Add missing ';'.
[dragonfly.git] / sys / net / bpf_filter.c
CommitLineData
984263bc
MD
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 $
3653973d 41 * $DragonFly: src/sys/net/bpf_filter.c,v 1.9 2008/01/02 11:22:03 sephe Exp $
984263bc
MD
42 */
43
44#include <sys/param.h>
45
20df2adc 46#if defined(sparc) || defined(mips) || defined(ibm032)
984263bc
MD
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 } \
984263bc
MD
81}
82
158abb01
RG
83static u_int16_t m_xhalf (struct mbuf *m, bpf_u_int32 k, int *err);
84static u_int32_t m_xword (struct mbuf *m, bpf_u_int32 k, int *err);
984263bc
MD
85
86static u_int32_t
7c1ae3b3 87m_xword(struct mbuf *m, bpf_u_int32 k, int *err)
984263bc 88{
82ed7fc2
RG
89 size_t len;
90 u_char *cp, *np;
91 struct mbuf *m0;
984263bc
MD
92
93 len = m->m_len;
94 while (k >= len) {
95 k -= len;
96 m = m->m_next;
97 if (m == 0)
98 goto bad;
99 len = m->m_len;
100 }
101 cp = mtod(m, u_char *) + k;
102 if (len - k >= 4) {
103 *err = 0;
104 return EXTRACT_LONG(cp);
105 }
106 m0 = m->m_next;
107 if (m0 == 0 || m0->m_len + len - k < 4)
108 goto bad;
109 *err = 0;
110 np = mtod(m0, u_char *);
111 switch (len - k) {
112
113 case 1:
114 return
115 ((u_int32_t)cp[0] << 24) |
116 ((u_int32_t)np[0] << 16) |
117 ((u_int32_t)np[1] << 8) |
118 (u_int32_t)np[2];
119
120 case 2:
121 return
122 ((u_int32_t)cp[0] << 24) |
123 ((u_int32_t)cp[1] << 16) |
124 ((u_int32_t)np[0] << 8) |
125 (u_int32_t)np[1];
126
127 default:
128 return
129 ((u_int32_t)cp[0] << 24) |
130 ((u_int32_t)cp[1] << 16) |
131 ((u_int32_t)cp[2] << 8) |
132 (u_int32_t)np[0];
133 }
134 bad:
135 *err = 1;
136 return 0;
137}
138
139static u_int16_t
7c1ae3b3 140m_xhalf(struct mbuf *m, bpf_u_int32 k, int *err)
984263bc 141{
82ed7fc2
RG
142 size_t len;
143 u_char *cp;
144 struct mbuf *m0;
984263bc
MD
145
146 len = m->m_len;
147 while (k >= len) {
148 k -= len;
149 m = m->m_next;
150 if (m == 0)
151 goto bad;
152 len = m->m_len;
153 }
154 cp = mtod(m, u_char *) + k;
155 if (len - k >= 2) {
156 *err = 0;
157 return EXTRACT_SHORT(cp);
158 }
159 m0 = m->m_next;
160 if (m0 == 0)
161 goto bad;
162 *err = 0;
163 return (cp[0] << 8) | mtod(m0, u_char *)[0];
164 bad:
165 *err = 1;
166 return 0;
167}
168#endif
169
170/*
171 * Execute the filter program starting at pc on the packet p
172 * wirelen is the length of the original packet
173 * buflen is the amount of data present
174 */
175u_int
7c1ae3b3 176bpf_filter(const struct bpf_insn *pc, u_char *p, u_int wirelen, u_int buflen)
984263bc 177{
82ed7fc2
RG
178 u_int32_t A = 0, X = 0;
179 bpf_u_int32 k;
984263bc
MD
180 int32_t mem[BPF_MEMWORDS];
181
7c1ae3b3 182 if (pc == 0) {
984263bc
MD
183 /*
184 * No filter means accept all.
185 */
186 return (u_int)-1;
7c1ae3b3 187 }
984263bc
MD
188
189 --pc;
190 while (1) {
191 ++pc;
192 switch (pc->code) {
193
194 default:
195#ifdef _KERNEL
196 return 0;
197#else
198 abort();
199#endif
200 case BPF_RET|BPF_K:
201 return (u_int)pc->k;
202
203 case BPF_RET|BPF_A:
204 return (u_int)A;
205
206 case BPF_LD|BPF_W|BPF_ABS:
207 k = pc->k;
208 if (k > buflen || sizeof(int32_t) > buflen - k) {
209#ifdef _KERNEL
210 int merr;
211
212 if (buflen != 0)
213 return 0;
214 A = m_xword((struct mbuf *)p, k, &merr);
215 if (merr != 0)
216 return 0;
217 continue;
218#else
219 return 0;
220#endif
221 }
222#ifdef BPF_ALIGN
223 if (((intptr_t)(p + k) & 3) != 0)
224 A = EXTRACT_LONG(&p[k]);
225 else
226#endif
227 A = ntohl(*(int32_t *)(p + k));
228 continue;
229
230 case BPF_LD|BPF_H|BPF_ABS:
231 k = pc->k;
232 if (k > buflen || sizeof(int16_t) > buflen - k) {
233#ifdef _KERNEL
234 int merr;
235
236 if (buflen != 0)
237 return 0;
238 A = m_xhalf((struct mbuf *)p, k, &merr);
239 continue;
240#else
241 return 0;
242#endif
243 }
244 A = EXTRACT_SHORT(&p[k]);
245 continue;
246
247 case BPF_LD|BPF_B|BPF_ABS:
248 k = pc->k;
249 if (k >= buflen) {
250#ifdef _KERNEL
82ed7fc2 251 struct mbuf *m;
984263bc
MD
252
253 if (buflen != 0)
254 return 0;
255 m = (struct mbuf *)p;
256 MINDEX(m, k);
257 A = mtod(m, u_char *)[k];
258 continue;
259#else
260 return 0;
261#endif
262 }
263 A = p[k];
264 continue;
265
266 case BPF_LD|BPF_W|BPF_LEN:
267 A = wirelen;
268 continue;
269
270 case BPF_LDX|BPF_W|BPF_LEN:
271 X = wirelen;
272 continue;
273
274 case BPF_LD|BPF_W|BPF_IND:
275 k = X + pc->k;
276 if (pc->k > buflen || X > buflen - pc->k ||
277 sizeof(int32_t) > buflen - k) {
278#ifdef _KERNEL
279 int merr;
280
281 if (buflen != 0)
282 return 0;
283 A = m_xword((struct mbuf *)p, k, &merr);
284 if (merr != 0)
285 return 0;
286 continue;
287#else
288 return 0;
289#endif
290 }
291#ifdef BPF_ALIGN
292 if (((intptr_t)(p + k) & 3) != 0)
293 A = EXTRACT_LONG(&p[k]);
294 else
295#endif
296 A = ntohl(*(int32_t *)(p + k));
297 continue;
298
299 case BPF_LD|BPF_H|BPF_IND:
300 k = X + pc->k;
301 if (X > buflen || pc->k > buflen - X ||
302 sizeof(int16_t) > buflen - k) {
303#ifdef _KERNEL
304 int merr;
305
306 if (buflen != 0)
307 return 0;
308 A = m_xhalf((struct mbuf *)p, k, &merr);
309 if (merr != 0)
310 return 0;
311 continue;
312#else
313 return 0;
314#endif
315 }
316 A = EXTRACT_SHORT(&p[k]);
317 continue;
318
319 case BPF_LD|BPF_B|BPF_IND:
320 k = X + pc->k;
321 if (pc->k >= buflen || X >= buflen - pc->k) {
322#ifdef _KERNEL
82ed7fc2 323 struct mbuf *m;
984263bc
MD
324
325 if (buflen != 0)
326 return 0;
327 m = (struct mbuf *)p;
328 MINDEX(m, k);
3653973d 329 A = mtod(m, u_char *)[k];
984263bc
MD
330 continue;
331#else
332 return 0;
333#endif
334 }
335 A = p[k];
336 continue;
337
338 case BPF_LDX|BPF_MSH|BPF_B:
339 k = pc->k;
340 if (k >= buflen) {
341#ifdef _KERNEL
82ed7fc2 342 struct mbuf *m;
984263bc
MD
343
344 if (buflen != 0)
345 return 0;
346 m = (struct mbuf *)p;
347 MINDEX(m, k);
348 X = (mtod(m, char *)[k] & 0xf) << 2;
349 continue;
350#else
351 return 0;
352#endif
353 }
354 X = (p[pc->k] & 0xf) << 2;
355 continue;
356
357 case BPF_LD|BPF_IMM:
358 A = pc->k;
359 continue;
360
361 case BPF_LDX|BPF_IMM:
362 X = pc->k;
363 continue;
364
365 case BPF_LD|BPF_MEM:
366 A = mem[pc->k];
367 continue;
368
369 case BPF_LDX|BPF_MEM:
370 X = mem[pc->k];
371 continue;
372
373 case BPF_ST:
374 mem[pc->k] = A;
375 continue;
376
377 case BPF_STX:
378 mem[pc->k] = X;
379 continue;
380
381 case BPF_JMP|BPF_JA:
382 pc += pc->k;
383 continue;
384
385 case BPF_JMP|BPF_JGT|BPF_K:
386 pc += (A > pc->k) ? pc->jt : pc->jf;
387 continue;
388
389 case BPF_JMP|BPF_JGE|BPF_K:
390 pc += (A >= pc->k) ? pc->jt : pc->jf;
391 continue;
392
393 case BPF_JMP|BPF_JEQ|BPF_K:
394 pc += (A == pc->k) ? pc->jt : pc->jf;
395 continue;
396
397 case BPF_JMP|BPF_JSET|BPF_K:
398 pc += (A & pc->k) ? pc->jt : pc->jf;
399 continue;
400
401 case BPF_JMP|BPF_JGT|BPF_X:
402 pc += (A > X) ? pc->jt : pc->jf;
403 continue;
404
405 case BPF_JMP|BPF_JGE|BPF_X:
406 pc += (A >= X) ? pc->jt : pc->jf;
407 continue;
408
409 case BPF_JMP|BPF_JEQ|BPF_X:
410 pc += (A == X) ? pc->jt : pc->jf;
411 continue;
412
413 case BPF_JMP|BPF_JSET|BPF_X:
414 pc += (A & X) ? pc->jt : pc->jf;
415 continue;
416
417 case BPF_ALU|BPF_ADD|BPF_X:
418 A += X;
419 continue;
420
421 case BPF_ALU|BPF_SUB|BPF_X:
422 A -= X;
423 continue;
424
425 case BPF_ALU|BPF_MUL|BPF_X:
426 A *= X;
427 continue;
428
429 case BPF_ALU|BPF_DIV|BPF_X:
430 if (X == 0)
431 return 0;
432 A /= X;
433 continue;
434
435 case BPF_ALU|BPF_AND|BPF_X:
436 A &= X;
437 continue;
438
439 case BPF_ALU|BPF_OR|BPF_X:
440 A |= X;
441 continue;
442
443 case BPF_ALU|BPF_LSH|BPF_X:
444 A <<= X;
445 continue;
446
447 case BPF_ALU|BPF_RSH|BPF_X:
448 A >>= X;
449 continue;
450
451 case BPF_ALU|BPF_ADD|BPF_K:
452 A += pc->k;
453 continue;
454
455 case BPF_ALU|BPF_SUB|BPF_K:
456 A -= pc->k;
457 continue;
458
459 case BPF_ALU|BPF_MUL|BPF_K:
460 A *= pc->k;
461 continue;
462
463 case BPF_ALU|BPF_DIV|BPF_K:
464 A /= pc->k;
465 continue;
466
467 case BPF_ALU|BPF_AND|BPF_K:
468 A &= pc->k;
469 continue;
470
471 case BPF_ALU|BPF_OR|BPF_K:
472 A |= pc->k;
473 continue;
474
475 case BPF_ALU|BPF_LSH|BPF_K:
476 A <<= pc->k;
477 continue;
478
479 case BPF_ALU|BPF_RSH|BPF_K:
480 A >>= pc->k;
481 continue;
482
483 case BPF_ALU|BPF_NEG:
484 A = -A;
485 continue;
486
487 case BPF_MISC|BPF_TAX:
488 X = A;
489 continue;
490
491 case BPF_MISC|BPF_TXA:
492 A = X;
493 continue;
494 }
495 }
496}
497
498#ifdef _KERNEL
499/*
500 * Return true if the 'fcode' is a valid filter program.
20eb33a0
CP
501 * The constraints are that jump and memory accesses are within valid
502 * ranges, and that the code terminates with either an accept or reject.
984263bc
MD
503 *
504 * The kernel needs to be able to verify an application's filter code.
505 * Otherwise, a bogus program could easily crash the system.
506 */
507int
7c1ae3b3 508bpf_validate(const struct bpf_insn *f, int len)
984263bc 509{
82ed7fc2
RG
510 int i;
511 const struct bpf_insn *p;
984263bc
MD
512
513 for (i = 0; i < len; ++i) {
514 /*
20eb33a0 515 * Check that that jumps are within the code block.
984263bc
MD
516 */
517 p = &f[i];
518 if (BPF_CLASS(p->code) == BPF_JMP) {
82ed7fc2 519 int from = i + 1;
984263bc
MD
520
521 if (BPF_OP(p->code) == BPF_JA) {
522 if (from >= len || p->k >= len - from)
523 return 0;
524 }
525 else if (from >= len || p->jt >= len - from ||
526 p->jf >= len - from)
527 return 0;
528 }
529 /*
530 * Check that memory operations use valid addresses.
531 */
532 if ((BPF_CLASS(p->code) == BPF_ST ||
533 (BPF_CLASS(p->code) == BPF_LD &&
534 (p->code & 0xe0) == BPF_MEM)) &&
535 p->k >= BPF_MEMWORDS)
536 return 0;
537 /*
538 * Check for constant division by 0.
539 */
540 if (p->code == (BPF_ALU|BPF_DIV|BPF_K) && p->k == 0)
541 return 0;
542 }
543 return BPF_CLASS(f[len - 1].code) == BPF_RET;
544}
545#endif