net: ipv6: Add IPv6 support to the ping socket.

[backport of net-next 6d0bfe22611602f36617bc7aa2ffa1bbb2f54c67]

This adds the ability to send ICMPv6 echo requests without a
raw socket. The equivalent ability for ICMPv4 was added in
2011.

Instead of having separate code paths for IPv4 and IPv6, make
most of the code in net/ipv4/ping.c dual-stack and only add a
few IPv6-specific bits (like the protocol definition) to a new
net/ipv6/ping.c. Hopefully this will reduce divergence and/or
duplication of bugs in the future.

Caveats:

- Setting options via ancillary data (e.g., using IPV6_PKTINFO
  to specify the outgoing interface) is not yet supported.
- There are no separate security settings for IPv4 and IPv6;
  everything is controlled by /proc/net/ipv4/ping_group_range.
- The proc interface does not yet display IPv6 ping sockets
  properly.

Tested with a patched copy of ping6 and using raw socket calls.
Compiles and works with all of CONFIG_IPV6={n,m,y}.

CRs-Fixed: 573548
Change-Id: I0081b4654dd54b12c8f233e00e18943582aa2142
Signed-off-by: Lorenzo Colitti <lorenzo@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
[lorenzo@google.com: backported to 3.4]
Signed-off-by: Lorenzo Colitti <lorenzo@google.com>
Git-commit: 1f0675844e3b63a765e5bd32bc5af051ccd951c0
Git-repo: https://android.googlesource.com/kernel/common
[subashab@codeaurora.org : resolve trivial merge conflicts]
Signed-off-by: Subash Abhinov Kasiviswanathan <subashab@codeaurora.org>
Signed-off-by: Ian Maund <imaund@codeaurora.org>
diff --git a/net/ipv6/icmp.c b/net/ipv6/icmp.c
index 27ac95a..ba0c147 100644
--- a/net/ipv6/icmp.c
+++ b/net/ipv6/icmp.c
@@ -55,6 +55,7 @@
 
 #include <net/ipv6.h>
 #include <net/ip6_checksum.h>
+#include <net/ping.h>
 #include <net/protocol.h>
 #include <net/raw.h>
 #include <net/rawv6.h>
@@ -79,10 +80,22 @@
 	return net->ipv6.icmp_sk[smp_processor_id()];
 }
 
+static void icmpv6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
+		       u8 type, u8 code, int offset, __be32 info)
+{
+	/* icmpv6_notify checks 8 bytes can be pulled, icmp6hdr is 8 bytes */
+	struct icmp6hdr *icmp6 = (struct icmp6hdr *) (skb->data + offset);
+
+	if (!(type & ICMPV6_INFOMSG_MASK))
+		if (icmp6->icmp6_type == ICMPV6_ECHO_REQUEST)
+			ping_err(skb, offset, info);
+}
+
 static int icmpv6_rcv(struct sk_buff *skb);
 
 static const struct inet6_protocol icmpv6_protocol = {
 	.handler	=	icmpv6_rcv,
+	.err_handler	=	icmpv6_err,
 	.flags		=	INET6_PROTO_NOPOLICY|INET6_PROTO_FINAL,
 };
 
@@ -217,7 +230,8 @@
 	return (*op & 0xC0) == 0x80;
 }
 
-static int icmpv6_push_pending_frames(struct sock *sk, struct flowi6 *fl6, struct icmp6hdr *thdr, int len)
+int icmpv6_push_pending_frames(struct sock *sk, struct flowi6 *fl6,
+			       struct icmp6hdr *thdr, int len)
 {
 	struct sk_buff *skb;
 	struct icmp6hdr *icmp6h;
@@ -300,8 +314,8 @@
 static inline void mip6_addr_swap(struct sk_buff *skb) {}
 #endif
 
-static struct dst_entry *icmpv6_route_lookup(struct net *net, struct sk_buff *skb,
-					     struct sock *sk, struct flowi6 *fl6)
+struct dst_entry *icmpv6_route_lookup(struct net *net, struct sk_buff *skb,
+				      struct sock *sk, struct flowi6 *fl6)
 {
 	struct dst_entry *dst, *dst2;
 	struct flowi6 fl2;
@@ -594,7 +608,7 @@
 	icmpv6_xmit_unlock(sk);
 }
 
-static void icmpv6_notify(struct sk_buff *skb, u8 type, u8 code, __be32 info)
+void icmpv6_notify(struct sk_buff *skb, u8 type, u8 code, __be32 info)
 {
 	const struct inet6_protocol *ipprot;
 	int inner_offset;
@@ -687,7 +701,8 @@
 		skb->csum = ~csum_unfold(csum_ipv6_magic(saddr, daddr, skb->len,
 					     IPPROTO_ICMPV6, 0));
 		if (__skb_checksum_complete(skb)) {
-			LIMIT_NETDEBUG(KERN_DEBUG "ICMPv6 checksum failed [%pI6 > %pI6]\n",
+			LIMIT_NETDEBUG(KERN_DEBUG
+				       "ICMPv6 checksum failed [%pI6c > %pI6c]\n",
 				       saddr, daddr);
 			goto discard_it;
 		}
@@ -708,7 +723,7 @@
 		break;
 
 	case ICMPV6_ECHO_REPLY:
-		/* we couldn't care less */
+		ping_rcv(skb);
 		break;
 
 	case ICMPV6_PKT_TOOBIG: