/* 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 . * SPDX-License-Identifier: LGPL-2.1+ * * This file was originally a part of GnuPG. */ #include #if defined(HAVE_W32_SYSTEM) #error This code is only used on POSIX #endif #include #include #include #include #include #ifdef HAVE_SIGNAL_H # include #endif #include #include #include #include #ifdef HAVE_GETRLIMIT #include #include #endif /*HAVE_GETRLIMIT*/ #ifdef HAVE_STAT # include #endif #if __linux__ # include # include #endif /*__linux__ */ #include "gpgrt-int.h" /* (Only glibc's unistd.h declares this iff _GNU_SOURCE is used.) */ extern char **environ; /* Definition for the gpgrt_spawn_actions_t. Note that there is a * different one for Windows. */ struct gpgrt_spawn_actions { int fd[3]; const int *except_fds; char **environ; void (*atfork) (void *); void *atfork_arg; }; /* Definition for the gpgrt_process_t. Note that there is a different * one for Windows. */ struct gpgrt_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; }; /* 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; 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 _gpgrt_close_all_fds (int first, const 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); } /* 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) { _gpgrt_post_syscall (); err = _gpg_err_code_from_syserror (); _gpgrt_log_info (_("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_info (_("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); } static gpg_err_code_t do_create_socketpair (int filedes[2]) { gpg_error_t err = 0; _gpgrt_pre_syscall (); if (socketpair (AF_LOCAL, SOCK_STREAM, 0, filedes) == -1) { err = _gpg_err_code_from_syserror (); filedes[0] = filedes[1] = -1; } _gpgrt_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) _gpgrt_log_fatal ("failed to open '/dev/null': %s\n", strerror (errno)); return fd; } static int my_exec (const char *pgmname, const char *argv[], gpgrt_spawn_actions_t act) { int i; /* Assign /dev/null to unused FDs. */ for (i = 0; i <= 2; i++) if (act->fd[i] == -1) act->fd[i] = posix_open_null (i); /* Connect the standard files. */ for (i = 0; i <= 2; i++) if (act->fd[i] != i) { if (dup2 (act->fd[i], i) == -1) _gpgrt_log_fatal ("dup2 std%s failed: %s\n", i==0?"in":i==1?"out":"err", strerror (errno)); /* * We don't close act->fd[i] here, but close them by * close_all_fds. Note that there may be same one in three of * act->fd[i]. */ } /* Close all other files. */ _gpgrt_close_all_fds (3, act->except_fds); if (act->environ) environ = act->environ; if (act->atfork) act->atfork (act->atfork_arg); /* This use case is for assuan pipe connect with no PGMNAME */ if (pgmname == NULL) return 0; execv (pgmname, (char *const *)argv); /* No way to print anything, as we have may have closed all streams. */ _exit (127); return -1; } static gpg_err_code_t spawn_detached (const char *pgmname, const char *argv[], gpgrt_spawn_actions_t act) { gpg_err_code_t ec; pid_t pid; if (access (pgmname, X_OK)) { ec = _gpg_err_code_from_syserror (); xfree (argv); return ec; } _gpgrt_pre_syscall (); pid = fork (); _gpgrt_post_syscall (); if (pid == (pid_t)(-1)) { ec = _gpg_err_code_from_syserror (); _gpgrt_log_info (_("error forking process: %s\n"), _gpg_strerror (ec)); xfree (argv); return ec; } if (!pid) { pid_t pid2; 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. */ my_exec (pgmname, argv, act); /*NOTREACHED*/ } xfree (argv); _gpgrt_pre_syscall (); if (waitpid (pid, NULL, 0) == -1) { _gpgrt_post_syscall (); ec = _gpg_err_code_from_syserror (); _gpgrt_log_info ("waitpid failed in gpgrt_spawn_process_detached: %s", _gpg_strerror (ec)); return ec; } else _gpgrt_post_syscall (); return 0; } gpg_err_code_t _gpgrt_spawn_actions_new (gpgrt_spawn_actions_t *r_act) { gpgrt_spawn_actions_t act; int i; *r_act = NULL; act = xtrycalloc (1, sizeof (struct gpgrt_spawn_actions)); if (act == NULL) return _gpg_err_code_from_syserror (); for (i = 0; i <= 2; i++) act->fd[i] = -1; *r_act = act; return 0; } void _gpgrt_spawn_actions_release (gpgrt_spawn_actions_t act) { if (!act) return; xfree (act); } void _gpgrt_spawn_actions_set_environ (gpgrt_spawn_actions_t act, char **environ_for_child) { act->environ = environ_for_child; } void _gpgrt_spawn_actions_set_atfork (gpgrt_spawn_actions_t act, void (*atfork)(void *), void *arg) { act->atfork = atfork; act->atfork_arg = arg; } void _gpgrt_spawn_actions_set_redirect (gpgrt_spawn_actions_t act, int in, int out, int err) { act->fd[0] = in; act->fd[1] = out; act->fd[2] = err; } void _gpgrt_spawn_actions_set_inherit_fds (gpgrt_spawn_actions_t act, const int *fds) { act->except_fds = fds; } gpg_err_code_t _gpgrt_process_spawn (const char *pgmname, const char *argv1[], unsigned int flags, gpgrt_spawn_actions_t act, gpgrt_process_t *r_process) { gpg_err_code_t ec; gpgrt_process_t process; int fd_in[2]; int fd_out[2]; int fd_err[2]; pid_t pid; const char **argv; int i, j; struct gpgrt_spawn_actions act_default; if (!act) { memset (&act_default, 0, sizeof (act_default)); for (i = 0; i <= 2; i++) act_default.fd[i] = -1; act = &act_default; } 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 (); if (pgmname) 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 & GPGRT_PROCESS_DETACHED)) { if ((flags & GPGRT_PROCESS_STDFDS_SETTING)) { xfree (argv); return GPG_ERR_INV_FLAG; } /* In detached case, it must be no R_PROCESS. */ if (r_process || pgmname == NULL) { xfree (argv); return GPG_ERR_INV_ARG; } if (!(flags & GPGRT_PROCESS_NO_EUID_CHECK)) { if (getuid() != geteuid()) { xfree (argv); return GPG_ERR_FORBIDDEN; } } return spawn_detached (pgmname, argv, act); } process = xtrycalloc (1, sizeof (struct gpgrt_process)); if (process == NULL) { xfree (argv); return _gpg_err_code_from_syserror (); } process->pgmname = pgmname; process->flags = flags; if ((flags & GPGRT_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 & GPGRT_PROCESS_STDIN_PIPE)) { ec = do_create_pipe (fd_in); if (ec) { xfree (process); xfree (argv); return ec; } } else if ((flags & GPGRT_PROCESS_STDIN_KEEP)) { fd_in[0] = 0; fd_in[1] = -1; } else { fd_in[0] = -1; fd_in[1] = -1; } if ((flags & GPGRT_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 & GPGRT_PROCESS_STDOUT_KEEP)) { fd_out[0] = -1; fd_out[1] = 1; } else { fd_out[0] = -1; fd_out[1] = -1; } } if ((flags & GPGRT_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 & GPGRT_PROCESS_STDERR_KEEP)) { fd_err[0] = -1; fd_err[1] = 2; } else { fd_err[0] = -1; fd_err[1] = -1; } _gpgrt_pre_syscall (); pid = fork (); _gpgrt_post_syscall (); if (pid == (pid_t)(-1)) { ec = _gpg_err_code_from_syserror (); _gpgrt_log_info (_("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) { 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]); if (act->fd[0] < 0) act->fd[0] = fd_in[0]; if (act->fd[1] < 0) act->fd[1] = fd_out[1]; if (act->fd[2] < 0) act->fd[2] = fd_err[1]; /* Run child. */ if (!my_exec (pgmname, argv, act)) { xfree (process); xfree (argv); *r_process = NULL; return 0; } /*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 = _gpgrt_process_wait (process, 1); _gpgrt_process_release (process); return ec; } *r_process = process; return 0; } static gpg_err_code_t process_kill (gpgrt_process_t process, int sig) { gpg_err_code_t ec = 0; pid_t pid = process->pid; _gpgrt_pre_syscall (); if (kill (pid, sig) < 0) ec = _gpg_err_code_from_syserror (); _gpgrt_post_syscall (); return ec; } gpg_err_code_t _gpgrt_process_terminate (gpgrt_process_t process) { return process_kill (process, SIGTERM); } gpg_err_code_t _gpgrt_process_get_fds (gpgrt_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 _gpgrt_process_get_streams (gpgrt_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 & GPGRT_PROCESS_STREAM_NONBLOCK)? 1: 0; if (r_fp_in) { *r_fp_in = _gpgrt_fdopen (process->fd_in, nonblock? "w,nonblock" : "w"); process->fd_in = -1; } if (r_fp_out) { *r_fp_out = _gpgrt_fdopen (process->fd_out, nonblock? "r,nonblock" : "r"); process->fd_out = -1; } if (r_fp_err) { *r_fp_err = _gpgrt_fdopen (process->fd_err, nonblock? "r,nonblock" : "r"); process->fd_err = -1; } return 0; } gpg_err_code_t _gpgrt_process_vctl (gpgrt_process_t process, unsigned int request, va_list arg_ptr) { switch (request) { case GPGRT_PROCESS_NOP: return 0; case GPGRT_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 GPGRT_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 GPGRT_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 GPGRT_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 GPGRT_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 _gpgrt_process_wait (gpgrt_process_t process, int hang) { gpg_err_code_t ec; int status; pid_t pid; if (process->terminated) /* Already terminated. */ return 0; _gpgrt_pre_syscall (); while ((pid = waitpid (process->pid, &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_info (_("waiting for process %d 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 _gpgrt_process_release (gpgrt_process_t process) { if (!process) return; if (!process->terminated) { _gpgrt_process_terminate (process); _gpgrt_process_wait (process, 1); } xfree (process); } gpg_err_code_t _gpgrt_process_wait_list (gpgrt_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 = _gpgrt_process_wait (process_list[i], hang); if (ec) break; } return ec; }