udp: add rehash on connect()

commit 719f835853a92f6090258114a72ffe41f09155cd upstream

commit 30fff923 introduced in linux-2.6.33 (udp: bind() optimisation)
added a secondary hash on UDP, hashed on (local addr, local port).

Problem is that following sequence :

fd = socket(...)
connect(fd, &remote, ...)

not only selects remote end point (address and port), but also sets
local address, while UDP stack stored in secondary hash table the socket
while its local address was INADDR_ANY (or ipv6 equivalent)

Sequence is :
 - autobind() : choose a random local port, insert socket in hash tables
              [while local address is INADDR_ANY]
 - connect() : set remote address and port, change local address to IP
              given by a route lookup.

When an incoming UDP frame comes, if more than 10 sockets are found in
primary hash table, we switch to secondary table, and fail to find
socket because its local address changed.

One solution to this problem is to rehash datagram socket if needed.

We add a new rehash(struct socket *) method in "struct proto", and
implement this method for UDP v4 & v6, using a common helper.

This rehashing only takes care of secondary hash table, since primary
hash (based on local port only) is not changed.

Reported-by: Krzysztof Piotr Oledzki <ole@ans.pl>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Tested-by: Krzysztof Piotr Oledzki <ole@ans.pl>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/include/net/sock.h b/include/net/sock.h
index 0a691ea7654aefb403e25039f08641691d3de74c..e2a9f591a0e3cd0a660097fc292c5dd75d149367 100644 (file)
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -749,6 +749,7 @@ struct proto {
        /* Keeping track of sk's, looking them up, and port selection methods. */
        void                    (*hash)(struct sock *sk);
        void                    (*unhash)(struct sock *sk);
+       void                    (*rehash)(struct sock *sk);
        int                     (*get_port)(struct sock *sk, unsigned short snum);
 
        /* Keeping track of sockets in use */

diff --git a/include/net/udp.h b/include/net/udp.h
index 5348d80b25bb8a0593c9f0a80f42c4a6b2aeebc9..4201dc8724ca2e82756014a13da037f3baf3c2e6 100644 (file)
--- a/include/net/udp.h
+++ b/include/net/udp.h
@@ -151,6 +151,7 @@ static inline void udp_lib_hash(struct sock *sk)
 }
 
 extern void udp_lib_unhash(struct sock *sk);
+extern void udp_lib_rehash(struct sock *sk, u16 new_hash);
 
 static inline void udp_lib_close(struct sock *sk, long timeout)
 {

diff --git a/net/ipv4/datagram.c b/net/ipv4/datagram.c
index fb2465811b48658b6be95d6cfd2498c3f8d41da7..31cafd491dde07b6a9217ed3e64f5db7ca8279df 100644 (file)
--- a/net/ipv4/datagram.c
+++ b/net/ipv4/datagram.c
@@ -62,8 +62,11 @@ int ip4_datagram_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
        }
        if (!inet->inet_saddr)
                inet->inet_saddr = rt->rt_src;  /* Update source address */
-       if (!inet->inet_rcv_saddr)
+       if (!inet->inet_rcv_saddr) {
                inet->inet_rcv_saddr = rt->rt_src;
+               if (sk->sk_prot->rehash)
+                       sk->sk_prot->rehash(sk);
+       }
        inet->inet_daddr = rt->rt_dst;
        inet->inet_dport = usin->sin_port;
        sk->sk_state = TCP_ESTABLISHED;

diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index eec4ff456e332e0b086d5451478fa5874213e0d1..434dd6777419b51948a6fea97841bb1bbd210083 100644 (file)
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -1260,6 +1260,49 @@ void udp_lib_unhash(struct sock *sk)
 }
 EXPORT_SYMBOL(udp_lib_unhash);
 
+/*
+ * inet_rcv_saddr was changed, we must rehash secondary hash
+ */
+void udp_lib_rehash(struct sock *sk, u16 newhash)
+{
+       if (sk_hashed(sk)) {
+               struct udp_table *udptable = sk->sk_prot->h.udp_table;
+               struct udp_hslot *hslot, *hslot2, *nhslot2;
+
+               hslot2 = udp_hashslot2(udptable, udp_sk(sk)->udp_portaddr_hash);
+               nhslot2 = udp_hashslot2(udptable, newhash);
+               udp_sk(sk)->udp_portaddr_hash = newhash;
+               if (hslot2 != nhslot2) {
+                       hslot = udp_hashslot(udptable, sock_net(sk),
+                                            udp_sk(sk)->udp_port_hash);
+                       /* we must lock primary chain too */
+                       spin_lock_bh(&hslot->lock);
+
+                       spin_lock(&hslot2->lock);
+                       hlist_nulls_del_init_rcu(&udp_sk(sk)->udp_portaddr_node);
+                       hslot2->count--;
+                       spin_unlock(&hslot2->lock);
+
+                       spin_lock(&nhslot2->lock);
+                       hlist_nulls_add_head_rcu(&udp_sk(sk)->udp_portaddr_node,
+                                                &nhslot2->head);
+                       nhslot2->count++;
+                       spin_unlock(&nhslot2->lock);
+
+                       spin_unlock_bh(&hslot->lock);
+               }
+       }
+}
+EXPORT_SYMBOL(udp_lib_rehash);
+
+static void udp_v4_rehash(struct sock *sk)
+{
+       u16 new_hash = udp4_portaddr_hash(sock_net(sk),
+                                         inet_sk(sk)->inet_rcv_saddr,
+                                         inet_sk(sk)->inet_num);
+       udp_lib_rehash(sk, new_hash);
+}
+
 static int __udp_queue_rcv_skb(struct sock *sk, struct sk_buff *skb)
 {
        int rc;
@@ -1843,6 +1886,7 @@ struct proto udp_prot = {
        .backlog_rcv       = __udp_queue_rcv_skb,
        .hash              = udp_lib_hash,
        .unhash            = udp_lib_unhash,
+       .rehash            = udp_v4_rehash,
        .get_port          = udp_v4_get_port,
        .memory_allocated  = &udp_memory_allocated,
        .sysctl_mem        = sysctl_udp_mem,

diff --git a/net/ipv6/datagram.c b/net/ipv6/datagram.c
index 712684687c9a9d8f25baca4ff07a86f0386820bd..0e3754a1237e530f60a12d82d7420787a84a9555 100644 (file)
--- a/net/ipv6/datagram.c
+++ b/net/ipv6/datagram.c
@@ -104,9 +104,12 @@ ipv4_connected:
                if (ipv6_addr_any(&np->saddr))
                        ipv6_addr_set_v4mapped(inet->inet_saddr, &np->saddr);
 
-               if (ipv6_addr_any(&np->rcv_saddr))
+               if (ipv6_addr_any(&np->rcv_saddr)) {
                        ipv6_addr_set_v4mapped(inet->inet_rcv_saddr,
                                               &np->rcv_saddr);
+                       if (sk->sk_prot->rehash)
+                               sk->sk_prot->rehash(sk);
+               }
 
                goto out;
        }
@@ -191,6 +194,8 @@ ipv4_connected:
        if (ipv6_addr_any(&np->rcv_saddr)) {
                ipv6_addr_copy(&np->rcv_saddr, &fl.fl6_src);
                inet->inet_rcv_saddr = LOOPBACK4_IPV6;
+               if (sk->sk_prot->rehash)
+                       sk->sk_prot->rehash(sk);
        }
 
        ip6_dst_store(sk, dst,

diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index 87be58673b55fffc75e34ec0d6cc1dceafd7de8e..97e1214d7ff92c2e711bbde02fb4fcc7a7d52f2a 100644 (file)
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -111,6 +111,15 @@ int udp_v6_get_port(struct sock *sk, unsigned short snum)
        return udp_lib_get_port(sk, snum, ipv6_rcv_saddr_equal, hash2_nulladdr);
 }
 
+static void udp_v6_rehash(struct sock *sk)
+{
+       u16 new_hash = udp6_portaddr_hash(sock_net(sk),
+                                         &inet6_sk(sk)->rcv_saddr,
+                                         inet_sk(sk)->inet_num);
+
+       udp_lib_rehash(sk, new_hash);
+}
+
 static inline int compute_score(struct sock *sk, struct net *net,
                                unsigned short hnum,
                                struct in6_addr *saddr, __be16 sport,
@@ -1452,6 +1461,7 @@ struct proto udpv6_prot = {
        .backlog_rcv       = udpv6_queue_rcv_skb,
        .hash              = udp_lib_hash,
        .unhash            = udp_lib_unhash,
+       .rehash            = udp_v6_rehash,
        .get_port          = udp_v6_get_port,
        .memory_allocated  = &udp_memory_allocated,
        .sysctl_mem        = sysctl_udp_mem,