net: make skb_set_owner_w() more robust

skb_set_owner_w() is called from various places that assume
skb->sk always point to a full blown socket (as it changes
sk->sk_wmem_alloc)

We'd like to attach skb to request sockets, and in the future
to timewait sockets as well. For these kind of pseudo sockets,
we need to take a traditional refcount and use sock_edemux()
as the destructor.

It is now time to un-inline skb_set_owner_w(), being too big.

Fixes: ca6fb0651883 ("tcp: attach SYNACK messages to request sockets instead of listener")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Bisected-by: Haiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/net/sock.h b/include/net/sock.h
index aeed5c95f3caedcdb4c10668c67764d8557e9369..f570e75e3da927c54438340988f2a56762220060 100644 (file)
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -1951,6 +1951,8 @@ static inline void skb_set_hash_from_sk(struct sk_buff *skb, struct sock *sk)
        }
 }
 
+void skb_set_owner_w(struct sk_buff *skb, struct sock *sk);
+
 /*
  *     Queue a received datagram if it will fit. Stream and sequenced
  *     protocols can't normally use this as they need to fit buffers in
@@ -1959,21 +1961,6 @@ static inline void skb_set_hash_from_sk(struct sk_buff *skb, struct sock *sk)
  *     Inlined as it's very short and called for pretty much every
  *     packet ever received.
  */
-
-static inline void skb_set_owner_w(struct sk_buff *skb, struct sock *sk)
-{
-       skb_orphan(skb);
-       skb->sk = sk;
-       skb->destructor = sock_wfree;
-       skb_set_hash_from_sk(skb, sk);
-       /*
-        * We used to take a refcount on sk, but following operation
-        * is enough to guarantee sk_free() wont free this sock until
-        * all in-flight packets are completed
-        */
-       atomic_add(skb->truesize, &sk->sk_wmem_alloc);
-}
-
 static inline void skb_set_owner_r(struct sk_buff *skb, struct sock *sk)
 {
        skb_orphan(skb);

diff --git a/net/core/sock.c b/net/core/sock.c
index 0ef30aa90132c7a1a04971c773d4de8ed4ac146b..7529eb9463be21a92dab4180adf5059cc0587807 100644 (file)
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -1656,6 +1656,28 @@ void sock_wfree(struct sk_buff *skb)
 }
 EXPORT_SYMBOL(sock_wfree);
 
+void skb_set_owner_w(struct sk_buff *skb, struct sock *sk)
+{
+       skb_orphan(skb);
+       skb->sk = sk;
+#ifdef CONFIG_INET
+       if (unlikely(!sk_fullsock(sk))) {
+               skb->destructor = sock_edemux;
+               sock_hold(sk);
+               return;
+       }
+#endif
+       skb->destructor = sock_wfree;
+       skb_set_hash_from_sk(skb, sk);
+       /*
+        * We used to take a refcount on sk, but following operation
+        * is enough to guarantee sk_free() wont free this sock until
+        * all in-flight packets are completed
+        */
+       atomic_add(skb->truesize, &sk->sk_wmem_alloc);
+}
+EXPORT_SYMBOL(skb_set_owner_w);
+
 void skb_orphan_partial(struct sk_buff *skb)
 {
        /* TCP stack sets skb->ooo_okay based on sk_wmem_alloc,

diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index f4f9793eb0255e62f623303b87e44c1c777e2251..cb7ca569052c5b69f78418e9c966cb285eff1d50 100644 (file)
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -2963,9 +2963,7 @@ struct sk_buff *tcp_make_synack(const struct sock *sk, struct dst_entry *dst,
        skb_reserve(skb, MAX_TCP_HEADER);
 
        if (attach_req) {
-               skb->destructor = sock_edemux;
-               sock_hold(req_to_sk(req));
-               skb->sk = req_to_sk(req);
+               skb_set_owner_w(skb, req_to_sk(req));
        } else {
                /* sk is a const pointer, because we want to express multiple
                 * cpu might call us concurrently.