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/*
* Copyright (C) 2016 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include <errno.h>
#include <fcntl.h>
#include <sys/mman.h>
#include <sys/ptrace.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/uio.h>
#include <unistd.h>
#include <algorithm>
#include <memory>
#include <android-base/unique_fd.h>
#include "Memory.h"
bool Memory::ReadString(uint64_t addr, std::string* string, uint64_t max_read) {
string->clear();
uint64_t bytes_read = 0;
while (bytes_read < max_read) {
uint8_t value;
if (!Read(addr, &value, sizeof(value))) {
return false;
}
if (value == '\0') {
return true;
}
string->push_back(value);
addr++;
bytes_read++;
}
return false;
}
bool MemoryBuffer::Read(uint64_t addr, void* dst, size_t size) {
uint64_t last_read_byte;
if (__builtin_add_overflow(size, addr, &last_read_byte)) {
return false;
}
if (last_read_byte > raw_.size()) {
return false;
}
memcpy(dst, &raw_[addr], size);
return true;
}
uint8_t* MemoryBuffer::GetPtr(size_t offset) {
if (offset < raw_.size()) {
return &raw_[offset];
}
return nullptr;
}
MemoryFileAtOffset::~MemoryFileAtOffset() {
Clear();
}
void MemoryFileAtOffset::Clear() {
if (data_) {
munmap(&data_[-offset_], size_ + offset_);
data_ = nullptr;
}
}
bool MemoryFileAtOffset::Init(const std::string& file, uint64_t offset, uint64_t size) {
// Clear out any previous data if it exists.
Clear();
android::base::unique_fd fd(TEMP_FAILURE_RETRY(open(file.c_str(), O_RDONLY | O_CLOEXEC)));
if (fd == -1) {
return false;
}
struct stat buf;
if (fstat(fd, &buf) == -1) {
return false;
}
if (offset >= static_cast<uint64_t>(buf.st_size)) {
return false;
}
offset_ = offset & (getpagesize() - 1);
uint64_t aligned_offset = offset & ~(getpagesize() - 1);
size_ = buf.st_size - aligned_offset;
if (size < (UINT64_MAX - offset_) && size + offset_ < size_) {
// Truncate the mapped size.
size_ = size + offset_;
}
void* map = mmap(nullptr, size_, PROT_READ, MAP_PRIVATE, fd, aligned_offset);
if (map == MAP_FAILED) {
return false;
}
data_ = &reinterpret_cast<uint8_t*>(map)[offset_];
size_ -= offset_;
return true;
}
bool MemoryFileAtOffset::Read(uint64_t addr, void* dst, size_t size) {
if (addr + size > size_) {
return false;
}
memcpy(dst, &data_[addr], size);
return true;
}
static bool PtraceRead(pid_t pid, uint64_t addr, long* value) {
#if !defined(__LP64__)
// Cannot read an address greater than 32 bits.
if (addr > UINT32_MAX) {
return false;
}
#endif
// ptrace() returns -1 and sets errno when the operation fails.
// To disambiguate -1 from a valid result, we clear errno beforehand.
errno = 0;
*value = ptrace(PTRACE_PEEKTEXT, pid, reinterpret_cast<void*>(addr), nullptr);
if (*value == -1 && errno) {
return false;
}
return true;
}
bool MemoryRemote::Read(uint64_t addr, void* dst, size_t bytes) {
size_t bytes_read = 0;
long data;
size_t align_bytes = addr & (sizeof(long) - 1);
if (align_bytes != 0) {
if (!PtraceRead(pid_, addr & ~(sizeof(long) - 1), &data)) {
return false;
}
size_t copy_bytes = std::min(sizeof(long) - align_bytes, bytes);
memcpy(dst, reinterpret_cast<uint8_t*>(&data) + align_bytes, copy_bytes);
addr += copy_bytes;
dst = reinterpret_cast<void*>(reinterpret_cast<uintptr_t>(dst) + copy_bytes);
bytes -= copy_bytes;
bytes_read += copy_bytes;
}
for (size_t i = 0; i < bytes / sizeof(long); i++) {
if (!PtraceRead(pid_, addr, &data)) {
return false;
}
memcpy(dst, &data, sizeof(long));
dst = reinterpret_cast<void*>(reinterpret_cast<uintptr_t>(dst) + sizeof(long));
addr += sizeof(long);
bytes_read += sizeof(long);
}
size_t left_over = bytes & (sizeof(long) - 1);
if (left_over) {
if (!PtraceRead(pid_, addr, &data)) {
return false;
}
memcpy(dst, &data, left_over);
bytes_read += left_over;
}
return true;
}
bool MemoryLocal::Read(uint64_t addr, void* dst, size_t size) {
// The process_vm_readv call does will not always work on remote
// processes, so only use it for reads from the current pid.
// Use this method to avoid crashes if an address is invalid since
// unwind data could try to access any part of the address space.
struct iovec local_io;
local_io.iov_base = dst;
local_io.iov_len = size;
struct iovec remote_io;
remote_io.iov_base = reinterpret_cast<void*>(static_cast<uintptr_t>(addr));
remote_io.iov_len = size;
ssize_t bytes_read = process_vm_readv(getpid(), &local_io, 1, &remote_io, 1, 0);
if (bytes_read == -1) {
return false;
}
return static_cast<size_t>(bytes_read) == size;
}
bool MemoryOffline::Init(const std::string& file, uint64_t offset) {
if (!MemoryFileAtOffset::Init(file, offset)) {
return false;
}
// The first uint64_t value is the start of memory.
if (!MemoryFileAtOffset::Read(0, &start_, sizeof(start_))) {
return false;
}
// Subtract the first 64 bit value from the total size.
size_ -= sizeof(start_);
return true;
}
bool MemoryOffline::Read(uint64_t addr, void* dst, size_t size) {
if (addr < start_ || addr + size > start_ + offset_ + size_) {
return false;
}
memcpy(dst, &data_[addr + offset_ - start_ + sizeof(start_)], size);
return true;
}
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