/* exechelp.c - Fork and exec helpers for POSIX * Copyright (C) 2004, 2007, 2008, 2009, * 2010 Free Software Foundation, Inc. * * This file is part of GnuPG. * * GnuPG 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 3 of the License, or * (at your option) any later version. * * GnuPG 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 . */ #include #if defined(HAVE_W32_SYSTEM) || defined (HAVE_W32CE_SYSTEM) #error This code is only used on POSIX #endif #include #include #include #include #include #ifdef HAVE_SIGNAL_H # include #endif #include #include #ifdef WITHOUT_GNU_PTH /* Give the Makefile a chance to build without Pth. */ #undef HAVE_PTH #undef USE_GNU_PTH #endif #ifdef USE_GNU_PTH #include #endif #include #ifdef HAVE_GETRLIMIT #include #include #endif /*HAVE_GETRLIMIT*/ #ifdef HAVE_STAT # include #endif #include "util.h" #include "i18n.h" #include "sysutils.h" #include "exechelp.h" /* We have the usual problem here: Some modules are linked against pth and some are not. However we want to use pth_fork and pth_waitpid here. Using a weak symbol works but is not portable - we should provide a an explicit dummy pth module instead of using the pragma. */ #pragma weak pth_fork #pragma weak pth_waitpid /* 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; # 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. */ 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 fucntion 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; } /* 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, 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 = xcalloc (i+2, sizeof *arg_list); arg_list[0] = strrchr (pgmname, '/'); if (arg_list[0]) arg_list[0]++; else arg_list[0] = xstrdup (pgmname); 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) 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) 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, NULL); if (preexec) preexec (); execv (pgmname, arg_list); /* No way to print anything, as we have closed all streams. */ _exit (127); } static gpg_error_t do_create_pipe (int filedes[2]) { gpg_error_t err = 0; if (pipe (filedes) == -1) { err = gpg_error_from_syserror (); filedes[0] = filedes[1] = -1; } return err; } /* Portable function to create a pipe. Under Windows the write end is inheritable. */ gpg_error_t gnupg_create_inbound_pipe (int filedes[2]) { return do_create_pipe (filedes); } /* Portable function to create a pipe. Under Windows the read end is inheritable. */ gpg_error_t gnupg_create_outbound_pipe (int filedes[2]) { return do_create_pipe (filedes); } /* Fork and exec the PGMNAME, see exechelp.h for details. */ gpg_error_t gnupg_spawn_process (const char *pgmname, const char *argv[], estream_t infile, estream_t outfile, void (*preexec)(void), unsigned int flags, estream_t *statusfile, pid_t *pid) { gpg_error_t err; int fd, fdout, rp[2]; (void)flags; /* Currently not used. */ *statusfile = NULL; *pid = (pid_t)(-1); es_fflush (infile); es_rewind (infile); fd = es_fileno (infile); fdout = es_fileno (outfile); if (fd == -1 || fdout == -1) log_fatal ("no file descriptor for file passed to gnupg_spawn_process\n"); if (pipe (rp) == -1) { err = gpg_error_from_syserror (); log_error (_("error creating a pipe: %s\n"), strerror (errno)); return err; } #ifdef USE_GNU_PTH *pid = pth_fork? pth_fork () : fork (); #else *pid = fork (); #endif if (*pid == (pid_t)(-1)) { err = gpg_error_from_syserror (); log_error (_("error forking process: %s\n"), strerror (errno)); close (rp[0]); close (rp[1]); return err; } if (!*pid) { gcry_control (GCRYCTL_TERM_SECMEM); /* Run child. */ do_exec (pgmname, argv, fd, fdout, rp[1], preexec); /*NOTREACHED*/ } /* Parent. */ close (rp[1]); *statusfile = es_fdopen (rp[0], "r"); if (!*statusfile) { err = gpg_error_from_syserror (); log_error (_("can't fdopen pipe for reading: %s\n"), strerror (errno)); kill (*pid, SIGTERM); *pid = (pid_t)(-1); return err; } return 0; } /* Simplified version of gnupg_spawn_process. This function forks and then execs PGMNAME, while connecting INFD to stdin, OUTFD to stdout and ERRFD to stderr (any of them may be -1 to connect them to /dev/null). The arguments for the process are expected in the NULL terminated array ARGV. The program name itself should not be included there. Calling gnupg_wait_process is required. Returns 0 on success or an error code. */ gpg_error_t gnupg_spawn_process_fd (const char *pgmname, const char *argv[], int infd, int outfd, int errfd, pid_t *pid) { gpg_error_t err; #ifdef USE_GNU_PTH *pid = pth_fork? pth_fork () : fork (); #else *pid = fork (); #endif if (*pid == (pid_t)(-1)) { err = gpg_error_from_syserror (); log_error (_("error forking process: %s\n"), strerror (errno)); return err; } if (!*pid) { gcry_control (GCRYCTL_TERM_SECMEM); /* Run child. */ do_exec (pgmname, argv, infd, outfd, errfd, NULL); /*NOTREACHED*/ } return 0; } /* Wait for the process identified by PID to terminate. PGMNAME should be the same as supplied to the spawn function and is only used for diagnostics. Returns 0 if the process succeeded, GPG_ERR_GENERAL for any failures of the spawned program or other error codes. If EXITCODE is not NULL the exit code of the process is stored at this address or -1 if it could not be retrieved. */ gpg_error_t gnupg_wait_process (const char *pgmname, pid_t pid, int *exitcode) { gpg_err_code_t ec; int i, status; if (exitcode) *exitcode = -1; if (pid == (pid_t)(-1)) return gpg_error (GPG_ERR_INV_VALUE); #ifdef USE_GNU_PTH i = pth_waitpid ? pth_waitpid (pid, &status, 0) : waitpid (pid, &status, 0); #else while ( (i=waitpid (pid, &status, 0)) == -1 && errno == EINTR) ; #endif if (i == (pid_t)(-1)) { log_error (_("waiting for process %d to terminate failed: %s\n"), (int)pid, strerror (errno)); ec = gpg_err_code_from_errno (errno); } else if (WIFEXITED (status) && WEXITSTATUS (status) == 127) { log_error (_("error running `%s': probably not installed\n"), pgmname); ec = GPG_ERR_CONFIGURATION; } else if (WIFEXITED (status) && WEXITSTATUS (status)) { log_error (_("error running `%s': exit status %d\n"), pgmname, WEXITSTATUS (status)); if (exitcode) *exitcode = WEXITSTATUS (status); ec = GPG_ERR_GENERAL; } else if (!WIFEXITED (status)) { log_error (_("error running `%s': terminated\n"), pgmname); ec = GPG_ERR_GENERAL; } else { if (exitcode) *exitcode = 0; ec = 0; } return gpg_err_make (GPG_ERR_SOURCE_DEFAULT, ec); } /* Spawn a new process and immediatley detach from it. The name of the program to exec is PGMNAME and its arguments are in ARGV (the programname is automatically passed as first argument). Environment strings in ENVP are set. An error is returned if pgmname is not executable; to make this work it is necessary to provide an absolute file name. All standard file descriptors are connected to /dev/null. */ gpg_error_t gnupg_spawn_process_detached (const char *pgmname, const char *argv[], const char *envp[] ) { pid_t pid; int i; if (getuid() != geteuid()) return gpg_error (GPG_ERR_BUG); if (access (pgmname, X_OK)) return gpg_error_from_syserror (); #ifdef USE_GNU_PTH pid = pth_fork? pth_fork () : fork (); #else pid = fork (); #endif if (pid == (pid_t)(-1)) { log_error (_("error forking process: %s\n"), strerror (errno)); return gpg_error_from_syserror (); } if (!pid) { gcry_control (GCRYCTL_TERM_SECMEM); if (setsid() == -1 || chdir ("/")) _exit (1); pid = fork (); /* Double fork to let init takes over the new child. */ if (pid == (pid_t)(-1)) _exit (1); if (pid) _exit (0); /* Let the parent exit immediately. */ if (envp) for (i=0; envp[i]; i++) putenv (xstrdup (envp[i])); do_exec (pgmname, argv, -1, -1, -1, NULL); /*NOTREACHED*/ } if (waitpid (pid, NULL, 0) == -1) log_error ("waitpid failed in gnupg_spawn_process_detached: %s", strerror (errno)); 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 gnupg_kill_process (pid_t pid) { if (pid != (pid_t)(-1)) { kill (pid, SIGTERM); } }