ref: fe2b29d13bac3ab3c16490b859f452201c6b4c77
dir: /src/libmach/elf64/elf64read.c/
#include <assert.h> #include <stdio.h> #include <stdlib.h> #include <scc/mach.h> #include "../libmach.h" #include "elf64.h" static int unpack_hdr(int order, unsigned char *buf, Elf_Ehdr *hdr) { int n; n = unpack(order, buf, "'16sslqqqlssssss", hdr->e_ident, &hdr->e_type, &hdr->e_machine, &hdr->e_version, &hdr->e_entry, &hdr->e_phoff, &hdr->e_shoff, &hdr->e_flags, &hdr->e_ehsize, &hdr->e_phentsize, &hdr->e_phnum, &hdr->e_shentsize, &hdr->e_shnum, &hdr->e_shstrndx); assert(n == ELFHSZ); return n; } static int unpack_phdr(int order, unsigned char *buf, Elf_Phdr *phdr) { int n; n = unpack(order, buf, "llqqqqqq", &phdr->p_type, &phdr->p_flags, &phdr->p_offset, &phdr->p_vaddr, &phdr->p_paddr, &phdr->p_filesz, &phdr->p_memsz, &phdr->p_align); assert(n == ELFPSZ); return n; } static int unpack_shdr(int order, unsigned char *buf, Elf_Shdr *shdr) { int n; n = unpack(order, buf, "llqqqqllqq", &shdr->sh_name, &shdr->sh_type, &shdr->sh_flags, &shdr->sh_addr, &shdr->sh_offset, &shdr->sh_size, &shdr->sh_link, &shdr->sh_info, &shdr->sh_addralign, &shdr->sh_entsize); assert(n == ELFSSZ); return n; } static int unpack_sym(int order, unsigned char *buf, Elf_Sym *sym) { int n; n = unpack(order, buf, "lccsqq", &sym->st_name, &sym->st_info, &sym->st_other, &sym->st_shndx, &sym->st_value, &sym->st_size); assert(n == ELFESZ); return n; } static int readhdr(Obj *obj, FILE *fp) { Elf64 *elf; Elf_Ehdr *hdr; unsigned char buf[ELFHSZ]; elf = obj->data; hdr = &elf->hdr; if (fread(buf, ELFHSZ, 1, fp) != 1) return 0; unpack_hdr(ORDER(obj->type), buf, hdr); switch (hdr->e_type) { case ET_REL: case ET_EXEC: case ET_DYN: return 1; default: return 0; } } static int readphdr(Obj *obj, FILE *fp) { long long i; Elf_Ehdr *hdr; Elf_Phdr *phdr; Elf64 *elf; unsigned char buf[ELFPSZ]; elf = obj->data; hdr = &elf->hdr; if (hdr->e_phoff == 0 || hdr->e_phnum == 0) return 1; phdr = calloc(hdr->e_phnum, sizeof(*phdr)); if (!phdr) return 0; elf->phdr = phdr; if (!objpos(obj, fp, hdr->e_phoff)) return 0; for (i = 0; i < hdr->e_phnum; i++) { if (fread(buf, ELFPSZ, 1, fp) != 1) return 0; unpack_phdr(ORDER(obj->type), buf, &phdr[i]); } return 1; } static int readshdr(Obj *obj, FILE *fp) { long long i, nsec; Elf_Ehdr *hdr; Elf_Shdr *shdr; Elf64 *elf; unsigned char buf[ELFSSZ + ELFHSZ]; elf = obj->data; hdr = &elf->hdr; if (hdr->e_shoff == 0) return 1; if (!objpos(obj, fp, hdr->e_shoff)) return 0; if (hdr->e_shnum != SHN_UNDEF) { nsec = hdr->e_shnum; } else { Elf_Shdr sec0; fpos_t pos; fgetpos(fp, &pos); fread(buf, ELFHSZ, 1, fp); fsetpos(fp, &pos); if (ferror(fp)) return 0; unpack_shdr(ORDER(obj->type), buf, &sec0); nsec = sec0.sh_size; } if (nsec > SIZE_MAX) return 0; shdr = calloc(nsec, sizeof(*shdr)); if (!shdr) return 0; elf->shdr = shdr; elf->nsec = nsec; for (i = 0; i < nsec; i++) { if (fread(buf, ELFSSZ, 1, fp) != 1) return 0; unpack_shdr(ORDER(obj->type), buf, &shdr[i]); if (shdr[i].sh_type == SHT_SYMTAB) { /* * elf supports multiple symbol table, but we don't * care and we only support one, and we reject elf * files with more of one symbol table. */ if (elf->symtab) return 0; elf->symtab = &shdr[i]; } } return 1; } static int readsecstr(Obj *obj, FILE *fp) { long idx; size_t siz; char *str; Elf_Shdr *shdr; Elf64 *elf; Elf_Ehdr *hdr; elf = obj->data; hdr = &elf->hdr; idx = hdr->e_shstrndx; if (idx == SHN_UNDEF) return 0; if (idx == SHN_XINDEX) { if (hdr->e_shnum == 0) return 0; idx = elf->shdr[0].sh_link; } if (idx >= hdr->e_shnum) return 0; shdr = &elf->shdr[idx]; if (shdr->sh_size > SIZE_MAX) return 0; siz = shdr->sh_size; if (siz == 0) return 1; str = malloc(siz); if (!str) return 0; elf->strtbl[SEC_STRTBL] = str; elf->strsiz[SEC_STRTBL] = siz; if (!objpos(obj, fp, shdr->sh_offset)) return 0; if (fread(str, siz, 1, fp) != 1) return 0; return 1; } static int readsymstr(Obj *obj, FILE *fp) { long idx; size_t siz; char *str; Elf64 *elf; Elf_Shdr *shdr; elf = obj->data; if (!elf->symtab) return 1; idx = elf->symtab->sh_link; if (idx >= elf->nsec) return 0; shdr = &elf->shdr[idx]; if (shdr->sh_size > SIZE_MAX) return 0; siz = shdr->sh_size; if (siz == 0) return 1; str = malloc(siz); if (!str) return 0; elf->strtbl[SYM_STRTBL] = str; elf->strsiz[SYM_STRTBL] = siz; if (!objpos(obj, fp, shdr->sh_offset)) return 0; if (fread(str, siz, 1, fp) != 1) return 0; return 1; } static int readsym(Obj *obj, FILE *fp) { long nsym, i; int sec; Elf64 *elf; Elf_Sym *syms; Elf_Shdr *shdr; unsigned char buf[ELFSSZ]; elf = obj->data; if (!elf->symtab) return 1; shdr = elf->symtab; assert(shdr->sh_type == SHT_SYMTAB); nsym = shdr->sh_size / shdr->sh_entsize; if (nsym >= SIZE_MAX) return 0; syms = calloc(nsym, sizeof(*syms)); if (!syms) return 0; elf->syms = syms; elf->nsym = nsym; if (!objpos(obj, fp, shdr->sh_offset)) return 0; for (i = 0; i < nsym; i++) { if (fread(buf, ELFESZ, 1, fp) != 1) return 0; unpack_sym(ORDER(obj->type), buf, &syms[i]); sec = syms[i].st_shndx; switch (sec) { case SHN_XINDEX: /* * Elf supports an extension mechanism to allow * indexes bigger than 4 bytes. We don't care * and we reject elf files using this feature. */ return 0; case SHN_UNDEF: case SHN_ABS: case SHN_COMMON: break; default: if (sec >= elf->nsec) return 0; break; } } return 1; } int elf64read(Obj *obj, FILE *fp) { if (!readhdr(obj, fp)) return -1; if (!readphdr(obj, fp)) return -1; if (!readshdr(obj, fp)) return -1; if (!readsym(obj, fp)) return -1; if (!readsecstr(obj, fp)) return -1; if (!readsymstr(obj, fp)) return -1; return 0; }