saad/minimal-linux-script
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity
minimal-linux-script/syslinux-6.03/efi/wrapper.c
aimran96 ad93368a73 add build files
2023-11-16 23:19:36 -05:00

294 lines
8.0 KiB
C
Raw Permalink Blame History

/*
* Copyright (C) 2011 Intel Corporation; author Matt Fleming
*
* Wrap the ELF shared library in a PE32 (32bit) or PE32+ (64bit) suit.
*
* Syslinux plays some games with the ELF sections that are not easily
* converted to a PE32 executable. For instance, Syslinux requires
* that a symbol hash table be present (GNU hash or SysV) so that
* symbols in ELF modules can be resolved at runtime but the EFI
* firmware loader doesn't like that and refuses to load the file.
*
* We pretend that we have an EFI executable with a single .text
* section so that the EFI loader will load it and jump to the entry
* point. Once the Syslinux ELF shared object has control we can do
* whatever we want.
*/
#include <linux/elf.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "wrapper.h"
#if __SIZEOF_POINTER__ == 4
typedef Elf32_Ehdr Elf_Ehdr;
typedef Elf32_Addr Elf_Addr;
#elif __SIZEOF_POINTER__ == 8
typedef Elf64_Ehdr Elf_Ehdr;
typedef Elf64_Addr Elf_Addr;
#else
#error "unsupported architecture"
#endif
/*
* 'so_memsz' is the size of the ELF shared object once loaded.
* 'data_size' is the size of initialised data in the shared object.
* 'class' dictates how the header is written
* For 32bit machines (class == ELFCLASS32), the optional
* header includes PE32 header fields
* For 64bit machines (class == ELFCLASS64), the optional
* header includes PE32+header fields
*/
static void write_header(FILE *f, __uint32_t entry, size_t data_size,
__uint32_t so_memsz, __uint8_t class)
{
struct optional_hdr o_hdr;
struct optional_hdr_pe32p o_hdr_pe32p;
struct section t_sec;
struct extra_hdr e_hdr;
struct extra_hdr_pe32p e_hdr_pe32p;
struct coff_hdr c_hdr;
struct header hdr;
__uint32_t total_sz = data_size;
__uint32_t hdr_sz;
__uint32_t reloc_start, reloc_end;
/*
* The header size have to be a multiple of file_align, which currently
* is 512
*/
hdr_sz = 512;
total_sz += hdr_sz;
entry += hdr_sz;
memset(&hdr, 0, sizeof(hdr));
hdr.msdos_signature = MSDOS_SIGNATURE;
/*
* The relocs table pointer needs to be >= 0x40 for PE files. It
* informs things like file(1) that we are not an MS-DOS
* executable.
*/
hdr.relocs_ptr = 0x40;
hdr.pe_hdr = OFFSETOF(struct header, pe_signature);
hdr.pe_signature = PE_SIGNATURE;
fwrite(&hdr, sizeof(hdr), 1, f);
memset(&c_hdr, 0, sizeof(c_hdr));
c_hdr.nr_sections = 1;
c_hdr.nr_syms = 1;
if (class == ELFCLASS32) {
c_hdr.arch = IMAGE_FILE_MACHINE_I386;
c_hdr.characteristics = IMAGE_FILE_32BIT_MACHINE |
IMAGE_FILE_DEBUG_STRIPPED | IMAGE_FILE_EXECUTABLE_IMAGE |
IMAGE_FILE_LINE_NUMBERS_STRIPPED;
c_hdr.optional_hdr_sz = sizeof(o_hdr) + sizeof(e_hdr);
fwrite(&c_hdr, sizeof(c_hdr), 1, f);
memset(&o_hdr, 0, sizeof(o_hdr));
o_hdr.format = PE32_FORMAT;
o_hdr.major_linker_version = 0x02;
o_hdr.minor_linker_version = 0x14;
o_hdr.code_sz = data_size;
o_hdr.entry_point = entry;
o_hdr.initialized_data_sz = data_size;
fwrite(&o_hdr, sizeof(o_hdr), 1, f);
memset(&e_hdr, 0, sizeof(e_hdr));
e_hdr.section_align = 4096;
e_hdr.file_align = 512;
e_hdr.image_sz = hdr_sz + so_memsz;
e_hdr.headers_sz = hdr_sz;
e_hdr.subsystem = IMAGE_SUBSYSTEM_EFI_APPLICATION;
e_hdr.rva_and_sizes_nr = sizeof(e_hdr.data_directory) / sizeof(__uint64_t);
fwrite(&e_hdr, sizeof(e_hdr), 1, f);
}
else if (class == ELFCLASS64) {
c_hdr.arch = IMAGE_FILE_MACHINE_X86_64;
c_hdr.characteristics = IMAGE_FILE_DEBUG_STRIPPED | IMAGE_FILE_EXECUTABLE_IMAGE |
IMAGE_FILE_LINE_NUMBERS_STRIPPED;
c_hdr.optional_hdr_sz = sizeof(o_hdr_pe32p) + sizeof(e_hdr_pe32p);
fwrite(&c_hdr, sizeof(c_hdr), 1, f);
memset(&o_hdr_pe32p, 0, sizeof(o_hdr_pe32p));
o_hdr_pe32p.format = PE32P_FORMAT;
o_hdr_pe32p.major_linker_version = 0x02;
o_hdr_pe32p.minor_linker_version = 0x14;
o_hdr_pe32p.code_sz = data_size;
o_hdr_pe32p.entry_point = entry;
o_hdr.initialized_data_sz = data_size;
fwrite(&o_hdr_pe32p, sizeof(o_hdr_pe32p), 1, f);
memset(&e_hdr_pe32p, 0, sizeof(e_hdr_pe32p));
e_hdr_pe32p.section_align = 4096;
e_hdr_pe32p.file_align = 512;
e_hdr_pe32p.image_sz = hdr_sz + so_memsz;
e_hdr_pe32p.headers_sz = hdr_sz;
e_hdr_pe32p.subsystem = IMAGE_SUBSYSTEM_EFI_APPLICATION;
e_hdr_pe32p.rva_and_sizes_nr = sizeof(e_hdr_pe32p.data_directory) / sizeof(__uint64_t);
fwrite(&e_hdr_pe32p, sizeof(e_hdr_pe32p), 1, f);
}
memset(&t_sec, 0, sizeof(t_sec));
strcpy((char *)t_sec.name, ".text");
t_sec.virtual_sz = data_size;
t_sec.virtual_address = hdr_sz;
t_sec.raw_data_sz = t_sec.virtual_sz;
t_sec.raw_data = t_sec.virtual_address;
t_sec.characteristics = IMAGE_SCN_CNT_CODE |
IMAGE_SCN_ALIGN_16BYTES | IMAGE_SCN_MEM_EXECUTE |
IMAGE_SCN_MEM_READ;
fwrite(&t_sec, sizeof(t_sec), 1, f);
/*
* Add some padding to align the ELF as needed
*/
if (ftell(f) > t_sec.virtual_address) {
/* Don't rewind! hdr_sz need to be increased. */
fprintf(stderr, "PE32+ headers are too large.\n");
exit(EXIT_FAILURE);
}
fseek(f, t_sec.virtual_address, SEEK_SET);
}
static void usage(char *progname)
{
fprintf(stderr, "usage: %s <ELF shared object> <output file>\n",
progname);
}
int main(int argc, char **argv)
{
Elf32_Ehdr e32_hdr;
Elf64_Ehdr e64_hdr;
__uint32_t entry;
__uint8_t class;
__uint64_t phoff = 0;
__uint16_t phnum = 0, phentsize = 0;
unsigned char *id;
FILE *f_in, *f_out;
void *buf;
size_t datasz, memsz, rv;
if (argc < 3) {
usage(argv[0]);
exit(0);
}
f_in = fopen(argv[1], "r");
if (!f_in) {
perror("fopen");
exit(EXIT_FAILURE);
}
f_out = fopen(argv[2], "w");
if (!f_out) {
perror("fopen");
exit(EXIT_FAILURE);
}
/*
* Parse the ELF header and find the entry point.
*/
fread((void *)&e32_hdr, sizeof(e32_hdr), 1, f_in);
if (e32_hdr.e_ident[EI_CLASS] == ELFCLASS32) {
id = e32_hdr.e_ident;
class = ELFCLASS32;
entry = e32_hdr.e_entry;
phoff = e32_hdr.e_phoff;
phnum = e32_hdr.e_phnum;
phentsize = e32_hdr.e_phentsize;
}
else if (e32_hdr.e_ident[EI_CLASS] == ELFCLASS64) {
/* read the header again for x86_64
* note that the elf header entry point is 64bit whereas
* the entry point in PE/COFF format is 32bit!*/
class = ELFCLASS64;
rewind(f_in);
fread((void *)&e64_hdr, sizeof(e64_hdr), 1, f_in);
id = e64_hdr.e_ident;
entry = e64_hdr.e_entry;
phoff = e64_hdr.e_phoff;
phnum = e64_hdr.e_phnum;
phentsize = e64_hdr.e_phentsize;
} else {
fprintf(stderr, "Unsupported architecture\n");
exit(EXIT_FAILURE);
}
if (id[EI_MAG0] != ELFMAG0 ||
id[EI_MAG1] != ELFMAG1 ||
id[EI_MAG2] != ELFMAG2 ||
id[EI_MAG3] != ELFMAG3) {
fprintf(stderr, "Input file not ELF shared object\n");
exit(EXIT_FAILURE);
}
if (!phoff || !phnum) {
fprintf(stderr, "Cannot find segment table\n");
exit(EXIT_FAILURE);
}
/*
* Find the LOAD program header. Everything in this segment
* is copied verbatim to the output file.
* Although there may be several LOAD program headers, only
* one is currently copied.
*/
if (e32_hdr.e_ident[EI_CLASS] == ELFCLASS32) {
Elf32_Phdr phdr;
int i;
/* Find the first LOAD program header */
for (i = 0; i < phnum; i++) {
fseek(f_in, phoff + i * phentsize, SEEK_SET);
fread(&phdr, sizeof(phdr), 1, f_in);
if (phdr.p_type == PT_LOAD)
break;
}
datasz = phdr.p_filesz;
memsz = phdr.p_memsz;
} else if (e32_hdr.e_ident[EI_CLASS] == ELFCLASS64) {
Elf64_Phdr phdr;
int i;
/* Find the first LOAD program header */
for (i = 0; i < phnum; i++) {
fseek(f_in, phoff + i * phentsize, SEEK_SET);
fread(&phdr, sizeof(phdr), 1, f_in);
if (phdr.p_type == PT_LOAD)
break;
}
datasz = phdr.p_filesz;
memsz = phdr.p_memsz;
}
buf = malloc(datasz);
if (!buf) {
perror("malloc");
exit(EXIT_FAILURE);
}
write_header(f_out, entry, datasz, memsz, class);
/* Write out the entire ELF shared object */
rewind(f_in);
rv = fread(buf, datasz, 1, f_in);
if (!rv && ferror(f_in)) {
fprintf(stderr, "Failed to read all bytes from input\n");
exit(EXIT_FAILURE);
}
fwrite(buf, datasz, rv, f_out);
free(buf);
fclose(f_out);
fclose(f_in);
return 0;
}
Reference in New Issue View Git Blame Copy Permalink