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1 | /* | |
2 | * Linux Socket Filter - Kernel level socket filtering | |
3 | * | |
4 | * Based on the design of the Berkeley Packet Filter. The new | |
5 | * internal format has been designed by PLUMgrid: | |
6 | * | |
7 | * Copyright (c) 2011 - 2014 PLUMgrid, http://plumgrid.com | |
8 | * | |
9 | * Authors: | |
10 | * | |
11 | * Jay Schulist <jschlst@samba.org> | |
12 | * Alexei Starovoitov <ast@plumgrid.com> | |
13 | * Daniel Borkmann <dborkman@redhat.com> | |
14 | * | |
15 | * This program is free software; you can redistribute it and/or | |
16 | * modify it under the terms of the GNU General Public License | |
17 | * as published by the Free Software Foundation; either version | |
18 | * 2 of the License, or (at your option) any later version. | |
19 | * | |
20 | * Andi Kleen - Fix a few bad bugs and races. | |
21 | * Kris Katterjohn - Added many additional checks in bpf_check_classic() | |
22 | */ | |
23 | ||
24 | #include <linux/module.h> | |
25 | #include <linux/types.h> | |
26 | #include <linux/mm.h> | |
27 | #include <linux/fcntl.h> | |
28 | #include <linux/socket.h> | |
29 | #include <linux/in.h> | |
30 | #include <linux/inet.h> | |
31 | #include <linux/netdevice.h> | |
32 | #include <linux/if_packet.h> | |
33 | #include <linux/gfp.h> | |
34 | #include <net/ip.h> | |
35 | #include <net/protocol.h> | |
36 | #include <net/netlink.h> | |
37 | #include <linux/skbuff.h> | |
38 | #include <net/sock.h> | |
39 | #include <linux/errno.h> | |
40 | #include <linux/timer.h> | |
41 | #include <asm/uaccess.h> | |
42 | #include <asm/unaligned.h> | |
43 | #include <linux/filter.h> | |
44 | #include <linux/ratelimit.h> | |
45 | #include <linux/seccomp.h> | |
46 | #include <linux/if_vlan.h> | |
47 | #include <linux/bpf.h> | |
48 | ||
49 | /** | |
50 | * sk_filter - run a packet through a socket filter | |
51 | * @sk: sock associated with &sk_buff | |
52 | * @skb: buffer to filter | |
53 | * | |
54 | * Run the filter code and then cut skb->data to correct size returned by | |
55 | * SK_RUN_FILTER. If pkt_len is 0 we toss packet. If skb->len is smaller | |
56 | * than pkt_len we keep whole skb->data. This is the socket level | |
57 | * wrapper to SK_RUN_FILTER. It returns 0 if the packet should | |
58 | * be accepted or -EPERM if the packet should be tossed. | |
59 | * | |
60 | */ | |
61 | int sk_filter(struct sock *sk, struct sk_buff *skb) | |
62 | { | |
63 | int err; | |
64 | struct sk_filter *filter; | |
65 | ||
66 | /* | |
67 | * If the skb was allocated from pfmemalloc reserves, only | |
68 | * allow SOCK_MEMALLOC sockets to use it as this socket is | |
69 | * helping free memory | |
70 | */ | |
71 | if (skb_pfmemalloc(skb) && !sock_flag(sk, SOCK_MEMALLOC)) | |
72 | return -ENOMEM; | |
73 | ||
74 | err = security_sock_rcv_skb(sk, skb); | |
75 | if (err) | |
76 | return err; | |
77 | ||
78 | rcu_read_lock(); | |
79 | filter = rcu_dereference(sk->sk_filter); | |
80 | if (filter) { | |
81 | unsigned int pkt_len = SK_RUN_FILTER(filter, skb); | |
82 | ||
83 | err = pkt_len ? pskb_trim(skb, pkt_len) : -EPERM; | |
84 | } | |
85 | rcu_read_unlock(); | |
86 | ||
87 | return err; | |
88 | } | |
89 | EXPORT_SYMBOL(sk_filter); | |
90 | ||
91 | static u64 __skb_get_pay_offset(u64 ctx, u64 a, u64 x, u64 r4, u64 r5) | |
92 | { | |
93 | return skb_get_poff((struct sk_buff *)(unsigned long) ctx); | |
94 | } | |
95 | ||
96 | static u64 __skb_get_nlattr(u64 ctx, u64 a, u64 x, u64 r4, u64 r5) | |
97 | { | |
98 | struct sk_buff *skb = (struct sk_buff *)(unsigned long) ctx; | |
99 | struct nlattr *nla; | |
100 | ||
101 | if (skb_is_nonlinear(skb)) | |
102 | return 0; | |
103 | ||
104 | if (skb->len < sizeof(struct nlattr)) | |
105 | return 0; | |
106 | ||
107 | if (a > skb->len - sizeof(struct nlattr)) | |
108 | return 0; | |
109 | ||
110 | nla = nla_find((struct nlattr *) &skb->data[a], skb->len - a, x); | |
111 | if (nla) | |
112 | return (void *) nla - (void *) skb->data; | |
113 | ||
114 | return 0; | |
115 | } | |
116 | ||
117 | static u64 __skb_get_nlattr_nest(u64 ctx, u64 a, u64 x, u64 r4, u64 r5) | |
118 | { | |
119 | struct sk_buff *skb = (struct sk_buff *)(unsigned long) ctx; | |
120 | struct nlattr *nla; | |
121 | ||
122 | if (skb_is_nonlinear(skb)) | |
123 | return 0; | |
124 | ||
125 | if (skb->len < sizeof(struct nlattr)) | |
126 | return 0; | |
127 | ||
128 | if (a > skb->len - sizeof(struct nlattr)) | |
129 | return 0; | |
130 | ||
131 | nla = (struct nlattr *) &skb->data[a]; | |
132 | if (nla->nla_len > skb->len - a) | |
133 | return 0; | |
134 | ||
135 | nla = nla_find_nested(nla, x); | |
136 | if (nla) | |
137 | return (void *) nla - (void *) skb->data; | |
138 | ||
139 | return 0; | |
140 | } | |
141 | ||
142 | static u64 __get_raw_cpu_id(u64 ctx, u64 a, u64 x, u64 r4, u64 r5) | |
143 | { | |
144 | return raw_smp_processor_id(); | |
145 | } | |
146 | ||
147 | /* note that this only generates 32-bit random numbers */ | |
148 | static u64 __get_random_u32(u64 ctx, u64 a, u64 x, u64 r4, u64 r5) | |
149 | { | |
150 | return prandom_u32(); | |
151 | } | |
152 | ||
153 | static bool convert_bpf_extensions(struct sock_filter *fp, | |
154 | struct bpf_insn **insnp) | |
155 | { | |
156 | struct bpf_insn *insn = *insnp; | |
157 | ||
158 | switch (fp->k) { | |
159 | case SKF_AD_OFF + SKF_AD_PROTOCOL: | |
160 | BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, protocol) != 2); | |
161 | ||
162 | /* A = *(u16 *) (CTX + offsetof(protocol)) */ | |
163 | *insn++ = BPF_LDX_MEM(BPF_H, BPF_REG_A, BPF_REG_CTX, | |
164 | offsetof(struct sk_buff, protocol)); | |
165 | /* A = ntohs(A) [emitting a nop or swap16] */ | |
166 | *insn = BPF_ENDIAN(BPF_FROM_BE, BPF_REG_A, 16); | |
167 | break; | |
168 | ||
169 | case SKF_AD_OFF + SKF_AD_PKTTYPE: | |
170 | *insn++ = BPF_LDX_MEM(BPF_B, BPF_REG_A, BPF_REG_CTX, | |
171 | PKT_TYPE_OFFSET()); | |
172 | *insn = BPF_ALU32_IMM(BPF_AND, BPF_REG_A, PKT_TYPE_MAX); | |
173 | #ifdef __BIG_ENDIAN_BITFIELD | |
174 | insn++; | |
175 | *insn = BPF_ALU32_IMM(BPF_RSH, BPF_REG_A, 5); | |
176 | #endif | |
177 | break; | |
178 | ||
179 | case SKF_AD_OFF + SKF_AD_IFINDEX: | |
180 | case SKF_AD_OFF + SKF_AD_HATYPE: | |
181 | BUILD_BUG_ON(FIELD_SIZEOF(struct net_device, ifindex) != 4); | |
182 | BUILD_BUG_ON(FIELD_SIZEOF(struct net_device, type) != 2); | |
183 | BUILD_BUG_ON(bytes_to_bpf_size(FIELD_SIZEOF(struct sk_buff, dev)) < 0); | |
184 | ||
185 | *insn++ = BPF_LDX_MEM(bytes_to_bpf_size(FIELD_SIZEOF(struct sk_buff, dev)), | |
186 | BPF_REG_TMP, BPF_REG_CTX, | |
187 | offsetof(struct sk_buff, dev)); | |
188 | /* if (tmp != 0) goto pc + 1 */ | |
189 | *insn++ = BPF_JMP_IMM(BPF_JNE, BPF_REG_TMP, 0, 1); | |
190 | *insn++ = BPF_EXIT_INSN(); | |
191 | if (fp->k == SKF_AD_OFF + SKF_AD_IFINDEX) | |
192 | *insn = BPF_LDX_MEM(BPF_W, BPF_REG_A, BPF_REG_TMP, | |
193 | offsetof(struct net_device, ifindex)); | |
194 | else | |
195 | *insn = BPF_LDX_MEM(BPF_H, BPF_REG_A, BPF_REG_TMP, | |
196 | offsetof(struct net_device, type)); | |
197 | break; | |
198 | ||
199 | case SKF_AD_OFF + SKF_AD_MARK: | |
200 | BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, mark) != 4); | |
201 | ||
202 | *insn = BPF_LDX_MEM(BPF_W, BPF_REG_A, BPF_REG_CTX, | |
203 | offsetof(struct sk_buff, mark)); | |
204 | break; | |
205 | ||
206 | case SKF_AD_OFF + SKF_AD_RXHASH: | |
207 | BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, hash) != 4); | |
208 | ||
209 | *insn = BPF_LDX_MEM(BPF_W, BPF_REG_A, BPF_REG_CTX, | |
210 | offsetof(struct sk_buff, hash)); | |
211 | break; | |
212 | ||
213 | case SKF_AD_OFF + SKF_AD_QUEUE: | |
214 | BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, queue_mapping) != 2); | |
215 | ||
216 | *insn = BPF_LDX_MEM(BPF_H, BPF_REG_A, BPF_REG_CTX, | |
217 | offsetof(struct sk_buff, queue_mapping)); | |
218 | break; | |
219 | ||
220 | case SKF_AD_OFF + SKF_AD_VLAN_TAG: | |
221 | case SKF_AD_OFF + SKF_AD_VLAN_TAG_PRESENT: | |
222 | BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, vlan_tci) != 2); | |
223 | BUILD_BUG_ON(VLAN_TAG_PRESENT != 0x1000); | |
224 | ||
225 | /* A = *(u16 *) (CTX + offsetof(vlan_tci)) */ | |
226 | *insn++ = BPF_LDX_MEM(BPF_H, BPF_REG_A, BPF_REG_CTX, | |
227 | offsetof(struct sk_buff, vlan_tci)); | |
228 | if (fp->k == SKF_AD_OFF + SKF_AD_VLAN_TAG) { | |
229 | *insn = BPF_ALU32_IMM(BPF_AND, BPF_REG_A, | |
230 | ~VLAN_TAG_PRESENT); | |
231 | } else { | |
232 | /* A >>= 12 */ | |
233 | *insn++ = BPF_ALU32_IMM(BPF_RSH, BPF_REG_A, 12); | |
234 | /* A &= 1 */ | |
235 | *insn = BPF_ALU32_IMM(BPF_AND, BPF_REG_A, 1); | |
236 | } | |
237 | break; | |
238 | ||
239 | case SKF_AD_OFF + SKF_AD_PAY_OFFSET: | |
240 | case SKF_AD_OFF + SKF_AD_NLATTR: | |
241 | case SKF_AD_OFF + SKF_AD_NLATTR_NEST: | |
242 | case SKF_AD_OFF + SKF_AD_CPU: | |
243 | case SKF_AD_OFF + SKF_AD_RANDOM: | |
244 | /* arg1 = CTX */ | |
245 | *insn++ = BPF_MOV64_REG(BPF_REG_ARG1, BPF_REG_CTX); | |
246 | /* arg2 = A */ | |
247 | *insn++ = BPF_MOV64_REG(BPF_REG_ARG2, BPF_REG_A); | |
248 | /* arg3 = X */ | |
249 | *insn++ = BPF_MOV64_REG(BPF_REG_ARG3, BPF_REG_X); | |
250 | /* Emit call(arg1=CTX, arg2=A, arg3=X) */ | |
251 | switch (fp->k) { | |
252 | case SKF_AD_OFF + SKF_AD_PAY_OFFSET: | |
253 | *insn = BPF_EMIT_CALL(__skb_get_pay_offset); | |
254 | break; | |
255 | case SKF_AD_OFF + SKF_AD_NLATTR: | |
256 | *insn = BPF_EMIT_CALL(__skb_get_nlattr); | |
257 | break; | |
258 | case SKF_AD_OFF + SKF_AD_NLATTR_NEST: | |
259 | *insn = BPF_EMIT_CALL(__skb_get_nlattr_nest); | |
260 | break; | |
261 | case SKF_AD_OFF + SKF_AD_CPU: | |
262 | *insn = BPF_EMIT_CALL(__get_raw_cpu_id); | |
263 | break; | |
264 | case SKF_AD_OFF + SKF_AD_RANDOM: | |
265 | *insn = BPF_EMIT_CALL(__get_random_u32); | |
266 | break; | |
267 | } | |
268 | break; | |
269 | ||
270 | case SKF_AD_OFF + SKF_AD_ALU_XOR_X: | |
271 | /* A ^= X */ | |
272 | *insn = BPF_ALU32_REG(BPF_XOR, BPF_REG_A, BPF_REG_X); | |
273 | break; | |
274 | ||
275 | default: | |
276 | /* This is just a dummy call to avoid letting the compiler | |
277 | * evict __bpf_call_base() as an optimization. Placed here | |
278 | * where no-one bothers. | |
279 | */ | |
280 | BUG_ON(__bpf_call_base(0, 0, 0, 0, 0) != 0); | |
281 | return false; | |
282 | } | |
283 | ||
284 | *insnp = insn; | |
285 | return true; | |
286 | } | |
287 | ||
288 | /** | |
289 | * bpf_convert_filter - convert filter program | |
290 | * @prog: the user passed filter program | |
291 | * @len: the length of the user passed filter program | |
292 | * @new_prog: buffer where converted program will be stored | |
293 | * @new_len: pointer to store length of converted program | |
294 | * | |
295 | * Remap 'sock_filter' style BPF instruction set to 'sock_filter_ext' style. | |
296 | * Conversion workflow: | |
297 | * | |
298 | * 1) First pass for calculating the new program length: | |
299 | * bpf_convert_filter(old_prog, old_len, NULL, &new_len) | |
300 | * | |
301 | * 2) 2nd pass to remap in two passes: 1st pass finds new | |
302 | * jump offsets, 2nd pass remapping: | |
303 | * new_prog = kmalloc(sizeof(struct bpf_insn) * new_len); | |
304 | * bpf_convert_filter(old_prog, old_len, new_prog, &new_len); | |
305 | * | |
306 | * User BPF's register A is mapped to our BPF register 6, user BPF | |
307 | * register X is mapped to BPF register 7; frame pointer is always | |
308 | * register 10; Context 'void *ctx' is stored in register 1, that is, | |
309 | * for socket filters: ctx == 'struct sk_buff *', for seccomp: | |
310 | * ctx == 'struct seccomp_data *'. | |
311 | */ | |
312 | int bpf_convert_filter(struct sock_filter *prog, int len, | |
313 | struct bpf_insn *new_prog, int *new_len) | |
314 | { | |
315 | int new_flen = 0, pass = 0, target, i; | |
316 | struct bpf_insn *new_insn; | |
317 | struct sock_filter *fp; | |
318 | int *addrs = NULL; | |
319 | u8 bpf_src; | |
320 | ||
321 | BUILD_BUG_ON(BPF_MEMWORDS * sizeof(u32) > MAX_BPF_STACK); | |
322 | BUILD_BUG_ON(BPF_REG_FP + 1 != MAX_BPF_REG); | |
323 | ||
324 | if (len <= 0 || len > BPF_MAXINSNS) | |
325 | return -EINVAL; | |
326 | ||
327 | if (new_prog) { | |
328 | addrs = kcalloc(len, sizeof(*addrs), GFP_KERNEL); | |
329 | if (!addrs) | |
330 | return -ENOMEM; | |
331 | } | |
332 | ||
333 | do_pass: | |
334 | new_insn = new_prog; | |
335 | fp = prog; | |
336 | ||
337 | if (new_insn) | |
338 | *new_insn = BPF_MOV64_REG(BPF_REG_CTX, BPF_REG_ARG1); | |
339 | new_insn++; | |
340 | ||
341 | for (i = 0; i < len; fp++, i++) { | |
342 | struct bpf_insn tmp_insns[6] = { }; | |
343 | struct bpf_insn *insn = tmp_insns; | |
344 | ||
345 | if (addrs) | |
346 | addrs[i] = new_insn - new_prog; | |
347 | ||
348 | switch (fp->code) { | |
349 | /* All arithmetic insns and skb loads map as-is. */ | |
350 | case BPF_ALU | BPF_ADD | BPF_X: | |
351 | case BPF_ALU | BPF_ADD | BPF_K: | |
352 | case BPF_ALU | BPF_SUB | BPF_X: | |
353 | case BPF_ALU | BPF_SUB | BPF_K: | |
354 | case BPF_ALU | BPF_AND | BPF_X: | |
355 | case BPF_ALU | BPF_AND | BPF_K: | |
356 | case BPF_ALU | BPF_OR | BPF_X: | |
357 | case BPF_ALU | BPF_OR | BPF_K: | |
358 | case BPF_ALU | BPF_LSH | BPF_X: | |
359 | case BPF_ALU | BPF_LSH | BPF_K: | |
360 | case BPF_ALU | BPF_RSH | BPF_X: | |
361 | case BPF_ALU | BPF_RSH | BPF_K: | |
362 | case BPF_ALU | BPF_XOR | BPF_X: | |
363 | case BPF_ALU | BPF_XOR | BPF_K: | |
364 | case BPF_ALU | BPF_MUL | BPF_X: | |
365 | case BPF_ALU | BPF_MUL | BPF_K: | |
366 | case BPF_ALU | BPF_DIV | BPF_X: | |
367 | case BPF_ALU | BPF_DIV | BPF_K: | |
368 | case BPF_ALU | BPF_MOD | BPF_X: | |
369 | case BPF_ALU | BPF_MOD | BPF_K: | |
370 | case BPF_ALU | BPF_NEG: | |
371 | case BPF_LD | BPF_ABS | BPF_W: | |
372 | case BPF_LD | BPF_ABS | BPF_H: | |
373 | case BPF_LD | BPF_ABS | BPF_B: | |
374 | case BPF_LD | BPF_IND | BPF_W: | |
375 | case BPF_LD | BPF_IND | BPF_H: | |
376 | case BPF_LD | BPF_IND | BPF_B: | |
377 | /* Check for overloaded BPF extension and | |
378 | * directly convert it if found, otherwise | |
379 | * just move on with mapping. | |
380 | */ | |
381 | if (BPF_CLASS(fp->code) == BPF_LD && | |
382 | BPF_MODE(fp->code) == BPF_ABS && | |
383 | convert_bpf_extensions(fp, &insn)) | |
384 | break; | |
385 | ||
386 | *insn = BPF_RAW_INSN(fp->code, BPF_REG_A, BPF_REG_X, 0, fp->k); | |
387 | break; | |
388 | ||
389 | /* Jump transformation cannot use BPF block macros | |
390 | * everywhere as offset calculation and target updates | |
391 | * require a bit more work than the rest, i.e. jump | |
392 | * opcodes map as-is, but offsets need adjustment. | |
393 | */ | |
394 | ||
395 | #define BPF_EMIT_JMP \ | |
396 | do { \ | |
397 | if (target >= len || target < 0) \ | |
398 | goto err; \ | |
399 | insn->off = addrs ? addrs[target] - addrs[i] - 1 : 0; \ | |
400 | /* Adjust pc relative offset for 2nd or 3rd insn. */ \ | |
401 | insn->off -= insn - tmp_insns; \ | |
402 | } while (0) | |
403 | ||
404 | case BPF_JMP | BPF_JA: | |
405 | target = i + fp->k + 1; | |
406 | insn->code = fp->code; | |
407 | BPF_EMIT_JMP; | |
408 | break; | |
409 | ||
410 | case BPF_JMP | BPF_JEQ | BPF_K: | |
411 | case BPF_JMP | BPF_JEQ | BPF_X: | |
412 | case BPF_JMP | BPF_JSET | BPF_K: | |
413 | case BPF_JMP | BPF_JSET | BPF_X: | |
414 | case BPF_JMP | BPF_JGT | BPF_K: | |
415 | case BPF_JMP | BPF_JGT | BPF_X: | |
416 | case BPF_JMP | BPF_JGE | BPF_K: | |
417 | case BPF_JMP | BPF_JGE | BPF_X: | |
418 | if (BPF_SRC(fp->code) == BPF_K && (int) fp->k < 0) { | |
419 | /* BPF immediates are signed, zero extend | |
420 | * immediate into tmp register and use it | |
421 | * in compare insn. | |
422 | */ | |
423 | *insn++ = BPF_MOV32_IMM(BPF_REG_TMP, fp->k); | |
424 | ||
425 | insn->dst_reg = BPF_REG_A; | |
426 | insn->src_reg = BPF_REG_TMP; | |
427 | bpf_src = BPF_X; | |
428 | } else { | |
429 | insn->dst_reg = BPF_REG_A; | |
430 | insn->src_reg = BPF_REG_X; | |
431 | insn->imm = fp->k; | |
432 | bpf_src = BPF_SRC(fp->code); | |
433 | } | |
434 | ||
435 | /* Common case where 'jump_false' is next insn. */ | |
436 | if (fp->jf == 0) { | |
437 | insn->code = BPF_JMP | BPF_OP(fp->code) | bpf_src; | |
438 | target = i + fp->jt + 1; | |
439 | BPF_EMIT_JMP; | |
440 | break; | |
441 | } | |
442 | ||
443 | /* Convert JEQ into JNE when 'jump_true' is next insn. */ | |
444 | if (fp->jt == 0 && BPF_OP(fp->code) == BPF_JEQ) { | |
445 | insn->code = BPF_JMP | BPF_JNE | bpf_src; | |
446 | target = i + fp->jf + 1; | |
447 | BPF_EMIT_JMP; | |
448 | break; | |
449 | } | |
450 | ||
451 | /* Other jumps are mapped into two insns: Jxx and JA. */ | |
452 | target = i + fp->jt + 1; | |
453 | insn->code = BPF_JMP | BPF_OP(fp->code) | bpf_src; | |
454 | BPF_EMIT_JMP; | |
455 | insn++; | |
456 | ||
457 | insn->code = BPF_JMP | BPF_JA; | |
458 | target = i + fp->jf + 1; | |
459 | BPF_EMIT_JMP; | |
460 | break; | |
461 | ||
462 | /* ldxb 4 * ([14] & 0xf) is remaped into 6 insns. */ | |
463 | case BPF_LDX | BPF_MSH | BPF_B: | |
464 | /* tmp = A */ | |
465 | *insn++ = BPF_MOV64_REG(BPF_REG_TMP, BPF_REG_A); | |
466 | /* A = BPF_R0 = *(u8 *) (skb->data + K) */ | |
467 | *insn++ = BPF_LD_ABS(BPF_B, fp->k); | |
468 | /* A &= 0xf */ | |
469 | *insn++ = BPF_ALU32_IMM(BPF_AND, BPF_REG_A, 0xf); | |
470 | /* A <<= 2 */ | |
471 | *insn++ = BPF_ALU32_IMM(BPF_LSH, BPF_REG_A, 2); | |
472 | /* X = A */ | |
473 | *insn++ = BPF_MOV64_REG(BPF_REG_X, BPF_REG_A); | |
474 | /* A = tmp */ | |
475 | *insn = BPF_MOV64_REG(BPF_REG_A, BPF_REG_TMP); | |
476 | break; | |
477 | ||
478 | /* RET_K, RET_A are remaped into 2 insns. */ | |
479 | case BPF_RET | BPF_A: | |
480 | case BPF_RET | BPF_K: | |
481 | *insn++ = BPF_MOV32_RAW(BPF_RVAL(fp->code) == BPF_K ? | |
482 | BPF_K : BPF_X, BPF_REG_0, | |
483 | BPF_REG_A, fp->k); | |
484 | *insn = BPF_EXIT_INSN(); | |
485 | break; | |
486 | ||
487 | /* Store to stack. */ | |
488 | case BPF_ST: | |
489 | case BPF_STX: | |
490 | *insn = BPF_STX_MEM(BPF_W, BPF_REG_FP, BPF_CLASS(fp->code) == | |
491 | BPF_ST ? BPF_REG_A : BPF_REG_X, | |
492 | -(BPF_MEMWORDS - fp->k) * 4); | |
493 | break; | |
494 | ||
495 | /* Load from stack. */ | |
496 | case BPF_LD | BPF_MEM: | |
497 | case BPF_LDX | BPF_MEM: | |
498 | *insn = BPF_LDX_MEM(BPF_W, BPF_CLASS(fp->code) == BPF_LD ? | |
499 | BPF_REG_A : BPF_REG_X, BPF_REG_FP, | |
500 | -(BPF_MEMWORDS - fp->k) * 4); | |
501 | break; | |
502 | ||
503 | /* A = K or X = K */ | |
504 | case BPF_LD | BPF_IMM: | |
505 | case BPF_LDX | BPF_IMM: | |
506 | *insn = BPF_MOV32_IMM(BPF_CLASS(fp->code) == BPF_LD ? | |
507 | BPF_REG_A : BPF_REG_X, fp->k); | |
508 | break; | |
509 | ||
510 | /* X = A */ | |
511 | case BPF_MISC | BPF_TAX: | |
512 | *insn = BPF_MOV64_REG(BPF_REG_X, BPF_REG_A); | |
513 | break; | |
514 | ||
515 | /* A = X */ | |
516 | case BPF_MISC | BPF_TXA: | |
517 | *insn = BPF_MOV64_REG(BPF_REG_A, BPF_REG_X); | |
518 | break; | |
519 | ||
520 | /* A = skb->len or X = skb->len */ | |
521 | case BPF_LD | BPF_W | BPF_LEN: | |
522 | case BPF_LDX | BPF_W | BPF_LEN: | |
523 | *insn = BPF_LDX_MEM(BPF_W, BPF_CLASS(fp->code) == BPF_LD ? | |
524 | BPF_REG_A : BPF_REG_X, BPF_REG_CTX, | |
525 | offsetof(struct sk_buff, len)); | |
526 | break; | |
527 | ||
528 | /* Access seccomp_data fields. */ | |
529 | case BPF_LDX | BPF_ABS | BPF_W: | |
530 | /* A = *(u32 *) (ctx + K) */ | |
531 | *insn = BPF_LDX_MEM(BPF_W, BPF_REG_A, BPF_REG_CTX, fp->k); | |
532 | break; | |
533 | ||
534 | /* Unknown instruction. */ | |
535 | default: | |
536 | goto err; | |
537 | } | |
538 | ||
539 | insn++; | |
540 | if (new_prog) | |
541 | memcpy(new_insn, tmp_insns, | |
542 | sizeof(*insn) * (insn - tmp_insns)); | |
543 | new_insn += insn - tmp_insns; | |
544 | } | |
545 | ||
546 | if (!new_prog) { | |
547 | /* Only calculating new length. */ | |
548 | *new_len = new_insn - new_prog; | |
549 | return 0; | |
550 | } | |
551 | ||
552 | pass++; | |
553 | if (new_flen != new_insn - new_prog) { | |
554 | new_flen = new_insn - new_prog; | |
555 | if (pass > 2) | |
556 | goto err; | |
557 | goto do_pass; | |
558 | } | |
559 | ||
560 | kfree(addrs); | |
561 | BUG_ON(*new_len != new_flen); | |
562 | return 0; | |
563 | err: | |
564 | kfree(addrs); | |
565 | return -EINVAL; | |
566 | } | |
567 | ||
568 | /* Security: | |
569 | * | |
570 | * As we dont want to clear mem[] array for each packet going through | |
571 | * __bpf_prog_run(), we check that filter loaded by user never try to read | |
572 | * a cell if not previously written, and we check all branches to be sure | |
573 | * a malicious user doesn't try to abuse us. | |
574 | */ | |
575 | static int check_load_and_stores(const struct sock_filter *filter, int flen) | |
576 | { | |
577 | u16 *masks, memvalid = 0; /* One bit per cell, 16 cells */ | |
578 | int pc, ret = 0; | |
579 | ||
580 | BUILD_BUG_ON(BPF_MEMWORDS > 16); | |
581 | ||
582 | masks = kmalloc_array(flen, sizeof(*masks), GFP_KERNEL); | |
583 | if (!masks) | |
584 | return -ENOMEM; | |
585 | ||
586 | memset(masks, 0xff, flen * sizeof(*masks)); | |
587 | ||
588 | for (pc = 0; pc < flen; pc++) { | |
589 | memvalid &= masks[pc]; | |
590 | ||
591 | switch (filter[pc].code) { | |
592 | case BPF_ST: | |
593 | case BPF_STX: | |
594 | memvalid |= (1 << filter[pc].k); | |
595 | break; | |
596 | case BPF_LD | BPF_MEM: | |
597 | case BPF_LDX | BPF_MEM: | |
598 | if (!(memvalid & (1 << filter[pc].k))) { | |
599 | ret = -EINVAL; | |
600 | goto error; | |
601 | } | |
602 | break; | |
603 | case BPF_JMP | BPF_JA: | |
604 | /* A jump must set masks on target */ | |
605 | masks[pc + 1 + filter[pc].k] &= memvalid; | |
606 | memvalid = ~0; | |
607 | break; | |
608 | case BPF_JMP | BPF_JEQ | BPF_K: | |
609 | case BPF_JMP | BPF_JEQ | BPF_X: | |
610 | case BPF_JMP | BPF_JGE | BPF_K: | |
611 | case BPF_JMP | BPF_JGE | BPF_X: | |
612 | case BPF_JMP | BPF_JGT | BPF_K: | |
613 | case BPF_JMP | BPF_JGT | BPF_X: | |
614 | case BPF_JMP | BPF_JSET | BPF_K: | |
615 | case BPF_JMP | BPF_JSET | BPF_X: | |
616 | /* A jump must set masks on targets */ | |
617 | masks[pc + 1 + filter[pc].jt] &= memvalid; | |
618 | masks[pc + 1 + filter[pc].jf] &= memvalid; | |
619 | memvalid = ~0; | |
620 | break; | |
621 | } | |
622 | } | |
623 | error: | |
624 | kfree(masks); | |
625 | return ret; | |
626 | } | |
627 | ||
628 | static bool chk_code_allowed(u16 code_to_probe) | |
629 | { | |
630 | static const bool codes[] = { | |
631 | /* 32 bit ALU operations */ | |
632 | [BPF_ALU | BPF_ADD | BPF_K] = true, | |
633 | [BPF_ALU | BPF_ADD | BPF_X] = true, | |
634 | [BPF_ALU | BPF_SUB | BPF_K] = true, | |
635 | [BPF_ALU | BPF_SUB | BPF_X] = true, | |
636 | [BPF_ALU | BPF_MUL | BPF_K] = true, | |
637 | [BPF_ALU | BPF_MUL | BPF_X] = true, | |
638 | [BPF_ALU | BPF_DIV | BPF_K] = true, | |
639 | [BPF_ALU | BPF_DIV | BPF_X] = true, | |
640 | [BPF_ALU | BPF_MOD | BPF_K] = true, | |
641 | [BPF_ALU | BPF_MOD | BPF_X] = true, | |
642 | [BPF_ALU | BPF_AND | BPF_K] = true, | |
643 | [BPF_ALU | BPF_AND | BPF_X] = true, | |
644 | [BPF_ALU | BPF_OR | BPF_K] = true, | |
645 | [BPF_ALU | BPF_OR | BPF_X] = true, | |
646 | [BPF_ALU | BPF_XOR | BPF_K] = true, | |
647 | [BPF_ALU | BPF_XOR | BPF_X] = true, | |
648 | [BPF_ALU | BPF_LSH | BPF_K] = true, | |
649 | [BPF_ALU | BPF_LSH | BPF_X] = true, | |
650 | [BPF_ALU | BPF_RSH | BPF_K] = true, | |
651 | [BPF_ALU | BPF_RSH | BPF_X] = true, | |
652 | [BPF_ALU | BPF_NEG] = true, | |
653 | /* Load instructions */ | |
654 | [BPF_LD | BPF_W | BPF_ABS] = true, | |
655 | [BPF_LD | BPF_H | BPF_ABS] = true, | |
656 | [BPF_LD | BPF_B | BPF_ABS] = true, | |
657 | [BPF_LD | BPF_W | BPF_LEN] = true, | |
658 | [BPF_LD | BPF_W | BPF_IND] = true, | |
659 | [BPF_LD | BPF_H | BPF_IND] = true, | |
660 | [BPF_LD | BPF_B | BPF_IND] = true, | |
661 | [BPF_LD | BPF_IMM] = true, | |
662 | [BPF_LD | BPF_MEM] = true, | |
663 | [BPF_LDX | BPF_W | BPF_LEN] = true, | |
664 | [BPF_LDX | BPF_B | BPF_MSH] = true, | |
665 | [BPF_LDX | BPF_IMM] = true, | |
666 | [BPF_LDX | BPF_MEM] = true, | |
667 | /* Store instructions */ | |
668 | [BPF_ST] = true, | |
669 | [BPF_STX] = true, | |
670 | /* Misc instructions */ | |
671 | [BPF_MISC | BPF_TAX] = true, | |
672 | [BPF_MISC | BPF_TXA] = true, | |
673 | /* Return instructions */ | |
674 | [BPF_RET | BPF_K] = true, | |
675 | [BPF_RET | BPF_A] = true, | |
676 | /* Jump instructions */ | |
677 | [BPF_JMP | BPF_JA] = true, | |
678 | [BPF_JMP | BPF_JEQ | BPF_K] = true, | |
679 | [BPF_JMP | BPF_JEQ | BPF_X] = true, | |
680 | [BPF_JMP | BPF_JGE | BPF_K] = true, | |
681 | [BPF_JMP | BPF_JGE | BPF_X] = true, | |
682 | [BPF_JMP | BPF_JGT | BPF_K] = true, | |
683 | [BPF_JMP | BPF_JGT | BPF_X] = true, | |
684 | [BPF_JMP | BPF_JSET | BPF_K] = true, | |
685 | [BPF_JMP | BPF_JSET | BPF_X] = true, | |
686 | }; | |
687 | ||
688 | if (code_to_probe >= ARRAY_SIZE(codes)) | |
689 | return false; | |
690 | ||
691 | return codes[code_to_probe]; | |
692 | } | |
693 | ||
694 | /** | |
695 | * bpf_check_classic - verify socket filter code | |
696 | * @filter: filter to verify | |
697 | * @flen: length of filter | |
698 | * | |
699 | * Check the user's filter code. If we let some ugly | |
700 | * filter code slip through kaboom! The filter must contain | |
701 | * no references or jumps that are out of range, no illegal | |
702 | * instructions, and must end with a RET instruction. | |
703 | * | |
704 | * All jumps are forward as they are not signed. | |
705 | * | |
706 | * Returns 0 if the rule set is legal or -EINVAL if not. | |
707 | */ | |
708 | int bpf_check_classic(const struct sock_filter *filter, unsigned int flen) | |
709 | { | |
710 | bool anc_found; | |
711 | int pc; | |
712 | ||
713 | if (flen == 0 || flen > BPF_MAXINSNS) | |
714 | return -EINVAL; | |
715 | ||
716 | /* Check the filter code now */ | |
717 | for (pc = 0; pc < flen; pc++) { | |
718 | const struct sock_filter *ftest = &filter[pc]; | |
719 | ||
720 | /* May we actually operate on this code? */ | |
721 | if (!chk_code_allowed(ftest->code)) | |
722 | return -EINVAL; | |
723 | ||
724 | /* Some instructions need special checks */ | |
725 | switch (ftest->code) { | |
726 | case BPF_ALU | BPF_DIV | BPF_K: | |
727 | case BPF_ALU | BPF_MOD | BPF_K: | |
728 | /* Check for division by zero */ | |
729 | if (ftest->k == 0) | |
730 | return -EINVAL; | |
731 | break; | |
732 | case BPF_LD | BPF_MEM: | |
733 | case BPF_LDX | BPF_MEM: | |
734 | case BPF_ST: | |
735 | case BPF_STX: | |
736 | /* Check for invalid memory addresses */ | |
737 | if (ftest->k >= BPF_MEMWORDS) | |
738 | return -EINVAL; | |
739 | break; | |
740 | case BPF_JMP | BPF_JA: | |
741 | /* Note, the large ftest->k might cause loops. | |
742 | * Compare this with conditional jumps below, | |
743 | * where offsets are limited. --ANK (981016) | |
744 | */ | |
745 | if (ftest->k >= (unsigned int)(flen - pc - 1)) | |
746 | return -EINVAL; | |
747 | break; | |
748 | case BPF_JMP | BPF_JEQ | BPF_K: | |
749 | case BPF_JMP | BPF_JEQ | BPF_X: | |
750 | case BPF_JMP | BPF_JGE | BPF_K: | |
751 | case BPF_JMP | BPF_JGE | BPF_X: | |
752 | case BPF_JMP | BPF_JGT | BPF_K: | |
753 | case BPF_JMP | BPF_JGT | BPF_X: | |
754 | case BPF_JMP | BPF_JSET | BPF_K: | |
755 | case BPF_JMP | BPF_JSET | BPF_X: | |
756 | /* Both conditionals must be safe */ | |
757 | if (pc + ftest->jt + 1 >= flen || | |
758 | pc + ftest->jf + 1 >= flen) | |
759 | return -EINVAL; | |
760 | break; | |
761 | case BPF_LD | BPF_W | BPF_ABS: | |
762 | case BPF_LD | BPF_H | BPF_ABS: | |
763 | case BPF_LD | BPF_B | BPF_ABS: | |
764 | anc_found = false; | |
765 | if (bpf_anc_helper(ftest) & BPF_ANC) | |
766 | anc_found = true; | |
767 | /* Ancillary operation unknown or unsupported */ | |
768 | if (anc_found == false && ftest->k >= SKF_AD_OFF) | |
769 | return -EINVAL; | |
770 | } | |
771 | } | |
772 | ||
773 | /* Last instruction must be a RET code */ | |
774 | switch (filter[flen - 1].code) { | |
775 | case BPF_RET | BPF_K: | |
776 | case BPF_RET | BPF_A: | |
777 | return check_load_and_stores(filter, flen); | |
778 | } | |
779 | ||
780 | return -EINVAL; | |
781 | } | |
782 | EXPORT_SYMBOL(bpf_check_classic); | |
783 | ||
784 | static int bpf_prog_store_orig_filter(struct bpf_prog *fp, | |
785 | const struct sock_fprog *fprog) | |
786 | { | |
787 | unsigned int fsize = bpf_classic_proglen(fprog); | |
788 | struct sock_fprog_kern *fkprog; | |
789 | ||
790 | fp->orig_prog = kmalloc(sizeof(*fkprog), GFP_KERNEL); | |
791 | if (!fp->orig_prog) | |
792 | return -ENOMEM; | |
793 | ||
794 | fkprog = fp->orig_prog; | |
795 | fkprog->len = fprog->len; | |
796 | fkprog->filter = kmemdup(fp->insns, fsize, GFP_KERNEL); | |
797 | if (!fkprog->filter) { | |
798 | kfree(fp->orig_prog); | |
799 | return -ENOMEM; | |
800 | } | |
801 | ||
802 | return 0; | |
803 | } | |
804 | ||
805 | static void bpf_release_orig_filter(struct bpf_prog *fp) | |
806 | { | |
807 | struct sock_fprog_kern *fprog = fp->orig_prog; | |
808 | ||
809 | if (fprog) { | |
810 | kfree(fprog->filter); | |
811 | kfree(fprog); | |
812 | } | |
813 | } | |
814 | ||
815 | static void __bpf_prog_release(struct bpf_prog *prog) | |
816 | { | |
817 | if (prog->type == BPF_PROG_TYPE_SOCKET_FILTER) { | |
818 | bpf_prog_put(prog); | |
819 | } else { | |
820 | bpf_release_orig_filter(prog); | |
821 | bpf_prog_free(prog); | |
822 | } | |
823 | } | |
824 | ||
825 | static void __sk_filter_release(struct sk_filter *fp) | |
826 | { | |
827 | __bpf_prog_release(fp->prog); | |
828 | kfree(fp); | |
829 | } | |
830 | ||
831 | /** | |
832 | * sk_filter_release_rcu - Release a socket filter by rcu_head | |
833 | * @rcu: rcu_head that contains the sk_filter to free | |
834 | */ | |
835 | static void sk_filter_release_rcu(struct rcu_head *rcu) | |
836 | { | |
837 | struct sk_filter *fp = container_of(rcu, struct sk_filter, rcu); | |
838 | ||
839 | __sk_filter_release(fp); | |
840 | } | |
841 | ||
842 | /** | |
843 | * sk_filter_release - release a socket filter | |
844 | * @fp: filter to remove | |
845 | * | |
846 | * Remove a filter from a socket and release its resources. | |
847 | */ | |
848 | static void sk_filter_release(struct sk_filter *fp) | |
849 | { | |
850 | if (atomic_dec_and_test(&fp->refcnt)) | |
851 | call_rcu(&fp->rcu, sk_filter_release_rcu); | |
852 | } | |
853 | ||
854 | void sk_filter_uncharge(struct sock *sk, struct sk_filter *fp) | |
855 | { | |
856 | u32 filter_size = bpf_prog_size(fp->prog->len); | |
857 | ||
858 | atomic_sub(filter_size, &sk->sk_omem_alloc); | |
859 | sk_filter_release(fp); | |
860 | } | |
861 | ||
862 | /* try to charge the socket memory if there is space available | |
863 | * return true on success | |
864 | */ | |
865 | bool sk_filter_charge(struct sock *sk, struct sk_filter *fp) | |
866 | { | |
867 | u32 filter_size = bpf_prog_size(fp->prog->len); | |
868 | ||
869 | /* same check as in sock_kmalloc() */ | |
870 | if (filter_size <= sysctl_optmem_max && | |
871 | atomic_read(&sk->sk_omem_alloc) + filter_size < sysctl_optmem_max) { | |
872 | atomic_inc(&fp->refcnt); | |
873 | atomic_add(filter_size, &sk->sk_omem_alloc); | |
874 | return true; | |
875 | } | |
876 | return false; | |
877 | } | |
878 | ||
879 | static struct bpf_prog *bpf_migrate_filter(struct bpf_prog *fp) | |
880 | { | |
881 | struct sock_filter *old_prog; | |
882 | struct bpf_prog *old_fp; | |
883 | int err, new_len, old_len = fp->len; | |
884 | ||
885 | /* We are free to overwrite insns et al right here as it | |
886 | * won't be used at this point in time anymore internally | |
887 | * after the migration to the internal BPF instruction | |
888 | * representation. | |
889 | */ | |
890 | BUILD_BUG_ON(sizeof(struct sock_filter) != | |
891 | sizeof(struct bpf_insn)); | |
892 | ||
893 | /* Conversion cannot happen on overlapping memory areas, | |
894 | * so we need to keep the user BPF around until the 2nd | |
895 | * pass. At this time, the user BPF is stored in fp->insns. | |
896 | */ | |
897 | old_prog = kmemdup(fp->insns, old_len * sizeof(struct sock_filter), | |
898 | GFP_KERNEL); | |
899 | if (!old_prog) { | |
900 | err = -ENOMEM; | |
901 | goto out_err; | |
902 | } | |
903 | ||
904 | /* 1st pass: calculate the new program length. */ | |
905 | err = bpf_convert_filter(old_prog, old_len, NULL, &new_len); | |
906 | if (err) | |
907 | goto out_err_free; | |
908 | ||
909 | /* Expand fp for appending the new filter representation. */ | |
910 | old_fp = fp; | |
911 | fp = bpf_prog_realloc(old_fp, bpf_prog_size(new_len), 0); | |
912 | if (!fp) { | |
913 | /* The old_fp is still around in case we couldn't | |
914 | * allocate new memory, so uncharge on that one. | |
915 | */ | |
916 | fp = old_fp; | |
917 | err = -ENOMEM; | |
918 | goto out_err_free; | |
919 | } | |
920 | ||
921 | fp->len = new_len; | |
922 | ||
923 | /* 2nd pass: remap sock_filter insns into bpf_insn insns. */ | |
924 | err = bpf_convert_filter(old_prog, old_len, fp->insnsi, &new_len); | |
925 | if (err) | |
926 | /* 2nd bpf_convert_filter() can fail only if it fails | |
927 | * to allocate memory, remapping must succeed. Note, | |
928 | * that at this time old_fp has already been released | |
929 | * by krealloc(). | |
930 | */ | |
931 | goto out_err_free; | |
932 | ||
933 | bpf_prog_select_runtime(fp); | |
934 | ||
935 | kfree(old_prog); | |
936 | return fp; | |
937 | ||
938 | out_err_free: | |
939 | kfree(old_prog); | |
940 | out_err: | |
941 | __bpf_prog_release(fp); | |
942 | return ERR_PTR(err); | |
943 | } | |
944 | ||
945 | static struct bpf_prog *bpf_prepare_filter(struct bpf_prog *fp) | |
946 | { | |
947 | int err; | |
948 | ||
949 | fp->bpf_func = NULL; | |
950 | fp->jited = false; | |
951 | ||
952 | err = bpf_check_classic(fp->insns, fp->len); | |
953 | if (err) { | |
954 | __bpf_prog_release(fp); | |
955 | return ERR_PTR(err); | |
956 | } | |
957 | ||
958 | /* Probe if we can JIT compile the filter and if so, do | |
959 | * the compilation of the filter. | |
960 | */ | |
961 | bpf_jit_compile(fp); | |
962 | ||
963 | /* JIT compiler couldn't process this filter, so do the | |
964 | * internal BPF translation for the optimized interpreter. | |
965 | */ | |
966 | if (!fp->jited) | |
967 | fp = bpf_migrate_filter(fp); | |
968 | ||
969 | return fp; | |
970 | } | |
971 | ||
972 | /** | |
973 | * bpf_prog_create - create an unattached filter | |
974 | * @pfp: the unattached filter that is created | |
975 | * @fprog: the filter program | |
976 | * | |
977 | * Create a filter independent of any socket. We first run some | |
978 | * sanity checks on it to make sure it does not explode on us later. | |
979 | * If an error occurs or there is insufficient memory for the filter | |
980 | * a negative errno code is returned. On success the return is zero. | |
981 | */ | |
982 | int bpf_prog_create(struct bpf_prog **pfp, struct sock_fprog_kern *fprog) | |
983 | { | |
984 | unsigned int fsize = bpf_classic_proglen(fprog); | |
985 | struct bpf_prog *fp; | |
986 | ||
987 | /* Make sure new filter is there and in the right amounts. */ | |
988 | if (fprog->filter == NULL) | |
989 | return -EINVAL; | |
990 | ||
991 | fp = bpf_prog_alloc(bpf_prog_size(fprog->len), 0); | |
992 | if (!fp) | |
993 | return -ENOMEM; | |
994 | ||
995 | memcpy(fp->insns, fprog->filter, fsize); | |
996 | ||
997 | fp->len = fprog->len; | |
998 | /* Since unattached filters are not copied back to user | |
999 | * space through sk_get_filter(), we do not need to hold | |
1000 | * a copy here, and can spare us the work. | |
1001 | */ | |
1002 | fp->orig_prog = NULL; | |
1003 | ||
1004 | /* bpf_prepare_filter() already takes care of freeing | |
1005 | * memory in case something goes wrong. | |
1006 | */ | |
1007 | fp = bpf_prepare_filter(fp); | |
1008 | if (IS_ERR(fp)) | |
1009 | return PTR_ERR(fp); | |
1010 | ||
1011 | *pfp = fp; | |
1012 | return 0; | |
1013 | } | |
1014 | EXPORT_SYMBOL_GPL(bpf_prog_create); | |
1015 | ||
1016 | void bpf_prog_destroy(struct bpf_prog *fp) | |
1017 | { | |
1018 | __bpf_prog_release(fp); | |
1019 | } | |
1020 | EXPORT_SYMBOL_GPL(bpf_prog_destroy); | |
1021 | ||
1022 | static int __sk_attach_prog(struct bpf_prog *prog, struct sock *sk) | |
1023 | { | |
1024 | struct sk_filter *fp, *old_fp; | |
1025 | ||
1026 | fp = kmalloc(sizeof(*fp), GFP_KERNEL); | |
1027 | if (!fp) | |
1028 | return -ENOMEM; | |
1029 | ||
1030 | fp->prog = prog; | |
1031 | atomic_set(&fp->refcnt, 0); | |
1032 | ||
1033 | if (!sk_filter_charge(sk, fp)) { | |
1034 | kfree(fp); | |
1035 | return -ENOMEM; | |
1036 | } | |
1037 | ||
1038 | old_fp = rcu_dereference_protected(sk->sk_filter, | |
1039 | sock_owned_by_user(sk)); | |
1040 | rcu_assign_pointer(sk->sk_filter, fp); | |
1041 | ||
1042 | if (old_fp) | |
1043 | sk_filter_uncharge(sk, old_fp); | |
1044 | ||
1045 | return 0; | |
1046 | } | |
1047 | ||
1048 | /** | |
1049 | * sk_attach_filter - attach a socket filter | |
1050 | * @fprog: the filter program | |
1051 | * @sk: the socket to use | |
1052 | * | |
1053 | * Attach the user's filter code. We first run some sanity checks on | |
1054 | * it to make sure it does not explode on us later. If an error | |
1055 | * occurs or there is insufficient memory for the filter a negative | |
1056 | * errno code is returned. On success the return is zero. | |
1057 | */ | |
1058 | int sk_attach_filter(struct sock_fprog *fprog, struct sock *sk) | |
1059 | { | |
1060 | unsigned int fsize = bpf_classic_proglen(fprog); | |
1061 | unsigned int bpf_fsize = bpf_prog_size(fprog->len); | |
1062 | struct bpf_prog *prog; | |
1063 | int err; | |
1064 | ||
1065 | if (sock_flag(sk, SOCK_FILTER_LOCKED)) | |
1066 | return -EPERM; | |
1067 | ||
1068 | /* Make sure new filter is there and in the right amounts. */ | |
1069 | if (fprog->filter == NULL) | |
1070 | return -EINVAL; | |
1071 | ||
1072 | prog = bpf_prog_alloc(bpf_fsize, 0); | |
1073 | if (!prog) | |
1074 | return -ENOMEM; | |
1075 | ||
1076 | if (copy_from_user(prog->insns, fprog->filter, fsize)) { | |
1077 | __bpf_prog_free(prog); | |
1078 | return -EFAULT; | |
1079 | } | |
1080 | ||
1081 | prog->len = fprog->len; | |
1082 | ||
1083 | err = bpf_prog_store_orig_filter(prog, fprog); | |
1084 | if (err) { | |
1085 | __bpf_prog_free(prog); | |
1086 | return -ENOMEM; | |
1087 | } | |
1088 | ||
1089 | /* bpf_prepare_filter() already takes care of freeing | |
1090 | * memory in case something goes wrong. | |
1091 | */ | |
1092 | prog = bpf_prepare_filter(prog); | |
1093 | if (IS_ERR(prog)) | |
1094 | return PTR_ERR(prog); | |
1095 | ||
1096 | err = __sk_attach_prog(prog, sk); | |
1097 | if (err < 0) { | |
1098 | __bpf_prog_release(prog); | |
1099 | return err; | |
1100 | } | |
1101 | ||
1102 | return 0; | |
1103 | } | |
1104 | EXPORT_SYMBOL_GPL(sk_attach_filter); | |
1105 | ||
1106 | int sk_attach_bpf(u32 ufd, struct sock *sk) | |
1107 | { | |
1108 | struct bpf_prog *prog; | |
1109 | int err; | |
1110 | ||
1111 | if (sock_flag(sk, SOCK_FILTER_LOCKED)) | |
1112 | return -EPERM; | |
1113 | ||
1114 | prog = bpf_prog_get(ufd); | |
1115 | if (IS_ERR(prog)) | |
1116 | return PTR_ERR(prog); | |
1117 | ||
1118 | if (prog->type != BPF_PROG_TYPE_SOCKET_FILTER) { | |
1119 | bpf_prog_put(prog); | |
1120 | return -EINVAL; | |
1121 | } | |
1122 | ||
1123 | err = __sk_attach_prog(prog, sk); | |
1124 | if (err < 0) { | |
1125 | bpf_prog_put(prog); | |
1126 | return err; | |
1127 | } | |
1128 | ||
1129 | return 0; | |
1130 | } | |
1131 | ||
1132 | static const struct bpf_func_proto * | |
1133 | sk_filter_func_proto(enum bpf_func_id func_id) | |
1134 | { | |
1135 | switch (func_id) { | |
1136 | case BPF_FUNC_map_lookup_elem: | |
1137 | return &bpf_map_lookup_elem_proto; | |
1138 | case BPF_FUNC_map_update_elem: | |
1139 | return &bpf_map_update_elem_proto; | |
1140 | case BPF_FUNC_map_delete_elem: | |
1141 | return &bpf_map_delete_elem_proto; | |
1142 | case BPF_FUNC_get_prandom_u32: | |
1143 | return &bpf_get_prandom_u32_proto; | |
1144 | default: | |
1145 | return NULL; | |
1146 | } | |
1147 | } | |
1148 | ||
1149 | static bool sk_filter_is_valid_access(int off, int size, | |
1150 | enum bpf_access_type type) | |
1151 | { | |
1152 | /* skb fields cannot be accessed yet */ | |
1153 | return false; | |
1154 | } | |
1155 | ||
1156 | static const struct bpf_verifier_ops sk_filter_ops = { | |
1157 | .get_func_proto = sk_filter_func_proto, | |
1158 | .is_valid_access = sk_filter_is_valid_access, | |
1159 | }; | |
1160 | ||
1161 | static struct bpf_prog_type_list sk_filter_type __read_mostly = { | |
1162 | .ops = &sk_filter_ops, | |
1163 | .type = BPF_PROG_TYPE_SOCKET_FILTER, | |
1164 | }; | |
1165 | ||
1166 | static struct bpf_prog_type_list sched_cls_type __read_mostly = { | |
1167 | .ops = &sk_filter_ops, | |
1168 | .type = BPF_PROG_TYPE_SCHED_CLS, | |
1169 | }; | |
1170 | ||
1171 | static int __init register_sk_filter_ops(void) | |
1172 | { | |
1173 | bpf_register_prog_type(&sk_filter_type); | |
1174 | bpf_register_prog_type(&sched_cls_type); | |
1175 | ||
1176 | return 0; | |
1177 | } | |
1178 | late_initcall(register_sk_filter_ops); | |
1179 | ||
1180 | int sk_detach_filter(struct sock *sk) | |
1181 | { | |
1182 | int ret = -ENOENT; | |
1183 | struct sk_filter *filter; | |
1184 | ||
1185 | if (sock_flag(sk, SOCK_FILTER_LOCKED)) | |
1186 | return -EPERM; | |
1187 | ||
1188 | filter = rcu_dereference_protected(sk->sk_filter, | |
1189 | sock_owned_by_user(sk)); | |
1190 | if (filter) { | |
1191 | RCU_INIT_POINTER(sk->sk_filter, NULL); | |
1192 | sk_filter_uncharge(sk, filter); | |
1193 | ret = 0; | |
1194 | } | |
1195 | ||
1196 | return ret; | |
1197 | } | |
1198 | EXPORT_SYMBOL_GPL(sk_detach_filter); | |
1199 | ||
1200 | int sk_get_filter(struct sock *sk, struct sock_filter __user *ubuf, | |
1201 | unsigned int len) | |
1202 | { | |
1203 | struct sock_fprog_kern *fprog; | |
1204 | struct sk_filter *filter; | |
1205 | int ret = 0; | |
1206 | ||
1207 | lock_sock(sk); | |
1208 | filter = rcu_dereference_protected(sk->sk_filter, | |
1209 | sock_owned_by_user(sk)); | |
1210 | if (!filter) | |
1211 | goto out; | |
1212 | ||
1213 | /* We're copying the filter that has been originally attached, | |
1214 | * so no conversion/decode needed anymore. | |
1215 | */ | |
1216 | fprog = filter->prog->orig_prog; | |
1217 | ||
1218 | ret = fprog->len; | |
1219 | if (!len) | |
1220 | /* User space only enquires number of filter blocks. */ | |
1221 | goto out; | |
1222 | ||
1223 | ret = -EINVAL; | |
1224 | if (len < fprog->len) | |
1225 | goto out; | |
1226 | ||
1227 | ret = -EFAULT; | |
1228 | if (copy_to_user(ubuf, fprog->filter, bpf_classic_proglen(fprog))) | |
1229 | goto out; | |
1230 | ||
1231 | /* Instead of bytes, the API requests to return the number | |
1232 | * of filter blocks. | |
1233 | */ | |
1234 | ret = fprog->len; | |
1235 | out: | |
1236 | release_sock(sk); | |
1237 | return ret; | |
1238 | } |