1 /* 2 * Common eBPF ELF object loading operations. 3 * 4 * Copyright (C) 2013-2015 Alexei Starovoitov <ast@kernel.org> 5 * Copyright (C) 2015 Wang Nan <wangnan0@huawei.com> 6 * Copyright (C) 2015 Huawei Inc. 7 * 8 * This program is free software; you can redistribute it and/or 9 * modify it under the terms of the GNU Lesser General Public 10 * License as published by the Free Software Foundation; 11 * version 2.1 of the License (not later!) 12 * 13 * This program is distributed in the hope that it will be useful, 14 * but WITHOUT ANY WARRANTY; without even the implied warranty of 15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 16 * GNU Lesser General Public License for more details. 17 * 18 * You should have received a copy of the GNU Lesser General Public 19 * License along with this program; if not, see <http://www.gnu.org/licenses> 20 */ 21 22 #include <stdlib.h> 23 #include <stdio.h> 24 #include <stdarg.h> 25 #include <inttypes.h> 26 #include <string.h> 27 #include <unistd.h> 28 #include <fcntl.h> 29 #include <errno.h> 30 #include <asm/unistd.h> 31 #include <linux/kernel.h> 32 #include <linux/bpf.h> 33 #include <linux/list.h> 34 #include <libelf.h> 35 #include <gelf.h> 36 37 #include "libbpf.h" 38 #include "bpf.h" 39 40 #define __printf(a, b) __attribute__((format(printf, a, b))) 41 42 __printf(1, 2) 43 static int __base_pr(const char *format, ...) 44 { 45 va_list args; 46 int err; 47 48 va_start(args, format); 49 err = vfprintf(stderr, format, args); 50 va_end(args); 51 return err; 52 } 53 54 static __printf(1, 2) libbpf_print_fn_t __pr_warning = __base_pr; 55 static __printf(1, 2) libbpf_print_fn_t __pr_info = __base_pr; 56 static __printf(1, 2) libbpf_print_fn_t __pr_debug; 57 58 #define __pr(func, fmt, ...) \ 59 do { \ 60 if ((func)) \ 61 (func)("libbpf: " fmt, ##__VA_ARGS__); \ 62 } while (0) 63 64 #define pr_warning(fmt, ...) __pr(__pr_warning, fmt, ##__VA_ARGS__) 65 #define pr_info(fmt, ...) __pr(__pr_info, fmt, ##__VA_ARGS__) 66 #define pr_debug(fmt, ...) __pr(__pr_debug, fmt, ##__VA_ARGS__) 67 68 void libbpf_set_print(libbpf_print_fn_t warn, 69 libbpf_print_fn_t info, 70 libbpf_print_fn_t debug) 71 { 72 __pr_warning = warn; 73 __pr_info = info; 74 __pr_debug = debug; 75 } 76 77 #define STRERR_BUFSIZE 128 78 79 #define ERRNO_OFFSET(e) ((e) - __LIBBPF_ERRNO__START) 80 #define ERRCODE_OFFSET(c) ERRNO_OFFSET(LIBBPF_ERRNO__##c) 81 #define NR_ERRNO (__LIBBPF_ERRNO__END - __LIBBPF_ERRNO__START) 82 83 static const char *libbpf_strerror_table[NR_ERRNO] = { 84 [ERRCODE_OFFSET(LIBELF)] = "Something wrong in libelf", 85 [ERRCODE_OFFSET(FORMAT)] = "BPF object format invalid", 86 [ERRCODE_OFFSET(KVERSION)] = "'version' section incorrect or lost", 87 [ERRCODE_OFFSET(ENDIAN)] = "Endian mismatch", 88 [ERRCODE_OFFSET(INTERNAL)] = "Internal error in libbpf", 89 [ERRCODE_OFFSET(RELOC)] = "Relocation failed", 90 [ERRCODE_OFFSET(VERIFY)] = "Kernel verifier blocks program loading", 91 [ERRCODE_OFFSET(PROG2BIG)] = "Program too big", 92 [ERRCODE_OFFSET(KVER)] = "Incorrect kernel version", 93 [ERRCODE_OFFSET(PROGTYPE)] = "Kernel doesn't support this program type", 94 }; 95 96 int libbpf_strerror(int err, char *buf, size_t size) 97 { 98 if (!buf || !size) 99 return -1; 100 101 err = err > 0 ? err : -err; 102 103 if (err < __LIBBPF_ERRNO__START) { 104 int ret; 105 106 ret = strerror_r(err, buf, size); 107 buf[size - 1] = '\0'; 108 return ret; 109 } 110 111 if (err < __LIBBPF_ERRNO__END) { 112 const char *msg; 113 114 msg = libbpf_strerror_table[ERRNO_OFFSET(err)]; 115 snprintf(buf, size, "%s", msg); 116 buf[size - 1] = '\0'; 117 return 0; 118 } 119 120 snprintf(buf, size, "Unknown libbpf error %d", err); 121 buf[size - 1] = '\0'; 122 return -1; 123 } 124 125 #define CHECK_ERR(action, err, out) do { \ 126 err = action; \ 127 if (err) \ 128 goto out; \ 129 } while(0) 130 131 132 /* Copied from tools/perf/util/util.h */ 133 #ifndef zfree 134 # define zfree(ptr) ({ free(*ptr); *ptr = NULL; }) 135 #endif 136 137 #ifndef zclose 138 # define zclose(fd) ({ \ 139 int ___err = 0; \ 140 if ((fd) >= 0) \ 141 ___err = close((fd)); \ 142 fd = -1; \ 143 ___err; }) 144 #endif 145 146 #ifdef HAVE_LIBELF_MMAP_SUPPORT 147 # define LIBBPF_ELF_C_READ_MMAP ELF_C_READ_MMAP 148 #else 149 # define LIBBPF_ELF_C_READ_MMAP ELF_C_READ 150 #endif 151 152 /* 153 * bpf_prog should be a better name but it has been used in 154 * linux/filter.h. 155 */ 156 struct bpf_program { 157 /* Index in elf obj file, for relocation use. */ 158 int idx; 159 char *section_name; 160 struct bpf_insn *insns; 161 size_t insns_cnt; 162 enum bpf_prog_type type; 163 164 struct { 165 int insn_idx; 166 int map_idx; 167 } *reloc_desc; 168 int nr_reloc; 169 170 struct { 171 int nr; 172 int *fds; 173 } instances; 174 bpf_program_prep_t preprocessor; 175 176 struct bpf_object *obj; 177 void *priv; 178 bpf_program_clear_priv_t clear_priv; 179 }; 180 181 struct bpf_map { 182 int fd; 183 char *name; 184 struct bpf_map_def def; 185 void *priv; 186 bpf_map_clear_priv_t clear_priv; 187 }; 188 189 static LIST_HEAD(bpf_objects_list); 190 191 struct bpf_object { 192 char license[64]; 193 u32 kern_version; 194 195 struct bpf_program *programs; 196 size_t nr_programs; 197 struct bpf_map *maps; 198 size_t nr_maps; 199 200 bool loaded; 201 202 /* 203 * Information when doing elf related work. Only valid if fd 204 * is valid. 205 */ 206 struct { 207 int fd; 208 void *obj_buf; 209 size_t obj_buf_sz; 210 Elf *elf; 211 GElf_Ehdr ehdr; 212 Elf_Data *symbols; 213 size_t strtabidx; 214 struct { 215 GElf_Shdr shdr; 216 Elf_Data *data; 217 } *reloc; 218 int nr_reloc; 219 int maps_shndx; 220 } efile; 221 /* 222 * All loaded bpf_object is linked in a list, which is 223 * hidden to caller. bpf_objects__<func> handlers deal with 224 * all objects. 225 */ 226 struct list_head list; 227 char path[]; 228 }; 229 #define obj_elf_valid(o) ((o)->efile.elf) 230 231 static void bpf_program__unload(struct bpf_program *prog) 232 { 233 int i; 234 235 if (!prog) 236 return; 237 238 /* 239 * If the object is opened but the program was never loaded, 240 * it is possible that prog->instances.nr == -1. 241 */ 242 if (prog->instances.nr > 0) { 243 for (i = 0; i < prog->instances.nr; i++) 244 zclose(prog->instances.fds[i]); 245 } else if (prog->instances.nr != -1) { 246 pr_warning("Internal error: instances.nr is %d\n", 247 prog->instances.nr); 248 } 249 250 prog->instances.nr = -1; 251 zfree(&prog->instances.fds); 252 } 253 254 static void bpf_program__exit(struct bpf_program *prog) 255 { 256 if (!prog) 257 return; 258 259 if (prog->clear_priv) 260 prog->clear_priv(prog, prog->priv); 261 262 prog->priv = NULL; 263 prog->clear_priv = NULL; 264 265 bpf_program__unload(prog); 266 zfree(&prog->section_name); 267 zfree(&prog->insns); 268 zfree(&prog->reloc_desc); 269 270 prog->nr_reloc = 0; 271 prog->insns_cnt = 0; 272 prog->idx = -1; 273 } 274 275 static int 276 bpf_program__init(void *data, size_t size, char *name, int idx, 277 struct bpf_program *prog) 278 { 279 if (size < sizeof(struct bpf_insn)) { 280 pr_warning("corrupted section '%s'\n", name); 281 return -EINVAL; 282 } 283 284 bzero(prog, sizeof(*prog)); 285 286 prog->section_name = strdup(name); 287 if (!prog->section_name) { 288 pr_warning("failed to alloc name for prog %s\n", 289 name); 290 goto errout; 291 } 292 293 prog->insns = malloc(size); 294 if (!prog->insns) { 295 pr_warning("failed to alloc insns for %s\n", name); 296 goto errout; 297 } 298 prog->insns_cnt = size / sizeof(struct bpf_insn); 299 memcpy(prog->insns, data, 300 prog->insns_cnt * sizeof(struct bpf_insn)); 301 prog->idx = idx; 302 prog->instances.fds = NULL; 303 prog->instances.nr = -1; 304 prog->type = BPF_PROG_TYPE_KPROBE; 305 306 return 0; 307 errout: 308 bpf_program__exit(prog); 309 return -ENOMEM; 310 } 311 312 static int 313 bpf_object__add_program(struct bpf_object *obj, void *data, size_t size, 314 char *name, int idx) 315 { 316 struct bpf_program prog, *progs; 317 int nr_progs, err; 318 319 err = bpf_program__init(data, size, name, idx, &prog); 320 if (err) 321 return err; 322 323 progs = obj->programs; 324 nr_progs = obj->nr_programs; 325 326 progs = realloc(progs, sizeof(progs[0]) * (nr_progs + 1)); 327 if (!progs) { 328 /* 329 * In this case the original obj->programs 330 * is still valid, so don't need special treat for 331 * bpf_close_object(). 332 */ 333 pr_warning("failed to alloc a new program '%s'\n", 334 name); 335 bpf_program__exit(&prog); 336 return -ENOMEM; 337 } 338 339 pr_debug("found program %s\n", prog.section_name); 340 obj->programs = progs; 341 obj->nr_programs = nr_progs + 1; 342 prog.obj = obj; 343 progs[nr_progs] = prog; 344 return 0; 345 } 346 347 static struct bpf_object *bpf_object__new(const char *path, 348 void *obj_buf, 349 size_t obj_buf_sz) 350 { 351 struct bpf_object *obj; 352 353 obj = calloc(1, sizeof(struct bpf_object) + strlen(path) + 1); 354 if (!obj) { 355 pr_warning("alloc memory failed for %s\n", path); 356 return ERR_PTR(-ENOMEM); 357 } 358 359 strcpy(obj->path, path); 360 obj->efile.fd = -1; 361 362 /* 363 * Caller of this function should also calls 364 * bpf_object__elf_finish() after data collection to return 365 * obj_buf to user. If not, we should duplicate the buffer to 366 * avoid user freeing them before elf finish. 367 */ 368 obj->efile.obj_buf = obj_buf; 369 obj->efile.obj_buf_sz = obj_buf_sz; 370 obj->efile.maps_shndx = -1; 371 372 obj->loaded = false; 373 374 INIT_LIST_HEAD(&obj->list); 375 list_add(&obj->list, &bpf_objects_list); 376 return obj; 377 } 378 379 static void bpf_object__elf_finish(struct bpf_object *obj) 380 { 381 if (!obj_elf_valid(obj)) 382 return; 383 384 if (obj->efile.elf) { 385 elf_end(obj->efile.elf); 386 obj->efile.elf = NULL; 387 } 388 obj->efile.symbols = NULL; 389 390 zfree(&obj->efile.reloc); 391 obj->efile.nr_reloc = 0; 392 zclose(obj->efile.fd); 393 obj->efile.obj_buf = NULL; 394 obj->efile.obj_buf_sz = 0; 395 } 396 397 static int bpf_object__elf_init(struct bpf_object *obj) 398 { 399 int err = 0; 400 GElf_Ehdr *ep; 401 402 if (obj_elf_valid(obj)) { 403 pr_warning("elf init: internal error\n"); 404 return -LIBBPF_ERRNO__LIBELF; 405 } 406 407 if (obj->efile.obj_buf_sz > 0) { 408 /* 409 * obj_buf should have been validated by 410 * bpf_object__open_buffer(). 411 */ 412 obj->efile.elf = elf_memory(obj->efile.obj_buf, 413 obj->efile.obj_buf_sz); 414 } else { 415 obj->efile.fd = open(obj->path, O_RDONLY); 416 if (obj->efile.fd < 0) { 417 pr_warning("failed to open %s: %s\n", obj->path, 418 strerror(errno)); 419 return -errno; 420 } 421 422 obj->efile.elf = elf_begin(obj->efile.fd, 423 LIBBPF_ELF_C_READ_MMAP, 424 NULL); 425 } 426 427 if (!obj->efile.elf) { 428 pr_warning("failed to open %s as ELF file\n", 429 obj->path); 430 err = -LIBBPF_ERRNO__LIBELF; 431 goto errout; 432 } 433 434 if (!gelf_getehdr(obj->efile.elf, &obj->efile.ehdr)) { 435 pr_warning("failed to get EHDR from %s\n", 436 obj->path); 437 err = -LIBBPF_ERRNO__FORMAT; 438 goto errout; 439 } 440 ep = &obj->efile.ehdr; 441 442 if ((ep->e_type != ET_REL) || (ep->e_machine != 0)) { 443 pr_warning("%s is not an eBPF object file\n", 444 obj->path); 445 err = -LIBBPF_ERRNO__FORMAT; 446 goto errout; 447 } 448 449 return 0; 450 errout: 451 bpf_object__elf_finish(obj); 452 return err; 453 } 454 455 static int 456 bpf_object__check_endianness(struct bpf_object *obj) 457 { 458 static unsigned int const endian = 1; 459 460 switch (obj->efile.ehdr.e_ident[EI_DATA]) { 461 case ELFDATA2LSB: 462 /* We are big endian, BPF obj is little endian. */ 463 if (*(unsigned char const *)&endian != 1) 464 goto mismatch; 465 break; 466 467 case ELFDATA2MSB: 468 /* We are little endian, BPF obj is big endian. */ 469 if (*(unsigned char const *)&endian != 0) 470 goto mismatch; 471 break; 472 default: 473 return -LIBBPF_ERRNO__ENDIAN; 474 } 475 476 return 0; 477 478 mismatch: 479 pr_warning("Error: endianness mismatch.\n"); 480 return -LIBBPF_ERRNO__ENDIAN; 481 } 482 483 static int 484 bpf_object__init_license(struct bpf_object *obj, 485 void *data, size_t size) 486 { 487 memcpy(obj->license, data, 488 min(size, sizeof(obj->license) - 1)); 489 pr_debug("license of %s is %s\n", obj->path, obj->license); 490 return 0; 491 } 492 493 static int 494 bpf_object__init_kversion(struct bpf_object *obj, 495 void *data, size_t size) 496 { 497 u32 kver; 498 499 if (size != sizeof(kver)) { 500 pr_warning("invalid kver section in %s\n", obj->path); 501 return -LIBBPF_ERRNO__FORMAT; 502 } 503 memcpy(&kver, data, sizeof(kver)); 504 obj->kern_version = kver; 505 pr_debug("kernel version of %s is %x\n", obj->path, 506 obj->kern_version); 507 return 0; 508 } 509 510 static int 511 bpf_object__init_maps(struct bpf_object *obj, void *data, 512 size_t size) 513 { 514 size_t nr_maps; 515 int i; 516 517 nr_maps = size / sizeof(struct bpf_map_def); 518 if (!data || !nr_maps) { 519 pr_debug("%s doesn't need map definition\n", 520 obj->path); 521 return 0; 522 } 523 524 pr_debug("maps in %s: %zd bytes\n", obj->path, size); 525 526 obj->maps = calloc(nr_maps, sizeof(obj->maps[0])); 527 if (!obj->maps) { 528 pr_warning("alloc maps for object failed\n"); 529 return -ENOMEM; 530 } 531 obj->nr_maps = nr_maps; 532 533 for (i = 0; i < nr_maps; i++) { 534 struct bpf_map_def *def = &obj->maps[i].def; 535 536 /* 537 * fill all fd with -1 so won't close incorrect 538 * fd (fd=0 is stdin) when failure (zclose won't close 539 * negative fd)). 540 */ 541 obj->maps[i].fd = -1; 542 543 /* Save map definition into obj->maps */ 544 *def = ((struct bpf_map_def *)data)[i]; 545 } 546 return 0; 547 } 548 549 static int 550 bpf_object__init_maps_name(struct bpf_object *obj) 551 { 552 int i; 553 Elf_Data *symbols = obj->efile.symbols; 554 555 if (!symbols || obj->efile.maps_shndx < 0) 556 return -EINVAL; 557 558 for (i = 0; i < symbols->d_size / sizeof(GElf_Sym); i++) { 559 GElf_Sym sym; 560 size_t map_idx; 561 const char *map_name; 562 563 if (!gelf_getsym(symbols, i, &sym)) 564 continue; 565 if (sym.st_shndx != obj->efile.maps_shndx) 566 continue; 567 568 map_name = elf_strptr(obj->efile.elf, 569 obj->efile.strtabidx, 570 sym.st_name); 571 map_idx = sym.st_value / sizeof(struct bpf_map_def); 572 if (map_idx >= obj->nr_maps) { 573 pr_warning("index of map \"%s\" is buggy: %zu > %zu\n", 574 map_name, map_idx, obj->nr_maps); 575 continue; 576 } 577 obj->maps[map_idx].name = strdup(map_name); 578 if (!obj->maps[map_idx].name) { 579 pr_warning("failed to alloc map name\n"); 580 return -ENOMEM; 581 } 582 pr_debug("map %zu is \"%s\"\n", map_idx, 583 obj->maps[map_idx].name); 584 } 585 return 0; 586 } 587 588 static int bpf_object__elf_collect(struct bpf_object *obj) 589 { 590 Elf *elf = obj->efile.elf; 591 GElf_Ehdr *ep = &obj->efile.ehdr; 592 Elf_Scn *scn = NULL; 593 int idx = 0, err = 0; 594 595 /* Elf is corrupted/truncated, avoid calling elf_strptr. */ 596 if (!elf_rawdata(elf_getscn(elf, ep->e_shstrndx), NULL)) { 597 pr_warning("failed to get e_shstrndx from %s\n", 598 obj->path); 599 return -LIBBPF_ERRNO__FORMAT; 600 } 601 602 while ((scn = elf_nextscn(elf, scn)) != NULL) { 603 char *name; 604 GElf_Shdr sh; 605 Elf_Data *data; 606 607 idx++; 608 if (gelf_getshdr(scn, &sh) != &sh) { 609 pr_warning("failed to get section header from %s\n", 610 obj->path); 611 err = -LIBBPF_ERRNO__FORMAT; 612 goto out; 613 } 614 615 name = elf_strptr(elf, ep->e_shstrndx, sh.sh_name); 616 if (!name) { 617 pr_warning("failed to get section name from %s\n", 618 obj->path); 619 err = -LIBBPF_ERRNO__FORMAT; 620 goto out; 621 } 622 623 data = elf_getdata(scn, 0); 624 if (!data) { 625 pr_warning("failed to get section data from %s(%s)\n", 626 name, obj->path); 627 err = -LIBBPF_ERRNO__FORMAT; 628 goto out; 629 } 630 pr_debug("section %s, size %ld, link %d, flags %lx, type=%d\n", 631 name, (unsigned long)data->d_size, 632 (int)sh.sh_link, (unsigned long)sh.sh_flags, 633 (int)sh.sh_type); 634 635 if (strcmp(name, "license") == 0) 636 err = bpf_object__init_license(obj, 637 data->d_buf, 638 data->d_size); 639 else if (strcmp(name, "version") == 0) 640 err = bpf_object__init_kversion(obj, 641 data->d_buf, 642 data->d_size); 643 else if (strcmp(name, "maps") == 0) { 644 err = bpf_object__init_maps(obj, data->d_buf, 645 data->d_size); 646 obj->efile.maps_shndx = idx; 647 } else if (sh.sh_type == SHT_SYMTAB) { 648 if (obj->efile.symbols) { 649 pr_warning("bpf: multiple SYMTAB in %s\n", 650 obj->path); 651 err = -LIBBPF_ERRNO__FORMAT; 652 } else { 653 obj->efile.symbols = data; 654 obj->efile.strtabidx = sh.sh_link; 655 } 656 } else if ((sh.sh_type == SHT_PROGBITS) && 657 (sh.sh_flags & SHF_EXECINSTR) && 658 (data->d_size > 0)) { 659 err = bpf_object__add_program(obj, data->d_buf, 660 data->d_size, name, idx); 661 if (err) { 662 char errmsg[STRERR_BUFSIZE]; 663 664 strerror_r(-err, errmsg, sizeof(errmsg)); 665 pr_warning("failed to alloc program %s (%s): %s", 666 name, obj->path, errmsg); 667 } 668 } else if (sh.sh_type == SHT_REL) { 669 void *reloc = obj->efile.reloc; 670 int nr_reloc = obj->efile.nr_reloc + 1; 671 672 reloc = realloc(reloc, 673 sizeof(*obj->efile.reloc) * nr_reloc); 674 if (!reloc) { 675 pr_warning("realloc failed\n"); 676 err = -ENOMEM; 677 } else { 678 int n = nr_reloc - 1; 679 680 obj->efile.reloc = reloc; 681 obj->efile.nr_reloc = nr_reloc; 682 683 obj->efile.reloc[n].shdr = sh; 684 obj->efile.reloc[n].data = data; 685 } 686 } 687 if (err) 688 goto out; 689 } 690 691 if (!obj->efile.strtabidx || obj->efile.strtabidx >= idx) { 692 pr_warning("Corrupted ELF file: index of strtab invalid\n"); 693 return LIBBPF_ERRNO__FORMAT; 694 } 695 if (obj->efile.maps_shndx >= 0) 696 err = bpf_object__init_maps_name(obj); 697 out: 698 return err; 699 } 700 701 static struct bpf_program * 702 bpf_object__find_prog_by_idx(struct bpf_object *obj, int idx) 703 { 704 struct bpf_program *prog; 705 size_t i; 706 707 for (i = 0; i < obj->nr_programs; i++) { 708 prog = &obj->programs[i]; 709 if (prog->idx == idx) 710 return prog; 711 } 712 return NULL; 713 } 714 715 static int 716 bpf_program__collect_reloc(struct bpf_program *prog, 717 size_t nr_maps, GElf_Shdr *shdr, 718 Elf_Data *data, Elf_Data *symbols, 719 int maps_shndx) 720 { 721 int i, nrels; 722 723 pr_debug("collecting relocating info for: '%s'\n", 724 prog->section_name); 725 nrels = shdr->sh_size / shdr->sh_entsize; 726 727 prog->reloc_desc = malloc(sizeof(*prog->reloc_desc) * nrels); 728 if (!prog->reloc_desc) { 729 pr_warning("failed to alloc memory in relocation\n"); 730 return -ENOMEM; 731 } 732 prog->nr_reloc = nrels; 733 734 for (i = 0; i < nrels; i++) { 735 GElf_Sym sym; 736 GElf_Rel rel; 737 unsigned int insn_idx; 738 struct bpf_insn *insns = prog->insns; 739 size_t map_idx; 740 741 if (!gelf_getrel(data, i, &rel)) { 742 pr_warning("relocation: failed to get %d reloc\n", i); 743 return -LIBBPF_ERRNO__FORMAT; 744 } 745 746 if (!gelf_getsym(symbols, 747 GELF_R_SYM(rel.r_info), 748 &sym)) { 749 pr_warning("relocation: symbol %"PRIx64" not found\n", 750 GELF_R_SYM(rel.r_info)); 751 return -LIBBPF_ERRNO__FORMAT; 752 } 753 754 if (sym.st_shndx != maps_shndx) { 755 pr_warning("Program '%s' contains non-map related relo data pointing to section %u\n", 756 prog->section_name, sym.st_shndx); 757 return -LIBBPF_ERRNO__RELOC; 758 } 759 760 insn_idx = rel.r_offset / sizeof(struct bpf_insn); 761 pr_debug("relocation: insn_idx=%u\n", insn_idx); 762 763 if (insns[insn_idx].code != (BPF_LD | BPF_IMM | BPF_DW)) { 764 pr_warning("bpf: relocation: invalid relo for insns[%d].code 0x%x\n", 765 insn_idx, insns[insn_idx].code); 766 return -LIBBPF_ERRNO__RELOC; 767 } 768 769 map_idx = sym.st_value / sizeof(struct bpf_map_def); 770 if (map_idx >= nr_maps) { 771 pr_warning("bpf relocation: map_idx %d large than %d\n", 772 (int)map_idx, (int)nr_maps - 1); 773 return -LIBBPF_ERRNO__RELOC; 774 } 775 776 prog->reloc_desc[i].insn_idx = insn_idx; 777 prog->reloc_desc[i].map_idx = map_idx; 778 } 779 return 0; 780 } 781 782 static int 783 bpf_object__create_maps(struct bpf_object *obj) 784 { 785 unsigned int i; 786 787 for (i = 0; i < obj->nr_maps; i++) { 788 struct bpf_map_def *def = &obj->maps[i].def; 789 int *pfd = &obj->maps[i].fd; 790 791 *pfd = bpf_create_map(def->type, 792 def->key_size, 793 def->value_size, 794 def->max_entries); 795 if (*pfd < 0) { 796 size_t j; 797 int err = *pfd; 798 799 pr_warning("failed to create map: %s\n", 800 strerror(errno)); 801 for (j = 0; j < i; j++) 802 zclose(obj->maps[j].fd); 803 return err; 804 } 805 pr_debug("create map: fd=%d\n", *pfd); 806 } 807 808 return 0; 809 } 810 811 static int 812 bpf_program__relocate(struct bpf_program *prog, struct bpf_object *obj) 813 { 814 int i; 815 816 if (!prog || !prog->reloc_desc) 817 return 0; 818 819 for (i = 0; i < prog->nr_reloc; i++) { 820 int insn_idx, map_idx; 821 struct bpf_insn *insns = prog->insns; 822 823 insn_idx = prog->reloc_desc[i].insn_idx; 824 map_idx = prog->reloc_desc[i].map_idx; 825 826 if (insn_idx >= (int)prog->insns_cnt) { 827 pr_warning("relocation out of range: '%s'\n", 828 prog->section_name); 829 return -LIBBPF_ERRNO__RELOC; 830 } 831 insns[insn_idx].src_reg = BPF_PSEUDO_MAP_FD; 832 insns[insn_idx].imm = obj->maps[map_idx].fd; 833 } 834 835 zfree(&prog->reloc_desc); 836 prog->nr_reloc = 0; 837 return 0; 838 } 839 840 841 static int 842 bpf_object__relocate(struct bpf_object *obj) 843 { 844 struct bpf_program *prog; 845 size_t i; 846 int err; 847 848 for (i = 0; i < obj->nr_programs; i++) { 849 prog = &obj->programs[i]; 850 851 err = bpf_program__relocate(prog, obj); 852 if (err) { 853 pr_warning("failed to relocate '%s'\n", 854 prog->section_name); 855 return err; 856 } 857 } 858 return 0; 859 } 860 861 static int bpf_object__collect_reloc(struct bpf_object *obj) 862 { 863 int i, err; 864 865 if (!obj_elf_valid(obj)) { 866 pr_warning("Internal error: elf object is closed\n"); 867 return -LIBBPF_ERRNO__INTERNAL; 868 } 869 870 for (i = 0; i < obj->efile.nr_reloc; i++) { 871 GElf_Shdr *shdr = &obj->efile.reloc[i].shdr; 872 Elf_Data *data = obj->efile.reloc[i].data; 873 int idx = shdr->sh_info; 874 struct bpf_program *prog; 875 size_t nr_maps = obj->nr_maps; 876 877 if (shdr->sh_type != SHT_REL) { 878 pr_warning("internal error at %d\n", __LINE__); 879 return -LIBBPF_ERRNO__INTERNAL; 880 } 881 882 prog = bpf_object__find_prog_by_idx(obj, idx); 883 if (!prog) { 884 pr_warning("relocation failed: no %d section\n", 885 idx); 886 return -LIBBPF_ERRNO__RELOC; 887 } 888 889 err = bpf_program__collect_reloc(prog, nr_maps, 890 shdr, data, 891 obj->efile.symbols, 892 obj->efile.maps_shndx); 893 if (err) 894 return err; 895 } 896 return 0; 897 } 898 899 static int 900 load_program(enum bpf_prog_type type, struct bpf_insn *insns, 901 int insns_cnt, char *license, u32 kern_version, int *pfd) 902 { 903 int ret; 904 char *log_buf; 905 906 if (!insns || !insns_cnt) 907 return -EINVAL; 908 909 log_buf = malloc(BPF_LOG_BUF_SIZE); 910 if (!log_buf) 911 pr_warning("Alloc log buffer for bpf loader error, continue without log\n"); 912 913 ret = bpf_load_program(type, insns, insns_cnt, license, 914 kern_version, log_buf, BPF_LOG_BUF_SIZE); 915 916 if (ret >= 0) { 917 *pfd = ret; 918 ret = 0; 919 goto out; 920 } 921 922 ret = -LIBBPF_ERRNO__LOAD; 923 pr_warning("load bpf program failed: %s\n", strerror(errno)); 924 925 if (log_buf && log_buf[0] != '\0') { 926 ret = -LIBBPF_ERRNO__VERIFY; 927 pr_warning("-- BEGIN DUMP LOG ---\n"); 928 pr_warning("\n%s\n", log_buf); 929 pr_warning("-- END LOG --\n"); 930 } else if (insns_cnt >= BPF_MAXINSNS) { 931 pr_warning("Program too large (%d insns), at most %d insns\n", 932 insns_cnt, BPF_MAXINSNS); 933 ret = -LIBBPF_ERRNO__PROG2BIG; 934 } else { 935 /* Wrong program type? */ 936 if (type != BPF_PROG_TYPE_KPROBE) { 937 int fd; 938 939 fd = bpf_load_program(BPF_PROG_TYPE_KPROBE, insns, 940 insns_cnt, license, kern_version, 941 NULL, 0); 942 if (fd >= 0) { 943 close(fd); 944 ret = -LIBBPF_ERRNO__PROGTYPE; 945 goto out; 946 } 947 } 948 949 if (log_buf) 950 ret = -LIBBPF_ERRNO__KVER; 951 } 952 953 out: 954 free(log_buf); 955 return ret; 956 } 957 958 static int 959 bpf_program__load(struct bpf_program *prog, 960 char *license, u32 kern_version) 961 { 962 int err = 0, fd, i; 963 964 if (prog->instances.nr < 0 || !prog->instances.fds) { 965 if (prog->preprocessor) { 966 pr_warning("Internal error: can't load program '%s'\n", 967 prog->section_name); 968 return -LIBBPF_ERRNO__INTERNAL; 969 } 970 971 prog->instances.fds = malloc(sizeof(int)); 972 if (!prog->instances.fds) { 973 pr_warning("Not enough memory for BPF fds\n"); 974 return -ENOMEM; 975 } 976 prog->instances.nr = 1; 977 prog->instances.fds[0] = -1; 978 } 979 980 if (!prog->preprocessor) { 981 if (prog->instances.nr != 1) { 982 pr_warning("Program '%s' is inconsistent: nr(%d) != 1\n", 983 prog->section_name, prog->instances.nr); 984 } 985 err = load_program(prog->type, prog->insns, prog->insns_cnt, 986 license, kern_version, &fd); 987 if (!err) 988 prog->instances.fds[0] = fd; 989 goto out; 990 } 991 992 for (i = 0; i < prog->instances.nr; i++) { 993 struct bpf_prog_prep_result result; 994 bpf_program_prep_t preprocessor = prog->preprocessor; 995 996 bzero(&result, sizeof(result)); 997 err = preprocessor(prog, i, prog->insns, 998 prog->insns_cnt, &result); 999 if (err) { 1000 pr_warning("Preprocessing the %dth instance of program '%s' failed\n", 1001 i, prog->section_name); 1002 goto out; 1003 } 1004 1005 if (!result.new_insn_ptr || !result.new_insn_cnt) { 1006 pr_debug("Skip loading the %dth instance of program '%s'\n", 1007 i, prog->section_name); 1008 prog->instances.fds[i] = -1; 1009 if (result.pfd) 1010 *result.pfd = -1; 1011 continue; 1012 } 1013 1014 err = load_program(prog->type, result.new_insn_ptr, 1015 result.new_insn_cnt, 1016 license, kern_version, &fd); 1017 1018 if (err) { 1019 pr_warning("Loading the %dth instance of program '%s' failed\n", 1020 i, prog->section_name); 1021 goto out; 1022 } 1023 1024 if (result.pfd) 1025 *result.pfd = fd; 1026 prog->instances.fds[i] = fd; 1027 } 1028 out: 1029 if (err) 1030 pr_warning("failed to load program '%s'\n", 1031 prog->section_name); 1032 zfree(&prog->insns); 1033 prog->insns_cnt = 0; 1034 return err; 1035 } 1036 1037 static int 1038 bpf_object__load_progs(struct bpf_object *obj) 1039 { 1040 size_t i; 1041 int err; 1042 1043 for (i = 0; i < obj->nr_programs; i++) { 1044 err = bpf_program__load(&obj->programs[i], 1045 obj->license, 1046 obj->kern_version); 1047 if (err) 1048 return err; 1049 } 1050 return 0; 1051 } 1052 1053 static int bpf_object__validate(struct bpf_object *obj) 1054 { 1055 if (obj->kern_version == 0) { 1056 pr_warning("%s doesn't provide kernel version\n", 1057 obj->path); 1058 return -LIBBPF_ERRNO__KVERSION; 1059 } 1060 return 0; 1061 } 1062 1063 static struct bpf_object * 1064 __bpf_object__open(const char *path, void *obj_buf, size_t obj_buf_sz) 1065 { 1066 struct bpf_object *obj; 1067 int err; 1068 1069 if (elf_version(EV_CURRENT) == EV_NONE) { 1070 pr_warning("failed to init libelf for %s\n", path); 1071 return ERR_PTR(-LIBBPF_ERRNO__LIBELF); 1072 } 1073 1074 obj = bpf_object__new(path, obj_buf, obj_buf_sz); 1075 if (IS_ERR(obj)) 1076 return obj; 1077 1078 CHECK_ERR(bpf_object__elf_init(obj), err, out); 1079 CHECK_ERR(bpf_object__check_endianness(obj), err, out); 1080 CHECK_ERR(bpf_object__elf_collect(obj), err, out); 1081 CHECK_ERR(bpf_object__collect_reloc(obj), err, out); 1082 CHECK_ERR(bpf_object__validate(obj), err, out); 1083 1084 bpf_object__elf_finish(obj); 1085 return obj; 1086 out: 1087 bpf_object__close(obj); 1088 return ERR_PTR(err); 1089 } 1090 1091 struct bpf_object *bpf_object__open(const char *path) 1092 { 1093 /* param validation */ 1094 if (!path) 1095 return NULL; 1096 1097 pr_debug("loading %s\n", path); 1098 1099 return __bpf_object__open(path, NULL, 0); 1100 } 1101 1102 struct bpf_object *bpf_object__open_buffer(void *obj_buf, 1103 size_t obj_buf_sz, 1104 const char *name) 1105 { 1106 char tmp_name[64]; 1107 1108 /* param validation */ 1109 if (!obj_buf || obj_buf_sz <= 0) 1110 return NULL; 1111 1112 if (!name) { 1113 snprintf(tmp_name, sizeof(tmp_name), "%lx-%lx", 1114 (unsigned long)obj_buf, 1115 (unsigned long)obj_buf_sz); 1116 tmp_name[sizeof(tmp_name) - 1] = '\0'; 1117 name = tmp_name; 1118 } 1119 pr_debug("loading object '%s' from buffer\n", 1120 name); 1121 1122 return __bpf_object__open(name, obj_buf, obj_buf_sz); 1123 } 1124 1125 int bpf_object__unload(struct bpf_object *obj) 1126 { 1127 size_t i; 1128 1129 if (!obj) 1130 return -EINVAL; 1131 1132 for (i = 0; i < obj->nr_maps; i++) 1133 zclose(obj->maps[i].fd); 1134 1135 for (i = 0; i < obj->nr_programs; i++) 1136 bpf_program__unload(&obj->programs[i]); 1137 1138 return 0; 1139 } 1140 1141 int bpf_object__load(struct bpf_object *obj) 1142 { 1143 int err; 1144 1145 if (!obj) 1146 return -EINVAL; 1147 1148 if (obj->loaded) { 1149 pr_warning("object should not be loaded twice\n"); 1150 return -EINVAL; 1151 } 1152 1153 obj->loaded = true; 1154 1155 CHECK_ERR(bpf_object__create_maps(obj), err, out); 1156 CHECK_ERR(bpf_object__relocate(obj), err, out); 1157 CHECK_ERR(bpf_object__load_progs(obj), err, out); 1158 1159 return 0; 1160 out: 1161 bpf_object__unload(obj); 1162 pr_warning("failed to load object '%s'\n", obj->path); 1163 return err; 1164 } 1165 1166 void bpf_object__close(struct bpf_object *obj) 1167 { 1168 size_t i; 1169 1170 if (!obj) 1171 return; 1172 1173 bpf_object__elf_finish(obj); 1174 bpf_object__unload(obj); 1175 1176 for (i = 0; i < obj->nr_maps; i++) { 1177 zfree(&obj->maps[i].name); 1178 if (obj->maps[i].clear_priv) 1179 obj->maps[i].clear_priv(&obj->maps[i], 1180 obj->maps[i].priv); 1181 obj->maps[i].priv = NULL; 1182 obj->maps[i].clear_priv = NULL; 1183 } 1184 zfree(&obj->maps); 1185 obj->nr_maps = 0; 1186 1187 if (obj->programs && obj->nr_programs) { 1188 for (i = 0; i < obj->nr_programs; i++) 1189 bpf_program__exit(&obj->programs[i]); 1190 } 1191 zfree(&obj->programs); 1192 1193 list_del(&obj->list); 1194 free(obj); 1195 } 1196 1197 struct bpf_object * 1198 bpf_object__next(struct bpf_object *prev) 1199 { 1200 struct bpf_object *next; 1201 1202 if (!prev) 1203 next = list_first_entry(&bpf_objects_list, 1204 struct bpf_object, 1205 list); 1206 else 1207 next = list_next_entry(prev, list); 1208 1209 /* Empty list is noticed here so don't need checking on entry. */ 1210 if (&next->list == &bpf_objects_list) 1211 return NULL; 1212 1213 return next; 1214 } 1215 1216 const char *bpf_object__name(struct bpf_object *obj) 1217 { 1218 return obj ? obj->path : ERR_PTR(-EINVAL); 1219 } 1220 1221 unsigned int bpf_object__kversion(struct bpf_object *obj) 1222 { 1223 return obj ? obj->kern_version : 0; 1224 } 1225 1226 struct bpf_program * 1227 bpf_program__next(struct bpf_program *prev, struct bpf_object *obj) 1228 { 1229 size_t idx; 1230 1231 if (!obj->programs) 1232 return NULL; 1233 /* First handler */ 1234 if (prev == NULL) 1235 return &obj->programs[0]; 1236 1237 if (prev->obj != obj) { 1238 pr_warning("error: program handler doesn't match object\n"); 1239 return NULL; 1240 } 1241 1242 idx = (prev - obj->programs) + 1; 1243 if (idx >= obj->nr_programs) 1244 return NULL; 1245 return &obj->programs[idx]; 1246 } 1247 1248 int bpf_program__set_priv(struct bpf_program *prog, void *priv, 1249 bpf_program_clear_priv_t clear_priv) 1250 { 1251 if (prog->priv && prog->clear_priv) 1252 prog->clear_priv(prog, prog->priv); 1253 1254 prog->priv = priv; 1255 prog->clear_priv = clear_priv; 1256 return 0; 1257 } 1258 1259 void *bpf_program__priv(struct bpf_program *prog) 1260 { 1261 return prog ? prog->priv : ERR_PTR(-EINVAL); 1262 } 1263 1264 const char *bpf_program__title(struct bpf_program *prog, bool needs_copy) 1265 { 1266 const char *title; 1267 1268 title = prog->section_name; 1269 if (needs_copy) { 1270 title = strdup(title); 1271 if (!title) { 1272 pr_warning("failed to strdup program title\n"); 1273 return ERR_PTR(-ENOMEM); 1274 } 1275 } 1276 1277 return title; 1278 } 1279 1280 int bpf_program__fd(struct bpf_program *prog) 1281 { 1282 return bpf_program__nth_fd(prog, 0); 1283 } 1284 1285 int bpf_program__set_prep(struct bpf_program *prog, int nr_instances, 1286 bpf_program_prep_t prep) 1287 { 1288 int *instances_fds; 1289 1290 if (nr_instances <= 0 || !prep) 1291 return -EINVAL; 1292 1293 if (prog->instances.nr > 0 || prog->instances.fds) { 1294 pr_warning("Can't set pre-processor after loading\n"); 1295 return -EINVAL; 1296 } 1297 1298 instances_fds = malloc(sizeof(int) * nr_instances); 1299 if (!instances_fds) { 1300 pr_warning("alloc memory failed for fds\n"); 1301 return -ENOMEM; 1302 } 1303 1304 /* fill all fd with -1 */ 1305 memset(instances_fds, -1, sizeof(int) * nr_instances); 1306 1307 prog->instances.nr = nr_instances; 1308 prog->instances.fds = instances_fds; 1309 prog->preprocessor = prep; 1310 return 0; 1311 } 1312 1313 int bpf_program__nth_fd(struct bpf_program *prog, int n) 1314 { 1315 int fd; 1316 1317 if (n >= prog->instances.nr || n < 0) { 1318 pr_warning("Can't get the %dth fd from program %s: only %d instances\n", 1319 n, prog->section_name, prog->instances.nr); 1320 return -EINVAL; 1321 } 1322 1323 fd = prog->instances.fds[n]; 1324 if (fd < 0) { 1325 pr_warning("%dth instance of program '%s' is invalid\n", 1326 n, prog->section_name); 1327 return -ENOENT; 1328 } 1329 1330 return fd; 1331 } 1332 1333 static void bpf_program__set_type(struct bpf_program *prog, 1334 enum bpf_prog_type type) 1335 { 1336 prog->type = type; 1337 } 1338 1339 int bpf_program__set_tracepoint(struct bpf_program *prog) 1340 { 1341 if (!prog) 1342 return -EINVAL; 1343 bpf_program__set_type(prog, BPF_PROG_TYPE_TRACEPOINT); 1344 return 0; 1345 } 1346 1347 int bpf_program__set_kprobe(struct bpf_program *prog) 1348 { 1349 if (!prog) 1350 return -EINVAL; 1351 bpf_program__set_type(prog, BPF_PROG_TYPE_KPROBE); 1352 return 0; 1353 } 1354 1355 static bool bpf_program__is_type(struct bpf_program *prog, 1356 enum bpf_prog_type type) 1357 { 1358 return prog ? (prog->type == type) : false; 1359 } 1360 1361 bool bpf_program__is_tracepoint(struct bpf_program *prog) 1362 { 1363 return bpf_program__is_type(prog, BPF_PROG_TYPE_TRACEPOINT); 1364 } 1365 1366 bool bpf_program__is_kprobe(struct bpf_program *prog) 1367 { 1368 return bpf_program__is_type(prog, BPF_PROG_TYPE_KPROBE); 1369 } 1370 1371 int bpf_map__fd(struct bpf_map *map) 1372 { 1373 return map ? map->fd : -EINVAL; 1374 } 1375 1376 const struct bpf_map_def *bpf_map__def(struct bpf_map *map) 1377 { 1378 return map ? &map->def : ERR_PTR(-EINVAL); 1379 } 1380 1381 const char *bpf_map__name(struct bpf_map *map) 1382 { 1383 return map ? map->name : NULL; 1384 } 1385 1386 int bpf_map__set_priv(struct bpf_map *map, void *priv, 1387 bpf_map_clear_priv_t clear_priv) 1388 { 1389 if (!map) 1390 return -EINVAL; 1391 1392 if (map->priv) { 1393 if (map->clear_priv) 1394 map->clear_priv(map, map->priv); 1395 } 1396 1397 map->priv = priv; 1398 map->clear_priv = clear_priv; 1399 return 0; 1400 } 1401 1402 void *bpf_map__priv(struct bpf_map *map) 1403 { 1404 return map ? map->priv : ERR_PTR(-EINVAL); 1405 } 1406 1407 struct bpf_map * 1408 bpf_map__next(struct bpf_map *prev, struct bpf_object *obj) 1409 { 1410 size_t idx; 1411 struct bpf_map *s, *e; 1412 1413 if (!obj || !obj->maps) 1414 return NULL; 1415 1416 s = obj->maps; 1417 e = obj->maps + obj->nr_maps; 1418 1419 if (prev == NULL) 1420 return s; 1421 1422 if ((prev < s) || (prev >= e)) { 1423 pr_warning("error in %s: map handler doesn't belong to object\n", 1424 __func__); 1425 return NULL; 1426 } 1427 1428 idx = (prev - obj->maps) + 1; 1429 if (idx >= obj->nr_maps) 1430 return NULL; 1431 return &obj->maps[idx]; 1432 } 1433 1434 struct bpf_map * 1435 bpf_object__find_map_by_name(struct bpf_object *obj, const char *name) 1436 { 1437 struct bpf_map *pos; 1438 1439 bpf_map__for_each(pos, obj) { 1440 if (pos->name && !strcmp(pos->name, name)) 1441 return pos; 1442 } 1443 return NULL; 1444 } 1445