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Merge pull request #6830 from mikezhang1234567890/osxddr
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Pass task port for core dump using IPC
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@babsingh
babsingh committed Dec 7, 2022
2 parents a932903 + 809f1ba commit a14c295
Showing 1 changed file with 143 additions and 11 deletions.
154 changes: 143 additions & 11 deletions port/osx/omrosdump.c
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Original file line number Diff line number Diff line change
Expand Up @@ -99,6 +99,110 @@ static kern_return_t coredump_to_file(mach_port_t, pid_t);
static kern_return_t list_thread_commands(mach_port_t, struct thread_command_full_64 **, natural_t *);
static kern_return_t list_segment_commands(mach_port_t, struct segment_command_64 **, natural_t *);

/**
* Create a mach port with send and receive rights that can be used to receive
* messages from other processes.
* For the core dump, the process to be dumped creates a child process which
* does the work of creating the core dump. A message port needs to be created
* on both the parent and child process. The ports are used in the core dump
* process as follows:
* First the parent creates a port for messaging. This message port is passed
* to the child via bootstrap port inheritance.
* The child process needs to create a port in order to receive task port
* rights from the parent. The child sends the rights to its new messaging port
* to the parent via the parent's messaging port it receives.
* Finally, the parent process receives the messaging port rights from the
* child process and sends the task port rights to the child using that port.
*
* @param[out] port the newly created port
*
* @return KERN_SUCCESS on success, error code from kernel on failure
*/
static kern_return_t
setup_msg_port(mach_port_t *port)
{
kern_return_t kr = KERN_SUCCESS;
mach_port_t messagePort = MACH_PORT_NULL;

kr = mach_port_allocate(mach_task_self(), MACH_PORT_RIGHT_RECEIVE, &messagePort);
if (KERN_SUCCESS != kr) {
mach_error("failed to create port:\n", kr);
return kr;
}
kr = mach_port_insert_right(mach_task_self(), messagePort, messagePort, MACH_MSG_TYPE_MAKE_SEND);
if (KERN_SUCCESS != kr) {
mach_error("failed to add send right to created port:\n", kr);
return kr;
}
*port = messagePort;
return kr;
}

/**
* Send a port right to the specified messaging port on another process.
*
* @param[in] messagePort the mach port in a remote process to send the port right to
* @param[in] toSend the port right to be sent
*
* @return KERN_SUCCESS on success, error code from kernel on failure
*/
static kern_return_t
send_port_msg(mach_port_t messagePort, mach_port_t toSend)
{
kern_return_t kr = KERN_SUCCESS;
struct {
mach_msg_header_t header;
mach_msg_body_t body;
mach_msg_port_descriptor_t task_port;
} msg;

memset(&msg, 0, sizeof(msg));
msg.header.msgh_remote_port = messagePort;
msg.header.msgh_local_port = MACH_PORT_NULL;
msg.header.msgh_bits = MACH_MSGH_BITS(MACH_MSG_TYPE_COPY_SEND, 0) | MACH_MSGH_BITS_COMPLEX;
msg.header.msgh_size = sizeof(msg);
msg.body.msgh_descriptor_count = 1;
msg.task_port.name = toSend;
msg.task_port.disposition = MACH_MSG_TYPE_COPY_SEND;
msg.task_port.type = MACH_MSG_PORT_DESCRIPTOR;

kr = mach_msg_send(&msg.header);
if (KERN_SUCCESS != kr) {
mach_error("failed to send msg over mach port:\n", kr);
}
return kr;
}

/**
* Receive a message on the specified port containing a port right from another
* process.
*
* @param[in] messagePort the mach port in a remote process which sends us the port right
* @param[out] toReceive the port right retrieved from the message or MACH_PORT_NULL in case of failure
*
* @return KERN_SUCCESS on success, error code from kernel on failure
*/
static kern_return_t
recv_port_msg(mach_port_t messagePort, mach_port_t *toReceive)
{
kern_return_t kr = KERN_SUCCESS;
struct {
mach_msg_header_t header;
mach_msg_body_t body;
mach_msg_port_descriptor_t task_port;
mach_msg_trailer_t trailer;
} msg;

kr = mach_msg(&msg.header, MACH_RCV_MSG, 0, sizeof(msg), messagePort, MACH_MSG_TIMEOUT_NONE, MACH_PORT_NULL);
if (kr != KERN_SUCCESS) {
mach_error("Can't recieve mach message\n", kr);
*toReceive = MACH_PORT_NULL;
} else {
*toReceive = msg.task_port.name;
}
return kr;
}

static kern_return_t
coredump_to_file(mach_port_t task_port, pid_t pid)
{
Expand Down Expand Up @@ -494,7 +598,8 @@ omrdump_create(struct OMRPortLibrary *portLibrary, char *filename, char *dumpTyp
pid_t child_pid = 0;
char *lastSep = NULL;
kern_return_t kr = KERN_SUCCESS;
mach_port_t pass_port = MACH_PORT_NULL;
mach_port_t parent_msg_port = MACH_PORT_NULL;
mach_port_t child_msg_port = MACH_PORT_NULL;
mach_port_t special_port = MACH_PORT_NULL;

/* filename cannot be null */
Expand All @@ -512,26 +617,42 @@ omrdump_create(struct OMRPortLibrary *portLibrary, char *filename, char *dumpTyp
strncpy(corefile_name, filename, PATH_MAX);
}

/* save the original special port so we can restore it after using it to pass the task port */
/* save the original special port so we can restore it after using it to pass a message port */
kr = task_get_bootstrap_port(mach_task_self(), &special_port);
if (KERN_SUCCESS != kr) {
mach_error("failed get special port:\n", kr);
goto done;
}
pass_port = mach_task_self();
/* pass parent task port to child through special port inheritance */
kr = task_set_bootstrap_port(mach_task_self(), pass_port);
/* set up a message port and pass to child through special port inheritance */
kr = setup_msg_port(&parent_msg_port);
if (KERN_SUCCESS != kr) {
goto done;
}
kr = task_set_bootstrap_port(mach_task_self(), parent_msg_port);
if (KERN_SUCCESS != kr) {
mach_error("failed set special port:\n", kr);
goto done;
}

child_pid = fork();
if (0 == child_pid) { /* in child process */
kr = task_get_bootstrap_port(mach_task_self(), &pass_port);
kr = task_get_bootstrap_port(mach_task_self(), &parent_msg_port);
if (KERN_SUCCESS != kr) {
mach_error("failed get special port:\n", kr);
} else {
/* set up port to receive message from parent, then get task port */
kr = setup_msg_port(&child_msg_port);
if (KERN_SUCCESS != kr) {
goto childdone;
}
kr = send_port_msg(parent_msg_port, child_msg_port);
if (KERN_SUCCESS != kr) {
goto childdone;
}
kr = recv_port_msg(child_msg_port, &special_port);
if (KERN_SUCCESS != kr) {
goto childdone;
}
/* Move to specified folder before dumping */
if (NULL != lastSep) {
/* keep separator for cases such as when the path is '/' */
Expand All @@ -540,22 +661,33 @@ omrdump_create(struct OMRPortLibrary *portLibrary, char *filename, char *dumpTyp
perror("failed to change directories, attempting to create dump in current dir");
}
}
kr = coredump_to_file(pass_port, parent_pid);
kr = coredump_to_file(special_port, parent_pid);
}
childdone:
raise(SIGKILL); /* kill child process without running any exit procedures */
} else if (child_pid < 0) { /* fork failed */
perror("forking for core dump failed");
} else { /* in parent process */
waitpid(child_pid, NULL, 0);
/* restore special port to original value */
kr = task_set_bootstrap_port(mach_task_self(), special_port);
kr = recv_port_msg(parent_msg_port, &child_msg_port);
if (KERN_SUCCESS != kr) {
mach_error("failed set special port:\n", kr);
goto done;
}
kr = send_port_msg(child_msg_port, mach_task_self());
if (KERN_SUCCESS != kr) {
goto done;
}
waitpid(child_pid, NULL, 0);
} /* 0 == child_pid */

done:
/* restore special port to original value, success is not important to core dump */
if (MACH_PORT_NULL != special_port) {
task_set_bootstrap_port(mach_task_self(), special_port);
}
/* deallocate msg port, again success is not important to core dump */
if (MACH_PORT_NULL != parent_msg_port) {
mach_port_deallocate(mach_task_self(), parent_msg_port);
}
if (KERN_SUCCESS == kr) {
/* check if the core file has been created in the right directory */
if (0 == access(filename, F_OK)) {
Expand Down

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