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