/*
* Copyright (C) 2005 Tomasz Kojm <tkojm@clamav.net>
*
* 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., 51 Franklin Street, Fifth Floor, Boston,
* MA 02110-1301, USA.
*/
#if HAVE_CONFIG_H
#include "clamav-config.h"
#endif
#include <stdio.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <unistd.h>
#include <time.h>
#include "cltypes.h"
#include "elf.h"
#include "clamav.h"
#include "execs.h"
static short need_conversion = 0;
static inline uint16_t EC16(uint16_t v)
{
if(!need_conversion)
return v;
else
return ((v >> 8) + (v << 8));
}
static inline uint32_t EC32(uint32_t v)
{
if(!need_conversion)
return v;
else
return ((v >> 24) | ((v & 0x00FF0000) >> 8) | ((v & 0x0000FF00) << 8) | (v << 24));
}
int cli_scanelf(int desc, cli_ctx *ctx)
{
struct elf_file_hdr32 file_hdr;
struct elf_section_hdr32 *section_hdr;
uint16_t shnum, shentsize;
uint32_t entry, shoff, image;
int i;
cli_dbgmsg("in cli_scanelf\n");
if(read(desc, &file_hdr, sizeof(file_hdr)) != sizeof(file_hdr)) {
/* Not an ELF file? */
cli_dbgmsg("ELF: Can't read file header\n");
return CL_CLEAN;
}
if(memcmp(file_hdr.e_ident, "\x7f\x45\x4c\x46", 4)) {
cli_dbgmsg("ELF: Not an ELF file\n");
return CL_CLEAN;
}
if(file_hdr.e_ident[4] != 1) {
cli_dbgmsg("ELF: 64-bit binaries are not supported (yet)\n");
return CL_CLEAN;
}
if(file_hdr.e_ident[5] == 1) {
image = 0x8048000;
#if WORDS_BIGENDIAN == 0
cli_dbgmsg("ELF: File is little-endian - conversion not required\n");
#else
cli_dbgmsg("ELF: File is little-endian - data conversion enabled\n");
need_conversion = 1;
#endif
} else {
image = 0x10000;
#if WORDS_BIGENDIAN == 0
cli_dbgmsg("ELF: File is big-endian - data conversion enabled\n");
need_conversion = 1;
#else
cli_dbgmsg("ELF: File is big-endian - conversion not required\n");
#endif
}
switch(EC16(file_hdr.e_type)) {
case 0x0: /* ET_NONE */
cli_dbgmsg("ELF: File type: None\n");
break;
case 0x1: /* ET_REL */
cli_dbgmsg("ELF: File type: Relocatable\n");
break;
case 0x2: /* ET_EXEC */
cli_dbgmsg("ELF: File type: Executable\n");
break;
case 0x3: /* ET_DYN */
cli_dbgmsg("ELF: File type: Core\n");
break;
case 0x4: /* ET_CORE */
cli_dbgmsg("ELF: File type: Core\n");
break;
default:
cli_dbgmsg("ELF: File type: Unknown (%d)\n", EC16(file_hdr.e_type));
}
switch(EC16(file_hdr.e_machine)) {
/* Due to a huge list, we only include the most popular machines here */
case 0x0: /* EM_NONE */
cli_dbgmsg("ELF: Machine type: None\n");
break;
case 0x2: /* EM_SPARC */
cli_dbgmsg("ELF: Machine type: SPARC\n");
break;
case 0x3: /* EM_386 */
cli_dbgmsg("ELF: Machine type: Intel 80386\n");
break;
case 0x4: /* EM_68K */
cli_dbgmsg("ELF: Machine type: Motorola 68000\n");
break;
case 0x8: /* EM_MIPS */
cli_dbgmsg("ELF: Machine type: MIPS RS3000\n");
break;
case 0x15: /* EM_PARISC */
cli_dbgmsg("ELF: Machine type: HPPA\n");
break;
case 0x20: /* EM_PPC */
cli_dbgmsg("ELF: Machine type: PowerPC\n");
break;
case 0x21: /* EM_PPC64 */
cli_dbgmsg("ELF: Machine type: PowerPC 64-bit\n");
break;
case 0x22: /* EM_S390 */
cli_dbgmsg("ELF: Machine type: IBM S390\n");
break;
case 0x40: /* EM_ARM */
cli_dbgmsg("ELF: Machine type: ARM\n");
break;
case 0x41: /* EM_FAKE_ALPHA */
cli_dbgmsg("ELF: Machine type: Digital Alpha\n");
break;
case 0x43: /* EM_SPARCV9 */
cli_dbgmsg("ELF: Machine type: SPARC v9 64-bit\n");
break;
case 0x50: /* EM_IA_64 */
cli_dbgmsg("ELF: Machine type: IA64\n");
break;
default:
cli_dbgmsg("ELF: Machine type: Unknown (%d)\n", EC16(file_hdr.e_machine));
}
entry = EC32(file_hdr.e_entry);
cli_dbgmsg("ELF: Entry point address: 0x%.8x\n", entry);
cli_dbgmsg("ELF: Entry point offset: 0x%.8x (%d)\n", entry - image, entry - image);
shnum = EC16(file_hdr.e_shnum);
cli_dbgmsg("ELF: Number of sections: %d\n", shnum);
if(shnum > 256) {
cli_dbgmsg("ELF: Suspicious number of sections\n");
if(DETECT_BROKEN) {
if(ctx->virname)
*ctx->virname = "Broken.Executable";
return CL_VIRUS;
}
return CL_EFORMAT;
}
shentsize = EC16(file_hdr.e_shentsize);
if(shentsize != sizeof(struct elf_section_hdr32)) {
cli_dbgmsg("ELF: shentsize != sizeof(struct elf_section_hdr32)\n");
if(DETECT_BROKEN) {
if(ctx->virname)
*ctx->virname = "Broken.Executable";
return CL_VIRUS;
}
return CL_EFORMAT;
}
shoff = EC32(file_hdr.e_shoff);
cli_dbgmsg("ELF: Section header table offset: %d\n", shoff);
if(lseek(desc, shoff, SEEK_SET) != shoff) {
/* Possibly broken end of file */
if(DETECT_BROKEN) {
if(ctx->virname)
*ctx->virname = "Broken.Executable";
return CL_VIRUS;
}
return CL_CLEAN;
}
section_hdr = (struct elf_section_hdr32 *) cli_calloc(shnum, shentsize);
if(!section_hdr) {
cli_errmsg("ELF: Can't allocate memory for section headers\n");
return CL_EMEM;
}
cli_dbgmsg("------------------------------------\n");
for(i = 0; i < shnum; i++) {
if(read(desc, §ion_hdr[i], sizeof(struct elf_section_hdr32)) != sizeof(struct elf_section_hdr32)) {
cli_dbgmsg("ELF: Can't read section header\n");
cli_dbgmsg("ELF: Possibly broken ELF file\n");
free(section_hdr);
if(DETECT_BROKEN) {
if(ctx->virname)
*ctx->virname = "Broken.Executable";
return CL_VIRUS;
}
return CL_CLEAN;
}
cli_dbgmsg("ELF: Section %d\n", i);
cli_dbgmsg("ELF: Section offset: %d\n", EC32(section_hdr[i].sh_offset));
cli_dbgmsg("ELF: Section size: %d\n", EC32(section_hdr[i].sh_size));
switch(EC32(section_hdr[i].sh_type)) {
case 0x6: /* SHT_DYNAMIC */
cli_dbgmsg("ELF: Section type: Dynamic linking information\n");
break;
case 0xb: /* SHT_DYNSYM */
cli_dbgmsg("ELF: Section type: Symbols for dynamic linking\n");
break;
case 0xf: /* SHT_FINI_ARRAY */
cli_dbgmsg("ELF: Section type: Array of pointers to termination functions\n");
break;
case 0x5: /* SHT_HASH */
cli_dbgmsg("ELF: Section type: Symbol hash table\n");
break;
case 0xe: /* SHT_INIT_ARRAY */
cli_dbgmsg("ELF: Section type: Array of pointers to initialization functions\n");
break;
case 0x8: /* SHT_NOBITS */
cli_dbgmsg("ELF: Section type: Empty section (NOBITS)\n");
break;
case 0x7: /* SHT_NOTE */
cli_dbgmsg("ELF: Section type: Note section\n");
break;
case 0x0: /* SHT_NULL */
cli_dbgmsg("ELF: Section type: Null (no associated section)\n");
break;
case 0x10: /* SHT_PREINIT_ARRAY */
cli_dbgmsg("ELF: Section type: Array of pointers to preinit functions\n");
break;
case 0x1: /* SHT_PROGBITS */
cli_dbgmsg("ELF: Section type: Program information\n");
break;
case 0x9: /* SHT_REL */
cli_dbgmsg("ELF: Section type: Relocation entries w/o explicit addends\n");
break;
case 0x4: /* SHT_RELA */
cli_dbgmsg("ELF: Section type: Relocation entries with explicit addends\n");
break;
case 0x3: /* SHT_STRTAB */
cli_dbgmsg("ELF: Section type: String table\n");
break;
case 0x2: /* SHT_SYMTAB */
cli_dbgmsg("ELF: Section type: Symbol table\n");
break;
case 0x6ffffffd: /* SHT_GNU_verdef */
cli_dbgmsg("ELF: Section type: Provided symbol versions\n");
break;
case 0x6ffffffe: /* SHT_GNU_verneed */
cli_dbgmsg("ELF: Section type: Required symbol versions\n");
break;
case 0x6fffffff: /* SHT_GNU_versym */
cli_dbgmsg("ELF: Section type: Symbol Version Table\n");
break;
default :
cli_dbgmsg("ELF: Section type: Unknown\n");
}
if(EC32(section_hdr[i].sh_flags) & 0x1) /* SHF_WRITE */
cli_dbgmsg("ELF: Section contains writable data\n");
if(EC32(section_hdr[i].sh_flags) & 0x2) /* SHF_ALLOC */
cli_dbgmsg("ELF: Section occupies memory\n");
if(EC32(section_hdr[i].sh_flags) & 0x4) /* SHF_EXECINSTR */
cli_dbgmsg("ELF: Section contains executable code\n");
cli_dbgmsg("------------------------------------\n");
}
free(section_hdr);
return CL_CLEAN;
}
int cli_elfheader(int desc, struct cli_exe_info *elfinfo)
{
struct elf_file_hdr32 file_hdr;
struct elf_section_hdr32 *section_hdr;
uint16_t shnum, shentsize;
uint32_t entry, shoff, image;
int i;
cli_dbgmsg("in cli_elfheader\n");
if(read(desc, &file_hdr, sizeof(file_hdr)) != sizeof(file_hdr)) {
/* Not an ELF file? */
cli_dbgmsg("ELF: Can't read file header\n");
return -1;
}
if(memcmp(file_hdr.e_ident, "\x7f\x45\x4c\x46", 4)) {
cli_dbgmsg("ELF: Not an ELF file\n");
return -1;
}
if(file_hdr.e_ident[4] != 1) {
cli_dbgmsg("ELF: 64-bit binaries are not supported (yet)\n");
return -1;
}
if(file_hdr.e_ident[5] == 1) {
image = 0x8048000;
#if WORDS_BIGENDIAN == 1
need_conversion = 1;
#endif
} else {
image = 0x10000;
#if WORDS_BIGENDIAN == 0
need_conversion = 1;
#endif
}
entry = EC32(file_hdr.e_entry);
shnum = EC16(file_hdr.e_shnum);
if(shnum > 256) {
cli_dbgmsg("ELF: Suspicious number of sections\n");
return -1;
}
elfinfo->nsections = shnum;
shentsize = EC16(file_hdr.e_shentsize);
if(shentsize != sizeof(struct elf_section_hdr32)) {
cli_dbgmsg("ELF: shentsize != sizeof(struct elf_section_hdr32)\n");
return -1;
}
shoff = EC32(file_hdr.e_shoff);
if(lseek(desc, shoff, SEEK_SET) != shoff) {
/* Possibly broken end of file */
return -1;
}
elfinfo->section = (struct cli_exe_section *) cli_calloc(elfinfo->nsections, sizeof(struct cli_exe_section));
if(!elfinfo->section) {
cli_dbgmsg("ELF: Can't allocate memory for section headers\n");
return -1;
}
section_hdr = (struct elf_section_hdr32 *) cli_calloc(shnum, shentsize);
if(!section_hdr) {
cli_errmsg("ELF: Can't allocate memory for section headers\n");
return -1;
}
for(i = 0; i < shnum; i++) {
if(read(desc, §ion_hdr[i], sizeof(struct elf_section_hdr32)) != sizeof(struct elf_section_hdr32)) {
free(section_hdr);
free(elfinfo->section);
return -1;
}
elfinfo->section[i].rva = EC32(section_hdr[i].sh_addr);
elfinfo->section[i].raw = EC32(section_hdr[i].sh_offset);
elfinfo->section[i].rsz = EC32(section_hdr[i].sh_size);
}
free(section_hdr);
return 0;
}