linux/scripts/elf-parse.c at master · rdpwr/linux · GitHub

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#include <sys/types.h>

#include <sys/mman.h>

#include <sys/stat.h>

#include <fcntl.h>

#include <stdio.h>

#include <stdlib.h>

#include <stdbool.h>

#include <string.h>

#include <unistd.h>

#include <errno.h>

#include "elf-parse.h"

struct elf_funcs elf_parser;

* Get the whole file as a programming convenience in order to avoid

* malloc+lseek+read+free of many pieces. If successful, then mmap

* avoids copying unused pieces; else just read the whole file.

* Open for both read and write.

static void *map_file(char const *fname, size_t *size)

{

int fd;

struct stat sb;

void *addr = NULL;

fd = open(fname, O_RDWR);

if (fd < 0) {

perror(fname);

return NULL;

}

if (fstat(fd, &sb) < 0) {

perror(fname);

goto out;

}

if (!S_ISREG(sb.st_mode)) {

fprintf(stderr, "not a regular file: %s\n", fname);

goto out;

}

addr = mmap(0, sb.st_size, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);

if (addr == MAP_FAILED) {

fprintf(stderr, "Could not mmap file: %s\n", fname);

goto out;

}

*size = sb.st_size;

out:

close(fd);

return addr;

}

static int elf_parse(const char *fname, void *addr, uint32_t types)

{

Elf_Ehdr *ehdr = addr;

uint16_t type;

switch (ehdr->e32.e_ident[EI_DATA]) {

case ELFDATA2LSB:

elf_parser.r = rle;

elf_parser.r2 = r2le;

elf_parser.r8 = r8le;

elf_parser.w = wle;

elf_parser.w8 = w8le;

break;

case ELFDATA2MSB:

elf_parser.r = rbe;

elf_parser.r2 = r2be;

elf_parser.r8 = r8be;

elf_parser.w = wbe;

elf_parser.w8 = w8be;

break;

default:

fprintf(stderr, "unrecognized ELF data encoding %d: %s\n",

ehdr->e32.e_ident[EI_DATA], fname);

return -1;

}

if (memcmp(ELFMAG, ehdr->e32.e_ident, SELFMAG) != 0 ||

ehdr->e32.e_ident[EI_VERSION] != EV_CURRENT) {

fprintf(stderr, "unrecognized ELF file %s\n", fname);

return -1;

}

type = elf_parser.r2(&ehdr->e32.e_type);

if (!((1 << type) & types)) {

fprintf(stderr, "Invalid ELF type file %s\n", fname);

return -1;

}

switch (ehdr->e32.e_ident[EI_CLASS]) {

case ELFCLASS32: {

elf_parser.ehdr_shoff = ehdr32_shoff;

elf_parser.ehdr_shentsize = ehdr32_shentsize;

elf_parser.ehdr_shstrndx = ehdr32_shstrndx;

elf_parser.ehdr_shnum = ehdr32_shnum;

elf_parser.shdr_addr = shdr32_addr;

elf_parser.shdr_offset = shdr32_offset;

elf_parser.shdr_link = shdr32_link;

elf_parser.shdr_size = shdr32_size;

elf_parser.shdr_name = shdr32_name;

elf_parser.shdr_type = shdr32_type;

elf_parser.shdr_entsize = shdr32_entsize;

elf_parser.sym_type = sym32_type;

elf_parser.sym_name = sym32_name;

elf_parser.sym_value = sym32_value;

elf_parser.sym_shndx = sym32_shndx;

elf_parser.rela_offset = rela32_offset;

elf_parser.rela_info = rela32_info;

elf_parser.rela_addend = rela32_addend;

elf_parser.rela_write_addend = rela32_write_addend;

if (elf_parser.r2(&ehdr->e32.e_ehsize) != sizeof(Elf32_Ehdr) ||

elf_parser.r2(&ehdr->e32.e_shentsize) != sizeof(Elf32_Shdr)) {

fprintf(stderr,

"unrecognized ET_EXEC/ET_DYN file: %s\n", fname);

return -1;

}

break;

case ELFCLASS64: {

elf_parser.ehdr_shoff = ehdr64_shoff;

elf_parser.ehdr_shentsize = ehdr64_shentsize;

elf_parser.ehdr_shstrndx = ehdr64_shstrndx;

elf_parser.ehdr_shnum = ehdr64_shnum;

elf_parser.shdr_addr = shdr64_addr;

elf_parser.shdr_offset = shdr64_offset;

elf_parser.shdr_link = shdr64_link;

elf_parser.shdr_size = shdr64_size;

elf_parser.shdr_name = shdr64_name;

elf_parser.shdr_type = shdr64_type;

elf_parser.shdr_entsize = shdr64_entsize;

elf_parser.sym_type = sym64_type;

elf_parser.sym_name = sym64_name;

elf_parser.sym_value = sym64_value;

elf_parser.sym_shndx = sym64_shndx;

elf_parser.rela_offset = rela64_offset;

elf_parser.rela_info = rela64_info;

elf_parser.rela_addend = rela64_addend;

elf_parser.rela_write_addend = rela64_write_addend;

if (elf_parser.r2(&ehdr->e64.e_ehsize) != sizeof(Elf64_Ehdr) ||

elf_parser.r2(&ehdr->e64.e_shentsize) != sizeof(Elf64_Shdr)) {

fprintf(stderr,

"unrecognized ET_EXEC/ET_DYN file: %s\n",

fname);

return -1;

}

break;

default:

fprintf(stderr, "unrecognized ELF class %d %s\n",

ehdr->e32.e_ident[EI_CLASS], fname);

return -1;

}

return 0;

}

int elf_map_machine(void *addr)

{

Elf_Ehdr *ehdr = addr;

return elf_parser.r2(&ehdr->e32.e_machine);

}

int elf_map_long_size(void *addr)

{

Elf_Ehdr *ehdr = addr;

return ehdr->e32.e_ident[EI_CLASS] == ELFCLASS32 ? 4 : 8;

}

void *elf_map(char const *fname, size_t *size, uint32_t types)

{

void *addr;

int ret;

addr = map_file(fname, size);

if (!addr)

return NULL;

ret = elf_parse(fname, addr, types);

if (ret < 0) {

elf_unmap(addr, *size);

return NULL;

}

return addr;

}

void elf_unmap(void *addr, size_t size)

{

munmap(addr, size);

}

linux/scripts/elf-parse.c at master · rdpwr/linux · GitHub

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