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Merge tag 'pm-for-3.6-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael...
[GitHub/mt8127/android_kernel_alcatel_ttab.git] / net / core / filter.c
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/uaccess.h>
37 #include <asm/unaligned.h>
38 #include <linux/filter.h>
39 #include <linux/reciprocal_div.h>
40 #include <linux/ratelimit.h>
41 #include <linux/seccomp.h>
42
43 /* No hurry in this branch
44 *
45 * Exported for the bpf jit load helper.
46 */
47 void *bpf_internal_load_pointer_neg_helper(const struct sk_buff *skb, int k, unsigned int size)
48 {
49 u8 *ptr = NULL;
50
51 if (k >= SKF_NET_OFF)
52 ptr = skb_network_header(skb) + k - SKF_NET_OFF;
53 else if (k >= SKF_LL_OFF)
54 ptr = skb_mac_header(skb) + k - SKF_LL_OFF;
55
56 if (ptr >= skb->head && ptr + size <= skb_tail_pointer(skb))
57 return ptr;
58 return NULL;
59 }
60
61 static inline void *load_pointer(const struct sk_buff *skb, int k,
62 unsigned int size, void *buffer)
63 {
64 if (k >= 0)
65 return skb_header_pointer(skb, k, size, buffer);
66 return bpf_internal_load_pointer_neg_helper(skb, k, size);
67 }
68
69 /**
70 * sk_filter - run a packet through a socket filter
71 * @sk: sock associated with &sk_buff
72 * @skb: buffer to filter
73 *
74 * Run the filter code and then cut skb->data to correct size returned by
75 * sk_run_filter. If pkt_len is 0 we toss packet. If skb->len is smaller
76 * than pkt_len we keep whole skb->data. This is the socket level
77 * wrapper to sk_run_filter. It returns 0 if the packet should
78 * be accepted or -EPERM if the packet should be tossed.
79 *
80 */
81 int sk_filter(struct sock *sk, struct sk_buff *skb)
82 {
83 int err;
84 struct sk_filter *filter;
85
86 err = security_sock_rcv_skb(sk, skb);
87 if (err)
88 return err;
89
90 rcu_read_lock();
91 filter = rcu_dereference(sk->sk_filter);
92 if (filter) {
93 unsigned int pkt_len = SK_RUN_FILTER(filter, skb);
94
95 err = pkt_len ? pskb_trim(skb, pkt_len) : -EPERM;
96 }
97 rcu_read_unlock();
98
99 return err;
100 }
101 EXPORT_SYMBOL(sk_filter);
102
103 /**
104 * sk_run_filter - run a filter on a socket
105 * @skb: buffer to run the filter on
106 * @fentry: filter to apply
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.
111 * Because all jumps are guaranteed to be before last instruction,
112 * and last instruction guaranteed to be a RET, we dont need to check
113 * flen. (We used to pass to this function the length of filter)
114 */
115 unsigned int sk_run_filter(const struct sk_buff *skb,
116 const struct sock_filter *fentry)
117 {
118 void *ptr;
119 u32 A = 0; /* Accumulator */
120 u32 X = 0; /* Index Register */
121 u32 mem[BPF_MEMWORDS]; /* Scratch Memory Store */
122 u32 tmp;
123 int k;
124
125 /*
126 * Process array of filter instructions.
127 */
128 for (;; fentry++) {
129 #if defined(CONFIG_X86_32)
130 #define K (fentry->k)
131 #else
132 const u32 K = fentry->k;
133 #endif
134
135 switch (fentry->code) {
136 case BPF_S_ALU_ADD_X:
137 A += X;
138 continue;
139 case BPF_S_ALU_ADD_K:
140 A += K;
141 continue;
142 case BPF_S_ALU_SUB_X:
143 A -= X;
144 continue;
145 case BPF_S_ALU_SUB_K:
146 A -= K;
147 continue;
148 case BPF_S_ALU_MUL_X:
149 A *= X;
150 continue;
151 case BPF_S_ALU_MUL_K:
152 A *= K;
153 continue;
154 case BPF_S_ALU_DIV_X:
155 if (X == 0)
156 return 0;
157 A /= X;
158 continue;
159 case BPF_S_ALU_DIV_K:
160 A = reciprocal_divide(A, K);
161 continue;
162 case BPF_S_ALU_AND_X:
163 A &= X;
164 continue;
165 case BPF_S_ALU_AND_K:
166 A &= K;
167 continue;
168 case BPF_S_ALU_OR_X:
169 A |= X;
170 continue;
171 case BPF_S_ALU_OR_K:
172 A |= K;
173 continue;
174 case BPF_S_ALU_LSH_X:
175 A <<= X;
176 continue;
177 case BPF_S_ALU_LSH_K:
178 A <<= K;
179 continue;
180 case BPF_S_ALU_RSH_X:
181 A >>= X;
182 continue;
183 case BPF_S_ALU_RSH_K:
184 A >>= K;
185 continue;
186 case BPF_S_ALU_NEG:
187 A = -A;
188 continue;
189 case BPF_S_JMP_JA:
190 fentry += K;
191 continue;
192 case BPF_S_JMP_JGT_K:
193 fentry += (A > K) ? fentry->jt : fentry->jf;
194 continue;
195 case BPF_S_JMP_JGE_K:
196 fentry += (A >= K) ? fentry->jt : fentry->jf;
197 continue;
198 case BPF_S_JMP_JEQ_K:
199 fentry += (A == K) ? fentry->jt : fentry->jf;
200 continue;
201 case BPF_S_JMP_JSET_K:
202 fentry += (A & K) ? fentry->jt : fentry->jf;
203 continue;
204 case BPF_S_JMP_JGT_X:
205 fentry += (A > X) ? fentry->jt : fentry->jf;
206 continue;
207 case BPF_S_JMP_JGE_X:
208 fentry += (A >= X) ? fentry->jt : fentry->jf;
209 continue;
210 case BPF_S_JMP_JEQ_X:
211 fentry += (A == X) ? fentry->jt : fentry->jf;
212 continue;
213 case BPF_S_JMP_JSET_X:
214 fentry += (A & X) ? fentry->jt : fentry->jf;
215 continue;
216 case BPF_S_LD_W_ABS:
217 k = K;
218 load_w:
219 ptr = load_pointer(skb, k, 4, &tmp);
220 if (ptr != NULL) {
221 A = get_unaligned_be32(ptr);
222 continue;
223 }
224 return 0;
225 case BPF_S_LD_H_ABS:
226 k = K;
227 load_h:
228 ptr = load_pointer(skb, k, 2, &tmp);
229 if (ptr != NULL) {
230 A = get_unaligned_be16(ptr);
231 continue;
232 }
233 return 0;
234 case BPF_S_LD_B_ABS:
235 k = K;
236 load_b:
237 ptr = load_pointer(skb, k, 1, &tmp);
238 if (ptr != NULL) {
239 A = *(u8 *)ptr;
240 continue;
241 }
242 return 0;
243 case BPF_S_LD_W_LEN:
244 A = skb->len;
245 continue;
246 case BPF_S_LDX_W_LEN:
247 X = skb->len;
248 continue;
249 case BPF_S_LD_W_IND:
250 k = X + K;
251 goto load_w;
252 case BPF_S_LD_H_IND:
253 k = X + K;
254 goto load_h;
255 case BPF_S_LD_B_IND:
256 k = X + K;
257 goto load_b;
258 case BPF_S_LDX_B_MSH:
259 ptr = load_pointer(skb, K, 1, &tmp);
260 if (ptr != NULL) {
261 X = (*(u8 *)ptr & 0xf) << 2;
262 continue;
263 }
264 return 0;
265 case BPF_S_LD_IMM:
266 A = K;
267 continue;
268 case BPF_S_LDX_IMM:
269 X = K;
270 continue;
271 case BPF_S_LD_MEM:
272 A = mem[K];
273 continue;
274 case BPF_S_LDX_MEM:
275 X = mem[K];
276 continue;
277 case BPF_S_MISC_TAX:
278 X = A;
279 continue;
280 case BPF_S_MISC_TXA:
281 A = X;
282 continue;
283 case BPF_S_RET_K:
284 return K;
285 case BPF_S_RET_A:
286 return A;
287 case BPF_S_ST:
288 mem[K] = A;
289 continue;
290 case BPF_S_STX:
291 mem[K] = X;
292 continue;
293 case BPF_S_ANC_PROTOCOL:
294 A = ntohs(skb->protocol);
295 continue;
296 case BPF_S_ANC_PKTTYPE:
297 A = skb->pkt_type;
298 continue;
299 case BPF_S_ANC_IFINDEX:
300 if (!skb->dev)
301 return 0;
302 A = skb->dev->ifindex;
303 continue;
304 case BPF_S_ANC_MARK:
305 A = skb->mark;
306 continue;
307 case BPF_S_ANC_QUEUE:
308 A = skb->queue_mapping;
309 continue;
310 case BPF_S_ANC_HATYPE:
311 if (!skb->dev)
312 return 0;
313 A = skb->dev->type;
314 continue;
315 case BPF_S_ANC_RXHASH:
316 A = skb->rxhash;
317 continue;
318 case BPF_S_ANC_CPU:
319 A = raw_smp_processor_id();
320 continue;
321 case BPF_S_ANC_ALU_XOR_X:
322 A ^= X;
323 continue;
324 case BPF_S_ANC_NLATTR: {
325 struct nlattr *nla;
326
327 if (skb_is_nonlinear(skb))
328 return 0;
329 if (A > skb->len - sizeof(struct nlattr))
330 return 0;
331
332 nla = nla_find((struct nlattr *)&skb->data[A],
333 skb->len - A, X);
334 if (nla)
335 A = (void *)nla - (void *)skb->data;
336 else
337 A = 0;
338 continue;
339 }
340 case BPF_S_ANC_NLATTR_NEST: {
341 struct nlattr *nla;
342
343 if (skb_is_nonlinear(skb))
344 return 0;
345 if (A > skb->len - sizeof(struct nlattr))
346 return 0;
347
348 nla = (struct nlattr *)&skb->data[A];
349 if (nla->nla_len > A - skb->len)
350 return 0;
351
352 nla = nla_find_nested(nla, X);
353 if (nla)
354 A = (void *)nla - (void *)skb->data;
355 else
356 A = 0;
357 continue;
358 }
359 #ifdef CONFIG_SECCOMP_FILTER
360 case BPF_S_ANC_SECCOMP_LD_W:
361 A = seccomp_bpf_load(fentry->k);
362 continue;
363 #endif
364 default:
365 WARN_RATELIMIT(1, "Unknown code:%u jt:%u tf:%u k:%u\n",
366 fentry->code, fentry->jt,
367 fentry->jf, fentry->k);
368 return 0;
369 }
370 }
371
372 return 0;
373 }
374 EXPORT_SYMBOL(sk_run_filter);
375
376 /*
377 * Security :
378 * A BPF program is able to use 16 cells of memory to store intermediate
379 * values (check u32 mem[BPF_MEMWORDS] in sk_run_filter())
380 * As we dont want to clear mem[] array for each packet going through
381 * sk_run_filter(), we check that filter loaded by user never try to read
382 * a cell if not previously written, and we check all branches to be sure
383 * a malicious user doesn't try to abuse us.
384 */
385 static int check_load_and_stores(struct sock_filter *filter, int flen)
386 {
387 u16 *masks, memvalid = 0; /* one bit per cell, 16 cells */
388 int pc, ret = 0;
389
390 BUILD_BUG_ON(BPF_MEMWORDS > 16);
391 masks = kmalloc(flen * sizeof(*masks), GFP_KERNEL);
392 if (!masks)
393 return -ENOMEM;
394 memset(masks, 0xff, flen * sizeof(*masks));
395
396 for (pc = 0; pc < flen; pc++) {
397 memvalid &= masks[pc];
398
399 switch (filter[pc].code) {
400 case BPF_S_ST:
401 case BPF_S_STX:
402 memvalid |= (1 << filter[pc].k);
403 break;
404 case BPF_S_LD_MEM:
405 case BPF_S_LDX_MEM:
406 if (!(memvalid & (1 << filter[pc].k))) {
407 ret = -EINVAL;
408 goto error;
409 }
410 break;
411 case BPF_S_JMP_JA:
412 /* a jump must set masks on target */
413 masks[pc + 1 + filter[pc].k] &= memvalid;
414 memvalid = ~0;
415 break;
416 case BPF_S_JMP_JEQ_K:
417 case BPF_S_JMP_JEQ_X:
418 case BPF_S_JMP_JGE_K:
419 case BPF_S_JMP_JGE_X:
420 case BPF_S_JMP_JGT_K:
421 case BPF_S_JMP_JGT_X:
422 case BPF_S_JMP_JSET_X:
423 case BPF_S_JMP_JSET_K:
424 /* a jump must set masks on targets */
425 masks[pc + 1 + filter[pc].jt] &= memvalid;
426 masks[pc + 1 + filter[pc].jf] &= memvalid;
427 memvalid = ~0;
428 break;
429 }
430 }
431 error:
432 kfree(masks);
433 return ret;
434 }
435
436 /**
437 * sk_chk_filter - verify socket filter code
438 * @filter: filter to verify
439 * @flen: length of filter
440 *
441 * Check the user's filter code. If we let some ugly
442 * filter code slip through kaboom! The filter must contain
443 * no references or jumps that are out of range, no illegal
444 * instructions, and must end with a RET instruction.
445 *
446 * All jumps are forward as they are not signed.
447 *
448 * Returns 0 if the rule set is legal or -EINVAL if not.
449 */
450 int sk_chk_filter(struct sock_filter *filter, unsigned int flen)
451 {
452 /*
453 * Valid instructions are initialized to non-0.
454 * Invalid instructions are initialized to 0.
455 */
456 static const u8 codes[] = {
457 [BPF_ALU|BPF_ADD|BPF_K] = BPF_S_ALU_ADD_K,
458 [BPF_ALU|BPF_ADD|BPF_X] = BPF_S_ALU_ADD_X,
459 [BPF_ALU|BPF_SUB|BPF_K] = BPF_S_ALU_SUB_K,
460 [BPF_ALU|BPF_SUB|BPF_X] = BPF_S_ALU_SUB_X,
461 [BPF_ALU|BPF_MUL|BPF_K] = BPF_S_ALU_MUL_K,
462 [BPF_ALU|BPF_MUL|BPF_X] = BPF_S_ALU_MUL_X,
463 [BPF_ALU|BPF_DIV|BPF_X] = BPF_S_ALU_DIV_X,
464 [BPF_ALU|BPF_AND|BPF_K] = BPF_S_ALU_AND_K,
465 [BPF_ALU|BPF_AND|BPF_X] = BPF_S_ALU_AND_X,
466 [BPF_ALU|BPF_OR|BPF_K] = BPF_S_ALU_OR_K,
467 [BPF_ALU|BPF_OR|BPF_X] = BPF_S_ALU_OR_X,
468 [BPF_ALU|BPF_LSH|BPF_K] = BPF_S_ALU_LSH_K,
469 [BPF_ALU|BPF_LSH|BPF_X] = BPF_S_ALU_LSH_X,
470 [BPF_ALU|BPF_RSH|BPF_K] = BPF_S_ALU_RSH_K,
471 [BPF_ALU|BPF_RSH|BPF_X] = BPF_S_ALU_RSH_X,
472 [BPF_ALU|BPF_NEG] = BPF_S_ALU_NEG,
473 [BPF_LD|BPF_W|BPF_ABS] = BPF_S_LD_W_ABS,
474 [BPF_LD|BPF_H|BPF_ABS] = BPF_S_LD_H_ABS,
475 [BPF_LD|BPF_B|BPF_ABS] = BPF_S_LD_B_ABS,
476 [BPF_LD|BPF_W|BPF_LEN] = BPF_S_LD_W_LEN,
477 [BPF_LD|BPF_W|BPF_IND] = BPF_S_LD_W_IND,
478 [BPF_LD|BPF_H|BPF_IND] = BPF_S_LD_H_IND,
479 [BPF_LD|BPF_B|BPF_IND] = BPF_S_LD_B_IND,
480 [BPF_LD|BPF_IMM] = BPF_S_LD_IMM,
481 [BPF_LDX|BPF_W|BPF_LEN] = BPF_S_LDX_W_LEN,
482 [BPF_LDX|BPF_B|BPF_MSH] = BPF_S_LDX_B_MSH,
483 [BPF_LDX|BPF_IMM] = BPF_S_LDX_IMM,
484 [BPF_MISC|BPF_TAX] = BPF_S_MISC_TAX,
485 [BPF_MISC|BPF_TXA] = BPF_S_MISC_TXA,
486 [BPF_RET|BPF_K] = BPF_S_RET_K,
487 [BPF_RET|BPF_A] = BPF_S_RET_A,
488 [BPF_ALU|BPF_DIV|BPF_K] = BPF_S_ALU_DIV_K,
489 [BPF_LD|BPF_MEM] = BPF_S_LD_MEM,
490 [BPF_LDX|BPF_MEM] = BPF_S_LDX_MEM,
491 [BPF_ST] = BPF_S_ST,
492 [BPF_STX] = BPF_S_STX,
493 [BPF_JMP|BPF_JA] = BPF_S_JMP_JA,
494 [BPF_JMP|BPF_JEQ|BPF_K] = BPF_S_JMP_JEQ_K,
495 [BPF_JMP|BPF_JEQ|BPF_X] = BPF_S_JMP_JEQ_X,
496 [BPF_JMP|BPF_JGE|BPF_K] = BPF_S_JMP_JGE_K,
497 [BPF_JMP|BPF_JGE|BPF_X] = BPF_S_JMP_JGE_X,
498 [BPF_JMP|BPF_JGT|BPF_K] = BPF_S_JMP_JGT_K,
499 [BPF_JMP|BPF_JGT|BPF_X] = BPF_S_JMP_JGT_X,
500 [BPF_JMP|BPF_JSET|BPF_K] = BPF_S_JMP_JSET_K,
501 [BPF_JMP|BPF_JSET|BPF_X] = BPF_S_JMP_JSET_X,
502 };
503 int pc;
504
505 if (flen == 0 || flen > BPF_MAXINSNS)
506 return -EINVAL;
507
508 /* check the filter code now */
509 for (pc = 0; pc < flen; pc++) {
510 struct sock_filter *ftest = &filter[pc];
511 u16 code = ftest->code;
512
513 if (code >= ARRAY_SIZE(codes))
514 return -EINVAL;
515 code = codes[code];
516 if (!code)
517 return -EINVAL;
518 /* Some instructions need special checks */
519 switch (code) {
520 case BPF_S_ALU_DIV_K:
521 /* check for division by zero */
522 if (ftest->k == 0)
523 return -EINVAL;
524 ftest->k = reciprocal_value(ftest->k);
525 break;
526 case BPF_S_LD_MEM:
527 case BPF_S_LDX_MEM:
528 case BPF_S_ST:
529 case BPF_S_STX:
530 /* check for invalid memory addresses */
531 if (ftest->k >= BPF_MEMWORDS)
532 return -EINVAL;
533 break;
534 case BPF_S_JMP_JA:
535 /*
536 * Note, the large ftest->k might cause loops.
537 * Compare this with conditional jumps below,
538 * where offsets are limited. --ANK (981016)
539 */
540 if (ftest->k >= (unsigned int)(flen-pc-1))
541 return -EINVAL;
542 break;
543 case BPF_S_JMP_JEQ_K:
544 case BPF_S_JMP_JEQ_X:
545 case BPF_S_JMP_JGE_K:
546 case BPF_S_JMP_JGE_X:
547 case BPF_S_JMP_JGT_K:
548 case BPF_S_JMP_JGT_X:
549 case BPF_S_JMP_JSET_X:
550 case BPF_S_JMP_JSET_K:
551 /* for conditionals both must be safe */
552 if (pc + ftest->jt + 1 >= flen ||
553 pc + ftest->jf + 1 >= flen)
554 return -EINVAL;
555 break;
556 case BPF_S_LD_W_ABS:
557 case BPF_S_LD_H_ABS:
558 case BPF_S_LD_B_ABS:
559 #define ANCILLARY(CODE) case SKF_AD_OFF + SKF_AD_##CODE: \
560 code = BPF_S_ANC_##CODE; \
561 break
562 switch (ftest->k) {
563 ANCILLARY(PROTOCOL);
564 ANCILLARY(PKTTYPE);
565 ANCILLARY(IFINDEX);
566 ANCILLARY(NLATTR);
567 ANCILLARY(NLATTR_NEST);
568 ANCILLARY(MARK);
569 ANCILLARY(QUEUE);
570 ANCILLARY(HATYPE);
571 ANCILLARY(RXHASH);
572 ANCILLARY(CPU);
573 ANCILLARY(ALU_XOR_X);
574 }
575 }
576 ftest->code = code;
577 }
578
579 /* last instruction must be a RET code */
580 switch (filter[flen - 1].code) {
581 case BPF_S_RET_K:
582 case BPF_S_RET_A:
583 return check_load_and_stores(filter, flen);
584 }
585 return -EINVAL;
586 }
587 EXPORT_SYMBOL(sk_chk_filter);
588
589 /**
590 * sk_filter_release_rcu - Release a socket filter by rcu_head
591 * @rcu: rcu_head that contains the sk_filter to free
592 */
593 void sk_filter_release_rcu(struct rcu_head *rcu)
594 {
595 struct sk_filter *fp = container_of(rcu, struct sk_filter, rcu);
596
597 bpf_jit_free(fp);
598 kfree(fp);
599 }
600 EXPORT_SYMBOL(sk_filter_release_rcu);
601
602 static int __sk_prepare_filter(struct sk_filter *fp)
603 {
604 int err;
605
606 fp->bpf_func = sk_run_filter;
607
608 err = sk_chk_filter(fp->insns, fp->len);
609 if (err)
610 return err;
611
612 bpf_jit_compile(fp);
613 return 0;
614 }
615
616 /**
617 * sk_unattached_filter_create - create an unattached filter
618 * @fprog: the filter program
619 * @pfp: the unattached filter that is created
620 *
621 * Create a filter independent of any socket. We first run some
622 * sanity checks on it to make sure it does not explode on us later.
623 * If an error occurs or there is insufficient memory for the filter
624 * a negative errno code is returned. On success the return is zero.
625 */
626 int sk_unattached_filter_create(struct sk_filter **pfp,
627 struct sock_fprog *fprog)
628 {
629 struct sk_filter *fp;
630 unsigned int fsize = sizeof(struct sock_filter) * fprog->len;
631 int err;
632
633 /* Make sure new filter is there and in the right amounts. */
634 if (fprog->filter == NULL)
635 return -EINVAL;
636
637 fp = kmalloc(fsize + sizeof(*fp), GFP_KERNEL);
638 if (!fp)
639 return -ENOMEM;
640 memcpy(fp->insns, fprog->filter, fsize);
641
642 atomic_set(&fp->refcnt, 1);
643 fp->len = fprog->len;
644
645 err = __sk_prepare_filter(fp);
646 if (err)
647 goto free_mem;
648
649 *pfp = fp;
650 return 0;
651 free_mem:
652 kfree(fp);
653 return err;
654 }
655 EXPORT_SYMBOL_GPL(sk_unattached_filter_create);
656
657 void sk_unattached_filter_destroy(struct sk_filter *fp)
658 {
659 sk_filter_release(fp);
660 }
661 EXPORT_SYMBOL_GPL(sk_unattached_filter_destroy);
662
663 /**
664 * sk_attach_filter - attach a socket filter
665 * @fprog: the filter program
666 * @sk: the socket to use
667 *
668 * Attach the user's filter code. We first run some sanity checks on
669 * it to make sure it does not explode on us later. If an error
670 * occurs or there is insufficient memory for the filter a negative
671 * errno code is returned. On success the return is zero.
672 */
673 int sk_attach_filter(struct sock_fprog *fprog, struct sock *sk)
674 {
675 struct sk_filter *fp, *old_fp;
676 unsigned int fsize = sizeof(struct sock_filter) * fprog->len;
677 int err;
678
679 /* Make sure new filter is there and in the right amounts. */
680 if (fprog->filter == NULL)
681 return -EINVAL;
682
683 fp = sock_kmalloc(sk, fsize+sizeof(*fp), GFP_KERNEL);
684 if (!fp)
685 return -ENOMEM;
686 if (copy_from_user(fp->insns, fprog->filter, fsize)) {
687 sock_kfree_s(sk, fp, fsize+sizeof(*fp));
688 return -EFAULT;
689 }
690
691 atomic_set(&fp->refcnt, 1);
692 fp->len = fprog->len;
693
694 err = __sk_prepare_filter(fp);
695 if (err) {
696 sk_filter_uncharge(sk, fp);
697 return err;
698 }
699
700 old_fp = rcu_dereference_protected(sk->sk_filter,
701 sock_owned_by_user(sk));
702 rcu_assign_pointer(sk->sk_filter, fp);
703
704 if (old_fp)
705 sk_filter_uncharge(sk, old_fp);
706 return 0;
707 }
708 EXPORT_SYMBOL_GPL(sk_attach_filter);
709
710 int sk_detach_filter(struct sock *sk)
711 {
712 int ret = -ENOENT;
713 struct sk_filter *filter;
714
715 filter = rcu_dereference_protected(sk->sk_filter,
716 sock_owned_by_user(sk));
717 if (filter) {
718 RCU_INIT_POINTER(sk->sk_filter, NULL);
719 sk_filter_uncharge(sk, filter);
720 ret = 0;
721 }
722 return ret;
723 }
724 EXPORT_SYMBOL_GPL(sk_detach_filter);
kernel source for telekom puls (alcatel/mediatek)