diff options
Diffstat (limited to 'src/tty-ask-password-agent')
| -rw-r--r-- | src/tty-ask-password-agent/meson.build | 9 | ||||
| -rw-r--r-- | src/tty-ask-password-agent/tty-ask-password-agent.c | 710 |
2 files changed, 719 insertions, 0 deletions
diff --git a/src/tty-ask-password-agent/meson.build b/src/tty-ask-password-agent/meson.build new file mode 100644 index 0000000..ad0c73b --- /dev/null +++ b/src/tty-ask-password-agent/meson.build @@ -0,0 +1,9 @@ +# SPDX-License-Identifier: LGPL-2.1-or-later + +executables += [ + executable_template + { + 'name' : 'systemd-tty-ask-password-agent', + 'public' : true, + 'sources' : files('tty-ask-password-agent.c'), + }, +] diff --git a/src/tty-ask-password-agent/tty-ask-password-agent.c b/src/tty-ask-password-agent/tty-ask-password-agent.c new file mode 100644 index 0000000..3a30bfe --- /dev/null +++ b/src/tty-ask-password-agent/tty-ask-password-agent.c @@ -0,0 +1,710 @@ +/* SPDX-License-Identifier: LGPL-2.1-or-later */ +/*** + Copyright © 2015 Werner Fink +***/ + +#include <errno.h> +#include <fcntl.h> +#include <getopt.h> +#include <stdbool.h> +#include <stddef.h> +#include <sys/prctl.h> +#include <sys/signalfd.h> +#include <sys/stat.h> +#include <sys/types.h> +#include <sys/un.h> +#include <sys/wait.h> +#include <unistd.h> + +#include "alloc-util.h" +#include "ask-password-api.h" +#include "build.h" +#include "conf-parser.h" +#include "constants.h" +#include "dirent-util.h" +#include "exit-status.h" +#include "fd-util.h" +#include "fileio.h" +#include "hashmap.h" +#include "inotify-util.h" +#include "io-util.h" +#include "macro.h" +#include "main-func.h" +#include "memory-util.h" +#include "mkdir-label.h" +#include "path-util.h" +#include "pretty-print.h" +#include "process-util.h" +#include "set.h" +#include "signal-util.h" +#include "socket-util.h" +#include "string-util.h" +#include "strv.h" +#include "terminal-util.h" +#include "wall.h" + +static enum { + ACTION_LIST, + ACTION_QUERY, + ACTION_WATCH, + ACTION_WALL, +} arg_action = ACTION_QUERY; + +static bool arg_plymouth = false; +static bool arg_console = false; +static const char *arg_device = NULL; + +static int send_passwords(const char *socket_name, char **passwords) { + _cleanup_(erase_and_freep) char *packet = NULL; + _cleanup_close_ int socket_fd = -EBADF; + union sockaddr_union sa; + socklen_t sa_len; + size_t packet_length = 1; + char *d; + ssize_t n; + int r; + + assert(socket_name); + + r = sockaddr_un_set_path(&sa.un, socket_name); + if (r < 0) + return r; + sa_len = r; + + STRV_FOREACH(p, passwords) + packet_length += strlen(*p) + 1; + + packet = new(char, packet_length); + if (!packet) + return -ENOMEM; + + packet[0] = '+'; + + d = packet + 1; + STRV_FOREACH(p, passwords) + d = stpcpy(d, *p) + 1; + + socket_fd = socket(AF_UNIX, SOCK_DGRAM|SOCK_CLOEXEC, 0); + if (socket_fd < 0) + return log_debug_errno(errno, "socket(): %m"); + + n = sendto(socket_fd, packet, packet_length, MSG_NOSIGNAL, &sa.sa, sa_len); + if (n < 0) + return log_debug_errno(errno, "sendto(): %m"); + + return (int) n; +} + +static bool wall_tty_match(const char *path, bool is_local, void *userdata) { + _cleanup_free_ char *p = NULL; + _cleanup_close_ int fd = -EBADF; + struct stat st; + + assert(path_is_absolute(path)); + + if (lstat(path, &st) < 0) { + log_debug_errno(errno, "Failed to stat %s: %m", path); + return true; + } + + if (!S_ISCHR(st.st_mode)) { + log_debug("%s is not a character device.", path); + return true; + } + + /* We use named pipes to ensure that wall messages suggesting + * password entry are not printed over password prompts + * already shown. We use the fact here that opening a pipe in + * non-blocking mode for write-only will succeed only if + * there's some writer behind it. Using pipes has the + * advantage that the block will automatically go away if the + * process dies. */ + + if (asprintf(&p, "/run/systemd/ask-password-block/%u:%u", major(st.st_rdev), minor(st.st_rdev)) < 0) { + log_oom(); + return true; + } + + fd = open(p, O_WRONLY|O_CLOEXEC|O_NONBLOCK|O_NOCTTY); + if (fd < 0) { + log_debug_errno(errno, "Failed to open the wall pipe: %m"); + return 1; + } + + /* What, we managed to open the pipe? Then this tty is filtered. */ + return 0; +} + +static int agent_ask_password_tty( + const char *message, + usec_t until, + AskPasswordFlags flags, + const char *flag_file, + char ***ret) { + + int tty_fd = -EBADF, r; + const char *con = arg_device ?: "/dev/console"; + + if (arg_console) { + tty_fd = acquire_terminal(con, ACQUIRE_TERMINAL_WAIT, USEC_INFINITY); + if (tty_fd < 0) + return log_error_errno(tty_fd, "Failed to acquire %s: %m", con); + + r = reset_terminal_fd(tty_fd, true); + if (r < 0) + log_warning_errno(r, "Failed to reset terminal, ignoring: %m"); + + log_info("Starting password query on %s.", con); + } + + r = ask_password_tty(tty_fd, message, NULL, until, flags, flag_file, ret); + + if (arg_console) { + tty_fd = safe_close(tty_fd); + release_terminal(); + + if (r >= 0) + log_info("Password query on %s finished successfully.", con); + } + + return r; +} + +static int process_one_password_file(const char *filename) { + _cleanup_free_ char *socket_name = NULL, *message = NULL; + bool accept_cached = false, echo = false, silent = false; + uint64_t not_after = 0; + pid_t pid = 0; + + const ConfigTableItem items[] = { + { "Ask", "Socket", config_parse_string, CONFIG_PARSE_STRING_SAFE, &socket_name }, + { "Ask", "NotAfter", config_parse_uint64, 0, ¬_after }, + { "Ask", "Message", config_parse_string, 0, &message }, + { "Ask", "PID", config_parse_pid, 0, &pid }, + { "Ask", "AcceptCached", config_parse_bool, 0, &accept_cached }, + { "Ask", "Echo", config_parse_bool, 0, &echo }, + { "Ask", "Silent", config_parse_bool, 0, &silent }, + {} + }; + + int r; + + assert(filename); + + r = config_parse(NULL, filename, NULL, + NULL, + config_item_table_lookup, items, + CONFIG_PARSE_RELAXED|CONFIG_PARSE_WARN, + NULL, + NULL); + if (r < 0) + return r; + + if (!socket_name) + return log_error_errno(SYNTHETIC_ERRNO(EBADMSG), + "Invalid password file %s", filename); + + if (not_after > 0 && now(CLOCK_MONOTONIC) > not_after) + return 0; + + if (pid > 0 && pid_is_alive(pid) <= 0) + return 0; + + switch (arg_action) { + case ACTION_LIST: + printf("'%s' (PID " PID_FMT ")\n", strna(message), pid); + return 0; + + case ACTION_WALL: { + _cleanup_free_ char *msg = NULL; + + if (asprintf(&msg, + "Password entry required for \'%s\' (PID " PID_FMT ").\r\n" + "Please enter password with the systemd-tty-ask-password-agent tool.", + strna(message), + pid) < 0) + return log_oom(); + + (void) wall(msg, NULL, NULL, wall_tty_match, NULL); + return 0; + } + case ACTION_QUERY: + case ACTION_WATCH: { + _cleanup_strv_free_erase_ char **passwords = NULL; + AskPasswordFlags flags = 0; + + if (access(socket_name, W_OK) < 0) { + if (arg_action == ACTION_QUERY) + log_info("Not querying '%s' (PID " PID_FMT "), lacking privileges.", strna(message), pid); + + return 0; + } + + SET_FLAG(flags, ASK_PASSWORD_ACCEPT_CACHED, accept_cached); + SET_FLAG(flags, ASK_PASSWORD_CONSOLE_COLOR, arg_console); + SET_FLAG(flags, ASK_PASSWORD_ECHO, echo); + SET_FLAG(flags, ASK_PASSWORD_SILENT, silent); + + if (arg_plymouth) + r = ask_password_plymouth(message, not_after, flags, filename, &passwords); + else + r = agent_ask_password_tty(message, not_after, flags, filename, &passwords); + if (r < 0) { + /* If the query went away, that's OK */ + if (IN_SET(r, -ETIME, -ENOENT)) + return 0; + + return log_error_errno(r, "Failed to query password: %m"); + } + + if (strv_isempty(passwords)) + return -ECANCELED; + + r = send_passwords(socket_name, passwords); + if (r < 0) + return log_error_errno(r, "Failed to send: %m"); + break; + }} + + return 0; +} + +static int wall_tty_block(void) { + _cleanup_free_ char *p = NULL; + dev_t devnr; + int fd, r; + + r = get_ctty_devnr(0, &devnr); + if (r == -ENXIO) /* We have no controlling tty */ + return -ENOTTY; + if (r < 0) + return log_error_errno(r, "Failed to get controlling TTY: %m"); + + if (asprintf(&p, "/run/systemd/ask-password-block/%u:%u", major(devnr), minor(devnr)) < 0) + return log_oom(); + + (void) mkdir_parents_label(p, 0700); + (void) mkfifo(p, 0600); + + fd = open(p, O_RDONLY|O_CLOEXEC|O_NONBLOCK|O_NOCTTY); + if (fd < 0) + return log_debug_errno(errno, "Failed to open %s: %m", p); + + return fd; +} + +static int process_password_files(void) { + _cleanup_closedir_ DIR *d = NULL; + int r = 0; + + d = opendir("/run/systemd/ask-password"); + if (!d) { + if (errno == ENOENT) + return 0; + + return log_error_errno(errno, "Failed to open /run/systemd/ask-password: %m"); + } + + FOREACH_DIRENT(de, d, return log_error_errno(errno, "Failed to read directory: %m")) { + _cleanup_free_ char *p = NULL; + int q; + + /* We only support /run on tmpfs, hence we can rely on + * d_type to be reliable */ + + if (de->d_type != DT_REG) + continue; + + if (!startswith(de->d_name, "ask.")) + continue; + + p = path_join("/run/systemd/ask-password", de->d_name); + if (!p) + return log_oom(); + + q = process_one_password_file(p); + if (q < 0 && r == 0) + r = q; + } + + return r; +} + +static int process_and_watch_password_files(bool watch) { + enum { + FD_SIGNAL, + FD_INOTIFY, + _FD_MAX + }; + + _unused_ _cleanup_close_ int tty_block_fd = -EBADF; + _cleanup_close_ int notify = -EBADF, signal_fd = -EBADF; + struct pollfd pollfd[_FD_MAX]; + sigset_t mask; + int r; + + tty_block_fd = wall_tty_block(); + + (void) mkdir_p_label("/run/systemd/ask-password", 0755); + + assert_se(sigemptyset(&mask) >= 0); + assert_se(sigset_add_many(&mask, SIGTERM, -1) >= 0); + assert_se(sigprocmask(SIG_SETMASK, &mask, NULL) >= 0); + + if (watch) { + signal_fd = signalfd(-1, &mask, SFD_NONBLOCK|SFD_CLOEXEC); + if (signal_fd < 0) + return log_error_errno(errno, "Failed to allocate signal file descriptor: %m"); + + pollfd[FD_SIGNAL] = (struct pollfd) { .fd = signal_fd, .events = POLLIN }; + + notify = inotify_init1(IN_CLOEXEC); + if (notify < 0) + return log_error_errno(errno, "Failed to allocate directory watch: %m"); + + r = inotify_add_watch_and_warn(notify, "/run/systemd/ask-password", IN_CLOSE_WRITE|IN_MOVED_TO); + if (r < 0) + return r; + + pollfd[FD_INOTIFY] = (struct pollfd) { .fd = notify, .events = POLLIN }; + } + + for (;;) { + usec_t timeout = USEC_INFINITY; + + r = process_password_files(); + if (r < 0) { + if (r == -ECANCELED) + /* Disable poll() timeout since at least one password has + * been skipped and therefore one file remains and is + * unlikely to trigger any events. */ + timeout = 0; + else + /* FIXME: we should do something here since otherwise the service + * requesting the password won't notice the error and will wait + * indefinitely. */ + log_error_errno(r, "Failed to process password: %m"); + } + + if (!watch) + break; + + r = ppoll_usec(pollfd, _FD_MAX, timeout); + if (r == -EINTR) + continue; + if (r < 0) + return r; + + if (pollfd[FD_INOTIFY].revents != 0) + (void) flush_fd(notify); + + if (pollfd[FD_SIGNAL].revents != 0) + break; + } + + return 0; +} + +static int help(void) { + _cleanup_free_ char *link = NULL; + int r; + + r = terminal_urlify_man("systemd-tty-ask-password-agent", "1", &link); + if (r < 0) + return log_oom(); + + printf("%s [OPTIONS...]\n\n" + "%sProcess system password requests.%s\n\n" + " -h --help Show this help\n" + " --version Show package version\n" + " --list Show pending password requests\n" + " --query Process pending password requests\n" + " --watch Continuously process password requests\n" + " --wall Continuously forward password requests to wall\n" + " --plymouth Ask question with Plymouth instead of on TTY\n" + " --console[=DEVICE] Ask question on /dev/console (or DEVICE if specified)\n" + " instead of the current TTY\n" + "\nSee the %s for details.\n", + program_invocation_short_name, + ansi_highlight(), + ansi_normal(), + link); + + return 0; +} + +static int parse_argv(int argc, char *argv[]) { + + enum { + ARG_LIST = 0x100, + ARG_QUERY, + ARG_WATCH, + ARG_WALL, + ARG_PLYMOUTH, + ARG_CONSOLE, + ARG_VERSION + }; + + static const struct option options[] = { + { "help", no_argument, NULL, 'h' }, + { "version", no_argument, NULL, ARG_VERSION }, + { "list", no_argument, NULL, ARG_LIST }, + { "query", no_argument, NULL, ARG_QUERY }, + { "watch", no_argument, NULL, ARG_WATCH }, + { "wall", no_argument, NULL, ARG_WALL }, + { "plymouth", no_argument, NULL, ARG_PLYMOUTH }, + { "console", optional_argument, NULL, ARG_CONSOLE }, + {} + }; + + int c; + + assert(argc >= 0); + assert(argv); + + while ((c = getopt_long(argc, argv, "h", options, NULL)) >= 0) + + switch (c) { + + case 'h': + return help(); + + case ARG_VERSION: + return version(); + + case ARG_LIST: + arg_action = ACTION_LIST; + break; + + case ARG_QUERY: + arg_action = ACTION_QUERY; + break; + + case ARG_WATCH: + arg_action = ACTION_WATCH; + break; + + case ARG_WALL: + arg_action = ACTION_WALL; + break; + + case ARG_PLYMOUTH: + arg_plymouth = true; + break; + + case ARG_CONSOLE: + arg_console = true; + if (optarg) { + + if (isempty(optarg)) + return log_error_errno(SYNTHETIC_ERRNO(EINVAL), + "Empty console device path is not allowed."); + + arg_device = optarg; + } + break; + + case '?': + return -EINVAL; + + default: + assert_not_reached(); + } + + if (optind != argc) + return log_error_errno(SYNTHETIC_ERRNO(EINVAL), + "%s takes no arguments.", program_invocation_short_name); + + if (arg_plymouth || arg_console) { + + if (!IN_SET(arg_action, ACTION_QUERY, ACTION_WATCH)) + return log_error_errno(SYNTHETIC_ERRNO(EINVAL), + "Options --query and --watch conflict."); + + if (arg_plymouth && arg_console) + return log_error_errno(SYNTHETIC_ERRNO(EINVAL), + "Options --plymouth and --console conflict."); + } + + return 1; +} + +/* + * To be able to ask on all terminal devices of /dev/console the devices are collected. If more than one + * device is found, then on each of the terminals an inquiring task is forked. Every task has its own session + * and its own controlling terminal. If one of the tasks does handle a password, the remaining tasks will be + * terminated. + */ +static int ask_on_this_console(const char *tty, pid_t *ret_pid, char **arguments) { + static const struct sigaction sigchld = { + .sa_handler = nop_signal_handler, + .sa_flags = SA_NOCLDSTOP | SA_RESTART, + }; + static const struct sigaction sighup = { + .sa_handler = SIG_DFL, + .sa_flags = SA_RESTART, + }; + int r; + + assert_se(sigaction(SIGCHLD, &sigchld, NULL) >= 0); + assert_se(sigaction(SIGHUP, &sighup, NULL) >= 0); + assert_se(sigprocmask_many(SIG_UNBLOCK, NULL, SIGHUP, SIGCHLD, -1) >= 0); + + r = safe_fork("(sd-passwd)", FORK_RESET_SIGNALS|FORK_LOG, ret_pid); + if (r < 0) + return r; + if (r == 0) { + assert_se(prctl(PR_SET_PDEATHSIG, SIGHUP) >= 0); + + STRV_FOREACH(i, arguments) { + char *k; + + if (!streq(*i, "--console")) + continue; + + k = strjoin("--console=", tty); + if (!k) { + log_oom(); + _exit(EXIT_FAILURE); + } + + free_and_replace(*i, k); + } + + execv(SYSTEMD_TTY_ASK_PASSWORD_AGENT_BINARY_PATH, arguments); + _exit(EXIT_FAILURE); + } + + return 0; +} + +static void terminate_agents(Set *pids) { + sigset_t set; + void *p; + int r, signum; + + /* + * Request termination of the remaining processes as those + * are not required anymore. + */ + SET_FOREACH(p, pids) + (void) kill(PTR_TO_PID(p), SIGTERM); + + /* + * Collect the processes which have go away. + */ + assert_se(sigemptyset(&set) >= 0); + assert_se(sigaddset(&set, SIGCHLD) >= 0); + + while (!set_isempty(pids)) { + siginfo_t status = {}; + + r = waitid(P_ALL, 0, &status, WEXITED|WNOHANG); + if (r < 0 && errno == EINTR) + continue; + + if (r == 0 && status.si_pid > 0) { + set_remove(pids, PID_TO_PTR(status.si_pid)); + continue; + } + + signum = sigtimedwait(&set, NULL, TIMESPEC_STORE(50 * USEC_PER_MSEC)); + if (signum < 0) { + if (errno != EAGAIN) + log_error_errno(errno, "sigtimedwait() failed: %m"); + break; + } + assert(signum == SIGCHLD); + } + + /* + * Kill hanging processes. + */ + SET_FOREACH(p, pids) { + log_warning("Failed to terminate child %d, killing it", PTR_TO_PID(p)); + (void) kill(PTR_TO_PID(p), SIGKILL); + } +} + +static int ask_on_consoles(char *argv[]) { + _cleanup_set_free_ Set *pids = NULL; + _cleanup_strv_free_ char **consoles = NULL, **arguments = NULL; + siginfo_t status = {}; + pid_t pid; + int r; + + r = get_kernel_consoles(&consoles); + if (r < 0) + return log_error_errno(r, "Failed to determine devices of /dev/console: %m"); + + pids = set_new(NULL); + if (!pids) + return log_oom(); + + arguments = strv_copy(argv); + if (!arguments) + return log_oom(); + + /* Start an agent on each console. */ + STRV_FOREACH(tty, consoles) { + r = ask_on_this_console(*tty, &pid, arguments); + if (r < 0) + return r; + + if (set_put(pids, PID_TO_PTR(pid)) < 0) + return log_oom(); + } + + /* Wait for an agent to exit. */ + for (;;) { + zero(status); + + if (waitid(P_ALL, 0, &status, WEXITED) < 0) { + if (errno == EINTR) + continue; + + return log_error_errno(errno, "waitid() failed: %m"); + } + + set_remove(pids, PID_TO_PTR(status.si_pid)); + break; + } + + if (!is_clean_exit(status.si_code, status.si_status, EXIT_CLEAN_DAEMON, NULL)) + log_error("Password agent failed with: %d", status.si_status); + + terminate_agents(pids); + return 0; +} + +static int run(int argc, char *argv[]) { + int r; + + log_setup(); + + umask(0022); + + r = parse_argv(argc, argv); + if (r <= 0) + return r; + + if (arg_console && !arg_device) + /* + * Spawn a separate process for each console device. + */ + return ask_on_consoles(argv); + + if (arg_device) { + /* + * Later on, a controlling terminal will be acquired, + * therefore the current process has to become a session + * leader and should not have a controlling terminal already. + */ + (void) setsid(); + (void) release_terminal(); + } + + return process_and_watch_password_files(!IN_SET(arg_action, ACTION_QUERY, ACTION_LIST)); +} + +DEFINE_MAIN_FUNCTION(run); |