libunwindstack-ndk/Memory.cpp at master · getsentry/libunwindstack-ndk · GitHub

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* 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.

#ifndef SENTRY_ADDED

#ifndef _GNU_SOURCE

# define _GNU_SOURCE 1

#endif

#endif // SENTRY_ADDED

#include <errno.h>

#include <fcntl.h>

#include <stdint.h>

#include <string.h>

#include <sys/mman.h>

#include <sys/ptrace.h>

#include <sys/stat.h>

#include <sys/types.h>

#include <sys/uio.h>

#include <unistd.h>

#ifndef SENTRY_ADDED

#include "unistdfix.h"

#include <sys/syscall.h>

#endif // SENTRY_ADDED

#include <algorithm>

#include <memory>

#include <mutex>

#include <optional>

#include <string>

#include <android-base/unique_fd.h>

#include <unwindstack/Log.h>

#include <unwindstack/Memory.h>

#include "MemoryBuffer.h"

#include "MemoryCache.h"

#include "MemoryFileAtOffset.h"

#include "MemoryLocal.h"

#include "MemoryOffline.h"

#include "MemoryOfflineBuffer.h"

#include "MemoryRange.h"

#include "MemoryRemote.h"

#ifndef SENTRY_ADDED

#if defined(__ANDROID_API__) && __ANDROID_API__ < 23

static ssize_t

process_vm_readv(pid_t __pid, const struct iovec *__local_iov,

unsigned long __local_iov_count, const struct iovec *__remote_iov,

unsigned long __remote_iov_count, unsigned long __flags)

{

return syscall(__NR_process_vm_readv, __pid, __local_iov, __local_iov_count,

__remote_iov, __remote_iov_count, __flags);

}

#endif

#endif // SENTRY_ADDED

namespace unwindstack {

static size_t ProcessVmRead(pid_t pid, uint64_t remote_src, void* dst, size_t len) {

// Split up the remote read across page boundaries.

// From the manpage:

// A partial read/write may result if one of the remote_iov elements points to an invalid

// memory region in the remote process.

// Partial transfers apply at the granularity of iovec elements. These system calls won't

// perform a partial transfer that splits a single iovec element.

constexpr size_t kMaxIovecs = 64;

struct iovec src_iovs[kMaxIovecs];

uint64_t cur = remote_src;

size_t total_read = 0;

while (len > 0) {

struct iovec dst_iov = {

.iov_base = &reinterpret_cast<uint8_t*>(dst)[total_read], .iov_len = len,

};

size_t iovecs_used = 0;

while (len > 0) {

if (iovecs_used == kMaxIovecs) {

break;

}

// struct iovec uses void* for iov_base.

if (cur >= UINTPTR_MAX) {

errno = EFAULT;

return total_read;

}

src_iovs[iovecs_used].iov_base = reinterpret_cast<void*>(cur);

uintptr_t misalignment = cur & (getpagesize() - 1);

size_t iov_len = getpagesize() - misalignment;

iov_len = std::min(iov_len, len);

len -= iov_len;

if (__builtin_add_overflow(cur, iov_len, &cur)) {

errno = EFAULT;

return total_read;

}

src_iovs[iovecs_used].iov_len = iov_len;

++iovecs_used;

}

ssize_t rc = process_vm_readv(pid, &dst_iov, 1, src_iovs, iovecs_used, 0);

if (rc == -1) {

return total_read;

}

total_read += rc;

}

return total_read;

}

static bool PtraceReadLong(pid_t pid, uint64_t addr, long* value) {

// 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;

}

static size_t PtraceRead(pid_t pid, uint64_t addr, void* dst, size_t bytes) {

// Make sure that there is no overflow.

uint64_t max_size;

if (__builtin_add_overflow(addr, bytes, &max_size)) {

return 0;

}

size_t bytes_read = 0;

long data;

size_t align_bytes = addr & (sizeof(long) - 1);

if (align_bytes != 0) {

if (!PtraceReadLong(pid, addr & ~(sizeof(long) - 1), &data)) {

return 0;

}

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 (!PtraceReadLong(pid, addr, &data)) {

return bytes_read;

}

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 (!PtraceReadLong(pid, addr, &data)) {

return bytes_read;

}

memcpy(dst, &data, left_over);

bytes_read += left_over;

}

return bytes_read;

}

bool Memory::ReadFully(uint64_t addr, void* dst, size_t size) {

size_t rc = Read(addr, dst, size);

return rc == size;

}

bool Memory::ReadString(uint64_t addr, std::string* dst, size_t max_read) {

char buffer[256]; // Large enough for 99% of symbol names.

size_t size = 0; // Number of bytes which were read into the buffer.

for (size_t offset = 0; offset < max_read; offset += size) {

// Look for null-terminator first, so we can allocate string of exact size.

// If we know the end of valid memory range, do the reads in larger blocks.

size_t read = std::min(sizeof(buffer), max_read - offset);

size = Read(addr + offset, buffer, read);

if (size == 0) {

return false; // We have not found end of string yet and we can not read more data.

}

size_t length = strnlen(buffer, size); // Index of the null-terminator.

if (length < size) {

// We found the null-terminator. Allocate the string and set its content.

if (offset == 0) {

// We did just single read, so the buffer already contains the whole string.

dst->assign(buffer, length);

return true;

} else {

// The buffer contains only the last block. Read the whole string again.

dst->assign(offset + length, '\0');

return ReadFully(addr, dst->data(), dst->size());

}

return false;

}

std::unique_ptr<Memory> Memory::CreateFileMemory(const std::string& path, uint64_t offset,

uint64_t size) {

auto memory = std::make_unique<MemoryFileAtOffset>();

if (memory->Init(path, offset, size)) {

return memory;

}

return nullptr;

}

std::shared_ptr<Memory> Memory::CreateProcessMemory(pid_t pid) {

if (pid == getpid()) {

return std::shared_ptr<Memory>(new MemoryLocal());

}

return std::shared_ptr<Memory>(new MemoryRemote(pid));

}

std::shared_ptr<Memory> Memory::CreateProcessMemoryCached(pid_t pid) {

if (pid == getpid()) {

return std::shared_ptr<Memory>(new MemoryCache(new MemoryLocal()));

}

return std::shared_ptr<Memory>(new MemoryCache(new MemoryRemote(pid)));

}

std::shared_ptr<Memory> Memory::CreateProcessMemoryThreadCached(pid_t pid) {

if (pid == getpid()) {

return std::shared_ptr<Memory>(new MemoryThreadCache(new MemoryLocal()));

}

return std::shared_ptr<Memory>(new MemoryThreadCache(new MemoryRemote(pid)));

}

std::shared_ptr<Memory> Memory::CreateOfflineMemory(const uint8_t* data, uint64_t start,

uint64_t end) {

return std::shared_ptr<Memory>(new MemoryOfflineBuffer(data, start, end));

}

size_t MemoryBuffer::Read(uint64_t addr, void* dst, size_t size) {

if (addr >= size_) {

return 0;

}

size_t bytes_left = size_ - static_cast<size_t>(addr);

const unsigned char* actual_base = static_cast<const unsigned char*>(raw_) + addr;

size_t actual_len = std::min(bytes_left, size);

memcpy(dst, actual_base, actual_len);

return actual_len;

}

uint8_t* MemoryBuffer::GetPtr(size_t offset) {

if (offset < 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);

if (aligned_offset > static_cast<uint64_t>(buf.st_size) ||

offset > static_cast<uint64_t>(buf.st_size)) {

return false;

}

size_ = buf.st_size - aligned_offset;

uint64_t max_size;

if (!__builtin_add_overflow(size, offset_, &max_size) && max_size < size_) {

// Truncate the mapped size.

size_ = max_size;

}

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;

}

size_t MemoryFileAtOffset::Read(uint64_t addr, void* dst, size_t size) {

if (addr >= size_) {

return 0;

}

size_t bytes_left = size_ - static_cast<size_t>(addr);

const unsigned char* actual_base = static_cast<const unsigned char*>(data_) + addr;

size_t actual_len = std::min(bytes_left, size);

memcpy(dst, actual_base, actual_len);

return actual_len;

}

size_t MemoryRemote::Read(uint64_t addr, void* dst, size_t size) {

#if !defined(__LP64__)

// Cannot read an address greater than 32 bits in a 32 bit context.

if (addr > UINT32_MAX) {

return 0;

}

#endif

size_t (*read_func)(pid_t, uint64_t, void*, size_t) =

reinterpret_cast<size_t (*)(pid_t, uint64_t, void*, size_t)>(read_redirect_func_.load());

if (read_func != nullptr) {

return read_func(pid_, addr, dst, size);

} else {

// Prefer process_vm_read, try it first. If it doesn't work, use the

// ptrace function. If at least one of them returns at least some data,

// set that as the permanent function to use.

// This assumes that if process_vm_read works once, it will continue

// to work.

size_t bytes = ProcessVmRead(pid_, addr, dst, size);

if (bytes > 0) {

read_redirect_func_ = reinterpret_cast<uintptr_t>(ProcessVmRead);

return bytes;

}

bytes = PtraceRead(pid_, addr, dst, size);

if (bytes > 0) {

read_redirect_func_ = reinterpret_cast<uintptr_t>(PtraceRead);

}

return bytes;

}

size_t MemoryLocal::Read(uint64_t addr, void* dst, size_t size) {

#ifndef SENTRY_MODIFIED

errno = 0;

size_t rv = ProcessVmRead(getpid(), addr, dst, size);

// The syscall is only available in Linux 3.2, meaning Android 17.

// If that is the case, just fall back to an unsafe memcpy.

#if defined(__ANDROID_API__) && __ANDROID_API__ < 17

if (rv != size && errno == EINVAL) {

memcpy(dst, (void*)addr, size);

rv = size;

}

#endif

return rv;

#endif // SENTRY_MODIFIED

}

MemoryRange::MemoryRange(const std::shared_ptr<Memory>& memory, uint64_t begin, uint64_t length,

uint64_t offset)

: memory_(memory), begin_(begin), length_(length), offset_(offset) {}

size_t MemoryRange::Read(uint64_t addr, void* dst, size_t size) {

if (addr < offset_) {

return 0;

}

uint64_t read_offset = addr - offset_;

if (read_offset >= length_) {

return 0;

}

uint64_t read_length = std::min(static_cast<uint64_t>(size), length_ - read_offset);

uint64_t read_addr;

if (__builtin_add_overflow(read_offset, begin_, &read_addr)) {

return 0;

}

return memory_->Read(read_addr, dst, read_length);

}

bool MemoryRanges::Insert(MemoryRange* memory) {

uint64_t last_addr;

if (__builtin_add_overflow(memory->offset(), memory->length(), &last_addr)) {

// This should never happen in the real world. However, it is possible

// that an offset in a mapped in segment could be crafted such that

// this value overflows. In that case, clamp the value to the max uint64

// value.

last_addr = UINT64_MAX;

}

auto entry = maps_.try_emplace(last_addr, memory);

if (entry.second) {

return true;

}

delete memory;

return false;

}

size_t MemoryRanges::Read(uint64_t addr, void* dst, size_t size) {

auto entry = maps_.upper_bound(addr);

if (entry != maps_.end()) {

return entry->second->Read(addr, dst, size);

}

return 0;

}

bool MemoryOffline::Init(const std::string& file, uint64_t offset) {

auto memory_file = std::make_shared<MemoryFileAtOffset>();

if (!memory_file->Init(file, offset)) {

return false;

}

// The first uint64_t value is the start of memory.

uint64_t start;

if (!memory_file->ReadFully(0, &start, sizeof(start))) {

return false;

}

uint64_t size = memory_file->Size();

if (__builtin_sub_overflow(size, sizeof(start), &size)) {

return false;

}

memory_ = std::make_unique<MemoryRange>(memory_file, sizeof(start), size, start);

return true;

}

bool MemoryOffline::Init(const std::string& file, uint64_t offset, uint64_t start, uint64_t size) {

auto memory_file = std::make_shared<MemoryFileAtOffset>();

if (!memory_file->Init(file, offset)) {

return false;

}

memory_ = std::make_unique<MemoryRange>(memory_file, 0, size, start);

return true;

}

size_t MemoryOffline::Read(uint64_t addr, void* dst, size_t size) {

if (!memory_) {

return 0;

}

return memory_->Read(addr, dst, size);

}

MemoryOfflineBuffer::MemoryOfflineBuffer(const uint8_t* data, uint64_t start, uint64_t end)

: data_(data), start_(start), end_(end) {}

void MemoryOfflineBuffer::Reset(const uint8_t* data, uint64_t start, uint64_t end) {

data_ = data;

start_ = start;

end_ = end;

}

size_t MemoryOfflineBuffer::Read(uint64_t addr, void* dst, size_t size) {

if (addr < start_ || addr >= end_) {

return 0;

}

size_t read_length = std::min(size, static_cast<size_t>(end_ - addr));

memcpy(dst, &data_[addr - start_], read_length);

return read_length;

}

MemoryOfflineParts::~MemoryOfflineParts() {

for (auto memory : memories_) {

delete memory;

}

size_t MemoryOfflineParts::Read(uint64_t addr, void* dst, size_t size) {

if (memories_.empty()) {

return 0;

}

// Do a read on each memory object, no support for reading across the

// different memory objects.

for (MemoryOffline* memory : memories_) {

size_t bytes = memory->Read(addr, dst, size);

if (bytes != 0) {

return bytes;

}

return 0;

}

size_t MemoryCacheBase::InternalCachedRead(uint64_t addr, void* dst, size_t size,

CacheDataType* cache) {

uint64_t addr_page = addr >> kCacheBits;

auto entry = cache->find(addr_page);

uint8_t* cache_dst;

if (entry != cache->end()) {

cache_dst = entry->second;

} else {

cache_dst = (*cache)[addr_page];

if (!impl_->ReadFully(addr_page << kCacheBits, cache_dst, kCacheSize)) {

// Erase the entry.

cache->erase(addr_page);

return impl_->Read(addr, dst, size);

}

size_t max_read = ((addr_page + 1) << kCacheBits) - addr;

if (size <= max_read) {

memcpy(dst, &cache_dst[addr & kCacheMask], size);

return size;

}

// The read crossed into another cached entry, since a read can only cross

// into one extra cached page, duplicate the code rather than looping.

memcpy(dst, &cache_dst[addr & kCacheMask], max_read);

dst = &reinterpret_cast<uint8_t*>(dst)[max_read];

addr_page++;

entry = cache->find(addr_page);

if (entry != cache->end()) {

cache_dst = entry->second;

} else {

cache_dst = (*cache)[addr_page];

if (!impl_->ReadFully(addr_page << kCacheBits, cache_dst, kCacheSize)) {

// Erase the entry.

cache->erase(addr_page);

return impl_->Read(addr_page << kCacheBits, dst, size - max_read) + max_read;

}

memcpy(dst, cache_dst, size - max_read);

return size;

}

void MemoryCache::Clear() {

std::lock_guard<std::mutex> lock(cache_lock_);

cache_.clear();

}

size_t MemoryCache::CachedRead(uint64_t addr, void* dst, size_t size) {

// Use a single lock since this object is not designed to be performant

// for multiple object reading from multiple threads.

std::lock_guard<std::mutex> lock(cache_lock_);

return InternalCachedRead(addr, dst, size, &cache_);

}

MemoryThreadCache::MemoryThreadCache(Memory* memory) : MemoryCacheBase(memory) {

thread_cache_ = std::make_optional<pthread_t>();

if (pthread_key_create(&*thread_cache_, [](void* memory) {

CacheDataType* cache = reinterpret_cast<CacheDataType*>(memory);

delete cache;

}) != 0) {

Log::AsyncSafe("Failed to create pthread key.");

thread_cache_.reset();

}

MemoryThreadCache::~MemoryThreadCache() {

if (thread_cache_) {

CacheDataType* cache = reinterpret_cast<CacheDataType*>(pthread_getspecific(*thread_cache_));

delete cache;

pthread_key_delete(*thread_cache_);

}

size_t MemoryThreadCache::CachedRead(uint64_t addr, void* dst, size_t size) {

if (!thread_cache_) {

return impl_->Read(addr, dst, size);

}

CacheDataType* cache = reinterpret_cast<CacheDataType*>(pthread_getspecific(*thread_cache_));

if (cache == nullptr) {

cache = new CacheDataType;

pthread_setspecific(*thread_cache_, cache);

}

return InternalCachedRead(addr, dst, size, cache);

}

void MemoryThreadCache::Clear() {

if (!thread_cache_) {

return;

}

CacheDataType* cache = reinterpret_cast<CacheDataType*>(pthread_getspecific(*thread_cache_));

if (cache != nullptr) {

delete cache;

pthread_setspecific(*thread_cache_, nullptr);

}

} // namespace unwindstack

libunwindstack-ndk/Memory.cpp at master · getsentry/libunwindstack-ndk · GitHub

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