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                         size = le32toh(size);
 210                         if (size+5 > sizeof(buffer)) {
 211                                 r = -EIO;
 212                                 goto finish;
 213                         }
 214
 215                         if (p-5 < size)
 216                                 continue;
 217
 218                         if (!(l = strv_parse_nulstr(buffer + 5, size))) {
 219                                 r = -ENOMEM;
 220                                 goto finish;
 221                         }
 222
 223                         *_passphrases = l;
 224                         break;
 225
 226                 } else {
 227                         /* Unknown packet */
 228                         r = -EIO;
 229                         goto finish;
 230                 }
 231         }
 232
 233         r = 0;
 234
 235 finish:
 236         if (notify >= 0)
 237                 close_nointr_nofail(notify);
 238
 239         if (fd >= 0)
 240                 close_nointr_nofail(fd);
 241
 242         free(packet);
 243
 244         return r;
 245 }
 246
 247 static int parse_password(const char *filename, char **wall) {
 248         char *socket_name = NULL, *message = NULL, *packet = NULL;
 249         uint64_t not_after = 0;
 250         unsigned pid = 0;
 251         int socket_fd = -1;
 252         bool accept_cached = false;
 253
 254         const ConfigTableItem items[] = {
 255                 { "Ask", "Socket",       config_parse_string,   0, &socket_name   },
 256                 { "Ask", "NotAfter",     config_parse_uint64,   0, &not_after     },
 257                 { "Ask", "Message",      config_parse_string,   0, &message       },
 258                 { "Ask", "PID",          config_parse_unsigned, 0, &pid           },
 259                 { "Ask", "AcceptCached", config_parse_bool,     0, &accept_cached },
 260                 { NULL, NULL, NULL, 0, NULL }
 261         };
 262
 263         FILE *f;
 264         int r;
 265
 266         assert(filename);
 267
 268         f = fopen(filename, "re");
 269         if (!f) {
 270                 if (errno == ENOENT)
 271                         return 0;
 272
 273                 log_error("open(%s): %m", filename);
 274                 return -errno;
 275         }
 276
 277         r = config_parse(filename, f, NULL, config_item_table_lookup, (void*) items, true, NULL);
 278         if (r < 0) {
 279                 log_error("Failed to parse password file %s: %s", filename, strerror(-r));
 280                 goto finish;
 281         }
 282
 283         if (!socket_name) {
 284                 log_error("Invalid password file %s", filename);
 285                 r = -EBADMSG;
 286                 goto finish;
 287         }
 288
 289         if (not_after > 0) {
 290                 if (now(CLOCK_MONOTONIC) > not_after) {
 291                         r = 0;
 292                         goto finish;
 293                 }
 294         }
 295
 296         if (pid > 0 &&
 297             kill(pid, 0) < 0 &&
 298             errno == ESRCH) {
 299                 r = 0;
 300                 goto finish;
 301         }
 302
 303         if (arg_action == ACTION_LIST)
 304                 printf("'%s' (PID %u)\n", message, pid);
 305         else if (arg_action == ACTION_WALL) {
 306                 char *_wall;
 307
 308                 if (asprintf(&_wall,
 309                              "%s%sPassword entry required for \'%s\' (PID %u).\r\n"
 310                              "Please enter password with the systemd-tty-ask-password-agent tool!",
 311                              *wall ? *wall : "",
 312                              *wall ? "\r\n\r\n" : "",
 313                              message,
 314                              pid) < 0) {
 315                         log_error("Out of memory");
 316                         r = -ENOMEM;
 317                         goto finish;
 318                 }
 319
 320                 free(*wall);
 321                 *wall = _wall;
 322         } else {
 323                 union {
 324                         struct sockaddr sa;
 325                         struct sockaddr_un un;
 326                 } sa;
 327                 size_t packet_length = 0;
 328
 329                 assert(arg_action == ACTION_QUERY ||
 330                        arg_action == ACTION_WATCH);
 331
 332                 if (access(socket_name, W_OK) < 0) {
 333
 334                         if (arg_action == ACTION_QUERY)
 335                                 log_info("Not querying '%s' (PID %u), lacking privileges.", message, pid);
 336
 337                         r = 0;
 338                         goto finish;
 339                 }
 340
 341                 if (arg_plymouth) {
 342                         char **passwords = NULL;
 343
 344                         if ((r = ask_password_plymouth(message, not_after, filename, accept_cached, &passwords)) >= 0) {
 345                                 char **p;
 346
 347                                 packet_length = 1;
 348                                 STRV_FOREACH(p, passwords)
 349                                         packet_length += strlen(*p) + 1;
 350
 351                                 if (!(packet = new(char, packet_length)))
 352                                         r = -ENOMEM;
 353                                 else {
 354                                         char *d;
 355
 356                                         packet[0] = '+';
 357                                         d = packet+1;
 358
 359                                         STRV_FOREACH(p, passwords)
 360                                                 d = stpcpy(d, *p) + 1;
 361                                 }
 362                         }
 363
 364                 } else {
 365                         int tty_fd = -1;
 366                         char *password;
 367
 368                         if (arg_console)
 369                                 if ((tty_fd = acquire_terminal("/dev/console", false, false, false)) < 0) {
 370                                         r = tty_fd;
 371                                         goto finish;
 372                                 }
 373
 374                         r = ask_password_tty(message, not_after, filename, &password);
 375
 376                         if (arg_console) {
 377                                 close_nointr_nofail(tty_fd);
 378                                 release_terminal();
 379                         }
 380
 381                         if (r >= 0) {
 382                                 packet_length = 1+strlen(password)+1;
 383                                 if (!(packet = new(char, packet_length)))
 384                                         r = -ENOMEM;
 385                                 else {
 386                                         packet[0] = '+';
 387                                         strcpy(packet+1, password);
 388                                 }
 389
 390                                 free(password);
 391                         }
 392                 }
 393
 394                 if (r == -ETIME || r == -ENOENT) {
 395                         /* If the query went away, that's OK */
 396                         r = 0;
 397                         goto finish;
 398                 }
 399
 400                 if (r < 0) {
 401                         log_error("Failed to query password: %s", strerror(-r));
 402                         goto finish;
 403                 }
 404
 405                 if ((socket_fd = socket(AF_UNIX, SOCK_DGRAM|SOCK_CLOEXEC, 0)) < 0) {
 406                         log_error("socket(): %m");
 407                         r = -errno;
 408                         goto finish;
 409                 }
 410
 411                 zero(sa);
 412                 sa.un.sun_family = AF_UNIX;
 413                 strncpy(sa.un.sun_path, socket_name, sizeof(sa.un.sun_path));
 414
 415                 if (sendto(socket_fd, packet, packet_length, MSG_NOSIGNAL, &sa.sa, offsetof(struct sockaddr_un, sun_path) + strlen(socket_name)) < 0) {
 416                         log_error("Failed to send: %m");
 417                         r = -errno;
 418                         goto finish;
 419                 }
 420         }
 421
 422 finish:
 423         fclose(f);
 424
 425         if (socket_fd >= 0)
 426                 close_nointr_nofail(socket_fd);
 427
 428         free(packet);
 429         free(socket_name);
 430         free(message);
 431
 432         return r;
 433 }
 434
 435 static int wall_tty_block(void) {
 436         char *p;
 437         int fd, r;
 438         dev_t devnr;
 439
 440         r = get_ctty_devnr(0, &devnr);
 441         if (r < 0)
 442                 return -r;
 443
 444         if (asprintf(&p, "/run/systemd/ask-password-block/%u:%u", major(devnr), minor(devnr)) < 0)
 445                 return -ENOMEM;
 446
 447         mkdir_parents(p, 0700);
 448         mkfifo(p, 0600);
 449
 450         fd = open(p, O_RDONLY|O_CLOEXEC|O_NONBLOCK|O_NOCTTY);
 451         free(p);
 452
 453         if (fd < 0)
 454                 return -errno;
 455
 456         return fd;
 457 }
 458
 459 static bool wall_tty_match(const char *path) {
 460         int fd, k;
 461         char *p;
 462         struct stat st;
 463
 464         if (path_is_absolute(path))
 465                 k = lstat(path, &st);
 466         else {
 467                 if (asprintf(&p, "/dev/%s", path) < 0)
 468                         return true;
 469
 470                 k = lstat(p, &st);
 471                 free(p);
 472         }
 473
 474         if (k < 0)
 475                 return true;
 476
 477         if (!S_ISCHR(st.st_mode))
 478                 return true;
 479
 480         /* We use named pipes to ensure that wall messages suggesting
 481          * password entry are not printed over password prompts
 482          * already shown. We use the fact here that opening a pipe in
 483          * non-blocking mode for write-only will succeed only if
 484          * there's some writer behind it. Using pipes has the
 485          * advantage that the block will automatically go away if the
 486          * process dies. */
 487
 488         if (asprintf(&p, "/run/systemd/ask-password-block/%u:%u", major(st.st_rdev), minor(st.st_rdev)) < 0)
 489                 return true;
 490
 491         fd = open(p, O_WRONLY|O_CLOEXEC|O_NONBLOCK|O_NOCTTY);
 492         free(p);
 493
 494         if (fd < 0)
 495                 return true;
 496
 497         /* What, we managed to open the pipe? Then this tty is filtered. */
 498         close_nointr_nofail(fd);
 499         return false;
 500 }
 501
 502 static int show_passwords(void) {
 503         DIR *d;
 504         struct dirent *de;
 505         int r = 0;
 506
 507         if (!(d = opendir("/run/systemd/ask-password"))) {
 508                 if (errno == ENOENT)
 509                         return 0;
 510
 511                 log_error("opendir(): %m");
 512                 return -errno;
 513         }
 514
 515         while ((de = readdir(d))) {
 516                 char *p;
 517                 int q;
 518                 char *wall;
 519
 520                 /* We only support /dev on tmpfs, hence we can rely on
 521                  * d_type to be reliable */
 522
 523                 if (de->d_type != DT_REG)
 524                         continue;
 525
 526                 if (ignore_file(de->d_name))
 527                         continue;
 528
 529                 if (!startswith(de->d_name, "ask."))
 530                         continue;
 531
 532                 if (!(p = strappend("/run/systemd/ask-password/", de->d_name))) {
 533                         log_error("Out of memory");
 534                         r = -ENOMEM;
 535                         goto finish;
 536                 }
 537
 538                 wall = NULL;
 539                 if ((q = parse_password(p, &wall)) < 0)
 540                         r = q;
 541
 542                 free(p);
 543
 544                 if (wall) {
 545                         utmp_wall(wall, wall_tty_match);
 546                         free(wall);
 547                 }
 548         }
 549
 550 finish:
 551         if (d)
 552                 closedir(d);
 553
 554         return r;
 555 }
 556
 557 static int watch_passwords(void) {
 558         enum {
 559                 FD_INOTIFY,
 560                 FD_SIGNAL,
 561                 _FD_MAX
 562         };
 563
 564         int notify = -1, signal_fd = -1, tty_block_fd = -1;
 565         struct pollfd pollfd[_FD_MAX];
 566         sigset_t mask;
 567         int r;
 568
 569         tty_block_fd = wall_tty_block();
 570
 571         mkdir_p("/run/systemd/ask-password", 0755);
 572
 573         if ((notify = inotify_init1(IN_CLOEXEC)) < 0) {
 574                 r = -errno;
 575                 goto finish;
 576         }
 577
 578         if (inotify_add_watch(notify, "/run/systemd/ask-password", IN_CLOSE_WRITE|IN_MOVED_TO) < 0) {
 579                 r = -errno;
 580                 goto finish;
 581         }
 582
 583         assert_se(sigemptyset(&mask) == 0);
 584         sigset_add_many(&mask, SIGINT, SIGTERM, -1);
 585         assert_se(sigprocmask(SIG_SETMASK, &mask, NULL) == 0);
 586
 587         if ((signal_fd = signalfd(-1, &mask, SFD_NONBLOCK|SFD_CLOEXEC)) < 0) {
 588                 log_error("signalfd(): %m");
 589                 r = -errno;
 590                 goto finish;
 591         }
 592
 593         zero(pollfd);
 594         pollfd[FD_INOTIFY].fd = notify;
 595         pollfd[FD_INOTIFY].events = POLLIN;
 596         pollfd[FD_SIGNAL].fd = signal_fd;
 597         pollfd[FD_SIGNAL].events = POLLIN;
 598
 599         for (;;) {
 600                 if ((r = show_passwords()) < 0)
 601                         log_error("Failed to show password: %s", strerror(-r));
 602
 603                 if (poll(pollfd, _FD_MAX, -1) < 0) {
 604
 605                         if (errno == EINTR)
 606                                 continue;
 607
 608                         r = -errno;
 609                         goto finish;
 610                 }
 611
 612                 if (pollfd[FD_INOTIFY].revents != 0)
 613                         flush_fd(notify);
 614
 615                 if (pollfd[FD_SIGNAL].revents != 0)
 616                         break;
 617         }
 618
 619         r = 0;
 620
 621 finish:
 622         if (notify >= 0)
 623                 close_nointr_nofail(notify);
 624
 625         if (signal_fd >= 0)
 626                 close_nointr_nofail(signal_fd);
 627
 628         if (tty_block_fd >= 0)
 629                 close_nointr_nofail(tty_block_fd);
 630
 631         return r;
 632 }
 633
 634 static int help(void) {
 635
 636         printf("%s [OPTIONS...]\n\n"
 637                "Process system password requests.\n\n"
 638                "  -h --help     Show this help\n"
 639                "     --list     Show pending password requests\n"
 640                "     --query    Process pending password requests\n"
 641                "     --watch    Continuously process password requests\n"
 642                "     --wall     Continuously forward password requests to wall\n"
 643                "     --plymouth Ask question with Plymouth instead of on TTY\n"
 644                "     --console  Ask question on /dev/console instead of current TTY\n",
 645                program_invocation_short_name);
 646
 647         return 0;
 648 }
 649
 650 static int parse_argv(int argc, char *argv[]) {
 651
 652         enum {
 653                 ARG_LIST = 0x100,
 654                 ARG_QUERY,
 655                 ARG_WATCH,
 656                 ARG_WALL,
 657                 ARG_PLYMOUTH,
 658                 ARG_CONSOLE
 659         };
 660
 661         static const struct option options[] = {
 662                 { "help",     no_argument, NULL, 'h'          },
 663                 { "list",     no_argument, NULL, ARG_LIST     },
 664                 { "query",    no_argument, NULL, ARG_QUERY    },
 665                 { "watch",    no_argument, NULL, ARG_WATCH    },
 666                 { "wall",     no_argument, NULL, ARG_WALL     },
 667                 { "plymouth", no_argument, NULL, ARG_PLYMOUTH },
 668                 { "console",  no_argument, NULL, ARG_CONSOLE  },
 669                 { NULL,    0,           NULL, 0               }
 670         };
 671
 672         int c;
 673
 674         assert(argc >= 0);
 675         assert(argv);
 676
 677         while ((c = getopt_long(argc, argv, "h", options, NULL)) >= 0) {
 678
 679                 switch (c) {
 680
 681                 case 'h':
 682                         help();
 683                         return 0;
 684
 685                 case ARG_LIST:
 686                         arg_action = ACTION_LIST;
 687                         break;
 688
 689                 case ARG_QUERY:
 690                         arg_action = ACTION_QUERY;
 691                         break;
 692
 693                 case ARG_WATCH:
 694                         arg_action = ACTION_WATCH;
 695                         break;
 696
 697                 case ARG_WALL:
 698                         arg_action = ACTION_WALL;
 699                         break;
 700
 701                 case ARG_PLYMOUTH:
 702                         arg_plymouth = true;
 703                         break;
 704
 705                 case ARG_CONSOLE:
 706                         arg_console = true;
 707                         break;
 708
 709                 case '?':
 710                         return -EINVAL;
 711
 712                 default:
 713                         log_error("Unknown option code %c", c);
 714                         return -EINVAL;
 715                 }
 716         }
 717
 718         if (optind != argc) {
 719                 help();
 720                 return -EINVAL;
 721         }
 722
 723         return 1;
 724 }
 725
 726 int main(int argc, char *argv[]) {
 727         int r;
 728
 729         log_parse_environment();
 730         log_open();
 731
 732         umask(0022);
 733
 734         if ((r = parse_argv(argc, argv)) <= 0)
 735                 goto finish;
 736
 737         if (arg_console) {
 738                 setsid();
 739                 release_terminal();
 740         }
 741
 742         if (arg_action == ACTION_WATCH ||
 743             arg_action == ACTION_WALL)
 744                 r = watch_passwords();
 745         else
 746                 r = show_passwords();
 747
 748         if (r < 0)
 749                 log_error("Error: %s", strerror(-r));
 750
 751 finish:
 752         return r < 0 ? EXIT_FAILURE : EXIT_SUCCESS;
 753 }