inet: fix request sock refcounting

While testing last patch series, I found req sock refcounting was wrong.

We must set skc_refcnt to 1 for all request socks added in hashes,
but also on request sockets created by FastOpen or syncookies.

It is tricky because we need to defer this initialization so that
future RCU lookups do not try to take a refcount on a not yet
fully initialized request socket.

Also get rid of ireq_refcnt alias.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Fixes: 13854e5a6046 ("inet: add proper refcounting to request sock")
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/net/inet_connection_sock.h b/include/net/inet_connection_sock.h
index 191feec..b9a6b0a 100644 (file)
--- a/include/net/inet_connection_sock.h
+++ b/include/net/inet_connection_sock.h
@@ -275,11 +275,6 @@ static inline void inet_csk_reqsk_queue_add(struct sock *sk,
                                            struct sock *child)
 {
        reqsk_queue_add(&inet_csk(sk)->icsk_accept_queue, req, sk, child);
-       /* before letting lookups find us, make sure all req fields
-        * are committed to memory.
-        */
-       smp_wmb();
-       atomic_set(&req->rsk_refcnt, 1);
 }
 
 void inet_csk_reqsk_queue_hash_add(struct sock *sk, struct request_sock *req,

diff --git a/include/net/inet_sock.h b/include/net/inet_sock.h
index 6fec734..b6c3737 100644 (file)
--- a/include/net/inet_sock.h
+++ b/include/net/inet_sock.h
@@ -81,7 +81,6 @@ struct inet_request_sock {
 #define ir_cookie              req.__req_common.skc_cookie
 #define ireq_net               req.__req_common.skc_net
 #define ireq_state             req.__req_common.skc_state
-#define ireq_refcnt            req.__req_common.skc_refcnt
 #define ireq_family            req.__req_common.skc_family
 
        kmemcheck_bitfield_begin(flags);

diff --git a/include/net/request_sock.h b/include/net/request_sock.h
index 723d1cb..3fa4f82 100644 (file)
--- a/include/net/request_sock.h
+++ b/include/net/request_sock.h
@@ -77,6 +77,11 @@ reqsk_alloc(const struct request_sock_ops *ops, struct sock *sk_listener)
                req->rsk_ops = ops;
                sock_hold(sk_listener);
                req->rsk_listener = sk_listener;
+
+               /* Following is temporary. It is coupled with debugging
+                * helpers in reqsk_put() & reqsk_free()
+                */
+               atomic_set(&req->rsk_refcnt, 0);
        }
        return req;
 }
@@ -292,6 +297,12 @@ static inline void reqsk_queue_hash_req(struct request_sock_queue *queue,
        req->sk = NULL;
        req->dl_next = lopt->syn_table[hash];
 
+       /* before letting lookups find us, make sure all req fields
+        * are committed to memory and refcnt initialized.
+        */
+       smp_wmb();
+       atomic_set(&req->rsk_refcnt, 1);
+
        write_lock(&queue->syn_wait_lock);
        lopt->syn_table[hash] = req;
        write_unlock(&queue->syn_wait_lock);

diff --git a/net/ipv4/syncookies.c b/net/ipv4/syncookies.c
index 574b677..34e7554 100644 (file)
--- a/net/ipv4/syncookies.c
+++ b/net/ipv4/syncookies.c
@@ -227,11 +227,12 @@ static struct sock *get_cookie_sock(struct sock *sk, struct sk_buff *skb,
        struct sock *child;
 
        child = icsk->icsk_af_ops->syn_recv_sock(sk, skb, req, dst);
-       if (child)
+       if (child) {
+               atomic_set(&req->rsk_refcnt, 1);
                inet_csk_reqsk_queue_add(sk, req, child);
-       else
+       } else {
                reqsk_free(req);
-
+       }
        return child;
 }
 
@@ -356,7 +357,7 @@ struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb)
        ireq->opt = tcp_v4_save_options(skb);
 
        if (security_inet_conn_request(sk, skb, req)) {
-               reqsk_put(req);
+               reqsk_free(req);
                goto out;
        }
 
@@ -377,7 +378,7 @@ struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb)
        security_req_classify_flow(req, flowi4_to_flowi(&fl4));
        rt = ip_route_output_key(sock_net(sk), &fl4);
        if (IS_ERR(rt)) {
-               reqsk_put(req);
+               reqsk_free(req);
                goto out;
        }
 

diff --git a/net/ipv4/tcp_fastopen.c b/net/ipv4/tcp_fastopen.c
index 186fd39..82e375a 100644 (file)
--- a/net/ipv4/tcp_fastopen.c
+++ b/net/ipv4/tcp_fastopen.c
@@ -169,6 +169,7 @@ static bool tcp_fastopen_create_child(struct sock *sk,
        inet_csk_reset_xmit_timer(child, ICSK_TIME_RETRANS,
                                  TCP_TIMEOUT_INIT, TCP_RTO_MAX);
 
+       atomic_set(&req->rsk_refcnt, 1);
        /* Add the child socket directly into the accept queue */
        inet_csk_reqsk_queue_add(sk, req, child);
 

diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index a94ddb9..1dfbaee 100644 (file)
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -5981,10 +5981,6 @@ struct request_sock *inet_reqsk_alloc(const struct request_sock_ops *ops,
                ireq->ireq_state = TCP_NEW_SYN_RECV;
                write_pnet(&ireq->ireq_net, sock_net(sk_listener));
 
-               /* Following is temporary. It is coupled with debugging
-                * helpers in reqsk_put() & reqsk_free()
-                */
-               atomic_set(&ireq->ireq_refcnt, 0);
        }
 
        return req;

diff --git a/net/ipv6/syncookies.c b/net/ipv6/syncookies.c
index 1ef0c92..da5823e 100644 (file)
--- a/net/ipv6/syncookies.c
+++ b/net/ipv6/syncookies.c
@@ -49,11 +49,12 @@ static inline struct sock *get_cookie_sock(struct sock *sk, struct sk_buff *skb,
        struct sock *child;
 
        child = icsk->icsk_af_ops->syn_recv_sock(sk, skb, req, dst);
-       if (child)
+       if (child) {
+               atomic_set(&req->rsk_refcnt, 1);
                inet_csk_reqsk_queue_add(sk, req, child);
-       else
+       } else {
                reqsk_free(req);
-
+       }
        return child;
 }