bpf_filter.c revision 1.1.1.1
1 /*- 2 * Copyright (c) 1991 The Regents of the University of California. 3 * 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 of Lawrence Berkeley Laboratory. 8 * 9 * Redistribution and use in source and binary forms, with or without 10 * modification, are permitted provided that the following conditions 11 * are met: 12 * 1. Redistributions of source code must retain the above copyright 13 * notice, this list of conditions and the following disclaimer. 14 * 2. Redistributions in binary form must reproduce the above copyright 15 * notice, this list of conditions and the following disclaimer in the 16 * documentation and/or other materials provided with the distribution. 17 * 3. All advertising materials mentioning features or use of this software 18 * must display the following acknowledgement: 19 * This product includes software developed by the University of 20 * California, Berkeley and its contributors. 21 * 4. Neither the name of the University nor the names of its contributors 22 * may be used to endorse or promote products derived from this software 23 * without specific prior written permission. 24 * 25 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 26 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 27 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 28 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 29 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 30 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 31 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 32 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 33 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 34 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 35 * SUCH DAMAGE. 36 * 37 * @(#)bpf_filter.c 7.2 (Berkeley) 5/14/91 38 * 39 * static char rcsid[] = 40 * "@(#) $Header: /tank/opengrok/rsync2/NetBSD/src/sys/net/bpf_filter.c,v 1.1.1.1 1993/03/21 09:45:37 cgd Exp $ (LBL)"; 41 */ 42 43 #include <sys/param.h> 44 #include <sys/types.h> 45 #include <sys/time.h> 46 #include <net/bpf.h> 47 48 #ifdef sun 49 #include <netinet/in.h> 50 #endif 51 52 #if defined(sparc) || defined(mips) 53 #define ALIGN 54 #endif 55 56 #ifndef ALIGN 57 #define EXTRACT_SHORT(p) (ntohs(*(u_short *)p)) 58 #define EXTRACT_LONG(p) (ntohl(*(u_long *)p)) 59 #else 60 #define EXTRACT_SHORT(p)\ 61 ((u_short)\ 62 (*((u_char *)(p)+0)<<8|\ 63 *((u_char *)(p)+1)<<0)) 64 #define EXTRACT_LONG(p)\ 65 (*((u_char *)(p)+0)<<24|\ 66 *((u_char *)(p)+1)<<16|\ 67 *((u_char *)(p)+2)<<8|\ 68 *((u_char *)(p)+3)<<0) 69 #endif 70 71 #ifdef KERNEL 72 #include <sys/mbuf.h> 73 #define MINDEX(m, k) \ 74 { \ 75 register int len = m->m_len; \ 76 \ 77 while (k >= len) { \ 78 k -= len; \ 79 m = m->m_next; \ 80 if (m == 0) \ 81 return 0; \ 82 len = m->m_len; \ 83 } \ 84 } 85 86 static int 87 m_xword(m, k, err) 88 register struct mbuf *m; 89 register int k, *err; 90 { 91 register int len; 92 register u_char *cp, *np; 93 register struct mbuf *m0; 94 95 len = m->m_len; 96 while (k >= len) { 97 k -= len; 98 m = m->m_next; 99 if (m == 0) 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; 109 if (m0 == 0 || m0->m_len + len - k < 4) 110 goto bad; 111 *err = 0; 112 np = mtod(m0, u_char *); 113 switch (len - k) { 114 115 case 1: 116 return (cp[k] << 24) | (np[0] << 16) | (np[1] << 8) | np[2]; 117 118 case 2: 119 return (cp[k] << 24) | (cp[k + 1] << 16) | (np[0] << 8) | 120 np[1]; 121 122 default: 123 return (cp[k] << 24) | (cp[k + 1] << 16) | (cp[k + 2] << 8) | 124 np[0]; 125 } 126 bad: 127 *err = 1; 128 return 0; 129 } 130 131 static int 132 m_xhalf(m, k, err) 133 register struct mbuf *m; 134 register int k, *err; 135 { 136 register int len; 137 register u_char *cp, *np; 138 register struct mbuf *m0; 139 140 len = m->m_len; 141 while (k >= len) { 142 k -= len; 143 m = m->m_next; 144 if (m == 0) 145 goto bad; 146 len = m->m_len; 147 } 148 cp = mtod(m, u_char *) + k; 149 if (len - k >= 2) { 150 *err = 0; 151 return EXTRACT_SHORT(cp); 152 } 153 m0 = m->m_next; 154 if (m0 == 0) 155 goto bad; 156 *err = 0; 157 return (cp[k] << 8) | mtod(m0, u_char *)[0]; 158 bad: 159 *err = 1; 160 return 0; 161 } 162 163 164 #endif 165 166 /* 167 * Execute the filter program starting at pc on the packet p 168 * wirelen is the length of the original packet 169 * buflen is the amount of data present 170 */ 171 u_int 172 bpf_filter(pc, p, wirelen, buflen) 173 register struct bpf_insn *pc; 174 register u_char *p; 175 u_int wirelen; 176 register u_int buflen; 177 { 178 register long A, X; 179 register int k; 180 long mem[BPF_MEMWORDS]; 181 182 if (pc == 0) 183 /* 184 * No filter means accept all. 185 */ 186 return (u_int)-1; 187 #ifdef lint 188 A = 0; 189 X = 0; 190 #endif 191 --pc; 192 while (1) { 193 ++pc; 194 switch (pc->code) { 195 196 default: 197 #ifdef KERNEL 198 return 0; 199 #else 200 abort(); 201 #endif 202 case BPF_RET|BPF_K: 203 return (u_int)pc->k; 204 205 case BPF_RET|BPF_A: 206 return (u_int)A; 207 208 case BPF_LD|BPF_W|BPF_ABS: 209 k = pc->k; 210 if (k + sizeof(long) > buflen) { 211 #ifdef KERNEL 212 int merr; 213 214 if (buflen != 0) 215 return 0; 216 A = m_xword((struct mbuf *)p, k, &merr); 217 if (merr != 0) 218 return 0; 219 continue; 220 #else 221 return 0; 222 #endif 223 } 224 #ifdef ALIGN 225 if (((int)(p + k) & 3) != 0) 226 A = EXTRACT_LONG(&p[k]); 227 else 228 #endif 229 A = *(long *)(p + k); 230 continue; 231 232 case BPF_LD|BPF_H|BPF_ABS: 233 k = pc->k; 234 if (k + sizeof(short) > buflen) { 235 #ifdef KERNEL 236 int merr; 237 238 if (buflen != 0) 239 return 0; 240 A = m_xhalf((struct mbuf *)p, k, &merr); 241 continue; 242 #else 243 return 0; 244 #endif 245 } 246 A = EXTRACT_SHORT(&p[k]); 247 continue; 248 249 case BPF_LD|BPF_B|BPF_ABS: 250 k = pc->k; 251 if (k >= buflen) { 252 #ifdef KERNEL 253 register struct mbuf *m; 254 255 if (buflen != 0) 256 return 0; 257 m = (struct mbuf *)p; 258 MINDEX(m, k); 259 A = mtod(m, u_char *)[k]; 260 continue; 261 #else 262 return 0; 263 #endif 264 } 265 A = p[k]; 266 continue; 267 268 case BPF_LD|BPF_W|BPF_LEN: 269 A = wirelen; 270 continue; 271 272 case BPF_LDX|BPF_W|BPF_LEN: 273 X = wirelen; 274 continue; 275 276 case BPF_LD|BPF_W|BPF_IND: 277 k = X + pc->k; 278 if (k + sizeof(long) > buflen) { 279 #ifdef KERNEL 280 int merr; 281 282 if (buflen != 0) 283 return 0; 284 A = m_xword((struct mbuf *)p, k, &merr); 285 if (merr != 0) 286 return 0; 287 continue; 288 #else 289 return 0; 290 #endif 291 } 292 #ifdef ALIGN 293 if (((int)(p + k) & 3) != 0) 294 A = EXTRACT_LONG(&p[k]); 295 else 296 #endif 297 A = *(long *)(p + k); 298 continue; 299 300 case BPF_LD|BPF_H|BPF_IND: 301 k = X + pc->k; 302 if (k + sizeof(short) > buflen) { 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 (k >= buflen) { 322 #ifdef KERNEL 323 register struct mbuf *m; 324 325 if (buflen != 0) 326 return 0; 327 m = (struct mbuf *)p; 328 MINDEX(m, k); 329 A = mtod(m, char *)[k]; 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 342 register struct mbuf *m; 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. 501 * The constraints are that each jump be forward and to a valid 502 * code. The code must terminate with either an accept or reject. 503 * 'valid' is an array for use by the routine (it must be at least 504 * 'len' bytes long). 505 * 506 * The kernel needs to be able to verify an application's filter code. 507 * Otherwise, a bogus program could easily crash the system. 508 */ 509 int 510 bpf_validate(f, len) 511 struct bpf_insn *f; 512 int len; 513 { 514 register int i; 515 register struct bpf_insn *p; 516 517 for (i = 0; i < len; ++i) { 518 /* 519 * Check that that jumps are forward, and within 520 * the code block. 521 */ 522 p = &f[i]; 523 if (BPF_CLASS(p->code) == BPF_JMP) { 524 register int from = i + 1; 525 526 if (BPF_OP(p->code) == BPF_JA) { 527 if (from + p->k >= len) 528 return 0; 529 } 530 else if (from + p->jt >= len || from + p->jf >= len) 531 return 0; 532 } 533 /* 534 * Check that memory operations use valid addresses. 535 */ 536 if ((BPF_CLASS(p->code) == BPF_ST || 537 (BPF_CLASS(p->code) == BPF_LD && 538 (p->code & 0xe0) == BPF_MEM)) && 539 (p->k >= BPF_MEMWORDS || p->k < 0)) 540 return 0; 541 /* 542 * Check for constant division by 0. 543 */ 544 if (p->code == BPF_ALU|BPF_DIV|BPF_K && p->k == 0) 545 return; 546 } 547 return BPF_CLASS(f[len - 1].code) == BPF_RET; 548 } 549 #endif 550
Indexes created Tue Sep 30 07:10:03 GMT 2025