rxrpc: Fix potential call vs socket/net destruction race

rxrpc_call structs don't pin sockets or network namespaces, but may attempt
to access both after their refcount reaches 0 so that they can detach
themselves from the network namespace.  However, there's no guarantee that
the socket still exists at this point (so sock_net(&call->socket->sk) may
be invalid) and the namespace may have gone away if the call isn't pinning
a peer.

Fix this by (a) carrying a net pointer in the rxrpc_call struct and (b)
waiting for all calls to be destroyed when the network namespace goes away.

This was detected by checker:

net/rxrpc/call_object.c:634:57: warning: incorrect type in argument 1 (different address spaces)
net/rxrpc/call_object.c:634:57:    expected struct sock const *sk
net/rxrpc/call_object.c:634:57:    got struct sock [noderef] <asn:4>*<noident>

Fixes: 2baec2c3f854 ("rxrpc: Support network namespacing")
Signed-off-by: David Howells <dhowells@redhat.com>

diff --git a/net/rxrpc/ar-internal.h b/net/rxrpc/ar-internal.h
index 8a348e0..2a2b0fd 100644 (file)
--- a/net/rxrpc/ar-internal.h
+++ b/net/rxrpc/ar-internal.h
@@ -75,6 +75,7 @@ struct rxrpc_net {
        u32                     epoch;          /* Local epoch for detecting local-end reset */
        struct list_head        calls;          /* List of calls active in this namespace */
        rwlock_t                call_lock;      /* Lock for ->calls */
+       atomic_t                nr_calls;       /* Count of allocated calls */
 
        struct list_head        conn_proc_list; /* List of conns in this namespace for proc */
        struct list_head        service_conns;  /* Service conns in this namespace */
@@ -528,6 +529,7 @@ struct rxrpc_call {
        struct rxrpc_connection *conn;          /* connection carrying call */
        struct rxrpc_peer       *peer;          /* Peer record for remote address */
        struct rxrpc_sock __rcu *socket;        /* socket responsible */
+       struct rxrpc_net        *rxnet;         /* Network namespace to which call belongs */
        struct mutex            user_mutex;     /* User access mutex */
        unsigned long           ack_at;         /* When deferred ACK needs to happen */
        unsigned long           ack_lost_at;    /* When ACK is figured as lost */

diff --git a/net/rxrpc/call_accept.c b/net/rxrpc/call_accept.c
index 4ce24c0..4935450 100644 (file)
--- a/net/rxrpc/call_accept.c
+++ b/net/rxrpc/call_accept.c
@@ -138,6 +138,7 @@ static int rxrpc_service_prealloc_one(struct rxrpc_sock *rx,
 
        write_unlock(&rx->call_lock);
 
+       rxnet = call->rxnet;
        write_lock(&rxnet->call_lock);
        list_add_tail(&call->link, &rxnet->calls);
        write_unlock(&rxnet->call_lock);

diff --git a/net/rxrpc/call_object.c b/net/rxrpc/call_object.c
index 85b12c4..f721c2b 100644 (file)
--- a/net/rxrpc/call_object.c
+++ b/net/rxrpc/call_object.c
@@ -103,6 +103,7 @@ struct rxrpc_call *rxrpc_alloc_call(struct rxrpc_sock *rx, gfp_t gfp,
                                    unsigned int debug_id)
 {
        struct rxrpc_call *call;
+       struct rxrpc_net *rxnet = rxrpc_net(sock_net(&rx->sk));
 
        call = kmem_cache_zalloc(rxrpc_call_jar, gfp);
        if (!call)
@@ -153,6 +154,9 @@ struct rxrpc_call *rxrpc_alloc_call(struct rxrpc_sock *rx, gfp_t gfp,
 
        call->cong_cwnd = 2;
        call->cong_ssthresh = RXRPC_RXTX_BUFF_SIZE - 1;
+
+       call->rxnet = rxnet;
+       atomic_inc(&rxnet->nr_calls);
        return call;
 
 nomem_2:
@@ -222,7 +226,7 @@ struct rxrpc_call *rxrpc_new_client_call(struct rxrpc_sock *rx,
        __acquires(&call->user_mutex)
 {
        struct rxrpc_call *call, *xcall;
-       struct rxrpc_net *rxnet = rxrpc_net(sock_net(&rx->sk));
+       struct rxrpc_net *rxnet;
        struct rb_node *parent, **pp;
        const void *here = __builtin_return_address(0);
        int ret;
@@ -272,6 +276,7 @@ struct rxrpc_call *rxrpc_new_client_call(struct rxrpc_sock *rx,
 
        write_unlock(&rx->call_lock);
 
+       rxnet = call->rxnet;
        write_lock(&rxnet->call_lock);
        list_add_tail(&call->link, &rxnet->calls);
        write_unlock(&rxnet->call_lock);
@@ -617,7 +622,7 @@ void rxrpc_release_calls_on_socket(struct rxrpc_sock *rx)
  */
 void rxrpc_put_call(struct rxrpc_call *call, enum rxrpc_call_trace op)
 {
-       struct rxrpc_net *rxnet;
+       struct rxrpc_net *rxnet = call->rxnet;
        const void *here = __builtin_return_address(0);
        int n;
 
@@ -631,7 +636,6 @@ void rxrpc_put_call(struct rxrpc_call *call, enum rxrpc_call_trace op)
                ASSERTCMP(call->state, ==, RXRPC_CALL_COMPLETE);
 
                if (!list_empty(&call->link)) {
-                       rxnet = rxrpc_net(sock_net(&call->socket->sk));
                        write_lock(&rxnet->call_lock);
                        list_del_init(&call->link);
                        write_unlock(&rxnet->call_lock);
@@ -647,11 +651,14 @@ void rxrpc_put_call(struct rxrpc_call *call, enum rxrpc_call_trace op)
 static void rxrpc_rcu_destroy_call(struct rcu_head *rcu)
 {
        struct rxrpc_call *call = container_of(rcu, struct rxrpc_call, rcu);
+       struct rxrpc_net *rxnet = call->rxnet;
 
        rxrpc_put_peer(call->peer);
        kfree(call->rxtx_buffer);
        kfree(call->rxtx_annotations);
        kmem_cache_free(rxrpc_call_jar, call);
+       if (atomic_dec_and_test(&rxnet->nr_calls))
+               wake_up_atomic_t(&rxnet->nr_calls);
 }
 
 /*
@@ -716,4 +723,7 @@ void rxrpc_destroy_all_calls(struct rxrpc_net *rxnet)
        }
 
        write_unlock(&rxnet->call_lock);
+
+       atomic_dec(&rxnet->nr_calls);
+       wait_on_atomic_t(&rxnet->nr_calls, atomic_t_wait, TASK_UNINTERRUPTIBLE);
 }

diff --git a/net/rxrpc/net_ns.c b/net/rxrpc/net_ns.c
index 66baf2b..101019b 100644 (file)
--- a/net/rxrpc/net_ns.c
+++ b/net/rxrpc/net_ns.c
@@ -55,6 +55,7 @@ static __net_init int rxrpc_init_net(struct net *net)
 
        INIT_LIST_HEAD(&rxnet->calls);
        rwlock_init(&rxnet->call_lock);
+       atomic_set(&rxnet->nr_calls, 1);
 
        INIT_LIST_HEAD(&rxnet->conn_proc_list);
        INIT_LIST_HEAD(&rxnet->service_conns);