// Copyright 2014 The Crashpad Authors
//
// 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 "util/mach/mach_message.h"
#include <Availability.h>
#include <limits>
#include "base/apple/mach_logging.h"
#include "base/logging.h"
#include "build/build_config.h"
#include "util/misc/clock.h"
#include "util/misc/implicit_cast.h"
#if BUILDFLAG(IS_MAC)
#include <bsm/libbsm.h>
#endif // BUILDFLAG(IS_MAC)
namespace crashpad {
namespace {
constexpr int kNanosecondsPerMillisecond = 1E6;
// TimerRunning() determines whether |deadline| has passed. If |deadline| is
// kMachMessageDeadlineWaitIndefinitely, |*timeout_options| is set to
// MACH_MSG_OPTION_NONE, |*remaining_ms| is set to MACH_MSG_TIMEOUT_NONE, and
// this function returns true. When used with mach_msg(), this will cause
// indefinite waiting. In any other case, |*timeout_options| is set to
// MACH_SEND_TIMEOUT | MACH_RCV_TIMEOUT, so mach_msg() will enforce a timeout
// specified by |*remaining_ms|. If |deadline| is in the future, |*remaining_ms|
// is set to the number of milliseconds remaining, which will always be a
// positive value, and this function returns true. If |deadline| is
// kMachMessageDeadlineNonblocking (indicating that no timer is in effect),
// |*remaining_ms| is set to zero and this function returns true. Otherwise,
// this function sets |*remaining_ms| to zero and returns false.
bool TimerRunning(uint64_t deadline,
mach_msg_timeout_t* remaining_ms,
mach_msg_option_t* timeout_options) {
if (deadline == kMachMessageDeadlineWaitIndefinitely) {
*remaining_ms = MACH_MSG_TIMEOUT_NONE;
*timeout_options = MACH_MSG_OPTION_NONE;
return true;
}
*timeout_options = MACH_SEND_TIMEOUT | MACH_RCV_TIMEOUT;
if (deadline == kMachMessageDeadlineNonblocking) {
*remaining_ms = 0;
return true;
}
uint64_t now = ClockMonotonicNanoseconds();
if (now >= deadline) {
*remaining_ms = 0;
} else {
uint64_t remaining = deadline - now;
// Round to the nearest millisecond, taking care not to overflow.
constexpr int kHalfMillisecondInNanoseconds =
kNanosecondsPerMillisecond / 2;
if (remaining <=
std::numeric_limits<uint64_t>::max() - kHalfMillisecondInNanoseconds) {
*remaining_ms = (remaining + kHalfMillisecondInNanoseconds) /
kNanosecondsPerMillisecond;
} else {
*remaining_ms = remaining / kNanosecondsPerMillisecond;
}
}
return *remaining_ms != 0;
}
// This is an internal implementation detail of MachMessageWithDeadline(). It
// determines whether |deadline| has expired, and what timeout value and
// timeout-related options to pass to mach_msg() based on the value of
// |deadline|. mach_msg() will only be called if TimerRunning() returns true or
// if run_even_if_expired is true.
mach_msg_return_t MachMessageWithDeadlineInternal(mach_msg_header_t* message,
mach_msg_option_t options,
mach_msg_size_t receive_size,
mach_port_name_t receive_port,
MachMessageDeadline deadline,
mach_port_name_t notify_port,
bool run_even_if_expired) {
mach_msg_timeout_t remaining_ms;
mach_msg_option_t timeout_options;
if (!TimerRunning(deadline, &remaining_ms, &timeout_options) &&
!run_even_if_expired) {
// Simulate the timed-out return values from mach_msg().
if (options & MACH_SEND_MSG) {
return MACH_SEND_TIMED_OUT;
}
if (options & MACH_RCV_MSG) {
return MACH_RCV_TIMED_OUT;
}
return MACH_MSG_SUCCESS;
}
// Turn off the passed-in timeout bits and replace them with the ones from
// TimerRunning(). Get the send_size value from message->msgh_size if sending
// a message.
return mach_msg(
message,
(options & ~(MACH_SEND_TIMEOUT | MACH_RCV_TIMEOUT)) | timeout_options,
options & MACH_SEND_MSG ? message->msgh_size : 0,
receive_size,
receive_port,
remaining_ms,
notify_port);
}
} // namespace
MachMessageDeadline MachMessageDeadlineFromTimeout(
mach_msg_timeout_t timeout_ms) {
switch (timeout_ms) {
case kMachMessageTimeoutNonblocking:
return kMachMessageDeadlineNonblocking;
case kMachMessageTimeoutWaitIndefinitely:
return kMachMessageDeadlineWaitIndefinitely;
default:
return ClockMonotonicNanoseconds() +
implicit_cast<uint64_t>(timeout_ms) * kNanosecondsPerMillisecond;
}
}
mach_msg_return_t MachMessageWithDeadline(mach_msg_header_t* message,
mach_msg_option_t options,
mach_msg_size_t receive_size,
mach_port_name_t receive_port,
MachMessageDeadline deadline,
mach_port_name_t notify_port,
bool run_even_if_expired) {
// mach_msg() actaully does return MACH_MSG_SUCCESS when not asked to send or
// receive anything. See 10.9.5 xnu-1504.15.3/osfmk/ipc/mach_msg.c
// mach_msg_overwrite_trap().
mach_msg_return_t mr = MACH_MSG_SUCCESS;
// Break up the send and receive into separate operations, so that the timeout
// can be recomputed from the deadline for each. Otherwise, the computed
// timeout will apply individually to the send and then to the receive, and
// the desired deadline could be exceeded.
//
// During sends, always set MACH_SEND_INTERRUPT, and during receives, always
// set MACH_RCV_INTERRUPT. If the caller didn’t specify these options, the
// calls will be retried with a recomputed deadline. If these bits weren’t
// set, the libsyscall wrapper (10.9.5
// xnu-2422.115.4/libsyscall/mach/mach_msg.c mach_msg() would restart
// interrupted calls with the original timeout value computed from the
// deadline, which would no longer correspond to the actual deadline. If the
// caller did specify these bits, don’t restart anything, because the caller
// wants to be notified of any interrupted calls.
if (options & MACH_SEND_MSG) {
do {
mr = MachMessageWithDeadlineInternal(
message,
(options & ~MACH_RCV_MSG) | MACH_SEND_INTERRUPT,
0,
MACH_PORT_NULL,
deadline,
notify_port,
run_even_if_expired);
} while (mr == MACH_SEND_INTERRUPTED && !(options & MACH_SEND_INTERRUPT));
if (mr != MACH_MSG_SUCCESS) {
return mr;
}
}
if (options & MACH_RCV_MSG) {
do {
mr = MachMessageWithDeadlineInternal(
message,
(options & ~MACH_SEND_MSG) | MACH_RCV_INTERRUPT,
receive_size,
receive_port,
deadline,
notify_port,
run_even_if_expired);
} while (mr == MACH_RCV_INTERRUPTED && !(options & MACH_RCV_INTERRUPT));
}
return mr;
}
void PrepareMIGReplyFromRequest(const mach_msg_header_t* in_header,
mach_msg_header_t* out_header) {
out_header->msgh_bits =
MACH_MSGH_BITS(MACH_MSGH_BITS_REMOTE(in_header->msgh_bits), 0);
out_header->msgh_size = sizeof(mig_reply_error_t);
out_header->msgh_remote_port = in_header->msgh_remote_port;
out_header->msgh_local_port = MACH_PORT_NULL;
out_header->msgh_reserved = 0;
out_header->msgh_id = in_header->msgh_id + 100;
reinterpret_cast<mig_reply_error_t*>(out_header)->NDR = NDR_record;
}
void SetMIGReplyError(mach_msg_header_t* out_header, kern_return_t error) {
reinterpret_cast<mig_reply_error_t*>(out_header)->RetCode = error;
}
const mach_msg_trailer_t* MachMessageTrailerFromHeader(
const mach_msg_header_t* header) {
vm_address_t header_address = reinterpret_cast<vm_address_t>(header);
vm_address_t trailer_address = header_address + round_msg(header->msgh_size);
return reinterpret_cast<const mach_msg_trailer_t*>(trailer_address);
}
bool MachMessageDestroyReceivedPort(mach_port_t port,
mach_msg_type_name_t port_right_type) {
// This implements a subset of 10.10.5
// xnu-2782.40.9/libsyscall/mach/mach_msg.c mach_msg_destroy_port() that deals
// only with port rights that can be received in Mach messages.
switch (port_right_type) {
case MACH_MSG_TYPE_PORT_RECEIVE: {
kern_return_t kr = mach_port_mod_refs(
mach_task_self(), port, MACH_PORT_RIGHT_RECEIVE, -1);
if (kr != KERN_SUCCESS) {
MACH_LOG(ERROR, kr) << "mach_port_mod_refs";
return false;
}
return true;
}
case MACH_MSG_TYPE_PORT_SEND:
case MACH_MSG_TYPE_PORT_SEND_ONCE: {
kern_return_t kr = mach_port_deallocate(mach_task_self(), port);
if (kr != KERN_SUCCESS) {
MACH_LOG(ERROR, kr) << "mach_port_deallocate";
return false;
}
return true;
}
default: {
LOG(ERROR) << "unexpected port right type " << port_right_type;
return false;
}
}
}
#if BUILDFLAG(IS_MAC)
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_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;
}
#endif // BUILDFLAG(IS_MAC)
} // namespace crashpad
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