bpf_filter.c revision 1.2
1 /*- 2 * Copyright (c) 1990-1991 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 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 7.2 (Berkeley) 5/14/91 39 * 40 * static char rcsid[] = 41 * "@(#) $Header: /tank/opengrok/rsync2/NetBSD/src/sys/net/bpf_filter.c,v 1.2 1993/03/25 00:27:53 cgd Exp $ (LBL)"; 42 */ 43 #if !(defined(lint) || defined(KERNEL)) 44 static char rcsid[] = 45 "@(#) $Header: /tank/opengrok/rsync2/NetBSD/src/sys/net/bpf_filter.c,v 1.2 1993/03/25 00:27:53 cgd Exp $ (LBL)"; 46 #endif 47 48 #include <sys/param.h> 49 #include <sys/types.h> 50 #include <sys/time.h> 51 #include <net/bpf.h> 52 53 #ifdef sun 54 #include <netinet/in.h> 55 #endif 56 57 #if defined(sparc) || defined(mips) || defined(ibm032) 58 #define BPF_ALIGN 59 #endif 60 61 #ifndef BPF_ALIGN 62 #define EXTRACT_SHORT(p) ((u_short)ntohs(*(u_short *)p)) 63 #define EXTRACT_LONG(p) (ntohl(*(u_long *)p)) 64 #else 65 #define EXTRACT_SHORT(p)\ 66 ((u_short)\ 67 ((u_short)*((u_char *)p+0)<<8|\ 68 (u_short)*((u_char *)p+1)<<0)) 69 #define EXTRACT_LONG(p)\ 70 ((u_long)*((u_char *)p+0)<<24|\ 71 (u_long)*((u_char *)p+1)<<16|\ 72 (u_long)*((u_char *)p+2)<<8|\ 73 (u_long)*((u_char *)p+3)<<0) 74 #endif 75 76 #ifdef KERNEL 77 #include <sys/mbuf.h> 78 #define MINDEX(m, k) \ 79 { \ 80 register int len = m->m_len; \ 81 \ 82 while (k >= len) { \ 83 k -= len; \ 84 m = m->m_next; \ 85 if (m == 0) \ 86 return 0; \ 87 len = m->m_len; \ 88 } \ 89 } 90 91 static int 92 m_xword(m, k, err) 93 register struct mbuf *m; 94 register int k, *err; 95 { 96 register int len; 97 register u_char *cp, *np; 98 register struct mbuf *m0; 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 (cp[k] << 24) | (np[0] << 16) | (np[1] << 8) | np[2]; 122 123 case 2: 124 return (cp[k] << 24) | (cp[k + 1] << 16) | (np[0] << 8) | 125 np[1]; 126 127 default: 128 return (cp[k] << 24) | (cp[k + 1] << 16) | (cp[k + 2] << 8) | 129 np[0]; 130 } 131 bad: 132 *err = 1; 133 return 0; 134 } 135 136 static int 137 m_xhalf(m, k, err) 138 register struct mbuf *m; 139 register int k, *err; 140 { 141 register int len; 142 register u_char *cp; 143 register struct mbuf *m0; 144 145 len = m->m_len; 146 while (k >= len) { 147 k -= len; 148 m = m->m_next; 149 if (m == 0) 150 goto bad; 151 len = m->m_len; 152 } 153 cp = mtod(m, u_char *) + k; 154 if (len - k >= 2) { 155 *err = 0; 156 return EXTRACT_SHORT(cp); 157 } 158 m0 = m->m_next; 159 if (m0 == 0) 160 goto bad; 161 *err = 0; 162 return (cp[k] << 8) | mtod(m0, u_char *)[0]; 163 bad: 164 *err = 1; 165 return 0; 166 } 167 #endif 168 169 /* 170 * Execute the filter program starting at pc on the packet p 171 * wirelen is the length of the original packet 172 * buflen is the amount of data present 173 */ 174 u_int 175 bpf_filter(pc, p, wirelen, buflen) 176 register struct bpf_insn *pc; 177 register u_char *p; 178 u_int wirelen; 179 register u_int buflen; 180 { 181 register u_long A, X; 182 register int k; 183 long mem[BPF_MEMWORDS]; 184 185 if (pc == 0) 186 /* 187 * No filter means accept all. 188 */ 189 return (u_int)-1; 190 #ifdef lint 191 A = 0; 192 X = 0; 193 #endif 194 --pc; 195 while (1) { 196 ++pc; 197 switch (pc->code) { 198 199 default: 200 #ifdef KERNEL 201 return 0; 202 #else 203 abort(); 204 #endif 205 case BPF_RET|BPF_K: 206 return (u_int)pc->k; 207 208 case BPF_RET|BPF_A: 209 return (u_int)A; 210 211 case BPF_LD|BPF_W|BPF_ABS: 212 k = pc->k; 213 if (k + sizeof(long) > buflen) { 214 #ifdef KERNEL 215 int merr; 216 217 if (buflen != 0) 218 return 0; 219 A = m_xword((struct mbuf *)p, k, &merr); 220 if (merr != 0) 221 return 0; 222 continue; 223 #else 224 return 0; 225 #endif 226 } 227 #ifdef BPF_ALIGN 228 if (((int)(p + k) & 3) != 0) 229 A = EXTRACT_LONG(&p[k]); 230 else 231 #endif 232 A = ntohl(*(long *)(p + k)); 233 continue; 234 235 case BPF_LD|BPF_H|BPF_ABS: 236 k = pc->k; 237 if (k + sizeof(short) > buflen) { 238 #ifdef KERNEL 239 int merr; 240 241 if (buflen != 0) 242 return 0; 243 A = m_xhalf((struct mbuf *)p, k, &merr); 244 continue; 245 #else 246 return 0; 247 #endif 248 } 249 A = EXTRACT_SHORT(&p[k]); 250 continue; 251 252 case BPF_LD|BPF_B|BPF_ABS: 253 k = pc->k; 254 if (k >= buflen) { 255 #ifdef KERNEL 256 register struct mbuf *m; 257 258 if (buflen != 0) 259 return 0; 260 m = (struct mbuf *)p; 261 MINDEX(m, k); 262 A = mtod(m, u_char *)[k]; 263 continue; 264 #else 265 return 0; 266 #endif 267 } 268 A = p[k]; 269 continue; 270 271 case BPF_LD|BPF_W|BPF_LEN: 272 A = wirelen; 273 continue; 274 275 case BPF_LDX|BPF_W|BPF_LEN: 276 X = wirelen; 277 continue; 278 279 case BPF_LD|BPF_W|BPF_IND: 280 k = X + pc->k; 281 if (k + sizeof(long) > buflen) { 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 (((int)(p + k) & 3) != 0) 297 A = EXTRACT_LONG(&p[k]); 298 else 299 #endif 300 A = ntohl(*(long *)(p + k)); 301 continue; 302 303 case BPF_LD|BPF_H|BPF_IND: 304 k = X + pc->k; 305 if (k + sizeof(short) > buflen) { 306 #ifdef KERNEL 307 int merr; 308 309 if (buflen != 0) 310 return 0; 311 A = m_xhalf((struct mbuf *)p, k, &merr); 312 if (merr != 0) 313 return 0; 314 continue; 315 #else 316 return 0; 317 #endif 318 } 319 A = EXTRACT_SHORT(&p[k]); 320 continue; 321 322 case BPF_LD|BPF_B|BPF_IND: 323 k = X + pc->k; 324 if (k >= buflen) { 325 #ifdef KERNEL 326 register struct mbuf *m; 327 328 if (buflen != 0) 329 return 0; 330 m = (struct mbuf *)p; 331 MINDEX(m, k); 332 A = mtod(m, char *)[k]; 333 continue; 334 #else 335 return 0; 336 #endif 337 } 338 A = p[k]; 339 continue; 340 341 case BPF_LDX|BPF_MSH|BPF_B: 342 k = pc->k; 343 if (k >= buflen) { 344 #ifdef KERNEL 345 register struct mbuf *m; 346 347 if (buflen != 0) 348 return 0; 349 m = (struct mbuf *)p; 350 MINDEX(m, k); 351 X = (mtod(m, char *)[k] & 0xf) << 2; 352 continue; 353 #else 354 return 0; 355 #endif 356 } 357 X = (p[pc->k] & 0xf) << 2; 358 continue; 359 360 case BPF_LD|BPF_IMM: 361 A = pc->k; 362 continue; 363 364 case BPF_LDX|BPF_IMM: 365 X = pc->k; 366 continue; 367 368 case BPF_LD|BPF_MEM: 369 A = mem[pc->k]; 370 continue; 371 372 case BPF_LDX|BPF_MEM: 373 X = mem[pc->k]; 374 continue; 375 376 case BPF_ST: 377 mem[pc->k] = A; 378 continue; 379 380 case BPF_STX: 381 mem[pc->k] = X; 382 continue; 383 384 case BPF_JMP|BPF_JA: 385 pc += pc->k; 386 continue; 387 388 case BPF_JMP|BPF_JGT|BPF_K: 389 pc += (A > pc->k) ? pc->jt : pc->jf; 390 continue; 391 392 case BPF_JMP|BPF_JGE|BPF_K: 393 pc += (A >= pc->k) ? pc->jt : pc->jf; 394 continue; 395 396 case BPF_JMP|BPF_JEQ|BPF_K: 397 pc += (A == pc->k) ? pc->jt : pc->jf; 398 continue; 399 400 case BPF_JMP|BPF_JSET|BPF_K: 401 pc += (A & pc->k) ? pc->jt : pc->jf; 402 continue; 403 404 case BPF_JMP|BPF_JGT|BPF_X: 405 pc += (A > X) ? pc->jt : pc->jf; 406 continue; 407 408 case BPF_JMP|BPF_JGE|BPF_X: 409 pc += (A >= X) ? pc->jt : pc->jf; 410 continue; 411 412 case BPF_JMP|BPF_JEQ|BPF_X: 413 pc += (A == X) ? pc->jt : pc->jf; 414 continue; 415 416 case BPF_JMP|BPF_JSET|BPF_X: 417 pc += (A & X) ? pc->jt : pc->jf; 418 continue; 419 420 case BPF_ALU|BPF_ADD|BPF_X: 421 A += X; 422 continue; 423 424 case BPF_ALU|BPF_SUB|BPF_X: 425 A -= X; 426 continue; 427 428 case BPF_ALU|BPF_MUL|BPF_X: 429 A *= X; 430 continue; 431 432 case BPF_ALU|BPF_DIV|BPF_X: 433 if (X == 0) 434 return 0; 435 A /= X; 436 continue; 437 438 case BPF_ALU|BPF_AND|BPF_X: 439 A &= X; 440 continue; 441 442 case BPF_ALU|BPF_OR|BPF_X: 443 A |= X; 444 continue; 445 446 case BPF_ALU|BPF_LSH|BPF_X: 447 A <<= X; 448 continue; 449 450 case BPF_ALU|BPF_RSH|BPF_X: 451 A >>= X; 452 continue; 453 454 case BPF_ALU|BPF_ADD|BPF_K: 455 A += pc->k; 456 continue; 457 458 case BPF_ALU|BPF_SUB|BPF_K: 459 A -= pc->k; 460 continue; 461 462 case BPF_ALU|BPF_MUL|BPF_K: 463 A *= pc->k; 464 continue; 465 466 case BPF_ALU|BPF_DIV|BPF_K: 467 A /= pc->k; 468 continue; 469 470 case BPF_ALU|BPF_AND|BPF_K: 471 A &= pc->k; 472 continue; 473 474 case BPF_ALU|BPF_OR|BPF_K: 475 A |= pc->k; 476 continue; 477 478 case BPF_ALU|BPF_LSH|BPF_K: 479 A <<= pc->k; 480 continue; 481 482 case BPF_ALU|BPF_RSH|BPF_K: 483 A >>= pc->k; 484 continue; 485 486 case BPF_ALU|BPF_NEG: 487 A = -A; 488 continue; 489 490 case BPF_MISC|BPF_TAX: 491 X = A; 492 continue; 493 494 case BPF_MISC|BPF_TXA: 495 A = X; 496 continue; 497 } 498 } 499 } 500 501 #ifdef KERNEL 502 /* 503 * Return true if the 'fcode' is a valid filter program. 504 * The constraints are that each jump be forward and to a valid 505 * code. The code must terminate with either an accept or reject. 506 * 'valid' is an array for use by the routine (it must be at least 507 * 'len' bytes long). 508 * 509 * The kernel needs to be able to verify an application's filter code. 510 * Otherwise, a bogus program could easily crash the system. 511 */ 512 int 513 bpf_validate(f, len) 514 struct bpf_insn *f; 515 int len; 516 { 517 register int i; 518 register struct bpf_insn *p; 519 520 for (i = 0; i < len; ++i) { 521 /* 522 * Check that that jumps are forward, and within 523 * the code block. 524 */ 525 p = &f[i]; 526 if (BPF_CLASS(p->code) == BPF_JMP) { 527 register int from = i + 1; 528 529 if (BPF_OP(p->code) == BPF_JA) { 530 if (from + p->k >= len) 531 return 0; 532 } 533 else if (from + p->jt >= len || from + p->jf >= len) 534 return 0; 535 } 536 /* 537 * Check that memory operations use valid addresses. 538 */ 539 if ((BPF_CLASS(p->code) == BPF_ST || 540 (BPF_CLASS(p->code) == BPF_LD && 541 (p->code & 0xe0) == BPF_MEM)) && 542 (p->k >= BPF_MEMWORDS || p->k < 0)) 543 return 0; 544 /* 545 * Check for constant division by 0. 546 */ 547 if (p->code == (BPF_ALU|BPF_DIV|BPF_K) && p->k == 0) 548 return 0; 549 } 550 return BPF_CLASS(f[len - 1].code) == BPF_RET; 551 } 552 #endif 553
Indexes created Tue Sep 30 10:09:55 GMT 2025