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glibc/hurd/hurdexec.c
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/* Copyright (C) 1991-2016 Free Software Foundation, Inc. | |
This file is part of the GNU C Library. | |
The GNU C Library is free software; you can redistribute it and/or | |
modify it under the terms of the GNU Lesser General Public | |
License as published by the Free Software Foundation; either | |
version 2.1 of the License, or (at your option) any later version. | |
The GNU C Library 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 | |
Lesser General Public License for more details. | |
You should have received a copy of the GNU Lesser General Public | |
License along with the GNU C Library; if not, see | |
<http://www.gnu.org/licenses/>. */ | |
#include <errno.h> | |
#include <unistd.h> | |
#include <fcntl.h> | |
#include <limits.h> | |
#include <stdlib.h> | |
#include <string.h> | |
#include <hurd.h> | |
#include <hurd/fd.h> | |
#include <hurd/signal.h> | |
#include <hurd/id.h> | |
#include <assert.h> | |
#include <argz.h> | |
/* Overlay TASK, executing FILE with arguments ARGV and environment ENVP. | |
If TASK == mach_task_self (), some ports are dealloc'd by the exec server. | |
ARGV and ENVP are terminated by NULL pointers. */ | |
error_t | |
_hurd_exec (task_t task, file_t file, | |
char *const argv[], char *const envp[]) | |
{ | |
error_t err; | |
char *args, *env; | |
size_t argslen, envlen; | |
int ints[INIT_INT_MAX]; | |
mach_port_t ports[_hurd_nports]; | |
struct hurd_userlink ulink_ports[_hurd_nports]; | |
inline void free_port (unsigned int i) | |
{ | |
_hurd_port_free (&_hurd_ports[i], &ulink_ports[i], ports[i]); | |
} | |
file_t *dtable; | |
unsigned int dtablesize, i; | |
struct hurd_port **dtable_cells; | |
struct hurd_userlink *ulink_dtable; | |
struct hurd_sigstate *ss; | |
mach_port_t *please_dealloc, *pdp; | |
int reauth = 0; | |
/* XXX needs to be hurdmalloc XXX */ | |
if (argv == NULL) | |
args = NULL, argslen = 0; | |
else if (err = __argz_create (argv, &args, &argslen)) | |
return err; | |
if (envp == NULL) | |
env = NULL, envlen = 0; | |
else if (err = __argz_create (envp, &env, &envlen)) | |
goto outargs; | |
/* Load up the ports to give to the new program. */ | |
for (i = 0; i < _hurd_nports; ++i) | |
if (i == INIT_PORT_PROC && task != __mach_task_self ()) | |
{ | |
/* This is another task, so we need to ask the proc server | |
for the right proc server port for it. */ | |
if (err = __USEPORT (PROC, __proc_task2proc (port, task, &ports[i]))) | |
{ | |
while (--i > 0) | |
free_port (i); | |
goto outenv; | |
} | |
} | |
else | |
ports[i] = _hurd_port_get (&_hurd_ports[i], &ulink_ports[i]); | |
/* Load up the ints to give the new program. */ | |
for (i = 0; i < INIT_INT_MAX; ++i) | |
switch (i) | |
{ | |
case INIT_UMASK: | |
ints[i] = _hurd_umask; | |
break; | |
case INIT_SIGMASK: | |
case INIT_SIGIGN: | |
case INIT_SIGPENDING: | |
/* We will set these all below. */ | |
break; | |
case INIT_TRACEMASK: | |
ints[i] = _hurdsig_traced; | |
break; | |
default: | |
ints[i] = 0; | |
} | |
ss = _hurd_self_sigstate (); | |
assert (! __spin_lock_locked (&ss->critical_section_lock)); | |
__spin_lock (&ss->critical_section_lock); | |
__spin_lock (&ss->lock); | |
ints[INIT_SIGMASK] = ss->blocked; | |
ints[INIT_SIGPENDING] = ss->pending; | |
ints[INIT_SIGIGN] = 0; | |
for (i = 1; i < NSIG; ++i) | |
if (ss->actions[i].sa_handler == SIG_IGN) | |
ints[INIT_SIGIGN] |= __sigmask (i); | |
/* We hold the sigstate lock until the exec has failed so that no signal | |
can arrive between when we pack the blocked and ignored signals, and | |
when the exec actually happens. A signal handler could change what | |
signals are blocked and ignored. Either the change will be reflected | |
in the exec, or the signal will never be delivered. Setting the | |
critical section flag avoids anything we call trying to acquire the | |
sigstate lock. */ | |
__spin_unlock (&ss->lock); | |
/* Pack up the descriptor table to give the new program. */ | |
__mutex_lock (&_hurd_dtable_lock); | |
dtablesize = _hurd_dtable ? _hurd_dtablesize : _hurd_init_dtablesize; | |
if (task == __mach_task_self ()) | |
/* Request the exec server to deallocate some ports from us if the exec | |
succeeds. The init ports and descriptor ports will arrive in the | |
new program's exec_startup message. If we failed to deallocate | |
them, the new program would have duplicate user references for them. | |
But we cannot deallocate them ourselves, because we must still have | |
them after a failed exec call. */ | |
please_dealloc = __alloca ((_hurd_nports + 3 + (3 * dtablesize)) | |
* sizeof (mach_port_t)); | |
else | |
please_dealloc = NULL; | |
pdp = please_dealloc; | |
if (_hurd_dtable != NULL) | |
{ | |
dtable = __alloca (dtablesize * sizeof (dtable[0])); | |
ulink_dtable = __alloca (dtablesize * sizeof (ulink_dtable[0])); | |
dtable_cells = __alloca (dtablesize * sizeof (dtable_cells[0])); | |
for (i = 0; i < dtablesize; ++i) | |
{ | |
struct hurd_fd *const d = _hurd_dtable[i]; | |
if (d == NULL) | |
{ | |
dtable[i] = MACH_PORT_NULL; | |
continue; | |
} | |
__spin_lock (&d->port.lock); | |
if (d->flags & FD_CLOEXEC) | |
{ | |
/* This descriptor is marked to be closed on exec. | |
So don't pass it to the new program. */ | |
dtable[i] = MACH_PORT_NULL; | |
if (pdp && d->port.port != MACH_PORT_NULL) | |
{ | |
/* We still need to deallocate the ports. */ | |
*pdp++ = d->port.port; | |
if (d->ctty.port != MACH_PORT_NULL) | |
*pdp++ = d->ctty.port; | |
} | |
__spin_unlock (&d->port.lock); | |
} | |
else | |
{ | |
if (pdp && d->ctty.port != MACH_PORT_NULL) | |
/* All the elements of DTABLE are added to PLEASE_DEALLOC | |
below, so we needn't add the port itself. | |
But we must deallocate the ctty port as well as | |
the normal port that got installed in DTABLE[I]. */ | |
*pdp++ = d->ctty.port; | |
dtable[i] = _hurd_port_locked_get (&d->port, &ulink_dtable[i]); | |
dtable_cells[i] = &d->port; | |
} | |
} | |
} | |
else | |
{ | |
dtable = _hurd_init_dtable; | |
ulink_dtable = NULL; | |
dtable_cells = NULL; | |
} | |
/* Prune trailing null ports from the descriptor table. */ | |
while (dtablesize > 0 && dtable[dtablesize - 1] == MACH_PORT_NULL) | |
--dtablesize; | |
/* See if we need to diddle the auth port of the new program. | |
The purpose of this is to get the effect setting the saved-set UID and | |
GID to the respective effective IDs after the exec, as POSIX.1 requires. | |
Note that we don't reauthenticate with the proc server; that would be a | |
no-op since it only keeps track of the effective UIDs, and if it did | |
keep track of the available IDs we would have the problem that we'd be | |
changing the IDs before the exec and have to change them back after a | |
failure. Arguably we could skip all the reauthentications because the | |
available IDs have no bearing on any filesystem. But the conservative | |
approach is to reauthenticate all the io ports so that no state anywhere | |
reflects that our whole ID set differs from what we've set it to. */ | |
__mutex_lock (&_hurd_id.lock); | |
err = _hurd_check_ids (); | |
if (err == 0 && ((_hurd_id.aux.nuids >= 2 && _hurd_id.gen.nuids >= 1 | |
&& _hurd_id.aux.uids[1] != _hurd_id.gen.uids[0]) | |
|| (_hurd_id.aux.ngids >= 2 && _hurd_id.gen.ngids >= 1 | |
&& _hurd_id.aux.gids[1] != _hurd_id.gen.gids[0]))) | |
{ | |
/* We have euid != svuid or egid != svgid. POSIX.1 says that exec | |
sets svuid = euid and svgid = egid. So we must get a new auth | |
port and reauthenticate everything with it. We'll pass the new | |
ports in file_exec instead of our own ports. */ | |
auth_t newauth; | |
_hurd_id.aux.uids[1] = _hurd_id.gen.uids[0]; | |
_hurd_id.aux.gids[1] = _hurd_id.gen.gids[0]; | |
_hurd_id.valid = 0; | |
if (_hurd_id.rid_auth != MACH_PORT_NULL) | |
{ | |
__mach_port_deallocate (__mach_task_self (), _hurd_id.rid_auth); | |
_hurd_id.rid_auth = MACH_PORT_NULL; | |
} | |
err = __auth_makeauth (ports[INIT_PORT_AUTH], | |
NULL, MACH_MSG_TYPE_COPY_SEND, 0, | |
_hurd_id.gen.uids, _hurd_id.gen.nuids, | |
_hurd_id.aux.uids, _hurd_id.aux.nuids, | |
_hurd_id.gen.gids, _hurd_id.gen.ngids, | |
_hurd_id.aux.gids, _hurd_id.aux.ngids, | |
&newauth); | |
if (err == 0) | |
{ | |
/* Now we have to reauthenticate the ports with this new ID. | |
*/ | |
inline error_t reauth_io (io_t port, io_t *newport) | |
{ | |
mach_port_t ref = __mach_reply_port (); | |
*newport = MACH_PORT_NULL; | |
error_t err = __io_reauthenticate (port, | |
ref, MACH_MSG_TYPE_MAKE_SEND); | |
if (!err) | |
err = __auth_user_authenticate (newauth, | |
ref, MACH_MSG_TYPE_MAKE_SEND, | |
newport); | |
__mach_port_destroy (__mach_task_self (), ref); | |
return err; | |
} | |
inline void reauth_port (unsigned int idx) | |
{ | |
io_t newport; | |
err = reauth_io (ports[idx], &newport) ?: err; | |
if (pdp) | |
*pdp++ = ports[idx]; /* XXX presumed still in _hurd_ports */ | |
free_port (idx); | |
ports[idx] = newport; | |
} | |
if (pdp) | |
*pdp++ = ports[INIT_PORT_AUTH]; | |
free_port (INIT_PORT_AUTH); | |
ports[INIT_PORT_AUTH] = newauth; | |
reauth_port (INIT_PORT_CRDIR); | |
reauth_port (INIT_PORT_CWDIR); | |
if (!err) | |
{ | |
/* Now we'll reauthenticate each file descriptor. */ | |
if (ulink_dtable == NULL) | |
{ | |
assert (dtable == _hurd_init_dtable); | |
dtable = __alloca (dtablesize * sizeof (dtable[0])); | |
for (i = 0; i < dtablesize; ++i) | |
if (_hurd_init_dtable[i] != MACH_PORT_NULL) | |
{ | |
if (pdp) | |
*pdp++ = _hurd_init_dtable[i]; | |
err = reauth_io (_hurd_init_dtable[i], &dtable[i]); | |
if (err) | |
{ | |
while (++i < dtablesize) | |
dtable[i] = MACH_PORT_NULL; | |
break; | |
} | |
} | |
else | |
dtable[i] = MACH_PORT_NULL; | |
} | |
else | |
{ | |
if (pdp) | |
{ | |
/* Ask to deallocate all the old fd ports, | |
since we will have new ones in DTABLE. */ | |
memcpy (pdp, dtable, dtablesize * sizeof pdp[0]); | |
pdp += dtablesize; | |
} | |
for (i = 0; i < dtablesize; ++i) | |
if (dtable[i] != MACH_PORT_NULL) | |
{ | |
io_t newport; | |
err = reauth_io (dtable[i], &newport); | |
_hurd_port_free (dtable_cells[i], &ulink_dtable[i], | |
dtable[i]); | |
dtable[i] = newport; | |
if (err) | |
{ | |
while (++i < dtablesize) | |
_hurd_port_free (dtable_cells[i], | |
&ulink_dtable[i], dtable[i]); | |
break; | |
} | |
} | |
ulink_dtable = NULL; | |
dtable_cells = NULL; | |
} | |
} | |
} | |
reauth = 1; | |
} | |
__mutex_unlock (&_hurd_id.lock); | |
/* The information is all set up now. Try to exec the file. */ | |
if (!err) | |
{ | |
int flags; | |
if (pdp) | |
{ | |
/* Request the exec server to deallocate some ports from us if | |
the exec succeeds. The init ports and descriptor ports will | |
arrive in the new program's exec_startup message. If we | |
failed to deallocate them, the new program would have | |
duplicate user references for them. But we cannot deallocate | |
them ourselves, because we must still have them after a failed | |
exec call. */ | |
for (i = 0; i < _hurd_nports; ++i) | |
*pdp++ = ports[i]; | |
for (i = 0; i < dtablesize; ++i) | |
*pdp++ = dtable[i]; | |
} | |
flags = 0; | |
#ifdef EXEC_SIGTRAP | |
/* PTRACE_TRACEME sets all bits in _hurdsig_traced, which is | |
propagated through exec by INIT_TRACEMASK, so this checks if | |
PTRACE_TRACEME has been called in this process in any of its | |
current or prior lives. */ | |
if (__sigismember (&_hurdsig_traced, SIGKILL)) | |
flags |= EXEC_SIGTRAP; | |
#endif | |
err = __file_exec (file, task, flags, | |
args, argslen, env, envlen, | |
dtable, MACH_MSG_TYPE_COPY_SEND, dtablesize, | |
ports, MACH_MSG_TYPE_COPY_SEND, _hurd_nports, | |
ints, INIT_INT_MAX, | |
please_dealloc, pdp - please_dealloc, | |
&_hurd_msgport, task == __mach_task_self () ? 1 : 0); | |
} | |
/* Release references to the standard ports. */ | |
for (i = 0; i < _hurd_nports; ++i) | |
if ((i == INIT_PORT_PROC && task != __mach_task_self ()) | |
|| (reauth && (i == INIT_PORT_AUTH | |
|| i == INIT_PORT_CRDIR || i == INIT_PORT_CWDIR))) | |
__mach_port_deallocate (__mach_task_self (), ports[i]); | |
else | |
free_port (i); | |
/* Release references to the file descriptor ports. */ | |
if (ulink_dtable != NULL) | |
{ | |
for (i = 0; i < dtablesize; ++i) | |
if (dtable[i] != MACH_PORT_NULL) | |
_hurd_port_free (dtable_cells[i], &ulink_dtable[i], dtable[i]); | |
} | |
else if (dtable && dtable != _hurd_init_dtable) | |
for (i = 0; i < dtablesize; ++i) | |
__mach_port_deallocate (__mach_task_self (), dtable[i]); | |
/* Release lock on the file descriptor table. */ | |
__mutex_unlock (&_hurd_dtable_lock); | |
/* Safe to let signals happen now. */ | |
_hurd_critical_section_unlock (ss); | |
outargs: | |
free (args); | |
outenv: | |
free (env); | |
return err; | |
} |