1 // SPDX-License-Identifier: GPL-2.0
2
3 #include <limits.h>
4 #include <stdio.h>
5 #include <string.h>
6 #include <ctype.h>
7 #include <regex.h>
8 #include <test_progs.h>
9
10 #include "bpf/btf.h"
11 #include "bpf_util.h"
12 #include "linux/filter.h"
13 #include "disasm.h"
14
15 #define MAX_PROG_TEXT_SZ (32 * 1024)
16
17 /* The code in this file serves the sole purpose of executing test cases
18 * specified in the test_cases array. Each test case specifies a program
19 * type, context field offset, and disassembly patterns that correspond
20 * to read and write instructions generated by
21 * verifier.c:convert_ctx_access() for accessing that field.
22 *
23 * For each test case, up to three programs are created:
24 * - One that uses BPF_LDX_MEM to read the context field.
25 * - One that uses BPF_STX_MEM to write to the context field.
26 * - One that uses BPF_ST_MEM to write to the context field.
27 *
28 * The disassembly of each program is then compared with the pattern
29 * specified in the test case.
30 */
31 struct test_case {
32 char *name;
33 enum bpf_prog_type prog_type;
34 enum bpf_attach_type expected_attach_type;
35 int field_offset;
36 int field_sz;
37 /* Program generated for BPF_ST_MEM uses value 42 by default,
38 * this field allows to specify custom value.
39 */
40 struct {
41 bool use;
42 int value;
43 } st_value;
44 /* Pattern for BPF_LDX_MEM(field_sz, dst, ctx, field_offset) */
45 char *read;
46 /* Pattern for BPF_STX_MEM(field_sz, ctx, src, field_offset) and
47 * BPF_ST_MEM (field_sz, ctx, src, field_offset)
48 */
49 char *write;
50 /* Pattern for BPF_ST_MEM(field_sz, ctx, src, field_offset),
51 * takes priority over `write`.
52 */
53 char *write_st;
54 /* Pattern for BPF_STX_MEM (field_sz, ctx, src, field_offset),
55 * takes priority over `write`.
56 */
57 char *write_stx;
58 };
59
60 #define N(_prog_type, type, field, name_extra...) \
61 .name = #_prog_type "." #field name_extra, \
62 .prog_type = BPF_PROG_TYPE_##_prog_type, \
63 .field_offset = offsetof(type, field), \
64 .field_sz = sizeof(typeof(((type *)NULL)->field))
65
66 static struct test_case test_cases[] = {
67 /* Sign extension on s390 changes the pattern */
68 #if defined(__x86_64__) || defined(__aarch64__)
69 {
70 N(SCHED_CLS, struct __sk_buff, tstamp),
71 .read = "r11 = *(u8 *)($ctx + sk_buff::__mono_tc_offset);"
72 "w11 &= 3;"
73 "if w11 != 0x3 goto pc+2;"
74 "$dst = 0;"
75 "goto pc+1;"
76 "$dst = *(u64 *)($ctx + sk_buff::tstamp);",
77 .write = "r11 = *(u8 *)($ctx + sk_buff::__mono_tc_offset);"
78 "if w11 & 0x2 goto pc+1;"
79 "goto pc+2;"
80 "w11 &= -2;"
81 "*(u8 *)($ctx + sk_buff::__mono_tc_offset) = r11;"
82 "*(u64 *)($ctx + sk_buff::tstamp) = $src;",
83 },
84 #endif
85 {
86 N(SCHED_CLS, struct __sk_buff, priority),
87 .read = "$dst = *(u32 *)($ctx + sk_buff::priority);",
88 .write = "*(u32 *)($ctx + sk_buff::priority) = $src;",
89 },
90 {
91 N(SCHED_CLS, struct __sk_buff, mark),
92 .read = "$dst = *(u32 *)($ctx + sk_buff::mark);",
93 .write = "*(u32 *)($ctx + sk_buff::mark) = $src;",
94 },
95 {
96 N(SCHED_CLS, struct __sk_buff, cb[0]),
97 .read = "$dst = *(u32 *)($ctx + $(sk_buff::cb + qdisc_skb_cb::data));",
98 .write = "*(u32 *)($ctx + $(sk_buff::cb + qdisc_skb_cb::data)) = $src;",
99 },
100 {
101 N(SCHED_CLS, struct __sk_buff, tc_classid),
102 .read = "$dst = *(u16 *)($ctx + $(sk_buff::cb + qdisc_skb_cb::tc_classid));",
103 .write = "*(u16 *)($ctx + $(sk_buff::cb + qdisc_skb_cb::tc_classid)) = $src;",
104 },
105 {
106 N(SCHED_CLS, struct __sk_buff, tc_index),
107 .read = "$dst = *(u16 *)($ctx + sk_buff::tc_index);",
108 .write = "*(u16 *)($ctx + sk_buff::tc_index) = $src;",
109 },
110 {
111 N(SCHED_CLS, struct __sk_buff, queue_mapping),
112 .read = "$dst = *(u16 *)($ctx + sk_buff::queue_mapping);",
113 .write_stx = "if $src >= 0xffff goto pc+1;"
114 "*(u16 *)($ctx + sk_buff::queue_mapping) = $src;",
115 .write_st = "*(u16 *)($ctx + sk_buff::queue_mapping) = $src;",
116 },
117 {
118 /* This is a corner case in filter.c:bpf_convert_ctx_access() */
119 N(SCHED_CLS, struct __sk_buff, queue_mapping, ".ushrt_max"),
120 .st_value = { true, USHRT_MAX },
121 .write_st = "goto pc+0;",
122 },
123 {
124 N(CGROUP_SOCK, struct bpf_sock, bound_dev_if),
125 .read = "$dst = *(u32 *)($ctx + sock_common::skc_bound_dev_if);",
126 .write = "*(u32 *)($ctx + sock_common::skc_bound_dev_if) = $src;",
127 },
128 {
129 N(CGROUP_SOCK, struct bpf_sock, mark),
130 .read = "$dst = *(u32 *)($ctx + sock::sk_mark);",
131 .write = "*(u32 *)($ctx + sock::sk_mark) = $src;",
132 },
133 {
134 N(CGROUP_SOCK, struct bpf_sock, priority),
135 .read = "$dst = *(u32 *)($ctx + sock::sk_priority);",
136 .write = "*(u32 *)($ctx + sock::sk_priority) = $src;",
137 },
138 {
139 N(SOCK_OPS, struct bpf_sock_ops, replylong[0]),
140 .read = "$dst = *(u32 *)($ctx + bpf_sock_ops_kern::replylong);",
141 .write = "*(u32 *)($ctx + bpf_sock_ops_kern::replylong) = $src;",
142 },
143 {
144 N(CGROUP_SYSCTL, struct bpf_sysctl, file_pos),
145 #if __BYTE_ORDER == __LITTLE_ENDIAN
146 .read = "$dst = *(u64 *)($ctx + bpf_sysctl_kern::ppos);"
147 "$dst = *(u32 *)($dst +0);",
148 .write = "*(u64 *)($ctx + bpf_sysctl_kern::tmp_reg) = r9;"
149 "r9 = *(u64 *)($ctx + bpf_sysctl_kern::ppos);"
150 "*(u32 *)(r9 +0) = $src;"
151 "r9 = *(u64 *)($ctx + bpf_sysctl_kern::tmp_reg);",
152 #else
153 .read = "$dst = *(u64 *)($ctx + bpf_sysctl_kern::ppos);"
154 "$dst = *(u32 *)($dst +4);",
155 .write = "*(u64 *)($ctx + bpf_sysctl_kern::tmp_reg) = r9;"
156 "r9 = *(u64 *)($ctx + bpf_sysctl_kern::ppos);"
157 "*(u32 *)(r9 +4) = $src;"
158 "r9 = *(u64 *)($ctx + bpf_sysctl_kern::tmp_reg);",
159 #endif
160 },
161 {
162 N(CGROUP_SOCKOPT, struct bpf_sockopt, sk),
163 .read = "$dst = *(u64 *)($ctx + bpf_sockopt_kern::sk);",
164 .expected_attach_type = BPF_CGROUP_GETSOCKOPT,
165 },
166 {
167 N(CGROUP_SOCKOPT, struct bpf_sockopt, level),
168 .read = "$dst = *(u32 *)($ctx + bpf_sockopt_kern::level);",
169 .write = "*(u32 *)($ctx + bpf_sockopt_kern::level) = $src;",
170 .expected_attach_type = BPF_CGROUP_SETSOCKOPT,
171 },
172 {
173 N(CGROUP_SOCKOPT, struct bpf_sockopt, optname),
174 .read = "$dst = *(u32 *)($ctx + bpf_sockopt_kern::optname);",
175 .write = "*(u32 *)($ctx + bpf_sockopt_kern::optname) = $src;",
176 .expected_attach_type = BPF_CGROUP_SETSOCKOPT,
177 },
178 {
179 N(CGROUP_SOCKOPT, struct bpf_sockopt, optlen),
180 .read = "$dst = *(u32 *)($ctx + bpf_sockopt_kern::optlen);",
181 .write = "*(u32 *)($ctx + bpf_sockopt_kern::optlen) = $src;",
182 .expected_attach_type = BPF_CGROUP_SETSOCKOPT,
183 },
184 {
185 N(CGROUP_SOCKOPT, struct bpf_sockopt, retval),
186 .read = "$dst = *(u64 *)($ctx + bpf_sockopt_kern::current_task);"
187 "$dst = *(u64 *)($dst + task_struct::bpf_ctx);"
188 "$dst = *(u32 *)($dst + bpf_cg_run_ctx::retval);",
189 .write = "*(u64 *)($ctx + bpf_sockopt_kern::tmp_reg) = r9;"
190 "r9 = *(u64 *)($ctx + bpf_sockopt_kern::current_task);"
191 "r9 = *(u64 *)(r9 + task_struct::bpf_ctx);"
192 "*(u32 *)(r9 + bpf_cg_run_ctx::retval) = $src;"
193 "r9 = *(u64 *)($ctx + bpf_sockopt_kern::tmp_reg);",
194 .expected_attach_type = BPF_CGROUP_GETSOCKOPT,
195 },
196 {
197 N(CGROUP_SOCKOPT, struct bpf_sockopt, optval),
198 .read = "$dst = *(u64 *)($ctx + bpf_sockopt_kern::optval);",
199 .expected_attach_type = BPF_CGROUP_GETSOCKOPT,
200 },
201 {
202 N(CGROUP_SOCKOPT, struct bpf_sockopt, optval_end),
203 .read = "$dst = *(u64 *)($ctx + bpf_sockopt_kern::optval_end);",
204 .expected_attach_type = BPF_CGROUP_GETSOCKOPT,
205 },
206 };
207
208 #undef N
209
210 static regex_t *ident_regex;
211 static regex_t *field_regex;
212
skip_space(char * str)213 static char *skip_space(char *str)
214 {
215 while (*str && isspace(*str))
216 ++str;
217 return str;
218 }
219
skip_space_and_semi(char * str)220 static char *skip_space_and_semi(char *str)
221 {
222 while (*str && (isspace(*str) || *str == ';'))
223 ++str;
224 return str;
225 }
226
match_str(char * str,char * prefix)227 static char *match_str(char *str, char *prefix)
228 {
229 while (*str && *prefix && *str == *prefix) {
230 ++str;
231 ++prefix;
232 }
233 if (*prefix)
234 return NULL;
235 return str;
236 }
237
match_number(char * str,int num)238 static char *match_number(char *str, int num)
239 {
240 char *next;
241 int snum = strtol(str, &next, 10);
242
243 if (next - str == 0 || num != snum)
244 return NULL;
245
246 return next;
247 }
248
find_field_offset_aux(struct btf * btf,int btf_id,char * field_name,int off)249 static int find_field_offset_aux(struct btf *btf, int btf_id, char *field_name, int off)
250 {
251 const struct btf_type *type = btf__type_by_id(btf, btf_id);
252 const struct btf_member *m;
253 __u16 mnum;
254 int i;
255
256 if (!type) {
257 PRINT_FAIL("Can't find btf_type for id %d\n", btf_id);
258 return -1;
259 }
260
261 if (!btf_is_struct(type) && !btf_is_union(type)) {
262 PRINT_FAIL("BTF id %d is not struct or union\n", btf_id);
263 return -1;
264 }
265
266 m = btf_members(type);
267 mnum = btf_vlen(type);
268
269 for (i = 0; i < mnum; ++i, ++m) {
270 const char *mname = btf__name_by_offset(btf, m->name_off);
271
272 if (strcmp(mname, "") == 0) {
273 int msize = find_field_offset_aux(btf, m->type, field_name,
274 off + m->offset);
275 if (msize >= 0)
276 return msize;
277 }
278
279 if (strcmp(mname, field_name))
280 continue;
281
282 return (off + m->offset) / 8;
283 }
284
285 return -1;
286 }
287
find_field_offset(struct btf * btf,char * pattern,regmatch_t * matches)288 static int find_field_offset(struct btf *btf, char *pattern, regmatch_t *matches)
289 {
290 int type_sz = matches[1].rm_eo - matches[1].rm_so;
291 int field_sz = matches[2].rm_eo - matches[2].rm_so;
292 char *type = pattern + matches[1].rm_so;
293 char *field = pattern + matches[2].rm_so;
294 char field_str[128] = {};
295 char type_str[128] = {};
296 int btf_id, field_offset;
297
298 if (type_sz >= sizeof(type_str)) {
299 PRINT_FAIL("Malformed pattern: type ident is too long: %d\n", type_sz);
300 return -1;
301 }
302
303 if (field_sz >= sizeof(field_str)) {
304 PRINT_FAIL("Malformed pattern: field ident is too long: %d\n", field_sz);
305 return -1;
306 }
307
308 strncpy(type_str, type, type_sz);
309 strncpy(field_str, field, field_sz);
310 btf_id = btf__find_by_name(btf, type_str);
311 if (btf_id < 0) {
312 PRINT_FAIL("No BTF info for type %s\n", type_str);
313 return -1;
314 }
315
316 field_offset = find_field_offset_aux(btf, btf_id, field_str, 0);
317 if (field_offset < 0) {
318 PRINT_FAIL("No BTF info for field %s::%s\n", type_str, field_str);
319 return -1;
320 }
321
322 return field_offset;
323 }
324
compile_regex(char * pat)325 static regex_t *compile_regex(char *pat)
326 {
327 regex_t *re;
328 int err;
329
330 re = malloc(sizeof(regex_t));
331 if (!re) {
332 PRINT_FAIL("Can't alloc regex\n");
333 return NULL;
334 }
335
336 err = regcomp(re, pat, REG_EXTENDED);
337 if (err) {
338 char errbuf[512];
339
340 regerror(err, re, errbuf, sizeof(errbuf));
341 PRINT_FAIL("Can't compile regex: %s\n", errbuf);
342 free(re);
343 return NULL;
344 }
345
346 return re;
347 }
348
free_regex(regex_t * re)349 static void free_regex(regex_t *re)
350 {
351 if (!re)
352 return;
353
354 regfree(re);
355 free(re);
356 }
357
max_line_len(char * str)358 static u32 max_line_len(char *str)
359 {
360 u32 max_line = 0;
361 char *next = str;
362
363 while (next) {
364 next = strchr(str, '\n');
365 if (next) {
366 max_line = max_t(u32, max_line, (next - str));
367 str = next + 1;
368 } else {
369 max_line = max_t(u32, max_line, strlen(str));
370 }
371 }
372
373 return min(max_line, 60u);
374 }
375
376 /* Print strings `pattern_origin` and `text_origin` side by side,
377 * assume `pattern_pos` and `text_pos` designate location within
378 * corresponding origin string where match diverges.
379 * The output should look like:
380 *
381 * Can't match disassembly(left) with pattern(right):
382 * r2 = *(u64 *)(r1 +0) ; $dst = *(u64 *)($ctx + bpf_sockopt_kern::sk1)
383 * ^ ^
384 * r0 = 0 ;
385 * exit ;
386 */
print_match_error(FILE * out,char * pattern_origin,char * text_origin,char * pattern_pos,char * text_pos)387 static void print_match_error(FILE *out,
388 char *pattern_origin, char *text_origin,
389 char *pattern_pos, char *text_pos)
390 {
391 char *pattern = pattern_origin;
392 char *text = text_origin;
393 int middle = max_line_len(text) + 2;
394
395 fprintf(out, "Can't match disassembly(left) with pattern(right):\n");
396 while (*pattern || *text) {
397 int column = 0;
398 int mark1 = -1;
399 int mark2 = -1;
400
401 /* Print one line from text */
402 while (*text && *text != '\n') {
403 if (text == text_pos)
404 mark1 = column;
405 fputc(*text, out);
406 ++text;
407 ++column;
408 }
409 if (text == text_pos)
410 mark1 = column;
411
412 /* Pad to the middle */
413 while (column < middle) {
414 fputc(' ', out);
415 ++column;
416 }
417 fputs("; ", out);
418 column += 3;
419
420 /* Print one line from pattern, pattern lines are terminated by ';' */
421 while (*pattern && *pattern != ';') {
422 if (pattern == pattern_pos)
423 mark2 = column;
424 fputc(*pattern, out);
425 ++pattern;
426 ++column;
427 }
428 if (pattern == pattern_pos)
429 mark2 = column;
430
431 fputc('\n', out);
432 if (*pattern)
433 ++pattern;
434 if (*text)
435 ++text;
436
437 /* If pattern and text diverge at this line, print an
438 * additional line with '^' marks, highlighting
439 * positions where match fails.
440 */
441 if (mark1 > 0 || mark2 > 0) {
442 for (column = 0; column <= max(mark1, mark2); ++column) {
443 if (column == mark1 || column == mark2)
444 fputc('^', out);
445 else
446 fputc(' ', out);
447 }
448 fputc('\n', out);
449 }
450 }
451 }
452
453 /* Test if `text` matches `pattern`. Pattern consists of the following elements:
454 *
455 * - Field offset references:
456 *
457 * <type>::<field>
458 *
459 * When such reference is encountered BTF is used to compute numerical
460 * value for the offset of <field> in <type>. The `text` is expected to
461 * contain matching numerical value.
462 *
463 * - Field groups:
464 *
465 * $(<type>::<field> [+ <type>::<field>]*)
466 *
467 * Allows to specify an offset that is a sum of multiple field offsets.
468 * The `text` is expected to contain matching numerical value.
469 *
470 * - Variable references, e.g. `$src`, `$dst`, `$ctx`.
471 * These are substitutions specified in `reg_map` array.
472 * If a substring of pattern is equal to `reg_map[i][0]` the `text` is
473 * expected to contain `reg_map[i][1]` in the matching position.
474 *
475 * - Whitespace is ignored, ';' counts as whitespace for `pattern`.
476 *
477 * - Any other characters, `pattern` and `text` should match one-to-one.
478 *
479 * Example of a pattern:
480 *
481 * __________ fields group ________________
482 * ' '
483 * *(u16 *)($ctx + $(sk_buff::cb + qdisc_skb_cb::tc_classid)) = $src;
484 * ^^^^ '______________________'
485 * variable reference field offset reference
486 */
match_pattern(struct btf * btf,char * pattern,char * text,char * reg_map[][2])487 static bool match_pattern(struct btf *btf, char *pattern, char *text, char *reg_map[][2])
488 {
489 char *pattern_origin = pattern;
490 char *text_origin = text;
491 regmatch_t matches[3];
492
493 _continue:
494 while (*pattern) {
495 if (!*text)
496 goto err;
497
498 /* Skip whitespace */
499 if (isspace(*pattern) || *pattern == ';') {
500 if (!isspace(*text) && text != text_origin && isalnum(text[-1]))
501 goto err;
502 pattern = skip_space_and_semi(pattern);
503 text = skip_space(text);
504 continue;
505 }
506
507 /* Check for variable references */
508 for (int i = 0; reg_map[i][0]; ++i) {
509 char *pattern_next, *text_next;
510
511 pattern_next = match_str(pattern, reg_map[i][0]);
512 if (!pattern_next)
513 continue;
514
515 text_next = match_str(text, reg_map[i][1]);
516 if (!text_next)
517 goto err;
518
519 pattern = pattern_next;
520 text = text_next;
521 goto _continue;
522 }
523
524 /* Match field group:
525 * $(sk_buff::cb + qdisc_skb_cb::tc_classid)
526 */
527 if (strncmp(pattern, "$(", 2) == 0) {
528 char *group_start = pattern, *text_next;
529 int acc_offset = 0;
530
531 pattern += 2;
532
533 for (;;) {
534 int field_offset;
535
536 pattern = skip_space(pattern);
537 if (!*pattern) {
538 PRINT_FAIL("Unexpected end of pattern\n");
539 goto err;
540 }
541
542 if (*pattern == ')') {
543 ++pattern;
544 break;
545 }
546
547 if (*pattern == '+') {
548 ++pattern;
549 continue;
550 }
551
552 printf("pattern: %s\n", pattern);
553 if (regexec(field_regex, pattern, 3, matches, 0) != 0) {
554 PRINT_FAIL("Field reference expected\n");
555 goto err;
556 }
557
558 field_offset = find_field_offset(btf, pattern, matches);
559 if (field_offset < 0)
560 goto err;
561
562 pattern += matches[0].rm_eo;
563 acc_offset += field_offset;
564 }
565
566 text_next = match_number(text, acc_offset);
567 if (!text_next) {
568 PRINT_FAIL("No match for group offset %.*s (%d)\n",
569 (int)(pattern - group_start),
570 group_start,
571 acc_offset);
572 goto err;
573 }
574 text = text_next;
575 }
576
577 /* Match field reference:
578 * sk_buff::cb
579 */
580 if (regexec(field_regex, pattern, 3, matches, 0) == 0) {
581 int field_offset;
582 char *text_next;
583
584 field_offset = find_field_offset(btf, pattern, matches);
585 if (field_offset < 0)
586 goto err;
587
588 text_next = match_number(text, field_offset);
589 if (!text_next) {
590 PRINT_FAIL("No match for field offset %.*s (%d)\n",
591 (int)matches[0].rm_eo, pattern, field_offset);
592 goto err;
593 }
594
595 pattern += matches[0].rm_eo;
596 text = text_next;
597 continue;
598 }
599
600 /* If pattern points to identifier not followed by '::'
601 * skip the identifier to avoid n^2 application of the
602 * field reference rule.
603 */
604 if (regexec(ident_regex, pattern, 1, matches, 0) == 0) {
605 if (strncmp(pattern, text, matches[0].rm_eo) != 0)
606 goto err;
607
608 pattern += matches[0].rm_eo;
609 text += matches[0].rm_eo;
610 continue;
611 }
612
613 /* Match literally */
614 if (*pattern != *text)
615 goto err;
616
617 ++pattern;
618 ++text;
619 }
620
621 return true;
622
623 err:
624 test__fail();
625 print_match_error(stdout, pattern_origin, text_origin, pattern, text);
626 return false;
627 }
628
629 /* Request BPF program instructions after all rewrites are applied,
630 * e.g. verifier.c:convert_ctx_access() is done.
631 */
get_xlated_program(int fd_prog,struct bpf_insn ** buf,__u32 * cnt)632 static int get_xlated_program(int fd_prog, struct bpf_insn **buf, __u32 *cnt)
633 {
634 struct bpf_prog_info info = {};
635 __u32 info_len = sizeof(info);
636 __u32 xlated_prog_len;
637 __u32 buf_element_size = sizeof(struct bpf_insn);
638
639 if (bpf_prog_get_info_by_fd(fd_prog, &info, &info_len)) {
640 perror("bpf_prog_get_info_by_fd failed");
641 return -1;
642 }
643
644 xlated_prog_len = info.xlated_prog_len;
645 if (xlated_prog_len % buf_element_size) {
646 printf("Program length %d is not multiple of %d\n",
647 xlated_prog_len, buf_element_size);
648 return -1;
649 }
650
651 *cnt = xlated_prog_len / buf_element_size;
652 *buf = calloc(*cnt, buf_element_size);
653 if (!buf) {
654 perror("can't allocate xlated program buffer");
655 return -ENOMEM;
656 }
657
658 bzero(&info, sizeof(info));
659 info.xlated_prog_len = xlated_prog_len;
660 info.xlated_prog_insns = (__u64)(unsigned long)*buf;
661 if (bpf_prog_get_info_by_fd(fd_prog, &info, &info_len)) {
662 perror("second bpf_prog_get_info_by_fd failed");
663 goto out_free_buf;
664 }
665
666 return 0;
667
668 out_free_buf:
669 free(*buf);
670 return -1;
671 }
672
print_insn(void * private_data,const char * fmt,...)673 static void print_insn(void *private_data, const char *fmt, ...)
674 {
675 va_list args;
676
677 va_start(args, fmt);
678 vfprintf((FILE *)private_data, fmt, args);
679 va_end(args);
680 }
681
682 /* Disassemble instructions to a stream */
print_xlated(FILE * out,struct bpf_insn * insn,__u32 len)683 static void print_xlated(FILE *out, struct bpf_insn *insn, __u32 len)
684 {
685 const struct bpf_insn_cbs cbs = {
686 .cb_print = print_insn,
687 .cb_call = NULL,
688 .cb_imm = NULL,
689 .private_data = out,
690 };
691 bool double_insn = false;
692 int i;
693
694 for (i = 0; i < len; i++) {
695 if (double_insn) {
696 double_insn = false;
697 continue;
698 }
699
700 double_insn = insn[i].code == (BPF_LD | BPF_IMM | BPF_DW);
701 print_bpf_insn(&cbs, insn + i, true);
702 }
703 }
704
705 /* We share code with kernel BPF disassembler, it adds '(FF) ' prefix
706 * for each instruction (FF stands for instruction `code` byte).
707 * This function removes the prefix inplace for each line in `str`.
708 */
remove_insn_prefix(char * str,int size)709 static void remove_insn_prefix(char *str, int size)
710 {
711 const int prefix_size = 5;
712
713 int write_pos = 0, read_pos = prefix_size;
714 int len = strlen(str);
715 char c;
716
717 size = min(size, len);
718
719 while (read_pos < size) {
720 c = str[read_pos++];
721 if (c == 0)
722 break;
723 str[write_pos++] = c;
724 if (c == '\n')
725 read_pos += prefix_size;
726 }
727 str[write_pos] = 0;
728 }
729
730 struct prog_info {
731 char *prog_kind;
732 enum bpf_prog_type prog_type;
733 enum bpf_attach_type expected_attach_type;
734 struct bpf_insn *prog;
735 u32 prog_len;
736 };
737
match_program(struct btf * btf,struct prog_info * pinfo,char * pattern,char * reg_map[][2],bool skip_first_insn)738 static void match_program(struct btf *btf,
739 struct prog_info *pinfo,
740 char *pattern,
741 char *reg_map[][2],
742 bool skip_first_insn)
743 {
744 struct bpf_insn *buf = NULL;
745 int err = 0, prog_fd = 0;
746 FILE *prog_out = NULL;
747 char *text = NULL;
748 __u32 cnt = 0;
749
750 text = calloc(MAX_PROG_TEXT_SZ, 1);
751 if (!text) {
752 PRINT_FAIL("Can't allocate %d bytes\n", MAX_PROG_TEXT_SZ);
753 goto out;
754 }
755
756 // TODO: log level
757 LIBBPF_OPTS(bpf_prog_load_opts, opts);
758 opts.log_buf = text;
759 opts.log_size = MAX_PROG_TEXT_SZ;
760 opts.log_level = 1 | 2 | 4;
761 opts.expected_attach_type = pinfo->expected_attach_type;
762
763 prog_fd = bpf_prog_load(pinfo->prog_type, NULL, "GPL",
764 pinfo->prog, pinfo->prog_len, &opts);
765 if (prog_fd < 0) {
766 PRINT_FAIL("Can't load program, errno %d (%s), verifier log:\n%s\n",
767 errno, strerror(errno), text);
768 goto out;
769 }
770
771 memset(text, 0, MAX_PROG_TEXT_SZ);
772
773 err = get_xlated_program(prog_fd, &buf, &cnt);
774 if (err) {
775 PRINT_FAIL("Can't load back BPF program\n");
776 goto out;
777 }
778
779 prog_out = fmemopen(text, MAX_PROG_TEXT_SZ - 1, "w");
780 if (!prog_out) {
781 PRINT_FAIL("Can't open memory stream\n");
782 goto out;
783 }
784 if (skip_first_insn)
785 print_xlated(prog_out, buf + 1, cnt - 1);
786 else
787 print_xlated(prog_out, buf, cnt);
788 fclose(prog_out);
789 remove_insn_prefix(text, MAX_PROG_TEXT_SZ);
790
791 ASSERT_TRUE(match_pattern(btf, pattern, text, reg_map),
792 pinfo->prog_kind);
793
794 out:
795 if (prog_fd)
796 close(prog_fd);
797 free(buf);
798 free(text);
799 }
800
run_one_testcase(struct btf * btf,struct test_case * test)801 static void run_one_testcase(struct btf *btf, struct test_case *test)
802 {
803 struct prog_info pinfo = {};
804 int bpf_sz;
805
806 if (!test__start_subtest(test->name))
807 return;
808
809 switch (test->field_sz) {
810 case 8:
811 bpf_sz = BPF_DW;
812 break;
813 case 4:
814 bpf_sz = BPF_W;
815 break;
816 case 2:
817 bpf_sz = BPF_H;
818 break;
819 case 1:
820 bpf_sz = BPF_B;
821 break;
822 default:
823 PRINT_FAIL("Unexpected field size: %d, want 8,4,2 or 1\n", test->field_sz);
824 return;
825 }
826
827 pinfo.prog_type = test->prog_type;
828 pinfo.expected_attach_type = test->expected_attach_type;
829
830 if (test->read) {
831 struct bpf_insn ldx_prog[] = {
832 BPF_LDX_MEM(bpf_sz, BPF_REG_2, BPF_REG_1, test->field_offset),
833 BPF_MOV64_IMM(BPF_REG_0, 0),
834 BPF_EXIT_INSN(),
835 };
836 char *reg_map[][2] = {
837 { "$ctx", "r1" },
838 { "$dst", "r2" },
839 {}
840 };
841
842 pinfo.prog_kind = "LDX";
843 pinfo.prog = ldx_prog;
844 pinfo.prog_len = ARRAY_SIZE(ldx_prog);
845 match_program(btf, &pinfo, test->read, reg_map, false);
846 }
847
848 if (test->write || test->write_st || test->write_stx) {
849 struct bpf_insn stx_prog[] = {
850 BPF_MOV64_IMM(BPF_REG_2, 0),
851 BPF_STX_MEM(bpf_sz, BPF_REG_1, BPF_REG_2, test->field_offset),
852 BPF_MOV64_IMM(BPF_REG_0, 0),
853 BPF_EXIT_INSN(),
854 };
855 char *stx_reg_map[][2] = {
856 { "$ctx", "r1" },
857 { "$src", "r2" },
858 {}
859 };
860 struct bpf_insn st_prog[] = {
861 BPF_ST_MEM(bpf_sz, BPF_REG_1, test->field_offset,
862 test->st_value.use ? test->st_value.value : 42),
863 BPF_MOV64_IMM(BPF_REG_0, 0),
864 BPF_EXIT_INSN(),
865 };
866 char *st_reg_map[][2] = {
867 { "$ctx", "r1" },
868 { "$src", "42" },
869 {}
870 };
871
872 if (test->write || test->write_stx) {
873 char *pattern = test->write_stx ? test->write_stx : test->write;
874
875 pinfo.prog_kind = "STX";
876 pinfo.prog = stx_prog;
877 pinfo.prog_len = ARRAY_SIZE(stx_prog);
878 match_program(btf, &pinfo, pattern, stx_reg_map, true);
879 }
880
881 if (test->write || test->write_st) {
882 char *pattern = test->write_st ? test->write_st : test->write;
883
884 pinfo.prog_kind = "ST";
885 pinfo.prog = st_prog;
886 pinfo.prog_len = ARRAY_SIZE(st_prog);
887 match_program(btf, &pinfo, pattern, st_reg_map, false);
888 }
889 }
890
891 test__end_subtest();
892 }
893
test_ctx_rewrite(void)894 void test_ctx_rewrite(void)
895 {
896 struct btf *btf;
897 int i;
898
899 field_regex = compile_regex("^([[:alpha:]_][[:alnum:]_]+)::([[:alpha:]_][[:alnum:]_]+)");
900 ident_regex = compile_regex("^[[:alpha:]_][[:alnum:]_]+");
901 if (!field_regex || !ident_regex)
902 return;
903
904 btf = btf__load_vmlinux_btf();
905 if (!btf) {
906 PRINT_FAIL("Can't load vmlinux BTF, errno %d (%s)\n", errno, strerror(errno));
907 goto out;
908 }
909
910 for (i = 0; i < ARRAY_SIZE(test_cases); ++i)
911 run_one_testcase(btf, &test_cases[i]);
912
913 out:
914 btf__free(btf);
915 free_regex(field_regex);
916 free_regex(ident_regex);
917 }
918
