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Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm...
[mirror_ubuntu-bionic-kernel.git] / net / ipv4 / ip_options.c
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * INET An implementation of the TCP/IP protocol suite for the LINUX
4 * operating system. INET is implemented using the BSD Socket
5 * interface as the means of communication with the user level.
6 *
7 * The options processing module for ip.c
8 *
9 * Authors: A.N.Kuznetsov
10 *
11 */
12
13 #define pr_fmt(fmt) "IPv4: " fmt
14
15 #include <linux/capability.h>
16 #include <linux/module.h>
17 #include <linux/slab.h>
18 #include <linux/types.h>
19 #include <linux/uaccess.h>
20 #include <asm/unaligned.h>
21 #include <linux/skbuff.h>
22 #include <linux/ip.h>
23 #include <linux/icmp.h>
24 #include <linux/netdevice.h>
25 #include <linux/rtnetlink.h>
26 #include <net/sock.h>
27 #include <net/ip.h>
28 #include <net/icmp.h>
29 #include <net/route.h>
30 #include <net/cipso_ipv4.h>
31 #include <net/ip_fib.h>
32
33 /*
34 * Write options to IP header, record destination address to
35 * source route option, address of outgoing interface
36 * (we should already know it, so that this function is allowed be
37 * called only after routing decision) and timestamp,
38 * if we originate this datagram.
39 *
40 * daddr is real destination address, next hop is recorded in IP header.
41 * saddr is address of outgoing interface.
42 */
43
44 void ip_options_build(struct sk_buff *skb, struct ip_options *opt,
45 __be32 daddr, struct rtable *rt, int is_frag)
46 {
47 unsigned char *iph = skb_network_header(skb);
48
49 memcpy(&(IPCB(skb)->opt), opt, sizeof(struct ip_options));
50 memcpy(iph+sizeof(struct iphdr), opt->__data, opt->optlen);
51 opt = &(IPCB(skb)->opt);
52
53 if (opt->srr)
54 memcpy(iph+opt->srr+iph[opt->srr+1]-4, &daddr, 4);
55
56 if (!is_frag) {
57 if (opt->rr_needaddr)
58 ip_rt_get_source(iph+opt->rr+iph[opt->rr+2]-5, skb, rt);
59 if (opt->ts_needaddr)
60 ip_rt_get_source(iph+opt->ts+iph[opt->ts+2]-9, skb, rt);
61 if (opt->ts_needtime) {
62 __be32 midtime;
63
64 midtime = inet_current_timestamp();
65 memcpy(iph+opt->ts+iph[opt->ts+2]-5, &midtime, 4);
66 }
67 return;
68 }
69 if (opt->rr) {
70 memset(iph+opt->rr, IPOPT_NOP, iph[opt->rr+1]);
71 opt->rr = 0;
72 opt->rr_needaddr = 0;
73 }
74 if (opt->ts) {
75 memset(iph+opt->ts, IPOPT_NOP, iph[opt->ts+1]);
76 opt->ts = 0;
77 opt->ts_needaddr = opt->ts_needtime = 0;
78 }
79 }
80
81 /*
82 * Provided (sopt, skb) points to received options,
83 * build in dopt compiled option set appropriate for answering.
84 * i.e. invert SRR option, copy anothers,
85 * and grab room in RR/TS options.
86 *
87 * NOTE: dopt cannot point to skb.
88 */
89
90 int __ip_options_echo(struct net *net, struct ip_options *dopt,
91 struct sk_buff *skb, const struct ip_options *sopt)
92 {
93 unsigned char *sptr, *dptr;
94 int soffset, doffset;
95 int optlen;
96
97 memset(dopt, 0, sizeof(struct ip_options));
98
99 if (sopt->optlen == 0)
100 return 0;
101
102 sptr = skb_network_header(skb);
103 dptr = dopt->__data;
104
105 if (sopt->rr) {
106 optlen = sptr[sopt->rr+1];
107 soffset = sptr[sopt->rr+2];
108 dopt->rr = dopt->optlen + sizeof(struct iphdr);
109 memcpy(dptr, sptr+sopt->rr, optlen);
110 if (sopt->rr_needaddr && soffset <= optlen) {
111 if (soffset + 3 > optlen)
112 return -EINVAL;
113 dptr[2] = soffset + 4;
114 dopt->rr_needaddr = 1;
115 }
116 dptr += optlen;
117 dopt->optlen += optlen;
118 }
119 if (sopt->ts) {
120 optlen = sptr[sopt->ts+1];
121 soffset = sptr[sopt->ts+2];
122 dopt->ts = dopt->optlen + sizeof(struct iphdr);
123 memcpy(dptr, sptr+sopt->ts, optlen);
124 if (soffset <= optlen) {
125 if (sopt->ts_needaddr) {
126 if (soffset + 3 > optlen)
127 return -EINVAL;
128 dopt->ts_needaddr = 1;
129 soffset += 4;
130 }
131 if (sopt->ts_needtime) {
132 if (soffset + 3 > optlen)
133 return -EINVAL;
134 if ((dptr[3]&0xF) != IPOPT_TS_PRESPEC) {
135 dopt->ts_needtime = 1;
136 soffset += 4;
137 } else {
138 dopt->ts_needtime = 0;
139
140 if (soffset + 7 <= optlen) {
141 __be32 addr;
142
143 memcpy(&addr, dptr+soffset-1, 4);
144 if (inet_addr_type(net, addr) != RTN_UNICAST) {
145 dopt->ts_needtime = 1;
146 soffset += 8;
147 }
148 }
149 }
150 }
151 dptr[2] = soffset;
152 }
153 dptr += optlen;
154 dopt->optlen += optlen;
155 }
156 if (sopt->srr) {
157 unsigned char *start = sptr+sopt->srr;
158 __be32 faddr;
159
160 optlen = start[1];
161 soffset = start[2];
162 doffset = 0;
163 if (soffset > optlen)
164 soffset = optlen + 1;
165 soffset -= 4;
166 if (soffset > 3) {
167 memcpy(&faddr, &start[soffset-1], 4);
168 for (soffset -= 4, doffset = 4; soffset > 3; soffset -= 4, doffset += 4)
169 memcpy(&dptr[doffset-1], &start[soffset-1], 4);
170 /*
171 * RFC1812 requires to fix illegal source routes.
172 */
173 if (memcmp(&ip_hdr(skb)->saddr,
174 &start[soffset + 3], 4) == 0)
175 doffset -= 4;
176 }
177 if (doffset > 3) {
178 dopt->faddr = faddr;
179 dptr[0] = start[0];
180 dptr[1] = doffset+3;
181 dptr[2] = 4;
182 dptr += doffset+3;
183 dopt->srr = dopt->optlen + sizeof(struct iphdr);
184 dopt->optlen += doffset+3;
185 dopt->is_strictroute = sopt->is_strictroute;
186 }
187 }
188 if (sopt->cipso) {
189 optlen = sptr[sopt->cipso+1];
190 dopt->cipso = dopt->optlen+sizeof(struct iphdr);
191 memcpy(dptr, sptr+sopt->cipso, optlen);
192 dptr += optlen;
193 dopt->optlen += optlen;
194 }
195 while (dopt->optlen & 3) {
196 *dptr++ = IPOPT_END;
197 dopt->optlen++;
198 }
199 return 0;
200 }
201
202 /*
203 * Options "fragmenting", just fill options not
204 * allowed in fragments with NOOPs.
205 * Simple and stupid 8), but the most efficient way.
206 */
207
208 void ip_options_fragment(struct sk_buff *skb)
209 {
210 unsigned char *optptr = skb_network_header(skb) + sizeof(struct iphdr);
211 struct ip_options *opt = &(IPCB(skb)->opt);
212 int l = opt->optlen;
213 int optlen;
214
215 while (l > 0) {
216 switch (*optptr) {
217 case IPOPT_END:
218 return;
219 case IPOPT_NOOP:
220 l--;
221 optptr++;
222 continue;
223 }
224 optlen = optptr[1];
225 if (optlen < 2 || optlen > l)
226 return;
227 if (!IPOPT_COPIED(*optptr))
228 memset(optptr, IPOPT_NOOP, optlen);
229 l -= optlen;
230 optptr += optlen;
231 }
232 opt->ts = 0;
233 opt->rr = 0;
234 opt->rr_needaddr = 0;
235 opt->ts_needaddr = 0;
236 opt->ts_needtime = 0;
237 }
238
239 /* helper used by ip_options_compile() to call fib_compute_spec_dst()
240 * at most one time.
241 */
242 static void spec_dst_fill(__be32 *spec_dst, struct sk_buff *skb)
243 {
244 if (*spec_dst == htonl(INADDR_ANY))
245 *spec_dst = fib_compute_spec_dst(skb);
246 }
247
248 /*
249 * Verify options and fill pointers in struct options.
250 * Caller should clear *opt, and set opt->data.
251 * If opt == NULL, then skb->data should point to IP header.
252 */
253
254 int ip_options_compile(struct net *net,
255 struct ip_options *opt, struct sk_buff *skb)
256 {
257 __be32 spec_dst = htonl(INADDR_ANY);
258 unsigned char *pp_ptr = NULL;
259 struct rtable *rt = NULL;
260 unsigned char *optptr;
261 unsigned char *iph;
262 int optlen, l;
263
264 if (skb) {
265 rt = skb_rtable(skb);
266 optptr = (unsigned char *)&(ip_hdr(skb)[1]);
267 } else
268 optptr = opt->__data;
269 iph = optptr - sizeof(struct iphdr);
270
271 for (l = opt->optlen; l > 0; ) {
272 switch (*optptr) {
273 case IPOPT_END:
274 for (optptr++, l--; l > 0; optptr++, l--) {
275 if (*optptr != IPOPT_END) {
276 *optptr = IPOPT_END;
277 opt->is_changed = 1;
278 }
279 }
280 goto eol;
281 case IPOPT_NOOP:
282 l--;
283 optptr++;
284 continue;
285 }
286 if (unlikely(l < 2)) {
287 pp_ptr = optptr;
288 goto error;
289 }
290 optlen = optptr[1];
291 if (optlen < 2 || optlen > l) {
292 pp_ptr = optptr;
293 goto error;
294 }
295 switch (*optptr) {
296 case IPOPT_SSRR:
297 case IPOPT_LSRR:
298 if (optlen < 3) {
299 pp_ptr = optptr + 1;
300 goto error;
301 }
302 if (optptr[2] < 4) {
303 pp_ptr = optptr + 2;
304 goto error;
305 }
306 /* NB: cf RFC-1812 5.2.4.1 */
307 if (opt->srr) {
308 pp_ptr = optptr;
309 goto error;
310 }
311 if (!skb) {
312 if (optptr[2] != 4 || optlen < 7 || ((optlen-3) & 3)) {
313 pp_ptr = optptr + 1;
314 goto error;
315 }
316 memcpy(&opt->faddr, &optptr[3], 4);
317 if (optlen > 7)
318 memmove(&optptr[3], &optptr[7], optlen-7);
319 }
320 opt->is_strictroute = (optptr[0] == IPOPT_SSRR);
321 opt->srr = optptr - iph;
322 break;
323 case IPOPT_RR:
324 if (opt->rr) {
325 pp_ptr = optptr;
326 goto error;
327 }
328 if (optlen < 3) {
329 pp_ptr = optptr + 1;
330 goto error;
331 }
332 if (optptr[2] < 4) {
333 pp_ptr = optptr + 2;
334 goto error;
335 }
336 if (optptr[2] <= optlen) {
337 if (optptr[2]+3 > optlen) {
338 pp_ptr = optptr + 2;
339 goto error;
340 }
341 if (rt) {
342 spec_dst_fill(&spec_dst, skb);
343 memcpy(&optptr[optptr[2]-1], &spec_dst, 4);
344 opt->is_changed = 1;
345 }
346 optptr[2] += 4;
347 opt->rr_needaddr = 1;
348 }
349 opt->rr = optptr - iph;
350 break;
351 case IPOPT_TIMESTAMP:
352 if (opt->ts) {
353 pp_ptr = optptr;
354 goto error;
355 }
356 if (optlen < 4) {
357 pp_ptr = optptr + 1;
358 goto error;
359 }
360 if (optptr[2] < 5) {
361 pp_ptr = optptr + 2;
362 goto error;
363 }
364 if (optptr[2] <= optlen) {
365 unsigned char *timeptr = NULL;
366 if (optptr[2]+3 > optlen) {
367 pp_ptr = optptr + 2;
368 goto error;
369 }
370 switch (optptr[3]&0xF) {
371 case IPOPT_TS_TSONLY:
372 if (skb)
373 timeptr = &optptr[optptr[2]-1];
374 opt->ts_needtime = 1;
375 optptr[2] += 4;
376 break;
377 case IPOPT_TS_TSANDADDR:
378 if (optptr[2]+7 > optlen) {
379 pp_ptr = optptr + 2;
380 goto error;
381 }
382 if (rt) {
383 spec_dst_fill(&spec_dst, skb);
384 memcpy(&optptr[optptr[2]-1], &spec_dst, 4);
385 timeptr = &optptr[optptr[2]+3];
386 }
387 opt->ts_needaddr = 1;
388 opt->ts_needtime = 1;
389 optptr[2] += 8;
390 break;
391 case IPOPT_TS_PRESPEC:
392 if (optptr[2]+7 > optlen) {
393 pp_ptr = optptr + 2;
394 goto error;
395 }
396 {
397 __be32 addr;
398 memcpy(&addr, &optptr[optptr[2]-1], 4);
399 if (inet_addr_type(net, addr) == RTN_UNICAST)
400 break;
401 if (skb)
402 timeptr = &optptr[optptr[2]+3];
403 }
404 opt->ts_needtime = 1;
405 optptr[2] += 8;
406 break;
407 default:
408 if (!skb && !ns_capable(net->user_ns, CAP_NET_RAW)) {
409 pp_ptr = optptr + 3;
410 goto error;
411 }
412 break;
413 }
414 if (timeptr) {
415 __be32 midtime;
416
417 midtime = inet_current_timestamp();
418 memcpy(timeptr, &midtime, 4);
419 opt->is_changed = 1;
420 }
421 } else if ((optptr[3]&0xF) != IPOPT_TS_PRESPEC) {
422 unsigned int overflow = optptr[3]>>4;
423 if (overflow == 15) {
424 pp_ptr = optptr + 3;
425 goto error;
426 }
427 if (skb) {
428 optptr[3] = (optptr[3]&0xF)|((overflow+1)<<4);
429 opt->is_changed = 1;
430 }
431 }
432 opt->ts = optptr - iph;
433 break;
434 case IPOPT_RA:
435 if (optlen < 4) {
436 pp_ptr = optptr + 1;
437 goto error;
438 }
439 if (optptr[2] == 0 && optptr[3] == 0)
440 opt->router_alert = optptr - iph;
441 break;
442 case IPOPT_CIPSO:
443 if ((!skb && !ns_capable(net->user_ns, CAP_NET_RAW)) || opt->cipso) {
444 pp_ptr = optptr;
445 goto error;
446 }
447 opt->cipso = optptr - iph;
448 if (cipso_v4_validate(skb, &optptr)) {
449 pp_ptr = optptr;
450 goto error;
451 }
452 break;
453 case IPOPT_SEC:
454 case IPOPT_SID:
455 default:
456 if (!skb && !ns_capable(net->user_ns, CAP_NET_RAW)) {
457 pp_ptr = optptr;
458 goto error;
459 }
460 break;
461 }
462 l -= optlen;
463 optptr += optlen;
464 }
465
466 eol:
467 if (!pp_ptr)
468 return 0;
469
470 error:
471 if (skb) {
472 icmp_send(skb, ICMP_PARAMETERPROB, 0, htonl((pp_ptr-iph)<<24));
473 }
474 return -EINVAL;
475 }
476 EXPORT_SYMBOL(ip_options_compile);
477
478 /*
479 * Undo all the changes done by ip_options_compile().
480 */
481
482 void ip_options_undo(struct ip_options *opt)
483 {
484 if (opt->srr) {
485 unsigned char *optptr = opt->__data+opt->srr-sizeof(struct iphdr);
486 memmove(optptr+7, optptr+3, optptr[1]-7);
487 memcpy(optptr+3, &opt->faddr, 4);
488 }
489 if (opt->rr_needaddr) {
490 unsigned char *optptr = opt->__data+opt->rr-sizeof(struct iphdr);
491 optptr[2] -= 4;
492 memset(&optptr[optptr[2]-1], 0, 4);
493 }
494 if (opt->ts) {
495 unsigned char *optptr = opt->__data+opt->ts-sizeof(struct iphdr);
496 if (opt->ts_needtime) {
497 optptr[2] -= 4;
498 memset(&optptr[optptr[2]-1], 0, 4);
499 if ((optptr[3]&0xF) == IPOPT_TS_PRESPEC)
500 optptr[2] -= 4;
501 }
502 if (opt->ts_needaddr) {
503 optptr[2] -= 4;
504 memset(&optptr[optptr[2]-1], 0, 4);
505 }
506 }
507 }
508
509 static struct ip_options_rcu *ip_options_get_alloc(const int optlen)
510 {
511 return kzalloc(sizeof(struct ip_options_rcu) + ((optlen + 3) & ~3),
512 GFP_KERNEL);
513 }
514
515 static int ip_options_get_finish(struct net *net, struct ip_options_rcu **optp,
516 struct ip_options_rcu *opt, int optlen)
517 {
518 while (optlen & 3)
519 opt->opt.__data[optlen++] = IPOPT_END;
520 opt->opt.optlen = optlen;
521 if (optlen && ip_options_compile(net, &opt->opt, NULL)) {
522 kfree(opt);
523 return -EINVAL;
524 }
525 kfree(*optp);
526 *optp = opt;
527 return 0;
528 }
529
530 int ip_options_get_from_user(struct net *net, struct ip_options_rcu **optp,
531 unsigned char __user *data, int optlen)
532 {
533 struct ip_options_rcu *opt = ip_options_get_alloc(optlen);
534
535 if (!opt)
536 return -ENOMEM;
537 if (optlen && copy_from_user(opt->opt.__data, data, optlen)) {
538 kfree(opt);
539 return -EFAULT;
540 }
541 return ip_options_get_finish(net, optp, opt, optlen);
542 }
543
544 int ip_options_get(struct net *net, struct ip_options_rcu **optp,
545 unsigned char *data, int optlen)
546 {
547 struct ip_options_rcu *opt = ip_options_get_alloc(optlen);
548
549 if (!opt)
550 return -ENOMEM;
551 if (optlen)
552 memcpy(opt->opt.__data, data, optlen);
553 return ip_options_get_finish(net, optp, opt, optlen);
554 }
555
556 void ip_forward_options(struct sk_buff *skb)
557 {
558 struct ip_options *opt = &(IPCB(skb)->opt);
559 unsigned char *optptr;
560 struct rtable *rt = skb_rtable(skb);
561 unsigned char *raw = skb_network_header(skb);
562
563 if (opt->rr_needaddr) {
564 optptr = (unsigned char *)raw + opt->rr;
565 ip_rt_get_source(&optptr[optptr[2]-5], skb, rt);
566 opt->is_changed = 1;
567 }
568 if (opt->srr_is_hit) {
569 int srrptr, srrspace;
570
571 optptr = raw + opt->srr;
572
573 for ( srrptr = optptr[2], srrspace = optptr[1];
574 srrptr <= srrspace;
575 srrptr += 4
576 ) {
577 if (srrptr + 3 > srrspace)
578 break;
579 if (memcmp(&opt->nexthop, &optptr[srrptr-1], 4) == 0)
580 break;
581 }
582 if (srrptr + 3 <= srrspace) {
583 opt->is_changed = 1;
584 ip_hdr(skb)->daddr = opt->nexthop;
585 ip_rt_get_source(&optptr[srrptr-1], skb, rt);
586 optptr[2] = srrptr+4;
587 } else {
588 net_crit_ratelimited("%s(): Argh! Destination lost!\n",
589 __func__);
590 }
591 if (opt->ts_needaddr) {
592 optptr = raw + opt->ts;
593 ip_rt_get_source(&optptr[optptr[2]-9], skb, rt);
594 opt->is_changed = 1;
595 }
596 }
597 if (opt->is_changed) {
598 opt->is_changed = 0;
599 ip_send_check(ip_hdr(skb));
600 }
601 }
602
603 int ip_options_rcv_srr(struct sk_buff *skb)
604 {
605 struct ip_options *opt = &(IPCB(skb)->opt);
606 int srrspace, srrptr;
607 __be32 nexthop;
608 struct iphdr *iph = ip_hdr(skb);
609 unsigned char *optptr = skb_network_header(skb) + opt->srr;
610 struct rtable *rt = skb_rtable(skb);
611 struct rtable *rt2;
612 unsigned long orefdst;
613 int err;
614
615 if (!rt)
616 return 0;
617
618 if (skb->pkt_type != PACKET_HOST)
619 return -EINVAL;
620 if (rt->rt_type == RTN_UNICAST) {
621 if (!opt->is_strictroute)
622 return 0;
623 icmp_send(skb, ICMP_PARAMETERPROB, 0, htonl(16<<24));
624 return -EINVAL;
625 }
626 if (rt->rt_type != RTN_LOCAL)
627 return -EINVAL;
628
629 for (srrptr = optptr[2], srrspace = optptr[1]; srrptr <= srrspace; srrptr += 4) {
630 if (srrptr + 3 > srrspace) {
631 icmp_send(skb, ICMP_PARAMETERPROB, 0, htonl((opt->srr+2)<<24));
632 return -EINVAL;
633 }
634 memcpy(&nexthop, &optptr[srrptr-1], 4);
635
636 orefdst = skb->_skb_refdst;
637 skb_dst_set(skb, NULL);
638 err = ip_route_input(skb, nexthop, iph->saddr, iph->tos, skb->dev);
639 rt2 = skb_rtable(skb);
640 if (err || (rt2->rt_type != RTN_UNICAST && rt2->rt_type != RTN_LOCAL)) {
641 skb_dst_drop(skb);
642 skb->_skb_refdst = orefdst;
643 return -EINVAL;
644 }
645 refdst_drop(orefdst);
646 if (rt2->rt_type != RTN_LOCAL)
647 break;
648 /* Superfast 8) loopback forward */
649 iph->daddr = nexthop;
650 opt->is_changed = 1;
651 }
652 if (srrptr <= srrspace) {
653 opt->srr_is_hit = 1;
654 opt->nexthop = nexthop;
655 opt->is_changed = 1;
656 }
657 return 0;
658 }
659 EXPORT_SYMBOL(ip_options_rcv_srr);
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