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Commit d7a669dd authored by David Lebrun's avatar David Lebrun Committed by David S. Miller
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ipv6: sr: add helper functions for seg6local 



This patch adds three helper functions to be used with the seg6local packet
processing actions.

The decap_and_validate() function will be used by the End.D* actions, that
decapsulate an SR-enabled packet.

The advance_nextseg() function applies the fundamental operations to update
an SRH for the next segment.

The lookup_nexthop() function helps select the next-hop for the processed
SR packets. It supports an optional next-hop address to route the packet
specifically through it, and an optional routing table to use.

Signed-off-by: default avatarDavid Lebrun <david.lebrun@uclouvain.be>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 6285217f

net/ipv6/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -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_local.c

+100 −89
Original line number Diff line number Diff line
@@ -99,23 +99,105 @@ static struct ipv6_sr_hdr *get_and_validate_srh(struct sk_buff *skb) 
	return srh;

}



static bool decap_and_validate(struct sk_buff *skb, int proto)

{

	struct ipv6_sr_hdr *srh;

	unsigned int off = 0;



	srh = get_srh(skb);

	if (srh && srh->segments_left > 0)

		return false;



#ifdef CONFIG_IPV6_SEG6_HMAC

	if (srh && !seg6_hmac_validate_skb(skb))

		return false;

#endif



	if (ipv6_find_hdr(skb, &off, proto, NULL, NULL) < 0)

		return false;



	if (!pskb_pull(skb, off))

		return false;



	skb_postpull_rcsum(skb, skb_network_header(skb), off);



	skb_reset_network_header(skb);

	skb_reset_transport_header(skb);

	skb->encapsulation = 0;



	return true;

}



static void advance_nextseg(struct ipv6_sr_hdr *srh, struct in6_addr *daddr)

{

	struct in6_addr *addr;



	srh->segments_left--;

	addr = srh->segments + srh->segments_left;

	*daddr = *addr;

}



static void lookup_nexthop(struct sk_buff *skb, struct in6_addr *nhaddr,

			   u32 tbl_id)

{

	struct net *net = dev_net(skb->dev);

	struct ipv6hdr *hdr = ipv6_hdr(skb);

	int flags = RT6_LOOKUP_F_HAS_SADDR;

	struct dst_entry *dst = NULL;

	struct rt6_info *rt;

	struct flowi6 fl6;



	fl6.flowi6_iif = skb->dev->ifindex;

	fl6.daddr = nhaddr ? *nhaddr : hdr->daddr;

	fl6.saddr = hdr->saddr;

	fl6.flowlabel = ip6_flowinfo(hdr);

	fl6.flowi6_mark = skb->mark;

	fl6.flowi6_proto = hdr->nexthdr;



	if (nhaddr)

		fl6.flowi6_flags = FLOWI_FLAG_KNOWN_NH;



	if (!tbl_id) {

		dst = ip6_route_input_lookup(net, skb->dev, &fl6, flags);

	} else {

		struct fib6_table *table;



		table = fib6_get_table(net, tbl_id);

		if (!table)

			goto out;



		rt = ip6_pol_route(net, table, 0, &fl6, flags);

		dst = &rt->dst;

	}



	if (dst && dst->dev->flags & IFF_LOOPBACK && !dst->error) {

		dst_release(dst);

		dst = NULL;

	}



out:

	if (!dst) {

		rt = net->ipv6.ip6_blk_hole_entry;

		dst = &rt->dst;

		dst_hold(dst);

	}



	skb_dst_drop(skb);

	skb_dst_set(skb, dst);

}



/* regular endpoint function */

static int input_action_end(struct sk_buff *skb, struct seg6_local_lwt *slwt)

{

	struct ipv6_sr_hdr *srh;

	struct in6_addr *addr;



	srh = get_and_validate_srh(skb);

	if (!srh)

		goto drop;



	srh->segments_left--;

	addr = srh->segments + srh->segments_left;



	ipv6_hdr(skb)->daddr = *addr;

	advance_nextseg(srh, &ipv6_hdr(skb)->daddr);



	skb_dst_drop(skb);

	ip6_route_input(skb);

	lookup_nexthop(skb, NULL, 0);



	return dst_input(skb);
@@ -127,41 +209,15 @@ static int input_action_end(struct sk_buff *skb, struct seg6_local_lwt *slwt) 
/* regular endpoint, and forward to specified nexthop */

static int input_action_end_x(struct sk_buff *skb, struct seg6_local_lwt *slwt)

{

	struct net *net = dev_net(skb->dev);

	struct ipv6_sr_hdr *srh;

	struct dst_entry *dst;

	struct in6_addr *addr;

	struct ipv6hdr *hdr;

	struct flowi6 fl6;

	int flags;



	srh = get_and_validate_srh(skb);

	if (!srh)

		goto drop;



	srh->segments_left--;

	addr = srh->segments + srh->segments_left;



	hdr = ipv6_hdr(skb);

	hdr->daddr = *addr;

	advance_nextseg(srh, &ipv6_hdr(skb)->daddr);



	skb_dst_drop(skb);



	fl6.flowi6_iif = skb->dev->ifindex;

	fl6.daddr = slwt->nh6;

	fl6.saddr = hdr->saddr;

	fl6.flowlabel = ip6_flowinfo(hdr);

	fl6.flowi6_mark = skb->mark;

	fl6.flowi6_proto = hdr->nexthdr;



	flags = RT6_LOOKUP_F_HAS_SADDR | RT6_LOOKUP_F_IFACE |

		RT6_LOOKUP_F_REACHABLE;



	dst = ip6_route_input_lookup(net, skb->dev, &fl6, flags);

	if (dst->dev->flags & IFF_LOOPBACK)

		goto drop;



	skb_dst_set(skb, dst);

	lookup_nexthop(skb, &slwt->nh6, 0);



	return dst_input(skb);
@@ -174,41 +230,17 @@ static int input_action_end_x(struct sk_buff *skb, struct seg6_local_lwt *slwt) 
static int input_action_end_dx6(struct sk_buff *skb,

				struct seg6_local_lwt *slwt)

{

	struct net *net = dev_net(skb->dev);

	struct ipv6hdr *inner_hdr;

	struct ipv6_sr_hdr *srh;

	struct dst_entry *dst;

	unsigned int off = 0;

	struct flowi6 fl6;

	bool use_nh;

	int flags;

	struct in6_addr *nhaddr = NULL;



	/* this function accepts IPv6 encapsulated packets, with either

	 * an SRH with SL=0, or no SRH.

	 */



	srh = get_srh(skb);

	if (srh && srh->segments_left > 0)

	if (!decap_and_validate(skb, IPPROTO_IPV6))

		goto drop;



#ifdef CONFIG_IPV6_SEG6_HMAC

	if (srh && !seg6_hmac_validate_skb(skb))

	if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))

		goto drop;

#endif



	if (ipv6_find_hdr(skb, &off, IPPROTO_IPV6, NULL, NULL) < 0)

		goto drop;



	if (!pskb_pull(skb, off))

		goto drop;



	skb_postpull_rcsum(skb, skb_network_header(skb), off);



	skb_reset_network_header(skb);

	skb_reset_transport_header(skb);

	skb->encapsulation = 0;



	inner_hdr = ipv6_hdr(skb);



	/* The inner packet is not associated to any local interface,

	 * so we do not call netif_rx().
@@ -217,26 +249,10 @@ static int input_action_end_dx6(struct sk_buff *skb, 
	 * inner packet's DA. Otherwise, use the specified nexthop.

	 */



	use_nh = !ipv6_addr_any(&slwt->nh6);



	skb_dst_drop(skb);



	fl6.flowi6_iif = skb->dev->ifindex;

	fl6.daddr = use_nh ? slwt->nh6 : inner_hdr->daddr;

	fl6.saddr = inner_hdr->saddr;

	fl6.flowlabel = ip6_flowinfo(inner_hdr);

	fl6.flowi6_mark = skb->mark;

	fl6.flowi6_proto = inner_hdr->nexthdr;



	flags = RT6_LOOKUP_F_HAS_SADDR | RT6_LOOKUP_F_REACHABLE;

	if (use_nh)

		flags |= RT6_LOOKUP_F_IFACE;



	dst = ip6_route_input_lookup(net, skb->dev, &fl6, flags);

	if (dst->dev->flags & IFF_LOOPBACK)

		goto drop;

	if (!ipv6_addr_any(&slwt->nh6))

		nhaddr = &slwt->nh6;



	skb_dst_set(skb, dst);

	lookup_nexthop(skb, nhaddr, 0);



	return dst_input(skb);

drop:
@@ -261,8 +277,7 @@ static int input_action_end_b6(struct sk_buff *skb, struct seg6_local_lwt *slwt) 
	ipv6_hdr(skb)->payload_len = htons(skb->len - sizeof(struct ipv6hdr));

	skb_set_transport_header(skb, sizeof(struct ipv6hdr));



	skb_dst_drop(skb);

	ip6_route_input(skb);

	lookup_nexthop(skb, NULL, 0);



	return dst_input(skb);
@@ -276,16 +291,13 @@ static int input_action_end_b6_encap(struct sk_buff *skb, 
				     struct seg6_local_lwt *slwt)

{

	struct ipv6_sr_hdr *srh;

	struct in6_addr *addr;

	int err = -EINVAL;



	srh = get_and_validate_srh(skb);

	if (!srh)

		goto drop;



	srh->segments_left--;

	addr = srh->segments + srh->segments_left;

	ipv6_hdr(skb)->daddr = *addr;

	advance_nextseg(srh, &ipv6_hdr(skb)->daddr);



	skb_reset_inner_headers(skb);

	skb->encapsulation = 1;
@@ -297,8 +309,7 @@ static int input_action_end_b6_encap(struct sk_buff *skb, 
	ipv6_hdr(skb)->payload_len = htons(skb->len - sizeof(struct ipv6hdr));

	skb_set_transport_header(skb, sizeof(struct ipv6hdr));



	skb_dst_drop(skb);

	ip6_route_input(skb);

	lookup_nexthop(skb, NULL, 0);



	return dst_input(skb);