| /* Guts of POSIX spawn interface. Generic POSIX.1 version. |
| Copyright (C) 2000-2018 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 <spawn.h> |
| #include <assert.h> |
| #include <fcntl.h> |
| #include <paths.h> |
| #include <string.h> |
| #include <sys/resource.h> |
| #include <sys/wait.h> |
| #include <sys/param.h> |
| #include <sys/mman.h> |
| #include <not-cancel.h> |
| #include <local-setxid.h> |
| #include <shlib-compat.h> |
| #include <nptl/pthreadP.h> |
| #include <dl-sysdep.h> |
| #include <libc-pointer-arith.h> |
| #include <ldsodefs.h> |
| #include "spawn_int.h" |
| |
| |
| /* The Unix standard contains a long explanation of the way to signal |
| an error after the fork() was successful. Since no new wait status |
| was wanted there is no way to signal an error using one of the |
| available methods. The committee chose to signal an error by a |
| normal program exit with the exit code 127. */ |
| #define SPAWN_ERROR 127 |
| |
| struct posix_spawn_args |
| { |
| sigset_t oldmask; |
| const char *file; |
| int (*exec) (const char *, char *const *, char *const *); |
| const posix_spawn_file_actions_t *fa; |
| const posix_spawnattr_t *restrict attr; |
| char *const *argv; |
| ptrdiff_t argc; |
| char *const *envp; |
| int xflags; |
| int pipe[2]; |
| }; |
| |
| /* Older version requires that shell script without shebang definition |
| to be called explicitly using /bin/sh (_PATH_BSHELL). */ |
| static void |
| maybe_script_execute (struct posix_spawn_args *args) |
| { |
| if (SHLIB_COMPAT (libc, GLIBC_2_2, GLIBC_2_15) |
| && (args->xflags & SPAWN_XFLAGS_TRY_SHELL) && errno == ENOEXEC) |
| { |
| char *const *argv = args->argv; |
| ptrdiff_t argc = args->argc; |
| |
| /* Construct an argument list for the shell. */ |
| char *new_argv[argc + 1]; |
| new_argv[0] = (char *) _PATH_BSHELL; |
| new_argv[1] = (char *) args->file; |
| if (argc > 1) |
| memcpy (new_argv + 2, argv + 1, argc * sizeof(char *)); |
| else |
| new_argv[2] = NULL; |
| |
| /* Execute the shell. */ |
| args->exec (new_argv[0], new_argv, args->envp); |
| } |
| } |
| |
| /* Function used in the clone call to setup the signals mask, posix_spawn |
| attributes, and file actions. */ |
| static int |
| __spawni_child (void *arguments) |
| { |
| struct posix_spawn_args *args = arguments; |
| const posix_spawnattr_t *restrict attr = args->attr; |
| const posix_spawn_file_actions_t *file_actions = args->fa; |
| int ret; |
| |
| __close (args->pipe[0]); |
| |
| /* Set signal default action. */ |
| if ((attr->__flags & POSIX_SPAWN_SETSIGDEF) != 0) |
| { |
| /* We have to iterate over all signals. This could possibly be |
| done better but it requires system specific solutions since |
| the sigset_t data type can be very different on different |
| architectures. */ |
| int sig; |
| struct sigaction sa; |
| |
| memset (&sa, '\0', sizeof (sa)); |
| sa.sa_handler = SIG_DFL; |
| |
| for (sig = 1; sig <= _NSIG; ++sig) |
| if (__sigismember (&attr->__sd, sig) != 0 |
| && __sigaction (sig, &sa, NULL) != 0) |
| goto fail; |
| } |
| |
| #ifdef _POSIX_PRIORITY_SCHEDULING |
| /* Set the scheduling algorithm and parameters. */ |
| if ((attr->__flags & (POSIX_SPAWN_SETSCHEDPARAM | POSIX_SPAWN_SETSCHEDULER)) |
| == POSIX_SPAWN_SETSCHEDPARAM) |
| { |
| if (__sched_setparam (0, &attr->__sp) == -1) |
| goto fail; |
| } |
| else if ((attr->__flags & POSIX_SPAWN_SETSCHEDULER) != 0) |
| { |
| if (__sched_setscheduler (0, attr->__policy, &attr->__sp) == -1) |
| goto fail; |
| } |
| #endif |
| |
| /* Set the process session ID. */ |
| if ((attr->__flags & POSIX_SPAWN_SETSID) != 0 |
| && __setsid () < 0) |
| goto fail; |
| |
| /* Set the process group ID. */ |
| if ((attr->__flags & POSIX_SPAWN_SETPGROUP) != 0 |
| && __setpgid (0, attr->__pgrp) != 0) |
| goto fail; |
| |
| /* Set the effective user and group IDs. */ |
| if ((attr->__flags & POSIX_SPAWN_RESETIDS) != 0 |
| && (local_seteuid (__getuid ()) != 0 |
| || local_setegid (__getgid ())) != 0) |
| goto fail; |
| |
| /* Execute the file actions. */ |
| if (file_actions != NULL) |
| { |
| int cnt; |
| struct rlimit64 fdlimit; |
| bool have_fdlimit = false; |
| |
| for (cnt = 0; cnt < file_actions->__used; ++cnt) |
| { |
| struct __spawn_action *action = &file_actions->__actions[cnt]; |
| |
| switch (action->tag) |
| { |
| case spawn_do_close: |
| if (__close_nocancel (action->action.close_action.fd) != 0) |
| { |
| if (have_fdlimit == 0) |
| { |
| __getrlimit64 (RLIMIT_NOFILE, &fdlimit); |
| have_fdlimit = true; |
| } |
| |
| /* Only signal errors for file descriptors out of range. */ |
| if (action->action.close_action.fd < 0 |
| || action->action.close_action.fd >= fdlimit.rlim_cur) |
| goto fail; |
| } |
| break; |
| |
| case spawn_do_open: |
| { |
| /* POSIX states that if fildes was already an open file descriptor, |
| it shall be closed before the new file is opened. This avoid |
| pontential issues when posix_spawn plus addopen action is called |
| with the process already at maximum number of file descriptor |
| opened and also for multiple actions on single-open special |
| paths (like /dev/watchdog). */ |
| __close_nocancel (action->action.open_action.fd); |
| |
| int new_fd = __open_nocancel (action->action.open_action.path, |
| action->action.open_action.oflag |
| | O_LARGEFILE, |
| action->action.open_action.mode); |
| |
| if (new_fd == -1) |
| goto fail; |
| |
| /* Make sure the desired file descriptor is used. */ |
| if (new_fd != action->action.open_action.fd) |
| { |
| if (__dup2 (new_fd, action->action.open_action.fd) |
| != action->action.open_action.fd) |
| goto fail; |
| |
| if (__close_nocancel (new_fd) != 0) |
| goto fail; |
| } |
| } |
| break; |
| |
| case spawn_do_dup2: |
| if (__dup2 (action->action.dup2_action.fd, |
| action->action.dup2_action.newfd) |
| != action->action.dup2_action.newfd) |
| goto fail; |
| break; |
| } |
| } |
| } |
| |
| /* Set the initial signal mask of the child if POSIX_SPAWN_SETSIGMASK |
| is set, otherwise restore the previous one. */ |
| __sigprocmask (SIG_SETMASK, (attr->__flags & POSIX_SPAWN_SETSIGMASK) |
| ? &attr->__ss : &args->oldmask, 0); |
| |
| args->exec (args->file, args->argv, args->envp); |
| |
| /* This is compatibility function required to enable posix_spawn run |
| script without shebang definition for older posix_spawn versions |
| (2.15). */ |
| maybe_script_execute (args); |
| |
| fail: |
| /* errno should have an appropriate non-zero value; otherwise, |
| there's a bug in glibc or the kernel. For lack of an error code |
| (EINTERNALBUG) describing that, use ECHILD. Another option would |
| be to set args->err to some negative sentinel and have the parent |
| abort(), but that seems needlessly harsh. */ |
| ret = errno ? : ECHILD; |
| if (ret) |
| /* Since sizeof errno < PIPE_BUF, the write is atomic. */ |
| while (__write_nocancel (args->pipe[1], &ret, sizeof (ret)) < 0); |
| |
| _exit (SPAWN_ERROR); |
| } |
| |
| /* Spawn a new process executing PATH with the attributes describes in *ATTRP. |
| Before running the process perform the actions described in FILE-ACTIONS. */ |
| int |
| __spawnix (pid_t *pid, const char *file, |
| const posix_spawn_file_actions_t *file_actions, |
| const posix_spawnattr_t *attrp, char *const argv[], |
| char *const envp[], int xflags, |
| int (*exec) (const char *, char *const *, char *const *)) |
| { |
| struct posix_spawn_args args; |
| int ec; |
| |
| if (__pipe2 (args.pipe, O_CLOEXEC)) |
| return errno; |
| |
| /* Disable asynchronous cancellation. */ |
| int state; |
| __libc_ptf_call (__pthread_setcancelstate, |
| (PTHREAD_CANCEL_DISABLE, &state), 0); |
| |
| ptrdiff_t argc = 0; |
| ptrdiff_t limit = INT_MAX - 1; |
| while (argv[argc++] != NULL) |
| if (argc == limit) |
| { |
| errno = E2BIG; |
| return errno; |
| } |
| |
| args.file = file; |
| args.exec = exec; |
| args.fa = file_actions; |
| args.attr = attrp ? attrp : &(const posix_spawnattr_t) { 0 }; |
| args.argv = argv; |
| args.argc = argc; |
| args.envp = envp; |
| args.xflags = xflags; |
| |
| /* Generate the new process. */ |
| pid_t new_pid = __fork (); |
| |
| if (new_pid == 0) |
| __spawni_child (&args); |
| else if (new_pid > 0) |
| { |
| __close (args.pipe[1]); |
| |
| if (__read (args.pipe[0], &ec, sizeof ec) != sizeof ec) |
| ec = 0; |
| else |
| __waitpid (new_pid, &(int) { 0 }, 0); |
| } |
| else |
| ec = errno; |
| |
| __close (args.pipe[0]); |
| |
| if ((ec == 0) && (pid != NULL)) |
| *pid = new_pid; |
| |
| __libc_ptf_call (__pthread_setcancelstate, (state, NULL), 0); |
| |
| return ec; |
| } |
| |
| int |
| __spawni (pid_t * pid, const char *file, |
| const posix_spawn_file_actions_t * acts, |
| const posix_spawnattr_t * attrp, char *const argv[], |
| char *const envp[], int xflags) |
| { |
| return __spawnix (pid, file, acts, attrp, argv, envp, xflags, |
| xflags & SPAWN_XFLAGS_USE_PATH ? __execvpe : __execve); |
| } |