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