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>

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 @@ static int ipv6_srh_rcv(struct sk_buff *skb)
 		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 &&

net/ipv6/seg6_iptunnel.c

@@ -29,6 +29,9 @@
 #ifdef CONFIG_DST_CACHE
 #include <net/dst_cache.h>
 #endif
+#ifdef CONFIG_IPV6_SEG6_HMAC
+#include <net/seg6_hmac.h>
+#endif
 
 struct seg6_lwt {
 #ifdef CONFIG_DST_CACHE
@@ -130,6 +133,14 @@ static int seg6_do_srh_encap(struct sk_buff *skb, struct ipv6_sr_hdr *osrh)
 	hdr->daddr = isrh->segments[isrh->first_segment];
 	set_tun_src(net, skb->dev, &hdr->daddr, &hdr->saddr);
 
+#ifdef CONFIG_IPV6_SEG6_HMAC
+	if (sr_has_hmac(isrh)) {
+		err = seg6_push_hmac(net, &hdr->saddr, isrh);
+		if (unlikely(err))
+			return err;
+	}
+#endif
+
 	skb_postpush_rcsum(skb, hdr, tot_len);
 
 	return 0;
@@ -172,6 +183,16 @@ static int seg6_do_srh_inline(struct sk_buff *skb, struct ipv6_sr_hdr *osrh)
 	isrh->segments[0] = hdr->daddr;
 	hdr->daddr = isrh->segments[isrh->first_segment];
 
+#ifdef CONFIG_IPV6_SEG6_HMAC
+	if (sr_has_hmac(isrh)) {
+		struct net *net = dev_net(skb_dst(skb)->dev);
+
+		err = seg6_push_hmac(net, &hdr->saddr, isrh);
+		if (unlikely(err))
+			return err;
+	}
+#endif
+
 	skb_postpush_rcsum(skb, hdr, sizeof(struct ipv6hdr) + hdrlen);
 
 	return 0;