The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 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 | |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 41 | #ifdef HAVE_CONFIG_H |
Haibo Huang | 165065a | 2018-07-23 17:26:52 -0700 | [diff] [blame] | 42 | #include <config.h> |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 43 | #endif |
| 44 | |
Haibo Huang | 165065a | 2018-07-23 17:26:52 -0700 | [diff] [blame] | 45 | #include <pcap/pcap-inttypes.h> |
| 46 | #include "pcap-types.h" |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 47 | |
Haibo Huang | 165065a | 2018-07-23 17:26:52 -0700 | [diff] [blame] | 48 | #ifndef _WIN32 |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 49 | #include <sys/param.h> |
| 50 | #include <sys/types.h> |
| 51 | #include <sys/time.h> |
Elliott Hughes | 965a4b5 | 2017-05-15 10:37:39 -0700 | [diff] [blame] | 52 | #endif /* _WIN32 */ |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 53 | |
JP Abgrall | 511eca3 | 2014-02-12 13:46:45 -0800 | [diff] [blame] | 54 | #include <pcap/bpf.h> |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 55 | |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 56 | #include <stdlib.h> |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 57 | |
| 58 | #define int32 bpf_int32 |
| 59 | #define u_int32 bpf_u_int32 |
| 60 | |
| 61 | #ifndef LBL_ALIGN |
| 62 | /* |
| 63 | * XXX - IA-64? If not, this probably won't work on Win64 IA-64 |
| 64 | * systems, unless LBL_ALIGN is defined elsewhere for them. |
| 65 | * XXX - SuperH? If not, this probably won't work on WinCE SuperH |
| 66 | * systems, unless LBL_ALIGN is defined elsewhere for them. |
| 67 | */ |
| 68 | #if defined(sparc) || defined(__sparc__) || defined(mips) || \ |
| 69 | defined(ibm032) || defined(__alpha) || defined(__hpux) || \ |
| 70 | defined(__arm__) |
| 71 | #define LBL_ALIGN |
| 72 | #endif |
| 73 | #endif |
| 74 | |
| 75 | #ifndef LBL_ALIGN |
Elliott Hughes | 965a4b5 | 2017-05-15 10:37:39 -0700 | [diff] [blame] | 76 | #ifndef _WIN32 |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 77 | #include <netinet/in.h> |
| 78 | #endif |
| 79 | |
| 80 | #define EXTRACT_SHORT(p) ((u_short)ntohs(*(u_short *)p)) |
| 81 | #define EXTRACT_LONG(p) (ntohl(*(u_int32 *)p)) |
| 82 | #else |
| 83 | #define EXTRACT_SHORT(p)\ |
| 84 | ((u_short)\ |
| 85 | ((u_short)*((u_char *)p+0)<<8|\ |
| 86 | (u_short)*((u_char *)p+1)<<0)) |
| 87 | #define EXTRACT_LONG(p)\ |
| 88 | ((u_int32)*((u_char *)p+0)<<24|\ |
| 89 | (u_int32)*((u_char *)p+1)<<16|\ |
| 90 | (u_int32)*((u_char *)p+2)<<8|\ |
| 91 | (u_int32)*((u_char *)p+3)<<0) |
| 92 | #endif |
| 93 | |
Elliott Hughes | d8845d7 | 2015-10-19 18:07:04 -0700 | [diff] [blame] | 94 | #ifdef __linux__ |
| 95 | #include <linux/types.h> |
| 96 | #include <linux/if_packet.h> |
| 97 | #include <linux/filter.h> |
| 98 | #endif |
| 99 | |
| 100 | enum { |
| 101 | BPF_S_ANC_NONE, |
| 102 | BPF_S_ANC_VLAN_TAG, |
| 103 | BPF_S_ANC_VLAN_TAG_PRESENT, |
| 104 | }; |
| 105 | |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 106 | /* |
| 107 | * Execute the filter program starting at pc on the packet p |
| 108 | * wirelen is the length of the original packet |
| 109 | * buflen is the amount of data present |
Elliott Hughes | d8845d7 | 2015-10-19 18:07:04 -0700 | [diff] [blame] | 110 | * aux_data is auxiliary data, currently used only when interpreting |
| 111 | * filters intended for the Linux kernel in cases where the kernel |
| 112 | * rejects the filter; it contains VLAN tag information |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 113 | * For the kernel, p is assumed to be a pointer to an mbuf if buflen is 0, |
| 114 | * in all other cases, p is a pointer to a buffer and buflen is its size. |
Elliott Hughes | 965a4b5 | 2017-05-15 10:37:39 -0700 | [diff] [blame] | 115 | * |
| 116 | * Thanks to Ani Sinha <ani@arista.com> for providing initial implementation |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 117 | */ |
| 118 | u_int |
Haibo Huang | 165065a | 2018-07-23 17:26:52 -0700 | [diff] [blame] | 119 | bpf_filter_with_aux_data(const struct bpf_insn *pc, const u_char *p, |
| 120 | u_int wirelen, u_int buflen, const struct bpf_aux_data *aux_data) |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 121 | { |
| 122 | register u_int32 A, X; |
Elliott Hughes | d8845d7 | 2015-10-19 18:07:04 -0700 | [diff] [blame] | 123 | register bpf_u_int32 k; |
| 124 | u_int32 mem[BPF_MEMWORDS]; |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 125 | |
| 126 | if (pc == 0) |
| 127 | /* |
| 128 | * No filter means accept all. |
| 129 | */ |
| 130 | return (u_int)-1; |
| 131 | A = 0; |
| 132 | X = 0; |
| 133 | --pc; |
Haibo Huang | 165065a | 2018-07-23 17:26:52 -0700 | [diff] [blame] | 134 | for (;;) { |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 135 | ++pc; |
| 136 | switch (pc->code) { |
| 137 | |
| 138 | default: |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 139 | abort(); |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 140 | case BPF_RET|BPF_K: |
| 141 | return (u_int)pc->k; |
| 142 | |
| 143 | case BPF_RET|BPF_A: |
| 144 | return (u_int)A; |
| 145 | |
| 146 | case BPF_LD|BPF_W|BPF_ABS: |
| 147 | k = pc->k; |
Elliott Hughes | d8845d7 | 2015-10-19 18:07:04 -0700 | [diff] [blame] | 148 | if (k > buflen || sizeof(int32_t) > buflen - k) { |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 149 | return 0; |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 150 | } |
| 151 | A = EXTRACT_LONG(&p[k]); |
| 152 | continue; |
| 153 | |
| 154 | case BPF_LD|BPF_H|BPF_ABS: |
| 155 | k = pc->k; |
Elliott Hughes | d8845d7 | 2015-10-19 18:07:04 -0700 | [diff] [blame] | 156 | if (k > buflen || sizeof(int16_t) > buflen - k) { |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 157 | return 0; |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 158 | } |
| 159 | A = EXTRACT_SHORT(&p[k]); |
| 160 | continue; |
| 161 | |
| 162 | case BPF_LD|BPF_B|BPF_ABS: |
Haibo Huang | 165065a | 2018-07-23 17:26:52 -0700 | [diff] [blame] | 163 | switch (pc->k) { |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 164 | |
Haibo Huang | 165065a | 2018-07-23 17:26:52 -0700 | [diff] [blame] | 165 | #if defined(SKF_AD_VLAN_TAG_PRESENT) |
| 166 | case SKF_AD_OFF + SKF_AD_VLAN_TAG: |
| 167 | if (!aux_data) |
| 168 | return 0; |
| 169 | A = aux_data->vlan_tag; |
| 170 | break; |
Elliott Hughes | d8845d7 | 2015-10-19 18:07:04 -0700 | [diff] [blame] | 171 | |
Haibo Huang | 165065a | 2018-07-23 17:26:52 -0700 | [diff] [blame] | 172 | case SKF_AD_OFF + SKF_AD_VLAN_TAG_PRESENT: |
| 173 | if (!aux_data) |
| 174 | return 0; |
| 175 | A = aux_data->vlan_tag_present; |
| 176 | break; |
Elliott Hughes | d8845d7 | 2015-10-19 18:07:04 -0700 | [diff] [blame] | 177 | #endif |
Haibo Huang | 165065a | 2018-07-23 17:26:52 -0700 | [diff] [blame] | 178 | default: |
| 179 | k = pc->k; |
| 180 | if (k >= buflen) { |
| 181 | return 0; |
| 182 | } |
| 183 | A = p[k]; |
| 184 | break; |
Elliott Hughes | d8845d7 | 2015-10-19 18:07:04 -0700 | [diff] [blame] | 185 | } |
Haibo Huang | 165065a | 2018-07-23 17:26:52 -0700 | [diff] [blame] | 186 | continue; |
| 187 | |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 188 | case BPF_LD|BPF_W|BPF_LEN: |
| 189 | A = wirelen; |
| 190 | continue; |
| 191 | |
| 192 | case BPF_LDX|BPF_W|BPF_LEN: |
| 193 | X = wirelen; |
| 194 | continue; |
| 195 | |
| 196 | case BPF_LD|BPF_W|BPF_IND: |
| 197 | k = X + pc->k; |
Elliott Hughes | d8845d7 | 2015-10-19 18:07:04 -0700 | [diff] [blame] | 198 | if (pc->k > buflen || X > buflen - pc->k || |
| 199 | sizeof(int32_t) > buflen - k) { |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 200 | return 0; |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 201 | } |
| 202 | A = EXTRACT_LONG(&p[k]); |
| 203 | continue; |
| 204 | |
| 205 | case BPF_LD|BPF_H|BPF_IND: |
| 206 | k = X + pc->k; |
Elliott Hughes | d8845d7 | 2015-10-19 18:07:04 -0700 | [diff] [blame] | 207 | if (X > buflen || pc->k > buflen - X || |
| 208 | sizeof(int16_t) > buflen - k) { |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 209 | return 0; |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 210 | } |
| 211 | A = EXTRACT_SHORT(&p[k]); |
| 212 | continue; |
| 213 | |
| 214 | case BPF_LD|BPF_B|BPF_IND: |
| 215 | k = X + pc->k; |
Elliott Hughes | d8845d7 | 2015-10-19 18:07:04 -0700 | [diff] [blame] | 216 | if (pc->k >= buflen || X >= buflen - pc->k) { |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 217 | return 0; |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 218 | } |
| 219 | A = p[k]; |
| 220 | continue; |
| 221 | |
| 222 | case BPF_LDX|BPF_MSH|BPF_B: |
| 223 | k = pc->k; |
| 224 | if (k >= buflen) { |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 225 | return 0; |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 226 | } |
| 227 | X = (p[pc->k] & 0xf) << 2; |
| 228 | continue; |
| 229 | |
| 230 | case BPF_LD|BPF_IMM: |
| 231 | A = pc->k; |
| 232 | continue; |
| 233 | |
| 234 | case BPF_LDX|BPF_IMM: |
| 235 | X = pc->k; |
| 236 | continue; |
| 237 | |
| 238 | case BPF_LD|BPF_MEM: |
| 239 | A = mem[pc->k]; |
| 240 | continue; |
| 241 | |
| 242 | case BPF_LDX|BPF_MEM: |
| 243 | X = mem[pc->k]; |
| 244 | continue; |
| 245 | |
| 246 | case BPF_ST: |
| 247 | mem[pc->k] = A; |
| 248 | continue; |
| 249 | |
| 250 | case BPF_STX: |
| 251 | mem[pc->k] = X; |
| 252 | continue; |
| 253 | |
| 254 | case BPF_JMP|BPF_JA: |
JP Abgrall | 511eca3 | 2014-02-12 13:46:45 -0800 | [diff] [blame] | 255 | /* |
| 256 | * XXX - we currently implement "ip6 protochain" |
| 257 | * with backward jumps, so sign-extend pc->k. |
| 258 | */ |
| 259 | pc += (bpf_int32)pc->k; |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 260 | continue; |
| 261 | |
| 262 | case BPF_JMP|BPF_JGT|BPF_K: |
| 263 | pc += (A > pc->k) ? pc->jt : pc->jf; |
| 264 | continue; |
| 265 | |
| 266 | case BPF_JMP|BPF_JGE|BPF_K: |
| 267 | pc += (A >= pc->k) ? pc->jt : pc->jf; |
| 268 | continue; |
| 269 | |
| 270 | case BPF_JMP|BPF_JEQ|BPF_K: |
| 271 | pc += (A == pc->k) ? pc->jt : pc->jf; |
| 272 | continue; |
| 273 | |
| 274 | case BPF_JMP|BPF_JSET|BPF_K: |
| 275 | pc += (A & pc->k) ? pc->jt : pc->jf; |
| 276 | continue; |
| 277 | |
| 278 | case BPF_JMP|BPF_JGT|BPF_X: |
| 279 | pc += (A > X) ? pc->jt : pc->jf; |
| 280 | continue; |
| 281 | |
| 282 | case BPF_JMP|BPF_JGE|BPF_X: |
| 283 | pc += (A >= X) ? pc->jt : pc->jf; |
| 284 | continue; |
| 285 | |
| 286 | case BPF_JMP|BPF_JEQ|BPF_X: |
| 287 | pc += (A == X) ? pc->jt : pc->jf; |
| 288 | continue; |
| 289 | |
| 290 | case BPF_JMP|BPF_JSET|BPF_X: |
| 291 | pc += (A & X) ? pc->jt : pc->jf; |
| 292 | continue; |
| 293 | |
| 294 | case BPF_ALU|BPF_ADD|BPF_X: |
| 295 | A += X; |
| 296 | continue; |
| 297 | |
| 298 | case BPF_ALU|BPF_SUB|BPF_X: |
| 299 | A -= X; |
| 300 | continue; |
| 301 | |
| 302 | case BPF_ALU|BPF_MUL|BPF_X: |
| 303 | A *= X; |
| 304 | continue; |
| 305 | |
| 306 | case BPF_ALU|BPF_DIV|BPF_X: |
| 307 | if (X == 0) |
| 308 | return 0; |
| 309 | A /= X; |
| 310 | continue; |
| 311 | |
Elliott Hughes | d8845d7 | 2015-10-19 18:07:04 -0700 | [diff] [blame] | 312 | case BPF_ALU|BPF_MOD|BPF_X: |
| 313 | if (X == 0) |
| 314 | return 0; |
| 315 | A %= X; |
| 316 | continue; |
| 317 | |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 318 | case BPF_ALU|BPF_AND|BPF_X: |
| 319 | A &= X; |
| 320 | continue; |
| 321 | |
| 322 | case BPF_ALU|BPF_OR|BPF_X: |
| 323 | A |= X; |
| 324 | continue; |
| 325 | |
Elliott Hughes | d8845d7 | 2015-10-19 18:07:04 -0700 | [diff] [blame] | 326 | case BPF_ALU|BPF_XOR|BPF_X: |
| 327 | A ^= X; |
| 328 | continue; |
| 329 | |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 330 | case BPF_ALU|BPF_LSH|BPF_X: |
| 331 | A <<= X; |
| 332 | continue; |
| 333 | |
| 334 | case BPF_ALU|BPF_RSH|BPF_X: |
| 335 | A >>= X; |
| 336 | continue; |
| 337 | |
| 338 | case BPF_ALU|BPF_ADD|BPF_K: |
| 339 | A += pc->k; |
| 340 | continue; |
| 341 | |
| 342 | case BPF_ALU|BPF_SUB|BPF_K: |
| 343 | A -= pc->k; |
| 344 | continue; |
| 345 | |
| 346 | case BPF_ALU|BPF_MUL|BPF_K: |
| 347 | A *= pc->k; |
| 348 | continue; |
| 349 | |
| 350 | case BPF_ALU|BPF_DIV|BPF_K: |
| 351 | A /= pc->k; |
| 352 | continue; |
| 353 | |
Elliott Hughes | d8845d7 | 2015-10-19 18:07:04 -0700 | [diff] [blame] | 354 | case BPF_ALU|BPF_MOD|BPF_K: |
| 355 | A %= pc->k; |
| 356 | continue; |
| 357 | |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 358 | case BPF_ALU|BPF_AND|BPF_K: |
| 359 | A &= pc->k; |
| 360 | continue; |
| 361 | |
| 362 | case BPF_ALU|BPF_OR|BPF_K: |
| 363 | A |= pc->k; |
| 364 | continue; |
| 365 | |
Elliott Hughes | d8845d7 | 2015-10-19 18:07:04 -0700 | [diff] [blame] | 366 | case BPF_ALU|BPF_XOR|BPF_K: |
| 367 | A ^= pc->k; |
| 368 | continue; |
| 369 | |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 370 | case BPF_ALU|BPF_LSH|BPF_K: |
| 371 | A <<= pc->k; |
| 372 | continue; |
| 373 | |
| 374 | case BPF_ALU|BPF_RSH|BPF_K: |
| 375 | A >>= pc->k; |
| 376 | continue; |
| 377 | |
| 378 | case BPF_ALU|BPF_NEG: |
Elliott Hughes | 965a4b5 | 2017-05-15 10:37:39 -0700 | [diff] [blame] | 379 | /* |
| 380 | * Most BPF arithmetic is unsigned, but negation |
| 381 | * can't be unsigned; throw some casts to |
| 382 | * specify what we're trying to do. |
| 383 | */ |
| 384 | A = (u_int32)(-(int32)A); |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 385 | continue; |
| 386 | |
| 387 | case BPF_MISC|BPF_TAX: |
| 388 | X = A; |
| 389 | continue; |
| 390 | |
| 391 | case BPF_MISC|BPF_TXA: |
| 392 | A = X; |
| 393 | continue; |
| 394 | } |
| 395 | } |
| 396 | } |
| 397 | |
Elliott Hughes | d8845d7 | 2015-10-19 18:07:04 -0700 | [diff] [blame] | 398 | u_int |
Haibo Huang | 165065a | 2018-07-23 17:26:52 -0700 | [diff] [blame] | 399 | bpf_filter(const struct bpf_insn *pc, const u_char *p, u_int wirelen, |
| 400 | u_int buflen) |
Elliott Hughes | d8845d7 | 2015-10-19 18:07:04 -0700 | [diff] [blame] | 401 | { |
| 402 | return bpf_filter_with_aux_data(pc, p, wirelen, buflen, NULL); |
| 403 | } |
| 404 | |
| 405 | |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 406 | /* |
| 407 | * Return true if the 'fcode' is a valid filter program. |
| 408 | * The constraints are that each jump be forward and to a valid |
JP Abgrall | 511eca3 | 2014-02-12 13:46:45 -0800 | [diff] [blame] | 409 | * code, that memory accesses are within valid ranges (to the |
| 410 | * extent that this can be checked statically; loads of packet |
| 411 | * data have to be, and are, also checked at run time), and that |
| 412 | * the code terminates with either an accept or reject. |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 413 | * |
| 414 | * The kernel needs to be able to verify an application's filter code. |
| 415 | * Otherwise, a bogus program could easily crash the system. |
| 416 | */ |
| 417 | int |
Haibo Huang | 165065a | 2018-07-23 17:26:52 -0700 | [diff] [blame] | 418 | bpf_validate(const struct bpf_insn *f, int len) |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 419 | { |
JP Abgrall | 511eca3 | 2014-02-12 13:46:45 -0800 | [diff] [blame] | 420 | u_int i, from; |
| 421 | const struct bpf_insn *p; |
| 422 | |
| 423 | if (len < 1) |
| 424 | return 0; |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 425 | |
Elliott Hughes | 965a4b5 | 2017-05-15 10:37:39 -0700 | [diff] [blame] | 426 | for (i = 0; i < (u_int)len; ++i) { |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 427 | p = &f[i]; |
JP Abgrall | 511eca3 | 2014-02-12 13:46:45 -0800 | [diff] [blame] | 428 | switch (BPF_CLASS(p->code)) { |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 429 | /* |
| 430 | * Check that memory operations use valid addresses. |
| 431 | */ |
JP Abgrall | 511eca3 | 2014-02-12 13:46:45 -0800 | [diff] [blame] | 432 | case BPF_LD: |
| 433 | case BPF_LDX: |
| 434 | switch (BPF_MODE(p->code)) { |
| 435 | case BPF_IMM: |
| 436 | break; |
| 437 | case BPF_ABS: |
| 438 | case BPF_IND: |
| 439 | case BPF_MSH: |
| 440 | /* |
| 441 | * There's no maximum packet data size |
| 442 | * in userland. The runtime packet length |
| 443 | * check suffices. |
| 444 | */ |
JP Abgrall | 511eca3 | 2014-02-12 13:46:45 -0800 | [diff] [blame] | 445 | break; |
| 446 | case BPF_MEM: |
| 447 | if (p->k >= BPF_MEMWORDS) |
| 448 | return 0; |
| 449 | break; |
| 450 | case BPF_LEN: |
| 451 | break; |
| 452 | default: |
| 453 | return 0; |
| 454 | } |
| 455 | break; |
| 456 | case BPF_ST: |
| 457 | case BPF_STX: |
| 458 | if (p->k >= BPF_MEMWORDS) |
| 459 | return 0; |
| 460 | break; |
| 461 | case BPF_ALU: |
| 462 | switch (BPF_OP(p->code)) { |
| 463 | case BPF_ADD: |
| 464 | case BPF_SUB: |
| 465 | case BPF_MUL: |
| 466 | case BPF_OR: |
| 467 | case BPF_AND: |
Elliott Hughes | d8845d7 | 2015-10-19 18:07:04 -0700 | [diff] [blame] | 468 | case BPF_XOR: |
JP Abgrall | 511eca3 | 2014-02-12 13:46:45 -0800 | [diff] [blame] | 469 | case BPF_LSH: |
| 470 | case BPF_RSH: |
| 471 | case BPF_NEG: |
| 472 | break; |
| 473 | case BPF_DIV: |
Elliott Hughes | d8845d7 | 2015-10-19 18:07:04 -0700 | [diff] [blame] | 474 | case BPF_MOD: |
JP Abgrall | 511eca3 | 2014-02-12 13:46:45 -0800 | [diff] [blame] | 475 | /* |
Elliott Hughes | d8845d7 | 2015-10-19 18:07:04 -0700 | [diff] [blame] | 476 | * Check for constant division or modulus |
| 477 | * by 0. |
JP Abgrall | 511eca3 | 2014-02-12 13:46:45 -0800 | [diff] [blame] | 478 | */ |
| 479 | if (BPF_SRC(p->code) == BPF_K && p->k == 0) |
| 480 | return 0; |
| 481 | break; |
| 482 | default: |
| 483 | return 0; |
| 484 | } |
| 485 | break; |
| 486 | case BPF_JMP: |
| 487 | /* |
| 488 | * Check that jumps are within the code block, |
| 489 | * and that unconditional branches don't go |
| 490 | * backwards as a result of an overflow. |
| 491 | * Unconditional branches have a 32-bit offset, |
| 492 | * so they could overflow; we check to make |
| 493 | * sure they don't. Conditional branches have |
| 494 | * an 8-bit offset, and the from address is <= |
| 495 | * BPF_MAXINSNS, and we assume that BPF_MAXINSNS |
| 496 | * is sufficiently small that adding 255 to it |
| 497 | * won't overflow. |
| 498 | * |
| 499 | * We know that len is <= BPF_MAXINSNS, and we |
| 500 | * assume that BPF_MAXINSNS is < the maximum size |
| 501 | * of a u_int, so that i + 1 doesn't overflow. |
| 502 | * |
| 503 | * For userland, we don't know that the from |
| 504 | * or len are <= BPF_MAXINSNS, but we know that |
| 505 | * from <= len, and, except on a 64-bit system, |
| 506 | * it's unlikely that len, if it truly reflects |
| 507 | * the size of the program we've been handed, |
| 508 | * will be anywhere near the maximum size of |
| 509 | * a u_int. We also don't check for backward |
| 510 | * branches, as we currently support them in |
| 511 | * userland for the protochain operation. |
| 512 | */ |
| 513 | from = i + 1; |
| 514 | switch (BPF_OP(p->code)) { |
| 515 | case BPF_JA: |
Elliott Hughes | 965a4b5 | 2017-05-15 10:37:39 -0700 | [diff] [blame] | 516 | if (from + p->k >= (u_int)len) |
JP Abgrall | 511eca3 | 2014-02-12 13:46:45 -0800 | [diff] [blame] | 517 | return 0; |
| 518 | break; |
| 519 | case BPF_JEQ: |
| 520 | case BPF_JGT: |
| 521 | case BPF_JGE: |
| 522 | case BPF_JSET: |
Elliott Hughes | 965a4b5 | 2017-05-15 10:37:39 -0700 | [diff] [blame] | 523 | if (from + p->jt >= (u_int)len || from + p->jf >= (u_int)len) |
JP Abgrall | 511eca3 | 2014-02-12 13:46:45 -0800 | [diff] [blame] | 524 | return 0; |
| 525 | break; |
| 526 | default: |
| 527 | return 0; |
| 528 | } |
| 529 | break; |
| 530 | case BPF_RET: |
| 531 | break; |
| 532 | case BPF_MISC: |
| 533 | break; |
| 534 | default: |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 535 | return 0; |
JP Abgrall | 511eca3 | 2014-02-12 13:46:45 -0800 | [diff] [blame] | 536 | } |
The Android Open Source Project | 478ab6c | 2009-03-03 19:30:05 -0800 | [diff] [blame] | 537 | } |
| 538 | return BPF_CLASS(f[len - 1].code) == BPF_RET; |
| 539 | } |