net: ipv4: listified version of ip_rcv

Also involved adding a way to run a netfilter hook over a list of packets.
 Rather than attempting to make netfilter know about lists (which would be
 a major project in itself) we just let it call the regular okfn (in this
 case ip_rcv_finish()) for any packets it steals, and have it give us back
 a list of packets it's synchronously accepted (which normally NF_HOOK
 would automatically call okfn() on, but we want to be able to potentially
 pass the list to a listified version of okfn().)
The netfilter hooks themselves are indirect calls that still happen per-
 packet (see nf_hook_entry_hookfn()), but again, changing that can be left
 for future work.

There is potential for out-of-order receives if the netfilter hook ends up
 synchronously stealing packets, as they will be processed before any
 accepts earlier in the list.  However, it was already possible for an
 asynchronous accept to cause out-of-order receives, so presumably this is
 considered OK.

Signed-off-by: Edward Cree <ecree@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 27 insertions, 0 deletions

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index f67258f057ca..c1ef749b6f9f 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -2297,6 +2297,9 @@ struct packet_type {
 					 struct net_device *,
 					 struct packet_type *,
 					 struct net_device *);
+	void			(*list_func) (struct list_head *,
+					      struct packet_type *,
+					      struct net_device *);
 	bool			(*id_match)(struct packet_type *ptype,
 					    struct sock *sk);
 	void			*af_packet_priv;
diff --git a/include/linux/netfilter.h b/include/linux/netfilter.h
index dd2052f0efb7..5a5e0a2ab2a3 100644
--- a/include/linux/netfilter.h
+++ b/include/linux/netfilter.h
@@ -288,6 +288,20 @@ NF_HOOK(uint8_t pf, unsigned int hook, struct net *net, struct sock *sk, struct
 	return ret;
 }
 
+static inline void
+NF_HOOK_LIST(uint8_t pf, unsigned int hook, struct net *net, struct sock *sk,
+	     struct list_head *head, struct net_device *in, struct net_device *out,
+	     int (*okfn)(struct net *, struct sock *, struct sk_buff *))
+{
+	struct sk_buff *skb, *next;
+
+	list_for_each_entry_safe(skb, next, head, list) {
+		int ret = nf_hook(pf, hook, net, sk, skb, in, out, okfn);
+		if (ret != 1)
+			list_del(&skb->list);
+	}
+}
+
 /* Call setsockopt() */
 int nf_setsockopt(struct sock *sk, u_int8_t pf, int optval, char __user *opt,
 		  unsigned int len);
@@ -369,6 +383,14 @@ NF_HOOK(uint8_t pf, unsigned int hook, struct net *net, struct sock *sk,
 	return okfn(net, sk, skb);
 }
 
+static inline void
+NF_HOOK_LIST(uint8_t pf, unsigned int hook, struct net *net, struct sock *sk,
+	     struct list_head *head, struct net_device *in, struct net_device *out,
+	     int (*okfn)(struct net *, struct sock *, struct sk_buff *))
+{
+	/* nothing to do */
+}
+
 static inline int nf_hook(u_int8_t pf, unsigned int hook, struct net *net,
 			  struct sock *sk, struct sk_buff *skb,
 			  struct net_device *indev, struct net_device *outdev,
diff --git a/include/net/ip.h b/include/net/ip.h
index 09da79d8ceea..99d1b835d2aa 100644
--- a/include/net/ip.h
+++ b/include/net/ip.h
@@ -138,6 +138,8 @@ int ip_build_and_send_pkt(struct sk_buff *skb, const struct sock *sk,
 			  struct ip_options_rcu *opt);
 int ip_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type *pt,
 	   struct net_device *orig_dev);
+void ip_list_rcv(struct list_head *head, struct packet_type *pt,
+		 struct net_device *orig_dev);
 int ip_local_deliver(struct sk_buff *skb);
 int ip_mr_input(struct sk_buff *skb);
 int ip_output(struct net *net, struct sock *sk, struct sk_buff *skb);