首先完成此: objcopy把--writable文本--set-section-flags .text = CONTENTS,ALLOC,LOAD,CODE
然後objdump -x或readelf -a查看通常在程序頭後的加載段表。請參閱ELF的手冊頁。對於32位可執行文件,例如:
用hexedit打開二進制文件並查看文件偏移量0x1C(通常爲0x34)處的值,然後遍歷0x20字節結構(文件偏移量爲0x2a處列出的大小),直到找到在前面轉儲中標識爲包含.text部分的那個。倒數第二個值爲00000005(05 00 00 00),需要添加寫入00000007(07 00 00 00)。現在它將按預期工作,沒有任何限制,例如與-Wl,omagic共享庫問題。有點技術性,但需要幾秒鐘的時間。
無論如何,這一位標誌已經造成了無數的問題,沒有任何解釋澄清了這一點,使它能夠完美地工作。
A碼的解決方案可以與GCC輕易地編譯,如果經常做它做這很可能是更容易的改變和更好的解決方案:
#include <stdlib.h>
#include <stdio.h>
#include <elf.h>
int main(int argc, char** argv)
{
if (argc <= 1) return -1;
FILE* fp = fopen(argv[1], "r+");
Elf64_Ehdr teh;
fread(&teh, sizeof(teh), 1, fp);
fseek(fp, 0, SEEK_SET);
if (teh.e_ident[EI_CLASS] == ELFCLASS64) {
Elf64_Ehdr eh;
fread(&eh, sizeof(eh), 1, fp);
Elf64_Phdr* ph = malloc(eh.e_phnum * eh.e_phentsize);
Elf64_Shdr* sh = malloc(eh.e_shnum * eh.e_shentsize);
fseek(fp, eh.e_phoff, SEEK_SET);
fread(ph, eh.e_phentsize, eh.e_phnum, fp);
fseek(fp, eh.e_shoff, SEEK_SET);
fread(sh, eh.e_shentsize, eh.e_shnum, fp);
for (int i = 0; i < eh.e_phnum; i++) {
if (ph[i].p_vaddr <= eh.e_entry && ph[i].p_vaddr + ph[i].p_memsz > eh.e_entry) {
fseek(fp, eh.e_phoff + i * eh.e_phentsize + (unsigned int)&((Elf64_Phdr*)0)->p_flags, SEEK_SET);
ph[i].p_flags |= PF_W;
fwrite(&ph[i].p_flags, sizeof(ph[i].p_flags), 1, fp);
}
}
for (int i = 0; i < eh.e_shnum; i++) {
if (sh[i].sh_addr <= eh.e_entry && sh[i].sh_addr + sh[i].sh_size > eh.e_entry) {
fseek(fp, eh.e_shoff + i * eh.e_shentsize + (unsigned int)&((Elf64_Shdr*)0)->sh_flags, SEEK_SET);
sh[i].sh_flags |= SHF_WRITE;
fwrite(&sh[i].sh_flags, sizeof(sh[i].sh_flags), 1, fp);
}
}
free(ph);
free(sh);
} else {
Elf32_Ehdr eh;
fread(&eh, sizeof(eh), 1, fp);
Elf32_Phdr* ph = malloc(eh.e_phnum * eh.e_phentsize);
Elf32_Shdr* sh = malloc(eh.e_shnum * eh.e_shentsize);
fseek(fp, eh.e_phoff, SEEK_SET);
fread(ph, eh.e_phentsize, eh.e_phnum, fp);
fseek(fp, eh.e_shoff, SEEK_SET);
fread(sh, eh.e_shentsize, eh.e_shnum, fp);
for (int i = 0; i < eh.e_phnum; i++) {
if (ph[i].p_vaddr <= eh.e_entry && ph[i].p_vaddr + ph[i].p_memsz > eh.e_entry) {
fseek(fp, eh.e_phoff + i * eh.e_phentsize + (unsigned int)&((Elf32_Phdr*)0)->p_flags, SEEK_SET);
ph[i].p_flags |= PF_W;
fwrite(&ph[i].p_flags, sizeof(ph[i].p_flags), 1, fp);
}
}
for (int i = 0; i < eh.e_shnum; i++) {
if (sh[i].sh_addr <= eh.e_entry && sh[i].sh_addr + sh[i].sh_size > eh.e_entry) {
fseek(fp, eh.e_shoff + i * eh.e_shentsize + (unsigned int)&((Elf32_Shdr*)0)->sh_flags, SEEK_SET);
sh[i].sh_flags |= SHF_WRITE;
fwrite(&sh[i].sh_flags, sizeof(sh[i].sh_flags), 1, fp);
}
}
free(ph);
free(sh);
}
fflush(fp);
fclose(fp);
return 0;
}