ipv6: sr: add calls to verify and insert HMAC signatures

This patch enables the verification of the HMAC signature for transiting
SR-enabled packets, and its insertion on encapsulated/injected SRH.

Signed-off-by: David Lebrun <david.lebrun@uclouvain.be>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv6/exthdrs.c b/net/ipv6/exthdrs.c
index b8ba396..541cfa6 100644
--- a/net/ipv6/exthdrs.c
+++ b/net/ipv6/exthdrs.c
@@ -49,6 +49,9 @@
 #endif
 #include <linux/seg6.h>
 #include <net/seg6.h>
+#ifdef CONFIG_IPV6_SEG6_HMAC
+#include <net/seg6_hmac.h>
+#endif
 
 #include <linux/uaccess.h>
 
@@ -340,6 +343,13 @@
 		return -1;
 	}
 
+#ifdef CONFIG_IPV6_SEG6_HMAC
+	if (!seg6_hmac_validate_skb(skb)) {
+		kfree_skb(skb);
+		return -1;
+	}
+#endif
+
 looped_back:
 	if (hdr->segments_left > 0) {
 		if (hdr->nexthdr != NEXTHDR_IPV6 && hdr->segments_left == 1 &&