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>
This commit is contained in:
David Lebrun
David S. Miller
parent
6285217f0c
commit
d7a669dd2f
@ -308,6 +308,7 @@ config IPV6_SEG6_LWTUNNEL
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depends on IPV6
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select LWTUNNEL
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select DST_CACHE
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select IPV6_MULTIPLE_TABLES
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---help---
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Support for encapsulation of packets within an outer IPv6
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header and a Segment Routing Header using the lightweight
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@ -99,23 +99,105 @@ static struct ipv6_sr_hdr *get_and_validate_srh(struct sk_buff *skb)
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return srh;
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}
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static bool decap_and_validate(struct sk_buff *skb, int proto)
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{
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struct ipv6_sr_hdr *srh;
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unsigned int off = 0;
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srh = get_srh(skb);
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if (srh && srh->segments_left > 0)
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return false;
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#ifdef CONFIG_IPV6_SEG6_HMAC
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if (srh && !seg6_hmac_validate_skb(skb))
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return false;
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#endif
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if (ipv6_find_hdr(skb, &off, proto, NULL, NULL) < 0)
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return false;
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if (!pskb_pull(skb, off))
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return false;
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skb_postpull_rcsum(skb, skb_network_header(skb), off);
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skb_reset_network_header(skb);
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skb_reset_transport_header(skb);
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skb->encapsulation = 0;
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return true;
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}
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static void advance_nextseg(struct ipv6_sr_hdr *srh, struct in6_addr *daddr)
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{
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struct in6_addr *addr;
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srh->segments_left--;
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addr = srh->segments + srh->segments_left;
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*daddr = *addr;
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}
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static void lookup_nexthop(struct sk_buff *skb, struct in6_addr *nhaddr,
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u32 tbl_id)
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{
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struct net *net = dev_net(skb->dev);
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struct ipv6hdr *hdr = ipv6_hdr(skb);
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int flags = RT6_LOOKUP_F_HAS_SADDR;
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struct dst_entry *dst = NULL;
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struct rt6_info *rt;
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struct flowi6 fl6;
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fl6.flowi6_iif = skb->dev->ifindex;
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fl6.daddr = nhaddr ? *nhaddr : hdr->daddr;
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fl6.saddr = hdr->saddr;
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fl6.flowlabel = ip6_flowinfo(hdr);
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fl6.flowi6_mark = skb->mark;
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fl6.flowi6_proto = hdr->nexthdr;
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if (nhaddr)
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fl6.flowi6_flags = FLOWI_FLAG_KNOWN_NH;
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if (!tbl_id) {
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dst = ip6_route_input_lookup(net, skb->dev, &fl6, flags);
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} else {
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struct fib6_table *table;
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table = fib6_get_table(net, tbl_id);
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if (!table)
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goto out;
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rt = ip6_pol_route(net, table, 0, &fl6, flags);
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dst = &rt->dst;
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}
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if (dst && dst->dev->flags & IFF_LOOPBACK && !dst->error) {
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dst_release(dst);
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dst = NULL;
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}
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out:
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if (!dst) {
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rt = net->ipv6.ip6_blk_hole_entry;
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dst = &rt->dst;
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dst_hold(dst);
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}
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skb_dst_drop(skb);
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skb_dst_set(skb, dst);
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}
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/* regular endpoint function */
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static int input_action_end(struct sk_buff *skb, struct seg6_local_lwt *slwt)
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{
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struct ipv6_sr_hdr *srh;
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struct in6_addr *addr;
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srh = get_and_validate_srh(skb);
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if (!srh)
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goto drop;
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srh->segments_left--;
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addr = srh->segments + srh->segments_left;
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advance_nextseg(srh, &ipv6_hdr(skb)->daddr);
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ipv6_hdr(skb)->daddr = *addr;
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skb_dst_drop(skb);
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ip6_route_input(skb);
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lookup_nexthop(skb, NULL, 0);
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return dst_input(skb);
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@ -127,41 +209,15 @@ drop:
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/* regular endpoint, and forward to specified nexthop */
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static int input_action_end_x(struct sk_buff *skb, struct seg6_local_lwt *slwt)
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{
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struct net *net = dev_net(skb->dev);
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struct ipv6_sr_hdr *srh;
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struct dst_entry *dst;
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struct in6_addr *addr;
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struct ipv6hdr *hdr;
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struct flowi6 fl6;
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int flags;
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srh = get_and_validate_srh(skb);
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if (!srh)
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goto drop;
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srh->segments_left--;
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addr = srh->segments + srh->segments_left;
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advance_nextseg(srh, &ipv6_hdr(skb)->daddr);
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hdr = ipv6_hdr(skb);
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hdr->daddr = *addr;
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skb_dst_drop(skb);
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fl6.flowi6_iif = skb->dev->ifindex;
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fl6.daddr = slwt->nh6;
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fl6.saddr = hdr->saddr;
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fl6.flowlabel = ip6_flowinfo(hdr);
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fl6.flowi6_mark = skb->mark;
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fl6.flowi6_proto = hdr->nexthdr;
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flags = RT6_LOOKUP_F_HAS_SADDR | RT6_LOOKUP_F_IFACE |
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RT6_LOOKUP_F_REACHABLE;
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dst = ip6_route_input_lookup(net, skb->dev, &fl6, flags);
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if (dst->dev->flags & IFF_LOOPBACK)
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goto drop;
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skb_dst_set(skb, dst);
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lookup_nexthop(skb, &slwt->nh6, 0);
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return dst_input(skb);
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@ -174,41 +230,17 @@ drop:
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static int input_action_end_dx6(struct sk_buff *skb,
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struct seg6_local_lwt *slwt)
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{
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struct net *net = dev_net(skb->dev);
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struct ipv6hdr *inner_hdr;
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struct ipv6_sr_hdr *srh;
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struct dst_entry *dst;
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unsigned int off = 0;
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struct flowi6 fl6;
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bool use_nh;
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int flags;
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struct in6_addr *nhaddr = NULL;
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/* this function accepts IPv6 encapsulated packets, with either
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* an SRH with SL=0, or no SRH.
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*/
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srh = get_srh(skb);
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if (srh && srh->segments_left > 0)
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if (!decap_and_validate(skb, IPPROTO_IPV6))
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goto drop;
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#ifdef CONFIG_IPV6_SEG6_HMAC
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if (srh && !seg6_hmac_validate_skb(skb))
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if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
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goto drop;
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#endif
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if (ipv6_find_hdr(skb, &off, IPPROTO_IPV6, NULL, NULL) < 0)
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goto drop;
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if (!pskb_pull(skb, off))
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goto drop;
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skb_postpull_rcsum(skb, skb_network_header(skb), off);
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skb_reset_network_header(skb);
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skb_reset_transport_header(skb);
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skb->encapsulation = 0;
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inner_hdr = ipv6_hdr(skb);
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/* The inner packet is not associated to any local interface,
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* so we do not call netif_rx().
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@ -217,26 +249,10 @@ static int input_action_end_dx6(struct sk_buff *skb,
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* inner packet's DA. Otherwise, use the specified nexthop.
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*/
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use_nh = !ipv6_addr_any(&slwt->nh6);
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if (!ipv6_addr_any(&slwt->nh6))
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nhaddr = &slwt->nh6;
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skb_dst_drop(skb);
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fl6.flowi6_iif = skb->dev->ifindex;
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fl6.daddr = use_nh ? slwt->nh6 : inner_hdr->daddr;
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fl6.saddr = inner_hdr->saddr;
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fl6.flowlabel = ip6_flowinfo(inner_hdr);
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fl6.flowi6_mark = skb->mark;
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fl6.flowi6_proto = inner_hdr->nexthdr;
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flags = RT6_LOOKUP_F_HAS_SADDR | RT6_LOOKUP_F_REACHABLE;
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if (use_nh)
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flags |= RT6_LOOKUP_F_IFACE;
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dst = ip6_route_input_lookup(net, skb->dev, &fl6, flags);
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if (dst->dev->flags & IFF_LOOPBACK)
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goto drop;
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skb_dst_set(skb, dst);
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lookup_nexthop(skb, nhaddr, 0);
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return dst_input(skb);
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drop:
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@ -261,8 +277,7 @@ static int input_action_end_b6(struct sk_buff *skb, struct seg6_local_lwt *slwt)
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ipv6_hdr(skb)->payload_len = htons(skb->len - sizeof(struct ipv6hdr));
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skb_set_transport_header(skb, sizeof(struct ipv6hdr));
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skb_dst_drop(skb);
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ip6_route_input(skb);
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lookup_nexthop(skb, NULL, 0);
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return dst_input(skb);
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@ -276,16 +291,13 @@ static int input_action_end_b6_encap(struct sk_buff *skb,
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struct seg6_local_lwt *slwt)
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{
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struct ipv6_sr_hdr *srh;
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struct in6_addr *addr;
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int err = -EINVAL;
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srh = get_and_validate_srh(skb);
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if (!srh)
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goto drop;
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srh->segments_left--;
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addr = srh->segments + srh->segments_left;
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ipv6_hdr(skb)->daddr = *addr;
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advance_nextseg(srh, &ipv6_hdr(skb)->daddr);
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skb_reset_inner_headers(skb);
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skb->encapsulation = 1;
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@ -297,8 +309,7 @@ static int input_action_end_b6_encap(struct sk_buff *skb,
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ipv6_hdr(skb)->payload_len = htons(skb->len - sizeof(struct ipv6hdr));
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skb_set_transport_header(skb, sizeof(struct ipv6hdr));
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skb_dst_drop(skb);
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ip6_route_input(skb);
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lookup_nexthop(skb, NULL, 0);
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return dst_input(skb);
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