Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/linville/wirel...
[linux-2.6.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/system.h>
37 #include <asm/uaccess.h>
38 #include <asm/unaligned.h>
39 #include <linux/filter.h>
40 #include <linux/reciprocal_div.h>
41 #include <linux/ratelimit.h>
42
43 /* No hurry in this branch */
44 static void *__load_pointer(const struct sk_buff *skb, int k, unsigned int size)
45 {
46         u8 *ptr = NULL;
47
48         if (k >= SKF_NET_OFF)
49                 ptr = skb_network_header(skb) + k - SKF_NET_OFF;
50         else if (k >= SKF_LL_OFF)
51                 ptr = skb_mac_header(skb) + k - SKF_LL_OFF;
52
53         if (ptr >= skb->head && ptr + size <= skb_tail_pointer(skb))
54                 return ptr;
55         return NULL;
56 }
57
58 static inline void *load_pointer(const struct sk_buff *skb, int k,
59                                  unsigned int size, void *buffer)
60 {
61         if (k >= 0)
62                 return skb_header_pointer(skb, k, size, buffer);
63         return __load_pointer(skb, k, size);
64 }
65
66 /**
67  *      sk_filter - run a packet through a socket filter
68  *      @sk: sock associated with &sk_buff
69  *      @skb: buffer to filter
70  *
71  * Run the filter code and then cut skb->data to correct size returned by
72  * sk_run_filter. If pkt_len is 0 we toss packet. If skb->len is smaller
73  * than pkt_len we keep whole skb->data. This is the socket level
74  * wrapper to sk_run_filter. It returns 0 if the packet should
75  * be accepted or -EPERM if the packet should be tossed.
76  *
77  */
78 int sk_filter(struct sock *sk, struct sk_buff *skb)
79 {
80         int err;
81         struct sk_filter *filter;
82
83         err = security_sock_rcv_skb(sk, skb);
84         if (err)
85                 return err;
86
87         rcu_read_lock();
88         filter = rcu_dereference(sk->sk_filter);
89         if (filter) {
90                 unsigned int pkt_len = SK_RUN_FILTER(filter, skb);
91
92                 err = pkt_len ? pskb_trim(skb, pkt_len) : -EPERM;
93         }
94         rcu_read_unlock();
95
96         return err;
97 }
98 EXPORT_SYMBOL(sk_filter);
99
100 /**
101  *      sk_run_filter - run a filter on a socket
102  *      @skb: buffer to run the filter on
103  *      @fentry: filter to apply
104  *
105  * Decode and apply filter instructions to the skb->data.
106  * Return length to keep, 0 for none. @skb is the data we are
107  * filtering, @filter is the array of filter instructions.
108  * Because all jumps are guaranteed to be before last instruction,
109  * and last instruction guaranteed to be a RET, we dont need to check
110  * flen. (We used to pass to this function the length of filter)
111  */
112 unsigned int sk_run_filter(const struct sk_buff *skb,
113                            const struct sock_filter *fentry)
114 {
115         void *ptr;
116         u32 A = 0;                      /* Accumulator */
117         u32 X = 0;                      /* Index Register */
118         u32 mem[BPF_MEMWORDS];          /* Scratch Memory Store */
119         u32 tmp;
120         int k;
121
122         /*
123          * Process array of filter instructions.
124          */
125         for (;; fentry++) {
126 #if defined(CONFIG_X86_32)
127 #define K (fentry->k)
128 #else
129                 const u32 K = fentry->k;
130 #endif
131
132                 switch (fentry->code) {
133                 case BPF_S_ALU_ADD_X:
134                         A += X;
135                         continue;
136                 case BPF_S_ALU_ADD_K:
137                         A += K;
138                         continue;
139                 case BPF_S_ALU_SUB_X:
140                         A -= X;
141                         continue;
142                 case BPF_S_ALU_SUB_K:
143                         A -= K;
144                         continue;
145                 case BPF_S_ALU_MUL_X:
146                         A *= X;
147                         continue;
148                 case BPF_S_ALU_MUL_K:
149                         A *= K;
150                         continue;
151                 case BPF_S_ALU_DIV_X:
152                         if (X == 0)
153                                 return 0;
154                         A /= X;
155                         continue;
156                 case BPF_S_ALU_DIV_K:
157                         A = reciprocal_divide(A, K);
158                         continue;
159                 case BPF_S_ALU_AND_X:
160                         A &= X;
161                         continue;
162                 case BPF_S_ALU_AND_K:
163                         A &= K;
164                         continue;
165                 case BPF_S_ALU_OR_X:
166                         A |= X;
167                         continue;
168                 case BPF_S_ALU_OR_K:
169                         A |= K;
170                         continue;
171                 case BPF_S_ALU_LSH_X:
172                         A <<= X;
173                         continue;
174                 case BPF_S_ALU_LSH_K:
175                         A <<= K;
176                         continue;
177                 case BPF_S_ALU_RSH_X:
178                         A >>= X;
179                         continue;
180                 case BPF_S_ALU_RSH_K:
181                         A >>= K;
182                         continue;
183                 case BPF_S_ALU_NEG:
184                         A = -A;
185                         continue;
186                 case BPF_S_JMP_JA:
187                         fentry += K;
188                         continue;
189                 case BPF_S_JMP_JGT_K:
190                         fentry += (A > K) ? fentry->jt : fentry->jf;
191                         continue;
192                 case BPF_S_JMP_JGE_K:
193                         fentry += (A >= K) ? fentry->jt : fentry->jf;
194                         continue;
195                 case BPF_S_JMP_JEQ_K:
196                         fentry += (A == K) ? fentry->jt : fentry->jf;
197                         continue;
198                 case BPF_S_JMP_JSET_K:
199                         fentry += (A & K) ? fentry->jt : fentry->jf;
200                         continue;
201                 case BPF_S_JMP_JGT_X:
202                         fentry += (A > X) ? fentry->jt : fentry->jf;
203                         continue;
204                 case BPF_S_JMP_JGE_X:
205                         fentry += (A >= X) ? fentry->jt : fentry->jf;
206                         continue;
207                 case BPF_S_JMP_JEQ_X:
208                         fentry += (A == X) ? fentry->jt : fentry->jf;
209                         continue;
210                 case BPF_S_JMP_JSET_X:
211                         fentry += (A & X) ? fentry->jt : fentry->jf;
212                         continue;
213                 case BPF_S_LD_W_ABS:
214                         k = K;
215 load_w:
216                         ptr = load_pointer(skb, k, 4, &tmp);
217                         if (ptr != NULL) {
218                                 A = get_unaligned_be32(ptr);
219                                 continue;
220                         }
221                         return 0;
222                 case BPF_S_LD_H_ABS:
223                         k = K;
224 load_h:
225                         ptr = load_pointer(skb, k, 2, &tmp);
226                         if (ptr != NULL) {
227                                 A = get_unaligned_be16(ptr);
228                                 continue;
229                         }
230                         return 0;
231                 case BPF_S_LD_B_ABS:
232                         k = K;
233 load_b:
234                         ptr = load_pointer(skb, k, 1, &tmp);
235                         if (ptr != NULL) {
236                                 A = *(u8 *)ptr;
237                                 continue;
238                         }
239                         return 0;
240                 case BPF_S_LD_W_LEN:
241                         A = skb->len;
242                         continue;
243                 case BPF_S_LDX_W_LEN:
244                         X = skb->len;
245                         continue;
246                 case BPF_S_LD_W_IND:
247                         k = X + K;
248                         goto load_w;
249                 case BPF_S_LD_H_IND:
250                         k = X + K;
251                         goto load_h;
252                 case BPF_S_LD_B_IND:
253                         k = X + K;
254                         goto load_b;
255                 case BPF_S_LDX_B_MSH:
256                         ptr = load_pointer(skb, K, 1, &tmp);
257                         if (ptr != NULL) {
258                                 X = (*(u8 *)ptr & 0xf) << 2;
259                                 continue;
260                         }
261                         return 0;
262                 case BPF_S_LD_IMM:
263                         A = K;
264                         continue;
265                 case BPF_S_LDX_IMM:
266                         X = K;
267                         continue;
268                 case BPF_S_LD_MEM:
269                         A = mem[K];
270                         continue;
271                 case BPF_S_LDX_MEM:
272                         X = mem[K];
273                         continue;
274                 case BPF_S_MISC_TAX:
275                         X = A;
276                         continue;
277                 case BPF_S_MISC_TXA:
278                         A = X;
279                         continue;
280                 case BPF_S_RET_K:
281                         return K;
282                 case BPF_S_RET_A:
283                         return A;
284                 case BPF_S_ST:
285                         mem[K] = A;
286                         continue;
287                 case BPF_S_STX:
288                         mem[K] = X;
289                         continue;
290                 case BPF_S_ANC_PROTOCOL:
291                         A = ntohs(skb->protocol);
292                         continue;
293                 case BPF_S_ANC_PKTTYPE:
294                         A = skb->pkt_type;
295                         continue;
296                 case BPF_S_ANC_IFINDEX:
297                         if (!skb->dev)
298                                 return 0;
299                         A = skb->dev->ifindex;
300                         continue;
301                 case BPF_S_ANC_MARK:
302                         A = skb->mark;
303                         continue;
304                 case BPF_S_ANC_QUEUE:
305                         A = skb->queue_mapping;
306                         continue;
307                 case BPF_S_ANC_HATYPE:
308                         if (!skb->dev)
309                                 return 0;
310                         A = skb->dev->type;
311                         continue;
312                 case BPF_S_ANC_RXHASH:
313                         A = skb->rxhash;
314                         continue;
315                 case BPF_S_ANC_CPU:
316                         A = raw_smp_processor_id();
317                         continue;
318                 case BPF_S_ANC_NLATTR: {
319                         struct nlattr *nla;
320
321                         if (skb_is_nonlinear(skb))
322                                 return 0;
323                         if (A > skb->len - sizeof(struct nlattr))
324                                 return 0;
325
326                         nla = nla_find((struct nlattr *)&skb->data[A],
327                                        skb->len - A, X);
328                         if (nla)
329                                 A = (void *)nla - (void *)skb->data;
330                         else
331                                 A = 0;
332                         continue;
333                 }
334                 case BPF_S_ANC_NLATTR_NEST: {
335                         struct nlattr *nla;
336
337                         if (skb_is_nonlinear(skb))
338                                 return 0;
339                         if (A > skb->len - sizeof(struct nlattr))
340                                 return 0;
341
342                         nla = (struct nlattr *)&skb->data[A];
343                         if (nla->nla_len > A - skb->len)
344                                 return 0;
345
346                         nla = nla_find_nested(nla, X);
347                         if (nla)
348                                 A = (void *)nla - (void *)skb->data;
349                         else
350                                 A = 0;
351                         continue;
352                 }
353                 default:
354                         WARN_RATELIMIT(1, "Unknown code:%u jt:%u tf:%u k:%u\n",
355                                        fentry->code, fentry->jt,
356                                        fentry->jf, fentry->k);
357                         return 0;
358                 }
359         }
360
361         return 0;
362 }
363 EXPORT_SYMBOL(sk_run_filter);
364
365 /*
366  * Security :
367  * A BPF program is able to use 16 cells of memory to store intermediate
368  * values (check u32 mem[BPF_MEMWORDS] in sk_run_filter())
369  * As we dont want to clear mem[] array for each packet going through
370  * sk_run_filter(), we check that filter loaded by user never try to read
371  * a cell if not previously written, and we check all branches to be sure
372  * a malicious user doesn't try to abuse us.
373  */
374 static int check_load_and_stores(struct sock_filter *filter, int flen)
375 {
376         u16 *masks, memvalid = 0; /* one bit per cell, 16 cells */
377         int pc, ret = 0;
378
379         BUILD_BUG_ON(BPF_MEMWORDS > 16);
380         masks = kmalloc(flen * sizeof(*masks), GFP_KERNEL);
381         if (!masks)
382                 return -ENOMEM;
383         memset(masks, 0xff, flen * sizeof(*masks));
384
385         for (pc = 0; pc < flen; pc++) {
386                 memvalid &= masks[pc];
387
388                 switch (filter[pc].code) {
389                 case BPF_S_ST:
390                 case BPF_S_STX:
391                         memvalid |= (1 << filter[pc].k);
392                         break;
393                 case BPF_S_LD_MEM:
394                 case BPF_S_LDX_MEM:
395                         if (!(memvalid & (1 << filter[pc].k))) {
396                                 ret = -EINVAL;
397                                 goto error;
398                         }
399                         break;
400                 case BPF_S_JMP_JA:
401                         /* a jump must set masks on target */
402                         masks[pc + 1 + filter[pc].k] &= memvalid;
403                         memvalid = ~0;
404                         break;
405                 case BPF_S_JMP_JEQ_K:
406                 case BPF_S_JMP_JEQ_X:
407                 case BPF_S_JMP_JGE_K:
408                 case BPF_S_JMP_JGE_X:
409                 case BPF_S_JMP_JGT_K:
410                 case BPF_S_JMP_JGT_X:
411                 case BPF_S_JMP_JSET_X:
412                 case BPF_S_JMP_JSET_K:
413                         /* a jump must set masks on targets */
414                         masks[pc + 1 + filter[pc].jt] &= memvalid;
415                         masks[pc + 1 + filter[pc].jf] &= memvalid;
416                         memvalid = ~0;
417                         break;
418                 }
419         }
420 error:
421         kfree(masks);
422         return ret;
423 }
424
425 /**
426  *      sk_chk_filter - verify socket filter code
427  *      @filter: filter to verify
428  *      @flen: length of filter
429  *
430  * Check the user's filter code. If we let some ugly
431  * filter code slip through kaboom! The filter must contain
432  * no references or jumps that are out of range, no illegal
433  * instructions, and must end with a RET instruction.
434  *
435  * All jumps are forward as they are not signed.
436  *
437  * Returns 0 if the rule set is legal or -EINVAL if not.
438  */
439 int sk_chk_filter(struct sock_filter *filter, unsigned int flen)
440 {
441         /*
442          * Valid instructions are initialized to non-0.
443          * Invalid instructions are initialized to 0.
444          */
445         static const u8 codes[] = {
446                 [BPF_ALU|BPF_ADD|BPF_K]  = BPF_S_ALU_ADD_K,
447                 [BPF_ALU|BPF_ADD|BPF_X]  = BPF_S_ALU_ADD_X,
448                 [BPF_ALU|BPF_SUB|BPF_K]  = BPF_S_ALU_SUB_K,
449                 [BPF_ALU|BPF_SUB|BPF_X]  = BPF_S_ALU_SUB_X,
450                 [BPF_ALU|BPF_MUL|BPF_K]  = BPF_S_ALU_MUL_K,
451                 [BPF_ALU|BPF_MUL|BPF_X]  = BPF_S_ALU_MUL_X,
452                 [BPF_ALU|BPF_DIV|BPF_X]  = BPF_S_ALU_DIV_X,
453                 [BPF_ALU|BPF_AND|BPF_K]  = BPF_S_ALU_AND_K,
454                 [BPF_ALU|BPF_AND|BPF_X]  = BPF_S_ALU_AND_X,
455                 [BPF_ALU|BPF_OR|BPF_K]   = BPF_S_ALU_OR_K,
456                 [BPF_ALU|BPF_OR|BPF_X]   = BPF_S_ALU_OR_X,
457                 [BPF_ALU|BPF_LSH|BPF_K]  = BPF_S_ALU_LSH_K,
458                 [BPF_ALU|BPF_LSH|BPF_X]  = BPF_S_ALU_LSH_X,
459                 [BPF_ALU|BPF_RSH|BPF_K]  = BPF_S_ALU_RSH_K,
460                 [BPF_ALU|BPF_RSH|BPF_X]  = BPF_S_ALU_RSH_X,
461                 [BPF_ALU|BPF_NEG]        = BPF_S_ALU_NEG,
462                 [BPF_LD|BPF_W|BPF_ABS]   = BPF_S_LD_W_ABS,
463                 [BPF_LD|BPF_H|BPF_ABS]   = BPF_S_LD_H_ABS,
464                 [BPF_LD|BPF_B|BPF_ABS]   = BPF_S_LD_B_ABS,
465                 [BPF_LD|BPF_W|BPF_LEN]   = BPF_S_LD_W_LEN,
466                 [BPF_LD|BPF_W|BPF_IND]   = BPF_S_LD_W_IND,
467                 [BPF_LD|BPF_H|BPF_IND]   = BPF_S_LD_H_IND,
468                 [BPF_LD|BPF_B|BPF_IND]   = BPF_S_LD_B_IND,
469                 [BPF_LD|BPF_IMM]         = BPF_S_LD_IMM,
470                 [BPF_LDX|BPF_W|BPF_LEN]  = BPF_S_LDX_W_LEN,
471                 [BPF_LDX|BPF_B|BPF_MSH]  = BPF_S_LDX_B_MSH,
472                 [BPF_LDX|BPF_IMM]        = BPF_S_LDX_IMM,
473                 [BPF_MISC|BPF_TAX]       = BPF_S_MISC_TAX,
474                 [BPF_MISC|BPF_TXA]       = BPF_S_MISC_TXA,
475                 [BPF_RET|BPF_K]          = BPF_S_RET_K,
476                 [BPF_RET|BPF_A]          = BPF_S_RET_A,
477                 [BPF_ALU|BPF_DIV|BPF_K]  = BPF_S_ALU_DIV_K,
478                 [BPF_LD|BPF_MEM]         = BPF_S_LD_MEM,
479                 [BPF_LDX|BPF_MEM]        = BPF_S_LDX_MEM,
480                 [BPF_ST]                 = BPF_S_ST,
481                 [BPF_STX]                = BPF_S_STX,
482                 [BPF_JMP|BPF_JA]         = BPF_S_JMP_JA,
483                 [BPF_JMP|BPF_JEQ|BPF_K]  = BPF_S_JMP_JEQ_K,
484                 [BPF_JMP|BPF_JEQ|BPF_X]  = BPF_S_JMP_JEQ_X,
485                 [BPF_JMP|BPF_JGE|BPF_K]  = BPF_S_JMP_JGE_K,
486                 [BPF_JMP|BPF_JGE|BPF_X]  = BPF_S_JMP_JGE_X,
487                 [BPF_JMP|BPF_JGT|BPF_K]  = BPF_S_JMP_JGT_K,
488                 [BPF_JMP|BPF_JGT|BPF_X]  = BPF_S_JMP_JGT_X,
489                 [BPF_JMP|BPF_JSET|BPF_K] = BPF_S_JMP_JSET_K,
490                 [BPF_JMP|BPF_JSET|BPF_X] = BPF_S_JMP_JSET_X,
491         };
492         int pc;
493
494         if (flen == 0 || flen > BPF_MAXINSNS)
495                 return -EINVAL;
496
497         /* check the filter code now */
498         for (pc = 0; pc < flen; pc++) {
499                 struct sock_filter *ftest = &filter[pc];
500                 u16 code = ftest->code;
501
502                 if (code >= ARRAY_SIZE(codes))
503                         return -EINVAL;
504                 code = codes[code];
505                 if (!code)
506                         return -EINVAL;
507                 /* Some instructions need special checks */
508                 switch (code) {
509                 case BPF_S_ALU_DIV_K:
510                         /* check for division by zero */
511                         if (ftest->k == 0)
512                                 return -EINVAL;
513                         ftest->k = reciprocal_value(ftest->k);
514                         break;
515                 case BPF_S_LD_MEM:
516                 case BPF_S_LDX_MEM:
517                 case BPF_S_ST:
518                 case BPF_S_STX:
519                         /* check for invalid memory addresses */
520                         if (ftest->k >= BPF_MEMWORDS)
521                                 return -EINVAL;
522                         break;
523                 case BPF_S_JMP_JA:
524                         /*
525                          * Note, the large ftest->k might cause loops.
526                          * Compare this with conditional jumps below,
527                          * where offsets are limited. --ANK (981016)
528                          */
529                         if (ftest->k >= (unsigned)(flen-pc-1))
530                                 return -EINVAL;
531                         break;
532                 case BPF_S_JMP_JEQ_K:
533                 case BPF_S_JMP_JEQ_X:
534                 case BPF_S_JMP_JGE_K:
535                 case BPF_S_JMP_JGE_X:
536                 case BPF_S_JMP_JGT_K:
537                 case BPF_S_JMP_JGT_X:
538                 case BPF_S_JMP_JSET_X:
539                 case BPF_S_JMP_JSET_K:
540                         /* for conditionals both must be safe */
541                         if (pc + ftest->jt + 1 >= flen ||
542                             pc + ftest->jf + 1 >= flen)
543                                 return -EINVAL;
544                         break;
545                 case BPF_S_LD_W_ABS:
546                 case BPF_S_LD_H_ABS:
547                 case BPF_S_LD_B_ABS:
548 #define ANCILLARY(CODE) case SKF_AD_OFF + SKF_AD_##CODE:        \
549                                 code = BPF_S_ANC_##CODE;        \
550                                 break
551                         switch (ftest->k) {
552                         ANCILLARY(PROTOCOL);
553                         ANCILLARY(PKTTYPE);
554                         ANCILLARY(IFINDEX);
555                         ANCILLARY(NLATTR);
556                         ANCILLARY(NLATTR_NEST);
557                         ANCILLARY(MARK);
558                         ANCILLARY(QUEUE);
559                         ANCILLARY(HATYPE);
560                         ANCILLARY(RXHASH);
561                         ANCILLARY(CPU);
562                         }
563                 }
564                 ftest->code = code;
565         }
566
567         /* last instruction must be a RET code */
568         switch (filter[flen - 1].code) {
569         case BPF_S_RET_K:
570         case BPF_S_RET_A:
571                 return check_load_and_stores(filter, flen);
572         }
573         return -EINVAL;
574 }
575 EXPORT_SYMBOL(sk_chk_filter);
576
577 /**
578  *      sk_filter_release_rcu - Release a socket filter by rcu_head
579  *      @rcu: rcu_head that contains the sk_filter to free
580  */
581 void sk_filter_release_rcu(struct rcu_head *rcu)
582 {
583         struct sk_filter *fp = container_of(rcu, struct sk_filter, rcu);
584
585         bpf_jit_free(fp);
586         kfree(fp);
587 }
588 EXPORT_SYMBOL(sk_filter_release_rcu);
589
590 /**
591  *      sk_attach_filter - attach a socket filter
592  *      @fprog: the filter program
593  *      @sk: the socket to use
594  *
595  * Attach the user's filter code. We first run some sanity checks on
596  * it to make sure it does not explode on us later. If an error
597  * occurs or there is insufficient memory for the filter a negative
598  * errno code is returned. On success the return is zero.
599  */
600 int sk_attach_filter(struct sock_fprog *fprog, struct sock *sk)
601 {
602         struct sk_filter *fp, *old_fp;
603         unsigned int fsize = sizeof(struct sock_filter) * fprog->len;
604         int err;
605
606         /* Make sure new filter is there and in the right amounts. */
607         if (fprog->filter == NULL)
608                 return -EINVAL;
609
610         fp = sock_kmalloc(sk, fsize+sizeof(*fp), GFP_KERNEL);
611         if (!fp)
612                 return -ENOMEM;
613         if (copy_from_user(fp->insns, fprog->filter, fsize)) {
614                 sock_kfree_s(sk, fp, fsize+sizeof(*fp));
615                 return -EFAULT;
616         }
617
618         atomic_set(&fp->refcnt, 1);
619         fp->len = fprog->len;
620         fp->bpf_func = sk_run_filter;
621
622         err = sk_chk_filter(fp->insns, fp->len);
623         if (err) {
624                 sk_filter_uncharge(sk, fp);
625                 return err;
626         }
627
628         bpf_jit_compile(fp);
629
630         old_fp = rcu_dereference_protected(sk->sk_filter,
631                                            sock_owned_by_user(sk));
632         rcu_assign_pointer(sk->sk_filter, fp);
633
634         if (old_fp)
635                 sk_filter_uncharge(sk, old_fp);
636         return 0;
637 }
638 EXPORT_SYMBOL_GPL(sk_attach_filter);
639
640 int sk_detach_filter(struct sock *sk)
641 {
642         int ret = -ENOENT;
643         struct sk_filter *filter;
644
645         filter = rcu_dereference_protected(sk->sk_filter,
646                                            sock_owned_by_user(sk));
647         if (filter) {
648                 RCU_INIT_POINTER(sk->sk_filter, NULL);
649                 sk_filter_uncharge(sk, filter);
650                 ret = 0;
651         }
652         return ret;
653 }
654 EXPORT_SYMBOL_GPL(sk_detach_filter);