/* pressure-vessel-adverb — run a command with an altered execution environment, * e.g. holding a lock. * The lock is basically flock(1), but using fcntl locks compatible with * those used by bubblewrap and Flatpak. * * Copyright © 2019-2020 Collabora Ltd. * * SPDX-License-Identifier: LGPL-2.1-or-later * * This program 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. * * This 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 this library. If not, see <http://www.gnu.org/licenses/>. */ #include "config.h" #include "subprojects/libglnx/config.h" #include <fcntl.h> #include <locale.h> #include <sysexits.h> #include <sys/prctl.h> #include <sys/types.h> #include <sys/wait.h> #include <glib.h> #include <glib/gstdio.h> #include <gio/gio.h> #include "glib-backports.h" #include "libglnx/libglnx.h" #include "bwrap-lock.h" #include "flatpak-utils-base-private.h" #include "launcher.h" #include "utils.h" static GPtrArray *global_locks = NULL; static GArray *global_pass_fds = NULL; static gboolean opt_create = FALSE; static gboolean opt_exit_with_parent = FALSE; static gboolean opt_generate_locales = FALSE; static gboolean opt_subreaper = FALSE; static double opt_terminate_idle_timeout = 0.0; static double opt_terminate_timeout = -1.0; static gboolean opt_verbose = FALSE; static gboolean opt_version = FALSE; static gboolean opt_wait = FALSE; static gboolean opt_write = FALSE; static GPid child_pid; typedef struct { int original_stdout_fd; int *pass_fds; } ChildSetupData; static void child_setup_cb (gpointer user_data) { ChildSetupData *data = user_data; sigset_t set; const int *iter; int i; /* The adverb should wait for its child before it exits, but if it * gets terminated prematurely, we want the child to terminate too. * The child could reset this, but we assume it usually won't. * This makes it exit even if we are killed by SIGKILL, unless it * takes steps not to be. */ if (opt_exit_with_parent && prctl (PR_SET_PDEATHSIG, SIGTERM, 0, 0, 0) != 0) pv_async_signal_safe_error ("Failed to set up parent-death signal\n", LAUNCH_EX_FAILED); /* Unblock all signals */ sigemptyset (&set); if (pthread_sigmask (SIG_SETMASK, &set, NULL) == -1) pv_async_signal_safe_error ("Failed to unblock signals when starting child\n", LAUNCH_EX_FAILED); /* Reset the handlers for all signals to their defaults. */ for (i = 1; i < NSIG; i++) { if (i != SIGSTOP && i != SIGKILL) signal (i, SIG_DFL); } /* Put back the original stdout for the child process */ if (data != NULL && data->original_stdout_fd > 0 && dup2 (data->original_stdout_fd, STDOUT_FILENO) != STDOUT_FILENO) pv_async_signal_safe_error ("pressure-vessel-adverb: Unable to reinstate original stdout\n", LAUNCH_EX_FAILED); /* Make all other file descriptors close-on-exec */ flatpak_close_fds_workaround (3); /* Make the fds we pass through *not* be close-on-exec */ if (data != NULL && data->pass_fds) { for (iter = data->pass_fds; *iter >= 0; iter++) { int fd = *iter; int fd_flags; fd_flags = fcntl (fd, F_GETFD); if (fd_flags < 0) pv_async_signal_safe_error ("pressure-vessel-adverb: Invalid fd?\n", LAUNCH_EX_FAILED); if ((fd_flags & FD_CLOEXEC) != 0 && fcntl (fd, F_SETFD, fd_flags & ~FD_CLOEXEC) != 0) pv_async_signal_safe_error ("pressure-vessel-adverb: Unable to clear close-on-exec\n", LAUNCH_EX_FAILED); } } } static gboolean opt_fd_cb (const char *name, const char *value, gpointer data, GError **error) { char *endptr; gint64 i64 = g_ascii_strtoll (value, &endptr, 10); int fd; int fd_flags; g_return_val_if_fail (global_locks != NULL, FALSE); g_return_val_if_fail (error == NULL || *error == NULL, FALSE); g_return_val_if_fail (value != NULL, FALSE); if (i64 < 0 || i64 > G_MAXINT || endptr == value || *endptr != '\0') { g_set_error (error, G_OPTION_ERROR, G_OPTION_ERROR_BAD_VALUE, "Integer out of range or invalid: %s", value); return FALSE; } fd = (int) i64; fd_flags = fcntl (fd, F_GETFD); if (fd_flags < 0) return glnx_throw_errno_prefix (error, "Unable to receive --fd %d", fd); if ((fd_flags & FD_CLOEXEC) == 0 && fcntl (fd, F_SETFD, fd_flags | FD_CLOEXEC) != 0) return glnx_throw_errno_prefix (error, "Unable to configure --fd %d for " "close-on-exec", fd); /* We don't know whether this is an OFD lock or not. Assume it is: * it won't change our behaviour either way, and if it was passed * to us across a fork(), it had better be an OFD. */ g_ptr_array_add (global_locks, pv_bwrap_lock_new_take (fd, TRUE)); return TRUE; } static gboolean opt_pass_fd_cb (const char *name, const char *value, gpointer data, GError **error) { char *endptr; gint64 i64 = g_ascii_strtoll (value, &endptr, 10); int fd; int fd_flags; g_return_val_if_fail (error == NULL || *error == NULL, FALSE); g_return_val_if_fail (value != NULL, FALSE); if (i64 < 0 || i64 > G_MAXINT || endptr == value || *endptr != '\0') { g_set_error (error, G_OPTION_ERROR, G_OPTION_ERROR_BAD_VALUE, "Integer out of range or invalid: %s", value); return FALSE; } fd = (int) i64; fd_flags = fcntl (fd, F_GETFD); if (fd_flags < 0) return glnx_throw_errno_prefix (error, "Unable to receive --fd %d", fd); if (global_pass_fds == NULL) global_pass_fds = g_array_new (FALSE, FALSE, sizeof (int)); g_array_append_val (global_pass_fds, fd); return TRUE; } static gboolean opt_lock_file_cb (const char *name, const char *value, gpointer data, GError **error) { PvBwrapLock *lock; PvBwrapLockFlags flags = PV_BWRAP_LOCK_FLAGS_NONE; g_return_val_if_fail (global_locks != NULL, FALSE); g_return_val_if_fail (error == NULL || *error == NULL, FALSE); g_return_val_if_fail (value != NULL, FALSE); if (opt_create) flags |= PV_BWRAP_LOCK_FLAGS_CREATE; if (opt_write) flags |= PV_BWRAP_LOCK_FLAGS_WRITE; if (opt_wait) flags |= PV_BWRAP_LOCK_FLAGS_WAIT; lock = pv_bwrap_lock_new (AT_FDCWD, value, flags, error); if (lock == NULL) return FALSE; g_ptr_array_add (global_locks, lock); return TRUE; } static gboolean generate_locales (gchar **locpath_out, GError **error) { g_autofree gchar *temp_dir = NULL; g_autoptr(GDir) dir = NULL; int wait_status; g_autofree gchar *child_stdout = NULL; g_autofree gchar *child_stderr = NULL; g_autofree gchar *pvlg = NULL; g_autofree gchar *this_path = NULL; g_autofree gchar *this_dir = NULL; gboolean ret; sigset_t mask; sigset_t old_mask; g_return_val_if_fail (locpath_out == NULL || *locpath_out == NULL, FALSE); g_return_val_if_fail (error == NULL || *error == NULL, FALSE); sigemptyset (&mask); sigemptyset (&old_mask); sigaddset (&mask, SIGCHLD); temp_dir = g_dir_make_tmp ("pressure-vessel-locales-XXXXXX", error); if (temp_dir == NULL) { if (error != NULL) glnx_prefix_error (error, "Cannot create temporary directory for locales"); return FALSE; } this_path = g_file_read_link ("/proc/self/exe", NULL); this_dir = g_path_get_dirname (this_path); pvlg = g_build_filename (this_dir, "pressure-vessel-locale-gen", NULL); const char *locale_gen_argv[] = { pvlg, "--output-dir", temp_dir, "--verbose", NULL }; /* Unblock SIGCHLD in case g_spawn_sync() needs it in some version */ if (pthread_sigmask (SIG_UNBLOCK, &mask, &old_mask) != 0) return glnx_throw_errno_prefix (error, "pthread_sigmask"); /* We use LEAVE_DESCRIPTORS_OPEN to work around a deadlock in older GLib, * see flatpak_close_fds_workaround */ ret = g_spawn_sync (NULL, /* cwd */ (gchar **) locale_gen_argv, NULL, /* environ */ G_SPAWN_LEAVE_DESCRIPTORS_OPEN, child_setup_cb, NULL, &child_stdout, &child_stderr, &wait_status, error); if (pthread_sigmask (SIG_SETMASK, &old_mask, NULL) != 0) return glnx_throw_errno_prefix (error, "pthread_sigmask"); if (!ret) { if (error != NULL) glnx_prefix_error (error, "Cannot run pressure-vessel-locale-gen"); return FALSE; } if (child_stdout != NULL && child_stdout[0] != '\0') g_debug ("Output:\n%s", child_stdout); if (child_stderr != NULL && child_stderr[0] != '\0') g_debug ("Diagnostic output:\n%s", child_stderr); if (WIFEXITED (wait_status) && WEXITSTATUS (wait_status) == EX_OSFILE) { /* locale-gen exits 72 (EX_OSFILE) if it had to correct for * missing locales at OS level. This is not an error. */ g_debug ("pressure-vessel-locale-gen created missing locales"); } else if (!g_spawn_check_exit_status (wait_status, error)) { if (error != NULL) glnx_prefix_error (error, "Unable to generate locales"); return FALSE; } /* else all locales were already present (exit status 0) */ dir = g_dir_open (temp_dir, 0, error); if (dir == NULL || g_dir_read_name (dir) == NULL) { g_debug ("No locales have been generated"); return TRUE; } if (locpath_out != NULL) *locpath_out = g_steal_pointer (&temp_dir); return TRUE; } /* Only do async-signal-safe things here: see signal-safety(7) */ static void terminate_child_cb (int signum) { if (child_pid != 0) { /* pass it on to the child we're going to wait for */ kill (child_pid, signum); } else { /* guess I'll just die, then */ signal (signum, SIG_DFL); raise (signum); } } static GOptionEntry options[] = { { "fd", '\0', G_OPTION_FLAG_NONE, G_OPTION_ARG_CALLBACK, opt_fd_cb, "Take a file descriptor, already locked if desired, and keep it " "open. May be repeated.", NULL }, { "create", '\0', G_OPTION_FLAG_NONE, G_OPTION_ARG_NONE, &opt_create, "Create each subsequent lock file if it doesn't exist.", NULL }, { "no-create", '\0', G_OPTION_FLAG_REVERSE, G_OPTION_ARG_NONE, &opt_create, "Don't create subsequent nonexistent lock files [default].", NULL }, { "exit-with-parent", '\0', G_OPTION_FLAG_NONE, G_OPTION_ARG_NONE, &opt_exit_with_parent, "Terminate child process and self with SIGTERM when parent process " "exits.", NULL }, { "no-exit-with-parent", '\0', G_OPTION_FLAG_REVERSE, G_OPTION_ARG_NONE, &opt_exit_with_parent, "Don't do anything special when parent process exits [default].", NULL }, { "generate-locales", '\0', G_OPTION_FLAG_NONE, G_OPTION_ARG_NONE, &opt_generate_locales, "Attempt to generate any missing locales.", NULL }, { "no-generate-locales", '\0', G_OPTION_FLAG_REVERSE, G_OPTION_ARG_NONE, &opt_generate_locales, "Don't generate any missing locales [default].", NULL }, { "write", '\0', G_OPTION_FLAG_NONE, G_OPTION_ARG_NONE, &opt_write, "Lock each subsequent lock file for write access.", NULL }, { "no-write", '\0', G_OPTION_FLAG_REVERSE, G_OPTION_ARG_NONE, &opt_write, "Lock each subsequent lock file for read-only access [default].", NULL }, { "wait", '\0', G_OPTION_FLAG_NONE, G_OPTION_ARG_NONE, &opt_wait, "Wait for each subsequent lock file.", NULL }, { "no-wait", '\0', G_OPTION_FLAG_REVERSE, G_OPTION_ARG_NONE, &opt_wait, "Exit unsuccessfully if a lock-file is busy [default].", NULL }, { "lock-file", '\0', G_OPTION_FLAG_NONE, G_OPTION_ARG_CALLBACK, opt_lock_file_cb, "Open the given file and lock it, affected by options appearing " "earlier on the command-line. May be repeated.", NULL }, { "pass-fd", '\0', G_OPTION_FLAG_NONE, G_OPTION_ARG_CALLBACK, opt_pass_fd_cb, "Let the launched process inherit the given fd.", NULL }, { "subreaper", '\0', G_OPTION_FLAG_NONE, G_OPTION_ARG_NONE, &opt_subreaper, "Do not exit until all descendant processes have exited.", NULL }, { "no-subreaper", '\0', G_OPTION_FLAG_REVERSE, G_OPTION_ARG_NONE, &opt_subreaper, "Only wait for a direct child process [default].", NULL }, { "terminate-idle-timeout", '\0', G_OPTION_FLAG_NONE, G_OPTION_ARG_DOUBLE, &opt_terminate_idle_timeout, "If --terminate-timeout is used, wait this many seconds before " "sending SIGTERM. [default: 0.0]", "SECONDS" }, { "terminate-timeout", '\0', G_OPTION_FLAG_NONE, G_OPTION_ARG_DOUBLE, &opt_terminate_timeout, "Send SIGTERM and SIGCONT to descendant processes that didn't " "exit within --terminate-idle-timeout. If they don't all exit within " "this many seconds, send SIGKILL and SIGCONT to survivors. If 0.0, " "skip SIGTERM and use SIGKILL immediately. Implies --subreaper. " "[Default: -1.0, meaning don't signal].", "SECONDS" }, { "verbose", '\0', G_OPTION_FLAG_NONE, G_OPTION_ARG_NONE, &opt_verbose, "Be more verbose.", NULL }, { "version", '\0', G_OPTION_FLAG_NONE, G_OPTION_ARG_NONE, &opt_version, "Print version number and exit.", NULL }, { NULL } }; static int my_pid = -1; static void cli_log_func (const gchar *log_domain, GLogLevelFlags log_level, const gchar *message, gpointer user_data) { g_printerr ("%s[%d]: %s\n", (const char *) user_data, my_pid, message); } int main (int argc, char *argv[]) { g_autoptr(GPtrArray) locks = NULL; g_autoptr(GOptionContext) context = NULL; g_autoptr(GError) local_error = NULL; GError **error = &local_error; int ret = EX_USAGE; char **command_and_args; int wait_status = -1; g_autofree gchar *locales_temp_dir = NULL; g_auto(GStrv) my_environ = NULL; g_autoptr(FILE) original_stdout = NULL; ChildSetupData child_setup_data = { -1, NULL }; sigset_t mask; struct sigaction terminate_child_action = {}; my_pid = getpid (); sigemptyset (&mask); sigaddset (&mask, SIGCHLD); /* Must be called before we start any threads */ if (pthread_sigmask (SIG_BLOCK, &mask, NULL) != 0) { ret = EX_UNAVAILABLE; glnx_throw_errno_prefix (error, "pthread_sigmask"); goto out; } setlocale (LC_ALL, ""); locks = g_ptr_array_new_with_free_func ((GDestroyNotify) pv_bwrap_lock_free); global_locks = locks; g_set_prgname ("pressure-vessel-adverb"); g_log_set_handler (G_LOG_DOMAIN, G_LOG_LEVEL_WARNING | G_LOG_LEVEL_MESSAGE, cli_log_func, (void *) g_get_prgname ()); context = g_option_context_new ( "COMMAND [ARG...]\n" "Run COMMAND [ARG...] with a lock held, a subreaper, or similar.\n"); g_option_context_add_main_entries (context, options, NULL); opt_verbose = pv_boolean_environment ("PRESSURE_VESSEL_VERBOSE", FALSE); if (!g_option_context_parse (context, &argc, &argv, error)) { if (g_error_matches (local_error, G_IO_ERROR, G_IO_ERROR_BUSY)) ret = EX_TEMPFAIL; else if (local_error->domain == G_OPTION_ERROR) ret = EX_USAGE; else ret = EX_UNAVAILABLE; goto out; } if (opt_version) { g_print ("%s:\n" " Package: pressure-vessel\n" " Version: %s\n", argv[0], VERSION); ret = 0; goto out; } if (opt_verbose) g_log_set_handler (G_LOG_DOMAIN, G_LOG_LEVEL_DEBUG | G_LOG_LEVEL_INFO, cli_log_func, (void *) g_get_prgname ()); original_stdout = pv_divert_stdout_to_stderr (error); if (original_stdout == NULL) { ret = 1; goto out; } pv_avoid_gvfs (); if (argc >= 2 && strcmp (argv[1], "--") == 0) { argv++; argc--; } if (argc < 2) { g_printerr ("%s: Usage: %s [OPTIONS] COMMAND [ARG...]\n", g_get_prgname (), g_get_prgname ()); goto out; } ret = EX_UNAVAILABLE; command_and_args = argv + 1; if (opt_exit_with_parent) { g_debug ("Setting up to exit when parent does"); if (prctl (PR_SET_PDEATHSIG, SIGTERM, 0, 0, 0) != 0) { glnx_throw_errno_prefix (error, "Unable to set parent death signal"); goto out; } } if ((opt_subreaper || opt_terminate_timeout >= 0) && prctl (PR_SET_CHILD_SUBREAPER, 1, 0, 0, 0) != 0) { glnx_throw_errno_prefix (error, "Unable to manage background processes"); goto out; } my_environ = g_get_environ (); if (opt_generate_locales) { g_debug ("Making sure locales are available"); /* If this fails, it is not fatal - carry on anyway */ if (!generate_locales (&locales_temp_dir, error)) { g_warning ("%s", local_error->message); g_clear_error (error); } else if (locales_temp_dir != NULL) { g_debug ("Generated locales in %s", locales_temp_dir); my_environ = g_environ_setenv (my_environ, "LOCPATH", locales_temp_dir, TRUE); } else { g_debug ("No locales were missing"); } } /* Respond to common termination signals by killing the child instead of * ourselves */ terminate_child_action.sa_handler = terminate_child_cb; sigaction (SIGHUP, &terminate_child_action, NULL); sigaction (SIGINT, &terminate_child_action, NULL); sigaction (SIGQUIT, &terminate_child_action, NULL); sigaction (SIGTERM, &terminate_child_action, NULL); sigaction (SIGUSR1, &terminate_child_action, NULL); sigaction (SIGUSR2, &terminate_child_action, NULL); g_debug ("Launching child process..."); fflush (stdout); child_setup_data.original_stdout_fd = fileno (original_stdout); if (global_pass_fds != NULL) { int terminator = -1; g_array_append_val (global_pass_fds, terminator); child_setup_data.pass_fds = (int *) g_array_free (g_steal_pointer (&global_pass_fds), FALSE); } /* We use LEAVE_DESCRIPTORS_OPEN to work around a deadlock in older GLib, * see flatpak_close_fds_workaround */ if (!g_spawn_async (NULL, /* working directory */ command_and_args, my_environ, (G_SPAWN_SEARCH_PATH | G_SPAWN_DO_NOT_REAP_CHILD | G_SPAWN_LEAVE_DESCRIPTORS_OPEN | G_SPAWN_CHILD_INHERITS_STDIN), child_setup_cb, &child_setup_data, &child_pid, &local_error)) { ret = 127; goto out; } g_free (child_setup_data.pass_fds); /* If the child writes to stdout and closes it, don't interfere */ g_clear_pointer (&original_stdout, fclose); /* Reap child processes until child_pid exits */ if (!pv_wait_for_child_processes (child_pid, &wait_status, error)) goto out; child_pid = 0; if (WIFEXITED (wait_status)) { ret = WEXITSTATUS (wait_status); g_debug ("Command exited with status %d", ret); } else if (WIFSIGNALED (wait_status)) { ret = 128 + WTERMSIG (wait_status); g_debug ("Command killed by signal %d", ret - 128); } else { ret = EX_SOFTWARE; g_debug ("Command terminated in an unknown way (wait status %d)", wait_status); } if (opt_terminate_idle_timeout < 0.0) opt_terminate_idle_timeout = 0.0; /* Wait for the other child processes, if any, possibly killing them */ if (opt_terminate_timeout >= 0.0) { if (!pv_terminate_all_child_processes (opt_terminate_idle_timeout * G_TIME_SPAN_SECOND, opt_terminate_timeout * G_TIME_SPAN_SECOND, error)) goto out; } else { if (!pv_wait_for_child_processes (0, NULL, error)) goto out; } out: global_locks = NULL; g_clear_pointer (&global_pass_fds, g_array_unref); if (locales_temp_dir != NULL) pv_rm_rf (locales_temp_dir); if (local_error != NULL) g_warning ("%s", local_error->message); g_debug ("Exiting with status %d", ret); return ret; }