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gnupg/common/exechelp-posix.c

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/* 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 GnuPG.
*
* This file is free software; you can redistribute it and/or modify
* it under the terms of either
*
* - the GNU Lesser General Public License as published by the Free
* Software Foundation; either version 3 of the License, or (at
* your option) any later version.
*
* or
*
* - the GNU General Public License as published by the Free
* Software Foundation; either version 2 of the License, or (at
* your option) any later version.
*
* or both in parallel, as here.
*
* This file 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, see <https://www.gnu.org/licenses/>.
* SPDX-License-Identifier: (LGPL-3.0+ OR GPL-2.0+)
*/
#include <config.h>
#if defined(HAVE_W32_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>
#include <assert.h>
#ifdef HAVE_SIGNAL_H
# include <signal.h>
#endif
#include <unistd.h>
#include <fcntl.h>
#ifdef WITHOUT_NPTH /* Give the Makefile a chance to build without Pth. */
#undef HAVE_NPTH
#undef USE_NPTH
#endif
#ifdef HAVE_NPTH
#include <npth.h>
#endif
#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 "util.h"
#include "i18n.h"
#include "sysutils.h"
#include "exechelp.h"
/* Helper */
static inline gpg_error_t
my_error_from_syserror (void)
{
return gpg_err_make (default_errsource, gpg_err_code_from_syserror ());
}
static inline gpg_error_t
my_error (int errcode)
{
return gpg_err_make (default_errsource, errcode);
}
/* Return the maximum number of currently allowed open file
descriptors. Only useful on POSIX systems but returns a value on
other systems too. */
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;
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. */
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. */
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;
}
static gpg_error_t
do_create_pipe (int filedes[2])
{
gpg_error_t err = 0;
if (pipe (filedes) == -1)
{
err = my_error_from_syserror ();
filedes[0] = filedes[1] = -1;
}
return err;
}
static gpg_error_t
create_pipe_and_estream (int filedes[2], estream_t *r_fp,
int outbound, int nonblock)
{
gpg_error_t err;
if (pipe (filedes) == -1)
{
err = my_error_from_syserror ();
log_error (_("error creating a pipe: %s\n"), gpg_strerror (err));
filedes[0] = filedes[1] = -1;
*r_fp = NULL;
return err;
}
if (!outbound)
*r_fp = es_fdopen (filedes[0], nonblock? "r,nonblock" : "r");
else
*r_fp = es_fdopen (filedes[1], nonblock? "w,nonblock" : "w");
if (!*r_fp)
{
err = my_error_from_syserror ();
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;
}
/* Portable function to create a pipe. Under Windows the write end is
inheritable. If R_FP is not NULL, an estream is created for the
read end and stored at R_FP. */
gpg_error_t
gnupg_create_inbound_pipe (int filedes[2], estream_t *r_fp, int nonblock)
{
if (r_fp)
return create_pipe_and_estream (filedes, r_fp, 0, nonblock);
else
return do_create_pipe (filedes);
}
/* Portable function to create a pipe. Under Windows the read end is
inheritable. If R_FP is not NULL, an estream is created for the
write end and stored at R_FP. */
gpg_error_t
gnupg_create_outbound_pipe (int filedes[2], estream_t *r_fp, int nonblock)
{
if (r_fp)
return create_pipe_and_estream (filedes, r_fp, 1, nonblock);
else
return do_create_pipe (filedes);
}
/* Portable function to create a pipe. Under Windows both ends are
inheritable. */
gpg_error_t
gnupg_create_pipe (int filedes[2])
{
return do_create_pipe (filedes);
}
/* Close the end of a pipe. */
void
gnupg_close_pipe (int fd)
{
if (fd != -1)
close (fd);
}
#include <sys/socket.h>
struct gnupg_process {
const char *pgmname;
unsigned int terminated :1; /* or detached */
unsigned int flags;
pid_t pid;
int fd_in;
int fd_out;
int fd_err;
int wstatus;
};
static int gnupg_process_syscall_func_initialized;
/* Functions called before and after blocking syscalls. */
static void (*pre_syscall_func) (void);
static void (*post_syscall_func) (void);
static void
check_syscall_func (void)
{
if (!gnupg_process_syscall_func_initialized)
{
gpgrt_get_syscall_clamp (&pre_syscall_func, &post_syscall_func);
gnupg_process_syscall_func_initialized = 1;
}
}
static void
pre_syscall (void)
{
if (pre_syscall_func)
pre_syscall_func ();
}
static void
post_syscall (void)
{
if (post_syscall_func)
post_syscall_func ();
}
static gpg_err_code_t
do_create_socketpair (int filedes[2])
{
gpg_error_t err = 0;
pre_syscall ();
if (socketpair (AF_LOCAL, SOCK_STREAM, 0, filedes) == -1)
{
err = gpg_err_code_from_syserror ();
filedes[0] = filedes[1] = -1;
}
post_syscall ();
return err;
}
static int
posix_open_null (int for_write)
{
int fd;
fd = open ("/dev/null", for_write? O_WRONLY : O_RDONLY);
if (fd == -1)
log_fatal ("failed to open '/dev/null': %s\n", strerror (errno));
return fd;
}
static void
call_spawn_cb (struct spawn_cb_arg *sca,
int fd_in, int fd_out, int fd_err,
void (*spawn_cb) (struct spawn_cb_arg *), void *spawn_cb_arg)
{
sca->fds[0] = fd_in;
sca->fds[1] = fd_out;
sca->fds[2] = fd_err;
sca->except_fds = NULL;
sca->arg = spawn_cb_arg;
if (spawn_cb)
(*spawn_cb) (sca);
}
static void
my_exec (const char *pgmname, const char *argv[], struct spawn_cb_arg *sca)
{
int i;
/* Assign /dev/null to unused FDs. */
for (i = 0; i <= 2; i++)
if (sca->fds[i] == -1)
sca->fds[i] = posix_open_null (i);
/* Connect the standard files. */
for (i = 0; i <= 2; i++)
if (sca->fds[i] != i)
{
if (dup2 (sca->fds[i], i) == -1)
log_fatal ("dup2 std%s failed: %s\n",
i==0?"in":i==1?"out":"err", strerror (errno));
/*
* We don't close sca.fds[i] here, but close them by
* close_all_fds. Note that there may be same one in three of
* sca->fds[i].
*/
}
/* Close all other files. */
close_all_fds (3, sca->except_fds);
execv (pgmname, (char *const *)argv);
/* No way to print anything, as we have may have closed all streams. */
_exit (127);
}
static gpg_err_code_t
spawn_detached (const char *pgmname, const char *argv[],
void (*spawn_cb) (struct spawn_cb_arg *), void *spawn_cb_arg)
{
gpg_err_code_t ec;
pid_t pid;
/* FIXME: Is this GnuPG specific or should we keep it. */
if (getuid() != geteuid())
{
xfree (argv);
return GPG_ERR_BUG;
}
if (access (pgmname, X_OK))
{
ec = gpg_err_code_from_syserror ();
xfree (argv);
return ec;
}
pre_syscall ();
pid = fork ();
post_syscall ();
if (pid == (pid_t)(-1))
{
ec = gpg_err_code_from_syserror ();
log_error (_("error forking process: %s\n"), gpg_strerror (ec));
xfree (argv);
return ec;
}
if (!pid)
{
pid_t pid2;
struct spawn_cb_arg sca;
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. */
call_spawn_cb (&sca, -1, -1, -1, spawn_cb, spawn_cb_arg);
my_exec (pgmname, argv, &sca);
/*NOTREACHED*/
}
pre_syscall ();
if (waitpid (pid, NULL, 0) == -1)
{
post_syscall ();
ec = gpg_err_code_from_syserror ();
log_error ("waitpid failed in gpgrt_spawn_process_detached: %s",
gpg_strerror (ec));
return ec;
}
else
post_syscall ();
return 0;
}
void
gnupg_spawn_helper (struct spawn_cb_arg *sca)
{
int *user_except = sca->arg;
sca->except_fds = user_except;
}
gpg_err_code_t
gnupg_process_spawn (const char *pgmname, const char *argv1[],
unsigned int flags,
void (*spawn_cb) (struct spawn_cb_arg *),
void *spawn_cb_arg,
gnupg_process_t *r_process)
{
gpg_err_code_t ec;
gnupg_process_t process;
int fd_in[2];
int fd_out[2];
int fd_err[2];
pid_t pid;
const char **argv;
int i, j;
check_syscall_func ();
if (r_process)
*r_process = NULL;
/* Create the command line argument array. */
i = 0;
if (argv1)
while (argv1[i])
i++;
argv = xtrycalloc (i+2, sizeof *argv);
if (!argv)
return gpg_err_code_from_syserror ();
argv[0] = strrchr (pgmname, '/');
if (argv[0])
argv[0]++;
else
argv[0] = pgmname;
if (argv1)
for (i=0, j=1; argv1[i]; i++, j++)
argv[j] = argv1[i];
if ((flags & GNUPG_PROCESS_DETACHED))
{
if ((flags & GNUPG_PROCESS_STDFDS_SETTING))
{
xfree (argv);
return GPG_ERR_INV_FLAG;
}
/* In detached case, it must be no R_PROCESS. */
if (r_process)
{
xfree (argv);
return GPG_ERR_INV_ARG;
}
return spawn_detached (pgmname, argv, spawn_cb, spawn_cb_arg);
}
process = xtrycalloc (1, sizeof (struct gnupg_process));
if (process == NULL)
{
xfree (argv);
return gpg_err_code_from_syserror ();
}
process->pgmname = pgmname;
process->flags = flags;
if ((flags & GNUPG_PROCESS_STDINOUT_SOCKETPAIR))
{
ec = do_create_socketpair (fd_in);
if (ec)
{
xfree (process);
xfree (argv);
return ec;
}
fd_out[0] = dup (fd_in[0]);
fd_out[1] = dup (fd_in[1]);
}
else
{
if ((flags & GNUPG_PROCESS_STDIN_PIPE))
{
ec = do_create_pipe (fd_in);
if (ec)
{
xfree (process);
xfree (argv);
return ec;
}
}
else if ((flags & GNUPG_PROCESS_STDIN_KEEP))
{
fd_in[0] = 0;
fd_in[1] = -1;
}
else
{
fd_in[0] = -1;
fd_in[1] = -1;
}
if ((flags & GNUPG_PROCESS_STDOUT_PIPE))
{
ec = do_create_pipe (fd_out);
if (ec)
{
if (fd_in[0] >= 0 && fd_in[0] != 0)
close (fd_in[0]);
if (fd_in[1] >= 0)
close (fd_in[1]);
xfree (process);
xfree (argv);
return ec;
}
}
else if ((flags & GNUPG_PROCESS_STDOUT_KEEP))
{
fd_out[0] = -1;
fd_out[1] = 1;
}
else
{
fd_out[0] = -1;
fd_out[1] = -1;
}
}
if ((flags & GNUPG_PROCESS_STDERR_PIPE))
{
ec = do_create_pipe (fd_err);
if (ec)
{
if (fd_in[0] >= 0 && fd_in[0] != 0)
close (fd_in[0]);
if (fd_in[1] >= 0)
close (fd_in[1]);
if (fd_out[0] >= 0)
close (fd_out[0]);
if (fd_out[1] >= 0 && fd_out[1] != 1)
close (fd_out[1]);
xfree (process);
xfree (argv);
return ec;
}
}
else if ((flags & GNUPG_PROCESS_STDERR_KEEP))
{
fd_err[0] = -1;
fd_err[1] = 2;
}
else
{
fd_err[0] = -1;
fd_err[1] = -1;
}
pre_syscall ();
pid = fork ();
post_syscall ();
if (pid == (pid_t)(-1))
{
ec = gpg_err_code_from_syserror ();
log_error (_("error forking process: %s\n"), gpg_strerror (ec));
if (fd_in[0] >= 0 && fd_in[0] != 0)
close (fd_in[0]);
if (fd_in[1] >= 0)
close (fd_in[1]);
if (fd_out[0] >= 0)
close (fd_out[0]);
if (fd_out[1] >= 0 && fd_out[1] != 1)
close (fd_out[1]);
if (fd_err[0] >= 0)
close (fd_err[0]);
if (fd_err[1] >= 0 && fd_err[1] != 2)
close (fd_err[1]);
xfree (process);
xfree (argv);
return ec;
}
if (!pid)
{
struct spawn_cb_arg sca;
if (fd_in[1] >= 0)
close (fd_in[1]);
if (fd_out[0] >= 0)
close (fd_out[0]);
if (fd_err[0] >= 0)
close (fd_err[0]);
call_spawn_cb (&sca, fd_in[0], fd_out[1], fd_err[1],
spawn_cb, spawn_cb_arg);
/* Run child. */
my_exec (pgmname, argv, &sca);
/*NOTREACHED*/
}
xfree (argv);
process->pid = pid;
if (fd_in[0] >= 0 && fd_in[0] != 0)
close (fd_in[0]);
if (fd_out[1] >= 0 && fd_out[1] != 1)
close (fd_out[1]);
if (fd_err[1] >= 0 && fd_err[1] != 2)
close (fd_err[1]);
process->fd_in = fd_in[1];
process->fd_out = fd_out[0];
process->fd_err = fd_err[0];
process->wstatus = -1;
process->terminated = 0;
if (r_process == NULL)
{
ec = gnupg_process_wait (process, 1);
gnupg_process_release (process);
return ec;
}
*r_process = process;
return 0;
}
static gpg_err_code_t
process_kill (gnupg_process_t process, int sig)
{
gpg_err_code_t ec = 0;
pid_t pid = process->pid;
pre_syscall ();
if (kill (pid, sig) < 0)
ec = gpg_err_code_from_syserror ();
post_syscall ();
return ec;
}
gpg_err_code_t
gnupg_process_terminate (gnupg_process_t process)
{
return process_kill (process, SIGTERM);
}
gpg_err_code_t
gnupg_process_get_fds (gnupg_process_t process, unsigned int flags,
int *r_fd_in, int *r_fd_out, int *r_fd_err)
{
(void)flags;
if (r_fd_in)
{
*r_fd_in = process->fd_in;
process->fd_in = -1;
}
if (r_fd_out)
{
*r_fd_out = process->fd_out;
process->fd_out = -1;
}
if (r_fd_err)
{
*r_fd_err = process->fd_err;
process->fd_err = -1;
}
return 0;
}
gpg_err_code_t
gnupg_process_get_streams (gnupg_process_t process, unsigned int flags,
gpgrt_stream_t *r_fp_in, gpgrt_stream_t *r_fp_out,
gpgrt_stream_t *r_fp_err)
{
int nonblock = (flags & GNUPG_PROCESS_STREAM_NONBLOCK)? 1: 0;
if (r_fp_in)
{
*r_fp_in = es_fdopen (process->fd_in, nonblock? "w,nonblock" : "w");
process->fd_in = -1;
}
if (r_fp_out)
{
*r_fp_out = es_fdopen (process->fd_out, nonblock? "r,nonblock" : "r");
process->fd_out = -1;
}
if (r_fp_err)
{
*r_fp_err = es_fdopen (process->fd_err, nonblock? "r,nonblock" : "r");
process->fd_err = -1;
}
return 0;
}
static gpg_err_code_t
process_vctl (gnupg_process_t process, unsigned int request, va_list arg_ptr)
{
switch (request)
{
case GNUPG_PROCESS_NOP:
return 0;
case GNUPG_PROCESS_GET_PROC_ID:
{
int *r_id = va_arg (arg_ptr, int *);
if (r_id == NULL)
return GPG_ERR_INV_VALUE;
*r_id = (int)process->pid;
return 0;
}
case GNUPG_PROCESS_GET_EXIT_ID:
{
int status = process->wstatus;
int *r_exit_status = va_arg (arg_ptr, int *);
if (!process->terminated)
return GPG_ERR_UNFINISHED;
if (WIFEXITED (status))
{
if (r_exit_status)
*r_exit_status = WEXITSTATUS (status);
}
else
*r_exit_status = -1;
return 0;
}
case GNUPG_PROCESS_GET_PID:
{
pid_t *r_pid = va_arg (arg_ptr, pid_t *);
if (r_pid == NULL)
return GPG_ERR_INV_VALUE;
*r_pid = process->pid;
return 0;
}
case GNUPG_PROCESS_GET_WSTATUS:
{
int status = process->wstatus;
int *r_if_exited = va_arg (arg_ptr, int *);
int *r_if_signaled = va_arg (arg_ptr, int *);
int *r_exit_status = va_arg (arg_ptr, int *);
int *r_termsig = va_arg (arg_ptr, int *);
if (!process->terminated)
return GPG_ERR_UNFINISHED;
if (WIFEXITED (status))
{
if (r_if_exited)
*r_if_exited = 1;
if (r_if_signaled)
*r_if_signaled = 0;
if (r_exit_status)
*r_exit_status = WEXITSTATUS (status);
if (r_termsig)
*r_termsig = 0;
}
else if (WIFSIGNALED (status))
{
if (r_if_exited)
*r_if_exited = 0;
if (r_if_signaled)
*r_if_signaled = 1;
if (r_exit_status)
*r_exit_status = 0;
if (r_termsig)
*r_termsig = WTERMSIG (status);
}
return 0;
}
case GNUPG_PROCESS_KILL:
{
int sig = va_arg (arg_ptr, int);
return process_kill (process, sig);
}
default:
break;
}
return GPG_ERR_UNKNOWN_COMMAND;
}
gpg_err_code_t
gnupg_process_ctl (gnupg_process_t process, unsigned int request, ...)
{
va_list arg_ptr;
gpg_err_code_t ec;
va_start (arg_ptr, request);
ec = process_vctl (process, request, arg_ptr);
va_end (arg_ptr);
return ec;
}
gpg_err_code_t
gnupg_process_wait (gnupg_process_t process, int hang)
{
gpg_err_code_t ec;
int status;
pid_t pid;
if (process->terminated)
/* Already terminated. */
return 0;
pre_syscall ();
while ((pid = waitpid (process->pid, &status, hang? 0: WNOHANG))
== (pid_t)(-1) && errno == EINTR);
post_syscall ();
if (pid == (pid_t)(-1))
{
ec = gpg_err_code_from_syserror ();
log_error (_("waiting for process %d to terminate failed: %s\n"),
(int)pid, gpg_strerror (ec));
}
else if (!pid)
{
ec = GPG_ERR_TIMEOUT; /* Still running. */
}
else
{
process->terminated = 1;
process->wstatus = status;
ec = 0;
}
return ec;
}
void
gnupg_process_release (gnupg_process_t process)
{
if (!process)
return;
if (process->terminated)
{
gnupg_process_terminate (process);
gnupg_process_wait (process, 1);
}
xfree (process);
}
gpg_err_code_t
gnupg_process_wait_list (gnupg_process_t *process_list, int count, int hang)
{
gpg_err_code_t ec = 0;
int i;
for (i = 0; i < count; i++)
{
if (process_list[i]->terminated)
continue;
ec = gnupg_process_wait (process_list[i], hang);
if (ec)
break;
}
return ec;
}
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