| | 1 | /* |
| | 2 | * Linux Socket Filter - Kernel level socket filtering |
| | 3 | * |
| | 4 | * Author: |
| | 5 | * Jay Schulist <jschlst@samba.org> |
| | 6 | * |
| | 7 | * Based on the design of: |
| | 8 | * - The Berkeley Packet Filter |
| | 9 | * |
| | 10 | * This program is free software; you can redistribute it and/or |
| | 11 | * modify it under the terms of the GNU General Public License |
| | 12 | * as published by the Free Software Foundation; either version |
| | 13 | * 2 of the License, or (at your option) any later version. |
| | 14 | * |
| | 15 | * Andi Kleen - Fix a few bad bugs and races. |
| | 16 | * Kris Katterjohn - Added many additional checks in sk_chk_filter() |
| | 17 | */ |
| | 18 | |
| | 19 | #include <linux/module.h> |
| | 20 | #include <linux/types.h> |
| | 21 | #include <linux/mm.h> |
| | 22 | #include <linux/fcntl.h> |
| | 23 | #include <linux/socket.h> |
| | 24 | #include <linux/in.h> |
| | 25 | #include <linux/inet.h> |
| | 26 | #include <linux/netdevice.h> |
| | 27 | #include <linux/if_packet.h> |
| | 28 | #include <linux/gfp.h> |
| | 29 | #include <net/ip.h> |
| | 30 | #include <net/protocol.h> |
| | 31 | #include <net/netlink.h> |
| | 32 | #include <linux/skbuff.h> |
| | 33 | #include <net/sock.h> |
| | 34 | #include <linux/errno.h> |
| | 35 | #include <linux/timer.h> |
| | 36 | #include <asm/system.h> |
| | 37 | #include <asm/uaccess.h> |
| | 38 | #include <asm/unaligned.h> |
| | 39 | #include <linux/filter.h> |
| | 40 | |
| | 41 | /* No hurry in this branch */ |
| | 42 | static void *__load_pointer(struct sk_buff *skb, int k) |
| | 43 | { |
| | 44 | u8 *ptr = NULL; |
| | 45 | |
| | 46 | if (k >= SKF_NET_OFF) |
| | 47 | ptr = skb_network_header(skb) + k - SKF_NET_OFF; |
| | 48 | else if (k >= SKF_LL_OFF) |
| | 49 | ptr = skb_mac_header(skb) + k - SKF_LL_OFF; |
| | 50 | |
| | 51 | if (ptr >= skb->head && ptr < skb_tail_pointer(skb)) |
| | 52 | return ptr; |
| | 53 | return NULL; |
| | 54 | } |
| | 55 | |
| | 56 | static inline void *load_pointer(struct sk_buff *skb, int k, |
| | 57 | unsigned int size, void *buffer) |
| | 58 | { |
| | 59 | if (k >= 0) |
| | 60 | return skb_header_pointer(skb, k, size, buffer); |
| | 61 | else { |
| | 62 | if (k >= SKF_AD_OFF) |
| | 63 | return NULL; |
| | 64 | return __load_pointer(skb, k); |
| | 65 | } |
| | 66 | } |
| | 67 | |
| | 68 | /** |
| | 69 | * sk_filter - run a packet through a socket filter |
| | 70 | * @sk: sock associated with &sk_buff |
| | 71 | * @skb: buffer to filter |
| | 72 | * |
| | 73 | * Run the filter code and then cut skb->data to correct size returned by |
| | 74 | * sk_run_filter. If pkt_len is 0 we toss packet. If skb->len is smaller |
| | 75 | * than pkt_len we keep whole skb->data. This is the socket level |
| | 76 | * wrapper to sk_run_filter. It returns 0 if the packet should |
| | 77 | * be accepted or -EPERM if the packet should be tossed. |
| | 78 | * |
| | 79 | */ |
| | 80 | int sk_filter(struct sock *sk, struct sk_buff *skb) |
| | 81 | { |
| | 82 | int err; |
| | 83 | struct sk_filter *filter; |
| | 84 | |
| | 85 | err = security_sock_rcv_skb(sk, skb); |
| | 86 | if (err) |
| | 87 | return err; |
| | 88 | |
| | 89 | rcu_read_lock_bh(); |
| | 90 | filter = rcu_dereference_bh(sk->sk_filter); |
| | 91 | if (filter) { |
| | 92 | unsigned int pkt_len = sk_run_filter(skb, filter->insns, filter->len); |
| | 93 | |
| | 94 | err = pkt_len ? pskb_trim(skb, pkt_len) : -EPERM; |
| | 95 | } |
| | 96 | rcu_read_unlock_bh(); |
| | 97 | |
| | 98 | return err; |
| | 99 | } |
| | 100 | EXPORT_SYMBOL(sk_filter); |
| | 101 | |
| | 102 | /** |
| | 103 | * sk_run_filter - run a filter on a socket |
| | 104 | * @skb: buffer to run the filter on |
| | 105 | * @filter: filter to apply |
| | 106 | * @flen: length of filter |
| | 107 | * |
| | 108 | * Decode and apply filter instructions to the skb->data. |
| | 109 | * Return length to keep, 0 for none. skb is the data we are |
| | 110 | * filtering, filter is the array of filter instructions, and |
| | 111 | * len is the number of filter blocks in the array. |
| | 112 | */ |
| | 113 | unsigned int sk_run_filter(struct sk_buff *skb, struct sock_filter *filter, int flen) |
| | 114 | { |
| | 115 | void *ptr; |
| | 116 | u32 A = 0; /* Accumulator */ |
| | 117 | u32 X = 0; /* Index Register */ |
| | 118 | u32 mem[BPF_MEMWORDS]; /* Scratch Memory Store */ |
| | 119 | unsigned long memvalid = 0; |
| | 120 | u32 tmp; |
| | 121 | int k; |
| | 122 | int pc; |
| | 123 | |
| | 124 | BUILD_BUG_ON(BPF_MEMWORDS > BITS_PER_LONG); |
| | 125 | /* |
| | 126 | * Process array of filter instructions. |
| | 127 | */ |
| | 128 | for (pc = 0; pc < flen; pc++) { |
| | 129 | const struct sock_filter *fentry = &filter[pc]; |
| | 130 | u32 f_k = fentry->k; |
| | 131 | |
| | 132 | switch (fentry->code) { |
| | 133 | case BPF_S_ALU_ADD_X: |
| | 134 | A += X; |
| | 135 | continue; |
| | 136 | case BPF_S_ALU_ADD_K: |
| | 137 | A += f_k; |
| | 138 | continue; |
| | 139 | case BPF_S_ALU_SUB_X: |
| | 140 | A -= X; |
| | 141 | continue; |
| | 142 | case BPF_S_ALU_SUB_K: |
| | 143 | A -= f_k; |
| | 144 | continue; |
| | 145 | case BPF_S_ALU_MUL_X: |
| | 146 | A *= X; |
| | 147 | continue; |
| | 148 | case BPF_S_ALU_MUL_K: |
| | 149 | A *= f_k; |
| | 150 | continue; |
| | 151 | case BPF_S_ALU_DIV_X: |
| | 152 | if (X == 0) |
| | 153 | return 0; |
| | 154 | A /= X; |
| | 155 | continue; |
| | 156 | case BPF_S_ALU_DIV_K: |
| | 157 | A /= f_k; |
| | 158 | continue; |
| | 159 | case BPF_S_ALU_AND_X: |
| | 160 | A &= X; |
| | 161 | continue; |
| | 162 | case BPF_S_ALU_AND_K: |
| | 163 | A &= f_k; |
| | 164 | continue; |
| | 165 | case BPF_S_ALU_OR_X: |
| | 166 | A |= X; |
| | 167 | continue; |
| | 168 | case BPF_S_ALU_OR_K: |
| | 169 | A |= f_k; |
| | 170 | continue; |
| | 171 | case BPF_S_ALU_LSH_X: |
| | 172 | A <<= X; |
| | 173 | continue; |
| | 174 | case BPF_S_ALU_LSH_K: |
| | 175 | A <<= f_k; |
| | 176 | continue; |
| | 177 | case BPF_S_ALU_RSH_X: |
| | 178 | A >>= X; |
| | 179 | continue; |
| | 180 | case BPF_S_ALU_RSH_K: |
| | 181 | A >>= f_k; |
| | 182 | continue; |
| | 183 | case BPF_S_ALU_NEG: |
| | 184 | A = -A; |
| | 185 | continue; |
| | 186 | case BPF_S_JMP_JA: |
| | 187 | pc += f_k; |
| | 188 | continue; |
| | 189 | case BPF_S_JMP_JGT_K: |
| | 190 | pc += (A > f_k) ? fentry->jt : fentry->jf; |
| | 191 | continue; |
| | 192 | case BPF_S_JMP_JGE_K: |
| | 193 | pc += (A >= f_k) ? fentry->jt : fentry->jf; |
| | 194 | continue; |
| | 195 | case BPF_S_JMP_JEQ_K: |
| | 196 | pc += (A == f_k) ? fentry->jt : fentry->jf; |
| | 197 | continue; |
| | 198 | case BPF_S_JMP_JSET_K: |
| | 199 | pc += (A & f_k) ? fentry->jt : fentry->jf; |
| | 200 | continue; |
| | 201 | case BPF_S_JMP_JGT_X: |
| | 202 | pc += (A > X) ? fentry->jt : fentry->jf; |
| | 203 | continue; |
| | 204 | case BPF_S_JMP_JGE_X: |
| | 205 | pc += (A >= X) ? fentry->jt : fentry->jf; |
| | 206 | continue; |
| | 207 | case BPF_S_JMP_JEQ_X: |
| | 208 | pc += (A == X) ? fentry->jt : fentry->jf; |
| | 209 | continue; |
| | 210 | case BPF_S_JMP_JSET_X: |
| | 211 | pc += (A & X) ? fentry->jt : fentry->jf; |
| | 212 | continue; |
| | 213 | case BPF_S_LD_W_ABS: |
| | 214 | k = f_k; |
| | 215 | load_w: |
| | 216 | ptr = load_pointer(skb, k, 4, &tmp); |
| | 217 | if (ptr != NULL) { |
| | 218 | A = get_unaligned_be32(ptr); |
| | 219 | continue; |
| | 220 | } |
| | 221 | break; |
| | 222 | case BPF_S_LD_H_ABS: |
| | 223 | k = f_k; |
| | 224 | load_h: |
| | 225 | ptr = load_pointer(skb, k, 2, &tmp); |
| | 226 | if (ptr != NULL) { |
| | 227 | A = get_unaligned_be16(ptr); |
| | 228 | continue; |
| | 229 | } |
| | 230 | break; |
| | 231 | case BPF_S_LD_B_ABS: |
| | 232 | k = f_k; |
| | 233 | load_b: |
| | 234 | ptr = load_pointer(skb, k, 1, &tmp); |
| | 235 | if (ptr != NULL) { |
| | 236 | A = *(u8 *)ptr; |
| | 237 | continue; |
| | 238 | } |
| | 239 | break; |
| | 240 | case BPF_S_LD_W_LEN: |
| | 241 | A = skb->len; |
| | 242 | continue; |
| | 243 | case BPF_S_LDX_W_LEN: |
| | 244 | X = skb->len; |
| | 245 | continue; |
| | 246 | case BPF_S_LD_W_IND: |
| | 247 | k = X + f_k; |
| | 248 | goto load_w; |
| | 249 | case BPF_S_LD_H_IND: |
| | 250 | k = X + f_k; |
| | 251 | goto load_h; |
| | 252 | case BPF_S_LD_B_IND: |
| | 253 | k = X + f_k; |
| | 254 | goto load_b; |
| | 255 | case BPF_S_LDX_B_MSH: |
| | 256 | ptr = load_pointer(skb, f_k, 1, &tmp); |
| | 257 | if (ptr != NULL) { |
| | 258 | X = (*(u8 *)ptr & 0xf) << 2; |
| | 259 | continue; |
| | 260 | } |
| | 261 | return 0; |
| | 262 | case BPF_S_LD_IMM: |
| | 263 | A = f_k; |
| | 264 | continue; |
| | 265 | case BPF_S_LDX_IMM: |
| | 266 | X = f_k; |
| | 267 | continue; |
| | 268 | case BPF_S_LD_MEM: |
| | 269 | A = (memvalid & (1UL << f_k)) ? |
| | 270 | mem[f_k] : 0; |
| | 271 | continue; |
| | 272 | case BPF_S_LDX_MEM: |
| | 273 | X = (memvalid & (1UL << f_k)) ? |
| | 274 | mem[f_k] : 0; |
| | 275 | continue; |
| | 276 | case BPF_S_MISC_TAX: |
| | 277 | X = A; |
| | 278 | continue; |
| | 279 | case BPF_S_MISC_TXA: |
| | 280 | A = X; |
| | 281 | continue; |
| | 282 | case BPF_S_RET_K: |
| | 283 | return f_k; |
| | 284 | case BPF_S_RET_A: |
| | 285 | return A; |
| | 286 | case BPF_S_ST: |
| | 287 | memvalid |= 1UL << f_k; |
| | 288 | mem[f_k] = A; |
| | 289 | continue; |
| | 290 | case BPF_S_STX: |
| | 291 | memvalid |= 1UL << f_k; |
| | 292 | mem[f_k] = X; |
| | 293 | continue; |
| | 294 | default: |
| | 295 | WARN_ON(1); |
| | 296 | return 0; |
| | 297 | } |
| | 298 | |
| | 299 | /* |
| | 300 | * Handle ancillary data, which are impossible |
| | 301 | * (or very difficult) to get parsing packet contents. |
| | 302 | */ |
| | 303 | switch (k-SKF_AD_OFF) { |
| | 304 | case SKF_AD_PROTOCOL: |
| | 305 | A = ntohs(skb->protocol); |
| | 306 | continue; |
| | 307 | case SKF_AD_PKTTYPE: |
| | 308 | A = skb->pkt_type; |
| | 309 | continue; |
| | 310 | case SKF_AD_IFINDEX: |
| | 311 | if (!skb->dev) |
| | 312 | return 0; |
| | 313 | A = skb->dev->ifindex; |
| | 314 | continue; |
| | 315 | case SKF_AD_MARK: |
| | 316 | A = skb->mark; |
| | 317 | continue; |
| | 318 | case SKF_AD_QUEUE: |
| | 319 | A = skb->queue_mapping; |
| | 320 | continue; |
| | 321 | case SKF_AD_HATYPE: |
| | 322 | if (!skb->dev) |
| | 323 | return 0; |
| | 324 | A = skb->dev->type; |
| | 325 | continue; |
| | 326 | case SKF_AD_NLATTR: { |
| | 327 | struct nlattr *nla; |
| | 328 | |
| | 329 | if (skb_is_nonlinear(skb)) |
| | 330 | return 0; |
| | 331 | if (A > skb->len - sizeof(struct nlattr)) |
| | 332 | return 0; |
| | 333 | |
| | 334 | nla = nla_find((struct nlattr *)&skb->data[A], |
| | 335 | skb->len - A, X); |
| | 336 | if (nla) |
| | 337 | A = (void *)nla - (void *)skb->data; |
| | 338 | else |
| | 339 | A = 0; |
| | 340 | continue; |
| | 341 | } |
| | 342 | case SKF_AD_NLATTR_NEST: { |
| | 343 | struct nlattr *nla; |
| | 344 | |
| | 345 | if (skb_is_nonlinear(skb)) |
| | 346 | return 0; |
| | 347 | if (A > skb->len - sizeof(struct nlattr)) |
| | 348 | return 0; |
| | 349 | |
| | 350 | nla = (struct nlattr *)&skb->data[A]; |
| | 351 | if (nla->nla_len > A - skb->len) |
| | 352 | return 0; |
| | 353 | |
| | 354 | nla = nla_find_nested(nla, X); |
| | 355 | if (nla) |
| | 356 | A = (void *)nla - (void *)skb->data; |
| | 357 | else |
| | 358 | A = 0; |
| | 359 | continue; |
| | 360 | } |
| | 361 | default: |
| | 362 | return 0; |
| | 363 | } |
| | 364 | } |
| | 365 | |
| | 366 | return 0; |
| | 367 | } |
| | 368 | EXPORT_SYMBOL(sk_run_filter); |
| | 369 | |
| | 370 | /** |
| | 371 | * sk_chk_filter - verify socket filter code |
| | 372 | * @filter: filter to verify |
| | 373 | * @flen: length of filter |
| | 374 | * |
| | 375 | * Check the user's filter code. If we let some ugly |
| | 376 | * filter code slip through kaboom! The filter must contain |
| | 377 | * no references or jumps that are out of range, no illegal |
| | 378 | * instructions, and must end with a RET instruction. |
| | 379 | * |
| | 380 | * All jumps are forward as they are not signed. |
| | 381 | * |
| | 382 | * Returns 0 if the rule set is legal or -EINVAL if not. |
| | 383 | */ |
| | 384 | int sk_chk_filter(struct sock_filter *filter, int flen) |
| | 385 | { |
| | 386 | /* |
| | 387 | * Valid instructions are initialized to non-0. |
| | 388 | * Invalid instructions are initialized to 0. |
| | 389 | */ |
| | 390 | static const u8 codes[] = { |
| | 391 | [BPF_ALU|BPF_ADD|BPF_K] = BPF_S_ALU_ADD_K + 1, |
| | 392 | [BPF_ALU|BPF_ADD|BPF_X] = BPF_S_ALU_ADD_X + 1, |
| | 393 | [BPF_ALU|BPF_SUB|BPF_K] = BPF_S_ALU_SUB_K + 1, |
| | 394 | [BPF_ALU|BPF_SUB|BPF_X] = BPF_S_ALU_SUB_X + 1, |
| | 395 | [BPF_ALU|BPF_MUL|BPF_K] = BPF_S_ALU_MUL_K + 1, |
| | 396 | [BPF_ALU|BPF_MUL|BPF_X] = BPF_S_ALU_MUL_X + 1, |
| | 397 | [BPF_ALU|BPF_DIV|BPF_X] = BPF_S_ALU_DIV_X + 1, |
| | 398 | [BPF_ALU|BPF_AND|BPF_K] = BPF_S_ALU_AND_K + 1, |
| | 399 | [BPF_ALU|BPF_AND|BPF_X] = BPF_S_ALU_AND_X + 1, |
| | 400 | [BPF_ALU|BPF_OR|BPF_K] = BPF_S_ALU_OR_K + 1, |
| | 401 | [BPF_ALU|BPF_OR|BPF_X] = BPF_S_ALU_OR_X + 1, |
| | 402 | [BPF_ALU|BPF_LSH|BPF_K] = BPF_S_ALU_LSH_K + 1, |
| | 403 | [BPF_ALU|BPF_LSH|BPF_X] = BPF_S_ALU_LSH_X + 1, |
| | 404 | [BPF_ALU|BPF_RSH|BPF_K] = BPF_S_ALU_RSH_K + 1, |
| | 405 | [BPF_ALU|BPF_RSH|BPF_X] = BPF_S_ALU_RSH_X + 1, |
| | 406 | [BPF_ALU|BPF_NEG] = BPF_S_ALU_NEG + 1, |
| | 407 | [BPF_LD|BPF_W|BPF_ABS] = BPF_S_LD_W_ABS + 1, |
| | 408 | [BPF_LD|BPF_H|BPF_ABS] = BPF_S_LD_H_ABS + 1, |
| | 409 | [BPF_LD|BPF_B|BPF_ABS] = BPF_S_LD_B_ABS + 1, |
| | 410 | [BPF_LD|BPF_W|BPF_LEN] = BPF_S_LD_W_LEN + 1, |
| | 411 | [BPF_LD|BPF_W|BPF_IND] = BPF_S_LD_W_IND + 1, |
| | 412 | [BPF_LD|BPF_H|BPF_IND] = BPF_S_LD_H_IND + 1, |
| | 413 | [BPF_LD|BPF_B|BPF_IND] = BPF_S_LD_B_IND + 1, |
| | 414 | [BPF_LD|BPF_IMM] = BPF_S_LD_IMM + 1, |
| | 415 | [BPF_LDX|BPF_W|BPF_LEN] = BPF_S_LDX_W_LEN + 1, |
| | 416 | [BPF_LDX|BPF_B|BPF_MSH] = BPF_S_LDX_B_MSH + 1, |
| | 417 | [BPF_LDX|BPF_IMM] = BPF_S_LDX_IMM + 1, |
| | 418 | [BPF_MISC|BPF_TAX] = BPF_S_MISC_TAX + 1, |
| | 419 | [BPF_MISC|BPF_TXA] = BPF_S_MISC_TXA + 1, |
| | 420 | [BPF_RET|BPF_K] = BPF_S_RET_K + 1, |
| | 421 | [BPF_RET|BPF_A] = BPF_S_RET_A + 1, |
| | 422 | [BPF_ALU|BPF_DIV|BPF_K] = BPF_S_ALU_DIV_K + 1, |
| | 423 | [BPF_LD|BPF_MEM] = BPF_S_LD_MEM + 1, |
| | 424 | [BPF_LDX|BPF_MEM] = BPF_S_LDX_MEM + 1, |
| | 425 | [BPF_ST] = BPF_S_ST + 1, |
| | 426 | [BPF_STX] = BPF_S_STX + 1, |
| | 427 | [BPF_JMP|BPF_JA] = BPF_S_JMP_JA + 1, |
| | 428 | [BPF_JMP|BPF_JEQ|BPF_K] = BPF_S_JMP_JEQ_K + 1, |
| | 429 | [BPF_JMP|BPF_JEQ|BPF_X] = BPF_S_JMP_JEQ_X + 1, |
| | 430 | [BPF_JMP|BPF_JGE|BPF_K] = BPF_S_JMP_JGE_K + 1, |
| | 431 | [BPF_JMP|BPF_JGE|BPF_X] = BPF_S_JMP_JGE_X + 1, |
| | 432 | [BPF_JMP|BPF_JGT|BPF_K] = BPF_S_JMP_JGT_K + 1, |
| | 433 | [BPF_JMP|BPF_JGT|BPF_X] = BPF_S_JMP_JGT_X + 1, |
| | 434 | [BPF_JMP|BPF_JSET|BPF_K] = BPF_S_JMP_JSET_K + 1, |
| | 435 | [BPF_JMP|BPF_JSET|BPF_X] = BPF_S_JMP_JSET_X + 1, |
| | 436 | }; |
| | 437 | int pc; |
| | 438 | |
| | 439 | if (flen == 0 || flen > BPF_MAXINSNS) |
| | 440 | return -EINVAL; |
| | 441 | |
| | 442 | /* check the filter code now */ |
| | 443 | for (pc = 0; pc < flen; pc++) { |
| | 444 | struct sock_filter *ftest = &filter[pc]; |
| | 445 | u16 code = ftest->code; |
| | 446 | |
| | 447 | if (code >= ARRAY_SIZE(codes)) |
| | 448 | return -EINVAL; |
| | 449 | code = codes[code]; |
| | 450 | /* Undo the '+ 1' in codes[] after validation. */ |
| | 451 | if (!code--) |
| | 452 | return -EINVAL; |
| | 453 | /* Some instructions need special checks */ |
| | 454 | switch (code) { |
| | 455 | case BPF_S_ALU_DIV_K: |
| | 456 | /* check for division by zero */ |
| | 457 | if (ftest->k == 0) |
| | 458 | return -EINVAL; |
| | 459 | break; |
| | 460 | case BPF_S_LD_MEM: |
| | 461 | case BPF_S_LDX_MEM: |
| | 462 | case BPF_S_ST: |
| | 463 | case BPF_S_STX: |
| | 464 | /* check for invalid memory addresses */ |
| | 465 | if (ftest->k >= BPF_MEMWORDS) |
| | 466 | return -EINVAL; |
| | 467 | break; |
| | 468 | case BPF_S_JMP_JA: |
| | 469 | /* |
| | 470 | * Note, the large ftest->k might cause loops. |
| | 471 | * Compare this with conditional jumps below, |
| | 472 | * where offsets are limited. --ANK (981016) |
| | 473 | */ |
| | 474 | if (ftest->k >= (unsigned)(flen-pc-1)) |
| | 475 | return -EINVAL; |
| | 476 | break; |
| | 477 | case BPF_S_JMP_JEQ_K: |
| | 478 | case BPF_S_JMP_JEQ_X: |
| | 479 | case BPF_S_JMP_JGE_K: |
| | 480 | case BPF_S_JMP_JGE_X: |
| | 481 | case BPF_S_JMP_JGT_K: |
| | 482 | case BPF_S_JMP_JGT_X: |
| | 483 | case BPF_S_JMP_JSET_X: |
| | 484 | case BPF_S_JMP_JSET_K: |
| | 485 | /* for conditionals both must be safe */ |
| | 486 | if (pc + ftest->jt + 1 >= flen || |
| | 487 | pc + ftest->jf + 1 >= flen) |
| | 488 | return -EINVAL; |
| | 489 | break; |
| | 490 | } |
| | 491 | ftest->code = code; |
| | 492 | } |
| | 493 | |
| | 494 | /* last instruction must be a RET code */ |
| | 495 | switch (filter[flen - 1].code) { |
| | 496 | case BPF_S_RET_K: |
| | 497 | case BPF_S_RET_A: |
| | 498 | return 0; |
| | 499 | } |
| | 500 | return -EINVAL; |
| | 501 | } |
| | 502 | EXPORT_SYMBOL(sk_chk_filter); |
| | 503 | |
| | 504 | /** |
| | 505 | * sk_filter_rcu_release: Release a socket filter by rcu_head |
| | 506 | * @rcu: rcu_head that contains the sk_filter to free |
| | 507 | */ |
| | 508 | static void sk_filter_rcu_release(struct rcu_head *rcu) |
| | 509 | { |
| | 510 | struct sk_filter *fp = container_of(rcu, struct sk_filter, rcu); |
| | 511 | |
| | 512 | sk_filter_release(fp); |
| | 513 | } |
| | 514 | |
| | 515 | static void sk_filter_delayed_uncharge(struct sock *sk, struct sk_filter *fp) |
| | 516 | { |
| | 517 | unsigned int size = sk_filter_len(fp); |
| | 518 | |
| | 519 | atomic_sub(size, &sk->sk_omem_alloc); |
| | 520 | call_rcu_bh(&fp->rcu, sk_filter_rcu_release); |
| | 521 | } |
| | 522 | |
| | 523 | /** |
| | 524 | * sk_attach_filter - attach a socket filter |
| | 525 | * @fprog: the filter program |
| | 526 | * @sk: the socket to use |
| | 527 | * |
| | 528 | * Attach the user's filter code. We first run some sanity checks on |
| | 529 | * it to make sure it does not explode on us later. If an error |
| | 530 | * occurs or there is insufficient memory for the filter a negative |
| | 531 | * errno code is returned. On success the return is zero. |
| | 532 | */ |
| | 533 | int sk_attach_filter(struct sock_fprog *fprog, struct sock *sk) |
| | 534 | { |
| | 535 | struct sk_filter *fp, *old_fp; |
| | 536 | unsigned int fsize = sizeof(struct sock_filter) * fprog->len; |
| | 537 | int err; |
| | 538 | |
| | 539 | /* Make sure new filter is there and in the right amounts. */ |
| | 540 | if (fprog->filter == NULL) |
| | 541 | return -EINVAL; |
| | 542 | |
| | 543 | fp = sock_kmalloc(sk, fsize+sizeof(*fp), GFP_KERNEL); |
| | 544 | if (!fp) |
| | 545 | return -ENOMEM; |
| | 546 | if (copy_from_user(fp->insns, fprog->filter, fsize)) { |
| | 547 | sock_kfree_s(sk, fp, fsize+sizeof(*fp)); |
| | 548 | return -EFAULT; |
| | 549 | } |
| | 550 | |
| | 551 | atomic_set(&fp->refcnt, 1); |
| | 552 | fp->len = fprog->len; |
| | 553 | |
| | 554 | err = sk_chk_filter(fp->insns, fp->len); |
| | 555 | if (err) { |
| | 556 | sk_filter_uncharge(sk, fp); |
| | 557 | return err; |
| | 558 | } |
| | 559 | |
| | 560 | old_fp = rcu_dereference_protected(sk->sk_filter, |
| | 561 | sock_owned_by_user(sk)); |
| | 562 | rcu_assign_pointer(sk->sk_filter, fp); |
| | 563 | |
| | 564 | if (old_fp) |
| | 565 | sk_filter_delayed_uncharge(sk, old_fp); |
| | 566 | return 0; |
| | 567 | } |
| | 568 | EXPORT_SYMBOL_GPL(sk_attach_filter); |
| | 569 | |
| | 570 | int sk_detach_filter(struct sock *sk) |
| | 571 | { |
| | 572 | int ret = -ENOENT; |
| | 573 | struct sk_filter *filter; |
| | 574 | |
| | 575 | filter = rcu_dereference_protected(sk->sk_filter, |
| | 576 | sock_owned_by_user(sk)); |
| | 577 | if (filter) { |
| | 578 | rcu_assign_pointer(sk->sk_filter, NULL); |
| | 579 | sk_filter_delayed_uncharge(sk, filter); |
| | 580 | ret = 0; |
| | 581 | } |
| | 582 | return ret; |
| | 583 | } |
| | 584 | EXPORT_SYMBOL_GPL(sk_detach_filter); |
git://bbs.cooldavid.org / net-next-2.6.git / blame_incremental