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> | |
28 | #include <net/ip.h> | |
29 | #include <net/protocol.h> | |
4738c1db | 30 | #include <net/netlink.h> |
1da177e4 LT |
31 | #include <linux/skbuff.h> |
32 | #include <net/sock.h> | |
33 | #include <linux/errno.h> | |
34 | #include <linux/timer.h> | |
35 | #include <asm/system.h> | |
36 | #include <asm/uaccess.h> | |
40daafc8 | 37 | #include <asm/unaligned.h> |
1da177e4 LT |
38 | #include <linux/filter.h> |
39 | ||
40 | /* No hurry in this branch */ | |
0b05b2a4 | 41 | static void *__load_pointer(struct sk_buff *skb, int k) |
1da177e4 LT |
42 | { |
43 | u8 *ptr = NULL; | |
44 | ||
45 | if (k >= SKF_NET_OFF) | |
d56f90a7 | 46 | ptr = skb_network_header(skb) + k - SKF_NET_OFF; |
1da177e4 | 47 | else if (k >= SKF_LL_OFF) |
98e399f8 | 48 | ptr = skb_mac_header(skb) + k - SKF_LL_OFF; |
1da177e4 | 49 | |
27a884dc | 50 | if (ptr >= skb->head && ptr < skb_tail_pointer(skb)) |
1da177e4 LT |
51 | return ptr; |
52 | return NULL; | |
53 | } | |
54 | ||
0b05b2a4 | 55 | static inline void *load_pointer(struct sk_buff *skb, int k, |
4ec93edb | 56 | unsigned int size, void *buffer) |
0b05b2a4 PM |
57 | { |
58 | if (k >= 0) | |
59 | return skb_header_pointer(skb, k, size, buffer); | |
60 | else { | |
61 | if (k >= SKF_AD_OFF) | |
62 | return NULL; | |
63 | return __load_pointer(skb, k); | |
64 | } | |
65 | } | |
66 | ||
43db6d65 SH |
67 | /** |
68 | * sk_filter - run a packet through a socket filter | |
69 | * @sk: sock associated with &sk_buff | |
70 | * @skb: buffer to filter | |
43db6d65 SH |
71 | * |
72 | * Run the filter code and then cut skb->data to correct size returned by | |
73 | * sk_run_filter. If pkt_len is 0 we toss packet. If skb->len is smaller | |
74 | * than pkt_len we keep whole skb->data. This is the socket level | |
75 | * wrapper to sk_run_filter. It returns 0 if the packet should | |
76 | * be accepted or -EPERM if the packet should be tossed. | |
77 | * | |
78 | */ | |
79 | int sk_filter(struct sock *sk, struct sk_buff *skb) | |
80 | { | |
81 | int err; | |
82 | struct sk_filter *filter; | |
83 | ||
84 | err = security_sock_rcv_skb(sk, skb); | |
85 | if (err) | |
86 | return err; | |
87 | ||
88 | rcu_read_lock_bh(); | |
89 | filter = rcu_dereference(sk->sk_filter); | |
90 | if (filter) { | |
91 | unsigned int pkt_len = sk_run_filter(skb, filter->insns, | |
92 | filter->len); | |
93 | err = pkt_len ? pskb_trim(skb, pkt_len) : -EPERM; | |
94 | } | |
95 | rcu_read_unlock_bh(); | |
96 | ||
97 | return err; | |
98 | } | |
99 | EXPORT_SYMBOL(sk_filter); | |
100 | ||
1da177e4 | 101 | /** |
2966b66c | 102 | * sk_run_filter - run a filter on a socket |
1da177e4 LT |
103 | * @skb: buffer to run the filter on |
104 | * @filter: filter to apply | |
105 | * @flen: length of filter | |
106 | * | |
107 | * Decode and apply filter instructions to the skb->data. | |
108 | * Return length to keep, 0 for none. skb is the data we are | |
109 | * filtering, filter is the array of filter instructions, and | |
110 | * len is the number of filter blocks in the array. | |
111 | */ | |
4bad4dc9 | 112 | unsigned int sk_run_filter(struct sk_buff *skb, struct sock_filter *filter, int flen) |
1da177e4 | 113 | { |
1da177e4 | 114 | struct sock_filter *fentry; /* We walk down these */ |
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 LT |
120 | int k; |
121 | int pc; | |
122 | ||
123 | /* | |
124 | * Process array of filter instructions. | |
125 | */ | |
126 | for (pc = 0; pc < flen; pc++) { | |
127 | fentry = &filter[pc]; | |
4ec93edb | 128 | |
1da177e4 LT |
129 | switch (fentry->code) { |
130 | case BPF_ALU|BPF_ADD|BPF_X: | |
131 | A += X; | |
132 | continue; | |
133 | case BPF_ALU|BPF_ADD|BPF_K: | |
134 | A += fentry->k; | |
135 | continue; | |
136 | case BPF_ALU|BPF_SUB|BPF_X: | |
137 | A -= X; | |
138 | continue; | |
139 | case BPF_ALU|BPF_SUB|BPF_K: | |
140 | A -= fentry->k; | |
141 | continue; | |
142 | case BPF_ALU|BPF_MUL|BPF_X: | |
143 | A *= X; | |
144 | continue; | |
145 | case BPF_ALU|BPF_MUL|BPF_K: | |
146 | A *= fentry->k; | |
147 | continue; | |
148 | case BPF_ALU|BPF_DIV|BPF_X: | |
149 | if (X == 0) | |
150 | return 0; | |
151 | A /= X; | |
152 | continue; | |
153 | case BPF_ALU|BPF_DIV|BPF_K: | |
1da177e4 LT |
154 | A /= fentry->k; |
155 | continue; | |
156 | case BPF_ALU|BPF_AND|BPF_X: | |
157 | A &= X; | |
158 | continue; | |
159 | case BPF_ALU|BPF_AND|BPF_K: | |
160 | A &= fentry->k; | |
161 | continue; | |
162 | case BPF_ALU|BPF_OR|BPF_X: | |
163 | A |= X; | |
164 | continue; | |
165 | case BPF_ALU|BPF_OR|BPF_K: | |
166 | A |= fentry->k; | |
167 | continue; | |
168 | case BPF_ALU|BPF_LSH|BPF_X: | |
169 | A <<= X; | |
170 | continue; | |
171 | case BPF_ALU|BPF_LSH|BPF_K: | |
172 | A <<= fentry->k; | |
173 | continue; | |
174 | case BPF_ALU|BPF_RSH|BPF_X: | |
175 | A >>= X; | |
176 | continue; | |
177 | case BPF_ALU|BPF_RSH|BPF_K: | |
178 | A >>= fentry->k; | |
179 | continue; | |
180 | case BPF_ALU|BPF_NEG: | |
181 | A = -A; | |
182 | continue; | |
183 | case BPF_JMP|BPF_JA: | |
184 | pc += fentry->k; | |
185 | continue; | |
186 | case BPF_JMP|BPF_JGT|BPF_K: | |
187 | pc += (A > fentry->k) ? fentry->jt : fentry->jf; | |
188 | continue; | |
189 | case BPF_JMP|BPF_JGE|BPF_K: | |
190 | pc += (A >= fentry->k) ? fentry->jt : fentry->jf; | |
191 | continue; | |
192 | case BPF_JMP|BPF_JEQ|BPF_K: | |
193 | pc += (A == fentry->k) ? fentry->jt : fentry->jf; | |
194 | continue; | |
195 | case BPF_JMP|BPF_JSET|BPF_K: | |
196 | pc += (A & fentry->k) ? fentry->jt : fentry->jf; | |
197 | continue; | |
198 | case BPF_JMP|BPF_JGT|BPF_X: | |
199 | pc += (A > X) ? fentry->jt : fentry->jf; | |
200 | continue; | |
201 | case BPF_JMP|BPF_JGE|BPF_X: | |
202 | pc += (A >= X) ? fentry->jt : fentry->jf; | |
203 | continue; | |
204 | case BPF_JMP|BPF_JEQ|BPF_X: | |
205 | pc += (A == X) ? fentry->jt : fentry->jf; | |
206 | continue; | |
207 | case BPF_JMP|BPF_JSET|BPF_X: | |
208 | pc += (A & X) ? fentry->jt : fentry->jf; | |
209 | continue; | |
210 | case BPF_LD|BPF_W|BPF_ABS: | |
211 | k = fentry->k; | |
e35bedf3 | 212 | load_w: |
0b05b2a4 PM |
213 | ptr = load_pointer(skb, k, 4, &tmp); |
214 | if (ptr != NULL) { | |
d3e2ce3b | 215 | A = get_unaligned_be32(ptr); |
0b05b2a4 | 216 | continue; |
1da177e4 | 217 | } |
1198ad00 | 218 | break; |
1da177e4 LT |
219 | case BPF_LD|BPF_H|BPF_ABS: |
220 | k = fentry->k; | |
e35bedf3 | 221 | load_h: |
0b05b2a4 PM |
222 | ptr = load_pointer(skb, k, 2, &tmp); |
223 | if (ptr != NULL) { | |
d3e2ce3b | 224 | A = get_unaligned_be16(ptr); |
0b05b2a4 | 225 | continue; |
1da177e4 | 226 | } |
1198ad00 | 227 | break; |
1da177e4 LT |
228 | case BPF_LD|BPF_B|BPF_ABS: |
229 | k = fentry->k; | |
230 | load_b: | |
0b05b2a4 PM |
231 | ptr = load_pointer(skb, k, 1, &tmp); |
232 | if (ptr != NULL) { | |
233 | A = *(u8 *)ptr; | |
234 | continue; | |
1da177e4 | 235 | } |
1198ad00 | 236 | break; |
1da177e4 | 237 | case BPF_LD|BPF_W|BPF_LEN: |
3154e540 | 238 | A = skb->len; |
1da177e4 LT |
239 | continue; |
240 | case BPF_LDX|BPF_W|BPF_LEN: | |
3154e540 | 241 | X = skb->len; |
1da177e4 LT |
242 | continue; |
243 | case BPF_LD|BPF_W|BPF_IND: | |
244 | k = X + fentry->k; | |
245 | goto load_w; | |
246 | case BPF_LD|BPF_H|BPF_IND: | |
247 | k = X + fentry->k; | |
248 | goto load_h; | |
249 | case BPF_LD|BPF_B|BPF_IND: | |
250 | k = X + fentry->k; | |
251 | goto load_b; | |
252 | case BPF_LDX|BPF_B|BPF_MSH: | |
0b05b2a4 PM |
253 | ptr = load_pointer(skb, fentry->k, 1, &tmp); |
254 | if (ptr != NULL) { | |
255 | X = (*(u8 *)ptr & 0xf) << 2; | |
256 | continue; | |
257 | } | |
258 | return 0; | |
1da177e4 LT |
259 | case BPF_LD|BPF_IMM: |
260 | A = fentry->k; | |
261 | continue; | |
262 | case BPF_LDX|BPF_IMM: | |
263 | X = fentry->k; | |
264 | continue; | |
265 | case BPF_LD|BPF_MEM: | |
266 | A = mem[fentry->k]; | |
267 | continue; | |
268 | case BPF_LDX|BPF_MEM: | |
269 | X = mem[fentry->k]; | |
270 | continue; | |
271 | case BPF_MISC|BPF_TAX: | |
272 | X = A; | |
273 | continue; | |
274 | case BPF_MISC|BPF_TXA: | |
275 | A = X; | |
276 | continue; | |
277 | case BPF_RET|BPF_K: | |
4bad4dc9 | 278 | return fentry->k; |
1da177e4 | 279 | case BPF_RET|BPF_A: |
4bad4dc9 | 280 | return A; |
1da177e4 LT |
281 | case BPF_ST: |
282 | mem[fentry->k] = A; | |
283 | continue; | |
284 | case BPF_STX: | |
285 | mem[fentry->k] = X; | |
286 | continue; | |
287 | default: | |
93699863 | 288 | WARN_ON(1); |
1da177e4 LT |
289 | return 0; |
290 | } | |
291 | ||
292 | /* | |
293 | * Handle ancillary data, which are impossible | |
294 | * (or very difficult) to get parsing packet contents. | |
295 | */ | |
296 | switch (k-SKF_AD_OFF) { | |
297 | case SKF_AD_PROTOCOL: | |
252e3346 | 298 | A = ntohs(skb->protocol); |
1da177e4 LT |
299 | continue; |
300 | case SKF_AD_PKTTYPE: | |
301 | A = skb->pkt_type; | |
302 | continue; | |
303 | case SKF_AD_IFINDEX: | |
304 | A = skb->dev->ifindex; | |
305 | continue; | |
7e75f93e | 306 | case SKF_AD_MARK: |
307 | A = skb->mark; | |
308 | continue; | |
d19742fb ED |
309 | case SKF_AD_QUEUE: |
310 | A = skb->queue_mapping; | |
311 | continue; | |
4738c1db PM |
312 | case SKF_AD_NLATTR: { |
313 | struct nlattr *nla; | |
314 | ||
315 | if (skb_is_nonlinear(skb)) | |
316 | return 0; | |
317 | if (A > skb->len - sizeof(struct nlattr)) | |
318 | return 0; | |
319 | ||
320 | nla = nla_find((struct nlattr *)&skb->data[A], | |
321 | skb->len - A, X); | |
322 | if (nla) | |
323 | A = (void *)nla - (void *)skb->data; | |
324 | else | |
325 | A = 0; | |
326 | continue; | |
327 | } | |
d214c753 PNA |
328 | case SKF_AD_NLATTR_NEST: { |
329 | struct nlattr *nla; | |
330 | ||
331 | if (skb_is_nonlinear(skb)) | |
332 | return 0; | |
333 | if (A > skb->len - sizeof(struct nlattr)) | |
334 | return 0; | |
335 | ||
336 | nla = (struct nlattr *)&skb->data[A]; | |
337 | if (nla->nla_len > A - skb->len) | |
338 | return 0; | |
339 | ||
340 | nla = nla_find_nested(nla, X); | |
341 | if (nla) | |
342 | A = (void *)nla - (void *)skb->data; | |
343 | else | |
344 | A = 0; | |
345 | continue; | |
346 | } | |
1da177e4 LT |
347 | default: |
348 | return 0; | |
349 | } | |
350 | } | |
351 | ||
352 | return 0; | |
353 | } | |
b715631f | 354 | EXPORT_SYMBOL(sk_run_filter); |
1da177e4 LT |
355 | |
356 | /** | |
357 | * sk_chk_filter - verify socket filter code | |
358 | * @filter: filter to verify | |
359 | * @flen: length of filter | |
360 | * | |
361 | * Check the user's filter code. If we let some ugly | |
362 | * filter code slip through kaboom! The filter must contain | |
93699863 KK |
363 | * no references or jumps that are out of range, no illegal |
364 | * instructions, and must end with a RET instruction. | |
1da177e4 | 365 | * |
7b11f69f KK |
366 | * All jumps are forward as they are not signed. |
367 | * | |
368 | * Returns 0 if the rule set is legal or -EINVAL if not. | |
1da177e4 LT |
369 | */ |
370 | int sk_chk_filter(struct sock_filter *filter, int flen) | |
371 | { | |
372 | struct sock_filter *ftest; | |
373 | int pc; | |
374 | ||
1b93ae64 | 375 | if (flen == 0 || flen > BPF_MAXINSNS) |
1da177e4 LT |
376 | return -EINVAL; |
377 | ||
378 | /* check the filter code now */ | |
379 | for (pc = 0; pc < flen; pc++) { | |
1da177e4 | 380 | ftest = &filter[pc]; |
1da177e4 | 381 | |
93699863 KK |
382 | /* Only allow valid instructions */ |
383 | switch (ftest->code) { | |
384 | case BPF_ALU|BPF_ADD|BPF_K: | |
385 | case BPF_ALU|BPF_ADD|BPF_X: | |
386 | case BPF_ALU|BPF_SUB|BPF_K: | |
387 | case BPF_ALU|BPF_SUB|BPF_X: | |
388 | case BPF_ALU|BPF_MUL|BPF_K: | |
389 | case BPF_ALU|BPF_MUL|BPF_X: | |
390 | case BPF_ALU|BPF_DIV|BPF_X: | |
391 | case BPF_ALU|BPF_AND|BPF_K: | |
392 | case BPF_ALU|BPF_AND|BPF_X: | |
393 | case BPF_ALU|BPF_OR|BPF_K: | |
394 | case BPF_ALU|BPF_OR|BPF_X: | |
395 | case BPF_ALU|BPF_LSH|BPF_K: | |
396 | case BPF_ALU|BPF_LSH|BPF_X: | |
397 | case BPF_ALU|BPF_RSH|BPF_K: | |
398 | case BPF_ALU|BPF_RSH|BPF_X: | |
399 | case BPF_ALU|BPF_NEG: | |
400 | case BPF_LD|BPF_W|BPF_ABS: | |
401 | case BPF_LD|BPF_H|BPF_ABS: | |
402 | case BPF_LD|BPF_B|BPF_ABS: | |
403 | case BPF_LD|BPF_W|BPF_LEN: | |
404 | case BPF_LD|BPF_W|BPF_IND: | |
405 | case BPF_LD|BPF_H|BPF_IND: | |
406 | case BPF_LD|BPF_B|BPF_IND: | |
407 | case BPF_LD|BPF_IMM: | |
408 | case BPF_LDX|BPF_W|BPF_LEN: | |
409 | case BPF_LDX|BPF_B|BPF_MSH: | |
410 | case BPF_LDX|BPF_IMM: | |
411 | case BPF_MISC|BPF_TAX: | |
412 | case BPF_MISC|BPF_TXA: | |
413 | case BPF_RET|BPF_K: | |
414 | case BPF_RET|BPF_A: | |
415 | break; | |
416 | ||
417 | /* Some instructions need special checks */ | |
fb0d366b | 418 | |
93699863 KK |
419 | case BPF_ALU|BPF_DIV|BPF_K: |
420 | /* check for division by zero */ | |
421 | if (ftest->k == 0) | |
1da177e4 | 422 | return -EINVAL; |
93699863 KK |
423 | break; |
424 | ||
425 | case BPF_LD|BPF_MEM: | |
426 | case BPF_LDX|BPF_MEM: | |
427 | case BPF_ST: | |
428 | case BPF_STX: | |
429 | /* check for invalid memory addresses */ | |
430 | if (ftest->k >= BPF_MEMWORDS) | |
431 | return -EINVAL; | |
432 | break; | |
433 | ||
434 | case BPF_JMP|BPF_JA: | |
435 | /* | |
436 | * Note, the large ftest->k might cause loops. | |
437 | * Compare this with conditional jumps below, | |
438 | * where offsets are limited. --ANK (981016) | |
439 | */ | |
440 | if (ftest->k >= (unsigned)(flen-pc-1)) | |
441 | return -EINVAL; | |
442 | break; | |
443 | ||
444 | case BPF_JMP|BPF_JEQ|BPF_K: | |
445 | case BPF_JMP|BPF_JEQ|BPF_X: | |
446 | case BPF_JMP|BPF_JGE|BPF_K: | |
447 | case BPF_JMP|BPF_JGE|BPF_X: | |
448 | case BPF_JMP|BPF_JGT|BPF_K: | |
449 | case BPF_JMP|BPF_JGT|BPF_X: | |
450 | case BPF_JMP|BPF_JSET|BPF_K: | |
451 | case BPF_JMP|BPF_JSET|BPF_X: | |
452 | /* for conditionals both must be safe */ | |
e35bedf3 | 453 | if (pc + ftest->jt + 1 >= flen || |
93699863 KK |
454 | pc + ftest->jf + 1 >= flen) |
455 | return -EINVAL; | |
456 | break; | |
457 | ||
458 | default: | |
459 | return -EINVAL; | |
1da177e4 LT |
460 | } |
461 | } | |
462 | ||
e35bedf3 | 463 | return (BPF_CLASS(filter[flen - 1].code) == BPF_RET) ? 0 : -EINVAL; |
1da177e4 | 464 | } |
b715631f | 465 | EXPORT_SYMBOL(sk_chk_filter); |
1da177e4 | 466 | |
47e958ea PE |
467 | /** |
468 | * sk_filter_rcu_release: Release a socket filter by rcu_head | |
469 | * @rcu: rcu_head that contains the sk_filter to free | |
470 | */ | |
471 | static void sk_filter_rcu_release(struct rcu_head *rcu) | |
472 | { | |
473 | struct sk_filter *fp = container_of(rcu, struct sk_filter, rcu); | |
474 | ||
475 | sk_filter_release(fp); | |
476 | } | |
477 | ||
478 | static void sk_filter_delayed_uncharge(struct sock *sk, struct sk_filter *fp) | |
479 | { | |
480 | unsigned int size = sk_filter_len(fp); | |
481 | ||
482 | atomic_sub(size, &sk->sk_omem_alloc); | |
483 | call_rcu_bh(&fp->rcu, sk_filter_rcu_release); | |
484 | } | |
485 | ||
1da177e4 LT |
486 | /** |
487 | * sk_attach_filter - attach a socket filter | |
488 | * @fprog: the filter program | |
489 | * @sk: the socket to use | |
490 | * | |
491 | * Attach the user's filter code. We first run some sanity checks on | |
492 | * it to make sure it does not explode on us later. If an error | |
493 | * occurs or there is insufficient memory for the filter a negative | |
494 | * errno code is returned. On success the return is zero. | |
495 | */ | |
496 | int sk_attach_filter(struct sock_fprog *fprog, struct sock *sk) | |
497 | { | |
d3904b73 | 498 | struct sk_filter *fp, *old_fp; |
1da177e4 LT |
499 | unsigned int fsize = sizeof(struct sock_filter) * fprog->len; |
500 | int err; | |
501 | ||
502 | /* Make sure new filter is there and in the right amounts. */ | |
e35bedf3 KK |
503 | if (fprog->filter == NULL) |
504 | return -EINVAL; | |
1da177e4 LT |
505 | |
506 | fp = sock_kmalloc(sk, fsize+sizeof(*fp), GFP_KERNEL); | |
507 | if (!fp) | |
508 | return -ENOMEM; | |
509 | if (copy_from_user(fp->insns, fprog->filter, fsize)) { | |
4ec93edb | 510 | sock_kfree_s(sk, fp, fsize+sizeof(*fp)); |
1da177e4 LT |
511 | return -EFAULT; |
512 | } | |
513 | ||
514 | atomic_set(&fp->refcnt, 1); | |
515 | fp->len = fprog->len; | |
516 | ||
517 | err = sk_chk_filter(fp->insns, fp->len); | |
d3904b73 PE |
518 | if (err) { |
519 | sk_filter_uncharge(sk, fp); | |
520 | return err; | |
1da177e4 LT |
521 | } |
522 | ||
d3904b73 PE |
523 | rcu_read_lock_bh(); |
524 | old_fp = rcu_dereference(sk->sk_filter); | |
525 | rcu_assign_pointer(sk->sk_filter, fp); | |
526 | rcu_read_unlock_bh(); | |
527 | ||
9b013e05 OJ |
528 | if (old_fp) |
529 | sk_filter_delayed_uncharge(sk, old_fp); | |
d3904b73 | 530 | return 0; |
1da177e4 LT |
531 | } |
532 | ||
55b33325 PE |
533 | int sk_detach_filter(struct sock *sk) |
534 | { | |
535 | int ret = -ENOENT; | |
536 | struct sk_filter *filter; | |
537 | ||
538 | rcu_read_lock_bh(); | |
539 | filter = rcu_dereference(sk->sk_filter); | |
540 | if (filter) { | |
541 | rcu_assign_pointer(sk->sk_filter, NULL); | |
47e958ea | 542 | sk_filter_delayed_uncharge(sk, filter); |
55b33325 PE |
543 | ret = 0; |
544 | } | |
545 | rcu_read_unlock_bh(); | |
546 | return ret; | |
547 | } |