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1 office 1 /*-
2 * Copyright (c) 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997
3 * The Regents of the University of California. All rights reserved.
4 *
5 * This code is derived from the Stanford/CMU enet packet filter,
6 * (net/enet.c) distributed as part of 4.3BSD, and code contributed
7 * to Berkeley by Steven McCanne and Van Jacobson both of Lawrence
8 * Berkeley Laboratory.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 * 3. All advertising materials mentioning features or use of this software
19 * must display the following acknowledgement:
20 * This product includes software developed by the University of
21 * California, Berkeley and its contributors.
22 * 4. Neither the name of the University nor the names of its contributors
23 * may be used to endorse or promote products derived from this software
24 * without specific prior written permission.
25 *
26 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
29 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
36 * SUCH DAMAGE.
37 *
38 * @(#)bpf.c 7.5 (Berkeley) 7/15/91
39 */
40  
41 #ifdef HAVE_CONFIG_H
42 #include "config.h"
43 #endif
44  
45 #ifdef WIN32
46  
47 #include <pcap-stdinc.h>
48  
49 #else /* WIN32 */
50  
51 #if HAVE_INTTYPES_H
52 #include <inttypes.h>
53 #elif HAVE_STDINT_H
54 #include <stdint.h>
55 #endif
56 #ifdef HAVE_SYS_BITYPES_H
57 #include <sys/bitypes.h>
58 #endif
59  
60 #include <sys/param.h>
61 #include <sys/types.h>
62 #include <sys/time.h>
63  
64 #define SOLARIS (defined(sun) && (defined(__SVR4) || defined(__svr4__)))
65 #if defined(__hpux) || SOLARIS
66 # include <sys/sysmacros.h>
67 # include <sys/stream.h>
68 # define mbuf msgb
69 # define m_next b_cont
70 # define MLEN(m) ((m)->b_wptr - (m)->b_rptr)
71 # define mtod(m,t) ((t)(m)->b_rptr)
72 #else /* defined(__hpux) || SOLARIS */
73 # define MLEN(m) ((m)->m_len)
74 #endif /* defined(__hpux) || SOLARIS */
75  
76 #endif /* WIN32 */
77  
78 #include <pcap/bpf.h>
79  
80 #if !defined(KERNEL) && !defined(_KERNEL)
81 #include <stdlib.h>
82 #endif
83  
84 #define int32 bpf_int32
85 #define u_int32 bpf_u_int32
86  
87 #ifndef LBL_ALIGN
88 /*
89 * XXX - IA-64? If not, this probably won't work on Win64 IA-64
90 * systems, unless LBL_ALIGN is defined elsewhere for them.
91 * XXX - SuperH? If not, this probably won't work on WinCE SuperH
92 * systems, unless LBL_ALIGN is defined elsewhere for them.
93 */
94 #if defined(sparc) || defined(__sparc__) || defined(mips) || \
95 defined(ibm032) || defined(__alpha) || defined(__hpux) || \
96 defined(__arm__)
97 #define LBL_ALIGN
98 #endif
99 #endif
100  
101 #ifndef LBL_ALIGN
102 #ifndef WIN32
103 #include <netinet/in.h>
104 #endif
105  
106 #define EXTRACT_SHORT(p) ((u_short)ntohs(*(u_short *)p))
107 #define EXTRACT_LONG(p) (ntohl(*(u_int32 *)p))
108 #else
109 #define EXTRACT_SHORT(p)\
110 ((u_short)\
111 ((u_short)*((u_char *)p+0)<<8|\
112 (u_short)*((u_char *)p+1)<<0))
113 #define EXTRACT_LONG(p)\
114 ((u_int32)*((u_char *)p+0)<<24|\
115 (u_int32)*((u_char *)p+1)<<16|\
116 (u_int32)*((u_char *)p+2)<<8|\
117 (u_int32)*((u_char *)p+3)<<0)
118 #endif
119  
120 #if defined(KERNEL) || defined(_KERNEL)
121 # if !defined(__hpux) && !SOLARIS
122 #include <sys/mbuf.h>
123 # endif
124 #define MINDEX(len, _m, _k) \
125 { \
126 len = MLEN(m); \
127 while ((_k) >= len) { \
128 (_k) -= len; \
129 (_m) = (_m)->m_next; \
130 if ((_m) == 0) \
131 return 0; \
132 len = MLEN(m); \
133 } \
134 }
135  
136 static int
137 m_xword(m, k, err)
138 register struct mbuf *m;
139 register int k, *err;
140 {
141 register int len;
142 register u_char *cp, *np;
143 register struct mbuf *m0;
144  
145 MINDEX(len, m, k);
146 cp = mtod(m, u_char *) + k;
147 if (len - k >= 4) {
148 *err = 0;
149 return EXTRACT_LONG(cp);
150 }
151 m0 = m->m_next;
152 if (m0 == 0 || MLEN(m0) + len - k < 4)
153 goto bad;
154 *err = 0;
155 np = mtod(m0, u_char *);
156 switch (len - k) {
157  
158 case 1:
159 return (cp[0] << 24) | (np[0] << 16) | (np[1] << 8) | np[2];
160  
161 case 2:
162 return (cp[0] << 24) | (cp[1] << 16) | (np[0] << 8) | np[1];
163  
164 default:
165 return (cp[0] << 24) | (cp[1] << 16) | (cp[2] << 8) | np[0];
166 }
167 bad:
168 *err = 1;
169 return 0;
170 }
171  
172 static int
173 m_xhalf(m, k, err)
174 register struct mbuf *m;
175 register int k, *err;
176 {
177 register int len;
178 register u_char *cp;
179 register struct mbuf *m0;
180  
181 MINDEX(len, m, k);
182 cp = mtod(m, u_char *) + k;
183 if (len - k >= 2) {
184 *err = 0;
185 return EXTRACT_SHORT(cp);
186 }
187 m0 = m->m_next;
188 if (m0 == 0)
189 goto bad;
190 *err = 0;
191 return (cp[0] << 8) | mtod(m0, u_char *)[0];
192 bad:
193 *err = 1;
194 return 0;
195 }
196 #endif
197  
198 #ifdef __linux__
199 #include <linux/types.h>
200 #include <linux/if_packet.h>
201 #include <linux/filter.h>
202 #endif
203  
204 enum {
205 BPF_S_ANC_NONE,
206 BPF_S_ANC_VLAN_TAG,
207 BPF_S_ANC_VLAN_TAG_PRESENT,
208 };
209  
210 /*
211 * Execute the filter program starting at pc on the packet p
212 * wirelen is the length of the original packet
213 * buflen is the amount of data present
214 * aux_data is auxiliary data, currently used only when interpreting
215 * filters intended for the Linux kernel in cases where the kernel
216 * rejects the filter; it contains VLAN tag information
217 * For the kernel, p is assumed to be a pointer to an mbuf if buflen is 0,
218 * in all other cases, p is a pointer to a buffer and buflen is its size.
219 */
220 u_int
221 bpf_filter_with_aux_data(pc, p, wirelen, buflen, aux_data)
222 register const struct bpf_insn *pc;
223 register const u_char *p;
224 u_int wirelen;
225 register u_int buflen;
226 register const struct bpf_aux_data *aux_data;
227 {
228 register u_int32 A, X;
229 register bpf_u_int32 k;
230 u_int32 mem[BPF_MEMWORDS];
231 #if defined(KERNEL) || defined(_KERNEL)
232 struct mbuf *m, *n;
233 int merr, len;
234  
235 if (buflen == 0) {
236 m = (struct mbuf *)p;
237 p = mtod(m, u_char *);
238 buflen = MLEN(m);
239 } else
240 m = NULL;
241 #endif
242  
243 if (pc == 0)
244 /*
245 * No filter means accept all.
246 */
247 return (u_int)-1;
248 A = 0;
249 X = 0;
250 --pc;
251 while (1) {
252 ++pc;
253 switch (pc->code) {
254  
255 default:
256 #if defined(KERNEL) || defined(_KERNEL)
257 return 0;
258 #else
259 abort();
260 #endif
261 case BPF_RET|BPF_K:
262 return (u_int)pc->k;
263  
264 case BPF_RET|BPF_A:
265 return (u_int)A;
266  
267 case BPF_LD|BPF_W|BPF_ABS:
268 k = pc->k;
269 if (k > buflen || sizeof(int32_t) > buflen - k) {
270 #if defined(KERNEL) || defined(_KERNEL)
271 if (m == NULL)
272 return 0;
273 A = m_xword(m, k, &merr);
274 if (merr != 0)
275 return 0;
276 continue;
277 #else
278 return 0;
279 #endif
280 }
281 A = EXTRACT_LONG(&p[k]);
282 continue;
283  
284 case BPF_LD|BPF_H|BPF_ABS:
285 k = pc->k;
286 if (k > buflen || sizeof(int16_t) > buflen - k) {
287 #if defined(KERNEL) || defined(_KERNEL)
288 if (m == NULL)
289 return 0;
290 A = m_xhalf(m, k, &merr);
291 if (merr != 0)
292 return 0;
293 continue;
294 #else
295 return 0;
296 #endif
297 }
298 A = EXTRACT_SHORT(&p[k]);
299 continue;
300  
301 case BPF_LD|BPF_B|BPF_ABS:
302 {
303 #if defined(SKF_AD_VLAN_TAG) && defined(SKF_AD_VLAN_TAG_PRESENT)
304 int code = BPF_S_ANC_NONE;
305 #define ANCILLARY(CODE) case SKF_AD_OFF + SKF_AD_##CODE: \
306 code = BPF_S_ANC_##CODE; \
307 if (!aux_data) \
308 return 0; \
309 break;
310  
311 switch (pc->k) {
312 ANCILLARY(VLAN_TAG);
313 ANCILLARY(VLAN_TAG_PRESENT);
314 default :
315 #endif
316 k = pc->k;
317 if (k >= buflen) {
318 #if defined(KERNEL) || defined(_KERNEL)
319 if (m == NULL)
320 return 0;
321 n = m;
322 MINDEX(len, n, k);
323 A = mtod(n, u_char *)[k];
324 continue;
325 #else
326 return 0;
327 #endif
328 }
329 A = p[k];
330 #if defined(SKF_AD_VLAN_TAG) && defined(SKF_AD_VLAN_TAG_PRESENT)
331 }
332 switch (code) {
333 case BPF_S_ANC_VLAN_TAG:
334 if (aux_data)
335 A = aux_data->vlan_tag;
336 break;
337  
338 case BPF_S_ANC_VLAN_TAG_PRESENT:
339 if (aux_data)
340 A = aux_data->vlan_tag_present;
341 break;
342 }
343 #endif
344 continue;
345 }
346 case BPF_LD|BPF_W|BPF_LEN:
347 A = wirelen;
348 continue;
349  
350 case BPF_LDX|BPF_W|BPF_LEN:
351 X = wirelen;
352 continue;
353  
354 case BPF_LD|BPF_W|BPF_IND:
355 k = X + pc->k;
356 if (pc->k > buflen || X > buflen - pc->k ||
357 sizeof(int32_t) > buflen - k) {
358 #if defined(KERNEL) || defined(_KERNEL)
359 if (m == NULL)
360 return 0;
361 A = m_xword(m, k, &merr);
362 if (merr != 0)
363 return 0;
364 continue;
365 #else
366 return 0;
367 #endif
368 }
369 A = EXTRACT_LONG(&p[k]);
370 continue;
371  
372 case BPF_LD|BPF_H|BPF_IND:
373 k = X + pc->k;
374 if (X > buflen || pc->k > buflen - X ||
375 sizeof(int16_t) > buflen - k) {
376 #if defined(KERNEL) || defined(_KERNEL)
377 if (m == NULL)
378 return 0;
379 A = m_xhalf(m, k, &merr);
380 if (merr != 0)
381 return 0;
382 continue;
383 #else
384 return 0;
385 #endif
386 }
387 A = EXTRACT_SHORT(&p[k]);
388 continue;
389  
390 case BPF_LD|BPF_B|BPF_IND:
391 k = X + pc->k;
392 if (pc->k >= buflen || X >= buflen - pc->k) {
393 #if defined(KERNEL) || defined(_KERNEL)
394 if (m == NULL)
395 return 0;
396 n = m;
397 MINDEX(len, n, k);
398 A = mtod(n, u_char *)[k];
399 continue;
400 #else
401 return 0;
402 #endif
403 }
404 A = p[k];
405 continue;
406  
407 case BPF_LDX|BPF_MSH|BPF_B:
408 k = pc->k;
409 if (k >= buflen) {
410 #if defined(KERNEL) || defined(_KERNEL)
411 if (m == NULL)
412 return 0;
413 n = m;
414 MINDEX(len, n, k);
415 X = (mtod(n, char *)[k] & 0xf) << 2;
416 continue;
417 #else
418 return 0;
419 #endif
420 }
421 X = (p[pc->k] & 0xf) << 2;
422 continue;
423  
424 case BPF_LD|BPF_IMM:
425 A = pc->k;
426 continue;
427  
428 case BPF_LDX|BPF_IMM:
429 X = pc->k;
430 continue;
431  
432 case BPF_LD|BPF_MEM:
433 A = mem[pc->k];
434 continue;
435  
436 case BPF_LDX|BPF_MEM:
437 X = mem[pc->k];
438 continue;
439  
440 case BPF_ST:
441 mem[pc->k] = A;
442 continue;
443  
444 case BPF_STX:
445 mem[pc->k] = X;
446 continue;
447  
448 case BPF_JMP|BPF_JA:
449 #if defined(KERNEL) || defined(_KERNEL)
450 /*
451 * No backward jumps allowed.
452 */
453 pc += pc->k;
454 #else
455 /*
456 * XXX - we currently implement "ip6 protochain"
457 * with backward jumps, so sign-extend pc->k.
458 */
459 pc += (bpf_int32)pc->k;
460 #endif
461 continue;
462  
463 case BPF_JMP|BPF_JGT|BPF_K:
464 pc += (A > pc->k) ? pc->jt : pc->jf;
465 continue;
466  
467 case BPF_JMP|BPF_JGE|BPF_K:
468 pc += (A >= pc->k) ? pc->jt : pc->jf;
469 continue;
470  
471 case BPF_JMP|BPF_JEQ|BPF_K:
472 pc += (A == pc->k) ? pc->jt : pc->jf;
473 continue;
474  
475 case BPF_JMP|BPF_JSET|BPF_K:
476 pc += (A & pc->k) ? pc->jt : pc->jf;
477 continue;
478  
479 case BPF_JMP|BPF_JGT|BPF_X:
480 pc += (A > X) ? pc->jt : pc->jf;
481 continue;
482  
483 case BPF_JMP|BPF_JGE|BPF_X:
484 pc += (A >= X) ? pc->jt : pc->jf;
485 continue;
486  
487 case BPF_JMP|BPF_JEQ|BPF_X:
488 pc += (A == X) ? pc->jt : pc->jf;
489 continue;
490  
491 case BPF_JMP|BPF_JSET|BPF_X:
492 pc += (A & X) ? pc->jt : pc->jf;
493 continue;
494  
495 case BPF_ALU|BPF_ADD|BPF_X:
496 A += X;
497 continue;
498  
499 case BPF_ALU|BPF_SUB|BPF_X:
500 A -= X;
501 continue;
502  
503 case BPF_ALU|BPF_MUL|BPF_X:
504 A *= X;
505 continue;
506  
507 case BPF_ALU|BPF_DIV|BPF_X:
508 if (X == 0)
509 return 0;
510 A /= X;
511 continue;
512  
513 case BPF_ALU|BPF_MOD|BPF_X:
514 if (X == 0)
515 return 0;
516 A %= X;
517 continue;
518  
519 case BPF_ALU|BPF_AND|BPF_X:
520 A &= X;
521 continue;
522  
523 case BPF_ALU|BPF_OR|BPF_X:
524 A |= X;
525 continue;
526  
527 case BPF_ALU|BPF_XOR|BPF_X:
528 A ^= X;
529 continue;
530  
531 case BPF_ALU|BPF_LSH|BPF_X:
532 A <<= X;
533 continue;
534  
535 case BPF_ALU|BPF_RSH|BPF_X:
536 A >>= X;
537 continue;
538  
539 case BPF_ALU|BPF_ADD|BPF_K:
540 A += pc->k;
541 continue;
542  
543 case BPF_ALU|BPF_SUB|BPF_K:
544 A -= pc->k;
545 continue;
546  
547 case BPF_ALU|BPF_MUL|BPF_K:
548 A *= pc->k;
549 continue;
550  
551 case BPF_ALU|BPF_DIV|BPF_K:
552 A /= pc->k;
553 continue;
554  
555 case BPF_ALU|BPF_MOD|BPF_K:
556 A %= pc->k;
557 continue;
558  
559 case BPF_ALU|BPF_AND|BPF_K:
560 A &= pc->k;
561 continue;
562  
563 case BPF_ALU|BPF_OR|BPF_K:
564 A |= pc->k;
565 continue;
566  
567 case BPF_ALU|BPF_XOR|BPF_K:
568 A ^= pc->k;
569 continue;
570  
571 case BPF_ALU|BPF_LSH|BPF_K:
572 A <<= pc->k;
573 continue;
574  
575 case BPF_ALU|BPF_RSH|BPF_K:
576 A >>= pc->k;
577 continue;
578  
579 case BPF_ALU|BPF_NEG:
580 A = -A;
581 continue;
582  
583 case BPF_MISC|BPF_TAX:
584 X = A;
585 continue;
586  
587 case BPF_MISC|BPF_TXA:
588 A = X;
589 continue;
590 }
591 }
592 }
593  
594 u_int
595 bpf_filter(pc, p, wirelen, buflen)
596 register const struct bpf_insn *pc;
597 register const u_char *p;
598 u_int wirelen;
599 register u_int buflen;
600 {
601 return bpf_filter_with_aux_data(pc, p, wirelen, buflen, NULL);
602 }
603  
604  
605 /*
606 * Return true if the 'fcode' is a valid filter program.
607 * The constraints are that each jump be forward and to a valid
608 * code, that memory accesses are within valid ranges (to the
609 * extent that this can be checked statically; loads of packet
610 * data have to be, and are, also checked at run time), and that
611 * the code terminates with either an accept or reject.
612 *
613 * The kernel needs to be able to verify an application's filter code.
614 * Otherwise, a bogus program could easily crash the system.
615 */
616 int
617 bpf_validate(f, len)
618 const struct bpf_insn *f;
619 int len;
620 {
621 u_int i, from;
622 const struct bpf_insn *p;
623  
624 if (len < 1)
625 return 0;
626 /*
627 * There's no maximum program length in userland.
628 */
629 #if defined(KERNEL) || defined(_KERNEL)
630 if (len > BPF_MAXINSNS)
631 return 0;
632 #endif
633  
634 for (i = 0; i < len; ++i) {
635 p = &f[i];
636 switch (BPF_CLASS(p->code)) {
637 /*
638 * Check that memory operations use valid addresses.
639 */
640 case BPF_LD:
641 case BPF_LDX:
642 switch (BPF_MODE(p->code)) {
643 case BPF_IMM:
644 break;
645 case BPF_ABS:
646 case BPF_IND:
647 case BPF_MSH:
648 /*
649 * There's no maximum packet data size
650 * in userland. The runtime packet length
651 * check suffices.
652 */
653 #if defined(KERNEL) || defined(_KERNEL)
654 /*
655 * More strict check with actual packet length
656 * is done runtime.
657 */
658 if (p->k >= bpf_maxbufsize)
659 return 0;
660 #endif
661 break;
662 case BPF_MEM:
663 if (p->k >= BPF_MEMWORDS)
664 return 0;
665 break;
666 case BPF_LEN:
667 break;
668 default:
669 return 0;
670 }
671 break;
672 case BPF_ST:
673 case BPF_STX:
674 if (p->k >= BPF_MEMWORDS)
675 return 0;
676 break;
677 case BPF_ALU:
678 switch (BPF_OP(p->code)) {
679 case BPF_ADD:
680 case BPF_SUB:
681 case BPF_MUL:
682 case BPF_OR:
683 case BPF_AND:
684 case BPF_XOR:
685 case BPF_LSH:
686 case BPF_RSH:
687 case BPF_NEG:
688 break;
689 case BPF_DIV:
690 case BPF_MOD:
691 /*
692 * Check for constant division or modulus
693 * by 0.
694 */
695 if (BPF_SRC(p->code) == BPF_K && p->k == 0)
696 return 0;
697 break;
698 default:
699 return 0;
700 }
701 break;
702 case BPF_JMP:
703 /*
704 * Check that jumps are within the code block,
705 * and that unconditional branches don't go
706 * backwards as a result of an overflow.
707 * Unconditional branches have a 32-bit offset,
708 * so they could overflow; we check to make
709 * sure they don't. Conditional branches have
710 * an 8-bit offset, and the from address is <=
711 * BPF_MAXINSNS, and we assume that BPF_MAXINSNS
712 * is sufficiently small that adding 255 to it
713 * won't overflow.
714 *
715 * We know that len is <= BPF_MAXINSNS, and we
716 * assume that BPF_MAXINSNS is < the maximum size
717 * of a u_int, so that i + 1 doesn't overflow.
718 *
719 * For userland, we don't know that the from
720 * or len are <= BPF_MAXINSNS, but we know that
721 * from <= len, and, except on a 64-bit system,
722 * it's unlikely that len, if it truly reflects
723 * the size of the program we've been handed,
724 * will be anywhere near the maximum size of
725 * a u_int. We also don't check for backward
726 * branches, as we currently support them in
727 * userland for the protochain operation.
728 */
729 from = i + 1;
730 switch (BPF_OP(p->code)) {
731 case BPF_JA:
732 #if defined(KERNEL) || defined(_KERNEL)
733 if (from + p->k < from || from + p->k >= len)
734 #else
735 if (from + p->k >= len)
736 #endif
737 return 0;
738 break;
739 case BPF_JEQ:
740 case BPF_JGT:
741 case BPF_JGE:
742 case BPF_JSET:
743 if (from + p->jt >= len || from + p->jf >= len)
744 return 0;
745 break;
746 default:
747 return 0;
748 }
749 break;
750 case BPF_RET:
751 break;
752 case BPF_MISC:
753 break;
754 default:
755 return 0;
756 }
757 }
758 return BPF_CLASS(f[len - 1].code) == BPF_RET;
759 }