Merge branch 'ipv6-sr-updates'

David Lebrun says:

====================
net: updates for IPv6 Segment Routing

v2: seg6_lwt_headroom() is not relevant for lwtunnel_input_redirect()
    use cases, and L2ENCAP only uses this redirection. Fix incoherence
    between arbitrary MAC header size support and fixed headroom
    computation by setting only LWTUNNEL_STATE_INPUT_REDIRECT for L2ENCAP
    mode.

This patch series provides several updates for the SRv6 implementation. The
first patch leverages the existing infrastructure to support encapsulation
of IPv4 packets. The second patch implements the T.Encaps.L2 SR function,
enabling to encapsulate an L2 Ethernet frame within an IPv6+SRH packet.
The last three patches update the seg6local lightweight tunnel, and mainly
implement four new actions: End.T, End.DX2, End.DX4 and End.DT6.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/seg6.h

@@ -60,7 +60,8 @@ extern int seg6_local_init(void);
 extern void seg6_local_exit(void);
 
 extern bool seg6_validate_srh(struct ipv6_sr_hdr *srh, int len);
-extern int seg6_do_srh_encap(struct sk_buff *skb, struct ipv6_sr_hdr *osrh);
+extern int seg6_do_srh_encap(struct sk_buff *skb, struct ipv6_sr_hdr *osrh,
+			     int proto);
 extern int seg6_do_srh_inline(struct sk_buff *skb, struct ipv6_sr_hdr *osrh);
 
 #endif

include/uapi/linux/seg6_iptunnel.h

@@ -33,16 +33,26 @@ struct seg6_iptunnel_encap {
 enum {
 	SEG6_IPTUN_MODE_INLINE,
 	SEG6_IPTUN_MODE_ENCAP,
+	SEG6_IPTUN_MODE_L2ENCAP,
 };
 
 #ifdef __KERNEL__
 
 static inline size_t seg6_lwt_headroom(struct seg6_iptunnel_encap *tuninfo)
 {
-	int encap = (tuninfo->mode == SEG6_IPTUN_MODE_ENCAP);
-
-	return ((tuninfo->srh->hdrlen + 1) << 3) +
-	       (encap * sizeof(struct ipv6hdr));
+	int head = 0;
+
+	switch (tuninfo->mode) {
+	case SEG6_IPTUN_MODE_INLINE:
+		break;
+	case SEG6_IPTUN_MODE_ENCAP:
+		head = sizeof(struct ipv6hdr);
+		break;
+	case SEG6_IPTUN_MODE_L2ENCAP:
+		return 0;
+	}
+
+	return ((tuninfo->srh->hdrlen + 1) << 3) + head;
 }
 
 #endif

net/ipv6/Kconfig

@@ -308,6 +308,7 @@ config IPV6_SEG6_LWTUNNEL
 	depends on IPV6
 	select LWTUNNEL
 	select DST_CACHE
+	select IPV6_MULTIPLE_TABLES
 	---help---
 	  Support for encapsulation of packets within an outer IPv6
 	  header and a Segment Routing Header using the lightweight

net/ipv6/seg6_iptunnel.c

@@ -91,7 +91,7 @@ static void set_tun_src(struct net *net, struct net_device *dev,
 }
 
 /* encapsulate an IPv6 packet within an outer IPv6 header with a given SRH */
-int seg6_do_srh_encap(struct sk_buff *skb, struct ipv6_sr_hdr *osrh)
+int seg6_do_srh_encap(struct sk_buff *skb, struct ipv6_sr_hdr *osrh, int proto)
 {
 	struct net *net = dev_net(skb_dst(skb)->dev);
 	struct ipv6hdr *hdr, *inner_hdr;
@@ -116,15 +116,22 @@ int seg6_do_srh_encap(struct sk_buff *skb, struct ipv6_sr_hdr *osrh)
 	 * hlim will be decremented in ip6_forward() afterwards and
 	 * decapsulation will overwrite inner hlim with outer hlim
 	 */
+
+	if (skb->protocol == htons(ETH_P_IPV6)) {
 		ip6_flow_hdr(hdr, ip6_tclass(ip6_flowinfo(inner_hdr)),
 			     ip6_flowlabel(inner_hdr));
 		hdr->hop_limit = inner_hdr->hop_limit;
+	} else {
+		ip6_flow_hdr(hdr, 0, 0);
+		hdr->hop_limit = ip6_dst_hoplimit(skb_dst(skb));
+	}
+
 	hdr->nexthdr = NEXTHDR_ROUTING;
 
 	isrh = (void *)hdr + sizeof(*hdr);
 	memcpy(isrh, osrh, hdrlen);
 
-	isrh->nexthdr = NEXTHDR_IPV6;
+	isrh->nexthdr = proto;
 
 	hdr->daddr = isrh->segments[isrh->first_segment];
 	set_tun_src(net, skb->dev, &hdr->daddr, &hdr->saddr);
@@ -199,7 +206,7 @@ static int seg6_do_srh(struct sk_buff *skb)
 {
 	struct dst_entry *dst = skb_dst(skb);
 	struct seg6_iptunnel_encap *tinfo;
-	int err = 0;
+	int proto, err = 0;
 
 	tinfo = seg6_encap_lwtunnel(dst->lwtstate);
 
@@ -210,17 +217,47 @@ static int seg6_do_srh(struct sk_buff *skb)
 
 	switch (tinfo->mode) {
 	case SEG6_IPTUN_MODE_INLINE:
+		if (skb->protocol != htons(ETH_P_IPV6))
+			return -EINVAL;
+
 		err = seg6_do_srh_inline(skb, tinfo->srh);
+		if (err)
+			return err;
+
 		skb_reset_inner_headers(skb);
 		break;
 	case SEG6_IPTUN_MODE_ENCAP:
-		err = seg6_do_srh_encap(skb, tinfo->srh);
+		if (skb->protocol == htons(ETH_P_IPV6))
+			proto = IPPROTO_IPV6;
+		else if (skb->protocol == htons(ETH_P_IP))
+			proto = IPPROTO_IPIP;
+		else
+			return -EINVAL;
+
+		err = seg6_do_srh_encap(skb, tinfo->srh, proto);
+		if (err)
+			return err;
+
+		skb->protocol = htons(ETH_P_IPV6);
 		break;
-	}
+	case SEG6_IPTUN_MODE_L2ENCAP:
+		if (!skb_mac_header_was_set(skb))
+			return -EINVAL;
+
+		if (pskb_expand_head(skb, skb->mac_len, 0, GFP_ATOMIC) < 0)
+			return -ENOMEM;
+
+		skb_mac_header_rebuild(skb);
+		skb_push(skb, skb->mac_len);
 
+		err = seg6_do_srh_encap(skb, tinfo->srh, NEXTHDR_NONE);
 		if (err)
 			return err;
 
+		skb->protocol = htons(ETH_P_IPV6);
+		break;
+	}
+
 	ipv6_hdr(skb)->payload_len = htons(skb->len - sizeof(struct ipv6hdr));
 	skb_set_transport_header(skb, sizeof(struct ipv6hdr));
 
@@ -334,6 +371,9 @@ static int seg6_build_state(struct nlattr *nla,
 	struct seg6_lwt *slwt;
 	int err;
 
+	if (family != AF_INET && family != AF_INET6)
+		return -EINVAL;
+
 	err = nla_parse_nested(tb, SEG6_IPTUNNEL_MAX, nla,
 			       seg6_iptunnel_policy, extack);
 
@@ -356,9 +396,14 @@ static int seg6_build_state(struct nlattr *nla,
 
 	switch (tuninfo->mode) {
 	case SEG6_IPTUN_MODE_INLINE:
+		if (family != AF_INET6)
+			return -EINVAL;
+
 		break;
 	case SEG6_IPTUN_MODE_ENCAP:
 		break;
+	case SEG6_IPTUN_MODE_L2ENCAP:
+		break;
 	default:
 		return -EINVAL;
 	}
@@ -382,8 +427,11 @@ static int seg6_build_state(struct nlattr *nla,
 	memcpy(&slwt->tuninfo, tuninfo, tuninfo_len);
 
 	newts->type = LWTUNNEL_ENCAP_SEG6;
-	newts->flags |= LWTUNNEL_STATE_OUTPUT_REDIRECT |
-			LWTUNNEL_STATE_INPUT_REDIRECT;
+	newts->flags |= LWTUNNEL_STATE_INPUT_REDIRECT;
+
+	if (tuninfo->mode != SEG6_IPTUN_MODE_L2ENCAP)
+		newts->flags |= LWTUNNEL_STATE_OUTPUT_REDIRECT;
+
 	newts->headroom = seg6_lwt_headroom(tuninfo);
 
 	*ts = newts;