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handler/mac: Log a warning when an exception message has a suspicious

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origin.

This adds AuditPIDFromMachMessageTrailer() to get the process ID of a
Mach message’s sender. Exception messages are considered suspicious when
not sent by the kernel or the exception process.

TEST=crashpad_util_test
R=rsesek@chromium.org

Review URL: https://codereview.chromium.org/1001943002
This commit is contained in:
Mark Mentovai 2015-03-12 14:00:38 -04:00
parent 995e762a45
commit 5f19d639e1
9 changed files with 186 additions and 46 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

17
handler/mac/crash_report_exception_handler.cc
View File

@ -29,6 +29,7 @@
#include "util/mach/exc_client_variants.h"
#include "util/mach/exception_behaviors.h"
#include "util/mach/mach_extensions.h"
#include "util/mach/mach_message.h"
#include "util/mach/scoped_task_suspend.h"
#include "util/misc/tri_state.h"
#include "util/misc/uuid.h"
@ -119,6 +120,22 @@ kern_return_t CrashReportExceptionHandler::CatchMachException(
return KERN_FAILURE;
}
// Check for suspicious message sources. A suspicious exception message comes
// from a source other than the kernel or the process that the exception
// purportedly occurred in.
//
// TODO(mark): Consider exceptions outside of the range (0, 32) from the
// kernel to be suspicious, and exceptions other than kMachExceptionSimulated
// from the process itself to be suspicious.
pid_t audit_pid = AuditPIDFromMachMessageTrailer(trailer);
if (audit_pid != -1 && audit_pid != 0) {
pid_t exception_pid = process_snapshot.ProcessID();
if (exception_pid != audit_pid) {
LOG(WARNING) << "exception for pid " << exception_pid << " sent by pid "
<< audit_pid;
}
}
CrashpadInfoClientOptions client_options;
process_snapshot.GetCrashpadOptions(&client_options);

5
handler/mac/exception_handler_server.cc
View File

@ -26,8 +26,7 @@ namespace crashpad {
namespace {
class ExceptionHandlerServerRun
: public UniversalMachExcServer::Interface,
class ExceptionHandlerServerRun : public UniversalMachExcServer::Interface,
public NotifyServer::Interface {
public:
ExceptionHandlerServerRun(
@ -100,7 +99,7 @@ class ExceptionHandlerServerRun
mach_msg_return_t mr =
MachMessageServer::Run(&composite_mach_message_server_,
server_port_set,
MACH_MSG_OPTION_NONE,
kMachMessageReceiveAuditTrailer,
MachMessageServer::kOneShot,
MachMessageServer::kReceiveLargeIgnore,
kMachMessageTimeoutWaitIndefinitely);

4
util/mach/exception_ports_test.cc
View File

@ -197,6 +197,8 @@ class TestExceptionPorts : public MachMultiprocess,
SetExpectedChildTermination(kTerminationSignal, signal);
}
EXPECT_EQ(0, AuditPIDFromMachMessageTrailer(trailer));
return ExcServerSuccessfulReturnValue(behavior, false);
}
@ -443,7 +445,7 @@ class TestExceptionPorts : public MachMultiprocess,
kern_return_t kr =
MachMessageServer::Run(&universal_mach_exc_server,
local_port,
MACH_MSG_OPTION_NONE,
kMachMessageReceiveAuditTrailer,
MachMessageServer::kOneShot,
MachMessageServer::kReceiveLargeError,
kTimeoutMs);

36
util/mach/mach_message.cc
View File

@ -14,9 +14,13 @@
#include "util/mach/mach_message.h"
#include <AvailabilityMacros.h>
#include <bsm/libbsm.h>
#include <limits>
#include "base/basictypes.h"
#include "base/logging.h"
#include "util/misc/clock.h"
namespace crashpad {
@ -213,4 +217,36 @@ const mach_msg_trailer_t* MachMessageTrailerFromHeader(
return reinterpret_cast<const mach_msg_trailer_t*>(trailer_address);
}
pid_t AuditPIDFromMachMessageTrailer(const mach_msg_trailer_t* trailer) {
if (trailer->msgh_trailer_type != MACH_MSG_TRAILER_FORMAT_0) {
LOG(ERROR) << "unexpected msgh_trailer_type " << trailer->msgh_trailer_type;
return -1;
}
if (trailer->msgh_trailer_size <
REQUESTED_TRAILER_SIZE(kMachMessageReceiveAuditTrailer)) {
LOG(ERROR) << "small msgh_trailer_size " << trailer->msgh_trailer_size;
return -1;
}
const mach_msg_audit_trailer_t* audit_trailer =
reinterpret_cast<const mach_msg_audit_trailer_t*>(trailer);
#if MAC_OS_X_VERSION_MIN_REQUIRED < MAC_OS_X_VERSION_10_8
pid_t audit_pid;
audit_token_to_au32(audit_trailer->msgh_audit,
nullptr,
nullptr,
nullptr,
nullptr,
nullptr,
&audit_pid,
nullptr,
nullptr);
#else
pid_t audit_pid = audit_token_to_pid(audit_trailer->msgh_audit);
#endif
return audit_pid;
}
} // namespace crashpad

26
util/mach/mach_message.h
View File

@ -17,9 +17,19 @@
#include <mach/mach.h>
#include <stdint.h>
#include <sys/types.h>
namespace crashpad {
//! \brief A Mach message option specifying that an audit trailer should be
//! delivered during a receive operation.
//!
//! This constant is provided because the macros normally used to request this
//! behavior are cumbersome.
const mach_msg_option_t kMachMessageReceiveAuditTrailer =
MACH_RCV_TRAILER_TYPE(MACH_MSG_TRAILER_FORMAT_0) |
MACH_RCV_TRAILER_ELEMENTS(MACH_RCV_TRAILER_AUDIT);
//! \brief Special constants used as `mach_msg_timeout_t` values.
enum : mach_msg_timeout_t {
//! \brief When passed to MachMessageDeadlineFromTimeout(), that function will
@ -148,6 +158,22 @@ void SetMIGReplyError(mach_msg_header_t* out_header, kern_return_t error);
const mach_msg_trailer_t* MachMessageTrailerFromHeader(
const mach_msg_header_t* header);
//! \brief Returns the process ID of a Mach message’s sender from its audit
//! trailer.
//!
//! For the audit trailer to be present, the message must have been received
//! with #kMachMessageReceiveAuditTrailer or its macro equivalent specified in
//! the receive options.
//!
//! If the kernel is the message’s sender, a process ID of `0` will be returned.
//!
//! \param[in] trailer The trailer received with a Mach message.
//!
//! \return The process ID of the message’s sender, or `-1` on failure with a
//! message logged. It is considered a failure for \a trailer to not contain
//! audit information.
pid_t AuditPIDFromMachMessageTrailer(const mach_msg_trailer_t* trailer);
} // namespace crashpad
#endif // CRASHPAD_UTIL_MACH_MACH_MESSAGE_H_

44
util/mach/mach_message_test.cc
View File

@ -14,9 +14,13 @@
#include "util/mach/mach_message.h"
#include <unistd.h>
#include "base/basictypes.h"
#include "base/mac/scoped_mach_port.h"
#include "gtest/gtest.h"
#include "util/mach/mach_extensions.h"
#include "util/test/mac/mach_errors.h"
namespace crashpad {
namespace test {
@ -104,6 +108,46 @@ TEST(MachMessage, MachMessageTrailerFromHeader) {
EXPECT_EQ(&test.receive.trailer, MachMessageTrailerFromHeader(&test.receive));
}
TEST(MachMessage, AuditPIDFromMachMessageTrailer) {
base::mac::ScopedMachReceiveRight port(NewMachPort(MACH_PORT_RIGHT_RECEIVE));
ASSERT_NE(kMachPortNull, port);
mach_msg_empty_send_t send = {};
send.header.msgh_bits = MACH_MSGH_BITS(MACH_MSG_TYPE_MAKE_SEND_ONCE, 0);
send.header.msgh_size = sizeof(send);
send.header.msgh_remote_port = port;
mach_msg_return_t mr =
MachMessageWithDeadline(&send.header,
MACH_SEND_MSG,
0,
MACH_PORT_NULL,
kMachMessageDeadlineNonblocking,
MACH_PORT_NULL,
false);
ASSERT_EQ(MACH_MSG_SUCCESS, mr)
<< MachErrorMessage(mr, "MachMessageWithDeadline send");
struct EmptyReceiveMessageWithAuditTrailer : public mach_msg_empty_send_t {
union {
mach_msg_trailer_t trailer;
mach_msg_audit_trailer_t audit_trailer;
};
};
EmptyReceiveMessageWithAuditTrailer receive;
mr = MachMessageWithDeadline(&receive.header,
MACH_RCV_MSG | kMachMessageReceiveAuditTrailer,
sizeof(receive),
port,
kMachMessageDeadlineNonblocking,
MACH_PORT_NULL,
false);
ASSERT_EQ(MACH_MSG_SUCCESS, mr)
<< MachErrorMessage(mr, "MachMessageWithDeadline receive");
EXPECT_EQ(getpid(), AuditPIDFromMachMessageTrailer(&receive.trailer));
}
} // namespace
} // namespace test
} // namespace crashpad

61
util/mach/notify_server_test.cc
View File

@ -30,7 +30,6 @@ namespace {
using testing::AllOf;
using testing::Eq;
using testing::Invoke;
using testing::Ne;
using testing::Pointee;
using testing::ResultOf;
using testing::Return;
@ -239,7 +238,7 @@ class NotifyServerTestBase : public testing::Test,
mach_msg_return_t mr =
MachMessageServer::Run(&notify_server,
ServerPort(),
MACH_MSG_OPTION_NONE,
kMachMessageReceiveAuditTrailer,
MachMessageServer::kPersistent,
MachMessageServer::kReceiveLargeError,
kMachMessageTimeoutNonblocking);
@ -315,12 +314,14 @@ TEST_F(NotifyServerTest, MachNotifyPortDeleted) {
SendOnceRightFromReceiveRight(receive_right));
ASSERT_NE(kMachPortNull, send_once_right);
ASSERT_TRUE(RequestMachPortNotification(
send_once_right, MACH_NOTIFY_DEAD_NAME, 0));
ASSERT_TRUE(
RequestMachPortNotification(send_once_right, MACH_NOTIFY_DEAD_NAME, 0));
EXPECT_CALL(*this, DoMachNotifyPortDeleted(ServerPort(),
EXPECT_CALL(
*this,
DoMachNotifyPortDeleted(ServerPort(),
send_once_right.get(),
Ne(nullptr)))
ResultOf(AuditPIDFromMachMessageTrailer, 0)))
.WillOnce(Return(MIG_NO_REPLY))
.RetiresOnSaturation();
@ -339,9 +340,11 @@ TEST_F(NotifyServerTest, MachNotifyPortDestroyed) {
ASSERT_TRUE(RequestMachPortNotification(
receive_right, MACH_NOTIFY_PORT_DESTROYED, 0));
EXPECT_CALL(*this, DoMachNotifyPortDestroyed(ServerPort(),
EXPECT_CALL(
*this,
DoMachNotifyPortDestroyed(ServerPort(),
ResultOf(IsReceiveRight, true),
Ne(nullptr),
ResultOf(AuditPIDFromMachMessageTrailer, 0),
Pointee(Eq(false))))
.WillOnce(DoAll(SetArgPointee<3>(true), Return(MIG_NO_REPLY)))
.RetiresOnSaturation();
@ -371,10 +374,12 @@ TEST_F(NotifyServerTest, MachNotifyNoSenders_NoSendRight) {
NewMachPort(MACH_PORT_RIGHT_RECEIVE));
ASSERT_NE(kMachPortNull, receive_right);
ASSERT_TRUE(RequestMachPortNotification(
receive_right, MACH_NOTIFY_NO_SENDERS, 0));
ASSERT_TRUE(
RequestMachPortNotification(receive_right, MACH_NOTIFY_NO_SENDERS, 0));
EXPECT_CALL(*this, DoMachNotifyNoSenders(ServerPort(), 0, Ne(nullptr)))
EXPECT_CALL(*this,
DoMachNotifyNoSenders(
ServerPort(), 0, ResultOf(AuditPIDFromMachMessageTrailer, 0)))
.WillOnce(Return(MIG_NO_REPLY))
.RetiresOnSaturation();
@ -393,10 +398,12 @@ TEST_F(NotifyServerTest, MachNotifyNoSenders_SendRightDeallocated) {
SendRightFromReceiveRight(receive_right));
ASSERT_NE(kMachPortNull, send_right);
ASSERT_TRUE(RequestMachPortNotification(
receive_right, MACH_NOTIFY_NO_SENDERS, 1));
ASSERT_TRUE(
RequestMachPortNotification(receive_right, MACH_NOTIFY_NO_SENDERS, 1));
EXPECT_CALL(*this, DoMachNotifyNoSenders(ServerPort(), 1, Ne(nullptr)))
EXPECT_CALL(*this,
DoMachNotifyNoSenders(
ServerPort(), 1, ResultOf(AuditPIDFromMachMessageTrailer, 0)))
.WillOnce(Return(MIG_NO_REPLY))
.RetiresOnSaturation();
@ -420,8 +427,8 @@ TEST_F(NotifyServerTest, MachNotifyNoSenders_NoNotification) {
SendRightFromReceiveRight(receive_right));
ASSERT_NE(kMachPortNull, send_right_1);
ASSERT_TRUE(RequestMachPortNotification(
receive_right, MACH_NOTIFY_NO_SENDERS, 1));
ASSERT_TRUE(
RequestMachPortNotification(receive_right, MACH_NOTIFY_NO_SENDERS, 1));
send_right_1.reset();
@ -438,7 +445,9 @@ TEST_F(NotifyServerTest, MachNotifySendOnce_ExplicitDeallocation) {
SendOnceRightFromReceiveRight(ServerPort()));
ASSERT_NE(kMachPortNull, send_once_right);
EXPECT_CALL(*this, DoMachNotifySendOnce(ServerPort(), Ne(nullptr)))
EXPECT_CALL(*this,
DoMachNotifySendOnce(ServerPort(),
ResultOf(AuditPIDFromMachMessageTrailer, 0)))
.WillOnce(Return(MIG_NO_REPLY))
.RetiresOnSaturation();
@ -470,7 +479,9 @@ TEST_F(NotifyServerTest, MachNotifySendOnce_ImplicitDeallocation) {
MACH_PORT_NULL);
ASSERT_EQ(MACH_MSG_SUCCESS, mr) << MachErrorMessage(mr, "mach_msg");
EXPECT_CALL(*this, DoMachNotifySendOnce(ServerPort(), Ne(nullptr)))
EXPECT_CALL(*this,
DoMachNotifySendOnce(ServerPort(),
ResultOf(AuditPIDFromMachMessageTrailer, 0)))
.WillOnce(Return(MIG_NO_REPLY))
.RetiresOnSaturation();
@ -491,8 +502,8 @@ TEST_F(NotifyServerTest, MachNotifyDeadName) {
SendOnceRightFromReceiveRight(receive_right));
ASSERT_NE(kMachPortNull, send_once_right);
ASSERT_TRUE(RequestMachPortNotification(
send_once_right, MACH_NOTIFY_DEAD_NAME, 0));
ASSERT_TRUE(
RequestMachPortNotification(send_once_right, MACH_NOTIFY_DEAD_NAME, 0));
// send_once_right becomes a dead name with the send-once right’s original
// user reference count of 1, but the dead-name notification increments the
@ -502,9 +513,9 @@ TEST_F(NotifyServerTest, MachNotifyDeadName) {
DoMachNotifyDeadName(ServerPort(),
AllOf(send_once_right.get(),
ResultOf(DeadNameRightRefCount, 2)),
Ne(nullptr)))
.WillOnce(DoAll(WithArg<1>(Invoke(MachPortDeallocate)),
Return(MIG_NO_REPLY)))
ResultOf(AuditPIDFromMachMessageTrailer, 0)))
.WillOnce(
DoAll(WithArg<1>(Invoke(MachPortDeallocate)), Return(MIG_NO_REPLY)))
.RetiresOnSaturation();
receive_right.reset();
@ -529,8 +540,8 @@ TEST_F(NotifyServerTest, MachNotifyDeadName_NoNotification) {
SendOnceRightFromReceiveRight(receive_right));
ASSERT_NE(kMachPortNull, send_once_right);
ASSERT_TRUE(RequestMachPortNotification(
send_once_right, MACH_NOTIFY_DEAD_NAME, 0));
ASSERT_TRUE(
RequestMachPortNotification(send_once_right, MACH_NOTIFY_DEAD_NAME, 0));
RunServer();

12
util/test/mac/mach_multiprocess.cc
View File

@ -28,6 +28,7 @@
#include "gtest/gtest.h"
#include "util/file/file_io.h"
#include "util/mach/mach_extensions.h"
#include "util/mach/mach_message.h"
#include "util/misc/scoped_forbid_return.h"
#include "util/test/errors.h"
#include "util/test/mac/mach_errors.h"
@ -40,7 +41,10 @@ struct SendHelloMessage : public mach_msg_base_t {
};
struct ReceiveHelloMessage : public SendHelloMessage {
union {
mach_msg_trailer_t trailer;
mach_msg_audit_trailer_t audit_trailer;
};
};
} // namespace
@ -120,10 +124,8 @@ task_t MachMultiprocess::ChildTask() const {
void MachMultiprocess::MultiprocessParent() {
ReceiveHelloMessage message = {};
kern_return_t kr =
mach_msg(&message.header,
MACH_RCV_MSG | MACH_RCV_TRAILER_TYPE(MACH_MSG_TRAILER_FORMAT_0) |
MACH_RCV_TRAILER_ELEMENTS(MACH_RCV_TRAILER_AUDIT),
kern_return_t kr = mach_msg(&message.header,
MACH_RCV_MSG | kMachMessageReceiveAuditTrailer,
0,
sizeof(message),
info_->local_port,
@ -186,6 +188,8 @@ void MachMultiprocess::MultiprocessParent() {
EXPECT_EQ(getgid(), audit_rgid);
ASSERT_EQ(ChildPID(), audit_pid);
ASSERT_EQ(ChildPID(), AuditPIDFromMachMessageTrailer(&message.trailer));
auditinfo_addr_t audit_info;
int rv = getaudit_addr(&audit_info, sizeof(audit_info));
ASSERT_EQ(0, rv) << ErrnoMessage("getaudit_addr");

1
util/util.gyp
View File

@ -199,6 +199,7 @@
'$(SDKROOT)/System/Library/Frameworks/CoreFoundation.framework',
'$(SDKROOT)/System/Library/Frameworks/Foundation.framework',
'$(SDKROOT)/System/Library/Frameworks/IOKit.framework',
'$(SDKROOT)/usr/lib/libbsm.dylib',
],
},
}],