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/*
File: file_elf.c
Copyright (C) 2007 Christophe GRENIER <grenier@cgsecurity.org>
This software 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 the Free Software Foundation, Inc., 51
Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#if !defined(SINGLE_FORMAT) || defined(SINGLE_FORMAT_elf)
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#ifdef HAVE_STRING_H
#include <string.h>
#endif
#include <stdio.h>
#include "types.h"
#include "common.h"
#include "filegen.h"
/*@ requires valid_register_header_check(file_stat); */
static void register_header_check_elf(file_stat_t *file_stat);
const file_hint_t file_hint_elf= {
.extension="elf",
.description="Executable and Linking Format",
.max_filesize=10*1024*1024,
.recover=1,
.enable_by_default=1,
.register_header_check=®ister_header_check_elf
};
#define EI_NIDENT 16
/* Type for a 16-bit quantity. */
typedef uint16_t Elf32_Half;
typedef uint16_t Elf64_Half;
/* Types for signed and unsigned 32-bit quantities. */
typedef uint32_t Elf32_Word;
typedef int32_t Elf32_Sword;
typedef uint32_t Elf64_Word;
typedef int32_t Elf64_Sword;
/* Types for signed and unsigned 64-bit quantities. */
typedef uint64_t Elf32_Xword;
typedef int64_t Elf32_Sxword;
typedef uint64_t Elf64_Xword;
typedef int64_t Elf64_Sxword;
/* Type of addresses. */
typedef uint32_t Elf32_Addr;
typedef uint64_t Elf64_Addr;
/* Type of file offsets. */
typedef uint32_t Elf32_Off;
typedef uint64_t Elf64_Off;
/* Type for section indices, which are 16-bit quantities. */
typedef uint16_t Elf32_Section;
typedef uint16_t Elf64_Section;
/* Type of symbol indices. */
typedef uint32_t Elf32_Symndx;
typedef uint64_t Elf64_Symndx;
typedef struct {
unsigned char e_ident[EI_NIDENT];
Elf32_Half e_type;
Elf32_Half e_machine;
Elf32_Word e_version;
Elf32_Addr e_entry;
Elf32_Off e_phoff;
Elf32_Off e_shoff;
Elf32_Word e_flags;
Elf32_Half e_ehsize;
Elf32_Half e_phentsize;
Elf32_Half e_phnum;
Elf32_Half e_shentsize;
Elf32_Half e_shnum;
Elf32_Half e_shtrndx;
} Elf32_Ehdr;
typedef struct {
unsigned char e_ident[EI_NIDENT];
Elf64_Half e_type;
Elf64_Half e_machine;
Elf64_Word e_version;
Elf64_Addr e_entry;
Elf64_Off e_phoff;
Elf64_Off e_shoff;
Elf64_Word e_flags;
Elf64_Half e_ehsize;
Elf64_Half e_phentsize;
Elf64_Half e_phnum;
Elf64_Half e_shentsize;
Elf64_Half e_shnum;
Elf64_Half e_shtrndx;
} Elf64_Ehdr;
#define EI_CLASS 4 /* File class byte index */
#define ELFCLASS32 1 /* 32-bit objects */
#define ELFCLASS64 2 /* 64-bit objects */
#define EI_DATA 5 /* Data encoding byte index */
#define ELFDATA2LSB 1 /* 2's complement, little endian */
#define ELFDATA2MSB 2 /* 2's complement, big endian */
/*@
@ requires buffer_size >= sizeof(Elf32_Ehdr);
@ requires separation: \separated(&file_hint_elf, buffer+(..), file_recovery, file_recovery_new);
@ requires valid_header_check_param(buffer, buffer_size, safe_header_only, file_recovery, file_recovery_new);
@ ensures valid_header_check_result(\result, file_recovery_new);
@ assigns *file_recovery_new;
@*/
static int header_check_elf32_lsb(const unsigned char *buffer, const unsigned int buffer_size, const unsigned int safe_header_only, const file_recovery_t *file_recovery, file_recovery_t *file_recovery_new)
{
const Elf32_Ehdr *hdr=(const Elf32_Ehdr *)buffer;
if(le32(hdr->e_version) != 1)
return 0;
/* http://en.wikipedia.org/wiki/Executable_and_Linkable_Format */
reset_file_recovery(file_recovery_new);
file_recovery_new->extension=file_hint_elf.extension;
{
const uint32_t tmp=le32(hdr->e_shoff);
file_recovery_new->min_filesize=le32(hdr->e_phoff);
if(file_recovery_new->min_filesize < tmp)
file_recovery_new->min_filesize=tmp;
}
return 1;
}
/*@
@ requires buffer_size >= sizeof(Elf32_Ehdr);
@ requires separation: \separated(&file_hint_elf, buffer+(..), file_recovery, file_recovery_new);
@ requires valid_header_check_param(buffer, buffer_size, safe_header_only, file_recovery, file_recovery_new);
@ ensures valid_header_check_result(\result, file_recovery_new);
@ assigns *file_recovery_new;
@*/
static int header_check_elf32_msb(const unsigned char *buffer, const unsigned int buffer_size, const unsigned int safe_header_only, const file_recovery_t *file_recovery, file_recovery_t *file_recovery_new)
{
const Elf32_Ehdr *hdr=(const Elf32_Ehdr *)buffer;
if(be32(hdr->e_version) != 1)
return 0;
/* http://en.wikipedia.org/wiki/Executable_and_Linkable_Format */
reset_file_recovery(file_recovery_new);
file_recovery_new->extension=file_hint_elf.extension;
{
const uint32_t tmp=be32(hdr->e_shoff);
file_recovery_new->min_filesize=be32(hdr->e_phoff);
if(file_recovery_new->min_filesize < tmp)
file_recovery_new->min_filesize=tmp;
}
return 1;
}
/*@
@ requires buffer_size >= sizeof(Elf64_Ehdr);
@ requires separation: \separated(&file_hint_elf, buffer+(..), file_recovery, file_recovery_new);
@ requires valid_header_check_param(buffer, buffer_size, safe_header_only, file_recovery, file_recovery_new);
@ ensures valid_header_check_result(\result, file_recovery_new);
@ assigns *file_recovery_new;
@*/
static int header_check_elf64_lsb(const unsigned char *buffer, const unsigned int buffer_size, const unsigned int safe_header_only, const file_recovery_t *file_recovery, file_recovery_t *file_recovery_new)
{
const Elf64_Ehdr *hdr=(const Elf64_Ehdr *)buffer;
if(le32(hdr->e_version) != 1)
return 0;
/* http://en.wikipedia.org/wiki/Executable_and_Linkable_Format */
reset_file_recovery(file_recovery_new);
file_recovery_new->extension=file_hint_elf.extension;
{
const uint64_t tmp=le64(hdr->e_shoff);
file_recovery_new->min_filesize=le64(hdr->e_phoff);
if(file_recovery_new->min_filesize < tmp)
file_recovery_new->min_filesize=tmp;
}
return 1;
}
/*@
@ requires buffer_size >= sizeof(Elf64_Ehdr);
@ requires separation: \separated(&file_hint_elf, buffer+(..), file_recovery, file_recovery_new);
@ requires valid_header_check_param(buffer, buffer_size, safe_header_only, file_recovery, file_recovery_new);
@ ensures valid_header_check_result(\result, file_recovery_new);
@ assigns *file_recovery_new;
@*/
static int header_check_elf64_msb(const unsigned char *buffer, const unsigned int buffer_size, const unsigned int safe_header_only, const file_recovery_t *file_recovery, file_recovery_t *file_recovery_new)
{
const Elf64_Ehdr *hdr=(const Elf64_Ehdr *)buffer;
if(be32(hdr->e_version) != 1)
return 0;
/* http://en.wikipedia.org/wiki/Executable_and_Linkable_Format */
reset_file_recovery(file_recovery_new);
file_recovery_new->extension=file_hint_elf.extension;
{
const uint64_t tmp=be64(hdr->e_shoff);
file_recovery_new->min_filesize=be64(hdr->e_phoff);
if(file_recovery_new->min_filesize < tmp)
file_recovery_new->min_filesize=tmp;
}
return 1;
}
static void register_header_check_elf(file_stat_t *file_stat)
{
static const unsigned char elf_header32_lsb[6] = { 0x7f, 'E','L','F',0x01, ELFDATA2LSB};
static const unsigned char elf_header32_msb[6] = { 0x7f, 'E','L','F',0x01, ELFDATA2MSB};
static const unsigned char elf_header64_lsb[6] = { 0x7f, 'E','L','F',0x02, ELFDATA2LSB};
static const unsigned char elf_header64_msb[6] = { 0x7f, 'E','L','F',0x02, ELFDATA2MSB};
register_header_check(0, elf_header32_lsb, sizeof(elf_header32_lsb), &header_check_elf32_lsb, file_stat);
register_header_check(0, elf_header32_msb, sizeof(elf_header32_msb), &header_check_elf32_msb, file_stat);
register_header_check(0, elf_header64_lsb, sizeof(elf_header64_lsb), &header_check_elf64_lsb, file_stat);
register_header_check(0, elf_header64_msb, sizeof(elf_header64_msb), &header_check_elf64_msb, file_stat);
}
#endif
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