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Systemd/src/tty-ask-password-agent/tty-ask-password-agent.c

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/* SPDX-License-Identifier: LGPL-2.1+ */
/***
Copyright © 2015 Werner Fink
***/
#include <errno.h>
#include <fcntl.h>
#include <getopt.h>
#include <poll.h>
#include <signal.h>
#include <stdbool.h>
#include <stddef.h>
#include <string.h>
#include <sys/inotify.h>
#include <sys/prctl.h>
#include <sys/signalfd.h>
#include <sys/socket.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 "conf-parser.h"
#include "def.h"
#include "dirent-util.h"
#include "exit-status.h"
#include "fd-util.h"
#include "fileio.h"
#include "hashmap.h"
#include "io-util.h"
#include "macro.h"
#include "main-func.h"
#include "memory-util.h"
#include "mkdir.h"
#include "path-util.h"
#include "plymouth-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 "utmp-wtmp.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 ask_password_plymouth(
const char *message,
usec_t until,
AskPasswordFlags flags,
const char *flag_file,
char ***ret) {
static const union sockaddr_union sa = PLYMOUTH_SOCKET;
_cleanup_close_ int fd = -1, notify = -1;
_cleanup_free_ char *packet = NULL;
ssize_t k;
int r, n;
struct pollfd pollfd[2] = {};
char buffer[LINE_MAX];
size_t p = 0;
enum {
POLL_SOCKET,
POLL_INOTIFY
};
assert(ret);
if (flag_file) {
notify = inotify_init1(IN_CLOEXEC|IN_NONBLOCK);
if (notify < 0)
return -errno;
r = inotify_add_watch(notify, flag_file, IN_ATTRIB); /* for the link count */
if (r < 0)
return -errno;
}
fd = socket(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0);
if (fd < 0)
return -errno;
r = connect(fd, &sa.sa, SOCKADDR_UN_LEN(sa.un));
if (r < 0)
return -errno;
if (flags & ASK_PASSWORD_ACCEPT_CACHED) {
packet = strdup("c");
n = 1;
} else if (asprintf(&packet, "*\002%c%s%n", (int) (strlen(message) + 1), message, &n) < 0)
packet = NULL;
if (!packet)
return -ENOMEM;
r = loop_write(fd, packet, n + 1, true);
if (r < 0)
return r;
pollfd[POLL_SOCKET].fd = fd;
pollfd[POLL_SOCKET].events = POLLIN;
pollfd[POLL_INOTIFY].fd = notify;
pollfd[POLL_INOTIFY].events = POLLIN;
for (;;) {
int sleep_for = -1, j;
if (until > 0) {
usec_t y;
y = now(CLOCK_MONOTONIC);
if (y > until) {
r = -ETIME;
goto finish;
}
sleep_for = (int) ((until - y) / USEC_PER_MSEC);
}
if (flag_file && access(flag_file, F_OK) < 0) {
r = -errno;
goto finish;
}
j = poll(pollfd, notify >= 0 ? 2 : 1, sleep_for);
if (j < 0) {
if (errno == EINTR)
continue;
r = -errno;
goto finish;
} else if (j == 0) {
r = -ETIME;
goto finish;
}
if (notify >= 0 && pollfd[POLL_INOTIFY].revents != 0)
(void) flush_fd(notify);
if (pollfd[POLL_SOCKET].revents == 0)
continue;
k = read(fd, buffer + p, sizeof(buffer) - p);
if (k < 0) {
if (IN_SET(errno, EINTR, EAGAIN))
continue;
r = -errno;
goto finish;
} else if (k == 0) {
r = -EIO;
goto finish;
}
p += k;
if (p < 1)
continue;
if (buffer[0] == 5) {
if (flags & ASK_PASSWORD_ACCEPT_CACHED) {
/* Hmm, first try with cached
* passwords failed, so let's retry
* with a normal password request */
packet = mfree(packet);
if (asprintf(&packet, "*\002%c%s%n", (int) (strlen(message) + 1), message, &n) < 0) {
r = -ENOMEM;
goto finish;
}
r = loop_write(fd, packet, n+1, true);
if (r < 0)
goto finish;
flags &= ~ASK_PASSWORD_ACCEPT_CACHED;
p = 0;
continue;
}
/* No password, because UI not shown */
r = -ENOENT;
goto finish;
} else if (IN_SET(buffer[0], 2, 9)) {
uint32_t size;
char **l;
/* One or more answers */
if (p < 5)
continue;
memcpy(&size, buffer+1, sizeof(size));
size = le32toh(size);
if (size + 5 > sizeof(buffer)) {
r = -EIO;
goto finish;
}
if (p-5 < size)
continue;
l = strv_parse_nulstr(buffer + 5, size);
if (!l) {
r = -ENOMEM;
goto finish;
}
*ret = l;
break;
} else {
/* Unknown packet */
r = -EIO;
goto finish;
}
}
r = 0;
finish:
explicit_bzero_safe(buffer, sizeof(buffer));
return r;
}
static int send_passwords(const char *socket_name, char **passwords) {
_cleanup_(erase_and_freep) char *packet = NULL;
_cleanup_close_ int socket_fd = -1;
union sockaddr_union sa = {};
size_t packet_length = 1;
char **p, *d;
ssize_t n;
int salen;
assert(socket_name);
salen = sockaddr_un_set_path(&sa.un, socket_name);
if (salen < 0)
return salen;
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, salen);
if (n < 0)
return log_debug_errno(errno, "sendto(): %m");
return (int) n;
}
static int parse_password(const char *filename, char **wall) {
_cleanup_free_ char *socket_name = NULL, *message = NULL;
bool accept_cached = false, echo = false;
uint64_t not_after = 0;
unsigned pid = 0;
const ConfigTableItem items[] = {
{ "Ask", "Socket", config_parse_string, 0, &socket_name },
{ "Ask", "NotAfter", config_parse_uint64, 0, &not_after },
{ "Ask", "Message", config_parse_string, 0, &message },
{ "Ask", "PID", config_parse_unsigned, 0, &pid },
{ "Ask", "AcceptCached", config_parse_bool, 0, &accept_cached },
{ "Ask", "Echo", config_parse_bool, 0, &echo },
{}
};
int r;
assert(filename);
r = config_parse(NULL, filename, NULL,
NULL,
config_item_table_lookup, items,
CONFIG_PARSE_RELAXED|CONFIG_PARSE_WARN, 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))
return 0;
if (arg_action == ACTION_LIST)
printf("'%s' (PID %u)\n", message, pid);
else if (arg_action == ACTION_WALL) {
char *_wall;
if (asprintf(&_wall,
"%s%sPassword entry required for \'%s\' (PID %u).\r\n"
"Please enter password with the systemd-tty-ask-password-agent tool:",
strempty(*wall),
*wall ? "\r\n\r\n" : "",
message,
pid) < 0)
return log_oom();
free(*wall);
*wall = _wall;
} else {
_cleanup_strv_free_erase_ char **passwords = NULL;
assert(IN_SET(arg_action, ACTION_QUERY, ACTION_WATCH));
if (access(socket_name, W_OK) < 0) {
if (arg_action == ACTION_QUERY)
log_info("Not querying '%s' (PID %u), lacking privileges.", message, pid);
return 0;
}
if (arg_plymouth)
r = ask_password_plymouth(message, not_after, accept_cached ? ASK_PASSWORD_ACCEPT_CACHED : 0, filename, &passwords);
else {
int tty_fd = -1;
if (arg_console) {
const char *con = arg_device ?: "/dev/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");
}
r = ask_password_tty(tty_fd, message, NULL, not_after,
(echo ? ASK_PASSWORD_ECHO : 0) |
(arg_console ? ASK_PASSWORD_CONSOLE_COLOR : 0),
filename, &passwords);
if (arg_console) {
tty_fd = safe_close(tty_fd);
release_terminal();
}
}
/* If the query went away, that's OK */
if (IN_SET(r, -ETIME, -ENOENT))
return 0;
if (r < 0)
return log_error_errno(r, "Failed to query password: %m");
r = send_passwords(socket_name, passwords);
if (r < 0)
return log_error_errno(r, "Failed to send: %m");
}
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 bool wall_tty_match(const char *path, void *userdata) {
_cleanup_free_ char *p = NULL;
_cleanup_close_ int fd = -1;
struct stat st;
if (!path_is_absolute(path))
path = strjoina("/dev/", 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 show_passwords(void) {
_cleanup_closedir_ DIR *d;
struct dirent *de;
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_ALL(de, d, return log_error_errno(errno, "Failed to read directory: %m")) {
_cleanup_free_ char *p = NULL, *wall = NULL;
int q;
/* We only support /dev on tmpfs, hence we can rely on
* d_type to be reliable */
if (de->d_type != DT_REG)
continue;
if (hidden_or_backup_file(de->d_name))
continue;
if (!startswith(de->d_name, "ask."))
continue;
p = path_join("/run/systemd/ask-password", de->d_name);
if (!p)
return log_oom();
q = parse_password(p, &wall);
if (q < 0 && r == 0)
r = q;
if (wall)
(void) utmp_wall(wall, NULL, NULL, wall_tty_match, NULL);
}
return r;
}
static int watch_passwords(void) {
enum {
FD_INOTIFY,
FD_SIGNAL,
_FD_MAX
};
_cleanup_close_ int notify = -1, signal_fd = -1, tty_block_fd = -1;
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);
notify = inotify_init1(IN_CLOEXEC);
if (notify < 0)
return log_error_errno(errno, "Failed to allocate directory watch: %m");
if (inotify_add_watch(notify, "/run/systemd/ask-password", IN_CLOSE_WRITE|IN_MOVED_TO) < 0) {
if (errno == ENOSPC)
return log_error_errno(errno, "Failed to add /run/systemd/ask-password to directory watch: inotify watch limit reached");
else
return log_error_errno(errno, "Failed to add /run/systemd/ask-password to directory watch: %m");
}
assert_se(sigemptyset(&mask) >= 0);
assert_se(sigset_add_many(&mask, SIGINT, SIGTERM, -1) >= 0);
assert_se(sigprocmask(SIG_SETMASK, &mask, NULL) >= 0);
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_INOTIFY].fd = notify;
pollfd[FD_INOTIFY].events = POLLIN;
pollfd[FD_SIGNAL].fd = signal_fd;
pollfd[FD_SIGNAL].events = POLLIN;
for (;;) {
r = show_passwords();
if (r < 0)
log_error_errno(r, "Failed to show password: %m");
if (poll(pollfd, _FD_MAX, -1) < 0) {
if (errno == EINTR)
continue;
return -errno;
}
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"
"Process system password requests.\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 Ask question on /dev/console instead of current TTY\n"
"\nSee the %s for details.\n"
, program_invocation_short_name
, 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("Unhandled option");
}
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 a 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) {
char **i;
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) {
struct timespec ts;
siginfo_t status = {};
sigset_t set;
Iterator i;
void *p;
int r, signum;
/*
* Request termination of the remaining processes as those
* are not required anymore.
*/
SET_FOREACH(p, pids, i)
(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);
timespec_store(&ts, 50 * USEC_PER_MSEC);
while (!set_isempty(pids)) {
zero(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, &ts);
if (signum < 0) {
if (errno != EAGAIN)
log_error_errno(errno, "sigtimedwait() failed: %m");
break;
}
assert(signum == SIGCHLD);
}
/*
* Kill hanging processes.
*/
SET_FOREACH(p, pids, i) {
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 = {};
char **tty;
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_service();
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();
}
if (IN_SET(arg_action, ACTION_WATCH, ACTION_WALL))
return watch_passwords();
else
return show_passwords();
}
DEFINE_MAIN_FUNCTION(run);
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