udp: complete port availability checking

While looking at UDP port randomization, I noticed it
was litle bit pessimistic, not looking at type of sockets
(IPV6/IPV4) and not looking at bound addresses if any.

We should perform same tests than when binding to a
specific port.

This permits a cleanup of udp_lib_get_port()

Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 19 insertions, 24 deletions

diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 67d8430b4a2a..eacf4cfef146 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -122,14 +122,23 @@ EXPORT_SYMBOL(sysctl_udp_wmem_min);
 atomic_t udp_memory_allocated;
 EXPORT_SYMBOL(udp_memory_allocated);
 
-static inline int __udp_lib_lport_inuse(struct net *net, __u16 num,
-                                        const struct hlist_head udptable[])
+static int udp_lib_lport_inuse(struct net *net, __u16 num,
+                               const struct hlist_head udptable[],
+                               struct sock *sk,
+                               int (*saddr_comp)(const struct sock *sk1,
+                                                 const struct sock *sk2))
 {
-        struct sock *sk;
+        struct sock *sk2;
         struct hlist_node *node;
 
-        sk_for_each(sk, node, &udptable[udp_hashfn(net, num)])
-                if (net_eq(sock_net(sk), net) && sk->sk_hash == num)
+        sk_for_each(sk2, node, &udptable[udp_hashfn(net, num)])
+                if (net_eq(sock_net(sk2), net)                  &&
+                    sk2 != sk                                   &&
+                    sk2->sk_hash == num                         &&
+                    (!sk2->sk_reuse || !sk->sk_reuse)           &&
+                    (!sk2->sk_bound_dev_if || !sk->sk_bound_dev_if
+                        || sk2->sk_bound_dev_if == sk->sk_bound_dev_if) &&
+                    (*saddr_comp)(sk, sk2))
                         return 1;
         return 0;
 }
@@ -146,9 +155,6 @@ int udp_lib_get_port(struct sock *sk, unsigned short snum,
                                          const struct sock *sk2 )    )
 {
         struct hlist_head *udptable = sk->sk_prot->h.udp_hash;
-        struct hlist_node *node;
-        struct hlist_head *head;
-        struct sock *sk2;
         int    error = 1;
         struct net *net = sock_net(sk);
 
@@ -165,32 +171,21 @@ int udp_lib_get_port(struct sock *sk, unsigned short snum,
                 rand = net_random();
                 snum = first = rand % remaining + low;
                 rand |= 1;
-                while (__udp_lib_lport_inuse(net, snum, udptable)) {
+                while (udp_lib_lport_inuse(net, snum, udptable, sk,
+                                           saddr_comp)) {
                         do {
                                 snum = snum + rand;
                         } while (snum < low || snum > high);
                         if (snum == first)
                                 goto fail;
                 }
-        } else {
-                head = &udptable[udp_hashfn(net, snum)];
-
-                sk_for_each(sk2, node, head)
-                        if (sk2->sk_hash == snum                             &&
-                            sk2 != sk                                        &&
-                            net_eq(sock_net(sk2), net)                       &&
-                            (!sk2->sk_reuse        || !sk->sk_reuse)         &&
-                            (!sk2->sk_bound_dev_if || !sk->sk_bound_dev_if
-                             || sk2->sk_bound_dev_if == sk->sk_bound_dev_if) &&
-                            (*saddr_comp)(sk, sk2)                             )
-                                goto fail;
-        }
+        } else if (udp_lib_lport_inuse(net, snum, udptable, sk, saddr_comp))
+                goto fail;
 
         inet_sk(sk)->num = snum;
         sk->sk_hash = snum;
         if (sk_unhashed(sk)) {
-                head = &udptable[udp_hashfn(net, snum)];
-                sk_add_node(sk, head);
+                sk_add_node(sk, &udptable[udp_hashfn(net, snum)]);
                 sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
         }
         error = 0;