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                 loop_write(ttyfd, ANSI_HIGHLIGHT, strlen(ANSI_HIGHLIGHT), false);
 257                 loop_write(ttyfd, message, strlen(message), false);
 258                 loop_write(ttyfd, " ", 1, false);
 259                 loop_write(ttyfd, ANSI_NORMAL, strlen(ANSI_NORMAL), false);
 260
 261                 new_termios = old_termios;
 262                 new_termios.c_lflag &= ~(ICANON|ECHO);
 263                 new_termios.c_cc[VMIN] = 1;
 264                 new_termios.c_cc[VTIME] = 0;
 265
 266                 if (tcsetattr(ttyfd, TCSADRAIN, &new_termios) < 0) {
 267                         r = -errno;
 268                         goto finish;
 269                 }
 270
 271                 reset_tty = true;
 272         }
 273
 274         zero(pollfd);
 275         pollfd[POLL_TTY].fd = ttyfd >= 0 ? ttyfd : STDIN_FILENO;
 276         pollfd[POLL_TTY].events = POLLIN;
 277         pollfd[POLL_INOTIFY].fd = notify;
 278         pollfd[POLL_INOTIFY].events = POLLIN;
 279
 280         for (;;) {
 281                 char c;
 282                 int sleep_for = -1, k;
 283                 ssize_t n;
 284
 285                 if (until > 0) {
 286                         usec_t y;
 287
 288                         y = now(CLOCK_MONOTONIC);
 289
 290                         if (y > until) {
 291                                 r = -ETIME;
 292                                 goto finish;
 293                         }
 294
 295                         sleep_for = (int) ((until - y) / USEC_PER_MSEC);
 296                 }
 297
 298                 if (flag_file)
 299                         if (access(flag_file, F_OK) < 0) {
 300                                 r = -errno;
 301                                 goto finish;
 302                         }
 303
 304                 k = poll(pollfd, notify >= 0 ? 2 : 1, sleep_for);
 305                 if (k < 0) {
 306                         if (errno == EINTR)
 307                                 continue;
 308
 309                         r = -errno;
 310                         goto finish;
 311                 } else if (k == 0) {
 312                         r = -ETIME;
 313                         goto finish;
 314                 }
 315
 316                 if (notify >= 0 && pollfd[POLL_INOTIFY].revents != 0)
 317                         flush_fd(notify);
 318
 319                 if (pollfd[POLL_TTY].revents == 0)
 320                         continue;
 321
 322                 n = read(ttyfd >= 0 ? ttyfd : STDIN_FILENO, &c, 1);
 323                 if (n < 0) {
 324                         if (errno == EINTR || errno == EAGAIN)
 325                                 continue;
 326
 327                         r = -errno;
 328                         goto finish;
 329
 330                 } else if (n == 0)
 331                         break;
 332
 333                 if (c == '\n')
 334                         break;
 335                 else if (c == 21) { /* C-u */
 336
 337                         if (!(flags & ASK_PASSWORD_SILENT))
 338                                 backspace_chars(ttyfd, p);
 339                         p = 0;
 340
 341                 } else if (c == '\b' || c == 127) {
 342
 343                         if (p > 0) {
 344
 345                                 if (!(flags & ASK_PASSWORD_SILENT))
 346                                         backspace_chars(ttyfd, 1);
 347
 348                                 p--;
 349                         } else if (!dirty && !(flags & ASK_PASSWORD_SILENT)) {
 350
 351                                 flags |= ASK_PASSWORD_SILENT;
 352
 353                                 /* There are two ways to enter silent
 354                                  * mode. Either by pressing backspace
 355                                  * as first key (and only as first
 356                                  * key), or ... */
 357                                 if (ttyfd >= 0)
 358                                         loop_write(ttyfd, "(no echo) ", 10, false);
 359
 360                         } else if (ttyfd >= 0)
 361                                 loop_write(ttyfd, "\a", 1, false);
 362
 363                 } else if (c == '\t' && !(flags & ASK_PASSWORD_SILENT)) {
 364
 365                         backspace_chars(ttyfd, p);
 366                         flags |= ASK_PASSWORD_SILENT;
 367
 368                         /* ... or by pressing TAB at any time. */
 369
 370                         if (ttyfd >= 0)
 371                                 loop_write(ttyfd, "(no echo) ", 10, false);
 372                 } else {
 373                         if (p >= sizeof(passphrase)-1) {
 374                                 loop_write(ttyfd, "\a", 1, false);
 375                                 continue;
 376                         }
 377
 378                         passphrase[p++] = c;
 379
 380                         if (!(flags & ASK_PASSWORD_SILENT) && ttyfd >= 0) {
 381                                 n = utf8_encoded_valid_unichar(passphrase + codepoint);
 382                                 if (n >= 0) {
 383                                         codepoint = p;
 384                                         loop_write(ttyfd, (flags & ASK_PASSWORD_ECHO) ? &c : "*", 1, false);
 385                                 }
 386                         }
 387
 388                         dirty = true;
 389                 }
 390
 391                 c = 'x';
 392         }
 393
 394         x = strndup(passphrase, p);
 395         memory_erase(passphrase, p);
 396         if (!x) {
 397                 r = -ENOMEM;
 398                 goto finish;
 399         }
 400
 401         if (keyname)
 402                 (void) add_to_keyring_and_log(keyname, flags, STRV_MAKE(x));
 403
 404         *ret = x;
 405         r = 0;
 406
 407 finish:
 408         if (ttyfd >= 0 && reset_tty) {
 409                 loop_write(ttyfd, "\n", 1, false);
 410                 tcsetattr(ttyfd, TCSADRAIN, &old_termios);
 411         }
 412
 413         return r;
 414 }
 415
 416 static int create_socket(char **name) {
 417         union sockaddr_union sa = {
 418                 .un.sun_family = AF_UNIX,
 419         };
 420         _cleanup_close_ int fd = -1;
 421         static const int one = 1;
 422         char *c;
 423         int r;
 424
 425         assert(name);
 426
 427         fd = socket(AF_UNIX, SOCK_DGRAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0);
 428         if (fd < 0)
 429                 return -errno;
 430
 431         snprintf(sa.un.sun_path, sizeof(sa.un.sun_path)-1, "/run/systemd/ask-password/sck.%" PRIx64, random_u64());
 432
 433         RUN_WITH_UMASK(0177) {
 434                 if (bind(fd, &sa.sa, offsetof(struct sockaddr_un, sun_path) + strlen(sa.un.sun_path)) < 0)
 435                         return -errno;
 436         }
 437
 438         if (setsockopt(fd, SOL_SOCKET, SO_PASSCRED, &one, sizeof(one)) < 0)
 439                 return -errno;
 440
 441         c = strdup(sa.un.sun_path);
 442         if (!c)
 443                 return -ENOMEM;
 444
 445         *name = c;
 446
 447         r = fd;
 448         fd = -1;
 449
 450         return r;
 451 }
 452
 453 int ask_password_agent(
 454                 const char *message,
 455                 const char *icon,
 456                 const char *id,
 457                 const char *keyname,
 458                 usec_t until,
 459                 AskPasswordFlags flags,
 460                 char ***ret) {
 461
 462         enum {
 463                 FD_SOCKET,
 464                 FD_SIGNAL,
 465                 _FD_MAX
 466         };
 467
 468         _cleanup_close_ int socket_fd = -1, signal_fd = -1, fd = -1;
 469         char temp[] = "/run/systemd/ask-password/tmp.XXXXXX";
 470         char final[sizeof(temp)] = "";
 471         _cleanup_free_ char *socket_name = NULL;
 472         _cleanup_strv_free_ char **l = NULL;
 473         _cleanup_fclose_ FILE *f = NULL;
 474         struct pollfd pollfd[_FD_MAX];
 475         sigset_t mask, oldmask;
 476         int r;
 477
 478         assert(ret);
 479
 480         if (flags & ASK_PASSWORD_NO_AGENT)
 481                 return -EUNATCH;
 482
 483         assert_se(sigemptyset(&mask) >= 0);
 484         assert_se(sigset_add_many(&mask, SIGINT, SIGTERM, -1) >= 0);
 485         assert_se(sigprocmask(SIG_BLOCK, &mask, &oldmask) >= 0);
 486
 487         (void) mkdir_p_label("/run/systemd/ask-password", 0755);
 488
 489         fd = mkostemp_safe(temp, O_WRONLY|O_CLOEXEC);
 490         if (fd < 0) {
 491                 r = fd;
 492                 goto finish;
 493         }
 494
 495         (void) fchmod(fd, 0644);
 496
 497         f = fdopen(fd, "w");
 498         if (!f) {
 499                 r = -errno;
 500                 goto finish;
 501         }
 502
 503         fd = -1;
 504
 505         signal_fd = signalfd(-1, &mask, SFD_NONBLOCK|SFD_CLOEXEC);
 506         if (signal_fd < 0) {
 507                 r = -errno;
 508                 goto finish;
 509         }
 510
 511         socket_fd = create_socket(&socket_name);
 512         if (socket_fd < 0) {
 513                 r = socket_fd;
 514                 goto finish;
 515         }
 516
 517         fprintf(f,
 518                 "[Ask]\n"
 519                 "PID="PID_FMT"\n"
 520                 "Socket=%s\n"
 521                 "AcceptCached=%i\n"
 522                 "Echo=%i\n"
 523                 "NotAfter="USEC_FMT"\n",
 524                 getpid(),
 525                 socket_name,
 526                 (flags & ASK_PASSWORD_ACCEPT_CACHED) ? 1 : 0,
 527                 (flags & ASK_PASSWORD_ECHO) ? 1 : 0,
 528                 until);
 529
 530         if (message)
 531                 fprintf(f, "Message=%s\n", message);
 532
 533         if (icon)
 534                 fprintf(f, "Icon=%s\n", icon);
 535
 536         if (id)
 537                 fprintf(f, "Id=%s\n", id);
 538
 539         r = fflush_and_check(f);
 540         if (r < 0)
 541                 goto finish;
 542
 543         memcpy(final, temp, sizeof(temp));
 544
 545         final[sizeof(final)-11] = 'a';
 546         final[sizeof(final)-10] = 's';
 547         final[sizeof(final)-9] = 'k';
 548
 549         if (rename(temp, final) < 0) {
 550                 r = -errno;
 551                 goto finish;
 552         }
 553
 554         zero(pollfd);
 555         pollfd[FD_SOCKET].fd = socket_fd;
 556         pollfd[FD_SOCKET].events = POLLIN;
 557         pollfd[FD_SIGNAL].fd = signal_fd;
 558         pollfd[FD_SIGNAL].events = POLLIN;
 559
 560         for (;;) {
 561                 char passphrase[LINE_MAX+1];
 562                 struct msghdr msghdr;
 563                 struct iovec iovec;
 564                 struct ucred *ucred;
 565                 union {
 566                         struct cmsghdr cmsghdr;
 567                         uint8_t buf[CMSG_SPACE(sizeof(struct ucred))];
 568                 } control;
 569                 ssize_t n;
 570                 int k;
 571                 usec_t t;
 572
 573                 t = now(CLOCK_MONOTONIC);
 574
 575                 if (until > 0 && until <= t) {
 576                         r = -ETIME;
 577                         goto finish;
 578                 }
 579
 580                 k = poll(pollfd, _FD_MAX, until > 0 ? (int) ((until-t)/USEC_PER_MSEC) : -1);
 581                 if (k < 0) {
 582                         if (errno == EINTR)
 583                                 continue;
 584
 585                         r = -errno;
 586                         goto finish;
 587                 }
 588
 589                 if (k <= 0) {
 590                         r = -ETIME;
 591                         goto finish;
 592                 }
 593
 594                 if (pollfd[FD_SIGNAL].revents & POLLIN) {
 595                         r = -EINTR;
 596                         goto finish;
 597                 }
 598
 599                 if (pollfd[FD_SOCKET].revents != POLLIN) {
 600                         r = -EIO;
 601                         goto finish;
 602                 }
 603
 604                 zero(iovec);
 605                 iovec.iov_base = passphrase;
 606                 iovec.iov_len = sizeof(passphrase);
 607
 608                 zero(control);
 609                 zero(msghdr);
 610                 msghdr.msg_iov = &iovec;
 611                 msghdr.msg_iovlen = 1;
 612                 msghdr.msg_control = &control;
 613                 msghdr.msg_controllen = sizeof(control);
 614
 615                 n = recvmsg(socket_fd, &msghdr, 0);
 616                 if (n < 0) {
 617                         if (errno == EAGAIN ||
 618                             errno == EINTR)
 619                                 continue;
 620
 621                         r = -errno;
 622                         goto finish;
 623                 }
 624
 625                 cmsg_close_all(&msghdr);
 626
 627                 if (n <= 0) {
 628                         log_debug("Message too short");
 629                         continue;
 630                 }
 631
 632                 if (msghdr.msg_controllen < CMSG_LEN(sizeof(struct ucred)) ||
 633                     control.cmsghdr.cmsg_level != SOL_SOCKET ||
 634                     control.cmsghdr.cmsg_type != SCM_CREDENTIALS ||
 635                     control.cmsghdr.cmsg_len != CMSG_LEN(sizeof(struct ucred))) {
 636                         log_debug("Received message without credentials. Ignoring.");
 637                         continue;
 638                 }
 639
 640                 ucred = (struct ucred*) CMSG_DATA(&control.cmsghdr);
 641                 if (ucred->uid != 0) {
 642                         log_debug("Got request from unprivileged user. Ignoring.");
 643                         continue;
 644                 }
 645
 646                 if (passphrase[0] == '+') {
 647                         /* An empty message refers to the empty password */
 648                         if (n == 1)
 649                                 l = strv_new("", NULL);
 650                         else
 651                                 l = strv_parse_nulstr(passphrase+1, n-1);
 652                         memory_erase(passphrase, n);
 653                         if (!l) {
 654                                 r = -ENOMEM;
 655                                 goto finish;
 656                         }
 657
 658                         if (strv_length(l) <= 0) {
 659                                 l = strv_free(l);
 660                                 log_debug("Invalid packet");
 661                                 continue;
 662                         }
 663
 664                         break;
 665                 }
 666
 667                 if (passphrase[0] == '-') {
 668                         r = -ECANCELED;
 669                         goto finish;
 670                 }
 671
 672                 log_debug("Invalid packet");
 673         }
 674
 675         if (keyname)
 676                 (void) add_to_keyring_and_log(keyname, flags, l);
 677
 678         *ret = l;
 679         l = NULL;
 680         r = 0;
 681
 682 finish:
 683         if (socket_name)
 684                 (void) unlink(socket_name);
 685
 686         (void) unlink(temp);
 687
 688         if (final[0])
 689                 (void) unlink(final);
 690
 691         assert_se(sigprocmask(SIG_SETMASK, &oldmask, NULL) == 0);
 692         return r;
 693 }
 694
 695 int ask_password_auto(
 696                 const char *message,
 697                 const char *icon,
 698                 const char *id,
 699                 const char *keyname,
 700                 usec_t until,
 701                 AskPasswordFlags flags,
 702                 char ***ret) {
 703
 704         int r;
 705
 706         assert(ret);
 707
 708         if ((flags & ASK_PASSWORD_ACCEPT_CACHED) && keyname) {
 709                 r = ask_password_keyring(keyname, flags, ret);
 710                 if (r != -ENOKEY)
 711                         return r;
 712         }
 713
 714         if (!(flags & ASK_PASSWORD_NO_TTY) && isatty(STDIN_FILENO)) {
 715                 char *s = NULL, **l = NULL;
 716
 717                 r = ask_password_tty(message, keyname, until, flags, NULL, &s);
 718                 if (r < 0)
 719                         return r;
 720
 721                 r = strv_push(&l, s);
 722                 if (r < 0) {
 723                         string_erase(s);
 724                         free(s);
 725                         return -ENOMEM;
 726                 }
 727
 728                 *ret = l;
 729                 return 0;
 730         }
 731
 732         if (!(flags & ASK_PASSWORD_NO_AGENT))
 733                 return ask_password_agent(message, icon, id, keyname, until, flags, ret);
 734
 735         return -EUNATCH;
 736 }