[PATCH] capable/capability.h (net/)
[linux-2.6.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  * Version:     $Id: ip_options.c,v 1.21 2001/09/01 00:31:50 davem Exp $
9  *
10  * Authors:     A.N.Kuznetsov
11  *              
12  */
13
14 #include <linux/capability.h>
15 #include <linux/module.h>
16 #include <linux/types.h>
17 #include <asm/uaccess.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
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                             u32 daddr, struct rtable *rt, int is_frag) 
41 {
42         unsigned char * iph = skb->nh.raw;
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         opt->is_data = 0;
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, rt);
55                 if (opt->ts_needaddr)
56                         ip_rt_get_source(iph+opt->ts+iph[opt->ts+2]-9, rt);
57                 if (opt->ts_needtime) {
58                         struct timeval tv;
59                         __u32 midtime;
60                         do_gettimeofday(&tv);
61                         midtime = htonl((tv.tv_sec % 86400) * 1000 + tv.tv_usec / 1000);
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         struct ip_options *sopt;
90         unsigned char *sptr, *dptr;
91         int soffset, doffset;
92         int     optlen;
93         u32     daddr;
94
95         memset(dopt, 0, sizeof(struct ip_options));
96
97         dopt->is_data = 1;
98
99         sopt = &(IPCB(skb)->opt);
100
101         if (sopt->optlen == 0) {
102                 dopt->optlen = 0;
103                 return 0;
104         }
105
106         sptr = skb->nh.raw;
107         dptr = dopt->__data;
108
109         if (skb->dst)
110                 daddr = ((struct rtable*)skb->dst)->rt_spec_dst;
111         else
112                 daddr = skb->nh.iph->daddr;
113
114         if (sopt->rr) {
115                 optlen  = sptr[sopt->rr+1];
116                 soffset = sptr[sopt->rr+2];
117                 dopt->rr = dopt->optlen + sizeof(struct iphdr);
118                 memcpy(dptr, sptr+sopt->rr, optlen);
119                 if (sopt->rr_needaddr && soffset <= optlen) {
120                         if (soffset + 3 > optlen)
121                                 return -EINVAL;
122                         dptr[2] = soffset + 4;
123                         dopt->rr_needaddr = 1;
124                 }
125                 dptr += optlen;
126                 dopt->optlen += optlen;
127         }
128         if (sopt->ts) {
129                 optlen = sptr[sopt->ts+1];
130                 soffset = sptr[sopt->ts+2];
131                 dopt->ts = dopt->optlen + sizeof(struct iphdr);
132                 memcpy(dptr, sptr+sopt->ts, optlen);
133                 if (soffset <= optlen) {
134                         if (sopt->ts_needaddr) {
135                                 if (soffset + 3 > optlen)
136                                         return -EINVAL;
137                                 dopt->ts_needaddr = 1;
138                                 soffset += 4;
139                         }
140                         if (sopt->ts_needtime) {
141                                 if (soffset + 3 > optlen)
142                                         return -EINVAL;
143                                 if ((dptr[3]&0xF) != IPOPT_TS_PRESPEC) {
144                                         dopt->ts_needtime = 1;
145                                         soffset += 4;
146                                 } else {
147                                         dopt->ts_needtime = 0;
148
149                                         if (soffset + 8 <= optlen) {
150                                                 __u32 addr;
151
152                                                 memcpy(&addr, sptr+soffset-1, 4);
153                                                 if (inet_addr_type(addr) != RTN_LOCAL) {
154                                                         dopt->ts_needtime = 1;
155                                                         soffset += 8;
156                                                 }
157                                         }
158                                 }
159                         }
160                         dptr[2] = soffset;
161                 }
162                 dptr += optlen;
163                 dopt->optlen += optlen;
164         }
165         if (sopt->srr) {
166                 unsigned char * start = sptr+sopt->srr;
167                 u32 faddr;
168
169                 optlen  = start[1];
170                 soffset = start[2];
171                 doffset = 0;
172                 if (soffset > optlen)
173                         soffset = optlen + 1;
174                 soffset -= 4;
175                 if (soffset > 3) {
176                         memcpy(&faddr, &start[soffset-1], 4);
177                         for (soffset-=4, doffset=4; soffset > 3; soffset-=4, doffset+=4)
178                                 memcpy(&dptr[doffset-1], &start[soffset-1], 4);
179                         /*
180                          * RFC1812 requires to fix illegal source routes.
181                          */
182                         if (memcmp(&skb->nh.iph->saddr, &start[soffset+3], 4) == 0)
183                                 doffset -= 4;
184                 }
185                 if (doffset > 3) {
186                         memcpy(&start[doffset-1], &daddr, 4);
187                         dopt->faddr = faddr;
188                         dptr[0] = start[0];
189                         dptr[1] = doffset+3;
190                         dptr[2] = 4;
191                         dptr += doffset+3;
192                         dopt->srr = dopt->optlen + sizeof(struct iphdr);
193                         dopt->optlen += doffset+3;
194                         dopt->is_strictroute = sopt->is_strictroute;
195                 }
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->nh.raw;
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         return;
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 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 = skb ? (struct rtable*)skb->dst : NULL;
256
257         if (!opt) {
258                 opt = &(IPCB(skb)->opt);
259                 memset(opt, 0, sizeof(struct ip_options));
260                 iph = skb->nh.raw;
261                 opt->optlen = ((struct iphdr *)iph)->ihl*4 - sizeof(struct iphdr);
262                 optptr = iph + sizeof(struct iphdr);
263                 opt->is_data = 0;
264         } else {
265                 optptr = opt->is_data ? opt->__data : (unsigned char*)&(skb->nh.iph[1]);
266                 iph = optptr - sizeof(struct iphdr);
267         }
268
269         for (l = opt->optlen; l > 0; ) {
270                 switch (*optptr) {
271                       case IPOPT_END:
272                         for (optptr++, l--; l>0; optptr++, l--) {
273                                 if (*optptr != IPOPT_END) {
274                                         *optptr = IPOPT_END;
275                                         opt->is_changed = 1;
276                                 }
277                         }
278                         goto eol;
279                       case IPOPT_NOOP:
280                         l--;
281                         optptr++;
282                         continue;
283                 }
284                 optlen = optptr[1];
285                 if (optlen<2 || optlen>l) {
286                         pp_ptr = optptr;
287                         goto error;
288                 }
289                 switch (*optptr) {
290                       case IPOPT_SSRR:
291                       case IPOPT_LSRR:
292                         if (optlen < 3) {
293                                 pp_ptr = optptr + 1;
294                                 goto error;
295                         }
296                         if (optptr[2] < 4) {
297                                 pp_ptr = optptr + 2;
298                                 goto error;
299                         }
300                         /* NB: cf RFC-1812 5.2.4.1 */
301                         if (opt->srr) {
302                                 pp_ptr = optptr;
303                                 goto error;
304                         }
305                         if (!skb) {
306                                 if (optptr[2] != 4 || optlen < 7 || ((optlen-3) & 3)) {
307                                         pp_ptr = optptr + 1;
308                                         goto error;
309                                 }
310                                 memcpy(&opt->faddr, &optptr[3], 4);
311                                 if (optlen > 7)
312                                         memmove(&optptr[3], &optptr[7], optlen-7);
313                         }
314                         opt->is_strictroute = (optptr[0] == IPOPT_SSRR);
315                         opt->srr = optptr - iph;
316                         break;
317                       case IPOPT_RR:
318                         if (opt->rr) {
319                                 pp_ptr = optptr;
320                                 goto error;
321                         }
322                         if (optlen < 3) {
323                                 pp_ptr = optptr + 1;
324                                 goto error;
325                         }
326                         if (optptr[2] < 4) {
327                                 pp_ptr = optptr + 2;
328                                 goto error;
329                         }
330                         if (optptr[2] <= optlen) {
331                                 if (optptr[2]+3 > optlen) {
332                                         pp_ptr = optptr + 2;
333                                         goto error;
334                                 }
335                                 if (skb) {
336                                         memcpy(&optptr[optptr[2]-1], &rt->rt_spec_dst, 4);
337                                         opt->is_changed = 1;
338                                 }
339                                 optptr[2] += 4;
340                                 opt->rr_needaddr = 1;
341                         }
342                         opt->rr = optptr - iph;
343                         break;
344                       case IPOPT_TIMESTAMP:
345                         if (opt->ts) {
346                                 pp_ptr = optptr;
347                                 goto error;
348                         }
349                         if (optlen < 4) {
350                                 pp_ptr = optptr + 1;
351                                 goto error;
352                         }
353                         if (optptr[2] < 5) {
354                                 pp_ptr = optptr + 2;
355                                 goto error;
356                         }
357                         if (optptr[2] <= optlen) {
358                                 __u32 * timeptr = NULL;
359                                 if (optptr[2]+3 > optptr[1]) {
360                                         pp_ptr = optptr + 2;
361                                         goto error;
362                                 }
363                                 switch (optptr[3]&0xF) {
364                                       case IPOPT_TS_TSONLY:
365                                         opt->ts = optptr - iph;
366                                         if (skb) 
367                                                 timeptr = (__u32*)&optptr[optptr[2]-1];
368                                         opt->ts_needtime = 1;
369                                         optptr[2] += 4;
370                                         break;
371                                       case IPOPT_TS_TSANDADDR:
372                                         if (optptr[2]+7 > optptr[1]) {
373                                                 pp_ptr = optptr + 2;
374                                                 goto error;
375                                         }
376                                         opt->ts = optptr - iph;
377                                         if (skb) {
378                                                 memcpy(&optptr[optptr[2]-1], &rt->rt_spec_dst, 4);
379                                                 timeptr = (__u32*)&optptr[optptr[2]+3];
380                                         }
381                                         opt->ts_needaddr = 1;
382                                         opt->ts_needtime = 1;
383                                         optptr[2] += 8;
384                                         break;
385                                       case IPOPT_TS_PRESPEC:
386                                         if (optptr[2]+7 > optptr[1]) {
387                                                 pp_ptr = optptr + 2;
388                                                 goto error;
389                                         }
390                                         opt->ts = optptr - iph;
391                                         {
392                                                 u32 addr;
393                                                 memcpy(&addr, &optptr[optptr[2]-1], 4);
394                                                 if (inet_addr_type(addr) == RTN_UNICAST)
395                                                         break;
396                                                 if (skb)
397                                                         timeptr = (__u32*)&optptr[optptr[2]+3];
398                                         }
399                                         opt->ts_needtime = 1;
400                                         optptr[2] += 8;
401                                         break;
402                                       default:
403                                         if (!skb && !capable(CAP_NET_RAW)) {
404                                                 pp_ptr = optptr + 3;
405                                                 goto error;
406                                         }
407                                         break;
408                                 }
409                                 if (timeptr) {
410                                         struct timeval tv;
411                                         __u32  midtime;
412                                         do_gettimeofday(&tv);
413                                         midtime = htonl((tv.tv_sec % 86400) * 1000 + tv.tv_usec / 1000);
414                                         memcpy(timeptr, &midtime, sizeof(__u32));
415                                         opt->is_changed = 1;
416                                 }
417                         } else {
418                                 unsigned overflow = optptr[3]>>4;
419                                 if (overflow == 15) {
420                                         pp_ptr = optptr + 3;
421                                         goto error;
422                                 }
423                                 opt->ts = optptr - iph;
424                                 if (skb) {
425                                         optptr[3] = (optptr[3]&0xF)|((overflow+1)<<4);
426                                         opt->is_changed = 1;
427                                 }
428                         }
429                         break;
430                       case IPOPT_RA:
431                         if (optlen < 4) {
432                                 pp_ptr = optptr + 1;
433                                 goto error;
434                         }
435                         if (optptr[2] == 0 && optptr[3] == 0)
436                                 opt->router_alert = optptr - iph;
437                         break;
438                       case IPOPT_SEC:
439                       case IPOPT_SID:
440                       default:
441                         if (!skb && !capable(CAP_NET_RAW)) {
442                                 pp_ptr = optptr;
443                                 goto error;
444                         }
445                         break;
446                 }
447                 l -= optlen;
448                 optptr += optlen;
449         }
450
451 eol:
452         if (!pp_ptr)
453                 return 0;
454
455 error:
456         if (skb) {
457                 icmp_send(skb, ICMP_PARAMETERPROB, 0, htonl((pp_ptr-iph)<<24));
458         }
459         return -EINVAL;
460 }
461
462
463 /*
464  *      Undo all the changes done by ip_options_compile().
465  */
466
467 void ip_options_undo(struct ip_options * opt)
468 {
469         if (opt->srr) {
470                 unsigned  char * optptr = opt->__data+opt->srr-sizeof(struct  iphdr);
471                 memmove(optptr+7, optptr+3, optptr[1]-7);
472                 memcpy(optptr+3, &opt->faddr, 4);
473         }
474         if (opt->rr_needaddr) {
475                 unsigned  char * optptr = opt->__data+opt->rr-sizeof(struct  iphdr);
476                 optptr[2] -= 4;
477                 memset(&optptr[optptr[2]-1], 0, 4);
478         }
479         if (opt->ts) {
480                 unsigned  char * optptr = opt->__data+opt->ts-sizeof(struct  iphdr);
481                 if (opt->ts_needtime) {
482                         optptr[2] -= 4;
483                         memset(&optptr[optptr[2]-1], 0, 4);
484                         if ((optptr[3]&0xF) == IPOPT_TS_PRESPEC)
485                                 optptr[2] -= 4;
486                 }
487                 if (opt->ts_needaddr) {
488                         optptr[2] -= 4;
489                         memset(&optptr[optptr[2]-1], 0, 4);
490                 }
491         }
492 }
493
494 static struct ip_options *ip_options_get_alloc(const int optlen)
495 {
496         struct ip_options *opt = kmalloc(sizeof(*opt) + ((optlen + 3) & ~3),
497                                          GFP_KERNEL);
498         if (opt)
499                 memset(opt, 0, sizeof(*opt));
500         return opt;
501 }
502
503 static int ip_options_get_finish(struct ip_options **optp,
504                                  struct ip_options *opt, int optlen)
505 {
506         while (optlen & 3)
507                 opt->__data[optlen++] = IPOPT_END;
508         opt->optlen = optlen;
509         opt->is_data = 1;
510         opt->is_setbyuser = 1;
511         if (optlen && ip_options_compile(opt, NULL)) {
512                 kfree(opt);
513                 return -EINVAL;
514         }
515         kfree(*optp);
516         *optp = opt;
517         return 0;
518 }
519
520 int ip_options_get_from_user(struct ip_options **optp, unsigned char __user *data, int optlen)
521 {
522         struct ip_options *opt = ip_options_get_alloc(optlen);
523
524         if (!opt)
525                 return -ENOMEM;
526         if (optlen && copy_from_user(opt->__data, data, optlen)) {
527                 kfree(opt);
528                 return -EFAULT;
529         }
530         return ip_options_get_finish(optp, opt, optlen);
531 }
532
533 int ip_options_get(struct ip_options **optp, unsigned char *data, int optlen)
534 {
535         struct ip_options *opt = ip_options_get_alloc(optlen);
536
537         if (!opt)
538                 return -ENOMEM;
539         if (optlen)
540                 memcpy(opt->__data, data, optlen);
541         return ip_options_get_finish(optp, opt, optlen);
542 }
543
544 void ip_forward_options(struct sk_buff *skb)
545 {
546         struct   ip_options * opt       = &(IPCB(skb)->opt);
547         unsigned char * optptr;
548         struct rtable *rt = (struct rtable*)skb->dst;
549         unsigned char *raw = skb->nh.raw;
550
551         if (opt->rr_needaddr) {
552                 optptr = (unsigned char *)raw + opt->rr;
553                 ip_rt_get_source(&optptr[optptr[2]-5], rt);
554                 opt->is_changed = 1;
555         }
556         if (opt->srr_is_hit) {
557                 int srrptr, srrspace;
558
559                 optptr = raw + opt->srr;
560
561                 for ( srrptr=optptr[2], srrspace = optptr[1];
562                      srrptr <= srrspace;
563                      srrptr += 4
564                      ) {
565                         if (srrptr + 3 > srrspace)
566                                 break;
567                         if (memcmp(&rt->rt_dst, &optptr[srrptr-1], 4) == 0)
568                                 break;
569                 }
570                 if (srrptr + 3 <= srrspace) {
571                         opt->is_changed = 1;
572                         ip_rt_get_source(&optptr[srrptr-1], rt);
573                         skb->nh.iph->daddr = rt->rt_dst;
574                         optptr[2] = srrptr+4;
575                 } else if (net_ratelimit())
576                         printk(KERN_CRIT "ip_forward(): Argh! Destination lost!\n");
577                 if (opt->ts_needaddr) {
578                         optptr = raw + opt->ts;
579                         ip_rt_get_source(&optptr[optptr[2]-9], rt);
580                         opt->is_changed = 1;
581                 }
582         }
583         if (opt->is_changed) {
584                 opt->is_changed = 0;
585                 ip_send_check(skb->nh.iph);
586         }
587 }
588
589 int ip_options_rcv_srr(struct sk_buff *skb)
590 {
591         struct ip_options *opt = &(IPCB(skb)->opt);
592         int srrspace, srrptr;
593         u32 nexthop;
594         struct iphdr *iph = skb->nh.iph;
595         unsigned char * optptr = skb->nh.raw + opt->srr;
596         struct rtable *rt = (struct rtable*)skb->dst;
597         struct rtable *rt2;
598         int err;
599
600         if (!opt->srr)
601                 return 0;
602
603         if (skb->pkt_type != PACKET_HOST)
604                 return -EINVAL;
605         if (rt->rt_type == RTN_UNICAST) {
606                 if (!opt->is_strictroute)
607                         return 0;
608                 icmp_send(skb, ICMP_PARAMETERPROB, 0, htonl(16<<24));
609                 return -EINVAL;
610         }
611         if (rt->rt_type != RTN_LOCAL)
612                 return -EINVAL;
613
614         for (srrptr=optptr[2], srrspace = optptr[1]; srrptr <= srrspace; srrptr += 4) {
615                 if (srrptr + 3 > srrspace) {
616                         icmp_send(skb, ICMP_PARAMETERPROB, 0, htonl((opt->srr+2)<<24));
617                         return -EINVAL;
618                 }
619                 memcpy(&nexthop, &optptr[srrptr-1], 4);
620
621                 rt = (struct rtable*)skb->dst;
622                 skb->dst = NULL;
623                 err = ip_route_input(skb, nexthop, iph->saddr, iph->tos, skb->dev);
624                 rt2 = (struct rtable*)skb->dst;
625                 if (err || (rt2->rt_type != RTN_UNICAST && rt2->rt_type != RTN_LOCAL)) {
626                         ip_rt_put(rt2);
627                         skb->dst = &rt->u.dst;
628                         return -EINVAL;
629                 }
630                 ip_rt_put(rt);
631                 if (rt2->rt_type != RTN_LOCAL)
632                         break;
633                 /* Superfast 8) loopback forward */
634                 memcpy(&iph->daddr, &optptr[srrptr-1], 4);
635                 opt->is_changed = 1;
636         }
637         if (srrptr <= srrspace) {
638                 opt->srr_is_hit = 1;
639                 opt->is_changed = 1;
640         }
641         return 0;
642 }