projects / deliverable / linux.git / blob
? search:
summary | shortlog | log | commit | commitdiff | tree
blame | history | raw | HEAD
filter: add MOD operation
[deliverable/linux.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 /*
87 * If the skb was allocated from pfmemalloc reserves, only
88 * allow SOCK_MEMALLOC sockets to use it as this socket is
89 * helping free memory
90 */
91 if (skb_pfmemalloc(skb) && !sock_flag(sk, SOCK_MEMALLOC))
92 return -ENOMEM;
93
94 err = security_sock_rcv_skb(sk, skb);
95 if (err)
96 return err;
97
98 rcu_read_lock();
99 filter = rcu_dereference(sk->sk_filter);
100 if (filter) {
101 unsigned int pkt_len = SK_RUN_FILTER(filter, skb);
102
103 err = pkt_len ? pskb_trim(skb, pkt_len) : -EPERM;
104 }
105 rcu_read_unlock();
106
107 return err;
108 }
109 EXPORT_SYMBOL(sk_filter);
110
111 /**
112 * sk_run_filter - run a filter on a socket
113 * @skb: buffer to run the filter on
114 * @fentry: filter to apply
115 *
116 * Decode and apply filter instructions to the skb->data.
117 * Return length to keep, 0 for none. @skb is the data we are
118 * filtering, @filter is the array of filter instructions.
119 * Because all jumps are guaranteed to be before last instruction,
120 * and last instruction guaranteed to be a RET, we dont need to check
121 * flen. (We used to pass to this function the length of filter)
122 */
123 unsigned int sk_run_filter(const struct sk_buff *skb,
124 const struct sock_filter *fentry)
125 {
126 void *ptr;
127 u32 A = 0; /* Accumulator */
128 u32 X = 0; /* Index Register */
129 u32 mem[BPF_MEMWORDS]; /* Scratch Memory Store */
130 u32 tmp;
131 int k;
132
133 /*
134 * Process array of filter instructions.
135 */
136 for (;; fentry++) {
137 #if defined(CONFIG_X86_32)
138 #define K (fentry->k)
139 #else
140 const u32 K = fentry->k;
141 #endif
142
143 switch (fentry->code) {
144 case BPF_S_ALU_ADD_X:
145 A += X;
146 continue;
147 case BPF_S_ALU_ADD_K:
148 A += K;
149 continue;
150 case BPF_S_ALU_SUB_X:
151 A -= X;
152 continue;
153 case BPF_S_ALU_SUB_K:
154 A -= K;
155 continue;
156 case BPF_S_ALU_MUL_X:
157 A *= X;
158 continue;
159 case BPF_S_ALU_MUL_K:
160 A *= K;
161 continue;
162 case BPF_S_ALU_DIV_X:
163 if (X == 0)
164 return 0;
165 A /= X;
166 continue;
167 case BPF_S_ALU_DIV_K:
168 A = reciprocal_divide(A, K);
169 continue;
170 case BPF_S_ALU_MOD_X:
171 if (X == 0)
172 return 0;
173 A %= X;
174 continue;
175 case BPF_S_ALU_MOD_K:
176 A %= K;
177 continue;
178 case BPF_S_ALU_AND_X:
179 A &= X;
180 continue;
181 case BPF_S_ALU_AND_K:
182 A &= K;
183 continue;
184 case BPF_S_ALU_OR_X:
185 A |= X;
186 continue;
187 case BPF_S_ALU_OR_K:
188 A |= K;
189 continue;
190 case BPF_S_ALU_LSH_X:
191 A <<= X;
192 continue;
193 case BPF_S_ALU_LSH_K:
194 A <<= K;
195 continue;
196 case BPF_S_ALU_RSH_X:
197 A >>= X;
198 continue;
199 case BPF_S_ALU_RSH_K:
200 A >>= K;
201 continue;
202 case BPF_S_ALU_NEG:
203 A = -A;
204 continue;
205 case BPF_S_JMP_JA:
206 fentry += K;
207 continue;
208 case BPF_S_JMP_JGT_K:
209 fentry += (A > K) ? fentry->jt : fentry->jf;
210 continue;
211 case BPF_S_JMP_JGE_K:
212 fentry += (A >= K) ? fentry->jt : fentry->jf;
213 continue;
214 case BPF_S_JMP_JEQ_K:
215 fentry += (A == K) ? fentry->jt : fentry->jf;
216 continue;
217 case BPF_S_JMP_JSET_K:
218 fentry += (A & K) ? fentry->jt : fentry->jf;
219 continue;
220 case BPF_S_JMP_JGT_X:
221 fentry += (A > X) ? fentry->jt : fentry->jf;
222 continue;
223 case BPF_S_JMP_JGE_X:
224 fentry += (A >= X) ? fentry->jt : fentry->jf;
225 continue;
226 case BPF_S_JMP_JEQ_X:
227 fentry += (A == X) ? fentry->jt : fentry->jf;
228 continue;
229 case BPF_S_JMP_JSET_X:
230 fentry += (A & X) ? fentry->jt : fentry->jf;
231 continue;
232 case BPF_S_LD_W_ABS:
233 k = K;
234 load_w:
235 ptr = load_pointer(skb, k, 4, &tmp);
236 if (ptr != NULL) {
237 A = get_unaligned_be32(ptr);
238 continue;
239 }
240 return 0;
241 case BPF_S_LD_H_ABS:
242 k = K;
243 load_h:
244 ptr = load_pointer(skb, k, 2, &tmp);
245 if (ptr != NULL) {
246 A = get_unaligned_be16(ptr);
247 continue;
248 }
249 return 0;
250 case BPF_S_LD_B_ABS:
251 k = K;
252 load_b:
253 ptr = load_pointer(skb, k, 1, &tmp);
254 if (ptr != NULL) {
255 A = *(u8 *)ptr;
256 continue;
257 }
258 return 0;
259 case BPF_S_LD_W_LEN:
260 A = skb->len;
261 continue;
262 case BPF_S_LDX_W_LEN:
263 X = skb->len;
264 continue;
265 case BPF_S_LD_W_IND:
266 k = X + K;
267 goto load_w;
268 case BPF_S_LD_H_IND:
269 k = X + K;
270 goto load_h;
271 case BPF_S_LD_B_IND:
272 k = X + K;
273 goto load_b;
274 case BPF_S_LDX_B_MSH:
275 ptr = load_pointer(skb, K, 1, &tmp);
276 if (ptr != NULL) {
277 X = (*(u8 *)ptr & 0xf) << 2;
278 continue;
279 }
280 return 0;
281 case BPF_S_LD_IMM:
282 A = K;
283 continue;
284 case BPF_S_LDX_IMM:
285 X = K;
286 continue;
287 case BPF_S_LD_MEM:
288 A = mem[K];
289 continue;
290 case BPF_S_LDX_MEM:
291 X = mem[K];
292 continue;
293 case BPF_S_MISC_TAX:
294 X = A;
295 continue;
296 case BPF_S_MISC_TXA:
297 A = X;
298 continue;
299 case BPF_S_RET_K:
300 return K;
301 case BPF_S_RET_A:
302 return A;
303 case BPF_S_ST:
304 mem[K] = A;
305 continue;
306 case BPF_S_STX:
307 mem[K] = X;
308 continue;
309 case BPF_S_ANC_PROTOCOL:
310 A = ntohs(skb->protocol);
311 continue;
312 case BPF_S_ANC_PKTTYPE:
313 A = skb->pkt_type;
314 continue;
315 case BPF_S_ANC_IFINDEX:
316 if (!skb->dev)
317 return 0;
318 A = skb->dev->ifindex;
319 continue;
320 case BPF_S_ANC_MARK:
321 A = skb->mark;
322 continue;
323 case BPF_S_ANC_QUEUE:
324 A = skb->queue_mapping;
325 continue;
326 case BPF_S_ANC_HATYPE:
327 if (!skb->dev)
328 return 0;
329 A = skb->dev->type;
330 continue;
331 case BPF_S_ANC_RXHASH:
332 A = skb->rxhash;
333 continue;
334 case BPF_S_ANC_CPU:
335 A = raw_smp_processor_id();
336 continue;
337 case BPF_S_ANC_ALU_XOR_X:
338 A ^= X;
339 continue;
340 case BPF_S_ANC_NLATTR: {
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 = nla_find((struct nlattr *)&skb->data[A],
349 skb->len - A, X);
350 if (nla)
351 A = (void *)nla - (void *)skb->data;
352 else
353 A = 0;
354 continue;
355 }
356 case BPF_S_ANC_NLATTR_NEST: {
357 struct nlattr *nla;
358
359 if (skb_is_nonlinear(skb))
360 return 0;
361 if (A > skb->len - sizeof(struct nlattr))
362 return 0;
363
364 nla = (struct nlattr *)&skb->data[A];
365 if (nla->nla_len > A - skb->len)
366 return 0;
367
368 nla = nla_find_nested(nla, X);
369 if (nla)
370 A = (void *)nla - (void *)skb->data;
371 else
372 A = 0;
373 continue;
374 }
375 #ifdef CONFIG_SECCOMP_FILTER
376 case BPF_S_ANC_SECCOMP_LD_W:
377 A = seccomp_bpf_load(fentry->k);
378 continue;
379 #endif
380 default:
381 WARN_RATELIMIT(1, "Unknown code:%u jt:%u tf:%u k:%u\n",
382 fentry->code, fentry->jt,
383 fentry->jf, fentry->k);
384 return 0;
385 }
386 }
387
388 return 0;
389 }
390 EXPORT_SYMBOL(sk_run_filter);
391
392 /*
393 * Security :
394 * A BPF program is able to use 16 cells of memory to store intermediate
395 * values (check u32 mem[BPF_MEMWORDS] in sk_run_filter())
396 * As we dont want to clear mem[] array for each packet going through
397 * sk_run_filter(), we check that filter loaded by user never try to read
398 * a cell if not previously written, and we check all branches to be sure
399 * a malicious user doesn't try to abuse us.
400 */
401 static int check_load_and_stores(struct sock_filter *filter, int flen)
402 {
403 u16 *masks, memvalid = 0; /* one bit per cell, 16 cells */
404 int pc, ret = 0;
405
406 BUILD_BUG_ON(BPF_MEMWORDS > 16);
407 masks = kmalloc(flen * sizeof(*masks), GFP_KERNEL);
408 if (!masks)
409 return -ENOMEM;
410 memset(masks, 0xff, flen * sizeof(*masks));
411
412 for (pc = 0; pc < flen; pc++) {
413 memvalid &= masks[pc];
414
415 switch (filter[pc].code) {
416 case BPF_S_ST:
417 case BPF_S_STX:
418 memvalid |= (1 << filter[pc].k);
419 break;
420 case BPF_S_LD_MEM:
421 case BPF_S_LDX_MEM:
422 if (!(memvalid & (1 << filter[pc].k))) {
423 ret = -EINVAL;
424 goto error;
425 }
426 break;
427 case BPF_S_JMP_JA:
428 /* a jump must set masks on target */
429 masks[pc + 1 + filter[pc].k] &= memvalid;
430 memvalid = ~0;
431 break;
432 case BPF_S_JMP_JEQ_K:
433 case BPF_S_JMP_JEQ_X:
434 case BPF_S_JMP_JGE_K:
435 case BPF_S_JMP_JGE_X:
436 case BPF_S_JMP_JGT_K:
437 case BPF_S_JMP_JGT_X:
438 case BPF_S_JMP_JSET_X:
439 case BPF_S_JMP_JSET_K:
440 /* a jump must set masks on targets */
441 masks[pc + 1 + filter[pc].jt] &= memvalid;
442 masks[pc + 1 + filter[pc].jf] &= memvalid;
443 memvalid = ~0;
444 break;
445 }
446 }
447 error:
448 kfree(masks);
449 return ret;
450 }
451
452 /**
453 * sk_chk_filter - verify socket filter code
454 * @filter: filter to verify
455 * @flen: length of filter
456 *
457 * Check the user's filter code. If we let some ugly
458 * filter code slip through kaboom! The filter must contain
459 * no references or jumps that are out of range, no illegal
460 * instructions, and must end with a RET instruction.
461 *
462 * All jumps are forward as they are not signed.
463 *
464 * Returns 0 if the rule set is legal or -EINVAL if not.
465 */
466 int sk_chk_filter(struct sock_filter *filter, unsigned int flen)
467 {
468 /*
469 * Valid instructions are initialized to non-0.
470 * Invalid instructions are initialized to 0.
471 */
472 static const u8 codes[] = {
473 [BPF_ALU|BPF_ADD|BPF_K] = BPF_S_ALU_ADD_K,
474 [BPF_ALU|BPF_ADD|BPF_X] = BPF_S_ALU_ADD_X,
475 [BPF_ALU|BPF_SUB|BPF_K] = BPF_S_ALU_SUB_K,
476 [BPF_ALU|BPF_SUB|BPF_X] = BPF_S_ALU_SUB_X,
477 [BPF_ALU|BPF_MUL|BPF_K] = BPF_S_ALU_MUL_K,
478 [BPF_ALU|BPF_MUL|BPF_X] = BPF_S_ALU_MUL_X,
479 [BPF_ALU|BPF_DIV|BPF_X] = BPF_S_ALU_DIV_X,
480 [BPF_ALU|BPF_MOD|BPF_K] = BPF_S_ALU_MOD_K,
481 [BPF_ALU|BPF_MOD|BPF_X] = BPF_S_ALU_MOD_X,
482 [BPF_ALU|BPF_AND|BPF_K] = BPF_S_ALU_AND_K,
483 [BPF_ALU|BPF_AND|BPF_X] = BPF_S_ALU_AND_X,
484 [BPF_ALU|BPF_OR|BPF_K] = BPF_S_ALU_OR_K,
485 [BPF_ALU|BPF_OR|BPF_X] = BPF_S_ALU_OR_X,
486 [BPF_ALU|BPF_LSH|BPF_K] = BPF_S_ALU_LSH_K,
487 [BPF_ALU|BPF_LSH|BPF_X] = BPF_S_ALU_LSH_X,
488 [BPF_ALU|BPF_RSH|BPF_K] = BPF_S_ALU_RSH_K,
489 [BPF_ALU|BPF_RSH|BPF_X] = BPF_S_ALU_RSH_X,
490 [BPF_ALU|BPF_NEG] = BPF_S_ALU_NEG,
491 [BPF_LD|BPF_W|BPF_ABS] = BPF_S_LD_W_ABS,
492 [BPF_LD|BPF_H|BPF_ABS] = BPF_S_LD_H_ABS,
493 [BPF_LD|BPF_B|BPF_ABS] = BPF_S_LD_B_ABS,
494 [BPF_LD|BPF_W|BPF_LEN] = BPF_S_LD_W_LEN,
495 [BPF_LD|BPF_W|BPF_IND] = BPF_S_LD_W_IND,
496 [BPF_LD|BPF_H|BPF_IND] = BPF_S_LD_H_IND,
497 [BPF_LD|BPF_B|BPF_IND] = BPF_S_LD_B_IND,
498 [BPF_LD|BPF_IMM] = BPF_S_LD_IMM,
499 [BPF_LDX|BPF_W|BPF_LEN] = BPF_S_LDX_W_LEN,
500 [BPF_LDX|BPF_B|BPF_MSH] = BPF_S_LDX_B_MSH,
501 [BPF_LDX|BPF_IMM] = BPF_S_LDX_IMM,
502 [BPF_MISC|BPF_TAX] = BPF_S_MISC_TAX,
503 [BPF_MISC|BPF_TXA] = BPF_S_MISC_TXA,
504 [BPF_RET|BPF_K] = BPF_S_RET_K,
505 [BPF_RET|BPF_A] = BPF_S_RET_A,
506 [BPF_ALU|BPF_DIV|BPF_K] = BPF_S_ALU_DIV_K,
507 [BPF_LD|BPF_MEM] = BPF_S_LD_MEM,
508 [BPF_LDX|BPF_MEM] = BPF_S_LDX_MEM,
509 [BPF_ST] = BPF_S_ST,
510 [BPF_STX] = BPF_S_STX,
511 [BPF_JMP|BPF_JA] = BPF_S_JMP_JA,
512 [BPF_JMP|BPF_JEQ|BPF_K] = BPF_S_JMP_JEQ_K,
513 [BPF_JMP|BPF_JEQ|BPF_X] = BPF_S_JMP_JEQ_X,
514 [BPF_JMP|BPF_JGE|BPF_K] = BPF_S_JMP_JGE_K,
515 [BPF_JMP|BPF_JGE|BPF_X] = BPF_S_JMP_JGE_X,
516 [BPF_JMP|BPF_JGT|BPF_K] = BPF_S_JMP_JGT_K,
517 [BPF_JMP|BPF_JGT|BPF_X] = BPF_S_JMP_JGT_X,
518 [BPF_JMP|BPF_JSET|BPF_K] = BPF_S_JMP_JSET_K,
519 [BPF_JMP|BPF_JSET|BPF_X] = BPF_S_JMP_JSET_X,
520 };
521 int pc;
522
523 if (flen == 0 || flen > BPF_MAXINSNS)
524 return -EINVAL;
525
526 /* check the filter code now */
527 for (pc = 0; pc < flen; pc++) {
528 struct sock_filter *ftest = &filter[pc];
529 u16 code = ftest->code;
530
531 if (code >= ARRAY_SIZE(codes))
532 return -EINVAL;
533 code = codes[code];
534 if (!code)
535 return -EINVAL;
536 /* Some instructions need special checks */
537 switch (code) {
538 case BPF_S_ALU_DIV_K:
539 /* check for division by zero */
540 if (ftest->k == 0)
541 return -EINVAL;
542 ftest->k = reciprocal_value(ftest->k);
543 break;
544 case BPF_S_ALU_MOD_K:
545 /* check for division by zero */
546 if (ftest->k == 0)
547 return -EINVAL;
548 break;
549 case BPF_S_LD_MEM:
550 case BPF_S_LDX_MEM:
551 case BPF_S_ST:
552 case BPF_S_STX:
553 /* check for invalid memory addresses */
554 if (ftest->k >= BPF_MEMWORDS)
555 return -EINVAL;
556 break;
557 case BPF_S_JMP_JA:
558 /*
559 * Note, the large ftest->k might cause loops.
560 * Compare this with conditional jumps below,
561 * where offsets are limited. --ANK (981016)
562 */
563 if (ftest->k >= (unsigned int)(flen-pc-1))
564 return -EINVAL;
565 break;
566 case BPF_S_JMP_JEQ_K:
567 case BPF_S_JMP_JEQ_X:
568 case BPF_S_JMP_JGE_K:
569 case BPF_S_JMP_JGE_X:
570 case BPF_S_JMP_JGT_K:
571 case BPF_S_JMP_JGT_X:
572 case BPF_S_JMP_JSET_X:
573 case BPF_S_JMP_JSET_K:
574 /* for conditionals both must be safe */
575 if (pc + ftest->jt + 1 >= flen ||
576 pc + ftest->jf + 1 >= flen)
577 return -EINVAL;
578 break;
579 case BPF_S_LD_W_ABS:
580 case BPF_S_LD_H_ABS:
581 case BPF_S_LD_B_ABS:
582 #define ANCILLARY(CODE) case SKF_AD_OFF + SKF_AD_##CODE: \
583 code = BPF_S_ANC_##CODE; \
584 break
585 switch (ftest->k) {
586 ANCILLARY(PROTOCOL);
587 ANCILLARY(PKTTYPE);
588 ANCILLARY(IFINDEX);
589 ANCILLARY(NLATTR);
590 ANCILLARY(NLATTR_NEST);
591 ANCILLARY(MARK);
592 ANCILLARY(QUEUE);
593 ANCILLARY(HATYPE);
594 ANCILLARY(RXHASH);
595 ANCILLARY(CPU);
596 ANCILLARY(ALU_XOR_X);
597 }
598 }
599 ftest->code = code;
600 }
601
602 /* last instruction must be a RET code */
603 switch (filter[flen - 1].code) {
604 case BPF_S_RET_K:
605 case BPF_S_RET_A:
606 return check_load_and_stores(filter, flen);
607 }
608 return -EINVAL;
609 }
610 EXPORT_SYMBOL(sk_chk_filter);
611
612 /**
613 * sk_filter_release_rcu - Release a socket filter by rcu_head
614 * @rcu: rcu_head that contains the sk_filter to free
615 */
616 void sk_filter_release_rcu(struct rcu_head *rcu)
617 {
618 struct sk_filter *fp = container_of(rcu, struct sk_filter, rcu);
619
620 bpf_jit_free(fp);
621 kfree(fp);
622 }
623 EXPORT_SYMBOL(sk_filter_release_rcu);
624
625 static int __sk_prepare_filter(struct sk_filter *fp)
626 {
627 int err;
628
629 fp->bpf_func = sk_run_filter;
630
631 err = sk_chk_filter(fp->insns, fp->len);
632 if (err)
633 return err;
634
635 bpf_jit_compile(fp);
636 return 0;
637 }
638
639 /**
640 * sk_unattached_filter_create - create an unattached filter
641 * @fprog: the filter program
642 * @pfp: the unattached filter that is created
643 *
644 * Create a filter independent of any socket. We first run some
645 * sanity checks on it to make sure it does not explode on us later.
646 * If an error occurs or there is insufficient memory for the filter
647 * a negative errno code is returned. On success the return is zero.
648 */
649 int sk_unattached_filter_create(struct sk_filter **pfp,
650 struct sock_fprog *fprog)
651 {
652 struct sk_filter *fp;
653 unsigned int fsize = sizeof(struct sock_filter) * fprog->len;
654 int err;
655
656 /* Make sure new filter is there and in the right amounts. */
657 if (fprog->filter == NULL)
658 return -EINVAL;
659
660 fp = kmalloc(fsize + sizeof(*fp), GFP_KERNEL);
661 if (!fp)
662 return -ENOMEM;
663 memcpy(fp->insns, fprog->filter, fsize);
664
665 atomic_set(&fp->refcnt, 1);
666 fp->len = fprog->len;
667
668 err = __sk_prepare_filter(fp);
669 if (err)
670 goto free_mem;
671
672 *pfp = fp;
673 return 0;
674 free_mem:
675 kfree(fp);
676 return err;
677 }
678 EXPORT_SYMBOL_GPL(sk_unattached_filter_create);
679
680 void sk_unattached_filter_destroy(struct sk_filter *fp)
681 {
682 sk_filter_release(fp);
683 }
684 EXPORT_SYMBOL_GPL(sk_unattached_filter_destroy);
685
686 /**
687 * sk_attach_filter - attach a socket filter
688 * @fprog: the filter program
689 * @sk: the socket to use
690 *
691 * Attach the user's filter code. We first run some sanity checks on
692 * it to make sure it does not explode on us later. If an error
693 * occurs or there is insufficient memory for the filter a negative
694 * errno code is returned. On success the return is zero.
695 */
696 int sk_attach_filter(struct sock_fprog *fprog, struct sock *sk)
697 {
698 struct sk_filter *fp, *old_fp;
699 unsigned int fsize = sizeof(struct sock_filter) * fprog->len;
700 int err;
701
702 /* Make sure new filter is there and in the right amounts. */
703 if (fprog->filter == NULL)
704 return -EINVAL;
705
706 fp = sock_kmalloc(sk, fsize+sizeof(*fp), GFP_KERNEL);
707 if (!fp)
708 return -ENOMEM;
709 if (copy_from_user(fp->insns, fprog->filter, fsize)) {
710 sock_kfree_s(sk, fp, fsize+sizeof(*fp));
711 return -EFAULT;
712 }
713
714 atomic_set(&fp->refcnt, 1);
715 fp->len = fprog->len;
716
717 err = __sk_prepare_filter(fp);
718 if (err) {
719 sk_filter_uncharge(sk, fp);
720 return err;
721 }
722
723 old_fp = rcu_dereference_protected(sk->sk_filter,
724 sock_owned_by_user(sk));
725 rcu_assign_pointer(sk->sk_filter, fp);
726
727 if (old_fp)
728 sk_filter_uncharge(sk, old_fp);
729 return 0;
730 }
731 EXPORT_SYMBOL_GPL(sk_attach_filter);
732
733 int sk_detach_filter(struct sock *sk)
734 {
735 int ret = -ENOENT;
736 struct sk_filter *filter;
737
738 filter = rcu_dereference_protected(sk->sk_filter,
739 sock_owned_by_user(sk));
740 if (filter) {
741 RCU_INIT_POINTER(sk->sk_filter, NULL);
742 sk_filter_uncharge(sk, filter);
743 ret = 0;
744 }
745 return ret;
746 }
747 EXPORT_SYMBOL_GPL(sk_detach_filter);
Linux kernel - Deliverables
This page took 0.044049 seconds and 5 git commands to generate.