void serialize(std::ofstream &file, char ei_class, char ei_data) { // Readjust code offsets for (std::vector<ElfSection *>::iterator c = code.begin(); c != code.end(); c++) (*c)->getShdr().sh_addr += getAddr(); // Apply relocations for (ElfSection *rel = elf->getSection(1); rel != NULL; rel = rel->getNext()) if ((rel->getType() == SHT_REL) || (rel->getType() == SHT_RELA)) { ElfSection *section = rel->getInfo().section; if ((section->getType() == SHT_PROGBITS) && (section->getFlags() & SHF_EXECINSTR)) { if (rel->getType() == SHT_REL) apply_relocations((ElfRel_Section<Elf_Rel> *)rel, section); else apply_relocations((ElfRel_Section<Elf_Rela> *)rel, section); } } ElfSection::serialize(file, ei_class, ei_data); }
ElfRelHackCode_Section(Elf_Shdr &s, Elf &e) : ElfSection(s, NULL, NULL), parent(e) { std::string file(rundir); init = parent.getDynSection()->getSectionForType(DT_INIT); file += "/inject/"; switch (parent.getMachine()) { case EM_386: file += "x86"; break; case EM_X86_64: file += "x86_64"; break; case EM_ARM: file += "arm"; break; default: throw std::runtime_error("unsupported architecture"); } if (init == NULL) file += "-noinit"; file += ".o"; std::ifstream inject(file.c_str(), std::ios::in|std::ios::binary); elf = new Elf(inject); if (elf->getType() != ET_REL) throw std::runtime_error("object for injected code is not ET_REL"); if (elf->getMachine() != parent.getMachine()) throw std::runtime_error("architecture of object for injected code doesn't match"); ElfSymtab_Section *symtab = NULL; // Get all executable sections from the injected code object. // Most of the time, there will only be one for the init function, // but on e.g. x86, there is a separate section for // __i686.get_pc_thunk.$reg // Find the symbol table at the same time. for (ElfSection *section = elf->getSection(1); section != NULL; section = section->getNext()) { if ((section->getType() == SHT_PROGBITS) && (section->getFlags() & SHF_EXECINSTR)) { code.push_back(section); // We need to align this section depending on the greater // alignment required by code sections. if (shdr.sh_addralign < section->getAddrAlign()) shdr.sh_addralign = section->getAddrAlign(); } else if (section->getType() == SHT_SYMTAB) { symtab = (ElfSymtab_Section *) section; } } assert(code.size() != 0); if (symtab == NULL) throw std::runtime_error("Couldn't find a symbol table for the injected code"); // Find the init symbol entry_point = -1; int shndx = 0; for (std::vector<Elf_SymValue>::iterator sym = symtab->syms.begin(); sym != symtab->syms.end(); sym++) { if (strcmp(sym->name, "init") == 0) { entry_point = sym->value.getValue(); shndx = sym->value.getSection()->getIndex(); break; } } if (entry_point == -1) throw std::runtime_error("Couldn't find an 'init' symbol in the injected code"); // Adjust code sections offsets according to their size std::vector<ElfSection *>::iterator c = code.begin(); (*c)->getShdr().sh_addr = 0; for(ElfSection *last = *(c++); c != code.end(); c++) { unsigned int addr = last->getShdr().sh_addr + last->getSize(); if (addr & ((*c)->getAddrAlign() - 1)) addr = (addr | ((*c)->getAddrAlign() - 1)) + 1; (*c)->getShdr().sh_addr = addr; } shdr.sh_size = code.back()->getAddr() + code.back()->getSize(); data = new char[shdr.sh_size]; char *buf = data; for (c = code.begin(); c != code.end(); c++) { memcpy(buf, (*c)->getData(), (*c)->getSize()); buf += (*c)->getSize(); if ((*c)->getIndex() < shndx) entry_point += (*c)->getSize(); } name = elfhack_text; }