diff options
| -rw-r--r-- | net/ipv4/udp.c | 55 |
1 files changed, 39 insertions, 16 deletions
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c index cf5ab0581eb..b7faffe5c02 100644 --- a/net/ipv4/udp.c +++ b/net/ipv4/udp.c @@ -120,8 +120,11 @@ EXPORT_SYMBOL(sysctl_udp_wmem_min); atomic_t udp_memory_allocated; EXPORT_SYMBOL(udp_memory_allocated); +#define PORTS_PER_CHAIN (65536 / UDP_HTABLE_SIZE) + static int udp_lib_lport_inuse(struct net *net, __u16 num, const struct udp_hslot *hslot, + unsigned long *bitmap, struct sock *sk, int (*saddr_comp)(const struct sock *sk1, const struct sock *sk2)) @@ -132,12 +135,17 @@ static int udp_lib_lport_inuse(struct net *net, __u16 num, sk_nulls_for_each(sk2, node, &hslot->head) if (net_eq(sock_net(sk2), net) && sk2 != sk && - sk2->sk_hash == num && + (bitmap || 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; + (*saddr_comp)(sk, sk2)) { + if (bitmap) + __set_bit(sk2->sk_hash / UDP_HTABLE_SIZE, + bitmap); + else + return 1; + } return 0; } @@ -160,32 +168,47 @@ int udp_lib_get_port(struct sock *sk, unsigned short snum, if (!snum) { int low, high, remaining; unsigned rand; - unsigned short first; + unsigned short first, last; + DECLARE_BITMAP(bitmap, PORTS_PER_CHAIN); inet_get_local_port_range(&low, &high); remaining = (high - low) + 1; rand = net_random(); - snum = first = rand % remaining + low; - rand |= 1; - for (;;) { - hslot = &udptable->hash[udp_hashfn(net, snum)]; + first = (((u64)rand * remaining) >> 32) + low; + /* + * force rand to be an odd multiple of UDP_HTABLE_SIZE + */ + rand = (rand | 1) * UDP_HTABLE_SIZE; + for (last = first + UDP_HTABLE_SIZE; first != last; first++) { + hslot = &udptable->hash[udp_hashfn(net, first)]; + bitmap_zero(bitmap, PORTS_PER_CHAIN); spin_lock_bh(&hslot->lock); - if (!udp_lib_lport_inuse(net, snum, hslot, sk, saddr_comp)) - break; - spin_unlock_bh(&hslot->lock); + udp_lib_lport_inuse(net, snum, hslot, bitmap, sk, + saddr_comp); + + snum = first; + /* + * Iterate on all possible values of snum for this hash. + * Using steps of an odd multiple of UDP_HTABLE_SIZE + * give us randomization and full range coverage. + */ do { - snum = snum + rand; - } while (snum < low || snum > high); - if (snum == first) - goto fail; + if (low <= snum && snum <= high && + !test_bit(snum / UDP_HTABLE_SIZE, bitmap)) + goto found; + snum += rand; + } while (snum != first); + spin_unlock_bh(&hslot->lock); } + goto fail; } else { hslot = &udptable->hash[udp_hashfn(net, snum)]; spin_lock_bh(&hslot->lock); - if (udp_lib_lport_inuse(net, snum, hslot, sk, saddr_comp)) + if (udp_lib_lport_inuse(net, snum, hslot, NULL, sk, saddr_comp)) goto fail_unlock; } +found: inet_sk(sk)->num = snum; sk->sk_hash = snum; if (sk_unhashed(sk)) { |