net/ipv6/rpl_iptunnel.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * Authors:
  * (C) 2020 Alexander Aring <alex.aring@gmail.com>
  */

 #include <linux/rpl_iptunnel.h>

 #include <net/dst_cache.h>
 #include <net/ip6_route.h>
 #include <net/lwtunnel.h>
 #include <net/ipv6.h>
 #include <net/rpl.h>

 struct rpl_iptunnel_encap {
 	DECLARE_FLEX_ARRAY(struct ipv6_rpl_sr_hdr, srh);
 };

 struct rpl_lwt {
 	struct dst_cache cache;
 	struct rpl_iptunnel_encap tuninfo;
 };

 static inline struct rpl_lwt *rpl_lwt_lwtunnel(struct lwtunnel_state *lwt)
 {
 	return (struct rpl_lwt *)lwt->data;
 }

 static inline struct rpl_iptunnel_encap *
 rpl_encap_lwtunnel(struct lwtunnel_state *lwt)
 {
 	return &rpl_lwt_lwtunnel(lwt)->tuninfo;
 }

 static const struct nla_policy rpl_iptunnel_policy[RPL_IPTUNNEL_MAX + 1] = {
 	[RPL_IPTUNNEL_SRH]	= { .type = NLA_BINARY },
 };

 static bool rpl_validate_srh(struct net *net, struct ipv6_rpl_sr_hdr *srh,
 			     size_t seglen)
 {
 	int err;

 	if ((srh->hdrlen << 3) != seglen)
 		return false;

 	/* check at least one segment and seglen fit with segments_left */
 	if (!srh->segments_left ||
 	    (srh->segments_left * sizeof(struct in6_addr)) != seglen)
 		return false;

 	if (srh->cmpri || srh->cmpre)
 		return false;

 	err = ipv6_chk_rpl_srh_loop(net, srh->rpl_segaddr,
 				    srh->segments_left);
 	if (err)
 		return false;

 	if (ipv6_addr_type(&srh->rpl_segaddr[srh->segments_left - 1]) &
 	    IPV6_ADDR_MULTICAST)
 		return false;

 	return true;
 }

 static int rpl_build_state(struct net *net, struct nlattr *nla,
 			   unsigned int family, const void *cfg,
 			   struct lwtunnel_state **ts,
 			   struct netlink_ext_ack *extack)
 {
 	struct nlattr *tb[RPL_IPTUNNEL_MAX + 1];
 	struct lwtunnel_state *newts;
 	struct ipv6_rpl_sr_hdr *srh;
 	struct rpl_lwt *rlwt;
 	int err, srh_len;

 	if (family != AF_INET6)
 		return -EINVAL;

 	err = nla_parse_nested(tb, RPL_IPTUNNEL_MAX, nla,
 			       rpl_iptunnel_policy, extack);
 	if (err < 0)
 		return err;

 	if (!tb[RPL_IPTUNNEL_SRH])
 		return -EINVAL;

 	srh = nla_data(tb[RPL_IPTUNNEL_SRH]);
 	srh_len = nla_len(tb[RPL_IPTUNNEL_SRH]);

 	if (srh_len < sizeof(*srh))
 		return -EINVAL;

 	/* verify that SRH is consistent */
 	if (!rpl_validate_srh(net, srh, srh_len - sizeof(*srh)))
 		return -EINVAL;

 	newts = lwtunnel_state_alloc(srh_len + sizeof(*rlwt));
 	if (!newts)
 		return -ENOMEM;

 	rlwt = rpl_lwt_lwtunnel(newts);

 	err = dst_cache_init(&rlwt->cache, GFP_ATOMIC);
 	if (err) {
 		kfree(newts);
 		return err;
 	}

 	memcpy(&rlwt->tuninfo.srh, srh, srh_len);

 	newts->type = LWTUNNEL_ENCAP_RPL;
 	newts->flags |= LWTUNNEL_STATE_INPUT_REDIRECT;
 	newts->flags |= LWTUNNEL_STATE_OUTPUT_REDIRECT;

 	*ts = newts;

 	return 0;
 }

 static void rpl_destroy_state(struct lwtunnel_state *lwt)
 {
 	dst_cache_destroy(&rpl_lwt_lwtunnel(lwt)->cache);
 }

 static int rpl_do_srh_inline(struct sk_buff *skb, const struct rpl_lwt *rlwt,
 			     const struct ipv6_rpl_sr_hdr *srh)
 {
 	struct ipv6_rpl_sr_hdr *isrh, *csrh;
 	const struct ipv6hdr *oldhdr;
 	struct ipv6hdr *hdr;
 	unsigned char *buf;
 	size_t hdrlen;
 	int err;

 	oldhdr = ipv6_hdr(skb);

 	buf = kcalloc(struct_size(srh, segments.addr, srh->segments_left), 2, GFP_ATOMIC);
 	if (!buf)
 		return -ENOMEM;

 	isrh = (struct ipv6_rpl_sr_hdr *)buf;
 	csrh = (struct ipv6_rpl_sr_hdr *)(buf + ((srh->hdrlen + 1) << 3));

 	memcpy(isrh, srh, sizeof(*isrh));
 	memcpy(isrh->rpl_segaddr, &srh->rpl_segaddr[1],
 	       (srh->segments_left - 1) * 16);
 	isrh->rpl_segaddr[srh->segments_left - 1] = oldhdr->daddr;

 	ipv6_rpl_srh_compress(csrh, isrh, &srh->rpl_segaddr[0],
 			      isrh->segments_left - 1);

 	hdrlen = ((csrh->hdrlen + 1) << 3);

 	err = skb_cow_head(skb, hdrlen + skb->mac_len);
 	if (unlikely(err)) {
 		kfree(buf);
 		return err;
 	}

 	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, csrh, hdrlen);

 	isrh->nexthdr = hdr->nexthdr;
 	hdr->nexthdr = NEXTHDR_ROUTING;
 	hdr->daddr = srh->rpl_segaddr[0];

 	ipv6_hdr(skb)->payload_len = htons(skb->len - sizeof(struct ipv6hdr));
 	skb_set_transport_header(skb, sizeof(struct ipv6hdr));

 	skb_postpush_rcsum(skb, hdr, sizeof(struct ipv6hdr) + hdrlen);

 	kfree(buf);

 	return 0;
 }

 static int rpl_do_srh(struct sk_buff *skb, const struct rpl_lwt *rlwt)
 {
 	struct dst_entry *dst = skb_dst(skb);
 	struct rpl_iptunnel_encap *tinfo;

 	if (skb->protocol != htons(ETH_P_IPV6))
 		return -EINVAL;

 	tinfo = rpl_encap_lwtunnel(dst->lwtstate);

 	return rpl_do_srh_inline(skb, rlwt, tinfo->srh);
 }

 static int rpl_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 rpl_lwt *rlwt;
 	int err;

 	rlwt = rpl_lwt_lwtunnel(orig_dst->lwtstate);

 	err = rpl_do_srh(skb, rlwt);
 	if (unlikely(err))
 		goto drop;

 	preempt_disable();
 	dst = dst_cache_get(&rlwt->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(&rlwt->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 rpl_input(struct sk_buff *skb)
 {
 	struct dst_entry *orig_dst = skb_dst(skb);
 	struct dst_entry *dst = NULL;
 	struct rpl_lwt *rlwt;
 	int err;

 	rlwt = rpl_lwt_lwtunnel(orig_dst->lwtstate);

 	err = rpl_do_srh(skb, rlwt);
 	if (unlikely(err)) {
 		kfree_skb(skb);
 		return err;
 	}

 	preempt_disable();
 	dst = dst_cache_get(&rlwt->cache);
 	preempt_enable();

 	if (!dst) {
 		ip6_route_input(skb);
 		dst = skb_dst(skb);
 		if (!dst->error) {
 			preempt_disable();
 			dst_cache_set_ip6(&rlwt->cache, dst,
 					  &ipv6_hdr(skb)->saddr);
 			preempt_enable();
 		}
 	} else {
 		skb_dst_drop(skb);
 		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 nla_put_rpl_srh(struct sk_buff *skb, int attrtype,
 			   struct rpl_iptunnel_encap *tuninfo)
 {
 	struct rpl_iptunnel_encap *data;
 	struct nlattr *nla;
 	int len;

 	len = RPL_IPTUNNEL_SRH_SIZE(tuninfo->srh);

 	nla = nla_reserve(skb, attrtype, len);
 	if (!nla)
 		return -EMSGSIZE;

 	data = nla_data(nla);
 	memcpy(data, tuninfo->srh, len);

 	return 0;
 }

 static int rpl_fill_encap_info(struct sk_buff *skb,
 			       struct lwtunnel_state *lwtstate)
 {
 	struct rpl_iptunnel_encap *tuninfo = rpl_encap_lwtunnel(lwtstate);

 	if (nla_put_rpl_srh(skb, RPL_IPTUNNEL_SRH, tuninfo))
 		return -EMSGSIZE;

 	return 0;
 }

 static int rpl_encap_nlsize(struct lwtunnel_state *lwtstate)
 {
 	struct rpl_iptunnel_encap *tuninfo = rpl_encap_lwtunnel(lwtstate);

 	return nla_total_size(RPL_IPTUNNEL_SRH_SIZE(tuninfo->srh));
 }

 static int rpl_encap_cmp(struct lwtunnel_state *a, struct lwtunnel_state *b)
 {
 	struct rpl_iptunnel_encap *a_hdr = rpl_encap_lwtunnel(a);
 	struct rpl_iptunnel_encap *b_hdr = rpl_encap_lwtunnel(b);
 	int len = RPL_IPTUNNEL_SRH_SIZE(a_hdr->srh);

 	if (len != RPL_IPTUNNEL_SRH_SIZE(b_hdr->srh))
 		return 1;

 	return memcmp(a_hdr, b_hdr, len);
 }

 static const struct lwtunnel_encap_ops rpl_ops = {
 	.build_state	= rpl_build_state,
 	.destroy_state	= rpl_destroy_state,
 	.output		= rpl_output,
 	.input		= rpl_input,
 	.fill_encap	= rpl_fill_encap_info,
 	.get_encap_size	= rpl_encap_nlsize,
 	.cmp_encap	= rpl_encap_cmp,
 	.owner		= THIS_MODULE,
 };

 int __init rpl_init(void)
 {
 	int err;

 	err = lwtunnel_encap_add_ops(&rpl_ops, LWTUNNEL_ENCAP_RPL);
 	if (err)
 		goto out;

 	pr_info("RPL Segment Routing with IPv6\n");

 	return 0;

 out:
 	return err;
 }

 void rpl_exit(void)
 {
 	lwtunnel_encap_del_ops(&rpl_ops, LWTUNNEL_ENCAP_RPL);
 }
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* Authors:
	* (C) 2020 Alexander Aring <alex.aring@gmail.com>
	*/

	#include <linux/rpl_iptunnel.h>

	#include <net/dst_cache.h>
	#include <net/ip6_route.h>
	#include <net/lwtunnel.h>
	#include <net/ipv6.h>
	#include <net/rpl.h>

	struct rpl_iptunnel_encap {
	DECLARE_FLEX_ARRAY(struct ipv6_rpl_sr_hdr, srh);
	};

	struct rpl_lwt {
	struct dst_cache cache;
	struct rpl_iptunnel_encap tuninfo;
	};

	static inline struct rpl_lwt rpl_lwt_lwtunnel(struct lwtunnel_state lwt)
	{
	return (struct rpl_lwt *)lwt->data;
	}

	static inline struct rpl_iptunnel_encap *
	rpl_encap_lwtunnel(struct lwtunnel_state *lwt)
	{
	return &rpl_lwt_lwtunnel(lwt)->tuninfo;
	}

	static const struct nla_policy rpl_iptunnel_policy[RPL_IPTUNNEL_MAX + 1] = {
	[RPL_IPTUNNEL_SRH] = { .type = NLA_BINARY },
	};

	static bool rpl_validate_srh(struct net net, struct ipv6_rpl_sr_hdr srh,
	size_t seglen)
	{
	int err;

	if ((srh->hdrlen << 3) != seglen)
	return false;

	/* check at least one segment and seglen fit with segments_left */
	if (!srh->segments_left \|\|
	(srh->segments_left * sizeof(struct in6_addr)) != seglen)
	return false;

	if (srh->cmpri \|\| srh->cmpre)
	return false;

	err = ipv6_chk_rpl_srh_loop(net, srh->rpl_segaddr,
	srh->segments_left);
	if (err)
	return false;

	if (ipv6_addr_type(&srh->rpl_segaddr[srh->segments_left - 1]) &
	IPV6_ADDR_MULTICAST)
	return false;

	return true;
	}

	static int rpl_build_state(struct net net, struct nlattr nla,
	unsigned int family, const void *cfg,
	struct lwtunnel_state **ts,
	struct netlink_ext_ack *extack)
	{
	struct nlattr *tb[RPL_IPTUNNEL_MAX + 1];
	struct lwtunnel_state *newts;
	struct ipv6_rpl_sr_hdr *srh;
	struct rpl_lwt *rlwt;
	int err, srh_len;

	if (family != AF_INET6)
	return -EINVAL;

	err = nla_parse_nested(tb, RPL_IPTUNNEL_MAX, nla,
	rpl_iptunnel_policy, extack);
	if (err < 0)
	return err;

	if (!tb[RPL_IPTUNNEL_SRH])
	return -EINVAL;

	srh = nla_data(tb[RPL_IPTUNNEL_SRH]);
	srh_len = nla_len(tb[RPL_IPTUNNEL_SRH]);

	if (srh_len < sizeof(*srh))
	return -EINVAL;

	/* verify that SRH is consistent */
	if (!rpl_validate_srh(net, srh, srh_len - sizeof(*srh)))
	return -EINVAL;

	newts = lwtunnel_state_alloc(srh_len + sizeof(*rlwt));
	if (!newts)
	return -ENOMEM;

	rlwt = rpl_lwt_lwtunnel(newts);

	err = dst_cache_init(&rlwt->cache, GFP_ATOMIC);
	if (err) {
	kfree(newts);
	return err;
	}

	memcpy(&rlwt->tuninfo.srh, srh, srh_len);

	newts->type = LWTUNNEL_ENCAP_RPL;
	newts->flags \|= LWTUNNEL_STATE_INPUT_REDIRECT;
	newts->flags \|= LWTUNNEL_STATE_OUTPUT_REDIRECT;

	*ts = newts;

	return 0;
	}

	static void rpl_destroy_state(struct lwtunnel_state *lwt)
	{
	dst_cache_destroy(&rpl_lwt_lwtunnel(lwt)->cache);
	}

	static int rpl_do_srh_inline(struct sk_buff skb, const struct rpl_lwt rlwt,
	const struct ipv6_rpl_sr_hdr *srh)
	{
	struct ipv6_rpl_sr_hdr isrh, csrh;
	const struct ipv6hdr *oldhdr;
	struct ipv6hdr *hdr;
	unsigned char *buf;
	size_t hdrlen;
	int err;

	oldhdr = ipv6_hdr(skb);

	buf = kcalloc(struct_size(srh, segments.addr, srh->segments_left), 2, GFP_ATOMIC);
	if (!buf)
	return -ENOMEM;

	isrh = (struct ipv6_rpl_sr_hdr *)buf;
	csrh = (struct ipv6_rpl_sr_hdr *)(buf + ((srh->hdrlen + 1) << 3));

	memcpy(isrh, srh, sizeof(*isrh));
	memcpy(isrh->rpl_segaddr, &srh->rpl_segaddr[1],
	(srh->segments_left - 1) * 16);
	isrh->rpl_segaddr[srh->segments_left - 1] = oldhdr->daddr;

	ipv6_rpl_srh_compress(csrh, isrh, &srh->rpl_segaddr[0],
	isrh->segments_left - 1);

	hdrlen = ((csrh->hdrlen + 1) << 3);

	err = skb_cow_head(skb, hdrlen + skb->mac_len);
	if (unlikely(err)) {
	kfree(buf);
	return err;
	}

	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, csrh, hdrlen);

	isrh->nexthdr = hdr->nexthdr;
	hdr->nexthdr = NEXTHDR_ROUTING;
	hdr->daddr = srh->rpl_segaddr[0];

	ipv6_hdr(skb)->payload_len = htons(skb->len - sizeof(struct ipv6hdr));
	skb_set_transport_header(skb, sizeof(struct ipv6hdr));

	skb_postpush_rcsum(skb, hdr, sizeof(struct ipv6hdr) + hdrlen);

	kfree(buf);

	return 0;
	}

	static int rpl_do_srh(struct sk_buff skb, const struct rpl_lwt rlwt)
	{
	struct dst_entry *dst = skb_dst(skb);
	struct rpl_iptunnel_encap *tinfo;

	if (skb->protocol != htons(ETH_P_IPV6))
	return -EINVAL;

	tinfo = rpl_encap_lwtunnel(dst->lwtstate);

	return rpl_do_srh_inline(skb, rlwt, tinfo->srh);
	}

	static int rpl_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 rpl_lwt *rlwt;
	int err;

	rlwt = rpl_lwt_lwtunnel(orig_dst->lwtstate);

	err = rpl_do_srh(skb, rlwt);
	if (unlikely(err))
	goto drop;

	preempt_disable();
	dst = dst_cache_get(&rlwt->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(&rlwt->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 rpl_input(struct sk_buff *skb)
	{
	struct dst_entry *orig_dst = skb_dst(skb);
	struct dst_entry *dst = NULL;
	struct rpl_lwt *rlwt;
	int err;

	rlwt = rpl_lwt_lwtunnel(orig_dst->lwtstate);

	err = rpl_do_srh(skb, rlwt);
	if (unlikely(err)) {
	kfree_skb(skb);
	return err;
	}

	preempt_disable();
	dst = dst_cache_get(&rlwt->cache);
	preempt_enable();

	if (!dst) {
	ip6_route_input(skb);
	dst = skb_dst(skb);
	if (!dst->error) {
	preempt_disable();
	dst_cache_set_ip6(&rlwt->cache, dst,
	&ipv6_hdr(skb)->saddr);
	preempt_enable();
	}
	} else {
	skb_dst_drop(skb);
	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 nla_put_rpl_srh(struct sk_buff *skb, int attrtype,
	struct rpl_iptunnel_encap *tuninfo)
	{
	struct rpl_iptunnel_encap *data;
	struct nlattr *nla;
	int len;

	len = RPL_IPTUNNEL_SRH_SIZE(tuninfo->srh);

	nla = nla_reserve(skb, attrtype, len);
	if (!nla)
	return -EMSGSIZE;

	data = nla_data(nla);
	memcpy(data, tuninfo->srh, len);

	return 0;
	}

	static int rpl_fill_encap_info(struct sk_buff *skb,
	struct lwtunnel_state *lwtstate)
	{
	struct rpl_iptunnel_encap *tuninfo = rpl_encap_lwtunnel(lwtstate);

	if (nla_put_rpl_srh(skb, RPL_IPTUNNEL_SRH, tuninfo))
	return -EMSGSIZE;

	return 0;
	}

	static int rpl_encap_nlsize(struct lwtunnel_state *lwtstate)
	{
	struct rpl_iptunnel_encap *tuninfo = rpl_encap_lwtunnel(lwtstate);

	return nla_total_size(RPL_IPTUNNEL_SRH_SIZE(tuninfo->srh));
	}

	static int rpl_encap_cmp(struct lwtunnel_state a, struct lwtunnel_state b)
	{
	struct rpl_iptunnel_encap *a_hdr = rpl_encap_lwtunnel(a);
	struct rpl_iptunnel_encap *b_hdr = rpl_encap_lwtunnel(b);
	int len = RPL_IPTUNNEL_SRH_SIZE(a_hdr->srh);

	if (len != RPL_IPTUNNEL_SRH_SIZE(b_hdr->srh))
	return 1;

	return memcmp(a_hdr, b_hdr, len);
	}

	static const struct lwtunnel_encap_ops rpl_ops = {
	.build_state = rpl_build_state,
	.destroy_state = rpl_destroy_state,
	.output = rpl_output,
	.input = rpl_input,
	.fill_encap = rpl_fill_encap_info,
	.get_encap_size = rpl_encap_nlsize,
	.cmp_encap = rpl_encap_cmp,
	.owner = THIS_MODULE,
	};

	int __init rpl_init(void)
	{
	int err;

	err = lwtunnel_encap_add_ops(&rpl_ops, LWTUNNEL_ENCAP_RPL);
	if (err)
	goto out;

	pr_info("RPL Segment Routing with IPv6\n");

	return 0;

	out:
	return err;
	}

	void rpl_exit(void)
	{
	lwtunnel_encap_del_ops(&rpl_ops, LWTUNNEL_ENCAP_RPL);
	}