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Linux 3.8-rc7
[cris-mirror.git] / net / ipv4 / ip_options.c
blobf6289bf6f3325edc2c78541eca88e546e5ec97c9
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 <asm/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 struct timespec tv;
62 __be32 midtime;
63 getnstimeofday(&tv);
64 midtime = htonl((tv.tv_sec % 86400) * MSEC_PER_SEC + tv.tv_nsec / NSEC_PER_MSEC);
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 ip_options *dopt, struct sk_buff *skb)
91 {
92 const struct ip_options *sopt;
93 unsigned char *sptr, *dptr;
94 int soffset, doffset;
95 int optlen;
96
97 memset(dopt, 0, sizeof(struct ip_options));
98
99 sopt = &(IPCB(skb)->opt);
100
101 if (sopt->optlen == 0)
102 return 0;
103
104 sptr = skb_network_header(skb);
105 dptr = dopt->__data;
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 __be32 daddr = fib_compute_spec_dst(skb);
181
182 memcpy(&start[doffset-1], &daddr, 4);
183 dopt->faddr = faddr;
184 dptr[0] = start[0];
185 dptr[1] = doffset+3;
186 dptr[2] = 4;
187 dptr += doffset+3;
188 dopt->srr = dopt->optlen + sizeof(struct iphdr);
189 dopt->optlen += doffset+3;
190 dopt->is_strictroute = sopt->is_strictroute;
191 }
192 }
193 if (sopt->cipso) {
194 optlen = sptr[sopt->cipso+1];
195 dopt->cipso = dopt->optlen+sizeof(struct iphdr);
196 memcpy(dptr, sptr+sopt->cipso, optlen);
197 dptr += optlen;
198 dopt->optlen += optlen;
199 }
200 while (dopt->optlen & 3) {
201 *dptr++ = IPOPT_END;
202 dopt->optlen++;
203 }
204 return 0;
205 }
206
207 /*
208 * Options "fragmenting", just fill options not
209 * allowed in fragments with NOOPs.
210 * Simple and stupid 8), but the most efficient way.
211 */
212
213 void ip_options_fragment(struct sk_buff *skb)
214 {
215 unsigned char *optptr = skb_network_header(skb) + sizeof(struct iphdr);
216 struct ip_options *opt = &(IPCB(skb)->opt);
217 int l = opt->optlen;
218 int optlen;
219
220 while (l > 0) {
221 switch (*optptr) {
222 case IPOPT_END:
223 return;
224 case IPOPT_NOOP:
225 l--;
226 optptr++;
227 continue;
228 }
229 optlen = optptr[1];
230 if (optlen<2 || optlen>l)
231 return;
232 if (!IPOPT_COPIED(*optptr))
233 memset(optptr, IPOPT_NOOP, optlen);
234 l -= optlen;
235 optptr += optlen;
236 }
237 opt->ts = 0;
238 opt->rr = 0;
239 opt->rr_needaddr = 0;
240 opt->ts_needaddr = 0;
241 opt->ts_needtime = 0;
242 }
243
244 /* helper used by ip_options_compile() to call fib_compute_spec_dst()
245 * at most one time.
246 */
247 static void spec_dst_fill(__be32 *spec_dst, struct sk_buff *skb)
248 {
249 if (*spec_dst == htonl(INADDR_ANY))
250 *spec_dst = fib_compute_spec_dst(skb);
251 }
252
253 /*
254 * Verify options and fill pointers in struct options.
255 * Caller should clear *opt, and set opt->data.
256 * If opt == NULL, then skb->data should point to IP header.
257 */
258
259 int ip_options_compile(struct net *net,
260 struct ip_options *opt, struct sk_buff *skb)
261 {
262 __be32 spec_dst = htonl(INADDR_ANY);
263 unsigned char *pp_ptr = NULL;
264 struct rtable *rt = NULL;
265 unsigned char *optptr;
266 unsigned char *iph;
267 int optlen, l;
268
269 if (skb != NULL) {
270 rt = skb_rtable(skb);
271 optptr = (unsigned char *)&(ip_hdr(skb)[1]);
272 } else
273 optptr = opt->__data;
274 iph = optptr - sizeof(struct iphdr);
275
276 for (l = opt->optlen; l > 0; ) {
277 switch (*optptr) {
278 case IPOPT_END:
279 for (optptr++, l--; l>0; optptr++, l--) {
280 if (*optptr != IPOPT_END) {
281 *optptr = IPOPT_END;
282 opt->is_changed = 1;
283 }
284 }
285 goto eol;
286 case IPOPT_NOOP:
287 l--;
288 optptr++;
289 continue;
290 }
291 optlen = optptr[1];
292 if (optlen<2 || optlen>l) {
293 pp_ptr = optptr;
294 goto error;
295 }
296 switch (*optptr) {
297 case IPOPT_SSRR:
298 case IPOPT_LSRR:
299 if (optlen < 3) {
300 pp_ptr = optptr + 1;
301 goto error;
302 }
303 if (optptr[2] < 4) {
304 pp_ptr = optptr + 2;
305 goto error;
306 }
307 /* NB: cf RFC-1812 5.2.4.1 */
308 if (opt->srr) {
309 pp_ptr = optptr;
310 goto error;
311 }
312 if (!skb) {
313 if (optptr[2] != 4 || optlen < 7 || ((optlen-3) & 3)) {
314 pp_ptr = optptr + 1;
315 goto error;
316 }
317 memcpy(&opt->faddr, &optptr[3], 4);
318 if (optlen > 7)
319 memmove(&optptr[3], &optptr[7], optlen-7);
320 }
321 opt->is_strictroute = (optptr[0] == IPOPT_SSRR);
322 opt->srr = optptr - iph;
323 break;
324 case IPOPT_RR:
325 if (opt->rr) {
326 pp_ptr = optptr;
327 goto error;
328 }
329 if (optlen < 3) {
330 pp_ptr = optptr + 1;
331 goto error;
332 }
333 if (optptr[2] < 4) {
334 pp_ptr = optptr + 2;
335 goto error;
336 }
337 if (optptr[2] <= optlen) {
338 if (optptr[2]+3 > optlen) {
339 pp_ptr = optptr + 2;
340 goto error;
341 }
342 if (rt) {
343 spec_dst_fill(&spec_dst, skb);
344 memcpy(&optptr[optptr[2]-1], &spec_dst, 4);
345 opt->is_changed = 1;
346 }
347 optptr[2] += 4;
348 opt->rr_needaddr = 1;
349 }
350 opt->rr = optptr - iph;
351 break;
352 case IPOPT_TIMESTAMP:
353 if (opt->ts) {
354 pp_ptr = optptr;
355 goto error;
356 }
357 if (optlen < 4) {
358 pp_ptr = optptr + 1;
359 goto error;
360 }
361 if (optptr[2] < 5) {
362 pp_ptr = optptr + 2;
363 goto error;
364 }
365 if (optptr[2] <= optlen) {
366 unsigned char *timeptr = NULL;
367 if (optptr[2]+3 > optptr[1]) {
368 pp_ptr = optptr + 2;
369 goto error;
370 }
371 switch (optptr[3]&0xF) {
372 case IPOPT_TS_TSONLY:
373 opt->ts = optptr - iph;
374 if (skb)
375 timeptr = &optptr[optptr[2]-1];
376 opt->ts_needtime = 1;
377 optptr[2] += 4;
378 break;
379 case IPOPT_TS_TSANDADDR:
380 if (optptr[2]+7 > optptr[1]) {
381 pp_ptr = optptr + 2;
382 goto error;
383 }
384 opt->ts = optptr - iph;
385 if (rt) {
386 spec_dst_fill(&spec_dst, skb);
387 memcpy(&optptr[optptr[2]-1], &spec_dst, 4);
388 timeptr = &optptr[optptr[2]+3];
389 }
390 opt->ts_needaddr = 1;
391 opt->ts_needtime = 1;
392 optptr[2] += 8;
393 break;
394 case IPOPT_TS_PRESPEC:
395 if (optptr[2]+7 > optptr[1]) {
396 pp_ptr = optptr + 2;
397 goto error;
398 }
399 opt->ts = optptr - iph;
400 {
401 __be32 addr;
402 memcpy(&addr, &optptr[optptr[2]-1], 4);
403 if (inet_addr_type(net, addr) == RTN_UNICAST)
404 break;
405 if (skb)
406 timeptr = &optptr[optptr[2]+3];
407 }
408 opt->ts_needtime = 1;
409 optptr[2] += 8;
410 break;
411 default:
412 if (!skb && !ns_capable(net->user_ns, CAP_NET_RAW)) {
413 pp_ptr = optptr + 3;
414 goto error;
415 }
416 break;
417 }
418 if (timeptr) {
419 struct timespec tv;
420 u32 midtime;
421 getnstimeofday(&tv);
422 midtime = (tv.tv_sec % 86400) * MSEC_PER_SEC + tv.tv_nsec / NSEC_PER_MSEC;
423 put_unaligned_be32(midtime, timeptr);
424 opt->is_changed = 1;
425 }
426 } else {
427 unsigned int overflow = optptr[3]>>4;
428 if (overflow == 15) {
429 pp_ptr = optptr + 3;
430 goto error;
431 }
432 opt->ts = optptr - iph;
433 if (skb) {
434 optptr[3] = (optptr[3]&0xF)|((overflow+1)<<4);
435 opt->is_changed = 1;
436 }
437 }
438 break;
439 case IPOPT_RA:
440 if (optlen < 4) {
441 pp_ptr = optptr + 1;
442 goto error;
443 }
444 if (optptr[2] == 0 && optptr[3] == 0)
445 opt->router_alert = optptr - iph;
446 break;
447 case IPOPT_CIPSO:
448 if ((!skb && !ns_capable(net->user_ns, CAP_NET_RAW)) || opt->cipso) {
449 pp_ptr = optptr;
450 goto error;
451 }
452 opt->cipso = optptr - iph;
453 if (cipso_v4_validate(skb, &optptr)) {
454 pp_ptr = optptr;
455 goto error;
456 }
457 break;
458 case IPOPT_SEC:
459 case IPOPT_SID:
460 default:
461 if (!skb && !ns_capable(net->user_ns, CAP_NET_RAW)) {
462 pp_ptr = optptr;
463 goto error;
464 }
465 break;
466 }
467 l -= optlen;
468 optptr += optlen;
469 }
470
471 eol:
472 if (!pp_ptr)
473 return 0;
474
475 error:
476 if (skb) {
477 icmp_send(skb, ICMP_PARAMETERPROB, 0, htonl((pp_ptr-iph)<<24));
478 }
479 return -EINVAL;
480 }
481 EXPORT_SYMBOL(ip_options_compile);
482
483 /*
484 * Undo all the changes done by ip_options_compile().
485 */
486
487 void ip_options_undo(struct ip_options *opt)
488 {
489 if (opt->srr) {
490 unsigned char *optptr = opt->__data+opt->srr-sizeof(struct iphdr);
491 memmove(optptr+7, optptr+3, optptr[1]-7);
492 memcpy(optptr+3, &opt->faddr, 4);
493 }
494 if (opt->rr_needaddr) {
495 unsigned char *optptr = opt->__data+opt->rr-sizeof(struct iphdr);
496 optptr[2] -= 4;
497 memset(&optptr[optptr[2]-1], 0, 4);
498 }
499 if (opt->ts) {
500 unsigned char *optptr = opt->__data+opt->ts-sizeof(struct iphdr);
501 if (opt->ts_needtime) {
502 optptr[2] -= 4;
503 memset(&optptr[optptr[2]-1], 0, 4);
504 if ((optptr[3]&0xF) == IPOPT_TS_PRESPEC)
505 optptr[2] -= 4;
506 }
507 if (opt->ts_needaddr) {
508 optptr[2] -= 4;
509 memset(&optptr[optptr[2]-1], 0, 4);
510 }
511 }
512 }
513
514 static struct ip_options_rcu *ip_options_get_alloc(const int optlen)
515 {
516 return kzalloc(sizeof(struct ip_options_rcu) + ((optlen + 3) & ~3),
517 GFP_KERNEL);
518 }
519
520 static int ip_options_get_finish(struct net *net, struct ip_options_rcu **optp,
521 struct ip_options_rcu *opt, int optlen)
522 {
523 while (optlen & 3)
524 opt->opt.__data[optlen++] = IPOPT_END;
525 opt->opt.optlen = optlen;
526 if (optlen && ip_options_compile(net, &opt->opt, NULL)) {
527 kfree(opt);
528 return -EINVAL;
529 }
530 kfree(*optp);
531 *optp = opt;
532 return 0;
533 }
534
535 int ip_options_get_from_user(struct net *net, struct ip_options_rcu **optp,
536 unsigned char __user *data, int optlen)
537 {
538 struct ip_options_rcu *opt = ip_options_get_alloc(optlen);
539
540 if (!opt)
541 return -ENOMEM;
542 if (optlen && copy_from_user(opt->opt.__data, data, optlen)) {
543 kfree(opt);
544 return -EFAULT;
545 }
546 return ip_options_get_finish(net, optp, opt, optlen);
547 }
548
549 int ip_options_get(struct net *net, struct ip_options_rcu **optp,
550 unsigned char *data, int optlen)
551 {
552 struct ip_options_rcu *opt = ip_options_get_alloc(optlen);
553
554 if (!opt)
555 return -ENOMEM;
556 if (optlen)
557 memcpy(opt->opt.__data, data, optlen);
558 return ip_options_get_finish(net, optp, opt, optlen);
559 }
560
561 void ip_forward_options(struct sk_buff *skb)
562 {
563 struct ip_options *opt = &(IPCB(skb)->opt);
564 unsigned char *optptr;
565 struct rtable *rt = skb_rtable(skb);
566 unsigned char *raw = skb_network_header(skb);
567
568 if (opt->rr_needaddr) {
569 optptr = (unsigned char *)raw + opt->rr;
570 ip_rt_get_source(&optptr[optptr[2]-5], skb, rt);
571 opt->is_changed = 1;
572 }
573 if (opt->srr_is_hit) {
574 int srrptr, srrspace;
575
576 optptr = raw + opt->srr;
577
578 for ( srrptr=optptr[2], srrspace = optptr[1];
579 srrptr <= srrspace;
580 srrptr += 4
581 ) {
582 if (srrptr + 3 > srrspace)
583 break;
584 if (memcmp(&opt->nexthop, &optptr[srrptr-1], 4) == 0)
585 break;
586 }
587 if (srrptr + 3 <= srrspace) {
588 opt->is_changed = 1;
589 ip_hdr(skb)->daddr = opt->nexthop;
590 ip_rt_get_source(&optptr[srrptr-1], skb, rt);
591 optptr[2] = srrptr+4;
592 } else {
593 net_crit_ratelimited("%s(): Argh! Destination lost!\n",
594 __func__);
595 }
596 if (opt->ts_needaddr) {
597 optptr = raw + opt->ts;
598 ip_rt_get_source(&optptr[optptr[2]-9], skb, rt);
599 opt->is_changed = 1;
600 }
601 }
602 if (opt->is_changed) {
603 opt->is_changed = 0;
604 ip_send_check(ip_hdr(skb));
605 }
606 }
607
608 int ip_options_rcv_srr(struct sk_buff *skb)
609 {
610 struct ip_options *opt = &(IPCB(skb)->opt);
611 int srrspace, srrptr;
612 __be32 nexthop;
613 struct iphdr *iph = ip_hdr(skb);
614 unsigned char *optptr = skb_network_header(skb) + opt->srr;
615 struct rtable *rt = skb_rtable(skb);
616 struct rtable *rt2;
617 unsigned long orefdst;
618 int err;
619
620 if (!rt)
621 return 0;
622
623 if (skb->pkt_type != PACKET_HOST)
624 return -EINVAL;
625 if (rt->rt_type == RTN_UNICAST) {
626 if (!opt->is_strictroute)
627 return 0;
628 icmp_send(skb, ICMP_PARAMETERPROB, 0, htonl(16<<24));
629 return -EINVAL;
630 }
631 if (rt->rt_type != RTN_LOCAL)
632 return -EINVAL;
633
634 for (srrptr=optptr[2], srrspace = optptr[1]; srrptr <= srrspace; srrptr += 4) {
635 if (srrptr + 3 > srrspace) {
636 icmp_send(skb, ICMP_PARAMETERPROB, 0, htonl((opt->srr+2)<<24));
637 return -EINVAL;
638 }
639 memcpy(&nexthop, &optptr[srrptr-1], 4);
640
641 orefdst = skb->_skb_refdst;
642 skb_dst_set(skb, NULL);
643 err = ip_route_input(skb, nexthop, iph->saddr, iph->tos, skb->dev);
644 rt2 = skb_rtable(skb);
645 if (err || (rt2->rt_type != RTN_UNICAST && rt2->rt_type != RTN_LOCAL)) {
646 skb_dst_drop(skb);
647 skb->_skb_refdst = orefdst;
648 return -EINVAL;
649 }
650 refdst_drop(orefdst);
651 if (rt2->rt_type != RTN_LOCAL)
652 break;
653 /* Superfast 8) loopback forward */
654 iph->daddr = nexthop;
655 opt->is_changed = 1;
656 }
657 if (srrptr <= srrspace) {
658 opt->srr_is_hit = 1;
659 opt->nexthop = nexthop;
660 opt->is_changed = 1;
661 }
662 return 0;
663 }
664 EXPORT_SYMBOL(ip_options_rcv_srr);
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