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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 LT |
39 | #include <linux/filter.h> |
40 | ||
41 | /* No hurry in this branch */ | |
0b05b2a4 | 42 | static void *__load_pointer(struct sk_buff *skb, int k) |
1da177e4 LT |
43 | { |
44 | u8 *ptr = NULL; | |
45 | ||
46 | if (k >= SKF_NET_OFF) | |
d56f90a7 | 47 | ptr = skb_network_header(skb) + k - SKF_NET_OFF; |
1da177e4 | 48 | else if (k >= SKF_LL_OFF) |
98e399f8 | 49 | ptr = skb_mac_header(skb) + k - SKF_LL_OFF; |
1da177e4 | 50 | |
27a884dc | 51 | if (ptr >= skb->head && ptr < skb_tail_pointer(skb)) |
1da177e4 LT |
52 | return ptr; |
53 | return NULL; | |
54 | } | |
55 | ||
0b05b2a4 | 56 | static inline void *load_pointer(struct sk_buff *skb, int k, |
4ec93edb | 57 | unsigned int size, void *buffer) |
0b05b2a4 PM |
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 | ||
43db6d65 SH |
68 | /** |
69 | * sk_filter - run a packet through a socket filter | |
70 | * @sk: sock associated with &sk_buff | |
71 | * @skb: buffer to filter | |
43db6d65 SH |
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(); | |
a898def2 | 90 | filter = rcu_dereference_bh(sk->sk_filter); |
43db6d65 SH |
91 | if (filter) { |
92 | unsigned int pkt_len = sk_run_filter(skb, filter->insns, | |
93 | filter->len); | |
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 | ||
1da177e4 | 102 | /** |
2966b66c | 103 | * sk_run_filter - run a filter on a socket |
1da177e4 LT |
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 | */ | |
4bad4dc9 | 113 | unsigned int sk_run_filter(struct sk_buff *skb, struct sock_filter *filter, int flen) |
1da177e4 | 114 | { |
1da177e4 | 115 | struct sock_filter *fentry; /* We walk down these */ |
0b05b2a4 | 116 | void *ptr; |
2966b66c KK |
117 | u32 A = 0; /* Accumulator */ |
118 | u32 X = 0; /* Index Register */ | |
1da177e4 | 119 | u32 mem[BPF_MEMWORDS]; /* Scratch Memory Store */ |
0b05b2a4 | 120 | u32 tmp; |
1da177e4 LT |
121 | int k; |
122 | int pc; | |
123 | ||
124 | /* | |
125 | * Process array of filter instructions. | |
126 | */ | |
127 | for (pc = 0; pc < flen; pc++) { | |
128 | fentry = &filter[pc]; | |
4ec93edb | 129 | |
1da177e4 | 130 | switch (fentry->code) { |
01f2f3f6 | 131 | case BPF_S_ALU_ADD_X: |
1da177e4 LT |
132 | A += X; |
133 | continue; | |
01f2f3f6 | 134 | case BPF_S_ALU_ADD_K: |
1da177e4 LT |
135 | A += fentry->k; |
136 | continue; | |
01f2f3f6 | 137 | case BPF_S_ALU_SUB_X: |
1da177e4 LT |
138 | A -= X; |
139 | continue; | |
01f2f3f6 | 140 | case BPF_S_ALU_SUB_K: |
1da177e4 LT |
141 | A -= fentry->k; |
142 | continue; | |
01f2f3f6 | 143 | case BPF_S_ALU_MUL_X: |
1da177e4 LT |
144 | A *= X; |
145 | continue; | |
01f2f3f6 | 146 | case BPF_S_ALU_MUL_K: |
1da177e4 LT |
147 | A *= fentry->k; |
148 | continue; | |
01f2f3f6 | 149 | case BPF_S_ALU_DIV_X: |
1da177e4 LT |
150 | if (X == 0) |
151 | return 0; | |
152 | A /= X; | |
153 | continue; | |
01f2f3f6 | 154 | case BPF_S_ALU_DIV_K: |
1da177e4 LT |
155 | A /= fentry->k; |
156 | continue; | |
01f2f3f6 | 157 | case BPF_S_ALU_AND_X: |
1da177e4 LT |
158 | A &= X; |
159 | continue; | |
01f2f3f6 | 160 | case BPF_S_ALU_AND_K: |
1da177e4 LT |
161 | A &= fentry->k; |
162 | continue; | |
01f2f3f6 | 163 | case BPF_S_ALU_OR_X: |
1da177e4 LT |
164 | A |= X; |
165 | continue; | |
01f2f3f6 | 166 | case BPF_S_ALU_OR_K: |
1da177e4 LT |
167 | A |= fentry->k; |
168 | continue; | |
01f2f3f6 | 169 | case BPF_S_ALU_LSH_X: |
1da177e4 LT |
170 | A <<= X; |
171 | continue; | |
01f2f3f6 | 172 | case BPF_S_ALU_LSH_K: |
1da177e4 LT |
173 | A <<= fentry->k; |
174 | continue; | |
01f2f3f6 | 175 | case BPF_S_ALU_RSH_X: |
1da177e4 LT |
176 | A >>= X; |
177 | continue; | |
01f2f3f6 | 178 | case BPF_S_ALU_RSH_K: |
1da177e4 LT |
179 | A >>= fentry->k; |
180 | continue; | |
01f2f3f6 | 181 | case BPF_S_ALU_NEG: |
1da177e4 LT |
182 | A = -A; |
183 | continue; | |
01f2f3f6 | 184 | case BPF_S_JMP_JA: |
1da177e4 LT |
185 | pc += fentry->k; |
186 | continue; | |
01f2f3f6 | 187 | case BPF_S_JMP_JGT_K: |
1da177e4 LT |
188 | pc += (A > fentry->k) ? fentry->jt : fentry->jf; |
189 | continue; | |
01f2f3f6 | 190 | case BPF_S_JMP_JGE_K: |
1da177e4 LT |
191 | pc += (A >= fentry->k) ? fentry->jt : fentry->jf; |
192 | continue; | |
01f2f3f6 | 193 | case BPF_S_JMP_JEQ_K: |
1da177e4 LT |
194 | pc += (A == fentry->k) ? fentry->jt : fentry->jf; |
195 | continue; | |
01f2f3f6 | 196 | case BPF_S_JMP_JSET_K: |
1da177e4 LT |
197 | pc += (A & fentry->k) ? fentry->jt : fentry->jf; |
198 | continue; | |
01f2f3f6 | 199 | case BPF_S_JMP_JGT_X: |
1da177e4 LT |
200 | pc += (A > X) ? fentry->jt : fentry->jf; |
201 | continue; | |
01f2f3f6 | 202 | case BPF_S_JMP_JGE_X: |
1da177e4 LT |
203 | pc += (A >= X) ? fentry->jt : fentry->jf; |
204 | continue; | |
01f2f3f6 | 205 | case BPF_S_JMP_JEQ_X: |
1da177e4 LT |
206 | pc += (A == X) ? fentry->jt : fentry->jf; |
207 | continue; | |
01f2f3f6 | 208 | case BPF_S_JMP_JSET_X: |
1da177e4 LT |
209 | pc += (A & X) ? fentry->jt : fentry->jf; |
210 | continue; | |
01f2f3f6 | 211 | case BPF_S_LD_W_ABS: |
1da177e4 | 212 | k = fentry->k; |
e35bedf3 | 213 | load_w: |
0b05b2a4 PM |
214 | ptr = load_pointer(skb, k, 4, &tmp); |
215 | if (ptr != NULL) { | |
d3e2ce3b | 216 | A = get_unaligned_be32(ptr); |
0b05b2a4 | 217 | continue; |
1da177e4 | 218 | } |
1198ad00 | 219 | break; |
01f2f3f6 | 220 | case BPF_S_LD_H_ABS: |
1da177e4 | 221 | k = fentry->k; |
e35bedf3 | 222 | load_h: |
0b05b2a4 PM |
223 | ptr = load_pointer(skb, k, 2, &tmp); |
224 | if (ptr != NULL) { | |
d3e2ce3b | 225 | A = get_unaligned_be16(ptr); |
0b05b2a4 | 226 | continue; |
1da177e4 | 227 | } |
1198ad00 | 228 | break; |
01f2f3f6 | 229 | case BPF_S_LD_B_ABS: |
1da177e4 LT |
230 | k = fentry->k; |
231 | load_b: | |
0b05b2a4 PM |
232 | ptr = load_pointer(skb, k, 1, &tmp); |
233 | if (ptr != NULL) { | |
234 | A = *(u8 *)ptr; | |
235 | continue; | |
1da177e4 | 236 | } |
1198ad00 | 237 | break; |
01f2f3f6 | 238 | case BPF_S_LD_W_LEN: |
3154e540 | 239 | A = skb->len; |
1da177e4 | 240 | continue; |
01f2f3f6 | 241 | case BPF_S_LDX_W_LEN: |
3154e540 | 242 | X = skb->len; |
1da177e4 | 243 | continue; |
01f2f3f6 | 244 | case BPF_S_LD_W_IND: |
1da177e4 LT |
245 | k = X + fentry->k; |
246 | goto load_w; | |
01f2f3f6 | 247 | case BPF_S_LD_H_IND: |
1da177e4 LT |
248 | k = X + fentry->k; |
249 | goto load_h; | |
01f2f3f6 | 250 | case BPF_S_LD_B_IND: |
1da177e4 LT |
251 | k = X + fentry->k; |
252 | goto load_b; | |
01f2f3f6 | 253 | case BPF_S_LDX_B_MSH: |
0b05b2a4 PM |
254 | ptr = load_pointer(skb, fentry->k, 1, &tmp); |
255 | if (ptr != NULL) { | |
256 | X = (*(u8 *)ptr & 0xf) << 2; | |
257 | continue; | |
258 | } | |
259 | return 0; | |
01f2f3f6 | 260 | case BPF_S_LD_IMM: |
1da177e4 LT |
261 | A = fentry->k; |
262 | continue; | |
01f2f3f6 | 263 | case BPF_S_LDX_IMM: |
1da177e4 LT |
264 | X = fentry->k; |
265 | continue; | |
01f2f3f6 | 266 | case BPF_S_LD_MEM: |
1da177e4 LT |
267 | A = mem[fentry->k]; |
268 | continue; | |
01f2f3f6 | 269 | case BPF_S_LDX_MEM: |
1da177e4 LT |
270 | X = mem[fentry->k]; |
271 | continue; | |
01f2f3f6 | 272 | case BPF_S_MISC_TAX: |
1da177e4 LT |
273 | X = A; |
274 | continue; | |
01f2f3f6 | 275 | case BPF_S_MISC_TXA: |
1da177e4 LT |
276 | A = X; |
277 | continue; | |
01f2f3f6 | 278 | case BPF_S_RET_K: |
4bad4dc9 | 279 | return fentry->k; |
01f2f3f6 | 280 | case BPF_S_RET_A: |
4bad4dc9 | 281 | return A; |
01f2f3f6 | 282 | case BPF_S_ST: |
1da177e4 LT |
283 | mem[fentry->k] = A; |
284 | continue; | |
01f2f3f6 | 285 | case BPF_S_STX: |
1da177e4 LT |
286 | mem[fentry->k] = X; |
287 | continue; | |
288 | default: | |
93699863 | 289 | WARN_ON(1); |
1da177e4 LT |
290 | return 0; |
291 | } | |
292 | ||
293 | /* | |
294 | * Handle ancillary data, which are impossible | |
295 | * (or very difficult) to get parsing packet contents. | |
296 | */ | |
297 | switch (k-SKF_AD_OFF) { | |
298 | case SKF_AD_PROTOCOL: | |
252e3346 | 299 | A = ntohs(skb->protocol); |
1da177e4 LT |
300 | continue; |
301 | case SKF_AD_PKTTYPE: | |
302 | A = skb->pkt_type; | |
303 | continue; | |
304 | case SKF_AD_IFINDEX: | |
40eaf962 PLE |
305 | if (!skb->dev) |
306 | return 0; | |
1da177e4 LT |
307 | A = skb->dev->ifindex; |
308 | continue; | |
7e75f93e | 309 | case SKF_AD_MARK: |
310 | A = skb->mark; | |
311 | continue; | |
d19742fb ED |
312 | case SKF_AD_QUEUE: |
313 | A = skb->queue_mapping; | |
314 | continue; | |
40eaf962 PLE |
315 | case SKF_AD_HATYPE: |
316 | if (!skb->dev) | |
317 | return 0; | |
318 | A = skb->dev->type; | |
319 | continue; | |
4738c1db PM |
320 | case SKF_AD_NLATTR: { |
321 | struct nlattr *nla; | |
322 | ||
323 | if (skb_is_nonlinear(skb)) | |
324 | return 0; | |
325 | if (A > skb->len - sizeof(struct nlattr)) | |
326 | return 0; | |
327 | ||
328 | nla = nla_find((struct nlattr *)&skb->data[A], | |
329 | skb->len - A, X); | |
330 | if (nla) | |
331 | A = (void *)nla - (void *)skb->data; | |
332 | else | |
333 | A = 0; | |
334 | continue; | |
335 | } | |
d214c753 PNA |
336 | case SKF_AD_NLATTR_NEST: { |
337 | struct nlattr *nla; | |
338 | ||
339 | if (skb_is_nonlinear(skb)) | |
340 | return 0; | |
341 | if (A > skb->len - sizeof(struct nlattr)) | |
342 | return 0; | |
343 | ||
344 | nla = (struct nlattr *)&skb->data[A]; | |
345 | if (nla->nla_len > A - skb->len) | |
346 | return 0; | |
347 | ||
348 | nla = nla_find_nested(nla, X); | |
349 | if (nla) | |
350 | A = (void *)nla - (void *)skb->data; | |
351 | else | |
352 | A = 0; | |
353 | continue; | |
354 | } | |
1da177e4 LT |
355 | default: |
356 | return 0; | |
357 | } | |
358 | } | |
359 | ||
360 | return 0; | |
361 | } | |
b715631f | 362 | EXPORT_SYMBOL(sk_run_filter); |
1da177e4 LT |
363 | |
364 | /** | |
365 | * sk_chk_filter - verify socket filter code | |
366 | * @filter: filter to verify | |
367 | * @flen: length of filter | |
368 | * | |
369 | * Check the user's filter code. If we let some ugly | |
370 | * filter code slip through kaboom! The filter must contain | |
93699863 KK |
371 | * no references or jumps that are out of range, no illegal |
372 | * instructions, and must end with a RET instruction. | |
1da177e4 | 373 | * |
7b11f69f KK |
374 | * All jumps are forward as they are not signed. |
375 | * | |
376 | * Returns 0 if the rule set is legal or -EINVAL if not. | |
1da177e4 LT |
377 | */ |
378 | int sk_chk_filter(struct sock_filter *filter, int flen) | |
379 | { | |
380 | struct sock_filter *ftest; | |
381 | int pc; | |
382 | ||
1b93ae64 | 383 | if (flen == 0 || flen > BPF_MAXINSNS) |
1da177e4 LT |
384 | return -EINVAL; |
385 | ||
386 | /* check the filter code now */ | |
387 | for (pc = 0; pc < flen; pc++) { | |
1da177e4 | 388 | ftest = &filter[pc]; |
1da177e4 | 389 | |
93699863 KK |
390 | /* Only allow valid instructions */ |
391 | switch (ftest->code) { | |
392 | case BPF_ALU|BPF_ADD|BPF_K: | |
01f2f3f6 HPP |
393 | ftest->code = BPF_S_ALU_ADD_K; |
394 | break; | |
93699863 | 395 | case BPF_ALU|BPF_ADD|BPF_X: |
01f2f3f6 HPP |
396 | ftest->code = BPF_S_ALU_ADD_X; |
397 | break; | |
93699863 | 398 | case BPF_ALU|BPF_SUB|BPF_K: |
01f2f3f6 HPP |
399 | ftest->code = BPF_S_ALU_SUB_K; |
400 | break; | |
93699863 | 401 | case BPF_ALU|BPF_SUB|BPF_X: |
01f2f3f6 HPP |
402 | ftest->code = BPF_S_ALU_SUB_X; |
403 | break; | |
93699863 | 404 | case BPF_ALU|BPF_MUL|BPF_K: |
01f2f3f6 HPP |
405 | ftest->code = BPF_S_ALU_MUL_K; |
406 | break; | |
93699863 | 407 | case BPF_ALU|BPF_MUL|BPF_X: |
01f2f3f6 HPP |
408 | ftest->code = BPF_S_ALU_MUL_X; |
409 | break; | |
93699863 | 410 | case BPF_ALU|BPF_DIV|BPF_X: |
01f2f3f6 HPP |
411 | ftest->code = BPF_S_ALU_DIV_X; |
412 | break; | |
93699863 | 413 | case BPF_ALU|BPF_AND|BPF_K: |
01f2f3f6 HPP |
414 | ftest->code = BPF_S_ALU_AND_K; |
415 | break; | |
93699863 | 416 | case BPF_ALU|BPF_AND|BPF_X: |
01f2f3f6 HPP |
417 | ftest->code = BPF_S_ALU_AND_X; |
418 | break; | |
93699863 | 419 | case BPF_ALU|BPF_OR|BPF_K: |
01f2f3f6 HPP |
420 | ftest->code = BPF_S_ALU_OR_K; |
421 | break; | |
93699863 | 422 | case BPF_ALU|BPF_OR|BPF_X: |
01f2f3f6 HPP |
423 | ftest->code = BPF_S_ALU_OR_X; |
424 | break; | |
93699863 | 425 | case BPF_ALU|BPF_LSH|BPF_K: |
01f2f3f6 HPP |
426 | ftest->code = BPF_S_ALU_LSH_K; |
427 | break; | |
93699863 | 428 | case BPF_ALU|BPF_LSH|BPF_X: |
01f2f3f6 HPP |
429 | ftest->code = BPF_S_ALU_LSH_X; |
430 | break; | |
93699863 | 431 | case BPF_ALU|BPF_RSH|BPF_K: |
01f2f3f6 HPP |
432 | ftest->code = BPF_S_ALU_RSH_K; |
433 | break; | |
93699863 | 434 | case BPF_ALU|BPF_RSH|BPF_X: |
01f2f3f6 HPP |
435 | ftest->code = BPF_S_ALU_RSH_X; |
436 | break; | |
93699863 | 437 | case BPF_ALU|BPF_NEG: |
01f2f3f6 HPP |
438 | ftest->code = BPF_S_ALU_NEG; |
439 | break; | |
93699863 | 440 | case BPF_LD|BPF_W|BPF_ABS: |
01f2f3f6 HPP |
441 | ftest->code = BPF_S_LD_W_ABS; |
442 | break; | |
93699863 | 443 | case BPF_LD|BPF_H|BPF_ABS: |
01f2f3f6 HPP |
444 | ftest->code = BPF_S_LD_H_ABS; |
445 | break; | |
93699863 | 446 | case BPF_LD|BPF_B|BPF_ABS: |
01f2f3f6 HPP |
447 | ftest->code = BPF_S_LD_B_ABS; |
448 | break; | |
93699863 | 449 | case BPF_LD|BPF_W|BPF_LEN: |
01f2f3f6 HPP |
450 | ftest->code = BPF_S_LD_W_LEN; |
451 | break; | |
93699863 | 452 | case BPF_LD|BPF_W|BPF_IND: |
01f2f3f6 HPP |
453 | ftest->code = BPF_S_LD_W_IND; |
454 | break; | |
93699863 | 455 | case BPF_LD|BPF_H|BPF_IND: |
01f2f3f6 HPP |
456 | ftest->code = BPF_S_LD_H_IND; |
457 | break; | |
93699863 | 458 | case BPF_LD|BPF_B|BPF_IND: |
01f2f3f6 HPP |
459 | ftest->code = BPF_S_LD_B_IND; |
460 | break; | |
93699863 | 461 | case BPF_LD|BPF_IMM: |
01f2f3f6 HPP |
462 | ftest->code = BPF_S_LD_IMM; |
463 | break; | |
93699863 | 464 | case BPF_LDX|BPF_W|BPF_LEN: |
01f2f3f6 HPP |
465 | ftest->code = BPF_S_LDX_W_LEN; |
466 | break; | |
93699863 | 467 | case BPF_LDX|BPF_B|BPF_MSH: |
01f2f3f6 HPP |
468 | ftest->code = BPF_S_LDX_B_MSH; |
469 | break; | |
93699863 | 470 | case BPF_LDX|BPF_IMM: |
01f2f3f6 HPP |
471 | ftest->code = BPF_S_LDX_IMM; |
472 | break; | |
93699863 | 473 | case BPF_MISC|BPF_TAX: |
01f2f3f6 HPP |
474 | ftest->code = BPF_S_MISC_TAX; |
475 | break; | |
93699863 | 476 | case BPF_MISC|BPF_TXA: |
01f2f3f6 HPP |
477 | ftest->code = BPF_S_MISC_TXA; |
478 | break; | |
93699863 | 479 | case BPF_RET|BPF_K: |
01f2f3f6 HPP |
480 | ftest->code = BPF_S_RET_K; |
481 | break; | |
93699863 | 482 | case BPF_RET|BPF_A: |
01f2f3f6 | 483 | ftest->code = BPF_S_RET_A; |
93699863 KK |
484 | break; |
485 | ||
486 | /* Some instructions need special checks */ | |
fb0d366b | 487 | |
93699863 | 488 | /* check for division by zero */ |
01f2f3f6 | 489 | case BPF_ALU|BPF_DIV|BPF_K: |
93699863 | 490 | if (ftest->k == 0) |
1da177e4 | 491 | return -EINVAL; |
01f2f3f6 | 492 | ftest->code = BPF_S_ALU_DIV_K; |
93699863 KK |
493 | break; |
494 | ||
01f2f3f6 | 495 | /* check for invalid memory addresses */ |
93699863 | 496 | case BPF_LD|BPF_MEM: |
01f2f3f6 HPP |
497 | if (ftest->k >= BPF_MEMWORDS) |
498 | return -EINVAL; | |
499 | ftest->code = BPF_S_LD_MEM; | |
500 | break; | |
93699863 | 501 | case BPF_LDX|BPF_MEM: |
01f2f3f6 HPP |
502 | if (ftest->k >= BPF_MEMWORDS) |
503 | return -EINVAL; | |
504 | ftest->code = BPF_S_LDX_MEM; | |
505 | break; | |
93699863 | 506 | case BPF_ST: |
01f2f3f6 HPP |
507 | if (ftest->k >= BPF_MEMWORDS) |
508 | return -EINVAL; | |
509 | ftest->code = BPF_S_ST; | |
510 | break; | |
93699863 | 511 | case BPF_STX: |
93699863 KK |
512 | if (ftest->k >= BPF_MEMWORDS) |
513 | return -EINVAL; | |
01f2f3f6 | 514 | ftest->code = BPF_S_STX; |
93699863 KK |
515 | break; |
516 | ||
517 | case BPF_JMP|BPF_JA: | |
518 | /* | |
519 | * Note, the large ftest->k might cause loops. | |
520 | * Compare this with conditional jumps below, | |
521 | * where offsets are limited. --ANK (981016) | |
522 | */ | |
523 | if (ftest->k >= (unsigned)(flen-pc-1)) | |
524 | return -EINVAL; | |
01f2f3f6 | 525 | ftest->code = BPF_S_JMP_JA; |
93699863 KK |
526 | break; |
527 | ||
528 | case BPF_JMP|BPF_JEQ|BPF_K: | |
01f2f3f6 HPP |
529 | ftest->code = BPF_S_JMP_JEQ_K; |
530 | break; | |
93699863 | 531 | case BPF_JMP|BPF_JEQ|BPF_X: |
01f2f3f6 HPP |
532 | ftest->code = BPF_S_JMP_JEQ_X; |
533 | break; | |
93699863 | 534 | case BPF_JMP|BPF_JGE|BPF_K: |
01f2f3f6 HPP |
535 | ftest->code = BPF_S_JMP_JGE_K; |
536 | break; | |
93699863 | 537 | case BPF_JMP|BPF_JGE|BPF_X: |
01f2f3f6 HPP |
538 | ftest->code = BPF_S_JMP_JGE_X; |
539 | break; | |
93699863 | 540 | case BPF_JMP|BPF_JGT|BPF_K: |
01f2f3f6 HPP |
541 | ftest->code = BPF_S_JMP_JGT_K; |
542 | break; | |
93699863 | 543 | case BPF_JMP|BPF_JGT|BPF_X: |
01f2f3f6 HPP |
544 | ftest->code = BPF_S_JMP_JGT_X; |
545 | break; | |
93699863 | 546 | case BPF_JMP|BPF_JSET|BPF_K: |
01f2f3f6 HPP |
547 | ftest->code = BPF_S_JMP_JSET_K; |
548 | break; | |
93699863 | 549 | case BPF_JMP|BPF_JSET|BPF_X: |
01f2f3f6 HPP |
550 | ftest->code = BPF_S_JMP_JSET_X; |
551 | break; | |
552 | ||
553 | default: | |
554 | return -EINVAL; | |
555 | } | |
556 | ||
93699863 | 557 | /* for conditionals both must be safe */ |
01f2f3f6 HPP |
558 | switch (ftest->code) { |
559 | case BPF_S_JMP_JEQ_K: | |
560 | case BPF_S_JMP_JEQ_X: | |
561 | case BPF_S_JMP_JGE_K: | |
562 | case BPF_S_JMP_JGE_X: | |
563 | case BPF_S_JMP_JGT_K: | |
564 | case BPF_S_JMP_JGT_X: | |
565 | case BPF_S_JMP_JSET_X: | |
566 | case BPF_S_JMP_JSET_K: | |
e35bedf3 | 567 | if (pc + ftest->jt + 1 >= flen || |
93699863 KK |
568 | pc + ftest->jf + 1 >= flen) |
569 | return -EINVAL; | |
01f2f3f6 HPP |
570 | } |
571 | } | |
93699863 | 572 | |
01f2f3f6 HPP |
573 | /* last instruction must be a RET code */ |
574 | switch (filter[flen - 1].code) { | |
575 | case BPF_S_RET_K: | |
576 | case BPF_S_RET_A: | |
577 | return 0; | |
578 | break; | |
93699863 KK |
579 | default: |
580 | return -EINVAL; | |
1da177e4 | 581 | } |
1da177e4 | 582 | } |
b715631f | 583 | EXPORT_SYMBOL(sk_chk_filter); |
1da177e4 | 584 | |
47e958ea PE |
585 | /** |
586 | * sk_filter_rcu_release: Release a socket filter by rcu_head | |
587 | * @rcu: rcu_head that contains the sk_filter to free | |
588 | */ | |
589 | static void sk_filter_rcu_release(struct rcu_head *rcu) | |
590 | { | |
591 | struct sk_filter *fp = container_of(rcu, struct sk_filter, rcu); | |
592 | ||
593 | sk_filter_release(fp); | |
594 | } | |
595 | ||
596 | static void sk_filter_delayed_uncharge(struct sock *sk, struct sk_filter *fp) | |
597 | { | |
598 | unsigned int size = sk_filter_len(fp); | |
599 | ||
600 | atomic_sub(size, &sk->sk_omem_alloc); | |
601 | call_rcu_bh(&fp->rcu, sk_filter_rcu_release); | |
602 | } | |
603 | ||
1da177e4 LT |
604 | /** |
605 | * sk_attach_filter - attach a socket filter | |
606 | * @fprog: the filter program | |
607 | * @sk: the socket to use | |
608 | * | |
609 | * Attach the user's filter code. We first run some sanity checks on | |
610 | * it to make sure it does not explode on us later. If an error | |
611 | * occurs or there is insufficient memory for the filter a negative | |
612 | * errno code is returned. On success the return is zero. | |
613 | */ | |
614 | int sk_attach_filter(struct sock_fprog *fprog, struct sock *sk) | |
615 | { | |
d3904b73 | 616 | struct sk_filter *fp, *old_fp; |
1da177e4 LT |
617 | unsigned int fsize = sizeof(struct sock_filter) * fprog->len; |
618 | int err; | |
619 | ||
620 | /* Make sure new filter is there and in the right amounts. */ | |
e35bedf3 KK |
621 | if (fprog->filter == NULL) |
622 | return -EINVAL; | |
1da177e4 LT |
623 | |
624 | fp = sock_kmalloc(sk, fsize+sizeof(*fp), GFP_KERNEL); | |
625 | if (!fp) | |
626 | return -ENOMEM; | |
627 | if (copy_from_user(fp->insns, fprog->filter, fsize)) { | |
4ec93edb | 628 | sock_kfree_s(sk, fp, fsize+sizeof(*fp)); |
1da177e4 LT |
629 | return -EFAULT; |
630 | } | |
631 | ||
632 | atomic_set(&fp->refcnt, 1); | |
633 | fp->len = fprog->len; | |
634 | ||
635 | err = sk_chk_filter(fp->insns, fp->len); | |
d3904b73 PE |
636 | if (err) { |
637 | sk_filter_uncharge(sk, fp); | |
638 | return err; | |
1da177e4 LT |
639 | } |
640 | ||
d3904b73 | 641 | rcu_read_lock_bh(); |
a898def2 | 642 | old_fp = rcu_dereference_bh(sk->sk_filter); |
d3904b73 PE |
643 | rcu_assign_pointer(sk->sk_filter, fp); |
644 | rcu_read_unlock_bh(); | |
645 | ||
9b013e05 OJ |
646 | if (old_fp) |
647 | sk_filter_delayed_uncharge(sk, old_fp); | |
d3904b73 | 648 | return 0; |
1da177e4 | 649 | } |
5ff3f073 | 650 | EXPORT_SYMBOL_GPL(sk_attach_filter); |
1da177e4 | 651 | |
55b33325 PE |
652 | int sk_detach_filter(struct sock *sk) |
653 | { | |
654 | int ret = -ENOENT; | |
655 | struct sk_filter *filter; | |
656 | ||
657 | rcu_read_lock_bh(); | |
a898def2 | 658 | filter = rcu_dereference_bh(sk->sk_filter); |
55b33325 PE |
659 | if (filter) { |
660 | rcu_assign_pointer(sk->sk_filter, NULL); | |
47e958ea | 661 | sk_filter_delayed_uncharge(sk, filter); |
55b33325 PE |
662 | ret = 0; |
663 | } | |
664 | rcu_read_unlock_bh(); | |
665 | return ret; | |
666 | } | |
5ff3f073 | 667 | EXPORT_SYMBOL_GPL(sk_detach_filter); |