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#include <algorithm>
#include <cerrno>
#include <cstring>
#include <fstream>
#include <ios>
#include <memory>
#include <sys/uio.h>
#include <syscall.h>
#include <system_error>
#include <unistd.h>
#include <utility>
#include "corefile.h"
#include "logging.h"
#include "mem.h"
namespace pystack {
static ssize_t
_process_vm_readv(
pid_t pid,
const struct iovec* lvec,
unsigned long liovcnt,
const struct iovec* rvec,
unsigned long riovcnt,
unsigned long flags)
{
return syscall(SYS_process_vm_readv, pid, lvec, liovcnt, rvec, riovcnt, flags);
}
static const std::string PERM_MESSAGE = "Operation not permitted";
static const size_t CACHE_CAPACITY = 5e+7; // 50MB
VirtualMap::VirtualMap(
uintptr_t start,
uintptr_t end,
unsigned long filesize,
std::string flags,
unsigned long offset,
std::string device,
unsigned long inode,
std::string pathname)
: d_start(start)
, d_end(end)
, d_filesize(filesize)
, d_flags(std::move(flags))
, d_offset(offset)
, d_device(std::move(device))
, d_inode(inode)
, d_path(std::move(pathname))
{
}
bool
VirtualMap::containsAddr(remote_addr_t addr) const
{
return d_start <= addr && addr < d_end;
}
uintptr_t
VirtualMap::Start() const
{
return d_start;
}
uintptr_t
VirtualMap::End() const
{
return d_end;
}
unsigned long
VirtualMap::FileSize() const
{
return d_filesize;
}
const std::string&
VirtualMap::Flags() const
{
return d_flags;
}
unsigned long
VirtualMap::Offset() const
{
return d_offset;
}
const std::string&
VirtualMap::Device() const
{
return d_device;
}
unsigned long
VirtualMap::Inode() const
{
return d_inode;
}
const std::string&
VirtualMap::Path() const
{
return d_path;
}
size_t
VirtualMap::Size() const
{
return d_end - d_start;
}
MemoryMapInformation::MemoryMapInformation()
: d_main_map(std::nullopt)
, d_bss(std::nullopt)
, d_heap(std::nullopt)
{
}
const std::optional<VirtualMap>&
MemoryMapInformation::MainMap()
{
return d_main_map;
}
const std::optional<VirtualMap>&
MemoryMapInformation::Bss()
{
return d_bss;
}
const std::optional<VirtualMap>&
MemoryMapInformation::Heap()
{
return d_heap;
}
void
MemoryMapInformation::setMainMap(const VirtualMap& main_map)
{
d_main_map = main_map;
}
void
MemoryMapInformation::setBss(const VirtualMap& bss)
{
d_bss = bss;
}
void
MemoryMapInformation::setHeap(const VirtualMap& heap)
{
d_heap = heap;
}
LRUCache::LRUCache(size_t capacity)
: d_cache_capacity(capacity)
, d_size(0){};
void
LRUCache::put(uintptr_t key, std::vector<char>&& value)
{
size_t value_size = value.size();
if (!can_fit(value_size)) {
return;
}
auto it = d_cache.find(key);
if (it != d_cache.end()) {
d_cache_list.erase(it->second.it);
d_cache.erase(it);
}
while (d_size + value_size > d_cache_capacity) {
d_cache.erase(d_cache_list.back().key);
d_size -= d_cache_list.back().size;
d_cache_list.pop_back();
}
d_cache_list.push_front(LRUCache::ListNode{key, value_size});
d_cache[key] = LRUCache::CacheValue{std::move(value), d_cache_list.begin()};
d_size += value_size;
}
const std::vector<char>&
LRUCache::get(uintptr_t key)
{
auto it = d_cache.find(key);
if (it == d_cache.end()) {
throw std::range_error("There is no such key in the cache");
} else {
auto node_it = it->second.it;
d_cache_list.splice(d_cache_list.begin(), d_cache_list, node_it);
return it->second.data;
}
}
bool
LRUCache::exists(uintptr_t key)
{
return (d_cache.find(key) != d_cache.end());
}
bool
LRUCache::can_fit(size_t size)
{
return d_cache_capacity >= size;
}
ProcessMemoryManager::ProcessMemoryManager(pid_t pid, const std::vector<VirtualMap>& vmaps)
: d_pid(pid)
, d_vmaps(vmaps)
, d_lru_cache(CACHE_CAPACITY)
{
}
ProcessMemoryManager::ProcessMemoryManager(pid_t pid)
: d_pid(pid)
, d_lru_cache(CACHE_CAPACITY)
{
}
ssize_t
ProcessMemoryManager::readChunk(remote_addr_t addr, size_t len, char* dst) const
{
struct iovec local[1];
struct iovec remote[1];
ssize_t result = 0;
ssize_t read = 0;
do {
local[0].iov_base = dst + result;
local[0].iov_len = len - result;
remote[0].iov_base = reinterpret_cast<uint8_t*>(addr) + result;
remote[0].iov_len = len - result;
read = _process_vm_readv(d_pid, local, 1, remote, 1, 0);
if (read < 0) {
if (errno == EFAULT) {
throw InvalidRemoteAddress();
} else if (errno == EPERM) {
throw std::runtime_error(PERM_MESSAGE);
}
throw std::system_error(errno, std::generic_category());
}
result += read;
} while ((size_t)read != local[0].iov_len);
return result;
}
ssize_t
ProcessMemoryManager::copyMemoryFromProcess(remote_addr_t addr, size_t len, void* dst) const
{
auto vmap = std::find_if(d_vmaps.begin(), d_vmaps.end(), [&](const auto& vmap) {
return vmap.containsAddr(addr) && vmap.containsAddr(addr + len - 1);
});
if (vmap == d_vmaps.end() || !d_lru_cache.can_fit(vmap->Size())) {
return readChunk(addr, len, reinterpret_cast<char*>(dst));
}
uintptr_t key = vmap->Start();
size_t chunk_size = vmap->Size();
remote_addr_t vmap_start_addr = vmap->Start();
size_t offset_addr = addr - vmap_start_addr;
if (!d_lru_cache.exists(key)) {
std::vector<char> buf(chunk_size);
readChunk(vmap_start_addr, chunk_size, buf.data());
d_lru_cache.put(key, std::move(buf));
}
std::memcpy(dst, d_lru_cache.get(key).data() + offset_addr, len);
return len;
}
bool
ProcessMemoryManager::isAddressValid(remote_addr_t addr, const VirtualMap& map) const
{
if (addr == (uintptr_t) nullptr) {
return false;
}
return map.Start() <= addr && addr < map.End();
}
CorefileRemoteMemoryManager::CorefileRemoteMemoryManager(
std::shared_ptr<CoreFileAnalyzer> analyzer,
std::vector<VirtualMap>& vmaps)
: d_analyzer(std::move(analyzer))
, d_vmaps(vmaps)
{
CoreFileExtractor extractor{d_analyzer};
d_shared_libs = extractor.ModuleInformation();
const char* filename = d_analyzer->d_filename.c_str();
int fd = open(filename, O_RDONLY);
if (fd == -1) {
LOG(ERROR) << "Failed to open a file " << filename;
throw RemoteMemCopyError();
}
StatusCode ret = readCorefile(fd, filename);
int close_ret = close(fd);
if (close_ret == -1) {
LOG(ERROR) << "Failed to close a file " << filename;
throw RemoteMemCopyError();
}
if (ret == StatusCode::ERROR) {
throw RemoteMemCopyError();
}
}
CorefileRemoteMemoryManager::StatusCode
CorefileRemoteMemoryManager::readCorefile(int fd, const char* filename) noexcept
{
struct stat fileInfo = {0};
if (fstat(fd, &fileInfo) == -1) {
LOG(ERROR) << "Failed to get a file size for a file " << filename;
return StatusCode::ERROR;
}
if (fileInfo.st_size == 0) {
LOG(ERROR) << "File " << filename << " is empty";
return StatusCode::ERROR;
}
d_corefile_size = fileInfo.st_size;
void* map = mmap(0, d_corefile_size, PROT_READ, MAP_PRIVATE, fd, 0);
if (map == MAP_FAILED) {
LOG(ERROR) << "Failed to mmap a file " << filename;
return StatusCode::ERROR;
}
d_corefile_data = std::unique_ptr<char, std::function<void(char*)>>(
reinterpret_cast<char*>(map),
[this](auto addr) {
if (munmap(addr, d_corefile_size) == -1) {
LOG(ERROR) << "Failed to un-mmap a file " << d_analyzer->d_filename.c_str();
}
});
int madvise_result = madvise(d_corefile_data.get(), d_corefile_size, MADV_RANDOM);
if (madvise_result == -1) {
LOG(WARNING) << "Madvise for a file " << filename << " failed";
}
return StatusCode::SUCCESS;
}
ssize_t
CorefileRemoteMemoryManager::copyMemoryFromProcess(remote_addr_t addr, size_t size, void* destination)
const
{
off_t offset_in_file = 0;
StatusCode ret = getMemoryLocationFromCore(addr, &offset_in_file);
if (ret == StatusCode::SUCCESS) {
if (size > d_corefile_size || static_cast<size_t>(offset_in_file) > d_corefile_size - size) {
throw InvalidRemoteAddress();
}
memcpy(destination, d_corefile_data.get() + offset_in_file, size);
return size;
}
// The memory may be in the data segment of some shared library
const std::string* filename = nullptr;
ret = getMemoryLocationFromElf(addr, &filename, &offset_in_file);
if (ret == StatusCode::ERROR) {
throw InvalidRemoteAddress();
}
std::ifstream is(*filename, std::ifstream::binary);
if (is) {
is.seekg(offset_in_file);
is.read((char*)destination, size);
} else {
LOG(ERROR) << "Failed to read memory from file " << *filename;
throw InvalidRemoteAddress();
}
return size;
}
CorefileRemoteMemoryManager::StatusCode
CorefileRemoteMemoryManager::getMemoryLocationFromCore(remote_addr_t addr, off_t* offset_in_file) const
{
auto corefile_it = std::find_if(d_vmaps.cbegin(), d_vmaps.cend(), [&](auto& map) {
return (map.Start() <= addr && addr < map.End()) && (map.FileSize() != 0 && map.Offset() != 0);
});
if (corefile_it == d_vmaps.cend()) {
return StatusCode::ERROR;
}
unsigned long base = corefile_it->Offset() - corefile_it->Start();
*offset_in_file = base + addr;
return StatusCode::SUCCESS;
}
CorefileRemoteMemoryManager::StatusCode
CorefileRemoteMemoryManager::getMemoryLocationFromElf(
remote_addr_t addr,
const std::string** filename,
off_t* offset_in_file) const
{
auto shared_libs_it = std::find_if(d_shared_libs.cbegin(), d_shared_libs.cend(), [&](auto& map) {
return map.start <= addr && addr <= map.end;
});
if (shared_libs_it == d_shared_libs.cend()) {
return StatusCode::ERROR;
}
*filename = &shared_libs_it->filename;
*offset_in_file = addr - shared_libs_it->start;
return StatusCode::SUCCESS;
}
bool
CorefileRemoteMemoryManager::isAddressValid(remote_addr_t addr, const VirtualMap& map) const
{
if (addr == (uintptr_t) nullptr) {
return false;
}
return map.Start() <= addr && addr < map.Start() + map.Size();
}
} // namespace pystack