Revert "tcp/dccp: get rid of inet_twsk_purge()"

This reverts commits:

8824bc0f9c93f6f07c4a81a30df4a8440ba9f6c4 ("tcp/dccp: get rid of inet_twsk_purge()")
bc3343585f9fb2988faf858ce5f1f85b82045609 ("tcp/dccp: add tw->tw_bslot")

As Leonard pointed out, a newly allocated netns can happen
to reuse a freed 'struct net'.

While TCP TW timers were covered by my patches, other things were not:

1) Lookups in rx path (INET_MATCH() and INET6_MATCH()), as they look
  at 4-tuple plus the 'struct net' pointer.

2) /proc/net/tcp[6] and inet_diag, same reason.

3) hashinfo->bhash[], same reason.

Fixing all this seems risky, lets instead revert.

In the future, we might have a per netns tcp hash table, or
a per netns list of timewait sockets...

Fixes: 8824bc0f9c93 ("tcp/dccp: get rid of inet_twsk_purge()")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Leonard Crestez <cdleonard@gmail.com>
Tested-by: Leonard Crestez <cdleonard@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/net/inet_timewait_sock.h b/include/net/inet_timewait_sock.h
index 463ae5d33eb09c40caeb4d039af268609b5e563b..5b47545f22d39eb2dd9725ac37bd7d7a9016a03c 100644 (file)
--- a/include/net/inet_timewait_sock.h
+++ b/include/net/inet_timewait_sock.h
@@ -71,7 +71,6 @@ struct inet_timewait_sock {
                                tw_tos          : 8;
        u32                     tw_txhash;
        u32                     tw_priority;
-       u32                     tw_bslot; /* bind bucket slot */
        struct timer_list       tw_timer;
        struct inet_bind_bucket *tw_tb;
 };
@@ -110,6 +109,8 @@ static inline void inet_twsk_reschedule(struct inet_timewait_sock *tw, int timeo
 
 void inet_twsk_deschedule_put(struct inet_timewait_sock *tw);
 
+void inet_twsk_purge(struct inet_hashinfo *hashinfo, int family);
+
 static inline
 struct net *twsk_net(const struct inet_timewait_sock *twsk)
 {

diff --git a/net/dccp/ipv4.c b/net/dccp/ipv4.c
index ae662567a6cb6a440c79a9805a2cd6d146ac5a29..0ea29270d7e53730d14ec43654be8f956f891552 100644 (file)
--- a/net/dccp/ipv4.c
+++ b/net/dccp/ipv4.c
@@ -1030,9 +1030,15 @@ static void __net_exit dccp_v4_exit_net(struct net *net)
        inet_ctl_sock_destroy(pn->v4_ctl_sk);
 }
 
+static void __net_exit dccp_v4_exit_batch(struct list_head *net_exit_list)
+{
+       inet_twsk_purge(&dccp_hashinfo, AF_INET);
+}
+
 static struct pernet_operations dccp_v4_ops = {
        .init   = dccp_v4_init_net,
        .exit   = dccp_v4_exit_net,
+       .exit_batch = dccp_v4_exit_batch,
        .id     = &dccp_v4_pernet_id,
        .size   = sizeof(struct dccp_v4_pernet),
 };

diff --git a/net/dccp/ipv6.c b/net/dccp/ipv6.c
index eab3bd1ee9a0a0064c04ff97fd8363e60daa0079..fa663518fa0e465458b7486ad0cd0672425f08b0 100644 (file)
--- a/net/dccp/ipv6.c
+++ b/net/dccp/ipv6.c
@@ -1115,9 +1115,15 @@ static void __net_exit dccp_v6_exit_net(struct net *net)
        inet_ctl_sock_destroy(pn->v6_ctl_sk);
 }
 
+static void __net_exit dccp_v6_exit_batch(struct list_head *net_exit_list)
+{
+       inet_twsk_purge(&dccp_hashinfo, AF_INET6);
+}
+
 static struct pernet_operations dccp_v6_ops = {
        .init   = dccp_v6_init_net,
        .exit   = dccp_v6_exit_net,
+       .exit_batch = dccp_v6_exit_batch,
        .id     = &dccp_v6_pernet_id,
        .size   = sizeof(struct dccp_v6_pernet),
 };

diff --git a/net/ipv4/inet_timewait_sock.c b/net/ipv4/inet_timewait_sock.c
index 9e0bbd02656013e6e8be5765a7b86fc16e6bf831..0ec501845cb3bb51082f8091b4e0ebb32f83bf33 100644 (file)
--- a/net/ipv4/inet_timewait_sock.c
+++ b/net/ipv4/inet_timewait_sock.c
@@ -52,7 +52,8 @@ static void inet_twsk_kill(struct inet_timewait_sock *tw)
        spin_unlock(lock);
 
        /* Disassociate with bind bucket. */
-       bhead = &hashinfo->bhash[tw->tw_bslot];
+       bhead = &hashinfo->bhash[inet_bhashfn(twsk_net(tw), tw->tw_num,
+                       hashinfo->bhash_size)];
 
        spin_lock(&bhead->lock);
        inet_twsk_bind_unhash(tw, hashinfo);
@@ -111,12 +112,8 @@ void inet_twsk_hashdance(struct inet_timewait_sock *tw, struct sock *sk,
           Note, that any socket with inet->num != 0 MUST be bound in
           binding cache, even if it is closed.
         */
-       /* Cache inet_bhashfn(), because 'struct net' might be no longer
-        * available later in inet_twsk_kill().
-        */
-       tw->tw_bslot = inet_bhashfn(twsk_net(tw), inet->inet_num,
-                                   hashinfo->bhash_size);
-       bhead = &hashinfo->bhash[tw->tw_bslot];
+       bhead = &hashinfo->bhash[inet_bhashfn(twsk_net(tw), inet->inet_num,
+                       hashinfo->bhash_size)];
        spin_lock(&bhead->lock);
        tw->tw_tb = icsk->icsk_bind_hash;
        WARN_ON(!icsk->icsk_bind_hash);
@@ -257,3 +254,50 @@ void __inet_twsk_schedule(struct inet_timewait_sock *tw, int timeo, bool rearm)
        }
 }
 EXPORT_SYMBOL_GPL(__inet_twsk_schedule);
+
+void inet_twsk_purge(struct inet_hashinfo *hashinfo, int family)
+{
+       struct inet_timewait_sock *tw;
+       struct sock *sk;
+       struct hlist_nulls_node *node;
+       unsigned int slot;
+
+       for (slot = 0; slot <= hashinfo->ehash_mask; slot++) {
+               struct inet_ehash_bucket *head = &hashinfo->ehash[slot];
+restart_rcu:
+               cond_resched();
+               rcu_read_lock();
+restart:
+               sk_nulls_for_each_rcu(sk, node, &head->chain) {
+                       if (sk->sk_state != TCP_TIME_WAIT)
+                               continue;
+                       tw = inet_twsk(sk);
+                       if ((tw->tw_family != family) ||
+                               refcount_read(&twsk_net(tw)->ns.count))
+                               continue;
+
+                       if (unlikely(!refcount_inc_not_zero(&tw->tw_refcnt)))
+                               continue;
+
+                       if (unlikely((tw->tw_family != family) ||
+                                    refcount_read(&twsk_net(tw)->ns.count))) {
+                               inet_twsk_put(tw);
+                               goto restart;
+                       }
+
+                       rcu_read_unlock();
+                       local_bh_disable();
+                       inet_twsk_deschedule_put(tw);
+                       local_bh_enable();
+                       goto restart_rcu;
+               }
+               /* If the nulls value we got at the end of this lookup is
+                * not the expected one, we must restart lookup.
+                * We probably met an item that was moved to another chain.
+                */
+               if (get_nulls_value(node) != slot)
+                       goto restart;
+               rcu_read_unlock();
+       }
+}
+EXPORT_SYMBOL_GPL(inet_twsk_purge);

diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index f9cec624068dfa1d218357d7e88c89459d7d54f4..457f5b5d5d4a95c06eca82db1dbe7822cb4d040c 100644 (file)
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -3173,6 +3173,8 @@ static void __net_exit tcp_sk_exit_batch(struct list_head *net_exit_list)
 {
        struct net *net;
 
+       inet_twsk_purge(&tcp_hashinfo, AF_INET);
+
        list_for_each_entry(net, net_exit_list, exit_list)
                tcp_fastopen_ctx_destroy(net);
 }

diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 13678d3908fac9990e5b0c0df87fa4cca685baaf..faaddaf43c90b96e7a2bc9fbad7941ae5ada1b3c 100644 (file)
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -2207,9 +2207,15 @@ static void __net_exit tcpv6_net_exit(struct net *net)
        inet_ctl_sock_destroy(net->ipv6.tcp_sk);
 }
 
+static void __net_exit tcpv6_net_exit_batch(struct list_head *net_exit_list)
+{
+       inet_twsk_purge(&tcp_hashinfo, AF_INET6);
+}
+
 static struct pernet_operations tcpv6_net_ops = {
        .init       = tcpv6_net_init,
        .exit       = tcpv6_net_exit,
+       .exit_batch = tcpv6_net_exit_batch,
 };
 
 int __init tcpv6_init(void)