bge: Avoid accessing invalid internal memory region on BCM5906
[dragonfly.git] / sys / net / bpf_filter.c
CommitLineData
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1/*
2 * Copyright (c) 1990, 1991, 1993
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_filter.c 8.1 (Berkeley) 6/10/93
39 *
40 * $FreeBSD: src/sys/net/bpf_filter.c,v 1.17 1999/12/29 04:38:31 peter Exp $
41 */
42
2d4fcd80 43#include <sys/systm.h>
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44#include <sys/param.h>
45
20df2adc 46#if defined(sparc) || defined(mips) || defined(ibm032)
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47#define BPF_ALIGN
48#endif
49
50#ifndef BPF_ALIGN
51#define EXTRACT_SHORT(p) ((u_int16_t)ntohs(*(u_int16_t *)p))
52#define EXTRACT_LONG(p) (ntohl(*(u_int32_t *)p))
53#else
54#define EXTRACT_SHORT(p)\
55 ((u_int16_t)\
56 ((u_int16_t)*((u_char *)p+0)<<8|\
57 (u_int16_t)*((u_char *)p+1)<<0))
58#define EXTRACT_LONG(p)\
59 ((u_int32_t)*((u_char *)p+0)<<24|\
60 (u_int32_t)*((u_char *)p+1)<<16|\
61 (u_int32_t)*((u_char *)p+2)<<8|\
62 (u_int32_t)*((u_char *)p+3)<<0)
63#endif
64
65#ifdef _KERNEL
66#include <sys/mbuf.h>
67#endif
68#include <net/bpf.h>
69#ifdef _KERNEL
7c1ae3b3
CP
70#define MINDEX(m, k) \
71{ \
72 int len = m->m_len; \
f23061d4 73 \
7c1ae3b3
CP
74 while (k >= len) { \
75 k -= len; \
76 m = m->m_next; \
77 if (m == 0) \
78 return 0; \
79 len = m->m_len; \
80 } \
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81}
82
faff5ee2
SZ
83extern int bpf_maxbufsize;
84
158abb01
RG
85static u_int16_t m_xhalf (struct mbuf *m, bpf_u_int32 k, int *err);
86static u_int32_t m_xword (struct mbuf *m, bpf_u_int32 k, int *err);
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87
88static u_int32_t
7c1ae3b3 89m_xword(struct mbuf *m, bpf_u_int32 k, int *err)
984263bc 90{
82ed7fc2
RG
91 size_t len;
92 u_char *cp, *np;
93 struct mbuf *m0;
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94
95 len = m->m_len;
96 while (k >= len) {
97 k -= len;
98 m = m->m_next;
4090d6ff 99 if (m == NULL)
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100 goto bad;
101 len = m->m_len;
102 }
103 cp = mtod(m, u_char *) + k;
104 if (len - k >= 4) {
105 *err = 0;
106 return EXTRACT_LONG(cp);
107 }
108 m0 = m->m_next;
4090d6ff 109 if (m0 == NULL || m0->m_len + len - k < 4)
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110 goto bad;
111 *err = 0;
112 np = mtod(m0, u_char *);
113 switch (len - k) {
114
115 case 1:
116 return
117 ((u_int32_t)cp[0] << 24) |
118 ((u_int32_t)np[0] << 16) |
119 ((u_int32_t)np[1] << 8) |
120 (u_int32_t)np[2];
121
122 case 2:
123 return
124 ((u_int32_t)cp[0] << 24) |
125 ((u_int32_t)cp[1] << 16) |
126 ((u_int32_t)np[0] << 8) |
127 (u_int32_t)np[1];
128
129 default:
130 return
131 ((u_int32_t)cp[0] << 24) |
132 ((u_int32_t)cp[1] << 16) |
133 ((u_int32_t)cp[2] << 8) |
134 (u_int32_t)np[0];
135 }
136 bad:
137 *err = 1;
138 return 0;
139}
140
141static u_int16_t
7c1ae3b3 142m_xhalf(struct mbuf *m, bpf_u_int32 k, int *err)
984263bc 143{
82ed7fc2
RG
144 size_t len;
145 u_char *cp;
146 struct mbuf *m0;
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MD
147
148 len = m->m_len;
149 while (k >= len) {
150 k -= len;
151 m = m->m_next;
4090d6ff 152 if (m == NULL)
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153 goto bad;
154 len = m->m_len;
155 }
156 cp = mtod(m, u_char *) + k;
157 if (len - k >= 2) {
158 *err = 0;
159 return EXTRACT_SHORT(cp);
160 }
161 m0 = m->m_next;
4090d6ff 162 if (m0 == NULL)
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163 goto bad;
164 *err = 0;
165 return (cp[0] << 8) | mtod(m0, u_char *)[0];
166 bad:
167 *err = 1;
168 return 0;
169}
170#endif
171
172/*
173 * Execute the filter program starting at pc on the packet p
174 * wirelen is the length of the original packet
175 * buflen is the amount of data present
176 */
177u_int
7c1ae3b3 178bpf_filter(const struct bpf_insn *pc, u_char *p, u_int wirelen, u_int buflen)
984263bc 179{
82ed7fc2
RG
180 u_int32_t A = 0, X = 0;
181 bpf_u_int32 k;
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MD
182 int32_t mem[BPF_MEMWORDS];
183
2d4fcd80
VS
184 bzero(mem, sizeof(mem));
185
4090d6ff 186 if (pc == NULL) {
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187 /*
188 * No filter means accept all.
189 */
190 return (u_int)-1;
7c1ae3b3 191 }
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192
193 --pc;
194 while (1) {
195 ++pc;
196 switch (pc->code) {
197
198 default:
199#ifdef _KERNEL
200 return 0;
201#else
202 abort();
203#endif
204 case BPF_RET|BPF_K:
205 return (u_int)pc->k;
206
207 case BPF_RET|BPF_A:
208 return (u_int)A;
209
210 case BPF_LD|BPF_W|BPF_ABS:
211 k = pc->k;
212 if (k > buflen || sizeof(int32_t) > buflen - k) {
213#ifdef _KERNEL
214 int merr;
215
216 if (buflen != 0)
217 return 0;
218 A = m_xword((struct mbuf *)p, k, &merr);
219 if (merr != 0)
220 return 0;
221 continue;
222#else
223 return 0;
224#endif
225 }
226#ifdef BPF_ALIGN
227 if (((intptr_t)(p + k) & 3) != 0)
228 A = EXTRACT_LONG(&p[k]);
229 else
230#endif
231 A = ntohl(*(int32_t *)(p + k));
232 continue;
233
234 case BPF_LD|BPF_H|BPF_ABS:
235 k = pc->k;
236 if (k > buflen || sizeof(int16_t) > buflen - k) {
237#ifdef _KERNEL
238 int merr;
239
240 if (buflen != 0)
241 return 0;
242 A = m_xhalf((struct mbuf *)p, k, &merr);
243 continue;
244#else
245 return 0;
246#endif
247 }
248 A = EXTRACT_SHORT(&p[k]);
249 continue;
250
251 case BPF_LD|BPF_B|BPF_ABS:
252 k = pc->k;
253 if (k >= buflen) {
254#ifdef _KERNEL
82ed7fc2 255 struct mbuf *m;
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256
257 if (buflen != 0)
258 return 0;
259 m = (struct mbuf *)p;
260 MINDEX(m, k);
261 A = mtod(m, u_char *)[k];
262 continue;
263#else
264 return 0;
265#endif
266 }
267 A = p[k];
268 continue;
269
270 case BPF_LD|BPF_W|BPF_LEN:
271 A = wirelen;
272 continue;
273
274 case BPF_LDX|BPF_W|BPF_LEN:
275 X = wirelen;
276 continue;
277
278 case BPF_LD|BPF_W|BPF_IND:
279 k = X + pc->k;
280 if (pc->k > buflen || X > buflen - pc->k ||
281 sizeof(int32_t) > buflen - k) {
282#ifdef _KERNEL
283 int merr;
284
285 if (buflen != 0)
286 return 0;
287 A = m_xword((struct mbuf *)p, k, &merr);
288 if (merr != 0)
289 return 0;
290 continue;
291#else
292 return 0;
293#endif
294 }
295#ifdef BPF_ALIGN
296 if (((intptr_t)(p + k) & 3) != 0)
297 A = EXTRACT_LONG(&p[k]);
298 else
299#endif
300 A = ntohl(*(int32_t *)(p + k));
301 continue;
302
303 case BPF_LD|BPF_H|BPF_IND:
304 k = X + pc->k;
305 if (X > buflen || pc->k > buflen - X ||
306 sizeof(int16_t) > buflen - k) {
307#ifdef _KERNEL
308 int merr;
309
310 if (buflen != 0)
311 return 0;
312 A = m_xhalf((struct mbuf *)p, k, &merr);
313 if (merr != 0)
314 return 0;
315 continue;
316#else
317 return 0;
318#endif
319 }
320 A = EXTRACT_SHORT(&p[k]);
321 continue;
322
323 case BPF_LD|BPF_B|BPF_IND:
324 k = X + pc->k;
325 if (pc->k >= buflen || X >= buflen - pc->k) {
326#ifdef _KERNEL
82ed7fc2 327 struct mbuf *m;
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328
329 if (buflen != 0)
330 return 0;
331 m = (struct mbuf *)p;
332 MINDEX(m, k);
3653973d 333 A = mtod(m, u_char *)[k];
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334 continue;
335#else
336 return 0;
337#endif
338 }
339 A = p[k];
340 continue;
341
342 case BPF_LDX|BPF_MSH|BPF_B:
343 k = pc->k;
344 if (k >= buflen) {
345#ifdef _KERNEL
82ed7fc2 346 struct mbuf *m;
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347
348 if (buflen != 0)
349 return 0;
350 m = (struct mbuf *)p;
351 MINDEX(m, k);
352 X = (mtod(m, char *)[k] & 0xf) << 2;
353 continue;
354#else
355 return 0;
356#endif
357 }
358 X = (p[pc->k] & 0xf) << 2;
359 continue;
360
361 case BPF_LD|BPF_IMM:
362 A = pc->k;
363 continue;
364
365 case BPF_LDX|BPF_IMM:
366 X = pc->k;
367 continue;
368
369 case BPF_LD|BPF_MEM:
370 A = mem[pc->k];
371 continue;
372
373 case BPF_LDX|BPF_MEM:
374 X = mem[pc->k];
375 continue;
376
377 case BPF_ST:
378 mem[pc->k] = A;
379 continue;
380
381 case BPF_STX:
382 mem[pc->k] = X;
383 continue;
384
385 case BPF_JMP|BPF_JA:
386 pc += pc->k;
387 continue;
388
389 case BPF_JMP|BPF_JGT|BPF_K:
390 pc += (A > pc->k) ? pc->jt : pc->jf;
391 continue;
392
393 case BPF_JMP|BPF_JGE|BPF_K:
394 pc += (A >= pc->k) ? pc->jt : pc->jf;
395 continue;
396
397 case BPF_JMP|BPF_JEQ|BPF_K:
398 pc += (A == pc->k) ? pc->jt : pc->jf;
399 continue;
400
401 case BPF_JMP|BPF_JSET|BPF_K:
402 pc += (A & pc->k) ? pc->jt : pc->jf;
403 continue;
404
405 case BPF_JMP|BPF_JGT|BPF_X:
406 pc += (A > X) ? pc->jt : pc->jf;
407 continue;
408
409 case BPF_JMP|BPF_JGE|BPF_X:
410 pc += (A >= X) ? pc->jt : pc->jf;
411 continue;
412
413 case BPF_JMP|BPF_JEQ|BPF_X:
414 pc += (A == X) ? pc->jt : pc->jf;
415 continue;
416
417 case BPF_JMP|BPF_JSET|BPF_X:
418 pc += (A & X) ? pc->jt : pc->jf;
419 continue;
420
421 case BPF_ALU|BPF_ADD|BPF_X:
422 A += X;
423 continue;
424
425 case BPF_ALU|BPF_SUB|BPF_X:
426 A -= X;
427 continue;
428
429 case BPF_ALU|BPF_MUL|BPF_X:
430 A *= X;
431 continue;
432
433 case BPF_ALU|BPF_DIV|BPF_X:
434 if (X == 0)
435 return 0;
436 A /= X;
437 continue;
438
439 case BPF_ALU|BPF_AND|BPF_X:
440 A &= X;
441 continue;
442
443 case BPF_ALU|BPF_OR|BPF_X:
444 A |= X;
445 continue;
446
447 case BPF_ALU|BPF_LSH|BPF_X:
448 A <<= X;
449 continue;
450
451 case BPF_ALU|BPF_RSH|BPF_X:
452 A >>= X;
453 continue;
454
455 case BPF_ALU|BPF_ADD|BPF_K:
456 A += pc->k;
457 continue;
458
459 case BPF_ALU|BPF_SUB|BPF_K:
460 A -= pc->k;
461 continue;
462
463 case BPF_ALU|BPF_MUL|BPF_K:
464 A *= pc->k;
465 continue;
466
467 case BPF_ALU|BPF_DIV|BPF_K:
468 A /= pc->k;
469 continue;
470
471 case BPF_ALU|BPF_AND|BPF_K:
472 A &= pc->k;
473 continue;
474
475 case BPF_ALU|BPF_OR|BPF_K:
476 A |= pc->k;
477 continue;
478
479 case BPF_ALU|BPF_LSH|BPF_K:
480 A <<= pc->k;
481 continue;
482
483 case BPF_ALU|BPF_RSH|BPF_K:
484 A >>= pc->k;
485 continue;
486
487 case BPF_ALU|BPF_NEG:
488 A = -A;
489 continue;
490
491 case BPF_MISC|BPF_TAX:
492 X = A;
493 continue;
494
495 case BPF_MISC|BPF_TXA:
496 A = X;
497 continue;
498 }
499 }
500}
501
502#ifdef _KERNEL
503/*
504 * Return true if the 'fcode' is a valid filter program.
faff5ee2
SZ
505 * The constraints are that each jump be forward and to a valid
506 * code, that memory accesses are within valid ranges (to the
507 * extent that this can be checked statically; loads of packet
508 * data have to be, and are, also checked at run time), and that
509 * the code terminates with either an accept or reject.
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MD
510 *
511 * The kernel needs to be able to verify an application's filter code.
512 * Otherwise, a bogus program could easily crash the system.
513 */
514int
7c1ae3b3 515bpf_validate(const struct bpf_insn *f, int len)
984263bc 516{
faff5ee2 517 u_int i, from;
82ed7fc2 518 const struct bpf_insn *p;
984263bc 519
faff5ee2
SZ
520 if (len < 1 || len > BPF_MAXINSNS)
521 return 0;
522
984263bc 523 for (i = 0; i < len; ++i) {
faff5ee2
SZ
524 p = &f[i];
525 switch (BPF_CLASS(p->code)) {
984263bc 526 /*
faff5ee2 527 * Check that memory operations use valid addresses.
984263bc 528 */
faff5ee2
SZ
529 case BPF_LD:
530 case BPF_LDX:
531 switch (BPF_MODE(p->code)) {
532 case BPF_IMM:
533 break;
534 case BPF_ABS:
535 case BPF_IND:
536 case BPF_MSH:
537 /*
538 * More strict check with actual packet length
539 * is done runtime.
540 */
541 if (p->k >= bpf_maxbufsize)
542 return 0;
543 break;
544 case BPF_MEM:
545 if (p->k >= BPF_MEMWORDS)
984263bc 546 return 0;
faff5ee2
SZ
547 break;
548 case BPF_LEN:
549 break;
550 default:
551 return 0;
984263bc 552 }
faff5ee2
SZ
553 break;
554 case BPF_ST:
555 case BPF_STX:
556 if (p->k >= BPF_MEMWORDS)
984263bc 557 return 0;
faff5ee2
SZ
558 break;
559 case BPF_ALU:
560 switch (BPF_OP(p->code)) {
561 case BPF_ADD:
562 case BPF_SUB:
563 case BPF_MUL:
564 case BPF_OR:
565 case BPF_AND:
566 case BPF_LSH:
567 case BPF_RSH:
568 case BPF_NEG:
569 break;
570 case BPF_DIV:
571 /*
572 * Check for constant division by 0.
573 */
3361ad4a 574 if (BPF_SRC(p->code) == BPF_K && p->k == 0)
faff5ee2
SZ
575 return 0;
576 break;
577 default:
578 return 0;
579 }
580 break;
581 case BPF_JMP:
582 /*
583 * Check that jumps are within the code block,
584 * and that unconditional branches don't go
585 * backwards as a result of an overflow.
586 * Unconditional branches have a 32-bit offset,
587 * so they could overflow; we check to make
588 * sure they don't. Conditional branches have
589 * an 8-bit offset, and the from address is <=
590 * BPF_MAXINSNS, and we assume that BPF_MAXINSNS
591 * is sufficiently small that adding 255 to it
592 * won't overflow.
593 *
594 * We know that len is <= BPF_MAXINSNS, and we
595 * assume that BPF_MAXINSNS is < the maximum size
596 * of a u_int, so that i + 1 doesn't overflow.
597 */
598 from = i + 1;
599 switch (BPF_OP(p->code)) {
600 case BPF_JA:
601 if (from + p->k < from || from + p->k >= len)
602 return 0;
603 break;
604 case BPF_JEQ:
605 case BPF_JGT:
606 case BPF_JGE:
607 case BPF_JSET:
608 if (from + p->jt >= len || from + p->jf >= len)
609 return 0;
610 break;
611 default:
612 return 0;
613 }
614 break;
615 case BPF_RET:
616 break;
617 case BPF_MISC:
618 break;
619 default:
984263bc 620 return 0;
faff5ee2 621 }
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MD
622 }
623 return BPF_CLASS(f[len - 1].code) == BPF_RET;
624}
625#endif