Subject: [PATCH 5/6] gtp: add socket to pdp context

From: Andreas Schultz <[email-masked]>
Date: Mon, 30 Jan 2017 17:31:59 +0100

Having the socket present in context simplifies the sending logic.
It also fixes the invalid assumption that we have to use the same
sending socket for all client IP's on a specific gtp interface.

Signed-off-by: Andreas Schultz <[email-masked]>
---
 drivers/net/gtp.c | 72 ++++++++++++++++++++++++++++++-------------------------
 1 file changed, 39 insertions(+), 33 deletions(-)

diff --git a/drivers/net/gtp.c b/drivers/net/gtp.c
index 68c6c9b..ff00597 100644
--- a/drivers/net/gtp.c
+++ b/drivers/net/gtp.c
@@ -58,6 +58,8 @@ struct pdp_ctx {
 	struct in_addr		ms_addr_ip4;
 	struct in_addr		sgsn_addr_ip4;
 
+	struct sock		*sk;
+
 	atomic_t		tx_seq;
 	struct rcu_head		rcu_head;
 };
@@ -371,8 +373,9 @@ static void gtp_dev_uninit(struct net_device *dev)
 	free_percpu(dev->tstats);
 }
 
-static struct rtable *ip4_route_output_gtp(struct net *net, struct flowi4 *fl4,
-					   const struct sock *sk, __be32 daddr)
+static struct rtable *ip4_route_output_gtp(struct flowi4 *fl4,
+					   const struct sock *sk,
+					   __be32 daddr)
 {
 	memset(fl4, 0, sizeof(*fl4));
 	fl4->flowi4_oif		= sk->sk_bound_dev_if;
@@ -381,7 +384,7 @@ static struct rtable *ip4_route_output_gtp(struct net *net, struct flowi4 *fl4,
 	fl4->flowi4_tos		= RT_CONN_FLAGS(sk);
 	fl4->flowi4_proto	= sk->sk_protocol;
 
-	return ip_route_output_key(net, fl4);
+	return ip_route_output_key(sock_net(sk), fl4);
 }
 
 static inline void gtp0_push_header(struct sk_buff *skb, struct pdp_ctx *pctx)
@@ -470,7 +473,6 @@ static int gtp_build_skb_ip4(struct sk_buff *skb, struct net_device *dev,
 	struct rtable *rt;
 	struct flowi4 fl4;
 	struct iphdr *iph;
-	struct sock *sk;
 	__be16 df;
 	int mtu;
 
@@ -486,30 +488,7 @@ static int gtp_build_skb_ip4(struct sk_buff *skb, struct net_device *dev,
 	}
 	netdev_dbg(dev, "found PDP context %p\n", pctx);
 
-	switch (pctx->gtp_version) {
-	case GTP_V0:
-		if (gtp->sock0)
-			sk = gtp->sock0->sk;
-		else
-			sk = NULL;
-		break;
-	case GTP_V1:
-		if (gtp->sock1u)
-			sk = gtp->sock1u->sk;
-		else
-			sk = NULL;
-		break;
-	default:
-		return -ENOENT;
-	}
-
-	if (!sk) {
-		netdev_dbg(dev, "no userspace socket is available, skip\n");
-		return -ENOENT;
-	}
-
-	rt = ip4_route_output_gtp(sock_net(sk), &fl4, gtp->sock0->sk,
-				  pctx->sgsn_addr_ip4.s_addr);
+	rt = ip4_route_output_gtp(&fl4, pctx->sk, pctx->sgsn_addr_ip4.s_addr);
 	if (IS_ERR(rt)) {
 		netdev_dbg(dev, "no route to SSGN %pI4\n",
 			   &pctx->sgsn_addr_ip4.s_addr);
@@ -554,7 +533,7 @@ static int gtp_build_skb_ip4(struct sk_buff *skb, struct net_device *dev,
 		goto err_rt;
 	}
 
-	gtp_set_pktinfo_ipv4(pktinfo, sk, iph, pctx, rt, &fl4, dev);
+	gtp_set_pktinfo_ipv4(pktinfo, pctx->sk, iph, pctx, rt, &fl4, dev);
 	gtp_push_header(skb, pktinfo);
 
 	return 0;
@@ -908,7 +887,8 @@ static void ipv4_pdp_fill(struct pdp_ctx *pctx, struct genl_info *info)
 	}
 }
 
-static int ipv4_pdp_add(struct gtp_dev *gtp, struct genl_info *info)
+static int ipv4_pdp_add(struct gtp_dev *gtp, struct sock *sk,
+			struct genl_info *info)
 {
 	u32 hash_ms, hash_tid = 0;
 	struct pdp_ctx *pctx;
@@ -948,6 +928,8 @@ static int ipv4_pdp_add(struct gtp_dev *gtp, struct genl_info *info)
 	if (pctx == NULL)
 		return -ENOMEM;
 
+	sock_hold(sk);
+	pctx->sk = sk;
 	ipv4_pdp_fill(pctx, info);
 	atomic_set(&pctx->tx_seq, 0);
 
@@ -984,16 +966,26 @@ static int ipv4_pdp_add(struct gtp_dev *gtp, struct genl_info *info)
 	return 0;
 }
 
+static void pdp_context_free(struct rcu_head *head)
+{
+	struct pdp_ctx *pctx = container_of(head, struct pdp_ctx, rcu_head);
+
+	sock_put(pctx->sk);
+	kfree(pctx);
+}
+
 static void pdp_context_delete(struct pdp_ctx *pctx)
 {
 	hlist_del_rcu(&pctx->hlist_tid);
 	hlist_del_rcu(&pctx->hlist_addr);
-	kfree(pctx);
+	call_rcu(&pctx->rcu_head, pdp_context_free);
 }
 
 static int gtp_genl_new_pdp(struct sk_buff *skb, struct genl_info *info)
 {
+	unsigned int version;
 	struct gtp_dev *gtp;
+	struct socket *sock;
 	int err;
 
 	if (!info->attrs[GTPA_VERSION] ||
@@ -1002,7 +994,9 @@ static int gtp_genl_new_pdp(struct sk_buff *skb, struct genl_info *info)
 	    !info->attrs[GTPA_MS_ADDRESS])
 		return -EINVAL;
 
-	switch (nla_get_u32(info->attrs[GTPA_VERSION])) {
+	version = nla_get_u32(info->attrs[GTPA_VERSION]);
+
+	switch (version) {
 	case GTP_V0:
 		if (!info->attrs[GTPA_TID] ||
 		    !info->attrs[GTPA_FLOW])
@@ -1026,7 +1020,19 @@ static int gtp_genl_new_pdp(struct sk_buff *skb, struct genl_info *info)
 		goto out_unlock;
 	}
 
-	err = ipv4_pdp_add(gtp, info);
+	if (version == GTP_V0)
+		sock = gtp->sock0;
+	else if (version == GTP_V1)
+		sock = gtp->sock1u;
+	else
+		sock = NULL;
+
+	if (!sock || !sock->sk) {
+		err = -ENODEV;
+		goto out_unlock;
+	}
+
+	err = ipv4_pdp_add(gtp, sock->sk, info);
 
 out_unlock:
 	rcu_read_unlock();
-- 
2.10.2