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: David Lebrun <david.lebrun@uclouvain.be>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv6/Kconfig b/net/ipv6/Kconfig
index 0d72239..ea71e4b 100644
--- a/net/ipv6/Kconfig
+++ b/net/ipv6/Kconfig
@@ -308,6 +308,7 @@
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
diff --git a/net/ipv6/seg6_local.c b/net/ipv6/seg6_local.c
index c626325..26db4d3e 100644
--- a/net/ipv6/seg6_local.c
+++ b/net/ipv6/seg6_local.c
@@ -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;
+ advance_nextseg(srh, &ipv6_hdr(skb)->daddr);
- ipv6_hdr(skb)->daddr = *addr;
-
- 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;
+ advance_nextseg(srh, &ipv6_hdr(skb)->daddr);
- hdr = ipv6_hdr(skb);
- hdr->daddr = *addr;
-
- 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);
+ if (!ipv6_addr_any(&slwt->nh6))
+ nhaddr = &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;
-
- 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);