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 <string.h> 7 #include <unistd.h> 8 #include <net/if.h> 9 #ifdef USE_LIBCAP 10 #include <sys/capability.h> 11 #endif 12 #include <sys/utsname.h> 13 #include <sys/vfs.h> 14 15 #include <linux/filter.h> 16 #include <linux/limits.h> 17 18 #include <bpf/bpf.h> 19 #include <bpf/libbpf.h> 20 #include <zlib.h> 21 22 #include "main.h" 23 24 #ifndef PROC_SUPER_MAGIC 25 # define PROC_SUPER_MAGIC 0x9fa0 26 #endif 27 28 enum probe_component { 29 COMPONENT_UNSPEC, 30 COMPONENT_KERNEL, 31 COMPONENT_DEVICE, 32 }; 33 34 #define BPF_HELPER_MAKE_ENTRY(name) [BPF_FUNC_ ## name] = "bpf_" # name 35 static const char * const helper_name[] = { 36 __BPF_FUNC_MAPPER(BPF_HELPER_MAKE_ENTRY) 37 }; 38 39 #undef BPF_HELPER_MAKE_ENTRY 40 41 static bool full_mode; 42 #ifdef USE_LIBCAP 43 static bool run_as_unprivileged; 44 #endif 45 46 /* Miscellaneous utility functions */ 47 48 static bool check_procfs(void) 49 { 50 struct statfs st_fs; 51 52 if (statfs("/proc", &st_fs) < 0) 53 return false; 54 if ((unsigned long)st_fs.f_type != PROC_SUPER_MAGIC) 55 return false; 56 57 return true; 58 } 59 60 static void uppercase(char *str, size_t len) 61 { 62 size_t i; 63 64 for (i = 0; i < len && str[i] != '\0'; i++) 65 str[i] = toupper(str[i]); 66 } 67 68 /* Printing utility functions */ 69 70 static void 71 print_bool_feature(const char *feat_name, const char *plain_name, 72 const char *define_name, bool res, const char *define_prefix) 73 { 74 if (json_output) 75 jsonw_bool_field(json_wtr, feat_name, res); 76 else if (define_prefix) 77 printf("#define %s%sHAVE_%s\n", define_prefix, 78 res ? "" : "NO_", define_name); 79 else 80 printf("%s is %savailable\n", plain_name, res ? "" : "NOT "); 81 } 82 83 static void print_kernel_option(const char *name, const char *value, 84 const char *define_prefix) 85 { 86 char *endptr; 87 int res; 88 89 if (json_output) { 90 if (!value) { 91 jsonw_null_field(json_wtr, name); 92 return; 93 } 94 errno = 0; 95 res = strtol(value, &endptr, 0); 96 if (!errno && *endptr == '\n') 97 jsonw_int_field(json_wtr, name, res); 98 else 99 jsonw_string_field(json_wtr, name, value); 100 } else if (define_prefix) { 101 if (value) 102 printf("#define %s%s %s\n", define_prefix, 103 name, value); 104 else 105 printf("/* %s%s is not set */\n", define_prefix, name); 106 } else { 107 if (value) 108 printf("%s is set to %s\n", name, value); 109 else 110 printf("%s is not set\n", name); 111 } 112 } 113 114 static void 115 print_start_section(const char *json_title, const char *plain_title, 116 const char *define_comment, const char *define_prefix) 117 { 118 if (json_output) { 119 jsonw_name(json_wtr, json_title); 120 jsonw_start_object(json_wtr); 121 } else if (define_prefix) { 122 printf("%s\n", define_comment); 123 } else { 124 printf("%s\n", plain_title); 125 } 126 } 127 128 static void print_end_section(void) 129 { 130 if (json_output) 131 jsonw_end_object(json_wtr); 132 else 133 printf("\n"); 134 } 135 136 /* Probing functions */ 137 138 static int read_procfs(const char *path) 139 { 140 char *endptr, *line = NULL; 141 size_t len = 0; 142 FILE *fd; 143 int res; 144 145 fd = fopen(path, "r"); 146 if (!fd) 147 return -1; 148 149 res = getline(&line, &len, fd); 150 fclose(fd); 151 if (res < 0) 152 return -1; 153 154 errno = 0; 155 res = strtol(line, &endptr, 10); 156 if (errno || *line == '\0' || *endptr != '\n') 157 res = -1; 158 free(line); 159 160 return res; 161 } 162 163 static void probe_unprivileged_disabled(void) 164 { 165 int res; 166 167 /* No support for C-style ouptut */ 168 169 res = read_procfs("/proc/sys/kernel/unprivileged_bpf_disabled"); 170 if (json_output) { 171 jsonw_int_field(json_wtr, "unprivileged_bpf_disabled", res); 172 } else { 173 switch (res) { 174 case 0: 175 printf("bpf() syscall for unprivileged users is enabled\n"); 176 break; 177 case 1: 178 printf("bpf() syscall restricted to privileged users\n"); 179 break; 180 case -1: 181 printf("Unable to retrieve required privileges for bpf() syscall\n"); 182 break; 183 default: 184 printf("bpf() syscall restriction has unknown value %d\n", res); 185 } 186 } 187 } 188 189 static void probe_jit_enable(void) 190 { 191 int res; 192 193 /* No support for C-style ouptut */ 194 195 res = read_procfs("/proc/sys/net/core/bpf_jit_enable"); 196 if (json_output) { 197 jsonw_int_field(json_wtr, "bpf_jit_enable", res); 198 } else { 199 switch (res) { 200 case 0: 201 printf("JIT compiler is disabled\n"); 202 break; 203 case 1: 204 printf("JIT compiler is enabled\n"); 205 break; 206 case 2: 207 printf("JIT compiler is enabled with debugging traces in kernel logs\n"); 208 break; 209 case -1: 210 printf("Unable to retrieve JIT-compiler status\n"); 211 break; 212 default: 213 printf("JIT-compiler status has unknown value %d\n", 214 res); 215 } 216 } 217 } 218 219 static void probe_jit_harden(void) 220 { 221 int res; 222 223 /* No support for C-style ouptut */ 224 225 res = read_procfs("/proc/sys/net/core/bpf_jit_harden"); 226 if (json_output) { 227 jsonw_int_field(json_wtr, "bpf_jit_harden", res); 228 } else { 229 switch (res) { 230 case 0: 231 printf("JIT compiler hardening is disabled\n"); 232 break; 233 case 1: 234 printf("JIT compiler hardening is enabled for unprivileged users\n"); 235 break; 236 case 2: 237 printf("JIT compiler hardening is enabled for all users\n"); 238 break; 239 case -1: 240 printf("Unable to retrieve JIT hardening status\n"); 241 break; 242 default: 243 printf("JIT hardening status has unknown value %d\n", 244 res); 245 } 246 } 247 } 248 249 static void probe_jit_kallsyms(void) 250 { 251 int res; 252 253 /* No support for C-style ouptut */ 254 255 res = read_procfs("/proc/sys/net/core/bpf_jit_kallsyms"); 256 if (json_output) { 257 jsonw_int_field(json_wtr, "bpf_jit_kallsyms", res); 258 } else { 259 switch (res) { 260 case 0: 261 printf("JIT compiler kallsyms exports are disabled\n"); 262 break; 263 case 1: 264 printf("JIT compiler kallsyms exports are enabled for root\n"); 265 break; 266 case -1: 267 printf("Unable to retrieve JIT kallsyms export status\n"); 268 break; 269 default: 270 printf("JIT kallsyms exports status has unknown value %d\n", res); 271 } 272 } 273 } 274 275 static void probe_jit_limit(void) 276 { 277 int res; 278 279 /* No support for C-style ouptut */ 280 281 res = read_procfs("/proc/sys/net/core/bpf_jit_limit"); 282 if (json_output) { 283 jsonw_int_field(json_wtr, "bpf_jit_limit", res); 284 } else { 285 switch (res) { 286 case -1: 287 printf("Unable to retrieve global memory limit for JIT compiler for unprivileged users\n"); 288 break; 289 default: 290 printf("Global memory limit for JIT compiler for unprivileged users is %d bytes\n", res); 291 } 292 } 293 } 294 295 static bool read_next_kernel_config_option(gzFile file, char *buf, size_t n, 296 char **value) 297 { 298 char *sep; 299 300 while (gzgets(file, buf, n)) { 301 if (strncmp(buf, "CONFIG_", 7)) 302 continue; 303 304 sep = strchr(buf, '='); 305 if (!sep) 306 continue; 307 308 /* Trim ending '\n' */ 309 buf[strlen(buf) - 1] = '\0'; 310 311 /* Split on '=' and ensure that a value is present. */ 312 *sep = '\0'; 313 if (!sep[1]) 314 continue; 315 316 *value = sep + 1; 317 return true; 318 } 319 320 return false; 321 } 322 323 static void probe_kernel_image_config(const char *define_prefix) 324 { 325 static const struct { 326 const char * const name; 327 bool macro_dump; 328 } options[] = { 329 /* Enable BPF */ 330 { "CONFIG_BPF", }, 331 /* Enable bpf() syscall */ 332 { "CONFIG_BPF_SYSCALL", }, 333 /* Does selected architecture support eBPF JIT compiler */ 334 { "CONFIG_HAVE_EBPF_JIT", }, 335 /* Compile eBPF JIT compiler */ 336 { "CONFIG_BPF_JIT", }, 337 /* Avoid compiling eBPF interpreter (use JIT only) */ 338 { "CONFIG_BPF_JIT_ALWAYS_ON", }, 339 340 /* cgroups */ 341 { "CONFIG_CGROUPS", }, 342 /* BPF programs attached to cgroups */ 343 { "CONFIG_CGROUP_BPF", }, 344 /* bpf_get_cgroup_classid() helper */ 345 { "CONFIG_CGROUP_NET_CLASSID", }, 346 /* bpf_skb_{,ancestor_}cgroup_id() helpers */ 347 { "CONFIG_SOCK_CGROUP_DATA", }, 348 349 /* Tracing: attach BPF to kprobes, tracepoints, etc. */ 350 { "CONFIG_BPF_EVENTS", }, 351 /* Kprobes */ 352 { "CONFIG_KPROBE_EVENTS", }, 353 /* Uprobes */ 354 { "CONFIG_UPROBE_EVENTS", }, 355 /* Tracepoints */ 356 { "CONFIG_TRACING", }, 357 /* Syscall tracepoints */ 358 { "CONFIG_FTRACE_SYSCALLS", }, 359 /* bpf_override_return() helper support for selected arch */ 360 { "CONFIG_FUNCTION_ERROR_INJECTION", }, 361 /* bpf_override_return() helper */ 362 { "CONFIG_BPF_KPROBE_OVERRIDE", }, 363 364 /* Network */ 365 { "CONFIG_NET", }, 366 /* AF_XDP sockets */ 367 { "CONFIG_XDP_SOCKETS", }, 368 /* BPF_PROG_TYPE_LWT_* and related helpers */ 369 { "CONFIG_LWTUNNEL_BPF", }, 370 /* BPF_PROG_TYPE_SCHED_ACT, TC (traffic control) actions */ 371 { "CONFIG_NET_ACT_BPF", }, 372 /* BPF_PROG_TYPE_SCHED_CLS, TC filters */ 373 { "CONFIG_NET_CLS_BPF", }, 374 /* TC clsact qdisc */ 375 { "CONFIG_NET_CLS_ACT", }, 376 /* Ingress filtering with TC */ 377 { "CONFIG_NET_SCH_INGRESS", }, 378 /* bpf_skb_get_xfrm_state() helper */ 379 { "CONFIG_XFRM", }, 380 /* bpf_get_route_realm() helper */ 381 { "CONFIG_IP_ROUTE_CLASSID", }, 382 /* BPF_PROG_TYPE_LWT_SEG6_LOCAL and related helpers */ 383 { "CONFIG_IPV6_SEG6_BPF", }, 384 /* BPF_PROG_TYPE_LIRC_MODE2 and related helpers */ 385 { "CONFIG_BPF_LIRC_MODE2", }, 386 /* BPF stream parser and BPF socket maps */ 387 { "CONFIG_BPF_STREAM_PARSER", }, 388 /* xt_bpf module for passing BPF programs to netfilter */ 389 { "CONFIG_NETFILTER_XT_MATCH_BPF", }, 390 /* bpfilter back-end for iptables */ 391 { "CONFIG_BPFILTER", }, 392 /* bpftilter module with "user mode helper" */ 393 { "CONFIG_BPFILTER_UMH", }, 394 395 /* test_bpf module for BPF tests */ 396 { "CONFIG_TEST_BPF", }, 397 398 /* Misc configs useful in BPF C programs */ 399 /* jiffies <-> sec conversion for bpf_jiffies64() helper */ 400 { "CONFIG_HZ", true, } 401 }; 402 char *values[ARRAY_SIZE(options)] = { }; 403 struct utsname utsn; 404 char path[PATH_MAX]; 405 gzFile file = NULL; 406 char buf[4096]; 407 char *value; 408 size_t i; 409 410 if (!uname(&utsn)) { 411 snprintf(path, sizeof(path), "/boot/config-%s", utsn.release); 412 413 /* gzopen also accepts uncompressed files. */ 414 file = gzopen(path, "r"); 415 } 416 417 if (!file) { 418 /* Some distributions build with CONFIG_IKCONFIG=y and put the 419 * config file at /proc/config.gz. 420 */ 421 file = gzopen("/proc/config.gz", "r"); 422 } 423 if (!file) { 424 p_info("skipping kernel config, can't open file: %s", 425 strerror(errno)); 426 goto end_parse; 427 } 428 /* Sanity checks */ 429 if (!gzgets(file, buf, sizeof(buf)) || 430 !gzgets(file, buf, sizeof(buf))) { 431 p_info("skipping kernel config, can't read from file: %s", 432 strerror(errno)); 433 goto end_parse; 434 } 435 if (strcmp(buf, "# Automatically generated file; DO NOT EDIT.\n")) { 436 p_info("skipping kernel config, can't find correct file"); 437 goto end_parse; 438 } 439 440 while (read_next_kernel_config_option(file, buf, sizeof(buf), &value)) { 441 for (i = 0; i < ARRAY_SIZE(options); i++) { 442 if ((define_prefix && !options[i].macro_dump) || 443 values[i] || strcmp(buf, options[i].name)) 444 continue; 445 446 values[i] = strdup(value); 447 } 448 } 449 450 end_parse: 451 if (file) 452 gzclose(file); 453 454 for (i = 0; i < ARRAY_SIZE(options); i++) { 455 if (define_prefix && !options[i].macro_dump) 456 continue; 457 print_kernel_option(options[i].name, values[i], define_prefix); 458 free(values[i]); 459 } 460 } 461 462 static bool probe_bpf_syscall(const char *define_prefix) 463 { 464 bool res; 465 466 bpf_load_program(BPF_PROG_TYPE_UNSPEC, NULL, 0, NULL, 0, NULL, 0); 467 res = (errno != ENOSYS); 468 469 print_bool_feature("have_bpf_syscall", 470 "bpf() syscall", 471 "BPF_SYSCALL", 472 res, define_prefix); 473 474 return res; 475 } 476 477 static void 478 probe_prog_type(enum bpf_prog_type prog_type, bool *supported_types, 479 const char *define_prefix, __u32 ifindex) 480 { 481 char feat_name[128], plain_desc[128], define_name[128]; 482 const char *plain_comment = "eBPF program_type "; 483 size_t maxlen; 484 bool res; 485 486 if (ifindex) 487 /* Only test offload-able program types */ 488 switch (prog_type) { 489 case BPF_PROG_TYPE_SCHED_CLS: 490 case BPF_PROG_TYPE_XDP: 491 break; 492 default: 493 return; 494 } 495 496 res = bpf_probe_prog_type(prog_type, ifindex); 497 #ifdef USE_LIBCAP 498 /* Probe may succeed even if program load fails, for unprivileged users 499 * check that we did not fail because of insufficient permissions 500 */ 501 if (run_as_unprivileged && errno == EPERM) 502 res = false; 503 #endif 504 505 supported_types[prog_type] |= res; 506 507 maxlen = sizeof(plain_desc) - strlen(plain_comment) - 1; 508 if (strlen(prog_type_name[prog_type]) > maxlen) { 509 p_info("program type name too long"); 510 return; 511 } 512 513 sprintf(feat_name, "have_%s_prog_type", prog_type_name[prog_type]); 514 sprintf(define_name, "%s_prog_type", prog_type_name[prog_type]); 515 uppercase(define_name, sizeof(define_name)); 516 sprintf(plain_desc, "%s%s", plain_comment, prog_type_name[prog_type]); 517 print_bool_feature(feat_name, plain_desc, define_name, res, 518 define_prefix); 519 } 520 521 static void 522 probe_map_type(enum bpf_map_type map_type, const char *define_prefix, 523 __u32 ifindex) 524 { 525 char feat_name[128], plain_desc[128], define_name[128]; 526 const char *plain_comment = "eBPF map_type "; 527 size_t maxlen; 528 bool res; 529 530 res = bpf_probe_map_type(map_type, ifindex); 531 532 /* Probe result depends on the success of map creation, no additional 533 * check required for unprivileged users 534 */ 535 536 maxlen = sizeof(plain_desc) - strlen(plain_comment) - 1; 537 if (strlen(map_type_name[map_type]) > maxlen) { 538 p_info("map type name too long"); 539 return; 540 } 541 542 sprintf(feat_name, "have_%s_map_type", map_type_name[map_type]); 543 sprintf(define_name, "%s_map_type", map_type_name[map_type]); 544 uppercase(define_name, sizeof(define_name)); 545 sprintf(plain_desc, "%s%s", plain_comment, map_type_name[map_type]); 546 print_bool_feature(feat_name, plain_desc, define_name, res, 547 define_prefix); 548 } 549 550 static void 551 probe_helper_for_progtype(enum bpf_prog_type prog_type, bool supported_type, 552 const char *define_prefix, unsigned int id, 553 const char *ptype_name, __u32 ifindex) 554 { 555 bool res = false; 556 557 if (supported_type) { 558 res = bpf_probe_helper(id, prog_type, ifindex); 559 #ifdef USE_LIBCAP 560 /* Probe may succeed even if program load fails, for 561 * unprivileged users check that we did not fail because of 562 * insufficient permissions 563 */ 564 if (run_as_unprivileged && errno == EPERM) 565 res = false; 566 #endif 567 } 568 569 if (json_output) { 570 if (res) 571 jsonw_string(json_wtr, helper_name[id]); 572 } else if (define_prefix) { 573 printf("#define %sBPF__PROG_TYPE_%s__HELPER_%s %s\n", 574 define_prefix, ptype_name, helper_name[id], 575 res ? "1" : "0"); 576 } else { 577 if (res) 578 printf("\n\t- %s", helper_name[id]); 579 } 580 } 581 582 static void 583 probe_helpers_for_progtype(enum bpf_prog_type prog_type, bool supported_type, 584 const char *define_prefix, __u32 ifindex) 585 { 586 const char *ptype_name = prog_type_name[prog_type]; 587 char feat_name[128]; 588 unsigned int id; 589 590 if (ifindex) 591 /* Only test helpers for offload-able program types */ 592 switch (prog_type) { 593 case BPF_PROG_TYPE_SCHED_CLS: 594 case BPF_PROG_TYPE_XDP: 595 break; 596 default: 597 return; 598 } 599 600 if (json_output) { 601 sprintf(feat_name, "%s_available_helpers", ptype_name); 602 jsonw_name(json_wtr, feat_name); 603 jsonw_start_array(json_wtr); 604 } else if (!define_prefix) { 605 printf("eBPF helpers supported for program type %s:", 606 ptype_name); 607 } 608 609 for (id = 1; id < ARRAY_SIZE(helper_name); id++) { 610 /* Skip helper functions which emit dmesg messages when not in 611 * the full mode. 612 */ 613 switch (id) { 614 case BPF_FUNC_trace_printk: 615 case BPF_FUNC_probe_write_user: 616 if (!full_mode) 617 continue; 618 /* fallthrough */ 619 default: 620 probe_helper_for_progtype(prog_type, supported_type, 621 define_prefix, id, ptype_name, 622 ifindex); 623 } 624 } 625 626 if (json_output) 627 jsonw_end_array(json_wtr); 628 else if (!define_prefix) 629 printf("\n"); 630 } 631 632 static void 633 probe_large_insn_limit(const char *define_prefix, __u32 ifindex) 634 { 635 bool res; 636 637 res = bpf_probe_large_insn_limit(ifindex); 638 print_bool_feature("have_large_insn_limit", 639 "Large program size limit", 640 "LARGE_INSN_LIMIT", 641 res, define_prefix); 642 } 643 644 static void 645 section_system_config(enum probe_component target, const char *define_prefix) 646 { 647 switch (target) { 648 case COMPONENT_KERNEL: 649 case COMPONENT_UNSPEC: 650 print_start_section("system_config", 651 "Scanning system configuration...", 652 "/*** Misc kernel config items ***/", 653 define_prefix); 654 if (!define_prefix) { 655 if (check_procfs()) { 656 probe_unprivileged_disabled(); 657 probe_jit_enable(); 658 probe_jit_harden(); 659 probe_jit_kallsyms(); 660 probe_jit_limit(); 661 } else { 662 p_info("/* procfs not mounted, skipping related probes */"); 663 } 664 } 665 probe_kernel_image_config(define_prefix); 666 print_end_section(); 667 break; 668 default: 669 break; 670 } 671 } 672 673 static bool section_syscall_config(const char *define_prefix) 674 { 675 bool res; 676 677 print_start_section("syscall_config", 678 "Scanning system call availability...", 679 "/*** System call availability ***/", 680 define_prefix); 681 res = probe_bpf_syscall(define_prefix); 682 print_end_section(); 683 684 return res; 685 } 686 687 static void 688 section_program_types(bool *supported_types, const char *define_prefix, 689 __u32 ifindex) 690 { 691 unsigned int i; 692 693 print_start_section("program_types", 694 "Scanning eBPF program types...", 695 "/*** eBPF program types ***/", 696 define_prefix); 697 698 for (i = BPF_PROG_TYPE_UNSPEC + 1; i < ARRAY_SIZE(prog_type_name); i++) 699 probe_prog_type(i, supported_types, define_prefix, ifindex); 700 701 print_end_section(); 702 } 703 704 static void section_map_types(const char *define_prefix, __u32 ifindex) 705 { 706 unsigned int i; 707 708 print_start_section("map_types", 709 "Scanning eBPF map types...", 710 "/*** eBPF map types ***/", 711 define_prefix); 712 713 for (i = BPF_MAP_TYPE_UNSPEC + 1; i < map_type_name_size; i++) 714 probe_map_type(i, define_prefix, ifindex); 715 716 print_end_section(); 717 } 718 719 static void 720 section_helpers(bool *supported_types, const char *define_prefix, __u32 ifindex) 721 { 722 unsigned int i; 723 724 print_start_section("helpers", 725 "Scanning eBPF helper functions...", 726 "/*** eBPF helper functions ***/", 727 define_prefix); 728 729 if (define_prefix) 730 printf("/*\n" 731 " * Use %sHAVE_PROG_TYPE_HELPER(prog_type_name, helper_name)\n" 732 " * to determine if <helper_name> is available for <prog_type_name>,\n" 733 " * e.g.\n" 734 " * #if %sHAVE_PROG_TYPE_HELPER(xdp, bpf_redirect)\n" 735 " * // do stuff with this helper\n" 736 " * #elif\n" 737 " * // use a workaround\n" 738 " * #endif\n" 739 " */\n" 740 "#define %sHAVE_PROG_TYPE_HELPER(prog_type, helper) \\\n" 741 " %sBPF__PROG_TYPE_ ## prog_type ## __HELPER_ ## helper\n", 742 define_prefix, define_prefix, define_prefix, 743 define_prefix); 744 for (i = BPF_PROG_TYPE_UNSPEC + 1; i < ARRAY_SIZE(prog_type_name); i++) 745 probe_helpers_for_progtype(i, supported_types[i], define_prefix, 746 ifindex); 747 748 print_end_section(); 749 } 750 751 static void section_misc(const char *define_prefix, __u32 ifindex) 752 { 753 print_start_section("misc", 754 "Scanning miscellaneous eBPF features...", 755 "/*** eBPF misc features ***/", 756 define_prefix); 757 probe_large_insn_limit(define_prefix, ifindex); 758 print_end_section(); 759 } 760 761 static int handle_perms(void) 762 { 763 #ifdef USE_LIBCAP 764 cap_value_t cap_list[1] = { CAP_SYS_ADMIN }; 765 bool has_sys_admin_cap = false; 766 cap_flag_value_t val; 767 int res = -1; 768 cap_t caps; 769 770 caps = cap_get_proc(); 771 if (!caps) { 772 p_err("failed to get capabilities for process: %s", 773 strerror(errno)); 774 return -1; 775 } 776 777 if (cap_get_flag(caps, CAP_SYS_ADMIN, CAP_EFFECTIVE, &val)) { 778 p_err("bug: failed to retrieve CAP_SYS_ADMIN status"); 779 goto exit_free; 780 } 781 if (val == CAP_SET) 782 has_sys_admin_cap = true; 783 784 if (!run_as_unprivileged && !has_sys_admin_cap) { 785 p_err("full feature probing requires CAP_SYS_ADMIN, run as root or use 'unprivileged'"); 786 goto exit_free; 787 } 788 789 if ((run_as_unprivileged && !has_sys_admin_cap) || 790 (!run_as_unprivileged && has_sys_admin_cap)) { 791 /* We are all good, exit now */ 792 res = 0; 793 goto exit_free; 794 } 795 796 /* if (run_as_unprivileged && has_sys_admin_cap), drop CAP_SYS_ADMIN */ 797 798 if (cap_set_flag(caps, CAP_EFFECTIVE, ARRAY_SIZE(cap_list), cap_list, 799 CAP_CLEAR)) { 800 p_err("bug: failed to clear CAP_SYS_ADMIN from capabilities"); 801 goto exit_free; 802 } 803 804 if (cap_set_proc(caps)) { 805 p_err("failed to drop CAP_SYS_ADMIN: %s", strerror(errno)); 806 goto exit_free; 807 } 808 809 res = 0; 810 811 exit_free: 812 if (cap_free(caps) && !res) { 813 p_err("failed to clear storage object for capabilities: %s", 814 strerror(errno)); 815 res = -1; 816 } 817 818 return res; 819 #else 820 /* Detection assumes user has sufficient privileges (CAP_SYS_ADMIN). 821 * We do not use libpcap so let's approximate, and restrict usage to 822 * root user only. 823 */ 824 if (geteuid()) { 825 p_err("full feature probing requires root privileges"); 826 return -1; 827 } 828 829 return 0; 830 #endif /* USE_LIBCAP */ 831 } 832 833 static int do_probe(int argc, char **argv) 834 { 835 enum probe_component target = COMPONENT_UNSPEC; 836 const char *define_prefix = NULL; 837 bool supported_types[128] = {}; 838 __u32 ifindex = 0; 839 char *ifname; 840 841 set_max_rlimit(); 842 843 while (argc) { 844 if (is_prefix(*argv, "kernel")) { 845 if (target != COMPONENT_UNSPEC) { 846 p_err("component to probe already specified"); 847 return -1; 848 } 849 target = COMPONENT_KERNEL; 850 NEXT_ARG(); 851 } else if (is_prefix(*argv, "dev")) { 852 NEXT_ARG(); 853 854 if (target != COMPONENT_UNSPEC || ifindex) { 855 p_err("component to probe already specified"); 856 return -1; 857 } 858 if (!REQ_ARGS(1)) 859 return -1; 860 861 target = COMPONENT_DEVICE; 862 ifname = GET_ARG(); 863 ifindex = if_nametoindex(ifname); 864 if (!ifindex) { 865 p_err("unrecognized netdevice '%s': %s", ifname, 866 strerror(errno)); 867 return -1; 868 } 869 } else if (is_prefix(*argv, "full")) { 870 full_mode = true; 871 NEXT_ARG(); 872 } else if (is_prefix(*argv, "macros") && !define_prefix) { 873 define_prefix = ""; 874 NEXT_ARG(); 875 } else if (is_prefix(*argv, "prefix")) { 876 if (!define_prefix) { 877 p_err("'prefix' argument can only be use after 'macros'"); 878 return -1; 879 } 880 if (strcmp(define_prefix, "")) { 881 p_err("'prefix' already defined"); 882 return -1; 883 } 884 NEXT_ARG(); 885 886 if (!REQ_ARGS(1)) 887 return -1; 888 define_prefix = GET_ARG(); 889 } else if (is_prefix(*argv, "unprivileged")) { 890 #ifdef USE_LIBCAP 891 run_as_unprivileged = true; 892 NEXT_ARG(); 893 #else 894 p_err("unprivileged run not supported, recompile bpftool with libcap"); 895 return -1; 896 #endif 897 } else { 898 p_err("expected no more arguments, 'kernel', 'dev', 'macros' or 'prefix', got: '%s'?", 899 *argv); 900 return -1; 901 } 902 } 903 904 /* Full feature detection requires CAP_SYS_ADMIN privilege. 905 * Let's approximate, and warn if user is not root. 906 */ 907 if (handle_perms()) 908 return -1; 909 910 if (json_output) { 911 define_prefix = NULL; 912 jsonw_start_object(json_wtr); 913 } 914 915 section_system_config(target, define_prefix); 916 if (!section_syscall_config(define_prefix)) 917 /* bpf() syscall unavailable, don't probe other BPF features */ 918 goto exit_close_json; 919 section_program_types(supported_types, define_prefix, ifindex); 920 section_map_types(define_prefix, ifindex); 921 section_helpers(supported_types, define_prefix, ifindex); 922 section_misc(define_prefix, ifindex); 923 924 exit_close_json: 925 if (json_output) 926 /* End root object */ 927 jsonw_end_object(json_wtr); 928 929 return 0; 930 } 931 932 static int do_help(int argc, char **argv) 933 { 934 if (json_output) { 935 jsonw_null(json_wtr); 936 return 0; 937 } 938 939 fprintf(stderr, 940 "Usage: %s %s probe [COMPONENT] [full] [unprivileged] [macros [prefix PREFIX]]\n" 941 " %s %s help\n" 942 "\n" 943 " COMPONENT := { kernel | dev NAME }\n" 944 "", 945 bin_name, argv[-2], bin_name, argv[-2]); 946 947 return 0; 948 } 949 950 static const struct cmd cmds[] = { 951 { "probe", do_probe }, 952 { "help", do_help }, 953 { 0 } 954 }; 955 956 int do_feature(int argc, char **argv) 957 { 958 return cmd_select(cmds, argc, argv, do_help); 959 } 960