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ipv6: sr: add support for SRH encapsulation and injection with lwtunnels

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This patch creates a new type of interfaceless lightweight tunnel (SEG6),
enabling the encapsulation and injection of SRH within locally emitted
packets and forwarded packets.

>From a configuration viewpoint, a seg6 tunnel would be configured as follows:

  ip -6 ro ad fc00::1/128 encap seg6 mode encap segs fc42::1,fc42::2,fc42::3 dev eth0

Any packet whose destination address is fc00::1 would thus be encapsulated
within an outer IPv6 header containing the SRH with three segments, and would
actually be routed to the first segment of the list. If `mode inline' was
specified instead of `mode encap', then the SRH would be directly inserted
after the IPv6 header without outer encapsulation.

The inline mode is only available if CONFIG_IPV6_SEG6_INLINE is enabled. This
feature was made configurable because direct header insertion may break
several mechanisms such as PMTUD or IPSec AH.

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
2016-11-08 14:57:41 +01:00
committed by David S. Miller
parent 915d7e5e59
commit 6c8702c60b
9 changed files with 526 additions and 1 deletions
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44
net/ipv6/seg6.c
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@@ -26,6 +26,43 @@
#include <linux/seg6.h>
#include <linux/seg6_genl.h>
bool seg6_validate_srh(struct ipv6_sr_hdr *srh, int len)
{
int trailing;
unsigned int tlv_offset;
if (srh->type != IPV6_SRCRT_TYPE_4)
return false;
if (((srh->hdrlen + 1) << 3) != len)
return false;
if (srh->segments_left != srh->first_segment)
return false;
tlv_offset = sizeof(*srh) + ((srh->first_segment + 1) << 4);
trailing = len - tlv_offset;
if (trailing < 0)
return false;
while (trailing) {
struct sr6_tlv *tlv;
unsigned int tlv_len;
tlv = (struct sr6_tlv *)((unsigned char *)srh + tlv_offset);
tlv_len = sizeof(*tlv) + tlv->len;
trailing -= tlv_len;
if (trailing < 0)
return false;
tlv_offset += tlv_len;
}
return true;
}
static struct genl_family seg6_genl_family;
static const struct nla_policy seg6_genl_policy[SEG6_ATTR_MAX + 1] = {
@@ -198,10 +235,16 @@ int __init seg6_init(void)
if (err)
goto out_unregister_genl;
err = seg6_iptunnel_init();
if (err)
goto out_unregister_pernet;
pr_info("Segment Routing with IPv6\n");
out:
return err;
out_unregister_pernet:
unregister_pernet_subsys(&ip6_segments_ops);
out_unregister_genl:
genl_unregister_family(&seg6_genl_family);
goto out;
@@ -209,6 +252,7 @@ out_unregister_genl:
void seg6_exit(void)
{
seg6_iptunnel_exit();
unregister_pernet_subsys(&ip6_segments_ops);
genl_unregister_family(&seg6_genl_family);
}