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Commit | Line | Data |
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1da177e4 LT |
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. | |
93699863 | 16 | * Kris Katterjohn - Added many additional checks in sk_chk_filter() |
1da177e4 LT |
17 | */ |
18 | ||
19 | #include <linux/module.h> | |
20 | #include <linux/types.h> | |
1da177e4 LT |
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> | |
5a0e3ad6 | 28 | #include <linux/gfp.h> |
1da177e4 LT |
29 | #include <net/ip.h> |
30 | #include <net/protocol.h> | |
4738c1db | 31 | #include <net/netlink.h> |
1da177e4 LT |
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> | |
40daafc8 | 38 | #include <asm/unaligned.h> |
1da177e4 | 39 | #include <linux/filter.h> |
c26aed40 | 40 | #include <linux/reciprocal_div.h> |
1da177e4 | 41 | |
4c3710af | 42 | enum { |
8c1592d6 | 43 | BPF_S_RET_K = 1, |
4c3710af CG |
44 | BPF_S_RET_A, |
45 | BPF_S_ALU_ADD_K, | |
46 | BPF_S_ALU_ADD_X, | |
47 | BPF_S_ALU_SUB_K, | |
48 | BPF_S_ALU_SUB_X, | |
49 | BPF_S_ALU_MUL_K, | |
50 | BPF_S_ALU_MUL_X, | |
51 | BPF_S_ALU_DIV_X, | |
52 | BPF_S_ALU_AND_K, | |
53 | BPF_S_ALU_AND_X, | |
54 | BPF_S_ALU_OR_K, | |
55 | BPF_S_ALU_OR_X, | |
56 | BPF_S_ALU_LSH_K, | |
57 | BPF_S_ALU_LSH_X, | |
58 | BPF_S_ALU_RSH_K, | |
59 | BPF_S_ALU_RSH_X, | |
60 | BPF_S_ALU_NEG, | |
61 | BPF_S_LD_W_ABS, | |
62 | BPF_S_LD_H_ABS, | |
63 | BPF_S_LD_B_ABS, | |
64 | BPF_S_LD_W_LEN, | |
65 | BPF_S_LD_W_IND, | |
66 | BPF_S_LD_H_IND, | |
67 | BPF_S_LD_B_IND, | |
68 | BPF_S_LD_IMM, | |
69 | BPF_S_LDX_W_LEN, | |
70 | BPF_S_LDX_B_MSH, | |
71 | BPF_S_LDX_IMM, | |
72 | BPF_S_MISC_TAX, | |
73 | BPF_S_MISC_TXA, | |
74 | BPF_S_ALU_DIV_K, | |
75 | BPF_S_LD_MEM, | |
76 | BPF_S_LDX_MEM, | |
77 | BPF_S_ST, | |
78 | BPF_S_STX, | |
79 | BPF_S_JMP_JA, | |
80 | BPF_S_JMP_JEQ_K, | |
81 | BPF_S_JMP_JEQ_X, | |
82 | BPF_S_JMP_JGE_K, | |
83 | BPF_S_JMP_JGE_X, | |
84 | BPF_S_JMP_JGT_K, | |
85 | BPF_S_JMP_JGT_X, | |
86 | BPF_S_JMP_JSET_K, | |
87 | BPF_S_JMP_JSET_X, | |
88 | }; | |
89 | ||
1da177e4 | 90 | /* No hurry in this branch */ |
0b05b2a4 | 91 | static void *__load_pointer(struct sk_buff *skb, int k) |
1da177e4 LT |
92 | { |
93 | u8 *ptr = NULL; | |
94 | ||
95 | if (k >= SKF_NET_OFF) | |
d56f90a7 | 96 | ptr = skb_network_header(skb) + k - SKF_NET_OFF; |
1da177e4 | 97 | else if (k >= SKF_LL_OFF) |
98e399f8 | 98 | ptr = skb_mac_header(skb) + k - SKF_LL_OFF; |
1da177e4 | 99 | |
27a884dc | 100 | if (ptr >= skb->head && ptr < skb_tail_pointer(skb)) |
1da177e4 LT |
101 | return ptr; |
102 | return NULL; | |
103 | } | |
104 | ||
0b05b2a4 | 105 | static inline void *load_pointer(struct sk_buff *skb, int k, |
4ec93edb | 106 | unsigned int size, void *buffer) |
0b05b2a4 PM |
107 | { |
108 | if (k >= 0) | |
109 | return skb_header_pointer(skb, k, size, buffer); | |
110 | else { | |
111 | if (k >= SKF_AD_OFF) | |
112 | return NULL; | |
113 | return __load_pointer(skb, k); | |
114 | } | |
115 | } | |
116 | ||
43db6d65 SH |
117 | /** |
118 | * sk_filter - run a packet through a socket filter | |
119 | * @sk: sock associated with &sk_buff | |
120 | * @skb: buffer to filter | |
43db6d65 SH |
121 | * |
122 | * Run the filter code and then cut skb->data to correct size returned by | |
123 | * sk_run_filter. If pkt_len is 0 we toss packet. If skb->len is smaller | |
124 | * than pkt_len we keep whole skb->data. This is the socket level | |
125 | * wrapper to sk_run_filter. It returns 0 if the packet should | |
126 | * be accepted or -EPERM if the packet should be tossed. | |
127 | * | |
128 | */ | |
129 | int sk_filter(struct sock *sk, struct sk_buff *skb) | |
130 | { | |
131 | int err; | |
132 | struct sk_filter *filter; | |
133 | ||
134 | err = security_sock_rcv_skb(sk, skb); | |
135 | if (err) | |
136 | return err; | |
137 | ||
138 | rcu_read_lock_bh(); | |
a898def2 | 139 | filter = rcu_dereference_bh(sk->sk_filter); |
43db6d65 | 140 | if (filter) { |
93aaae2e | 141 | unsigned int pkt_len = sk_run_filter(skb, filter->insns); |
0d7da9dd | 142 | |
43db6d65 SH |
143 | err = pkt_len ? pskb_trim(skb, pkt_len) : -EPERM; |
144 | } | |
145 | rcu_read_unlock_bh(); | |
146 | ||
147 | return err; | |
148 | } | |
149 | EXPORT_SYMBOL(sk_filter); | |
150 | ||
1da177e4 | 151 | /** |
2966b66c | 152 | * sk_run_filter - run a filter on a socket |
1da177e4 LT |
153 | * @skb: buffer to run the filter on |
154 | * @filter: filter to apply | |
1da177e4 LT |
155 | * |
156 | * Decode and apply filter instructions to the skb->data. | |
93aaae2e ED |
157 | * Return length to keep, 0 for none. @skb is the data we are |
158 | * filtering, @filter is the array of filter instructions. | |
159 | * Because all jumps are guaranteed to be before last instruction, | |
160 | * and last instruction guaranteed to be a RET, we dont need to check | |
161 | * flen. (We used to pass to this function the length of filter) | |
1da177e4 | 162 | */ |
93aaae2e | 163 | unsigned int sk_run_filter(struct sk_buff *skb, const struct sock_filter *fentry) |
1da177e4 | 164 | { |
0b05b2a4 | 165 | void *ptr; |
2966b66c KK |
166 | u32 A = 0; /* Accumulator */ |
167 | u32 X = 0; /* Index Register */ | |
1da177e4 | 168 | u32 mem[BPF_MEMWORDS]; /* Scratch Memory Store */ |
57fe93b3 | 169 | unsigned long memvalid = 0; |
0b05b2a4 | 170 | u32 tmp; |
1da177e4 | 171 | int k; |
1da177e4 | 172 | |
57fe93b3 | 173 | BUILD_BUG_ON(BPF_MEMWORDS > BITS_PER_LONG); |
1da177e4 LT |
174 | /* |
175 | * Process array of filter instructions. | |
176 | */ | |
93aaae2e ED |
177 | for (;; fentry++) { |
178 | #if defined(CONFIG_X86_32) | |
179 | #define K (fentry->k) | |
180 | #else | |
181 | const u32 K = fentry->k; | |
182 | #endif | |
4ec93edb | 183 | |
1da177e4 | 184 | switch (fentry->code) { |
01f2f3f6 | 185 | case BPF_S_ALU_ADD_X: |
1da177e4 LT |
186 | A += X; |
187 | continue; | |
01f2f3f6 | 188 | case BPF_S_ALU_ADD_K: |
93aaae2e | 189 | A += K; |
1da177e4 | 190 | continue; |
01f2f3f6 | 191 | case BPF_S_ALU_SUB_X: |
1da177e4 LT |
192 | A -= X; |
193 | continue; | |
01f2f3f6 | 194 | case BPF_S_ALU_SUB_K: |
93aaae2e | 195 | A -= K; |
1da177e4 | 196 | continue; |
01f2f3f6 | 197 | case BPF_S_ALU_MUL_X: |
1da177e4 LT |
198 | A *= X; |
199 | continue; | |
01f2f3f6 | 200 | case BPF_S_ALU_MUL_K: |
93aaae2e | 201 | A *= K; |
1da177e4 | 202 | continue; |
01f2f3f6 | 203 | case BPF_S_ALU_DIV_X: |
1da177e4 LT |
204 | if (X == 0) |
205 | return 0; | |
206 | A /= X; | |
207 | continue; | |
01f2f3f6 | 208 | case BPF_S_ALU_DIV_K: |
c26aed40 | 209 | A = reciprocal_divide(A, K); |
1da177e4 | 210 | continue; |
01f2f3f6 | 211 | case BPF_S_ALU_AND_X: |
1da177e4 LT |
212 | A &= X; |
213 | continue; | |
01f2f3f6 | 214 | case BPF_S_ALU_AND_K: |
93aaae2e | 215 | A &= K; |
1da177e4 | 216 | continue; |
01f2f3f6 | 217 | case BPF_S_ALU_OR_X: |
1da177e4 LT |
218 | A |= X; |
219 | continue; | |
01f2f3f6 | 220 | case BPF_S_ALU_OR_K: |
93aaae2e | 221 | A |= K; |
1da177e4 | 222 | continue; |
01f2f3f6 | 223 | case BPF_S_ALU_LSH_X: |
1da177e4 LT |
224 | A <<= X; |
225 | continue; | |
01f2f3f6 | 226 | case BPF_S_ALU_LSH_K: |
93aaae2e | 227 | A <<= K; |
1da177e4 | 228 | continue; |
01f2f3f6 | 229 | case BPF_S_ALU_RSH_X: |
1da177e4 LT |
230 | A >>= X; |
231 | continue; | |
01f2f3f6 | 232 | case BPF_S_ALU_RSH_K: |
93aaae2e | 233 | A >>= K; |
1da177e4 | 234 | continue; |
01f2f3f6 | 235 | case BPF_S_ALU_NEG: |
1da177e4 LT |
236 | A = -A; |
237 | continue; | |
01f2f3f6 | 238 | case BPF_S_JMP_JA: |
93aaae2e | 239 | fentry += K; |
1da177e4 | 240 | continue; |
01f2f3f6 | 241 | case BPF_S_JMP_JGT_K: |
93aaae2e | 242 | fentry += (A > K) ? fentry->jt : fentry->jf; |
1da177e4 | 243 | continue; |
01f2f3f6 | 244 | case BPF_S_JMP_JGE_K: |
93aaae2e | 245 | fentry += (A >= K) ? fentry->jt : fentry->jf; |
1da177e4 | 246 | continue; |
01f2f3f6 | 247 | case BPF_S_JMP_JEQ_K: |
93aaae2e | 248 | fentry += (A == K) ? fentry->jt : fentry->jf; |
1da177e4 | 249 | continue; |
01f2f3f6 | 250 | case BPF_S_JMP_JSET_K: |
93aaae2e | 251 | fentry += (A & K) ? fentry->jt : fentry->jf; |
1da177e4 | 252 | continue; |
01f2f3f6 | 253 | case BPF_S_JMP_JGT_X: |
93aaae2e | 254 | fentry += (A > X) ? fentry->jt : fentry->jf; |
1da177e4 | 255 | continue; |
01f2f3f6 | 256 | case BPF_S_JMP_JGE_X: |
93aaae2e | 257 | fentry += (A >= X) ? fentry->jt : fentry->jf; |
1da177e4 | 258 | continue; |
01f2f3f6 | 259 | case BPF_S_JMP_JEQ_X: |
93aaae2e | 260 | fentry += (A == X) ? fentry->jt : fentry->jf; |
1da177e4 | 261 | continue; |
01f2f3f6 | 262 | case BPF_S_JMP_JSET_X: |
93aaae2e | 263 | fentry += (A & X) ? fentry->jt : fentry->jf; |
1da177e4 | 264 | continue; |
01f2f3f6 | 265 | case BPF_S_LD_W_ABS: |
93aaae2e | 266 | k = K; |
e35bedf3 | 267 | load_w: |
0b05b2a4 PM |
268 | ptr = load_pointer(skb, k, 4, &tmp); |
269 | if (ptr != NULL) { | |
d3e2ce3b | 270 | A = get_unaligned_be32(ptr); |
0b05b2a4 | 271 | continue; |
1da177e4 | 272 | } |
1198ad00 | 273 | break; |
01f2f3f6 | 274 | case BPF_S_LD_H_ABS: |
93aaae2e | 275 | k = K; |
e35bedf3 | 276 | load_h: |
0b05b2a4 PM |
277 | ptr = load_pointer(skb, k, 2, &tmp); |
278 | if (ptr != NULL) { | |
d3e2ce3b | 279 | A = get_unaligned_be16(ptr); |
0b05b2a4 | 280 | continue; |
1da177e4 | 281 | } |
1198ad00 | 282 | break; |
01f2f3f6 | 283 | case BPF_S_LD_B_ABS: |
93aaae2e | 284 | k = K; |
1da177e4 | 285 | load_b: |
0b05b2a4 PM |
286 | ptr = load_pointer(skb, k, 1, &tmp); |
287 | if (ptr != NULL) { | |
288 | A = *(u8 *)ptr; | |
289 | continue; | |
1da177e4 | 290 | } |
1198ad00 | 291 | break; |
01f2f3f6 | 292 | case BPF_S_LD_W_LEN: |
3154e540 | 293 | A = skb->len; |
1da177e4 | 294 | continue; |
01f2f3f6 | 295 | case BPF_S_LDX_W_LEN: |
3154e540 | 296 | X = skb->len; |
1da177e4 | 297 | continue; |
01f2f3f6 | 298 | case BPF_S_LD_W_IND: |
93aaae2e | 299 | k = X + K; |
1da177e4 | 300 | goto load_w; |
01f2f3f6 | 301 | case BPF_S_LD_H_IND: |
93aaae2e | 302 | k = X + K; |
1da177e4 | 303 | goto load_h; |
01f2f3f6 | 304 | case BPF_S_LD_B_IND: |
93aaae2e | 305 | k = X + K; |
1da177e4 | 306 | goto load_b; |
01f2f3f6 | 307 | case BPF_S_LDX_B_MSH: |
93aaae2e | 308 | ptr = load_pointer(skb, K, 1, &tmp); |
0b05b2a4 PM |
309 | if (ptr != NULL) { |
310 | X = (*(u8 *)ptr & 0xf) << 2; | |
311 | continue; | |
312 | } | |
313 | return 0; | |
01f2f3f6 | 314 | case BPF_S_LD_IMM: |
93aaae2e | 315 | A = K; |
1da177e4 | 316 | continue; |
01f2f3f6 | 317 | case BPF_S_LDX_IMM: |
93aaae2e | 318 | X = K; |
1da177e4 | 319 | continue; |
01f2f3f6 | 320 | case BPF_S_LD_MEM: |
93aaae2e ED |
321 | A = (memvalid & (1UL << K)) ? |
322 | mem[K] : 0; | |
1da177e4 | 323 | continue; |
01f2f3f6 | 324 | case BPF_S_LDX_MEM: |
93aaae2e ED |
325 | X = (memvalid & (1UL << K)) ? |
326 | mem[K] : 0; | |
1da177e4 | 327 | continue; |
01f2f3f6 | 328 | case BPF_S_MISC_TAX: |
1da177e4 LT |
329 | X = A; |
330 | continue; | |
01f2f3f6 | 331 | case BPF_S_MISC_TXA: |
1da177e4 LT |
332 | A = X; |
333 | continue; | |
01f2f3f6 | 334 | case BPF_S_RET_K: |
93aaae2e | 335 | return K; |
01f2f3f6 | 336 | case BPF_S_RET_A: |
4bad4dc9 | 337 | return A; |
01f2f3f6 | 338 | case BPF_S_ST: |
93aaae2e ED |
339 | memvalid |= 1UL << K; |
340 | mem[K] = A; | |
1da177e4 | 341 | continue; |
01f2f3f6 | 342 | case BPF_S_STX: |
93aaae2e ED |
343 | memvalid |= 1UL << K; |
344 | mem[K] = X; | |
1da177e4 LT |
345 | continue; |
346 | default: | |
93699863 | 347 | WARN_ON(1); |
1da177e4 LT |
348 | return 0; |
349 | } | |
350 | ||
351 | /* | |
352 | * Handle ancillary data, which are impossible | |
353 | * (or very difficult) to get parsing packet contents. | |
354 | */ | |
355 | switch (k-SKF_AD_OFF) { | |
356 | case SKF_AD_PROTOCOL: | |
252e3346 | 357 | A = ntohs(skb->protocol); |
1da177e4 LT |
358 | continue; |
359 | case SKF_AD_PKTTYPE: | |
360 | A = skb->pkt_type; | |
361 | continue; | |
362 | case SKF_AD_IFINDEX: | |
40eaf962 PLE |
363 | if (!skb->dev) |
364 | return 0; | |
1da177e4 LT |
365 | A = skb->dev->ifindex; |
366 | continue; | |
7e75f93e | 367 | case SKF_AD_MARK: |
368 | A = skb->mark; | |
369 | continue; | |
d19742fb ED |
370 | case SKF_AD_QUEUE: |
371 | A = skb->queue_mapping; | |
372 | continue; | |
40eaf962 PLE |
373 | case SKF_AD_HATYPE: |
374 | if (!skb->dev) | |
375 | return 0; | |
376 | A = skb->dev->type; | |
377 | continue; | |
4738c1db PM |
378 | case SKF_AD_NLATTR: { |
379 | struct nlattr *nla; | |
380 | ||
381 | if (skb_is_nonlinear(skb)) | |
382 | return 0; | |
383 | if (A > skb->len - sizeof(struct nlattr)) | |
384 | return 0; | |
385 | ||
386 | nla = nla_find((struct nlattr *)&skb->data[A], | |
387 | skb->len - A, X); | |
388 | if (nla) | |
389 | A = (void *)nla - (void *)skb->data; | |
390 | else | |
391 | A = 0; | |
392 | continue; | |
393 | } | |
d214c753 PNA |
394 | case SKF_AD_NLATTR_NEST: { |
395 | struct nlattr *nla; | |
396 | ||
397 | if (skb_is_nonlinear(skb)) | |
398 | return 0; | |
399 | if (A > skb->len - sizeof(struct nlattr)) | |
400 | return 0; | |
401 | ||
402 | nla = (struct nlattr *)&skb->data[A]; | |
403 | if (nla->nla_len > A - skb->len) | |
404 | return 0; | |
405 | ||
406 | nla = nla_find_nested(nla, X); | |
407 | if (nla) | |
408 | A = (void *)nla - (void *)skb->data; | |
409 | else | |
410 | A = 0; | |
411 | continue; | |
412 | } | |
1da177e4 LT |
413 | default: |
414 | return 0; | |
415 | } | |
416 | } | |
417 | ||
418 | return 0; | |
419 | } | |
b715631f | 420 | EXPORT_SYMBOL(sk_run_filter); |
1da177e4 LT |
421 | |
422 | /** | |
423 | * sk_chk_filter - verify socket filter code | |
424 | * @filter: filter to verify | |
425 | * @flen: length of filter | |
426 | * | |
427 | * Check the user's filter code. If we let some ugly | |
428 | * filter code slip through kaboom! The filter must contain | |
93699863 KK |
429 | * no references or jumps that are out of range, no illegal |
430 | * instructions, and must end with a RET instruction. | |
1da177e4 | 431 | * |
7b11f69f KK |
432 | * All jumps are forward as they are not signed. |
433 | * | |
434 | * Returns 0 if the rule set is legal or -EINVAL if not. | |
1da177e4 LT |
435 | */ |
436 | int sk_chk_filter(struct sock_filter *filter, int flen) | |
437 | { | |
cba328fc TH |
438 | /* |
439 | * Valid instructions are initialized to non-0. | |
440 | * Invalid instructions are initialized to 0. | |
441 | */ | |
442 | static const u8 codes[] = { | |
8c1592d6 ED |
443 | [BPF_ALU|BPF_ADD|BPF_K] = BPF_S_ALU_ADD_K, |
444 | [BPF_ALU|BPF_ADD|BPF_X] = BPF_S_ALU_ADD_X, | |
445 | [BPF_ALU|BPF_SUB|BPF_K] = BPF_S_ALU_SUB_K, | |
446 | [BPF_ALU|BPF_SUB|BPF_X] = BPF_S_ALU_SUB_X, | |
447 | [BPF_ALU|BPF_MUL|BPF_K] = BPF_S_ALU_MUL_K, | |
448 | [BPF_ALU|BPF_MUL|BPF_X] = BPF_S_ALU_MUL_X, | |
449 | [BPF_ALU|BPF_DIV|BPF_X] = BPF_S_ALU_DIV_X, | |
450 | [BPF_ALU|BPF_AND|BPF_K] = BPF_S_ALU_AND_K, | |
451 | [BPF_ALU|BPF_AND|BPF_X] = BPF_S_ALU_AND_X, | |
452 | [BPF_ALU|BPF_OR|BPF_K] = BPF_S_ALU_OR_K, | |
453 | [BPF_ALU|BPF_OR|BPF_X] = BPF_S_ALU_OR_X, | |
454 | [BPF_ALU|BPF_LSH|BPF_K] = BPF_S_ALU_LSH_K, | |
455 | [BPF_ALU|BPF_LSH|BPF_X] = BPF_S_ALU_LSH_X, | |
456 | [BPF_ALU|BPF_RSH|BPF_K] = BPF_S_ALU_RSH_K, | |
457 | [BPF_ALU|BPF_RSH|BPF_X] = BPF_S_ALU_RSH_X, | |
458 | [BPF_ALU|BPF_NEG] = BPF_S_ALU_NEG, | |
459 | [BPF_LD|BPF_W|BPF_ABS] = BPF_S_LD_W_ABS, | |
460 | [BPF_LD|BPF_H|BPF_ABS] = BPF_S_LD_H_ABS, | |
461 | [BPF_LD|BPF_B|BPF_ABS] = BPF_S_LD_B_ABS, | |
462 | [BPF_LD|BPF_W|BPF_LEN] = BPF_S_LD_W_LEN, | |
463 | [BPF_LD|BPF_W|BPF_IND] = BPF_S_LD_W_IND, | |
464 | [BPF_LD|BPF_H|BPF_IND] = BPF_S_LD_H_IND, | |
465 | [BPF_LD|BPF_B|BPF_IND] = BPF_S_LD_B_IND, | |
466 | [BPF_LD|BPF_IMM] = BPF_S_LD_IMM, | |
467 | [BPF_LDX|BPF_W|BPF_LEN] = BPF_S_LDX_W_LEN, | |
468 | [BPF_LDX|BPF_B|BPF_MSH] = BPF_S_LDX_B_MSH, | |
469 | [BPF_LDX|BPF_IMM] = BPF_S_LDX_IMM, | |
470 | [BPF_MISC|BPF_TAX] = BPF_S_MISC_TAX, | |
471 | [BPF_MISC|BPF_TXA] = BPF_S_MISC_TXA, | |
472 | [BPF_RET|BPF_K] = BPF_S_RET_K, | |
473 | [BPF_RET|BPF_A] = BPF_S_RET_A, | |
474 | [BPF_ALU|BPF_DIV|BPF_K] = BPF_S_ALU_DIV_K, | |
475 | [BPF_LD|BPF_MEM] = BPF_S_LD_MEM, | |
476 | [BPF_LDX|BPF_MEM] = BPF_S_LDX_MEM, | |
477 | [BPF_ST] = BPF_S_ST, | |
478 | [BPF_STX] = BPF_S_STX, | |
479 | [BPF_JMP|BPF_JA] = BPF_S_JMP_JA, | |
480 | [BPF_JMP|BPF_JEQ|BPF_K] = BPF_S_JMP_JEQ_K, | |
481 | [BPF_JMP|BPF_JEQ|BPF_X] = BPF_S_JMP_JEQ_X, | |
482 | [BPF_JMP|BPF_JGE|BPF_K] = BPF_S_JMP_JGE_K, | |
483 | [BPF_JMP|BPF_JGE|BPF_X] = BPF_S_JMP_JGE_X, | |
484 | [BPF_JMP|BPF_JGT|BPF_K] = BPF_S_JMP_JGT_K, | |
485 | [BPF_JMP|BPF_JGT|BPF_X] = BPF_S_JMP_JGT_X, | |
486 | [BPF_JMP|BPF_JSET|BPF_K] = BPF_S_JMP_JSET_K, | |
487 | [BPF_JMP|BPF_JSET|BPF_X] = BPF_S_JMP_JSET_X, | |
cba328fc | 488 | }; |
1da177e4 LT |
489 | int pc; |
490 | ||
1b93ae64 | 491 | if (flen == 0 || flen > BPF_MAXINSNS) |
1da177e4 LT |
492 | return -EINVAL; |
493 | ||
494 | /* check the filter code now */ | |
495 | for (pc = 0; pc < flen; pc++) { | |
cba328fc TH |
496 | struct sock_filter *ftest = &filter[pc]; |
497 | u16 code = ftest->code; | |
93699863 | 498 | |
cba328fc TH |
499 | if (code >= ARRAY_SIZE(codes)) |
500 | return -EINVAL; | |
501 | code = codes[code]; | |
8c1592d6 | 502 | if (!code) |
cba328fc | 503 | return -EINVAL; |
93699863 | 504 | /* Some instructions need special checks */ |
cba328fc TH |
505 | switch (code) { |
506 | case BPF_S_ALU_DIV_K: | |
93699863 KK |
507 | /* check for division by zero */ |
508 | if (ftest->k == 0) | |
1da177e4 | 509 | return -EINVAL; |
c26aed40 | 510 | ftest->k = reciprocal_value(ftest->k); |
93699863 | 511 | break; |
cba328fc TH |
512 | case BPF_S_LD_MEM: |
513 | case BPF_S_LDX_MEM: | |
514 | case BPF_S_ST: | |
515 | case BPF_S_STX: | |
516 | /* check for invalid memory addresses */ | |
93699863 KK |
517 | if (ftest->k >= BPF_MEMWORDS) |
518 | return -EINVAL; | |
519 | break; | |
cba328fc | 520 | case BPF_S_JMP_JA: |
93699863 KK |
521 | /* |
522 | * Note, the large ftest->k might cause loops. | |
523 | * Compare this with conditional jumps below, | |
524 | * where offsets are limited. --ANK (981016) | |
525 | */ | |
526 | if (ftest->k >= (unsigned)(flen-pc-1)) | |
527 | return -EINVAL; | |
01f2f3f6 | 528 | break; |
01f2f3f6 HPP |
529 | case BPF_S_JMP_JEQ_K: |
530 | case BPF_S_JMP_JEQ_X: | |
531 | case BPF_S_JMP_JGE_K: | |
532 | case BPF_S_JMP_JGE_X: | |
533 | case BPF_S_JMP_JGT_K: | |
534 | case BPF_S_JMP_JGT_X: | |
535 | case BPF_S_JMP_JSET_X: | |
536 | case BPF_S_JMP_JSET_K: | |
cba328fc | 537 | /* for conditionals both must be safe */ |
e35bedf3 | 538 | if (pc + ftest->jt + 1 >= flen || |
93699863 KK |
539 | pc + ftest->jf + 1 >= flen) |
540 | return -EINVAL; | |
cba328fc | 541 | break; |
01f2f3f6 | 542 | } |
cba328fc | 543 | ftest->code = code; |
01f2f3f6 | 544 | } |
93699863 | 545 | |
01f2f3f6 HPP |
546 | /* last instruction must be a RET code */ |
547 | switch (filter[flen - 1].code) { | |
548 | case BPF_S_RET_K: | |
549 | case BPF_S_RET_A: | |
550 | return 0; | |
cba328fc TH |
551 | } |
552 | return -EINVAL; | |
1da177e4 | 553 | } |
b715631f | 554 | EXPORT_SYMBOL(sk_chk_filter); |
1da177e4 | 555 | |
47e958ea | 556 | /** |
0302b862 | 557 | * sk_filter_rcu_release - Release a socket filter by rcu_head |
47e958ea PE |
558 | * @rcu: rcu_head that contains the sk_filter to free |
559 | */ | |
560 | static void sk_filter_rcu_release(struct rcu_head *rcu) | |
561 | { | |
562 | struct sk_filter *fp = container_of(rcu, struct sk_filter, rcu); | |
563 | ||
564 | sk_filter_release(fp); | |
565 | } | |
566 | ||
567 | static void sk_filter_delayed_uncharge(struct sock *sk, struct sk_filter *fp) | |
568 | { | |
569 | unsigned int size = sk_filter_len(fp); | |
570 | ||
571 | atomic_sub(size, &sk->sk_omem_alloc); | |
572 | call_rcu_bh(&fp->rcu, sk_filter_rcu_release); | |
573 | } | |
574 | ||
1da177e4 LT |
575 | /** |
576 | * sk_attach_filter - attach a socket filter | |
577 | * @fprog: the filter program | |
578 | * @sk: the socket to use | |
579 | * | |
580 | * Attach the user's filter code. We first run some sanity checks on | |
581 | * it to make sure it does not explode on us later. If an error | |
582 | * occurs or there is insufficient memory for the filter a negative | |
583 | * errno code is returned. On success the return is zero. | |
584 | */ | |
585 | int sk_attach_filter(struct sock_fprog *fprog, struct sock *sk) | |
586 | { | |
d3904b73 | 587 | struct sk_filter *fp, *old_fp; |
1da177e4 LT |
588 | unsigned int fsize = sizeof(struct sock_filter) * fprog->len; |
589 | int err; | |
590 | ||
591 | /* Make sure new filter is there and in the right amounts. */ | |
e35bedf3 KK |
592 | if (fprog->filter == NULL) |
593 | return -EINVAL; | |
1da177e4 LT |
594 | |
595 | fp = sock_kmalloc(sk, fsize+sizeof(*fp), GFP_KERNEL); | |
596 | if (!fp) | |
597 | return -ENOMEM; | |
598 | if (copy_from_user(fp->insns, fprog->filter, fsize)) { | |
4ec93edb | 599 | sock_kfree_s(sk, fp, fsize+sizeof(*fp)); |
1da177e4 LT |
600 | return -EFAULT; |
601 | } | |
602 | ||
603 | atomic_set(&fp->refcnt, 1); | |
604 | fp->len = fprog->len; | |
605 | ||
606 | err = sk_chk_filter(fp->insns, fp->len); | |
d3904b73 PE |
607 | if (err) { |
608 | sk_filter_uncharge(sk, fp); | |
609 | return err; | |
1da177e4 LT |
610 | } |
611 | ||
f91ff5b9 ED |
612 | old_fp = rcu_dereference_protected(sk->sk_filter, |
613 | sock_owned_by_user(sk)); | |
d3904b73 | 614 | rcu_assign_pointer(sk->sk_filter, fp); |
d3904b73 | 615 | |
9b013e05 OJ |
616 | if (old_fp) |
617 | sk_filter_delayed_uncharge(sk, old_fp); | |
d3904b73 | 618 | return 0; |
1da177e4 | 619 | } |
5ff3f073 | 620 | EXPORT_SYMBOL_GPL(sk_attach_filter); |
1da177e4 | 621 | |
55b33325 PE |
622 | int sk_detach_filter(struct sock *sk) |
623 | { | |
624 | int ret = -ENOENT; | |
625 | struct sk_filter *filter; | |
626 | ||
f91ff5b9 ED |
627 | filter = rcu_dereference_protected(sk->sk_filter, |
628 | sock_owned_by_user(sk)); | |
55b33325 PE |
629 | if (filter) { |
630 | rcu_assign_pointer(sk->sk_filter, NULL); | |
47e958ea | 631 | sk_filter_delayed_uncharge(sk, filter); |
55b33325 PE |
632 | ret = 0; |
633 | } | |
55b33325 PE |
634 | return ret; |
635 | } | |
5ff3f073 | 636 | EXPORT_SYMBOL_GPL(sk_detach_filter); |