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