Phonet: resource routing backend

When both destination device and object are nul, Phonet routes the
packet according to the resource field. In fact, this is the most
common pattern when sending Phonet "request" packets. In this case,
the packet is delivered to whichever endpoint (socket) has
registered the resource.

This adds a new table so that Linux processes can register their
Phonet sockets to Phonet resources, if they have adequate privileges.

(Namespace support is not implemented at the moment.)

Signed-off-by: Rémi Denis-Courmont <remi.denis-courmont@nokia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/net/phonet/phonet.h b/include/net/phonet/phonet.h
index 7b114079a51bb18327c96005cd7c6a9864bc4a25..d5df797f954048b458071b544d8e5de94785b4e6 100644 (file)
--- a/include/net/phonet/phonet.h
+++ b/include/net/phonet/phonet.h
@@ -54,6 +54,11 @@ void pn_sock_hash(struct sock *sk);
 void pn_sock_unhash(struct sock *sk);
 int pn_sock_get_port(struct sock *sk, unsigned short sport);
 
+struct sock *pn_find_sock_by_res(struct net *net, u8 res);
+int pn_sock_bind_res(struct sock *sock, u8 res);
+int pn_sock_unbind_res(struct sock *sk, u8 res);
+void pn_sock_unbind_all_res(struct sock *sk);
+
 int pn_skb_send(struct sock *sk, struct sk_buff *skb,
                const struct sockaddr_pn *target);
 

diff --git a/net/phonet/socket.c b/net/phonet/socket.c
index 7c91f739f13848e63e45a174c35c881301a40a03..4c29a23e900752f100bcbcbafc4764328eb0d430 100644 (file)
--- a/net/phonet/socket.c
+++ b/net/phonet/socket.c
@@ -565,3 +565,91 @@ const struct file_operations pn_sock_seq_fops = {
        .release = seq_release_net,
 };
 #endif
+
+static struct  {
+       struct sock *sk[256];
+} pnres;
+
+/*
+ * Find and hold socket based on resource.
+ */
+struct sock *pn_find_sock_by_res(struct net *net, u8 res)
+{
+       struct sock *sk;
+
+       if (!net_eq(net, &init_net))
+               return NULL;
+
+       rcu_read_lock();
+       sk = rcu_dereference(pnres.sk[res]);
+       if (sk)
+               sock_hold(sk);
+       rcu_read_unlock();
+       return sk;
+}
+
+static DEFINE_MUTEX(resource_mutex);
+
+int pn_sock_bind_res(struct sock *sk, u8 res)
+{
+       int ret = -EADDRINUSE;
+
+       if (!net_eq(sock_net(sk), &init_net))
+               return -ENOIOCTLCMD;
+       if (!capable(CAP_SYS_ADMIN))
+               return -EPERM;
+       if (pn_socket_autobind(sk->sk_socket))
+               return -EAGAIN;
+
+       mutex_lock(&resource_mutex);
+       if (pnres.sk[res] == NULL) {
+               sock_hold(sk);
+               rcu_assign_pointer(pnres.sk[res], sk);
+               ret = 0;
+       }
+       mutex_unlock(&resource_mutex);
+       return ret;
+}
+
+int pn_sock_unbind_res(struct sock *sk, u8 res)
+{
+       int ret = -ENOENT;
+
+       if (!capable(CAP_SYS_ADMIN))
+               return -EPERM;
+
+       mutex_lock(&resource_mutex);
+       if (pnres.sk[res] == sk) {
+               rcu_assign_pointer(pnres.sk[res], NULL);
+               ret = 0;
+       }
+       mutex_unlock(&resource_mutex);
+
+       if (ret == 0) {
+               synchronize_rcu();
+               sock_put(sk);
+       }
+       return ret;
+}
+
+void pn_sock_unbind_all_res(struct sock *sk)
+{
+       unsigned res, match = 0;
+
+       mutex_lock(&resource_mutex);
+       for (res = 0; res < 256; res++) {
+               if (pnres.sk[res] == sk) {
+                       rcu_assign_pointer(pnres.sk[res], NULL);
+                       match++;
+               }
+       }
+       mutex_unlock(&resource_mutex);
+
+       if (match == 0)
+               return;
+       synchronize_rcu();
+       while (match > 0) {
+               sock_put(sk);
+               match--;
+       }
+}