src/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 General Public License as published by
  10   the Free Software Foundation; either version 2 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   General Public License for more details.
  17
  18   You should have received a copy of the GNU 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 "conf-parser.h"
  37 #include "utmp-wtmp.h"
  38 #include "socket-util.h"
  39 #include "ask-password-api.h"
  40 #include "strv.h"
  41
  42 static enum {
  43         ACTION_LIST,
  44         ACTION_QUERY,
  45         ACTION_WATCH,
  46         ACTION_WALL
  47 } arg_action = ACTION_QUERY;
  48
  49 static bool arg_plymouth = false;
  50 static bool arg_console = false;
  51
  52 static int ask_password_plymouth(
  53                 const char *message,
  54                 usec_t until,
  55                 const char *flag_file,
  56                 bool accept_cached,
  57                 char ***_passphrases) {
  58
  59         int fd = -1, notify = -1;
  60         union sockaddr_union sa;
  61         char *packet = NULL;
  62         ssize_t k;
  63         int r, n;
  64         struct pollfd pollfd[2];
  65         char buffer[LINE_MAX];
  66         size_t p = 0;
  67         enum {
  68                 POLL_SOCKET,
  69                 POLL_INOTIFY
  70         };
  71
  72         assert(_passphrases);
  73
  74         if (flag_file) {
  75                 if ((notify = inotify_init1(IN_CLOEXEC|IN_NONBLOCK)) < 0) {
  76                         r = -errno;
  77                         goto finish;
  78                 }
  79
  80                 if (inotify_add_watch(notify, flag_file, IN_ATTRIB /* for the link count */) < 0) {
  81                         r = -errno;
  82                         goto finish;
  83                 }
  84         }
  85
  86         if ((fd = socket(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0)) < 0) {
  87                 r = -errno;
  88                 goto finish;
  89         }
  90
  91         zero(sa);
  92         sa.sa.sa_family = AF_UNIX;
  93         strncpy(sa.un.sun_path+1, "/org/freedesktop/plymouthd", sizeof(sa.un.sun_path)-1);
  94         if (connect(fd, &sa.sa, offsetof(struct sockaddr_un, sun_path) + 1 + strlen(sa.un.sun_path+1)) < 0) {
  95                 log_error("Failed to connect to Plymouth: %m");
  96                 r = -errno;
  97                 goto finish;
  98         }
  99
 100         if (accept_cached) {
 101                 packet = strdup("c");
 102                 n = 1;
 103         } else
 104                 asprintf(&packet, "*\002%c%s%n", (int) (strlen(message) + 1), message, &n);
 105
 106         if (!packet) {
 107                 r = -ENOMEM;
 108                 goto finish;
 109         }
 110
 111         if ((k = loop_write(fd, packet, n+1, true)) != n+1) {
 112                 r = k < 0 ? (int) k : -EIO;
 113                 goto finish;
 114         }
 115
 116         zero(pollfd);
 117         pollfd[POLL_SOCKET].fd = fd;
 118         pollfd[POLL_SOCKET].events = POLLIN;
 119         pollfd[POLL_INOTIFY].fd = notify;
 120         pollfd[POLL_INOTIFY].events = POLLIN;
 121
 122         for (;;) {
 123                 int sleep_for = -1, j;
 124
 125                 if (until > 0) {
 126                         usec_t y;
 127
 128                         y = now(CLOCK_MONOTONIC);
 129
 130                         if (y > until) {
 131                                 r = -ETIME;
 132                                 goto finish;
 133                         }
 134
 135                         sleep_for = (int) ((until - y) / USEC_PER_MSEC);
 136                 }
 137
 138                 if (flag_file)
 139                         if (access(flag_file, F_OK) < 0) {
 140                                 r = -errno;
 141                                 goto finish;
 142                         }
 143
 144                 if ((j = poll(pollfd, notify > 0 ? 2 : 1, sleep_for)) < 0) {
 145
 146                         if (errno == EINTR)
 147                                 continue;
 148
 149                         r = -errno;
 150                         goto finish;
 151                 } else if (j == 0) {
 152                         r = -ETIME;
 153                         goto finish;
 154                 }
 155
 156                 if (notify > 0 && pollfd[POLL_INOTIFY].revents != 0)
 157                         flush_fd(notify);
 158
 159                 if (pollfd[POLL_SOCKET].revents == 0)
 160                         continue;
 161
 162                 if ((k = read(fd, buffer + p, sizeof(buffer) - p)) <= 0) {
 163                         r = k < 0 ? -errno : -EIO;
 164                         goto finish;
 165                 }
 166
 167                 p += k;
 168
 169                 if (p < 1)
 170                         continue;
 171
 172                 if (buffer[0] == 5) {
 173
 174                         if (accept_cached) {
 175                                 /* Hmm, first try with cached
 176                                  * passwords failed, so let's retry
 177                                  * with a normal password request */
 178                                 free(packet);
 179                                 packet = NULL;
 180
 181                                 if (asprintf(&packet, "*\002%c%s%n", (int) (strlen(message) + 1), message, &n) < 0) {
 182                                         r = -ENOMEM;
 183                                         goto finish;
 184                                 }
 185
 186                                 if ((k = loop_write(fd, packet, n+1, true)) != n+1) {
 187                                         r = k < 0 ? (int) k : -EIO;
 188                                         goto finish;
 189                                 }
 190
 191                                 accept_cached = false;
 192                                 p = 0;
 193                                 continue;
 194                         }
 195
 196                         /* No password, because UI not shown */
 197                         r = -ENOENT;
 198                         goto finish;
 199
 200                 } else if (buffer[0] == 2 || buffer[0] == 9) {
 201                         uint32_t size;
 202                         char **l;
 203
 204                         /* One ore more answers */
 205                         if (p < 5)
 206                                 continue;
 207
 208                         memcpy(&size, buffer+1, sizeof(size));
 209                         if (size+5 > sizeof(buffer)) {
 210                                 r = -EIO;
 211                                 goto finish;
 212                         }
 213
 214                         if (p-5 < size)
 215                                 continue;
 216
 217                         if (!(l = strv_parse_nulstr(buffer + 5, size))) {
 218                                 r = -ENOMEM;
 219                                 goto finish;
 220                         }
 221
 222                         *_passphrases = l;
 223                         break;
 224
 225                 } else {
 226                         /* Unknown packet */
 227                         r = -EIO;
 228                         goto finish;
 229                 }
 230         }
 231
 232         r = 0;
 233
 234 finish:
 235         if (notify >= 0)
 236                 close_nointr_nofail(notify);
 237
 238         if (fd >= 0)
 239                 close_nointr_nofail(fd);
 240
 241         free(packet);
 242
 243         return r;
 244 }
 245
 246 static int parse_password(const char *filename, char **wall) {
 247         char *socket_name = NULL, *message = NULL, *packet = NULL;
 248         uint64_t not_after = 0;
 249         unsigned pid = 0;
 250         int socket_fd = -1;
 251         bool accept_cached = false;
 252
 253         const ConfigItem items[] = {
 254                 { "Socket",       config_parse_string,   &socket_name,   "Ask" },
 255                 { "NotAfter",     config_parse_uint64,   &not_after,     "Ask" },
 256                 { "Message",      config_parse_string,   &message,       "Ask" },
 257                 { "PID",          config_parse_unsigned, &pid,           "Ask" },
 258                 { "AcceptCached", config_parse_bool,     &accept_cached, "Ask" },
 259                 { NULL, NULL, NULL, NULL }
 260         };
 261
 262         FILE *f;
 263         int r;
 264         usec_t n;
 265
 266         assert(filename);
 267
 268         if (!(f = fopen(filename, "re"))) {
 269
 270                 if (errno == ENOENT)
 271                         return 0;
 272
 273                 log_error("open(%s): %m", filename);
 274                 return -errno;
 275         }
 276
 277         if ((r = config_parse(filename, f, NULL, items, true, NULL)) < 0) {
 278                 log_error("Failed to parse password file %s: %s", filename, strerror(-r));
 279                 goto finish;
 280         }
 281
 282         if (!socket_name || not_after <= 0) {
 283                 log_error("Invalid password file %s", filename);
 284                 r = -EBADMSG;
 285                 goto finish;
 286         }
 287
 288         n = now(CLOCK_MONOTONIC);
 289         if (n > not_after) {
 290                 r = 0;
 291                 goto finish;
 292         }
 293
 294         if (arg_action == ACTION_LIST)
 295                 printf("'%s' (PID %u)\n", message, pid);
 296         else if (arg_action == ACTION_WALL) {
 297                 char *_wall;
 298
 299                 if (asprintf(&_wall,
 300                              "%s%sPassword entry required for \'%s\' (PID %u).\r\n"
 301                              "Please enter password with the systemd-tty-ask-password-agent tool!",
 302                              *wall ? *wall : "",
 303                              *wall ? "\r\n\r\n" : "",
 304                              message,
 305                              pid) < 0) {
 306                         log_error("Out of memory");
 307                         r = -ENOMEM;
 308                         goto finish;
 309                 }
 310
 311                 free(*wall);
 312                 *wall = _wall;
 313         } else {
 314                 union {
 315                         struct sockaddr sa;
 316                         struct sockaddr_un un;
 317                 } sa;
 318                 size_t packet_length = 0;
 319
 320                 assert(arg_action == ACTION_QUERY ||
 321                        arg_action == ACTION_WATCH);
 322
 323                 if (access(socket_name, W_OK) < 0) {
 324
 325                         if (arg_action == ACTION_QUERY)
 326                                 log_info("Not querying '%s' (PID %u), lacking privileges.", message, pid);
 327
 328                         r = 0;
 329                         goto finish;
 330                 }
 331
 332                 if (arg_plymouth) {
 333                         char **passwords = NULL;
 334
 335                         if ((r = ask_password_plymouth(message, not_after, filename, accept_cached, &passwords)) >= 0) {
 336                                 char **p;
 337
 338                                 packet_length = 1;
 339                                 STRV_FOREACH(p, passwords)
 340                                         packet_length += strlen(*p) + 1;
 341
 342                                 if (!(packet = new(char, packet_length)))
 343                                         r = -ENOMEM;
 344                                 else {
 345                                         char *d;
 346
 347                                         packet[0] = '+';
 348                                         d = packet+1;
 349
 350                                         STRV_FOREACH(p, passwords)
 351                                                 d = stpcpy(d, *p) + 1;
 352                                 }
 353                         }
 354
 355                 } else {
 356                         int tty_fd = -1;
 357                         char *password;
 358
 359                         if (arg_console)
 360                                 if ((tty_fd = acquire_terminal("/dev/console", false, false, false)) < 0) {
 361                                         r = tty_fd;
 362                                         goto finish;
 363                                 }
 364
 365                         r = ask_password_tty(message, not_after, filename, &password);
 366
 367                         if (arg_console) {
 368                                 close_nointr_nofail(tty_fd);
 369                                 release_terminal();
 370                         }
 371
 372                         asprintf(&packet, "+%s", password);
 373                         free(password);
 374
 375                         packet_length = strlen(packet);
 376                 }
 377
 378                 if (r == -ETIME || r == -ENOENT) {
 379                         /* If the query went away, that's OK */
 380                         r = 0;
 381                         goto finish;
 382                 }
 383
 384                 if (r < 0) {
 385
 386                         log_error("Failed to query password: %s", strerror(-r));
 387                         goto finish;
 388                 }
 389
 390                 if (!packet) {
 391                         log_error("Out of memory");
 392                         r = -ENOMEM;
 393                         goto finish;
 394                 }
 395
 396                 if ((socket_fd = socket(AF_UNIX, SOCK_DGRAM|SOCK_CLOEXEC, 0)) < 0) {
 397                         log_error("socket(): %m");
 398                         r = -errno;
 399                         goto finish;
 400                 }
 401
 402                 zero(sa);
 403                 sa.un.sun_family = AF_UNIX;
 404                 strncpy(sa.un.sun_path, socket_name, sizeof(sa.un.sun_path));
 405
 406                 if (sendto(socket_fd, packet, packet_length, MSG_NOSIGNAL, &sa.sa, offsetof(struct sockaddr_un, sun_path) + strlen(socket_name)) < 0) {
 407                         log_error("Failed to send: %m");
 408                         r = -errno;
 409                         goto finish;
 410                 }
 411         }
 412
 413 finish:
 414         fclose(f);
 415
 416         if (socket_fd >= 0)
 417                 close_nointr_nofail(socket_fd);
 418
 419         free(packet);
 420         free(socket_name);
 421         free(message);
 422
 423         return r;
 424 }
 425
 426 static int wall_tty_block(void) {
 427         char *p;
 428         int fd, r;
 429         dev_t devnr;
 430
 431         if ((r = get_ctty_devnr(&devnr)) < 0)
 432                 return -r;
 433
 434         if (asprintf(&p, "/dev/.systemd/ask-password-block/%u:%u", major(devnr), minor(devnr)) < 0)
 435                 return -ENOMEM;
 436
 437         mkdir_parents(p, 0700);
 438         mkfifo(p, 0600);
 439
 440         fd = open(p, O_RDONLY|O_CLOEXEC|O_NONBLOCK|O_NOCTTY);
 441         free(p);
 442
 443         if (fd < 0)
 444                 return -errno;
 445
 446         return fd;
 447 }
 448
 449 static bool wall_tty_match(const char *path) {
 450         int fd, k;
 451         char *p;
 452         struct stat st;
 453
 454         if (path_is_absolute(path))
 455                 k = lstat(path, &st);
 456         else {
 457                 if (asprintf(&p, "/dev/%s", path) < 0)
 458                         return true;
 459
 460                 k = lstat(p, &st);
 461                 free(p);
 462         }
 463
 464         if (k < 0)
 465                 return true;
 466
 467         if (!S_ISCHR(st.st_mode))
 468                 return true;
 469
 470         /* We use named pipes to ensure that wall messages suggesting
 471          * password entry are not printed over password prompts
 472          * already shown. We use the fact here that opening a pipe in
 473          * non-blocking mode for write-only will succeed only if
 474          * there's some writer behind it. Using pipes has the
 475          * advantage that the block will automatically go away if the
 476          * process dies. */
 477
 478         if (asprintf(&p, "/dev/.systemd/ask-password-block/%u:%u", major(st.st_rdev), minor(st.st_rdev)) < 0)
 479                 return true;
 480
 481         fd = open(p, O_WRONLY|O_CLOEXEC|O_NONBLOCK|O_NOCTTY);
 482         free(p);
 483
 484         if (fd < 0)
 485                 return true;
 486
 487         /* What, we managed to open the pipe? Then this tty is filtered. */
 488         close_nointr_nofail(fd);
 489         return false;
 490 }
 491
 492 static int show_passwords(void) {
 493         DIR *d;
 494         struct dirent *de;
 495         int r = 0;
 496
 497         if (!(d = opendir("/dev/.systemd/ask-password"))) {
 498                 if (errno == ENOENT)
 499                         return 0;
 500
 501                 log_error("opendir(): %m");
 502                 return -errno;
 503         }
 504
 505         while ((de = readdir(d))) {
 506                 char *p;
 507                 int q;
 508                 char *wall;
 509
 510                 /* We only support /dev on tmpfs, hence we can rely on
 511                  * d_type to be reliable */
 512
 513                 if (de->d_type != DT_REG)
 514                         continue;
 515
 516                 if (ignore_file(de->d_name))
 517                         continue;
 518
 519                 if (!startswith(de->d_name, "ask."))
 520                         continue;
 521
 522                 if (!(p = strappend("/dev/.systemd/ask-password/", de->d_name))) {
 523                         log_error("Out of memory");
 524                         r = -ENOMEM;
 525                         goto finish;
 526                 }
 527
 528                 wall = NULL;
 529                 if ((q = parse_password(p, &wall)) < 0)
 530                         r = q;
 531
 532                 free(p);
 533
 534                 if (wall) {
 535                         utmp_wall(wall, wall_tty_match);
 536                         free(wall);
 537                 }
 538         }
 539
 540 finish:
 541         if (d)
 542                 closedir(d);
 543
 544         return r;
 545 }
 546
 547 static int watch_passwords(void) {
 548         enum {
 549                 FD_INOTIFY,
 550                 FD_SIGNAL,
 551                 _FD_MAX
 552         };
 553
 554         int notify = -1, signal_fd = -1, tty_block_fd = -1;
 555         struct pollfd pollfd[_FD_MAX];
 556         sigset_t mask;
 557         int r;
 558
 559         tty_block_fd = wall_tty_block();
 560
 561         mkdir_p("/dev/.systemd/ask-password", 0755);
 562
 563         if ((notify = inotify_init1(IN_CLOEXEC)) < 0) {
 564                 r = -errno;
 565                 goto finish;
 566         }
 567
 568         if (inotify_add_watch(notify, "/dev/.systemd/ask-password", IN_CLOSE_WRITE|IN_MOVED_TO) < 0) {
 569                 r = -errno;
 570                 goto finish;
 571         }
 572
 573         assert_se(sigemptyset(&mask) == 0);
 574         sigset_add_many(&mask, SIGINT, SIGTERM, -1);
 575         assert_se(sigprocmask(SIG_SETMASK, &mask, NULL) == 0);
 576
 577         if ((signal_fd = signalfd(-1, &mask, SFD_NONBLOCK|SFD_CLOEXEC)) < 0) {
 578                 log_error("signalfd(): %m");
 579                 r = -errno;
 580                 goto finish;
 581         }
 582
 583         zero(pollfd);
 584         pollfd[FD_INOTIFY].fd = notify;
 585         pollfd[FD_INOTIFY].events = POLLIN;
 586         pollfd[FD_SIGNAL].fd = signal_fd;
 587         pollfd[FD_SIGNAL].events = POLLIN;
 588
 589         for (;;) {
 590                 if ((r = show_passwords()) < 0)
 591                         log_error("Failed to show password: %s", strerror(-r));
 592
 593                 if (poll(pollfd, _FD_MAX, -1) < 0) {
 594
 595                         if (errno == EINTR)
 596                                 continue;
 597
 598                         r = -errno;
 599                         goto finish;
 600                 }
 601
 602                 if (pollfd[FD_INOTIFY].revents != 0)
 603                         flush_fd(notify);
 604
 605                 if (pollfd[FD_SIGNAL].revents != 0)
 606                         break;
 607         }
 608
 609         r = 0;
 610
 611 finish:
 612         if (notify >= 0)
 613                 close_nointr_nofail(notify);
 614
 615         if (signal_fd >= 0)
 616                 close_nointr_nofail(signal_fd);
 617
 618         if (tty_block_fd >= 0)
 619                 close_nointr_nofail(tty_block_fd);
 620
 621         return r;
 622 }
 623
 624 static int help(void) {
 625
 626         printf("%s [OPTIONS...]\n\n"
 627                "Process system password requests.\n\n"
 628                "  -h --help     Show this help\n"
 629                "     --list     Show pending password requests\n"
 630                "     --query    Process pending password requests\n"
 631                "     --watch    Continuously process password requests\n"
 632                "     --wall     Continuously forward password requests to wall\n"
 633                "     --plymouth Ask question with Plymouth instead of on TTY\n"
 634                "     --console  Ask question on /dev/console instead of current TTY\n",
 635                program_invocation_short_name);
 636
 637         return 0;
 638 }
 639
 640 static int parse_argv(int argc, char *argv[]) {
 641
 642         enum {
 643                 ARG_LIST = 0x100,
 644                 ARG_QUERY,
 645                 ARG_WATCH,
 646                 ARG_WALL,
 647                 ARG_PLYMOUTH,
 648                 ARG_CONSOLE
 649         };
 650
 651         static const struct option options[] = {
 652                 { "help",     no_argument, NULL, 'h'          },
 653                 { "list",     no_argument, NULL, ARG_LIST     },
 654                 { "query",    no_argument, NULL, ARG_QUERY    },
 655                 { "watch",    no_argument, NULL, ARG_WATCH    },
 656                 { "wall",     no_argument, NULL, ARG_WALL     },
 657                 { "plymouth", no_argument, NULL, ARG_PLYMOUTH },
 658                 { "console",  no_argument, NULL, ARG_CONSOLE  },
 659                 { NULL,    0,           NULL, 0               }
 660         };
 661
 662         int c;
 663
 664         assert(argc >= 0);
 665         assert(argv);
 666
 667         while ((c = getopt_long(argc, argv, "h", options, NULL)) >= 0) {
 668
 669                 switch (c) {
 670
 671                 case 'h':
 672                         help();
 673                         return 0;
 674
 675                 case ARG_LIST:
 676                         arg_action = ACTION_LIST;
 677                         break;
 678
 679                 case ARG_QUERY:
 680                         arg_action = ACTION_QUERY;
 681                         break;
 682
 683                 case ARG_WATCH:
 684                         arg_action = ACTION_WATCH;
 685                         break;
 686
 687                 case ARG_WALL:
 688                         arg_action = ACTION_WALL;
 689                         break;
 690
 691                 case ARG_PLYMOUTH:
 692                         arg_plymouth = true;
 693                         break;
 694
 695                 case ARG_CONSOLE:
 696                         arg_console = true;
 697                         break;
 698
 699                 case '?':
 700                         return -EINVAL;
 701
 702                 default:
 703                         log_error("Unknown option code %c", c);
 704                         return -EINVAL;
 705                 }
 706         }
 707
 708         if (optind != argc) {
 709                 help();
 710                 return -EINVAL;
 711         }
 712
 713         return 1;
 714 }
 715
 716 int main(int argc, char *argv[]) {
 717         int r;
 718
 719         log_parse_environment();
 720         log_open();
 721
 722         if ((r = parse_argv(argc, argv)) <= 0)
 723                 goto finish;
 724
 725         if (arg_console) {
 726                 setsid();
 727                 release_terminal();
 728         }
 729
 730         if (arg_action == ACTION_WATCH ||
 731             arg_action == ACTION_WALL)
 732                 r = watch_passwords();
 733         else
 734                 r = show_passwords();
 735
 736         if (r < 0)
 737                 log_error("Error: %s", strerror(-r));
 738
 739 finish:
 740         return r < 0 ? EXIT_FAILURE : EXIT_SUCCESS;
 741 }