Commit | Line | Data |
---|---|---|
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> |
86e4ca66 | 41 | #include <linux/ratelimit.h> |
1da177e4 LT |
42 | |
43 | /* No hurry in this branch */ | |
4bc65dd8 | 44 | static void *__load_pointer(const struct sk_buff *skb, int k, unsigned int size) |
1da177e4 LT |
45 | { |
46 | u8 *ptr = NULL; | |
47 | ||
48 | if (k >= SKF_NET_OFF) | |
d56f90a7 | 49 | ptr = skb_network_header(skb) + k - SKF_NET_OFF; |
1da177e4 | 50 | else if (k >= SKF_LL_OFF) |
98e399f8 | 51 | ptr = skb_mac_header(skb) + k - SKF_LL_OFF; |
1da177e4 | 52 | |
4bc65dd8 | 53 | if (ptr >= skb->head && ptr + size <= skb_tail_pointer(skb)) |
1da177e4 LT |
54 | return ptr; |
55 | return NULL; | |
56 | } | |
57 | ||
62ab0812 | 58 | static inline void *load_pointer(const struct sk_buff *skb, int k, |
4ec93edb | 59 | unsigned int size, void *buffer) |
0b05b2a4 PM |
60 | { |
61 | if (k >= 0) | |
62 | return skb_header_pointer(skb, k, size, buffer); | |
12b16dad | 63 | return __load_pointer(skb, k, size); |
0b05b2a4 PM |
64 | } |
65 | ||
43db6d65 SH |
66 | /** |
67 | * sk_filter - run a packet through a socket filter | |
68 | * @sk: sock associated with &sk_buff | |
69 | * @skb: buffer to filter | |
43db6d65 SH |
70 | * |
71 | * Run the filter code and then cut skb->data to correct size returned by | |
72 | * sk_run_filter. If pkt_len is 0 we toss packet. If skb->len is smaller | |
73 | * than pkt_len we keep whole skb->data. This is the socket level | |
74 | * wrapper to sk_run_filter. It returns 0 if the packet should | |
75 | * be accepted or -EPERM if the packet should be tossed. | |
76 | * | |
77 | */ | |
78 | int sk_filter(struct sock *sk, struct sk_buff *skb) | |
79 | { | |
80 | int err; | |
81 | struct sk_filter *filter; | |
82 | ||
83 | err = security_sock_rcv_skb(sk, skb); | |
84 | if (err) | |
85 | return err; | |
86 | ||
80f8f102 ED |
87 | rcu_read_lock(); |
88 | filter = rcu_dereference(sk->sk_filter); | |
43db6d65 | 89 | if (filter) { |
0a14842f | 90 | unsigned int pkt_len = SK_RUN_FILTER(filter, skb); |
0d7da9dd | 91 | |
43db6d65 SH |
92 | err = pkt_len ? pskb_trim(skb, pkt_len) : -EPERM; |
93 | } | |
80f8f102 | 94 | rcu_read_unlock(); |
43db6d65 SH |
95 | |
96 | return err; | |
97 | } | |
98 | EXPORT_SYMBOL(sk_filter); | |
99 | ||
1da177e4 | 100 | /** |
2966b66c | 101 | * sk_run_filter - run a filter on a socket |
1da177e4 | 102 | * @skb: buffer to run the filter on |
697d0e33 | 103 | * @fentry: filter to apply |
1da177e4 LT |
104 | * |
105 | * Decode and apply filter instructions to the skb->data. | |
93aaae2e ED |
106 | * Return length to keep, 0 for none. @skb is the data we are |
107 | * filtering, @filter is the array of filter instructions. | |
108 | * Because all jumps are guaranteed to be before last instruction, | |
109 | * and last instruction guaranteed to be a RET, we dont need to check | |
110 | * flen. (We used to pass to this function the length of filter) | |
1da177e4 | 111 | */ |
62ab0812 ED |
112 | unsigned int sk_run_filter(const struct sk_buff *skb, |
113 | const struct sock_filter *fentry) | |
1da177e4 | 114 | { |
0b05b2a4 | 115 | void *ptr; |
2966b66c KK |
116 | u32 A = 0; /* Accumulator */ |
117 | u32 X = 0; /* Index Register */ | |
1da177e4 | 118 | u32 mem[BPF_MEMWORDS]; /* Scratch Memory Store */ |
0b05b2a4 | 119 | u32 tmp; |
1da177e4 | 120 | int k; |
1da177e4 LT |
121 | |
122 | /* | |
123 | * Process array of filter instructions. | |
124 | */ | |
93aaae2e ED |
125 | for (;; fentry++) { |
126 | #if defined(CONFIG_X86_32) | |
127 | #define K (fentry->k) | |
128 | #else | |
129 | const u32 K = fentry->k; | |
130 | #endif | |
4ec93edb | 131 | |
1da177e4 | 132 | switch (fentry->code) { |
01f2f3f6 | 133 | case BPF_S_ALU_ADD_X: |
1da177e4 LT |
134 | A += X; |
135 | continue; | |
01f2f3f6 | 136 | case BPF_S_ALU_ADD_K: |
93aaae2e | 137 | A += K; |
1da177e4 | 138 | continue; |
01f2f3f6 | 139 | case BPF_S_ALU_SUB_X: |
1da177e4 LT |
140 | A -= X; |
141 | continue; | |
01f2f3f6 | 142 | case BPF_S_ALU_SUB_K: |
93aaae2e | 143 | A -= K; |
1da177e4 | 144 | continue; |
01f2f3f6 | 145 | case BPF_S_ALU_MUL_X: |
1da177e4 LT |
146 | A *= X; |
147 | continue; | |
01f2f3f6 | 148 | case BPF_S_ALU_MUL_K: |
93aaae2e | 149 | A *= K; |
1da177e4 | 150 | continue; |
01f2f3f6 | 151 | case BPF_S_ALU_DIV_X: |
1da177e4 LT |
152 | if (X == 0) |
153 | return 0; | |
154 | A /= X; | |
155 | continue; | |
01f2f3f6 | 156 | case BPF_S_ALU_DIV_K: |
c26aed40 | 157 | A = reciprocal_divide(A, K); |
1da177e4 | 158 | continue; |
01f2f3f6 | 159 | case BPF_S_ALU_AND_X: |
1da177e4 LT |
160 | A &= X; |
161 | continue; | |
01f2f3f6 | 162 | case BPF_S_ALU_AND_K: |
93aaae2e | 163 | A &= K; |
1da177e4 | 164 | continue; |
01f2f3f6 | 165 | case BPF_S_ALU_OR_X: |
1da177e4 LT |
166 | A |= X; |
167 | continue; | |
01f2f3f6 | 168 | case BPF_S_ALU_OR_K: |
93aaae2e | 169 | A |= K; |
1da177e4 | 170 | continue; |
01f2f3f6 | 171 | case BPF_S_ALU_LSH_X: |
1da177e4 LT |
172 | A <<= X; |
173 | continue; | |
01f2f3f6 | 174 | case BPF_S_ALU_LSH_K: |
93aaae2e | 175 | A <<= K; |
1da177e4 | 176 | continue; |
01f2f3f6 | 177 | case BPF_S_ALU_RSH_X: |
1da177e4 LT |
178 | A >>= X; |
179 | continue; | |
01f2f3f6 | 180 | case BPF_S_ALU_RSH_K: |
93aaae2e | 181 | A >>= K; |
1da177e4 | 182 | continue; |
01f2f3f6 | 183 | case BPF_S_ALU_NEG: |
1da177e4 LT |
184 | A = -A; |
185 | continue; | |
01f2f3f6 | 186 | case BPF_S_JMP_JA: |
93aaae2e | 187 | fentry += K; |
1da177e4 | 188 | continue; |
01f2f3f6 | 189 | case BPF_S_JMP_JGT_K: |
93aaae2e | 190 | fentry += (A > K) ? fentry->jt : fentry->jf; |
1da177e4 | 191 | continue; |
01f2f3f6 | 192 | case BPF_S_JMP_JGE_K: |
93aaae2e | 193 | fentry += (A >= K) ? fentry->jt : fentry->jf; |
1da177e4 | 194 | continue; |
01f2f3f6 | 195 | case BPF_S_JMP_JEQ_K: |
93aaae2e | 196 | fentry += (A == K) ? fentry->jt : fentry->jf; |
1da177e4 | 197 | continue; |
01f2f3f6 | 198 | case BPF_S_JMP_JSET_K: |
93aaae2e | 199 | fentry += (A & K) ? fentry->jt : fentry->jf; |
1da177e4 | 200 | continue; |
01f2f3f6 | 201 | case BPF_S_JMP_JGT_X: |
93aaae2e | 202 | fentry += (A > X) ? fentry->jt : fentry->jf; |
1da177e4 | 203 | continue; |
01f2f3f6 | 204 | case BPF_S_JMP_JGE_X: |
93aaae2e | 205 | fentry += (A >= X) ? fentry->jt : fentry->jf; |
1da177e4 | 206 | continue; |
01f2f3f6 | 207 | case BPF_S_JMP_JEQ_X: |
93aaae2e | 208 | fentry += (A == X) ? fentry->jt : fentry->jf; |
1da177e4 | 209 | continue; |
01f2f3f6 | 210 | case BPF_S_JMP_JSET_X: |
93aaae2e | 211 | fentry += (A & X) ? fentry->jt : fentry->jf; |
1da177e4 | 212 | continue; |
01f2f3f6 | 213 | case BPF_S_LD_W_ABS: |
93aaae2e | 214 | k = K; |
e35bedf3 | 215 | load_w: |
0b05b2a4 PM |
216 | ptr = load_pointer(skb, k, 4, &tmp); |
217 | if (ptr != NULL) { | |
d3e2ce3b | 218 | A = get_unaligned_be32(ptr); |
0b05b2a4 | 219 | continue; |
1da177e4 | 220 | } |
12b16dad | 221 | return 0; |
01f2f3f6 | 222 | case BPF_S_LD_H_ABS: |
93aaae2e | 223 | k = K; |
e35bedf3 | 224 | load_h: |
0b05b2a4 PM |
225 | ptr = load_pointer(skb, k, 2, &tmp); |
226 | if (ptr != NULL) { | |
d3e2ce3b | 227 | A = get_unaligned_be16(ptr); |
0b05b2a4 | 228 | continue; |
1da177e4 | 229 | } |
12b16dad | 230 | return 0; |
01f2f3f6 | 231 | case BPF_S_LD_B_ABS: |
93aaae2e | 232 | k = K; |
1da177e4 | 233 | load_b: |
0b05b2a4 PM |
234 | ptr = load_pointer(skb, k, 1, &tmp); |
235 | if (ptr != NULL) { | |
236 | A = *(u8 *)ptr; | |
237 | continue; | |
1da177e4 | 238 | } |
12b16dad | 239 | return 0; |
01f2f3f6 | 240 | case BPF_S_LD_W_LEN: |
3154e540 | 241 | A = skb->len; |
1da177e4 | 242 | continue; |
01f2f3f6 | 243 | case BPF_S_LDX_W_LEN: |
3154e540 | 244 | X = skb->len; |
1da177e4 | 245 | continue; |
01f2f3f6 | 246 | case BPF_S_LD_W_IND: |
93aaae2e | 247 | k = X + K; |
1da177e4 | 248 | goto load_w; |
01f2f3f6 | 249 | case BPF_S_LD_H_IND: |
93aaae2e | 250 | k = X + K; |
1da177e4 | 251 | goto load_h; |
01f2f3f6 | 252 | case BPF_S_LD_B_IND: |
93aaae2e | 253 | k = X + K; |
1da177e4 | 254 | goto load_b; |
01f2f3f6 | 255 | case BPF_S_LDX_B_MSH: |
93aaae2e | 256 | ptr = load_pointer(skb, K, 1, &tmp); |
0b05b2a4 PM |
257 | if (ptr != NULL) { |
258 | X = (*(u8 *)ptr & 0xf) << 2; | |
259 | continue; | |
260 | } | |
261 | return 0; | |
01f2f3f6 | 262 | case BPF_S_LD_IMM: |
93aaae2e | 263 | A = K; |
1da177e4 | 264 | continue; |
01f2f3f6 | 265 | case BPF_S_LDX_IMM: |
93aaae2e | 266 | X = K; |
1da177e4 | 267 | continue; |
01f2f3f6 | 268 | case BPF_S_LD_MEM: |
2d5311e4 | 269 | A = mem[K]; |
1da177e4 | 270 | continue; |
01f2f3f6 | 271 | case BPF_S_LDX_MEM: |
2d5311e4 | 272 | X = mem[K]; |
1da177e4 | 273 | continue; |
01f2f3f6 | 274 | case BPF_S_MISC_TAX: |
1da177e4 LT |
275 | X = A; |
276 | continue; | |
01f2f3f6 | 277 | case BPF_S_MISC_TXA: |
1da177e4 LT |
278 | A = X; |
279 | continue; | |
01f2f3f6 | 280 | case BPF_S_RET_K: |
93aaae2e | 281 | return K; |
01f2f3f6 | 282 | case BPF_S_RET_A: |
4bad4dc9 | 283 | return A; |
01f2f3f6 | 284 | case BPF_S_ST: |
93aaae2e | 285 | mem[K] = A; |
1da177e4 | 286 | continue; |
01f2f3f6 | 287 | case BPF_S_STX: |
93aaae2e | 288 | mem[K] = X; |
1da177e4 | 289 | continue; |
12b16dad | 290 | case BPF_S_ANC_PROTOCOL: |
252e3346 | 291 | A = ntohs(skb->protocol); |
1da177e4 | 292 | continue; |
12b16dad | 293 | case BPF_S_ANC_PKTTYPE: |
1da177e4 LT |
294 | A = skb->pkt_type; |
295 | continue; | |
12b16dad | 296 | case BPF_S_ANC_IFINDEX: |
40eaf962 PLE |
297 | if (!skb->dev) |
298 | return 0; | |
1da177e4 LT |
299 | A = skb->dev->ifindex; |
300 | continue; | |
12b16dad | 301 | case BPF_S_ANC_MARK: |
7e75f93e | 302 | A = skb->mark; |
303 | continue; | |
12b16dad | 304 | case BPF_S_ANC_QUEUE: |
d19742fb ED |
305 | A = skb->queue_mapping; |
306 | continue; | |
12b16dad | 307 | case BPF_S_ANC_HATYPE: |
40eaf962 PLE |
308 | if (!skb->dev) |
309 | return 0; | |
310 | A = skb->dev->type; | |
311 | continue; | |
12b16dad | 312 | case BPF_S_ANC_RXHASH: |
da2033c2 ED |
313 | A = skb->rxhash; |
314 | continue; | |
12b16dad | 315 | case BPF_S_ANC_CPU: |
da2033c2 ED |
316 | A = raw_smp_processor_id(); |
317 | continue; | |
12b16dad | 318 | case BPF_S_ANC_NLATTR: { |
4738c1db PM |
319 | struct nlattr *nla; |
320 | ||
321 | if (skb_is_nonlinear(skb)) | |
322 | return 0; | |
323 | if (A > skb->len - sizeof(struct nlattr)) | |
324 | return 0; | |
325 | ||
326 | nla = nla_find((struct nlattr *)&skb->data[A], | |
327 | skb->len - A, X); | |
328 | if (nla) | |
329 | A = (void *)nla - (void *)skb->data; | |
330 | else | |
331 | A = 0; | |
332 | continue; | |
333 | } | |
12b16dad | 334 | case BPF_S_ANC_NLATTR_NEST: { |
d214c753 PNA |
335 | struct nlattr *nla; |
336 | ||
337 | if (skb_is_nonlinear(skb)) | |
338 | return 0; | |
339 | if (A > skb->len - sizeof(struct nlattr)) | |
340 | return 0; | |
341 | ||
342 | nla = (struct nlattr *)&skb->data[A]; | |
343 | if (nla->nla_len > A - skb->len) | |
344 | return 0; | |
345 | ||
346 | nla = nla_find_nested(nla, X); | |
347 | if (nla) | |
348 | A = (void *)nla - (void *)skb->data; | |
349 | else | |
350 | A = 0; | |
351 | continue; | |
352 | } | |
1da177e4 | 353 | default: |
6c4a5cb2 JP |
354 | WARN_RATELIMIT(1, "Unknown code:%u jt:%u tf:%u k:%u\n", |
355 | fentry->code, fentry->jt, | |
356 | fentry->jf, fentry->k); | |
1da177e4 LT |
357 | return 0; |
358 | } | |
359 | } | |
360 | ||
361 | return 0; | |
362 | } | |
b715631f | 363 | EXPORT_SYMBOL(sk_run_filter); |
1da177e4 | 364 | |
2d5311e4 ED |
365 | /* |
366 | * Security : | |
367 | * A BPF program is able to use 16 cells of memory to store intermediate | |
368 | * values (check u32 mem[BPF_MEMWORDS] in sk_run_filter()) | |
369 | * As we dont want to clear mem[] array for each packet going through | |
370 | * sk_run_filter(), we check that filter loaded by user never try to read | |
371 | * a cell if not previously written, and we check all branches to be sure | |
25985edc | 372 | * a malicious user doesn't try to abuse us. |
2d5311e4 ED |
373 | */ |
374 | static int check_load_and_stores(struct sock_filter *filter, int flen) | |
375 | { | |
376 | u16 *masks, memvalid = 0; /* one bit per cell, 16 cells */ | |
377 | int pc, ret = 0; | |
378 | ||
379 | BUILD_BUG_ON(BPF_MEMWORDS > 16); | |
380 | masks = kmalloc(flen * sizeof(*masks), GFP_KERNEL); | |
381 | if (!masks) | |
382 | return -ENOMEM; | |
383 | memset(masks, 0xff, flen * sizeof(*masks)); | |
384 | ||
385 | for (pc = 0; pc < flen; pc++) { | |
386 | memvalid &= masks[pc]; | |
387 | ||
388 | switch (filter[pc].code) { | |
389 | case BPF_S_ST: | |
390 | case BPF_S_STX: | |
391 | memvalid |= (1 << filter[pc].k); | |
392 | break; | |
393 | case BPF_S_LD_MEM: | |
394 | case BPF_S_LDX_MEM: | |
395 | if (!(memvalid & (1 << filter[pc].k))) { | |
396 | ret = -EINVAL; | |
397 | goto error; | |
398 | } | |
399 | break; | |
400 | case BPF_S_JMP_JA: | |
401 | /* a jump must set masks on target */ | |
402 | masks[pc + 1 + filter[pc].k] &= memvalid; | |
403 | memvalid = ~0; | |
404 | break; | |
405 | case BPF_S_JMP_JEQ_K: | |
406 | case BPF_S_JMP_JEQ_X: | |
407 | case BPF_S_JMP_JGE_K: | |
408 | case BPF_S_JMP_JGE_X: | |
409 | case BPF_S_JMP_JGT_K: | |
410 | case BPF_S_JMP_JGT_X: | |
411 | case BPF_S_JMP_JSET_X: | |
412 | case BPF_S_JMP_JSET_K: | |
413 | /* a jump must set masks on targets */ | |
414 | masks[pc + 1 + filter[pc].jt] &= memvalid; | |
415 | masks[pc + 1 + filter[pc].jf] &= memvalid; | |
416 | memvalid = ~0; | |
417 | break; | |
418 | } | |
419 | } | |
420 | error: | |
421 | kfree(masks); | |
422 | return ret; | |
423 | } | |
424 | ||
1da177e4 LT |
425 | /** |
426 | * sk_chk_filter - verify socket filter code | |
427 | * @filter: filter to verify | |
428 | * @flen: length of filter | |
429 | * | |
430 | * Check the user's filter code. If we let some ugly | |
431 | * filter code slip through kaboom! The filter must contain | |
93699863 KK |
432 | * no references or jumps that are out of range, no illegal |
433 | * instructions, and must end with a RET instruction. | |
1da177e4 | 434 | * |
7b11f69f KK |
435 | * All jumps are forward as they are not signed. |
436 | * | |
437 | * Returns 0 if the rule set is legal or -EINVAL if not. | |
1da177e4 LT |
438 | */ |
439 | int sk_chk_filter(struct sock_filter *filter, int flen) | |
440 | { | |
cba328fc TH |
441 | /* |
442 | * Valid instructions are initialized to non-0. | |
443 | * Invalid instructions are initialized to 0. | |
444 | */ | |
445 | static const u8 codes[] = { | |
8c1592d6 ED |
446 | [BPF_ALU|BPF_ADD|BPF_K] = BPF_S_ALU_ADD_K, |
447 | [BPF_ALU|BPF_ADD|BPF_X] = BPF_S_ALU_ADD_X, | |
448 | [BPF_ALU|BPF_SUB|BPF_K] = BPF_S_ALU_SUB_K, | |
449 | [BPF_ALU|BPF_SUB|BPF_X] = BPF_S_ALU_SUB_X, | |
450 | [BPF_ALU|BPF_MUL|BPF_K] = BPF_S_ALU_MUL_K, | |
451 | [BPF_ALU|BPF_MUL|BPF_X] = BPF_S_ALU_MUL_X, | |
452 | [BPF_ALU|BPF_DIV|BPF_X] = BPF_S_ALU_DIV_X, | |
453 | [BPF_ALU|BPF_AND|BPF_K] = BPF_S_ALU_AND_K, | |
454 | [BPF_ALU|BPF_AND|BPF_X] = BPF_S_ALU_AND_X, | |
455 | [BPF_ALU|BPF_OR|BPF_K] = BPF_S_ALU_OR_K, | |
456 | [BPF_ALU|BPF_OR|BPF_X] = BPF_S_ALU_OR_X, | |
457 | [BPF_ALU|BPF_LSH|BPF_K] = BPF_S_ALU_LSH_K, | |
458 | [BPF_ALU|BPF_LSH|BPF_X] = BPF_S_ALU_LSH_X, | |
459 | [BPF_ALU|BPF_RSH|BPF_K] = BPF_S_ALU_RSH_K, | |
460 | [BPF_ALU|BPF_RSH|BPF_X] = BPF_S_ALU_RSH_X, | |
461 | [BPF_ALU|BPF_NEG] = BPF_S_ALU_NEG, | |
462 | [BPF_LD|BPF_W|BPF_ABS] = BPF_S_LD_W_ABS, | |
463 | [BPF_LD|BPF_H|BPF_ABS] = BPF_S_LD_H_ABS, | |
464 | [BPF_LD|BPF_B|BPF_ABS] = BPF_S_LD_B_ABS, | |
465 | [BPF_LD|BPF_W|BPF_LEN] = BPF_S_LD_W_LEN, | |
466 | [BPF_LD|BPF_W|BPF_IND] = BPF_S_LD_W_IND, | |
467 | [BPF_LD|BPF_H|BPF_IND] = BPF_S_LD_H_IND, | |
468 | [BPF_LD|BPF_B|BPF_IND] = BPF_S_LD_B_IND, | |
469 | [BPF_LD|BPF_IMM] = BPF_S_LD_IMM, | |
470 | [BPF_LDX|BPF_W|BPF_LEN] = BPF_S_LDX_W_LEN, | |
471 | [BPF_LDX|BPF_B|BPF_MSH] = BPF_S_LDX_B_MSH, | |
472 | [BPF_LDX|BPF_IMM] = BPF_S_LDX_IMM, | |
473 | [BPF_MISC|BPF_TAX] = BPF_S_MISC_TAX, | |
474 | [BPF_MISC|BPF_TXA] = BPF_S_MISC_TXA, | |
475 | [BPF_RET|BPF_K] = BPF_S_RET_K, | |
476 | [BPF_RET|BPF_A] = BPF_S_RET_A, | |
477 | [BPF_ALU|BPF_DIV|BPF_K] = BPF_S_ALU_DIV_K, | |
478 | [BPF_LD|BPF_MEM] = BPF_S_LD_MEM, | |
479 | [BPF_LDX|BPF_MEM] = BPF_S_LDX_MEM, | |
480 | [BPF_ST] = BPF_S_ST, | |
481 | [BPF_STX] = BPF_S_STX, | |
482 | [BPF_JMP|BPF_JA] = BPF_S_JMP_JA, | |
483 | [BPF_JMP|BPF_JEQ|BPF_K] = BPF_S_JMP_JEQ_K, | |
484 | [BPF_JMP|BPF_JEQ|BPF_X] = BPF_S_JMP_JEQ_X, | |
485 | [BPF_JMP|BPF_JGE|BPF_K] = BPF_S_JMP_JGE_K, | |
486 | [BPF_JMP|BPF_JGE|BPF_X] = BPF_S_JMP_JGE_X, | |
487 | [BPF_JMP|BPF_JGT|BPF_K] = BPF_S_JMP_JGT_K, | |
488 | [BPF_JMP|BPF_JGT|BPF_X] = BPF_S_JMP_JGT_X, | |
489 | [BPF_JMP|BPF_JSET|BPF_K] = BPF_S_JMP_JSET_K, | |
490 | [BPF_JMP|BPF_JSET|BPF_X] = BPF_S_JMP_JSET_X, | |
cba328fc | 491 | }; |
1da177e4 LT |
492 | int pc; |
493 | ||
1b93ae64 | 494 | if (flen == 0 || flen > BPF_MAXINSNS) |
1da177e4 LT |
495 | return -EINVAL; |
496 | ||
497 | /* check the filter code now */ | |
498 | for (pc = 0; pc < flen; pc++) { | |
cba328fc TH |
499 | struct sock_filter *ftest = &filter[pc]; |
500 | u16 code = ftest->code; | |
93699863 | 501 | |
cba328fc TH |
502 | if (code >= ARRAY_SIZE(codes)) |
503 | return -EINVAL; | |
504 | code = codes[code]; | |
8c1592d6 | 505 | if (!code) |
cba328fc | 506 | return -EINVAL; |
93699863 | 507 | /* Some instructions need special checks */ |
cba328fc TH |
508 | switch (code) { |
509 | case BPF_S_ALU_DIV_K: | |
93699863 KK |
510 | /* check for division by zero */ |
511 | if (ftest->k == 0) | |
1da177e4 | 512 | return -EINVAL; |
c26aed40 | 513 | ftest->k = reciprocal_value(ftest->k); |
93699863 | 514 | break; |
cba328fc TH |
515 | case BPF_S_LD_MEM: |
516 | case BPF_S_LDX_MEM: | |
517 | case BPF_S_ST: | |
518 | case BPF_S_STX: | |
519 | /* check for invalid memory addresses */ | |
93699863 KK |
520 | if (ftest->k >= BPF_MEMWORDS) |
521 | return -EINVAL; | |
522 | break; | |
cba328fc | 523 | case BPF_S_JMP_JA: |
93699863 KK |
524 | /* |
525 | * Note, the large ftest->k might cause loops. | |
526 | * Compare this with conditional jumps below, | |
527 | * where offsets are limited. --ANK (981016) | |
528 | */ | |
529 | if (ftest->k >= (unsigned)(flen-pc-1)) | |
530 | return -EINVAL; | |
01f2f3f6 | 531 | break; |
01f2f3f6 HPP |
532 | case BPF_S_JMP_JEQ_K: |
533 | case BPF_S_JMP_JEQ_X: | |
534 | case BPF_S_JMP_JGE_K: | |
535 | case BPF_S_JMP_JGE_X: | |
536 | case BPF_S_JMP_JGT_K: | |
537 | case BPF_S_JMP_JGT_X: | |
538 | case BPF_S_JMP_JSET_X: | |
539 | case BPF_S_JMP_JSET_K: | |
cba328fc | 540 | /* for conditionals both must be safe */ |
e35bedf3 | 541 | if (pc + ftest->jt + 1 >= flen || |
93699863 KK |
542 | pc + ftest->jf + 1 >= flen) |
543 | return -EINVAL; | |
cba328fc | 544 | break; |
12b16dad ED |
545 | case BPF_S_LD_W_ABS: |
546 | case BPF_S_LD_H_ABS: | |
547 | case BPF_S_LD_B_ABS: | |
548 | #define ANCILLARY(CODE) case SKF_AD_OFF + SKF_AD_##CODE: \ | |
549 | code = BPF_S_ANC_##CODE; \ | |
550 | break | |
551 | switch (ftest->k) { | |
552 | ANCILLARY(PROTOCOL); | |
553 | ANCILLARY(PKTTYPE); | |
554 | ANCILLARY(IFINDEX); | |
555 | ANCILLARY(NLATTR); | |
556 | ANCILLARY(NLATTR_NEST); | |
557 | ANCILLARY(MARK); | |
558 | ANCILLARY(QUEUE); | |
559 | ANCILLARY(HATYPE); | |
560 | ANCILLARY(RXHASH); | |
561 | ANCILLARY(CPU); | |
562 | } | |
01f2f3f6 | 563 | } |
cba328fc | 564 | ftest->code = code; |
01f2f3f6 | 565 | } |
93699863 | 566 | |
01f2f3f6 HPP |
567 | /* last instruction must be a RET code */ |
568 | switch (filter[flen - 1].code) { | |
569 | case BPF_S_RET_K: | |
570 | case BPF_S_RET_A: | |
2d5311e4 | 571 | return check_load_and_stores(filter, flen); |
cba328fc TH |
572 | } |
573 | return -EINVAL; | |
1da177e4 | 574 | } |
b715631f | 575 | EXPORT_SYMBOL(sk_chk_filter); |
1da177e4 | 576 | |
47e958ea | 577 | /** |
46bcf14f | 578 | * sk_filter_release_rcu - Release a socket filter by rcu_head |
47e958ea PE |
579 | * @rcu: rcu_head that contains the sk_filter to free |
580 | */ | |
46bcf14f | 581 | void sk_filter_release_rcu(struct rcu_head *rcu) |
47e958ea PE |
582 | { |
583 | struct sk_filter *fp = container_of(rcu, struct sk_filter, rcu); | |
584 | ||
0a14842f | 585 | bpf_jit_free(fp); |
46bcf14f | 586 | kfree(fp); |
47e958ea | 587 | } |
46bcf14f | 588 | EXPORT_SYMBOL(sk_filter_release_rcu); |
47e958ea | 589 | |
1da177e4 LT |
590 | /** |
591 | * sk_attach_filter - attach a socket filter | |
592 | * @fprog: the filter program | |
593 | * @sk: the socket to use | |
594 | * | |
595 | * Attach the user's filter code. We first run some sanity checks on | |
596 | * it to make sure it does not explode on us later. If an error | |
597 | * occurs or there is insufficient memory for the filter a negative | |
598 | * errno code is returned. On success the return is zero. | |
599 | */ | |
600 | int sk_attach_filter(struct sock_fprog *fprog, struct sock *sk) | |
601 | { | |
d3904b73 | 602 | struct sk_filter *fp, *old_fp; |
1da177e4 LT |
603 | unsigned int fsize = sizeof(struct sock_filter) * fprog->len; |
604 | int err; | |
605 | ||
606 | /* Make sure new filter is there and in the right amounts. */ | |
e35bedf3 KK |
607 | if (fprog->filter == NULL) |
608 | return -EINVAL; | |
1da177e4 LT |
609 | |
610 | fp = sock_kmalloc(sk, fsize+sizeof(*fp), GFP_KERNEL); | |
611 | if (!fp) | |
612 | return -ENOMEM; | |
613 | if (copy_from_user(fp->insns, fprog->filter, fsize)) { | |
4ec93edb | 614 | sock_kfree_s(sk, fp, fsize+sizeof(*fp)); |
1da177e4 LT |
615 | return -EFAULT; |
616 | } | |
617 | ||
618 | atomic_set(&fp->refcnt, 1); | |
619 | fp->len = fprog->len; | |
0a14842f | 620 | fp->bpf_func = sk_run_filter; |
1da177e4 LT |
621 | |
622 | err = sk_chk_filter(fp->insns, fp->len); | |
d3904b73 PE |
623 | if (err) { |
624 | sk_filter_uncharge(sk, fp); | |
625 | return err; | |
1da177e4 LT |
626 | } |
627 | ||
0a14842f ED |
628 | bpf_jit_compile(fp); |
629 | ||
f91ff5b9 ED |
630 | old_fp = rcu_dereference_protected(sk->sk_filter, |
631 | sock_owned_by_user(sk)); | |
d3904b73 | 632 | rcu_assign_pointer(sk->sk_filter, fp); |
d3904b73 | 633 | |
9b013e05 | 634 | if (old_fp) |
46bcf14f | 635 | sk_filter_uncharge(sk, old_fp); |
d3904b73 | 636 | return 0; |
1da177e4 | 637 | } |
5ff3f073 | 638 | EXPORT_SYMBOL_GPL(sk_attach_filter); |
1da177e4 | 639 | |
55b33325 PE |
640 | int sk_detach_filter(struct sock *sk) |
641 | { | |
642 | int ret = -ENOENT; | |
643 | struct sk_filter *filter; | |
644 | ||
f91ff5b9 ED |
645 | filter = rcu_dereference_protected(sk->sk_filter, |
646 | sock_owned_by_user(sk)); | |
55b33325 PE |
647 | if (filter) { |
648 | rcu_assign_pointer(sk->sk_filter, NULL); | |
46bcf14f | 649 | sk_filter_uncharge(sk, filter); |
55b33325 PE |
650 | ret = 0; |
651 | } | |
55b33325 PE |
652 | return ret; |
653 | } | |
5ff3f073 | 654 | EXPORT_SYMBOL_GPL(sk_detach_filter); |