1 /* $KAME: ip6opt.c,v 1.13 2003/06/06 10:08:20 suz Exp $ */
2
3 /*-
4 * SPDX-License-Identifier: BSD-3-Clause
5 *
6 * Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
7 * All rights reserved.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 * 1. Redistributions of source code must retain the above copyright
13 * notice, this list of conditions and the following disclaimer.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 * notice, this list of conditions and the following disclaimer in the
16 * documentation and/or other materials provided with the distribution.
17 * 3. Neither the name of the project nor the names of its contributors
18 * may be used to endorse or promote products derived from this software
19 * without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 */
33
34 #include <sys/cdefs.h>
35 __FBSDID("$FreeBSD$");
36
37 #include <sys/param.h>
38 #include <sys/socket.h>
39
40 #include <netinet/in.h>
41 #include <netinet/ip6.h>
42
43 #include <string.h>
44 #include <stdio.h>
45
46 static int ip6optlen(u_int8_t *opt, u_int8_t *lim);
47 static void inet6_insert_padopt(u_char *p, int len);
48
49 #ifndef IPV6_2292HOPOPTS
50 #define IPV6_2292HOPOPTS 22
51 #endif
52 #ifndef IPV6_2292DSTOPTS
53 #define IPV6_2292DSTOPTS 23
54 #endif
55
56 #define is_ipv6_hopopts(x) \
57 ((x) == IPV6_HOPOPTS || (x) == IPV6_2292HOPOPTS)
58 #define is_ipv6_dstopts(x) \
59 ((x) == IPV6_DSTOPTS || (x) == IPV6_2292DSTOPTS)
60
61 /*
62 * This function returns the number of bytes required to hold an option
63 * when it is stored as ancillary data, including the cmsghdr structure
64 * at the beginning, and any padding at the end (to make its size a
65 * multiple of 8 bytes). The argument is the size of the structure
66 * defining the option, which must include any pad bytes at the
67 * beginning (the value y in the alignment term "xn + y"), the type
68 * byte, the length byte, and the option data.
69 */
70 int
inet6_option_space(int nbytes)71 inet6_option_space(int nbytes)
72 {
73 nbytes += 2; /* we need space for nxt-hdr and length fields */
74 return(CMSG_SPACE((nbytes + 7) & ~7));
75 }
76
77 /*
78 * This function is called once per ancillary data object that will
79 * contain either Hop-by-Hop or Destination options. It returns 0 on
80 * success or -1 on an error.
81 */
82 int
inet6_option_init(void * bp,struct cmsghdr ** cmsgp,int type)83 inet6_option_init(void *bp, struct cmsghdr **cmsgp, int type)
84 {
85 struct cmsghdr *ch = (struct cmsghdr *)bp;
86
87 /* argument validation */
88 if (!is_ipv6_hopopts(type) && !is_ipv6_dstopts(type))
89 return(-1);
90
91 ch->cmsg_level = IPPROTO_IPV6;
92 ch->cmsg_type = type;
93 ch->cmsg_len = CMSG_LEN(0);
94
95 *cmsgp = ch;
96 return(0);
97 }
98
99 /*
100 * This function appends a Hop-by-Hop option or a Destination option
101 * into an ancillary data object that has been initialized by
102 * inet6_option_init(). This function returns 0 if it succeeds or -1 on
103 * an error.
104 * multx is the value x in the alignment term "xn + y" described
105 * earlier. It must have a value of 1, 2, 4, or 8.
106 * plusy is the value y in the alignment term "xn + y" described
107 * earlier. It must have a value between 0 and 7, inclusive.
108 */
109 int
inet6_option_append(struct cmsghdr * cmsg,const u_int8_t * typep,int multx,int plusy)110 inet6_option_append(struct cmsghdr *cmsg, const u_int8_t *typep, int multx,
111 int plusy)
112 {
113 int padlen, optlen, off;
114 u_char *bp = (u_char *)cmsg + cmsg->cmsg_len;
115 struct ip6_ext *eh = (struct ip6_ext *)CMSG_DATA(cmsg);
116
117 /* argument validation */
118 if (multx != 1 && multx != 2 && multx != 4 && multx != 8)
119 return(-1);
120 if (plusy < 0 || plusy > 7)
121 return(-1);
122
123 /*
124 * If this is the first option, allocate space for the
125 * first 2 bytes(for next header and length fields) of
126 * the option header.
127 */
128 if (bp == (u_char *)eh) {
129 bp += 2;
130 cmsg->cmsg_len += 2;
131 }
132
133 /* calculate pad length before the option. */
134 off = bp - (u_char *)eh;
135 padlen = roundup2(off % multx, multx) - (off % multx);
136 padlen += plusy;
137 padlen %= multx; /* keep the pad as short as possible */
138 /* insert padding */
139 inet6_insert_padopt(bp, padlen);
140 cmsg->cmsg_len += padlen;
141 bp += padlen;
142
143 /* copy the option */
144 if (typep[0] == IP6OPT_PAD1)
145 optlen = 1;
146 else
147 optlen = typep[1] + 2;
148 memcpy(bp, typep, optlen);
149 bp += optlen;
150 cmsg->cmsg_len += optlen;
151
152 /* calculate pad length after the option and insert the padding */
153 off = bp - (u_char *)eh;
154 padlen = ((off + 7) & ~7) - off;
155 inet6_insert_padopt(bp, padlen);
156 bp += padlen;
157 cmsg->cmsg_len += padlen;
158
159 /* update the length field of the ip6 option header */
160 eh->ip6e_len = ((bp - (u_char *)eh) >> 3) - 1;
161
162 return(0);
163 }
164
165 /*
166 * This function appends a Hop-by-Hop option or a Destination option
167 * into an ancillary data object that has been initialized by
168 * inet6_option_init(). This function returns a pointer to the 8-bit
169 * option type field that starts the option on success, or NULL on an
170 * error.
171 * The difference between this function and inet6_option_append() is
172 * that the latter copies the contents of a previously built option into
173 * the ancillary data object while the current function returns a
174 * pointer to the space in the data object where the option's TLV must
175 * then be built by the caller.
176 *
177 */
178 u_int8_t *
inet6_option_alloc(struct cmsghdr * cmsg,int datalen,int multx,int plusy)179 inet6_option_alloc(struct cmsghdr *cmsg, int datalen, int multx, int plusy)
180 {
181 int padlen, off;
182 u_int8_t *bp = (u_char *)cmsg + cmsg->cmsg_len;
183 u_int8_t *retval;
184 struct ip6_ext *eh = (struct ip6_ext *)CMSG_DATA(cmsg);
185
186 /* argument validation */
187 if (multx != 1 && multx != 2 && multx != 4 && multx != 8)
188 return(NULL);
189 if (plusy < 0 || plusy > 7)
190 return(NULL);
191
192 /*
193 * If this is the first option, allocate space for the
194 * first 2 bytes(for next header and length fields) of
195 * the option header.
196 */
197 if (bp == (u_char *)eh) {
198 bp += 2;
199 cmsg->cmsg_len += 2;
200 }
201
202 /* calculate pad length before the option. */
203 off = bp - (u_char *)eh;
204 padlen = roundup2(off % multx, multx) - (off % multx);
205 padlen += plusy;
206 padlen %= multx; /* keep the pad as short as possible */
207 /* insert padding */
208 inet6_insert_padopt(bp, padlen);
209 cmsg->cmsg_len += padlen;
210 bp += padlen;
211
212 /* keep space to store specified length of data */
213 retval = bp;
214 bp += datalen;
215 cmsg->cmsg_len += datalen;
216
217 /* calculate pad length after the option and insert the padding */
218 off = bp - (u_char *)eh;
219 padlen = ((off + 7) & ~7) - off;
220 inet6_insert_padopt(bp, padlen);
221 bp += padlen;
222 cmsg->cmsg_len += padlen;
223
224 /* update the length field of the ip6 option header */
225 eh->ip6e_len = ((bp - (u_char *)eh) >> 3) - 1;
226
227 return(retval);
228 }
229
230 /*
231 * This function processes the next Hop-by-Hop option or Destination
232 * option in an ancillary data object. If another option remains to be
233 * processed, the return value of the function is 0 and *tptrp points to
234 * the 8-bit option type field (which is followed by the 8-bit option
235 * data length, followed by the option data). If no more options remain
236 * to be processed, the return value is -1 and *tptrp is NULL. If an
237 * error occurs, the return value is -1 and *tptrp is not NULL.
238 * (RFC 2292, 6.3.5)
239 */
240 int
inet6_option_next(const struct cmsghdr * cmsg,u_int8_t ** tptrp)241 inet6_option_next(const struct cmsghdr *cmsg, u_int8_t **tptrp)
242 {
243 struct ip6_ext *ip6e;
244 int hdrlen, optlen;
245 u_int8_t *lim;
246
247 if (cmsg->cmsg_level != IPPROTO_IPV6 ||
248 (!is_ipv6_hopopts(cmsg->cmsg_type) &&
249 !is_ipv6_dstopts(cmsg->cmsg_type)))
250 return(-1);
251
252 /* message length validation */
253 if (cmsg->cmsg_len < CMSG_SPACE(sizeof(struct ip6_ext)))
254 return(-1);
255 ip6e = (struct ip6_ext *)CMSG_DATA(cmsg);
256 hdrlen = (ip6e->ip6e_len + 1) << 3;
257 if (cmsg->cmsg_len < CMSG_SPACE(hdrlen))
258 return(-1);
259
260 /*
261 * If the caller does not specify the starting point,
262 * simply return the 1st option.
263 * Otherwise, search the option list for the next option.
264 */
265 lim = (u_int8_t *)ip6e + hdrlen;
266 if (*tptrp == NULL)
267 *tptrp = (u_int8_t *)(ip6e + 1);
268 else {
269 if ((optlen = ip6optlen(*tptrp, lim)) == 0)
270 return(-1);
271
272 *tptrp = *tptrp + optlen;
273 }
274 if (*tptrp >= lim) { /* there is no option */
275 *tptrp = NULL;
276 return(-1);
277 }
278 /*
279 * Finally, checks if the next option is safely stored in the
280 * cmsg data.
281 */
282 if (ip6optlen(*tptrp, lim) == 0)
283 return(-1);
284 else
285 return(0);
286 }
287
288 /*
289 * This function is similar to the inet6_option_next() function,
290 * except this function lets the caller specify the option type to be
291 * searched for, instead of always returning the next option in the
292 * ancillary data object.
293 * Note: RFC 2292 says the type of tptrp is u_int8_t *, but we think
294 * it's a typo. The variable should be type of u_int8_t **.
295 */
296 int
inet6_option_find(const struct cmsghdr * cmsg,u_int8_t ** tptrp,int type)297 inet6_option_find(const struct cmsghdr *cmsg, u_int8_t **tptrp, int type)
298 {
299 struct ip6_ext *ip6e;
300 int hdrlen, optlen;
301 u_int8_t *optp, *lim;
302
303 if (cmsg->cmsg_level != IPPROTO_IPV6 ||
304 (!is_ipv6_hopopts(cmsg->cmsg_type) &&
305 !is_ipv6_dstopts(cmsg->cmsg_type)))
306 return(-1);
307
308 /* message length validation */
309 if (cmsg->cmsg_len < CMSG_SPACE(sizeof(struct ip6_ext)))
310 return(-1);
311 ip6e = (struct ip6_ext *)CMSG_DATA(cmsg);
312 hdrlen = (ip6e->ip6e_len + 1) << 3;
313 if (cmsg->cmsg_len < CMSG_SPACE(hdrlen))
314 return(-1);
315
316 /*
317 * If the caller does not specify the starting point,
318 * search from the beginning of the option list.
319 * Otherwise, search from *the next option* of the specified point.
320 */
321 lim = (u_int8_t *)ip6e + hdrlen;
322 if (*tptrp == NULL)
323 *tptrp = (u_int8_t *)(ip6e + 1);
324 else {
325 if ((optlen = ip6optlen(*tptrp, lim)) == 0)
326 return(-1);
327
328 *tptrp = *tptrp + optlen;
329 }
330 for (optp = *tptrp; optp < lim; optp += optlen) {
331 if (*optp == type) {
332 *tptrp = optp;
333 return(0);
334 }
335 if ((optlen = ip6optlen(optp, lim)) == 0)
336 return(-1);
337 }
338
339 /* search failed */
340 *tptrp = NULL;
341 return(-1);
342 }
343
344 /*
345 * Calculate the length of a given IPv6 option. Also checks
346 * if the option is safely stored in user's buffer according to the
347 * calculated length and the limitation of the buffer.
348 */
349 static int
ip6optlen(u_int8_t * opt,u_int8_t * lim)350 ip6optlen(u_int8_t *opt, u_int8_t *lim)
351 {
352 int optlen;
353
354 if (*opt == IP6OPT_PAD1)
355 optlen = 1;
356 else {
357 /* is there enough space to store type and len? */
358 if (opt + 2 > lim)
359 return(0);
360 optlen = *(opt + 1) + 2;
361 }
362 if (opt + optlen <= lim)
363 return(optlen);
364
365 return(0);
366 }
367
368 static void
inet6_insert_padopt(u_char * p,int len)369 inet6_insert_padopt(u_char *p, int len)
370 {
371 switch(len) {
372 case 0:
373 return;
374 case 1:
375 p[0] = IP6OPT_PAD1;
376 return;
377 default:
378 p[0] = IP6OPT_PADN;
379 p[1] = len - 2;
380 memset(&p[2], 0, len - 2);
381 return;
382 }
383 }
384
385 /*
386 * The following functions are defined in RFC3542, which is a successor
387 * of RFC2292.
388 */
389
390 int
inet6_opt_init(void * extbuf,socklen_t extlen)391 inet6_opt_init(void *extbuf, socklen_t extlen)
392 {
393 struct ip6_ext *ext = (struct ip6_ext *)extbuf;
394
395 if (ext) {
396 if (extlen <= 0 || (extlen % 8))
397 return(-1);
398 ext->ip6e_len = (extlen >> 3) - 1;
399 }
400
401 return(2); /* sizeof the next and the length fields */
402 }
403
404 int
inet6_opt_append(void * extbuf,socklen_t extlen,int offset,u_int8_t type,socklen_t len,u_int8_t align,void ** databufp)405 inet6_opt_append(void *extbuf, socklen_t extlen, int offset, u_int8_t type,
406 socklen_t len, u_int8_t align, void **databufp)
407 {
408 int currentlen = offset, padlen = 0;
409
410 /*
411 * The option type must have a value from 2 to 255, inclusive.
412 * (0 and 1 are reserved for the Pad1 and PadN options, respectively.)
413 */
414 if (type < 2)
415 return(-1);
416
417 /*
418 * The option data length must have a value between 0 and 255,
419 * inclusive, and is the length of the option data that follows.
420 */
421 if (len > 255 || len < 0 )
422 return(-1);
423
424 /*
425 * The align parameter must have a value of 1, 2, 4, or 8.
426 * The align value can not exceed the value of len.
427 */
428 if (align != 1 && align != 2 && align != 4 && align != 8)
429 return(-1);
430 if (align > len)
431 return(-1);
432
433 /* Calculate the padding length. */
434 currentlen += 2 + len; /* 2 means "type + len" */
435 if (currentlen % align)
436 padlen = align - (currentlen % align);
437
438 /* The option must fit in the extension header buffer. */
439 currentlen += padlen;
440 if (extlen && /* XXX: right? */
441 currentlen > extlen)
442 return(-1);
443
444 if (extbuf) {
445 u_int8_t *optp = (u_int8_t *)extbuf + offset;
446
447 if (padlen == 1) {
448 /* insert a Pad1 option */
449 *optp = IP6OPT_PAD1;
450 optp++;
451 }
452 else if (padlen > 0) {
453 /* insert a PadN option for alignment */
454 *optp++ = IP6OPT_PADN;
455 *optp++ = padlen - 2;
456 memset(optp, 0, padlen - 2);
457 optp += (padlen - 2);
458 }
459
460 *optp++ = type;
461 *optp++ = len;
462
463 *databufp = optp;
464 }
465
466 return(currentlen);
467 }
468
469 int
inet6_opt_finish(void * extbuf,socklen_t extlen,int offset)470 inet6_opt_finish(void *extbuf, socklen_t extlen, int offset)
471 {
472 int updatelen = offset > 0 ? (1 + ((offset - 1) | 7)) : 0;
473
474 if (extbuf) {
475 u_int8_t *padp;
476 int padlen = updatelen - offset;
477
478 if (updatelen > extlen)
479 return(-1);
480
481 padp = (u_int8_t *)extbuf + offset;
482 if (padlen == 1)
483 *padp = IP6OPT_PAD1;
484 else if (padlen > 0) {
485 *padp++ = IP6OPT_PADN;
486 *padp++ = (padlen - 2);
487 memset(padp, 0, padlen - 2);
488 }
489 }
490
491 return(updatelen);
492 }
493
494 int
inet6_opt_set_val(void * databuf,int offset,void * val,socklen_t vallen)495 inet6_opt_set_val(void *databuf, int offset, void *val, socklen_t vallen)
496 {
497
498 memcpy((u_int8_t *)databuf + offset, val, vallen);
499 return(offset + vallen);
500 }
501
502 int
inet6_opt_next(void * extbuf,socklen_t extlen,int offset,u_int8_t * typep,socklen_t * lenp,void ** databufp)503 inet6_opt_next(void *extbuf, socklen_t extlen, int offset, u_int8_t *typep,
504 socklen_t *lenp, void **databufp)
505 {
506 u_int8_t *optp, *lim;
507 int optlen;
508
509 /* Validate extlen. XXX: is the variable really necessary?? */
510 if (extlen == 0 || (extlen % 8))
511 return(-1);
512 lim = (u_int8_t *)extbuf + extlen;
513
514 /*
515 * If this is the first time this function called for this options
516 * header, simply return the 1st option.
517 * Otherwise, search the option list for the next option.
518 */
519 if (offset == 0) {
520 optp = (u_int8_t *)((struct ip6_hbh *)extbuf + 1);
521 }
522 else
523 optp = (u_int8_t *)extbuf + offset;
524
525 /* Find the next option skipping any padding options. */
526 while(optp < lim) {
527 switch(*optp) {
528 case IP6OPT_PAD1:
529 optp++;
530 break;
531 case IP6OPT_PADN:
532 if ((optlen = ip6optlen(optp, lim)) == 0)
533 goto optend;
534 optp += optlen;
535 break;
536 default: /* found */
537 if ((optlen = ip6optlen(optp, lim)) == 0)
538 goto optend;
539 *typep = *optp;
540 *lenp = optlen - 2;
541 *databufp = optp + 2;
542 return(optp + optlen - (u_int8_t *)extbuf);
543 }
544 }
545
546 optend:
547 *databufp = NULL; /* for safety */
548 return(-1);
549 }
550
551 int
inet6_opt_find(void * extbuf,socklen_t extlen,int offset,u_int8_t type,socklen_t * lenp,void ** databufp)552 inet6_opt_find(void *extbuf, socklen_t extlen, int offset, u_int8_t type,
553 socklen_t *lenp, void **databufp)
554 {
555 u_int8_t *optp, *lim;
556 int optlen;
557
558 /* Validate extlen. XXX: is the variable really necessary?? */
559 if (extlen == 0 || (extlen % 8))
560 return(-1);
561 lim = (u_int8_t *)extbuf + extlen;
562
563 /*
564 * If this is the first time this function called for this options
565 * header, simply return the 1st option.
566 * Otherwise, search the option list for the next option.
567 */
568 if (offset == 0) {
569 optp = (u_int8_t *)((struct ip6_hbh *)extbuf + 1);
570 }
571 else
572 optp = (u_int8_t *)extbuf + offset;
573
574 /* Find the specified option */
575 while(optp < lim) {
576 if ((optlen = ip6optlen(optp, lim)) == 0)
577 goto optend;
578
579 if (*optp == type) { /* found */
580 *lenp = optlen - 2;
581 *databufp = optp + 2;
582 return(optp + optlen - (u_int8_t *)extbuf);
583 }
584
585 optp += optlen;
586 }
587
588 optend:
589 *databufp = NULL; /* for safety */
590 return(-1);
591 }
592
593 int
inet6_opt_get_val(void * databuf,int offset,void * val,socklen_t vallen)594 inet6_opt_get_val(void *databuf, int offset, void *val, socklen_t vallen)
595 {
596
597 /* we can't assume alignment here */
598 memcpy(val, (u_int8_t *)databuf + offset, vallen);
599
600 return(offset + vallen);
601 }
602