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tuntap: fix leaking reference count
[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / net / core / filter.c
blobc23543cba132bc19a213ed242e47386e8e41ca65
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 #include <linux/if_vlan.h>
43
44 /* No hurry in this branch
45 *
46 * Exported for the bpf jit load helper.
47 */
48 void *bpf_internal_load_pointer_neg_helper(const struct sk_buff *skb, int k, unsigned int size)
49 {
50 u8 *ptr = NULL;
51
52 if (k >= SKF_NET_OFF)
53 ptr = skb_network_header(skb) + k - SKF_NET_OFF;
54 else if (k >= SKF_LL_OFF)
55 ptr = skb_mac_header(skb) + k - SKF_LL_OFF;
56
57 if (ptr >= skb->head && ptr + size <= skb_tail_pointer(skb))
58 return ptr;
59 return NULL;
60 }
61
62 static inline void *load_pointer(const struct sk_buff *skb, int k,
63 unsigned int size, void *buffer)
64 {
65 if (k >= 0)
66 return skb_header_pointer(skb, k, size, buffer);
67 return bpf_internal_load_pointer_neg_helper(skb, k, size);
68 }
69
70 /**
71 * sk_filter - run a packet through a socket filter
72 * @sk: sock associated with &sk_buff
73 * @skb: buffer to filter
74 *
75 * Run the filter code and then cut skb->data to correct size returned by
76 * sk_run_filter. If pkt_len is 0 we toss packet. If skb->len is smaller
77 * than pkt_len we keep whole skb->data. This is the socket level
78 * wrapper to sk_run_filter. It returns 0 if the packet should
79 * be accepted or -EPERM if the packet should be tossed.
80 *
81 */
82 int sk_filter(struct sock *sk, struct sk_buff *skb)
83 {
84 int err;
85 struct sk_filter *filter;
86
87 /*
88 * If the skb was allocated from pfmemalloc reserves, only
89 * allow SOCK_MEMALLOC sockets to use it as this socket is
90 * helping free memory
91 */
92 if (skb_pfmemalloc(skb) && !sock_flag(sk, SOCK_MEMALLOC))
93 return -ENOMEM;
94
95 err = security_sock_rcv_skb(sk, skb);
96 if (err)
97 return err;
98
99 rcu_read_lock();
100 filter = rcu_dereference(sk->sk_filter);
101 if (filter) {
102 unsigned int pkt_len = SK_RUN_FILTER(filter, skb);
103
104 err = pkt_len ? pskb_trim(skb, pkt_len) : -EPERM;
105 }
106 rcu_read_unlock();
107
108 return err;
109 }
110 EXPORT_SYMBOL(sk_filter);
111
112 /**
113 * sk_run_filter - run a filter on a socket
114 * @skb: buffer to run the filter on
115 * @fentry: filter to apply
116 *
117 * Decode and apply filter instructions to the skb->data.
118 * Return length to keep, 0 for none. @skb is the data we are
119 * filtering, @filter is the array of filter instructions.
120 * Because all jumps are guaranteed to be before last instruction,
121 * and last instruction guaranteed to be a RET, we dont need to check
122 * flen. (We used to pass to this function the length of filter)
123 */
124 unsigned int sk_run_filter(const struct sk_buff *skb,
125 const struct sock_filter *fentry)
126 {
127 void *ptr;
128 u32 A = 0; /* Accumulator */
129 u32 X = 0; /* Index Register */
130 u32 mem[BPF_MEMWORDS]; /* Scratch Memory Store */
131 u32 tmp;
132 int k;
133
134 /*
135 * Process array of filter instructions.
136 */
137 for (;; fentry++) {
138 #if defined(CONFIG_X86_32)
139 #define K (fentry->k)
140 #else
141 const u32 K = fentry->k;
142 #endif
143
144 switch (fentry->code) {
145 case BPF_S_ALU_ADD_X:
146 A += X;
147 continue;
148 case BPF_S_ALU_ADD_K:
149 A += K;
150 continue;
151 case BPF_S_ALU_SUB_X:
152 A -= X;
153 continue;
154 case BPF_S_ALU_SUB_K:
155 A -= K;
156 continue;
157 case BPF_S_ALU_MUL_X:
158 A *= X;
159 continue;
160 case BPF_S_ALU_MUL_K:
161 A *= K;
162 continue;
163 case BPF_S_ALU_DIV_X:
164 if (X == 0)
165 return 0;
166 A /= X;
167 continue;
168 case BPF_S_ALU_DIV_K:
169 A = reciprocal_divide(A, K);
170 continue;
171 case BPF_S_ALU_MOD_X:
172 if (X == 0)
173 return 0;
174 A %= X;
175 continue;
176 case BPF_S_ALU_MOD_K:
177 A %= K;
178 continue;
179 case BPF_S_ALU_AND_X:
180 A &= X;
181 continue;
182 case BPF_S_ALU_AND_K:
183 A &= K;
184 continue;
185 case BPF_S_ALU_OR_X:
186 A |= X;
187 continue;
188 case BPF_S_ALU_OR_K:
189 A |= K;
190 continue;
191 case BPF_S_ANC_ALU_XOR_X:
192 case BPF_S_ALU_XOR_X:
193 A ^= X;
194 continue;
195 case BPF_S_ALU_XOR_K:
196 A ^= K;
197 continue;
198 case BPF_S_ALU_LSH_X:
199 A <<= X;
200 continue;
201 case BPF_S_ALU_LSH_K:
202 A <<= K;
203 continue;
204 case BPF_S_ALU_RSH_X:
205 A >>= X;
206 continue;
207 case BPF_S_ALU_RSH_K:
208 A >>= K;
209 continue;
210 case BPF_S_ALU_NEG:
211 A = -A;
212 continue;
213 case BPF_S_JMP_JA:
214 fentry += K;
215 continue;
216 case BPF_S_JMP_JGT_K:
217 fentry += (A > K) ? fentry->jt : fentry->jf;
218 continue;
219 case BPF_S_JMP_JGE_K:
220 fentry += (A >= K) ? fentry->jt : fentry->jf;
221 continue;
222 case BPF_S_JMP_JEQ_K:
223 fentry += (A == K) ? fentry->jt : fentry->jf;
224 continue;
225 case BPF_S_JMP_JSET_K:
226 fentry += (A & K) ? fentry->jt : fentry->jf;
227 continue;
228 case BPF_S_JMP_JGT_X:
229 fentry += (A > X) ? fentry->jt : fentry->jf;
230 continue;
231 case BPF_S_JMP_JGE_X:
232 fentry += (A >= X) ? fentry->jt : fentry->jf;
233 continue;
234 case BPF_S_JMP_JEQ_X:
235 fentry += (A == X) ? fentry->jt : fentry->jf;
236 continue;
237 case BPF_S_JMP_JSET_X:
238 fentry += (A & X) ? fentry->jt : fentry->jf;
239 continue;
240 case BPF_S_LD_W_ABS:
241 k = K;
242 load_w:
243 ptr = load_pointer(skb, k, 4, &tmp);
244 if (ptr != NULL) {
245 A = get_unaligned_be32(ptr);
246 continue;
247 }
248 return 0;
249 case BPF_S_LD_H_ABS:
250 k = K;
251 load_h:
252 ptr = load_pointer(skb, k, 2, &tmp);
253 if (ptr != NULL) {
254 A = get_unaligned_be16(ptr);
255 continue;
256 }
257 return 0;
258 case BPF_S_LD_B_ABS:
259 k = K;
260 load_b:
261 ptr = load_pointer(skb, k, 1, &tmp);
262 if (ptr != NULL) {
263 A = *(u8 *)ptr;
264 continue;
265 }
266 return 0;
267 case BPF_S_LD_W_LEN:
268 A = skb->len;
269 continue;
270 case BPF_S_LDX_W_LEN:
271 X = skb->len;
272 continue;
273 case BPF_S_LD_W_IND:
274 k = X + K;
275 goto load_w;
276 case BPF_S_LD_H_IND:
277 k = X + K;
278 goto load_h;
279 case BPF_S_LD_B_IND:
280 k = X + K;
281 goto load_b;
282 case BPF_S_LDX_B_MSH:
283 ptr = load_pointer(skb, K, 1, &tmp);
284 if (ptr != NULL) {
285 X = (*(u8 *)ptr & 0xf) << 2;
286 continue;
287 }
288 return 0;
289 case BPF_S_LD_IMM:
290 A = K;
291 continue;
292 case BPF_S_LDX_IMM:
293 X = K;
294 continue;
295 case BPF_S_LD_MEM:
296 A = mem[K];
297 continue;
298 case BPF_S_LDX_MEM:
299 X = mem[K];
300 continue;
301 case BPF_S_MISC_TAX:
302 X = A;
303 continue;
304 case BPF_S_MISC_TXA:
305 A = X;
306 continue;
307 case BPF_S_RET_K:
308 return K;
309 case BPF_S_RET_A:
310 return A;
311 case BPF_S_ST:
312 mem[K] = A;
313 continue;
314 case BPF_S_STX:
315 mem[K] = X;
316 continue;
317 case BPF_S_ANC_PROTOCOL:
318 A = ntohs(skb->protocol);
319 continue;
320 case BPF_S_ANC_PKTTYPE:
321 A = skb->pkt_type;
322 continue;
323 case BPF_S_ANC_IFINDEX:
324 if (!skb->dev)
325 return 0;
326 A = skb->dev->ifindex;
327 continue;
328 case BPF_S_ANC_MARK:
329 A = skb->mark;
330 continue;
331 case BPF_S_ANC_QUEUE:
332 A = skb->queue_mapping;
333 continue;
334 case BPF_S_ANC_HATYPE:
335 if (!skb->dev)
336 return 0;
337 A = skb->dev->type;
338 continue;
339 case BPF_S_ANC_RXHASH:
340 A = skb->rxhash;
341 continue;
342 case BPF_S_ANC_CPU:
343 A = raw_smp_processor_id();
344 continue;
345 case BPF_S_ANC_VLAN_TAG:
346 A = vlan_tx_tag_get(skb);
347 continue;
348 case BPF_S_ANC_VLAN_TAG_PRESENT:
349 A = !!vlan_tx_tag_present(skb);
350 continue;
351 case BPF_S_ANC_NLATTR: {
352 struct nlattr *nla;
353
354 if (skb_is_nonlinear(skb))
355 return 0;
356 if (A > skb->len - sizeof(struct nlattr))
357 return 0;
358
359 nla = nla_find((struct nlattr *)&skb->data[A],
360 skb->len - A, X);
361 if (nla)
362 A = (void *)nla - (void *)skb->data;
363 else
364 A = 0;
365 continue;
366 }
367 case BPF_S_ANC_NLATTR_NEST: {
368 struct nlattr *nla;
369
370 if (skb_is_nonlinear(skb))
371 return 0;
372 if (A > skb->len - sizeof(struct nlattr))
373 return 0;
374
375 nla = (struct nlattr *)&skb->data[A];
376 if (nla->nla_len > A - skb->len)
377 return 0;
378
379 nla = nla_find_nested(nla, X);
380 if (nla)
381 A = (void *)nla - (void *)skb->data;
382 else
383 A = 0;
384 continue;
385 }
386 #ifdef CONFIG_SECCOMP_FILTER
387 case BPF_S_ANC_SECCOMP_LD_W:
388 A = seccomp_bpf_load(fentry->k);
389 continue;
390 #endif
391 default:
392 WARN_RATELIMIT(1, "Unknown code:%u jt:%u tf:%u k:%u\n",
393 fentry->code, fentry->jt,
394 fentry->jf, fentry->k);
395 return 0;
396 }
397 }
398
399 return 0;
400 }
401 EXPORT_SYMBOL(sk_run_filter);
402
403 /*
404 * Security :
405 * A BPF program is able to use 16 cells of memory to store intermediate
406 * values (check u32 mem[BPF_MEMWORDS] in sk_run_filter())
407 * As we dont want to clear mem[] array for each packet going through
408 * sk_run_filter(), we check that filter loaded by user never try to read
409 * a cell if not previously written, and we check all branches to be sure
410 * a malicious user doesn't try to abuse us.
411 */
412 static int check_load_and_stores(struct sock_filter *filter, int flen)
413 {
414 u16 *masks, memvalid = 0; /* one bit per cell, 16 cells */
415 int pc, ret = 0;
416
417 BUILD_BUG_ON(BPF_MEMWORDS > 16);
418 masks = kmalloc(flen * sizeof(*masks), GFP_KERNEL);
419 if (!masks)
420 return -ENOMEM;
421 memset(masks, 0xff, flen * sizeof(*masks));
422
423 for (pc = 0; pc < flen; pc++) {
424 memvalid &= masks[pc];
425
426 switch (filter[pc].code) {
427 case BPF_S_ST:
428 case BPF_S_STX:
429 memvalid |= (1 << filter[pc].k);
430 break;
431 case BPF_S_LD_MEM:
432 case BPF_S_LDX_MEM:
433 if (!(memvalid & (1 << filter[pc].k))) {
434 ret = -EINVAL;
435 goto error;
436 }
437 break;
438 case BPF_S_JMP_JA:
439 /* a jump must set masks on target */
440 masks[pc + 1 + filter[pc].k] &= memvalid;
441 memvalid = ~0;
442 break;
443 case BPF_S_JMP_JEQ_K:
444 case BPF_S_JMP_JEQ_X:
445 case BPF_S_JMP_JGE_K:
446 case BPF_S_JMP_JGE_X:
447 case BPF_S_JMP_JGT_K:
448 case BPF_S_JMP_JGT_X:
449 case BPF_S_JMP_JSET_X:
450 case BPF_S_JMP_JSET_K:
451 /* a jump must set masks on targets */
452 masks[pc + 1 + filter[pc].jt] &= memvalid;
453 masks[pc + 1 + filter[pc].jf] &= memvalid;
454 memvalid = ~0;
455 break;
456 }
457 }
458 error:
459 kfree(masks);
460 return ret;
461 }
462
463 /**
464 * sk_chk_filter - verify socket filter code
465 * @filter: filter to verify
466 * @flen: length of filter
467 *
468 * Check the user's filter code. If we let some ugly
469 * filter code slip through kaboom! The filter must contain
470 * no references or jumps that are out of range, no illegal
471 * instructions, and must end with a RET instruction.
472 *
473 * All jumps are forward as they are not signed.
474 *
475 * Returns 0 if the rule set is legal or -EINVAL if not.
476 */
477 int sk_chk_filter(struct sock_filter *filter, unsigned int flen)
478 {
479 /*
480 * Valid instructions are initialized to non-0.
481 * Invalid instructions are initialized to 0.
482 */
483 static const u8 codes[] = {
484 [BPF_ALU|BPF_ADD|BPF_K] = BPF_S_ALU_ADD_K,
485 [BPF_ALU|BPF_ADD|BPF_X] = BPF_S_ALU_ADD_X,
486 [BPF_ALU|BPF_SUB|BPF_K] = BPF_S_ALU_SUB_K,
487 [BPF_ALU|BPF_SUB|BPF_X] = BPF_S_ALU_SUB_X,
488 [BPF_ALU|BPF_MUL|BPF_K] = BPF_S_ALU_MUL_K,
489 [BPF_ALU|BPF_MUL|BPF_X] = BPF_S_ALU_MUL_X,
490 [BPF_ALU|BPF_DIV|BPF_X] = BPF_S_ALU_DIV_X,
491 [BPF_ALU|BPF_MOD|BPF_K] = BPF_S_ALU_MOD_K,
492 [BPF_ALU|BPF_MOD|BPF_X] = BPF_S_ALU_MOD_X,
493 [BPF_ALU|BPF_AND|BPF_K] = BPF_S_ALU_AND_K,
494 [BPF_ALU|BPF_AND|BPF_X] = BPF_S_ALU_AND_X,
495 [BPF_ALU|BPF_OR|BPF_K] = BPF_S_ALU_OR_K,
496 [BPF_ALU|BPF_OR|BPF_X] = BPF_S_ALU_OR_X,
497 [BPF_ALU|BPF_XOR|BPF_K] = BPF_S_ALU_XOR_K,
498 [BPF_ALU|BPF_XOR|BPF_X] = BPF_S_ALU_XOR_X,
499 [BPF_ALU|BPF_LSH|BPF_K] = BPF_S_ALU_LSH_K,
500 [BPF_ALU|BPF_LSH|BPF_X] = BPF_S_ALU_LSH_X,
501 [BPF_ALU|BPF_RSH|BPF_K] = BPF_S_ALU_RSH_K,
502 [BPF_ALU|BPF_RSH|BPF_X] = BPF_S_ALU_RSH_X,
503 [BPF_ALU|BPF_NEG] = BPF_S_ALU_NEG,
504 [BPF_LD|BPF_W|BPF_ABS] = BPF_S_LD_W_ABS,
505 [BPF_LD|BPF_H|BPF_ABS] = BPF_S_LD_H_ABS,
506 [BPF_LD|BPF_B|BPF_ABS] = BPF_S_LD_B_ABS,
507 [BPF_LD|BPF_W|BPF_LEN] = BPF_S_LD_W_LEN,
508 [BPF_LD|BPF_W|BPF_IND] = BPF_S_LD_W_IND,
509 [BPF_LD|BPF_H|BPF_IND] = BPF_S_LD_H_IND,
510 [BPF_LD|BPF_B|BPF_IND] = BPF_S_LD_B_IND,
511 [BPF_LD|BPF_IMM] = BPF_S_LD_IMM,
512 [BPF_LDX|BPF_W|BPF_LEN] = BPF_S_LDX_W_LEN,
513 [BPF_LDX|BPF_B|BPF_MSH] = BPF_S_LDX_B_MSH,
514 [BPF_LDX|BPF_IMM] = BPF_S_LDX_IMM,
515 [BPF_MISC|BPF_TAX] = BPF_S_MISC_TAX,
516 [BPF_MISC|BPF_TXA] = BPF_S_MISC_TXA,
517 [BPF_RET|BPF_K] = BPF_S_RET_K,
518 [BPF_RET|BPF_A] = BPF_S_RET_A,
519 [BPF_ALU|BPF_DIV|BPF_K] = BPF_S_ALU_DIV_K,
520 [BPF_LD|BPF_MEM] = BPF_S_LD_MEM,
521 [BPF_LDX|BPF_MEM] = BPF_S_LDX_MEM,
522 [BPF_ST] = BPF_S_ST,
523 [BPF_STX] = BPF_S_STX,
524 [BPF_JMP|BPF_JA] = BPF_S_JMP_JA,
525 [BPF_JMP|BPF_JEQ|BPF_K] = BPF_S_JMP_JEQ_K,
526 [BPF_JMP|BPF_JEQ|BPF_X] = BPF_S_JMP_JEQ_X,
527 [BPF_JMP|BPF_JGE|BPF_K] = BPF_S_JMP_JGE_K,
528 [BPF_JMP|BPF_JGE|BPF_X] = BPF_S_JMP_JGE_X,
529 [BPF_JMP|BPF_JGT|BPF_K] = BPF_S_JMP_JGT_K,
530 [BPF_JMP|BPF_JGT|BPF_X] = BPF_S_JMP_JGT_X,
531 [BPF_JMP|BPF_JSET|BPF_K] = BPF_S_JMP_JSET_K,
532 [BPF_JMP|BPF_JSET|BPF_X] = BPF_S_JMP_JSET_X,
533 };
534 int pc;
535
536 if (flen == 0 || flen > BPF_MAXINSNS)
537 return -EINVAL;
538
539 /* check the filter code now */
540 for (pc = 0; pc < flen; pc++) {
541 struct sock_filter *ftest = &filter[pc];
542 u16 code = ftest->code;
543
544 if (code >= ARRAY_SIZE(codes))
545 return -EINVAL;
546 code = codes[code];
547 if (!code)
548 return -EINVAL;
549 /* Some instructions need special checks */
550 switch (code) {
551 case BPF_S_ALU_DIV_K:
552 /* check for division by zero */
553 if (ftest->k == 0)
554 return -EINVAL;
555 ftest->k = reciprocal_value(ftest->k);
556 break;
557 case BPF_S_ALU_MOD_K:
558 /* check for division by zero */
559 if (ftest->k == 0)
560 return -EINVAL;
561 break;
562 case BPF_S_LD_MEM:
563 case BPF_S_LDX_MEM:
564 case BPF_S_ST:
565 case BPF_S_STX:
566 /* check for invalid memory addresses */
567 if (ftest->k >= BPF_MEMWORDS)
568 return -EINVAL;
569 break;
570 case BPF_S_JMP_JA:
571 /*
572 * Note, the large ftest->k might cause loops.
573 * Compare this with conditional jumps below,
574 * where offsets are limited. --ANK (981016)
575 */
576 if (ftest->k >= (unsigned int)(flen-pc-1))
577 return -EINVAL;
578 break;
579 case BPF_S_JMP_JEQ_K:
580 case BPF_S_JMP_JEQ_X:
581 case BPF_S_JMP_JGE_K:
582 case BPF_S_JMP_JGE_X:
583 case BPF_S_JMP_JGT_K:
584 case BPF_S_JMP_JGT_X:
585 case BPF_S_JMP_JSET_X:
586 case BPF_S_JMP_JSET_K:
587 /* for conditionals both must be safe */
588 if (pc + ftest->jt + 1 >= flen ||
589 pc + ftest->jf + 1 >= flen)
590 return -EINVAL;
591 break;
592 case BPF_S_LD_W_ABS:
593 case BPF_S_LD_H_ABS:
594 case BPF_S_LD_B_ABS:
595 #define ANCILLARY(CODE) case SKF_AD_OFF + SKF_AD_##CODE: \
596 code = BPF_S_ANC_##CODE; \
597 break
598 switch (ftest->k) {
599 ANCILLARY(PROTOCOL);
600 ANCILLARY(PKTTYPE);
601 ANCILLARY(IFINDEX);
602 ANCILLARY(NLATTR);
603 ANCILLARY(NLATTR_NEST);
604 ANCILLARY(MARK);
605 ANCILLARY(QUEUE);
606 ANCILLARY(HATYPE);
607 ANCILLARY(RXHASH);
608 ANCILLARY(CPU);
609 ANCILLARY(ALU_XOR_X);
610 ANCILLARY(VLAN_TAG);
611 ANCILLARY(VLAN_TAG_PRESENT);
612 }
613 }
614 ftest->code = code;
615 }
616
617 /* last instruction must be a RET code */
618 switch (filter[flen - 1].code) {
619 case BPF_S_RET_K:
620 case BPF_S_RET_A:
621 return check_load_and_stores(filter, flen);
622 }
623 return -EINVAL;
624 }
625 EXPORT_SYMBOL(sk_chk_filter);
626
627 /**
628 * sk_filter_release_rcu - Release a socket filter by rcu_head
629 * @rcu: rcu_head that contains the sk_filter to free
630 */
631 void sk_filter_release_rcu(struct rcu_head *rcu)
632 {
633 struct sk_filter *fp = container_of(rcu, struct sk_filter, rcu);
634
635 bpf_jit_free(fp);
636 kfree(fp);
637 }
638 EXPORT_SYMBOL(sk_filter_release_rcu);
639
640 static int __sk_prepare_filter(struct sk_filter *fp)
641 {
642 int err;
643
644 fp->bpf_func = sk_run_filter;
645
646 err = sk_chk_filter(fp->insns, fp->len);
647 if (err)
648 return err;
649
650 bpf_jit_compile(fp);
651 return 0;
652 }
653
654 /**
655 * sk_unattached_filter_create - create an unattached filter
656 * @fprog: the filter program
657 * @pfp: the unattached filter that is created
658 *
659 * Create a filter independent of any socket. We first run some
660 * sanity checks on it to make sure it does not explode on us later.
661 * If an error occurs or there is insufficient memory for the filter
662 * a negative errno code is returned. On success the return is zero.
663 */
664 int sk_unattached_filter_create(struct sk_filter **pfp,
665 struct sock_fprog *fprog)
666 {
667 struct sk_filter *fp;
668 unsigned int fsize = sizeof(struct sock_filter) * fprog->len;
669 int err;
670
671 /* Make sure new filter is there and in the right amounts. */
672 if (fprog->filter == NULL)
673 return -EINVAL;
674
675 fp = kmalloc(fsize + sizeof(*fp), GFP_KERNEL);
676 if (!fp)
677 return -ENOMEM;
678 memcpy(fp->insns, fprog->filter, fsize);
679
680 atomic_set(&fp->refcnt, 1);
681 fp->len = fprog->len;
682
683 err = __sk_prepare_filter(fp);
684 if (err)
685 goto free_mem;
686
687 *pfp = fp;
688 return 0;
689 free_mem:
690 kfree(fp);
691 return err;
692 }
693 EXPORT_SYMBOL_GPL(sk_unattached_filter_create);
694
695 void sk_unattached_filter_destroy(struct sk_filter *fp)
696 {
697 sk_filter_release(fp);
698 }
699 EXPORT_SYMBOL_GPL(sk_unattached_filter_destroy);
700
701 /**
702 * sk_attach_filter - attach a socket filter
703 * @fprog: the filter program
704 * @sk: the socket to use
705 *
706 * Attach the user's filter code. We first run some sanity checks on
707 * it to make sure it does not explode on us later. If an error
708 * occurs or there is insufficient memory for the filter a negative
709 * errno code is returned. On success the return is zero.
710 */
711 int sk_attach_filter(struct sock_fprog *fprog, struct sock *sk)
712 {
713 struct sk_filter *fp, *old_fp;
714 unsigned int fsize = sizeof(struct sock_filter) * fprog->len;
715 int err;
716
717 /* Make sure new filter is there and in the right amounts. */
718 if (fprog->filter == NULL)
719 return -EINVAL;
720
721 fp = sock_kmalloc(sk, fsize+sizeof(*fp), GFP_KERNEL);
722 if (!fp)
723 return -ENOMEM;
724 if (copy_from_user(fp->insns, fprog->filter, fsize)) {
725 sock_kfree_s(sk, fp, fsize+sizeof(*fp));
726 return -EFAULT;
727 }
728
729 atomic_set(&fp->refcnt, 1);
730 fp->len = fprog->len;
731
732 err = __sk_prepare_filter(fp);
733 if (err) {
734 sk_filter_uncharge(sk, fp);
735 return err;
736 }
737
738 old_fp = rcu_dereference_protected(sk->sk_filter,
739 sock_owned_by_user(sk));
740 rcu_assign_pointer(sk->sk_filter, fp);
741
742 if (old_fp)
743 sk_filter_uncharge(sk, old_fp);
744 return 0;
745 }
746 EXPORT_SYMBOL_GPL(sk_attach_filter);
747
748 int sk_detach_filter(struct sock *sk)
749 {
750 int ret = -ENOENT;
751 struct sk_filter *filter;
752
753 filter = rcu_dereference_protected(sk->sk_filter,
754 sock_owned_by_user(sk));
755 if (filter) {
756 RCU_INIT_POINTER(sk->sk_filter, NULL);
757 sk_filter_uncharge(sk, filter);
758 ret = 0;
759 }
760 return ret;
761 }
762 EXPORT_SYMBOL_GPL(sk_detach_filter);
763
764 static void sk_decode_filter(struct sock_filter *filt, struct sock_filter *to)
765 {
766 static const u16 decodes[] = {
767 [BPF_S_ALU_ADD_K] = BPF_ALU|BPF_ADD|BPF_K,
768 [BPF_S_ALU_ADD_X] = BPF_ALU|BPF_ADD|BPF_X,
769 [BPF_S_ALU_SUB_K] = BPF_ALU|BPF_SUB|BPF_K,
770 [BPF_S_ALU_SUB_X] = BPF_ALU|BPF_SUB|BPF_X,
771 [BPF_S_ALU_MUL_K] = BPF_ALU|BPF_MUL|BPF_K,
772 [BPF_S_ALU_MUL_X] = BPF_ALU|BPF_MUL|BPF_X,
773 [BPF_S_ALU_DIV_X] = BPF_ALU|BPF_DIV|BPF_X,
774 [BPF_S_ALU_MOD_K] = BPF_ALU|BPF_MOD|BPF_K,
775 [BPF_S_ALU_MOD_X] = BPF_ALU|BPF_MOD|BPF_X,
776 [BPF_S_ALU_AND_K] = BPF_ALU|BPF_AND|BPF_K,
777 [BPF_S_ALU_AND_X] = BPF_ALU|BPF_AND|BPF_X,
778 [BPF_S_ALU_OR_K] = BPF_ALU|BPF_OR|BPF_K,
779 [BPF_S_ALU_OR_X] = BPF_ALU|BPF_OR|BPF_X,
780 [BPF_S_ALU_XOR_K] = BPF_ALU|BPF_XOR|BPF_K,
781 [BPF_S_ALU_XOR_X] = BPF_ALU|BPF_XOR|BPF_X,
782 [BPF_S_ALU_LSH_K] = BPF_ALU|BPF_LSH|BPF_K,
783 [BPF_S_ALU_LSH_X] = BPF_ALU|BPF_LSH|BPF_X,
784 [BPF_S_ALU_RSH_K] = BPF_ALU|BPF_RSH|BPF_K,
785 [BPF_S_ALU_RSH_X] = BPF_ALU|BPF_RSH|BPF_X,
786 [BPF_S_ALU_NEG] = BPF_ALU|BPF_NEG,
787 [BPF_S_LD_W_ABS] = BPF_LD|BPF_W|BPF_ABS,
788 [BPF_S_LD_H_ABS] = BPF_LD|BPF_H|BPF_ABS,
789 [BPF_S_LD_B_ABS] = BPF_LD|BPF_B|BPF_ABS,
790 [BPF_S_ANC_PROTOCOL] = BPF_LD|BPF_B|BPF_ABS,
791 [BPF_S_ANC_PKTTYPE] = BPF_LD|BPF_B|BPF_ABS,
792 [BPF_S_ANC_IFINDEX] = BPF_LD|BPF_B|BPF_ABS,
793 [BPF_S_ANC_NLATTR] = BPF_LD|BPF_B|BPF_ABS,
794 [BPF_S_ANC_NLATTR_NEST] = BPF_LD|BPF_B|BPF_ABS,
795 [BPF_S_ANC_MARK] = BPF_LD|BPF_B|BPF_ABS,
796 [BPF_S_ANC_QUEUE] = BPF_LD|BPF_B|BPF_ABS,
797 [BPF_S_ANC_HATYPE] = BPF_LD|BPF_B|BPF_ABS,
798 [BPF_S_ANC_RXHASH] = BPF_LD|BPF_B|BPF_ABS,
799 [BPF_S_ANC_CPU] = BPF_LD|BPF_B|BPF_ABS,
800 [BPF_S_ANC_ALU_XOR_X] = BPF_LD|BPF_B|BPF_ABS,
801 [BPF_S_ANC_SECCOMP_LD_W] = BPF_LD|BPF_B|BPF_ABS,
802 [BPF_S_ANC_VLAN_TAG] = BPF_LD|BPF_B|BPF_ABS,
803 [BPF_S_ANC_VLAN_TAG_PRESENT] = BPF_LD|BPF_B|BPF_ABS,
804 [BPF_S_LD_W_LEN] = BPF_LD|BPF_W|BPF_LEN,
805 [BPF_S_LD_W_IND] = BPF_LD|BPF_W|BPF_IND,
806 [BPF_S_LD_H_IND] = BPF_LD|BPF_H|BPF_IND,
807 [BPF_S_LD_B_IND] = BPF_LD|BPF_B|BPF_IND,
808 [BPF_S_LD_IMM] = BPF_LD|BPF_IMM,
809 [BPF_S_LDX_W_LEN] = BPF_LDX|BPF_W|BPF_LEN,
810 [BPF_S_LDX_B_MSH] = BPF_LDX|BPF_B|BPF_MSH,
811 [BPF_S_LDX_IMM] = BPF_LDX|BPF_IMM,
812 [BPF_S_MISC_TAX] = BPF_MISC|BPF_TAX,
813 [BPF_S_MISC_TXA] = BPF_MISC|BPF_TXA,
814 [BPF_S_RET_K] = BPF_RET|BPF_K,
815 [BPF_S_RET_A] = BPF_RET|BPF_A,
816 [BPF_S_ALU_DIV_K] = BPF_ALU|BPF_DIV|BPF_K,
817 [BPF_S_LD_MEM] = BPF_LD|BPF_MEM,
818 [BPF_S_LDX_MEM] = BPF_LDX|BPF_MEM,
819 [BPF_S_ST] = BPF_ST,
820 [BPF_S_STX] = BPF_STX,
821 [BPF_S_JMP_JA] = BPF_JMP|BPF_JA,
822 [BPF_S_JMP_JEQ_K] = BPF_JMP|BPF_JEQ|BPF_K,
823 [BPF_S_JMP_JEQ_X] = BPF_JMP|BPF_JEQ|BPF_X,
824 [BPF_S_JMP_JGE_K] = BPF_JMP|BPF_JGE|BPF_K,
825 [BPF_S_JMP_JGE_X] = BPF_JMP|BPF_JGE|BPF_X,
826 [BPF_S_JMP_JGT_K] = BPF_JMP|BPF_JGT|BPF_K,
827 [BPF_S_JMP_JGT_X] = BPF_JMP|BPF_JGT|BPF_X,
828 [BPF_S_JMP_JSET_K] = BPF_JMP|BPF_JSET|BPF_K,
829 [BPF_S_JMP_JSET_X] = BPF_JMP|BPF_JSET|BPF_X,
830 };
831 u16 code;
832
833 code = filt->code;
834
835 to->code = decodes[code];
836 to->jt = filt->jt;
837 to->jf = filt->jf;
838
839 if (code == BPF_S_ALU_DIV_K) {
840 /*
841 * When loaded this rule user gave us X, which was
842 * translated into R = r(X). Now we calculate the
843 * RR = r(R) and report it back. If next time this
844 * value is loaded and RRR = r(RR) is calculated
845 * then the R == RRR will be true.
846 *
847 * One exception. X == 1 translates into R == 0 and
848 * we can't calculate RR out of it with r().
849 */
850
851 if (filt->k == 0)
852 to->k = 1;
853 else
854 to->k = reciprocal_value(filt->k);
855
856 BUG_ON(reciprocal_value(to->k) != filt->k);
857 } else
858 to->k = filt->k;
859 }
860
861 int sk_get_filter(struct sock *sk, struct sock_filter __user *ubuf, unsigned int len)
862 {
863 struct sk_filter *filter;
864 int i, ret;
865
866 lock_sock(sk);
867 filter = rcu_dereference_protected(sk->sk_filter,
868 sock_owned_by_user(sk));
869 ret = 0;
870 if (!filter)
871 goto out;
872 ret = filter->len;
873 if (!len)
874 goto out;
875 ret = -EINVAL;
876 if (len < filter->len)
877 goto out;
878
879 ret = -EFAULT;
880 for (i = 0; i < filter->len; i++) {
881 struct sock_filter fb;
882
883 sk_decode_filter(&filter->insns[i], &fb);
884 if (copy_to_user(&ubuf[i], &fb, sizeof(fb)))
885 goto out;
886 }
887
888 ret = filter->len;
889 out:
890 release_sock(sk);
891 return ret;
892 }
Linux 2.6 ibm-acpi/thinkpad-acpi driver git tree