diff options
Diffstat (limited to 'tools/lib/bpf/linker.c')
| -rw-r--r-- | tools/lib/bpf/linker.c | 248 |
1 files changed, 181 insertions, 67 deletions
diff --git a/tools/lib/bpf/linker.c b/tools/lib/bpf/linker.c index cf71d149fe26..b52f71c59616 100644 --- a/tools/lib/bpf/linker.c +++ b/tools/lib/bpf/linker.c @@ -4,6 +4,10 @@ * * Copyright (c) 2021 Facebook */ +#ifndef _GNU_SOURCE +#define _GNU_SOURCE +#endif + #include <stdbool.h> #include <stddef.h> #include <stdio.h> @@ -16,6 +20,7 @@ #include <elf.h> #include <libelf.h> #include <fcntl.h> +#include <sys/mman.h> #include "libbpf.h" #include "btf.h" #include "libbpf_internal.h" @@ -152,15 +157,19 @@ struct bpf_linker { /* global (including extern) ELF symbols */ int glob_sym_cnt; struct glob_sym *glob_syms; + + bool fd_is_owned; }; #define pr_warn_elf(fmt, ...) \ libbpf_print(LIBBPF_WARN, "libbpf: " fmt ": %s\n", ##__VA_ARGS__, elf_errmsg(-1)) -static int init_output_elf(struct bpf_linker *linker, const char *file); +static int init_output_elf(struct bpf_linker *linker); -static int linker_load_obj_file(struct bpf_linker *linker, const char *filename, - const struct bpf_linker_file_opts *opts, +static int bpf_linker_add_file(struct bpf_linker *linker, int fd, + const char *filename); + +static int linker_load_obj_file(struct bpf_linker *linker, struct src_obj *obj); static int linker_sanity_check_elf(struct src_obj *obj); static int linker_sanity_check_elf_symtab(struct src_obj *obj, struct src_sec *sec); @@ -191,7 +200,7 @@ void bpf_linker__free(struct bpf_linker *linker) if (linker->elf) elf_end(linker->elf); - if (linker->fd >= 0) + if (linker->fd >= 0 && linker->fd_is_owned) close(linker->fd); strset__free(linker->strtab_strs); @@ -233,9 +242,63 @@ struct bpf_linker *bpf_linker__new(const char *filename, struct bpf_linker_opts if (!linker) return errno = ENOMEM, NULL; - linker->fd = -1; + linker->filename = strdup(filename); + if (!linker->filename) { + err = -ENOMEM; + goto err_out; + } + + linker->fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC | O_CLOEXEC, 0644); + if (linker->fd < 0) { + err = -errno; + pr_warn("failed to create '%s': %d\n", filename, err); + goto err_out; + } + linker->fd_is_owned = true; + + err = init_output_elf(linker); + if (err) + goto err_out; + + return linker; + +err_out: + bpf_linker__free(linker); + return errno = -err, NULL; +} + +struct bpf_linker *bpf_linker__new_fd(int fd, struct bpf_linker_opts *opts) +{ + struct bpf_linker *linker; + char filename[32]; + int err; + + if (fd < 0) + return errno = EINVAL, NULL; + + if (!OPTS_VALID(opts, bpf_linker_opts)) + return errno = EINVAL, NULL; + + if (elf_version(EV_CURRENT) == EV_NONE) { + pr_warn_elf("libelf initialization failed"); + return errno = EINVAL, NULL; + } - err = init_output_elf(linker, filename); + linker = calloc(1, sizeof(*linker)); + if (!linker) + return errno = ENOMEM, NULL; + + snprintf(filename, sizeof(filename), "fd:%d", fd); + linker->filename = strdup(filename); + if (!linker->filename) { + err = -ENOMEM; + goto err_out; + } + + linker->fd = fd; + linker->fd_is_owned = false; + + err = init_output_elf(linker); if (err) goto err_out; @@ -294,23 +357,12 @@ static Elf64_Sym *add_new_sym(struct bpf_linker *linker, size_t *sym_idx) return sym; } -static int init_output_elf(struct bpf_linker *linker, const char *file) +static int init_output_elf(struct bpf_linker *linker) { int err, str_off; Elf64_Sym *init_sym; struct dst_sec *sec; - linker->filename = strdup(file); - if (!linker->filename) - return -ENOMEM; - - linker->fd = open(file, O_WRONLY | O_CREAT | O_TRUNC | O_CLOEXEC, 0644); - if (linker->fd < 0) { - err = -errno; - pr_warn("failed to create '%s': %s\n", file, errstr(err)); - return err; - } - linker->elf = elf_begin(linker->fd, ELF_C_WRITE, NULL); if (!linker->elf) { pr_warn_elf("failed to create ELF object"); @@ -436,19 +488,16 @@ static int init_output_elf(struct bpf_linker *linker, const char *file) return 0; } -int bpf_linker__add_file(struct bpf_linker *linker, const char *filename, - const struct bpf_linker_file_opts *opts) +static int bpf_linker_add_file(struct bpf_linker *linker, int fd, + const char *filename) { struct src_obj obj = {}; int err = 0; - if (!OPTS_VALID(opts, bpf_linker_file_opts)) - return libbpf_err(-EINVAL); - - if (!linker->elf) - return libbpf_err(-EINVAL); + obj.filename = filename; + obj.fd = fd; - err = err ?: linker_load_obj_file(linker, filename, opts, &obj); + err = err ?: linker_load_obj_file(linker, &obj); err = err ?: linker_append_sec_data(linker, &obj); err = err ?: linker_append_elf_syms(linker, &obj); err = err ?: linker_append_elf_relos(linker, &obj); @@ -463,12 +512,91 @@ int bpf_linker__add_file(struct bpf_linker *linker, const char *filename, free(obj.sym_map); if (obj.elf) elf_end(obj.elf); - if (obj.fd >= 0) - close(obj.fd); + return err; +} + +int bpf_linker__add_file(struct bpf_linker *linker, const char *filename, + const struct bpf_linker_file_opts *opts) +{ + int fd, err; + + if (!OPTS_VALID(opts, bpf_linker_file_opts)) + return libbpf_err(-EINVAL); + + if (!linker->elf) + return libbpf_err(-EINVAL); + + fd = open(filename, O_RDONLY | O_CLOEXEC); + if (fd < 0) { + err = -errno; + pr_warn("failed to open file '%s': %s\n", filename, errstr(err)); + return libbpf_err(err); + } + + err = bpf_linker_add_file(linker, fd, filename); + close(fd); return libbpf_err(err); } +int bpf_linker__add_fd(struct bpf_linker *linker, int fd, + const struct bpf_linker_file_opts *opts) +{ + char filename[32]; + int err; + + if (!OPTS_VALID(opts, bpf_linker_file_opts)) + return libbpf_err(-EINVAL); + + if (!linker->elf) + return libbpf_err(-EINVAL); + + if (fd < 0) + return libbpf_err(-EINVAL); + + snprintf(filename, sizeof(filename), "fd:%d", fd); + err = bpf_linker_add_file(linker, fd, filename); + return libbpf_err(err); +} + +int bpf_linker__add_buf(struct bpf_linker *linker, void *buf, size_t buf_sz, + const struct bpf_linker_file_opts *opts) +{ + char filename[32]; + int fd, written, ret; + + if (!OPTS_VALID(opts, bpf_linker_file_opts)) + return libbpf_err(-EINVAL); + + if (!linker->elf) + return libbpf_err(-EINVAL); + + snprintf(filename, sizeof(filename), "mem:%p+%zu", buf, buf_sz); + + fd = memfd_create(filename, 0); + if (fd < 0) { + ret = -errno; + pr_warn("failed to create memfd '%s': %s\n", filename, errstr(ret)); + return libbpf_err(ret); + } + + written = 0; + while (written < buf_sz) { + ret = write(fd, buf, buf_sz); + if (ret < 0) { + ret = -errno; + pr_warn("failed to write '%s': %s\n", filename, errstr(ret)); + goto err_out; + } + written += ret; + } + + ret = bpf_linker_add_file(linker, fd, filename); +err_out: + close(fd); + return libbpf_err(ret); +} + static bool is_dwarf_sec_name(const char *name) { /* approximation, but the actual list is too long */ @@ -534,8 +662,7 @@ static struct src_sec *add_src_sec(struct src_obj *obj, const char *sec_name) return sec; } -static int linker_load_obj_file(struct bpf_linker *linker, const char *filename, - const struct bpf_linker_file_opts *opts, +static int linker_load_obj_file(struct bpf_linker *linker, struct src_obj *obj) { int err = 0; @@ -554,36 +681,26 @@ static int linker_load_obj_file(struct bpf_linker *linker, const char *filename, #error "Unknown __BYTE_ORDER__" #endif - pr_debug("linker: adding object file '%s'...\n", filename); - - obj->filename = filename; + pr_debug("linker: adding object file '%s'...\n", obj->filename); - obj->fd = open(filename, O_RDONLY | O_CLOEXEC); - if (obj->fd < 0) { - err = -errno; - pr_warn("failed to open file '%s': %s\n", filename, errstr(err)); - return err; - } obj->elf = elf_begin(obj->fd, ELF_C_READ_MMAP, NULL); if (!obj->elf) { - err = -errno; - pr_warn_elf("failed to parse ELF file '%s'", filename); - return err; + pr_warn_elf("failed to parse ELF file '%s'", obj->filename); + return -EINVAL; } /* Sanity check ELF file high-level properties */ ehdr = elf64_getehdr(obj->elf); if (!ehdr) { - err = -errno; - pr_warn_elf("failed to get ELF header for %s", filename); - return err; + pr_warn_elf("failed to get ELF header for %s", obj->filename); + return -EINVAL; } /* Linker output endianness set by first input object */ obj_byteorder = ehdr->e_ident[EI_DATA]; if (obj_byteorder != ELFDATA2LSB && obj_byteorder != ELFDATA2MSB) { err = -EOPNOTSUPP; - pr_warn("unknown byte order of ELF file %s\n", filename); + pr_warn("unknown byte order of ELF file %s\n", obj->filename); return err; } if (link_byteorder == ELFDATANONE) { @@ -593,7 +710,7 @@ static int linker_load_obj_file(struct bpf_linker *linker, const char *filename, obj_byteorder == ELFDATA2MSB ? "big" : "little"); } else if (link_byteorder != obj_byteorder) { err = -EOPNOTSUPP; - pr_warn("byte order mismatch with ELF file %s\n", filename); + pr_warn("byte order mismatch with ELF file %s\n", obj->filename); return err; } @@ -601,14 +718,13 @@ static int linker_load_obj_file(struct bpf_linker *linker, const char *filename, || ehdr->e_machine != EM_BPF || ehdr->e_ident[EI_CLASS] != ELFCLASS64) { err = -EOPNOTSUPP; - pr_warn_elf("unsupported kind of ELF file %s", filename); + pr_warn_elf("unsupported kind of ELF file %s", obj->filename); return err; } if (elf_getshdrstrndx(obj->elf, &obj->shstrs_sec_idx)) { - err = -errno; - pr_warn_elf("failed to get SHSTRTAB section index for %s", filename); - return err; + pr_warn_elf("failed to get SHSTRTAB section index for %s", obj->filename); + return -EINVAL; } scn = NULL; @@ -618,26 +734,23 @@ static int linker_load_obj_file(struct bpf_linker *linker, const char *filename, shdr = elf64_getshdr(scn); if (!shdr) { - err = -errno; pr_warn_elf("failed to get section #%zu header for %s", - sec_idx, filename); - return err; + sec_idx, obj->filename); + return -EINVAL; } sec_name = elf_strptr(obj->elf, obj->shstrs_sec_idx, shdr->sh_name); if (!sec_name) { - err = -errno; pr_warn_elf("failed to get section #%zu name for %s", - sec_idx, filename); - return err; + sec_idx, obj->filename); + return -EINVAL; } data = elf_getdata(scn, 0); if (!data) { - err = -errno; pr_warn_elf("failed to get section #%zu (%s) data from %s", - sec_idx, sec_name, filename); - return err; + sec_idx, sec_name, obj->filename); + return -EINVAL; } sec = add_src_sec(obj, sec_name); @@ -672,7 +785,7 @@ static int linker_load_obj_file(struct bpf_linker *linker, const char *filename, err = libbpf_get_error(obj->btf); if (err) { pr_warn("failed to parse .BTF from %s: %s\n", - filename, errstr(err)); + obj->filename, errstr(err)); return err; } sec->skipped = true; @@ -683,7 +796,7 @@ static int linker_load_obj_file(struct bpf_linker *linker, const char *filename, err = libbpf_get_error(obj->btf_ext); if (err) { pr_warn("failed to parse .BTF.ext from '%s': %s\n", - filename, errstr(err)); + obj->filename, errstr(err)); return err; } sec->skipped = true; @@ -700,7 +813,7 @@ static int linker_load_obj_file(struct bpf_linker *linker, const char *filename, break; default: pr_warn("unrecognized section #%zu (%s) in %s\n", - sec_idx, sec_name, filename); + sec_idx, sec_name, obj->filename); err = -EINVAL; return err; } @@ -2680,22 +2793,23 @@ int bpf_linker__finalize(struct bpf_linker *linker) /* Finalize ELF layout */ if (elf_update(linker->elf, ELF_C_NULL) < 0) { - err = -errno; + err = -EINVAL; pr_warn_elf("failed to finalize ELF layout"); return libbpf_err(err); } /* Write out final ELF contents */ if (elf_update(linker->elf, ELF_C_WRITE) < 0) { - err = -errno; + err = -EINVAL; pr_warn_elf("failed to write ELF contents"); return libbpf_err(err); } elf_end(linker->elf); - close(linker->fd); - linker->elf = NULL; + + if (linker->fd_is_owned) + close(linker->fd); linker->fd = -1; return 0; |