1 files changed, 526 insertions, 0 deletions
diff --git a/net/ipv6/seg6_iptunnel.c b/net/ipv6/seg6_iptunnel.c
new file mode 100644
index 000000000..26882fd93
--- /dev/null
+++ b/net/ipv6/seg6_iptunnel.c
@@ -0,0 +1,526 @@
+/*
+ *  SR-IPv6 implementation
+ *
+ *  Author:
+ *  David Lebrun <david.lebrun@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/ip_tunnels.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>
+#include <net/dst_cache.h>
+#ifdef CONFIG_IPV6_SEG6_HMAC
+#include <net/seg6_hmac.h>
+#endif
+
+struct seg6_lwt {
+	struct dst_cache cache;
+	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 },
+};
+
+static 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();
+}
+
+/* Compute flowlabel for outer IPv6 header */
+static __be32 seg6_make_flowlabel(struct net *net, struct sk_buff *skb,
+				  struct ipv6hdr *inner_hdr)
+{
+	int do_flowlabel = net->ipv6.sysctl.seg6_flowlabel;
+	__be32 flowlabel = 0;
+	u32 hash;
+
+	if (do_flowlabel > 0) {
+		hash = skb_get_hash(skb);
+		hash = rol32(hash, 16);
+		flowlabel = (__force __be32)hash & IPV6_FLOWLABEL_MASK;
+	} else if (!do_flowlabel && skb->protocol == htons(ETH_P_IPV6)) {
+		flowlabel = ip6_flowlabel(inner_hdr);
+	}
+	return flowlabel;
+}
+
+/* encapsulate an IPv6 packet within an outer IPv6 header with a given SRH */
+int seg6_do_srh_encap(struct sk_buff *skb, struct ipv6_sr_hdr *osrh, int proto)
+{
+	struct dst_entry *dst = skb_dst(skb);
+	struct net *net = dev_net(dst->dev);
+	struct ipv6hdr *hdr, *inner_hdr;
+	struct ipv6_sr_hdr *isrh;
+	int hdrlen, tot_len, err;
+	__be32 flowlabel;
+
+	hdrlen = (osrh->hdrlen + 1) << 3;
+	tot_len = hdrlen + sizeof(*hdr);
+
+	err = skb_cow_head(skb, tot_len + skb->mac_len);
+	if (unlikely(err))
+		return err;
+
+	inner_hdr = ipv6_hdr(skb);
+	flowlabel = seg6_make_flowlabel(net, skb, inner_hdr);
+
+	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
+	 */
+
+	if (skb->protocol == htons(ETH_P_IPV6)) {
+		ip6_flow_hdr(hdr, ip6_tclass(ip6_flowinfo(inner_hdr)),
+			     flowlabel);
+		hdr->hop_limit = inner_hdr->hop_limit;
+	} else {
+		ip6_flow_hdr(hdr, 0, flowlabel);
+		hdr->hop_limit = ip6_dst_hoplimit(skb_dst(skb));
+
+		memset(IP6CB(skb), 0, sizeof(*IP6CB(skb)));
+
+		/* the control block has been erased, so we have to set the
+		 * iif once again.
+		 * We read the receiving interface index directly from the
+		 * skb->skb_iif as it is done in the IPv4 receiving path (i.e.:
+		 * ip_rcv_core(...)).
+		 */
+		IP6CB(skb)->iif = skb->skb_iif;
+	}
+
+	hdr->nexthdr = NEXTHDR_ROUTING;
+
+	isrh = (void *)hdr + sizeof(*hdr);
+	memcpy(isrh, osrh, hdrlen);
+
+	isrh->nexthdr = proto;
+
+	hdr->daddr = isrh->segments[isrh->first_segment];
+	set_tun_src(net, dst->dev, &hdr->daddr, &hdr->saddr);
+
+#ifdef CONFIG_IPV6_SEG6_HMAC
+	if (sr_has_hmac(isrh)) {
+		err = seg6_push_hmac(net, &hdr->saddr, isrh);
+		if (unlikely(err))
+			return err;
+	}
+#endif
+
+	skb_postpush_rcsum(skb, hdr, tot_len);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(seg6_do_srh_encap);
+
+/* insert an SRH within an IPv6 packet, just after the IPv6 header */
+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 = skb_cow_head(skb, hdrlen + skb->mac_len);
+	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];
+
+#ifdef CONFIG_IPV6_SEG6_HMAC
+	if (sr_has_hmac(isrh)) {
+		struct net *net = dev_net(skb_dst(skb)->dev);
+
+		err = seg6_push_hmac(net, &hdr->saddr, isrh);
+		if (unlikely(err))
+			return err;
+	}
+#endif
+
+	skb_postpush_rcsum(skb, hdr, sizeof(struct ipv6hdr) + hdrlen);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(seg6_do_srh_inline);
+
+static int seg6_do_srh(struct sk_buff *skb)
+{
+	struct dst_entry *dst = skb_dst(skb);
+	struct seg6_iptunnel_encap *tinfo;
+	int proto, err = 0;
+
+	tinfo = seg6_encap_lwtunnel(dst->lwtstate);
+
+	switch (tinfo->mode) {
+	case SEG6_IPTUN_MODE_INLINE:
+		if (skb->protocol != htons(ETH_P_IPV6))
+			return -EINVAL;
+
+		err = seg6_do_srh_inline(skb, tinfo->srh);
+		if (err)
+			return err;
+		break;
+	case SEG6_IPTUN_MODE_ENCAP:
+		err = iptunnel_handle_offloads(skb, SKB_GSO_IPXIP6);
+		if (err)
+			return err;
+
+		if (skb->protocol == htons(ETH_P_IPV6))
+			proto = IPPROTO_IPV6;
+		else if (skb->protocol == htons(ETH_P_IP))
+			proto = IPPROTO_IPIP;
+		else
+			return -EINVAL;
+
+		err = seg6_do_srh_encap(skb, tinfo->srh, proto);
+		if (err)
+			return err;
+
+		skb_set_inner_transport_header(skb, skb_transport_offset(skb));
+		skb_set_inner_protocol(skb, skb->protocol);
+		skb->protocol = htons(ETH_P_IPV6);
+		break;
+	case SEG6_IPTUN_MODE_L2ENCAP:
+		if (!skb_mac_header_was_set(skb))
+			return -EINVAL;
+
+		if (pskb_expand_head(skb, skb->mac_len, 0, GFP_ATOMIC) < 0)
+			return -ENOMEM;
+
+		skb_mac_header_rebuild(skb);
+		skb_push(skb, skb->mac_len);
+
+		err = seg6_do_srh_encap(skb, tinfo->srh, NEXTHDR_NONE);
+		if (err)
+			return err;
+
+		skb->protocol = htons(ETH_P_IPV6);
+		break;
+	}
+
+	ipv6_hdr(skb)->payload_len = htons(skb->len - sizeof(struct ipv6hdr));
+	skb_set_transport_header(skb, sizeof(struct ipv6hdr));
+
+	return 0;
+}
+
+static int seg6_input(struct sk_buff *skb)
+{
+	struct dst_entry *orig_dst = skb_dst(skb);
+	struct dst_entry *dst = NULL;
+	struct seg6_lwt *slwt;
+	int err;
+
+	err = seg6_do_srh(skb);
+	if (unlikely(err)) {
+		kfree_skb(skb);
+		return err;
+	}
+
+	slwt = seg6_lwt_lwtunnel(orig_dst->lwtstate);
+
+	preempt_disable();
+	dst = dst_cache_get(&slwt->cache);
+	preempt_enable();
+
+	skb_dst_drop(skb);
+
+	if (!dst) {
+		ip6_route_input(skb);
+		dst = skb_dst(skb);
+		if (!dst->error) {
+			preempt_disable();
+			dst_cache_set_ip6(&slwt->cache, dst,
+					  &ipv6_hdr(skb)->saddr);
+			preempt_enable();
+		}
+	} else {
+		skb_dst_set(skb, dst);
+	}
+
+	err = skb_cow_head(skb, LL_RESERVED_SPACE(dst->dev));
+	if (unlikely(err))
+		return err;
+
+	return dst_input(skb);
+}
+
+static 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);
+
+	preempt_disable();
+	dst = dst_cache_get(&slwt->cache);
+	preempt_enable();
+
+	if (unlikely(!dst)) {
+		struct ipv6hdr *hdr = ipv6_hdr(skb);
+		struct flowi6 fl6;
+
+		memset(&fl6, 0, sizeof(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;
+		}
+
+		preempt_disable();
+		dst_cache_set_ip6(&slwt->cache, dst, &fl6.saddr);
+		preempt_enable();
+	}
+
+	skb_dst_drop(skb);
+	skb_dst_set(skb, dst);
+
+	err = skb_cow_head(skb, LL_RESERVED_SPACE(dst->dev));
+	if (unlikely(err))
+		goto drop;
+
+	return dst_output(net, sk, skb);
+drop:
+	kfree_skb(skb);
+	return err;
+}
+
+static int seg6_build_state(struct nlattr *nla,
+			    unsigned int family, const void *cfg,
+			    struct lwtunnel_state **ts,
+			    struct netlink_ext_ack *extack)
+{
+	struct nlattr *tb[SEG6_IPTUNNEL_MAX + 1];
+	struct seg6_iptunnel_encap *tuninfo;
+	struct lwtunnel_state *newts;
+	int tuninfo_len, min_size;
+	struct seg6_lwt *slwt;
+	int err;
+
+	if (family != AF_INET && family != AF_INET6)
+		return -EINVAL;
+
+	err = nla_parse_nested(tb, SEG6_IPTUNNEL_MAX, nla,
+			       seg6_iptunnel_policy, extack);
+
+	if (err < 0)
+		return err;
+
+	if (!tb[SEG6_IPTUNNEL_SRH])
+		return -EINVAL;
+
+	tuninfo = nla_data(tb[SEG6_IPTUNNEL_SRH]);
+	tuninfo_len = nla_len(tb[SEG6_IPTUNNEL_SRH]);
+
+	/* tuninfo must contain at least the iptunnel encap structure,
+	 * the SRH and one segment
+	 */
+	min_size = sizeof(*tuninfo) + sizeof(struct ipv6_sr_hdr) +
+		   sizeof(struct in6_addr);
+	if (tuninfo_len < min_size)
+		return -EINVAL;
+
+	switch (tuninfo->mode) {
+	case SEG6_IPTUN_MODE_INLINE:
+		if (family != AF_INET6)
+			return -EINVAL;
+
+		break;
+	case SEG6_IPTUN_MODE_ENCAP:
+		break;
+	case SEG6_IPTUN_MODE_L2ENCAP:
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	/* verify that SRH is consistent */
+	if (!seg6_validate_srh(tuninfo->srh, tuninfo_len - sizeof(*tuninfo)))
+		return -EINVAL;
+
+	newts = lwtunnel_state_alloc(tuninfo_len + sizeof(*slwt));
+	if (!newts)
+		return -ENOMEM;
+
+	slwt = seg6_lwt_lwtunnel(newts);
+
+	err = dst_cache_init(&slwt->cache, GFP_ATOMIC);
+	if (err) {
+		kfree(newts);
+		return err;
+	}
+
+	memcpy(&slwt->tuninfo, tuninfo, tuninfo_len);
+
+	newts->type = LWTUNNEL_ENCAP_SEG6;
+	newts->flags |= LWTUNNEL_STATE_INPUT_REDIRECT;
+
+	if (tuninfo->mode != SEG6_IPTUN_MODE_L2ENCAP)
+		newts->flags |= LWTUNNEL_STATE_OUTPUT_REDIRECT;
+
+	newts->headroom = seg6_lwt_headroom(tuninfo);
+
+	*ts = newts;
+
+	return 0;
+}
+
+static void seg6_destroy_state(struct lwtunnel_state *lwt)
+{
+	dst_cache_destroy(&seg6_lwt_lwtunnel(lwt)->cache);
+}
+
+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,
+	.destroy_state = seg6_destroy_state,
+	.output = seg6_output,
+	.input = seg6_input,
+	.fill_encap = seg6_fill_encap_info,
+	.get_encap_size = seg6_encap_nlsize,
+	.cmp_encap = seg6_encap_cmp,
+	.owner = THIS_MODULE,
+};
+
+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);
+}