1 /*
2 * BPF asm code parser
3 *
4 * This program is free software; you can distribute it and/or modify
5 * it under the terms of the GNU General Public License as published
6 * by the Free Software Foundation; either version 2 of the License,
7 * or (at your option) any later version.
8 *
9 * Syntax kept close to:
10 *
11 * Steven McCanne and Van Jacobson. 1993. The BSD packet filter: a new
12 * architecture for user-level packet capture. In Proceedings of the
13 * USENIX Winter 1993 Conference Proceedings on USENIX Winter 1993
14 * Conference Proceedings (USENIX'93). USENIX Association, Berkeley,
15 * CA, USA, 2-2.
16 *
17 * Copyright 2013 Daniel Borkmann <borkmann@redhat.com>
18 * Licensed under the GNU General Public License, version 2.0 (GPLv2)
19 */
20
21 %{
22
23 #include <stdio.h>
24 #include <string.h>
25 #include <stdint.h>
26 #include <stdlib.h>
27 #include <stdbool.h>
28 #include <unistd.h>
29 #include <errno.h>
30 #include <assert.h>
31 #include <linux/filter.h>
32
33 #include "bpf_exp.yacc.h"
34
35 enum jmp_type { JTL, JFL, JKL };
36
37 extern FILE *yyin;
38 extern int yylex(void);
39 extern void yyerror(const char *str);
40
41 extern void bpf_asm_compile(FILE *fp, bool cstyle);
42 static void bpf_set_curr_instr(uint16_t op, uint8_t jt, uint8_t jf, uint32_t k);
43 static void bpf_set_curr_label(char *label);
44 static void bpf_set_jmp_label(char *label, enum jmp_type type);
45
46 %}
47
48 %union {
49 char *label;
50 uint32_t number;
51 }
52
53 %token OP_LDB OP_LDH OP_LD OP_LDX OP_ST OP_STX OP_JMP OP_JEQ OP_JGT OP_JGE
54 %token OP_JSET OP_ADD OP_SUB OP_MUL OP_DIV OP_AND OP_OR OP_XOR OP_LSH OP_RSH
55 %token OP_RET OP_TAX OP_TXA OP_LDXB OP_MOD OP_NEG OP_JNEQ OP_JLT OP_JLE OP_LDI
56 %token OP_LDXI
57
58 %token K_PKT_LEN K_PROTO K_TYPE K_NLATTR K_NLATTR_NEST K_MARK K_QUEUE K_HATYPE
59 %token K_RXHASH K_CPU K_IFIDX K_VLAN_TCI K_VLAN_AVAIL K_VLAN_TPID K_POFF K_RAND
60
61 %token ':' ',' '[' ']' '(' ')' 'x' 'a' '+' 'M' '*' '&' '#' '%'
62
63 %token number label
64
65 %type <label> label
66 %type <number> number
67
68 %%
69
70 prog
71 : line
72 | prog line
73 ;
74
75 line
76 : instr
77 | labelled_instr
78 ;
79
80 labelled_instr
81 : labelled instr
82 ;
83
84 instr
85 : ldb
86 | ldh
87 | ld
88 | ldi
89 | ldx
90 | ldxi
91 | st
92 | stx
93 | jmp
94 | jeq
95 | jneq
96 | jlt
97 | jle
98 | jgt
99 | jge
100 | jset
101 | add
102 | sub
103 | mul
104 | div
105 | mod
106 | neg
107 | and
108 | or
109 | xor
110 | lsh
111 | rsh
112 | ret
113 | tax
114 | txa
115 ;
116
117 labelled
118 : label ':' { bpf_set_curr_label($1); }
119 ;
120
121 ldb
122 : OP_LDB '[' 'x' '+' number ']' {
123 bpf_set_curr_instr(BPF_LD | BPF_B | BPF_IND, 0, 0, $5); }
124 | OP_LDB '[' '%' 'x' '+' number ']' {
125 bpf_set_curr_instr(BPF_LD | BPF_B | BPF_IND, 0, 0, $6); }
126 | OP_LDB '[' number ']' {
127 bpf_set_curr_instr(BPF_LD | BPF_B | BPF_ABS, 0, 0, $3); }
128 | OP_LDB K_PROTO {
129 bpf_set_curr_instr(BPF_LD | BPF_B | BPF_ABS, 0, 0,
130 SKF_AD_OFF + SKF_AD_PROTOCOL); }
131 | OP_LDB K_TYPE {
132 bpf_set_curr_instr(BPF_LD | BPF_B | BPF_ABS, 0, 0,
133 SKF_AD_OFF + SKF_AD_PKTTYPE); }
134 | OP_LDB K_IFIDX {
135 bpf_set_curr_instr(BPF_LD | BPF_B | BPF_ABS, 0, 0,
136 SKF_AD_OFF + SKF_AD_IFINDEX); }
137 | OP_LDB K_NLATTR {
138 bpf_set_curr_instr(BPF_LD | BPF_B | BPF_ABS, 0, 0,
139 SKF_AD_OFF + SKF_AD_NLATTR); }
140 | OP_LDB K_NLATTR_NEST {
141 bpf_set_curr_instr(BPF_LD | BPF_B | BPF_ABS, 0, 0,
142 SKF_AD_OFF + SKF_AD_NLATTR_NEST); }
143 | OP_LDB K_MARK {
144 bpf_set_curr_instr(BPF_LD | BPF_B | BPF_ABS, 0, 0,
145 SKF_AD_OFF + SKF_AD_MARK); }
146 | OP_LDB K_QUEUE {
147 bpf_set_curr_instr(BPF_LD | BPF_B | BPF_ABS, 0, 0,
148 SKF_AD_OFF + SKF_AD_QUEUE); }
149 | OP_LDB K_HATYPE {
150 bpf_set_curr_instr(BPF_LD | BPF_B | BPF_ABS, 0, 0,
151 SKF_AD_OFF + SKF_AD_HATYPE); }
152 | OP_LDB K_RXHASH {
153 bpf_set_curr_instr(BPF_LD | BPF_B | BPF_ABS, 0, 0,
154 SKF_AD_OFF + SKF_AD_RXHASH); }
155 | OP_LDB K_CPU {
156 bpf_set_curr_instr(BPF_LD | BPF_B | BPF_ABS, 0, 0,
157 SKF_AD_OFF + SKF_AD_CPU); }
158 | OP_LDB K_VLAN_TCI {
159 bpf_set_curr_instr(BPF_LD | BPF_B | BPF_ABS, 0, 0,
160 SKF_AD_OFF + SKF_AD_VLAN_TAG); }
161 | OP_LDB K_VLAN_AVAIL {
162 bpf_set_curr_instr(BPF_LD | BPF_B | BPF_ABS, 0, 0,
163 SKF_AD_OFF + SKF_AD_VLAN_TAG_PRESENT); }
164 | OP_LDB K_POFF {
165 bpf_set_curr_instr(BPF_LD | BPF_B | BPF_ABS, 0, 0,
166 SKF_AD_OFF + SKF_AD_PAY_OFFSET); }
167 | OP_LDB K_RAND {
168 bpf_set_curr_instr(BPF_LD | BPF_B | BPF_ABS, 0, 0,
169 SKF_AD_OFF + SKF_AD_RANDOM); }
170 | OP_LDB K_VLAN_TPID {
171 bpf_set_curr_instr(BPF_LD | BPF_B | BPF_ABS, 0, 0,
172 SKF_AD_OFF + SKF_AD_VLAN_TPID); }
173 ;
174
175 ldh
176 : OP_LDH '[' 'x' '+' number ']' {
177 bpf_set_curr_instr(BPF_LD | BPF_H | BPF_IND, 0, 0, $5); }
178 | OP_LDH '[' '%' 'x' '+' number ']' {
179 bpf_set_curr_instr(BPF_LD | BPF_H | BPF_IND, 0, 0, $6); }
180 | OP_LDH '[' number ']' {
181 bpf_set_curr_instr(BPF_LD | BPF_H | BPF_ABS, 0, 0, $3); }
182 | OP_LDH K_PROTO {
183 bpf_set_curr_instr(BPF_LD | BPF_H | BPF_ABS, 0, 0,
184 SKF_AD_OFF + SKF_AD_PROTOCOL); }
185 | OP_LDH K_TYPE {
186 bpf_set_curr_instr(BPF_LD | BPF_H | BPF_ABS, 0, 0,
187 SKF_AD_OFF + SKF_AD_PKTTYPE); }
188 | OP_LDH K_IFIDX {
189 bpf_set_curr_instr(BPF_LD | BPF_H | BPF_ABS, 0, 0,
190 SKF_AD_OFF + SKF_AD_IFINDEX); }
191 | OP_LDH K_NLATTR {
192 bpf_set_curr_instr(BPF_LD | BPF_H | BPF_ABS, 0, 0,
193 SKF_AD_OFF + SKF_AD_NLATTR); }
194 | OP_LDH K_NLATTR_NEST {
195 bpf_set_curr_instr(BPF_LD | BPF_H | BPF_ABS, 0, 0,
196 SKF_AD_OFF + SKF_AD_NLATTR_NEST); }
197 | OP_LDH K_MARK {
198 bpf_set_curr_instr(BPF_LD | BPF_H | BPF_ABS, 0, 0,
199 SKF_AD_OFF + SKF_AD_MARK); }
200 | OP_LDH K_QUEUE {
201 bpf_set_curr_instr(BPF_LD | BPF_H | BPF_ABS, 0, 0,
202 SKF_AD_OFF + SKF_AD_QUEUE); }
203 | OP_LDH K_HATYPE {
204 bpf_set_curr_instr(BPF_LD | BPF_H | BPF_ABS, 0, 0,
205 SKF_AD_OFF + SKF_AD_HATYPE); }
206 | OP_LDH K_RXHASH {
207 bpf_set_curr_instr(BPF_LD | BPF_H | BPF_ABS, 0, 0,
208 SKF_AD_OFF + SKF_AD_RXHASH); }
209 | OP_LDH K_CPU {
210 bpf_set_curr_instr(BPF_LD | BPF_H | BPF_ABS, 0, 0,
211 SKF_AD_OFF + SKF_AD_CPU); }
212 | OP_LDH K_VLAN_TCI {
213 bpf_set_curr_instr(BPF_LD | BPF_H | BPF_ABS, 0, 0,
214 SKF_AD_OFF + SKF_AD_VLAN_TAG); }
215 | OP_LDH K_VLAN_AVAIL {
216 bpf_set_curr_instr(BPF_LD | BPF_H | BPF_ABS, 0, 0,
217 SKF_AD_OFF + SKF_AD_VLAN_TAG_PRESENT); }
218 | OP_LDH K_POFF {
219 bpf_set_curr_instr(BPF_LD | BPF_H | BPF_ABS, 0, 0,
220 SKF_AD_OFF + SKF_AD_PAY_OFFSET); }
221 | OP_LDH K_RAND {
222 bpf_set_curr_instr(BPF_LD | BPF_H | BPF_ABS, 0, 0,
223 SKF_AD_OFF + SKF_AD_RANDOM); }
224 | OP_LDH K_VLAN_TPID {
225 bpf_set_curr_instr(BPF_LD | BPF_H | BPF_ABS, 0, 0,
226 SKF_AD_OFF + SKF_AD_VLAN_TPID); }
227 ;
228
229 ldi
230 : OP_LDI '#' number {
231 bpf_set_curr_instr(BPF_LD | BPF_IMM, 0, 0, $3); }
232 | OP_LDI number {
233 bpf_set_curr_instr(BPF_LD | BPF_IMM, 0, 0, $2); }
234 ;
235
236 ld
237 : OP_LD '#' number {
238 bpf_set_curr_instr(BPF_LD | BPF_IMM, 0, 0, $3); }
239 | OP_LD K_PKT_LEN {
240 bpf_set_curr_instr(BPF_LD | BPF_W | BPF_LEN, 0, 0, 0); }
241 | OP_LD K_PROTO {
242 bpf_set_curr_instr(BPF_LD | BPF_W | BPF_ABS, 0, 0,
243 SKF_AD_OFF + SKF_AD_PROTOCOL); }
244 | OP_LD K_TYPE {
245 bpf_set_curr_instr(BPF_LD | BPF_W | BPF_ABS, 0, 0,
246 SKF_AD_OFF + SKF_AD_PKTTYPE); }
247 | OP_LD K_IFIDX {
248 bpf_set_curr_instr(BPF_LD | BPF_W | BPF_ABS, 0, 0,
249 SKF_AD_OFF + SKF_AD_IFINDEX); }
250 | OP_LD K_NLATTR {
251 bpf_set_curr_instr(BPF_LD | BPF_W | BPF_ABS, 0, 0,
252 SKF_AD_OFF + SKF_AD_NLATTR); }
253 | OP_LD K_NLATTR_NEST {
254 bpf_set_curr_instr(BPF_LD | BPF_W | BPF_ABS, 0, 0,
255 SKF_AD_OFF + SKF_AD_NLATTR_NEST); }
256 | OP_LD K_MARK {
257 bpf_set_curr_instr(BPF_LD | BPF_W | BPF_ABS, 0, 0,
258 SKF_AD_OFF + SKF_AD_MARK); }
259 | OP_LD K_QUEUE {
260 bpf_set_curr_instr(BPF_LD | BPF_W | BPF_ABS, 0, 0,
261 SKF_AD_OFF + SKF_AD_QUEUE); }
262 | OP_LD K_HATYPE {
263 bpf_set_curr_instr(BPF_LD | BPF_W | BPF_ABS, 0, 0,
264 SKF_AD_OFF + SKF_AD_HATYPE); }
265 | OP_LD K_RXHASH {
266 bpf_set_curr_instr(BPF_LD | BPF_W | BPF_ABS, 0, 0,
267 SKF_AD_OFF + SKF_AD_RXHASH); }
268 | OP_LD K_CPU {
269 bpf_set_curr_instr(BPF_LD | BPF_W | BPF_ABS, 0, 0,
270 SKF_AD_OFF + SKF_AD_CPU); }
271 | OP_LD K_VLAN_TCI {
272 bpf_set_curr_instr(BPF_LD | BPF_W | BPF_ABS, 0, 0,
273 SKF_AD_OFF + SKF_AD_VLAN_TAG); }
274 | OP_LD K_VLAN_AVAIL {
275 bpf_set_curr_instr(BPF_LD | BPF_W | BPF_ABS, 0, 0,
276 SKF_AD_OFF + SKF_AD_VLAN_TAG_PRESENT); }
277 | OP_LD K_POFF {
278 bpf_set_curr_instr(BPF_LD | BPF_W | BPF_ABS, 0, 0,
279 SKF_AD_OFF + SKF_AD_PAY_OFFSET); }
280 | OP_LD K_RAND {
281 bpf_set_curr_instr(BPF_LD | BPF_W | BPF_ABS, 0, 0,
282 SKF_AD_OFF + SKF_AD_RANDOM); }
283 | OP_LD K_VLAN_TPID {
284 bpf_set_curr_instr(BPF_LD | BPF_W | BPF_ABS, 0, 0,
285 SKF_AD_OFF + SKF_AD_VLAN_TPID); }
286 | OP_LD 'M' '[' number ']' {
287 bpf_set_curr_instr(BPF_LD | BPF_MEM, 0, 0, $4); }
288 | OP_LD '[' 'x' '+' number ']' {
289 bpf_set_curr_instr(BPF_LD | BPF_W | BPF_IND, 0, 0, $5); }
290 | OP_LD '[' '%' 'x' '+' number ']' {
291 bpf_set_curr_instr(BPF_LD | BPF_W | BPF_IND, 0, 0, $6); }
292 | OP_LD '[' number ']' {
293 bpf_set_curr_instr(BPF_LD | BPF_W | BPF_ABS, 0, 0, $3); }
294 ;
295
296 ldxi
297 : OP_LDXI '#' number {
298 bpf_set_curr_instr(BPF_LDX | BPF_IMM, 0, 0, $3); }
299 | OP_LDXI number {
300 bpf_set_curr_instr(BPF_LDX | BPF_IMM, 0, 0, $2); }
301 ;
302
303 ldx
304 : OP_LDX '#' number {
305 bpf_set_curr_instr(BPF_LDX | BPF_IMM, 0, 0, $3); }
306 | OP_LDX K_PKT_LEN {
307 bpf_set_curr_instr(BPF_LDX | BPF_W | BPF_LEN, 0, 0, 0); }
308 | OP_LDX 'M' '[' number ']' {
309 bpf_set_curr_instr(BPF_LDX | BPF_MEM, 0, 0, $4); }
310 | OP_LDXB number '*' '(' '[' number ']' '&' number ')' {
311 if ($2 != 4 || $9 != 0xf) {
312 fprintf(stderr, "ldxb offset not supported!\n");
313 exit(0);
314 } else {
315 bpf_set_curr_instr(BPF_LDX | BPF_MSH | BPF_B, 0, 0, $6); } }
316 | OP_LDX number '*' '(' '[' number ']' '&' number ')' {
317 if ($2 != 4 || $9 != 0xf) {
318 fprintf(stderr, "ldxb offset not supported!\n");
319 exit(0);
320 } else {
321 bpf_set_curr_instr(BPF_LDX | BPF_MSH | BPF_B, 0, 0, $6); } }
322 ;
323
324 st
325 : OP_ST 'M' '[' number ']' {
326 bpf_set_curr_instr(BPF_ST, 0, 0, $4); }
327 ;
328
329 stx
330 : OP_STX 'M' '[' number ']' {
331 bpf_set_curr_instr(BPF_STX, 0, 0, $4); }
332 ;
333
334 jmp
335 : OP_JMP label {
336 bpf_set_jmp_label($2, JKL);
337 bpf_set_curr_instr(BPF_JMP | BPF_JA, 0, 0, 0); }
338 ;
339
340 jeq
341 : OP_JEQ '#' number ',' label ',' label {
342 bpf_set_jmp_label($5, JTL);
343 bpf_set_jmp_label($7, JFL);
344 bpf_set_curr_instr(BPF_JMP | BPF_JEQ | BPF_K, 0, 0, $3); }
345 | OP_JEQ 'x' ',' label ',' label {
346 bpf_set_jmp_label($4, JTL);
347 bpf_set_jmp_label($6, JFL);
348 bpf_set_curr_instr(BPF_JMP | BPF_JEQ | BPF_X, 0, 0, 0); }
349 | OP_JEQ '%' 'x' ',' label ',' label {
350 bpf_set_jmp_label($5, JTL);
351 bpf_set_jmp_label($7, JFL);
352 bpf_set_curr_instr(BPF_JMP | BPF_JEQ | BPF_X, 0, 0, 0); }
353 | OP_JEQ '#' number ',' label {
354 bpf_set_jmp_label($5, JTL);
355 bpf_set_curr_instr(BPF_JMP | BPF_JEQ | BPF_K, 0, 0, $3); }
356 | OP_JEQ 'x' ',' label {
357 bpf_set_jmp_label($4, JTL);
358 bpf_set_curr_instr(BPF_JMP | BPF_JEQ | BPF_X, 0, 0, 0); }
359 | OP_JEQ '%' 'x' ',' label {
360 bpf_set_jmp_label($5, JTL);
361 bpf_set_curr_instr(BPF_JMP | BPF_JEQ | BPF_X, 0, 0, 0); }
362 ;
363
364 jneq
365 : OP_JNEQ '#' number ',' label {
366 bpf_set_jmp_label($5, JFL);
367 bpf_set_curr_instr(BPF_JMP | BPF_JEQ | BPF_K, 0, 0, $3); }
368 | OP_JNEQ 'x' ',' label {
369 bpf_set_jmp_label($4, JFL);
370 bpf_set_curr_instr(BPF_JMP | BPF_JEQ | BPF_X, 0, 0, 0); }
371 | OP_JNEQ '%' 'x' ',' label {
372 bpf_set_jmp_label($5, JFL);
373 bpf_set_curr_instr(BPF_JMP | BPF_JEQ | BPF_X, 0, 0, 0); }
374 ;
375
376 jlt
377 : OP_JLT '#' number ',' label {
378 bpf_set_jmp_label($5, JFL);
379 bpf_set_curr_instr(BPF_JMP | BPF_JGE | BPF_K, 0, 0, $3); }
380 | OP_JLT 'x' ',' label {
381 bpf_set_jmp_label($4, JFL);
382 bpf_set_curr_instr(BPF_JMP | BPF_JGE | BPF_X, 0, 0, 0); }
383 | OP_JLT '%' 'x' ',' label {
384 bpf_set_jmp_label($5, JFL);
385 bpf_set_curr_instr(BPF_JMP | BPF_JGE | BPF_X, 0, 0, 0); }
386 ;
387
388 jle
389 : OP_JLE '#' number ',' label {
390 bpf_set_jmp_label($5, JFL);
391 bpf_set_curr_instr(BPF_JMP | BPF_JGT | BPF_K, 0, 0, $3); }
392 | OP_JLE 'x' ',' label {
393 bpf_set_jmp_label($4, JFL);
394 bpf_set_curr_instr(BPF_JMP | BPF_JGT | BPF_X, 0, 0, 0); }
395 | OP_JLE '%' 'x' ',' label {
396 bpf_set_jmp_label($5, JFL);
397 bpf_set_curr_instr(BPF_JMP | BPF_JGT | BPF_X, 0, 0, 0); }
398 ;
399
400 jgt
401 : OP_JGT '#' number ',' label ',' label {
402 bpf_set_jmp_label($5, JTL);
403 bpf_set_jmp_label($7, JFL);
404 bpf_set_curr_instr(BPF_JMP | BPF_JGT | BPF_K, 0, 0, $3); }
405 | OP_JGT 'x' ',' label ',' label {
406 bpf_set_jmp_label($4, JTL);
407 bpf_set_jmp_label($6, JFL);
408 bpf_set_curr_instr(BPF_JMP | BPF_JGT | BPF_X, 0, 0, 0); }
409 | OP_JGT '%' 'x' ',' label ',' label {
410 bpf_set_jmp_label($5, JTL);
411 bpf_set_jmp_label($7, JFL);
412 bpf_set_curr_instr(BPF_JMP | BPF_JGT | BPF_X, 0, 0, 0); }
413 | OP_JGT '#' number ',' label {
414 bpf_set_jmp_label($5, JTL);
415 bpf_set_curr_instr(BPF_JMP | BPF_JGT | BPF_K, 0, 0, $3); }
416 | OP_JGT 'x' ',' label {
417 bpf_set_jmp_label($4, JTL);
418 bpf_set_curr_instr(BPF_JMP | BPF_JGT | BPF_X, 0, 0, 0); }
419 | OP_JGT '%' 'x' ',' label {
420 bpf_set_jmp_label($5, JTL);
421 bpf_set_curr_instr(BPF_JMP | BPF_JGT | BPF_X, 0, 0, 0); }
422 ;
423
424 jge
425 : OP_JGE '#' number ',' label ',' label {
426 bpf_set_jmp_label($5, JTL);
427 bpf_set_jmp_label($7, JFL);
428 bpf_set_curr_instr(BPF_JMP | BPF_JGE | BPF_K, 0, 0, $3); }
429 | OP_JGE 'x' ',' label ',' label {
430 bpf_set_jmp_label($4, JTL);
431 bpf_set_jmp_label($6, JFL);
432 bpf_set_curr_instr(BPF_JMP | BPF_JGE | BPF_X, 0, 0, 0); }
433 | OP_JGE '%' 'x' ',' label ',' label {
434 bpf_set_jmp_label($5, JTL);
435 bpf_set_jmp_label($7, JFL);
436 bpf_set_curr_instr(BPF_JMP | BPF_JGE | BPF_X, 0, 0, 0); }
437 | OP_JGE '#' number ',' label {
438 bpf_set_jmp_label($5, JTL);
439 bpf_set_curr_instr(BPF_JMP | BPF_JGE | BPF_K, 0, 0, $3); }
440 | OP_JGE 'x' ',' label {
441 bpf_set_jmp_label($4, JTL);
442 bpf_set_curr_instr(BPF_JMP | BPF_JGE | BPF_X, 0, 0, 0); }
443 | OP_JGE '%' 'x' ',' label {
444 bpf_set_jmp_label($5, JTL);
445 bpf_set_curr_instr(BPF_JMP | BPF_JGE | BPF_X, 0, 0, 0); }
446 ;
447
448 jset
449 : OP_JSET '#' number ',' label ',' label {
450 bpf_set_jmp_label($5, JTL);
451 bpf_set_jmp_label($7, JFL);
452 bpf_set_curr_instr(BPF_JMP | BPF_JSET | BPF_K, 0, 0, $3); }
453 | OP_JSET 'x' ',' label ',' label {
454 bpf_set_jmp_label($4, JTL);
455 bpf_set_jmp_label($6, JFL);
456 bpf_set_curr_instr(BPF_JMP | BPF_JSET | BPF_X, 0, 0, 0); }
457 | OP_JSET '%' 'x' ',' label ',' label {
458 bpf_set_jmp_label($5, JTL);
459 bpf_set_jmp_label($7, JFL);
460 bpf_set_curr_instr(BPF_JMP | BPF_JSET | BPF_X, 0, 0, 0); }
461 | OP_JSET '#' number ',' label {
462 bpf_set_jmp_label($5, JTL);
463 bpf_set_curr_instr(BPF_JMP | BPF_JSET | BPF_K, 0, 0, $3); }
464 | OP_JSET 'x' ',' label {
465 bpf_set_jmp_label($4, JTL);
466 bpf_set_curr_instr(BPF_JMP | BPF_JSET | BPF_X, 0, 0, 0); }
467 | OP_JSET '%' 'x' ',' label {
468 bpf_set_jmp_label($5, JTL);
469 bpf_set_curr_instr(BPF_JMP | BPF_JSET | BPF_X, 0, 0, 0); }
470 ;
471
472 add
473 : OP_ADD '#' number {
474 bpf_set_curr_instr(BPF_ALU | BPF_ADD | BPF_K, 0, 0, $3); }
475 | OP_ADD 'x' {
476 bpf_set_curr_instr(BPF_ALU | BPF_ADD | BPF_X, 0, 0, 0); }
477 | OP_ADD '%' 'x' {
478 bpf_set_curr_instr(BPF_ALU | BPF_ADD | BPF_X, 0, 0, 0); }
479 ;
480
481 sub
482 : OP_SUB '#' number {
483 bpf_set_curr_instr(BPF_ALU | BPF_SUB | BPF_K, 0, 0, $3); }
484 | OP_SUB 'x' {
485 bpf_set_curr_instr(BPF_ALU | BPF_SUB | BPF_X, 0, 0, 0); }
486 | OP_SUB '%' 'x' {
487 bpf_set_curr_instr(BPF_ALU | BPF_SUB | BPF_X, 0, 0, 0); }
488 ;
489
490 mul
491 : OP_MUL '#' number {
492 bpf_set_curr_instr(BPF_ALU | BPF_MUL | BPF_K, 0, 0, $3); }
493 | OP_MUL 'x' {
494 bpf_set_curr_instr(BPF_ALU | BPF_MUL | BPF_X, 0, 0, 0); }
495 | OP_MUL '%' 'x' {
496 bpf_set_curr_instr(BPF_ALU | BPF_MUL | BPF_X, 0, 0, 0); }
497 ;
498
499 div
500 : OP_DIV '#' number {
501 bpf_set_curr_instr(BPF_ALU | BPF_DIV | BPF_K, 0, 0, $3); }
502 | OP_DIV 'x' {
503 bpf_set_curr_instr(BPF_ALU | BPF_DIV | BPF_X, 0, 0, 0); }
504 | OP_DIV '%' 'x' {
505 bpf_set_curr_instr(BPF_ALU | BPF_DIV | BPF_X, 0, 0, 0); }
506 ;
507
508 mod
509 : OP_MOD '#' number {
510 bpf_set_curr_instr(BPF_ALU | BPF_MOD | BPF_K, 0, 0, $3); }
511 | OP_MOD 'x' {
512 bpf_set_curr_instr(BPF_ALU | BPF_MOD | BPF_X, 0, 0, 0); }
513 | OP_MOD '%' 'x' {
514 bpf_set_curr_instr(BPF_ALU | BPF_MOD | BPF_X, 0, 0, 0); }
515 ;
516
517 neg
518 : OP_NEG {
519 bpf_set_curr_instr(BPF_ALU | BPF_NEG, 0, 0, 0); }
520 ;
521
522 and
523 : OP_AND '#' number {
524 bpf_set_curr_instr(BPF_ALU | BPF_AND | BPF_K, 0, 0, $3); }
525 | OP_AND 'x' {
526 bpf_set_curr_instr(BPF_ALU | BPF_AND | BPF_X, 0, 0, 0); }
527 | OP_AND '%' 'x' {
528 bpf_set_curr_instr(BPF_ALU | BPF_AND | BPF_X, 0, 0, 0); }
529 ;
530
531 or
532 : OP_OR '#' number {
533 bpf_set_curr_instr(BPF_ALU | BPF_OR | BPF_K, 0, 0, $3); }
534 | OP_OR 'x' {
535 bpf_set_curr_instr(BPF_ALU | BPF_OR | BPF_X, 0, 0, 0); }
536 | OP_OR '%' 'x' {
537 bpf_set_curr_instr(BPF_ALU | BPF_OR | BPF_X, 0, 0, 0); }
538 ;
539
540 xor
541 : OP_XOR '#' number {
542 bpf_set_curr_instr(BPF_ALU | BPF_XOR | BPF_K, 0, 0, $3); }
543 | OP_XOR 'x' {
544 bpf_set_curr_instr(BPF_ALU | BPF_XOR | BPF_X, 0, 0, 0); }
545 | OP_XOR '%' 'x' {
546 bpf_set_curr_instr(BPF_ALU | BPF_XOR | BPF_X, 0, 0, 0); }
547 ;
548
549 lsh
550 : OP_LSH '#' number {
551 bpf_set_curr_instr(BPF_ALU | BPF_LSH | BPF_K, 0, 0, $3); }
552 | OP_LSH 'x' {
553 bpf_set_curr_instr(BPF_ALU | BPF_LSH | BPF_X, 0, 0, 0); }
554 | OP_LSH '%' 'x' {
555 bpf_set_curr_instr(BPF_ALU | BPF_LSH | BPF_X, 0, 0, 0); }
556 ;
557
558 rsh
559 : OP_RSH '#' number {
560 bpf_set_curr_instr(BPF_ALU | BPF_RSH | BPF_K, 0, 0, $3); }
561 | OP_RSH 'x' {
562 bpf_set_curr_instr(BPF_ALU | BPF_RSH | BPF_X, 0, 0, 0); }
563 | OP_RSH '%' 'x' {
564 bpf_set_curr_instr(BPF_ALU | BPF_RSH | BPF_X, 0, 0, 0); }
565 ;
566
567 ret
568 : OP_RET 'a' {
569 bpf_set_curr_instr(BPF_RET | BPF_A, 0, 0, 0); }
570 | OP_RET '%' 'a' {
571 bpf_set_curr_instr(BPF_RET | BPF_A, 0, 0, 0); }
572 | OP_RET 'x' {
573 bpf_set_curr_instr(BPF_RET | BPF_X, 0, 0, 0); }
574 | OP_RET '%' 'x' {
575 bpf_set_curr_instr(BPF_RET | BPF_X, 0, 0, 0); }
576 | OP_RET '#' number {
577 bpf_set_curr_instr(BPF_RET | BPF_K, 0, 0, $3); }
578 ;
579
580 tax
581 : OP_TAX {
582 bpf_set_curr_instr(BPF_MISC | BPF_TAX, 0, 0, 0); }
583 ;
584
585 txa
586 : OP_TXA {
587 bpf_set_curr_instr(BPF_MISC | BPF_TXA, 0, 0, 0); }
588 ;
589
590 %%
591
592 static int curr_instr = 0;
593 static struct sock_filter out[BPF_MAXINSNS];
594 static char **labels, **labels_jt, **labels_jf, **labels_k;
595
bpf_assert_max(void)596 static void bpf_assert_max(void)
597 {
598 if (curr_instr >= BPF_MAXINSNS) {
599 fprintf(stderr, "only max %u insns allowed!\n", BPF_MAXINSNS);
600 exit(0);
601 }
602 }
603
bpf_set_curr_instr(uint16_t code,uint8_t jt,uint8_t jf,uint32_t k)604 static void bpf_set_curr_instr(uint16_t code, uint8_t jt, uint8_t jf,
605 uint32_t k)
606 {
607 bpf_assert_max();
608 out[curr_instr].code = code;
609 out[curr_instr].jt = jt;
610 out[curr_instr].jf = jf;
611 out[curr_instr].k = k;
612 curr_instr++;
613 }
614
bpf_set_curr_label(char * label)615 static void bpf_set_curr_label(char *label)
616 {
617 bpf_assert_max();
618 labels[curr_instr] = label;
619 }
620
bpf_set_jmp_label(char * label,enum jmp_type type)621 static void bpf_set_jmp_label(char *label, enum jmp_type type)
622 {
623 bpf_assert_max();
624 switch (type) {
625 case JTL:
626 labels_jt[curr_instr] = label;
627 break;
628 case JFL:
629 labels_jf[curr_instr] = label;
630 break;
631 case JKL:
632 labels_k[curr_instr] = label;
633 break;
634 }
635 }
636
bpf_find_insns_offset(const char * label)637 static int bpf_find_insns_offset(const char *label)
638 {
639 int i, max = curr_instr, ret = -ENOENT;
640
641 for (i = 0; i < max; i++) {
642 if (labels[i] && !strcmp(label, labels[i])) {
643 ret = i;
644 break;
645 }
646 }
647
648 if (ret == -ENOENT) {
649 fprintf(stderr, "no such label \'%s\'!\n", label);
650 exit(0);
651 }
652
653 return ret;
654 }
655
bpf_stage_1_insert_insns(void)656 static void bpf_stage_1_insert_insns(void)
657 {
658 yyparse();
659 }
660
bpf_reduce_k_jumps(void)661 static void bpf_reduce_k_jumps(void)
662 {
663 int i;
664
665 for (i = 0; i < curr_instr; i++) {
666 if (labels_k[i]) {
667 int off = bpf_find_insns_offset(labels_k[i]);
668 out[i].k = (uint32_t) (off - i - 1);
669 }
670 }
671 }
672
bpf_reduce_jt_jumps(void)673 static void bpf_reduce_jt_jumps(void)
674 {
675 int i;
676
677 for (i = 0; i < curr_instr; i++) {
678 if (labels_jt[i]) {
679 int off = bpf_find_insns_offset(labels_jt[i]);
680 out[i].jt = (uint8_t) (off - i -1);
681 }
682 }
683 }
684
bpf_reduce_jf_jumps(void)685 static void bpf_reduce_jf_jumps(void)
686 {
687 int i;
688
689 for (i = 0; i < curr_instr; i++) {
690 if (labels_jf[i]) {
691 int off = bpf_find_insns_offset(labels_jf[i]);
692 out[i].jf = (uint8_t) (off - i - 1);
693 }
694 }
695 }
696
bpf_stage_2_reduce_labels(void)697 static void bpf_stage_2_reduce_labels(void)
698 {
699 bpf_reduce_k_jumps();
700 bpf_reduce_jt_jumps();
701 bpf_reduce_jf_jumps();
702 }
703
bpf_pretty_print_c(void)704 static void bpf_pretty_print_c(void)
705 {
706 int i;
707
708 for (i = 0; i < curr_instr; i++)
709 printf("{ %#04x, %2u, %2u, %#010x },\n", out[i].code,
710 out[i].jt, out[i].jf, out[i].k);
711 }
712
bpf_pretty_print(void)713 static void bpf_pretty_print(void)
714 {
715 int i;
716
717 printf("%u,", curr_instr);
718 for (i = 0; i < curr_instr; i++)
719 printf("%u %u %u %u,", out[i].code,
720 out[i].jt, out[i].jf, out[i].k);
721 printf("\n");
722 }
723
bpf_init(void)724 static void bpf_init(void)
725 {
726 memset(out, 0, sizeof(out));
727
728 labels = calloc(BPF_MAXINSNS, sizeof(*labels));
729 assert(labels);
730 labels_jt = calloc(BPF_MAXINSNS, sizeof(*labels_jt));
731 assert(labels_jt);
732 labels_jf = calloc(BPF_MAXINSNS, sizeof(*labels_jf));
733 assert(labels_jf);
734 labels_k = calloc(BPF_MAXINSNS, sizeof(*labels_k));
735 assert(labels_k);
736 }
737
bpf_destroy_labels(void)738 static void bpf_destroy_labels(void)
739 {
740 int i;
741
742 for (i = 0; i < curr_instr; i++) {
743 free(labels_jf[i]);
744 free(labels_jt[i]);
745 free(labels_k[i]);
746 free(labels[i]);
747 }
748 }
749
bpf_destroy(void)750 static void bpf_destroy(void)
751 {
752 bpf_destroy_labels();
753 free(labels_jt);
754 free(labels_jf);
755 free(labels_k);
756 free(labels);
757 }
758
bpf_asm_compile(FILE * fp,bool cstyle)759 void bpf_asm_compile(FILE *fp, bool cstyle)
760 {
761 yyin = fp;
762
763 bpf_init();
764 bpf_stage_1_insert_insns();
765 bpf_stage_2_reduce_labels();
766 bpf_destroy();
767
768 if (cstyle)
769 bpf_pretty_print_c();
770 else
771 bpf_pretty_print();
772
773 if (fp != stdin)
774 fclose(yyin);
775 }
776
yyerror(const char * str)777 void yyerror(const char *str)
778 {
779 exit(1);
780 }
781