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linux: Enable brokered memory reading

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This change:
1. Updates the broker's memory reading protocol to enable short reads.
2. Updates Ptracer to allow short reads.
3. Updates the broker to allow reading from a memory file.
4. Updates the broker's default file root to be "/proc/[pid]/".
5. Adds PtraceConnection::Memory() to produce a suitable memory reader
for a connection type.

Bug: crashpad:30
Change-Id: I8c004016065d981acd1fa74ad1b8e51ce07c7c85
Reviewed-on: https://chromium-review.googlesource.com/991455
Reviewed-by: Mark Mentovai <mark@chromium.org>
Commit-Queue: Joshua Peraza <jperaza@chromium.org>
This commit is contained in:
Joshua Peraza 2018-04-05 13:00:15 -07:00 committed by Commit Bot
parent 1ebedb05dd
commit 10fd672bde
16 changed files with 442 additions and 192 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
snapshot/linux/process_reader_linux.cc
View File

@ -182,7 +182,6 @@ ProcessReaderLinux::ProcessReaderLinux()
threads_(),
modules_(),
elf_readers_(),
process_memory_(),
is_64_bit_(false),
initialized_threads_(false),
initialized_modules_(false),
@ -203,11 +202,6 @@ bool ProcessReaderLinux::Initialize(PtraceConnection* connection) {
return false;
}
pid_t pid = connection->GetProcessID();
if (!process_memory_.Initialize(pid)) {
return false;
}
is_64_bit_ = process_info_.Is64Bit();
INITIALIZATION_STATE_SET_VALID(initialized_);

4
snapshot/linux/process_reader_linux.h
View File

@ -32,7 +32,6 @@
#include "util/misc/initialization_state_dcheck.h"
#include "util/posix/process_info.h"
#include "util/process/process_memory.h"
#include "util/process/process_memory_linux.h"
namespace crashpad {
@ -103,7 +102,7 @@ class ProcessReaderLinux {
pid_t ParentProcessID() const { return process_info_.ParentProcessID(); }
//! \brief Return a memory reader for the target process.
ProcessMemory* Memory() { return &process_memory_; }
ProcessMemory* Memory() { return connection_->Memory(); }
//! \brief Return a memory map of the target process.
MemoryMap* GetMemoryMap() { return &memory_map_; }
@ -146,7 +145,6 @@ class ProcessReaderLinux {
std::vector<Thread> threads_;
std::vector<Module> modules_;
std::vector<std::unique_ptr<ElfImageReader>> elf_readers_;
ProcessMemoryLinux process_memory_;
bool is_64_bit_;
bool initialized_threads_;
bool initialized_modules_;

15
test/linux/fake_ptrace_connection.cc
View File

@ -14,6 +14,8 @@
#include "test/linux/fake_ptrace_connection.h"
#include <utility>
#include "build/build_config.h"
#include "gtest/gtest.h"
#include "util/file/file_io.h"
@ -77,5 +79,18 @@ bool FakePtraceConnection::ReadFileContents(const base::FilePath& path,
return LoggingReadEntireFile(path, contents);
}
ProcessMemory* FakePtraceConnection::Memory() {
INITIALIZATION_STATE_DCHECK_VALID(initialized_);
if (!memory_) {
auto mem = std::make_unique<ProcessMemoryLinux>();
if (mem->Initialize(pid_)) {
memory_ = std::move(mem);
} else {
ADD_FAILURE();
}
}
return memory_.get();
}
} // namespace test
} // namespace crashpad

7
test/linux/fake_ptrace_connection.h
View File

@ -17,11 +17,13 @@
#include <sys/types.h>
#include <memory>
#include <set>
#include "base/macros.h"
#include "util/linux/ptrace_connection.h"
#include "util/misc/initialization_state_dcheck.h"
#include "util/process/process_memory_linux.h"
namespace crashpad {
namespace test {
@ -56,8 +58,13 @@ class FakePtraceConnection : public PtraceConnection {
bool ReadFileContents(const base::FilePath& path,
std::string* contents) override;
//! \brief Attempts to create a ProcessMemory when called, calling
//! ADD_FAILURE() and returning `nullptr` on failure.
ProcessMemory* Memory() override;
private:
std::set<pid_t> attachments_;
std::unique_ptr<ProcessMemoryLinux> memory_;
pid_t pid_;
bool is_64_bit_;
InitializationStateDcheck initialized_;

10
util/linux/direct_ptrace_connection.cc
View File

@ -23,6 +23,7 @@ namespace crashpad {
DirectPtraceConnection::DirectPtraceConnection()
: PtraceConnection(),
attachments_(),
memory_(),
pid_(-1),
ptracer_(/* can_log= */ true),
initialized_() {}
@ -37,6 +38,10 @@ bool DirectPtraceConnection::Initialize(pid_t pid) {
}
pid_ = pid;
if (!memory_.Initialize(pid)) {
return false;
}
INITIALIZATION_STATE_SET_VALID(initialized_);
return true;
}
@ -71,4 +76,9 @@ bool DirectPtraceConnection::ReadFileContents(const base::FilePath& path,
return LoggingReadEntireFile(path, contents);
}
ProcessMemory* DirectPtraceConnection::Memory() {
INITIALIZATION_STATE_DCHECK_VALID(initialized_);
return &memory_;
}
} // namespace crashpad

3
util/linux/direct_ptrace_connection.h
View File

@ -25,6 +25,7 @@
#include "util/linux/ptracer.h"
#include "util/linux/scoped_ptrace_attach.h"
#include "util/misc/initialization_state_dcheck.h"
#include "util/process/process_memory_linux.h"
namespace crashpad {
@ -54,9 +55,11 @@ class DirectPtraceConnection : public PtraceConnection {
bool GetThreadInfo(pid_t tid, ThreadInfo* info) override;
bool ReadFileContents(const base::FilePath& path,
std::string* contents) override;
ProcessMemory* Memory() override;
private:
std::vector<std::unique_ptr<ScopedPtraceAttach>> attachments_;
ProcessMemoryLinux memory_;
pid_t pid_;
Ptracer ptracer_;
InitializationStateDcheck initialized_;

2
util/linux/exception_handler_client.cc
View File

@ -130,7 +130,7 @@ int ExceptionHandlerClient::WaitForCrashDumpComplete() {
constexpr bool am_64_bit = false;
#endif // ARCH_CPU_64_BITS
PtraceBroker broker(server_sock_, am_64_bit);
PtraceBroker broker(server_sock_, getppid(), am_64_bit);
_exit(broker.Run());
}

113
util/linux/ptrace_broker.cc
View File

@ -23,24 +23,65 @@
#include "base/logging.h"
#include "base/posix/eintr_wrapper.h"
#include "util/file/file_io.h"
namespace crashpad {
PtraceBroker::PtraceBroker(int sock, bool is_64_bit)
namespace {
size_t FormatPID(char* buffer, pid_t pid) {
DCHECK_GE(pid, 0);
char pid_buf[16];
size_t length = 0;
do {
DCHECK_LT(length, sizeof(pid_buf));
pid_buf[length] = '0' + pid % 10;
pid /= 10;
++length;
} while (pid > 0);
for (size_t index = 0; index < length; ++index) {
buffer[index] = pid_buf[length - index - 1];
}
return length;
}
} // namespace
PtraceBroker::PtraceBroker(int sock, pid_t pid, bool is_64_bit)
: ptracer_(is_64_bit, /* can_log= */ false),
file_root_("/proc/"),
file_root_(file_root_buffer_),
attachments_(nullptr),
attach_count_(0),
attach_capacity_(0),
sock_(sock) {
memory_file_(),
sock_(sock),
memory_pid_(pid),
tried_opening_mem_file_(false) {
AllocateAttachments();
static constexpr char kProc[] = "/proc/";
size_t root_length = strlen(kProc);
memcpy(file_root_buffer_, kProc, root_length);
if (pid >= 0) {
root_length += FormatPID(file_root_buffer_ + root_length, pid);
DCHECK_LT(root_length, sizeof(file_root_buffer_));
file_root_buffer_[root_length] = '/';
++root_length;
}
DCHECK_LT(root_length, sizeof(file_root_buffer_));
file_root_buffer_[root_length] = '\0';
}
PtraceBroker::~PtraceBroker() = default;
void PtraceBroker::SetFileRoot(const char* new_root) {
DCHECK_EQ(new_root[strlen(new_root) - 1], '/');
memory_pid_ = -1;
file_root_ = new_root;
}
@ -189,12 +230,12 @@ int PtraceBroker::SendError(Errno err) {
return WriteFile(sock_, &err, sizeof(err)) ? 0 : errno;
}
int PtraceBroker::SendReadError(Errno err) {
int PtraceBroker::SendReadError(ReadError error) {
int32_t rv = -1;
if (!WriteFile(sock_, &rv, sizeof(rv))) {
return errno;
}
return SendError(err);
return WriteFile(sock_, &rv, sizeof(rv)) &&
WriteFile(sock_, &error, sizeof(error))
? 0
: errno;
}
int PtraceBroker::SendOpenResult(OpenResult result) {
@ -208,7 +249,7 @@ int PtraceBroker::SendFileContents(FileHandle handle) {
rv = ReadFile(handle, buffer, sizeof(buffer));
if (rv < 0) {
return SendReadError(errno);
return SendReadError(static_cast<ReadError>(errno));
}
if (!WriteFile(sock_, &rv, sizeof(rv))) {
@ -225,25 +266,59 @@ int PtraceBroker::SendFileContents(FileHandle handle) {
return 0;
}
void PtraceBroker::TryOpeningMemFile() {
if (tried_opening_mem_file_) {
return;
}
tried_opening_mem_file_ = true;
if (memory_pid_ < 0) {
return;
}
char mem_path[32];
size_t root_length = strlen(file_root_buffer_);
static constexpr char kMem[] = "mem";
DCHECK_LT(root_length + strlen(kMem) + 1, sizeof(mem_path));
memcpy(mem_path, file_root_buffer_, root_length);
// Include the trailing NUL.
memcpy(mem_path + root_length, kMem, strlen(kMem) + 1);
memory_file_.reset(
HANDLE_EINTR(open(mem_path, O_RDONLY | O_CLOEXEC | O_NOCTTY)));
}
int PtraceBroker::SendMemory(pid_t pid, VMAddress address, VMSize size) {
if (memory_pid_ >= 0 && pid != memory_pid_) {
return SendReadError(kReadErrorAccessDenied);
}
TryOpeningMemFile();
auto read_memory = [this, pid](VMAddress address, size_t size, char* buffer) {
return this->memory_file_.is_valid()
? HANDLE_EINTR(
pread64(this->memory_file_.get(), buffer, size, address))
: this->ptracer_.ReadUpTo(pid, address, size, buffer);
};
char buffer[4096];
while (size > 0) {
VMSize bytes_read = std::min(size, VMSize{sizeof(buffer)});
size_t to_read = std::min(size, VMSize{sizeof(buffer)});
if (!ptracer_.ReadMemory(pid, address, bytes_read, buffer)) {
bytes_read = 0;
Errno error = errno;
if (!WriteFile(sock_, &bytes_read, sizeof(bytes_read)) ||
!WriteFile(sock_, &error, sizeof(error))) {
return errno;
}
return 0;
int32_t bytes_read = read_memory(address, to_read, buffer);
if (bytes_read < 0) {
return SendReadError(static_cast<ReadError>(errno));
}
if (!WriteFile(sock_, &bytes_read, sizeof(bytes_read))) {
return errno;
}
if (bytes_read == 0) {
return 0;
}
if (!WriteFile(sock_, buffer, bytes_read)) {
return errno;
}

39
util/linux/ptrace_broker.h
View File

@ -62,12 +62,9 @@ class PtraceBroker {
kTypeGetThreadInfo,
//! \brief Reads memory from the attached process. The data is returned in
//! a series of messages. Each message begins with a VMSize indicating
//! the number of bytes being returned in this message, followed by
//! the requested bytes. The broker continues to send messages until
//! either all of the requested memory has been sent or an error
//! occurs, in which case it sends a message containing a VMSize equal
//! to zero, followed by an Errno.
//! a series of messages. Each message begins with an int32_t
//! indicating the number of bytes read, 0 for end-of-file, or -1 for
//! errors, followed by a ReadError. On success the bytes read follow.
kTypeReadMemory,
//! \brief Read a file's contents. The data is returned in a series of
@ -98,7 +95,7 @@ class PtraceBroker {
VMSize size;
} iov;
// \brief Specifies the file path to read for a kTypeReadFile request.
//! \brief Specifies the file path to read for a kTypeReadFile request.
struct {
//! \brief The number of bytes in #path. The path should not include a
//! `NUL`-terminator.
@ -124,6 +121,14 @@ class PtraceBroker {
kOpenResultSuccess = 0,
};
//! \brief A result used in operations that read from memory or files.
//!
//! Positive values of this enum are reserved for sending errno values.
enum ReadError : int32_t {
//! \brief Access to this data is denied.
kReadErrorAccessDenied = -1,
};
//! \brief The response sent for a Request with type kTypeGetThreadInfo.
struct GetThreadInfoResponse {
//! \brief Information about the specified thread. Only valid if #success
@ -139,9 +144,15 @@ class PtraceBroker {
//!
//! \param[in] sock A socket on which to read requests from a connected
//! PtraceClient. Does not take ownership of the socket.
//! \param[in] pid The process ID of the process the broker is expected to
//! trace. Setting this value exends the default file root to
//! "/proc/[pid]/" and enables memory reading via /proc/[pid]/mem. The
//! broker will deny any requests to read memory from processes whose
//! processID is not \a pid. If pid is -1, the broker will serve requests
//! to read memory from any process it is able to via `ptrace PEEKDATA`.
//! \param[in] is_64_bit Whether this broker should be configured to trace a
//! 64-bit process.
PtraceBroker(int sock, bool is_64_bit);
PtraceBroker(int sock, pid_t pid, bool is_64_bit);
~PtraceBroker();
@ -149,7 +160,10 @@ class PtraceBroker {
//! root.
//!
//! If this method is not called, the broker defaults to only serving files
//! under "/proc/".
//! under "/proc/" or "/proc/[pid]/" if a pid was set.
//!
//! Calling this function disables reading from a memory file if one has not
//! already been opened.
//!
//! \param[in] root A NUL-terminated c-string containing the path to the new
//! root. \a root must not be `nullptr`, must end in a '/', and the caller
@ -173,18 +187,23 @@ class PtraceBroker {
void ReleaseAttachments();
int RunImpl();
int SendError(Errno err);
int SendReadError(Errno err);
int SendReadError(ReadError err);
int SendOpenResult(OpenResult result);
int SendFileContents(FileHandle handle);
void TryOpeningMemFile();
int SendMemory(pid_t pid, VMAddress address, VMSize size);
int ReceiveAndOpenFilePath(VMSize path_length, ScopedFileHandle* handle);
char file_root_buffer_[32];
Ptracer ptracer_;
const char* file_root_;
ScopedPtraceAttach* attachments_;
size_t attach_count_;
size_t attach_capacity_;
ScopedFileHandle memory_file_;
int sock_;
pid_t memory_pid_;
bool tried_opening_mem_file_;
DISALLOW_COPY_AND_ASSIGN(PtraceBroker);
};

159
util/linux/ptrace_broker_test.cc
View File

@ -127,6 +127,85 @@ class SameBitnessTest : public Multiprocess {
}
private:
void BrokerTests(bool set_broker_pid,
LinuxVMAddress child1_tls,
LinuxVMAddress child2_tls,
pid_t child2_tid,
const base::FilePath& file_dir,
const base::FilePath& test_file,
const std::string& expected_file_contents) {
int socks[2];
ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, socks), 0);
ScopedFileHandle broker_sock(socks[0]);
ScopedFileHandle client_sock(socks[1]);
#if defined(ARCH_CPU_64_BITS)
constexpr bool am_64_bit = true;
#else
constexpr bool am_64_bit = false;
#endif // ARCH_CPU_64_BITS
PtraceBroker broker(
broker_sock.get(), set_broker_pid ? ChildPID() : -1, am_64_bit);
RunBrokerThread broker_thread(&broker);
broker_thread.Start();
PtraceClient client;
ASSERT_TRUE(client.Initialize(
client_sock.get(), ChildPID(), /* try_direct_memory= */ false));
EXPECT_EQ(client.GetProcessID(), ChildPID());
EXPECT_TRUE(client.Attach(child2_tid));
EXPECT_EQ(client.Is64Bit(), am_64_bit);
ThreadInfo info1;
ASSERT_TRUE(client.GetThreadInfo(ChildPID(), &info1));
EXPECT_EQ(info1.thread_specific_data_address, child1_tls);
ThreadInfo info2;
ASSERT_TRUE(client.GetThreadInfo(child2_tid, &info2));
EXPECT_EQ(info2.thread_specific_data_address, child2_tls);
ProcessMemory* memory = client.Memory();
ASSERT_TRUE(memory);
auto buffer = std::make_unique<char[]>(mapping_.len());
ASSERT_TRUE(memory->Read(
mapping_.addr_as<VMAddress>(), mapping_.len(), buffer.get()));
auto expected_buffer = mapping_.addr_as<char*>();
for (size_t index = 0; index < mapping_.len(); ++index) {
EXPECT_EQ(buffer[index], expected_buffer[index]);
}
char first;
ASSERT_TRUE(
memory->Read(mapping_.addr_as<VMAddress>(), sizeof(first), &first));
EXPECT_EQ(first, expected_buffer[0]);
char last;
ASSERT_TRUE(memory->Read(mapping_.addr_as<VMAddress>() + mapping_.len() - 1,
sizeof(last),
&last));
EXPECT_EQ(last, expected_buffer[mapping_.len() - 1]);
char unmapped;
EXPECT_FALSE(memory->Read(mapping_.addr_as<VMAddress>() + mapping_.len(),
sizeof(unmapped),
&unmapped));
std::string file_root = file_dir.value() + '/';
broker.SetFileRoot(file_root.c_str());
std::string file_contents;
ASSERT_TRUE(client.ReadFileContents(test_file, &file_contents));
EXPECT_EQ(file_contents, expected_file_contents);
ScopedTempDir temp_dir2;
base::FilePath test_file2(temp_dir2.path().Append("test_file2"));
ASSERT_TRUE(CreateFile(test_file2));
EXPECT_FALSE(client.ReadFileContents(test_file2, &file_contents));
}
void MultiprocessParent() override {
LinuxVMAddress child1_tls;
ASSERT_TRUE(LoggingReadFileExactly(
@ -140,11 +219,6 @@ class SameBitnessTest : public Multiprocess {
ASSERT_TRUE(LoggingReadFileExactly(
ReadPipeHandle(), &child2_tls, sizeof(child2_tls)));
int socks[2];
ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, socks), 0);
ScopedFileHandle broker_sock(socks[0]);
ScopedFileHandle client_sock(socks[1]);
ScopedTempDir temp_dir;
base::FilePath file_path(temp_dir.path().Append("test_file"));
std::string expected_file_contents;
@ -162,67 +236,20 @@ class SameBitnessTest : public Multiprocess {
expected_file_contents.size()));
}
#if defined(ARCH_CPU_64_BITS)
constexpr bool am_64_bit = true;
#else
constexpr bool am_64_bit = false;
#endif // ARCH_CPU_64_BITS
PtraceBroker broker(broker_sock.get(), am_64_bit);
RunBrokerThread broker_thread(&broker);
broker_thread.Start();
{
PtraceClient client;
ASSERT_TRUE(client.Initialize(client_sock.get(), ChildPID()));
EXPECT_EQ(client.GetProcessID(), ChildPID());
EXPECT_TRUE(client.Attach(child2_tid));
EXPECT_EQ(client.Is64Bit(), am_64_bit);
ThreadInfo info1;
ASSERT_TRUE(client.GetThreadInfo(ChildPID(), &info1));
EXPECT_EQ(info1.thread_specific_data_address, child1_tls);
ThreadInfo info2;
ASSERT_TRUE(client.GetThreadInfo(child2_tid, &info2));
EXPECT_EQ(info2.thread_specific_data_address, child2_tls);
auto buffer = std::make_unique<char[]>(mapping_.len());
ASSERT_TRUE(client.Read(
mapping_.addr_as<VMAddress>(), mapping_.len(), buffer.get()));
auto expected_buffer = mapping_.addr_as<char*>();
for (size_t index = 0; index < mapping_.len(); ++index) {
EXPECT_EQ(buffer[index], expected_buffer[index]);
}
char first;
ASSERT_TRUE(
client.Read(mapping_.addr_as<VMAddress>(), sizeof(first), &first));
EXPECT_EQ(first, expected_buffer[0]);
char last;
ASSERT_TRUE(
client.Read(mapping_.addr_as<VMAddress>() + mapping_.len() - 1,
sizeof(last),
&last));
EXPECT_EQ(last, expected_buffer[mapping_.len() - 1]);
char unmapped;
EXPECT_FALSE(client.Read(mapping_.addr_as<VMAddress>() + mapping_.len(),
sizeof(unmapped),
&unmapped));
std::string file_root = temp_dir.path().value() + '/';
broker.SetFileRoot(file_root.c_str());
std::string file_contents;
ASSERT_TRUE(client.ReadFileContents(file_path, &file_contents));
EXPECT_EQ(file_contents, expected_file_contents);
ScopedTempDir temp_dir2;
base::FilePath test_file2(temp_dir2.path().Append("test_file2"));
ASSERT_TRUE(CreateFile(test_file2));
EXPECT_FALSE(client.ReadFileContents(test_file2, &file_contents));
}
BrokerTests(true,
child1_tls,
child2_tls,
child2_tid,
temp_dir.path(),
file_path,
expected_file_contents);
BrokerTests(false,
child1_tls,
child2_tls,
child2_tid,
temp_dir.path(),
file_path,
expected_file_contents);
}
void MultiprocessChild() override {

134
util/linux/ptrace_client.cc
View File

@ -15,12 +15,14 @@
#include "util/linux/ptrace_client.h"
#include <errno.h>
#include <stdio.h>
#include <string>
#include "base/logging.h"
#include "util/file/file_io.h"
#include "util/linux/ptrace_broker.h"
#include "util/process/process_memory_linux.h"
namespace crashpad {
@ -36,6 +38,27 @@ bool ReceiveAndLogError(int sock, const std::string& operation) {
return true;
}
bool ReceiveAndLogReadError(int sock, const std::string& operation) {
PtraceBroker::ReadError err;
if (!LoggingReadFileExactly(sock, &err, sizeof(err))) {
return false;
}
switch (err) {
case PtraceBroker::kReadErrorAccessDenied:
LOG(ERROR) << operation << " access denied";
return true;
default:
if (err <= 0) {
LOG(ERROR) << operation << " invalid error " << err;
DCHECK(false);
return false;
}
errno = err;
PLOG(ERROR) << operation;
return true;
}
}
bool AttachImpl(int sock, pid_t tid) {
PtraceBroker::Request request;
request.type = PtraceBroker::Request::kTypeAttach;
@ -61,6 +84,7 @@ bool AttachImpl(int sock, pid_t tid) {
PtraceClient::PtraceClient()
: PtraceConnection(),
memory_(),
sock_(kInvalidFileHandle),
pid_(-1),
is_64_bit_(false),
@ -74,7 +98,7 @@ PtraceClient::~PtraceClient() {
}
}
bool PtraceClient::Initialize(int sock, pid_t pid) {
bool PtraceClient::Initialize(int sock, pid_t pid, bool try_direct_memory) {
INITIALIZATION_STATE_SET_INITIALIZING(initialized_);
sock_ = sock;
pid_ = pid;
@ -97,46 +121,20 @@ bool PtraceClient::Initialize(int sock, pid_t pid) {
}
is_64_bit_ = is_64_bit == kBoolTrue;
if (try_direct_memory) {
auto direct_mem = std::make_unique<ProcessMemoryLinux>();
if (direct_mem->Initialize(pid)) {
memory_.reset(direct_mem.release());
}
}
if (!memory_) {
memory_ = std::make_unique<BrokeredMemory>(this);
}
INITIALIZATION_STATE_SET_VALID(initialized_);
return true;
}
bool PtraceClient::Read(VMAddress address, size_t size, void* buffer) {
INITIALIZATION_STATE_DCHECK_VALID(initialized_);
char* buffer_c = reinterpret_cast<char*>(buffer);
PtraceBroker::Request request;
request.type = PtraceBroker::Request::kTypeReadMemory;
request.tid = pid_;
request.iov.base = address;
request.iov.size = size;
if (!LoggingWriteFile(sock_, &request, sizeof(request))) {
return false;
}
while (size > 0) {
VMSize bytes_read;
if (!LoggingReadFileExactly(sock_, &bytes_read, sizeof(bytes_read))) {
return false;
}
if (!bytes_read) {
ReceiveAndLogError(sock_, "PtraceBroker ReadMemory");
return false;
}
if (!LoggingReadFileExactly(sock_, buffer_c, bytes_read)) {
return false;
}
size -= bytes_read;
buffer_c += bytes_read;
}
return true;
}
pid_t PtraceClient::GetProcessID() {
INITIALIZATION_STATE_DCHECK_VALID(initialized_);
return pid_;
@ -197,7 +195,7 @@ bool PtraceClient::ReadFileContents(const base::FilePath& path,
}
if (read_result < 0) {
ReceiveAndLogError(sock_, "ReadFileContents");
ReceiveAndLogReadError(sock_, "ReadFileContents");
return false;
}
@ -215,6 +213,66 @@ bool PtraceClient::ReadFileContents(const base::FilePath& path,
return true;
}
ProcessMemory* PtraceClient::Memory() {
INITIALIZATION_STATE_DCHECK_VALID(initialized_);
return memory_.get();
}
PtraceClient::BrokeredMemory::BrokeredMemory(PtraceClient* client)
: ProcessMemory(), client_(client) {}
PtraceClient::BrokeredMemory::~BrokeredMemory() = default;
ssize_t PtraceClient::BrokeredMemory::ReadUpTo(VMAddress address,
size_t size,
void* buffer) const {
return client_->ReadUpTo(address, size, buffer);
}
ssize_t PtraceClient::ReadUpTo(VMAddress address,
size_t size,
void* buffer) const {
INITIALIZATION_STATE_DCHECK_VALID(initialized_);
char* buffer_c = reinterpret_cast<char*>(buffer);
PtraceBroker::Request request;
request.type = PtraceBroker::Request::kTypeReadMemory;
request.tid = pid_;
request.iov.base = address;
request.iov.size = size;
if (!LoggingWriteFile(sock_, &request, sizeof(request))) {
return false;
}
ssize_t total_read = 0;
while (size > 0) {
int32_t bytes_read;
if (!LoggingReadFileExactly(sock_, &bytes_read, sizeof(bytes_read))) {
return -1;
}
if (bytes_read < 0) {
ReceiveAndLogReadError(sock_, "PtraceBroker ReadMemory");
return -1;
}
if (bytes_read == 0) {
return total_read;
}
if (!LoggingReadFileExactly(sock_, buffer_c, bytes_read)) {
return -1;
}
size -= bytes_read;
buffer_c += bytes_read;
total_read += bytes_read;
}
return total_read;
}
bool PtraceClient::SendFilePath(const char* path, size_t length) {
if (!LoggingWriteFile(sock_, path, length)) {
return false;

44
util/linux/ptrace_client.h
View File

@ -17,10 +17,13 @@
#include <sys/types.h>
#include <memory>
#include "base/macros.h"
#include "util/linux/ptrace_connection.h"
#include "util/misc/address_types.h"
#include "util/misc/initialization_state_dcheck.h"
#include "util/process/process_memory.h"
namespace crashpad {
@ -43,26 +46,11 @@ class PtraceClient : public PtraceConnection {
//! ownership of the socket.
//! \param[in] pid The process ID of the process to form a PtraceConnection
//! with.
//! \param[in] try_direct_memory If `true` the client will attempt to support
//! memory reading operations by directly acessing the target process'
//! /proc/[pid]/mem file.
//! \return `true` on success. `false` on failure with a message logged.
bool Initialize(int sock, pid_t pid);
//! \brief Copies memory from the target process into a caller-provided buffer
//! in the current process.
//!
//! TODO(jperaza): In order for this to be usable, PtraceConnection will need
//! to surface it, possibly by inheriting from ProcessMemory, or providing a
//! method to return a ProcessMemory*.
//!
//! \param[in] address The address, in the target process' address space, of
//! the memory region to copy.
//! \param[in] size The size, in bytes, of the memory region to copy.
//! \a buffer must be at least this size.
//! \param[out] buffer The buffer into which the contents of the other
//! process' memory will be copied.
//!
//! \return `true` on success, with \a buffer filled appropriately. `false` on
//! failure, with a message logged.
bool Read(VMAddress address, size_t size, void* buffer);
bool Initialize(int sock, pid_t pid, bool try_direct_memory = true);
// PtraceConnection:
@ -72,10 +60,28 @@ class PtraceClient : public PtraceConnection {
bool GetThreadInfo(pid_t tid, ThreadInfo* info) override;
bool ReadFileContents(const base::FilePath& path,
std::string* contents) override;
ProcessMemory* Memory() override;
private:
class BrokeredMemory : public ProcessMemory {
public:
explicit BrokeredMemory(PtraceClient* client);
~BrokeredMemory();
ssize_t ReadUpTo(VMAddress address,
size_t size,
void* buffer) const override;
private:
PtraceClient* client_;
DISALLOW_COPY_AND_ASSIGN(BrokeredMemory);
};
ssize_t ReadUpTo(VMAddress address, size_t size, void* buffer) const;
bool SendFilePath(const char* path, size_t length);
std::unique_ptr<ProcessMemory> memory_;
int sock_;
pid_t pid_;
bool is_64_bit_;

7
util/linux/ptrace_connection.h
View File

@ -21,6 +21,7 @@
#include "base/files/file_path.h"
#include "util/linux/thread_info.h"
#include "util/process/process_memory.h"
namespace crashpad {
@ -57,6 +58,12 @@ class PtraceConnection {
//! \return `true` on success. `false` on failure with a message logged.
virtual bool ReadFileContents(const base::FilePath& path,
std::string* contents) = 0;
//! \brief Returns a memory reader for the connected process.
//!
//! The caller does not take ownership of the reader. The reader is valid for
//! the lifetime of the PtraceConnection that created it.
virtual ProcessMemory* Memory() = 0;
};
} // namespace crashpad

69
util/linux/ptracer.cc
View File

@ -375,10 +375,11 @@ bool Ptracer::GetThreadInfo(pid_t tid, ThreadInfo* info) {
can_log_);
}
bool Ptracer::ReadMemory(pid_t pid,
LinuxVMAddress address,
size_t size,
char* buffer) {
ssize_t Ptracer::ReadUpTo(pid_t pid,
LinuxVMAddress address,
size_t size,
char* buffer) {
size_t bytes_read = 0;
while (size > 0) {
errno = 0;
@ -386,46 +387,66 @@ bool Ptracer::ReadMemory(pid_t pid,
*reinterpret_cast<long*>(buffer) =
ptrace(PTRACE_PEEKDATA, pid, address, nullptr);
if (errno == EIO) {
ssize_t last_bytes = ReadLastBytes(pid, address, size, buffer);
return last_bytes >= 0 ? bytes_read + last_bytes : -1;
}
if (errno != 0) {
PLOG_IF(ERROR, can_log_) << "ptrace";
return false;
return -1;
}
size -= sizeof(long);
buffer += sizeof(long);
address += sizeof(long);
bytes_read += sizeof(long);
} else {
long word = ptrace(PTRACE_PEEKDATA, pid, address, nullptr);
if (errno == 0) {
memcpy(buffer, reinterpret_cast<char*>(&word), size);
return true;
return bytes_read + size;
}
if (errno != EIO) {
PLOG_IF(ERROR, can_log_);
return false;
}
// A read smaller than a word at the end of a mapping might spill over
// into unmapped memory. Try aligning the read so that the requested
// data is at the end of the word instead.
errno = 0;
word =
ptrace(PTRACE_PEEKDATA, pid, address - sizeof(word) + size, nullptr);
if (errno == 0) {
memcpy(
buffer, reinterpret_cast<char*>(&word) + sizeof(word) - size, size);
return true;
if (errno == EIO) {
ssize_t last_bytes = ReadLastBytes(pid, address, size, buffer);
return last_bytes >= 0 ? bytes_read + last_bytes : -1;
}
PLOG_IF(ERROR, can_log_);
return false;
return -1;
}
}
return true;
return bytes_read;
}
// Handles an EIO by reading at most size bytes from address into buffer if
// address was within a word of a possible page boundary, by aligning to read
// the last word of the page and extracting the desired bytes.
ssize_t Ptracer::ReadLastBytes(pid_t pid,
LinuxVMAddress address,
size_t size,
char* buffer) {
LinuxVMAddress aligned = ((address + 4095) & ~4095) - sizeof(long);
if (aligned >= address || aligned == address - sizeof(long)) {
PLOG_IF(ERROR, can_log_) << "ptrace";
return -1;
}
DCHECK_GT(aligned, address - sizeof(long));
errno = 0;
long word = ptrace(PTRACE_PEEKDATA, pid, aligned, nullptr);
if (errno != 0) {
PLOG_IF(ERROR, can_log_) << "ptrace";
return -1;
}
size_t bytes_read = address - aligned;
size_t last_bytes = std::min(sizeof(long) - bytes_read, size);
memcpy(buffer, reinterpret_cast<char*>(&word) + bytes_read, last_bytes);
return last_bytes;
}
} // namespace crashpad

19
util/linux/ptracer.h
View File

@ -72,20 +72,29 @@ class Ptracer {
bool GetThreadInfo(pid_t tid, ThreadInfo* info);
//! \brief Uses `ptrace` to read memory from the process with process ID \a
//! pid.
//! pid, up to a maximum number of bytes.
//!
//! The target process should already be attached before calling this method.
//! \see ScopedPtraceAttach
//!
//! \param[in] pid The process ID whose memory to read.
//! \param[in] address The base address of the region to read.
//! \param[in] size The size of the memory region to read.
//! \param[in] size The size of the memory region to read. \a buffer must be
//! at least this size.
//! \param[out] buffer The buffer to fill with the data read.
//! \return `true` on success. `false` on failure with a message logged, if
//! enabled.
bool ReadMemory(pid_t pid, LinuxVMAddress address, size_t size, char* buffer);
//! \return the number of bytes read, 0 if there are no more bytes to read, or
//! -1 on failure with a message logged if logging is enabled.
ssize_t ReadUpTo(pid_t pid,
LinuxVMAddress address,
size_t size,
char* buffer);
private:
ssize_t ReadLastBytes(pid_t pid,
LinuxVMAddress address,
size_t size,
char* buffer);
bool is_64_bit_;
bool can_log_;
InitializationStateDcheck initialized_;

3
util/process/process_memory.h
View File

@ -78,9 +78,10 @@ class ProcessMemory {
return ReadCStringInternal(address, true, size, string);
}
virtual ~ProcessMemory() = default;
protected:
ProcessMemory() = default;
~ProcessMemory() = default;
private:
//! \brief Copies memory from the target process into a caller-provided buffer