Merge branch 'gro_udp_encap'

Or Gerlitz says:

====================
net: Add GRO support for UDP encapsulating protocols

This series adds GRO handlers for protocols that do UDP encapsulation, with the
intent of being able to coalesce packets which encapsulate packets belonging to
the same TCP session.

For GRO purposes, the destination UDP port takes the role of the ether type
field in the ethernet header or the next protocol in the IP header.

The UDP GRO handler will only attempt to coalesce packets whose destination
port is registered to have gro handler.

The patches done against net-next 75e4364f "net: stmmac: fix NULL pointer
dereference in stmmac_get_tx_hwtstamp"

Or.

v4 --> v5 changes:
  - followed Eric's directives to avoid using atomic get/put ops on the
    udp gro receive and complete callbacks and instead keep the rcu_read_lock
    when calling the next handler on the chain.

v3 --> v4 changes:

  - applied feedback from Tom on some micro-optimizations that save
    branches and goto directives in the udp gro logic

 - applied feedback from Eric on correct RCU programming for the
   add/remove flow of the upper protocols udp gro handlers

v2 --> v3 changes:

 - moved to use linked list to store the udp gro handlers, this solves the
   problem of consuming 512KB of memory for the handlers.

 - use a mark on the skb GRO CB data to disallow running the udp gro_receive twice
   on a packet, this solves the problem of udp encapsulated packets whose inner VM
   packet is udp and happen to carry a port which has registered offloads - and flush it.

 - invoke the udp offload protocol registration and de-registration from the vxlan driver
   in a sleepable context
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/vxlan.c

@@ -40,6 +40,7 @@
 #include <net/net_namespace.h>
 #include <net/netns/generic.h>
 #include <net/vxlan.h>
+#include <net/protocol.h>
 #if IS_ENABLED(CONFIG_IPV6)
 #include <net/ipv6.h>
 #include <net/addrconf.h>
@@ -554,13 +555,106 @@ static int vxlan_fdb_append(struct vxlan_fdb *f,
 	return 1;
 }
 
+static struct sk_buff **vxlan_gro_receive(struct sk_buff **head, struct sk_buff *skb)
+{
+	struct sk_buff *p, **pp = NULL;
+	struct vxlanhdr *vh, *vh2;
+	struct ethhdr *eh, *eh2;
+	unsigned int hlen, off_vx, off_eth;
+	const struct packet_offload *ptype;
+	__be16 type;
+	int flush = 1;
+
+	off_vx = skb_gro_offset(skb);
+	hlen = off_vx + sizeof(*vh);
+	vh   = skb_gro_header_fast(skb, off_vx);
+	if (skb_gro_header_hard(skb, hlen)) {
+		vh = skb_gro_header_slow(skb, hlen, off_vx);
+		if (unlikely(!vh))
+			goto out;
+	}
+	skb_gro_pull(skb, sizeof(struct vxlanhdr)); /* pull vxlan header */
+
+	off_eth = skb_gro_offset(skb);
+	hlen = off_eth + sizeof(*eh);
+	eh   = skb_gro_header_fast(skb, off_eth);
+	if (skb_gro_header_hard(skb, hlen)) {
+		eh = skb_gro_header_slow(skb, hlen, off_eth);
+		if (unlikely(!eh))
+			goto out;
+	}
+
+	flush = 0;
+
+	for (p = *head; p; p = p->next) {
+		if (!NAPI_GRO_CB(p)->same_flow)
+			continue;
+
+		vh2 = (struct vxlanhdr *)(p->data + off_vx);
+		eh2 = (struct ethhdr   *)(p->data + off_eth);
+		if (vh->vx_vni != vh2->vx_vni || compare_ether_header(eh, eh2)) {
+			NAPI_GRO_CB(p)->same_flow = 0;
+			continue;
+		}
+		goto found;
+	}
+
+found:
+	type = eh->h_proto;
+
+	rcu_read_lock();
+	ptype = gro_find_receive_by_type(type);
+	if (ptype == NULL) {
+		flush = 1;
+		goto out_unlock;
+	}
+
+	skb_gro_pull(skb, sizeof(*eh)); /* pull inner eth header */
+	pp = ptype->callbacks.gro_receive(head, skb);
+
+out_unlock:
+	rcu_read_unlock();
+out:
+	NAPI_GRO_CB(skb)->flush |= flush;
+
+	return pp;
+}
+
+static int vxlan_gro_complete(struct sk_buff *skb, int nhoff)
+{
+	struct ethhdr *eh;
+	struct packet_offload *ptype;
+	__be16 type;
+	int vxlan_len  = sizeof(struct vxlanhdr) + sizeof(struct ethhdr);
+	int err = -ENOSYS;
+
+	eh = (struct ethhdr *)(skb->data + nhoff + sizeof(struct vxlanhdr));
+	type = eh->h_proto;
+
+	rcu_read_lock();
+	ptype = gro_find_complete_by_type(type);
+	if (ptype != NULL)
+		err = ptype->callbacks.gro_complete(skb, nhoff + vxlan_len);
+
+	rcu_read_unlock();
+	return err;
+}
+
 /* Notify netdevs that UDP port started listening */
-static void vxlan_notify_add_rx_port(struct sock *sk)
+static void vxlan_notify_add_rx_port(struct vxlan_sock *vs)
 {
 	struct net_device *dev;
+	struct sock *sk = vs->sock->sk;
 	struct net *net = sock_net(sk);
 	sa_family_t sa_family = sk->sk_family;
 	__be16 port = inet_sk(sk)->inet_sport;
+	int err;
+
+	if (sa_family == AF_INET) {
+		err = udp_add_offload(&vs->udp_offloads);
+		if (err)
+			pr_warn("vxlan: udp_add_offload failed with status %d\n", err);
+	}
 
 	rcu_read_lock();
 	for_each_netdev_rcu(net, dev) {
@@ -572,9 +666,10 @@ static void vxlan_notify_add_rx_port(struct sock *sk)
 }
 
 /* Notify netdevs that UDP port is no more listening */
-static void vxlan_notify_del_rx_port(struct sock *sk)
+static void vxlan_notify_del_rx_port(struct vxlan_sock *vs)
 {
 	struct net_device *dev;
+	struct sock *sk = vs->sock->sk;
 	struct net *net = sock_net(sk);
 	sa_family_t sa_family = sk->sk_family;
 	__be16 port = inet_sk(sk)->inet_sport;
@@ -586,6 +681,9 @@ static void vxlan_notify_del_rx_port(struct sock *sk)
 							    port);
 	}
 	rcu_read_unlock();
+
+	if (sa_family == AF_INET)
+		udp_del_offload(&vs->udp_offloads);
 }
 
 /* Add new entry to forwarding table -- assumes lock held */
@@ -963,7 +1061,7 @@ void vxlan_sock_release(struct vxlan_sock *vs)
 	spin_lock(&vn->sock_lock);
 	hlist_del_rcu(&vs->hlist);
 	rcu_assign_sk_user_data(vs->sock->sk, NULL);
-	vxlan_notify_del_rx_port(sk);
+	vxlan_notify_del_rx_port(vs);
 	spin_unlock(&vn->sock_lock);
 
 	queue_work(vxlan_wq, &vs->del_work);
@@ -1124,8 +1222,8 @@ static void vxlan_rcv(struct vxlan_sock *vs,
 	 * leave the CHECKSUM_UNNECESSARY, the device checksummed it
 	 * for us. Otherwise force the upper layers to verify it.
 	 */
-	if (skb->ip_summed != CHECKSUM_UNNECESSARY || !skb->encapsulation ||
-	    !(vxlan->dev->features & NETIF_F_RXCSUM))
+	if ((skb->ip_summed != CHECKSUM_UNNECESSARY && skb->ip_summed != CHECKSUM_PARTIAL) ||
+	    !skb->encapsulation || !(vxlan->dev->features & NETIF_F_RXCSUM))
 		skb->ip_summed = CHECKSUM_NONE;
 
 	skb->encapsulation = 0;
@@ -2303,7 +2401,7 @@ static struct vxlan_sock *vxlan_socket_create(struct net *net, __be16 port,
 	struct sock *sk;
 	unsigned int h;
 
-	vs = kmalloc(sizeof(*vs), GFP_KERNEL);
+	vs = kzalloc(sizeof(*vs), GFP_KERNEL);
 	if (!vs)
 		return ERR_PTR(-ENOMEM);
 
@@ -2328,9 +2426,14 @@ static struct vxlan_sock *vxlan_socket_create(struct net *net, __be16 port,
 	vs->data = data;
 	rcu_assign_sk_user_data(vs->sock->sk, vs);
 
+	/* Initialize the vxlan udp offloads structure */
+	vs->udp_offloads.port = port;
+	vs->udp_offloads.callbacks.gro_receive  = vxlan_gro_receive;
+	vs->udp_offloads.callbacks.gro_complete = vxlan_gro_complete;
+
 	spin_lock(&vn->sock_lock);
 	hlist_add_head_rcu(&vs->hlist, vs_head(net, port));
-	vxlan_notify_add_rx_port(sk);
+	vxlan_notify_add_rx_port(vs);
 	spin_unlock(&vn->sock_lock);
 
 	/* Mark socket as an encapsulation socket. */

include/linux/netdevice.h

@@ -1675,7 +1675,10 @@ struct napi_gro_cb {
 	unsigned long age;
 
 	/* Used in ipv6_gro_receive() */
-	int	proto;
+	u16	proto;
+
+	/* Used in udp_gro_receive */
+	u16	udp_mark;
 
 	/* used to support CHECKSUM_COMPLETE for tunneling protocols */
 	__wsum	csum;
@@ -1714,6 +1717,11 @@ struct packet_offload {
 	struct list_head	 list;
 };
 
+struct udp_offload {
+	__be16			 port;
+	struct offload_callbacks callbacks;
+};
+
 /* often modified stats are per cpu, other are shared (netdev->stats) */
 struct pcpu_sw_netstats {
 	u64     rx_packets;

include/net/protocol.h

@@ -108,6 +108,9 @@ int inet_del_offload(const struct net_offload *prot, unsigned char num);
 void inet_register_protosw(struct inet_protosw *p);
 void inet_unregister_protosw(struct inet_protosw *p);
 
+int  udp_add_offload(struct udp_offload *prot);
+void udp_del_offload(struct udp_offload *prot);
+
 #if IS_ENABLED(CONFIG_IPV6)
 int inet6_add_protocol(const struct inet6_protocol *prot, unsigned char num);
 int inet6_del_protocol(const struct inet6_protocol *prot, unsigned char num);

include/net/vxlan.h

@@ -21,6 +21,7 @@ struct vxlan_sock {
 	struct rcu_head	  rcu;
 	struct hlist_head vni_list[VNI_HASH_SIZE];
 	atomic_t	  refcnt;
+	struct udp_offload udp_offloads;
 };
 
 struct vxlan_sock *vxlan_sock_add(struct net *net, __be16 port,

net/core/dev.c

@@ -3893,6 +3893,7 @@ static enum gro_result dev_gro_receive(struct napi_struct *napi, struct sk_buff
 		NAPI_GRO_CB(skb)->same_flow = 0;
 		NAPI_GRO_CB(skb)->flush = 0;
 		NAPI_GRO_CB(skb)->free = 0;
+		NAPI_GRO_CB(skb)->udp_mark = 0;
 
 		pp = ptype->callbacks.gro_receive(&napi->gro_list, skb);
 		break;
@@ -3983,6 +3984,7 @@ struct packet_offload *gro_find_receive_by_type(__be16 type)
 	}
 	return NULL;
 }
+EXPORT_SYMBOL(gro_find_receive_by_type);
 
 struct packet_offload *gro_find_complete_by_type(__be16 type)
 {
@@ -3996,6 +3998,7 @@ struct packet_offload *gro_find_complete_by_type(__be16 type)
 	}
 	return NULL;
 }
+EXPORT_SYMBOL(gro_find_complete_by_type);
 
 static gro_result_t napi_skb_finish(gro_result_t ret, struct sk_buff *skb)
 {

net/ipv4/udp_offload.c

@@ -14,6 +14,15 @@
 #include <net/udp.h>
 #include <net/protocol.h>
 
+static DEFINE_SPINLOCK(udp_offload_lock);
+static struct udp_offload_priv *udp_offload_base __read_mostly;
+
+struct udp_offload_priv {
+	struct udp_offload	*offload;
+	struct rcu_head		rcu;
+	struct udp_offload_priv __rcu *next;
+};
+
 static int udp4_ufo_send_check(struct sk_buff *skb)
 {
 	if (!pskb_may_pull(skb, sizeof(struct udphdr)))
@@ -89,10 +98,144 @@ static struct sk_buff *udp4_ufo_fragment(struct sk_buff *skb,
 	return segs;
 }
 
+int udp_add_offload(struct udp_offload *uo)
+{
+	struct udp_offload_priv **head = &udp_offload_base;
+	struct udp_offload_priv *new_offload = kzalloc(sizeof(*new_offload), GFP_KERNEL);
+
+	if (!new_offload)
+		return -ENOMEM;
+
+	new_offload->offload = uo;
+
+	spin_lock(&udp_offload_lock);
+	rcu_assign_pointer(new_offload->next, rcu_dereference(*head));
+	rcu_assign_pointer(*head, rcu_dereference(new_offload));
+	spin_unlock(&udp_offload_lock);
+
+	return 0;
+}
+EXPORT_SYMBOL(udp_add_offload);
+
+static void udp_offload_free_routine(struct rcu_head *head)
+{
+	struct udp_offload_priv *ou_priv = container_of(head, struct udp_offload_priv, rcu);
+	kfree(ou_priv);
+}
+
+void udp_del_offload(struct udp_offload *uo)
+{
+	struct udp_offload_priv __rcu **head = &udp_offload_base;
+	struct udp_offload_priv *uo_priv;
+
+	spin_lock(&udp_offload_lock);
+
+	uo_priv = rcu_dereference(*head);
+	for (; uo_priv != NULL;
+		uo_priv = rcu_dereference(*head)) {
+
+		if (uo_priv->offload == uo) {
+			rcu_assign_pointer(*head, rcu_dereference(uo_priv->next));
+			goto unlock;
+		}
+		head = &uo_priv->next;
+	}
+	pr_warn("udp_del_offload: didn't find offload for port %d\n", htons(uo->port));
+unlock:
+	spin_unlock(&udp_offload_lock);
+	if (uo_priv != NULL)
+		call_rcu(&uo_priv->rcu, udp_offload_free_routine);
+}
+EXPORT_SYMBOL(udp_del_offload);
+
+static struct sk_buff **udp_gro_receive(struct sk_buff **head, struct sk_buff *skb)
+{
+	struct udp_offload_priv *uo_priv;
+	struct sk_buff *p, **pp = NULL;
+	struct udphdr *uh, *uh2;
+	unsigned int hlen, off;
+	int flush = 1;
+
+	if (NAPI_GRO_CB(skb)->udp_mark ||
+	    (!skb->encapsulation && skb->ip_summed != CHECKSUM_COMPLETE))
+		goto out;
+
+	/* mark that this skb passed once through the udp gro layer */
+	NAPI_GRO_CB(skb)->udp_mark = 1;
+
+	off  = skb_gro_offset(skb);
+	hlen = off + sizeof(*uh);
+	uh   = skb_gro_header_fast(skb, off);
+	if (skb_gro_header_hard(skb, hlen)) {
+		uh = skb_gro_header_slow(skb, hlen, off);
+		if (unlikely(!uh))
+			goto out;
+	}
+
+	rcu_read_lock();
+	uo_priv = rcu_dereference(udp_offload_base);
+	for (; uo_priv != NULL; uo_priv = rcu_dereference(uo_priv->next)) {
+		if (uo_priv->offload->port == uh->dest &&
+		    uo_priv->offload->callbacks.gro_receive)
+			goto unflush;
+	}
+	goto out_unlock;
+
+unflush:
+	flush = 0;
+
+	for (p = *head; p; p = p->next) {
+		if (!NAPI_GRO_CB(p)->same_flow)
+			continue;
+
+		uh2 = (struct udphdr   *)(p->data + off);
+		if ((*(u32 *)&uh->source != *(u32 *)&uh2->source)) {
+			NAPI_GRO_CB(p)->same_flow = 0;
+			continue;
+		}
+	}
+
+	skb_gro_pull(skb, sizeof(struct udphdr)); /* pull encapsulating udp header */
+	pp = uo_priv->offload->callbacks.gro_receive(head, skb);
+
+out_unlock:
+	rcu_read_unlock();
+out:
+	NAPI_GRO_CB(skb)->flush |= flush;
+	return pp;
+}
+
+static int udp_gro_complete(struct sk_buff *skb, int nhoff)
+{
+	struct udp_offload_priv *uo_priv;
+	__be16 newlen = htons(skb->len - nhoff);
+	struct udphdr *uh = (struct udphdr *)(skb->data + nhoff);
+	int err = -ENOSYS;
+
+	uh->len = newlen;
+
+	rcu_read_lock();
+
+	uo_priv = rcu_dereference(udp_offload_base);
+	for (; uo_priv != NULL; uo_priv = rcu_dereference(uo_priv->next)) {
+		if (uo_priv->offload->port == uh->dest &&
+		    uo_priv->offload->callbacks.gro_complete)
+			break;
+	}
+
+	if (uo_priv != NULL)
+		err = uo_priv->offload->callbacks.gro_complete(skb, nhoff + sizeof(struct udphdr));
+
+	rcu_read_unlock();
+	return err;
+}
+
 static const struct net_offload udpv4_offload = {
 	.callbacks = {
 		.gso_send_check = udp4_ufo_send_check,
 		.gso_segment = udp4_ufo_fragment,
+		.gro_receive  =	udp_gro_receive,
+		.gro_complete =	udp_gro_complete,
 	},
 };