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 struct netlink_range_validation freq_range = {
50 	.min = IOAM6_IPTUNNEL_FREQ_MIN,
51 	.max = IOAM6_IPTUNNEL_FREQ_MAX,
52 };
53 
ioam6_lwt_state(struct lwtunnel_state * lwt)54 static struct ioam6_lwt *ioam6_lwt_state(struct lwtunnel_state *lwt)
55 {
56 	return (struct ioam6_lwt *)lwt->data;
57 }
58 
ioam6_lwt_info(struct lwtunnel_state * lwt)59 static struct ioam6_lwt_encap *ioam6_lwt_info(struct lwtunnel_state *lwt)
60 {
61 	return &ioam6_lwt_state(lwt)->tuninfo;
62 }
63 
ioam6_lwt_trace(struct lwtunnel_state * lwt)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 
ioam6_validate_trace_hdr(struct ioam6_trace_hdr * trace)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 
ioam6_build_state(struct net * net,struct nlattr * nla,unsigned int family,const void * cfg,struct lwtunnel_state ** ts,struct netlink_ext_ack * extack)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 
ioam6_do_fill(struct net * net,struct sk_buff * skb)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 
ioam6_do_inline(struct net * net,struct sk_buff * skb,struct ioam6_lwt_encap * tuninfo)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 
ioam6_do_encap(struct net * net,struct sk_buff * skb,struct ioam6_lwt_encap * tuninfo,struct in6_addr * tundst)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 
ioam6_output(struct net * net,struct sock * sk,struct sk_buff * skb)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 		preempt_disable();
355 		dst = dst_cache_get(&ilwt->cache);
356 		preempt_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 			preempt_disable();
377 			dst_cache_set_ip6(&ilwt->cache, dst, &fl6.saddr);
378 			preempt_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 
ioam6_destroy_state(struct lwtunnel_state * lwt)393 static void ioam6_destroy_state(struct lwtunnel_state *lwt)
394 {
395 	dst_cache_destroy(&ioam6_lwt_state(lwt)->cache);
396 }
397 
ioam6_fill_encap_info(struct sk_buff * skb,struct lwtunnel_state * lwtstate)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 
ioam6_encap_nlsize(struct lwtunnel_state * lwtstate)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 
ioam6_encap_cmp(struct lwtunnel_state * a,struct lwtunnel_state * b)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 
ioam6_iptunnel_init(void)469 int __init ioam6_iptunnel_init(void)
470 {
471 	return lwtunnel_encap_add_ops(&ioam6_iptun_ops, LWTUNNEL_ENCAP_IOAM6);
472 }
473 
ioam6_iptunnel_exit(void)474 void ioam6_iptunnel_exit(void)
475 {
476 	lwtunnel_encap_del_ops(&ioam6_iptun_ops, LWTUNNEL_ENCAP_IOAM6);
477 }
478