/* exechelp.c - Fork and exec helpers for POSIX
* Copyright (C) 2004, 2007-2009, 2010 Free Software Foundation, Inc.
* Copyright (C) 2004, 2006-2012, 2014-2017 g10 Code GmbH
*
* This file is part of Libgpg-error.
*
* Libgpg-error 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.
*
* Libgpg-error 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 this program; if not, see <https://www.gnu.org/licenses/>.
* SPDX-License-Identifier: LGPL-2.1+
*
* This file was originally a part of GnuPG.
*/
#include <config.h>
#if defined(HAVE_W32_SYSTEM) || defined (HAVE_W32CE_SYSTEM)
#error This code is only used on POSIX
#endif
#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <string.h>
#include <errno.h>
#ifdef HAVE_SIGNAL_H
# include <signal.h>
#endif
#include <unistd.h>
#include <fcntl.h>
#include <sys/wait.h>
#ifdef HAVE_GETRLIMIT
#include <sys/time.h>
#include <sys/resource.h>
#endif /*HAVE_GETRLIMIT*/
#ifdef HAVE_STAT
# include <sys/stat.h>
#endif
#if __linux__
# include <sys/types.h>
# include <dirent.h>
#endif /*__linux__ */
#include "gpgrt-int.h"
static void
out_of_core (int line)
{
_gpgrt_log_fatal ("malloc failed at line %d: %s\n",
line, _gpg_strerror (_gpg_err_code_from_syserror ()));
/*NOTREACHED*/
}
/* Return the maximum number of currently allowed open file
* descriptors. Only useful on POSIX systems but returns a value on
* other systems too. */
static int
get_max_fds (void)
{
int max_fds = -1;
#ifdef HAVE_GETRLIMIT
struct rlimit rl;
/* Under Linux we can figure out the highest used file descriptor by
* reading /proc/PID/fd. This is in the common cases much fast than
* for example doing 4096 close calls where almost all of them will
* fail. On a system with a limit of 4096 files and only 8 files
* open with the highest number being 10, we speedup close_all_fds
* from 125ms to 0.4ms including readdir.
*
* Another option would be to close the file descriptors as returned
* from reading that directory - however then we need to snapshot
* that list before starting to close them. */
#ifdef __linux__
{
DIR *dir = NULL;
struct dirent *dir_entry;
const char *s;
int x;
/* FIXME: Check gpgme on how to do this right on Linux. */
dir = opendir ("/proc/self/fd");
if (dir)
{
while ((dir_entry = readdir (dir)))
{
s = dir_entry->d_name;
if ( *s < '0' || *s > '9')
continue;
x = atoi (s);
if (x > max_fds)
max_fds = x;
}
closedir (dir);
}
if (max_fds != -1)
return max_fds + 1;
}
#endif /* __linux__ */
# ifdef RLIMIT_NOFILE
if (!getrlimit (RLIMIT_NOFILE, &rl))
max_fds = rl.rlim_max;
# endif
# ifdef RLIMIT_OFILE
if (max_fds == -1 && !getrlimit (RLIMIT_OFILE, &rl))
max_fds = rl.rlim_max;
# endif
#endif /*HAVE_GETRLIMIT*/
#ifdef _SC_OPEN_MAX
if (max_fds == -1)
{
long int scres = sysconf (_SC_OPEN_MAX);
if (scres >= 0)
max_fds = scres;
}
#endif
#ifdef _POSIX_OPEN_MAX
if (max_fds == -1)
max_fds = _POSIX_OPEN_MAX;
#endif
#ifdef OPEN_MAX
if (max_fds == -1)
max_fds = OPEN_MAX;
#endif
if (max_fds == -1)
max_fds = 256; /* Arbitrary limit. */
/* AIX returns INT32_MAX instead of a proper value. We assume that
this is always an error and use an arbitrary limit. */
#ifdef INT32_MAX
if (max_fds == INT32_MAX)
max_fds = 256;
#endif
return max_fds;
}
/* Close all file descriptors starting with descriptor FIRST. If
* EXCEPT is not NULL, it is expected to be a list of file descriptors
* which shall not be closed. This list shall be sorted in ascending
* order with the end marked by -1. */
static void
close_all_fds (int first, int *except)
{
int max_fd = get_max_fds ();
int fd, i, except_start;
if (except)
{
except_start = 0;
for (fd=first; fd < max_fd; fd++)
{
for (i=except_start; except[i] != -1; i++)
{
if (except[i] == fd)
{
/* If we found the descriptor in the exception list
we can start the next compare run at the next
index because the exception list is ordered. */
except_start = i + 1;
break;
}
}
if (except[i] == -1)
close (fd);
}
}
else
{
for (fd=first; fd < max_fd; fd++)
close (fd);
}
_gpg_err_set_errno (0);
}
/* Returns an array with all currently open file descriptors. The end
* of the array is marked by -1. The caller needs to release this
* array using the *standard free* and not with xfree. This allow the
* use of this function right at startup even before libgcrypt has
* been initialized. Returns NULL on error and sets ERRNO
* accordingly.
*
* FIXME: Needs to be adjusted for use here.
*/
#if 0
int *
get_all_open_fds (void)
{
int *array;
size_t narray;
int fd, max_fd, idx;
#ifndef HAVE_STAT
array = calloc (1, sizeof *array);
if (array)
array[0] = -1;
#else /*HAVE_STAT*/
struct stat statbuf;
max_fd = get_max_fds ();
narray = 32; /* If you change this change also t-exechelp.c. */
array = calloc (narray, sizeof *array);
if (!array)
return NULL;
/* Note: The list we return is ordered. */
for (idx=0, fd=0; fd < max_fd; fd++)
if (!(fstat (fd, &statbuf) == -1 && errno == EBADF))
{
if (idx+1 >= narray)
{
int *tmp;
narray += (narray < 256)? 32:256;
tmp = realloc (array, narray * sizeof *array);
if (!tmp)
{
free (array);
return NULL;
}
array = tmp;
}
array[idx++] = fd;
}
array[idx] = -1;
#endif /*HAVE_STAT*/
return array;
}
#endif /*0*/
/* The exec core used right after the fork. This will never return. */
static void
do_exec (const char *pgmname, const char *argv[],
int fd_in, int fd_out, int fd_err,
int *except, void (*preexec)(void) )
{
char **arg_list;
int i, j;
int fds[3];
fds[0] = fd_in;
fds[1] = fd_out;
fds[2] = fd_err;
/* Create the command line argument array. */
i = 0;
if (argv)
while (argv[i])
i++;
arg_list = xtrycalloc (i+2, sizeof *arg_list);
if (!arg_list)
out_of_core (__LINE__);
arg_list[0] = strrchr (pgmname, '/');
if (arg_list[0])
arg_list[0]++;
else
{
arg_list[0] = xtrystrdup (pgmname);
if (!arg_list[0])
out_of_core (__LINE__);
}
if (argv)
for (i=0,j=1; argv[i]; i++, j++)
arg_list[j] = (char*)argv[i];
/* Assign /dev/null to unused FDs. */
for (i=0; i <= 2; i++)
{
if (fds[i] == -1 )
{
fds[i] = open ("/dev/null", i? O_WRONLY : O_RDONLY);
if (fds[i] == -1)
_gpgrt_log_fatal ("failed to open '%s': %s\n",
"/dev/null", strerror (errno));
}
}
/* Connect the standard files. */
for (i=0; i <= 2; i++)
{
if (fds[i] != i && dup2 (fds[i], i) == -1)
_gpgrt_log_fatal ("dup2 std%s failed: %s\n",
i==0?"in":i==1?"out":"err", strerror (errno));
}
/* Close all other files. */
close_all_fds (3, except);
if (preexec)
preexec ();
execv (pgmname, arg_list);
/* No way to print anything, as we have may have closed all streams. */
_exit (127);
}
/* Helper for _gpgrt_make_pipe. */
static gpg_err_code_t
do_create_pipe (int filedes[2])
{
gpg_error_t err = 0;
_gpgrt_pre_syscall ();
if (pipe (filedes) == -1)
{
err = _gpg_err_code_from_syserror ();
filedes[0] = filedes[1] = -1;
}
_gpgrt_post_syscall ();
return err;
}
/* Helper for _gpgrt_make_pipe. */
static gpg_err_code_t
do_create_pipe_and_estream (int filedes[2], estream_t *r_fp,
int outbound, int nonblock)
{
gpg_err_code_t err;
_gpgrt_pre_syscall ();
if (pipe (filedes) == -1)
{
err = _gpg_err_code_from_syserror ();
_gpgrt_log_error (_("error creating a pipe: %s\n"), _gpg_strerror (err));
filedes[0] = filedes[1] = -1;
*r_fp = NULL;
return err;
}
_gpgrt_post_syscall ();
if (!outbound)
*r_fp = _gpgrt_fdopen (filedes[0], nonblock? "r,nonblock" : "r");
else
*r_fp = _gpgrt_fdopen (filedes[1], nonblock? "w,nonblock" : "w");
if (!*r_fp)
{
err = _gpg_err_code_from_syserror ();
_gpgrt_log_error (_("error creating a stream for a pipe: %s\n"),
_gpg_strerror (err));
close (filedes[0]);
close (filedes[1]);
filedes[0] = filedes[1] = -1;
return err;
}
return 0;
}
/* Create a pipe. The DIRECTION parameter gives the type of the created pipe:
* DIRECTION < 0 := Inbound pipe: On Windows the write end is inheritable.
* DIRECTION > 0 := Outbound pipe: On Windows the read end is inheritable.
* If R_FP is NULL a standard pipe and no stream is created, DIRECTION
* should then be 0. */
gpg_err_code_t
_gpgrt_make_pipe (int filedes[2], estream_t *r_fp, int direction,
int nonblock)
{
if (r_fp && direction)
return do_create_pipe_and_estream (filedes, r_fp,
(direction > 0), nonblock);
else
return do_create_pipe (filedes);
}
/* Fork and exec the PGMNAME, see gpgrt-int.h for details. */
gpg_err_code_t
_gpgrt_spawn_process (const char *pgmname, const char *argv[],
int *except, void (*preexec)(void), unsigned int flags,
estream_t *r_infp,
estream_t *r_outfp,
estream_t *r_errfp,
pid_t *pid)
{
gpg_error_t err;
int inpipe[2] = {-1, -1};
int outpipe[2] = {-1, -1};
int errpipe[2] = {-1, -1};
estream_t infp = NULL;
estream_t outfp = NULL;
estream_t errfp = NULL;
int nonblock = !!(flags & GPGRT_SPAWN_NONBLOCK);
if (r_infp)
*r_infp = NULL;
if (r_outfp)
*r_outfp = NULL;
if (r_errfp)
*r_errfp = NULL;
*pid = (pid_t)(-1); /* Always required. */
if (r_infp)
{
err = _gpgrt_create_outbound_pipe (inpipe, &infp, nonblock);
if (err)
return err;
}
if (r_outfp)
{
err = _gpgrt_create_inbound_pipe (outpipe, &outfp, nonblock);
if (err)
{
if (infp)
_gpgrt_fclose (infp);
else if (inpipe[1] != -1)
close (inpipe[1]);
if (inpipe[0] != -1)
close (inpipe[0]);
return err;
}
}
if (r_errfp)
{
err = _gpgrt_create_inbound_pipe (errpipe, &errfp, nonblock);
if (err)
{
if (infp)
_gpgrt_fclose (infp);
else if (inpipe[1] != -1)
close (inpipe[1]);
if (inpipe[0] != -1)
close (inpipe[0]);
if (outfp)
_gpgrt_fclose (outfp);
else if (outpipe[0] != -1)
close (outpipe[0]);
if (outpipe[1] != -1)
close (outpipe[1]);
return err;
}
}
_gpgrt_pre_syscall ();
*pid = fork ();
_gpgrt_post_syscall ();
if (*pid == (pid_t)(-1))
{
err = _gpg_err_code_from_syserror ();
_gpgrt_log_error (_("error forking process: %s\n"), _gpg_strerror (err));
if (infp)
_gpgrt_fclose (infp);
else if (inpipe[1] != -1)
close (inpipe[1]);
if (inpipe[0] != -1)
close (inpipe[0]);
if (outfp)
_gpgrt_fclose (outfp);
else if (outpipe[0] != -1)
close (outpipe[0]);
if (outpipe[1] != -1)
close (outpipe[1]);
if (errfp)
_gpgrt_fclose (errfp);
else if (errpipe[0] != -1)
close (errpipe[0]);
if (errpipe[1] != -1)
close (errpipe[1]);
return err;
}
if (!*pid)
{
/* This is the child. */
/* FIXME: Needs to be done by preexec:
gcry_control (GCRYCTL_TERM_SECMEM); */
_gpgrt_fclose (infp);
_gpgrt_fclose (outfp);
_gpgrt_fclose (errfp);
do_exec (pgmname, argv, inpipe[0], outpipe[1], errpipe[1],
except, preexec);
/*NOTREACHED*/
}
/* This is the parent. */
if (inpipe[0] != -1)
close (inpipe[0]);
if (outpipe[1] != -1)
close (outpipe[1]);
if (errpipe[1] != -1)
close (errpipe[1]);
if (r_infp)
*r_infp = infp;
if (r_outfp)
*r_outfp = outfp;
if (r_errfp)
*r_errfp = errfp;
return 0;
}
/* Fork and exec the PGMNAME using FDs, see gpgrt-int.h for details. */
gpg_err_code_t
_gpgrt_spawn_process_fd (const char *pgmname, const char *argv[],
int infd, int outfd, int errfd, pid_t *pid)
{
gpg_error_t err;
_gpgrt_pre_syscall ();
*pid = fork ();
_gpgrt_post_syscall ();
if (*pid == (pid_t)(-1))
{
err = _gpg_err_code_from_syserror ();
_gpgrt_log_error (_("error forking process: %s\n"), _gpg_strerror (err));
return err;
}
if (!*pid)
{
/* FIXME: We need to add a preexec so that a
gcry_control (GCRYCTL_TERM_SECMEM);
can be done. */
/* Run child. */
do_exec (pgmname, argv, infd, outfd, errfd, NULL, NULL);
/*NOTREACHED*/
}
return 0;
}
/* Waiting for child processes.
*
* waitpid(2) may return information about terminated children that we
* did not yet request, and there is no portable way to wait for a
* specific set of children.
*
* As a workaround, we store the results of children for later use.
*
* XXX: This assumes that PIDs are not reused too quickly.
* FIXME: This is not thread-safe.
*/
struct terminated_child
{
pid_t pid;
int exitcode;
struct terminated_child *next;
};
static struct terminated_child *terminated_children;
static gpg_err_code_t
store_result (pid_t pid, int exitcode)
{
struct terminated_child *c;
c = xtrymalloc (sizeof *c);
if (c == NULL)
return _gpg_err_code_from_syserror ();
c->pid = pid;
c->exitcode = exitcode;
c->next = terminated_children;
terminated_children = c;
return 0;
}
static int
get_result (pid_t pid, int *r_exitcode)
{
struct terminated_child *c, **prevp;
for (prevp = &terminated_children, c = terminated_children;
c;
prevp = &c->next, c = c->next)
if (c->pid == pid)
{
*prevp = c->next;
*r_exitcode = c->exitcode;
xfree (c);
return 1;
}
return 0;
}
/* See gpgrt-int.h for a description. */
gpg_err_code_t
_gpgrt_wait_process (const char *pgmname, pid_t pid, int hang, int *r_exitcode)
{
gpg_err_code_t ec;
int i, status;
if (r_exitcode)
*r_exitcode = -1;
if (pid == (pid_t)(-1))
return GPG_ERR_INV_VALUE;
_gpgrt_pre_syscall ();
while ((i=waitpid (pid, &status, hang? 0:WNOHANG)) == (pid_t)(-1)
&& errno == EINTR);
_gpgrt_post_syscall ();
if (i == (pid_t)(-1))
{
ec = _gpg_err_code_from_syserror ();
_gpgrt_log_error (_("waiting for process %d to terminate failed: %s\n"),
(int)pid, _gpg_strerror (ec));
}
else if (!i)
{
ec = GPG_ERR_TIMEOUT; /* Still running. */
}
else if (WIFEXITED (status) && WEXITSTATUS (status) == 127)
{
/* FIXME: This is GnuPG specific. */
_gpgrt_log_error (_("error running '%s': probably not installed\n"),
pgmname);
ec = GPG_ERR_CONFIGURATION;
}
else if (WIFEXITED (status) && WEXITSTATUS (status))
{
if (!r_exitcode)
_gpgrt_log_error (_("error running '%s': exit status %d\n"), pgmname,
WEXITSTATUS (status));
else
*r_exitcode = WEXITSTATUS (status);
ec = GPG_ERR_GENERAL;
}
else if (!WIFEXITED (status))
{
_gpgrt_log_error (_("error running '%s': terminated\n"), pgmname);
ec = GPG_ERR_GENERAL;
}
else
{
if (r_exitcode)
*r_exitcode = 0;
ec = 0;
}
return ec;
}
/* See gpgrt-int.h for a description.
*
* FIXME: What about using a poll like data structure for the pids and
* their exit codes? The whole thing is anyway problematic in a
* threaded processs because waitpid has no association between PIDS
* and threads.
*/
gpg_err_code_t
_gpgrt_wait_processes (const char **pgmnames, pid_t *pids, size_t count,
int hang, int *r_exitcodes)
{
gpg_err_code_t ec = 0;
size_t i, left;
int *dummy = NULL;
if (!r_exitcodes)
{
dummy = r_exitcodes = xtrymalloc (sizeof *r_exitcodes * count);
if (!dummy)
return _gpg_err_code_from_syserror ();
}
for (i = 0, left = count; i < count; i++)
{
int status = -1;
if (pids[i] == (pid_t)(-1))
return GPG_ERR_INV_VALUE;
/* See if there was a previously stored result for this pid. */
if (get_result (pids[i], &status))
left -= 1;
r_exitcodes[i] = status;
}
while (left > 0)
{
pid_t pid;
int status;
_gpgrt_pre_syscall ();
while ((pid = waitpid (-1, &status, hang ? 0 : WNOHANG)) == (pid_t)(-1)
&& errno == EINTR);
_gpgrt_post_syscall ();
if (pid == (pid_t)(-1))
{
ec = _gpg_err_code_from_syserror ();
_gpgrt_log_error (_("waiting for processes to terminate"
" failed: %s\n"), _gpg_strerror (ec));
break;
}
else if (!pid)
{
ec = GPG_ERR_TIMEOUT; /* Still running. */
break;
}
else
{
for (i = 0; i < count; i++)
if (pid == pids[i])
break;
if (i == count)
{
/* No match, store this result. */
ec = store_result (pid, status);
if (ec)
break;
continue;
}
/* Process PIDS[i] died. */
if (r_exitcodes[i] != (pid_t) -1)
{
_gpgrt_log_error ("PID %d was reused", (int)pid);
ec = GPG_ERR_GENERAL;
break;
}
left -= 1;
r_exitcodes[i] = status;
}
}
for (i = 0; i < count; i++)
{
if (r_exitcodes[i] == -1)
continue;
if (WIFEXITED (r_exitcodes[i]) && WEXITSTATUS (r_exitcodes[i]) == 127)
{
_gpgrt_log_error (_("error running '%s': probably not installed\n"),
pgmnames[i]);
ec = GPG_ERR_CONFIGURATION;
}
else if (WIFEXITED (r_exitcodes[i]) && WEXITSTATUS (r_exitcodes[i]))
{
if (dummy)
_gpgrt_log_error (_("error running '%s': exit status %d\n"),
pgmnames[i], WEXITSTATUS (r_exitcodes[i]));
else
r_exitcodes[i] = WEXITSTATUS (r_exitcodes[i]);
ec = GPG_ERR_GENERAL;
}
else if (!WIFEXITED (r_exitcodes[i]))
{
_gpgrt_log_error (_("error running '%s': terminated\n"), pgmnames[i]);
ec = GPG_ERR_GENERAL;
}
}
xfree (dummy);
return ec;
}
/* See gpgrt-int.h for a description. FIXME: We should add a prexec
* callback. */
gpg_err_code_t
_gpgrt_spawn_process_detached (const char *pgmname, const char *argv[],
const char *envp[] )
{
gpg_err_code_t ec;
pid_t pid;
int i;
/* FIXME: Is this GnuPG specific or should we keep it. */
if (getuid() != geteuid())
return GPG_ERR_BUG;
if (access (pgmname, X_OK))
return _gpg_err_code_from_syserror ();
_gpgrt_pre_syscall ();
pid = fork ();
_gpgrt_post_syscall ();
if (pid == (pid_t)(-1))
{
ec = _gpg_err_code_from_syserror ();
_gpgrt_log_error (_("error forking process: %s\n"), _gpg_strerror (ec));
return ec;
}
if (!pid)
{
pid_t pid2;
/* gcry_control (GCRYCTL_TERM_SECMEM); */
if (setsid() == -1 || chdir ("/"))
_exit (1);
pid2 = fork (); /* Double fork to let init take over the new child. */
if (pid2 == (pid_t)(-1))
_exit (1);
if (pid2)
_exit (0); /* Let the parent exit immediately. */
for (i=0; envp && envp[i]; i++)
{
char *p = xtrystrdup (envp[i]);
if (!p)
out_of_core (__LINE__);
putenv (p);
}
do_exec (pgmname, argv, -1, -1, -1, NULL, NULL);
/*NOTREACHED*/
}
_gpgrt_pre_syscall ();
if (waitpid (pid, NULL, 0) == -1)
{
_gpgrt_post_syscall ();
ec = _gpg_err_code_from_syserror ();
_gpgrt_log_error ("waitpid failed in gpgrt_spawn_process_detached: %s",
_gpg_strerror (ec));
return ec;
}
else
_gpgrt_post_syscall ();
return 0;
}
/* Kill a process; that is send an appropriate signal to the process.
* gnupg_wait_process must be called to actually remove the process
from the system. An invalid PID is ignored. */
void
_gpgrt_kill_process (pid_t pid)
{
if (pid != (pid_t)(-1))
{
_gpgrt_pre_syscall ();
kill (pid, SIGTERM);
_gpgrt_post_syscall ();
}
}
void
_gpgrt_release_process (pid_t pid)
{
(void)pid;
}
