Fix typo in Makefile syntax to unbreak the build. Top was being patched from /cvs...
[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 $
158abb01 41 * $DragonFly: src/sys/net/bpf_filter.c,v 1.4 2003/08/26 20:49:47 rob Exp $
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42 */
43
44#include <sys/param.h>
45
46#ifdef sun
47#include <netinet/in.h>
48#endif
49
50#if defined(sparc) || defined(mips) || defined(ibm032) || defined(__alpha__)
51#define BPF_ALIGN
52#endif
53
54#ifndef BPF_ALIGN
55#define EXTRACT_SHORT(p) ((u_int16_t)ntohs(*(u_int16_t *)p))
56#define EXTRACT_LONG(p) (ntohl(*(u_int32_t *)p))
57#else
58#define EXTRACT_SHORT(p)\
59 ((u_int16_t)\
60 ((u_int16_t)*((u_char *)p+0)<<8|\
61 (u_int16_t)*((u_char *)p+1)<<0))
62#define EXTRACT_LONG(p)\
63 ((u_int32_t)*((u_char *)p+0)<<24|\
64 (u_int32_t)*((u_char *)p+1)<<16|\
65 (u_int32_t)*((u_char *)p+2)<<8|\
66 (u_int32_t)*((u_char *)p+3)<<0)
67#endif
68
69#ifdef _KERNEL
70#include <sys/mbuf.h>
71#endif
72#include <net/bpf.h>
73#ifdef _KERNEL
74#define MINDEX(m, k) \
75{ \
82ed7fc2 76 int len = m->m_len; \
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77 \
78 while (k >= len) { \
79 k -= len; \
80 m = m->m_next; \
81 if (m == 0) \
82 return 0; \
83 len = m->m_len; \
84 } \
85}
86
158abb01
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87static u_int16_t m_xhalf (struct mbuf *m, bpf_u_int32 k, int *err);
88static u_int32_t m_xword (struct mbuf *m, bpf_u_int32 k, int *err);
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89
90static u_int32_t
91m_xword(m, k, err)
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92 struct mbuf *m;
93 bpf_u_int32 k;
94 int *err;
984263bc 95{
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96 size_t len;
97 u_char *cp, *np;
98 struct mbuf *m0;
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99
100 len = m->m_len;
101 while (k >= len) {
102 k -= len;
103 m = m->m_next;
104 if (m == 0)
105 goto bad;
106 len = m->m_len;
107 }
108 cp = mtod(m, u_char *) + k;
109 if (len - k >= 4) {
110 *err = 0;
111 return EXTRACT_LONG(cp);
112 }
113 m0 = m->m_next;
114 if (m0 == 0 || m0->m_len + len - k < 4)
115 goto bad;
116 *err = 0;
117 np = mtod(m0, u_char *);
118 switch (len - k) {
119
120 case 1:
121 return
122 ((u_int32_t)cp[0] << 24) |
123 ((u_int32_t)np[0] << 16) |
124 ((u_int32_t)np[1] << 8) |
125 (u_int32_t)np[2];
126
127 case 2:
128 return
129 ((u_int32_t)cp[0] << 24) |
130 ((u_int32_t)cp[1] << 16) |
131 ((u_int32_t)np[0] << 8) |
132 (u_int32_t)np[1];
133
134 default:
135 return
136 ((u_int32_t)cp[0] << 24) |
137 ((u_int32_t)cp[1] << 16) |
138 ((u_int32_t)cp[2] << 8) |
139 (u_int32_t)np[0];
140 }
141 bad:
142 *err = 1;
143 return 0;
144}
145
146static u_int16_t
147m_xhalf(m, k, err)
82ed7fc2
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148 struct mbuf *m;
149 bpf_u_int32 k;
150 int *err;
984263bc 151{
82ed7fc2
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152 size_t len;
153 u_char *cp;
154 struct mbuf *m0;
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155
156 len = m->m_len;
157 while (k >= len) {
158 k -= len;
159 m = m->m_next;
160 if (m == 0)
161 goto bad;
162 len = m->m_len;
163 }
164 cp = mtod(m, u_char *) + k;
165 if (len - k >= 2) {
166 *err = 0;
167 return EXTRACT_SHORT(cp);
168 }
169 m0 = m->m_next;
170 if (m0 == 0)
171 goto bad;
172 *err = 0;
173 return (cp[0] << 8) | mtod(m0, u_char *)[0];
174 bad:
175 *err = 1;
176 return 0;
177}
178#endif
179
180/*
181 * Execute the filter program starting at pc on the packet p
182 * wirelen is the length of the original packet
183 * buflen is the amount of data present
184 */
185u_int
186bpf_filter(pc, p, wirelen, buflen)
82ed7fc2
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187 const struct bpf_insn *pc;
188 u_char *p;
984263bc 189 u_int wirelen;
82ed7fc2 190 u_int buflen;
984263bc 191{
82ed7fc2
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192 u_int32_t A = 0, X = 0;
193 bpf_u_int32 k;
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194 int32_t mem[BPF_MEMWORDS];
195
196 if (pc == 0)
197 /*
198 * No filter means accept all.
199 */
200 return (u_int)-1;
201
202 --pc;
203 while (1) {
204 ++pc;
205 switch (pc->code) {
206
207 default:
208#ifdef _KERNEL
209 return 0;
210#else
211 abort();
212#endif
213 case BPF_RET|BPF_K:
214 return (u_int)pc->k;
215
216 case BPF_RET|BPF_A:
217 return (u_int)A;
218
219 case BPF_LD|BPF_W|BPF_ABS:
220 k = pc->k;
221 if (k > buflen || sizeof(int32_t) > buflen - k) {
222#ifdef _KERNEL
223 int merr;
224
225 if (buflen != 0)
226 return 0;
227 A = m_xword((struct mbuf *)p, k, &merr);
228 if (merr != 0)
229 return 0;
230 continue;
231#else
232 return 0;
233#endif
234 }
235#ifdef BPF_ALIGN
236 if (((intptr_t)(p + k) & 3) != 0)
237 A = EXTRACT_LONG(&p[k]);
238 else
239#endif
240 A = ntohl(*(int32_t *)(p + k));
241 continue;
242
243 case BPF_LD|BPF_H|BPF_ABS:
244 k = pc->k;
245 if (k > buflen || sizeof(int16_t) > buflen - k) {
246#ifdef _KERNEL
247 int merr;
248
249 if (buflen != 0)
250 return 0;
251 A = m_xhalf((struct mbuf *)p, k, &merr);
252 continue;
253#else
254 return 0;
255#endif
256 }
257 A = EXTRACT_SHORT(&p[k]);
258 continue;
259
260 case BPF_LD|BPF_B|BPF_ABS:
261 k = pc->k;
262 if (k >= buflen) {
263#ifdef _KERNEL
82ed7fc2 264 struct mbuf *m;
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265
266 if (buflen != 0)
267 return 0;
268 m = (struct mbuf *)p;
269 MINDEX(m, k);
270 A = mtod(m, u_char *)[k];
271 continue;
272#else
273 return 0;
274#endif
275 }
276 A = p[k];
277 continue;
278
279 case BPF_LD|BPF_W|BPF_LEN:
280 A = wirelen;
281 continue;
282
283 case BPF_LDX|BPF_W|BPF_LEN:
284 X = wirelen;
285 continue;
286
287 case BPF_LD|BPF_W|BPF_IND:
288 k = X + pc->k;
289 if (pc->k > buflen || X > buflen - pc->k ||
290 sizeof(int32_t) > buflen - k) {
291#ifdef _KERNEL
292 int merr;
293
294 if (buflen != 0)
295 return 0;
296 A = m_xword((struct mbuf *)p, k, &merr);
297 if (merr != 0)
298 return 0;
299 continue;
300#else
301 return 0;
302#endif
303 }
304#ifdef BPF_ALIGN
305 if (((intptr_t)(p + k) & 3) != 0)
306 A = EXTRACT_LONG(&p[k]);
307 else
308#endif
309 A = ntohl(*(int32_t *)(p + k));
310 continue;
311
312 case BPF_LD|BPF_H|BPF_IND:
313 k = X + pc->k;
314 if (X > buflen || pc->k > buflen - X ||
315 sizeof(int16_t) > buflen - k) {
316#ifdef _KERNEL
317 int merr;
318
319 if (buflen != 0)
320 return 0;
321 A = m_xhalf((struct mbuf *)p, k, &merr);
322 if (merr != 0)
323 return 0;
324 continue;
325#else
326 return 0;
327#endif
328 }
329 A = EXTRACT_SHORT(&p[k]);
330 continue;
331
332 case BPF_LD|BPF_B|BPF_IND:
333 k = X + pc->k;
334 if (pc->k >= buflen || X >= buflen - pc->k) {
335#ifdef _KERNEL
82ed7fc2 336 struct mbuf *m;
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337
338 if (buflen != 0)
339 return 0;
340 m = (struct mbuf *)p;
341 MINDEX(m, k);
342 A = mtod(m, char *)[k];
343 continue;
344#else
345 return 0;
346#endif
347 }
348 A = p[k];
349 continue;
350
351 case BPF_LDX|BPF_MSH|BPF_B:
352 k = pc->k;
353 if (k >= buflen) {
354#ifdef _KERNEL
82ed7fc2 355 struct mbuf *m;
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356
357 if (buflen != 0)
358 return 0;
359 m = (struct mbuf *)p;
360 MINDEX(m, k);
361 X = (mtod(m, char *)[k] & 0xf) << 2;
362 continue;
363#else
364 return 0;
365#endif
366 }
367 X = (p[pc->k] & 0xf) << 2;
368 continue;
369
370 case BPF_LD|BPF_IMM:
371 A = pc->k;
372 continue;
373
374 case BPF_LDX|BPF_IMM:
375 X = pc->k;
376 continue;
377
378 case BPF_LD|BPF_MEM:
379 A = mem[pc->k];
380 continue;
381
382 case BPF_LDX|BPF_MEM:
383 X = mem[pc->k];
384 continue;
385
386 case BPF_ST:
387 mem[pc->k] = A;
388 continue;
389
390 case BPF_STX:
391 mem[pc->k] = X;
392 continue;
393
394 case BPF_JMP|BPF_JA:
395 pc += pc->k;
396 continue;
397
398 case BPF_JMP|BPF_JGT|BPF_K:
399 pc += (A > pc->k) ? pc->jt : pc->jf;
400 continue;
401
402 case BPF_JMP|BPF_JGE|BPF_K:
403 pc += (A >= pc->k) ? pc->jt : pc->jf;
404 continue;
405
406 case BPF_JMP|BPF_JEQ|BPF_K:
407 pc += (A == pc->k) ? pc->jt : pc->jf;
408 continue;
409
410 case BPF_JMP|BPF_JSET|BPF_K:
411 pc += (A & pc->k) ? pc->jt : pc->jf;
412 continue;
413
414 case BPF_JMP|BPF_JGT|BPF_X:
415 pc += (A > X) ? pc->jt : pc->jf;
416 continue;
417
418 case BPF_JMP|BPF_JGE|BPF_X:
419 pc += (A >= X) ? pc->jt : pc->jf;
420 continue;
421
422 case BPF_JMP|BPF_JEQ|BPF_X:
423 pc += (A == X) ? pc->jt : pc->jf;
424 continue;
425
426 case BPF_JMP|BPF_JSET|BPF_X:
427 pc += (A & X) ? pc->jt : pc->jf;
428 continue;
429
430 case BPF_ALU|BPF_ADD|BPF_X:
431 A += X;
432 continue;
433
434 case BPF_ALU|BPF_SUB|BPF_X:
435 A -= X;
436 continue;
437
438 case BPF_ALU|BPF_MUL|BPF_X:
439 A *= X;
440 continue;
441
442 case BPF_ALU|BPF_DIV|BPF_X:
443 if (X == 0)
444 return 0;
445 A /= X;
446 continue;
447
448 case BPF_ALU|BPF_AND|BPF_X:
449 A &= X;
450 continue;
451
452 case BPF_ALU|BPF_OR|BPF_X:
453 A |= X;
454 continue;
455
456 case BPF_ALU|BPF_LSH|BPF_X:
457 A <<= X;
458 continue;
459
460 case BPF_ALU|BPF_RSH|BPF_X:
461 A >>= X;
462 continue;
463
464 case BPF_ALU|BPF_ADD|BPF_K:
465 A += pc->k;
466 continue;
467
468 case BPF_ALU|BPF_SUB|BPF_K:
469 A -= pc->k;
470 continue;
471
472 case BPF_ALU|BPF_MUL|BPF_K:
473 A *= pc->k;
474 continue;
475
476 case BPF_ALU|BPF_DIV|BPF_K:
477 A /= pc->k;
478 continue;
479
480 case BPF_ALU|BPF_AND|BPF_K:
481 A &= pc->k;
482 continue;
483
484 case BPF_ALU|BPF_OR|BPF_K:
485 A |= pc->k;
486 continue;
487
488 case BPF_ALU|BPF_LSH|BPF_K:
489 A <<= pc->k;
490 continue;
491
492 case BPF_ALU|BPF_RSH|BPF_K:
493 A >>= pc->k;
494 continue;
495
496 case BPF_ALU|BPF_NEG:
497 A = -A;
498 continue;
499
500 case BPF_MISC|BPF_TAX:
501 X = A;
502 continue;
503
504 case BPF_MISC|BPF_TXA:
505 A = X;
506 continue;
507 }
508 }
509}
510
511#ifdef _KERNEL
512/*
513 * Return true if the 'fcode' is a valid filter program.
514 * The constraints are that each jump be forward and to a valid
515 * code. The code must terminate with either an accept or reject.
516 *
517 * The kernel needs to be able to verify an application's filter code.
518 * Otherwise, a bogus program could easily crash the system.
519 */
520int
521bpf_validate(f, len)
522 const struct bpf_insn *f;
523 int len;
524{
82ed7fc2
RG
525 int i;
526 const struct bpf_insn *p;
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527
528 for (i = 0; i < len; ++i) {
529 /*
530 * Check that that jumps are forward, and within
531 * the code block.
532 */
533 p = &f[i];
534 if (BPF_CLASS(p->code) == BPF_JMP) {
82ed7fc2 535 int from = i + 1;
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536
537 if (BPF_OP(p->code) == BPF_JA) {
538 if (from >= len || p->k >= len - from)
539 return 0;
540 }
541 else if (from >= len || p->jt >= len - from ||
542 p->jf >= len - from)
543 return 0;
544 }
545 /*
546 * Check that memory operations use valid addresses.
547 */
548 if ((BPF_CLASS(p->code) == BPF_ST ||
549 (BPF_CLASS(p->code) == BPF_LD &&
550 (p->code & 0xe0) == BPF_MEM)) &&
551 p->k >= BPF_MEMWORDS)
552 return 0;
553 /*
554 * Check for constant division by 0.
555 */
556 if (p->code == (BPF_ALU|BPF_DIV|BPF_K) && p->k == 0)
557 return 0;
558 }
559 return BPF_CLASS(f[len - 1].code) == BPF_RET;
560}
561#endif