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[openwrt.git] / target / linux / etrax-2.6 / image / e100boot / src / libpcap-0.4 / bpf / net / bpf_filter.c
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 #if !(defined(lint) || defined(KERNEL))
42 static const char rcsid[] =
43 "@(#) $Header: /usr/local/cvs/linux/tools/build/e100boot/libpcap-0.4/bpf/net/bpf_filter.c,v 1.1 1999/08/26 10:07:57 johana Exp $ (LBL)";
44 #endif
45
46 #include <sys/param.h>
47 #include <sys/types.h>
48 #include <sys/time.h>
49 #include <net/bpf.h>
50
51 #ifndef KERNEL
52 #include <stdlib.h>
53 #endif
54
55 #define int32 bpf_int32
56 #define u_int32 bpf_u_int32
57
58 #ifndef LBL_ALIGN
59 #if defined(sparc) || defined(mips) || defined(ibm032) || \
60 defined(__alpha) || defined(__hpux)
61 #define LBL_ALIGN
62 #endif
63 #endif
64
65 #ifndef LBL_ALIGN
66 #include <netinet/in.h>
67
68 #define EXTRACT_SHORT(p) ((u_short)ntohs(*(u_short *)p))
69 #define EXTRACT_LONG(p) (ntohl(*(u_int32 *)p))
70 #else
71 #define EXTRACT_SHORT(p)\
72 ((u_short)\
73 ((u_short)*((u_char *)p+0)<<8|\
74 (u_short)*((u_char *)p+1)<<0))
75 #define EXTRACT_LONG(p)\
76 ((u_int32)*((u_char *)p+0)<<24|\
77 (u_int32)*((u_char *)p+1)<<16|\
78 (u_int32)*((u_char *)p+2)<<8|\
79 (u_int32)*((u_char *)p+3)<<0)
80 #endif
81
82 #ifdef KERNEL
83 #include <sys/mbuf.h>
84 #define MINDEX(len, m, k) \
85 { \
86 len = m->m_len; \
87 while (k >= len) { \
88 k -= len; \
89 m = m->m_next; \
90 if (m == 0) \
91 return 0; \
92 len = m->m_len; \
93 } \
94 }
95
96 static int
97 m_xword(m, k, err)
98 register struct mbuf *m;
99 register int k, *err;
100 {
101 register int len;
102 register u_char *cp, *np;
103 register struct mbuf *m0;
104
105 MINDEX(len, m, k);
106 cp = mtod(m, u_char *) + k;
107 if (len - k >= 4) {
108 *err = 0;
109 return EXTRACT_LONG(cp);
110 }
111 m0 = m->m_next;
112 if (m0 == 0 || m0->m_len + len - k < 4)
113 goto bad;
114 *err = 0;
115 np = mtod(m0, u_char *);
116 switch (len - k) {
117
118 case 1:
119 return (cp[0] << 24) | (np[0] << 16) | (np[1] << 8) | np[2];
120
121 case 2:
122 return (cp[0] << 24) | (cp[1] << 16) | (np[0] << 8) | np[1];
123
124 default:
125 return (cp[0] << 24) | (cp[1] << 16) | (cp[2] << 8) | np[0];
126 }
127 bad:
128 *err = 1;
129 return 0;
130 }
131
132 static int
133 m_xhalf(m, k, err)
134 register struct mbuf *m;
135 register int k, *err;
136 {
137 register int len;
138 register u_char *cp;
139 register struct mbuf *m0;
140
141 MINDEX(len, m, k);
142 cp = mtod(m, u_char *) + k;
143 if (len - k >= 2) {
144 *err = 0;
145 return EXTRACT_SHORT(cp);
146 }
147 m0 = m->m_next;
148 if (m0 == 0)
149 goto bad;
150 *err = 0;
151 return (cp[0] << 8) | mtod(m0, u_char *)[0];
152 bad:
153 *err = 1;
154 return 0;
155 }
156 #endif
157
158 /*
159 * Execute the filter program starting at pc on the packet p
160 * wirelen is the length of the original packet
161 * buflen is the amount of data present
162 */
163 u_int
164 bpf_filter(pc, p, wirelen, buflen)
165 register struct bpf_insn *pc;
166 register u_char *p;
167 u_int wirelen;
168 register u_int buflen;
169 {
170 register u_int32 A, X;
171 register int k;
172 int32 mem[BPF_MEMWORDS];
173
174 if (pc == 0)
175 /*
176 * No filter means accept all.
177 */
178 return (u_int)-1;
179 A = 0;
180 X = 0;
181 --pc;
182 while (1) {
183 ++pc;
184 switch (pc->code) {
185
186 default:
187 #ifdef KERNEL
188 return 0;
189 #else
190 abort();
191 #endif
192 case BPF_RET|BPF_K:
193 return (u_int)pc->k;
194
195 case BPF_RET|BPF_A:
196 return (u_int)A;
197
198 case BPF_LD|BPF_W|BPF_ABS:
199 k = pc->k;
200 if (k + sizeof(int32) > buflen) {
201 #ifdef KERNEL
202 int merr;
203
204 if (buflen != 0)
205 return 0;
206 A = m_xword((struct mbuf *)p, k, &merr);
207 if (merr != 0)
208 return 0;
209 continue;
210 #else
211 return 0;
212 #endif
213 }
214 A = EXTRACT_LONG(&p[k]);
215 continue;
216
217 case BPF_LD|BPF_H|BPF_ABS:
218 k = pc->k;
219 if (k + sizeof(short) > buflen) {
220 #ifdef KERNEL
221 int merr;
222
223 if (buflen != 0)
224 return 0;
225 A = m_xhalf((struct mbuf *)p, k, &merr);
226 continue;
227 #else
228 return 0;
229 #endif
230 }
231 A = EXTRACT_SHORT(&p[k]);
232 continue;
233
234 case BPF_LD|BPF_B|BPF_ABS:
235 k = pc->k;
236 if (k >= buflen) {
237 #ifdef KERNEL
238 register struct mbuf *m;
239 register int len;
240
241 if (buflen != 0)
242 return 0;
243 m = (struct mbuf *)p;
244 MINDEX(len, m, k);
245 A = mtod(m, u_char *)[k];
246 continue;
247 #else
248 return 0;
249 #endif
250 }
251 A = p[k];
252 continue;
253
254 case BPF_LD|BPF_W|BPF_LEN:
255 A = wirelen;
256 continue;
257
258 case BPF_LDX|BPF_W|BPF_LEN:
259 X = wirelen;
260 continue;
261
262 case BPF_LD|BPF_W|BPF_IND:
263 k = X + pc->k;
264 if (k + sizeof(int32) > buflen) {
265 #ifdef KERNEL
266 int merr;
267
268 if (buflen != 0)
269 return 0;
270 A = m_xword((struct mbuf *)p, k, &merr);
271 if (merr != 0)
272 return 0;
273 continue;
274 #else
275 return 0;
276 #endif
277 }
278 A = EXTRACT_LONG(&p[k]);
279 continue;
280
281 case BPF_LD|BPF_H|BPF_IND:
282 k = X + pc->k;
283 if (k + sizeof(short) > buflen) {
284 #ifdef KERNEL
285 int merr;
286
287 if (buflen != 0)
288 return 0;
289 A = m_xhalf((struct mbuf *)p, k, &merr);
290 if (merr != 0)
291 return 0;
292 continue;
293 #else
294 return 0;
295 #endif
296 }
297 A = EXTRACT_SHORT(&p[k]);
298 continue;
299
300 case BPF_LD|BPF_B|BPF_IND:
301 k = X + pc->k;
302 if (k >= buflen) {
303 #ifdef KERNEL
304 register struct mbuf *m;
305 register int len;
306
307 if (buflen != 0)
308 return 0;
309 m = (struct mbuf *)p;
310 MINDEX(len, m, k);
311 A = mtod(m, u_char *)[k];
312 continue;
313 #else
314 return 0;
315 #endif
316 }
317 A = p[k];
318 continue;
319
320 case BPF_LDX|BPF_MSH|BPF_B:
321 k = pc->k;
322 if (k >= buflen) {
323 #ifdef KERNEL
324 register struct mbuf *m;
325 register int len;
326
327 if (buflen != 0)
328 return 0;
329 m = (struct mbuf *)p;
330 MINDEX(len, m, k);
331 X = (mtod(m, char *)[k] & 0xf) << 2;
332 continue;
333 #else
334 return 0;
335 #endif
336 }
337 X = (p[pc->k] & 0xf) << 2;
338 continue;
339
340 case BPF_LD|BPF_IMM:
341 A = pc->k;
342 continue;
343
344 case BPF_LDX|BPF_IMM:
345 X = pc->k;
346 continue;
347
348 case BPF_LD|BPF_MEM:
349 A = mem[pc->k];
350 continue;
351
352 case BPF_LDX|BPF_MEM:
353 X = mem[pc->k];
354 continue;
355
356 case BPF_ST:
357 mem[pc->k] = A;
358 continue;
359
360 case BPF_STX:
361 mem[pc->k] = X;
362 continue;
363
364 case BPF_JMP|BPF_JA:
365 pc += pc->k;
366 continue;
367
368 case BPF_JMP|BPF_JGT|BPF_K:
369 pc += (A > pc->k) ? pc->jt : pc->jf;
370 continue;
371
372 case BPF_JMP|BPF_JGE|BPF_K:
373 pc += (A >= pc->k) ? pc->jt : pc->jf;
374 continue;
375
376 case BPF_JMP|BPF_JEQ|BPF_K:
377 pc += (A == pc->k) ? pc->jt : pc->jf;
378 continue;
379
380 case BPF_JMP|BPF_JSET|BPF_K:
381 pc += (A & pc->k) ? pc->jt : pc->jf;
382 continue;
383
384 case BPF_JMP|BPF_JGT|BPF_X:
385 pc += (A > X) ? pc->jt : pc->jf;
386 continue;
387
388 case BPF_JMP|BPF_JGE|BPF_X:
389 pc += (A >= X) ? pc->jt : pc->jf;
390 continue;
391
392 case BPF_JMP|BPF_JEQ|BPF_X:
393 pc += (A == X) ? pc->jt : pc->jf;
394 continue;
395
396 case BPF_JMP|BPF_JSET|BPF_X:
397 pc += (A & X) ? pc->jt : pc->jf;
398 continue;
399
400 case BPF_ALU|BPF_ADD|BPF_X:
401 A += X;
402 continue;
403
404 case BPF_ALU|BPF_SUB|BPF_X:
405 A -= X;
406 continue;
407
408 case BPF_ALU|BPF_MUL|BPF_X:
409 A *= X;
410 continue;
411
412 case BPF_ALU|BPF_DIV|BPF_X:
413 if (X == 0)
414 return 0;
415 A /= X;
416 continue;
417
418 case BPF_ALU|BPF_AND|BPF_X:
419 A &= X;
420 continue;
421
422 case BPF_ALU|BPF_OR|BPF_X:
423 A |= X;
424 continue;
425
426 case BPF_ALU|BPF_LSH|BPF_X:
427 A <<= X;
428 continue;
429
430 case BPF_ALU|BPF_RSH|BPF_X:
431 A >>= X;
432 continue;
433
434 case BPF_ALU|BPF_ADD|BPF_K:
435 A += pc->k;
436 continue;
437
438 case BPF_ALU|BPF_SUB|BPF_K:
439 A -= pc->k;
440 continue;
441
442 case BPF_ALU|BPF_MUL|BPF_K:
443 A *= pc->k;
444 continue;
445
446 case BPF_ALU|BPF_DIV|BPF_K:
447 A /= pc->k;
448 continue;
449
450 case BPF_ALU|BPF_AND|BPF_K:
451 A &= pc->k;
452 continue;
453
454 case BPF_ALU|BPF_OR|BPF_K:
455 A |= pc->k;
456 continue;
457
458 case BPF_ALU|BPF_LSH|BPF_K:
459 A <<= pc->k;
460 continue;
461
462 case BPF_ALU|BPF_RSH|BPF_K:
463 A >>= pc->k;
464 continue;
465
466 case BPF_ALU|BPF_NEG:
467 A = -A;
468 continue;
469
470 case BPF_MISC|BPF_TAX:
471 X = A;
472 continue;
473
474 case BPF_MISC|BPF_TXA:
475 A = X;
476 continue;
477 }
478 }
479 }
480
481 #ifdef KERNEL
482 /*
483 * Return true if the 'fcode' is a valid filter program.
484 * The constraints are that each jump be forward and to a valid
485 * code. The code must terminate with either an accept or reject.
486 * 'valid' is an array for use by the routine (it must be at least
487 * 'len' bytes long).
488 *
489 * The kernel needs to be able to verify an application's filter code.
490 * Otherwise, a bogus program could easily crash the system.
491 */
492 int
493 bpf_validate(f, len)
494 struct bpf_insn *f;
495 int len;
496 {
497 register int i;
498 register struct bpf_insn *p;
499
500 for (i = 0; i < len; ++i) {
501 /*
502 * Check that that jumps are forward, and within
503 * the code block.
504 */
505 p = &f[i];
506 if (BPF_CLASS(p->code) == BPF_JMP) {
507 register int from = i + 1;
508
509 if (BPF_OP(p->code) == BPF_JA) {
510 if (from + p->k >= (unsigned)len)
511 return 0;
512 }
513 else if (from + p->jt >= len || from + p->jf >= len)
514 return 0;
515 }
516 /*
517 * Check that memory operations use valid addresses.
518 */
519 if ((BPF_CLASS(p->code) == BPF_ST ||
520 (BPF_CLASS(p->code) == BPF_LD &&
521 (p->code & 0xe0) == BPF_MEM)) &&
522 (p->k >= BPF_MEMWORDS || p->k < 0))
523 return 0;
524 /*
525 * Check for constant division by 0.
526 */
527 if (p->code == (BPF_ALU|BPF_DIV|BPF_K) && p->k == 0)
528 return 0;
529 }
530 return BPF_CLASS(f[len - 1].code) == BPF_RET;
531 }
532 #endif
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