1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3 * IPv6 IOAM Lightweight Tunnel implementation
4 *
5 * Author:
6 * Justin Iurman <justin.iurman@uliege.be>
7 */
8
9 #include <linux/kernel.h>
10 #include <linux/skbuff.h>
11 #include <linux/net.h>
12 #include <linux/in6.h>
13 #include <linux/ioam6.h>
14 #include <linux/ioam6_iptunnel.h>
15 #include <net/dst.h>
16 #include <net/sock.h>
17 #include <net/lwtunnel.h>
18 #include <net/ioam6.h>
19 #include <net/netlink.h>
20 #include <net/ipv6.h>
21 #include <net/dst_cache.h>
22 #include <net/ip6_route.h>
23 #include <net/addrconf.h>
24
25 #define IOAM6_MASK_SHORT_FIELDS 0xff100000
26 #define IOAM6_MASK_WIDE_FIELDS 0xe00000
27
28 struct ioam6_lwt_encap {
29 struct ipv6_hopopt_hdr eh;
30 u8 pad[2]; /* 2-octet padding for 4n-alignment */
31 struct ioam6_hdr ioamh;
32 struct ioam6_trace_hdr traceh;
33 } __packed;
34
35 struct ioam6_lwt_freq {
36 u32 k;
37 u32 n;
38 };
39
40 struct ioam6_lwt {
41 struct dst_cache cache;
42 struct ioam6_lwt_freq freq;
43 atomic_t pkt_cnt;
44 u8 mode;
45 struct in6_addr tundst;
46 struct ioam6_lwt_encap tuninfo;
47 };
48
49 static const struct netlink_range_validation freq_range = {
50 .min = IOAM6_IPTUNNEL_FREQ_MIN,
51 .max = IOAM6_IPTUNNEL_FREQ_MAX,
52 };
53
54 static struct ioam6_lwt *ioam6_lwt_state(struct lwtunnel_state *lwt)
55 {
56 return (struct ioam6_lwt *)lwt->data;
57 }
58
59 static struct ioam6_lwt_encap *ioam6_lwt_info(struct lwtunnel_state *lwt)
60 {
61 return &ioam6_lwt_state(lwt)->tuninfo;
62 }
63
64 static struct ioam6_trace_hdr *ioam6_lwt_trace(struct lwtunnel_state *lwt)
65 {
66 return &(ioam6_lwt_state(lwt)->tuninfo.traceh);
67 }
68
69 static const struct nla_policy ioam6_iptunnel_policy[IOAM6_IPTUNNEL_MAX + 1] = {
70 [IOAM6_IPTUNNEL_FREQ_K] = NLA_POLICY_FULL_RANGE(NLA_U32, &freq_range),
71 [IOAM6_IPTUNNEL_FREQ_N] = NLA_POLICY_FULL_RANGE(NLA_U32, &freq_range),
72 [IOAM6_IPTUNNEL_MODE] = NLA_POLICY_RANGE(NLA_U8,
73 IOAM6_IPTUNNEL_MODE_MIN,
74 IOAM6_IPTUNNEL_MODE_MAX),
75 [IOAM6_IPTUNNEL_DST] = NLA_POLICY_EXACT_LEN(sizeof(struct in6_addr)),
76 [IOAM6_IPTUNNEL_TRACE] = NLA_POLICY_EXACT_LEN(sizeof(struct ioam6_trace_hdr)),
77 };
78
79 static bool ioam6_validate_trace_hdr(struct ioam6_trace_hdr *trace)
80 {
81 u32 fields;
82
83 if (!trace->type_be32 || !trace->remlen ||
84 trace->remlen > IOAM6_TRACE_DATA_SIZE_MAX / 4 ||
85 trace->type.bit12 | trace->type.bit13 | trace->type.bit14 |
86 trace->type.bit15 | trace->type.bit16 | trace->type.bit17 |
87 trace->type.bit18 | trace->type.bit19 | trace->type.bit20 |
88 trace->type.bit21)
89 return false;
90
91 trace->nodelen = 0;
92 fields = be32_to_cpu(trace->type_be32);
93
94 trace->nodelen += hweight32(fields & IOAM6_MASK_SHORT_FIELDS)
95 * (sizeof(__be32) / 4);
96 trace->nodelen += hweight32(fields & IOAM6_MASK_WIDE_FIELDS)
97 * (sizeof(__be64) / 4);
98
99 return true;
100 }
101
102 static int ioam6_build_state(struct net *net, struct nlattr *nla,
103 unsigned int family, const void *cfg,
104 struct lwtunnel_state **ts,
105 struct netlink_ext_ack *extack)
106 {
107 struct nlattr *tb[IOAM6_IPTUNNEL_MAX + 1];
108 struct ioam6_lwt_encap *tuninfo;
109 struct ioam6_trace_hdr *trace;
110 struct lwtunnel_state *lwt;
111 struct ioam6_lwt *ilwt;
112 int len_aligned, err;
113 u32 freq_k, freq_n;
114 u8 mode;
115
116 if (family != AF_INET6)
117 return -EINVAL;
118
119 err = nla_parse_nested(tb, IOAM6_IPTUNNEL_MAX, nla,
120 ioam6_iptunnel_policy, extack);
121 if (err < 0)
122 return err;
123
124 if ((!tb[IOAM6_IPTUNNEL_FREQ_K] && tb[IOAM6_IPTUNNEL_FREQ_N]) ||
125 (tb[IOAM6_IPTUNNEL_FREQ_K] && !tb[IOAM6_IPTUNNEL_FREQ_N])) {
126 NL_SET_ERR_MSG(extack, "freq: missing parameter");
127 return -EINVAL;
128 } else if (!tb[IOAM6_IPTUNNEL_FREQ_K] && !tb[IOAM6_IPTUNNEL_FREQ_N]) {
129 freq_k = IOAM6_IPTUNNEL_FREQ_MIN;
130 freq_n = IOAM6_IPTUNNEL_FREQ_MIN;
131 } else {
132 freq_k = nla_get_u32(tb[IOAM6_IPTUNNEL_FREQ_K]);
133 freq_n = nla_get_u32(tb[IOAM6_IPTUNNEL_FREQ_N]);
134
135 if (freq_k > freq_n) {
136 NL_SET_ERR_MSG(extack, "freq: k > n is forbidden");
137 return -EINVAL;
138 }
139 }
140
141 if (!tb[IOAM6_IPTUNNEL_MODE])
142 mode = IOAM6_IPTUNNEL_MODE_INLINE;
143 else
144 mode = nla_get_u8(tb[IOAM6_IPTUNNEL_MODE]);
145
146 if (!tb[IOAM6_IPTUNNEL_DST] && mode != IOAM6_IPTUNNEL_MODE_INLINE) {
147 NL_SET_ERR_MSG(extack, "this mode needs a tunnel destination");
148 return -EINVAL;
149 }
150
151 if (!tb[IOAM6_IPTUNNEL_TRACE]) {
152 NL_SET_ERR_MSG(extack, "missing trace");
153 return -EINVAL;
154 }
155
156 trace = nla_data(tb[IOAM6_IPTUNNEL_TRACE]);
157 if (!ioam6_validate_trace_hdr(trace)) {
158 NL_SET_ERR_MSG_ATTR(extack, tb[IOAM6_IPTUNNEL_TRACE],
159 "invalid trace validation");
160 return -EINVAL;
161 }
162
163 len_aligned = ALIGN(trace->remlen * 4, 8);
164 lwt = lwtunnel_state_alloc(sizeof(*ilwt) + len_aligned);
165 if (!lwt)
166 return -ENOMEM;
167
168 ilwt = ioam6_lwt_state(lwt);
169 err = dst_cache_init(&ilwt->cache, GFP_ATOMIC);
170 if (err) {
171 kfree(lwt);
172 return err;
173 }
174
175 atomic_set(&ilwt->pkt_cnt, 0);
176 ilwt->freq.k = freq_k;
177 ilwt->freq.n = freq_n;
178
179 ilwt->mode = mode;
180 if (tb[IOAM6_IPTUNNEL_DST])
181 ilwt->tundst = nla_get_in6_addr(tb[IOAM6_IPTUNNEL_DST]);
182
183 tuninfo = ioam6_lwt_info(lwt);
184 tuninfo->eh.hdrlen = ((sizeof(*tuninfo) + len_aligned) >> 3) - 1;
185 tuninfo->pad[0] = IPV6_TLV_PADN;
186 tuninfo->ioamh.type = IOAM6_TYPE_PREALLOC;
187 tuninfo->ioamh.opt_type = IPV6_TLV_IOAM;
188 tuninfo->ioamh.opt_len = sizeof(tuninfo->ioamh) - 2 + sizeof(*trace)
189 + trace->remlen * 4;
190
191 memcpy(&tuninfo->traceh, trace, sizeof(*trace));
192
193 if (len_aligned - trace->remlen * 4) {
194 tuninfo->traceh.data[trace->remlen * 4] = IPV6_TLV_PADN;
195 tuninfo->traceh.data[trace->remlen * 4 + 1] = 2;
196 }
197
198 lwt->type = LWTUNNEL_ENCAP_IOAM6;
199 lwt->flags |= LWTUNNEL_STATE_OUTPUT_REDIRECT;
200
201 *ts = lwt;
202
203 return 0;
204 }
205
206 static int ioam6_do_fill(struct net *net, struct sk_buff *skb)
207 {
208 struct ioam6_trace_hdr *trace;
209 struct ioam6_namespace *ns;
210
211 trace = (struct ioam6_trace_hdr *)(skb_transport_header(skb)
212 + sizeof(struct ipv6_hopopt_hdr) + 2
213 + sizeof(struct ioam6_hdr));
214
215 ns = ioam6_namespace(net, trace->namespace_id);
216 if (ns)
217 ioam6_fill_trace_data(skb, ns, trace, false);
218
219 return 0;
220 }
221
222 static int ioam6_do_inline(struct net *net, struct sk_buff *skb,
223 struct ioam6_lwt_encap *tuninfo)
224 {
225 struct ipv6hdr *oldhdr, *hdr;
226 int hdrlen, err;
227
228 hdrlen = (tuninfo->eh.hdrlen + 1) << 3;
229
230 err = skb_cow_head(skb, hdrlen + skb->mac_len);
231 if (unlikely(err))
232 return err;
233
234 oldhdr = ipv6_hdr(skb);
235 skb_pull(skb, sizeof(*oldhdr));
236 skb_postpull_rcsum(skb, skb_network_header(skb), sizeof(*oldhdr));
237
238 skb_push(skb, sizeof(*oldhdr) + hdrlen);
239 skb_reset_network_header(skb);
240 skb_mac_header_rebuild(skb);
241
242 hdr = ipv6_hdr(skb);
243 memmove(hdr, oldhdr, sizeof(*oldhdr));
244 tuninfo->eh.nexthdr = hdr->nexthdr;
245
246 skb_set_transport_header(skb, sizeof(*hdr));
247 skb_postpush_rcsum(skb, hdr, sizeof(*hdr) + hdrlen);
248
249 memcpy(skb_transport_header(skb), (u8 *)tuninfo, hdrlen);
250
251 hdr->nexthdr = NEXTHDR_HOP;
252 hdr->payload_len = cpu_to_be16(skb->len - sizeof(*hdr));
253
254 return ioam6_do_fill(net, skb);
255 }
256
257 static int ioam6_do_encap(struct net *net, struct sk_buff *skb,
258 struct ioam6_lwt_encap *tuninfo,
259 struct in6_addr *tundst)
260 {
261 struct dst_entry *dst = skb_dst(skb);
262 struct ipv6hdr *hdr, *inner_hdr;
263 int hdrlen, len, err;
264
265 hdrlen = (tuninfo->eh.hdrlen + 1) << 3;
266 len = sizeof(*hdr) + hdrlen;
267
268 err = skb_cow_head(skb, len + skb->mac_len);
269 if (unlikely(err))
270 return err;
271
272 inner_hdr = ipv6_hdr(skb);
273
274 skb_push(skb, len);
275 skb_reset_network_header(skb);
276 skb_mac_header_rebuild(skb);
277 skb_set_transport_header(skb, sizeof(*hdr));
278
279 tuninfo->eh.nexthdr = NEXTHDR_IPV6;
280 memcpy(skb_transport_header(skb), (u8 *)tuninfo, hdrlen);
281
282 hdr = ipv6_hdr(skb);
283 memcpy(hdr, inner_hdr, sizeof(*hdr));
284
285 hdr->nexthdr = NEXTHDR_HOP;
286 hdr->payload_len = cpu_to_be16(skb->len - sizeof(*hdr));
287 hdr->daddr = *tundst;
288 ipv6_dev_get_saddr(net, dst->dev, &hdr->daddr,
289 IPV6_PREFER_SRC_PUBLIC, &hdr->saddr);
290
291 skb_postpush_rcsum(skb, hdr, len);
292
293 return ioam6_do_fill(net, skb);
294 }
295
296 static int ioam6_output(struct net *net, struct sock *sk, struct sk_buff *skb)
297 {
298 struct dst_entry *dst = skb_dst(skb);
299 struct in6_addr orig_daddr;
300 struct ioam6_lwt *ilwt;
301 int err = -EINVAL;
302 u32 pkt_cnt;
303
304 if (skb->protocol != htons(ETH_P_IPV6))
305 goto drop;
306
307 ilwt = ioam6_lwt_state(dst->lwtstate);
308
309 /* Check for insertion frequency (i.e., "k over n" insertions) */
310 pkt_cnt = atomic_fetch_inc(&ilwt->pkt_cnt);
311 if (pkt_cnt % ilwt->freq.n >= ilwt->freq.k)
312 goto out;
313
314 orig_daddr = ipv6_hdr(skb)->daddr;
315
316 switch (ilwt->mode) {
317 case IOAM6_IPTUNNEL_MODE_INLINE:
318 do_inline:
319 /* Direct insertion - if there is no Hop-by-Hop yet */
320 if (ipv6_hdr(skb)->nexthdr == NEXTHDR_HOP)
321 goto out;
322
323 err = ioam6_do_inline(net, skb, &ilwt->tuninfo);
324 if (unlikely(err))
325 goto drop;
326
327 break;
328 case IOAM6_IPTUNNEL_MODE_ENCAP:
329 do_encap:
330 /* Encapsulation (ip6ip6) */
331 err = ioam6_do_encap(net, skb, &ilwt->tuninfo, &ilwt->tundst);
332 if (unlikely(err))
333 goto drop;
334
335 break;
336 case IOAM6_IPTUNNEL_MODE_AUTO:
337 /* Automatic (RFC8200 compliant):
338 * - local packets -> INLINE mode
339 * - in-transit packets -> ENCAP mode
340 */
341 if (!skb->dev)
342 goto do_inline;
343
344 goto do_encap;
345 default:
346 goto drop;
347 }
348
349 err = skb_cow_head(skb, LL_RESERVED_SPACE(dst->dev));
350 if (unlikely(err))
351 goto drop;
352
353 if (!ipv6_addr_equal(&orig_daddr, &ipv6_hdr(skb)->daddr)) {
354 local_bh_disable();
355 dst = dst_cache_get(&ilwt->cache);
356 local_bh_enable();
357
358 if (unlikely(!dst)) {
359 struct ipv6hdr *hdr = ipv6_hdr(skb);
360 struct flowi6 fl6;
361
362 memset(&fl6, 0, sizeof(fl6));
363 fl6.daddr = hdr->daddr;
364 fl6.saddr = hdr->saddr;
365 fl6.flowlabel = ip6_flowinfo(hdr);
366 fl6.flowi6_mark = skb->mark;
367 fl6.flowi6_proto = hdr->nexthdr;
368
369 dst = ip6_route_output(net, NULL, &fl6);
370 if (dst->error) {
371 err = dst->error;
372 dst_release(dst);
373 goto drop;
374 }
375
376 local_bh_disable();
377 dst_cache_set_ip6(&ilwt->cache, dst, &fl6.saddr);
378 local_bh_enable();
379 }
380
381 skb_dst_drop(skb);
382 skb_dst_set(skb, dst);
383
384 return dst_output(net, sk, skb);
385 }
386 out:
387 return dst->lwtstate->orig_output(net, sk, skb);
388 drop:
389 kfree_skb(skb);
390 return err;
391 }
392
393 static void ioam6_destroy_state(struct lwtunnel_state *lwt)
394 {
395 dst_cache_destroy(&ioam6_lwt_state(lwt)->cache);
396 }
397
398 static int ioam6_fill_encap_info(struct sk_buff *skb,
399 struct lwtunnel_state *lwtstate)
400 {
401 struct ioam6_lwt *ilwt = ioam6_lwt_state(lwtstate);
402 int err;
403
404 err = nla_put_u32(skb, IOAM6_IPTUNNEL_FREQ_K, ilwt->freq.k);
405 if (err)
406 goto ret;
407
408 err = nla_put_u32(skb, IOAM6_IPTUNNEL_FREQ_N, ilwt->freq.n);
409 if (err)
410 goto ret;
411
412 err = nla_put_u8(skb, IOAM6_IPTUNNEL_MODE, ilwt->mode);
413 if (err)
414 goto ret;
415
416 if (ilwt->mode != IOAM6_IPTUNNEL_MODE_INLINE) {
417 err = nla_put_in6_addr(skb, IOAM6_IPTUNNEL_DST, &ilwt->tundst);
418 if (err)
419 goto ret;
420 }
421
422 err = nla_put(skb, IOAM6_IPTUNNEL_TRACE, sizeof(ilwt->tuninfo.traceh),
423 &ilwt->tuninfo.traceh);
424 ret:
425 return err;
426 }
427
428 static int ioam6_encap_nlsize(struct lwtunnel_state *lwtstate)
429 {
430 struct ioam6_lwt *ilwt = ioam6_lwt_state(lwtstate);
431 int nlsize;
432
433 nlsize = nla_total_size(sizeof(ilwt->freq.k)) +
434 nla_total_size(sizeof(ilwt->freq.n)) +
435 nla_total_size(sizeof(ilwt->mode)) +
436 nla_total_size(sizeof(ilwt->tuninfo.traceh));
437
438 if (ilwt->mode != IOAM6_IPTUNNEL_MODE_INLINE)
439 nlsize += nla_total_size(sizeof(ilwt->tundst));
440
441 return nlsize;
442 }
443
444 static int ioam6_encap_cmp(struct lwtunnel_state *a, struct lwtunnel_state *b)
445 {
446 struct ioam6_trace_hdr *trace_a = ioam6_lwt_trace(a);
447 struct ioam6_trace_hdr *trace_b = ioam6_lwt_trace(b);
448 struct ioam6_lwt *ilwt_a = ioam6_lwt_state(a);
449 struct ioam6_lwt *ilwt_b = ioam6_lwt_state(b);
450
451 return (ilwt_a->freq.k != ilwt_b->freq.k ||
452 ilwt_a->freq.n != ilwt_b->freq.n ||
453 ilwt_a->mode != ilwt_b->mode ||
454 (ilwt_a->mode != IOAM6_IPTUNNEL_MODE_INLINE &&
455 !ipv6_addr_equal(&ilwt_a->tundst, &ilwt_b->tundst)) ||
456 trace_a->namespace_id != trace_b->namespace_id);
457 }
458
459 static const struct lwtunnel_encap_ops ioam6_iptun_ops = {
460 .build_state = ioam6_build_state,
461 .destroy_state = ioam6_destroy_state,
462 .output = ioam6_output,
463 .fill_encap = ioam6_fill_encap_info,
464 .get_encap_size = ioam6_encap_nlsize,
465 .cmp_encap = ioam6_encap_cmp,
466 .owner = THIS_MODULE,
467 };
468
469 int __init ioam6_iptunnel_init(void)
470 {
471 return lwtunnel_encap_add_ops(&ioam6_iptun_ops, LWTUNNEL_ENCAP_IOAM6);
472 }
473
474 void ioam6_iptunnel_exit(void)
475 {
476 lwtunnel_encap_del_ops(&ioam6_iptun_ops, LWTUNNEL_ENCAP_IOAM6);
477 }
478
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