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denyhosts/clamscan/libclamav/elf.c
aixiao 07f551d5e4 添加病毒扫描
2022-10-22 18:41:00 +08:00

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/*
* Copyright (C) 2013-2022 Cisco Systems, Inc. and/or its affiliates. All rights reserved.
* Copyright (C) 2007-2013 Sourcefire, Inc.
*
* Authors: Tomasz Kojm
*
* Acknowledgements: The header structures were based upon "ELF: Executable
* and Linkable Format, Portable Formats Specification,
* Version 1.1".
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* 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>
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
#include <time.h>
#include "elf.h"
#include "clamav.h"
#include "execs.h"
#include "matcher.h"
#include "scanners.h"
#define EC16(v, conv) (conv ? cbswap16(v) : v)
#define EC32(v, conv) (conv ? cbswap32(v) : v)
#define EC64(v, conv) (conv ? cbswap64(v) : v)
#define CLI_TMPUNLK() \
if (!ctx->engine->keeptmp) { \
if (cli_unlink(tempfile)) { \
free(tempfile); \
return CL_EUNLINK; \
} \
}
static void cli_elf_sectionlog(uint32_t sh_type, uint32_t sh_flags);
static uint32_t cli_rawaddr32(uint32_t vaddr, struct elf_program_hdr32 *ph, uint16_t phnum, uint8_t conv, uint8_t *err)
{
uint16_t i, found = 0;
for (i = 0; i < phnum; i++) {
if (EC32(ph[i].p_vaddr, conv) <= vaddr && EC32(ph[i].p_vaddr, conv) + EC32(ph[i].p_memsz, conv) > vaddr) {
found = 1;
break;
}
}
if (!found) {
*err = 1;
return 0;
}
*err = 0;
return vaddr - EC32(ph[i].p_vaddr, conv) + EC32(ph[i].p_offset, conv);
}
static uint64_t cli_rawaddr64(uint64_t vaddr, struct elf_program_hdr64 *ph, uint16_t phnum, uint8_t conv, uint8_t *err)
{
uint16_t i, found = 0;
for (i = 0; i < phnum; i++) {
if (EC64(ph[i].p_vaddr, conv) <= vaddr && EC64(ph[i].p_vaddr, conv) + EC64(ph[i].p_memsz, conv) > vaddr) {
found = 1;
break;
}
}
if (!found) {
*err = 1;
return 0;
}
*err = 0;
return vaddr - EC64(ph[i].p_vaddr, conv) + EC64(ph[i].p_offset, conv);
}
/* Return converted endian-fixed header, or error code */
static int cli_elf_fileheader(cli_ctx *ctx, fmap_t *map, union elf_file_hdr *file_hdr,
uint8_t *do_convert, uint8_t *is64)
{
uint8_t format64, conv;
/* Load enough for smaller header first */
if (fmap_readn(map, file_hdr, 0, sizeof(struct elf_file_hdr32)) != sizeof(struct elf_file_hdr32)) {
/* Not an ELF file? */
cli_dbgmsg("ELF: Can't read file header\n");
return CL_BREAK;
}
if (memcmp(file_hdr->hdr64.e_ident, "\x7f\x45\x4c\x46", 4)) {
cli_dbgmsg("ELF: Not an ELF file\n");
return CL_BREAK;
}
switch (file_hdr->hdr64.e_ident[4]) {
case 1:
cli_dbgmsg("ELF: ELF class 1 (32-bit)\n");
format64 = 0;
break;
case 2:
cli_dbgmsg("ELF: ELF class 2 (64-bit)\n");
format64 = 1;
break;
default:
cli_dbgmsg("ELF: Unknown ELF class (%u)\n", file_hdr->hdr64.e_ident[4]);
if (ctx && SCAN_HEURISTIC_BROKEN && (CL_VIRUS == cli_append_virus(ctx, "Heuristics.Broken.Executable"))) {
return CL_VIRUS;
}
return CL_BREAK;
}
/* Need to know to endian convert */
if (file_hdr->hdr64.e_ident[5] == 1) {
#if WORDS_BIGENDIAN == 0
if (ctx)
cli_dbgmsg("ELF: File is little-endian - conversion not required\n");
conv = 0;
#else
if (ctx)
cli_dbgmsg("ELF: File is little-endian - data conversion enabled\n");
conv = 1;
#endif
} else {
#if WORDS_BIGENDIAN == 0
if (ctx)
cli_dbgmsg("ELF: File is big-endian - data conversion enabled\n");
conv = 1;
#else
if (ctx)
cli_dbgmsg("ELF: File is big-endian - conversion not required\n");
conv = 0;
#endif
}
*do_convert = conv;
*is64 = format64;
/* Solve bit-size and conversion pronto */
file_hdr->hdr64.e_type = EC16(file_hdr->hdr64.e_type, conv);
file_hdr->hdr64.e_machine = EC16(file_hdr->hdr64.e_machine, conv);
file_hdr->hdr64.e_version = EC32(file_hdr->hdr64.e_version, conv);
if (format64) {
/* Read rest of 64-bit header */
if (fmap_readn(map, file_hdr->hdr32.pad, sizeof(struct elf_file_hdr32), ELF_HDR_SIZEDIFF) != ELF_HDR_SIZEDIFF) {
/* Not an ELF file? */
cli_dbgmsg("ELF: Can't read file header\n");
return CL_BREAK;
}
/* Now endian convert, if needed */
if (conv) {
file_hdr->hdr64.e_entry = EC64(file_hdr->hdr64.e_entry, conv);
file_hdr->hdr64.e_phoff = EC64(file_hdr->hdr64.e_phoff, conv);
file_hdr->hdr64.e_shoff = EC64(file_hdr->hdr64.e_shoff, conv);
file_hdr->hdr64.e_flags = EC32(file_hdr->hdr64.e_flags, conv);
file_hdr->hdr64.e_ehsize = EC16(file_hdr->hdr64.e_ehsize, conv);
file_hdr->hdr64.e_phentsize = EC16(file_hdr->hdr64.e_phentsize, conv);
file_hdr->hdr64.e_phnum = EC16(file_hdr->hdr64.e_phnum, conv);
file_hdr->hdr64.e_shentsize = EC16(file_hdr->hdr64.e_shentsize, conv);
file_hdr->hdr64.e_shnum = EC16(file_hdr->hdr64.e_shnum, conv);
file_hdr->hdr64.e_shstrndx = EC16(file_hdr->hdr64.e_shstrndx, conv);
}
} else {
/* Convert 32-bit structure, if needed */
if (conv) {
file_hdr->hdr32.hdr.e_entry = EC32(file_hdr->hdr32.hdr.e_entry, conv);
file_hdr->hdr32.hdr.e_phoff = EC32(file_hdr->hdr32.hdr.e_phoff, conv);
file_hdr->hdr32.hdr.e_shoff = EC32(file_hdr->hdr32.hdr.e_shoff, conv);
file_hdr->hdr32.hdr.e_flags = EC32(file_hdr->hdr32.hdr.e_flags, conv);
file_hdr->hdr32.hdr.e_ehsize = EC16(file_hdr->hdr32.hdr.e_ehsize, conv);
file_hdr->hdr32.hdr.e_phentsize = EC16(file_hdr->hdr32.hdr.e_phentsize, conv);
file_hdr->hdr32.hdr.e_phnum = EC16(file_hdr->hdr32.hdr.e_phnum, conv);
file_hdr->hdr32.hdr.e_shentsize = EC16(file_hdr->hdr32.hdr.e_shentsize, conv);
file_hdr->hdr32.hdr.e_shnum = EC16(file_hdr->hdr32.hdr.e_shnum, conv);
file_hdr->hdr32.hdr.e_shstrndx = EC16(file_hdr->hdr32.hdr.e_shstrndx, conv);
}
/* Wipe pad for safety */
memset(file_hdr->hdr32.pad, 0, ELF_HDR_SIZEDIFF);
}
return CL_CLEAN;
}
/* Read 32-bit program headers */
static int cli_elf_ph32(cli_ctx *ctx, fmap_t *map, struct cli_exe_info *elfinfo,
struct elf_file_hdr32 *file_hdr, uint8_t conv)
{
struct elf_program_hdr32 *program_hdr = NULL;
uint16_t phnum, phentsize;
uint32_t entry, fentry = 0, phoff;
uint32_t i;
uint8_t err;
/* Program headers and Entry */
phnum = file_hdr->e_phnum;
cli_dbgmsg("ELF: Number of program headers: %d\n", phnum);
if (phnum > 128) {
cli_dbgmsg("ELF: Suspicious number of program headers\n");
if (ctx && SCAN_HEURISTIC_BROKEN && (CL_VIRUS == cli_append_virus(ctx, "Heuristics.Broken.Executable"))) {
return CL_VIRUS;
}
return CL_EFORMAT;
}
entry = file_hdr->e_entry;
if (phnum && entry) {
phentsize = file_hdr->e_phentsize;
/* Sanity check */
if (phentsize != sizeof(struct elf_program_hdr32)) {
cli_dbgmsg("ELF: phentsize != sizeof(struct elf_program_hdr32)\n");
if (ctx && SCAN_HEURISTIC_BROKEN && (CL_VIRUS == cli_append_virus(ctx, "Heuristics.Broken.Executable"))) {
return CL_VIRUS;
}
return CL_EFORMAT;
}
phoff = file_hdr->e_phoff;
if (ctx) {
cli_dbgmsg("ELF: Program header table offset: %u\n", phoff);
}
if (phnum) {
program_hdr = (struct elf_program_hdr32 *)cli_calloc(phnum, sizeof(struct elf_program_hdr32));
if (!program_hdr) {
cli_errmsg("ELF: Can't allocate memory for program headers\n");
return CL_EMEM;
}
if (ctx) {
cli_dbgmsg("------------------------------------\n");
}
}
for (i = 0; i < phnum; i++) {
err = 0;
if (fmap_readn(map, &program_hdr[i], phoff, sizeof(struct elf_program_hdr32)) != sizeof(struct elf_program_hdr32))
err = 1;
phoff += sizeof(struct elf_program_hdr32);
if (err) {
cli_dbgmsg("ELF: Can't read segment #%d\n", i);
if (ctx) {
cli_dbgmsg("ELF: Possibly broken ELF file\n");
}
free(program_hdr);
if (ctx && SCAN_HEURISTIC_BROKEN && (CL_VIRUS == cli_append_virus(ctx, "Heuristics.Broken.Executable"))) {
return CL_VIRUS;
}
return CL_BREAK;
}
if (ctx) {
cli_dbgmsg("ELF: Segment #%d\n", i);
cli_dbgmsg("ELF: Segment type: 0x%x\n", EC32(program_hdr[i].p_type, conv));
cli_dbgmsg("ELF: Segment offset: 0x%x\n", EC32(program_hdr[i].p_offset, conv));
cli_dbgmsg("ELF: Segment virtual address: 0x%x\n", EC32(program_hdr[i].p_vaddr, conv));
cli_dbgmsg("ELF: Segment real size: 0x%x\n", EC32(program_hdr[i].p_filesz, conv));
cli_dbgmsg("ELF: Segment virtual size: 0x%x\n", EC32(program_hdr[i].p_memsz, conv));
cli_dbgmsg("------------------------------------\n");
}
}
fentry = cli_rawaddr32(entry, program_hdr, phnum, conv, &err);
free(program_hdr);
if (err) {
cli_dbgmsg("ELF: Can't calculate file offset of entry point\n");
if (ctx && SCAN_HEURISTIC_BROKEN && (CL_VIRUS == cli_append_virus(ctx, "Heuristics.Broken.Executable"))) {
return CL_VIRUS;
}
return CL_EFORMAT;
}
if (ctx) {
cli_dbgmsg("ELF: Entry point address: 0x%.8x\n", entry);
cli_dbgmsg("ELF: Entry point offset: 0x%.8x (%d)\n", fentry, fentry);
}
}
if (elfinfo) {
elfinfo->ep = fentry;
}
return CL_CLEAN;
}
/* Read 64-bit program headers */
static int cli_elf_ph64(cli_ctx *ctx, fmap_t *map, struct cli_exe_info *elfinfo,
struct elf_file_hdr64 *file_hdr, uint8_t conv)
{
struct elf_program_hdr64 *program_hdr = NULL;
uint16_t phnum, phentsize;
uint64_t entry, fentry = 0, phoff;
uint32_t i;
uint8_t err;
/* Program headers and Entry */
phnum = file_hdr->e_phnum;
cli_dbgmsg("ELF: Number of program headers: %d\n", phnum);
if (phnum > 128) {
cli_dbgmsg("ELF: Suspicious number of program headers\n");
if (ctx && SCAN_HEURISTIC_BROKEN && (CL_VIRUS == cli_append_virus(ctx, "Heuristics.Broken.Executable"))) {
return CL_VIRUS;
}
return CL_EFORMAT;
}
entry = file_hdr->e_entry;
if (phnum && entry) {
phentsize = file_hdr->e_phentsize;
/* Sanity check */
if (phentsize != sizeof(struct elf_program_hdr64)) {
cli_dbgmsg("ELF: phentsize != sizeof(struct elf_program_hdr64)\n");
if (ctx && SCAN_HEURISTIC_BROKEN && (CL_VIRUS == cli_append_virus(ctx, "Heuristics.Broken.Executable"))) {
return CL_VIRUS;
}
return CL_EFORMAT;
}
phoff = file_hdr->e_phoff;
if (ctx) {
cli_dbgmsg("ELF: Program header table offset: " STDu64 "\n", phoff);
}
if (phnum) {
program_hdr = (struct elf_program_hdr64 *)cli_calloc(phnum, sizeof(struct elf_program_hdr64));
if (!program_hdr) {
cli_errmsg("ELF: Can't allocate memory for program headers\n");
return CL_EMEM;
}
if (ctx) {
cli_dbgmsg("------------------------------------\n");
}
}
for (i = 0; i < phnum; i++) {
err = 0;
if (fmap_readn(map, &program_hdr[i], phoff, sizeof(struct elf_program_hdr64)) != sizeof(struct elf_program_hdr64))
err = 1;
phoff += sizeof(struct elf_program_hdr64);
if (err) {
cli_dbgmsg("ELF: Can't read segment #%d\n", i);
if (ctx) {
cli_dbgmsg("ELF: Possibly broken ELF file\n");
}
free(program_hdr);
if (ctx && SCAN_HEURISTIC_BROKEN && (CL_VIRUS == cli_append_virus(ctx, "Heuristics.Broken.Executable"))) {
return CL_VIRUS;
}
return CL_BREAK;
}
if (ctx) {
cli_dbgmsg("ELF: Segment #%d\n", i);
cli_dbgmsg("ELF: Segment type: 0x" STDx32 "\n", (uint32_t)EC32(program_hdr[i].p_type, conv));
cli_dbgmsg("ELF: Segment offset: 0x" STDx64 "\n", (uint64_t)EC64(program_hdr[i].p_offset, conv));
cli_dbgmsg("ELF: Segment virtual address: 0x" STDx64 "\n", (uint64_t)EC64(program_hdr[i].p_vaddr, conv));
cli_dbgmsg("ELF: Segment real size: 0x" STDx64 "\n", (uint64_t)EC64(program_hdr[i].p_filesz, conv));
cli_dbgmsg("ELF: Segment virtual size: 0x" STDx64 "\n", (uint64_t)EC64(program_hdr[i].p_memsz, conv));
cli_dbgmsg("------------------------------------\n");
}
}
fentry = cli_rawaddr64(entry, program_hdr, phnum, conv, &err);
free(program_hdr);
if (err) {
cli_dbgmsg("ELF: Can't calculate file offset of entry point\n");
if (ctx && SCAN_HEURISTIC_BROKEN && (CL_VIRUS == cli_append_virus(ctx, "Heuristics.Broken.Executable"))) {
return CL_VIRUS;
}
return CL_EFORMAT;
}
if (ctx) {
cli_dbgmsg("ELF: Entry point address: 0x%.16" PRIx64 "\n", entry);
cli_dbgmsg("ELF: Entry point offset: 0x%.16" PRIx64 " (" STDi64 ")\n", fentry, fentry);
}
}
if (elfinfo) {
elfinfo->ep = fentry;
}
return CL_CLEAN;
}
/* 32-bit version of section header parsing */
static int cli_elf_sh32(cli_ctx *ctx, fmap_t *map, struct cli_exe_info *elfinfo,
struct elf_file_hdr32 *file_hdr, uint8_t conv)
{
struct elf_section_hdr32 *section_hdr = NULL;
uint16_t shnum, shentsize;
uint32_t shoff, i;
shnum = file_hdr->e_shnum;
cli_dbgmsg("ELF: Number of sections: %d\n", shnum);
if (ctx && (shnum > 2048)) {
cli_dbgmsg("ELF: Number of sections > 2048, skipping\n");
return CL_BREAK;
} else if (elfinfo && (shnum > 256)) {
cli_dbgmsg("ELF: Suspicious number of sections\n");
return CL_BREAK;
}
if (elfinfo) {
elfinfo->nsections = shnum;
}
shentsize = file_hdr->e_shentsize;
/* Sanity check */
if (shentsize != sizeof(struct elf_section_hdr32)) {
cli_dbgmsg("ELF: shentsize != sizeof(struct elf_section_hdr32)\n");
if (ctx && SCAN_HEURISTIC_BROKEN && (CL_VIRUS == cli_append_virus(ctx, "Heuristics.Broken.Executable"))) {
return CL_VIRUS;
}
return CL_EFORMAT;
}
if (elfinfo && !shnum) {
return CL_CLEAN;
}
shoff = file_hdr->e_shoff;
if (ctx)
cli_dbgmsg("ELF: Section header table offset: %d\n", shoff);
if (elfinfo) {
elfinfo->sections = (struct cli_exe_section *)cli_calloc(shnum, sizeof(struct cli_exe_section));
if (!elfinfo->sections) {
cli_dbgmsg("ELF: Can't allocate memory for section headers\n");
return CL_EMEM;
}
}
if (shnum) {
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;
}
if (ctx) {
cli_dbgmsg("------------------------------------\n");
}
}
/* Loop over section headers */
for (i = 0; i < shnum; i++) {
uint32_t sh_type, sh_flags;
if (fmap_readn(map, &section_hdr[i], shoff, sizeof(struct elf_section_hdr32)) != sizeof(struct elf_section_hdr32)) {
cli_dbgmsg("ELF: Can't read section header\n");
if (ctx) {
cli_dbgmsg("ELF: Possibly broken ELF file\n");
}
free(section_hdr);
if (ctx && SCAN_HEURISTIC_BROKEN && (CL_VIRUS == cli_append_virus(ctx, "Heuristics.Broken.Executable"))) {
return CL_VIRUS;
}
return CL_BREAK;
}
shoff += sizeof(struct elf_section_hdr32);
if (elfinfo) {
elfinfo->sections[i].rva = EC32(section_hdr[i].sh_addr, conv);
elfinfo->sections[i].raw = EC32(section_hdr[i].sh_offset, conv);
elfinfo->sections[i].rsz = EC32(section_hdr[i].sh_size, conv);
}
if (ctx) {
cli_dbgmsg("ELF: Section %u\n", i);
cli_dbgmsg("ELF: Section offset: %u\n", EC32(section_hdr[i].sh_offset, conv));
cli_dbgmsg("ELF: Section size: %u\n", EC32(section_hdr[i].sh_size, conv));
sh_type = EC32(section_hdr[i].sh_type, conv);
sh_flags = EC32(section_hdr[i].sh_flags, conv) & ELF_SHF_MASK;
cli_elf_sectionlog(sh_type, sh_flags);
cli_dbgmsg("------------------------------------\n");
}
}
free(section_hdr);
return CL_CLEAN;
}
/* 64-bit version of section header parsing */
static int cli_elf_sh64(cli_ctx *ctx, fmap_t *map, struct cli_exe_info *elfinfo,
struct elf_file_hdr64 *file_hdr, uint8_t conv)
{
struct elf_section_hdr64 *section_hdr = NULL;
uint16_t shnum, shentsize;
uint32_t i;
uint64_t shoff;
shnum = file_hdr->e_shnum;
cli_dbgmsg("ELF: Number of sections: %d\n", shnum);
if (ctx && (shnum > 2048)) {
cli_dbgmsg("ELF: Number of sections > 2048, skipping\n");
return CL_BREAK;
} else if (elfinfo && (shnum > 256)) {
cli_dbgmsg("ELF: Suspicious number of sections\n");
return CL_BREAK;
}
if (elfinfo) {
elfinfo->nsections = shnum;
}
shentsize = file_hdr->e_shentsize;
/* Sanity check */
if (shentsize != sizeof(struct elf_section_hdr64)) {
cli_dbgmsg("ELF: shentsize != sizeof(struct elf_section_hdr64)\n");
if (ctx && SCAN_HEURISTIC_BROKEN && (CL_VIRUS == cli_append_virus(ctx, "Heuristics.Broken.Executable"))) {
return CL_VIRUS;
}
return CL_EFORMAT;
}
if (elfinfo && !shnum) {
return CL_CLEAN;
}
shoff = file_hdr->e_shoff;
if (ctx)
cli_dbgmsg("ELF: Section header table offset: " STDu64 "\n", shoff);
if (elfinfo) {
elfinfo->sections = (struct cli_exe_section *)cli_calloc(shnum, sizeof(struct cli_exe_section));
if (!elfinfo->sections) {
cli_dbgmsg("ELF: Can't allocate memory for section headers\n");
return CL_EMEM;
}
}
if (shnum) {
section_hdr = (struct elf_section_hdr64 *)cli_calloc(shnum, shentsize);
if (!section_hdr) {
cli_errmsg("ELF: Can't allocate memory for section headers\n");
return CL_EMEM;
}
if (ctx) {
cli_dbgmsg("------------------------------------\n");
}
}
/* Loop over section headers */
for (i = 0; i < shnum; i++) {
uint32_t sh_type, sh_flags;
if (fmap_readn(map, &section_hdr[i], shoff, sizeof(struct elf_section_hdr64)) != sizeof(struct elf_section_hdr64)) {
cli_dbgmsg("ELF: Can't read section header\n");
if (ctx) {
cli_dbgmsg("ELF: Possibly broken ELF file\n");
}
free(section_hdr);
if (ctx && SCAN_HEURISTIC_BROKEN && (CL_VIRUS == cli_append_virus(ctx, "Heuristics.Broken.Executable"))) {
return CL_VIRUS;
}
return CL_BREAK;
}
shoff += sizeof(struct elf_section_hdr64);
if (elfinfo) {
elfinfo->sections[i].rva = EC64(section_hdr[i].sh_addr, conv);
elfinfo->sections[i].raw = EC64(section_hdr[i].sh_offset, conv);
elfinfo->sections[i].rsz = EC64(section_hdr[i].sh_size, conv);
}
if (ctx) {
cli_dbgmsg("ELF: Section " STDu32 "\n", (uint32_t)i);
cli_dbgmsg("ELF: Section offset: " STDu64 "\n", (uint64_t)EC64(section_hdr[i].sh_offset, conv));
cli_dbgmsg("ELF: Section size: " STDu64 "\n", (uint64_t)EC64(section_hdr[i].sh_size, conv));
sh_type = EC32(section_hdr[i].sh_type, conv);
sh_flags = (uint32_t)(EC64(section_hdr[i].sh_flags, conv) & ELF_SHF_MASK);
cli_elf_sectionlog(sh_type, sh_flags);
cli_dbgmsg("------------------------------------\n");
}
}
free(section_hdr);
return CL_CLEAN;
}
/* Print section type and selected flags to the log */
static void cli_elf_sectionlog(uint32_t sh_type, uint32_t sh_flags)
{
switch (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 (sh_flags & ELF_SHF_WRITE)
cli_dbgmsg("ELF: Section contains writable data\n");
if (sh_flags & ELF_SHF_ALLOC)
cli_dbgmsg("ELF: Section occupies memory\n");
if (sh_flags & ELF_SHF_EXECINSTR)
cli_dbgmsg("ELF: Section contains executable code\n");
}
/* Scan function for ELF */
int cli_scanelf(cli_ctx *ctx)
{
union elf_file_hdr file_hdr;
fmap_t *map = ctx->fmap;
int ret;
uint8_t conv = 0, is64 = 0;
cli_dbgmsg("in cli_scanelf\n");
/* Load header to determine size and class */
ret = cli_elf_fileheader(ctx, map, &file_hdr, &conv, &is64);
if (ret == CL_BREAK) {
return CL_CLEAN; /* here, break means "exit but report clean" */
} else if (ret != CL_CLEAN) {
return ret;
}
/* Log File type and machine type */
switch (file_hdr.hdr64.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", file_hdr.hdr64.e_type);
}
switch (file_hdr.hdr64.e_machine) {
/* Due to a huge list, we only include the most popular machines here */
case 0: /* EM_NONE */
cli_dbgmsg("ELF: Machine type: None\n");
break;
case 2: /* EM_SPARC */
cli_dbgmsg("ELF: Machine type: SPARC\n");
break;
case 3: /* EM_386 */
cli_dbgmsg("ELF: Machine type: Intel 80386\n");
break;
case 4: /* EM_68K */
cli_dbgmsg("ELF: Machine type: Motorola 68000\n");
break;
case 8: /* EM_MIPS */
cli_dbgmsg("ELF: Machine type: MIPS RS3000\n");
break;
case 9: /* EM_S370 */
cli_dbgmsg("ELF: Machine type: IBM System/370\n");
break;
case 15: /* EM_PARISC */
cli_dbgmsg("ELF: Machine type: HPPA\n");
break;
case 20: /* EM_PPC */
cli_dbgmsg("ELF: Machine type: PowerPC\n");
break;
case 21: /* EM_PPC64 */
cli_dbgmsg("ELF: Machine type: PowerPC 64-bit\n");
break;
case 22: /* EM_S390 */
cli_dbgmsg("ELF: Machine type: IBM S390\n");
break;
case 40: /* EM_ARM */
cli_dbgmsg("ELF: Machine type: ARM\n");
break;
case 41: /* EM_FAKE_ALPHA */
cli_dbgmsg("ELF: Machine type: Digital Alpha\n");
break;
case 43: /* EM_SPARCV9 */
cli_dbgmsg("ELF: Machine type: SPARC v9 64-bit\n");
break;
case 50: /* EM_IA_64 */
cli_dbgmsg("ELF: Machine type: IA64\n");
break;
case 62: /* EM_X86_64 */
cli_dbgmsg("ELF: Machine type: AMD x86-64\n");
break;
default:
cli_dbgmsg("ELF: Machine type: Unknown (0x%x)\n", file_hdr.hdr64.e_machine);
}
/* Program headers and Entry */
if (is64) {
ret = cli_elf_ph64(ctx, map, NULL, &(file_hdr.hdr64), conv);
} else {
ret = cli_elf_ph32(ctx, map, NULL, &(file_hdr.hdr32.hdr), conv);
}
if (ret == CL_BREAK) {
return CL_CLEAN; /* break means "exit but report clean" */
} else if (ret != CL_CLEAN) {
return ret;
}
/* Sections */
if (is64) {
ret = cli_elf_sh64(ctx, map, NULL, &(file_hdr.hdr64), conv);
} else {
ret = cli_elf_sh32(ctx, map, NULL, &(file_hdr.hdr32.hdr), conv);
}
if (ret == CL_BREAK) {
return CL_CLEAN; /* break means "exit but report clean" */
} else if (ret != CL_CLEAN) {
return ret;
}
return CL_CLEAN;
}
/* ELF header parsing only
* Returns 0 on success, -1 on error
*/
int cli_elfheader(cli_ctx *ctx, struct cli_exe_info *elfinfo)
{
union elf_file_hdr file_hdr;
uint8_t conv = 0, is64 = 0;
int ret;
cli_dbgmsg("in cli_elfheader\n");
// TODO This code assumes elfinfo->offset == 0, which might not always
// be the case. For now just print this debug message and continue on
if (0 != elfinfo->offset) {
cli_dbgmsg("cli_elfheader: Assumption Violated: elfinfo->offset != 0\n");
}
ret = cli_elf_fileheader(NULL, ctx->fmap, &file_hdr, &conv, &is64);
if (ret != CL_CLEAN) {
return -1;
}
/* Program headers and Entry */
if (is64) {
ret = cli_elf_ph64(NULL, ctx->fmap, elfinfo, &(file_hdr.hdr64), conv);
} else {
ret = cli_elf_ph32(NULL, ctx->fmap, elfinfo, &(file_hdr.hdr32.hdr), conv);
}
if (ret != CL_CLEAN) {
return -1;
}
/* Section Headers */
if (is64) {
ret = cli_elf_sh64(NULL, ctx->fmap, elfinfo, &(file_hdr.hdr64), conv);
} else {
ret = cli_elf_sh32(NULL, ctx->fmap, elfinfo, &(file_hdr.hdr32.hdr), conv);
}
if (ret != CL_CLEAN) {
return -1;
}
return 0;
}
/*
* ELF file unpacking.
*/
int cli_unpackelf(cli_ctx *ctx)
{
char *tempfile;
int ndesc;
struct cli_bc_ctx *bc_ctx;
int ret;
fmap_t *map = ctx->fmap;
/* Bytecode BC_ELF_UNPACKER hook */
bc_ctx = cli_bytecode_context_alloc();
if (!bc_ctx) {
cli_errmsg("cli_scanelf: can't allocate memory for bc_ctx\n");
return CL_EMEM;
}
cli_bytecode_context_setctx(bc_ctx, ctx);
cli_dbgmsg("Running bytecode hook\n");
ret = cli_bytecode_runhook(ctx, ctx->engine, bc_ctx, BC_ELF_UNPACKER, map);
cli_dbgmsg("Finished running bytecode hook\n");
switch (ret) {
case CL_VIRUS:
cli_bytecode_context_destroy(bc_ctx);
return CL_VIRUS;
case CL_SUCCESS:
ndesc = cli_bytecode_context_getresult_file(bc_ctx, &tempfile);
cli_bytecode_context_destroy(bc_ctx);
if (ndesc != -1 && tempfile) {
if (ctx->engine->keeptmp)
cli_dbgmsg("cli_scanelf: Unpacked and rebuilt executable saved in %s\n", tempfile);
else
cli_dbgmsg("cli_scanelf: Unpacked and rebuilt executable\n");
lseek(ndesc, 0, SEEK_SET);
cli_dbgmsg("***** Scanning rebuilt ELF file *****\n");
if (cli_magic_scan_desc(ndesc, tempfile, ctx, NULL) == CL_VIRUS) {
close(ndesc);
CLI_TMPUNLK();
free(tempfile);
return CL_VIRUS;
}
close(ndesc);
CLI_TMPUNLK();
free(tempfile);
return CL_CLEAN;
}
break;
default:
cli_bytecode_context_destroy(bc_ctx);
}
return CL_CLEAN;
}
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