[PATCH 03/12] gtp: add socket destroy handler

[Andreas Schultz]

  pts rule name              description
 ---- ---------------------- --------------------------------------------------
  2.7 DNS_FROM_AHBL_RHSBL    RBL: Envelope sender listed in dnsbl.ahbl.org
 -0.0 SPF_PASS               SPF: sender matches SPF record
 -1.9 BAYES_00               BODY: Bayes spam probability is 0 to 1%
                             [score: 0.0000]
Status: O
X-Status: F
Content-Length: 2487

Add a socket destroy handler and use it to detach and release all
resources from an UDP socket.

Do not longer pin the socket with a reference. This together with
the release handler allows user space to close the socket from
underneath us. The destroy handler will handle the rest.

Signed-off-by: Andreas Schultz <aschu...@tpip.net>
---
 gtp.c | 34 +++++++++++++++++++++++++++-------
 1 file changed, 27 insertions(+), 7 deletions(-)

diff --git a/gtp.c b/gtp.c
index cd41aea..280e93b 100644
--- a/gtp.c
+++ b/gtp.c
@@ -80,6 +80,8 @@ struct gtp_net {
        struct list_head gtp_instance_list;
 };

+static void gtp_encap_disable(struct gtp_instance *gti);
+
 static inline u32 gtp0_hashfn(u64 tid)
 {
        u32 *tid32 = (u32 *) &tid;
@@ -317,6 +319,16 @@ out_rcu:
        return ret;
 }

+static void gtp_udp_encap_destroy(struct sock *sk)
+{
+       struct gtp_instance *gti = sk_to_gti(sk);
+
+       if (gti) {
+               gtp_encap_disable(gti);
+               sock_put(sk);
+       }
+}
+
 /* UDP encapsulation receive handler. See net/ipv4/udp.c.
  * Return codes: 0: success, <0: error, >0: passed up to userspace UDP.
  */
@@ -401,8 +413,6 @@ static int gtp_dev_init(struct net_device *dev)
        return 0;
 }

-static void gtp_encap_disable(struct gtp_instance *gti);
-
 static void gtp_dev_uninit(struct net_device *dev)
 {
        struct gtp_instance *gti = netdev_priv(dev);
@@ -944,15 +954,18 @@ static int gtp_encap_enable(struct net_device *dev, 
struct gtp_instance *gti,
        sk = gti->sock0->sk;
        udp_sk(sk)->encap_type = UDP_ENCAP_GTP0;
        udp_sk(sk)->encap_rcv = gtp_udp_encap_recv;
+       udp_sk(sk)->encap_destroy = gtp_udp_encap_destroy;
        sk->sk_user_data = gti;
        udp_encap_enable();

        sk = gti->sock1u->sk;
        udp_sk(sk)->encap_type = UDP_ENCAP_GTP1U;
        udp_sk(sk)->encap_rcv = gtp_udp_encap_recv;
+       udp_sk(sk)->encap_destroy = gtp_udp_encap_destroy;
        sk->sk_user_data = gti;

-       return 0;
+       err = 0;
+
 err2:
        sockfd_put(sock1u);
 err1:
@@ -962,10 +975,17 @@ err1:

 static void gtp_encap_disable(struct gtp_instance *gti)
 {
-       if (gti->sock1u)
-               sockfd_put(gti->sock1u);
-       if (gti->sock0)
-               sockfd_put(gti->sock0);
+       if (gti->sock0 && gti->sock0->sk) {
+               udp_sk(gti->sock0->sk)->encap_type = 0;
+               rcu_assign_sk_user_data(gti->sock0->sk, NULL);
+       }
+       if (gti->sock1u && gti->sock1u->sk) {
+               udp_sk(gti->sock1u->sk)->encap_type = 0;
+               rcu_assign_sk_user_data(gti->sock1u->sk, NULL);
+       }
+
+       gti->sock0 = NULL;
+       gti->sock1u = NULL;
 }

 static struct net_device *gtp_find_dev(struct net *net, int ifindex)
-- 
2.7.4