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_VLANT K_VLANP 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_VLANT {
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_VLANP {
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 ;
171
172 ldh
173 : OP_LDH '[' 'x' '+' number ']' {
174 bpf_set_curr_instr(BPF_LD | BPF_H | BPF_IND, 0, 0, $5); }
175 | OP_LDH '[' '%' 'x' '+' number ']' {
176 bpf_set_curr_instr(BPF_LD | BPF_H | BPF_IND, 0, 0, $6); }
177 | OP_LDH '[' number ']' {
178 bpf_set_curr_instr(BPF_LD | BPF_H | BPF_ABS, 0, 0, $3); }
179 | OP_LDH K_PROTO {
180 bpf_set_curr_instr(BPF_LD | BPF_H | BPF_ABS, 0, 0,
181 SKF_AD_OFF + SKF_AD_PROTOCOL); }
182 | OP_LDH K_TYPE {
183 bpf_set_curr_instr(BPF_LD | BPF_H | BPF_ABS, 0, 0,
184 SKF_AD_OFF + SKF_AD_PKTTYPE); }
185 | OP_LDH K_IFIDX {
186 bpf_set_curr_instr(BPF_LD | BPF_H | BPF_ABS, 0, 0,
187 SKF_AD_OFF + SKF_AD_IFINDEX); }
188 | OP_LDH K_NLATTR {
189 bpf_set_curr_instr(BPF_LD | BPF_H | BPF_ABS, 0, 0,
190 SKF_AD_OFF + SKF_AD_NLATTR); }
191 | OP_LDH K_NLATTR_NEST {
192 bpf_set_curr_instr(BPF_LD | BPF_H | BPF_ABS, 0, 0,
193 SKF_AD_OFF + SKF_AD_NLATTR_NEST); }
194 | OP_LDH K_MARK {
195 bpf_set_curr_instr(BPF_LD | BPF_H | BPF_ABS, 0, 0,
196 SKF_AD_OFF + SKF_AD_MARK); }
197 | OP_LDH K_QUEUE {
198 bpf_set_curr_instr(BPF_LD | BPF_H | BPF_ABS, 0, 0,
199 SKF_AD_OFF + SKF_AD_QUEUE); }
200 | OP_LDH K_HATYPE {
201 bpf_set_curr_instr(BPF_LD | BPF_H | BPF_ABS, 0, 0,
202 SKF_AD_OFF + SKF_AD_HATYPE); }
203 | OP_LDH K_RXHASH {
204 bpf_set_curr_instr(BPF_LD | BPF_H | BPF_ABS, 0, 0,
205 SKF_AD_OFF + SKF_AD_RXHASH); }
206 | OP_LDH K_CPU {
207 bpf_set_curr_instr(BPF_LD | BPF_H | BPF_ABS, 0, 0,
208 SKF_AD_OFF + SKF_AD_CPU); }
209 | OP_LDH K_VLANT {
210 bpf_set_curr_instr(BPF_LD | BPF_H | BPF_ABS, 0, 0,
211 SKF_AD_OFF + SKF_AD_VLAN_TAG); }
212 | OP_LDH K_VLANP {
213 bpf_set_curr_instr(BPF_LD | BPF_H | BPF_ABS, 0, 0,
214 SKF_AD_OFF + SKF_AD_VLAN_TAG_PRESENT); }
215 | OP_LDH K_POFF {
216 bpf_set_curr_instr(BPF_LD | BPF_H | BPF_ABS, 0, 0,
217 SKF_AD_OFF + SKF_AD_PAY_OFFSET); }
218 | OP_LDH K_RAND {
219 bpf_set_curr_instr(BPF_LD | BPF_H | BPF_ABS, 0, 0,
220 SKF_AD_OFF + SKF_AD_RANDOM); }
221 ;
222
223 ldi
224 : OP_LDI '#' number {
225 bpf_set_curr_instr(BPF_LD | BPF_IMM, 0, 0, $3); }
226 | OP_LDI number {
227 bpf_set_curr_instr(BPF_LD | BPF_IMM, 0, 0, $2); }
228 ;
229
230 ld
231 : OP_LD '#' number {
232 bpf_set_curr_instr(BPF_LD | BPF_IMM, 0, 0, $3); }
233 | OP_LD K_PKT_LEN {
234 bpf_set_curr_instr(BPF_LD | BPF_W | BPF_LEN, 0, 0, 0); }
235 | OP_LD K_PROTO {
236 bpf_set_curr_instr(BPF_LD | BPF_W | BPF_ABS, 0, 0,
237 SKF_AD_OFF + SKF_AD_PROTOCOL); }
238 | OP_LD K_TYPE {
239 bpf_set_curr_instr(BPF_LD | BPF_W | BPF_ABS, 0, 0,
240 SKF_AD_OFF + SKF_AD_PKTTYPE); }
241 | OP_LD K_IFIDX {
242 bpf_set_curr_instr(BPF_LD | BPF_W | BPF_ABS, 0, 0,
243 SKF_AD_OFF + SKF_AD_IFINDEX); }
244 | OP_LD K_NLATTR {
245 bpf_set_curr_instr(BPF_LD | BPF_W | BPF_ABS, 0, 0,
246 SKF_AD_OFF + SKF_AD_NLATTR); }
247 | OP_LD K_NLATTR_NEST {
248 bpf_set_curr_instr(BPF_LD | BPF_W | BPF_ABS, 0, 0,
249 SKF_AD_OFF + SKF_AD_NLATTR_NEST); }
250 | OP_LD K_MARK {
251 bpf_set_curr_instr(BPF_LD | BPF_W | BPF_ABS, 0, 0,
252 SKF_AD_OFF + SKF_AD_MARK); }
253 | OP_LD K_QUEUE {
254 bpf_set_curr_instr(BPF_LD | BPF_W | BPF_ABS, 0, 0,
255 SKF_AD_OFF + SKF_AD_QUEUE); }
256 | OP_LD K_HATYPE {
257 bpf_set_curr_instr(BPF_LD | BPF_W | BPF_ABS, 0, 0,
258 SKF_AD_OFF + SKF_AD_HATYPE); }
259 | OP_LD K_RXHASH {
260 bpf_set_curr_instr(BPF_LD | BPF_W | BPF_ABS, 0, 0,
261 SKF_AD_OFF + SKF_AD_RXHASH); }
262 | OP_LD K_CPU {
263 bpf_set_curr_instr(BPF_LD | BPF_W | BPF_ABS, 0, 0,
264 SKF_AD_OFF + SKF_AD_CPU); }
265 | OP_LD K_VLANT {
266 bpf_set_curr_instr(BPF_LD | BPF_W | BPF_ABS, 0, 0,
267 SKF_AD_OFF + SKF_AD_VLAN_TAG); }
268 | OP_LD K_VLANP {
269 bpf_set_curr_instr(BPF_LD | BPF_W | BPF_ABS, 0, 0,
270 SKF_AD_OFF + SKF_AD_VLAN_TAG_PRESENT); }
271 | OP_LD K_POFF {
272 bpf_set_curr_instr(BPF_LD | BPF_W | BPF_ABS, 0, 0,
273 SKF_AD_OFF + SKF_AD_PAY_OFFSET); }
274 | OP_LD K_RAND {
275 bpf_set_curr_instr(BPF_LD | BPF_W | BPF_ABS, 0, 0,
276 SKF_AD_OFF + SKF_AD_RANDOM); }
277 | OP_LD 'M' '[' number ']' {
278 bpf_set_curr_instr(BPF_LD | BPF_MEM, 0, 0, $4); }
279 | OP_LD '[' 'x' '+' number ']' {
280 bpf_set_curr_instr(BPF_LD | BPF_W | BPF_IND, 0, 0, $5); }
281 | OP_LD '[' '%' 'x' '+' number ']' {
282 bpf_set_curr_instr(BPF_LD | BPF_W | BPF_IND, 0, 0, $6); }
283 | OP_LD '[' number ']' {
284 bpf_set_curr_instr(BPF_LD | BPF_W | BPF_ABS, 0, 0, $3); }
285 ;
286
287 ldxi
288 : OP_LDXI '#' number {
289 bpf_set_curr_instr(BPF_LDX | BPF_IMM, 0, 0, $3); }
290 | OP_LDXI number {
291 bpf_set_curr_instr(BPF_LDX | BPF_IMM, 0, 0, $2); }
292 ;
293
294 ldx
295 : OP_LDX '#' number {
296 bpf_set_curr_instr(BPF_LDX | BPF_IMM, 0, 0, $3); }
297 | OP_LDX K_PKT_LEN {
298 bpf_set_curr_instr(BPF_LDX | BPF_W | BPF_LEN, 0, 0, 0); }
299 | OP_LDX 'M' '[' number ']' {
300 bpf_set_curr_instr(BPF_LDX | BPF_MEM, 0, 0, $4); }
301 | OP_LDXB number '*' '(' '[' number ']' '&' number ')' {
302 if ($2 != 4 || $9 != 0xf) {
303 fprintf(stderr, "ldxb offset not supported!\n");
304 exit(0);
305 } else {
306 bpf_set_curr_instr(BPF_LDX | BPF_MSH | BPF_B, 0, 0, $6); } }
307 | OP_LDX number '*' '(' '[' number ']' '&' number ')' {
308 if ($2 != 4 || $9 != 0xf) {
309 fprintf(stderr, "ldxb offset not supported!\n");
310 exit(0);
311 } else {
312 bpf_set_curr_instr(BPF_LDX | BPF_MSH | BPF_B, 0, 0, $6); } }
313 ;
314
315 st
316 : OP_ST 'M' '[' number ']' {
317 bpf_set_curr_instr(BPF_ST, 0, 0, $4); }
318 ;
319
320 stx
321 : OP_STX 'M' '[' number ']' {
322 bpf_set_curr_instr(BPF_STX, 0, 0, $4); }
323 ;
324
325 jmp
326 : OP_JMP label {
327 bpf_set_jmp_label($2, JKL);
328 bpf_set_curr_instr(BPF_JMP | BPF_JA, 0, 0, 0); }
329 ;
330
331 jeq
332 : OP_JEQ '#' number ',' label ',' label {
333 bpf_set_jmp_label($5, JTL);
334 bpf_set_jmp_label($7, JFL);
335 bpf_set_curr_instr(BPF_JMP | BPF_JEQ | BPF_K, 0, 0, $3); }
336 | OP_JEQ 'x' ',' label ',' label {
337 bpf_set_jmp_label($4, JTL);
338 bpf_set_jmp_label($6, JFL);
339 bpf_set_curr_instr(BPF_JMP | BPF_JEQ | BPF_X, 0, 0, 0); }
340 | OP_JEQ '%' 'x' ',' label ',' label {
341 bpf_set_jmp_label($5, JTL);
342 bpf_set_jmp_label($7, JFL);
343 bpf_set_curr_instr(BPF_JMP | BPF_JEQ | BPF_X, 0, 0, 0); }
344 | OP_JEQ '#' number ',' label {
345 bpf_set_jmp_label($5, JTL);
346 bpf_set_curr_instr(BPF_JMP | BPF_JEQ | BPF_K, 0, 0, $3); }
347 | OP_JEQ 'x' ',' label {
348 bpf_set_jmp_label($4, JTL);
349 bpf_set_curr_instr(BPF_JMP | BPF_JEQ | BPF_X, 0, 0, 0); }
350 | OP_JEQ '%' 'x' ',' label {
351 bpf_set_jmp_label($5, JTL);
352 bpf_set_curr_instr(BPF_JMP | BPF_JEQ | BPF_X, 0, 0, 0); }
353 ;
354
355 jneq
356 : OP_JNEQ '#' number ',' label {
357 bpf_set_jmp_label($5, JFL);
358 bpf_set_curr_instr(BPF_JMP | BPF_JEQ | BPF_K, 0, 0, $3); }
359 | OP_JNEQ 'x' ',' label {
360 bpf_set_jmp_label($4, JFL);
361 bpf_set_curr_instr(BPF_JMP | BPF_JEQ | BPF_X, 0, 0, 0); }
362 | OP_JNEQ '%' 'x' ',' label {
363 bpf_set_jmp_label($5, JFL);
364 bpf_set_curr_instr(BPF_JMP | BPF_JEQ | BPF_X, 0, 0, 0); }
365 ;
366
367 jlt
368 : OP_JLT '#' number ',' label {
369 bpf_set_jmp_label($5, JFL);
370 bpf_set_curr_instr(BPF_JMP | BPF_JGE | BPF_K, 0, 0, $3); }
371 | OP_JLT 'x' ',' label {
372 bpf_set_jmp_label($4, JFL);
373 bpf_set_curr_instr(BPF_JMP | BPF_JGE | BPF_X, 0, 0, 0); }
374 | OP_JLT '%' 'x' ',' label {
375 bpf_set_jmp_label($5, JFL);
376 bpf_set_curr_instr(BPF_JMP | BPF_JGE | BPF_X, 0, 0, 0); }
377 ;
378
379 jle
380 : OP_JLE '#' number ',' label {
381 bpf_set_jmp_label($5, JFL);
382 bpf_set_curr_instr(BPF_JMP | BPF_JGT | BPF_K, 0, 0, $3); }
383 | OP_JLE 'x' ',' label {
384 bpf_set_jmp_label($4, JFL);
385 bpf_set_curr_instr(BPF_JMP | BPF_JGT | BPF_X, 0, 0, 0); }
386 | OP_JLE '%' 'x' ',' label {
387 bpf_set_jmp_label($5, JFL);
388 bpf_set_curr_instr(BPF_JMP | BPF_JGT | BPF_X, 0, 0, 0); }
389 ;
390
391 jgt
392 : OP_JGT '#' number ',' label ',' label {
393 bpf_set_jmp_label($5, JTL);
394 bpf_set_jmp_label($7, JFL);
395 bpf_set_curr_instr(BPF_JMP | BPF_JGT | BPF_K, 0, 0, $3); }
396 | OP_JGT 'x' ',' label ',' label {
397 bpf_set_jmp_label($4, JTL);
398 bpf_set_jmp_label($6, JFL);
399 bpf_set_curr_instr(BPF_JMP | BPF_JGT | BPF_X, 0, 0, 0); }
400 | OP_JGT '%' 'x' ',' label ',' label {
401 bpf_set_jmp_label($5, JTL);
402 bpf_set_jmp_label($7, JFL);
403 bpf_set_curr_instr(BPF_JMP | BPF_JGT | BPF_X, 0, 0, 0); }
404 | OP_JGT '#' number ',' label {
405 bpf_set_jmp_label($5, JTL);
406 bpf_set_curr_instr(BPF_JMP | BPF_JGT | BPF_K, 0, 0, $3); }
407 | OP_JGT 'x' ',' label {
408 bpf_set_jmp_label($4, JTL);
409 bpf_set_curr_instr(BPF_JMP | BPF_JGT | BPF_X, 0, 0, 0); }
410 | OP_JGT '%' 'x' ',' label {
411 bpf_set_jmp_label($5, JTL);
412 bpf_set_curr_instr(BPF_JMP | BPF_JGT | BPF_X, 0, 0, 0); }
413 ;
414
415 jge
416 : OP_JGE '#' number ',' label ',' label {
417 bpf_set_jmp_label($5, JTL);
418 bpf_set_jmp_label($7, JFL);
419 bpf_set_curr_instr(BPF_JMP | BPF_JGE | BPF_K, 0, 0, $3); }
420 | OP_JGE 'x' ',' label ',' label {
421 bpf_set_jmp_label($4, JTL);
422 bpf_set_jmp_label($6, JFL);
423 bpf_set_curr_instr(BPF_JMP | BPF_JGE | BPF_X, 0, 0, 0); }
424 | OP_JGE '%' 'x' ',' label ',' label {
425 bpf_set_jmp_label($5, JTL);
426 bpf_set_jmp_label($7, JFL);
427 bpf_set_curr_instr(BPF_JMP | BPF_JGE | BPF_X, 0, 0, 0); }
428 | OP_JGE '#' number ',' label {
429 bpf_set_jmp_label($5, JTL);
430 bpf_set_curr_instr(BPF_JMP | BPF_JGE | BPF_K, 0, 0, $3); }
431 | OP_JGE 'x' ',' label {
432 bpf_set_jmp_label($4, JTL);
433 bpf_set_curr_instr(BPF_JMP | BPF_JGE | BPF_X, 0, 0, 0); }
434 | OP_JGE '%' 'x' ',' label {
435 bpf_set_jmp_label($5, JTL);
436 bpf_set_curr_instr(BPF_JMP | BPF_JGE | BPF_X, 0, 0, 0); }
437 ;
438
439 jset
440 : OP_JSET '#' number ',' label ',' label {
441 bpf_set_jmp_label($5, JTL);
442 bpf_set_jmp_label($7, JFL);
443 bpf_set_curr_instr(BPF_JMP | BPF_JSET | BPF_K, 0, 0, $3); }
444 | OP_JSET 'x' ',' label ',' label {
445 bpf_set_jmp_label($4, JTL);
446 bpf_set_jmp_label($6, JFL);
447 bpf_set_curr_instr(BPF_JMP | BPF_JSET | BPF_X, 0, 0, 0); }
448 | OP_JSET '%' 'x' ',' label ',' label {
449 bpf_set_jmp_label($5, JTL);
450 bpf_set_jmp_label($7, JFL);
451 bpf_set_curr_instr(BPF_JMP | BPF_JSET | BPF_X, 0, 0, 0); }
452 | OP_JSET '#' number ',' label {
453 bpf_set_jmp_label($5, JTL);
454 bpf_set_curr_instr(BPF_JMP | BPF_JSET | BPF_K, 0, 0, $3); }
455 | OP_JSET 'x' ',' label {
456 bpf_set_jmp_label($4, JTL);
457 bpf_set_curr_instr(BPF_JMP | BPF_JSET | BPF_X, 0, 0, 0); }
458 | OP_JSET '%' 'x' ',' label {
459 bpf_set_jmp_label($5, JTL);
460 bpf_set_curr_instr(BPF_JMP | BPF_JSET | BPF_X, 0, 0, 0); }
461 ;
462
463 add
464 : OP_ADD '#' number {
465 bpf_set_curr_instr(BPF_ALU | BPF_ADD | BPF_K, 0, 0, $3); }
466 | OP_ADD 'x' {
467 bpf_set_curr_instr(BPF_ALU | BPF_ADD | BPF_X, 0, 0, 0); }
468 | OP_ADD '%' 'x' {
469 bpf_set_curr_instr(BPF_ALU | BPF_ADD | BPF_X, 0, 0, 0); }
470 ;
471
472 sub
473 : OP_SUB '#' number {
474 bpf_set_curr_instr(BPF_ALU | BPF_SUB | BPF_K, 0, 0, $3); }
475 | OP_SUB 'x' {
476 bpf_set_curr_instr(BPF_ALU | BPF_SUB | BPF_X, 0, 0, 0); }
477 | OP_SUB '%' 'x' {
478 bpf_set_curr_instr(BPF_ALU | BPF_SUB | BPF_X, 0, 0, 0); }
479 ;
480
481 mul
482 : OP_MUL '#' number {
483 bpf_set_curr_instr(BPF_ALU | BPF_MUL | BPF_K, 0, 0, $3); }
484 | OP_MUL 'x' {
485 bpf_set_curr_instr(BPF_ALU | BPF_MUL | BPF_X, 0, 0, 0); }
486 | OP_MUL '%' 'x' {
487 bpf_set_curr_instr(BPF_ALU | BPF_MUL | BPF_X, 0, 0, 0); }
488 ;
489
490 div
491 : OP_DIV '#' number {
492 bpf_set_curr_instr(BPF_ALU | BPF_DIV | BPF_K, 0, 0, $3); }
493 | OP_DIV 'x' {
494 bpf_set_curr_instr(BPF_ALU | BPF_DIV | BPF_X, 0, 0, 0); }
495 | OP_DIV '%' 'x' {
496 bpf_set_curr_instr(BPF_ALU | BPF_DIV | BPF_X, 0, 0, 0); }
497 ;
498
499 mod
500 : OP_MOD '#' number {
501 bpf_set_curr_instr(BPF_ALU | BPF_MOD | BPF_K, 0, 0, $3); }
502 | OP_MOD 'x' {
503 bpf_set_curr_instr(BPF_ALU | BPF_MOD | BPF_X, 0, 0, 0); }
504 | OP_MOD '%' 'x' {
505 bpf_set_curr_instr(BPF_ALU | BPF_MOD | BPF_X, 0, 0, 0); }
506 ;
507
508 neg
509 : OP_NEG {
510 bpf_set_curr_instr(BPF_ALU | BPF_NEG, 0, 0, 0); }
511 ;
512
513 and
514 : OP_AND '#' number {
515 bpf_set_curr_instr(BPF_ALU | BPF_AND | BPF_K, 0, 0, $3); }
516 | OP_AND 'x' {
517 bpf_set_curr_instr(BPF_ALU | BPF_AND | BPF_X, 0, 0, 0); }
518 | OP_AND '%' 'x' {
519 bpf_set_curr_instr(BPF_ALU | BPF_AND | BPF_X, 0, 0, 0); }
520 ;
521
522 or
523 : OP_OR '#' number {
524 bpf_set_curr_instr(BPF_ALU | BPF_OR | BPF_K, 0, 0, $3); }
525 | OP_OR 'x' {
526 bpf_set_curr_instr(BPF_ALU | BPF_OR | BPF_X, 0, 0, 0); }
527 | OP_OR '%' 'x' {
528 bpf_set_curr_instr(BPF_ALU | BPF_OR | BPF_X, 0, 0, 0); }
529 ;
530
531 xor
532 : OP_XOR '#' number {
533 bpf_set_curr_instr(BPF_ALU | BPF_XOR | BPF_K, 0, 0, $3); }
534 | OP_XOR 'x' {
535 bpf_set_curr_instr(BPF_ALU | BPF_XOR | BPF_X, 0, 0, 0); }
536 | OP_XOR '%' 'x' {
537 bpf_set_curr_instr(BPF_ALU | BPF_XOR | BPF_X, 0, 0, 0); }
538 ;
539
540 lsh
541 : OP_LSH '#' number {
542 bpf_set_curr_instr(BPF_ALU | BPF_LSH | BPF_K, 0, 0, $3); }
543 | OP_LSH 'x' {
544 bpf_set_curr_instr(BPF_ALU | BPF_LSH | BPF_X, 0, 0, 0); }
545 | OP_LSH '%' 'x' {
546 bpf_set_curr_instr(BPF_ALU | BPF_LSH | BPF_X, 0, 0, 0); }
547 ;
548
549 rsh
550 : OP_RSH '#' number {
551 bpf_set_curr_instr(BPF_ALU | BPF_RSH | BPF_K, 0, 0, $3); }
552 | OP_RSH 'x' {
553 bpf_set_curr_instr(BPF_ALU | BPF_RSH | BPF_X, 0, 0, 0); }
554 | OP_RSH '%' 'x' {
555 bpf_set_curr_instr(BPF_ALU | BPF_RSH | BPF_X, 0, 0, 0); }
556 ;
557
558 ret
559 : OP_RET 'a' {
560 bpf_set_curr_instr(BPF_RET | BPF_A, 0, 0, 0); }
561 | OP_RET '%' 'a' {
562 bpf_set_curr_instr(BPF_RET | BPF_A, 0, 0, 0); }
563 | OP_RET 'x' {
564 bpf_set_curr_instr(BPF_RET | BPF_X, 0, 0, 0); }
565 | OP_RET '%' 'x' {
566 bpf_set_curr_instr(BPF_RET | BPF_X, 0, 0, 0); }
567 | OP_RET '#' number {
568 bpf_set_curr_instr(BPF_RET | BPF_K, 0, 0, $3); }
569 ;
570
571 tax
572 : OP_TAX {
573 bpf_set_curr_instr(BPF_MISC | BPF_TAX, 0, 0, 0); }
574 ;
575
576 txa
577 : OP_TXA {
578 bpf_set_curr_instr(BPF_MISC | BPF_TXA, 0, 0, 0); }
579 ;
580
581 %%
582
583 static int curr_instr = 0;
584 static struct sock_filter out[BPF_MAXINSNS];
585 static char **labels, **labels_jt, **labels_jf, **labels_k;
586
587 static void bpf_assert_max(void)
588 {
589 if (curr_instr >= BPF_MAXINSNS) {
590 fprintf(stderr, "only max %u insns allowed!\n", BPF_MAXINSNS);
591 exit(0);
592 }
593 }
594
595 static void bpf_set_curr_instr(uint16_t code, uint8_t jt, uint8_t jf,
596 uint32_t k)
597 {
598 bpf_assert_max();
599 out[curr_instr].code = code;
600 out[curr_instr].jt = jt;
601 out[curr_instr].jf = jf;
602 out[curr_instr].k = k;
603 curr_instr++;
604 }
605
606 static void bpf_set_curr_label(char *label)
607 {
608 bpf_assert_max();
609 labels[curr_instr] = label;
610 }
611
612 static void bpf_set_jmp_label(char *label, enum jmp_type type)
613 {
614 bpf_assert_max();
615 switch (type) {
616 case JTL:
617 labels_jt[curr_instr] = label;
618 break;
619 case JFL:
620 labels_jf[curr_instr] = label;
621 break;
622 case JKL:
623 labels_k[curr_instr] = label;
624 break;
625 }
626 }
627
628 static int bpf_find_insns_offset(const char *label)
629 {
630 int i, max = curr_instr, ret = -ENOENT;
631
632 for (i = 0; i < max; i++) {
633 if (labels[i] && !strcmp(label, labels[i])) {
634 ret = i;
635 break;
636 }
637 }
638
639 if (ret == -ENOENT) {
640 fprintf(stderr, "no such label \'%s\'!\n", label);
641 exit(0);
642 }
643
644 return ret;
645 }
646
647 static void bpf_stage_1_insert_insns(void)
648 {
649 yyparse();
650 }
651
652 static void bpf_reduce_k_jumps(void)
653 {
654 int i;
655
656 for (i = 0; i < curr_instr; i++) {
657 if (labels_k[i]) {
658 int off = bpf_find_insns_offset(labels_k[i]);
659 out[i].k = (uint32_t) (off - i - 1);
660 }
661 }
662 }
663
664 static void bpf_reduce_jt_jumps(void)
665 {
666 int i;
667
668 for (i = 0; i < curr_instr; i++) {
669 if (labels_jt[i]) {
670 int off = bpf_find_insns_offset(labels_jt[i]);
671 out[i].jt = (uint8_t) (off - i -1);
672 }
673 }
674 }
675
676 static void bpf_reduce_jf_jumps(void)
677 {
678 int i;
679
680 for (i = 0; i < curr_instr; i++) {
681 if (labels_jf[i]) {
682 int off = bpf_find_insns_offset(labels_jf[i]);
683 out[i].jf = (uint8_t) (off - i - 1);
684 }
685 }
686 }
687
688 static void bpf_stage_2_reduce_labels(void)
689 {
690 bpf_reduce_k_jumps();
691 bpf_reduce_jt_jumps();
692 bpf_reduce_jf_jumps();
693 }
694
695 static void bpf_pretty_print_c(void)
696 {
697 int i;
698
699 for (i = 0; i < curr_instr; i++)
700 printf("{ %#04x, %2u, %2u, %#010x },\n", out[i].code,
701 out[i].jt, out[i].jf, out[i].k);
702 }
703
704 static void bpf_pretty_print(void)
705 {
706 int i;
707
708 printf("%u,", curr_instr);
709 for (i = 0; i < curr_instr; i++)
710 printf("%u %u %u %u,", out[i].code,
711 out[i].jt, out[i].jf, out[i].k);
712 printf("\n");
713 }
714
715 static void bpf_init(void)
716 {
717 memset(out, 0, sizeof(out));
718
719 labels = calloc(BPF_MAXINSNS, sizeof(*labels));
720 assert(labels);
721 labels_jt = calloc(BPF_MAXINSNS, sizeof(*labels_jt));
722 assert(labels_jt);
723 labels_jf = calloc(BPF_MAXINSNS, sizeof(*labels_jf));
724 assert(labels_jf);
725 labels_k = calloc(BPF_MAXINSNS, sizeof(*labels_k));
726 assert(labels_k);
727 }
728
729 static void bpf_destroy_labels(void)
730 {
731 int i;
732
733 for (i = 0; i < curr_instr; i++) {
734 free(labels_jf[i]);
735 free(labels_jt[i]);
736 free(labels_k[i]);
737 free(labels[i]);
738 }
739 }
740
741 static void bpf_destroy(void)
742 {
743 bpf_destroy_labels();
744 free(labels_jt);
745 free(labels_jf);
746 free(labels_k);
747 free(labels);
748 }
749
750 void bpf_asm_compile(FILE *fp, bool cstyle)
751 {
752 yyin = fp;
753
754 bpf_init();
755 bpf_stage_1_insert_insns();
756 bpf_stage_2_reduce_labels();
757 bpf_destroy();
758
759 if (cstyle)
760 bpf_pretty_print_c();
761 else
762 bpf_pretty_print();
763
764 if (fp != stdin)
765 fclose(yyin);
766 }
767
768 void yyerror(const char *str)
769 {
770 exit(1);
771 }
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