path: root/libfshelp/start-translator-long.c

/*
   Copyright (C) 1995, 1996, 1999, 2000, 2002, 2004, 2010
   Free Software Foundation, Inc.
   Written by Miles Bader and Michael I. Bushnell.

   This file is part of the GNU Hurd.

   The GNU Hurd is free software; you can redistribute it and/or
   modify it under the terms of the GNU General Public License as
   published by the Free Software Foundation; either version 2, or (at
   your option) any later version.

   The GNU Hurd is distributed in the hope that it will be useful, but
   WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */

#include <hurd.h>
#include <mach/notify.h>
#include <mach.h>
#include <errno.h>
#include <unistd.h>
#include <stdlib.h>
#include <fcntl.h>
#include <stdint.h>
#include <string.h>
#include <assert-backtrace.h>
#include "fshelp.h"


/* The data passed in the various messages we're interested in.  */
struct fsys_startup_request
{
  mach_msg_header_t head;
  mach_msg_type_t flagsType;
  int flags;
  mach_msg_type_t control_portType;
  mach_port_name_inlined_t control_port;
};

struct fsys_startup_reply
{
  mach_msg_header_t head;
  mach_msg_type_t RetCodeType;
  kern_return_t RetCode;
  mach_msg_type_t realnodeType;
  mach_port_name_inlined_t realnode;
};

/* Wait around for an fsys_startup message on the port PORT from the
   translator on NODE (timing out after TIMEOUT milliseconds), and return a
   send right for the resulting fsys control port in CONTROL.  If a no-senders
   notification is received on PORT, then it will be assumed that the
   translator died, and EDIED will be returned.  If an error occurs, the
   error code is returned, otherwise 0.  */
static error_t
service_fsys_startup (fshelp_open_fn_t underlying_open_fn, void *cookie,
		      mach_port_t port, long timeout, fsys_t *control,
		      task_t task)
{
  /* These should be optimized away to pure integer constants.  */
  const mach_msg_type_t flagsCheck =
    {
      .msgt_name = MACH_MSG_TYPE_INTEGER_32,
      .msgt_size = 32,
      .msgt_number = 1,
      .msgt_inline = TRUE,
      .msgt_longform = FALSE,
      .msgt_deallocate = FALSE,
      .msgt_unused = 0
    };
  const mach_msg_type_t control_portCheck =
    {
      .msgt_name = MACH_MSG_TYPE_PORT_SEND,
      .msgt_size = 8 * sizeof(mach_port_name_inlined_t),
      .msgt_number = 1,
      .msgt_inline = TRUE,
      .msgt_longform = FALSE,
      .msgt_deallocate = FALSE,
      .msgt_unused = 0
    };
  const mach_msg_type_t RetCodeType =
    {
      .msgt_name = MACH_MSG_TYPE_INTEGER_32,
      .msgt_size = 32,
      .msgt_number = 1,
      .msgt_inline = TRUE,
      .msgt_longform = FALSE,
      .msgt_deallocate = FALSE,
      .msgt_unused = 0
    };
  const mach_msg_type_t realnodeType =
    {
      .msgt_name = (unsigned char) MACH_MSG_TYPE_POLYMORPHIC,
      .msgt_size = 8 * sizeof(mach_port_name_inlined_t),
      .msgt_number = 1,
      .msgt_inline = TRUE,
      .msgt_longform = FALSE,
      .msgt_deallocate = FALSE,
      .msgt_unused = 0
    };

  /* Return true iff TYPE fails to match CHECK.  */
  inline int type_check (const mach_msg_type_t *type,
			 const mach_msg_type_t *check)
    {
      union
      {
        uintptr_t word;
	mach_msg_type_t type;
      } t, c;
      t.type = *type;
      c.type = *check;
      return t.word != c.word;
    }

  error_t err;
  union
  {
    mach_msg_header_t head;
    struct fsys_startup_request startup;
  }
  request;
  struct fsys_startup_reply reply;

  /* Wait for the fsys_startup message...  */
  err = mach_msg (&request.head, (MACH_RCV_MSG | MACH_RCV_INTERRUPT
				  | (timeout ? MACH_RCV_TIMEOUT : 0)),
		  0, sizeof(request), port, timeout, MACH_PORT_NULL);
  if (err)
    return err;

  /* Check whether we actually got a no-senders notification instead.  */
  if (request.head.msgh_id == MACH_NOTIFY_NO_SENDERS)
    return EDIED;

  /* Construct our reply to the fsys_startup rpc.  */
  reply.head.msgh_size = sizeof(reply);
  reply.head.msgh_bits =
    MACH_MSGH_BITS(MACH_MSGH_BITS_REMOTE(request.head.msgh_bits), 0);
  reply.head.msgh_remote_port = request.head.msgh_remote_port;
  reply.head.msgh_local_port = MACH_PORT_NULL;
  reply.head.msgh_seqno = 0;
  reply.head.msgh_id = request.head.msgh_id + 100;
  reply.RetCodeType = RetCodeType;

  if (request.head.msgh_id != 22000)
    reply.RetCode = MIG_BAD_ID;
  else if (type_check (&request.startup.control_portType, &control_portCheck)
	   || type_check (&request.startup.flagsType, &flagsCheck))
    reply.RetCode = MIG_BAD_ARGUMENTS;
  else
    {
      mach_msg_type_name_t realnode_type;

      *control = request.startup.control_port.name;

      reply.RetCode =
	(*underlying_open_fn) (request.startup.flags,
			       &reply.realnode.name, &realnode_type, task,
			       cookie);

      reply.realnodeType = realnodeType;
      reply.realnodeType.msgt_name = realnode_type;

      if (!reply.RetCode && reply.realnode.name != MACH_PORT_NULL)
	/* The message can't be simple because of the port.  */
	reply.head.msgh_bits |= MACH_MSGH_BITS_COMPLEX;
    }

  err = mach_msg (&reply.head, MACH_SEND_MSG | MACH_SEND_INTERRUPT,
		  sizeof(reply), 0,
		  request.head.msgh_remote_port,
		  MACH_MSG_TIMEOUT_NONE, MACH_PORT_NULL);
  if (err == MACH_SEND_INTERRUPTED
      && reply.realnodeType.msgt_name == MACH_MSG_TYPE_MOVE_SEND)
    /* For MACH_SEND_INTERRUPTED, we'll have pseudo-received the message
       and might have to clean up a generated send right.  */
    mach_port_deallocate (mach_task_self (), reply.realnode.name);

  if (reply.RetCode)
    /* Make our error return be the earlier one.  */
    err = reply.RetCode;

  return err;
}


error_t
fshelp_start_translator_long (fshelp_open_fn_t underlying_open_fn,
                              void *cookie, char *name, char *argz,
                              mach_msg_type_number_t argz_len,
                              mach_port_t *fds,
                              mach_msg_type_name_t fds_type,
                              mach_msg_type_number_t fds_len,
                              mach_port_t *ports,
                              mach_msg_type_name_t ports_type,
                              mach_msg_type_number_t ports_len,
                              int *ints,
                              mach_msg_type_number_t ints_len,
                              uid_t owner_uid,
                              int timeout, fsys_t *control)
{
  error_t err;
  file_t executable;
  mach_port_t bootstrap = MACH_PORT_NULL;
  mach_port_t task = MACH_PORT_NULL;
  mach_port_t prev_notify, proc, saveport;
  int deallocate_proc;

  /* While from our function signature it appears that we support passing
     incomplete port arrays of any type, this is what the implementation
     actually requires.  */
  assert_backtrace (ports_len > INIT_PORT_BOOTSTRAP);
  assert_backtrace (ports_type == MACH_MSG_TYPE_COPY_SEND);
  assert_backtrace (fds_type == MACH_MSG_TYPE_COPY_SEND);

  /* Find the translator itself.  Since argz has zero-separated elements, we
     can use it as a normal string representing the first element.  */
  executable = file_name_lookup (name, O_EXEC, 0);
  if (executable == MACH_PORT_NULL)
    return errno;

  /* Create a bootstrap port for the translator.  */
  err = mach_port_allocate (mach_task_self (),
                            MACH_PORT_RIGHT_RECEIVE,
                            &bootstrap);
  if (err)
    goto lose;

  err = mach_port_insert_right (mach_task_self (),
                                bootstrap, bootstrap,
                                MACH_MSG_TYPE_MAKE_SEND);
  if (err)
    goto lose;

  /* Create the task for the translator.  */
  err = task_create (mach_task_self (),
#ifdef KERN_INVALID_LEDGER
		     NULL, 0,	/* OSF Mach */
#endif
		     0, &task);
  if (err)
    goto lose;

  /* XXX 25 is BASEPRI_USER, which isn't exported by the kernel.  Ideally,
     nice values should be used, perhaps with a simple wrapper to convert
     them to Mach priorities.  */
  err = task_priority (task, 25, FALSE);

  if (err)
    goto lose_task;

  /* Designate TASK as our child, fill in its proc port, and set its owner
     accordingly.  */
  if (ports[INIT_PORT_PROC] == MACH_PORT_NULL)
    {
      proc = getproc ();
      deallocate_proc = 1;
    }
  else
    {
      proc = ports[INIT_PORT_PROC];
      deallocate_proc = 0;
    }

  proc_child (proc, task);
  err = proc_task2proc (proc, task, &ports[INIT_PORT_PROC]);
  if (!err)
    {
      /* Try proc_setowner () for compatibility with
         older proc server.  */
      err = proc_setowner (ports[INIT_PORT_PROC],
                           owner_uid,
                           owner_uid == (uid_t) -1);
      if (err == EOPNOTSUPP)
        err = 0;
    }
  if (deallocate_proc)
    mach_port_deallocate (mach_task_self (), proc);
  if (err)
    goto lose_task;

  /* If we have been passed an auth port, and it's different from our own,
     reauthenticate the child proc.  */
  if (MACH_PORT_VALID (ports[INIT_PORT_AUTH])
      && HURD_PORT_USE (&_hurd_ports[INIT_PORT_AUTH],
                        port != ports[INIT_PORT_AUTH]))
    {
      mach_port_t rend, newport = MACH_PORT_NULL;

      rend = mach_reply_port ();
      err = proc_reauthenticate (ports[INIT_PORT_PROC],
                                 rend, MACH_MSG_TYPE_MAKE_SEND);

      if (!err)
        err = auth_user_authenticate (ports[INIT_PORT_AUTH],
                                      rend, MACH_MSG_TYPE_MAKE_SEND,
                                      &newport);

      mach_port_mod_refs (mach_task_self (), rend,
                          MACH_PORT_RIGHT_RECEIVE, -1);

      if (err)
        goto lose_task;

      err = proc_reauthenticate_complete (newport);
      if (err)
        {
          mach_port_deallocate (mach_task_self (), newport);
          goto lose_task;
        }

      mach_port_deallocate (mach_task_self (), ports[INIT_PORT_PROC]);
      ports[INIT_PORT_PROC] = newport;
    }

  saveport = ports[INIT_PORT_BOOTSTRAP];
  ports[INIT_PORT_BOOTSTRAP] = bootstrap;

#ifdef HAVE_FILE_EXEC_PATHS
  /* Try and exec the translator in TASK...  */
  err = file_exec_paths (executable, task, EXEC_DEFAULTS, name, name,
			 argz, argz_len, 0, 0,
			 fds, fds_type, fds_len,
			 ports, ports_type, ports_len,
			 ints, ints_len, 0, 0, 0, 0);
  /* For backwards compatibility.  Just drop it when we kill file_exec.  */
  if (err == MIG_BAD_ID)
#endif
    err = file_exec (executable, task, EXEC_DEFAULTS,
		     argz, argz_len, 0, 0,
		     fds, fds_type, fds_len,
		     ports, ports_type, ports_len,
		     ints, ints_len, 0, 0, 0, 0);

  mach_port_deallocate (mach_task_self (), bootstrap);
  ports[INIT_PORT_BOOTSTRAP] = saveport;

  if (err)
    goto lose_task;

  /* Ask to be told if TASK dies.  It is OK to use the same port here, since we
     never give it out to anyone but the translator itself (and the file system,
     and the exec server).  If the translator wants us to believe it has died,
     so be it.  */
  err = mach_port_request_notification (mach_task_self (),
                                        bootstrap,
                                        MACH_NOTIFY_NO_SENDERS,
                                        0,
                                        bootstrap,
                                        MACH_MSG_TYPE_MAKE_SEND_ONCE,
                                        &prev_notify);
  if (err)
    goto lose_task;

  /* Ok, cool, we've got a running(?) program, now rendezvous with it if
     possible using the startup protocol on the bootstrap port... */
  err = service_fsys_startup (underlying_open_fn,
                              cookie, bootstrap,
                              timeout, control, task);

 lose_task:
  if (err)
    task_terminate (task);

 lose:
  if (bootstrap != MACH_PORT_NULL)
    mach_port_destroy (mach_task_self (), bootstrap);
  if (executable != MACH_PORT_NULL)
    mach_port_deallocate (mach_task_self (), executable);
  if (task != MACH_PORT_NULL)
    mach_port_deallocate (mach_task_self (), task);
  if (ports[INIT_PORT_PROC] != MACH_PORT_NULL)
    {
      mach_port_deallocate (mach_task_self (), ports[INIT_PORT_PROC]);
      ports[INIT_PORT_PROC] = MACH_PORT_NULL;
    }

  return err;
}