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