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("FIALED 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         const char *t;
 357         int fd;
 358
 359         if (!(t = ttyname(STDIN_FILENO)))
 360                 return -errno;
 361
 362         if (asprintf(&p, "/dev/.systemd/ask-password-block/%s", file_name_from_path(t)) < 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;
 379         char *p;
 380
 381         /* We use named pipes to ensure that wall messages suggesting
 382          * password entry are not printed over password prompts
 383          * already shown. We use the fact here that opening a pipe in
 384          * non-blocking mode for write-only will succeed only if
 385          * there's some writer behind it. Using pipes has the
 386          * advantage that the block will automatically go away if the
 387          * process dies. */
 388
 389         if (asprintf(&p, "/dev/.systemd/ask-password-block/%s", file_name_from_path(path)) < 0)
 390                 return true;
 391
 392         fd = open(p, O_WRONLY|O_CLOEXEC|O_NONBLOCK|O_NOCTTY);
 393         free(p);
 394
 395         if (fd < 0)
 396                 return true;
 397
 398         /* What, we managed to open the pipe? Then this tty is filtered. */
 399         close_nointr_nofail(fd);
 400         return false;
 401 }
 402
 403 static int show_passwords(void) {
 404         DIR *d;
 405         struct dirent *de;
 406         int r = 0;
 407
 408         if (!(d = opendir("/dev/.systemd/ask-password"))) {
 409                 if (errno == ENOENT)
 410                         return 0;
 411
 412                 log_error("opendir(): %m");
 413                 return -errno;
 414         }
 415
 416         while ((de = readdir(d))) {
 417                 char *p;
 418                 int q;
 419                 char *wall;
 420
 421                 if (de->d_type != DT_REG)
 422                         continue;
 423
 424                 if (ignore_file(de->d_name))
 425                         continue;
 426
 427                 if (!startswith(de->d_name, "ask."))
 428                         continue;
 429
 430                 if (!(p = strappend("/dev/.systemd/ask-password/", de->d_name))) {
 431                         log_error("Out of memory");
 432                         r = -ENOMEM;
 433                         goto finish;
 434                 }
 435
 436                 wall = NULL;
 437                 if ((q = parse_password(p, &wall)) < 0)
 438                         r = q;
 439
 440                 free(p);
 441
 442                 if (wall) {
 443                         utmp_wall(wall, wall_tty_match);
 444                         free(wall);
 445                 }
 446         }
 447
 448 finish:
 449         if (d)
 450                 closedir(d);
 451
 452         return r;
 453 }
 454
 455 static int watch_passwords(void) {
 456         enum {
 457                 FD_INOTIFY,
 458                 FD_SIGNAL,
 459                 _FD_MAX
 460         };
 461
 462         int notify = -1, signal_fd = -1, tty_block_fd = -1;
 463         struct pollfd pollfd[_FD_MAX];
 464         sigset_t mask;
 465         int r;
 466
 467         tty_block_fd = wall_tty_block();
 468
 469         mkdir_p("/dev/.systemd/ask-password", 0755);
 470
 471         if ((notify = inotify_init1(IN_CLOEXEC)) < 0) {
 472                 r = -errno;
 473                 goto finish;
 474         }
 475
 476         if (inotify_add_watch(notify, "/dev/.systemd/ask-password", IN_CLOSE_WRITE|IN_MOVED_TO) < 0) {
 477                 r = -errno;
 478                 goto finish;
 479         }
 480
 481         assert_se(sigemptyset(&mask) == 0);
 482         sigset_add_many(&mask, SIGINT, SIGTERM, -1);
 483         assert_se(sigprocmask(SIG_SETMASK, &mask, NULL) == 0);
 484
 485         if ((signal_fd = signalfd(-1, &mask, SFD_NONBLOCK|SFD_CLOEXEC)) < 0) {
 486                 log_error("signalfd(): %m");
 487                 r = -errno;
 488                 goto finish;
 489         }
 490
 491         zero(pollfd);
 492         pollfd[FD_INOTIFY].fd = notify;
 493         pollfd[FD_INOTIFY].events = POLLIN;
 494         pollfd[FD_SIGNAL].fd = signal_fd;
 495         pollfd[FD_SIGNAL].events = POLLIN;
 496
 497         for (;;) {
 498                 if ((r = show_passwords()) < 0)
 499                         log_error("Failed to show password: %s", strerror(-r));
 500
 501                 if (poll(pollfd, _FD_MAX, -1) < 0) {
 502
 503                         if (errno == EINTR)
 504                                 continue;
 505
 506                         r = -errno;
 507                         goto finish;
 508                 }
 509
 510                 if (pollfd[FD_INOTIFY].revents != 0)
 511                         flush_fd(notify);
 512
 513                 if (pollfd[FD_SIGNAL].revents != 0)
 514                         break;
 515         }
 516
 517         r = 0;
 518
 519 finish:
 520         if (notify >= 0)
 521                 close_nointr_nofail(notify);
 522
 523         if (signal_fd >= 0)
 524                 close_nointr_nofail(signal_fd);
 525
 526         if (tty_block_fd >= 0)
 527                 close_nointr_nofail(tty_block_fd);
 528
 529         return r;
 530 }
 531
 532 static int help(void) {
 533
 534         printf("%s [OPTIONS...]\n\n"
 535                "Process system password requests.\n\n"
 536                "  -h --help     Show this help\n"
 537                "     --list     Show pending password requests\n"
 538                "     --query    Process pending password requests\n"
 539                "     --watch    Continously process password requests\n"
 540                "     --wall     Continously forward password requests to wall\n"
 541                "     --plymouth Ask question with Plymouth instead of on TTY\n"
 542                "     --console  Ask question on /dev/console instead of current TTY\n",
 543                program_invocation_short_name);
 544
 545         return 0;
 546 }
 547
 548 static int parse_argv(int argc, char *argv[]) {
 549
 550         enum {
 551                 ARG_LIST = 0x100,
 552                 ARG_QUERY,
 553                 ARG_WATCH,
 554                 ARG_WALL,
 555                 ARG_PLYMOUTH,
 556                 ARG_CONSOLE
 557         };
 558
 559         static const struct option options[] = {
 560                 { "help",     no_argument, NULL, 'h'          },
 561                 { "list",     no_argument, NULL, ARG_LIST     },
 562                 { "query",    no_argument, NULL, ARG_QUERY    },
 563                 { "watch",    no_argument, NULL, ARG_WATCH    },
 564                 { "wall",     no_argument, NULL, ARG_WALL     },
 565                 { "plymouth", no_argument, NULL, ARG_PLYMOUTH },
 566                 { "console",  no_argument, NULL, ARG_CONSOLE  },
 567                 { NULL,    0,           NULL, 0               }
 568         };
 569
 570         int c;
 571
 572         assert(argc >= 0);
 573         assert(argv);
 574
 575         while ((c = getopt_long(argc, argv, "h", options, NULL)) >= 0) {
 576
 577                 switch (c) {
 578
 579                 case 'h':
 580                         help();
 581                         return 0;
 582
 583                 case ARG_LIST:
 584                         arg_action = ACTION_LIST;
 585                         break;
 586
 587                 case ARG_QUERY:
 588                         arg_action = ACTION_QUERY;
 589                         break;
 590
 591                 case ARG_WATCH:
 592                         arg_action = ACTION_WATCH;
 593                         break;
 594
 595                 case ARG_WALL:
 596                         arg_action = ACTION_WALL;
 597                         break;
 598
 599                 case ARG_PLYMOUTH:
 600                         arg_plymouth = true;
 601                         break;
 602
 603                 case ARG_CONSOLE:
 604                         arg_console = true;
 605                         break;
 606
 607                 case '?':
 608                         return -EINVAL;
 609
 610                 default:
 611                         log_error("Unknown option code %c", c);
 612                         return -EINVAL;
 613                 }
 614         }
 615
 616         if (optind != argc) {
 617                 help();
 618                 return -EINVAL;
 619         }
 620
 621         return 1;
 622 }
 623
 624 int main(int argc, char *argv[]) {
 625         int r;
 626
 627         log_parse_environment();
 628         log_open();
 629
 630         if ((r = parse_argv(argc, argv)) <= 0)
 631                 goto finish;
 632
 633         if (arg_console) {
 634                 setsid();
 635                 release_terminal();
 636         }
 637
 638         if (arg_action == ACTION_WATCH ||
 639             arg_action == ACTION_WALL)
 640                 r = watch_passwords();
 641         else
 642                 r = show_passwords();
 643
 644         if (r < 0)
 645                 log_error("Error: %s", strerror(-r));
 646
 647 finish:
 648         return r < 0 ? EXIT_FAILURE : EXIT_SUCCESS;
 649 }