Create separate UDP receive functions for GTP version 0 and version 1.
Set encap_rcv appropriately when configuring a socket.

Signed-off-by: Tom Herbert <t...@quantonium.net>
---
 drivers/net/gtp.c | 100 ++++++++++++++++++++++++++----------------------------
 1 file changed, 49 insertions(+), 51 deletions(-)

diff --git a/drivers/net/gtp.c b/drivers/net/gtp.c
index 00e5ea5cb935..a6e2e0a1f424 100644
--- a/drivers/net/gtp.c
+++ b/drivers/net/gtp.c
@@ -225,14 +225,20 @@ static int gtp_rx(struct pdp_ctx *pctx, struct sk_buff 
*skb,
        return 0;
 }
 
-/* 1 means pass up to the stack, -1 means drop and 0 means decapsulated. */
-static int gtp0_udp_encap_recv(struct gtp_dev *gtp, struct sk_buff *skb)
+/* UDP encapsulation receive handler for GTPv0-U . See net/ipv4/udp.c.
+ * Return codes: 0: success, <0: error, >0: pass up to userspace UDP socket.
+ */
+static int gtp0_udp_encap_recv(struct sock *sk, struct sk_buff *skb)
 {
+       struct gtp_dev *gtp = rcu_dereference_sk_user_data(sk);
        unsigned int hdrlen = sizeof(struct udphdr) +
                              sizeof(struct gtp0_header);
        struct gtp0_header *gtp0;
        struct pdp_ctx *pctx;
 
+       if (!gtp)
+               goto pass;
+
        if (!pskb_may_pull(skb, hdrlen))
                goto drop;
 
@@ -244,26 +250,41 @@ static int gtp0_udp_encap_recv(struct gtp_dev *gtp, 
struct sk_buff *skb)
        if (gtp0->type != GTP_TPDU)
                goto pass;
 
+       netdev_dbg(gtp->dev, "received GTP0 packet\n");
+
        pctx = gtp0_pdp_find(gtp, be64_to_cpu(gtp0->tid));
        if (!pctx) {
                netdev_dbg(gtp->dev, "No PDP ctx to decap skb=%p\n", skb);
                goto pass;
        }
 
-       return gtp_rx(pctx, skb, hdrlen, gtp->role);
+       if (!gtp_rx(pctx, skb, hdrlen, gtp->role)) {
+               /* Successfully received */
+               return 0;
+       }
+
 drop:
-       return -1;
+       kfree_skb(skb);
+       return 0;
+
 pass:
        return 1;
 }
 
-static int gtp1u_udp_encap_recv(struct gtp_dev *gtp, struct sk_buff *skb)
+/* UDP encapsulation receive handler for GTPv0-U . See net/ipv4/udp.c.
+ * Return codes: 0: success, <0: error, >0: pass up to userspace UDP socket.
+ */
+static int gtp1u_udp_encap_recv(struct sock *sk, struct sk_buff *skb)
 {
+       struct gtp_dev *gtp = rcu_dereference_sk_user_data(sk);
        unsigned int hdrlen = sizeof(struct udphdr) +
                              sizeof(struct gtp1_header);
        struct gtp1_header *gtp1;
        struct pdp_ctx *pctx;
 
+       if (!gtp)
+               goto pass;
+
        if (!pskb_may_pull(skb, hdrlen))
                goto drop;
 
@@ -275,6 +296,8 @@ static int gtp1u_udp_encap_recv(struct gtp_dev *gtp, struct 
sk_buff *skb)
        if (gtp1->type != GTP_TPDU)
                goto pass;
 
+       netdev_dbg(gtp->dev, "received GTP1 packet\n");
+
        /* From 29.060: "This field shall be present if and only if any one or
         * more of the S, PN and E flags are set.".
         *
@@ -296,9 +319,15 @@ static int gtp1u_udp_encap_recv(struct gtp_dev *gtp, 
struct sk_buff *skb)
                goto drop;
        }
 
-       return gtp_rx(pctx, skb, hdrlen, gtp->role);
+       if (!gtp_rx(pctx, skb, hdrlen, gtp->role)) {
+               /* Successfully received */
+               return 0;
+       }
+
 drop:
-       return -1;
+       kfree_skb(skb);
+       return 0;
+
 pass:
        return 1;
 }
@@ -329,49 +358,6 @@ static void gtp_encap_disable(struct gtp_dev *gtp)
        gtp_encap_disable_sock(gtp->sk1u);
 }
 
-/* UDP encapsulation receive handler. See net/ipv4/udp.c.
- * Return codes: 0: success, <0: error, >0: pass up to userspace UDP socket.
- */
-static int gtp_encap_recv(struct sock *sk, struct sk_buff *skb)
-{
-       struct gtp_dev *gtp;
-       int ret = 0;
-
-       gtp = rcu_dereference_sk_user_data(sk);
-       if (!gtp)
-               return 1;
-
-       netdev_dbg(gtp->dev, "encap_recv sk=%p\n", sk);
-
-       switch (udp_sk(sk)->encap_type) {
-       case UDP_ENCAP_GTP0:
-               netdev_dbg(gtp->dev, "received GTP0 packet\n");
-               ret = gtp0_udp_encap_recv(gtp, skb);
-               break;
-       case UDP_ENCAP_GTP1U:
-               netdev_dbg(gtp->dev, "received GTP1U packet\n");
-               ret = gtp1u_udp_encap_recv(gtp, skb);
-               break;
-       default:
-               ret = -1; /* Shouldn't happen. */
-       }
-
-       switch (ret) {
-       case 1:
-               netdev_dbg(gtp->dev, "pass up to the process\n");
-               break;
-       case 0:
-               break;
-       case -1:
-               netdev_dbg(gtp->dev, "GTP packet has been dropped\n");
-               kfree_skb(skb);
-               ret = 0;
-               break;
-       }
-
-       return ret;
-}
-
 static int gtp_dev_init(struct net_device *dev)
 {
        struct gtp_dev *gtp = netdev_priv(dev);
@@ -824,9 +810,21 @@ static struct sock *gtp_encap_enable_socket(int fd, int 
type,
        sk = sock->sk;
        sock_hold(sk);
 
+       switch (type) {
+       case UDP_ENCAP_GTP0:
+               tuncfg.encap_rcv = gtp0_udp_encap_recv;
+               break;
+       case UDP_ENCAP_GTP1U:
+               tuncfg.encap_rcv = gtp1u_udp_encap_recv;
+               break;
+       default:
+               pr_debug("Unknown encap type %u\n", type);
+               sk = ERR_PTR(-EINVAL);
+               goto out_sock;
+       }
+
        tuncfg.sk_user_data = gtp;
        tuncfg.encap_type = type;
-       tuncfg.encap_rcv = gtp_encap_recv;
        tuncfg.encap_destroy = gtp_encap_destroy;
 
        setup_udp_tunnel_sock(sock_net(sock->sk), sock, &tuncfg);
-- 
2.11.0

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