175,7 @@ static struct sock *udp6_lib_lookup2(struct net *net, result = NULL; badness = -1; udp_portaddr_for_each_entry_rcu(sk, &hslot2->head) { - score = compute_score2(sk, net, saddr, sport, + score = compute_score(sk, net, saddr, sport, daddr, hnum, dif); if (score > badness) { reuseport = sk->sk_reuseport; @@ -268,17 +224,22 @@ struct sock *__udp6_lib_lookup(struct net *net, result = udp6_lib_lookup2(net, saddr, sport, daddr, hnum, dif, - hslot2, slot2, skb); + hslot2, skb); if (!result) { + unsigned int old_slot2 = slot2; hash2 = udp6_portaddr_hash(net, &in6addr_any, hnum); slot2 = hash2 & udptable->mask; + /* avoid searching the same slot again. */ + if (unlikely(slot2 == old_slot2)) + return result; + hslot2 = &udptable->hash2[slot2]; if (hslot->count < hslot2->count) goto begin; result = udp6_lib_lookup2(net, saddr, sport, - &in6addr_any, hnum, dif, - hslot2, slot2, skb); + daddr, hnum, dif, + hslot2, skb); } return result; } @@ -286,7 +247,7 @@ begin: result = NULL; badness = -1; sk_for_each_rcu(sk, &hslot->head) { - score = compute_score(sk, net, hnum, saddr, sport, daddr, dport, dif); + score = compute_score(sk, net, saddr, sport, daddr, hnum, dif); if (score > badness) { reuseport = sk->sk_reuseport; if (reuseport) { -- 2.39.5