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

   1 /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
   2
   3 /***
   4   This file is part of systemd.
   5
   6   Copyright 2010 Lennart Poettering
   7
   8   systemd is free software; you can redistribute it and/or modify it
   9   under the terms of the GNU Lesser General Public License as published by
  10   the Free Software Foundation; either version 2.1 of the License, or
  11   (at your option) any later version.
  12
  13   systemd is distributed in the hope that it will be useful, but
  14   WITHOUT ANY WARRANTY; without even the implied warranty of
  15   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  16   Lesser General Public License for more details.
  17
  18   You should have received a copy of the GNU Lesser General Public License
  19   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  20 ***/
  21
  22 #include <stdbool.h>
  23 #include <errno.h>
  24 #include <string.h>
  25 #include <sys/socket.h>
  26 #include <sys/un.h>
  27 #include <stddef.h>
  28 #include <sys/poll.h>
  29 #include <sys/inotify.h>
  30 #include <unistd.h>
  31 #include <getopt.h>
  32 #include <sys/signalfd.h>
  33 #include <fcntl.h>
  34
  35 #include "util.h"
  36 #include "mkdir.h"
  37 #include "path-util.h"
  38 #include "conf-parser.h"
  39 #include "utmp-wtmp.h"
  40 #include "socket-util.h"
  41 #include "ask-password-api.h"
  42 #include "strv.h"
  43 #include "build.h"
  44 #include "def.h"
  45
  46 static enum {
  47         ACTION_LIST,
  48         ACTION_QUERY,
  49         ACTION_WATCH,
  50         ACTION_WALL
  51 } arg_action = ACTION_QUERY;
  52
  53 static bool arg_plymouth = false;
  54 static bool arg_console = false;
  55
  56 static int ask_password_plymouth(
  57                 const char *message,
  58                 usec_t until,
  59                 const char *flag_file,
  60                 bool accept_cached,
  61                 char ***_passphrases) {
  62
  63         _cleanup_close_ int fd = -1, notify = -1;
  64         union sockaddr_union sa = PLYMOUTH_SOCKET;
  65         _cleanup_free_ char *packet = NULL;
  66         ssize_t k;
  67         int r, n;
  68         struct pollfd pollfd[2] = {};
  69         char buffer[LINE_MAX];
  70         size_t p = 0;
  71         enum {
  72                 POLL_SOCKET,
  73                 POLL_INOTIFY
  74         };
  75
  76         assert(_passphrases);
  77
  78         if (flag_file) {
  79                 notify = inotify_init1(IN_CLOEXEC|IN_NONBLOCK);
  80                 if (notify < 0)
  81                         return -errno;
  82
  83                 r = inotify_add_watch(notify, flag_file, IN_ATTRIB); /* for the link count */
  84                 if (r < 0)
  85                         return -errno;
  86         }
  87
  88         fd = socket(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0);
  89         if (fd < 0)
  90                 return -errno;
  91
  92         r = connect(fd, &sa.sa, offsetof(struct sockaddr_un, sun_path) + 1 + strlen(sa.un.sun_path+1));
  93         if (r < 0) {
  94                 log_error("Failed to connect to Plymouth: %m");
  95                 return -errno;
  96         }
  97
  98         if (accept_cached) {
  99                 packet = strdup("c");
 100                 n = 1;
 101         } else if (asprintf(&packet, "*\002%c%s%n", (int) (strlen(message) + 1),
 102                             message, &n) < 0)
 103                 packet = NULL;
 104
 105         if (!packet)
 106                 return log_oom();
 107
 108         k = loop_write(fd, packet, n + 1, true);
 109         if (k != n + 1)
 110                 return k < 0 ? (int) k : -EIO;
 111
 112         pollfd[POLL_SOCKET].fd = fd;
 113         pollfd[POLL_SOCKET].events = POLLIN;
 114         pollfd[POLL_INOTIFY].fd = notify;
 115         pollfd[POLL_INOTIFY].events = POLLIN;
 116
 117         for (;;) {
 118                 int sleep_for = -1, j;
 119
 120                 if (until > 0) {
 121                         usec_t y;
 122
 123                         y = now(CLOCK_MONOTONIC);
 124
 125                         if (y > until)
 126                                 return -ETIME;
 127
 128                         sleep_for = (int) ((until - y) / USEC_PER_MSEC);
 129                 }
 130
 131                 if (flag_file && access(flag_file, F_OK) < 0)
 132                         return -errno;
 133
 134                 j = poll(pollfd, notify > 0 ? 2 : 1, sleep_for);
 135                 if (j < 0) {
 136                         if (errno == EINTR)
 137                                 continue;
 138
 139                         return -errno;
 140                 } else if (j == 0)
 141                         return -ETIME;
 142
 143                 if (notify > 0 && pollfd[POLL_INOTIFY].revents != 0)
 144                         flush_fd(notify);
 145
 146                 if (pollfd[POLL_SOCKET].revents == 0)
 147                         continue;
 148
 149                 k = read(fd, buffer + p, sizeof(buffer) - p);
 150                 if (k <= 0)
 151                         return r = k < 0 ? -errno : -EIO;
 152
 153                 p += k;
 154
 155                 if (p < 1)
 156                         continue;
 157
 158                 if (buffer[0] == 5) {
 159
 160                         if (accept_cached) {
 161                                 /* Hmm, first try with cached
 162                                  * passwords failed, so let's retry
 163                                  * with a normal password request */
 164                                 free(packet);
 165                                 packet = NULL;
 166
 167                                 if (asprintf(&packet, "*\002%c%s%n", (int) (strlen(message) + 1), message, &n) < 0)
 168                                         return -ENOMEM;
 169
 170                                 k = loop_write(fd, packet, n+1, true);
 171                                 if (k != n + 1)
 172                                         return k < 0 ? (int) k : -EIO;
 173
 174                                 accept_cached = false;
 175                                 p = 0;
 176                                 continue;
 177                         }
 178
 179                         /* No password, because UI not shown */
 180                         return -ENOENT;
 181
 182                 } else if (buffer[0] == 2 || buffer[0] == 9) {
 183                         uint32_t size;
 184                         char **l;
 185
 186                         /* One or more answers */
 187                         if (p < 5)
 188                                 continue;
 189
 190                         memcpy(&size, buffer+1, sizeof(size));
 191                         size = le32toh(size);
 192                         if (size + 5 > sizeof(buffer))
 193                                 return -EIO;
 194
 195                         if (p-5 < size)
 196                                 continue;
 197
 198                         l = strv_parse_nulstr(buffer + 5, size);
 199                         if (!l)
 200                                 return -ENOMEM;
 201
 202                         *_passphrases = l;
 203                         break;
 204
 205                 } else
 206                         /* Unknown packet */
 207                         return -EIO;
 208         }
 209
 210         return 0;
 211 }
 212
 213 static int parse_password(const char *filename, char **wall) {
 214         _cleanup_free_ char *socket_name = NULL, *message = NULL, *packet = NULL;
 215         uint64_t not_after = 0;
 216         unsigned pid = 0;
 217         bool accept_cached = false, echo = false;
 218
 219         const ConfigTableItem items[] = {
 220                 { "Ask", "Socket",       config_parse_string,   0, &socket_name   },
 221                 { "Ask", "NotAfter",     config_parse_uint64,   0, &not_after     },
 222                 { "Ask", "Message",      config_parse_string,   0, &message       },
 223                 { "Ask", "PID",          config_parse_unsigned, 0, &pid           },
 224                 { "Ask", "AcceptCached", config_parse_bool,     0, &accept_cached },
 225                 { "Ask", "Echo",         config_parse_bool,     0, &echo          },
 226                 {}
 227         };
 228
 229         int r;
 230
 231         assert(filename);
 232
 233         r = config_parse(NULL, filename, NULL,
 234                          NULL,
 235                          config_item_table_lookup, items,
 236                          true, false, true, NULL);
 237         if (r < 0)
 238                 return r;
 239
 240         if (!socket_name) {
 241                 log_error("Invalid password file %s", filename);
 242                 return -EBADMSG;
 243         }
 244
 245         if (not_after > 0 && now(CLOCK_MONOTONIC) > not_after)
 246                 return 0;
 247
 248         if (pid > 0 && !pid_is_alive(pid))
 249                 return 0;
 250
 251         if (arg_action == ACTION_LIST)
 252                 printf("'%s' (PID %u)\n", message, pid);
 253
 254         else if (arg_action == ACTION_WALL) {
 255                 char *_wall;
 256
 257                 if (asprintf(&_wall,
 258                              "%s%sPassword entry required for \'%s\' (PID %u).\r\n"
 259                              "Please enter password with the systemd-tty-ask-password-agent tool!",
 260                              *wall ? *wall : "",
 261                              *wall ? "\r\n\r\n" : "",
 262                              message,
 263                              pid) < 0)
 264                         return log_oom();
 265
 266                 free(*wall);
 267                 *wall = _wall;
 268
 269         } else {
 270                 union sockaddr_union sa = {};
 271                 size_t packet_length = 0;
 272                 _cleanup_close_ int socket_fd = -1;
 273
 274                 assert(arg_action == ACTION_QUERY ||
 275                        arg_action == ACTION_WATCH);
 276
 277                 if (access(socket_name, W_OK) < 0) {
 278                         if (arg_action == ACTION_QUERY)
 279                                 log_info("Not querying '%s' (PID %u), lacking privileges.", message, pid);
 280
 281                         return 0;
 282                 }
 283
 284                 if (arg_plymouth) {
 285                         _cleanup_strv_free_ char **passwords = NULL;
 286
 287                         r = ask_password_plymouth(message, not_after, filename, accept_cached, &passwords);
 288                         if (r >= 0) {
 289                                 char **p;
 290
 291                                 packet_length = 1;
 292                                 STRV_FOREACH(p, passwords)
 293                                         packet_length += strlen(*p) + 1;
 294
 295                                 packet = new(char, packet_length);
 296                                 if (!packet)
 297                                         r = -ENOMEM;
 298                                 else {
 299                                         char *d = packet + 1;
 300
 301                                         STRV_FOREACH(p, passwords)
 302                                                 d = stpcpy(d, *p) + 1;
 303
 304                                         packet[0] = '+';
 305                                 }
 306                         }
 307
 308                 } else {
 309                         int tty_fd = -1;
 310                         _cleanup_free_ char *password = NULL;
 311
 312                         if (arg_console) {
 313                                 tty_fd = acquire_terminal("/dev/console", false, false, false, USEC_INFINITY);
 314                                 if (tty_fd < 0)
 315                                         return tty_fd;
 316                         }
 317
 318                         r = ask_password_tty(message, not_after, echo, filename, &password);
 319
 320                         if (arg_console) {
 321                                 safe_close(tty_fd);
 322                                 release_terminal();
 323                         }
 324
 325                         if (r >= 0) {
 326                                 packet_length = 1 + strlen(password) + 1;
 327                                 packet = new(char, packet_length);
 328                                 if (!packet)
 329                                         r = -ENOMEM;
 330                                 else {
 331                                         packet[0] = '+';
 332                                         strcpy(packet + 1, password);
 333                                 }
 334                         }
 335                 }
 336
 337                 if (IN_SET(r, -ETIME, -ENOENT))
 338                         /* If the query went away, that's OK */
 339                         return 0;
 340
 341                 if (r < 0)
 342                         return log_error_errno(r, "Failed to query password: %m");
 343
 344                 socket_fd = socket(AF_UNIX, SOCK_DGRAM|SOCK_CLOEXEC, 0);
 345                 if (socket_fd < 0) {
 346                         log_error("socket(): %m");
 347                         return -errno;
 348                 }
 349
 350                 sa.un.sun_family = AF_UNIX;
 351                 strncpy(sa.un.sun_path, socket_name, sizeof(sa.un.sun_path));
 352
 353                 r = sendto(socket_fd, packet, packet_length, MSG_NOSIGNAL, &sa.sa,
 354                            offsetof(struct sockaddr_un, sun_path) + strlen(socket_name));
 355                 if (r < 0) {
 356                         log_error("Failed to send: %m");
 357                         return r;
 358                 }
 359         }
 360
 361         return 0;
 362 }
 363
 364 static int wall_tty_block(void) {
 365         _cleanup_free_ char *p = NULL;
 366         int fd, r;
 367         dev_t devnr;
 368
 369         r = get_ctty_devnr(0, &devnr);
 370         if (r < 0)
 371                 return r;
 372
 373         if (asprintf(&p, "/run/systemd/ask-password-block/%u:%u", major(devnr), minor(devnr)) < 0)
 374                 return -ENOMEM;
 375
 376         mkdir_parents_label(p, 0700);
 377         mkfifo(p, 0600);
 378
 379         fd = open(p, O_RDONLY|O_CLOEXEC|O_NONBLOCK|O_NOCTTY);
 380         if (fd < 0)
 381                 return -errno;
 382
 383         return fd;
 384 }
 385
 386 static bool wall_tty_match(const char *path) {
 387         int fd, r;
 388         struct stat st;
 389         _cleanup_free_ char *p = NULL;
 390
 391         if (!path_is_absolute(path))
 392                 path = strappenda("/dev/", path);
 393
 394         r = lstat(path, &st);
 395         if (r < 0)
 396                 return true;
 397
 398         if (!S_ISCHR(st.st_mode))
 399                 return true;
 400
 401         /* We use named pipes to ensure that wall messages suggesting
 402          * password entry are not printed over password prompts
 403          * already shown. We use the fact here that opening a pipe in
 404          * non-blocking mode for write-only will succeed only if
 405          * there's some writer behind it. Using pipes has the
 406          * advantage that the block will automatically go away if the
 407          * process dies. */
 408
 409         if (asprintf(&p, "/run/systemd/ask-password-block/%u:%u", major(st.st_rdev), minor(st.st_rdev)) < 0)
 410                 return true;
 411
 412         fd = open(p, O_WRONLY|O_CLOEXEC|O_NONBLOCK|O_NOCTTY);
 413         if (fd < 0)
 414                 return true;
 415
 416         /* What, we managed to open the pipe? Then this tty is filtered. */
 417         safe_close(fd);
 418         return false;
 419 }
 420
 421 static int show_passwords(void) {
 422         _cleanup_closedir_ DIR *d;
 423         struct dirent *de;
 424         int r = 0;
 425
 426         d = opendir("/run/systemd/ask-password");
 427         if (!d) {
 428                 if (errno == ENOENT)
 429                         return 0;
 430
 431                 log_error("opendir(/run/systemd/ask-password): %m");
 432                 return -errno;
 433         }
 434
 435         while ((de = readdir(d))) {
 436                 _cleanup_free_ char *p = NULL, *wall = NULL;
 437                 int q;
 438
 439                 /* We only support /dev on tmpfs, hence we can rely on
 440                  * d_type to be reliable */
 441
 442                 if (de->d_type != DT_REG)
 443                         continue;
 444
 445                 if (ignore_file(de->d_name))
 446                         continue;
 447
 448                 if (!startswith(de->d_name, "ask."))
 449                         continue;
 450
 451                 p = strappend("/run/systemd/ask-password/", de->d_name);
 452                 if (!p)
 453                         return log_oom();
 454
 455                 q = parse_password(p, &wall);
 456                 if (q < 0 && r == 0)
 457                         r = q;
 458
 459                 if (wall)
 460                         utmp_wall(wall, NULL, wall_tty_match);
 461         }
 462
 463         return r;
 464 }
 465
 466 static int watch_passwords(void) {
 467         enum {
 468                 FD_INOTIFY,
 469                 FD_SIGNAL,
 470                 _FD_MAX
 471         };
 472
 473         _cleanup_close_ int notify = -1, signal_fd = -1, tty_block_fd = -1;
 474         struct pollfd pollfd[_FD_MAX] = {};
 475         sigset_t mask;
 476         int r;
 477
 478         tty_block_fd = wall_tty_block();
 479
 480         mkdir_p_label("/run/systemd/ask-password", 0755);
 481
 482         notify = inotify_init1(IN_CLOEXEC);
 483         if (notify < 0)
 484                 return -errno;
 485
 486         if (inotify_add_watch(notify, "/run/systemd/ask-password", IN_CLOSE_WRITE|IN_MOVED_TO) < 0)
 487                 return -errno;
 488
 489         assert_se(sigemptyset(&mask) == 0);
 490         sigset_add_many(&mask, SIGINT, SIGTERM, -1);
 491         assert_se(sigprocmask(SIG_SETMASK, &mask, NULL) == 0);
 492
 493         signal_fd = signalfd(-1, &mask, SFD_NONBLOCK|SFD_CLOEXEC);
 494         if (signal_fd < 0)
 495                 return -errno;
 496
 497         pollfd[FD_INOTIFY].fd = notify;
 498         pollfd[FD_INOTIFY].events = POLLIN;
 499         pollfd[FD_SIGNAL].fd = signal_fd;
 500         pollfd[FD_SIGNAL].events = POLLIN;
 501
 502         for (;;) {
 503                 r = show_passwords();
 504                 if (r < 0)
 505                         log_error_errno(r, "Failed to show password: %m");
 506
 507                 if (poll(pollfd, _FD_MAX, -1) < 0) {
 508                         if (errno == EINTR)
 509                                 continue;
 510
 511                         return -errno;
 512                 }
 513
 514                 if (pollfd[FD_INOTIFY].revents != 0)
 515                         flush_fd(notify);
 516
 517                 if (pollfd[FD_SIGNAL].revents != 0)
 518                         break;
 519         }
 520
 521         return 0;
 522 }
 523
 524 static void help(void) {
 525         printf("%s [OPTIONS...]\n\n"
 526                "Process system password requests.\n\n"
 527                "  -h --help     Show this help\n"
 528                "     --version  Show package version\n"
 529                "     --list     Show pending password requests\n"
 530                "     --query    Process pending password requests\n"
 531                "     --watch    Continuously process password requests\n"
 532                "     --wall     Continuously forward password requests to wall\n"
 533                "     --plymouth Ask question with Plymouth instead of on TTY\n"
 534                "     --console  Ask question on /dev/console instead of current TTY\n",
 535                program_invocation_short_name);
 536 }
 537
 538 static int parse_argv(int argc, char *argv[]) {
 539
 540         enum {
 541                 ARG_LIST = 0x100,
 542                 ARG_QUERY,
 543                 ARG_WATCH,
 544                 ARG_WALL,
 545                 ARG_PLYMOUTH,
 546                 ARG_CONSOLE,
 547                 ARG_VERSION
 548         };
 549
 550         static const struct option options[] = {
 551                 { "help",     no_argument, NULL, 'h'          },
 552                 { "version",  no_argument, NULL, ARG_VERSION  },
 553                 { "list",     no_argument, NULL, ARG_LIST     },
 554                 { "query",    no_argument, NULL, ARG_QUERY    },
 555                 { "watch",    no_argument, NULL, ARG_WATCH    },
 556                 { "wall",     no_argument, NULL, ARG_WALL     },
 557                 { "plymouth", no_argument, NULL, ARG_PLYMOUTH },
 558                 { "console",  no_argument, NULL, ARG_CONSOLE  },
 559                 {}
 560         };
 561
 562         int c;
 563
 564         assert(argc >= 0);
 565         assert(argv);
 566
 567         while ((c = getopt_long(argc, argv, "h", options, NULL)) >= 0)
 568
 569                 switch (c) {
 570
 571                 case 'h':
 572                         help();
 573                         return 0;
 574
 575                 case ARG_VERSION:
 576                         puts(PACKAGE_STRING);
 577                         puts(SYSTEMD_FEATURES);
 578                         return 0;
 579
 580                 case ARG_LIST:
 581                         arg_action = ACTION_LIST;
 582                         break;
 583
 584                 case ARG_QUERY:
 585                         arg_action = ACTION_QUERY;
 586                         break;
 587
 588                 case ARG_WATCH:
 589                         arg_action = ACTION_WATCH;
 590                         break;
 591
 592                 case ARG_WALL:
 593                         arg_action = ACTION_WALL;
 594                         break;
 595
 596                 case ARG_PLYMOUTH:
 597                         arg_plymouth = true;
 598                         break;
 599
 600                 case ARG_CONSOLE:
 601                         arg_console = true;
 602                         break;
 603
 604                 case '?':
 605                         return -EINVAL;
 606
 607                 default:
 608                         assert_not_reached("Unhandled option");
 609                 }
 610
 611         if (optind != argc) {
 612                 log_error("%s takes no arguments.", program_invocation_short_name);
 613                 return -EINVAL;
 614         }
 615
 616         return 1;
 617 }
 618
 619 int main(int argc, char *argv[]) {
 620         int r;
 621
 622         log_set_target(LOG_TARGET_AUTO);
 623         log_parse_environment();
 624         log_open();
 625
 626         umask(0022);
 627
 628         r = parse_argv(argc, argv);
 629         if (r <= 0)
 630                 goto finish;
 631
 632         if (arg_console) {
 633                 setsid();
 634                 release_terminal();
 635         }
 636
 637         if (IN_SET(arg_action, ACTION_WATCH, ACTION_WALL))
 638                 r = watch_passwords();
 639         else
 640                 r = show_passwords();
 641
 642         if (r < 0)
 643                 log_error_errno(r, "Error: %m");
 644
 645 finish:
 646         return r < 0 ? EXIT_FAILURE : EXIT_SUCCESS;
 647 }