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