ipv6: sr: add support for SRH injection through setsockopt

This patch adds support for per-socket SRH injection with the setsockopt
system call through the IPPROTO_IPV6, IPV6_RTHDR options.
The SRH is pushed through the ipv6_push_nfrag_opts function.
Signed-off-by: David Lebrun <david.lebrun@uclouvain.be>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv6/exthdrs.c

@@ -864,7 +864,7 @@ int ipv6_parse_hopopts(struct sk_buff *skb)
  *	for headers.
  */
 
-static void ipv6_push_rthdr(struct sk_buff *skb, u8 *proto,
+static void ipv6_push_rthdr0(struct sk_buff *skb, u8 *proto,
 			     struct ipv6_rt_hdr *opt,
 			     struct in6_addr **addr_p, struct in6_addr *saddr)
 {
@@ -889,6 +889,62 @@ static void ipv6_push_rthdr(struct sk_buff *skb, u8 *proto,
 	*proto = NEXTHDR_ROUTING;
 }
 
+static void ipv6_push_rthdr4(struct sk_buff *skb, u8 *proto,
+			     struct ipv6_rt_hdr *opt,
+			     struct in6_addr **addr_p, struct in6_addr *saddr)
+{
+	struct ipv6_sr_hdr *sr_phdr, *sr_ihdr;
+	int plen, hops;
+
+	sr_ihdr = (struct ipv6_sr_hdr *)opt;
+	plen = (sr_ihdr->hdrlen + 1) << 3;
+
+	sr_phdr = (struct ipv6_sr_hdr *)skb_push(skb, plen);
+	memcpy(sr_phdr, sr_ihdr, sizeof(struct ipv6_sr_hdr));
+
+	hops = sr_ihdr->first_segment + 1;
+	memcpy(sr_phdr->segments + 1, sr_ihdr->segments + 1,
+	       (hops - 1) * sizeof(struct in6_addr));
+
+	sr_phdr->segments[0] = **addr_p;
+	*addr_p = &sr_ihdr->segments[hops - 1];
+
+#ifdef CONFIG_IPV6_SEG6_HMAC
+	if (sr_has_hmac(sr_phdr)) {
+		struct net *net = NULL;
+
+		if (skb->dev)
+			net = dev_net(skb->dev);
+		else if (skb->sk)
+			net = sock_net(skb->sk);
+
+		WARN_ON(!net);
+
+		if (net)
+			seg6_push_hmac(net, saddr, sr_phdr);
+	}
+#endif
+
+	sr_phdr->nexthdr = *proto;
+	*proto = NEXTHDR_ROUTING;
+}
+
+static void ipv6_push_rthdr(struct sk_buff *skb, u8 *proto,
+			    struct ipv6_rt_hdr *opt,
+			    struct in6_addr **addr_p, struct in6_addr *saddr)
+{
+	switch (opt->type) {
+	case IPV6_SRCRT_TYPE_0:
+		ipv6_push_rthdr0(skb, proto, opt, addr_p, saddr);
+		break;
+	case IPV6_SRCRT_TYPE_4:
+		ipv6_push_rthdr4(skb, proto, opt, addr_p, saddr);
+		break;
+	default:
+		break;
+	}
+}
+
 static void ipv6_push_exthdr(struct sk_buff *skb, u8 *proto, u8 type, struct ipv6_opt_hdr *opt)
 {
 	struct ipv6_opt_hdr *h = (struct ipv6_opt_hdr *)skb_push(skb, ipv6_optlen(opt));
@@ -1130,7 +1186,22 @@ struct in6_addr *fl6_update_dst(struct flowi6 *fl6,
 		return NULL;
 
 	*orig = fl6->daddr;
+
+	switch (opt->srcrt->type) {
+	case IPV6_SRCRT_TYPE_0:
 		fl6->daddr = *((struct rt0_hdr *)opt->srcrt)->addr;
+		break;
+	case IPV6_SRCRT_TYPE_4:
+	{
+		struct ipv6_sr_hdr *srh = (struct ipv6_sr_hdr *)opt->srcrt;
+
+		fl6->daddr = srh->segments[srh->first_segment];
+		break;
+	}
+	default:
+		return NULL;
+	}
+
 	return orig;
 }
 EXPORT_SYMBOL_GPL(fl6_update_dst);

net/ipv6/ipv6_sockglue.c

@@ -52,6 +52,7 @@
 #include <net/udplite.h>
 #include <net/xfrm.h>
 #include <net/compat.h>
+#include <net/seg6.h>
 
 #include <asm/uaccess.h>
 
@@ -430,6 +431,15 @@ static int do_ipv6_setsockopt(struct sock *sk, int level, int optname,
 
 				break;
 #endif
+			case IPV6_SRCRT_TYPE_4:
+			{
+				struct ipv6_sr_hdr *srh = (struct ipv6_sr_hdr *)
+							  opt->srcrt;
+
+				if (!seg6_validate_srh(srh, optlen))
+					goto sticky_done;
+				break;
+			}
 			default:
 				goto sticky_done;
 			}