/*- * Copyright (c) 2010,2011 Kai Wang * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. */ #include #include #include #include #include #include #include #include #include "elfcopy.h" ELFTC_VCSID("$Id: binary.c 3270 2015-12-11 18:48:56Z emaste $"); /* * Convert ELF object to `binary'. Sections with SHF_ALLOC flag set * are copied to the result binary. The relative offsets for each section * are retained, so the result binary file might contain "holes". */ void create_binary(int ifd, int ofd) { Elf *e; Elf_Scn *scn; Elf_Data *d; GElf_Shdr sh; off_t base, off; int elferr; if ((e = elf_begin(ifd, ELF_C_READ, NULL)) == NULL) errx(EXIT_FAILURE, "elf_begin() failed: %s", elf_errmsg(-1)); base = 0; if (lseek(ofd, base, SEEK_SET) < 0) err(EXIT_FAILURE, "lseek failed"); /* * Find base offset in the first iteration. */ base = -1; scn = NULL; while ((scn = elf_nextscn(e, scn)) != NULL) { if (gelf_getshdr(scn, &sh) == NULL) { warnx("gelf_getshdr failed: %s", elf_errmsg(-1)); (void) elf_errno(); continue; } if ((sh.sh_flags & SHF_ALLOC) == 0 || sh.sh_type == SHT_NOBITS || sh.sh_size == 0) continue; if (base == -1 || (off_t) sh.sh_offset < base) base = sh.sh_offset; } elferr = elf_errno(); if (elferr != 0) warnx("elf_nextscn failed: %s", elf_errmsg(elferr)); if (base == -1) return; /* * Write out sections in the second iteration. */ scn = NULL; while ((scn = elf_nextscn(e, scn)) != NULL) { if (gelf_getshdr(scn, &sh) == NULL) { warnx("gelf_getshdr failed: %s", elf_errmsg(-1)); (void) elf_errno(); continue; } if ((sh.sh_flags & SHF_ALLOC) == 0 || sh.sh_type == SHT_NOBITS || sh.sh_size == 0) continue; (void) elf_errno(); if ((d = elf_getdata(scn, NULL)) == NULL) { elferr = elf_errno(); if (elferr != 0) warnx("elf_getdata failed: %s", elf_errmsg(-1)); continue; } if (d->d_buf == NULL || d->d_size == 0) continue; /* lseek to section offset relative to `base'. */ off = sh.sh_offset - base; if (lseek(ofd, off, SEEK_SET) < 0) err(EXIT_FAILURE, "lseek failed"); /* Write out section contents. */ if (write(ofd, d->d_buf, d->d_size) != (ssize_t) d->d_size) err(EXIT_FAILURE, "write failed"); } elferr = elf_errno(); if (elferr != 0) warnx("elf_nextscn failed: %s", elf_errmsg(elferr)); } #define _SYMBOL_NAMSZ 1024 /* * Convert `binary' to ELF object. The input `binary' is converted to * a relocatable (.o) file, a few symbols will also be created to make * it easier to access the binary data in other compilation units. */ void create_elf_from_binary(struct elfcopy *ecp, int ifd, const char *ifn) { char name[_SYMBOL_NAMSZ]; struct section *sec, *sec_temp, *shtab; struct stat sb; GElf_Ehdr oeh; GElf_Shdr sh; void *content; uint64_t off, data_start, data_end, data_size; char *sym_basename, *p; /* Reset internal section list. */ if (!TAILQ_EMPTY(&ecp->v_sec)) TAILQ_FOREACH_SAFE(sec, &ecp->v_sec, sec_list, sec_temp) { TAILQ_REMOVE(&ecp->v_sec, sec, sec_list); free(sec); } if (fstat(ifd, &sb) == -1) err(EXIT_FAILURE, "fstat failed"); /* Read the input binary file to a internal buffer. */ if ((content = malloc(sb.st_size)) == NULL) err(EXIT_FAILURE, "malloc failed"); if (read(ifd, content, sb.st_size) != sb.st_size) err(EXIT_FAILURE, "read failed"); /* * TODO: copy the input binary to output binary verbatim if -O is not * specified. */ /* Create EHDR for output .o file. */ if (gelf_newehdr(ecp->eout, ecp->oec) == NULL) errx(EXIT_FAILURE, "gelf_newehdr failed: %s", elf_errmsg(-1)); if (gelf_getehdr(ecp->eout, &oeh) == NULL) errx(EXIT_FAILURE, "gelf_getehdr() failed: %s", elf_errmsg(-1)); /* Initialise e_ident fields. */ oeh.e_ident[EI_CLASS] = ecp->oec; oeh.e_ident[EI_DATA] = ecp->oed; /* * TODO: Set OSABI according to the OS platform where elfcopy(1) * was build. (probably) */ oeh.e_ident[EI_OSABI] = ELFOSABI_NONE; oeh.e_machine = ecp->oem; oeh.e_type = ET_REL; oeh.e_entry = 0; ecp->flags |= RELOCATABLE; /* Create .shstrtab section */ init_shstrtab(ecp); ecp->shstrtab->off = 0; /* * Create `.data' section which contains the binary data. The * section is inserted immediately after EHDR. */ off = gelf_fsize(ecp->eout, ELF_T_EHDR, 1, EV_CURRENT); if (off == 0) errx(EXIT_FAILURE, "gelf_fsize() failed: %s", elf_errmsg(-1)); (void) create_external_section(ecp, ".data", NULL, content, sb.st_size, off, SHT_PROGBITS, ELF_T_BYTE, SHF_ALLOC | SHF_WRITE, 1, 0, 1); /* Insert .shstrtab after .data section. */ if ((ecp->shstrtab->os = elf_newscn(ecp->eout)) == NULL) errx(EXIT_FAILURE, "elf_newscn failed: %s", elf_errmsg(-1)); insert_to_sec_list(ecp, ecp->shstrtab, 1); /* Insert section header table here. */ shtab = insert_shtab(ecp, 1); /* Count in .symtab and .strtab section headers. */ shtab->sz += gelf_fsize(ecp->eout, ELF_T_SHDR, 2, EV_CURRENT); if ((sym_basename = strdup(ifn)) == NULL) err(1, "strdup"); p = sym_basename; while ((p = strchr(p, '.')) != NULL) *p++ = '_'; #define _GEN_SYMNAME(S) do { \ snprintf(name, sizeof(name), "%s%s%s", "_binary_", sym_basename, S); \ } while (0) /* * Create symbol table. */ create_external_symtab(ecp); data_start = 0; data_end = data_start + sb.st_size; data_size = sb.st_size; _GEN_SYMNAME("_start"); add_to_symtab(ecp, name, data_start, 0, 1, ELF32_ST_INFO(STB_GLOBAL, STT_NOTYPE), 0, 1); _GEN_SYMNAME("_end"); add_to_symtab(ecp, name, data_end, 0, 1, ELF32_ST_INFO(STB_GLOBAL, STT_NOTYPE), 0, 1); _GEN_SYMNAME("_size"); add_to_symtab(ecp, name, data_size, 0, SHN_ABS, ELF32_ST_INFO(STB_GLOBAL, STT_NOTYPE), 0, 1); finalize_external_symtab(ecp); create_symtab_data(ecp); #undef _GEN_SYMNAME free(sym_basename); /* * Write the underlying ehdr. Note that it should be called * before elf_setshstrndx() since it will overwrite e->e_shstrndx. */ if (gelf_update_ehdr(ecp->eout, &oeh) == 0) errx(EXIT_FAILURE, "gelf_update_ehdr() failed: %s", elf_errmsg(-1)); /* Generate section name string table (.shstrtab). */ ecp->flags |= SYMTAB_EXIST; set_shstrtab(ecp); /* Update sh_name pointer for each section header entry. */ update_shdr(ecp, 0); /* Properly set sh_link field of .symtab section. */ if (gelf_getshdr(ecp->symtab->os, &sh) == NULL) errx(EXIT_FAILURE, "692 gelf_getshdr() failed: %s", elf_errmsg(-1)); sh.sh_link = elf_ndxscn(ecp->strtab->os); if (!gelf_update_shdr(ecp->symtab->os, &sh)) errx(EXIT_FAILURE, "gelf_update_shdr() failed: %s", elf_errmsg(-1)); /* Renew oeh to get the updated e_shstrndx. */ if (gelf_getehdr(ecp->eout, &oeh) == NULL) errx(EXIT_FAILURE, "gelf_getehdr() failed: %s", elf_errmsg(-1)); /* Resync section offsets. */ resync_sections(ecp); /* Store SHDR offset in EHDR. */ oeh.e_shoff = shtab->off; /* Update ehdr since we modified e_shoff. */ if (gelf_update_ehdr(ecp->eout, &oeh) == 0) errx(EXIT_FAILURE, "gelf_update_ehdr() failed: %s", elf_errmsg(-1)); /* Write out the output elf object. */ if (elf_update(ecp->eout, ELF_C_WRITE) < 0) errx(EXIT_FAILURE, "elf_update() failed: %s", elf_errmsg(-1)); /* Release allocated resource. */ free(content); free_elf(ecp); }