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.
Signed-off-by: David Lebrun <david.leb...@uclouvain.be>
---
include/linux/seg6_iptunnel.h | 6 +
include/net/seg6.h | 3 +
include/uapi/linux/lwtunnel.h | 1 +
include/uapi/linux/seg6_iptunnel.h | 41 ++++
net/core/lwtunnel.c | 2 +
net/ipv6/Makefile | 2 +-
net/ipv6/seg6.c | 7 +
net/ipv6/seg6_iptunnel.c | 380 +++++++++++++++++++++++++++++++++++++
8 files changed, 441 insertions(+), 1 deletion(-)
create mode 100644 include/linux/seg6_iptunnel.h
create mode 100644 include/uapi/linux/seg6_iptunnel.h
create mode 100644 net/ipv6/seg6_iptunnel.c
diff --git a/include/linux/seg6_iptunnel.h b/include/linux/seg6_iptunnel.h
new file mode 100644
index 0000000..5377cf6
--- /dev/null
+++ b/include/linux/seg6_iptunnel.h
@@ -0,0 +1,6 @@
+#ifndef _LINUX_SEG6_IPTUNNEL_H
+#define _LINUX_SEG6_IPTUNNEL_H
+
+#include <uapi/linux/seg6_iptunnel.h>
+
+#endif
diff --git a/include/net/seg6.h b/include/net/seg6.h
index 7c7b8ed..5dac54e 100644
--- a/include/net/seg6.h
+++ b/include/net/seg6.h
@@ -16,6 +16,7 @@
#include <linux/net.h>
#include <linux/ipv6.h>
+#include <net/lwtunnel.h>
static inline void update_csum_diff4(struct sk_buff *skb, __be32 from,
__be32 to)
@@ -48,5 +49,7 @@ static inline struct seg6_pernet_data *seg6_pernet(struct net
*net)
extern int seg6_init(void);
extern void seg6_exit(void);
+extern int seg6_iptunnel_init(void);
+extern void seg6_iptunnel_exit(void);
#endif
diff --git a/include/uapi/linux/lwtunnel.h b/include/uapi/linux/lwtunnel.h
index a478fe8..453cc62 100644
--- a/include/uapi/linux/lwtunnel.h
+++ b/include/uapi/linux/lwtunnel.h
@@ -9,6 +9,7 @@ enum lwtunnel_encap_types {
LWTUNNEL_ENCAP_IP,
LWTUNNEL_ENCAP_ILA,
LWTUNNEL_ENCAP_IP6,
+ LWTUNNEL_ENCAP_SEG6,
__LWTUNNEL_ENCAP_MAX,
};
diff --git a/include/uapi/linux/seg6_iptunnel.h
b/include/uapi/linux/seg6_iptunnel.h
new file mode 100644
index 0000000..da5524a
--- /dev/null
+++ b/include/uapi/linux/seg6_iptunnel.h
@@ -0,0 +1,41 @@
+/*
+ * SR-IPv6 implementation
+ *
+ * Author:
+ * David Lebrun <david.leb...@uclouvain.be>
+ *
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#ifndef _UAPI_LINUX_SEG6_IPTUNNEL_H
+#define _UAPI_LINUX_SEG6_IPTUNNEL_H
+
+enum {
+ SEG6_IPTUNNEL_UNSPEC,
+ SEG6_IPTUNNEL_SRH,
+ __SEG6_IPTUNNEL_MAX,
+};
+#define SEG6_IPTUNNEL_MAX (__SEG6_IPTUNNEL_MAX - 1)
+
+struct seg6_iptunnel_encap {
+ int flags;
+ struct ipv6_sr_hdr srh[0];
+};
+
+#define SEG6_IPTUN_ENCAP_SIZE(x) ((sizeof(*x)) + (((x)->srh->hdrlen + 1) << 3))
+
+#define SEG6_IPTUN_FLAG_ENCAP 0x1
+
+static inline size_t seg6_lwt_headroom(struct seg6_iptunnel_encap *tuninfo)
+{
+ int encap = !!(tuninfo->flags & SEG6_IPTUN_FLAG_ENCAP);
+
+ return ((tuninfo->srh->hdrlen + 1) << 3) +
+ (encap * sizeof(struct ipv6hdr));
+}
+
+#endif
diff --git a/net/core/lwtunnel.c b/net/core/lwtunnel.c
index 88fd642..03976e9 100644
--- a/net/core/lwtunnel.c
+++ b/net/core/lwtunnel.c
@@ -39,6 +39,8 @@ static const char *lwtunnel_encap_str(enum
lwtunnel_encap_types encap_type)
return "MPLS";
case LWTUNNEL_ENCAP_ILA:
return "ILA";
+ case LWTUNNEL_ENCAP_SEG6:
+ return "SEG6";
case LWTUNNEL_ENCAP_IP6:
case LWTUNNEL_ENCAP_IP:
case LWTUNNEL_ENCAP_NONE:
diff --git a/net/ipv6/Makefile b/net/ipv6/Makefile
index c92010d..59ee92f 100644
--- a/net/ipv6/Makefile
+++ b/net/ipv6/Makefile
@@ -9,7 +9,7 @@ ipv6-objs := af_inet6.o anycast.o ip6_output.o ip6_input.o
addrconf.o \
route.o ip6_fib.o ipv6_sockglue.o ndisc.o udp.o udplite.o \
raw.o icmp.o mcast.o reassembly.o tcp_ipv6.o ping.o \
exthdrs.o datagram.o ip6_flowlabel.o inet6_connection_sock.o \
- udp_offload.o seg6.o
+ udp_offload.o seg6.o seg6_iptunnel.o
ipv6-offload := ip6_offload.o tcpv6_offload.o exthdrs_offload.o
diff --git a/net/ipv6/seg6.c b/net/ipv6/seg6.c
index 9256e6e..8114ece 100644
--- a/net/ipv6/seg6.c
+++ b/net/ipv6/seg6.c
@@ -198,10 +198,16 @@ 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 +215,7 @@ int __init seg6_init(void)
void seg6_exit(void)
{
+ seg6_iptunnel_exit();
unregister_pernet_subsys(&ip6_segments_ops);
genl_unregister_family(&seg6_genl_family);
}
diff --git a/net/ipv6/seg6_iptunnel.c b/net/ipv6/seg6_iptunnel.c
new file mode 100644
index 0000000..9abeb45
--- /dev/null
+++ b/net/ipv6/seg6_iptunnel.c
@@ -0,0 +1,380 @@
+/*
+ * SR-IPv6 implementation
+ *
+ * Author:
+ * David Lebrun <david.leb...@uclouvain.be>
+ *
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/types.h>
+#include <linux/skbuff.h>
+#include <linux/net.h>
+#include <linux/module.h>
+#include <net/ip.h>
+#include <net/lwtunnel.h>
+#include <net/netevent.h>
+#include <net/netns/generic.h>
+#include <net/ip6_fib.h>
+#include <net/route.h>
+#include <net/seg6.h>
+#include <linux/seg6.h>
+#include <linux/seg6_iptunnel.h>
+#include <net/addrconf.h>
+#include <net/ip6_route.h>
+#ifdef CONFIG_DST_CACHE
+#include <net/dst_cache.h>
+#endif
+
+struct seg6_lwt {
+#ifdef CONFIG_DST_CACHE
+ struct dst_cache cache;
+#endif
+ struct seg6_iptunnel_encap tuninfo[0];
+};
+
+static inline struct seg6_lwt *seg6_lwt_lwtunnel(struct lwtunnel_state *lwt)
+{
+ return (struct seg6_lwt *)lwt->data;
+}
+
+static inline struct seg6_iptunnel_encap *
+seg6_encap_lwtunnel(struct lwtunnel_state *lwt)
+{
+ return seg6_lwt_lwtunnel(lwt)->tuninfo;
+}
+
+static const struct nla_policy seg6_iptunnel_policy[SEG6_IPTUNNEL_MAX + 1] = {
+ [SEG6_IPTUNNEL_SRH] = { .type = NLA_BINARY },
+};
+
+int nla_put_srh(struct sk_buff *skb, int attrtype,
+ struct seg6_iptunnel_encap *tuninfo)
+{
+ struct seg6_iptunnel_encap *data;
+ struct nlattr *nla;
+ int len;
+
+ len = SEG6_IPTUN_ENCAP_SIZE(tuninfo);
+
+ nla = nla_reserve(skb, attrtype, len);
+ if (!nla)
+ return -EMSGSIZE;
+
+ data = nla_data(nla);
+ memcpy(data, tuninfo, len);
+
+ return 0;
+}
+
+static void set_tun_src(struct net *net, struct net_device *dev,
+ struct in6_addr *daddr, struct in6_addr *saddr)
+{
+ struct seg6_pernet_data *sdata = seg6_pernet(net);
+ struct in6_addr *tun_src;
+
+ rcu_read_lock();
+
+ tun_src = rcu_dereference(sdata->tun_src);
+
+ if (!ipv6_addr_any(tun_src)) {
+ memcpy(saddr, tun_src, sizeof(struct in6_addr));
+ } else {
+ ipv6_dev_get_saddr(net, dev, daddr, IPV6_PREFER_SRC_PUBLIC,
+ saddr);
+ }
+
+ rcu_read_unlock();
+}
+
+/* encapsulate an IPv6 packet within an outer IPv6 header with a given SRH */
+static int seg6_do_srh_encap(struct sk_buff *skb, struct ipv6_sr_hdr *osrh)
+{
+ struct net *net = dev_net(skb_dst(skb)->dev);
+ struct ipv6hdr *hdr, *inner_hdr;
+ struct ipv6_sr_hdr *isrh;
+ int hdrlen, tot_len, err;
+
+ hdrlen = (osrh->hdrlen + 1) << 3;
+ tot_len = hdrlen + sizeof(*hdr);
+
+ err = pskb_expand_head(skb, tot_len, 0, GFP_ATOMIC);
+ if (unlikely(err))
+ return err;
+
+ inner_hdr = ipv6_hdr(skb);
+
+ skb_push(skb, tot_len);
+ skb_reset_network_header(skb);
+ skb_mac_header_rebuild(skb);
+ hdr = ipv6_hdr(skb);
+
+ /* inherit tc, flowlabel and hlim
+ * hlim will be decremented in ip6_forward() afterwards and
+ * decapsulation will overwrite inner hlim with outer hlim
+ */
+ ip6_flow_hdr(hdr, ip6_tclass(ip6_flowinfo(inner_hdr)),
+ ip6_flowlabel(inner_hdr));
+ hdr->hop_limit = inner_hdr->hop_limit;
+ hdr->nexthdr = NEXTHDR_ROUTING;
+
+ isrh = (void *)hdr + sizeof(*hdr);
+ memcpy(isrh, osrh, hdrlen);
+
+ isrh->nexthdr = NEXTHDR_IPV6;
+
+ hdr->daddr = isrh->segments[isrh->first_segment];
+ set_tun_src(net, skb->dev, &hdr->daddr, &hdr->saddr);
+
+ skb_postpush_rcsum(skb, hdr, tot_len);
+
+ return 0;
+}
+
+/* insert an SRH within an IPv6 packet, just after the IPv6 header */
+static int seg6_do_srh_inline(struct sk_buff *skb, struct ipv6_sr_hdr *osrh)
+{
+ struct ipv6hdr *hdr, *oldhdr;
+ struct ipv6_sr_hdr *isrh;
+ int hdrlen, err;
+
+ hdrlen = (osrh->hdrlen + 1) << 3;
+
+ err = pskb_expand_head(skb, hdrlen, 0, GFP_ATOMIC);
+ if (unlikely(err))
+ return err;
+
+ oldhdr = ipv6_hdr(skb);
+
+ skb_pull(skb, sizeof(struct ipv6hdr));
+ skb_postpull_rcsum(skb, skb_network_header(skb),
+ sizeof(struct ipv6hdr));
+
+ skb_push(skb, sizeof(struct ipv6hdr) + hdrlen);
+ skb_reset_network_header(skb);
+ skb_mac_header_rebuild(skb);
+
+ hdr = ipv6_hdr(skb);
+
+ memmove(hdr, oldhdr, sizeof(*hdr));
+
+ isrh = (void *)hdr + sizeof(*hdr);
+ memcpy(isrh, osrh, hdrlen);
+
+ isrh->nexthdr = hdr->nexthdr;
+ hdr->nexthdr = NEXTHDR_ROUTING;
+
+ isrh->segments[0] = hdr->daddr;
+ hdr->daddr = isrh->segments[isrh->first_segment];
+
+ skb_postpush_rcsum(skb, hdr, sizeof(struct ipv6hdr) + hdrlen);
+
+ return 0;
+}
+
+static int seg6_do_srh(struct sk_buff *skb)
+{
+ struct dst_entry *dst = skb_dst(skb);
+ struct seg6_iptunnel_encap *tinfo;
+ int err = 0;
+
+ tinfo = seg6_encap_lwtunnel(dst->lwtstate);
+
+ if (likely(!skb->encapsulation)) {
+ skb_reset_inner_headers(skb);
+ skb->encapsulation = 1;
+ }
+
+ if (tinfo->flags & SEG6_IPTUN_FLAG_ENCAP) {
+ err = seg6_do_srh_encap(skb, tinfo->srh);
+ } else {
+ err = seg6_do_srh_inline(skb, tinfo->srh);
+ skb_reset_inner_headers(skb);
+ }
+
+ if (err)
+ return err;
+
+ ipv6_hdr(skb)->payload_len = htons(skb->len - sizeof(struct ipv6hdr));
+ skb_set_transport_header(skb, sizeof(struct ipv6hdr));
+
+ skb_set_inner_protocol(skb, skb->protocol);
+
+ return 0;
+}
+
+int seg6_input(struct sk_buff *skb)
+{
+ int err;
+
+ err = seg6_do_srh(skb);
+ if (unlikely(err)) {
+ kfree_skb(skb);
+ return err;
+ }
+
+ skb_dst_drop(skb);
+ ip6_route_input(skb);
+
+ return dst_input(skb);
+}
+
+int seg6_output(struct net *net, struct sock *sk, struct sk_buff *skb)
+{
+ struct dst_entry *orig_dst = skb_dst(skb);
+ struct dst_entry *dst = NULL;
+ struct seg6_lwt *slwt;
+ int err = -EINVAL;
+
+ err = seg6_do_srh(skb);
+ if (unlikely(err))
+ goto drop;
+
+ slwt = seg6_lwt_lwtunnel(orig_dst->lwtstate);
+
+#ifdef CONFIG_DST_CACHE
+ dst = dst_cache_get(&slwt->cache);
+#endif
+
+ if (unlikely(!dst)) {
+ struct ipv6hdr *hdr = ipv6_hdr(skb);
+ struct flowi6 fl6;
+
+ fl6.daddr = hdr->daddr;
+ fl6.saddr = hdr->saddr;
+ fl6.flowlabel = ip6_flowinfo(hdr);
+ fl6.flowi6_mark = skb->mark;
+ fl6.flowi6_proto = hdr->nexthdr;
+
+ dst = ip6_route_output(net, NULL, &fl6);
+ if (dst->error) {
+ err = dst->error;
+ dst_release(dst);
+ goto drop;
+ }
+
+#ifdef CONFIG_DST_CACHE
+ dst_cache_set_ip6(&slwt->cache, dst, &fl6.saddr);
+#endif
+ }
+
+ skb_dst_drop(skb);
+ skb_dst_set(skb, dst);
+
+ return dst_output(net, sk, skb);
+drop:
+ kfree_skb(skb);
+ return err;
+}
+
+static int seg6_build_state(struct net_device *dev, struct nlattr *nla,
+ unsigned int family, const void *cfg,
+ struct lwtunnel_state **ts)
+{
+ struct nlattr *tb[SEG6_IPTUNNEL_MAX + 1];
+ struct seg6_iptunnel_encap *tuninfo;
+ struct lwtunnel_state *newts;
+ struct seg6_lwt *slwt;
+ int tuninfo_len;
+ int err;
+
+ err = nla_parse_nested(tb, SEG6_IPTUNNEL_MAX, nla,
+ seg6_iptunnel_policy);
+
+ if (err < 0)
+ return err;
+
+ if (!tb[SEG6_IPTUNNEL_SRH])
+ return -EINVAL;
+
+ tuninfo = nla_data(tb[SEG6_IPTUNNEL_SRH]);
+ tuninfo_len = SEG6_IPTUN_ENCAP_SIZE(tuninfo);
+
+ newts = lwtunnel_state_alloc(tuninfo_len + sizeof(*slwt));
+ if (!newts)
+ return -ENOMEM;
+
+ slwt = seg6_lwt_lwtunnel(newts);
+
+#ifdef CONFIG_DST_CACHE
+ err = dst_cache_init(&slwt->cache, GFP_KERNEL);
+ if (err) {
+ kfree(newts);
+ return err;
+ }
+#endif
+
+ memcpy(&slwt->tuninfo, tuninfo, tuninfo_len);
+
+ newts->type = LWTUNNEL_ENCAP_SEG6;
+ newts->flags |= LWTUNNEL_STATE_OUTPUT_REDIRECT |
+ LWTUNNEL_STATE_INPUT_REDIRECT;
+ newts->headroom = seg6_lwt_headroom(tuninfo);
+
+ *ts = newts;
+
+ return 0;
+}
+
+#ifdef CONFIG_DST_CACHE
+static void seg6_destroy_state(struct lwtunnel_state *lwt)
+{
+ dst_cache_destroy(&seg6_lwt_lwtunnel(lwt)->cache);
+}
+#endif
+
+static int seg6_fill_encap_info(struct sk_buff *skb,
+ struct lwtunnel_state *lwtstate)
+{
+ struct seg6_iptunnel_encap *tuninfo = seg6_encap_lwtunnel(lwtstate);
+
+ if (nla_put_srh(skb, SEG6_IPTUNNEL_SRH, tuninfo))
+ return -EMSGSIZE;
+
+ return 0;
+}
+
+static int seg6_encap_nlsize(struct lwtunnel_state *lwtstate)
+{
+ struct seg6_iptunnel_encap *tuninfo = seg6_encap_lwtunnel(lwtstate);
+
+ return nla_total_size(SEG6_IPTUN_ENCAP_SIZE(tuninfo));
+}
+
+static int seg6_encap_cmp(struct lwtunnel_state *a, struct lwtunnel_state *b)
+{
+ struct seg6_iptunnel_encap *a_hdr = seg6_encap_lwtunnel(a);
+ struct seg6_iptunnel_encap *b_hdr = seg6_encap_lwtunnel(b);
+ int len = SEG6_IPTUN_ENCAP_SIZE(a_hdr);
+
+ if (len != SEG6_IPTUN_ENCAP_SIZE(b_hdr))
+ return 1;
+
+ return memcmp(a_hdr, b_hdr, len);
+}
+
+static const struct lwtunnel_encap_ops seg6_iptun_ops = {
+ .build_state = seg6_build_state,
+#ifdef CONFIG_DST_CACHE
+ .destroy_state = seg6_destroy_state,
+#endif
+ .output = seg6_output,
+ .input = seg6_input,
+ .fill_encap = seg6_fill_encap_info,
+ .get_encap_size = seg6_encap_nlsize,
+ .cmp_encap = seg6_encap_cmp,
+};
+
+int __init seg6_iptunnel_init(void)
+{
+ return lwtunnel_encap_add_ops(&seg6_iptun_ops, LWTUNNEL_ENCAP_SEG6);
+}
+
+void seg6_iptunnel_exit(void)
+{
+ lwtunnel_encap_del_ops(&seg6_iptun_ops, LWTUNNEL_ENCAP_SEG6);
+}
--
2.7.3
