xref: /openbmc/linux/net/ipv6/rpl_iptunnel.c (revision a46add42)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Authors:
4  * (C) 2020 Alexander Aring <alex.aring@gmail.com>
5  */
6 
7 #include <linux/rpl_iptunnel.h>
8 
9 #include <net/dst_cache.h>
10 #include <net/ip6_route.h>
11 #include <net/lwtunnel.h>
12 #include <net/ipv6.h>
13 #include <net/rpl.h>
14 
15 struct rpl_iptunnel_encap {
16 	DECLARE_FLEX_ARRAY(struct ipv6_rpl_sr_hdr, srh);
17 };
18 
19 struct rpl_lwt {
20 	struct dst_cache cache;
21 	struct rpl_iptunnel_encap tuninfo;
22 };
23 
rpl_lwt_lwtunnel(struct lwtunnel_state * lwt)24 static inline struct rpl_lwt *rpl_lwt_lwtunnel(struct lwtunnel_state *lwt)
25 {
26 	return (struct rpl_lwt *)lwt->data;
27 }
28 
29 static inline struct rpl_iptunnel_encap *
rpl_encap_lwtunnel(struct lwtunnel_state * lwt)30 rpl_encap_lwtunnel(struct lwtunnel_state *lwt)
31 {
32 	return &rpl_lwt_lwtunnel(lwt)->tuninfo;
33 }
34 
35 static const struct nla_policy rpl_iptunnel_policy[RPL_IPTUNNEL_MAX + 1] = {
36 	[RPL_IPTUNNEL_SRH]	= { .type = NLA_BINARY },
37 };
38 
rpl_validate_srh(struct net * net,struct ipv6_rpl_sr_hdr * srh,size_t seglen)39 static bool rpl_validate_srh(struct net *net, struct ipv6_rpl_sr_hdr *srh,
40 			     size_t seglen)
41 {
42 	int err;
43 
44 	if ((srh->hdrlen << 3) != seglen)
45 		return false;
46 
47 	/* check at least one segment and seglen fit with segments_left */
48 	if (!srh->segments_left ||
49 	    (srh->segments_left * sizeof(struct in6_addr)) != seglen)
50 		return false;
51 
52 	if (srh->cmpri || srh->cmpre)
53 		return false;
54 
55 	err = ipv6_chk_rpl_srh_loop(net, srh->rpl_segaddr,
56 				    srh->segments_left);
57 	if (err)
58 		return false;
59 
60 	if (ipv6_addr_type(&srh->rpl_segaddr[srh->segments_left - 1]) &
61 	    IPV6_ADDR_MULTICAST)
62 		return false;
63 
64 	return true;
65 }
66 
rpl_build_state(struct net * net,struct nlattr * nla,unsigned int family,const void * cfg,struct lwtunnel_state ** ts,struct netlink_ext_ack * extack)67 static int rpl_build_state(struct net *net, struct nlattr *nla,
68 			   unsigned int family, const void *cfg,
69 			   struct lwtunnel_state **ts,
70 			   struct netlink_ext_ack *extack)
71 {
72 	struct nlattr *tb[RPL_IPTUNNEL_MAX + 1];
73 	struct lwtunnel_state *newts;
74 	struct ipv6_rpl_sr_hdr *srh;
75 	struct rpl_lwt *rlwt;
76 	int err, srh_len;
77 
78 	if (family != AF_INET6)
79 		return -EINVAL;
80 
81 	err = nla_parse_nested(tb, RPL_IPTUNNEL_MAX, nla,
82 			       rpl_iptunnel_policy, extack);
83 	if (err < 0)
84 		return err;
85 
86 	if (!tb[RPL_IPTUNNEL_SRH])
87 		return -EINVAL;
88 
89 	srh = nla_data(tb[RPL_IPTUNNEL_SRH]);
90 	srh_len = nla_len(tb[RPL_IPTUNNEL_SRH]);
91 
92 	if (srh_len < sizeof(*srh))
93 		return -EINVAL;
94 
95 	/* verify that SRH is consistent */
96 	if (!rpl_validate_srh(net, srh, srh_len - sizeof(*srh)))
97 		return -EINVAL;
98 
99 	newts = lwtunnel_state_alloc(srh_len + sizeof(*rlwt));
100 	if (!newts)
101 		return -ENOMEM;
102 
103 	rlwt = rpl_lwt_lwtunnel(newts);
104 
105 	err = dst_cache_init(&rlwt->cache, GFP_ATOMIC);
106 	if (err) {
107 		kfree(newts);
108 		return err;
109 	}
110 
111 	memcpy(&rlwt->tuninfo.srh, srh, srh_len);
112 
113 	newts->type = LWTUNNEL_ENCAP_RPL;
114 	newts->flags |= LWTUNNEL_STATE_INPUT_REDIRECT;
115 	newts->flags |= LWTUNNEL_STATE_OUTPUT_REDIRECT;
116 
117 	*ts = newts;
118 
119 	return 0;
120 }
121 
rpl_destroy_state(struct lwtunnel_state * lwt)122 static void rpl_destroy_state(struct lwtunnel_state *lwt)
123 {
124 	dst_cache_destroy(&rpl_lwt_lwtunnel(lwt)->cache);
125 }
126 
rpl_do_srh_inline(struct sk_buff * skb,const struct rpl_lwt * rlwt,const struct ipv6_rpl_sr_hdr * srh)127 static int rpl_do_srh_inline(struct sk_buff *skb, const struct rpl_lwt *rlwt,
128 			     const struct ipv6_rpl_sr_hdr *srh)
129 {
130 	struct ipv6_rpl_sr_hdr *isrh, *csrh;
131 	const struct ipv6hdr *oldhdr;
132 	struct ipv6hdr *hdr;
133 	unsigned char *buf;
134 	size_t hdrlen;
135 	int err;
136 
137 	oldhdr = ipv6_hdr(skb);
138 
139 	buf = kcalloc(struct_size(srh, segments.addr, srh->segments_left), 2, GFP_ATOMIC);
140 	if (!buf)
141 		return -ENOMEM;
142 
143 	isrh = (struct ipv6_rpl_sr_hdr *)buf;
144 	csrh = (struct ipv6_rpl_sr_hdr *)(buf + ((srh->hdrlen + 1) << 3));
145 
146 	memcpy(isrh, srh, sizeof(*isrh));
147 	memcpy(isrh->rpl_segaddr, &srh->rpl_segaddr[1],
148 	       (srh->segments_left - 1) * 16);
149 	isrh->rpl_segaddr[srh->segments_left - 1] = oldhdr->daddr;
150 
151 	ipv6_rpl_srh_compress(csrh, isrh, &srh->rpl_segaddr[0],
152 			      isrh->segments_left - 1);
153 
154 	hdrlen = ((csrh->hdrlen + 1) << 3);
155 
156 	err = skb_cow_head(skb, hdrlen + skb->mac_len);
157 	if (unlikely(err)) {
158 		kfree(buf);
159 		return err;
160 	}
161 
162 	skb_pull(skb, sizeof(struct ipv6hdr));
163 	skb_postpull_rcsum(skb, skb_network_header(skb),
164 			   sizeof(struct ipv6hdr));
165 
166 	skb_push(skb, sizeof(struct ipv6hdr) + hdrlen);
167 	skb_reset_network_header(skb);
168 	skb_mac_header_rebuild(skb);
169 
170 	hdr = ipv6_hdr(skb);
171 	memmove(hdr, oldhdr, sizeof(*hdr));
172 	isrh = (void *)hdr + sizeof(*hdr);
173 	memcpy(isrh, csrh, hdrlen);
174 
175 	isrh->nexthdr = hdr->nexthdr;
176 	hdr->nexthdr = NEXTHDR_ROUTING;
177 	hdr->daddr = srh->rpl_segaddr[0];
178 
179 	ipv6_hdr(skb)->payload_len = htons(skb->len - sizeof(struct ipv6hdr));
180 	skb_set_transport_header(skb, sizeof(struct ipv6hdr));
181 
182 	skb_postpush_rcsum(skb, hdr, sizeof(struct ipv6hdr) + hdrlen);
183 
184 	kfree(buf);
185 
186 	return 0;
187 }
188 
rpl_do_srh(struct sk_buff * skb,const struct rpl_lwt * rlwt)189 static int rpl_do_srh(struct sk_buff *skb, const struct rpl_lwt *rlwt)
190 {
191 	struct dst_entry *dst = skb_dst(skb);
192 	struct rpl_iptunnel_encap *tinfo;
193 
194 	if (skb->protocol != htons(ETH_P_IPV6))
195 		return -EINVAL;
196 
197 	tinfo = rpl_encap_lwtunnel(dst->lwtstate);
198 
199 	return rpl_do_srh_inline(skb, rlwt, tinfo->srh);
200 }
201 
rpl_output(struct net * net,struct sock * sk,struct sk_buff * skb)202 static int rpl_output(struct net *net, struct sock *sk, struct sk_buff *skb)
203 {
204 	struct dst_entry *orig_dst = skb_dst(skb);
205 	struct dst_entry *dst = NULL;
206 	struct rpl_lwt *rlwt;
207 	int err;
208 
209 	rlwt = rpl_lwt_lwtunnel(orig_dst->lwtstate);
210 
211 	err = rpl_do_srh(skb, rlwt);
212 	if (unlikely(err))
213 		goto drop;
214 
215 	local_bh_disable();
216 	dst = dst_cache_get(&rlwt->cache);
217 	local_bh_enable();
218 
219 	if (unlikely(!dst)) {
220 		struct ipv6hdr *hdr = ipv6_hdr(skb);
221 		struct flowi6 fl6;
222 
223 		memset(&fl6, 0, sizeof(fl6));
224 		fl6.daddr = hdr->daddr;
225 		fl6.saddr = hdr->saddr;
226 		fl6.flowlabel = ip6_flowinfo(hdr);
227 		fl6.flowi6_mark = skb->mark;
228 		fl6.flowi6_proto = hdr->nexthdr;
229 
230 		dst = ip6_route_output(net, NULL, &fl6);
231 		if (dst->error) {
232 			err = dst->error;
233 			dst_release(dst);
234 			goto drop;
235 		}
236 
237 		local_bh_disable();
238 		dst_cache_set_ip6(&rlwt->cache, dst, &fl6.saddr);
239 		local_bh_enable();
240 	}
241 
242 	skb_dst_drop(skb);
243 	skb_dst_set(skb, dst);
244 
245 	err = skb_cow_head(skb, LL_RESERVED_SPACE(dst->dev));
246 	if (unlikely(err))
247 		goto drop;
248 
249 	return dst_output(net, sk, skb);
250 
251 drop:
252 	kfree_skb(skb);
253 	return err;
254 }
255 
rpl_input(struct sk_buff * skb)256 static int rpl_input(struct sk_buff *skb)
257 {
258 	struct dst_entry *orig_dst = skb_dst(skb);
259 	struct dst_entry *dst = NULL;
260 	struct rpl_lwt *rlwt;
261 	int err;
262 
263 	rlwt = rpl_lwt_lwtunnel(orig_dst->lwtstate);
264 
265 	err = rpl_do_srh(skb, rlwt);
266 	if (unlikely(err))
267 		goto drop;
268 
269 	local_bh_disable();
270 	dst = dst_cache_get(&rlwt->cache);
271 
272 	if (!dst) {
273 		ip6_route_input(skb);
274 		dst = skb_dst(skb);
275 		if (!dst->error) {
276 			dst_cache_set_ip6(&rlwt->cache, dst,
277 					  &ipv6_hdr(skb)->saddr);
278 		}
279 	} else {
280 		skb_dst_drop(skb);
281 		skb_dst_set(skb, dst);
282 	}
283 	local_bh_enable();
284 
285 	err = skb_cow_head(skb, LL_RESERVED_SPACE(dst->dev));
286 	if (unlikely(err))
287 		goto drop;
288 
289 	return dst_input(skb);
290 
291 drop:
292 	kfree_skb(skb);
293 	return err;
294 }
295 
nla_put_rpl_srh(struct sk_buff * skb,int attrtype,struct rpl_iptunnel_encap * tuninfo)296 static int nla_put_rpl_srh(struct sk_buff *skb, int attrtype,
297 			   struct rpl_iptunnel_encap *tuninfo)
298 {
299 	struct rpl_iptunnel_encap *data;
300 	struct nlattr *nla;
301 	int len;
302 
303 	len = RPL_IPTUNNEL_SRH_SIZE(tuninfo->srh);
304 
305 	nla = nla_reserve(skb, attrtype, len);
306 	if (!nla)
307 		return -EMSGSIZE;
308 
309 	data = nla_data(nla);
310 	memcpy(data, tuninfo->srh, len);
311 
312 	return 0;
313 }
314 
rpl_fill_encap_info(struct sk_buff * skb,struct lwtunnel_state * lwtstate)315 static int rpl_fill_encap_info(struct sk_buff *skb,
316 			       struct lwtunnel_state *lwtstate)
317 {
318 	struct rpl_iptunnel_encap *tuninfo = rpl_encap_lwtunnel(lwtstate);
319 
320 	if (nla_put_rpl_srh(skb, RPL_IPTUNNEL_SRH, tuninfo))
321 		return -EMSGSIZE;
322 
323 	return 0;
324 }
325 
rpl_encap_nlsize(struct lwtunnel_state * lwtstate)326 static int rpl_encap_nlsize(struct lwtunnel_state *lwtstate)
327 {
328 	struct rpl_iptunnel_encap *tuninfo = rpl_encap_lwtunnel(lwtstate);
329 
330 	return nla_total_size(RPL_IPTUNNEL_SRH_SIZE(tuninfo->srh));
331 }
332 
rpl_encap_cmp(struct lwtunnel_state * a,struct lwtunnel_state * b)333 static int rpl_encap_cmp(struct lwtunnel_state *a, struct lwtunnel_state *b)
334 {
335 	struct rpl_iptunnel_encap *a_hdr = rpl_encap_lwtunnel(a);
336 	struct rpl_iptunnel_encap *b_hdr = rpl_encap_lwtunnel(b);
337 	int len = RPL_IPTUNNEL_SRH_SIZE(a_hdr->srh);
338 
339 	if (len != RPL_IPTUNNEL_SRH_SIZE(b_hdr->srh))
340 		return 1;
341 
342 	return memcmp(a_hdr, b_hdr, len);
343 }
344 
345 static const struct lwtunnel_encap_ops rpl_ops = {
346 	.build_state	= rpl_build_state,
347 	.destroy_state	= rpl_destroy_state,
348 	.output		= rpl_output,
349 	.input		= rpl_input,
350 	.fill_encap	= rpl_fill_encap_info,
351 	.get_encap_size	= rpl_encap_nlsize,
352 	.cmp_encap	= rpl_encap_cmp,
353 	.owner		= THIS_MODULE,
354 };
355 
rpl_init(void)356 int __init rpl_init(void)
357 {
358 	int err;
359 
360 	err = lwtunnel_encap_add_ops(&rpl_ops, LWTUNNEL_ENCAP_RPL);
361 	if (err)
362 		goto out;
363 
364 	pr_info("RPL Segment Routing with IPv6\n");
365 
366 	return 0;
367 
368 out:
369 	return err;
370 }
371 
rpl_exit(void)372 void rpl_exit(void)
373 {
374 	lwtunnel_encap_del_ops(&rpl_ops, LWTUNNEL_ENCAP_RPL);
375 }
376