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add: maps hiding (#13)

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This commit adds maps hiding. This commit is taken from Reveny's PR, for more information, see #9.

solves #9
This commit is contained in:
Pedro.js
2024-06-26 19:38:34 -03:00
committed by GitHub
parent 4aa8b2f828
commit af96b85a91
6 changed files with 563 additions and 7 deletions
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235
loader/src/common/elf_util.cpp Normal file
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@@ -0,0 +1,235 @@
/*
* This file is part of LSPosed.
*
* LSPosed is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* LSPosed 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 LSPosed. If not, see <https://www.gnu.org/licenses/>.
*
* Copyright (C) 2019 Swift Gan
* Copyright (C) 2021 LSPosed Contributors
*/
#include <malloc.h>
#include <cstring>
#include <sys/mman.h>
#include <fcntl.h>
#include <unistd.h>
#include <cassert>
#include <sys/stat.h>
#include "elf_util.h"
using namespace SandHook;
template<typename T>
inline constexpr auto offsetOf(ElfW(Ehdr) *head, ElfW(Off) off) {
return reinterpret_cast<std::conditional_t<std::is_pointer_v<T>, T, T *>>(
reinterpret_cast<uintptr_t>(head) + off);
}
ElfImg::ElfImg(std::string_view base_name) : elf(base_name) {
if (!findModuleBase()) {
base = nullptr;
return;
}
//load elf
int fd = open(elf.data(), O_RDONLY);
if (fd < 0) {
// LOGE("failed to open %s", elf.data());
return;
}
size = lseek(fd, 0, SEEK_END);
if (size <= 0) {
// LOGE("lseek() failed for %s", elf.data());
}
header = reinterpret_cast<decltype(header)>(mmap(nullptr, size, PROT_READ, MAP_SHARED, fd, 0));
close(fd);
section_header = offsetOf<decltype(section_header)>(header, header->e_shoff);
auto shoff = reinterpret_cast<uintptr_t>(section_header);
char *section_str = offsetOf<char *>(header, section_header[header->e_shstrndx].sh_offset);
for (int i = 0; i < header->e_shnum; i++, shoff += header->e_shentsize) {
auto *section_h = (ElfW(Shdr) *) shoff;
char *sname = section_h->sh_name + section_str;
auto entsize = section_h->sh_entsize;
switch (section_h->sh_type) {
case SHT_DYNSYM: {
if (bias == -4396) {
dynsym = section_h;
dynsym_offset = section_h->sh_offset;
dynsym_start = offsetOf<decltype(dynsym_start)>(header, dynsym_offset);
}
break;
}
case SHT_SYMTAB: {
if (strcmp(sname, ".symtab") == 0) {
symtab = section_h;
symtab_offset = section_h->sh_offset;
symtab_size = section_h->sh_size;
symtab_count = symtab_size / entsize;
symtab_start = offsetOf<decltype(symtab_start)>(header, symtab_offset);
}
break;
}
case SHT_STRTAB: {
if (bias == -4396) {
strtab = section_h;
symstr_offset = section_h->sh_offset;
strtab_start = offsetOf<decltype(strtab_start)>(header, symstr_offset);
}
if (strcmp(sname, ".strtab") == 0) {
symstr_offset_for_symtab = section_h->sh_offset;
}
break;
}
case SHT_PROGBITS: {
if (strtab == nullptr || dynsym == nullptr) break;
if (bias == -4396) {
bias = (off_t) section_h->sh_addr - (off_t) section_h->sh_offset;
}
break;
}
case SHT_HASH: {
auto *d_un = offsetOf<ElfW(Word)>(header, section_h->sh_offset);
nbucket_ = d_un[0];
bucket_ = d_un + 2;
chain_ = bucket_ + nbucket_;
break;
}
case SHT_GNU_HASH: {
auto *d_buf = reinterpret_cast<ElfW(Word) *>(((size_t) header) +
section_h->sh_offset);
gnu_nbucket_ = d_buf[0];
gnu_symndx_ = d_buf[1];
gnu_bloom_size_ = d_buf[2];
gnu_shift2_ = d_buf[3];
gnu_bloom_filter_ = reinterpret_cast<decltype(gnu_bloom_filter_)>(d_buf + 4);
gnu_bucket_ = reinterpret_cast<decltype(gnu_bucket_)>(gnu_bloom_filter_ +
gnu_bloom_size_);
gnu_chain_ = gnu_bucket_ + gnu_nbucket_ - gnu_symndx_;
break;
}
}
}
}
ElfW(Addr) ElfImg::ElfLookup(std::string_view name, uint32_t hash) const {
if (nbucket_ == 0) return 0;
char *strings = (char *) strtab_start;
for (auto n = bucket_[hash % nbucket_]; n != 0; n = chain_[n]) {
auto *sym = dynsym_start + n;
if (name == strings + sym->st_name) {
return sym->st_value;
}
}
return 0;
}
ElfW(Addr) ElfImg::GnuLookup(std::string_view name, uint32_t hash) const {
static constexpr auto bloom_mask_bits = sizeof(ElfW(Addr)) * 8;
if (gnu_nbucket_ == 0 || gnu_bloom_size_ == 0) return 0;
auto bloom_word = gnu_bloom_filter_[(hash / bloom_mask_bits) % gnu_bloom_size_];
uintptr_t mask = 0
| (uintptr_t) 1 << (hash % bloom_mask_bits)
| (uintptr_t) 1 << ((hash >> gnu_shift2_) % bloom_mask_bits);
if ((mask & bloom_word) == mask) {
auto sym_index = gnu_bucket_[hash % gnu_nbucket_];
if (sym_index >= gnu_symndx_) {
char *strings = (char *) strtab_start;
do {
auto *sym = dynsym_start + sym_index;
if (((gnu_chain_[sym_index] ^ hash) >> 1) == 0
&& name == strings + sym->st_name) {
return sym->st_value;
}
} while ((gnu_chain_[sym_index++] & 1) == 0);
}
}
return 0;
}
ElfW(Addr) ElfImg::LinearLookup(std::string_view name) const {
if (symtabs_.empty()) {
symtabs_.reserve(symtab_count);
if (symtab_start != nullptr && symstr_offset_for_symtab != 0) {
for (ElfW(Off) i = 0; i < symtab_count; i++) {
unsigned int st_type = ELF_ST_TYPE(symtab_start[i].st_info);
const char *st_name = offsetOf<const char *>(header, symstr_offset_for_symtab +
symtab_start[i].st_name);
if ((st_type == STT_FUNC || st_type == STT_OBJECT) && symtab_start[i].st_size) {
symtabs_.emplace(st_name, &symtab_start[i]);
}
}
}
}
if (auto i = symtabs_.find(name); i != symtabs_.end()) {
return i->second->st_value;
} else {
return 0;
}
}
ElfImg::~ElfImg() {
//open elf file local
if (buffer) {
free(buffer);
buffer = nullptr;
}
//use mmap
if (header) {
munmap(header, size);
}
}
ElfW(Addr) ElfImg::getSymbOffset(std::string_view name, uint32_t gnu_hash, uint32_t elf_hash) const {
if (auto offset = GnuLookup(name, gnu_hash); offset > 0) {
// LOGD("found %s %p in %s in dynsym by gnuhash", name.data(), reinterpret_cast<void *>(offset), elf.data());
return offset;
} else if (offset = ElfLookup(name, elf_hash); offset > 0) {
// LOGD("found %s %p in %s in dynsym by elfhash", name.data(), reinterpret_cast<void *>(offset), elf.data());
return offset;
} else if (offset = LinearLookup(name); offset > 0) {
// LOGD("found %s %p in %s in symtab by linear lookup", name.data(), reinterpret_cast<void *>(offset), elf.data());
return offset;
} else {
return 0;
}
}
bool ElfImg::findModuleBase() {
dl_iterate_phdr([](struct dl_phdr_info *info, size_t size, void *data) -> int {
(void) size;
if ((info)->dlpi_name == nullptr) {
return 0;
}
auto *self = reinterpret_cast<ElfImg *>(data);
if (strstr(info->dlpi_name, self->elf.data())) {
self->elf = info->dlpi_name;
self->base = reinterpret_cast<void *>(info->dlpi_addr);
return 1;
}
return 0;
}, this);
return base != 0;
}