2 * Linux Socket Filter - Kernel level socket filtering
4 * Based on the design of the Berkeley Packet Filter. The new
5 * internal format has been designed by PLUMgrid:
7 * Copyright (c) 2011 - 2014 PLUMgrid, http://plumgrid.com
11 * Jay Schulist <jschlst@samba.org>
12 * Alexei Starovoitov <ast@plumgrid.com>
13 * Daniel Borkmann <dborkman@redhat.com>
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.
20 * Andi Kleen - Fix a few bad bugs and races.
21 * Kris Katterjohn - Added many additional checks in bpf_check_classic()
24 #include <linux/module.h>
25 #include <linux/types.h>
27 #include <linux/fcntl.h>
28 #include <linux/socket.h>
30 #include <linux/inet.h>
31 #include <linux/netdevice.h>
32 #include <linux/if_packet.h>
33 #include <linux/gfp.h>
35 #include <net/protocol.h>
36 #include <net/netlink.h>
37 #include <linux/skbuff.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>
49 * sk_filter - run a packet through a socket filter
50 * @sk: sock associated with &sk_buff
51 * @skb: buffer to filter
53 * Run the filter code and then cut skb->data to correct size returned by
54 * sk_run_filter. If pkt_len is 0 we toss packet. If skb->len is smaller
55 * than pkt_len we keep whole skb->data. This is the socket level
56 * wrapper to sk_run_filter. It returns 0 if the packet should
57 * be accepted or -EPERM if the packet should be tossed.
60 int sk_filter(struct sock
*sk
, struct sk_buff
*skb
)
63 struct sk_filter
*filter
;
66 * If the skb was allocated from pfmemalloc reserves, only
67 * allow SOCK_MEMALLOC sockets to use it as this socket is
70 if (skb_pfmemalloc(skb
) && !sock_flag(sk
, SOCK_MEMALLOC
))
73 err
= security_sock_rcv_skb(sk
, skb
);
78 filter
= rcu_dereference(sk
->sk_filter
);
80 unsigned int pkt_len
= SK_RUN_FILTER(filter
, skb
);
82 err
= pkt_len
? pskb_trim(skb
, pkt_len
) : -EPERM
;
88 EXPORT_SYMBOL(sk_filter
);
90 /* Helper to find the offset of pkt_type in sk_buff structure. We want
91 * to make sure its still a 3bit field starting at a byte boundary;
92 * taken from arch/x86/net/bpf_jit_comp.c.
94 #ifdef __BIG_ENDIAN_BITFIELD
95 #define PKT_TYPE_MAX (7 << 5)
97 #define PKT_TYPE_MAX 7
99 static unsigned int pkt_type_offset(void)
101 struct sk_buff skb_probe
= { .pkt_type
= ~0, };
102 u8
*ct
= (u8
*) &skb_probe
;
105 for (off
= 0; off
< sizeof(struct sk_buff
); off
++) {
106 if (ct
[off
] == PKT_TYPE_MAX
)
110 pr_err_once("Please fix %s, as pkt_type couldn't be found!\n", __func__
);
114 static u64
__skb_get_pay_offset(u64 ctx
, u64 a
, u64 x
, u64 r4
, u64 r5
)
116 return __skb_get_poff((struct sk_buff
*)(unsigned long) ctx
);
119 static u64
__skb_get_nlattr(u64 ctx
, u64 a
, u64 x
, u64 r4
, u64 r5
)
121 struct sk_buff
*skb
= (struct sk_buff
*)(unsigned long) ctx
;
124 if (skb_is_nonlinear(skb
))
127 if (skb
->len
< sizeof(struct nlattr
))
130 if (a
> skb
->len
- sizeof(struct nlattr
))
133 nla
= nla_find((struct nlattr
*) &skb
->data
[a
], skb
->len
- a
, x
);
135 return (void *) nla
- (void *) skb
->data
;
140 static u64
__skb_get_nlattr_nest(u64 ctx
, u64 a
, u64 x
, u64 r4
, u64 r5
)
142 struct sk_buff
*skb
= (struct sk_buff
*)(unsigned long) ctx
;
145 if (skb_is_nonlinear(skb
))
148 if (skb
->len
< sizeof(struct nlattr
))
151 if (a
> skb
->len
- sizeof(struct nlattr
))
154 nla
= (struct nlattr
*) &skb
->data
[a
];
155 if (nla
->nla_len
> skb
->len
- a
)
158 nla
= nla_find_nested(nla
, x
);
160 return (void *) nla
- (void *) skb
->data
;
165 static u64
__get_raw_cpu_id(u64 ctx
, u64 a
, u64 x
, u64 r4
, u64 r5
)
167 return raw_smp_processor_id();
170 /* note that this only generates 32-bit random numbers */
171 static u64
__get_random_u32(u64 ctx
, u64 a
, u64 x
, u64 r4
, u64 r5
)
173 return prandom_u32();
176 static bool convert_bpf_extensions(struct sock_filter
*fp
,
177 struct bpf_insn
**insnp
)
179 struct bpf_insn
*insn
= *insnp
;
182 case SKF_AD_OFF
+ SKF_AD_PROTOCOL
:
183 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff
, protocol
) != 2);
185 /* A = *(u16 *) (CTX + offsetof(protocol)) */
186 *insn
++ = BPF_LDX_MEM(BPF_H
, BPF_REG_A
, BPF_REG_CTX
,
187 offsetof(struct sk_buff
, protocol
));
188 /* A = ntohs(A) [emitting a nop or swap16] */
189 *insn
= BPF_ENDIAN(BPF_FROM_BE
, BPF_REG_A
, 16);
192 case SKF_AD_OFF
+ SKF_AD_PKTTYPE
:
193 *insn
= BPF_LDX_MEM(BPF_B
, BPF_REG_A
, BPF_REG_CTX
,
198 *insn
= BPF_ALU32_IMM(BPF_AND
, BPF_REG_A
, PKT_TYPE_MAX
);
199 #ifdef __BIG_ENDIAN_BITFIELD
201 *insn
= BPF_ALU32_IMM(BPF_RSH
, BPF_REG_A
, 5);
205 case SKF_AD_OFF
+ SKF_AD_IFINDEX
:
206 case SKF_AD_OFF
+ SKF_AD_HATYPE
:
207 BUILD_BUG_ON(FIELD_SIZEOF(struct net_device
, ifindex
) != 4);
208 BUILD_BUG_ON(FIELD_SIZEOF(struct net_device
, type
) != 2);
209 BUILD_BUG_ON(bytes_to_bpf_size(FIELD_SIZEOF(struct sk_buff
, dev
)) < 0);
211 *insn
++ = BPF_LDX_MEM(bytes_to_bpf_size(FIELD_SIZEOF(struct sk_buff
, dev
)),
212 BPF_REG_TMP
, BPF_REG_CTX
,
213 offsetof(struct sk_buff
, dev
));
214 /* if (tmp != 0) goto pc + 1 */
215 *insn
++ = BPF_JMP_IMM(BPF_JNE
, BPF_REG_TMP
, 0, 1);
216 *insn
++ = BPF_EXIT_INSN();
217 if (fp
->k
== SKF_AD_OFF
+ SKF_AD_IFINDEX
)
218 *insn
= BPF_LDX_MEM(BPF_W
, BPF_REG_A
, BPF_REG_TMP
,
219 offsetof(struct net_device
, ifindex
));
221 *insn
= BPF_LDX_MEM(BPF_H
, BPF_REG_A
, BPF_REG_TMP
,
222 offsetof(struct net_device
, type
));
225 case SKF_AD_OFF
+ SKF_AD_MARK
:
226 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff
, mark
) != 4);
228 *insn
= BPF_LDX_MEM(BPF_W
, BPF_REG_A
, BPF_REG_CTX
,
229 offsetof(struct sk_buff
, mark
));
232 case SKF_AD_OFF
+ SKF_AD_RXHASH
:
233 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff
, hash
) != 4);
235 *insn
= BPF_LDX_MEM(BPF_W
, BPF_REG_A
, BPF_REG_CTX
,
236 offsetof(struct sk_buff
, hash
));
239 case SKF_AD_OFF
+ SKF_AD_QUEUE
:
240 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff
, queue_mapping
) != 2);
242 *insn
= BPF_LDX_MEM(BPF_H
, BPF_REG_A
, BPF_REG_CTX
,
243 offsetof(struct sk_buff
, queue_mapping
));
246 case SKF_AD_OFF
+ SKF_AD_VLAN_TAG
:
247 case SKF_AD_OFF
+ SKF_AD_VLAN_TAG_PRESENT
:
248 BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff
, vlan_tci
) != 2);
249 BUILD_BUG_ON(VLAN_TAG_PRESENT
!= 0x1000);
251 /* A = *(u16 *) (CTX + offsetof(vlan_tci)) */
252 *insn
++ = BPF_LDX_MEM(BPF_H
, BPF_REG_A
, BPF_REG_CTX
,
253 offsetof(struct sk_buff
, vlan_tci
));
254 if (fp
->k
== SKF_AD_OFF
+ SKF_AD_VLAN_TAG
) {
255 *insn
= BPF_ALU32_IMM(BPF_AND
, BPF_REG_A
,
259 *insn
++ = BPF_ALU32_IMM(BPF_RSH
, BPF_REG_A
, 12);
261 *insn
= BPF_ALU32_IMM(BPF_AND
, BPF_REG_A
, 1);
265 case SKF_AD_OFF
+ SKF_AD_PAY_OFFSET
:
266 case SKF_AD_OFF
+ SKF_AD_NLATTR
:
267 case SKF_AD_OFF
+ SKF_AD_NLATTR_NEST
:
268 case SKF_AD_OFF
+ SKF_AD_CPU
:
269 case SKF_AD_OFF
+ SKF_AD_RANDOM
:
271 *insn
++ = BPF_MOV64_REG(BPF_REG_ARG1
, BPF_REG_CTX
);
273 *insn
++ = BPF_MOV64_REG(BPF_REG_ARG2
, BPF_REG_A
);
275 *insn
++ = BPF_MOV64_REG(BPF_REG_ARG3
, BPF_REG_X
);
276 /* Emit call(arg1=CTX, arg2=A, arg3=X) */
278 case SKF_AD_OFF
+ SKF_AD_PAY_OFFSET
:
279 *insn
= BPF_EMIT_CALL(__skb_get_pay_offset
);
281 case SKF_AD_OFF
+ SKF_AD_NLATTR
:
282 *insn
= BPF_EMIT_CALL(__skb_get_nlattr
);
284 case SKF_AD_OFF
+ SKF_AD_NLATTR_NEST
:
285 *insn
= BPF_EMIT_CALL(__skb_get_nlattr_nest
);
287 case SKF_AD_OFF
+ SKF_AD_CPU
:
288 *insn
= BPF_EMIT_CALL(__get_raw_cpu_id
);
290 case SKF_AD_OFF
+ SKF_AD_RANDOM
:
291 *insn
= BPF_EMIT_CALL(__get_random_u32
);
296 case SKF_AD_OFF
+ SKF_AD_ALU_XOR_X
:
298 *insn
= BPF_ALU32_REG(BPF_XOR
, BPF_REG_A
, BPF_REG_X
);
302 /* This is just a dummy call to avoid letting the compiler
303 * evict __bpf_call_base() as an optimization. Placed here
304 * where no-one bothers.
306 BUG_ON(__bpf_call_base(0, 0, 0, 0, 0) != 0);
315 * bpf_convert_filter - convert filter program
316 * @prog: the user passed filter program
317 * @len: the length of the user passed filter program
318 * @new_prog: buffer where converted program will be stored
319 * @new_len: pointer to store length of converted program
321 * Remap 'sock_filter' style BPF instruction set to 'sock_filter_ext' style.
322 * Conversion workflow:
324 * 1) First pass for calculating the new program length:
325 * bpf_convert_filter(old_prog, old_len, NULL, &new_len)
327 * 2) 2nd pass to remap in two passes: 1st pass finds new
328 * jump offsets, 2nd pass remapping:
329 * new_prog = kmalloc(sizeof(struct bpf_insn) * new_len);
330 * bpf_convert_filter(old_prog, old_len, new_prog, &new_len);
332 * User BPF's register A is mapped to our BPF register 6, user BPF
333 * register X is mapped to BPF register 7; frame pointer is always
334 * register 10; Context 'void *ctx' is stored in register 1, that is,
335 * for socket filters: ctx == 'struct sk_buff *', for seccomp:
336 * ctx == 'struct seccomp_data *'.
338 int bpf_convert_filter(struct sock_filter
*prog
, int len
,
339 struct bpf_insn
*new_prog
, int *new_len
)
341 int new_flen
= 0, pass
= 0, target
, i
;
342 struct bpf_insn
*new_insn
;
343 struct sock_filter
*fp
;
347 BUILD_BUG_ON(BPF_MEMWORDS
* sizeof(u32
) > MAX_BPF_STACK
);
348 BUILD_BUG_ON(BPF_REG_FP
+ 1 != MAX_BPF_REG
);
350 if (len
<= 0 || len
> BPF_MAXINSNS
)
354 addrs
= kcalloc(len
, sizeof(*addrs
), GFP_KERNEL
);
364 *new_insn
= BPF_MOV64_REG(BPF_REG_CTX
, BPF_REG_ARG1
);
367 for (i
= 0; i
< len
; fp
++, i
++) {
368 struct bpf_insn tmp_insns
[6] = { };
369 struct bpf_insn
*insn
= tmp_insns
;
372 addrs
[i
] = new_insn
- new_prog
;
375 /* All arithmetic insns and skb loads map as-is. */
376 case BPF_ALU
| BPF_ADD
| BPF_X
:
377 case BPF_ALU
| BPF_ADD
| BPF_K
:
378 case BPF_ALU
| BPF_SUB
| BPF_X
:
379 case BPF_ALU
| BPF_SUB
| BPF_K
:
380 case BPF_ALU
| BPF_AND
| BPF_X
:
381 case BPF_ALU
| BPF_AND
| BPF_K
:
382 case BPF_ALU
| BPF_OR
| BPF_X
:
383 case BPF_ALU
| BPF_OR
| BPF_K
:
384 case BPF_ALU
| BPF_LSH
| BPF_X
:
385 case BPF_ALU
| BPF_LSH
| BPF_K
:
386 case BPF_ALU
| BPF_RSH
| BPF_X
:
387 case BPF_ALU
| BPF_RSH
| BPF_K
:
388 case BPF_ALU
| BPF_XOR
| BPF_X
:
389 case BPF_ALU
| BPF_XOR
| BPF_K
:
390 case BPF_ALU
| BPF_MUL
| BPF_X
:
391 case BPF_ALU
| BPF_MUL
| BPF_K
:
392 case BPF_ALU
| BPF_DIV
| BPF_X
:
393 case BPF_ALU
| BPF_DIV
| BPF_K
:
394 case BPF_ALU
| BPF_MOD
| BPF_X
:
395 case BPF_ALU
| BPF_MOD
| BPF_K
:
396 case BPF_ALU
| BPF_NEG
:
397 case BPF_LD
| BPF_ABS
| BPF_W
:
398 case BPF_LD
| BPF_ABS
| BPF_H
:
399 case BPF_LD
| BPF_ABS
| BPF_B
:
400 case BPF_LD
| BPF_IND
| BPF_W
:
401 case BPF_LD
| BPF_IND
| BPF_H
:
402 case BPF_LD
| BPF_IND
| BPF_B
:
403 /* Check for overloaded BPF extension and
404 * directly convert it if found, otherwise
405 * just move on with mapping.
407 if (BPF_CLASS(fp
->code
) == BPF_LD
&&
408 BPF_MODE(fp
->code
) == BPF_ABS
&&
409 convert_bpf_extensions(fp
, &insn
))
412 *insn
= BPF_RAW_INSN(fp
->code
, BPF_REG_A
, BPF_REG_X
, 0, fp
->k
);
415 /* Jump transformation cannot use BPF block macros
416 * everywhere as offset calculation and target updates
417 * require a bit more work than the rest, i.e. jump
418 * opcodes map as-is, but offsets need adjustment.
421 #define BPF_EMIT_JMP \
423 if (target >= len || target < 0) \
425 insn->off = addrs ? addrs[target] - addrs[i] - 1 : 0; \
426 /* Adjust pc relative offset for 2nd or 3rd insn. */ \
427 insn->off -= insn - tmp_insns; \
430 case BPF_JMP
| BPF_JA
:
431 target
= i
+ fp
->k
+ 1;
432 insn
->code
= fp
->code
;
436 case BPF_JMP
| BPF_JEQ
| BPF_K
:
437 case BPF_JMP
| BPF_JEQ
| BPF_X
:
438 case BPF_JMP
| BPF_JSET
| BPF_K
:
439 case BPF_JMP
| BPF_JSET
| BPF_X
:
440 case BPF_JMP
| BPF_JGT
| BPF_K
:
441 case BPF_JMP
| BPF_JGT
| BPF_X
:
442 case BPF_JMP
| BPF_JGE
| BPF_K
:
443 case BPF_JMP
| BPF_JGE
| BPF_X
:
444 if (BPF_SRC(fp
->code
) == BPF_K
&& (int) fp
->k
< 0) {
445 /* BPF immediates are signed, zero extend
446 * immediate into tmp register and use it
449 *insn
++ = BPF_MOV32_IMM(BPF_REG_TMP
, fp
->k
);
451 insn
->dst_reg
= BPF_REG_A
;
452 insn
->src_reg
= BPF_REG_TMP
;
455 insn
->dst_reg
= BPF_REG_A
;
456 insn
->src_reg
= BPF_REG_X
;
458 bpf_src
= BPF_SRC(fp
->code
);
461 /* Common case where 'jump_false' is next insn. */
463 insn
->code
= BPF_JMP
| BPF_OP(fp
->code
) | bpf_src
;
464 target
= i
+ fp
->jt
+ 1;
469 /* Convert JEQ into JNE when 'jump_true' is next insn. */
470 if (fp
->jt
== 0 && BPF_OP(fp
->code
) == BPF_JEQ
) {
471 insn
->code
= BPF_JMP
| BPF_JNE
| bpf_src
;
472 target
= i
+ fp
->jf
+ 1;
477 /* Other jumps are mapped into two insns: Jxx and JA. */
478 target
= i
+ fp
->jt
+ 1;
479 insn
->code
= BPF_JMP
| BPF_OP(fp
->code
) | bpf_src
;
483 insn
->code
= BPF_JMP
| BPF_JA
;
484 target
= i
+ fp
->jf
+ 1;
488 /* ldxb 4 * ([14] & 0xf) is remaped into 6 insns. */
489 case BPF_LDX
| BPF_MSH
| BPF_B
:
491 *insn
++ = BPF_MOV64_REG(BPF_REG_TMP
, BPF_REG_A
);
492 /* A = BPF_R0 = *(u8 *) (skb->data + K) */
493 *insn
++ = BPF_LD_ABS(BPF_B
, fp
->k
);
495 *insn
++ = BPF_ALU32_IMM(BPF_AND
, BPF_REG_A
, 0xf);
497 *insn
++ = BPF_ALU32_IMM(BPF_LSH
, BPF_REG_A
, 2);
499 *insn
++ = BPF_MOV64_REG(BPF_REG_X
, BPF_REG_A
);
501 *insn
= BPF_MOV64_REG(BPF_REG_A
, BPF_REG_TMP
);
504 /* RET_K, RET_A are remaped into 2 insns. */
505 case BPF_RET
| BPF_A
:
506 case BPF_RET
| BPF_K
:
507 *insn
++ = BPF_MOV32_RAW(BPF_RVAL(fp
->code
) == BPF_K
?
508 BPF_K
: BPF_X
, BPF_REG_0
,
510 *insn
= BPF_EXIT_INSN();
513 /* Store to stack. */
516 *insn
= BPF_STX_MEM(BPF_W
, BPF_REG_FP
, BPF_CLASS(fp
->code
) ==
517 BPF_ST
? BPF_REG_A
: BPF_REG_X
,
518 -(BPF_MEMWORDS
- fp
->k
) * 4);
521 /* Load from stack. */
522 case BPF_LD
| BPF_MEM
:
523 case BPF_LDX
| BPF_MEM
:
524 *insn
= BPF_LDX_MEM(BPF_W
, BPF_CLASS(fp
->code
) == BPF_LD
?
525 BPF_REG_A
: BPF_REG_X
, BPF_REG_FP
,
526 -(BPF_MEMWORDS
- fp
->k
) * 4);
530 case BPF_LD
| BPF_IMM
:
531 case BPF_LDX
| BPF_IMM
:
532 *insn
= BPF_MOV32_IMM(BPF_CLASS(fp
->code
) == BPF_LD
?
533 BPF_REG_A
: BPF_REG_X
, fp
->k
);
537 case BPF_MISC
| BPF_TAX
:
538 *insn
= BPF_MOV64_REG(BPF_REG_X
, BPF_REG_A
);
542 case BPF_MISC
| BPF_TXA
:
543 *insn
= BPF_MOV64_REG(BPF_REG_A
, BPF_REG_X
);
546 /* A = skb->len or X = skb->len */
547 case BPF_LD
| BPF_W
| BPF_LEN
:
548 case BPF_LDX
| BPF_W
| BPF_LEN
:
549 *insn
= BPF_LDX_MEM(BPF_W
, BPF_CLASS(fp
->code
) == BPF_LD
?
550 BPF_REG_A
: BPF_REG_X
, BPF_REG_CTX
,
551 offsetof(struct sk_buff
, len
));
554 /* Access seccomp_data fields. */
555 case BPF_LDX
| BPF_ABS
| BPF_W
:
556 /* A = *(u32 *) (ctx + K) */
557 *insn
= BPF_LDX_MEM(BPF_W
, BPF_REG_A
, BPF_REG_CTX
, fp
->k
);
560 /* Unkown instruction. */
567 memcpy(new_insn
, tmp_insns
,
568 sizeof(*insn
) * (insn
- tmp_insns
));
569 new_insn
+= insn
- tmp_insns
;
573 /* Only calculating new length. */
574 *new_len
= new_insn
- new_prog
;
579 if (new_flen
!= new_insn
- new_prog
) {
580 new_flen
= new_insn
- new_prog
;
587 BUG_ON(*new_len
!= new_flen
);
596 * A BPF program is able to use 16 cells of memory to store intermediate
597 * values (check u32 mem[BPF_MEMWORDS] in sk_run_filter()).
599 * As we dont want to clear mem[] array for each packet going through
600 * sk_run_filter(), we check that filter loaded by user never try to read
601 * a cell if not previously written, and we check all branches to be sure
602 * a malicious user doesn't try to abuse us.
604 static int check_load_and_stores(const struct sock_filter
*filter
, int flen
)
606 u16
*masks
, memvalid
= 0; /* One bit per cell, 16 cells */
609 BUILD_BUG_ON(BPF_MEMWORDS
> 16);
611 masks
= kmalloc_array(flen
, sizeof(*masks
), GFP_KERNEL
);
615 memset(masks
, 0xff, flen
* sizeof(*masks
));
617 for (pc
= 0; pc
< flen
; pc
++) {
618 memvalid
&= masks
[pc
];
620 switch (filter
[pc
].code
) {
623 memvalid
|= (1 << filter
[pc
].k
);
625 case BPF_LD
| BPF_MEM
:
626 case BPF_LDX
| BPF_MEM
:
627 if (!(memvalid
& (1 << filter
[pc
].k
))) {
632 case BPF_JMP
| BPF_JA
:
633 /* A jump must set masks on target */
634 masks
[pc
+ 1 + filter
[pc
].k
] &= memvalid
;
637 case BPF_JMP
| BPF_JEQ
| BPF_K
:
638 case BPF_JMP
| BPF_JEQ
| BPF_X
:
639 case BPF_JMP
| BPF_JGE
| BPF_K
:
640 case BPF_JMP
| BPF_JGE
| BPF_X
:
641 case BPF_JMP
| BPF_JGT
| BPF_K
:
642 case BPF_JMP
| BPF_JGT
| BPF_X
:
643 case BPF_JMP
| BPF_JSET
| BPF_K
:
644 case BPF_JMP
| BPF_JSET
| BPF_X
:
645 /* A jump must set masks on targets */
646 masks
[pc
+ 1 + filter
[pc
].jt
] &= memvalid
;
647 masks
[pc
+ 1 + filter
[pc
].jf
] &= memvalid
;
657 static bool chk_code_allowed(u16 code_to_probe
)
659 static const bool codes
[] = {
660 /* 32 bit ALU operations */
661 [BPF_ALU
| BPF_ADD
| BPF_K
] = true,
662 [BPF_ALU
| BPF_ADD
| BPF_X
] = true,
663 [BPF_ALU
| BPF_SUB
| BPF_K
] = true,
664 [BPF_ALU
| BPF_SUB
| BPF_X
] = true,
665 [BPF_ALU
| BPF_MUL
| BPF_K
] = true,
666 [BPF_ALU
| BPF_MUL
| BPF_X
] = true,
667 [BPF_ALU
| BPF_DIV
| BPF_K
] = true,
668 [BPF_ALU
| BPF_DIV
| BPF_X
] = true,
669 [BPF_ALU
| BPF_MOD
| BPF_K
] = true,
670 [BPF_ALU
| BPF_MOD
| BPF_X
] = true,
671 [BPF_ALU
| BPF_AND
| BPF_K
] = true,
672 [BPF_ALU
| BPF_AND
| BPF_X
] = true,
673 [BPF_ALU
| BPF_OR
| BPF_K
] = true,
674 [BPF_ALU
| BPF_OR
| BPF_X
] = true,
675 [BPF_ALU
| BPF_XOR
| BPF_K
] = true,
676 [BPF_ALU
| BPF_XOR
| BPF_X
] = true,
677 [BPF_ALU
| BPF_LSH
| BPF_K
] = true,
678 [BPF_ALU
| BPF_LSH
| BPF_X
] = true,
679 [BPF_ALU
| BPF_RSH
| BPF_K
] = true,
680 [BPF_ALU
| BPF_RSH
| BPF_X
] = true,
681 [BPF_ALU
| BPF_NEG
] = true,
682 /* Load instructions */
683 [BPF_LD
| BPF_W
| BPF_ABS
] = true,
684 [BPF_LD
| BPF_H
| BPF_ABS
] = true,
685 [BPF_LD
| BPF_B
| BPF_ABS
] = true,
686 [BPF_LD
| BPF_W
| BPF_LEN
] = true,
687 [BPF_LD
| BPF_W
| BPF_IND
] = true,
688 [BPF_LD
| BPF_H
| BPF_IND
] = true,
689 [BPF_LD
| BPF_B
| BPF_IND
] = true,
690 [BPF_LD
| BPF_IMM
] = true,
691 [BPF_LD
| BPF_MEM
] = true,
692 [BPF_LDX
| BPF_W
| BPF_LEN
] = true,
693 [BPF_LDX
| BPF_B
| BPF_MSH
] = true,
694 [BPF_LDX
| BPF_IMM
] = true,
695 [BPF_LDX
| BPF_MEM
] = true,
696 /* Store instructions */
699 /* Misc instructions */
700 [BPF_MISC
| BPF_TAX
] = true,
701 [BPF_MISC
| BPF_TXA
] = true,
702 /* Return instructions */
703 [BPF_RET
| BPF_K
] = true,
704 [BPF_RET
| BPF_A
] = true,
705 /* Jump instructions */
706 [BPF_JMP
| BPF_JA
] = true,
707 [BPF_JMP
| BPF_JEQ
| BPF_K
] = true,
708 [BPF_JMP
| BPF_JEQ
| BPF_X
] = true,
709 [BPF_JMP
| BPF_JGE
| BPF_K
] = true,
710 [BPF_JMP
| BPF_JGE
| BPF_X
] = true,
711 [BPF_JMP
| BPF_JGT
| BPF_K
] = true,
712 [BPF_JMP
| BPF_JGT
| BPF_X
] = true,
713 [BPF_JMP
| BPF_JSET
| BPF_K
] = true,
714 [BPF_JMP
| BPF_JSET
| BPF_X
] = true,
717 if (code_to_probe
>= ARRAY_SIZE(codes
))
720 return codes
[code_to_probe
];
724 * bpf_check_classic - verify socket filter code
725 * @filter: filter to verify
726 * @flen: length of filter
728 * Check the user's filter code. If we let some ugly
729 * filter code slip through kaboom! The filter must contain
730 * no references or jumps that are out of range, no illegal
731 * instructions, and must end with a RET instruction.
733 * All jumps are forward as they are not signed.
735 * Returns 0 if the rule set is legal or -EINVAL if not.
737 int bpf_check_classic(const struct sock_filter
*filter
, unsigned int flen
)
742 if (flen
== 0 || flen
> BPF_MAXINSNS
)
745 /* Check the filter code now */
746 for (pc
= 0; pc
< flen
; pc
++) {
747 const struct sock_filter
*ftest
= &filter
[pc
];
749 /* May we actually operate on this code? */
750 if (!chk_code_allowed(ftest
->code
))
753 /* Some instructions need special checks */
754 switch (ftest
->code
) {
755 case BPF_ALU
| BPF_DIV
| BPF_K
:
756 case BPF_ALU
| BPF_MOD
| BPF_K
:
757 /* Check for division by zero */
761 case BPF_LD
| BPF_MEM
:
762 case BPF_LDX
| BPF_MEM
:
765 /* Check for invalid memory addresses */
766 if (ftest
->k
>= BPF_MEMWORDS
)
769 case BPF_JMP
| BPF_JA
:
770 /* Note, the large ftest->k might cause loops.
771 * Compare this with conditional jumps below,
772 * where offsets are limited. --ANK (981016)
774 if (ftest
->k
>= (unsigned int)(flen
- pc
- 1))
777 case BPF_JMP
| BPF_JEQ
| BPF_K
:
778 case BPF_JMP
| BPF_JEQ
| BPF_X
:
779 case BPF_JMP
| BPF_JGE
| BPF_K
:
780 case BPF_JMP
| BPF_JGE
| BPF_X
:
781 case BPF_JMP
| BPF_JGT
| BPF_K
:
782 case BPF_JMP
| BPF_JGT
| BPF_X
:
783 case BPF_JMP
| BPF_JSET
| BPF_K
:
784 case BPF_JMP
| BPF_JSET
| BPF_X
:
785 /* Both conditionals must be safe */
786 if (pc
+ ftest
->jt
+ 1 >= flen
||
787 pc
+ ftest
->jf
+ 1 >= flen
)
790 case BPF_LD
| BPF_W
| BPF_ABS
:
791 case BPF_LD
| BPF_H
| BPF_ABS
:
792 case BPF_LD
| BPF_B
| BPF_ABS
:
794 if (bpf_anc_helper(ftest
) & BPF_ANC
)
796 /* Ancillary operation unknown or unsupported */
797 if (anc_found
== false && ftest
->k
>= SKF_AD_OFF
)
802 /* Last instruction must be a RET code */
803 switch (filter
[flen
- 1].code
) {
804 case BPF_RET
| BPF_K
:
805 case BPF_RET
| BPF_A
:
806 return check_load_and_stores(filter
, flen
);
811 EXPORT_SYMBOL(bpf_check_classic
);
813 static int bpf_prog_store_orig_filter(struct bpf_prog
*fp
,
814 const struct sock_fprog
*fprog
)
816 unsigned int fsize
= bpf_classic_proglen(fprog
);
817 struct sock_fprog_kern
*fkprog
;
819 fp
->orig_prog
= kmalloc(sizeof(*fkprog
), GFP_KERNEL
);
823 fkprog
= fp
->orig_prog
;
824 fkprog
->len
= fprog
->len
;
825 fkprog
->filter
= kmemdup(fp
->insns
, fsize
, GFP_KERNEL
);
826 if (!fkprog
->filter
) {
827 kfree(fp
->orig_prog
);
834 static void bpf_release_orig_filter(struct bpf_prog
*fp
)
836 struct sock_fprog_kern
*fprog
= fp
->orig_prog
;
839 kfree(fprog
->filter
);
844 static void __bpf_prog_release(struct bpf_prog
*prog
)
846 bpf_release_orig_filter(prog
);
850 static void __sk_filter_release(struct sk_filter
*fp
)
852 __bpf_prog_release(fp
->prog
);
857 * sk_filter_release_rcu - Release a socket filter by rcu_head
858 * @rcu: rcu_head that contains the sk_filter to free
860 static void sk_filter_release_rcu(struct rcu_head
*rcu
)
862 struct sk_filter
*fp
= container_of(rcu
, struct sk_filter
, rcu
);
864 __sk_filter_release(fp
);
868 * sk_filter_release - release a socket filter
869 * @fp: filter to remove
871 * Remove a filter from a socket and release its resources.
873 static void sk_filter_release(struct sk_filter
*fp
)
875 if (atomic_dec_and_test(&fp
->refcnt
))
876 call_rcu(&fp
->rcu
, sk_filter_release_rcu
);
879 void sk_filter_uncharge(struct sock
*sk
, struct sk_filter
*fp
)
881 u32 filter_size
= bpf_prog_size(fp
->prog
->len
);
883 atomic_sub(filter_size
, &sk
->sk_omem_alloc
);
884 sk_filter_release(fp
);
887 /* try to charge the socket memory if there is space available
888 * return true on success
890 bool sk_filter_charge(struct sock
*sk
, struct sk_filter
*fp
)
892 u32 filter_size
= bpf_prog_size(fp
->prog
->len
);
894 /* same check as in sock_kmalloc() */
895 if (filter_size
<= sysctl_optmem_max
&&
896 atomic_read(&sk
->sk_omem_alloc
) + filter_size
< sysctl_optmem_max
) {
897 atomic_inc(&fp
->refcnt
);
898 atomic_add(filter_size
, &sk
->sk_omem_alloc
);
904 static struct bpf_prog
*bpf_migrate_filter(struct bpf_prog
*fp
)
906 struct sock_filter
*old_prog
;
907 struct bpf_prog
*old_fp
;
908 int err
, new_len
, old_len
= fp
->len
;
910 /* We are free to overwrite insns et al right here as it
911 * won't be used at this point in time anymore internally
912 * after the migration to the internal BPF instruction
915 BUILD_BUG_ON(sizeof(struct sock_filter
) !=
916 sizeof(struct bpf_insn
));
918 /* Conversion cannot happen on overlapping memory areas,
919 * so we need to keep the user BPF around until the 2nd
920 * pass. At this time, the user BPF is stored in fp->insns.
922 old_prog
= kmemdup(fp
->insns
, old_len
* sizeof(struct sock_filter
),
929 /* 1st pass: calculate the new program length. */
930 err
= bpf_convert_filter(old_prog
, old_len
, NULL
, &new_len
);
934 /* Expand fp for appending the new filter representation. */
936 fp
= krealloc(old_fp
, bpf_prog_size(new_len
), GFP_KERNEL
);
938 /* The old_fp is still around in case we couldn't
939 * allocate new memory, so uncharge on that one.
948 /* 2nd pass: remap sock_filter insns into bpf_insn insns. */
949 err
= bpf_convert_filter(old_prog
, old_len
, fp
->insnsi
, &new_len
);
951 /* 2nd bpf_convert_filter() can fail only if it fails
952 * to allocate memory, remapping must succeed. Note,
953 * that at this time old_fp has already been released
958 bpf_prog_select_runtime(fp
);
966 __bpf_prog_release(fp
);
970 static struct bpf_prog
*bpf_prepare_filter(struct bpf_prog
*fp
)
977 err
= bpf_check_classic(fp
->insns
, fp
->len
);
979 __bpf_prog_release(fp
);
983 /* Probe if we can JIT compile the filter and if so, do
984 * the compilation of the filter.
988 /* JIT compiler couldn't process this filter, so do the
989 * internal BPF translation for the optimized interpreter.
992 fp
= bpf_migrate_filter(fp
);
998 * bpf_prog_create - create an unattached filter
999 * @pfp: the unattached filter that is created
1000 * @fprog: the filter program
1002 * Create a filter independent of any socket. We first run some
1003 * sanity checks on it to make sure it does not explode on us later.
1004 * If an error occurs or there is insufficient memory for the filter
1005 * a negative errno code is returned. On success the return is zero.
1007 int bpf_prog_create(struct bpf_prog
**pfp
, struct sock_fprog_kern
*fprog
)
1009 unsigned int fsize
= bpf_classic_proglen(fprog
);
1010 struct bpf_prog
*fp
;
1012 /* Make sure new filter is there and in the right amounts. */
1013 if (fprog
->filter
== NULL
)
1016 fp
= kmalloc(bpf_prog_size(fprog
->len
), GFP_KERNEL
);
1020 memcpy(fp
->insns
, fprog
->filter
, fsize
);
1022 fp
->len
= fprog
->len
;
1023 /* Since unattached filters are not copied back to user
1024 * space through sk_get_filter(), we do not need to hold
1025 * a copy here, and can spare us the work.
1027 fp
->orig_prog
= NULL
;
1029 /* bpf_prepare_filter() already takes care of freeing
1030 * memory in case something goes wrong.
1032 fp
= bpf_prepare_filter(fp
);
1039 EXPORT_SYMBOL_GPL(bpf_prog_create
);
1041 void bpf_prog_destroy(struct bpf_prog
*fp
)
1043 __bpf_prog_release(fp
);
1045 EXPORT_SYMBOL_GPL(bpf_prog_destroy
);
1048 * sk_attach_filter - attach a socket filter
1049 * @fprog: the filter program
1050 * @sk: the socket to use
1052 * Attach the user's filter code. We first run some sanity checks on
1053 * it to make sure it does not explode on us later. If an error
1054 * occurs or there is insufficient memory for the filter a negative
1055 * errno code is returned. On success the return is zero.
1057 int sk_attach_filter(struct sock_fprog
*fprog
, struct sock
*sk
)
1059 struct sk_filter
*fp
, *old_fp
;
1060 unsigned int fsize
= bpf_classic_proglen(fprog
);
1061 unsigned int bpf_fsize
= bpf_prog_size(fprog
->len
);
1062 struct bpf_prog
*prog
;
1065 if (sock_flag(sk
, SOCK_FILTER_LOCKED
))
1068 /* Make sure new filter is there and in the right amounts. */
1069 if (fprog
->filter
== NULL
)
1072 prog
= kmalloc(bpf_fsize
, GFP_KERNEL
);
1076 if (copy_from_user(prog
->insns
, fprog
->filter
, fsize
)) {
1081 prog
->len
= fprog
->len
;
1083 err
= bpf_prog_store_orig_filter(prog
, fprog
);
1089 /* bpf_prepare_filter() already takes care of freeing
1090 * memory in case something goes wrong.
1092 prog
= bpf_prepare_filter(prog
);
1094 return PTR_ERR(prog
);
1096 fp
= kmalloc(sizeof(*fp
), GFP_KERNEL
);
1098 __bpf_prog_release(prog
);
1103 atomic_set(&fp
->refcnt
, 0);
1105 if (!sk_filter_charge(sk
, fp
)) {
1106 __sk_filter_release(fp
);
1110 old_fp
= rcu_dereference_protected(sk
->sk_filter
,
1111 sock_owned_by_user(sk
));
1112 rcu_assign_pointer(sk
->sk_filter
, fp
);
1115 sk_filter_uncharge(sk
, old_fp
);
1119 EXPORT_SYMBOL_GPL(sk_attach_filter
);
1121 int sk_detach_filter(struct sock
*sk
)
1124 struct sk_filter
*filter
;
1126 if (sock_flag(sk
, SOCK_FILTER_LOCKED
))
1129 filter
= rcu_dereference_protected(sk
->sk_filter
,
1130 sock_owned_by_user(sk
));
1132 RCU_INIT_POINTER(sk
->sk_filter
, NULL
);
1133 sk_filter_uncharge(sk
, filter
);
1139 EXPORT_SYMBOL_GPL(sk_detach_filter
);
1141 int sk_get_filter(struct sock
*sk
, struct sock_filter __user
*ubuf
,
1144 struct sock_fprog_kern
*fprog
;
1145 struct sk_filter
*filter
;
1149 filter
= rcu_dereference_protected(sk
->sk_filter
,
1150 sock_owned_by_user(sk
));
1154 /* We're copying the filter that has been originally attached,
1155 * so no conversion/decode needed anymore.
1157 fprog
= filter
->prog
->orig_prog
;
1161 /* User space only enquires number of filter blocks. */
1165 if (len
< fprog
->len
)
1169 if (copy_to_user(ubuf
, fprog
->filter
, bpf_classic_proglen(fprog
)))
1172 /* Instead of bytes, the API requests to return the number
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