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