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

   1 /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
   2
   3 /***
   4   This file is part of systemd.
   5
   6   Copyright 2010 Lennart Poettering
   7
   8   systemd is free software; you can redistribute it and/or modify it
   9   under the terms of the GNU Lesser General Public License as published by
  10   the Free Software Foundation; either version 2.1 of the License, or
  11   (at your option) any later version.
  12
  13   systemd is distributed in the hope that it will be useful, but
  14   WITHOUT ANY WARRANTY; without even the implied warranty of
  15   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  16   Lesser General Public License for more details.
  17
  18   You should have received a copy of the GNU Lesser General Public License
  19   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  20 ***/
  21
  22 #include <stdbool.h>
  23 #include <errno.h>
  24 #include <string.h>
  25 #include <sys/socket.h>
  26 #include <sys/un.h>
  27 #include <stddef.h>
  28 #include <sys/poll.h>
  29 #include <sys/inotify.h>
  30 #include <unistd.h>
  31 #include <getopt.h>
  32 #include <sys/signalfd.h>
  33 #include <fcntl.h>
  34
  35 #include "util.h"
  36 #include "mkdir.h"
  37 #include "path-util.h"
  38 #include "conf-parser.h"
  39 #include "utmp-wtmp.h"
  40 #include "socket-util.h"
  41 #include "ask-password-api.h"
  42 #include "strv.h"
  43 #include "build.h"
  44
  45 static enum {
  46         ACTION_LIST,
  47         ACTION_QUERY,
  48         ACTION_WATCH,
  49         ACTION_WALL
  50 } arg_action = ACTION_QUERY;
  51
  52 static bool arg_plymouth = false;
  53 static bool arg_console = false;
  54
  55 static int ask_password_plymouth(
  56                 const char *message,
  57                 usec_t until,
  58                 const char *flag_file,
  59                 bool accept_cached,
  60                 char ***_passphrases) {
  61
  62         int fd = -1, notify = -1;
  63         union sockaddr_union sa;
  64         char *packet = NULL;
  65         ssize_t k;
  66         int r, n;
  67         struct pollfd pollfd[2];
  68         char buffer[LINE_MAX];
  69         size_t p = 0;
  70         enum {
  71                 POLL_SOCKET,
  72                 POLL_INOTIFY
  73         };
  74
  75         assert(_passphrases);
  76
  77         if (flag_file) {
  78                 if ((notify = inotify_init1(IN_CLOEXEC|IN_NONBLOCK)) < 0) {
  79                         r = -errno;
  80                         goto finish;
  81                 }
  82
  83                 if (inotify_add_watch(notify, flag_file, IN_ATTRIB /* for the link count */) < 0) {
  84                         r = -errno;
  85                         goto finish;
  86                 }
  87         }
  88
  89         if ((fd = socket(AF_UNIX, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0)) < 0) {
  90                 r = -errno;
  91                 goto finish;
  92         }
  93
  94         zero(sa);
  95         sa.sa.sa_family = AF_UNIX;
  96         strncpy(sa.un.sun_path+1, "/org/freedesktop/plymouthd", sizeof(sa.un.sun_path)-1);
  97         if (connect(fd, &sa.sa, offsetof(struct sockaddr_un, sun_path) + 1 + strlen(sa.un.sun_path+1)) < 0) {
  98                 log_error("Failed to connect to Plymouth: %m");
  99                 r = -errno;
 100                 goto finish;
 101         }
 102
 103         if (accept_cached) {
 104                 packet = strdup("c");
 105                 n = 1;
 106         } else
 107                 asprintf(&packet, "*\002%c%s%n", (int) (strlen(message) + 1), message, &n);
 108
 109         if (!packet) {
 110                 r = -ENOMEM;
 111                 goto finish;
 112         }
 113
 114         if ((k = loop_write(fd, packet, n+1, true)) != n+1) {
 115                 r = k < 0 ? (int) k : -EIO;
 116                 goto finish;
 117         }
 118
 119         zero(pollfd);
 120         pollfd[POLL_SOCKET].fd = fd;
 121         pollfd[POLL_SOCKET].events = POLLIN;
 122         pollfd[POLL_INOTIFY].fd = notify;
 123         pollfd[POLL_INOTIFY].events = POLLIN;
 124
 125         for (;;) {
 126                 int sleep_for = -1, j;
 127
 128                 if (until > 0) {
 129                         usec_t y;
 130
 131                         y = now(CLOCK_MONOTONIC);
 132
 133                         if (y > until) {
 134                                 r = -ETIME;
 135                                 goto finish;
 136                         }
 137
 138                         sleep_for = (int) ((until - y) / USEC_PER_MSEC);
 139                 }
 140
 141                 if (flag_file)
 142                         if (access(flag_file, F_OK) < 0) {
 143                                 r = -errno;
 144                                 goto finish;
 145                         }
 146
 147                 if ((j = poll(pollfd, notify > 0 ? 2 : 1, sleep_for)) < 0) {
 148
 149                         if (errno == EINTR)
 150                                 continue;
 151
 152                         r = -errno;
 153                         goto finish;
 154                 } else if (j == 0) {
 155                         r = -ETIME;
 156                         goto finish;
 157                 }
 158
 159                 if (notify > 0 && pollfd[POLL_INOTIFY].revents != 0)
 160                         flush_fd(notify);
 161
 162                 if (pollfd[POLL_SOCKET].revents == 0)
 163                         continue;
 164
 165                 if ((k = read(fd, buffer + p, sizeof(buffer) - p)) <= 0) {
 166                         r = k < 0 ? -errno : -EIO;
 167                         goto finish;
 168                 }
 169
 170                 p += k;
 171
 172                 if (p < 1)
 173                         continue;
 174
 175                 if (buffer[0] == 5) {
 176
 177                         if (accept_cached) {
 178                                 /* Hmm, first try with cached
 179                                  * passwords failed, so let's retry
 180                                  * with a normal password request */
 181                                 free(packet);
 182                                 packet = NULL;
 183
 184                                 if (asprintf(&packet, "*\002%c%s%n", (int) (strlen(message) + 1), message, &n) < 0) {
 185                                         r = -ENOMEM;
 186                                         goto finish;
 187                                 }
 188
 189                                 if ((k = loop_write(fd, packet, n+1, true)) != n+1) {
 190                                         r = k < 0 ? (int) k : -EIO;
 191                                         goto finish;
 192                                 }
 193
 194                                 accept_cached = false;
 195                                 p = 0;
 196                                 continue;
 197                         }
 198
 199                         /* No password, because UI not shown */
 200                         r = -ENOENT;
 201                         goto finish;
 202
 203                 } else if (buffer[0] == 2 || buffer[0] == 9) {
 204                         uint32_t size;
 205                         char **l;
 206
 207                         /* One ore more answers */
 208                         if (p < 5)
 209                                 continue;
 210
 211                         memcpy(&size, buffer+1, sizeof(size));
 212                         size = le32toh(size);
 213                         if (size+5 > sizeof(buffer)) {
 214                                 r = -EIO;
 215                                 goto finish;
 216                         }
 217
 218                         if (p-5 < size)
 219                                 continue;
 220
 221                         if (!(l = strv_parse_nulstr(buffer + 5, size))) {
 222                                 r = -ENOMEM;
 223                                 goto finish;
 224                         }
 225
 226                         *_passphrases = l;
 227                         break;
 228
 229                 } else {
 230                         /* Unknown packet */
 231                         r = -EIO;
 232                         goto finish;
 233                 }
 234         }
 235
 236         r = 0;
 237
 238 finish:
 239         if (notify >= 0)
 240                 close_nointr_nofail(notify);
 241
 242         if (fd >= 0)
 243                 close_nointr_nofail(fd);
 244
 245         free(packet);
 246
 247         return r;
 248 }
 249
 250 static int parse_password(const char *filename, char **wall) {
 251         char *socket_name = NULL, *message = NULL, *packet = NULL;
 252         uint64_t not_after = 0;
 253         unsigned pid = 0;
 254         int socket_fd = -1;
 255         bool accept_cached = false;
 256
 257         const ConfigTableItem items[] = {
 258                 { "Ask", "Socket",       config_parse_string,   0, &socket_name   },
 259                 { "Ask", "NotAfter",     config_parse_uint64,   0, &not_after     },
 260                 { "Ask", "Message",      config_parse_string,   0, &message       },
 261                 { "Ask", "PID",          config_parse_unsigned, 0, &pid           },
 262                 { "Ask", "AcceptCached", config_parse_bool,     0, &accept_cached },
 263                 { NULL, NULL, NULL, 0, NULL }
 264         };
 265
 266         FILE *f;
 267         int r;
 268
 269         assert(filename);
 270
 271         f = fopen(filename, "re");
 272         if (!f) {
 273                 if (errno == ENOENT)
 274                         return 0;
 275
 276                 log_error("open(%s): %m", filename);
 277                 return -errno;
 278         }
 279
 280         r = config_parse(filename, f, NULL, config_item_table_lookup, (void*) items, true, NULL);
 281         if (r < 0) {
 282                 log_error("Failed to parse password file %s: %s", filename, strerror(-r));
 283                 goto finish;
 284         }
 285
 286         if (!socket_name) {
 287                 log_error("Invalid password file %s", filename);
 288                 r = -EBADMSG;
 289                 goto finish;
 290         }
 291
 292         if (not_after > 0) {
 293                 if (now(CLOCK_MONOTONIC) > not_after) {
 294                         r = 0;
 295                         goto finish;
 296                 }
 297         }
 298
 299         if (pid > 0 &&
 300             kill(pid, 0) < 0 &&
 301             errno == ESRCH) {
 302                 r = 0;
 303                 goto finish;
 304         }
 305
 306         if (arg_action == ACTION_LIST)
 307                 printf("'%s' (PID %u)\n", message, pid);
 308         else if (arg_action == ACTION_WALL) {
 309                 char *_wall;
 310
 311                 if (asprintf(&_wall,
 312                              "%s%sPassword entry required for \'%s\' (PID %u).\r\n"
 313                              "Please enter password with the systemd-tty-ask-password-agent tool!",
 314                              *wall ? *wall : "",
 315                              *wall ? "\r\n\r\n" : "",
 316                              message,
 317                              pid) < 0) {
 318                         log_error("Out of memory");
 319                         r = -ENOMEM;
 320                         goto finish;
 321                 }
 322
 323                 free(*wall);
 324                 *wall = _wall;
 325         } else {
 326                 union {
 327                         struct sockaddr sa;
 328                         struct sockaddr_un un;
 329                 } sa;
 330                 size_t packet_length = 0;
 331
 332                 assert(arg_action == ACTION_QUERY ||
 333                        arg_action == ACTION_WATCH);
 334
 335                 if (access(socket_name, W_OK) < 0) {
 336
 337                         if (arg_action == ACTION_QUERY)
 338                                 log_info("Not querying '%s' (PID %u), lacking privileges.", message, pid);
 339
 340                         r = 0;
 341                         goto finish;
 342                 }
 343
 344                 if (arg_plymouth) {
 345                         char **passwords = NULL;
 346
 347                         if ((r = ask_password_plymouth(message, not_after, filename, accept_cached, &passwords)) >= 0) {
 348                                 char **p;
 349
 350                                 packet_length = 1;
 351                                 STRV_FOREACH(p, passwords)
 352                                         packet_length += strlen(*p) + 1;
 353
 354                                 if (!(packet = new(char, packet_length)))
 355                                         r = -ENOMEM;
 356                                 else {
 357                                         char *d;
 358
 359                                         packet[0] = '+';
 360                                         d = packet+1;
 361
 362                                         STRV_FOREACH(p, passwords)
 363                                                 d = stpcpy(d, *p) + 1;
 364                                 }
 365                         }
 366
 367                 } else {
 368                         int tty_fd = -1;
 369                         char *password;
 370
 371                         if (arg_console)
 372                                 if ((tty_fd = acquire_terminal("/dev/console", false, false, false, (usec_t) -1)) < 0) {
 373                                         r = tty_fd;
 374                                         goto finish;
 375                                 }
 376
 377                         r = ask_password_tty(message, not_after, filename, &password);
 378
 379                         if (arg_console) {
 380                                 close_nointr_nofail(tty_fd);
 381                                 release_terminal();
 382                         }
 383
 384                         if (r >= 0) {
 385                                 packet_length = 1+strlen(password)+1;
 386                                 if (!(packet = new(char, packet_length)))
 387                                         r = -ENOMEM;
 388                                 else {
 389                                         packet[0] = '+';
 390                                         strcpy(packet+1, password);
 391                                 }
 392
 393                                 free(password);
 394                         }
 395                 }
 396
 397                 if (r == -ETIME || r == -ENOENT) {
 398                         /* If the query went away, that's OK */
 399                         r = 0;
 400                         goto finish;
 401                 }
 402
 403                 if (r < 0) {
 404                         log_error("Failed to query password: %s", strerror(-r));
 405                         goto finish;
 406                 }
 407
 408                 if ((socket_fd = socket(AF_UNIX, SOCK_DGRAM|SOCK_CLOEXEC, 0)) < 0) {
 409                         log_error("socket(): %m");
 410                         r = -errno;
 411                         goto finish;
 412                 }
 413
 414                 zero(sa);
 415                 sa.un.sun_family = AF_UNIX;
 416                 strncpy(sa.un.sun_path, socket_name, sizeof(sa.un.sun_path));
 417
 418                 if (sendto(socket_fd, packet, packet_length, MSG_NOSIGNAL, &sa.sa, offsetof(struct sockaddr_un, sun_path) + strlen(socket_name)) < 0) {
 419                         log_error("Failed to send: %m");
 420                         r = -errno;
 421                         goto finish;
 422                 }
 423         }
 424
 425 finish:
 426         fclose(f);
 427
 428         if (socket_fd >= 0)
 429                 close_nointr_nofail(socket_fd);
 430
 431         free(packet);
 432         free(socket_name);
 433         free(message);
 434
 435         return r;
 436 }
 437
 438 static int wall_tty_block(void) {
 439         char *p;
 440         int fd, r;
 441         dev_t devnr;
 442
 443         r = get_ctty_devnr(0, &devnr);
 444         if (r < 0)
 445                 return -r;
 446
 447         if (asprintf(&p, "/run/systemd/ask-password-block/%u:%u", major(devnr), minor(devnr)) < 0)
 448                 return -ENOMEM;
 449
 450         mkdir_parents_label(p, 0700);
 451         mkfifo(p, 0600);
 452
 453         fd = open(p, O_RDONLY|O_CLOEXEC|O_NONBLOCK|O_NOCTTY);
 454         free(p);
 455
 456         if (fd < 0)
 457                 return -errno;
 458
 459         return fd;
 460 }
 461
 462 static bool wall_tty_match(const char *path) {
 463         int fd, k;
 464         char *p;
 465         struct stat st;
 466
 467         if (path_is_absolute(path))
 468                 k = lstat(path, &st);
 469         else {
 470                 if (asprintf(&p, "/dev/%s", path) < 0)
 471                         return true;
 472
 473                 k = lstat(p, &st);
 474                 free(p);
 475         }
 476
 477         if (k < 0)
 478                 return true;
 479
 480         if (!S_ISCHR(st.st_mode))
 481                 return true;
 482
 483         /* We use named pipes to ensure that wall messages suggesting
 484          * password entry are not printed over password prompts
 485          * already shown. We use the fact here that opening a pipe in
 486          * non-blocking mode for write-only will succeed only if
 487          * there's some writer behind it. Using pipes has the
 488          * advantage that the block will automatically go away if the
 489          * process dies. */
 490
 491         if (asprintf(&p, "/run/systemd/ask-password-block/%u:%u", major(st.st_rdev), minor(st.st_rdev)) < 0)
 492                 return true;
 493
 494         fd = open(p, O_WRONLY|O_CLOEXEC|O_NONBLOCK|O_NOCTTY);
 495         free(p);
 496
 497         if (fd < 0)
 498                 return true;
 499
 500         /* What, we managed to open the pipe? Then this tty is filtered. */
 501         close_nointr_nofail(fd);
 502         return false;
 503 }
 504
 505 static int show_passwords(void) {
 506         DIR *d;
 507         struct dirent *de;
 508         int r = 0;
 509
 510         if (!(d = opendir("/run/systemd/ask-password"))) {
 511                 if (errno == ENOENT)
 512                         return 0;
 513
 514                 log_error("opendir(): %m");
 515                 return -errno;
 516         }
 517
 518         while ((de = readdir(d))) {
 519                 char *p;
 520                 int q;
 521                 char *wall;
 522
 523                 /* We only support /dev on tmpfs, hence we can rely on
 524                  * d_type to be reliable */
 525
 526                 if (de->d_type != DT_REG)
 527                         continue;
 528
 529                 if (ignore_file(de->d_name))
 530                         continue;
 531
 532                 if (!startswith(de->d_name, "ask."))
 533                         continue;
 534
 535                 if (!(p = strappend("/run/systemd/ask-password/", de->d_name))) {
 536                         log_error("Out of memory");
 537                         r = -ENOMEM;
 538                         goto finish;
 539                 }
 540
 541                 wall = NULL;
 542                 if ((q = parse_password(p, &wall)) < 0)
 543                         r = q;
 544
 545                 free(p);
 546
 547                 if (wall) {
 548                         utmp_wall(wall, wall_tty_match);
 549                         free(wall);
 550                 }
 551         }
 552
 553 finish:
 554         if (d)
 555                 closedir(d);
 556
 557         return r;
 558 }
 559
 560 static int watch_passwords(void) {
 561         enum {
 562                 FD_INOTIFY,
 563                 FD_SIGNAL,
 564                 _FD_MAX
 565         };
 566
 567         int notify = -1, signal_fd = -1, tty_block_fd = -1;
 568         struct pollfd pollfd[_FD_MAX];
 569         sigset_t mask;
 570         int r;
 571
 572         tty_block_fd = wall_tty_block();
 573
 574         mkdir_p_label("/run/systemd/ask-password", 0755);
 575
 576         if ((notify = inotify_init1(IN_CLOEXEC)) < 0) {
 577                 r = -errno;
 578                 goto finish;
 579         }
 580
 581         if (inotify_add_watch(notify, "/run/systemd/ask-password", IN_CLOSE_WRITE|IN_MOVED_TO) < 0) {
 582                 r = -errno;
 583                 goto finish;
 584         }
 585
 586         assert_se(sigemptyset(&mask) == 0);
 587         sigset_add_many(&mask, SIGINT, SIGTERM, -1);
 588         assert_se(sigprocmask(SIG_SETMASK, &mask, NULL) == 0);
 589
 590         if ((signal_fd = signalfd(-1, &mask, SFD_NONBLOCK|SFD_CLOEXEC)) < 0) {
 591                 log_error("signalfd(): %m");
 592                 r = -errno;
 593                 goto finish;
 594         }
 595
 596         zero(pollfd);
 597         pollfd[FD_INOTIFY].fd = notify;
 598         pollfd[FD_INOTIFY].events = POLLIN;
 599         pollfd[FD_SIGNAL].fd = signal_fd;
 600         pollfd[FD_SIGNAL].events = POLLIN;
 601
 602         for (;;) {
 603                 if ((r = show_passwords()) < 0)
 604                         log_error("Failed to show password: %s", strerror(-r));
 605
 606                 if (poll(pollfd, _FD_MAX, -1) < 0) {
 607
 608                         if (errno == EINTR)
 609                                 continue;
 610
 611                         r = -errno;
 612                         goto finish;
 613                 }
 614
 615                 if (pollfd[FD_INOTIFY].revents != 0)
 616                         flush_fd(notify);
 617
 618                 if (pollfd[FD_SIGNAL].revents != 0)
 619                         break;
 620         }
 621
 622         r = 0;
 623
 624 finish:
 625         if (notify >= 0)
 626                 close_nointr_nofail(notify);
 627
 628         if (signal_fd >= 0)
 629                 close_nointr_nofail(signal_fd);
 630
 631         if (tty_block_fd >= 0)
 632                 close_nointr_nofail(tty_block_fd);
 633
 634         return r;
 635 }
 636
 637 static int help(void) {
 638
 639         printf("%s [OPTIONS...]\n\n"
 640                "Process system password requests.\n\n"
 641                "  -h --help     Show this help\n"
 642                "     --version  Show package version\n"
 643                "     --list     Show pending password requests\n"
 644                "     --query    Process pending password requests\n"
 645                "     --watch    Continuously process password requests\n"
 646                "     --wall     Continuously forward password requests to wall\n"
 647                "     --plymouth Ask question with Plymouth instead of on TTY\n"
 648                "     --console  Ask question on /dev/console instead of current TTY\n",
 649                program_invocation_short_name);
 650
 651         return 0;
 652 }
 653
 654 static int parse_argv(int argc, char *argv[]) {
 655
 656         enum {
 657                 ARG_LIST = 0x100,
 658                 ARG_QUERY,
 659                 ARG_WATCH,
 660                 ARG_WALL,
 661                 ARG_PLYMOUTH,
 662                 ARG_CONSOLE,
 663                 ARG_VERSION
 664         };
 665
 666         static const struct option options[] = {
 667                 { "help",     no_argument, NULL, 'h'          },
 668                 { "version",  no_argument, NULL, ARG_VERSION  },
 669                 { "list",     no_argument, NULL, ARG_LIST     },
 670                 { "query",    no_argument, NULL, ARG_QUERY    },
 671                 { "watch",    no_argument, NULL, ARG_WATCH    },
 672                 { "wall",     no_argument, NULL, ARG_WALL     },
 673                 { "plymouth", no_argument, NULL, ARG_PLYMOUTH },
 674                 { "console",  no_argument, NULL, ARG_CONSOLE  },
 675                 { NULL,    0,           NULL, 0               }
 676         };
 677
 678         int c;
 679
 680         assert(argc >= 0);
 681         assert(argv);
 682
 683         while ((c = getopt_long(argc, argv, "h", options, NULL)) >= 0) {
 684
 685                 switch (c) {
 686
 687                 case 'h':
 688                         help();
 689                         return 0;
 690
 691                 case ARG_VERSION:
 692                         puts(PACKAGE_STRING);
 693                         puts(DISTRIBUTION);
 694                         puts(SYSTEMD_FEATURES);
 695                         return 0;
 696
 697                 case ARG_LIST:
 698                         arg_action = ACTION_LIST;
 699                         break;
 700
 701                 case ARG_QUERY:
 702                         arg_action = ACTION_QUERY;
 703                         break;
 704
 705                 case ARG_WATCH:
 706                         arg_action = ACTION_WATCH;
 707                         break;
 708
 709                 case ARG_WALL:
 710                         arg_action = ACTION_WALL;
 711                         break;
 712
 713                 case ARG_PLYMOUTH:
 714                         arg_plymouth = true;
 715                         break;
 716
 717                 case ARG_CONSOLE:
 718                         arg_console = true;
 719                         break;
 720
 721                 case '?':
 722                         return -EINVAL;
 723
 724                 default:
 725                         log_error("Unknown option code %c", c);
 726                         return -EINVAL;
 727                 }
 728         }
 729
 730         if (optind != argc) {
 731                 help();
 732                 return -EINVAL;
 733         }
 734
 735         return 1;
 736 }
 737
 738 int main(int argc, char *argv[]) {
 739         int r;
 740
 741         log_set_target(LOG_TARGET_AUTO);
 742         log_parse_environment();
 743         log_open();
 744
 745         umask(0022);
 746
 747         if ((r = parse_argv(argc, argv)) <= 0)
 748                 goto finish;
 749
 750         if (arg_console) {
 751                 setsid();
 752                 release_terminal();
 753         }
 754
 755         if (arg_action == ACTION_WATCH ||
 756             arg_action == ACTION_WALL)
 757                 r = watch_passwords();
 758         else
 759                 r = show_passwords();
 760
 761         if (r < 0)
 762                 log_error("Error: %s", strerror(-r));
 763
 764 finish:
 765         return r < 0 ? EXIT_FAILURE : EXIT_SUCCESS;
 766 }