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Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * Linux Socket Filter - Kernel level socket filtering | |
3 | * | |
bd4cf0ed AS |
4 | * Based on the design of the Berkeley Packet Filter. The new |
5 | * internal format has been designed by PLUMgrid: | |
1da177e4 | 6 | * |
bd4cf0ed AS |
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> | |
1da177e4 LT |
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. | |
4df95ff4 | 21 | * Kris Katterjohn - Added many additional checks in bpf_check_classic() |
1da177e4 LT |
22 | */ |
23 | ||
24 | #include <linux/module.h> | |
25 | #include <linux/types.h> | |
1da177e4 LT |
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> | |
5a0e3ad6 | 33 | #include <linux/gfp.h> |
1da177e4 LT |
34 | #include <net/ip.h> |
35 | #include <net/protocol.h> | |
4738c1db | 36 | #include <net/netlink.h> |
1da177e4 LT |
37 | #include <linux/skbuff.h> |
38 | #include <net/sock.h> | |
39 | #include <linux/errno.h> | |
40 | #include <linux/timer.h> | |
1da177e4 | 41 | #include <asm/uaccess.h> |
40daafc8 | 42 | #include <asm/unaligned.h> |
1da177e4 | 43 | #include <linux/filter.h> |
86e4ca66 | 44 | #include <linux/ratelimit.h> |
46b325c7 | 45 | #include <linux/seccomp.h> |
f3335031 | 46 | #include <linux/if_vlan.h> |
89aa0758 | 47 | #include <linux/bpf.h> |
1da177e4 | 48 | |
43db6d65 SH |
49 | /** |
50 | * sk_filter - run a packet through a socket filter | |
51 | * @sk: sock associated with &sk_buff | |
52 | * @skb: buffer to filter | |
43db6d65 SH |
53 | * |
54 | * Run the filter code and then cut skb->data to correct size returned by | |
8ea6e345 | 55 | * SK_RUN_FILTER. If pkt_len is 0 we toss packet. If skb->len is smaller |
43db6d65 | 56 | * than pkt_len we keep whole skb->data. This is the socket level |
8ea6e345 | 57 | * wrapper to SK_RUN_FILTER. It returns 0 if the packet should |
43db6d65 SH |
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 | ||
c93bdd0e MG |
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 | ||
43db6d65 SH |
74 | err = security_sock_rcv_skb(sk, skb); |
75 | if (err) | |
76 | return err; | |
77 | ||
80f8f102 ED |
78 | rcu_read_lock(); |
79 | filter = rcu_dereference(sk->sk_filter); | |
43db6d65 | 80 | if (filter) { |
0a14842f | 81 | unsigned int pkt_len = SK_RUN_FILTER(filter, skb); |
0d7da9dd | 82 | |
43db6d65 SH |
83 | err = pkt_len ? pskb_trim(skb, pkt_len) : -EPERM; |
84 | } | |
80f8f102 | 85 | rcu_read_unlock(); |
43db6d65 SH |
86 | |
87 | return err; | |
88 | } | |
89 | EXPORT_SYMBOL(sk_filter); | |
90 | ||
30743837 | 91 | static u64 __skb_get_pay_offset(u64 ctx, u64 a, u64 x, u64 r4, u64 r5) |
bd4cf0ed | 92 | { |
56193d1b | 93 | return skb_get_poff((struct sk_buff *)(unsigned long) ctx); |
bd4cf0ed AS |
94 | } |
95 | ||
30743837 | 96 | static u64 __skb_get_nlattr(u64 ctx, u64 a, u64 x, u64 r4, u64 r5) |
bd4cf0ed | 97 | { |
eb9672f4 | 98 | struct sk_buff *skb = (struct sk_buff *)(unsigned long) ctx; |
bd4cf0ed AS |
99 | struct nlattr *nla; |
100 | ||
101 | if (skb_is_nonlinear(skb)) | |
102 | return 0; | |
103 | ||
05ab8f26 MK |
104 | if (skb->len < sizeof(struct nlattr)) |
105 | return 0; | |
106 | ||
30743837 | 107 | if (a > skb->len - sizeof(struct nlattr)) |
bd4cf0ed AS |
108 | return 0; |
109 | ||
30743837 | 110 | nla = nla_find((struct nlattr *) &skb->data[a], skb->len - a, x); |
bd4cf0ed AS |
111 | if (nla) |
112 | return (void *) nla - (void *) skb->data; | |
113 | ||
114 | return 0; | |
115 | } | |
116 | ||
30743837 | 117 | static u64 __skb_get_nlattr_nest(u64 ctx, u64 a, u64 x, u64 r4, u64 r5) |
bd4cf0ed | 118 | { |
eb9672f4 | 119 | struct sk_buff *skb = (struct sk_buff *)(unsigned long) ctx; |
bd4cf0ed AS |
120 | struct nlattr *nla; |
121 | ||
122 | if (skb_is_nonlinear(skb)) | |
123 | return 0; | |
124 | ||
05ab8f26 MK |
125 | if (skb->len < sizeof(struct nlattr)) |
126 | return 0; | |
127 | ||
30743837 | 128 | if (a > skb->len - sizeof(struct nlattr)) |
bd4cf0ed AS |
129 | return 0; |
130 | ||
30743837 DB |
131 | nla = (struct nlattr *) &skb->data[a]; |
132 | if (nla->nla_len > skb->len - a) | |
bd4cf0ed AS |
133 | return 0; |
134 | ||
30743837 | 135 | nla = nla_find_nested(nla, x); |
bd4cf0ed AS |
136 | if (nla) |
137 | return (void *) nla - (void *) skb->data; | |
138 | ||
139 | return 0; | |
140 | } | |
141 | ||
30743837 | 142 | static u64 __get_raw_cpu_id(u64 ctx, u64 a, u64 x, u64 r4, u64 r5) |
bd4cf0ed AS |
143 | { |
144 | return raw_smp_processor_id(); | |
145 | } | |
146 | ||
4cd3675e | 147 | /* note that this only generates 32-bit random numbers */ |
30743837 | 148 | static u64 __get_random_u32(u64 ctx, u64 a, u64 x, u64 r4, u64 r5) |
4cd3675e | 149 | { |
eb9672f4 | 150 | return prandom_u32(); |
4cd3675e CG |
151 | } |
152 | ||
9bac3d6d AS |
153 | static u32 convert_skb_access(int skb_field, int dst_reg, int src_reg, |
154 | struct bpf_insn *insn_buf) | |
155 | { | |
156 | struct bpf_insn *insn = insn_buf; | |
157 | ||
158 | switch (skb_field) { | |
159 | case SKF_AD_MARK: | |
160 | BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, mark) != 4); | |
161 | ||
162 | *insn++ = BPF_LDX_MEM(BPF_W, dst_reg, src_reg, | |
163 | offsetof(struct sk_buff, mark)); | |
164 | break; | |
165 | ||
166 | case SKF_AD_PKTTYPE: | |
167 | *insn++ = BPF_LDX_MEM(BPF_B, dst_reg, src_reg, PKT_TYPE_OFFSET()); | |
168 | *insn++ = BPF_ALU32_IMM(BPF_AND, dst_reg, PKT_TYPE_MAX); | |
169 | #ifdef __BIG_ENDIAN_BITFIELD | |
170 | *insn++ = BPF_ALU32_IMM(BPF_RSH, dst_reg, 5); | |
171 | #endif | |
172 | break; | |
173 | ||
174 | case SKF_AD_QUEUE: | |
175 | BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, queue_mapping) != 2); | |
176 | ||
177 | *insn++ = BPF_LDX_MEM(BPF_H, dst_reg, src_reg, | |
178 | offsetof(struct sk_buff, queue_mapping)); | |
179 | break; | |
c2497395 | 180 | |
c2497395 AS |
181 | case SKF_AD_VLAN_TAG: |
182 | case SKF_AD_VLAN_TAG_PRESENT: | |
183 | BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, vlan_tci) != 2); | |
184 | BUILD_BUG_ON(VLAN_TAG_PRESENT != 0x1000); | |
185 | ||
186 | /* dst_reg = *(u16 *) (src_reg + offsetof(vlan_tci)) */ | |
187 | *insn++ = BPF_LDX_MEM(BPF_H, dst_reg, src_reg, | |
188 | offsetof(struct sk_buff, vlan_tci)); | |
189 | if (skb_field == SKF_AD_VLAN_TAG) { | |
190 | *insn++ = BPF_ALU32_IMM(BPF_AND, dst_reg, | |
191 | ~VLAN_TAG_PRESENT); | |
192 | } else { | |
193 | /* dst_reg >>= 12 */ | |
194 | *insn++ = BPF_ALU32_IMM(BPF_RSH, dst_reg, 12); | |
195 | /* dst_reg &= 1 */ | |
196 | *insn++ = BPF_ALU32_IMM(BPF_AND, dst_reg, 1); | |
197 | } | |
198 | break; | |
9bac3d6d AS |
199 | } |
200 | ||
201 | return insn - insn_buf; | |
202 | } | |
203 | ||
bd4cf0ed | 204 | static bool convert_bpf_extensions(struct sock_filter *fp, |
2695fb55 | 205 | struct bpf_insn **insnp) |
bd4cf0ed | 206 | { |
2695fb55 | 207 | struct bpf_insn *insn = *insnp; |
9bac3d6d | 208 | u32 cnt; |
bd4cf0ed AS |
209 | |
210 | switch (fp->k) { | |
211 | case SKF_AD_OFF + SKF_AD_PROTOCOL: | |
0b8c707d DB |
212 | BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, protocol) != 2); |
213 | ||
214 | /* A = *(u16 *) (CTX + offsetof(protocol)) */ | |
215 | *insn++ = BPF_LDX_MEM(BPF_H, BPF_REG_A, BPF_REG_CTX, | |
216 | offsetof(struct sk_buff, protocol)); | |
217 | /* A = ntohs(A) [emitting a nop or swap16] */ | |
218 | *insn = BPF_ENDIAN(BPF_FROM_BE, BPF_REG_A, 16); | |
bd4cf0ed AS |
219 | break; |
220 | ||
221 | case SKF_AD_OFF + SKF_AD_PKTTYPE: | |
9bac3d6d AS |
222 | cnt = convert_skb_access(SKF_AD_PKTTYPE, BPF_REG_A, BPF_REG_CTX, insn); |
223 | insn += cnt - 1; | |
bd4cf0ed AS |
224 | break; |
225 | ||
226 | case SKF_AD_OFF + SKF_AD_IFINDEX: | |
227 | case SKF_AD_OFF + SKF_AD_HATYPE: | |
bd4cf0ed AS |
228 | BUILD_BUG_ON(FIELD_SIZEOF(struct net_device, ifindex) != 4); |
229 | BUILD_BUG_ON(FIELD_SIZEOF(struct net_device, type) != 2); | |
f8f6d679 DB |
230 | BUILD_BUG_ON(bytes_to_bpf_size(FIELD_SIZEOF(struct sk_buff, dev)) < 0); |
231 | ||
232 | *insn++ = BPF_LDX_MEM(bytes_to_bpf_size(FIELD_SIZEOF(struct sk_buff, dev)), | |
233 | BPF_REG_TMP, BPF_REG_CTX, | |
234 | offsetof(struct sk_buff, dev)); | |
235 | /* if (tmp != 0) goto pc + 1 */ | |
236 | *insn++ = BPF_JMP_IMM(BPF_JNE, BPF_REG_TMP, 0, 1); | |
237 | *insn++ = BPF_EXIT_INSN(); | |
238 | if (fp->k == SKF_AD_OFF + SKF_AD_IFINDEX) | |
239 | *insn = BPF_LDX_MEM(BPF_W, BPF_REG_A, BPF_REG_TMP, | |
240 | offsetof(struct net_device, ifindex)); | |
241 | else | |
242 | *insn = BPF_LDX_MEM(BPF_H, BPF_REG_A, BPF_REG_TMP, | |
243 | offsetof(struct net_device, type)); | |
bd4cf0ed AS |
244 | break; |
245 | ||
246 | case SKF_AD_OFF + SKF_AD_MARK: | |
9bac3d6d AS |
247 | cnt = convert_skb_access(SKF_AD_MARK, BPF_REG_A, BPF_REG_CTX, insn); |
248 | insn += cnt - 1; | |
bd4cf0ed AS |
249 | break; |
250 | ||
251 | case SKF_AD_OFF + SKF_AD_RXHASH: | |
252 | BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, hash) != 4); | |
253 | ||
9739eef1 AS |
254 | *insn = BPF_LDX_MEM(BPF_W, BPF_REG_A, BPF_REG_CTX, |
255 | offsetof(struct sk_buff, hash)); | |
bd4cf0ed AS |
256 | break; |
257 | ||
258 | case SKF_AD_OFF + SKF_AD_QUEUE: | |
9bac3d6d AS |
259 | cnt = convert_skb_access(SKF_AD_QUEUE, BPF_REG_A, BPF_REG_CTX, insn); |
260 | insn += cnt - 1; | |
bd4cf0ed AS |
261 | break; |
262 | ||
263 | case SKF_AD_OFF + SKF_AD_VLAN_TAG: | |
c2497395 AS |
264 | cnt = convert_skb_access(SKF_AD_VLAN_TAG, |
265 | BPF_REG_A, BPF_REG_CTX, insn); | |
266 | insn += cnt - 1; | |
267 | break; | |
bd4cf0ed | 268 | |
c2497395 AS |
269 | case SKF_AD_OFF + SKF_AD_VLAN_TAG_PRESENT: |
270 | cnt = convert_skb_access(SKF_AD_VLAN_TAG_PRESENT, | |
271 | BPF_REG_A, BPF_REG_CTX, insn); | |
272 | insn += cnt - 1; | |
bd4cf0ed AS |
273 | break; |
274 | ||
275 | case SKF_AD_OFF + SKF_AD_PAY_OFFSET: | |
276 | case SKF_AD_OFF + SKF_AD_NLATTR: | |
277 | case SKF_AD_OFF + SKF_AD_NLATTR_NEST: | |
278 | case SKF_AD_OFF + SKF_AD_CPU: | |
4cd3675e | 279 | case SKF_AD_OFF + SKF_AD_RANDOM: |
e430f34e | 280 | /* arg1 = CTX */ |
f8f6d679 | 281 | *insn++ = BPF_MOV64_REG(BPF_REG_ARG1, BPF_REG_CTX); |
bd4cf0ed | 282 | /* arg2 = A */ |
f8f6d679 | 283 | *insn++ = BPF_MOV64_REG(BPF_REG_ARG2, BPF_REG_A); |
bd4cf0ed | 284 | /* arg3 = X */ |
f8f6d679 | 285 | *insn++ = BPF_MOV64_REG(BPF_REG_ARG3, BPF_REG_X); |
e430f34e | 286 | /* Emit call(arg1=CTX, arg2=A, arg3=X) */ |
bd4cf0ed AS |
287 | switch (fp->k) { |
288 | case SKF_AD_OFF + SKF_AD_PAY_OFFSET: | |
f8f6d679 | 289 | *insn = BPF_EMIT_CALL(__skb_get_pay_offset); |
bd4cf0ed AS |
290 | break; |
291 | case SKF_AD_OFF + SKF_AD_NLATTR: | |
f8f6d679 | 292 | *insn = BPF_EMIT_CALL(__skb_get_nlattr); |
bd4cf0ed AS |
293 | break; |
294 | case SKF_AD_OFF + SKF_AD_NLATTR_NEST: | |
f8f6d679 | 295 | *insn = BPF_EMIT_CALL(__skb_get_nlattr_nest); |
bd4cf0ed AS |
296 | break; |
297 | case SKF_AD_OFF + SKF_AD_CPU: | |
f8f6d679 | 298 | *insn = BPF_EMIT_CALL(__get_raw_cpu_id); |
bd4cf0ed | 299 | break; |
4cd3675e | 300 | case SKF_AD_OFF + SKF_AD_RANDOM: |
f8f6d679 | 301 | *insn = BPF_EMIT_CALL(__get_random_u32); |
4cd3675e | 302 | break; |
bd4cf0ed AS |
303 | } |
304 | break; | |
305 | ||
306 | case SKF_AD_OFF + SKF_AD_ALU_XOR_X: | |
9739eef1 AS |
307 | /* A ^= X */ |
308 | *insn = BPF_ALU32_REG(BPF_XOR, BPF_REG_A, BPF_REG_X); | |
bd4cf0ed AS |
309 | break; |
310 | ||
311 | default: | |
312 | /* This is just a dummy call to avoid letting the compiler | |
313 | * evict __bpf_call_base() as an optimization. Placed here | |
314 | * where no-one bothers. | |
315 | */ | |
316 | BUG_ON(__bpf_call_base(0, 0, 0, 0, 0) != 0); | |
317 | return false; | |
318 | } | |
319 | ||
320 | *insnp = insn; | |
321 | return true; | |
322 | } | |
323 | ||
324 | /** | |
8fb575ca | 325 | * bpf_convert_filter - convert filter program |
bd4cf0ed AS |
326 | * @prog: the user passed filter program |
327 | * @len: the length of the user passed filter program | |
328 | * @new_prog: buffer where converted program will be stored | |
329 | * @new_len: pointer to store length of converted program | |
330 | * | |
331 | * Remap 'sock_filter' style BPF instruction set to 'sock_filter_ext' style. | |
332 | * Conversion workflow: | |
333 | * | |
334 | * 1) First pass for calculating the new program length: | |
8fb575ca | 335 | * bpf_convert_filter(old_prog, old_len, NULL, &new_len) |
bd4cf0ed AS |
336 | * |
337 | * 2) 2nd pass to remap in two passes: 1st pass finds new | |
338 | * jump offsets, 2nd pass remapping: | |
2695fb55 | 339 | * new_prog = kmalloc(sizeof(struct bpf_insn) * new_len); |
8fb575ca | 340 | * bpf_convert_filter(old_prog, old_len, new_prog, &new_len); |
bd4cf0ed AS |
341 | * |
342 | * User BPF's register A is mapped to our BPF register 6, user BPF | |
343 | * register X is mapped to BPF register 7; frame pointer is always | |
344 | * register 10; Context 'void *ctx' is stored in register 1, that is, | |
345 | * for socket filters: ctx == 'struct sk_buff *', for seccomp: | |
346 | * ctx == 'struct seccomp_data *'. | |
347 | */ | |
8fb575ca AS |
348 | int bpf_convert_filter(struct sock_filter *prog, int len, |
349 | struct bpf_insn *new_prog, int *new_len) | |
bd4cf0ed AS |
350 | { |
351 | int new_flen = 0, pass = 0, target, i; | |
2695fb55 | 352 | struct bpf_insn *new_insn; |
bd4cf0ed AS |
353 | struct sock_filter *fp; |
354 | int *addrs = NULL; | |
355 | u8 bpf_src; | |
356 | ||
357 | BUILD_BUG_ON(BPF_MEMWORDS * sizeof(u32) > MAX_BPF_STACK); | |
30743837 | 358 | BUILD_BUG_ON(BPF_REG_FP + 1 != MAX_BPF_REG); |
bd4cf0ed | 359 | |
6f9a093b | 360 | if (len <= 0 || len > BPF_MAXINSNS) |
bd4cf0ed AS |
361 | return -EINVAL; |
362 | ||
363 | if (new_prog) { | |
99e72a0f | 364 | addrs = kcalloc(len, sizeof(*addrs), GFP_KERNEL); |
bd4cf0ed AS |
365 | if (!addrs) |
366 | return -ENOMEM; | |
367 | } | |
368 | ||
369 | do_pass: | |
370 | new_insn = new_prog; | |
371 | fp = prog; | |
372 | ||
f8f6d679 DB |
373 | if (new_insn) |
374 | *new_insn = BPF_MOV64_REG(BPF_REG_CTX, BPF_REG_ARG1); | |
bd4cf0ed AS |
375 | new_insn++; |
376 | ||
377 | for (i = 0; i < len; fp++, i++) { | |
2695fb55 AS |
378 | struct bpf_insn tmp_insns[6] = { }; |
379 | struct bpf_insn *insn = tmp_insns; | |
bd4cf0ed AS |
380 | |
381 | if (addrs) | |
382 | addrs[i] = new_insn - new_prog; | |
383 | ||
384 | switch (fp->code) { | |
385 | /* All arithmetic insns and skb loads map as-is. */ | |
386 | case BPF_ALU | BPF_ADD | BPF_X: | |
387 | case BPF_ALU | BPF_ADD | BPF_K: | |
388 | case BPF_ALU | BPF_SUB | BPF_X: | |
389 | case BPF_ALU | BPF_SUB | BPF_K: | |
390 | case BPF_ALU | BPF_AND | BPF_X: | |
391 | case BPF_ALU | BPF_AND | BPF_K: | |
392 | case BPF_ALU | BPF_OR | BPF_X: | |
393 | case BPF_ALU | BPF_OR | BPF_K: | |
394 | case BPF_ALU | BPF_LSH | BPF_X: | |
395 | case BPF_ALU | BPF_LSH | BPF_K: | |
396 | case BPF_ALU | BPF_RSH | BPF_X: | |
397 | case BPF_ALU | BPF_RSH | BPF_K: | |
398 | case BPF_ALU | BPF_XOR | BPF_X: | |
399 | case BPF_ALU | BPF_XOR | BPF_K: | |
400 | case BPF_ALU | BPF_MUL | BPF_X: | |
401 | case BPF_ALU | BPF_MUL | BPF_K: | |
402 | case BPF_ALU | BPF_DIV | BPF_X: | |
403 | case BPF_ALU | BPF_DIV | BPF_K: | |
404 | case BPF_ALU | BPF_MOD | BPF_X: | |
405 | case BPF_ALU | BPF_MOD | BPF_K: | |
406 | case BPF_ALU | BPF_NEG: | |
407 | case BPF_LD | BPF_ABS | BPF_W: | |
408 | case BPF_LD | BPF_ABS | BPF_H: | |
409 | case BPF_LD | BPF_ABS | BPF_B: | |
410 | case BPF_LD | BPF_IND | BPF_W: | |
411 | case BPF_LD | BPF_IND | BPF_H: | |
412 | case BPF_LD | BPF_IND | BPF_B: | |
413 | /* Check for overloaded BPF extension and | |
414 | * directly convert it if found, otherwise | |
415 | * just move on with mapping. | |
416 | */ | |
417 | if (BPF_CLASS(fp->code) == BPF_LD && | |
418 | BPF_MODE(fp->code) == BPF_ABS && | |
419 | convert_bpf_extensions(fp, &insn)) | |
420 | break; | |
421 | ||
f8f6d679 | 422 | *insn = BPF_RAW_INSN(fp->code, BPF_REG_A, BPF_REG_X, 0, fp->k); |
bd4cf0ed AS |
423 | break; |
424 | ||
f8f6d679 DB |
425 | /* Jump transformation cannot use BPF block macros |
426 | * everywhere as offset calculation and target updates | |
427 | * require a bit more work than the rest, i.e. jump | |
428 | * opcodes map as-is, but offsets need adjustment. | |
429 | */ | |
430 | ||
431 | #define BPF_EMIT_JMP \ | |
bd4cf0ed AS |
432 | do { \ |
433 | if (target >= len || target < 0) \ | |
434 | goto err; \ | |
435 | insn->off = addrs ? addrs[target] - addrs[i] - 1 : 0; \ | |
436 | /* Adjust pc relative offset for 2nd or 3rd insn. */ \ | |
437 | insn->off -= insn - tmp_insns; \ | |
438 | } while (0) | |
439 | ||
f8f6d679 DB |
440 | case BPF_JMP | BPF_JA: |
441 | target = i + fp->k + 1; | |
442 | insn->code = fp->code; | |
443 | BPF_EMIT_JMP; | |
bd4cf0ed AS |
444 | break; |
445 | ||
446 | case BPF_JMP | BPF_JEQ | BPF_K: | |
447 | case BPF_JMP | BPF_JEQ | BPF_X: | |
448 | case BPF_JMP | BPF_JSET | BPF_K: | |
449 | case BPF_JMP | BPF_JSET | BPF_X: | |
450 | case BPF_JMP | BPF_JGT | BPF_K: | |
451 | case BPF_JMP | BPF_JGT | BPF_X: | |
452 | case BPF_JMP | BPF_JGE | BPF_K: | |
453 | case BPF_JMP | BPF_JGE | BPF_X: | |
454 | if (BPF_SRC(fp->code) == BPF_K && (int) fp->k < 0) { | |
455 | /* BPF immediates are signed, zero extend | |
456 | * immediate into tmp register and use it | |
457 | * in compare insn. | |
458 | */ | |
f8f6d679 | 459 | *insn++ = BPF_MOV32_IMM(BPF_REG_TMP, fp->k); |
bd4cf0ed | 460 | |
e430f34e AS |
461 | insn->dst_reg = BPF_REG_A; |
462 | insn->src_reg = BPF_REG_TMP; | |
bd4cf0ed AS |
463 | bpf_src = BPF_X; |
464 | } else { | |
e430f34e AS |
465 | insn->dst_reg = BPF_REG_A; |
466 | insn->src_reg = BPF_REG_X; | |
bd4cf0ed AS |
467 | insn->imm = fp->k; |
468 | bpf_src = BPF_SRC(fp->code); | |
1da177e4 | 469 | } |
bd4cf0ed AS |
470 | |
471 | /* Common case where 'jump_false' is next insn. */ | |
472 | if (fp->jf == 0) { | |
473 | insn->code = BPF_JMP | BPF_OP(fp->code) | bpf_src; | |
474 | target = i + fp->jt + 1; | |
f8f6d679 | 475 | BPF_EMIT_JMP; |
bd4cf0ed | 476 | break; |
1da177e4 | 477 | } |
bd4cf0ed AS |
478 | |
479 | /* Convert JEQ into JNE when 'jump_true' is next insn. */ | |
480 | if (fp->jt == 0 && BPF_OP(fp->code) == BPF_JEQ) { | |
481 | insn->code = BPF_JMP | BPF_JNE | bpf_src; | |
482 | target = i + fp->jf + 1; | |
f8f6d679 | 483 | BPF_EMIT_JMP; |
bd4cf0ed | 484 | break; |
0b05b2a4 | 485 | } |
bd4cf0ed AS |
486 | |
487 | /* Other jumps are mapped into two insns: Jxx and JA. */ | |
488 | target = i + fp->jt + 1; | |
489 | insn->code = BPF_JMP | BPF_OP(fp->code) | bpf_src; | |
f8f6d679 | 490 | BPF_EMIT_JMP; |
bd4cf0ed AS |
491 | insn++; |
492 | ||
493 | insn->code = BPF_JMP | BPF_JA; | |
494 | target = i + fp->jf + 1; | |
f8f6d679 | 495 | BPF_EMIT_JMP; |
bd4cf0ed AS |
496 | break; |
497 | ||
498 | /* ldxb 4 * ([14] & 0xf) is remaped into 6 insns. */ | |
499 | case BPF_LDX | BPF_MSH | BPF_B: | |
9739eef1 | 500 | /* tmp = A */ |
f8f6d679 | 501 | *insn++ = BPF_MOV64_REG(BPF_REG_TMP, BPF_REG_A); |
1268e253 | 502 | /* A = BPF_R0 = *(u8 *) (skb->data + K) */ |
f8f6d679 | 503 | *insn++ = BPF_LD_ABS(BPF_B, fp->k); |
9739eef1 | 504 | /* A &= 0xf */ |
f8f6d679 | 505 | *insn++ = BPF_ALU32_IMM(BPF_AND, BPF_REG_A, 0xf); |
9739eef1 | 506 | /* A <<= 2 */ |
f8f6d679 | 507 | *insn++ = BPF_ALU32_IMM(BPF_LSH, BPF_REG_A, 2); |
9739eef1 | 508 | /* X = A */ |
f8f6d679 | 509 | *insn++ = BPF_MOV64_REG(BPF_REG_X, BPF_REG_A); |
9739eef1 | 510 | /* A = tmp */ |
f8f6d679 | 511 | *insn = BPF_MOV64_REG(BPF_REG_A, BPF_REG_TMP); |
bd4cf0ed AS |
512 | break; |
513 | ||
514 | /* RET_K, RET_A are remaped into 2 insns. */ | |
515 | case BPF_RET | BPF_A: | |
516 | case BPF_RET | BPF_K: | |
f8f6d679 DB |
517 | *insn++ = BPF_MOV32_RAW(BPF_RVAL(fp->code) == BPF_K ? |
518 | BPF_K : BPF_X, BPF_REG_0, | |
519 | BPF_REG_A, fp->k); | |
9739eef1 | 520 | *insn = BPF_EXIT_INSN(); |
bd4cf0ed AS |
521 | break; |
522 | ||
523 | /* Store to stack. */ | |
524 | case BPF_ST: | |
525 | case BPF_STX: | |
f8f6d679 DB |
526 | *insn = BPF_STX_MEM(BPF_W, BPF_REG_FP, BPF_CLASS(fp->code) == |
527 | BPF_ST ? BPF_REG_A : BPF_REG_X, | |
528 | -(BPF_MEMWORDS - fp->k) * 4); | |
bd4cf0ed AS |
529 | break; |
530 | ||
531 | /* Load from stack. */ | |
532 | case BPF_LD | BPF_MEM: | |
533 | case BPF_LDX | BPF_MEM: | |
f8f6d679 DB |
534 | *insn = BPF_LDX_MEM(BPF_W, BPF_CLASS(fp->code) == BPF_LD ? |
535 | BPF_REG_A : BPF_REG_X, BPF_REG_FP, | |
536 | -(BPF_MEMWORDS - fp->k) * 4); | |
bd4cf0ed AS |
537 | break; |
538 | ||
539 | /* A = K or X = K */ | |
540 | case BPF_LD | BPF_IMM: | |
541 | case BPF_LDX | BPF_IMM: | |
f8f6d679 DB |
542 | *insn = BPF_MOV32_IMM(BPF_CLASS(fp->code) == BPF_LD ? |
543 | BPF_REG_A : BPF_REG_X, fp->k); | |
bd4cf0ed AS |
544 | break; |
545 | ||
546 | /* X = A */ | |
547 | case BPF_MISC | BPF_TAX: | |
f8f6d679 | 548 | *insn = BPF_MOV64_REG(BPF_REG_X, BPF_REG_A); |
bd4cf0ed AS |
549 | break; |
550 | ||
551 | /* A = X */ | |
552 | case BPF_MISC | BPF_TXA: | |
f8f6d679 | 553 | *insn = BPF_MOV64_REG(BPF_REG_A, BPF_REG_X); |
bd4cf0ed AS |
554 | break; |
555 | ||
556 | /* A = skb->len or X = skb->len */ | |
557 | case BPF_LD | BPF_W | BPF_LEN: | |
558 | case BPF_LDX | BPF_W | BPF_LEN: | |
f8f6d679 DB |
559 | *insn = BPF_LDX_MEM(BPF_W, BPF_CLASS(fp->code) == BPF_LD ? |
560 | BPF_REG_A : BPF_REG_X, BPF_REG_CTX, | |
561 | offsetof(struct sk_buff, len)); | |
bd4cf0ed AS |
562 | break; |
563 | ||
f8f6d679 | 564 | /* Access seccomp_data fields. */ |
bd4cf0ed | 565 | case BPF_LDX | BPF_ABS | BPF_W: |
9739eef1 AS |
566 | /* A = *(u32 *) (ctx + K) */ |
567 | *insn = BPF_LDX_MEM(BPF_W, BPF_REG_A, BPF_REG_CTX, fp->k); | |
bd4cf0ed AS |
568 | break; |
569 | ||
ca9f1fd2 | 570 | /* Unknown instruction. */ |
1da177e4 | 571 | default: |
bd4cf0ed | 572 | goto err; |
1da177e4 | 573 | } |
bd4cf0ed AS |
574 | |
575 | insn++; | |
576 | if (new_prog) | |
577 | memcpy(new_insn, tmp_insns, | |
578 | sizeof(*insn) * (insn - tmp_insns)); | |
bd4cf0ed | 579 | new_insn += insn - tmp_insns; |
1da177e4 LT |
580 | } |
581 | ||
bd4cf0ed AS |
582 | if (!new_prog) { |
583 | /* Only calculating new length. */ | |
584 | *new_len = new_insn - new_prog; | |
585 | return 0; | |
586 | } | |
587 | ||
588 | pass++; | |
589 | if (new_flen != new_insn - new_prog) { | |
590 | new_flen = new_insn - new_prog; | |
591 | if (pass > 2) | |
592 | goto err; | |
bd4cf0ed AS |
593 | goto do_pass; |
594 | } | |
595 | ||
596 | kfree(addrs); | |
597 | BUG_ON(*new_len != new_flen); | |
1da177e4 | 598 | return 0; |
bd4cf0ed AS |
599 | err: |
600 | kfree(addrs); | |
601 | return -EINVAL; | |
1da177e4 LT |
602 | } |
603 | ||
bd4cf0ed | 604 | /* Security: |
bd4cf0ed | 605 | * |
2d5311e4 | 606 | * As we dont want to clear mem[] array for each packet going through |
8ea6e345 | 607 | * __bpf_prog_run(), we check that filter loaded by user never try to read |
2d5311e4 | 608 | * a cell if not previously written, and we check all branches to be sure |
25985edc | 609 | * a malicious user doesn't try to abuse us. |
2d5311e4 | 610 | */ |
ec31a05c | 611 | static int check_load_and_stores(const struct sock_filter *filter, int flen) |
2d5311e4 | 612 | { |
34805931 | 613 | u16 *masks, memvalid = 0; /* One bit per cell, 16 cells */ |
2d5311e4 ED |
614 | int pc, ret = 0; |
615 | ||
616 | BUILD_BUG_ON(BPF_MEMWORDS > 16); | |
34805931 | 617 | |
99e72a0f | 618 | masks = kmalloc_array(flen, sizeof(*masks), GFP_KERNEL); |
2d5311e4 ED |
619 | if (!masks) |
620 | return -ENOMEM; | |
34805931 | 621 | |
2d5311e4 ED |
622 | memset(masks, 0xff, flen * sizeof(*masks)); |
623 | ||
624 | for (pc = 0; pc < flen; pc++) { | |
625 | memvalid &= masks[pc]; | |
626 | ||
627 | switch (filter[pc].code) { | |
34805931 DB |
628 | case BPF_ST: |
629 | case BPF_STX: | |
2d5311e4 ED |
630 | memvalid |= (1 << filter[pc].k); |
631 | break; | |
34805931 DB |
632 | case BPF_LD | BPF_MEM: |
633 | case BPF_LDX | BPF_MEM: | |
2d5311e4 ED |
634 | if (!(memvalid & (1 << filter[pc].k))) { |
635 | ret = -EINVAL; | |
636 | goto error; | |
637 | } | |
638 | break; | |
34805931 DB |
639 | case BPF_JMP | BPF_JA: |
640 | /* A jump must set masks on target */ | |
2d5311e4 ED |
641 | masks[pc + 1 + filter[pc].k] &= memvalid; |
642 | memvalid = ~0; | |
643 | break; | |
34805931 DB |
644 | case BPF_JMP | BPF_JEQ | BPF_K: |
645 | case BPF_JMP | BPF_JEQ | BPF_X: | |
646 | case BPF_JMP | BPF_JGE | BPF_K: | |
647 | case BPF_JMP | BPF_JGE | BPF_X: | |
648 | case BPF_JMP | BPF_JGT | BPF_K: | |
649 | case BPF_JMP | BPF_JGT | BPF_X: | |
650 | case BPF_JMP | BPF_JSET | BPF_K: | |
651 | case BPF_JMP | BPF_JSET | BPF_X: | |
652 | /* A jump must set masks on targets */ | |
2d5311e4 ED |
653 | masks[pc + 1 + filter[pc].jt] &= memvalid; |
654 | masks[pc + 1 + filter[pc].jf] &= memvalid; | |
655 | memvalid = ~0; | |
656 | break; | |
657 | } | |
658 | } | |
659 | error: | |
660 | kfree(masks); | |
661 | return ret; | |
662 | } | |
663 | ||
34805931 DB |
664 | static bool chk_code_allowed(u16 code_to_probe) |
665 | { | |
666 | static const bool codes[] = { | |
667 | /* 32 bit ALU operations */ | |
668 | [BPF_ALU | BPF_ADD | BPF_K] = true, | |
669 | [BPF_ALU | BPF_ADD | BPF_X] = true, | |
670 | [BPF_ALU | BPF_SUB | BPF_K] = true, | |
671 | [BPF_ALU | BPF_SUB | BPF_X] = true, | |
672 | [BPF_ALU | BPF_MUL | BPF_K] = true, | |
673 | [BPF_ALU | BPF_MUL | BPF_X] = true, | |
674 | [BPF_ALU | BPF_DIV | BPF_K] = true, | |
675 | [BPF_ALU | BPF_DIV | BPF_X] = true, | |
676 | [BPF_ALU | BPF_MOD | BPF_K] = true, | |
677 | [BPF_ALU | BPF_MOD | BPF_X] = true, | |
678 | [BPF_ALU | BPF_AND | BPF_K] = true, | |
679 | [BPF_ALU | BPF_AND | BPF_X] = true, | |
680 | [BPF_ALU | BPF_OR | BPF_K] = true, | |
681 | [BPF_ALU | BPF_OR | BPF_X] = true, | |
682 | [BPF_ALU | BPF_XOR | BPF_K] = true, | |
683 | [BPF_ALU | BPF_XOR | BPF_X] = true, | |
684 | [BPF_ALU | BPF_LSH | BPF_K] = true, | |
685 | [BPF_ALU | BPF_LSH | BPF_X] = true, | |
686 | [BPF_ALU | BPF_RSH | BPF_K] = true, | |
687 | [BPF_ALU | BPF_RSH | BPF_X] = true, | |
688 | [BPF_ALU | BPF_NEG] = true, | |
689 | /* Load instructions */ | |
690 | [BPF_LD | BPF_W | BPF_ABS] = true, | |
691 | [BPF_LD | BPF_H | BPF_ABS] = true, | |
692 | [BPF_LD | BPF_B | BPF_ABS] = true, | |
693 | [BPF_LD | BPF_W | BPF_LEN] = true, | |
694 | [BPF_LD | BPF_W | BPF_IND] = true, | |
695 | [BPF_LD | BPF_H | BPF_IND] = true, | |
696 | [BPF_LD | BPF_B | BPF_IND] = true, | |
697 | [BPF_LD | BPF_IMM] = true, | |
698 | [BPF_LD | BPF_MEM] = true, | |
699 | [BPF_LDX | BPF_W | BPF_LEN] = true, | |
700 | [BPF_LDX | BPF_B | BPF_MSH] = true, | |
701 | [BPF_LDX | BPF_IMM] = true, | |
702 | [BPF_LDX | BPF_MEM] = true, | |
703 | /* Store instructions */ | |
704 | [BPF_ST] = true, | |
705 | [BPF_STX] = true, | |
706 | /* Misc instructions */ | |
707 | [BPF_MISC | BPF_TAX] = true, | |
708 | [BPF_MISC | BPF_TXA] = true, | |
709 | /* Return instructions */ | |
710 | [BPF_RET | BPF_K] = true, | |
711 | [BPF_RET | BPF_A] = true, | |
712 | /* Jump instructions */ | |
713 | [BPF_JMP | BPF_JA] = true, | |
714 | [BPF_JMP | BPF_JEQ | BPF_K] = true, | |
715 | [BPF_JMP | BPF_JEQ | BPF_X] = true, | |
716 | [BPF_JMP | BPF_JGE | BPF_K] = true, | |
717 | [BPF_JMP | BPF_JGE | BPF_X] = true, | |
718 | [BPF_JMP | BPF_JGT | BPF_K] = true, | |
719 | [BPF_JMP | BPF_JGT | BPF_X] = true, | |
720 | [BPF_JMP | BPF_JSET | BPF_K] = true, | |
721 | [BPF_JMP | BPF_JSET | BPF_X] = true, | |
722 | }; | |
723 | ||
724 | if (code_to_probe >= ARRAY_SIZE(codes)) | |
725 | return false; | |
726 | ||
727 | return codes[code_to_probe]; | |
728 | } | |
729 | ||
1da177e4 | 730 | /** |
4df95ff4 | 731 | * bpf_check_classic - verify socket filter code |
1da177e4 LT |
732 | * @filter: filter to verify |
733 | * @flen: length of filter | |
734 | * | |
735 | * Check the user's filter code. If we let some ugly | |
736 | * filter code slip through kaboom! The filter must contain | |
93699863 KK |
737 | * no references or jumps that are out of range, no illegal |
738 | * instructions, and must end with a RET instruction. | |
1da177e4 | 739 | * |
7b11f69f KK |
740 | * All jumps are forward as they are not signed. |
741 | * | |
742 | * Returns 0 if the rule set is legal or -EINVAL if not. | |
1da177e4 | 743 | */ |
4df95ff4 | 744 | int bpf_check_classic(const struct sock_filter *filter, unsigned int flen) |
1da177e4 | 745 | { |
aa1113d9 | 746 | bool anc_found; |
34805931 | 747 | int pc; |
1da177e4 | 748 | |
1b93ae64 | 749 | if (flen == 0 || flen > BPF_MAXINSNS) |
1da177e4 LT |
750 | return -EINVAL; |
751 | ||
34805931 | 752 | /* Check the filter code now */ |
1da177e4 | 753 | for (pc = 0; pc < flen; pc++) { |
ec31a05c | 754 | const struct sock_filter *ftest = &filter[pc]; |
93699863 | 755 | |
34805931 DB |
756 | /* May we actually operate on this code? */ |
757 | if (!chk_code_allowed(ftest->code)) | |
cba328fc | 758 | return -EINVAL; |
34805931 | 759 | |
93699863 | 760 | /* Some instructions need special checks */ |
34805931 DB |
761 | switch (ftest->code) { |
762 | case BPF_ALU | BPF_DIV | BPF_K: | |
763 | case BPF_ALU | BPF_MOD | BPF_K: | |
764 | /* Check for division by zero */ | |
b6069a95 ED |
765 | if (ftest->k == 0) |
766 | return -EINVAL; | |
767 | break; | |
34805931 DB |
768 | case BPF_LD | BPF_MEM: |
769 | case BPF_LDX | BPF_MEM: | |
770 | case BPF_ST: | |
771 | case BPF_STX: | |
772 | /* Check for invalid memory addresses */ | |
93699863 KK |
773 | if (ftest->k >= BPF_MEMWORDS) |
774 | return -EINVAL; | |
775 | break; | |
34805931 DB |
776 | case BPF_JMP | BPF_JA: |
777 | /* Note, the large ftest->k might cause loops. | |
93699863 KK |
778 | * Compare this with conditional jumps below, |
779 | * where offsets are limited. --ANK (981016) | |
780 | */ | |
34805931 | 781 | if (ftest->k >= (unsigned int)(flen - pc - 1)) |
93699863 | 782 | return -EINVAL; |
01f2f3f6 | 783 | break; |
34805931 DB |
784 | case BPF_JMP | BPF_JEQ | BPF_K: |
785 | case BPF_JMP | BPF_JEQ | BPF_X: | |
786 | case BPF_JMP | BPF_JGE | BPF_K: | |
787 | case BPF_JMP | BPF_JGE | BPF_X: | |
788 | case BPF_JMP | BPF_JGT | BPF_K: | |
789 | case BPF_JMP | BPF_JGT | BPF_X: | |
790 | case BPF_JMP | BPF_JSET | BPF_K: | |
791 | case BPF_JMP | BPF_JSET | BPF_X: | |
792 | /* Both conditionals must be safe */ | |
e35bedf3 | 793 | if (pc + ftest->jt + 1 >= flen || |
93699863 KK |
794 | pc + ftest->jf + 1 >= flen) |
795 | return -EINVAL; | |
cba328fc | 796 | break; |
34805931 DB |
797 | case BPF_LD | BPF_W | BPF_ABS: |
798 | case BPF_LD | BPF_H | BPF_ABS: | |
799 | case BPF_LD | BPF_B | BPF_ABS: | |
aa1113d9 | 800 | anc_found = false; |
34805931 DB |
801 | if (bpf_anc_helper(ftest) & BPF_ANC) |
802 | anc_found = true; | |
803 | /* Ancillary operation unknown or unsupported */ | |
aa1113d9 DB |
804 | if (anc_found == false && ftest->k >= SKF_AD_OFF) |
805 | return -EINVAL; | |
01f2f3f6 HPP |
806 | } |
807 | } | |
93699863 | 808 | |
34805931 | 809 | /* Last instruction must be a RET code */ |
01f2f3f6 | 810 | switch (filter[flen - 1].code) { |
34805931 DB |
811 | case BPF_RET | BPF_K: |
812 | case BPF_RET | BPF_A: | |
2d5311e4 | 813 | return check_load_and_stores(filter, flen); |
cba328fc | 814 | } |
34805931 | 815 | |
cba328fc | 816 | return -EINVAL; |
1da177e4 | 817 | } |
4df95ff4 | 818 | EXPORT_SYMBOL(bpf_check_classic); |
1da177e4 | 819 | |
7ae457c1 AS |
820 | static int bpf_prog_store_orig_filter(struct bpf_prog *fp, |
821 | const struct sock_fprog *fprog) | |
a3ea269b | 822 | { |
009937e7 | 823 | unsigned int fsize = bpf_classic_proglen(fprog); |
a3ea269b DB |
824 | struct sock_fprog_kern *fkprog; |
825 | ||
826 | fp->orig_prog = kmalloc(sizeof(*fkprog), GFP_KERNEL); | |
827 | if (!fp->orig_prog) | |
828 | return -ENOMEM; | |
829 | ||
830 | fkprog = fp->orig_prog; | |
831 | fkprog->len = fprog->len; | |
832 | fkprog->filter = kmemdup(fp->insns, fsize, GFP_KERNEL); | |
833 | if (!fkprog->filter) { | |
834 | kfree(fp->orig_prog); | |
835 | return -ENOMEM; | |
836 | } | |
837 | ||
838 | return 0; | |
839 | } | |
840 | ||
7ae457c1 | 841 | static void bpf_release_orig_filter(struct bpf_prog *fp) |
a3ea269b DB |
842 | { |
843 | struct sock_fprog_kern *fprog = fp->orig_prog; | |
844 | ||
845 | if (fprog) { | |
846 | kfree(fprog->filter); | |
847 | kfree(fprog); | |
848 | } | |
849 | } | |
850 | ||
7ae457c1 AS |
851 | static void __bpf_prog_release(struct bpf_prog *prog) |
852 | { | |
24701ece | 853 | if (prog->type == BPF_PROG_TYPE_SOCKET_FILTER) { |
89aa0758 AS |
854 | bpf_prog_put(prog); |
855 | } else { | |
856 | bpf_release_orig_filter(prog); | |
857 | bpf_prog_free(prog); | |
858 | } | |
7ae457c1 AS |
859 | } |
860 | ||
34c5bd66 PN |
861 | static void __sk_filter_release(struct sk_filter *fp) |
862 | { | |
7ae457c1 AS |
863 | __bpf_prog_release(fp->prog); |
864 | kfree(fp); | |
34c5bd66 PN |
865 | } |
866 | ||
47e958ea | 867 | /** |
46bcf14f | 868 | * sk_filter_release_rcu - Release a socket filter by rcu_head |
47e958ea PE |
869 | * @rcu: rcu_head that contains the sk_filter to free |
870 | */ | |
fbc907f0 | 871 | static void sk_filter_release_rcu(struct rcu_head *rcu) |
47e958ea PE |
872 | { |
873 | struct sk_filter *fp = container_of(rcu, struct sk_filter, rcu); | |
874 | ||
34c5bd66 | 875 | __sk_filter_release(fp); |
47e958ea | 876 | } |
fbc907f0 DB |
877 | |
878 | /** | |
879 | * sk_filter_release - release a socket filter | |
880 | * @fp: filter to remove | |
881 | * | |
882 | * Remove a filter from a socket and release its resources. | |
883 | */ | |
884 | static void sk_filter_release(struct sk_filter *fp) | |
885 | { | |
886 | if (atomic_dec_and_test(&fp->refcnt)) | |
887 | call_rcu(&fp->rcu, sk_filter_release_rcu); | |
888 | } | |
889 | ||
890 | void sk_filter_uncharge(struct sock *sk, struct sk_filter *fp) | |
891 | { | |
7ae457c1 | 892 | u32 filter_size = bpf_prog_size(fp->prog->len); |
fbc907f0 | 893 | |
278571ba AS |
894 | atomic_sub(filter_size, &sk->sk_omem_alloc); |
895 | sk_filter_release(fp); | |
fbc907f0 | 896 | } |
47e958ea | 897 | |
278571ba AS |
898 | /* try to charge the socket memory if there is space available |
899 | * return true on success | |
900 | */ | |
901 | bool sk_filter_charge(struct sock *sk, struct sk_filter *fp) | |
bd4cf0ed | 902 | { |
7ae457c1 | 903 | u32 filter_size = bpf_prog_size(fp->prog->len); |
278571ba AS |
904 | |
905 | /* same check as in sock_kmalloc() */ | |
906 | if (filter_size <= sysctl_optmem_max && | |
907 | atomic_read(&sk->sk_omem_alloc) + filter_size < sysctl_optmem_max) { | |
908 | atomic_inc(&fp->refcnt); | |
909 | atomic_add(filter_size, &sk->sk_omem_alloc); | |
910 | return true; | |
bd4cf0ed | 911 | } |
278571ba | 912 | return false; |
bd4cf0ed AS |
913 | } |
914 | ||
7ae457c1 | 915 | static struct bpf_prog *bpf_migrate_filter(struct bpf_prog *fp) |
bd4cf0ed AS |
916 | { |
917 | struct sock_filter *old_prog; | |
7ae457c1 | 918 | struct bpf_prog *old_fp; |
34805931 | 919 | int err, new_len, old_len = fp->len; |
bd4cf0ed AS |
920 | |
921 | /* We are free to overwrite insns et al right here as it | |
922 | * won't be used at this point in time anymore internally | |
923 | * after the migration to the internal BPF instruction | |
924 | * representation. | |
925 | */ | |
926 | BUILD_BUG_ON(sizeof(struct sock_filter) != | |
2695fb55 | 927 | sizeof(struct bpf_insn)); |
bd4cf0ed | 928 | |
bd4cf0ed AS |
929 | /* Conversion cannot happen on overlapping memory areas, |
930 | * so we need to keep the user BPF around until the 2nd | |
931 | * pass. At this time, the user BPF is stored in fp->insns. | |
932 | */ | |
933 | old_prog = kmemdup(fp->insns, old_len * sizeof(struct sock_filter), | |
934 | GFP_KERNEL); | |
935 | if (!old_prog) { | |
936 | err = -ENOMEM; | |
937 | goto out_err; | |
938 | } | |
939 | ||
940 | /* 1st pass: calculate the new program length. */ | |
8fb575ca | 941 | err = bpf_convert_filter(old_prog, old_len, NULL, &new_len); |
bd4cf0ed AS |
942 | if (err) |
943 | goto out_err_free; | |
944 | ||
945 | /* Expand fp for appending the new filter representation. */ | |
946 | old_fp = fp; | |
60a3b225 | 947 | fp = bpf_prog_realloc(old_fp, bpf_prog_size(new_len), 0); |
bd4cf0ed AS |
948 | if (!fp) { |
949 | /* The old_fp is still around in case we couldn't | |
950 | * allocate new memory, so uncharge on that one. | |
951 | */ | |
952 | fp = old_fp; | |
953 | err = -ENOMEM; | |
954 | goto out_err_free; | |
955 | } | |
956 | ||
bd4cf0ed AS |
957 | fp->len = new_len; |
958 | ||
2695fb55 | 959 | /* 2nd pass: remap sock_filter insns into bpf_insn insns. */ |
8fb575ca | 960 | err = bpf_convert_filter(old_prog, old_len, fp->insnsi, &new_len); |
bd4cf0ed | 961 | if (err) |
8fb575ca | 962 | /* 2nd bpf_convert_filter() can fail only if it fails |
bd4cf0ed AS |
963 | * to allocate memory, remapping must succeed. Note, |
964 | * that at this time old_fp has already been released | |
278571ba | 965 | * by krealloc(). |
bd4cf0ed AS |
966 | */ |
967 | goto out_err_free; | |
968 | ||
7ae457c1 | 969 | bpf_prog_select_runtime(fp); |
5fe821a9 | 970 | |
bd4cf0ed AS |
971 | kfree(old_prog); |
972 | return fp; | |
973 | ||
974 | out_err_free: | |
975 | kfree(old_prog); | |
976 | out_err: | |
7ae457c1 | 977 | __bpf_prog_release(fp); |
bd4cf0ed AS |
978 | return ERR_PTR(err); |
979 | } | |
980 | ||
7ae457c1 | 981 | static struct bpf_prog *bpf_prepare_filter(struct bpf_prog *fp) |
302d6637 JP |
982 | { |
983 | int err; | |
984 | ||
bd4cf0ed | 985 | fp->bpf_func = NULL; |
286aad3c | 986 | fp->jited = false; |
302d6637 | 987 | |
4df95ff4 | 988 | err = bpf_check_classic(fp->insns, fp->len); |
418c96ac | 989 | if (err) { |
7ae457c1 | 990 | __bpf_prog_release(fp); |
bd4cf0ed | 991 | return ERR_PTR(err); |
418c96ac | 992 | } |
302d6637 | 993 | |
bd4cf0ed AS |
994 | /* Probe if we can JIT compile the filter and if so, do |
995 | * the compilation of the filter. | |
996 | */ | |
302d6637 | 997 | bpf_jit_compile(fp); |
bd4cf0ed AS |
998 | |
999 | /* JIT compiler couldn't process this filter, so do the | |
1000 | * internal BPF translation for the optimized interpreter. | |
1001 | */ | |
5fe821a9 | 1002 | if (!fp->jited) |
7ae457c1 | 1003 | fp = bpf_migrate_filter(fp); |
bd4cf0ed AS |
1004 | |
1005 | return fp; | |
302d6637 JP |
1006 | } |
1007 | ||
1008 | /** | |
7ae457c1 | 1009 | * bpf_prog_create - create an unattached filter |
c6c4b97c | 1010 | * @pfp: the unattached filter that is created |
677a9fd3 | 1011 | * @fprog: the filter program |
302d6637 | 1012 | * |
c6c4b97c | 1013 | * Create a filter independent of any socket. We first run some |
302d6637 JP |
1014 | * sanity checks on it to make sure it does not explode on us later. |
1015 | * If an error occurs or there is insufficient memory for the filter | |
1016 | * a negative errno code is returned. On success the return is zero. | |
1017 | */ | |
7ae457c1 | 1018 | int bpf_prog_create(struct bpf_prog **pfp, struct sock_fprog_kern *fprog) |
302d6637 | 1019 | { |
009937e7 | 1020 | unsigned int fsize = bpf_classic_proglen(fprog); |
7ae457c1 | 1021 | struct bpf_prog *fp; |
302d6637 JP |
1022 | |
1023 | /* Make sure new filter is there and in the right amounts. */ | |
1024 | if (fprog->filter == NULL) | |
1025 | return -EINVAL; | |
1026 | ||
60a3b225 | 1027 | fp = bpf_prog_alloc(bpf_prog_size(fprog->len), 0); |
302d6637 JP |
1028 | if (!fp) |
1029 | return -ENOMEM; | |
a3ea269b | 1030 | |
302d6637 JP |
1031 | memcpy(fp->insns, fprog->filter, fsize); |
1032 | ||
302d6637 | 1033 | fp->len = fprog->len; |
a3ea269b DB |
1034 | /* Since unattached filters are not copied back to user |
1035 | * space through sk_get_filter(), we do not need to hold | |
1036 | * a copy here, and can spare us the work. | |
1037 | */ | |
1038 | fp->orig_prog = NULL; | |
302d6637 | 1039 | |
7ae457c1 | 1040 | /* bpf_prepare_filter() already takes care of freeing |
bd4cf0ed AS |
1041 | * memory in case something goes wrong. |
1042 | */ | |
7ae457c1 | 1043 | fp = bpf_prepare_filter(fp); |
bd4cf0ed AS |
1044 | if (IS_ERR(fp)) |
1045 | return PTR_ERR(fp); | |
302d6637 JP |
1046 | |
1047 | *pfp = fp; | |
1048 | return 0; | |
302d6637 | 1049 | } |
7ae457c1 | 1050 | EXPORT_SYMBOL_GPL(bpf_prog_create); |
302d6637 | 1051 | |
7ae457c1 | 1052 | void bpf_prog_destroy(struct bpf_prog *fp) |
302d6637 | 1053 | { |
7ae457c1 | 1054 | __bpf_prog_release(fp); |
302d6637 | 1055 | } |
7ae457c1 | 1056 | EXPORT_SYMBOL_GPL(bpf_prog_destroy); |
302d6637 | 1057 | |
49b31e57 DB |
1058 | static int __sk_attach_prog(struct bpf_prog *prog, struct sock *sk) |
1059 | { | |
1060 | struct sk_filter *fp, *old_fp; | |
1061 | ||
1062 | fp = kmalloc(sizeof(*fp), GFP_KERNEL); | |
1063 | if (!fp) | |
1064 | return -ENOMEM; | |
1065 | ||
1066 | fp->prog = prog; | |
1067 | atomic_set(&fp->refcnt, 0); | |
1068 | ||
1069 | if (!sk_filter_charge(sk, fp)) { | |
1070 | kfree(fp); | |
1071 | return -ENOMEM; | |
1072 | } | |
1073 | ||
1074 | old_fp = rcu_dereference_protected(sk->sk_filter, | |
1075 | sock_owned_by_user(sk)); | |
1076 | rcu_assign_pointer(sk->sk_filter, fp); | |
1077 | ||
1078 | if (old_fp) | |
1079 | sk_filter_uncharge(sk, old_fp); | |
1080 | ||
1081 | return 0; | |
1082 | } | |
1083 | ||
1da177e4 LT |
1084 | /** |
1085 | * sk_attach_filter - attach a socket filter | |
1086 | * @fprog: the filter program | |
1087 | * @sk: the socket to use | |
1088 | * | |
1089 | * Attach the user's filter code. We first run some sanity checks on | |
1090 | * it to make sure it does not explode on us later. If an error | |
1091 | * occurs or there is insufficient memory for the filter a negative | |
1092 | * errno code is returned. On success the return is zero. | |
1093 | */ | |
1094 | int sk_attach_filter(struct sock_fprog *fprog, struct sock *sk) | |
1095 | { | |
009937e7 | 1096 | unsigned int fsize = bpf_classic_proglen(fprog); |
7ae457c1 AS |
1097 | unsigned int bpf_fsize = bpf_prog_size(fprog->len); |
1098 | struct bpf_prog *prog; | |
1da177e4 LT |
1099 | int err; |
1100 | ||
d59577b6 VB |
1101 | if (sock_flag(sk, SOCK_FILTER_LOCKED)) |
1102 | return -EPERM; | |
1103 | ||
1da177e4 | 1104 | /* Make sure new filter is there and in the right amounts. */ |
e35bedf3 KK |
1105 | if (fprog->filter == NULL) |
1106 | return -EINVAL; | |
1da177e4 | 1107 | |
60a3b225 | 1108 | prog = bpf_prog_alloc(bpf_fsize, 0); |
7ae457c1 | 1109 | if (!prog) |
1da177e4 | 1110 | return -ENOMEM; |
a3ea269b | 1111 | |
7ae457c1 | 1112 | if (copy_from_user(prog->insns, fprog->filter, fsize)) { |
c0d1379a | 1113 | __bpf_prog_free(prog); |
1da177e4 LT |
1114 | return -EFAULT; |
1115 | } | |
1116 | ||
7ae457c1 | 1117 | prog->len = fprog->len; |
1da177e4 | 1118 | |
7ae457c1 | 1119 | err = bpf_prog_store_orig_filter(prog, fprog); |
a3ea269b | 1120 | if (err) { |
c0d1379a | 1121 | __bpf_prog_free(prog); |
a3ea269b DB |
1122 | return -ENOMEM; |
1123 | } | |
1124 | ||
7ae457c1 | 1125 | /* bpf_prepare_filter() already takes care of freeing |
bd4cf0ed AS |
1126 | * memory in case something goes wrong. |
1127 | */ | |
7ae457c1 AS |
1128 | prog = bpf_prepare_filter(prog); |
1129 | if (IS_ERR(prog)) | |
1130 | return PTR_ERR(prog); | |
1131 | ||
49b31e57 DB |
1132 | err = __sk_attach_prog(prog, sk); |
1133 | if (err < 0) { | |
7ae457c1 | 1134 | __bpf_prog_release(prog); |
49b31e57 | 1135 | return err; |
278571ba AS |
1136 | } |
1137 | ||
d3904b73 | 1138 | return 0; |
1da177e4 | 1139 | } |
5ff3f073 | 1140 | EXPORT_SYMBOL_GPL(sk_attach_filter); |
1da177e4 | 1141 | |
89aa0758 AS |
1142 | int sk_attach_bpf(u32 ufd, struct sock *sk) |
1143 | { | |
89aa0758 | 1144 | struct bpf_prog *prog; |
49b31e57 | 1145 | int err; |
89aa0758 AS |
1146 | |
1147 | if (sock_flag(sk, SOCK_FILTER_LOCKED)) | |
1148 | return -EPERM; | |
1149 | ||
1150 | prog = bpf_prog_get(ufd); | |
198bf1b0 AS |
1151 | if (IS_ERR(prog)) |
1152 | return PTR_ERR(prog); | |
89aa0758 | 1153 | |
24701ece | 1154 | if (prog->type != BPF_PROG_TYPE_SOCKET_FILTER) { |
89aa0758 AS |
1155 | bpf_prog_put(prog); |
1156 | return -EINVAL; | |
1157 | } | |
1158 | ||
49b31e57 DB |
1159 | err = __sk_attach_prog(prog, sk); |
1160 | if (err < 0) { | |
89aa0758 | 1161 | bpf_prog_put(prog); |
49b31e57 | 1162 | return err; |
89aa0758 AS |
1163 | } |
1164 | ||
89aa0758 AS |
1165 | return 0; |
1166 | } | |
1167 | ||
d4052c4a DB |
1168 | static const struct bpf_func_proto * |
1169 | sk_filter_func_proto(enum bpf_func_id func_id) | |
89aa0758 AS |
1170 | { |
1171 | switch (func_id) { | |
1172 | case BPF_FUNC_map_lookup_elem: | |
1173 | return &bpf_map_lookup_elem_proto; | |
1174 | case BPF_FUNC_map_update_elem: | |
1175 | return &bpf_map_update_elem_proto; | |
1176 | case BPF_FUNC_map_delete_elem: | |
1177 | return &bpf_map_delete_elem_proto; | |
03e69b50 DB |
1178 | case BPF_FUNC_get_prandom_u32: |
1179 | return &bpf_get_prandom_u32_proto; | |
c04167ce DB |
1180 | case BPF_FUNC_get_smp_processor_id: |
1181 | return &bpf_get_smp_processor_id_proto; | |
89aa0758 AS |
1182 | default: |
1183 | return NULL; | |
1184 | } | |
1185 | } | |
1186 | ||
d4052c4a DB |
1187 | static bool sk_filter_is_valid_access(int off, int size, |
1188 | enum bpf_access_type type) | |
89aa0758 | 1189 | { |
9bac3d6d AS |
1190 | /* only read is allowed */ |
1191 | if (type != BPF_READ) | |
1192 | return false; | |
1193 | ||
1194 | /* check bounds */ | |
1195 | if (off < 0 || off >= sizeof(struct __sk_buff)) | |
1196 | return false; | |
1197 | ||
1198 | /* disallow misaligned access */ | |
1199 | if (off % size != 0) | |
1200 | return false; | |
1201 | ||
1202 | /* all __sk_buff fields are __u32 */ | |
1203 | if (size != 4) | |
1204 | return false; | |
1205 | ||
1206 | return true; | |
1207 | } | |
1208 | ||
1209 | static u32 sk_filter_convert_ctx_access(int dst_reg, int src_reg, int ctx_off, | |
1210 | struct bpf_insn *insn_buf) | |
1211 | { | |
1212 | struct bpf_insn *insn = insn_buf; | |
1213 | ||
1214 | switch (ctx_off) { | |
1215 | case offsetof(struct __sk_buff, len): | |
1216 | BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, len) != 4); | |
1217 | ||
1218 | *insn++ = BPF_LDX_MEM(BPF_W, dst_reg, src_reg, | |
1219 | offsetof(struct sk_buff, len)); | |
1220 | break; | |
1221 | ||
0b8c707d DB |
1222 | case offsetof(struct __sk_buff, protocol): |
1223 | BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff, protocol) != 2); | |
1224 | ||
1225 | *insn++ = BPF_LDX_MEM(BPF_H, dst_reg, src_reg, | |
1226 | offsetof(struct sk_buff, protocol)); | |
1227 | break; | |
1228 | ||
9bac3d6d AS |
1229 | case offsetof(struct __sk_buff, mark): |
1230 | return convert_skb_access(SKF_AD_MARK, dst_reg, src_reg, insn); | |
1231 | ||
1232 | case offsetof(struct __sk_buff, pkt_type): | |
1233 | return convert_skb_access(SKF_AD_PKTTYPE, dst_reg, src_reg, insn); | |
1234 | ||
1235 | case offsetof(struct __sk_buff, queue_mapping): | |
1236 | return convert_skb_access(SKF_AD_QUEUE, dst_reg, src_reg, insn); | |
c2497395 | 1237 | |
c2497395 AS |
1238 | case offsetof(struct __sk_buff, vlan_present): |
1239 | return convert_skb_access(SKF_AD_VLAN_TAG_PRESENT, | |
1240 | dst_reg, src_reg, insn); | |
1241 | ||
1242 | case offsetof(struct __sk_buff, vlan_tci): | |
1243 | return convert_skb_access(SKF_AD_VLAN_TAG, | |
1244 | dst_reg, src_reg, insn); | |
9bac3d6d AS |
1245 | } |
1246 | ||
1247 | return insn - insn_buf; | |
89aa0758 AS |
1248 | } |
1249 | ||
d4052c4a DB |
1250 | static const struct bpf_verifier_ops sk_filter_ops = { |
1251 | .get_func_proto = sk_filter_func_proto, | |
1252 | .is_valid_access = sk_filter_is_valid_access, | |
9bac3d6d | 1253 | .convert_ctx_access = sk_filter_convert_ctx_access, |
89aa0758 AS |
1254 | }; |
1255 | ||
d4052c4a DB |
1256 | static struct bpf_prog_type_list sk_filter_type __read_mostly = { |
1257 | .ops = &sk_filter_ops, | |
89aa0758 AS |
1258 | .type = BPF_PROG_TYPE_SOCKET_FILTER, |
1259 | }; | |
1260 | ||
96be4325 DB |
1261 | static struct bpf_prog_type_list sched_cls_type __read_mostly = { |
1262 | .ops = &sk_filter_ops, | |
1263 | .type = BPF_PROG_TYPE_SCHED_CLS, | |
1264 | }; | |
1265 | ||
94caee8c DB |
1266 | static struct bpf_prog_type_list sched_act_type __read_mostly = { |
1267 | .ops = &sk_filter_ops, | |
1268 | .type = BPF_PROG_TYPE_SCHED_ACT, | |
1269 | }; | |
1270 | ||
d4052c4a | 1271 | static int __init register_sk_filter_ops(void) |
89aa0758 | 1272 | { |
d4052c4a | 1273 | bpf_register_prog_type(&sk_filter_type); |
96be4325 | 1274 | bpf_register_prog_type(&sched_cls_type); |
94caee8c | 1275 | bpf_register_prog_type(&sched_act_type); |
96be4325 | 1276 | |
89aa0758 AS |
1277 | return 0; |
1278 | } | |
d4052c4a DB |
1279 | late_initcall(register_sk_filter_ops); |
1280 | ||
55b33325 PE |
1281 | int sk_detach_filter(struct sock *sk) |
1282 | { | |
1283 | int ret = -ENOENT; | |
1284 | struct sk_filter *filter; | |
1285 | ||
d59577b6 VB |
1286 | if (sock_flag(sk, SOCK_FILTER_LOCKED)) |
1287 | return -EPERM; | |
1288 | ||
f91ff5b9 ED |
1289 | filter = rcu_dereference_protected(sk->sk_filter, |
1290 | sock_owned_by_user(sk)); | |
55b33325 | 1291 | if (filter) { |
a9b3cd7f | 1292 | RCU_INIT_POINTER(sk->sk_filter, NULL); |
46bcf14f | 1293 | sk_filter_uncharge(sk, filter); |
55b33325 PE |
1294 | ret = 0; |
1295 | } | |
a3ea269b | 1296 | |
55b33325 PE |
1297 | return ret; |
1298 | } | |
5ff3f073 | 1299 | EXPORT_SYMBOL_GPL(sk_detach_filter); |
a8fc9277 | 1300 | |
a3ea269b DB |
1301 | int sk_get_filter(struct sock *sk, struct sock_filter __user *ubuf, |
1302 | unsigned int len) | |
a8fc9277 | 1303 | { |
a3ea269b | 1304 | struct sock_fprog_kern *fprog; |
a8fc9277 | 1305 | struct sk_filter *filter; |
a3ea269b | 1306 | int ret = 0; |
a8fc9277 PE |
1307 | |
1308 | lock_sock(sk); | |
1309 | filter = rcu_dereference_protected(sk->sk_filter, | |
a3ea269b | 1310 | sock_owned_by_user(sk)); |
a8fc9277 PE |
1311 | if (!filter) |
1312 | goto out; | |
a3ea269b DB |
1313 | |
1314 | /* We're copying the filter that has been originally attached, | |
1315 | * so no conversion/decode needed anymore. | |
1316 | */ | |
7ae457c1 | 1317 | fprog = filter->prog->orig_prog; |
a3ea269b DB |
1318 | |
1319 | ret = fprog->len; | |
a8fc9277 | 1320 | if (!len) |
a3ea269b | 1321 | /* User space only enquires number of filter blocks. */ |
a8fc9277 | 1322 | goto out; |
a3ea269b | 1323 | |
a8fc9277 | 1324 | ret = -EINVAL; |
a3ea269b | 1325 | if (len < fprog->len) |
a8fc9277 PE |
1326 | goto out; |
1327 | ||
1328 | ret = -EFAULT; | |
009937e7 | 1329 | if (copy_to_user(ubuf, fprog->filter, bpf_classic_proglen(fprog))) |
a3ea269b | 1330 | goto out; |
a8fc9277 | 1331 | |
a3ea269b DB |
1332 | /* Instead of bytes, the API requests to return the number |
1333 | * of filter blocks. | |
1334 | */ | |
1335 | ret = fprog->len; | |
a8fc9277 PE |
1336 | out: |
1337 | release_sock(sk); | |
1338 | return ret; | |
1339 | } |