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
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 *
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
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
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
122 static void rpl_destroy_state(struct lwtunnel_state *lwt)
123 {
124 dst_cache_destroy(&rpl_lwt_lwtunnel(lwt)->cache);
125 }
126
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
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
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
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
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
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
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
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
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
372 void rpl_exit(void)
373 {
374 lwtunnel_encap_del_ops(&rpl_ops, LWTUNNEL_ENCAP_RPL);
375 }
376
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