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