tcp: Fix a connect() race with timewait sockets
First patch changes __inet_hash_nolisten() and __inet6_hash()
to get a timewait parameter to be able to unhash it from ehash
at same time the new socket is inserted in hash.
This makes sure timewait socket wont be found by a concurrent
writer in __inet_check_established()
Reported-by: kapil dakhane <kdakhane@gmail.com>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/inet_hashtables.c b/net/ipv4/inet_hashtables.c
index 21e5e32..c4201b7 100644
--- a/net/ipv4/inet_hashtables.c
+++ b/net/ipv4/inet_hashtables.c
@@ -351,12 +351,13 @@
inet->inet_dport);
}
-void __inet_hash_nolisten(struct sock *sk)
+int __inet_hash_nolisten(struct sock *sk, struct inet_timewait_sock *tw)
{
struct inet_hashinfo *hashinfo = sk->sk_prot->h.hashinfo;
struct hlist_nulls_head *list;
spinlock_t *lock;
struct inet_ehash_bucket *head;
+ int twrefcnt = 0;
WARN_ON(!sk_unhashed(sk));
@@ -367,8 +368,13 @@
spin_lock(lock);
__sk_nulls_add_node_rcu(sk, list);
+ if (tw) {
+ WARN_ON(sk->sk_hash != tw->tw_hash);
+ twrefcnt = inet_twsk_unhash(tw);
+ }
spin_unlock(lock);
sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
+ return twrefcnt;
}
EXPORT_SYMBOL_GPL(__inet_hash_nolisten);
@@ -378,7 +384,7 @@
struct inet_listen_hashbucket *ilb;
if (sk->sk_state != TCP_LISTEN) {
- __inet_hash_nolisten(sk);
+ __inet_hash_nolisten(sk, NULL);
return;
}
@@ -427,7 +433,7 @@
struct sock *sk, u32 port_offset,
int (*check_established)(struct inet_timewait_death_row *,
struct sock *, __u16, struct inet_timewait_sock **),
- void (*hash)(struct sock *sk))
+ int (*hash)(struct sock *sk, struct inet_timewait_sock *twp))
{
struct inet_hashinfo *hinfo = death_row->hashinfo;
const unsigned short snum = inet_sk(sk)->inet_num;
@@ -435,6 +441,7 @@
struct inet_bind_bucket *tb;
int ret;
struct net *net = sock_net(sk);
+ int twrefcnt = 1;
if (!snum) {
int i, remaining, low, high, port;
@@ -493,13 +500,16 @@
inet_bind_hash(sk, tb, port);
if (sk_unhashed(sk)) {
inet_sk(sk)->inet_sport = htons(port);
- hash(sk);
+ twrefcnt += hash(sk, tw);
}
spin_unlock(&head->lock);
if (tw) {
inet_twsk_deschedule(tw, death_row);
- inet_twsk_put(tw);
+ while (twrefcnt) {
+ twrefcnt--;
+ inet_twsk_put(tw);
+ }
}
ret = 0;
@@ -510,7 +520,7 @@
tb = inet_csk(sk)->icsk_bind_hash;
spin_lock_bh(&head->lock);
if (sk_head(&tb->owners) == sk && !sk->sk_bind_node.next) {
- hash(sk);
+ hash(sk, NULL);
spin_unlock_bh(&head->lock);
return 0;
} else {