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 int read_procfs(const char *path)
171 {
172 char *endptr, *line = NULL;
173 size_t len = 0;
174 FILE *fd;
175 int 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 int res;
198
199 /* No support for C-style ouptut */
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 %d\n", res);
220 }
221 }
222 }
223
probe_jit_enable(void)224 static void probe_jit_enable(void)
225 {
226 int res;
227
228 /* No support for C-style ouptut */
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 %d\n",
249 res);
250 }
251 }
252 }
253
probe_jit_harden(void)254 static void probe_jit_harden(void)
255 {
256 int res;
257
258 /* No support for C-style ouptut */
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 %d\n",
279 res);
280 }
281 }
282 }
283
probe_jit_kallsyms(void)284 static void probe_jit_kallsyms(void)
285 {
286 int res;
287
288 /* No support for C-style ouptut */
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 %d\n", res);
306 }
307 }
308 }
309
probe_jit_limit(void)310 static void probe_jit_limit(void)
311 {
312 int res;
313
314 /* No support for C-style ouptut */
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 %d 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 /* bpfilter back-end for iptables */
430 { "CONFIG_BPFILTER", },
431 /* bpftilter module with "user mode helper" */
432 { "CONFIG_BPFILTER_UMH", },
433
434 /* test_bpf module for BPF tests */
435 { "CONFIG_TEST_BPF", },
436
437 /* Misc configs useful in BPF C programs */
438 /* jiffies <-> sec conversion for bpf_jiffies64() helper */
439 { "CONFIG_HZ", true, }
440 };
441 char *values[ARRAY_SIZE(options)] = { };
442 struct utsname utsn;
443 char path[PATH_MAX];
444 gzFile file = NULL;
445 char buf[4096];
446 char *value;
447 size_t i;
448
449 if (!uname(&utsn)) {
450 snprintf(path, sizeof(path), "/boot/config-%s", utsn.release);
451
452 /* gzopen also accepts uncompressed files. */
453 file = gzopen(path, "r");
454 }
455
456 if (!file) {
457 /* Some distributions build with CONFIG_IKCONFIG=y and put the
458 * config file at /proc/config.gz.
459 */
460 file = gzopen("/proc/config.gz", "r");
461 }
462 if (!file) {
463 p_info("skipping kernel config, can't open file: %s",
464 strerror(errno));
465 goto end_parse;
466 }
467 /* Sanity checks */
468 if (!gzgets(file, buf, sizeof(buf)) ||
469 !gzgets(file, buf, sizeof(buf))) {
470 p_info("skipping kernel config, can't read from file: %s",
471 strerror(errno));
472 goto end_parse;
473 }
474 if (strcmp(buf, "# Automatically generated file; DO NOT EDIT.\n")) {
475 p_info("skipping kernel config, can't find correct file");
476 goto end_parse;
477 }
478
479 while (read_next_kernel_config_option(file, buf, sizeof(buf), &value)) {
480 for (i = 0; i < ARRAY_SIZE(options); i++) {
481 if ((define_prefix && !options[i].macro_dump) ||
482 values[i] || strcmp(buf, options[i].name))
483 continue;
484
485 values[i] = strdup(value);
486 }
487 }
488
489 end_parse:
490 if (file)
491 gzclose(file);
492
493 for (i = 0; i < ARRAY_SIZE(options); i++) {
494 if (define_prefix && !options[i].macro_dump)
495 continue;
496 print_kernel_option(options[i].name, values[i], define_prefix);
497 free(values[i]);
498 }
499 }
500
probe_bpf_syscall(const char * define_prefix)501 static bool probe_bpf_syscall(const char *define_prefix)
502 {
503 bool res;
504
505 bpf_prog_load(BPF_PROG_TYPE_UNSPEC, NULL, NULL, NULL, 0, NULL);
506 res = (errno != ENOSYS);
507
508 print_bool_feature("have_bpf_syscall",
509 "bpf() syscall",
510 "BPF_SYSCALL",
511 res, define_prefix);
512
513 return res;
514 }
515
516 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)517 probe_prog_load_ifindex(enum bpf_prog_type prog_type,
518 const struct bpf_insn *insns, size_t insns_cnt,
519 char *log_buf, size_t log_buf_sz,
520 __u32 ifindex)
521 {
522 LIBBPF_OPTS(bpf_prog_load_opts, opts,
523 .log_buf = log_buf,
524 .log_size = log_buf_sz,
525 .log_level = log_buf ? 1 : 0,
526 .prog_ifindex = ifindex,
527 );
528 int fd;
529
530 errno = 0;
531 fd = bpf_prog_load(prog_type, NULL, "GPL", insns, insns_cnt, &opts);
532 if (fd >= 0)
533 close(fd);
534
535 return fd >= 0 && errno != EINVAL && errno != EOPNOTSUPP;
536 }
537
probe_prog_type_ifindex(enum bpf_prog_type prog_type,__u32 ifindex)538 static bool probe_prog_type_ifindex(enum bpf_prog_type prog_type, __u32 ifindex)
539 {
540 /* nfp returns -EINVAL on exit(0) with TC offload */
541 struct bpf_insn insns[2] = {
542 BPF_MOV64_IMM(BPF_REG_0, 2),
543 BPF_EXIT_INSN()
544 };
545
546 return probe_prog_load_ifindex(prog_type, insns, ARRAY_SIZE(insns),
547 NULL, 0, ifindex);
548 }
549
550 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)551 probe_prog_type(enum bpf_prog_type prog_type, const char *prog_type_str,
552 bool *supported_types, const char *define_prefix, __u32 ifindex)
553 {
554 char feat_name[128], plain_desc[128], define_name[128];
555 const char *plain_comment = "eBPF program_type ";
556 size_t maxlen;
557 bool res;
558
559 if (ifindex) {
560 switch (prog_type) {
561 case BPF_PROG_TYPE_SCHED_CLS:
562 case BPF_PROG_TYPE_XDP:
563 break;
564 default:
565 return;
566 }
567
568 res = probe_prog_type_ifindex(prog_type, ifindex);
569 } else {
570 res = libbpf_probe_bpf_prog_type(prog_type, NULL) > 0;
571 }
572
573 #ifdef USE_LIBCAP
574 /* Probe may succeed even if program load fails, for unprivileged users
575 * check that we did not fail because of insufficient permissions
576 */
577 if (run_as_unprivileged && errno == EPERM)
578 res = false;
579 #endif
580
581 supported_types[prog_type] |= res;
582
583 maxlen = sizeof(plain_desc) - strlen(plain_comment) - 1;
584 if (strlen(prog_type_str) > maxlen) {
585 p_info("program type name too long");
586 return;
587 }
588
589 sprintf(feat_name, "have_%s_prog_type", prog_type_str);
590 sprintf(define_name, "%s_prog_type", prog_type_str);
591 uppercase(define_name, sizeof(define_name));
592 sprintf(plain_desc, "%s%s", plain_comment, prog_type_str);
593 print_bool_feature(feat_name, plain_desc, define_name, res,
594 define_prefix);
595 }
596
probe_map_type_ifindex(enum bpf_map_type map_type,__u32 ifindex)597 static bool probe_map_type_ifindex(enum bpf_map_type map_type, __u32 ifindex)
598 {
599 LIBBPF_OPTS(bpf_map_create_opts, opts);
600 int key_size, value_size, max_entries;
601 int fd;
602
603 opts.map_ifindex = ifindex;
604
605 key_size = sizeof(__u32);
606 value_size = sizeof(__u32);
607 max_entries = 1;
608
609 fd = bpf_map_create(map_type, NULL, key_size, value_size, max_entries,
610 &opts);
611 if (fd >= 0)
612 close(fd);
613
614 return fd >= 0;
615 }
616
617 static void
probe_map_type(enum bpf_map_type map_type,char const * map_type_str,const char * define_prefix,__u32 ifindex)618 probe_map_type(enum bpf_map_type map_type, char const *map_type_str,
619 const char *define_prefix, __u32 ifindex)
620 {
621 char feat_name[128], plain_desc[128], define_name[128];
622 const char *plain_comment = "eBPF map_type ";
623 size_t maxlen;
624 bool res;
625
626 if (ifindex) {
627 switch (map_type) {
628 case BPF_MAP_TYPE_HASH:
629 case BPF_MAP_TYPE_ARRAY:
630 break;
631 default:
632 return;
633 }
634
635 res = probe_map_type_ifindex(map_type, ifindex);
636 } else {
637 res = libbpf_probe_bpf_map_type(map_type, NULL) > 0;
638 }
639
640 /* Probe result depends on the success of map creation, no additional
641 * check required for unprivileged users
642 */
643
644 maxlen = sizeof(plain_desc) - strlen(plain_comment) - 1;
645 if (strlen(map_type_str) > maxlen) {
646 p_info("map type name too long");
647 return;
648 }
649
650 sprintf(feat_name, "have_%s_map_type", map_type_str);
651 sprintf(define_name, "%s_map_type", map_type_str);
652 uppercase(define_name, sizeof(define_name));
653 sprintf(plain_desc, "%s%s", plain_comment, map_type_str);
654 print_bool_feature(feat_name, plain_desc, define_name, res,
655 define_prefix);
656 }
657
658 static bool
probe_helper_ifindex(enum bpf_func_id id,enum bpf_prog_type prog_type,__u32 ifindex)659 probe_helper_ifindex(enum bpf_func_id id, enum bpf_prog_type prog_type,
660 __u32 ifindex)
661 {
662 struct bpf_insn insns[2] = {
663 BPF_EMIT_CALL(id),
664 BPF_EXIT_INSN()
665 };
666 char buf[4096] = {};
667 bool res;
668
669 probe_prog_load_ifindex(prog_type, insns, ARRAY_SIZE(insns), buf,
670 sizeof(buf), ifindex);
671 res = !grep(buf, "invalid func ") && !grep(buf, "unknown func ");
672
673 switch (get_vendor_id(ifindex)) {
674 case 0x19ee: /* Netronome specific */
675 res = res && !grep(buf, "not supported by FW") &&
676 !grep(buf, "unsupported function id");
677 break;
678 default:
679 break;
680 }
681
682 return res;
683 }
684
685 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)686 probe_helper_for_progtype(enum bpf_prog_type prog_type, bool supported_type,
687 const char *define_prefix, unsigned int id,
688 const char *ptype_name, __u32 ifindex)
689 {
690 bool res = false;
691
692 if (supported_type) {
693 if (ifindex)
694 res = probe_helper_ifindex(id, prog_type, ifindex);
695 else
696 res = libbpf_probe_bpf_helper(prog_type, id, NULL) > 0;
697 #ifdef USE_LIBCAP
698 /* Probe may succeed even if program load fails, for
699 * unprivileged users check that we did not fail because of
700 * insufficient permissions
701 */
702 if (run_as_unprivileged && errno == EPERM)
703 res = false;
704 #endif
705 }
706
707 if (json_output) {
708 if (res)
709 jsonw_string(json_wtr, helper_name[id]);
710 } else if (define_prefix) {
711 printf("#define %sBPF__PROG_TYPE_%s__HELPER_%s %s\n",
712 define_prefix, ptype_name, helper_name[id],
713 res ? "1" : "0");
714 } else {
715 if (res)
716 printf("\n\t- %s", helper_name[id]);
717 }
718
719 return res;
720 }
721
722 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)723 probe_helpers_for_progtype(enum bpf_prog_type prog_type,
724 const char *prog_type_str, bool supported_type,
725 const char *define_prefix, __u32 ifindex)
726 {
727 char feat_name[128];
728 unsigned int id;
729 bool probe_res = false;
730
731 if (ifindex)
732 /* Only test helpers for offload-able program types */
733 switch (prog_type) {
734 case BPF_PROG_TYPE_SCHED_CLS:
735 case BPF_PROG_TYPE_XDP:
736 break;
737 default:
738 return;
739 }
740
741 if (json_output) {
742 sprintf(feat_name, "%s_available_helpers", prog_type_str);
743 jsonw_name(json_wtr, feat_name);
744 jsonw_start_array(json_wtr);
745 } else if (!define_prefix) {
746 printf("eBPF helpers supported for program type %s:",
747 prog_type_str);
748 }
749
750 for (id = 1; id < ARRAY_SIZE(helper_name); id++) {
751 /* Skip helper functions which emit dmesg messages when not in
752 * the full mode.
753 */
754 switch (id) {
755 case BPF_FUNC_trace_printk:
756 case BPF_FUNC_trace_vprintk:
757 case BPF_FUNC_probe_write_user:
758 if (!full_mode)
759 continue;
760 /* fallthrough */
761 default:
762 probe_res |= probe_helper_for_progtype(prog_type, supported_type,
763 define_prefix, id, prog_type_str,
764 ifindex);
765 }
766 }
767
768 if (json_output)
769 jsonw_end_array(json_wtr);
770 else if (!define_prefix) {
771 printf("\n");
772 if (!probe_res) {
773 if (!supported_type)
774 printf("\tProgram type not supported\n");
775 else
776 printf("\tCould not determine which helpers are available\n");
777 }
778 }
779
780
781 }
782
783 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)784 probe_misc_feature(struct bpf_insn *insns, size_t len,
785 const char *define_prefix, __u32 ifindex,
786 const char *feat_name, const char *plain_name,
787 const char *define_name)
788 {
789 LIBBPF_OPTS(bpf_prog_load_opts, opts,
790 .prog_ifindex = ifindex,
791 );
792 bool res;
793 int fd;
794
795 errno = 0;
796 fd = bpf_prog_load(BPF_PROG_TYPE_SOCKET_FILTER, NULL, "GPL",
797 insns, len, &opts);
798 res = fd >= 0 || !errno;
799
800 if (fd >= 0)
801 close(fd);
802
803 print_bool_feature(feat_name, plain_name, define_name, res,
804 define_prefix);
805 }
806
807 /*
808 * Probe for availability of kernel commit (5.3):
809 *
810 * c04c0d2b968a ("bpf: increase complexity limit and maximum program size")
811 */
probe_large_insn_limit(const char * define_prefix,__u32 ifindex)812 static void probe_large_insn_limit(const char *define_prefix, __u32 ifindex)
813 {
814 struct bpf_insn insns[BPF_MAXINSNS + 1];
815 int i;
816
817 for (i = 0; i < BPF_MAXINSNS; i++)
818 insns[i] = BPF_MOV64_IMM(BPF_REG_0, 1);
819 insns[BPF_MAXINSNS] = BPF_EXIT_INSN();
820
821 probe_misc_feature(insns, ARRAY_SIZE(insns),
822 define_prefix, ifindex,
823 "have_large_insn_limit",
824 "Large program size limit",
825 "LARGE_INSN_LIMIT");
826 }
827
828 /*
829 * Probe for bounded loop support introduced in commit 2589726d12a1
830 * ("bpf: introduce bounded loops").
831 */
832 static void
probe_bounded_loops(const char * define_prefix,__u32 ifindex)833 probe_bounded_loops(const char *define_prefix, __u32 ifindex)
834 {
835 struct bpf_insn insns[4] = {
836 BPF_MOV64_IMM(BPF_REG_0, 10),
837 BPF_ALU64_IMM(BPF_SUB, BPF_REG_0, 1),
838 BPF_JMP_IMM(BPF_JNE, BPF_REG_0, 0, -2),
839 BPF_EXIT_INSN()
840 };
841
842 probe_misc_feature(insns, ARRAY_SIZE(insns),
843 define_prefix, ifindex,
844 "have_bounded_loops",
845 "Bounded loop support",
846 "BOUNDED_LOOPS");
847 }
848
849 /*
850 * Probe for the v2 instruction set extension introduced in commit 92b31a9af73b
851 * ("bpf: add BPF_J{LT,LE,SLT,SLE} instructions").
852 */
853 static void
probe_v2_isa_extension(const char * define_prefix,__u32 ifindex)854 probe_v2_isa_extension(const char *define_prefix, __u32 ifindex)
855 {
856 struct bpf_insn insns[4] = {
857 BPF_MOV64_IMM(BPF_REG_0, 0),
858 BPF_JMP_IMM(BPF_JLT, BPF_REG_0, 0, 1),
859 BPF_MOV64_IMM(BPF_REG_0, 1),
860 BPF_EXIT_INSN()
861 };
862
863 probe_misc_feature(insns, ARRAY_SIZE(insns),
864 define_prefix, ifindex,
865 "have_v2_isa_extension",
866 "ISA extension v2",
867 "V2_ISA_EXTENSION");
868 }
869
870 /*
871 * Probe for the v3 instruction set extension introduced in commit 092ed0968bb6
872 * ("bpf: verifier support JMP32").
873 */
874 static void
probe_v3_isa_extension(const char * define_prefix,__u32 ifindex)875 probe_v3_isa_extension(const char *define_prefix, __u32 ifindex)
876 {
877 struct bpf_insn insns[4] = {
878 BPF_MOV64_IMM(BPF_REG_0, 0),
879 BPF_JMP32_IMM(BPF_JLT, BPF_REG_0, 0, 1),
880 BPF_MOV64_IMM(BPF_REG_0, 1),
881 BPF_EXIT_INSN()
882 };
883
884 probe_misc_feature(insns, ARRAY_SIZE(insns),
885 define_prefix, ifindex,
886 "have_v3_isa_extension",
887 "ISA extension v3",
888 "V3_ISA_EXTENSION");
889 }
890
891 static void
section_system_config(enum probe_component target,const char * define_prefix)892 section_system_config(enum probe_component target, const char *define_prefix)
893 {
894 switch (target) {
895 case COMPONENT_KERNEL:
896 case COMPONENT_UNSPEC:
897 print_start_section("system_config",
898 "Scanning system configuration...",
899 "/*** Misc kernel config items ***/",
900 define_prefix);
901 if (!define_prefix) {
902 if (check_procfs()) {
903 probe_unprivileged_disabled();
904 probe_jit_enable();
905 probe_jit_harden();
906 probe_jit_kallsyms();
907 probe_jit_limit();
908 } else {
909 p_info("/* procfs not mounted, skipping related probes */");
910 }
911 }
912 probe_kernel_image_config(define_prefix);
913 print_end_section();
914 break;
915 default:
916 break;
917 }
918 }
919
section_syscall_config(const char * define_prefix)920 static bool section_syscall_config(const char *define_prefix)
921 {
922 bool res;
923
924 print_start_section("syscall_config",
925 "Scanning system call availability...",
926 "/*** System call availability ***/",
927 define_prefix);
928 res = probe_bpf_syscall(define_prefix);
929 print_end_section();
930
931 return res;
932 }
933
934 static void
section_program_types(bool * supported_types,const char * define_prefix,__u32 ifindex)935 section_program_types(bool *supported_types, const char *define_prefix,
936 __u32 ifindex)
937 {
938 unsigned int prog_type = BPF_PROG_TYPE_UNSPEC;
939 const char *prog_type_str;
940
941 print_start_section("program_types",
942 "Scanning eBPF program types...",
943 "/*** eBPF program types ***/",
944 define_prefix);
945
946 while (true) {
947 prog_type++;
948 prog_type_str = libbpf_bpf_prog_type_str(prog_type);
949 /* libbpf will return NULL for variants unknown to it. */
950 if (!prog_type_str)
951 break;
952
953 probe_prog_type(prog_type, prog_type_str, supported_types, define_prefix,
954 ifindex);
955 }
956
957 print_end_section();
958 }
959
section_map_types(const char * define_prefix,__u32 ifindex)960 static void section_map_types(const char *define_prefix, __u32 ifindex)
961 {
962 unsigned int map_type = BPF_MAP_TYPE_UNSPEC;
963 const char *map_type_str;
964
965 print_start_section("map_types",
966 "Scanning eBPF map types...",
967 "/*** eBPF map types ***/",
968 define_prefix);
969
970 while (true) {
971 map_type++;
972 map_type_str = libbpf_bpf_map_type_str(map_type);
973 /* libbpf will return NULL for variants unknown to it. */
974 if (!map_type_str)
975 break;
976
977 probe_map_type(map_type, map_type_str, define_prefix, ifindex);
978 }
979
980 print_end_section();
981 }
982
983 static void
section_helpers(bool * supported_types,const char * define_prefix,__u32 ifindex)984 section_helpers(bool *supported_types, const char *define_prefix, __u32 ifindex)
985 {
986 unsigned int prog_type = BPF_PROG_TYPE_UNSPEC;
987 const char *prog_type_str;
988
989 print_start_section("helpers",
990 "Scanning eBPF helper functions...",
991 "/*** eBPF helper functions ***/",
992 define_prefix);
993
994 if (define_prefix)
995 printf("/*\n"
996 " * Use %sHAVE_PROG_TYPE_HELPER(prog_type_name, helper_name)\n"
997 " * to determine if <helper_name> is available for <prog_type_name>,\n"
998 " * e.g.\n"
999 " * #if %sHAVE_PROG_TYPE_HELPER(xdp, bpf_redirect)\n"
1000 " * // do stuff with this helper\n"
1001 " * #elif\n"
1002 " * // use a workaround\n"
1003 " * #endif\n"
1004 " */\n"
1005 "#define %sHAVE_PROG_TYPE_HELPER(prog_type, helper) \\\n"
1006 " %sBPF__PROG_TYPE_ ## prog_type ## __HELPER_ ## helper\n",
1007 define_prefix, define_prefix, define_prefix,
1008 define_prefix);
1009 while (true) {
1010 prog_type++;
1011 prog_type_str = libbpf_bpf_prog_type_str(prog_type);
1012 /* libbpf will return NULL for variants unknown to it. */
1013 if (!prog_type_str)
1014 break;
1015
1016 probe_helpers_for_progtype(prog_type, prog_type_str,
1017 supported_types[prog_type],
1018 define_prefix,
1019 ifindex);
1020 }
1021
1022 print_end_section();
1023 }
1024
section_misc(const char * define_prefix,__u32 ifindex)1025 static void section_misc(const char *define_prefix, __u32 ifindex)
1026 {
1027 print_start_section("misc",
1028 "Scanning miscellaneous eBPF features...",
1029 "/*** eBPF misc features ***/",
1030 define_prefix);
1031 probe_large_insn_limit(define_prefix, ifindex);
1032 probe_bounded_loops(define_prefix, ifindex);
1033 probe_v2_isa_extension(define_prefix, ifindex);
1034 probe_v3_isa_extension(define_prefix, ifindex);
1035 print_end_section();
1036 }
1037
1038 #ifdef USE_LIBCAP
1039 #define capability(c) { c, false, #c }
1040 #define capability_msg(a, i) a[i].set ? "" : a[i].name, a[i].set ? "" : ", "
1041 #endif
1042
handle_perms(void)1043 static int handle_perms(void)
1044 {
1045 #ifdef USE_LIBCAP
1046 struct {
1047 cap_value_t cap;
1048 bool set;
1049 char name[14]; /* strlen("CAP_SYS_ADMIN") */
1050 } bpf_caps[] = {
1051 capability(CAP_SYS_ADMIN),
1052 #ifdef CAP_BPF
1053 capability(CAP_BPF),
1054 capability(CAP_NET_ADMIN),
1055 capability(CAP_PERFMON),
1056 #endif
1057 };
1058 cap_value_t cap_list[ARRAY_SIZE(bpf_caps)];
1059 unsigned int i, nb_bpf_caps = 0;
1060 bool cap_sys_admin_only = true;
1061 cap_flag_value_t val;
1062 int res = -1;
1063 cap_t caps;
1064
1065 caps = cap_get_proc();
1066 if (!caps) {
1067 p_err("failed to get capabilities for process: %s",
1068 strerror(errno));
1069 return -1;
1070 }
1071
1072 #ifdef CAP_BPF
1073 if (CAP_IS_SUPPORTED(CAP_BPF))
1074 cap_sys_admin_only = false;
1075 #endif
1076
1077 for (i = 0; i < ARRAY_SIZE(bpf_caps); i++) {
1078 const char *cap_name = bpf_caps[i].name;
1079 cap_value_t cap = bpf_caps[i].cap;
1080
1081 if (cap_get_flag(caps, cap, CAP_EFFECTIVE, &val)) {
1082 p_err("bug: failed to retrieve %s status: %s", cap_name,
1083 strerror(errno));
1084 goto exit_free;
1085 }
1086
1087 if (val == CAP_SET) {
1088 bpf_caps[i].set = true;
1089 cap_list[nb_bpf_caps++] = cap;
1090 }
1091
1092 if (cap_sys_admin_only)
1093 /* System does not know about CAP_BPF, meaning that
1094 * CAP_SYS_ADMIN is the only capability required. We
1095 * just checked it, break.
1096 */
1097 break;
1098 }
1099
1100 if ((run_as_unprivileged && !nb_bpf_caps) ||
1101 (!run_as_unprivileged && nb_bpf_caps == ARRAY_SIZE(bpf_caps)) ||
1102 (!run_as_unprivileged && cap_sys_admin_only && nb_bpf_caps)) {
1103 /* We are all good, exit now */
1104 res = 0;
1105 goto exit_free;
1106 }
1107
1108 if (!run_as_unprivileged) {
1109 if (cap_sys_admin_only)
1110 p_err("missing %s, required for full feature probing; run as root or use 'unprivileged'",
1111 bpf_caps[0].name);
1112 else
1113 p_err("missing %s%s%s%s%s%s%s%srequired for full feature probing; run as root or use 'unprivileged'",
1114 capability_msg(bpf_caps, 0),
1115 #ifdef CAP_BPF
1116 capability_msg(bpf_caps, 1),
1117 capability_msg(bpf_caps, 2),
1118 capability_msg(bpf_caps, 3)
1119 #else
1120 "", "", "", "", "", ""
1121 #endif /* CAP_BPF */
1122 );
1123 goto exit_free;
1124 }
1125
1126 /* if (run_as_unprivileged && nb_bpf_caps > 0), drop capabilities. */
1127 if (cap_set_flag(caps, CAP_EFFECTIVE, nb_bpf_caps, cap_list,
1128 CAP_CLEAR)) {
1129 p_err("bug: failed to clear capabilities: %s", strerror(errno));
1130 goto exit_free;
1131 }
1132
1133 if (cap_set_proc(caps)) {
1134 p_err("failed to drop capabilities: %s", strerror(errno));
1135 goto exit_free;
1136 }
1137
1138 res = 0;
1139
1140 exit_free:
1141 if (cap_free(caps) && !res) {
1142 p_err("failed to clear storage object for capabilities: %s",
1143 strerror(errno));
1144 res = -1;
1145 }
1146
1147 return res;
1148 #else
1149 /* Detection assumes user has specific privileges.
1150 * We do not use libcap so let's approximate, and restrict usage to
1151 * root user only.
1152 */
1153 if (geteuid()) {
1154 p_err("full feature probing requires root privileges");
1155 return -1;
1156 }
1157
1158 return 0;
1159 #endif /* USE_LIBCAP */
1160 }
1161
do_probe(int argc,char ** argv)1162 static int do_probe(int argc, char **argv)
1163 {
1164 enum probe_component target = COMPONENT_UNSPEC;
1165 const char *define_prefix = NULL;
1166 bool supported_types[128] = {};
1167 __u32 ifindex = 0;
1168 char *ifname;
1169
1170 set_max_rlimit();
1171
1172 while (argc) {
1173 if (is_prefix(*argv, "kernel")) {
1174 if (target != COMPONENT_UNSPEC) {
1175 p_err("component to probe already specified");
1176 return -1;
1177 }
1178 target = COMPONENT_KERNEL;
1179 NEXT_ARG();
1180 } else if (is_prefix(*argv, "dev")) {
1181 NEXT_ARG();
1182
1183 if (target != COMPONENT_UNSPEC || ifindex) {
1184 p_err("component to probe already specified");
1185 return -1;
1186 }
1187 if (!REQ_ARGS(1))
1188 return -1;
1189
1190 target = COMPONENT_DEVICE;
1191 ifname = GET_ARG();
1192 ifindex = if_nametoindex(ifname);
1193 if (!ifindex) {
1194 p_err("unrecognized netdevice '%s': %s", ifname,
1195 strerror(errno));
1196 return -1;
1197 }
1198 } else if (is_prefix(*argv, "full")) {
1199 full_mode = true;
1200 NEXT_ARG();
1201 } else if (is_prefix(*argv, "macros") && !define_prefix) {
1202 define_prefix = "";
1203 NEXT_ARG();
1204 } else if (is_prefix(*argv, "prefix")) {
1205 if (!define_prefix) {
1206 p_err("'prefix' argument can only be use after 'macros'");
1207 return -1;
1208 }
1209 if (strcmp(define_prefix, "")) {
1210 p_err("'prefix' already defined");
1211 return -1;
1212 }
1213 NEXT_ARG();
1214
1215 if (!REQ_ARGS(1))
1216 return -1;
1217 define_prefix = GET_ARG();
1218 } else if (is_prefix(*argv, "unprivileged")) {
1219 #ifdef USE_LIBCAP
1220 run_as_unprivileged = true;
1221 NEXT_ARG();
1222 #else
1223 p_err("unprivileged run not supported, recompile bpftool with libcap");
1224 return -1;
1225 #endif
1226 } else {
1227 p_err("expected no more arguments, 'kernel', 'dev', 'macros' or 'prefix', got: '%s'?",
1228 *argv);
1229 return -1;
1230 }
1231 }
1232
1233 /* Full feature detection requires specific privileges.
1234 * Let's approximate, and warn if user is not root.
1235 */
1236 if (handle_perms())
1237 return -1;
1238
1239 if (json_output) {
1240 define_prefix = NULL;
1241 jsonw_start_object(json_wtr);
1242 }
1243
1244 section_system_config(target, define_prefix);
1245 if (!section_syscall_config(define_prefix))
1246 /* bpf() syscall unavailable, don't probe other BPF features */
1247 goto exit_close_json;
1248 section_program_types(supported_types, define_prefix, ifindex);
1249 section_map_types(define_prefix, ifindex);
1250 section_helpers(supported_types, define_prefix, ifindex);
1251 section_misc(define_prefix, ifindex);
1252
1253 exit_close_json:
1254 if (json_output)
1255 /* End root object */
1256 jsonw_end_object(json_wtr);
1257
1258 return 0;
1259 }
1260
get_helper_name(unsigned int id)1261 static const char *get_helper_name(unsigned int id)
1262 {
1263 if (id >= ARRAY_SIZE(helper_name))
1264 return NULL;
1265
1266 return helper_name[id];
1267 }
1268
do_list_builtins(int argc,char ** argv)1269 static int do_list_builtins(int argc, char **argv)
1270 {
1271 const char *(*get_name)(unsigned int id);
1272 unsigned int id = 0;
1273
1274 if (argc < 1)
1275 usage();
1276
1277 if (is_prefix(*argv, "prog_types")) {
1278 get_name = (const char *(*)(unsigned int))libbpf_bpf_prog_type_str;
1279 } else if (is_prefix(*argv, "map_types")) {
1280 get_name = (const char *(*)(unsigned int))libbpf_bpf_map_type_str;
1281 } else if (is_prefix(*argv, "attach_types")) {
1282 get_name = (const char *(*)(unsigned int))libbpf_bpf_attach_type_str;
1283 } else if (is_prefix(*argv, "link_types")) {
1284 get_name = (const char *(*)(unsigned int))libbpf_bpf_link_type_str;
1285 } else if (is_prefix(*argv, "helpers")) {
1286 get_name = get_helper_name;
1287 } else {
1288 p_err("expected 'prog_types', 'map_types', 'attach_types', 'link_types' or 'helpers', got: %s", *argv);
1289 return -1;
1290 }
1291
1292 if (json_output)
1293 jsonw_start_array(json_wtr); /* root array */
1294
1295 while (true) {
1296 const char *name;
1297
1298 name = get_name(id++);
1299 if (!name)
1300 break;
1301 if (json_output)
1302 jsonw_string(json_wtr, name);
1303 else
1304 printf("%s\n", name);
1305 }
1306
1307 if (json_output)
1308 jsonw_end_array(json_wtr); /* root array */
1309
1310 return 0;
1311 }
1312
do_help(int argc,char ** argv)1313 static int do_help(int argc, char **argv)
1314 {
1315 if (json_output) {
1316 jsonw_null(json_wtr);
1317 return 0;
1318 }
1319
1320 fprintf(stderr,
1321 "Usage: %1$s %2$s probe [COMPONENT] [full] [unprivileged] [macros [prefix PREFIX]]\n"
1322 " %1$s %2$s list_builtins GROUP\n"
1323 " %1$s %2$s help\n"
1324 "\n"
1325 " COMPONENT := { kernel | dev NAME }\n"
1326 " GROUP := { prog_types | map_types | attach_types | link_types | helpers }\n"
1327 " " HELP_SPEC_OPTIONS " }\n"
1328 "",
1329 bin_name, argv[-2]);
1330
1331 return 0;
1332 }
1333
1334 static const struct cmd cmds[] = {
1335 { "probe", do_probe },
1336 { "list_builtins", do_list_builtins },
1337 { "help", do_help },
1338 { 0 }
1339 };
1340
do_feature(int argc,char ** argv)1341 int do_feature(int argc, char **argv)
1342 {
1343 return cmd_select(cmds, argc, argv, do_help);
1344 }
1345
