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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 #include <linux/capability.h>
13 #include <linux/module.h>
14 #include <linux/slab.h>
15 #include <linux/types.h>
16 #include <asm/uaccess.h>
17 #include <asm/unaligned.h>
18 #include <linux/skbuff.h>
19 #include <linux/ip.h>
20 #include <linux/icmp.h>
21 #include <linux/netdevice.h>
22 #include <linux/rtnetlink.h>
23 #include <net/sock.h>
24 #include <net/ip.h>
25 #include <net/icmp.h>
26 #include <net/route.h>
27 #include <net/cipso_ipv4.h>
28
29 /*
30 * Write options to IP header, record destination address to
31 * source route option, address of outgoing interface
32 * (we should already know it, so that this function is allowed be
33 * called only after routing decision) and timestamp,
34 * if we originate this datagram.
35 *
36 * daddr is real destination address, next hop is recorded in IP header.
37 * saddr is address of outgoing interface.
38 */
39
40 void ip_options_build(struct sk_buff *skb, struct ip_options *opt,
41 __be32 daddr, struct rtable *rt, int is_frag)
42 {
43 unsigned char *iph = skb_network_header(skb);
44
45 memcpy(&(IPCB(skb)->opt), opt, sizeof(struct ip_options));
46 memcpy(iph+sizeof(struct iphdr), opt->__data, opt->optlen);
47 opt = &(IPCB(skb)->opt);
48
49 if (opt->srr)
50 memcpy(iph+opt->srr+iph[opt->srr+1]-4, &daddr, 4);
51
52 if (!is_frag) {
53 if (opt->rr_needaddr)
54 ip_rt_get_source(iph+opt->rr+iph[opt->rr+2]-5, skb, rt);
55 if (opt->ts_needaddr)
56 ip_rt_get_source(iph+opt->ts+iph[opt->ts+2]-9, skb, rt);
57 if (opt->ts_needtime) {
58 struct timespec tv;
59 __be32 midtime;
60 getnstimeofday(&tv);
61 midtime = htonl((tv.tv_sec % 86400) * MSEC_PER_SEC + tv.tv_nsec / NSEC_PER_MSEC);
62 memcpy(iph+opt->ts+iph[opt->ts+2]-5, &midtime, 4);
63 }
64 return;
65 }
66 if (opt->rr) {
67 memset(iph+opt->rr, IPOPT_NOP, iph[opt->rr+1]);
68 opt->rr = 0;
69 opt->rr_needaddr = 0;
70 }
71 if (opt->ts) {
72 memset(iph+opt->ts, IPOPT_NOP, iph[opt->ts+1]);
73 opt->ts = 0;
74 opt->ts_needaddr = opt->ts_needtime = 0;
75 }
76 }
77
78 /*
79 * Provided (sopt, skb) points to received options,
80 * build in dopt compiled option set appropriate for answering.
81 * i.e. invert SRR option, copy anothers,
82 * and grab room in RR/TS options.
83 *
84 * NOTE: dopt cannot point to skb.
85 */
86
87 int ip_options_echo(struct ip_options *dopt, struct sk_buff *skb)
88 {
89 const struct ip_options *sopt;
90 unsigned char *sptr, *dptr;
91 int soffset, doffset;
92 int optlen;
93 __be32 daddr;
94
95 memset(dopt, 0, sizeof(struct ip_options));
96
97 sopt = &(IPCB(skb)->opt);
98
99 if (sopt->optlen == 0)
100 return 0;
101
102 sptr = skb_network_header(skb);
103 dptr = dopt->__data;
104
105 daddr = skb_rtable(skb)->rt_spec_dst;
106
107 if (sopt->rr) {
108 optlen = sptr[sopt->rr+1];
109 soffset = sptr[sopt->rr+2];
110 dopt->rr = dopt->optlen + sizeof(struct iphdr);
111 memcpy(dptr, sptr+sopt->rr, optlen);
112 if (sopt->rr_needaddr && soffset <= optlen) {
113 if (soffset + 3 > optlen)
114 return -EINVAL;
115 dptr[2] = soffset + 4;
116 dopt->rr_needaddr = 1;
117 }
118 dptr += optlen;
119 dopt->optlen += optlen;
120 }
121 if (sopt->ts) {
122 optlen = sptr[sopt->ts+1];
123 soffset = sptr[sopt->ts+2];
124 dopt->ts = dopt->optlen + sizeof(struct iphdr);
125 memcpy(dptr, sptr+sopt->ts, optlen);
126 if (soffset <= optlen) {
127 if (sopt->ts_needaddr) {
128 if (soffset + 3 > optlen)
129 return -EINVAL;
130 dopt->ts_needaddr = 1;
131 soffset += 4;
132 }
133 if (sopt->ts_needtime) {
134 if (soffset + 3 > optlen)
135 return -EINVAL;
136 if ((dptr[3]&0xF) != IPOPT_TS_PRESPEC) {
137 dopt->ts_needtime = 1;
138 soffset += 4;
139 } else {
140 dopt->ts_needtime = 0;
141
142 if (soffset + 7 <= optlen) {
143 __be32 addr;
144
145 memcpy(&addr, dptr+soffset-1, 4);
146 if (inet_addr_type(dev_net(skb_dst(skb)->dev), addr) != RTN_UNICAST) {
147 dopt->ts_needtime = 1;
148 soffset += 8;
149 }
150 }
151 }
152 }
153 dptr[2] = soffset;
154 }
155 dptr += optlen;
156 dopt->optlen += optlen;
157 }
158 if (sopt->srr) {
159 unsigned char *start = sptr+sopt->srr;
160 __be32 faddr;
161
162 optlen = start[1];
163 soffset = start[2];
164 doffset = 0;
165 if (soffset > optlen)
166 soffset = optlen + 1;
167 soffset -= 4;
168 if (soffset > 3) {
169 memcpy(&faddr, &start[soffset-1], 4);
170 for (soffset-=4, doffset=4; soffset > 3; soffset-=4, doffset+=4)
171 memcpy(&dptr[doffset-1], &start[soffset-1], 4);
172 /*
173 * RFC1812 requires to fix illegal source routes.
174 */
175 if (memcmp(&ip_hdr(skb)->saddr,
176 &start[soffset + 3], 4) == 0)
177 doffset -= 4;
178 }
179 if (doffset > 3) {
180 memcpy(&start[doffset-1], &daddr, 4);
181 dopt->faddr = faddr;
182 dptr[0] = start[0];
183 dptr[1] = doffset+3;
184 dptr[2] = 4;
185 dptr += doffset+3;
186 dopt->srr = dopt->optlen + sizeof(struct iphdr);
187 dopt->optlen += doffset+3;
188 dopt->is_strictroute = sopt->is_strictroute;
189 }
190 }
191 if (sopt->cipso) {
192 optlen = sptr[sopt->cipso+1];
193 dopt->cipso = dopt->optlen+sizeof(struct iphdr);
194 memcpy(dptr, sptr+sopt->cipso, optlen);
195 dptr += optlen;
196 dopt->optlen += optlen;
197 }
198 while (dopt->optlen & 3) {
199 *dptr++ = IPOPT_END;
200 dopt->optlen++;
201 }
202 return 0;
203 }
204
205 /*
206 * Options "fragmenting", just fill options not
207 * allowed in fragments with NOOPs.
208 * Simple and stupid 8), but the most efficient way.
209 */
210
211 void ip_options_fragment(struct sk_buff * skb)
212 {
213 unsigned char *optptr = skb_network_header(skb) + sizeof(struct iphdr);
214 struct ip_options * opt = &(IPCB(skb)->opt);
215 int l = opt->optlen;
216 int optlen;
217
218 while (l > 0) {
219 switch (*optptr) {
220 case IPOPT_END:
221 return;
222 case IPOPT_NOOP:
223 l--;
224 optptr++;
225 continue;
226 }
227 optlen = optptr[1];
228 if (optlen<2 || optlen>l)
229 return;
230 if (!IPOPT_COPIED(*optptr))
231 memset(optptr, IPOPT_NOOP, optlen);
232 l -= optlen;
233 optptr += optlen;
234 }
235 opt->ts = 0;
236 opt->rr = 0;
237 opt->rr_needaddr = 0;
238 opt->ts_needaddr = 0;
239 opt->ts_needtime = 0;
240 }
241
242 /*
243 * Verify options and fill pointers in struct options.
244 * Caller should clear *opt, and set opt->data.
245 * If opt == NULL, then skb->data should point to IP header.
246 */
247
248 int ip_options_compile(struct net *net,
249 struct ip_options * opt, struct sk_buff * skb)
250 {
251 int l;
252 unsigned char * iph;
253 unsigned char * optptr;
254 int optlen;
255 unsigned char * pp_ptr = NULL;
256 struct rtable *rt = NULL;
257
258 if (skb != NULL) {
259 rt = skb_rtable(skb);
260 optptr = (unsigned char *)&(ip_hdr(skb)[1]);
261 } else
262 optptr = opt->__data;
263 iph = optptr - sizeof(struct iphdr);
264
265 for (l = opt->optlen; l > 0; ) {
266 switch (*optptr) {
267 case IPOPT_END:
268 for (optptr++, l--; l>0; optptr++, l--) {
269 if (*optptr != IPOPT_END) {
270 *optptr = IPOPT_END;
271 opt->is_changed = 1;
272 }
273 }
274 goto eol;
275 case IPOPT_NOOP:
276 l--;
277 optptr++;
278 continue;
279 }
280 optlen = optptr[1];
281 if (optlen<2 || optlen>l) {
282 pp_ptr = optptr;
283 goto error;
284 }
285 switch (*optptr) {
286 case IPOPT_SSRR:
287 case IPOPT_LSRR:
288 if (optlen < 3) {
289 pp_ptr = optptr + 1;
290 goto error;
291 }
292 if (optptr[2] < 4) {
293 pp_ptr = optptr + 2;
294 goto error;
295 }
296 /* NB: cf RFC-1812 5.2.4.1 */
297 if (opt->srr) {
298 pp_ptr = optptr;
299 goto error;
300 }
301 if (!skb) {
302 if (optptr[2] != 4 || optlen < 7 || ((optlen-3) & 3)) {
303 pp_ptr = optptr + 1;
304 goto error;
305 }
306 memcpy(&opt->faddr, &optptr[3], 4);
307 if (optlen > 7)
308 memmove(&optptr[3], &optptr[7], optlen-7);
309 }
310 opt->is_strictroute = (optptr[0] == IPOPT_SSRR);
311 opt->srr = optptr - iph;
312 break;
313 case IPOPT_RR:
314 if (opt->rr) {
315 pp_ptr = optptr;
316 goto error;
317 }
318 if (optlen < 3) {
319 pp_ptr = optptr + 1;
320 goto error;
321 }
322 if (optptr[2] < 4) {
323 pp_ptr = optptr + 2;
324 goto error;
325 }
326 if (optptr[2] <= optlen) {
327 if (optptr[2]+3 > optlen) {
328 pp_ptr = optptr + 2;
329 goto error;
330 }
331 if (rt) {
332 memcpy(&optptr[optptr[2]-1], &rt->rt_spec_dst, 4);
333 opt->is_changed = 1;
334 }
335 optptr[2] += 4;
336 opt->rr_needaddr = 1;
337 }
338 opt->rr = optptr - iph;
339 break;
340 case IPOPT_TIMESTAMP:
341 if (opt->ts) {
342 pp_ptr = optptr;
343 goto error;
344 }
345 if (optlen < 4) {
346 pp_ptr = optptr + 1;
347 goto error;
348 }
349 if (optptr[2] < 5) {
350 pp_ptr = optptr + 2;
351 goto error;
352 }
353 if (optptr[2] <= optlen) {
354 unsigned char *timeptr = NULL;
355 if (optptr[2]+3 > optptr[1]) {
356 pp_ptr = optptr + 2;
357 goto error;
358 }
359 switch (optptr[3]&0xF) {
360 case IPOPT_TS_TSONLY:
361 opt->ts = optptr - iph;
362 if (skb)
363 timeptr = &optptr[optptr[2]-1];
364 opt->ts_needtime = 1;
365 optptr[2] += 4;
366 break;
367 case IPOPT_TS_TSANDADDR:
368 if (optptr[2]+7 > optptr[1]) {
369 pp_ptr = optptr + 2;
370 goto error;
371 }
372 opt->ts = optptr - iph;
373 if (rt) {
374 memcpy(&optptr[optptr[2]-1], &rt->rt_spec_dst, 4);
375 timeptr = &optptr[optptr[2]+3];
376 }
377 opt->ts_needaddr = 1;
378 opt->ts_needtime = 1;
379 optptr[2] += 8;
380 break;
381 case IPOPT_TS_PRESPEC:
382 if (optptr[2]+7 > optptr[1]) {
383 pp_ptr = optptr + 2;
384 goto error;
385 }
386 opt->ts = optptr - iph;
387 {
388 __be32 addr;
389 memcpy(&addr, &optptr[optptr[2]-1], 4);
390 if (inet_addr_type(net, addr) == RTN_UNICAST)
391 break;
392 if (skb)
393 timeptr = &optptr[optptr[2]+3];
394 }
395 opt->ts_needtime = 1;
396 optptr[2] += 8;
397 break;
398 default:
399 if (!skb && !capable(CAP_NET_RAW)) {
400 pp_ptr = optptr + 3;
401 goto error;
402 }
403 break;
404 }
405 if (timeptr) {
406 struct timespec tv;
407 u32 midtime;
408 getnstimeofday(&tv);
409 midtime = (tv.tv_sec % 86400) * MSEC_PER_SEC + tv.tv_nsec / NSEC_PER_MSEC;
410 put_unaligned_be32(midtime, timeptr);
411 opt->is_changed = 1;
412 }
413 } else {
414 unsigned overflow = optptr[3]>>4;
415 if (overflow == 15) {
416 pp_ptr = optptr + 3;
417 goto error;
418 }
419 opt->ts = optptr - iph;
420 if (skb) {
421 optptr[3] = (optptr[3]&0xF)|((overflow+1)<<4);
422 opt->is_changed = 1;
423 }
424 }
425 break;
426 case IPOPT_RA:
427 if (optlen < 4) {
428 pp_ptr = optptr + 1;
429 goto error;
430 }
431 if (optptr[2] == 0 && optptr[3] == 0)
432 opt->router_alert = optptr - iph;
433 break;
434 case IPOPT_CIPSO:
435 if ((!skb && !capable(CAP_NET_RAW)) || opt->cipso) {
436 pp_ptr = optptr;
437 goto error;
438 }
439 opt->cipso = optptr - iph;
440 if (cipso_v4_validate(skb, &optptr)) {
441 pp_ptr = optptr;
442 goto error;
443 }
444 break;
445 case IPOPT_SEC:
446 case IPOPT_SID:
447 default:
448 if (!skb && !capable(CAP_NET_RAW)) {
449 pp_ptr = optptr;
450 goto error;
451 }
452 break;
453 }
454 l -= optlen;
455 optptr += optlen;
456 }
457
458 eol:
459 if (!pp_ptr)
460 return 0;
461
462 error:
463 if (skb) {
464 icmp_send(skb, ICMP_PARAMETERPROB, 0, htonl((pp_ptr-iph)<<24));
465 }
466 return -EINVAL;
467 }
468 EXPORT_SYMBOL(ip_options_compile);
469
470 /*
471 * Undo all the changes done by ip_options_compile().
472 */
473
474 void ip_options_undo(struct ip_options * opt)
475 {
476 if (opt->srr) {
477 unsigned char * optptr = opt->__data+opt->srr-sizeof(struct iphdr);
478 memmove(optptr+7, optptr+3, optptr[1]-7);
479 memcpy(optptr+3, &opt->faddr, 4);
480 }
481 if (opt->rr_needaddr) {
482 unsigned char * optptr = opt->__data+opt->rr-sizeof(struct iphdr);
483 optptr[2] -= 4;
484 memset(&optptr[optptr[2]-1], 0, 4);
485 }
486 if (opt->ts) {
487 unsigned char * optptr = opt->__data+opt->ts-sizeof(struct iphdr);
488 if (opt->ts_needtime) {
489 optptr[2] -= 4;
490 memset(&optptr[optptr[2]-1], 0, 4);
491 if ((optptr[3]&0xF) == IPOPT_TS_PRESPEC)
492 optptr[2] -= 4;
493 }
494 if (opt->ts_needaddr) {
495 optptr[2] -= 4;
496 memset(&optptr[optptr[2]-1], 0, 4);
497 }
498 }
499 }
500
501 static struct ip_options_rcu *ip_options_get_alloc(const int optlen)
502 {
503 return kzalloc(sizeof(struct ip_options_rcu) + ((optlen + 3) & ~3),
504 GFP_KERNEL);
505 }
506
507 static int ip_options_get_finish(struct net *net, struct ip_options_rcu **optp,
508 struct ip_options_rcu *opt, int optlen)
509 {
510 while (optlen & 3)
511 opt->opt.__data[optlen++] = IPOPT_END;
512 opt->opt.optlen = optlen;
513 if (optlen && ip_options_compile(net, &opt->opt, NULL)) {
514 kfree(opt);
515 return -EINVAL;
516 }
517 kfree(*optp);
518 *optp = opt;
519 return 0;
520 }
521
522 int ip_options_get_from_user(struct net *net, struct ip_options_rcu **optp,
523 unsigned char __user *data, int optlen)
524 {
525 struct ip_options_rcu *opt = ip_options_get_alloc(optlen);
526
527 if (!opt)
528 return -ENOMEM;
529 if (optlen && copy_from_user(opt->opt.__data, data, optlen)) {
530 kfree(opt);
531 return -EFAULT;
532 }
533 return ip_options_get_finish(net, optp, opt, optlen);
534 }
535
536 int ip_options_get(struct net *net, struct ip_options_rcu **optp,
537 unsigned char *data, int optlen)
538 {
539 struct ip_options_rcu *opt = ip_options_get_alloc(optlen);
540
541 if (!opt)
542 return -ENOMEM;
543 if (optlen)
544 memcpy(opt->opt.__data, data, optlen);
545 return ip_options_get_finish(net, optp, opt, optlen);
546 }
547
548 void ip_forward_options(struct sk_buff *skb)
549 {
550 struct ip_options * opt = &(IPCB(skb)->opt);
551 unsigned char * optptr;
552 struct rtable *rt = skb_rtable(skb);
553 unsigned char *raw = skb_network_header(skb);
554
555 if (opt->rr_needaddr) {
556 optptr = (unsigned char *)raw + opt->rr;
557 ip_rt_get_source(&optptr[optptr[2]-5], skb, rt);
558 opt->is_changed = 1;
559 }
560 if (opt->srr_is_hit) {
561 int srrptr, srrspace;
562
563 optptr = raw + opt->srr;
564
565 for ( srrptr=optptr[2], srrspace = optptr[1];
566 srrptr <= srrspace;
567 srrptr += 4
568 ) {
569 if (srrptr + 3 > srrspace)
570 break;
571 if (memcmp(&opt->nexthop, &optptr[srrptr-1], 4) == 0)
572 break;
573 }
574 if (srrptr + 3 <= srrspace) {
575 opt->is_changed = 1;
576 ip_hdr(skb)->daddr = opt->nexthop;
577 ip_rt_get_source(&optptr[srrptr-1], skb, rt);
578 optptr[2] = srrptr+4;
579 } else if (net_ratelimit())
580 printk(KERN_CRIT "ip_forward(): Argh! Destination lost!\n");
581 if (opt->ts_needaddr) {
582 optptr = raw + opt->ts;
583 ip_rt_get_source(&optptr[optptr[2]-9], skb, rt);
584 opt->is_changed = 1;
585 }
586 }
587 if (opt->is_changed) {
588 opt->is_changed = 0;
589 ip_send_check(ip_hdr(skb));
590 }
591 }
592
593 int ip_options_rcv_srr(struct sk_buff *skb)
594 {
595 struct ip_options *opt = &(IPCB(skb)->opt);
596 int srrspace, srrptr;
597 __be32 nexthop;
598 struct iphdr *iph = ip_hdr(skb);
599 unsigned char *optptr = skb_network_header(skb) + opt->srr;
600 struct rtable *rt = skb_rtable(skb);
601 struct rtable *rt2;
602 unsigned long orefdst;
603 int err;
604
605 if (!rt)
606 return 0;
607
608 if (skb->pkt_type != PACKET_HOST)
609 return -EINVAL;
610 if (rt->rt_type == RTN_UNICAST) {
611 if (!opt->is_strictroute)
612 return 0;
613 icmp_send(skb, ICMP_PARAMETERPROB, 0, htonl(16<<24));
614 return -EINVAL;
615 }
616 if (rt->rt_type != RTN_LOCAL)
617 return -EINVAL;
618
619 for (srrptr=optptr[2], srrspace = optptr[1]; srrptr <= srrspace; srrptr += 4) {
620 if (srrptr + 3 > srrspace) {
621 icmp_send(skb, ICMP_PARAMETERPROB, 0, htonl((opt->srr+2)<<24));
622 return -EINVAL;
623 }
624 memcpy(&nexthop, &optptr[srrptr-1], 4);
625
626 orefdst = skb->_skb_refdst;
627 skb_dst_set(skb, NULL);
628 err = ip_route_input(skb, nexthop, iph->saddr, iph->tos, skb->dev);
629 rt2 = skb_rtable(skb);
630 if (err || (rt2->rt_type != RTN_UNICAST && rt2->rt_type != RTN_LOCAL)) {
631 skb_dst_drop(skb);
632 skb->_skb_refdst = orefdst;
633 return -EINVAL;
634 }
635 refdst_drop(orefdst);
636 if (rt2->rt_type != RTN_LOCAL)
637 break;
638 /* Superfast 8) loopback forward */
639 iph->daddr = nexthop;
640 opt->is_changed = 1;
641 }
642 if (srrptr <= srrspace) {
643 opt->srr_is_hit = 1;
644 opt->nexthop = nexthop;
645 opt->is_changed = 1;
646 }
647 return 0;
648 }
649 EXPORT_SYMBOL(ip_options_rcv_srr);
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