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_trace_vprintk: 628 case BPF_FUNC_probe_write_user: 629 if (!full_mode) 630 continue; 631 /* fallthrough */ 632 default: 633 probe_helper_for_progtype(prog_type, supported_type, 634 define_prefix, id, ptype_name, 635 ifindex); 636 } 637 } 638 639 if (json_output) 640 jsonw_end_array(json_wtr); 641 else if (!define_prefix) 642 printf("\n"); 643 } 644 645 static void 646 probe_large_insn_limit(const char *define_prefix, __u32 ifindex) 647 { 648 bool res; 649 650 res = bpf_probe_large_insn_limit(ifindex); 651 print_bool_feature("have_large_insn_limit", 652 "Large program size limit", 653 "LARGE_INSN_LIMIT", 654 res, define_prefix); 655 } 656 657 static void 658 section_system_config(enum probe_component target, const char *define_prefix) 659 { 660 switch (target) { 661 case COMPONENT_KERNEL: 662 case COMPONENT_UNSPEC: 663 print_start_section("system_config", 664 "Scanning system configuration...", 665 "/*** Misc kernel config items ***/", 666 define_prefix); 667 if (!define_prefix) { 668 if (check_procfs()) { 669 probe_unprivileged_disabled(); 670 probe_jit_enable(); 671 probe_jit_harden(); 672 probe_jit_kallsyms(); 673 probe_jit_limit(); 674 } else { 675 p_info("/* procfs not mounted, skipping related probes */"); 676 } 677 } 678 probe_kernel_image_config(define_prefix); 679 print_end_section(); 680 break; 681 default: 682 break; 683 } 684 } 685 686 static bool section_syscall_config(const char *define_prefix) 687 { 688 bool res; 689 690 print_start_section("syscall_config", 691 "Scanning system call availability...", 692 "/*** System call availability ***/", 693 define_prefix); 694 res = probe_bpf_syscall(define_prefix); 695 print_end_section(); 696 697 return res; 698 } 699 700 static void 701 section_program_types(bool *supported_types, const char *define_prefix, 702 __u32 ifindex) 703 { 704 unsigned int i; 705 706 print_start_section("program_types", 707 "Scanning eBPF program types...", 708 "/*** eBPF program types ***/", 709 define_prefix); 710 711 for (i = BPF_PROG_TYPE_UNSPEC + 1; i < prog_type_name_size; i++) 712 probe_prog_type(i, supported_types, define_prefix, ifindex); 713 714 print_end_section(); 715 } 716 717 static void section_map_types(const char *define_prefix, __u32 ifindex) 718 { 719 unsigned int i; 720 721 print_start_section("map_types", 722 "Scanning eBPF map types...", 723 "/*** eBPF map types ***/", 724 define_prefix); 725 726 for (i = BPF_MAP_TYPE_UNSPEC + 1; i < map_type_name_size; i++) 727 probe_map_type(i, define_prefix, ifindex); 728 729 print_end_section(); 730 } 731 732 static void 733 section_helpers(bool *supported_types, const char *define_prefix, __u32 ifindex) 734 { 735 unsigned int i; 736 737 print_start_section("helpers", 738 "Scanning eBPF helper functions...", 739 "/*** eBPF helper functions ***/", 740 define_prefix); 741 742 if (define_prefix) 743 printf("/*\n" 744 " * Use %sHAVE_PROG_TYPE_HELPER(prog_type_name, helper_name)\n" 745 " * to determine if <helper_name> is available for <prog_type_name>,\n" 746 " * e.g.\n" 747 " * #if %sHAVE_PROG_TYPE_HELPER(xdp, bpf_redirect)\n" 748 " * // do stuff with this helper\n" 749 " * #elif\n" 750 " * // use a workaround\n" 751 " * #endif\n" 752 " */\n" 753 "#define %sHAVE_PROG_TYPE_HELPER(prog_type, helper) \\\n" 754 " %sBPF__PROG_TYPE_ ## prog_type ## __HELPER_ ## helper\n", 755 define_prefix, define_prefix, define_prefix, 756 define_prefix); 757 for (i = BPF_PROG_TYPE_UNSPEC + 1; i < prog_type_name_size; i++) 758 probe_helpers_for_progtype(i, supported_types[i], define_prefix, 759 ifindex); 760 761 print_end_section(); 762 } 763 764 static void section_misc(const char *define_prefix, __u32 ifindex) 765 { 766 print_start_section("misc", 767 "Scanning miscellaneous eBPF features...", 768 "/*** eBPF misc features ***/", 769 define_prefix); 770 probe_large_insn_limit(define_prefix, ifindex); 771 print_end_section(); 772 } 773 774 #ifdef USE_LIBCAP 775 #define capability(c) { c, false, #c } 776 #define capability_msg(a, i) a[i].set ? "" : a[i].name, a[i].set ? "" : ", " 777 #endif 778 779 static int handle_perms(void) 780 { 781 #ifdef USE_LIBCAP 782 struct { 783 cap_value_t cap; 784 bool set; 785 char name[14]; /* strlen("CAP_SYS_ADMIN") */ 786 } bpf_caps[] = { 787 capability(CAP_SYS_ADMIN), 788 #ifdef CAP_BPF 789 capability(CAP_BPF), 790 capability(CAP_NET_ADMIN), 791 capability(CAP_PERFMON), 792 #endif 793 }; 794 cap_value_t cap_list[ARRAY_SIZE(bpf_caps)]; 795 unsigned int i, nb_bpf_caps = 0; 796 bool cap_sys_admin_only = true; 797 cap_flag_value_t val; 798 int res = -1; 799 cap_t caps; 800 801 caps = cap_get_proc(); 802 if (!caps) { 803 p_err("failed to get capabilities for process: %s", 804 strerror(errno)); 805 return -1; 806 } 807 808 #ifdef CAP_BPF 809 if (CAP_IS_SUPPORTED(CAP_BPF)) 810 cap_sys_admin_only = false; 811 #endif 812 813 for (i = 0; i < ARRAY_SIZE(bpf_caps); i++) { 814 const char *cap_name = bpf_caps[i].name; 815 cap_value_t cap = bpf_caps[i].cap; 816 817 if (cap_get_flag(caps, cap, CAP_EFFECTIVE, &val)) { 818 p_err("bug: failed to retrieve %s status: %s", cap_name, 819 strerror(errno)); 820 goto exit_free; 821 } 822 823 if (val == CAP_SET) { 824 bpf_caps[i].set = true; 825 cap_list[nb_bpf_caps++] = cap; 826 } 827 828 if (cap_sys_admin_only) 829 /* System does not know about CAP_BPF, meaning that 830 * CAP_SYS_ADMIN is the only capability required. We 831 * just checked it, break. 832 */ 833 break; 834 } 835 836 if ((run_as_unprivileged && !nb_bpf_caps) || 837 (!run_as_unprivileged && nb_bpf_caps == ARRAY_SIZE(bpf_caps)) || 838 (!run_as_unprivileged && cap_sys_admin_only && nb_bpf_caps)) { 839 /* We are all good, exit now */ 840 res = 0; 841 goto exit_free; 842 } 843 844 if (!run_as_unprivileged) { 845 if (cap_sys_admin_only) 846 p_err("missing %s, required for full feature probing; run as root or use 'unprivileged'", 847 bpf_caps[0].name); 848 else 849 p_err("missing %s%s%s%s%s%s%s%srequired for full feature probing; run as root or use 'unprivileged'", 850 capability_msg(bpf_caps, 0), 851 #ifdef CAP_BPF 852 capability_msg(bpf_caps, 1), 853 capability_msg(bpf_caps, 2), 854 capability_msg(bpf_caps, 3) 855 #else 856 "", "", "", "", "", "" 857 #endif /* CAP_BPF */ 858 ); 859 goto exit_free; 860 } 861 862 /* if (run_as_unprivileged && nb_bpf_caps > 0), drop capabilities. */ 863 if (cap_set_flag(caps, CAP_EFFECTIVE, nb_bpf_caps, cap_list, 864 CAP_CLEAR)) { 865 p_err("bug: failed to clear capabilities: %s", strerror(errno)); 866 goto exit_free; 867 } 868 869 if (cap_set_proc(caps)) { 870 p_err("failed to drop capabilities: %s", strerror(errno)); 871 goto exit_free; 872 } 873 874 res = 0; 875 876 exit_free: 877 if (cap_free(caps) && !res) { 878 p_err("failed to clear storage object for capabilities: %s", 879 strerror(errno)); 880 res = -1; 881 } 882 883 return res; 884 #else 885 /* Detection assumes user has specific privileges. 886 * We do not use libpcap so let's approximate, and restrict usage to 887 * root user only. 888 */ 889 if (geteuid()) { 890 p_err("full feature probing requires root privileges"); 891 return -1; 892 } 893 894 return 0; 895 #endif /* USE_LIBCAP */ 896 } 897 898 static int do_probe(int argc, char **argv) 899 { 900 enum probe_component target = COMPONENT_UNSPEC; 901 const char *define_prefix = NULL; 902 bool supported_types[128] = {}; 903 __u32 ifindex = 0; 904 char *ifname; 905 906 set_max_rlimit(); 907 908 while (argc) { 909 if (is_prefix(*argv, "kernel")) { 910 if (target != COMPONENT_UNSPEC) { 911 p_err("component to probe already specified"); 912 return -1; 913 } 914 target = COMPONENT_KERNEL; 915 NEXT_ARG(); 916 } else if (is_prefix(*argv, "dev")) { 917 NEXT_ARG(); 918 919 if (target != COMPONENT_UNSPEC || ifindex) { 920 p_err("component to probe already specified"); 921 return -1; 922 } 923 if (!REQ_ARGS(1)) 924 return -1; 925 926 target = COMPONENT_DEVICE; 927 ifname = GET_ARG(); 928 ifindex = if_nametoindex(ifname); 929 if (!ifindex) { 930 p_err("unrecognized netdevice '%s': %s", ifname, 931 strerror(errno)); 932 return -1; 933 } 934 } else if (is_prefix(*argv, "full")) { 935 full_mode = true; 936 NEXT_ARG(); 937 } else if (is_prefix(*argv, "macros") && !define_prefix) { 938 define_prefix = ""; 939 NEXT_ARG(); 940 } else if (is_prefix(*argv, "prefix")) { 941 if (!define_prefix) { 942 p_err("'prefix' argument can only be use after 'macros'"); 943 return -1; 944 } 945 if (strcmp(define_prefix, "")) { 946 p_err("'prefix' already defined"); 947 return -1; 948 } 949 NEXT_ARG(); 950 951 if (!REQ_ARGS(1)) 952 return -1; 953 define_prefix = GET_ARG(); 954 } else if (is_prefix(*argv, "unprivileged")) { 955 #ifdef USE_LIBCAP 956 run_as_unprivileged = true; 957 NEXT_ARG(); 958 #else 959 p_err("unprivileged run not supported, recompile bpftool with libcap"); 960 return -1; 961 #endif 962 } else { 963 p_err("expected no more arguments, 'kernel', 'dev', 'macros' or 'prefix', got: '%s'?", 964 *argv); 965 return -1; 966 } 967 } 968 969 /* Full feature detection requires specific privileges. 970 * Let's approximate, and warn if user is not root. 971 */ 972 if (handle_perms()) 973 return -1; 974 975 if (json_output) { 976 define_prefix = NULL; 977 jsonw_start_object(json_wtr); 978 } 979 980 section_system_config(target, define_prefix); 981 if (!section_syscall_config(define_prefix)) 982 /* bpf() syscall unavailable, don't probe other BPF features */ 983 goto exit_close_json; 984 section_program_types(supported_types, define_prefix, ifindex); 985 section_map_types(define_prefix, ifindex); 986 section_helpers(supported_types, define_prefix, ifindex); 987 section_misc(define_prefix, ifindex); 988 989 exit_close_json: 990 if (json_output) 991 /* End root object */ 992 jsonw_end_object(json_wtr); 993 994 return 0; 995 } 996 997 static int do_help(int argc, char **argv) 998 { 999 if (json_output) { 1000 jsonw_null(json_wtr); 1001 return 0; 1002 } 1003 1004 fprintf(stderr, 1005 "Usage: %1$s %2$s probe [COMPONENT] [full] [unprivileged] [macros [prefix PREFIX]]\n" 1006 " %1$s %2$s help\n" 1007 "\n" 1008 " COMPONENT := { kernel | dev NAME }\n" 1009 " " HELP_SPEC_OPTIONS " }\n" 1010 "", 1011 bin_name, argv[-2]); 1012 1013 return 0; 1014 } 1015 1016 static const struct cmd cmds[] = { 1017 { "probe", do_probe }, 1018 { "help", do_help }, 1019 { 0 } 1020 }; 1021 1022 int do_feature(int argc, char **argv) 1023 { 1024 return cmd_select(cmds, argc, argv, do_help); 1025 } 1026