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 /* Kernel BTF debug information available */ 340 { "CONFIG_DEBUG_INFO_BTF", }, 341 /* Kernel module BTF debug information available */ 342 { "CONFIG_DEBUG_INFO_BTF_MODULES", }, 343 344 /* cgroups */ 345 { "CONFIG_CGROUPS", }, 346 /* BPF programs attached to cgroups */ 347 { "CONFIG_CGROUP_BPF", }, 348 /* bpf_get_cgroup_classid() helper */ 349 { "CONFIG_CGROUP_NET_CLASSID", }, 350 /* bpf_skb_{,ancestor_}cgroup_id() helpers */ 351 { "CONFIG_SOCK_CGROUP_DATA", }, 352 353 /* Tracing: attach BPF to kprobes, tracepoints, etc. */ 354 { "CONFIG_BPF_EVENTS", }, 355 /* Kprobes */ 356 { "CONFIG_KPROBE_EVENTS", }, 357 /* Uprobes */ 358 { "CONFIG_UPROBE_EVENTS", }, 359 /* Tracepoints */ 360 { "CONFIG_TRACING", }, 361 /* Syscall tracepoints */ 362 { "CONFIG_FTRACE_SYSCALLS", }, 363 /* bpf_override_return() helper support for selected arch */ 364 { "CONFIG_FUNCTION_ERROR_INJECTION", }, 365 /* bpf_override_return() helper */ 366 { "CONFIG_BPF_KPROBE_OVERRIDE", }, 367 368 /* Network */ 369 { "CONFIG_NET", }, 370 /* AF_XDP sockets */ 371 { "CONFIG_XDP_SOCKETS", }, 372 /* BPF_PROG_TYPE_LWT_* and related helpers */ 373 { "CONFIG_LWTUNNEL_BPF", }, 374 /* BPF_PROG_TYPE_SCHED_ACT, TC (traffic control) actions */ 375 { "CONFIG_NET_ACT_BPF", }, 376 /* BPF_PROG_TYPE_SCHED_CLS, TC filters */ 377 { "CONFIG_NET_CLS_BPF", }, 378 /* TC clsact qdisc */ 379 { "CONFIG_NET_CLS_ACT", }, 380 /* Ingress filtering with TC */ 381 { "CONFIG_NET_SCH_INGRESS", }, 382 /* bpf_skb_get_xfrm_state() helper */ 383 { "CONFIG_XFRM", }, 384 /* bpf_get_route_realm() helper */ 385 { "CONFIG_IP_ROUTE_CLASSID", }, 386 /* BPF_PROG_TYPE_LWT_SEG6_LOCAL and related helpers */ 387 { "CONFIG_IPV6_SEG6_BPF", }, 388 /* BPF_PROG_TYPE_LIRC_MODE2 and related helpers */ 389 { "CONFIG_BPF_LIRC_MODE2", }, 390 /* BPF stream parser and BPF socket maps */ 391 { "CONFIG_BPF_STREAM_PARSER", }, 392 /* xt_bpf module for passing BPF programs to netfilter */ 393 { "CONFIG_NETFILTER_XT_MATCH_BPF", }, 394 /* bpfilter back-end for iptables */ 395 { "CONFIG_BPFILTER", }, 396 /* bpftilter module with "user mode helper" */ 397 { "CONFIG_BPFILTER_UMH", }, 398 399 /* test_bpf module for BPF tests */ 400 { "CONFIG_TEST_BPF", }, 401 402 /* Misc configs useful in BPF C programs */ 403 /* jiffies <-> sec conversion for bpf_jiffies64() helper */ 404 { "CONFIG_HZ", true, } 405 }; 406 char *values[ARRAY_SIZE(options)] = { }; 407 struct utsname utsn; 408 char path[PATH_MAX]; 409 gzFile file = NULL; 410 char buf[4096]; 411 char *value; 412 size_t i; 413 414 if (!uname(&utsn)) { 415 snprintf(path, sizeof(path), "/boot/config-%s", utsn.release); 416 417 /* gzopen also accepts uncompressed files. */ 418 file = gzopen(path, "r"); 419 } 420 421 if (!file) { 422 /* Some distributions build with CONFIG_IKCONFIG=y and put the 423 * config file at /proc/config.gz. 424 */ 425 file = gzopen("/proc/config.gz", "r"); 426 } 427 if (!file) { 428 p_info("skipping kernel config, can't open file: %s", 429 strerror(errno)); 430 goto end_parse; 431 } 432 /* Sanity checks */ 433 if (!gzgets(file, buf, sizeof(buf)) || 434 !gzgets(file, buf, sizeof(buf))) { 435 p_info("skipping kernel config, can't read from file: %s", 436 strerror(errno)); 437 goto end_parse; 438 } 439 if (strcmp(buf, "# Automatically generated file; DO NOT EDIT.\n")) { 440 p_info("skipping kernel config, can't find correct file"); 441 goto end_parse; 442 } 443 444 while (read_next_kernel_config_option(file, buf, sizeof(buf), &value)) { 445 for (i = 0; i < ARRAY_SIZE(options); i++) { 446 if ((define_prefix && !options[i].macro_dump) || 447 values[i] || strcmp(buf, options[i].name)) 448 continue; 449 450 values[i] = strdup(value); 451 } 452 } 453 454 end_parse: 455 if (file) 456 gzclose(file); 457 458 for (i = 0; i < ARRAY_SIZE(options); i++) { 459 if (define_prefix && !options[i].macro_dump) 460 continue; 461 print_kernel_option(options[i].name, values[i], define_prefix); 462 free(values[i]); 463 } 464 } 465 466 static bool probe_bpf_syscall(const char *define_prefix) 467 { 468 bool res; 469 470 bpf_load_program(BPF_PROG_TYPE_UNSPEC, NULL, 0, NULL, 0, NULL, 0); 471 res = (errno != ENOSYS); 472 473 print_bool_feature("have_bpf_syscall", 474 "bpf() syscall", 475 "BPF_SYSCALL", 476 res, define_prefix); 477 478 return res; 479 } 480 481 static void 482 probe_prog_type(enum bpf_prog_type prog_type, bool *supported_types, 483 const char *define_prefix, __u32 ifindex) 484 { 485 char feat_name[128], plain_desc[128], define_name[128]; 486 const char *plain_comment = "eBPF program_type "; 487 size_t maxlen; 488 bool res; 489 490 if (ifindex) 491 /* Only test offload-able program types */ 492 switch (prog_type) { 493 case BPF_PROG_TYPE_SCHED_CLS: 494 case BPF_PROG_TYPE_XDP: 495 break; 496 default: 497 return; 498 } 499 500 res = bpf_probe_prog_type(prog_type, ifindex); 501 #ifdef USE_LIBCAP 502 /* Probe may succeed even if program load fails, for unprivileged users 503 * check that we did not fail because of insufficient permissions 504 */ 505 if (run_as_unprivileged && errno == EPERM) 506 res = false; 507 #endif 508 509 supported_types[prog_type] |= res; 510 511 if (!prog_type_name[prog_type]) { 512 p_info("program type name not found (type %d)", prog_type); 513 return; 514 } 515 maxlen = sizeof(plain_desc) - strlen(plain_comment) - 1; 516 if (strlen(prog_type_name[prog_type]) > maxlen) { 517 p_info("program type name too long"); 518 return; 519 } 520 521 sprintf(feat_name, "have_%s_prog_type", prog_type_name[prog_type]); 522 sprintf(define_name, "%s_prog_type", prog_type_name[prog_type]); 523 uppercase(define_name, sizeof(define_name)); 524 sprintf(plain_desc, "%s%s", plain_comment, prog_type_name[prog_type]); 525 print_bool_feature(feat_name, plain_desc, define_name, res, 526 define_prefix); 527 } 528 529 static void 530 probe_map_type(enum bpf_map_type map_type, const char *define_prefix, 531 __u32 ifindex) 532 { 533 char feat_name[128], plain_desc[128], define_name[128]; 534 const char *plain_comment = "eBPF map_type "; 535 size_t maxlen; 536 bool res; 537 538 res = bpf_probe_map_type(map_type, ifindex); 539 540 /* Probe result depends on the success of map creation, no additional 541 * check required for unprivileged users 542 */ 543 544 if (!map_type_name[map_type]) { 545 p_info("map type name not found (type %d)", map_type); 546 return; 547 } 548 maxlen = sizeof(plain_desc) - strlen(plain_comment) - 1; 549 if (strlen(map_type_name[map_type]) > maxlen) { 550 p_info("map type name too long"); 551 return; 552 } 553 554 sprintf(feat_name, "have_%s_map_type", map_type_name[map_type]); 555 sprintf(define_name, "%s_map_type", map_type_name[map_type]); 556 uppercase(define_name, sizeof(define_name)); 557 sprintf(plain_desc, "%s%s", plain_comment, map_type_name[map_type]); 558 print_bool_feature(feat_name, plain_desc, define_name, res, 559 define_prefix); 560 } 561 562 static void 563 probe_helper_for_progtype(enum bpf_prog_type prog_type, bool supported_type, 564 const char *define_prefix, unsigned int id, 565 const char *ptype_name, __u32 ifindex) 566 { 567 bool res = false; 568 569 if (supported_type) { 570 res = bpf_probe_helper(id, prog_type, ifindex); 571 #ifdef USE_LIBCAP 572 /* Probe may succeed even if program load fails, for 573 * unprivileged users check that we did not fail because of 574 * insufficient permissions 575 */ 576 if (run_as_unprivileged && errno == EPERM) 577 res = false; 578 #endif 579 } 580 581 if (json_output) { 582 if (res) 583 jsonw_string(json_wtr, helper_name[id]); 584 } else if (define_prefix) { 585 printf("#define %sBPF__PROG_TYPE_%s__HELPER_%s %s\n", 586 define_prefix, ptype_name, helper_name[id], 587 res ? "1" : "0"); 588 } else { 589 if (res) 590 printf("\n\t- %s", helper_name[id]); 591 } 592 } 593 594 static void 595 probe_helpers_for_progtype(enum bpf_prog_type prog_type, bool supported_type, 596 const char *define_prefix, __u32 ifindex) 597 { 598 const char *ptype_name = prog_type_name[prog_type]; 599 char feat_name[128]; 600 unsigned int id; 601 602 if (ifindex) 603 /* Only test helpers for offload-able program types */ 604 switch (prog_type) { 605 case BPF_PROG_TYPE_SCHED_CLS: 606 case BPF_PROG_TYPE_XDP: 607 break; 608 default: 609 return; 610 } 611 612 if (json_output) { 613 sprintf(feat_name, "%s_available_helpers", ptype_name); 614 jsonw_name(json_wtr, feat_name); 615 jsonw_start_array(json_wtr); 616 } else if (!define_prefix) { 617 printf("eBPF helpers supported for program type %s:", 618 ptype_name); 619 } 620 621 for (id = 1; id < ARRAY_SIZE(helper_name); id++) { 622 /* Skip helper functions which emit dmesg messages when not in 623 * the full mode. 624 */ 625 switch (id) { 626 case BPF_FUNC_trace_printk: 627 case BPF_FUNC_probe_write_user: 628 if (!full_mode) 629 continue; 630 /* fallthrough */ 631 default: 632 probe_helper_for_progtype(prog_type, supported_type, 633 define_prefix, id, ptype_name, 634 ifindex); 635 } 636 } 637 638 if (json_output) 639 jsonw_end_array(json_wtr); 640 else if (!define_prefix) 641 printf("\n"); 642 } 643 644 static void 645 probe_large_insn_limit(const char *define_prefix, __u32 ifindex) 646 { 647 bool res; 648 649 res = bpf_probe_large_insn_limit(ifindex); 650 print_bool_feature("have_large_insn_limit", 651 "Large program size limit", 652 "LARGE_INSN_LIMIT", 653 res, define_prefix); 654 } 655 656 static void 657 section_system_config(enum probe_component target, const char *define_prefix) 658 { 659 switch (target) { 660 case COMPONENT_KERNEL: 661 case COMPONENT_UNSPEC: 662 print_start_section("system_config", 663 "Scanning system configuration...", 664 "/*** Misc kernel config items ***/", 665 define_prefix); 666 if (!define_prefix) { 667 if (check_procfs()) { 668 probe_unprivileged_disabled(); 669 probe_jit_enable(); 670 probe_jit_harden(); 671 probe_jit_kallsyms(); 672 probe_jit_limit(); 673 } else { 674 p_info("/* procfs not mounted, skipping related probes */"); 675 } 676 } 677 probe_kernel_image_config(define_prefix); 678 print_end_section(); 679 break; 680 default: 681 break; 682 } 683 } 684 685 static bool section_syscall_config(const char *define_prefix) 686 { 687 bool res; 688 689 print_start_section("syscall_config", 690 "Scanning system call availability...", 691 "/*** System call availability ***/", 692 define_prefix); 693 res = probe_bpf_syscall(define_prefix); 694 print_end_section(); 695 696 return res; 697 } 698 699 static void 700 section_program_types(bool *supported_types, const char *define_prefix, 701 __u32 ifindex) 702 { 703 unsigned int i; 704 705 print_start_section("program_types", 706 "Scanning eBPF program types...", 707 "/*** eBPF program types ***/", 708 define_prefix); 709 710 for (i = BPF_PROG_TYPE_UNSPEC + 1; i < prog_type_name_size; i++) 711 probe_prog_type(i, supported_types, define_prefix, ifindex); 712 713 print_end_section(); 714 } 715 716 static void section_map_types(const char *define_prefix, __u32 ifindex) 717 { 718 unsigned int i; 719 720 print_start_section("map_types", 721 "Scanning eBPF map types...", 722 "/*** eBPF map types ***/", 723 define_prefix); 724 725 for (i = BPF_MAP_TYPE_UNSPEC + 1; i < map_type_name_size; i++) 726 probe_map_type(i, define_prefix, ifindex); 727 728 print_end_section(); 729 } 730 731 static void 732 section_helpers(bool *supported_types, const char *define_prefix, __u32 ifindex) 733 { 734 unsigned int i; 735 736 print_start_section("helpers", 737 "Scanning eBPF helper functions...", 738 "/*** eBPF helper functions ***/", 739 define_prefix); 740 741 if (define_prefix) 742 printf("/*\n" 743 " * Use %sHAVE_PROG_TYPE_HELPER(prog_type_name, helper_name)\n" 744 " * to determine if <helper_name> is available for <prog_type_name>,\n" 745 " * e.g.\n" 746 " * #if %sHAVE_PROG_TYPE_HELPER(xdp, bpf_redirect)\n" 747 " * // do stuff with this helper\n" 748 " * #elif\n" 749 " * // use a workaround\n" 750 " * #endif\n" 751 " */\n" 752 "#define %sHAVE_PROG_TYPE_HELPER(prog_type, helper) \\\n" 753 " %sBPF__PROG_TYPE_ ## prog_type ## __HELPER_ ## helper\n", 754 define_prefix, define_prefix, define_prefix, 755 define_prefix); 756 for (i = BPF_PROG_TYPE_UNSPEC + 1; i < prog_type_name_size; i++) 757 probe_helpers_for_progtype(i, supported_types[i], define_prefix, 758 ifindex); 759 760 print_end_section(); 761 } 762 763 static void section_misc(const char *define_prefix, __u32 ifindex) 764 { 765 print_start_section("misc", 766 "Scanning miscellaneous eBPF features...", 767 "/*** eBPF misc features ***/", 768 define_prefix); 769 probe_large_insn_limit(define_prefix, ifindex); 770 print_end_section(); 771 } 772 773 #ifdef USE_LIBCAP 774 #define capability(c) { c, false, #c } 775 #define capability_msg(a, i) a[i].set ? "" : a[i].name, a[i].set ? "" : ", " 776 #endif 777 778 static int handle_perms(void) 779 { 780 #ifdef USE_LIBCAP 781 struct { 782 cap_value_t cap; 783 bool set; 784 char name[14]; /* strlen("CAP_SYS_ADMIN") */ 785 } bpf_caps[] = { 786 capability(CAP_SYS_ADMIN), 787 #ifdef CAP_BPF 788 capability(CAP_BPF), 789 capability(CAP_NET_ADMIN), 790 capability(CAP_PERFMON), 791 #endif 792 }; 793 cap_value_t cap_list[ARRAY_SIZE(bpf_caps)]; 794 unsigned int i, nb_bpf_caps = 0; 795 bool cap_sys_admin_only = true; 796 cap_flag_value_t val; 797 int res = -1; 798 cap_t caps; 799 800 caps = cap_get_proc(); 801 if (!caps) { 802 p_err("failed to get capabilities for process: %s", 803 strerror(errno)); 804 return -1; 805 } 806 807 #ifdef CAP_BPF 808 if (CAP_IS_SUPPORTED(CAP_BPF)) 809 cap_sys_admin_only = false; 810 #endif 811 812 for (i = 0; i < ARRAY_SIZE(bpf_caps); i++) { 813 const char *cap_name = bpf_caps[i].name; 814 cap_value_t cap = bpf_caps[i].cap; 815 816 if (cap_get_flag(caps, cap, CAP_EFFECTIVE, &val)) { 817 p_err("bug: failed to retrieve %s status: %s", cap_name, 818 strerror(errno)); 819 goto exit_free; 820 } 821 822 if (val == CAP_SET) { 823 bpf_caps[i].set = true; 824 cap_list[nb_bpf_caps++] = cap; 825 } 826 827 if (cap_sys_admin_only) 828 /* System does not know about CAP_BPF, meaning that 829 * CAP_SYS_ADMIN is the only capability required. We 830 * just checked it, break. 831 */ 832 break; 833 } 834 835 if ((run_as_unprivileged && !nb_bpf_caps) || 836 (!run_as_unprivileged && nb_bpf_caps == ARRAY_SIZE(bpf_caps)) || 837 (!run_as_unprivileged && cap_sys_admin_only && nb_bpf_caps)) { 838 /* We are all good, exit now */ 839 res = 0; 840 goto exit_free; 841 } 842 843 if (!run_as_unprivileged) { 844 if (cap_sys_admin_only) 845 p_err("missing %s, required for full feature probing; run as root or use 'unprivileged'", 846 bpf_caps[0].name); 847 else 848 p_err("missing %s%s%s%s%s%s%s%srequired for full feature probing; run as root or use 'unprivileged'", 849 capability_msg(bpf_caps, 0), 850 #ifdef CAP_BPF 851 capability_msg(bpf_caps, 1), 852 capability_msg(bpf_caps, 2), 853 capability_msg(bpf_caps, 3) 854 #else 855 "", "", "", "", "", "" 856 #endif /* CAP_BPF */ 857 ); 858 goto exit_free; 859 } 860 861 /* if (run_as_unprivileged && nb_bpf_caps > 0), drop capabilities. */ 862 if (cap_set_flag(caps, CAP_EFFECTIVE, nb_bpf_caps, cap_list, 863 CAP_CLEAR)) { 864 p_err("bug: failed to clear capabilities: %s", strerror(errno)); 865 goto exit_free; 866 } 867 868 if (cap_set_proc(caps)) { 869 p_err("failed to drop capabilities: %s", strerror(errno)); 870 goto exit_free; 871 } 872 873 res = 0; 874 875 exit_free: 876 if (cap_free(caps) && !res) { 877 p_err("failed to clear storage object for capabilities: %s", 878 strerror(errno)); 879 res = -1; 880 } 881 882 return res; 883 #else 884 /* Detection assumes user has specific privileges. 885 * We do not use libpcap so let's approximate, and restrict usage to 886 * root user only. 887 */ 888 if (geteuid()) { 889 p_err("full feature probing requires root privileges"); 890 return -1; 891 } 892 893 return 0; 894 #endif /* USE_LIBCAP */ 895 } 896 897 static int do_probe(int argc, char **argv) 898 { 899 enum probe_component target = COMPONENT_UNSPEC; 900 const char *define_prefix = NULL; 901 bool supported_types[128] = {}; 902 __u32 ifindex = 0; 903 char *ifname; 904 905 set_max_rlimit(); 906 907 while (argc) { 908 if (is_prefix(*argv, "kernel")) { 909 if (target != COMPONENT_UNSPEC) { 910 p_err("component to probe already specified"); 911 return -1; 912 } 913 target = COMPONENT_KERNEL; 914 NEXT_ARG(); 915 } else if (is_prefix(*argv, "dev")) { 916 NEXT_ARG(); 917 918 if (target != COMPONENT_UNSPEC || ifindex) { 919 p_err("component to probe already specified"); 920 return -1; 921 } 922 if (!REQ_ARGS(1)) 923 return -1; 924 925 target = COMPONENT_DEVICE; 926 ifname = GET_ARG(); 927 ifindex = if_nametoindex(ifname); 928 if (!ifindex) { 929 p_err("unrecognized netdevice '%s': %s", ifname, 930 strerror(errno)); 931 return -1; 932 } 933 } else if (is_prefix(*argv, "full")) { 934 full_mode = true; 935 NEXT_ARG(); 936 } else if (is_prefix(*argv, "macros") && !define_prefix) { 937 define_prefix = ""; 938 NEXT_ARG(); 939 } else if (is_prefix(*argv, "prefix")) { 940 if (!define_prefix) { 941 p_err("'prefix' argument can only be use after 'macros'"); 942 return -1; 943 } 944 if (strcmp(define_prefix, "")) { 945 p_err("'prefix' already defined"); 946 return -1; 947 } 948 NEXT_ARG(); 949 950 if (!REQ_ARGS(1)) 951 return -1; 952 define_prefix = GET_ARG(); 953 } else if (is_prefix(*argv, "unprivileged")) { 954 #ifdef USE_LIBCAP 955 run_as_unprivileged = true; 956 NEXT_ARG(); 957 #else 958 p_err("unprivileged run not supported, recompile bpftool with libcap"); 959 return -1; 960 #endif 961 } else { 962 p_err("expected no more arguments, 'kernel', 'dev', 'macros' or 'prefix', got: '%s'?", 963 *argv); 964 return -1; 965 } 966 } 967 968 /* Full feature detection requires specific privileges. 969 * Let's approximate, and warn if user is not root. 970 */ 971 if (handle_perms()) 972 return -1; 973 974 if (json_output) { 975 define_prefix = NULL; 976 jsonw_start_object(json_wtr); 977 } 978 979 section_system_config(target, define_prefix); 980 if (!section_syscall_config(define_prefix)) 981 /* bpf() syscall unavailable, don't probe other BPF features */ 982 goto exit_close_json; 983 section_program_types(supported_types, define_prefix, ifindex); 984 section_map_types(define_prefix, ifindex); 985 section_helpers(supported_types, define_prefix, ifindex); 986 section_misc(define_prefix, ifindex); 987 988 exit_close_json: 989 if (json_output) 990 /* End root object */ 991 jsonw_end_object(json_wtr); 992 993 return 0; 994 } 995 996 static int do_help(int argc, char **argv) 997 { 998 if (json_output) { 999 jsonw_null(json_wtr); 1000 return 0; 1001 } 1002 1003 fprintf(stderr, 1004 "Usage: %1$s %2$s probe [COMPONENT] [full] [unprivileged] [macros [prefix PREFIX]]\n" 1005 " %1$s %2$s help\n" 1006 "\n" 1007 " COMPONENT := { kernel | dev NAME }\n" 1008 " " HELP_SPEC_OPTIONS " }\n" 1009 "", 1010 bin_name, argv[-2]); 1011 1012 return 0; 1013 } 1014 1015 static const struct cmd cmds[] = { 1016 { "probe", do_probe }, 1017 { "help", do_help }, 1018 { 0 } 1019 }; 1020 1021 int do_feature(int argc, char **argv) 1022 { 1023 return cmd_select(cmds, argc, argv, do_help); 1024 } 1025