/* vi: set sw=4 ts=4: */ /* * A small little readelf implementation for uClibc * * Copyright (C) 2000 by Lineo, inc and Erik Andersen * Copyright (C) 2000-2002 Erik Andersen <andersee@debian.org> * * Several functions in this file (specifically, elf_find_section_type(), * elf_find_phdr_type(), and elf_find_dynamic(), were stolen from elflib.c from * elfvector (http://www.BitWagon.com/elfvector.html) by John F. Reiser * <jreiser@BitWagon.com>, which is copyright 2000 BitWagon Software LLC * (GPL2). * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA * */ #include <fcntl.h> #include <stdio.h> #include <stdlib.h> #include <string.h> #include <unistd.h> #include <sys/mman.h> #include <sys/stat.h> #include <sys/types.h> #include "bswap.h" #include "elf.h" int byteswap; inline uint32_t byteswap32_to_host(uint32_t value) { if (byteswap==1) { return(bswap_32(value)); } else { return(value); } } Elf32_Shdr * elf_find_section_type( int key, Elf32_Ehdr *ehdr) { int j; Elf32_Shdr *shdr = (Elf32_Shdr *)(ehdr->e_shoff + (char *)ehdr); for (j = ehdr->e_shnum; --j>=0; ++shdr) { if (key==(int)byteswap32_to_host(shdr->sh_type)) { return shdr; } } return NULL; } Elf32_Phdr * elf_find_phdr_type( int type, Elf32_Ehdr *ehdr) { int j; Elf32_Phdr *phdr = (Elf32_Phdr *)(ehdr->e_phoff + (char *)ehdr); for (j = ehdr->e_phnum; --j>=0; ++phdr) { if (type==(int)byteswap32_to_host(phdr->p_type)) { return phdr; } } return NULL; } /* Returns value if return_val==1, ptr otherwise */ void * elf_find_dynamic(int const key, Elf32_Dyn *dynp, Elf32_Ehdr *ehdr, int return_val) { Elf32_Phdr *pt_text = elf_find_phdr_type(PT_LOAD, ehdr); unsigned tx_reloc = byteswap32_to_host(pt_text->p_vaddr) - byteswap32_to_host(pt_text->p_offset); for (; DT_NULL!=byteswap32_to_host(dynp->d_tag); ++dynp) { if (key == (int)byteswap32_to_host(dynp->d_tag)) { if (return_val == 1) return (void *)(intptr_t)byteswap32_to_host(dynp->d_un.d_val); else return (void *)(byteswap32_to_host(dynp->d_un.d_val) - tx_reloc + (char *)ehdr ); } } return NULL; } int check_elf_header(Elf32_Ehdr *const ehdr) { if (! ehdr || strncmp((void *)ehdr, ELFMAG, SELFMAG) != 0 || ehdr->e_ident[EI_CLASS] != ELFCLASS32 || ehdr->e_ident[EI_VERSION] != EV_CURRENT) { return 1; } /* Check if the target endianness matches the host's endianness */ byteswap = 0; #if __BYTE_ORDER == __LITTLE_ENDIAN if (ehdr->e_ident[5] == ELFDATA2MSB) { /* Ick -- we will have to byte-swap everything */ byteswap = 1; } #elif __BYTE_ORDER == __BIG_ENDIAN if (ehdr->e_ident[5] == ELFDATA2LSB) { byteswap = 1; } #else #error Unknown host byte order! #endif /* Be vary lazy, and only byteswap the stuff we use */ if (byteswap==1) { ehdr->e_type=bswap_16(ehdr->e_type); ehdr->e_machine=bswap_16(ehdr->e_machine); ehdr->e_phoff=bswap_32(ehdr->e_phoff); ehdr->e_shoff=bswap_32(ehdr->e_shoff); ehdr->e_phnum=bswap_16(ehdr->e_phnum); ehdr->e_shnum=bswap_16(ehdr->e_shnum); } return 0; } #define ELFOSABI_NONE 0 /* UNIX System V ABI */ #define ELFOSABI_HPUX 1 /* HP-UX operating system */ #define ELFOSABI_NETBSD 2 /* NetBSD */ #define ELFOSABI_LINUX 3 /* GNU/Linux */ #define ELFOSABI_HURD 4 /* GNU/Hurd */ #define ELFOSABI_SOLARIS 6 /* Solaris */ #define ELFOSABI_AIX 7 /* AIX */ #define ELFOSABI_IRIX 8 /* IRIX */ #define ELFOSABI_FREEBSD 9 /* FreeBSD */ #define ELFOSABI_TRU64 10 /* TRU64 UNIX */ #define ELFOSABI_MODESTO 11 /* Novell Modesto */ #define ELFOSABI_OPENBSD 12 /* OpenBSD */ #define ELFOSABI_STANDALONE 255 /* Standalone (embedded) application */ #define ELFOSABI_ARM 97 /* ARM */ static void describe_elf_hdr(Elf32_Ehdr* ehdr) { char *tmp, *tmp1; switch (ehdr->e_type) { case ET_NONE: tmp = "None"; tmp1 = "NONE"; break; case ET_REL: tmp = "Relocatable File"; tmp1 = "REL"; break; case ET_EXEC: tmp = "Executable file"; tmp1 = "EXEC"; break; case ET_DYN: tmp = "Shared object file"; tmp1 = "DYN"; break; case ET_CORE: tmp = "Core file"; tmp1 = "CORE"; break; default: tmp = tmp1 = "Unknown"; } printf( "Type:\t\t%s (%s)\n", tmp1, tmp); switch (ehdr->e_machine) { case EM_NONE: tmp="No machine"; break; case EM_M32: tmp="AT&T WE 32100"; break; case EM_SPARC: tmp="SUN SPARC"; break; case EM_386: tmp="Intel 80386"; break; case EM_68K: tmp="Motorola m68k family"; break; case EM_88K: tmp="Motorola m88k family"; break; case EM_860: tmp="Intel 80860"; break; case EM_MIPS: tmp="MIPS R3000 big-endian"; break; case EM_S370: tmp="IBM System/370"; break; case EM_MIPS_RS3_LE: tmp="MIPS R3000 little-endian"; break; case EM_PARISC: tmp="HPPA"; break; case EM_VPP500: tmp="Fujitsu VPP500"; break; case EM_SPARC32PLUS: tmp="Sun's v8plus"; break; case EM_960: tmp="Intel 80960"; break; case EM_PPC: tmp="PowerPC"; break; case EM_PPC64: tmp="PowerPC 64-bit"; break; case EM_S390: tmp="IBM S390"; break; case EM_V800: tmp="NEC V800 series"; break; case EM_FR20: tmp="Fujitsu FR20"; break; case EM_RH32: tmp="TRW RH-32"; break; case EM_RCE: tmp="Motorola RCE"; break; case EM_ARM: tmp="ARM"; break; case EM_FAKE_ALPHA: tmp="Digital Alpha"; break; case EM_SH: tmp="Hitachi SH"; break; case EM_SPARCV9: tmp="SPARC v9 64-bit"; break; case EM_TRICORE: tmp="Siemens Tricore"; break; case EM_ARC: tmp="Argonaut RISC Core"; break; case EM_H8_300: tmp="Hitachi H8/300"; break; case EM_H8_300H: tmp="Hitachi H8/300H"; break; case EM_H8S: tmp="Hitachi H8S"; break; case EM_H8_500: tmp="Hitachi H8/500"; break; case EM_IA_64: tmp="Intel Merced"; break; case EM_MIPS_X: tmp="Stanford MIPS-X"; break; case EM_COLDFIRE: tmp="Motorola Coldfire"; break; case EM_68HC12: tmp="Motorola M68HC12"; break; case EM_MMA: tmp="Fujitsu MMA Multimedia Accelerator"; break; case EM_PCP: tmp="Siemens PCP"; break; case EM_NCPU: tmp="Sony nCPU embeeded RISC"; break; case EM_NDR1: tmp="Denso NDR1 microprocessor"; break; case EM_STARCORE: tmp="Motorola Start*Core processor"; break; case EM_ME16: tmp="Toyota ME16 processor"; break; case EM_ST100: tmp="STMicroelectronic ST100 processor"; break; case EM_TINYJ: tmp="Advanced Logic Corp. Tinyj emb.fam"; break; case EM_X86_64: tmp="AMD x86-64 architecture"; break; case EM_PDSP: tmp="Sony DSP Processor"; break; case EM_FX66: tmp="Siemens FX66 microcontroller"; break; case EM_ST9PLUS: tmp="STMicroelectronics ST9+ 8/16 mc"; break; case EM_ST7: tmp="STmicroelectronics ST7 8 bit mc"; break; case EM_68HC16: tmp="Motorola MC68HC16 microcontroller"; break; case EM_68HC11: tmp="Motorola MC68HC11 microcontroller"; break; case EM_68HC08: tmp="Motorola MC68HC08 microcontroller"; break; case EM_68HC05: tmp="Motorola MC68HC05 microcontroller"; break; case EM_SVX: tmp="Silicon Graphics SVx"; break; case EM_AT19: tmp="STMicroelectronics ST19 8 bit mc"; break; case EM_VAX: tmp="Digital VAX"; break; case EM_CRIS: tmp="Axis Communications 32-bit embedded processor"; break; case EM_JAVELIN: tmp="Infineon Technologies 32-bit embedded processor"; break; case EM_FIREPATH: tmp="Element 14 64-bit DSP Processor"; break; case EM_ZSP: tmp="LSI Logic 16-bit DSP Processor"; break; case EM_MMIX: tmp="Donald Knuth's educational 64-bit processor"; break; case EM_HUANY: tmp="Harvard University machine-independent object files"; break; case EM_PRISM: tmp="SiTera Prism"; break; case EM_AVR: tmp="Atmel AVR 8-bit microcontroller"; break; case EM_FR30: tmp="Fujitsu FR30"; break; case EM_D10V: tmp="Mitsubishi D10V"; break; case EM_D30V: tmp="Mitsubishi D30V"; break; case EM_V850: tmp="NEC v850"; break; case EM_M32R: tmp="Mitsubishi M32R"; break; case EM_MN10300: tmp="Matsushita MN10300"; break; case EM_MN10200: tmp="Matsushita MN10200"; break; case EM_PJ: tmp="picoJava"; break; default: tmp="unknown"; } printf( "Machine:\t%s\n", tmp); switch (ehdr->e_ident[EI_CLASS]) { case ELFCLASSNONE: tmp = "Invalid class"; break; case ELFCLASS32: tmp = "ELF32"; break; case ELFCLASS64: tmp = "ELF64"; break; default: tmp = "Unknown"; } printf( "Class:\t\t%s\n", tmp); switch (ehdr->e_ident[EI_DATA]) { case ELFDATANONE: tmp = "Invalid data encoding"; break; case ELFDATA2LSB: tmp = "2's complement, little endian"; break; case ELFDATA2MSB: tmp = "2's complement, big endian"; break; default: tmp = "Unknown"; } printf( "Data:\t\t%s\n", tmp); printf( "Version:\t%d %s\n", ehdr->e_ident[EI_VERSION], (ehdr->e_ident[EI_VERSION]==EV_CURRENT)? "(current)" : "(unknown: %lx)"); switch (ehdr->e_ident[EI_OSABI]) { case ELFOSABI_SYSV: tmp ="UNIX - System V"; break; case ELFOSABI_HPUX: tmp ="UNIX - HP-UX"; break; case ELFOSABI_NETBSD: tmp ="UNIX - NetBSD"; break; case ELFOSABI_LINUX: tmp ="UNIX - Linux"; break; case ELFOSABI_HURD: tmp ="GNU/Hurd"; break; case ELFOSABI_SOLARIS: tmp ="UNIX - Solaris"; break; case ELFOSABI_AIX: tmp ="UNIX - AIX"; break; case ELFOSABI_IRIX: tmp ="UNIX - IRIX"; break; case ELFOSABI_FREEBSD: tmp ="UNIX - FreeBSD"; break; case ELFOSABI_TRU64: tmp ="UNIX - TRU64"; break; case ELFOSABI_MODESTO: tmp ="Novell - Modesto"; break; case ELFOSABI_OPENBSD: tmp ="UNIX - OpenBSD"; break; case ELFOSABI_STANDALONE: tmp ="Standalone App"; break; case ELFOSABI_ARM: tmp ="ARM"; break; default: tmp = "Unknown"; } printf( "OS/ABI:\t\t%s\n", tmp); printf( "ABI Version:\t%d\n", ehdr->e_ident[EI_ABIVERSION]); } static void list_needed_libraries(Elf32_Dyn* dynamic, char *strtab) { Elf32_Dyn *dyns; printf("Dependancies:\n"); for (dyns=dynamic; byteswap32_to_host(dyns->d_tag)!=DT_NULL; ++dyns) { if (dyns->d_tag == DT_NEEDED) { printf("\t%s\n", (char*)strtab + byteswap32_to_host(dyns->d_un.d_val)); } } } static void describe_elf_interpreter(Elf32_Ehdr* ehdr) { Elf32_Phdr *phdr; phdr = elf_find_phdr_type(PT_INTERP, ehdr); if (phdr) { printf("Interpreter:\t%s\n", (char*)ehdr + byteswap32_to_host(phdr->p_offset)); } } int main( int argc, char** argv) { /* map the .so, and locate interesting pieces */ char *dynstr; char *thefilename = argv[1]; FILE *thefile; struct stat statbuf; Elf32_Ehdr *ehdr = 0; Elf32_Shdr *dynsec; Elf32_Dyn *dynamic; if (argc < 2 || !thefilename) { fprintf(stderr, "No filename specified.\n"); exit(EXIT_FAILURE); } if (!(thefile = fopen(thefilename, "r"))) { perror(thefilename); exit(EXIT_FAILURE); } if (fstat(fileno(thefile), &statbuf) < 0) { perror(thefilename); exit(EXIT_FAILURE); } if ((size_t)statbuf.st_size < sizeof(Elf32_Ehdr)) goto foo; /* mmap the file to make reading stuff from it effortless */ ehdr = (Elf32_Ehdr *)mmap(0, statbuf.st_size, PROT_READ|PROT_WRITE, MAP_PRIVATE, fileno(thefile), 0); foo: /* Check if this looks legit */ if (check_elf_header(ehdr)) { fprintf(stderr, "This does not appear to be an ELF file.\n"); exit(EXIT_FAILURE); } describe_elf_hdr(ehdr); describe_elf_interpreter(ehdr); dynsec = elf_find_section_type(SHT_DYNAMIC, ehdr); if (dynsec) { dynamic = (Elf32_Dyn*)(byteswap32_to_host(dynsec->sh_offset) + (intptr_t)ehdr); dynstr = (char *)elf_find_dynamic(DT_STRTAB, dynamic, ehdr, 0); list_needed_libraries(dynamic, dynstr); } return 0; }