src/shared/ask-password-api.c

   1 /***
   2   This file is part of systemd.
   3
   4   Copyright 2010 Lennart Poettering
   5
   6   systemd is free software; you can redistribute it and/or modify it
   7   under the terms of the GNU Lesser General Public License as published by
   8   the Free Software Foundation; either version 2.1 of the License, or
   9   (at your option) any later version.
  10
  11   systemd is distributed in the hope that it will be useful, but
  12   WITHOUT ANY WARRANTY; without even the implied warranty of
  13   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  14   Lesser General Public License for more details.
  15
  16   You should have received a copy of the GNU Lesser General Public License
  17   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  18 ***/
  19
  20 #include <errno.h>
  21 #include <fcntl.h>
  22 #include <inttypes.h>
  23 #include <limits.h>
  24 #include <poll.h>
  25 #include <signal.h>
  26 #include <stdbool.h>
  27 #include <stddef.h>
  28 #include <stdint.h>
  29 #include <stdio.h>
  30 #include <stdlib.h>
  31 #include <string.h>
  32 #include <sys/inotify.h>
  33 #include <sys/signalfd.h>
  34 #include <sys/socket.h>
  35 #include <sys/stat.h>
  36 #include <sys/time.h>
  37 #include <sys/uio.h>
  38 #include <sys/un.h>
  39 #include <termios.h>
  40 #include <unistd.h>
  41
  42 #include "alloc-util.h"
  43 #include "ask-password-api.h"
  44 #include "fd-util.h"
  45 #include "fileio.h"
  46 #include "formats-util.h"
  47 #include "io-util.h"
  48 #include "log.h"
  49 #include "macro.h"
  50 #include "missing.h"
  51 #include "mkdir.h"
  52 #include "random-util.h"
  53 #include "signal-util.h"
  54 #include "socket-util.h"
  55 #include "string-util.h"
  56 #include "strv.h"
  57 #include "terminal-util.h"
  58 #include "time-util.h"
  59 #include "umask-util.h"
  60 #include "utf8.h"
  61 #include "util.h"
  62
  63 #define KEYRING_TIMEOUT_USEC ((5 * USEC_PER_MINUTE) / 2)
  64
  65 static int lookup_key(const char *keyname, key_serial_t *ret) {
  66         key_serial_t serial;
  67
  68         assert(keyname);
  69         assert(ret);
  70
  71         serial = request_key("user", keyname, NULL, 0);
  72         if (serial == -1)
  73                 return negative_errno();
  74
  75         *ret = serial;
  76         return 0;
  77 }
  78
  79 static int retrieve_key(key_serial_t serial, char ***ret) {
  80         _cleanup_free_ char *p = NULL;
  81         long m = 100, n;
  82         char **l;
  83
  84         assert(ret);
  85
  86         for (;;) {
  87                 p = new(char, m);
  88                 if (!p)
  89                         return -ENOMEM;
  90
  91                 n = keyctl(KEYCTL_READ, (unsigned long) serial, (unsigned long) p, (unsigned long) m, 0);
  92                 if (n < 0)
  93                         return -errno;
  94
  95                 if (n < m)
  96                         break;
  97
  98                 memory_erase(p, n);
  99                 free(p);
 100                 m *= 2;
 101         }
 102
 103         l = strv_parse_nulstr(p, n);
 104         if (!l)
 105                 return -ENOMEM;
 106
 107         memory_erase(p, n);
 108
 109         *ret = l;
 110         return 0;
 111 }
 112
 113 static int add_to_keyring(const char *keyname, AskPasswordFlags flags, char **passwords) {
 114         _cleanup_strv_free_erase_ char **l = NULL;
 115         _cleanup_free_ char *p = NULL;
 116         key_serial_t serial;
 117         size_t n;
 118         int r;
 119
 120         assert(keyname);
 121         assert(passwords);
 122
 123         if (!(flags & ASK_PASSWORD_PUSH_CACHE))
 124                 return 0;
 125
 126         r = lookup_key(keyname, &serial);
 127         if (r >= 0) {
 128                 r = retrieve_key(serial, &l);
 129                 if (r < 0)
 130                         return r;
 131         } else if (r != -ENOKEY)
 132                 return r;
 133
 134         r = strv_extend_strv(&l, passwords, true);
 135         if (r <= 0)
 136                 return r;
 137
 138         r = strv_make_nulstr(l, &p, &n);
 139         if (r < 0)
 140                 return r;
 141
 142         /* Truncate trailing NUL */
 143         assert(n > 0);
 144         assert(p[n-1] == 0);
 145
 146         serial = add_key("user", keyname, p, n-1, KEY_SPEC_USER_KEYRING);
 147         memory_erase(p, n);
 148         if (serial == -1)
 149                 return -errno;
 150
 151         if (keyctl(KEYCTL_SET_TIMEOUT,
 152                    (unsigned long) serial,
 153                    (unsigned long) DIV_ROUND_UP(KEYRING_TIMEOUT_USEC, USEC_PER_SEC), 0, 0) < 0)
 154                 log_debug_errno(errno, "Failed to adjust timeout: %m");
 155
 156         log_debug("Added key to keyring as %" PRIi32 ".", serial);
 157
 158         return 1;
 159 }
 160
 161 static int add_to_keyring_and_log(const char *keyname, AskPasswordFlags flags, char **passwords) {
 162         int r;
 163
 164         assert(keyname);
 165         assert(passwords);
 166
 167         r = add_to_keyring(keyname, flags, passwords);
 168         if (r < 0)
 169                 return log_debug_errno(r, "Failed to add password to keyring: %m");
 170
 171         return 0;
 172 }
 173
 174 int ask_password_keyring(const char *keyname, AskPasswordFlags flags, char ***ret) {
 175
 176         key_serial_t serial;
 177         int r;
 178
 179         assert(keyname);
 180         assert(ret);
 181
 182         if (!(flags & ASK_PASSWORD_ACCEPT_CACHED))
 183                 return -EUNATCH;
 184
 185         r = lookup_key(keyname, &serial);
 186         if (r == -ENOSYS) /* when retrieving the distinction doesn't matter */
 187                 return -ENOKEY;
 188         if (r < 0)
 189                 return r;
 190
 191         return retrieve_key(serial, ret);
 192 }
 193
 194 static void backspace_chars(int ttyfd, size_t p) {
 195
 196         if (ttyfd < 0)
 197                 return;
 198
 199         while (p > 0) {
 200                 p--;
 201
 202                 loop_write(ttyfd, "\b \b", 3, false);
 203         }
 204 }
 205
 206 int ask_password_tty(
 207                 const char *message,
 208                 const char *keyname,
 209                 usec_t until,
 210                 AskPasswordFlags flags,
 211                 const char *flag_file,
 212                 char **ret) {
 213
 214         struct termios old_termios, new_termios;
 215         char passphrase[LINE_MAX + 1] = {}, *x;
 216         size_t p = 0, codepoint = 0;
 217         int r;
 218         _cleanup_close_ int ttyfd = -1, notify = -1;
 219         struct pollfd pollfd[2];
 220         bool reset_tty = false;
 221         bool dirty = false;
 222         enum {
 223                 POLL_TTY,
 224                 POLL_INOTIFY
 225         };
 226
 227         assert(ret);
 228
 229         if (flags & ASK_PASSWORD_NO_TTY)
 230                 return -EUNATCH;
 231
 232         if (!message)
 233                 message = "Password:";
 234
 235         if (flag_file) {
 236                 notify = inotify_init1(IN_CLOEXEC|IN_NONBLOCK);
 237                 if (notify < 0) {
 238                         r = -errno;
 239                         goto finish;
 240                 }
 241
 242                 if (inotify_add_watch(notify, flag_file, IN_ATTRIB /* for the link count */) < 0) {
 243                         r = -errno;
 244                         goto finish;
 245                 }
 246         }
 247
 248         ttyfd = open("/dev/tty", O_RDWR|O_NOCTTY|O_CLOEXEC);
 249         if (ttyfd >= 0) {
 250
 251                 if (tcgetattr(ttyfd, &old_termios) < 0) {
 252                         r = -errno;
 253                         goto finish;
 254                 }
 255
 256                 if (colors_enabled())
 257                         loop_write(ttyfd, ANSI_HIGHLIGHT, strlen(ANSI_HIGHLIGHT), false);
 258                 loop_write(ttyfd, message, strlen(message), false);
 259                 loop_write(ttyfd, " ", 1, false);
 260                 if (colors_enabled())
 261                         loop_write(ttyfd, ANSI_NORMAL, strlen(ANSI_NORMAL), false);
 262
 263                 new_termios = old_termios;
 264                 new_termios.c_lflag &= ~(ICANON|ECHO);
 265                 new_termios.c_cc[VMIN] = 1;
 266                 new_termios.c_cc[VTIME] = 0;
 267
 268                 if (tcsetattr(ttyfd, TCSADRAIN, &new_termios) < 0) {
 269                         r = -errno;
 270                         goto finish;
 271                 }
 272
 273                 reset_tty = true;
 274         }
 275
 276         zero(pollfd);
 277         pollfd[POLL_TTY].fd = ttyfd >= 0 ? ttyfd : STDIN_FILENO;
 278         pollfd[POLL_TTY].events = POLLIN;
 279         pollfd[POLL_INOTIFY].fd = notify;
 280         pollfd[POLL_INOTIFY].events = POLLIN;
 281
 282         for (;;) {
 283                 char c;
 284                 int sleep_for = -1, k;
 285                 ssize_t n;
 286
 287                 if (until > 0) {
 288                         usec_t y;
 289
 290                         y = now(CLOCK_MONOTONIC);
 291
 292                         if (y > until) {
 293                                 r = -ETIME;
 294                                 goto finish;
 295                         }
 296
 297                         sleep_for = (int) ((until - y) / USEC_PER_MSEC);
 298                 }
 299
 300                 if (flag_file)
 301                         if (access(flag_file, F_OK) < 0) {
 302                                 r = -errno;
 303                                 goto finish;
 304                         }
 305
 306                 k = poll(pollfd, notify >= 0 ? 2 : 1, sleep_for);
 307                 if (k < 0) {
 308                         if (errno == EINTR)
 309                                 continue;
 310
 311                         r = -errno;
 312                         goto finish;
 313                 } else if (k == 0) {
 314                         r = -ETIME;
 315                         goto finish;
 316                 }
 317
 318                 if (notify >= 0 && pollfd[POLL_INOTIFY].revents != 0)
 319                         flush_fd(notify);
 320
 321                 if (pollfd[POLL_TTY].revents == 0)
 322                         continue;
 323
 324                 n = read(ttyfd >= 0 ? ttyfd : STDIN_FILENO, &c, 1);
 325                 if (n < 0) {
 326                         if (errno == EINTR || errno == EAGAIN)
 327                                 continue;
 328
 329                         r = -errno;
 330                         goto finish;
 331
 332                 } else if (n == 0)
 333                         break;
 334
 335                 if (c == '\n')
 336                         break;
 337                 else if (c == 21) { /* C-u */
 338
 339                         if (!(flags & ASK_PASSWORD_SILENT))
 340                                 backspace_chars(ttyfd, p);
 341                         p = 0;
 342
 343                 } else if (c == '\b' || c == 127) {
 344
 345                         if (p > 0) {
 346
 347                                 if (!(flags & ASK_PASSWORD_SILENT))
 348                                         backspace_chars(ttyfd, 1);
 349
 350                                 p--;
 351                         } else if (!dirty && !(flags & ASK_PASSWORD_SILENT)) {
 352
 353                                 flags |= ASK_PASSWORD_SILENT;
 354
 355                                 /* There are two ways to enter silent
 356                                  * mode. Either by pressing backspace
 357                                  * as first key (and only as first
 358                                  * key), or ... */
 359                                 if (ttyfd >= 0)
 360                                         loop_write(ttyfd, "(no echo) ", 10, false);
 361
 362                         } else if (ttyfd >= 0)
 363                                 loop_write(ttyfd, "\a", 1, false);
 364
 365                 } else if (c == '\t' && !(flags & ASK_PASSWORD_SILENT)) {
 366
 367                         backspace_chars(ttyfd, p);
 368                         flags |= ASK_PASSWORD_SILENT;
 369
 370                         /* ... or by pressing TAB at any time. */
 371
 372                         if (ttyfd >= 0)
 373                                 loop_write(ttyfd, "(no echo) ", 10, false);
 374                 } else {
 375                         if (p >= sizeof(passphrase)-1) {
 376                                 loop_write(ttyfd, "\a", 1, false);
 377                                 continue;
 378                         }
 379
 380                         passphrase[p++] = c;
 381
 382                         if (!(flags & ASK_PASSWORD_SILENT) && ttyfd >= 0) {
 383                                 n = utf8_encoded_valid_unichar(passphrase + codepoint);
 384                                 if (n >= 0) {
 385                                         codepoint = p;
 386                                         loop_write(ttyfd, (flags & ASK_PASSWORD_ECHO) ? &c : "*", 1, false);
 387                                 }
 388                         }
 389
 390                         dirty = true;
 391                 }
 392
 393                 c = 'x';
 394         }
 395
 396         x = strndup(passphrase, p);
 397         memory_erase(passphrase, p);
 398         if (!x) {
 399                 r = -ENOMEM;
 400                 goto finish;
 401         }
 402
 403         if (keyname)
 404                 (void) add_to_keyring_and_log(keyname, flags, STRV_MAKE(x));
 405
 406         *ret = x;
 407         r = 0;
 408
 409 finish:
 410         if (ttyfd >= 0 && reset_tty) {
 411                 loop_write(ttyfd, "\n", 1, false);
 412                 tcsetattr(ttyfd, TCSADRAIN, &old_termios);
 413         }
 414
 415         return r;
 416 }
 417
 418 static int create_socket(char **name) {
 419         union sockaddr_union sa = {
 420                 .un.sun_family = AF_UNIX,
 421         };
 422         _cleanup_close_ int fd = -1;
 423         static const int one = 1;
 424         char *c;
 425         int r;
 426
 427         assert(name);
 428
 429         fd = socket(AF_UNIX, SOCK_DGRAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0);
 430         if (fd < 0)
 431                 return -errno;
 432
 433         snprintf(sa.un.sun_path, sizeof(sa.un.sun_path)-1, "/run/systemd/ask-password/sck.%" PRIx64, random_u64());
 434
 435         RUN_WITH_UMASK(0177) {
 436                 if (bind(fd, &sa.sa, SOCKADDR_UN_LEN(sa.un)) < 0)
 437                         return -errno;
 438         }
 439
 440         if (setsockopt(fd, SOL_SOCKET, SO_PASSCRED, &one, sizeof(one)) < 0)
 441                 return -errno;
 442
 443         c = strdup(sa.un.sun_path);
 444         if (!c)
 445                 return -ENOMEM;
 446
 447         *name = c;
 448
 449         r = fd;
 450         fd = -1;
 451
 452         return r;
 453 }
 454
 455 int ask_password_agent(
 456                 const char *message,
 457                 const char *icon,
 458                 const char *id,
 459                 const char *keyname,
 460                 usec_t until,
 461                 AskPasswordFlags flags,
 462                 char ***ret) {
 463
 464         enum {
 465                 FD_SOCKET,
 466                 FD_SIGNAL,
 467                 _FD_MAX
 468         };
 469
 470         _cleanup_close_ int socket_fd = -1, signal_fd = -1, fd = -1;
 471         char temp[] = "/run/systemd/ask-password/tmp.XXXXXX";
 472         char final[sizeof(temp)] = "";
 473         _cleanup_free_ char *socket_name = NULL;
 474         _cleanup_strv_free_ char **l = NULL;
 475         _cleanup_fclose_ FILE *f = NULL;
 476         struct pollfd pollfd[_FD_MAX];
 477         sigset_t mask, oldmask;
 478         int r;
 479
 480         assert(ret);
 481
 482         if (flags & ASK_PASSWORD_NO_AGENT)
 483                 return -EUNATCH;
 484
 485         assert_se(sigemptyset(&mask) >= 0);
 486         assert_se(sigset_add_many(&mask, SIGINT, SIGTERM, -1) >= 0);
 487         assert_se(sigprocmask(SIG_BLOCK, &mask, &oldmask) >= 0);
 488
 489         (void) mkdir_p_label("/run/systemd/ask-password", 0755);
 490
 491         fd = mkostemp_safe(temp, O_WRONLY|O_CLOEXEC);
 492         if (fd < 0) {
 493                 r = fd;
 494                 goto finish;
 495         }
 496
 497         (void) fchmod(fd, 0644);
 498
 499         f = fdopen(fd, "w");
 500         if (!f) {
 501                 r = -errno;
 502                 goto finish;
 503         }
 504
 505         fd = -1;
 506
 507         signal_fd = signalfd(-1, &mask, SFD_NONBLOCK|SFD_CLOEXEC);
 508         if (signal_fd < 0) {
 509                 r = -errno;
 510                 goto finish;
 511         }
 512
 513         socket_fd = create_socket(&socket_name);
 514         if (socket_fd < 0) {
 515                 r = socket_fd;
 516                 goto finish;
 517         }
 518
 519         fprintf(f,
 520                 "[Ask]\n"
 521                 "PID="PID_FMT"\n"
 522                 "Socket=%s\n"
 523                 "AcceptCached=%i\n"
 524                 "Echo=%i\n"
 525                 "NotAfter="USEC_FMT"\n",
 526                 getpid(),
 527                 socket_name,
 528                 (flags & ASK_PASSWORD_ACCEPT_CACHED) ? 1 : 0,
 529                 (flags & ASK_PASSWORD_ECHO) ? 1 : 0,
 530                 until);
 531
 532         if (message)
 533                 fprintf(f, "Message=%s\n", message);
 534
 535         if (icon)
 536                 fprintf(f, "Icon=%s\n", icon);
 537
 538         if (id)
 539                 fprintf(f, "Id=%s\n", id);
 540
 541         r = fflush_and_check(f);
 542         if (r < 0)
 543                 goto finish;
 544
 545         memcpy(final, temp, sizeof(temp));
 546
 547         final[sizeof(final)-11] = 'a';
 548         final[sizeof(final)-10] = 's';
 549         final[sizeof(final)-9] = 'k';
 550
 551         if (rename(temp, final) < 0) {
 552                 r = -errno;
 553                 goto finish;
 554         }
 555
 556         zero(pollfd);
 557         pollfd[FD_SOCKET].fd = socket_fd;
 558         pollfd[FD_SOCKET].events = POLLIN;
 559         pollfd[FD_SIGNAL].fd = signal_fd;
 560         pollfd[FD_SIGNAL].events = POLLIN;
 561
 562         for (;;) {
 563                 char passphrase[LINE_MAX+1];
 564                 struct msghdr msghdr;
 565                 struct iovec iovec;
 566                 struct ucred *ucred;
 567                 union {
 568                         struct cmsghdr cmsghdr;
 569                         uint8_t buf[CMSG_SPACE(sizeof(struct ucred))];
 570                 } control;
 571                 ssize_t n;
 572                 int k;
 573                 usec_t t;
 574
 575                 t = now(CLOCK_MONOTONIC);
 576
 577                 if (until > 0 && until <= t) {
 578                         r = -ETIME;
 579                         goto finish;
 580                 }
 581
 582                 k = poll(pollfd, _FD_MAX, until > 0 ? (int) ((until-t)/USEC_PER_MSEC) : -1);
 583                 if (k < 0) {
 584                         if (errno == EINTR)
 585                                 continue;
 586
 587                         r = -errno;
 588                         goto finish;
 589                 }
 590
 591                 if (k <= 0) {
 592                         r = -ETIME;
 593                         goto finish;
 594                 }
 595
 596                 if (pollfd[FD_SIGNAL].revents & POLLIN) {
 597                         r = -EINTR;
 598                         goto finish;
 599                 }
 600
 601                 if (pollfd[FD_SOCKET].revents != POLLIN) {
 602                         r = -EIO;
 603                         goto finish;
 604                 }
 605
 606                 zero(iovec);
 607                 iovec.iov_base = passphrase;
 608                 iovec.iov_len = sizeof(passphrase);
 609
 610                 zero(control);
 611                 zero(msghdr);
 612                 msghdr.msg_iov = &iovec;
 613                 msghdr.msg_iovlen = 1;
 614                 msghdr.msg_control = &control;
 615                 msghdr.msg_controllen = sizeof(control);
 616
 617                 n = recvmsg(socket_fd, &msghdr, 0);
 618                 if (n < 0) {
 619                         if (errno == EAGAIN ||
 620                             errno == EINTR)
 621                                 continue;
 622
 623                         r = -errno;
 624                         goto finish;
 625                 }
 626
 627                 cmsg_close_all(&msghdr);
 628
 629                 if (n <= 0) {
 630                         log_debug("Message too short");
 631                         continue;
 632                 }
 633
 634                 if (msghdr.msg_controllen < CMSG_LEN(sizeof(struct ucred)) ||
 635                     control.cmsghdr.cmsg_level != SOL_SOCKET ||
 636                     control.cmsghdr.cmsg_type != SCM_CREDENTIALS ||
 637                     control.cmsghdr.cmsg_len != CMSG_LEN(sizeof(struct ucred))) {
 638                         log_debug("Received message without credentials. Ignoring.");
 639                         continue;
 640                 }
 641
 642                 ucred = (struct ucred*) CMSG_DATA(&control.cmsghdr);
 643                 if (ucred->uid != 0) {
 644                         log_debug("Got request from unprivileged user. Ignoring.");
 645                         continue;
 646                 }
 647
 648                 if (passphrase[0] == '+') {
 649                         /* An empty message refers to the empty password */
 650                         if (n == 1)
 651                                 l = strv_new("", NULL);
 652                         else
 653                                 l = strv_parse_nulstr(passphrase+1, n-1);
 654                         memory_erase(passphrase, n);
 655                         if (!l) {
 656                                 r = -ENOMEM;
 657                                 goto finish;
 658                         }
 659
 660                         if (strv_length(l) <= 0) {
 661                                 l = strv_free(l);
 662                                 log_debug("Invalid packet");
 663                                 continue;
 664                         }
 665
 666                         break;
 667                 }
 668
 669                 if (passphrase[0] == '-') {
 670                         r = -ECANCELED;
 671                         goto finish;
 672                 }
 673
 674                 log_debug("Invalid packet");
 675         }
 676
 677         if (keyname)
 678                 (void) add_to_keyring_and_log(keyname, flags, l);
 679
 680         *ret = l;
 681         l = NULL;
 682         r = 0;
 683
 684 finish:
 685         if (socket_name)
 686                 (void) unlink(socket_name);
 687
 688         (void) unlink(temp);
 689
 690         if (final[0])
 691                 (void) unlink(final);
 692
 693         assert_se(sigprocmask(SIG_SETMASK, &oldmask, NULL) == 0);
 694         return r;
 695 }
 696
 697 int ask_password_auto(
 698                 const char *message,
 699                 const char *icon,
 700                 const char *id,
 701                 const char *keyname,
 702                 usec_t until,
 703                 AskPasswordFlags flags,
 704                 char ***ret) {
 705
 706         int r;
 707
 708         assert(ret);
 709
 710         if ((flags & ASK_PASSWORD_ACCEPT_CACHED) && keyname) {
 711                 r = ask_password_keyring(keyname, flags, ret);
 712                 if (r != -ENOKEY)
 713                         return r;
 714         }
 715
 716         if (!(flags & ASK_PASSWORD_NO_TTY) && isatty(STDIN_FILENO)) {
 717                 char *s = NULL, **l = NULL;
 718
 719                 r = ask_password_tty(message, keyname, until, flags, NULL, &s);
 720                 if (r < 0)
 721                         return r;
 722
 723                 r = strv_push(&l, s);
 724                 if (r < 0) {
 725                         string_erase(s);
 726                         free(s);
 727                         return -ENOMEM;
 728                 }
 729
 730                 *ret = l;
 731                 return 0;
 732         }
 733
 734         if (!(flags & ASK_PASSWORD_NO_AGENT))
 735                 return ask_password_agent(message, icon, id, keyname, until, flags, ret);
 736
 737         return -EUNATCH;
 738 }