1 // SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
2 /* Copyright (c) 2019 Netronome Systems, Inc. */
3
4 #include <ctype.h>
5 #include <errno.h>
6 #include <fcntl.h>
7 #include <string.h>
8 #include <unistd.h>
9 #include <net/if.h>
10 #ifdef USE_LIBCAP
11 #include <sys/capability.h>
12 #endif
13 #include <sys/utsname.h>
14 #include <sys/vfs.h>
15
16 #include <linux/filter.h>
17 #include <linux/limits.h>
18
19 #include <bpf/bpf.h>
20 #include <bpf/libbpf.h>
21 #include <zlib.h>
22
23 #include "main.h"
24
25 #ifndef PROC_SUPER_MAGIC
26 # define PROC_SUPER_MAGIC 0x9fa0
27 #endif
28
29 enum probe_component {
30 COMPONENT_UNSPEC,
31 COMPONENT_KERNEL,
32 COMPONENT_DEVICE,
33 };
34
35 #define BPF_HELPER_MAKE_ENTRY(name) [BPF_FUNC_ ## name] = "bpf_" # name
36 static const char * const helper_name[] = {
37 __BPF_FUNC_MAPPER(BPF_HELPER_MAKE_ENTRY)
38 };
39
40 #undef BPF_HELPER_MAKE_ENTRY
41
42 static bool full_mode;
43 #ifdef USE_LIBCAP
44 static bool run_as_unprivileged;
45 #endif
46
47 /* Miscellaneous utility functions */
48
grep(const char * buffer,const char * pattern)49 static bool grep(const char *buffer, const char *pattern)
50 {
51 return !!strstr(buffer, pattern);
52 }
53
check_procfs(void)54 static bool check_procfs(void)
55 {
56 struct statfs st_fs;
57
58 if (statfs("/proc", &st_fs) < 0)
59 return false;
60 if ((unsigned long)st_fs.f_type != PROC_SUPER_MAGIC)
61 return false;
62
63 return true;
64 }
65
uppercase(char * str,size_t len)66 static void uppercase(char *str, size_t len)
67 {
68 size_t i;
69
70 for (i = 0; i < len && str[i] != '\0'; i++)
71 str[i] = toupper(str[i]);
72 }
73
74 /* Printing utility functions */
75
76 static void
print_bool_feature(const char * feat_name,const char * plain_name,const char * define_name,bool res,const char * define_prefix)77 print_bool_feature(const char *feat_name, const char *plain_name,
78 const char *define_name, bool res, const char *define_prefix)
79 {
80 if (json_output)
81 jsonw_bool_field(json_wtr, feat_name, res);
82 else if (define_prefix)
83 printf("#define %s%sHAVE_%s\n", define_prefix,
84 res ? "" : "NO_", define_name);
85 else
86 printf("%s is %savailable\n", plain_name, res ? "" : "NOT ");
87 }
88
print_kernel_option(const char * name,const char * value,const char * define_prefix)89 static void print_kernel_option(const char *name, const char *value,
90 const char *define_prefix)
91 {
92 char *endptr;
93 int res;
94
95 if (json_output) {
96 if (!value) {
97 jsonw_null_field(json_wtr, name);
98 return;
99 }
100 errno = 0;
101 res = strtol(value, &endptr, 0);
102 if (!errno && *endptr == '\n')
103 jsonw_int_field(json_wtr, name, res);
104 else
105 jsonw_string_field(json_wtr, name, value);
106 } else if (define_prefix) {
107 if (value)
108 printf("#define %s%s %s\n", define_prefix,
109 name, value);
110 else
111 printf("/* %s%s is not set */\n", define_prefix, name);
112 } else {
113 if (value)
114 printf("%s is set to %s\n", name, value);
115 else
116 printf("%s is not set\n", name);
117 }
118 }
119
120 static void
print_start_section(const char * json_title,const char * plain_title,const char * define_comment,const char * define_prefix)121 print_start_section(const char *json_title, const char *plain_title,
122 const char *define_comment, const char *define_prefix)
123 {
124 if (json_output) {
125 jsonw_name(json_wtr, json_title);
126 jsonw_start_object(json_wtr);
127 } else if (define_prefix) {
128 printf("%s\n", define_comment);
129 } else {
130 printf("%s\n", plain_title);
131 }
132 }
133
print_end_section(void)134 static void print_end_section(void)
135 {
136 if (json_output)
137 jsonw_end_object(json_wtr);
138 else
139 printf("\n");
140 }
141
142 /* Probing functions */
143
get_vendor_id(int ifindex)144 static int get_vendor_id(int ifindex)
145 {
146 char ifname[IF_NAMESIZE], path[64], buf[8];
147 ssize_t len;
148 int fd;
149
150 if (!if_indextoname(ifindex, ifname))
151 return -1;
152
153 snprintf(path, sizeof(path), "/sys/class/net/%s/device/vendor", ifname);
154
155 fd = open(path, O_RDONLY | O_CLOEXEC);
156 if (fd < 0)
157 return -1;
158
159 len = read(fd, buf, sizeof(buf));
160 close(fd);
161 if (len < 0)
162 return -1;
163 if (len >= (ssize_t)sizeof(buf))
164 return -1;
165 buf[len] = '\0';
166
167 return strtol(buf, NULL, 0);
168 }
169
read_procfs(const char * path)170 static long read_procfs(const char *path)
171 {
172 char *endptr, *line = NULL;
173 size_t len = 0;
174 FILE *fd;
175 long res;
176
177 fd = fopen(path, "r");
178 if (!fd)
179 return -1;
180
181 res = getline(&line, &len, fd);
182 fclose(fd);
183 if (res < 0)
184 return -1;
185
186 errno = 0;
187 res = strtol(line, &endptr, 10);
188 if (errno || *line == '\0' || *endptr != '\n')
189 res = -1;
190 free(line);
191
192 return res;
193 }
194
probe_unprivileged_disabled(void)195 static void probe_unprivileged_disabled(void)
196 {
197 long res;
198
199 /* No support for C-style output */
200
201 res = read_procfs("/proc/sys/kernel/unprivileged_bpf_disabled");
202 if (json_output) {
203 jsonw_int_field(json_wtr, "unprivileged_bpf_disabled", res);
204 } else {
205 switch (res) {
206 case 0:
207 printf("bpf() syscall for unprivileged users is enabled\n");
208 break;
209 case 1:
210 printf("bpf() syscall restricted to privileged users (without recovery)\n");
211 break;
212 case 2:
213 printf("bpf() syscall restricted to privileged users (admin can change)\n");
214 break;
215 case -1:
216 printf("Unable to retrieve required privileges for bpf() syscall\n");
217 break;
218 default:
219 printf("bpf() syscall restriction has unknown value %ld\n", res);
220 }
221 }
222 }
223
probe_jit_enable(void)224 static void probe_jit_enable(void)
225 {
226 long res;
227
228 /* No support for C-style output */
229
230 res = read_procfs("/proc/sys/net/core/bpf_jit_enable");
231 if (json_output) {
232 jsonw_int_field(json_wtr, "bpf_jit_enable", res);
233 } else {
234 switch (res) {
235 case 0:
236 printf("JIT compiler is disabled\n");
237 break;
238 case 1:
239 printf("JIT compiler is enabled\n");
240 break;
241 case 2:
242 printf("JIT compiler is enabled with debugging traces in kernel logs\n");
243 break;
244 case -1:
245 printf("Unable to retrieve JIT-compiler status\n");
246 break;
247 default:
248 printf("JIT-compiler status has unknown value %ld\n",
249 res);
250 }
251 }
252 }
253
probe_jit_harden(void)254 static void probe_jit_harden(void)
255 {
256 long res;
257
258 /* No support for C-style output */
259
260 res = read_procfs("/proc/sys/net/core/bpf_jit_harden");
261 if (json_output) {
262 jsonw_int_field(json_wtr, "bpf_jit_harden", res);
263 } else {
264 switch (res) {
265 case 0:
266 printf("JIT compiler hardening is disabled\n");
267 break;
268 case 1:
269 printf("JIT compiler hardening is enabled for unprivileged users\n");
270 break;
271 case 2:
272 printf("JIT compiler hardening is enabled for all users\n");
273 break;
274 case -1:
275 printf("Unable to retrieve JIT hardening status\n");
276 break;
277 default:
278 printf("JIT hardening status has unknown value %ld\n",
279 res);
280 }
281 }
282 }
283
probe_jit_kallsyms(void)284 static void probe_jit_kallsyms(void)
285 {
286 long res;
287
288 /* No support for C-style output */
289
290 res = read_procfs("/proc/sys/net/core/bpf_jit_kallsyms");
291 if (json_output) {
292 jsonw_int_field(json_wtr, "bpf_jit_kallsyms", res);
293 } else {
294 switch (res) {
295 case 0:
296 printf("JIT compiler kallsyms exports are disabled\n");
297 break;
298 case 1:
299 printf("JIT compiler kallsyms exports are enabled for root\n");
300 break;
301 case -1:
302 printf("Unable to retrieve JIT kallsyms export status\n");
303 break;
304 default:
305 printf("JIT kallsyms exports status has unknown value %ld\n", res);
306 }
307 }
308 }
309
probe_jit_limit(void)310 static void probe_jit_limit(void)
311 {
312 long res;
313
314 /* No support for C-style output */
315
316 res = read_procfs("/proc/sys/net/core/bpf_jit_limit");
317 if (json_output) {
318 jsonw_int_field(json_wtr, "bpf_jit_limit", res);
319 } else {
320 switch (res) {
321 case -1:
322 printf("Unable to retrieve global memory limit for JIT compiler for unprivileged users\n");
323 break;
324 default:
325 printf("Global memory limit for JIT compiler for unprivileged users is %ld bytes\n", res);
326 }
327 }
328 }
329
read_next_kernel_config_option(gzFile file,char * buf,size_t n,char ** value)330 static bool read_next_kernel_config_option(gzFile file, char *buf, size_t n,
331 char **value)
332 {
333 char *sep;
334
335 while (gzgets(file, buf, n)) {
336 if (strncmp(buf, "CONFIG_", 7))
337 continue;
338
339 sep = strchr(buf, '=');
340 if (!sep)
341 continue;
342
343 /* Trim ending '\n' */
344 buf[strlen(buf) - 1] = '\0';
345
346 /* Split on '=' and ensure that a value is present. */
347 *sep = '\0';
348 if (!sep[1])
349 continue;
350
351 *value = sep + 1;
352 return true;
353 }
354
355 return false;
356 }
357
probe_kernel_image_config(const char * define_prefix)358 static void probe_kernel_image_config(const char *define_prefix)
359 {
360 static const struct {
361 const char * const name;
362 bool macro_dump;
363 } options[] = {
364 /* Enable BPF */
365 { "CONFIG_BPF", },
366 /* Enable bpf() syscall */
367 { "CONFIG_BPF_SYSCALL", },
368 /* Does selected architecture support eBPF JIT compiler */
369 { "CONFIG_HAVE_EBPF_JIT", },
370 /* Compile eBPF JIT compiler */
371 { "CONFIG_BPF_JIT", },
372 /* Avoid compiling eBPF interpreter (use JIT only) */
373 { "CONFIG_BPF_JIT_ALWAYS_ON", },
374 /* Kernel BTF debug information available */
375 { "CONFIG_DEBUG_INFO_BTF", },
376 /* Kernel module BTF debug information available */
377 { "CONFIG_DEBUG_INFO_BTF_MODULES", },
378
379 /* cgroups */
380 { "CONFIG_CGROUPS", },
381 /* BPF programs attached to cgroups */
382 { "CONFIG_CGROUP_BPF", },
383 /* bpf_get_cgroup_classid() helper */
384 { "CONFIG_CGROUP_NET_CLASSID", },
385 /* bpf_skb_{,ancestor_}cgroup_id() helpers */
386 { "CONFIG_SOCK_CGROUP_DATA", },
387
388 /* Tracing: attach BPF to kprobes, tracepoints, etc. */
389 { "CONFIG_BPF_EVENTS", },
390 /* Kprobes */
391 { "CONFIG_KPROBE_EVENTS", },
392 /* Uprobes */
393 { "CONFIG_UPROBE_EVENTS", },
394 /* Tracepoints */
395 { "CONFIG_TRACING", },
396 /* Syscall tracepoints */
397 { "CONFIG_FTRACE_SYSCALLS", },
398 /* bpf_override_return() helper support for selected arch */
399 { "CONFIG_FUNCTION_ERROR_INJECTION", },
400 /* bpf_override_return() helper */
401 { "CONFIG_BPF_KPROBE_OVERRIDE", },
402
403 /* Network */
404 { "CONFIG_NET", },
405 /* AF_XDP sockets */
406 { "CONFIG_XDP_SOCKETS", },
407 /* BPF_PROG_TYPE_LWT_* and related helpers */
408 { "CONFIG_LWTUNNEL_BPF", },
409 /* BPF_PROG_TYPE_SCHED_ACT, TC (traffic control) actions */
410 { "CONFIG_NET_ACT_BPF", },
411 /* BPF_PROG_TYPE_SCHED_CLS, TC filters */
412 { "CONFIG_NET_CLS_BPF", },
413 /* TC clsact qdisc */
414 { "CONFIG_NET_CLS_ACT", },
415 /* Ingress filtering with TC */
416 { "CONFIG_NET_SCH_INGRESS", },
417 /* bpf_skb_get_xfrm_state() helper */
418 { "CONFIG_XFRM", },
419 /* bpf_get_route_realm() helper */
420 { "CONFIG_IP_ROUTE_CLASSID", },
421 /* BPF_PROG_TYPE_LWT_SEG6_LOCAL and related helpers */
422 { "CONFIG_IPV6_SEG6_BPF", },
423 /* BPF_PROG_TYPE_LIRC_MODE2 and related helpers */
424 { "CONFIG_BPF_LIRC_MODE2", },
425 /* BPF stream parser and BPF socket maps */
426 { "CONFIG_BPF_STREAM_PARSER", },
427 /* xt_bpf module for passing BPF programs to netfilter */
428 { "CONFIG_NETFILTER_XT_MATCH_BPF", },
429
430 /* test_bpf module for BPF tests */
431 { "CONFIG_TEST_BPF", },
432
433 /* Misc configs useful in BPF C programs */
434 /* jiffies <-> sec conversion for bpf_jiffies64() helper */
435 { "CONFIG_HZ", true, }
436 };
437 char *values[ARRAY_SIZE(options)] = { };
438 struct utsname utsn;
439 char path[PATH_MAX];
440 gzFile file = NULL;
441 char buf[4096];
442 char *value;
443 size_t i;
444
445 if (!uname(&utsn)) {
446 snprintf(path, sizeof(path), "/boot/config-%s", utsn.release);
447
448 /* gzopen also accepts uncompressed files. */
449 file = gzopen(path, "r");
450 }
451
452 if (!file) {
453 /* Some distributions build with CONFIG_IKCONFIG=y and put the
454 * config file at /proc/config.gz.
455 */
456 file = gzopen("/proc/config.gz", "r");
457 }
458 if (!file) {
459 p_info("skipping kernel config, can't open file: %s",
460 strerror(errno));
461 goto end_parse;
462 }
463 /* Sanity checks */
464 if (!gzgets(file, buf, sizeof(buf)) ||
465 !gzgets(file, buf, sizeof(buf))) {
466 p_info("skipping kernel config, can't read from file: %s",
467 strerror(errno));
468 goto end_parse;
469 }
470 if (strcmp(buf, "# Automatically generated file; DO NOT EDIT.\n")) {
471 p_info("skipping kernel config, can't find correct file");
472 goto end_parse;
473 }
474
475 while (read_next_kernel_config_option(file, buf, sizeof(buf), &value)) {
476 for (i = 0; i < ARRAY_SIZE(options); i++) {
477 if ((define_prefix && !options[i].macro_dump) ||
478 values[i] || strcmp(buf, options[i].name))
479 continue;
480
481 values[i] = strdup(value);
482 }
483 }
484
485 for (i = 0; i < ARRAY_SIZE(options); i++) {
486 if (define_prefix && !options[i].macro_dump)
487 continue;
488 print_kernel_option(options[i].name, values[i], define_prefix);
489 free(values[i]);
490 }
491
492 end_parse:
493 if (file)
494 gzclose(file);
495 }
496
probe_bpf_syscall(const char * define_prefix)497 static bool probe_bpf_syscall(const char *define_prefix)
498 {
499 bool res;
500
501 bpf_prog_load(BPF_PROG_TYPE_UNSPEC, NULL, NULL, NULL, 0, NULL);
502 res = (errno != ENOSYS);
503
504 print_bool_feature("have_bpf_syscall",
505 "bpf() syscall",
506 "BPF_SYSCALL",
507 res, define_prefix);
508
509 return res;
510 }
511
512 static bool
probe_prog_load_ifindex(enum bpf_prog_type prog_type,const struct bpf_insn * insns,size_t insns_cnt,char * log_buf,size_t log_buf_sz,__u32 ifindex)513 probe_prog_load_ifindex(enum bpf_prog_type prog_type,
514 const struct bpf_insn *insns, size_t insns_cnt,
515 char *log_buf, size_t log_buf_sz,
516 __u32 ifindex)
517 {
518 LIBBPF_OPTS(bpf_prog_load_opts, opts,
519 .log_buf = log_buf,
520 .log_size = log_buf_sz,
521 .log_level = log_buf ? 1 : 0,
522 .prog_ifindex = ifindex,
523 );
524 int fd;
525
526 errno = 0;
527 fd = bpf_prog_load(prog_type, NULL, "GPL", insns, insns_cnt, &opts);
528 if (fd >= 0)
529 close(fd);
530
531 return fd >= 0 && errno != EINVAL && errno != EOPNOTSUPP;
532 }
533
probe_prog_type_ifindex(enum bpf_prog_type prog_type,__u32 ifindex)534 static bool probe_prog_type_ifindex(enum bpf_prog_type prog_type, __u32 ifindex)
535 {
536 /* nfp returns -EINVAL on exit(0) with TC offload */
537 struct bpf_insn insns[2] = {
538 BPF_MOV64_IMM(BPF_REG_0, 2),
539 BPF_EXIT_INSN()
540 };
541
542 return probe_prog_load_ifindex(prog_type, insns, ARRAY_SIZE(insns),
543 NULL, 0, ifindex);
544 }
545
546 static void
probe_prog_type(enum bpf_prog_type prog_type,const char * prog_type_str,bool * supported_types,const char * define_prefix,__u32 ifindex)547 probe_prog_type(enum bpf_prog_type prog_type, const char *prog_type_str,
548 bool *supported_types, const char *define_prefix, __u32 ifindex)
549 {
550 char feat_name[128], plain_desc[128], define_name[128];
551 const char *plain_comment = "eBPF program_type ";
552 size_t maxlen;
553 bool res;
554
555 if (ifindex) {
556 switch (prog_type) {
557 case BPF_PROG_TYPE_SCHED_CLS:
558 case BPF_PROG_TYPE_XDP:
559 break;
560 default:
561 return;
562 }
563
564 res = probe_prog_type_ifindex(prog_type, ifindex);
565 } else {
566 res = libbpf_probe_bpf_prog_type(prog_type, NULL) > 0;
567 }
568
569 #ifdef USE_LIBCAP
570 /* Probe may succeed even if program load fails, for unprivileged users
571 * check that we did not fail because of insufficient permissions
572 */
573 if (run_as_unprivileged && errno == EPERM)
574 res = false;
575 #endif
576
577 supported_types[prog_type] |= res;
578
579 maxlen = sizeof(plain_desc) - strlen(plain_comment) - 1;
580 if (strlen(prog_type_str) > maxlen) {
581 p_info("program type name too long");
582 return;
583 }
584
585 sprintf(feat_name, "have_%s_prog_type", prog_type_str);
586 sprintf(define_name, "%s_prog_type", prog_type_str);
587 uppercase(define_name, sizeof(define_name));
588 sprintf(plain_desc, "%s%s", plain_comment, prog_type_str);
589 print_bool_feature(feat_name, plain_desc, define_name, res,
590 define_prefix);
591 }
592
probe_map_type_ifindex(enum bpf_map_type map_type,__u32 ifindex)593 static bool probe_map_type_ifindex(enum bpf_map_type map_type, __u32 ifindex)
594 {
595 LIBBPF_OPTS(bpf_map_create_opts, opts);
596 int key_size, value_size, max_entries;
597 int fd;
598
599 opts.map_ifindex = ifindex;
600
601 key_size = sizeof(__u32);
602 value_size = sizeof(__u32);
603 max_entries = 1;
604
605 fd = bpf_map_create(map_type, NULL, key_size, value_size, max_entries,
606 &opts);
607 if (fd >= 0)
608 close(fd);
609
610 return fd >= 0;
611 }
612
613 static void
probe_map_type(enum bpf_map_type map_type,char const * map_type_str,const char * define_prefix,__u32 ifindex)614 probe_map_type(enum bpf_map_type map_type, char const *map_type_str,
615 const char *define_prefix, __u32 ifindex)
616 {
617 char feat_name[128], plain_desc[128], define_name[128];
618 const char *plain_comment = "eBPF map_type ";
619 size_t maxlen;
620 bool res;
621
622 if (ifindex) {
623 switch (map_type) {
624 case BPF_MAP_TYPE_HASH:
625 case BPF_MAP_TYPE_ARRAY:
626 break;
627 default:
628 return;
629 }
630
631 res = probe_map_type_ifindex(map_type, ifindex);
632 } else {
633 res = libbpf_probe_bpf_map_type(map_type, NULL) > 0;
634 }
635
636 /* Probe result depends on the success of map creation, no additional
637 * check required for unprivileged users
638 */
639
640 maxlen = sizeof(plain_desc) - strlen(plain_comment) - 1;
641 if (strlen(map_type_str) > maxlen) {
642 p_info("map type name too long");
643 return;
644 }
645
646 sprintf(feat_name, "have_%s_map_type", map_type_str);
647 sprintf(define_name, "%s_map_type", map_type_str);
648 uppercase(define_name, sizeof(define_name));
649 sprintf(plain_desc, "%s%s", plain_comment, map_type_str);
650 print_bool_feature(feat_name, plain_desc, define_name, res,
651 define_prefix);
652 }
653
654 static bool
probe_helper_ifindex(enum bpf_func_id id,enum bpf_prog_type prog_type,__u32 ifindex)655 probe_helper_ifindex(enum bpf_func_id id, enum bpf_prog_type prog_type,
656 __u32 ifindex)
657 {
658 struct bpf_insn insns[2] = {
659 BPF_EMIT_CALL(id),
660 BPF_EXIT_INSN()
661 };
662 char buf[4096] = {};
663 bool res;
664
665 probe_prog_load_ifindex(prog_type, insns, ARRAY_SIZE(insns), buf,
666 sizeof(buf), ifindex);
667 res = !grep(buf, "invalid func ") && !grep(buf, "unknown func ") &&
668 !grep(buf, "program of this type cannot use helper ");
669
670 switch (get_vendor_id(ifindex)) {
671 case 0x19ee: /* Netronome specific */
672 res = res && !grep(buf, "not supported by FW") &&
673 !grep(buf, "unsupported function id");
674 break;
675 default:
676 break;
677 }
678
679 return res;
680 }
681
682 static bool
probe_helper_for_progtype(enum bpf_prog_type prog_type,bool supported_type,const char * define_prefix,unsigned int id,const char * ptype_name,__u32 ifindex)683 probe_helper_for_progtype(enum bpf_prog_type prog_type, bool supported_type,
684 const char *define_prefix, unsigned int id,
685 const char *ptype_name, __u32 ifindex)
686 {
687 bool res = false;
688
689 if (supported_type) {
690 if (ifindex)
691 res = probe_helper_ifindex(id, prog_type, ifindex);
692 else
693 res = libbpf_probe_bpf_helper(prog_type, id, NULL) > 0;
694 #ifdef USE_LIBCAP
695 /* Probe may succeed even if program load fails, for
696 * unprivileged users check that we did not fail because of
697 * insufficient permissions
698 */
699 if (run_as_unprivileged && errno == EPERM)
700 res = false;
701 #endif
702 }
703
704 if (json_output) {
705 if (res)
706 jsonw_string(json_wtr, helper_name[id]);
707 } else if (define_prefix) {
708 printf("#define %sBPF__PROG_TYPE_%s__HELPER_%s %s\n",
709 define_prefix, ptype_name, helper_name[id],
710 res ? "1" : "0");
711 } else {
712 if (res)
713 printf("\n\t- %s", helper_name[id]);
714 }
715
716 return res;
717 }
718
719 static void
probe_helpers_for_progtype(enum bpf_prog_type prog_type,const char * prog_type_str,bool supported_type,const char * define_prefix,__u32 ifindex)720 probe_helpers_for_progtype(enum bpf_prog_type prog_type,
721 const char *prog_type_str, bool supported_type,
722 const char *define_prefix, __u32 ifindex)
723 {
724 char feat_name[128];
725 unsigned int id;
726 bool probe_res = false;
727
728 if (ifindex)
729 /* Only test helpers for offload-able program types */
730 switch (prog_type) {
731 case BPF_PROG_TYPE_SCHED_CLS:
732 case BPF_PROG_TYPE_XDP:
733 break;
734 default:
735 return;
736 }
737
738 if (json_output) {
739 sprintf(feat_name, "%s_available_helpers", prog_type_str);
740 jsonw_name(json_wtr, feat_name);
741 jsonw_start_array(json_wtr);
742 } else if (!define_prefix) {
743 printf("eBPF helpers supported for program type %s:",
744 prog_type_str);
745 }
746
747 for (id = 1; id < ARRAY_SIZE(helper_name); id++) {
748 /* Skip helper functions which emit dmesg messages when not in
749 * the full mode.
750 */
751 switch (id) {
752 case BPF_FUNC_trace_printk:
753 case BPF_FUNC_trace_vprintk:
754 case BPF_FUNC_probe_write_user:
755 if (!full_mode)
756 continue;
757 fallthrough;
758 default:
759 probe_res |= probe_helper_for_progtype(prog_type, supported_type,
760 define_prefix, id, prog_type_str,
761 ifindex);
762 }
763 }
764
765 if (json_output)
766 jsonw_end_array(json_wtr);
767 else if (!define_prefix) {
768 printf("\n");
769 if (!probe_res) {
770 if (!supported_type)
771 printf("\tProgram type not supported\n");
772 else
773 printf("\tCould not determine which helpers are available\n");
774 }
775 }
776
777
778 }
779
780 static void
probe_misc_feature(struct bpf_insn * insns,size_t len,const char * define_prefix,__u32 ifindex,const char * feat_name,const char * plain_name,const char * define_name)781 probe_misc_feature(struct bpf_insn *insns, size_t len,
782 const char *define_prefix, __u32 ifindex,
783 const char *feat_name, const char *plain_name,
784 const char *define_name)
785 {
786 LIBBPF_OPTS(bpf_prog_load_opts, opts,
787 .prog_ifindex = ifindex,
788 );
789 bool res;
790 int fd;
791
792 errno = 0;
793 fd = bpf_prog_load(BPF_PROG_TYPE_SOCKET_FILTER, NULL, "GPL",
794 insns, len, &opts);
795 res = fd >= 0 || !errno;
796
797 if (fd >= 0)
798 close(fd);
799
800 print_bool_feature(feat_name, plain_name, define_name, res,
801 define_prefix);
802 }
803
804 /*
805 * Probe for availability of kernel commit (5.3):
806 *
807 * c04c0d2b968a ("bpf: increase complexity limit and maximum program size")
808 */
probe_large_insn_limit(const char * define_prefix,__u32 ifindex)809 static void probe_large_insn_limit(const char *define_prefix, __u32 ifindex)
810 {
811 struct bpf_insn insns[BPF_MAXINSNS + 1];
812 int i;
813
814 for (i = 0; i < BPF_MAXINSNS; i++)
815 insns[i] = BPF_MOV64_IMM(BPF_REG_0, 1);
816 insns[BPF_MAXINSNS] = BPF_EXIT_INSN();
817
818 probe_misc_feature(insns, ARRAY_SIZE(insns),
819 define_prefix, ifindex,
820 "have_large_insn_limit",
821 "Large program size limit",
822 "LARGE_INSN_LIMIT");
823 }
824
825 /*
826 * Probe for bounded loop support introduced in commit 2589726d12a1
827 * ("bpf: introduce bounded loops").
828 */
829 static void
probe_bounded_loops(const char * define_prefix,__u32 ifindex)830 probe_bounded_loops(const char *define_prefix, __u32 ifindex)
831 {
832 struct bpf_insn insns[4] = {
833 BPF_MOV64_IMM(BPF_REG_0, 10),
834 BPF_ALU64_IMM(BPF_SUB, BPF_REG_0, 1),
835 BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 0, -2),
836 BPF_EXIT_INSN()
837 };
838
839 probe_misc_feature(insns, ARRAY_SIZE(insns),
840 define_prefix, ifindex,
841 "have_bounded_loops",
842 "Bounded loop support",
843 "BOUNDED_LOOPS");
844 }
845
846 /*
847 * Probe for the v2 instruction set extension introduced in commit 92b31a9af73b
848 * ("bpf: add BPF_J{LT,LE,SLT,SLE} instructions").
849 */
850 static void
probe_v2_isa_extension(const char * define_prefix,__u32 ifindex)851 probe_v2_isa_extension(const char *define_prefix, __u32 ifindex)
852 {
853 struct bpf_insn insns[4] = {
854 BPF_MOV64_IMM(BPF_REG_0, 0),
855 BPF_JMP_IMM(BPF_JLT, BPF_REG_0, 0, 1),
856 BPF_MOV64_IMM(BPF_REG_0, 1),
857 BPF_EXIT_INSN()
858 };
859
860 probe_misc_feature(insns, ARRAY_SIZE(insns),
861 define_prefix, ifindex,
862 "have_v2_isa_extension",
863 "ISA extension v2",
864 "V2_ISA_EXTENSION");
865 }
866
867 /*
868 * Probe for the v3 instruction set extension introduced in commit 092ed0968bb6
869 * ("bpf: verifier support JMP32").
870 */
871 static void
probe_v3_isa_extension(const char * define_prefix,__u32 ifindex)872 probe_v3_isa_extension(const char *define_prefix, __u32 ifindex)
873 {
874 struct bpf_insn insns[4] = {
875 BPF_MOV64_IMM(BPF_REG_0, 0),
876 BPF_JMP32_IMM(BPF_JLT, BPF_REG_0, 0, 1),
877 BPF_MOV64_IMM(BPF_REG_0, 1),
878 BPF_EXIT_INSN()
879 };
880
881 probe_misc_feature(insns, ARRAY_SIZE(insns),
882 define_prefix, ifindex,
883 "have_v3_isa_extension",
884 "ISA extension v3",
885 "V3_ISA_EXTENSION");
886 }
887
888 static void
section_system_config(enum probe_component target,const char * define_prefix)889 section_system_config(enum probe_component target, const char *define_prefix)
890 {
891 switch (target) {
892 case COMPONENT_KERNEL:
893 case COMPONENT_UNSPEC:
894 print_start_section("system_config",
895 "Scanning system configuration...",
896 "/*** Misc kernel config items ***/",
897 define_prefix);
898 if (!define_prefix) {
899 if (check_procfs()) {
900 probe_unprivileged_disabled();
901 probe_jit_enable();
902 probe_jit_harden();
903 probe_jit_kallsyms();
904 probe_jit_limit();
905 } else {
906 p_info("/* procfs not mounted, skipping related probes */");
907 }
908 }
909 probe_kernel_image_config(define_prefix);
910 print_end_section();
911 break;
912 default:
913 break;
914 }
915 }
916
section_syscall_config(const char * define_prefix)917 static bool section_syscall_config(const char *define_prefix)
918 {
919 bool res;
920
921 print_start_section("syscall_config",
922 "Scanning system call availability...",
923 "/*** System call availability ***/",
924 define_prefix);
925 res = probe_bpf_syscall(define_prefix);
926 print_end_section();
927
928 return res;
929 }
930
931 static void
section_program_types(bool * supported_types,const char * define_prefix,__u32 ifindex)932 section_program_types(bool *supported_types, const char *define_prefix,
933 __u32 ifindex)
934 {
935 unsigned int prog_type = BPF_PROG_TYPE_UNSPEC;
936 const char *prog_type_str;
937
938 print_start_section("program_types",
939 "Scanning eBPF program types...",
940 "/*** eBPF program types ***/",
941 define_prefix);
942
943 while (true) {
944 prog_type++;
945 prog_type_str = libbpf_bpf_prog_type_str(prog_type);
946 /* libbpf will return NULL for variants unknown to it. */
947 if (!prog_type_str)
948 break;
949
950 probe_prog_type(prog_type, prog_type_str, supported_types, define_prefix,
951 ifindex);
952 }
953
954 print_end_section();
955 }
956
section_map_types(const char * define_prefix,__u32 ifindex)957 static void section_map_types(const char *define_prefix, __u32 ifindex)
958 {
959 unsigned int map_type = BPF_MAP_TYPE_UNSPEC;
960 const char *map_type_str;
961
962 print_start_section("map_types",
963 "Scanning eBPF map types...",
964 "/*** eBPF map types ***/",
965 define_prefix);
966
967 while (true) {
968 map_type++;
969 map_type_str = libbpf_bpf_map_type_str(map_type);
970 /* libbpf will return NULL for variants unknown to it. */
971 if (!map_type_str)
972 break;
973
974 probe_map_type(map_type, map_type_str, define_prefix, ifindex);
975 }
976
977 print_end_section();
978 }
979
980 static void
section_helpers(bool * supported_types,const char * define_prefix,__u32 ifindex)981 section_helpers(bool *supported_types, const char *define_prefix, __u32 ifindex)
982 {
983 unsigned int prog_type = BPF_PROG_TYPE_UNSPEC;
984 const char *prog_type_str;
985
986 print_start_section("helpers",
987 "Scanning eBPF helper functions...",
988 "/*** eBPF helper functions ***/",
989 define_prefix);
990
991 if (define_prefix)
992 printf("/*\n"
993 " * Use %sHAVE_PROG_TYPE_HELPER(prog_type_name, helper_name)\n"
994 " * to determine if <helper_name> is available for <prog_type_name>,\n"
995 " * e.g.\n"
996 " * #if %sHAVE_PROG_TYPE_HELPER(xdp, bpf_redirect)\n"
997 " * // do stuff with this helper\n"
998 " * #elif\n"
999 " * // use a workaround\n"
1000 " * #endif\n"
1001 " */\n"
1002 "#define %sHAVE_PROG_TYPE_HELPER(prog_type, helper) \\\n"
1003 " %sBPF__PROG_TYPE_ ## prog_type ## __HELPER_ ## helper\n",
1004 define_prefix, define_prefix, define_prefix,
1005 define_prefix);
1006 while (true) {
1007 prog_type++;
1008 prog_type_str = libbpf_bpf_prog_type_str(prog_type);
1009 /* libbpf will return NULL for variants unknown to it. */
1010 if (!prog_type_str)
1011 break;
1012
1013 probe_helpers_for_progtype(prog_type, prog_type_str,
1014 supported_types[prog_type],
1015 define_prefix,
1016 ifindex);
1017 }
1018
1019 print_end_section();
1020 }
1021
section_misc(const char * define_prefix,__u32 ifindex)1022 static void section_misc(const char *define_prefix, __u32 ifindex)
1023 {
1024 print_start_section("misc",
1025 "Scanning miscellaneous eBPF features...",
1026 "/*** eBPF misc features ***/",
1027 define_prefix);
1028 probe_large_insn_limit(define_prefix, ifindex);
1029 probe_bounded_loops(define_prefix, ifindex);
1030 probe_v2_isa_extension(define_prefix, ifindex);
1031 probe_v3_isa_extension(define_prefix, ifindex);
1032 print_end_section();
1033 }
1034
1035 #ifdef USE_LIBCAP
1036 #define capability(c) { c, false, #c }
1037 #define capability_msg(a, i) a[i].set ? "" : a[i].name, a[i].set ? "" : ", "
1038 #endif
1039
handle_perms(void)1040 static int handle_perms(void)
1041 {
1042 #ifdef USE_LIBCAP
1043 struct {
1044 cap_value_t cap;
1045 bool set;
1046 char name[14]; /* strlen("CAP_SYS_ADMIN") */
1047 } bpf_caps[] = {
1048 capability(CAP_SYS_ADMIN),
1049 #ifdef CAP_BPF
1050 capability(CAP_BPF),
1051 capability(CAP_NET_ADMIN),
1052 capability(CAP_PERFMON),
1053 #endif
1054 };
1055 cap_value_t cap_list[ARRAY_SIZE(bpf_caps)];
1056 unsigned int i, nb_bpf_caps = 0;
1057 bool cap_sys_admin_only = true;
1058 cap_flag_value_t val;
1059 int res = -1;
1060 cap_t caps;
1061
1062 caps = cap_get_proc();
1063 if (!caps) {
1064 p_err("failed to get capabilities for process: %s",
1065 strerror(errno));
1066 return -1;
1067 }
1068
1069 #ifdef CAP_BPF
1070 if (CAP_IS_SUPPORTED(CAP_BPF))
1071 cap_sys_admin_only = false;
1072 #endif
1073
1074 for (i = 0; i < ARRAY_SIZE(bpf_caps); i++) {
1075 const char *cap_name = bpf_caps[i].name;
1076 cap_value_t cap = bpf_caps[i].cap;
1077
1078 if (cap_get_flag(caps, cap, CAP_EFFECTIVE, &val)) {
1079 p_err("bug: failed to retrieve %s status: %s", cap_name,
1080 strerror(errno));
1081 goto exit_free;
1082 }
1083
1084 if (val == CAP_SET) {
1085 bpf_caps[i].set = true;
1086 cap_list[nb_bpf_caps++] = cap;
1087 }
1088
1089 if (cap_sys_admin_only)
1090 /* System does not know about CAP_BPF, meaning that
1091 * CAP_SYS_ADMIN is the only capability required. We
1092 * just checked it, break.
1093 */
1094 break;
1095 }
1096
1097 if ((run_as_unprivileged && !nb_bpf_caps) ||
1098 (!run_as_unprivileged && nb_bpf_caps == ARRAY_SIZE(bpf_caps)) ||
1099 (!run_as_unprivileged && cap_sys_admin_only && nb_bpf_caps)) {
1100 /* We are all good, exit now */
1101 res = 0;
1102 goto exit_free;
1103 }
1104
1105 if (!run_as_unprivileged) {
1106 if (cap_sys_admin_only)
1107 p_err("missing %s, required for full feature probing; run as root or use 'unprivileged'",
1108 bpf_caps[0].name);
1109 else
1110 p_err("missing %s%s%s%s%s%s%s%srequired for full feature probing; run as root or use 'unprivileged'",
1111 capability_msg(bpf_caps, 0),
1112 #ifdef CAP_BPF
1113 capability_msg(bpf_caps, 1),
1114 capability_msg(bpf_caps, 2),
1115 capability_msg(bpf_caps, 3)
1116 #else
1117 "", "", "", "", "", ""
1118 #endif /* CAP_BPF */
1119 );
1120 goto exit_free;
1121 }
1122
1123 /* if (run_as_unprivileged && nb_bpf_caps > 0), drop capabilities. */
1124 if (cap_set_flag(caps, CAP_EFFECTIVE, nb_bpf_caps, cap_list,
1125 CAP_CLEAR)) {
1126 p_err("bug: failed to clear capabilities: %s", strerror(errno));
1127 goto exit_free;
1128 }
1129
1130 if (cap_set_proc(caps)) {
1131 p_err("failed to drop capabilities: %s", strerror(errno));
1132 goto exit_free;
1133 }
1134
1135 res = 0;
1136
1137 exit_free:
1138 if (cap_free(caps) && !res) {
1139 p_err("failed to clear storage object for capabilities: %s",
1140 strerror(errno));
1141 res = -1;
1142 }
1143
1144 return res;
1145 #else
1146 /* Detection assumes user has specific privileges.
1147 * We do not use libcap so let's approximate, and restrict usage to
1148 * root user only.
1149 */
1150 if (geteuid()) {
1151 p_err("full feature probing requires root privileges");
1152 return -1;
1153 }
1154
1155 return 0;
1156 #endif /* USE_LIBCAP */
1157 }
1158
do_probe(int argc,char ** argv)1159 static int do_probe(int argc, char **argv)
1160 {
1161 enum probe_component target = COMPONENT_UNSPEC;
1162 const char *define_prefix = NULL;
1163 bool supported_types[128] = {};
1164 __u32 ifindex = 0;
1165 char *ifname;
1166
1167 set_max_rlimit();
1168
1169 while (argc) {
1170 if (is_prefix(*argv, "kernel")) {
1171 if (target != COMPONENT_UNSPEC) {
1172 p_err("component to probe already specified");
1173 return -1;
1174 }
1175 target = COMPONENT_KERNEL;
1176 NEXT_ARG();
1177 } else if (is_prefix(*argv, "dev")) {
1178 NEXT_ARG();
1179
1180 if (target != COMPONENT_UNSPEC || ifindex) {
1181 p_err("component to probe already specified");
1182 return -1;
1183 }
1184 if (!REQ_ARGS(1))
1185 return -1;
1186
1187 target = COMPONENT_DEVICE;
1188 ifname = GET_ARG();
1189 ifindex = if_nametoindex(ifname);
1190 if (!ifindex) {
1191 p_err("unrecognized netdevice '%s': %s", ifname,
1192 strerror(errno));
1193 return -1;
1194 }
1195 } else if (is_prefix(*argv, "full")) {
1196 full_mode = true;
1197 NEXT_ARG();
1198 } else if (is_prefix(*argv, "macros") && !define_prefix) {
1199 define_prefix = "";
1200 NEXT_ARG();
1201 } else if (is_prefix(*argv, "prefix")) {
1202 if (!define_prefix) {
1203 p_err("'prefix' argument can only be use after 'macros'");
1204 return -1;
1205 }
1206 if (strcmp(define_prefix, "")) {
1207 p_err("'prefix' already defined");
1208 return -1;
1209 }
1210 NEXT_ARG();
1211
1212 if (!REQ_ARGS(1))
1213 return -1;
1214 define_prefix = GET_ARG();
1215 } else if (is_prefix(*argv, "unprivileged")) {
1216 #ifdef USE_LIBCAP
1217 run_as_unprivileged = true;
1218 NEXT_ARG();
1219 #else
1220 p_err("unprivileged run not supported, recompile bpftool with libcap");
1221 return -1;
1222 #endif
1223 } else {
1224 p_err("expected no more arguments, 'kernel', 'dev', 'macros' or 'prefix', got: '%s'?",
1225 *argv);
1226 return -1;
1227 }
1228 }
1229
1230 /* Full feature detection requires specific privileges.
1231 * Let's approximate, and warn if user is not root.
1232 */
1233 if (handle_perms())
1234 return -1;
1235
1236 if (json_output) {
1237 define_prefix = NULL;
1238 jsonw_start_object(json_wtr);
1239 }
1240
1241 section_system_config(target, define_prefix);
1242 if (!section_syscall_config(define_prefix))
1243 /* bpf() syscall unavailable, don't probe other BPF features */
1244 goto exit_close_json;
1245 section_program_types(supported_types, define_prefix, ifindex);
1246 section_map_types(define_prefix, ifindex);
1247 section_helpers(supported_types, define_prefix, ifindex);
1248 section_misc(define_prefix, ifindex);
1249
1250 exit_close_json:
1251 if (json_output)
1252 /* End root object */
1253 jsonw_end_object(json_wtr);
1254
1255 return 0;
1256 }
1257
get_helper_name(unsigned int id)1258 static const char *get_helper_name(unsigned int id)
1259 {
1260 if (id >= ARRAY_SIZE(helper_name))
1261 return NULL;
1262
1263 return helper_name[id];
1264 }
1265
do_list_builtins(int argc,char ** argv)1266 static int do_list_builtins(int argc, char **argv)
1267 {
1268 const char *(*get_name)(unsigned int id);
1269 unsigned int id = 0;
1270
1271 if (argc < 1)
1272 usage();
1273
1274 if (is_prefix(*argv, "prog_types")) {
1275 get_name = (const char *(*)(unsigned int))libbpf_bpf_prog_type_str;
1276 } else if (is_prefix(*argv, "map_types")) {
1277 get_name = (const char *(*)(unsigned int))libbpf_bpf_map_type_str;
1278 } else if (is_prefix(*argv, "attach_types")) {
1279 get_name = (const char *(*)(unsigned int))libbpf_bpf_attach_type_str;
1280 } else if (is_prefix(*argv, "link_types")) {
1281 get_name = (const char *(*)(unsigned int))libbpf_bpf_link_type_str;
1282 } else if (is_prefix(*argv, "helpers")) {
1283 get_name = get_helper_name;
1284 } else {
1285 p_err("expected 'prog_types', 'map_types', 'attach_types', 'link_types' or 'helpers', got: %s", *argv);
1286 return -1;
1287 }
1288
1289 if (json_output)
1290 jsonw_start_array(json_wtr); /* root array */
1291
1292 while (true) {
1293 const char *name;
1294
1295 name = get_name(id++);
1296 if (!name)
1297 break;
1298 if (json_output)
1299 jsonw_string(json_wtr, name);
1300 else
1301 printf("%s\n", name);
1302 }
1303
1304 if (json_output)
1305 jsonw_end_array(json_wtr); /* root array */
1306
1307 return 0;
1308 }
1309
do_help(int argc,char ** argv)1310 static int do_help(int argc, char **argv)
1311 {
1312 if (json_output) {
1313 jsonw_null(json_wtr);
1314 return 0;
1315 }
1316
1317 fprintf(stderr,
1318 "Usage: %1$s %2$s probe [COMPONENT] [full] [unprivileged] [macros [prefix PREFIX]]\n"
1319 " %1$s %2$s list_builtins GROUP\n"
1320 " %1$s %2$s help\n"
1321 "\n"
1322 " COMPONENT := { kernel | dev NAME }\n"
1323 " GROUP := { prog_types | map_types | attach_types | link_types | helpers }\n"
1324 " " HELP_SPEC_OPTIONS " }\n"
1325 "",
1326 bin_name, argv[-2]);
1327
1328 return 0;
1329 }
1330
1331 static const struct cmd cmds[] = {
1332 { "probe", do_probe },
1333 { "list_builtins", do_list_builtins },
1334 { "help", do_help },
1335 { 0 }
1336 };
1337
do_feature(int argc,char ** argv)1338 int do_feature(int argc, char **argv)
1339 {
1340 return cmd_select(cmds, argc, argv, do_help);
1341 }
1342