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 "format-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         serial = add_key("user", keyname, p, n, KEY_SPEC_USER_KEYRING);
 143         memory_erase(p, n);
 144         if (serial == -1)
 145                 return -errno;
 146
 147         if (keyctl(KEYCTL_SET_TIMEOUT,
 148                    (unsigned long) serial,
 149                    (unsigned long) DIV_ROUND_UP(KEYRING_TIMEOUT_USEC, USEC_PER_SEC), 0, 0) < 0)
 150                 log_debug_errno(errno, "Failed to adjust timeout: %m");
 151
 152         log_debug("Added key to keyring as %" PRIi32 ".", serial);
 153
 154         return 1;
 155 }
 156
 157 static int add_to_keyring_and_log(const char *keyname, AskPasswordFlags flags, char **passwords) {
 158         int r;
 159
 160         assert(keyname);
 161         assert(passwords);
 162
 163         r = add_to_keyring(keyname, flags, passwords);
 164         if (r < 0)
 165                 return log_debug_errno(r, "Failed to add password to keyring: %m");
 166
 167         return 0;
 168 }
 169
 170 int ask_password_keyring(const char *keyname, AskPasswordFlags flags, char ***ret) {
 171
 172         key_serial_t serial;
 173         int r;
 174
 175         assert(keyname);
 176         assert(ret);
 177
 178         if (!(flags & ASK_PASSWORD_ACCEPT_CACHED))
 179                 return -EUNATCH;
 180
 181         r = lookup_key(keyname, &serial);
 182         if (r == -ENOSYS) /* when retrieving the distinction doesn't matter */
 183                 return -ENOKEY;
 184         if (r < 0)
 185                 return r;
 186
 187         return retrieve_key(serial, ret);
 188 }
 189
 190 static void backspace_chars(int ttyfd, size_t p) {
 191
 192         if (ttyfd < 0)
 193                 return;
 194
 195         while (p > 0) {
 196                 p--;
 197
 198                 loop_write(ttyfd, "\b \b", 3, false);
 199         }
 200 }
 201
 202 int ask_password_tty(
 203                 const char *message,
 204                 const char *keyname,
 205                 usec_t until,
 206                 AskPasswordFlags flags,
 207                 const char *flag_file,
 208                 char **ret) {
 209
 210         struct termios old_termios, new_termios;
 211         char passphrase[LINE_MAX + 1] = {}, *x;
 212         size_t p = 0, codepoint = 0;
 213         int r;
 214         _cleanup_close_ int ttyfd = -1, notify = -1;
 215         struct pollfd pollfd[2];
 216         bool reset_tty = false;
 217         bool dirty = false;
 218         enum {
 219                 POLL_TTY,
 220                 POLL_INOTIFY
 221         };
 222
 223         assert(ret);
 224
 225         if (flags & ASK_PASSWORD_NO_TTY)
 226                 return -EUNATCH;
 227
 228         if (!message)
 229                 message = "Password:";
 230
 231         if (flag_file) {
 232                 notify = inotify_init1(IN_CLOEXEC|IN_NONBLOCK);
 233                 if (notify < 0) {
 234                         r = -errno;
 235                         goto finish;
 236                 }
 237
 238                 if (inotify_add_watch(notify, flag_file, IN_ATTRIB /* for the link count */) < 0) {
 239                         r = -errno;
 240                         goto finish;
 241                 }
 242         }
 243
 244         ttyfd = open("/dev/tty", O_RDWR|O_NOCTTY|O_CLOEXEC);
 245         if (ttyfd >= 0) {
 246
 247                 if (tcgetattr(ttyfd, &old_termios) < 0) {
 248                         r = -errno;
 249                         goto finish;
 250                 }
 251
 252                 if (colors_enabled())
 253                         loop_write(ttyfd, ANSI_HIGHLIGHT, strlen(ANSI_HIGHLIGHT), false);
 254                 loop_write(ttyfd, message, strlen(message), false);
 255                 loop_write(ttyfd, " ", 1, false);
 256                 if (colors_enabled())
 257                         loop_write(ttyfd, ANSI_NORMAL, strlen(ANSI_NORMAL), false);
 258
 259                 new_termios = old_termios;
 260                 new_termios.c_lflag &= ~(ICANON|ECHO);
 261                 new_termios.c_cc[VMIN] = 1;
 262                 new_termios.c_cc[VTIME] = 0;
 263
 264                 if (tcsetattr(ttyfd, TCSADRAIN, &new_termios) < 0) {
 265                         r = -errno;
 266                         goto finish;
 267                 }
 268
 269                 reset_tty = true;
 270         }
 271
 272         zero(pollfd);
 273         pollfd[POLL_TTY].fd = ttyfd >= 0 ? ttyfd : STDIN_FILENO;
 274         pollfd[POLL_TTY].events = POLLIN;
 275         pollfd[POLL_INOTIFY].fd = notify;
 276         pollfd[POLL_INOTIFY].events = POLLIN;
 277
 278         for (;;) {
 279                 char c;
 280                 int sleep_for = -1, k;
 281                 ssize_t n;
 282
 283                 if (until > 0) {
 284                         usec_t y;
 285
 286                         y = now(CLOCK_MONOTONIC);
 287
 288                         if (y > until) {
 289                                 r = -ETIME;
 290                                 goto finish;
 291                         }
 292
 293                         sleep_for = (int) ((until - y) / USEC_PER_MSEC);
 294                 }
 295
 296                 if (flag_file)
 297                         if (access(flag_file, F_OK) < 0) {
 298                                 r = -errno;
 299                                 goto finish;
 300                         }
 301
 302                 k = poll(pollfd, notify >= 0 ? 2 : 1, sleep_for);
 303                 if (k < 0) {
 304                         if (errno == EINTR)
 305                                 continue;
 306
 307                         r = -errno;
 308                         goto finish;
 309                 } else if (k == 0) {
 310                         r = -ETIME;
 311                         goto finish;
 312                 }
 313
 314                 if (notify >= 0 && pollfd[POLL_INOTIFY].revents != 0)
 315                         flush_fd(notify);
 316
 317                 if (pollfd[POLL_TTY].revents == 0)
 318                         continue;
 319
 320                 n = read(ttyfd >= 0 ? ttyfd : STDIN_FILENO, &c, 1);
 321                 if (n < 0) {
 322                         if (errno == EINTR || errno == EAGAIN)
 323                                 continue;
 324
 325                         r = -errno;
 326                         goto finish;
 327
 328                 } else if (n == 0)
 329                         break;
 330
 331                 if (c == '\n')
 332                         break;
 333                 else if (c == 21) { /* C-u */
 334
 335                         if (!(flags & ASK_PASSWORD_SILENT))
 336                                 backspace_chars(ttyfd, p);
 337                         p = 0;
 338
 339                 } else if (c == '\b' || c == 127) {
 340
 341                         if (p > 0) {
 342
 343                                 if (!(flags & ASK_PASSWORD_SILENT))
 344                                         backspace_chars(ttyfd, 1);
 345
 346                                 p--;
 347                         } else if (!dirty && !(flags & ASK_PASSWORD_SILENT)) {
 348
 349                                 flags |= ASK_PASSWORD_SILENT;
 350
 351                                 /* There are two ways to enter silent
 352                                  * mode. Either by pressing backspace
 353                                  * as first key (and only as first
 354                                  * key), or ... */
 355                                 if (ttyfd >= 0)
 356                                         loop_write(ttyfd, "(no echo) ", 10, false);
 357
 358                         } else if (ttyfd >= 0)
 359                                 loop_write(ttyfd, "\a", 1, false);
 360
 361                 } else if (c == '\t' && !(flags & ASK_PASSWORD_SILENT)) {
 362
 363                         backspace_chars(ttyfd, p);
 364                         flags |= ASK_PASSWORD_SILENT;
 365
 366                         /* ... or by pressing TAB at any time. */
 367
 368                         if (ttyfd >= 0)
 369                                 loop_write(ttyfd, "(no echo) ", 10, false);
 370                 } else {
 371                         if (p >= sizeof(passphrase)-1) {
 372                                 loop_write(ttyfd, "\a", 1, false);
 373                                 continue;
 374                         }
 375
 376                         passphrase[p++] = c;
 377
 378                         if (!(flags & ASK_PASSWORD_SILENT) && ttyfd >= 0) {
 379                                 n = utf8_encoded_valid_unichar(passphrase + codepoint);
 380                                 if (n >= 0) {
 381                                         codepoint = p;
 382                                         loop_write(ttyfd, (flags & ASK_PASSWORD_ECHO) ? &c : "*", 1, false);
 383                                 }
 384                         }
 385
 386                         dirty = true;
 387                 }
 388
 389                 c = 'x';
 390         }
 391
 392         x = strndup(passphrase, p);
 393         memory_erase(passphrase, p);
 394         if (!x) {
 395                 r = -ENOMEM;
 396                 goto finish;
 397         }
 398
 399         if (keyname)
 400                 (void) add_to_keyring_and_log(keyname, flags, STRV_MAKE(x));
 401
 402         *ret = x;
 403         r = 0;
 404
 405 finish:
 406         if (ttyfd >= 0 && reset_tty) {
 407                 loop_write(ttyfd, "\n", 1, false);
 408                 tcsetattr(ttyfd, TCSADRAIN, &old_termios);
 409         }
 410
 411         return r;
 412 }
 413
 414 static int create_socket(char **name) {
 415         union sockaddr_union sa = {
 416                 .un.sun_family = AF_UNIX,
 417         };
 418         _cleanup_close_ int fd = -1;
 419         static const int one = 1;
 420         char *c;
 421         int r;
 422
 423         assert(name);
 424
 425         fd = socket(AF_UNIX, SOCK_DGRAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0);
 426         if (fd < 0)
 427                 return -errno;
 428
 429         snprintf(sa.un.sun_path, sizeof(sa.un.sun_path)-1, "/run/systemd/ask-password/sck.%" PRIx64, random_u64());
 430
 431         RUN_WITH_UMASK(0177) {
 432                 if (bind(fd, &sa.sa, SOCKADDR_UN_LEN(sa.un)) < 0)
 433                         return -errno;
 434         }
 435
 436         if (setsockopt(fd, SOL_SOCKET, SO_PASSCRED, &one, sizeof(one)) < 0)
 437                 return -errno;
 438
 439         c = strdup(sa.un.sun_path);
 440         if (!c)
 441                 return -ENOMEM;
 442
 443         *name = c;
 444
 445         r = fd;
 446         fd = -1;
 447
 448         return r;
 449 }
 450
 451 int ask_password_agent(
 452                 const char *message,
 453                 const char *icon,
 454                 const char *id,
 455                 const char *keyname,
 456                 usec_t until,
 457                 AskPasswordFlags flags,
 458                 char ***ret) {
 459
 460         enum {
 461                 FD_SOCKET,
 462                 FD_SIGNAL,
 463                 _FD_MAX
 464         };
 465
 466         _cleanup_close_ int socket_fd = -1, signal_fd = -1, fd = -1;
 467         char temp[] = "/run/systemd/ask-password/tmp.XXXXXX";
 468         char final[sizeof(temp)] = "";
 469         _cleanup_free_ char *socket_name = NULL;
 470         _cleanup_strv_free_ char **l = NULL;
 471         _cleanup_fclose_ FILE *f = NULL;
 472         struct pollfd pollfd[_FD_MAX];
 473         sigset_t mask, oldmask;
 474         int r;
 475
 476         assert(ret);
 477
 478         if (flags & ASK_PASSWORD_NO_AGENT)
 479                 return -EUNATCH;
 480
 481         assert_se(sigemptyset(&mask) >= 0);
 482         assert_se(sigset_add_many(&mask, SIGINT, SIGTERM, -1) >= 0);
 483         assert_se(sigprocmask(SIG_BLOCK, &mask, &oldmask) >= 0);
 484
 485         (void) mkdir_p_label("/run/systemd/ask-password", 0755);
 486
 487         fd = mkostemp_safe(temp);
 488         if (fd < 0) {
 489                 r = fd;
 490                 goto finish;
 491         }
 492
 493         (void) fchmod(fd, 0644);
 494
 495         f = fdopen(fd, "w");
 496         if (!f) {
 497                 r = -errno;
 498                 goto finish;
 499         }
 500
 501         fd = -1;
 502
 503         signal_fd = signalfd(-1, &mask, SFD_NONBLOCK|SFD_CLOEXEC);
 504         if (signal_fd < 0) {
 505                 r = -errno;
 506                 goto finish;
 507         }
 508
 509         socket_fd = create_socket(&socket_name);
 510         if (socket_fd < 0) {
 511                 r = socket_fd;
 512                 goto finish;
 513         }
 514
 515         fprintf(f,
 516                 "[Ask]\n"
 517                 "PID="PID_FMT"\n"
 518                 "Socket=%s\n"
 519                 "AcceptCached=%i\n"
 520                 "Echo=%i\n"
 521                 "NotAfter="USEC_FMT"\n",
 522                 getpid(),
 523                 socket_name,
 524                 (flags & ASK_PASSWORD_ACCEPT_CACHED) ? 1 : 0,
 525                 (flags & ASK_PASSWORD_ECHO) ? 1 : 0,
 526                 until);
 527
 528         if (message)
 529                 fprintf(f, "Message=%s\n", message);
 530
 531         if (icon)
 532                 fprintf(f, "Icon=%s\n", icon);
 533
 534         if (id)
 535                 fprintf(f, "Id=%s\n", id);
 536
 537         r = fflush_and_check(f);
 538         if (r < 0)
 539                 goto finish;
 540
 541         memcpy(final, temp, sizeof(temp));
 542
 543         final[sizeof(final)-11] = 'a';
 544         final[sizeof(final)-10] = 's';
 545         final[sizeof(final)-9] = 'k';
 546
 547         if (rename(temp, final) < 0) {
 548                 r = -errno;
 549                 goto finish;
 550         }
 551
 552         zero(pollfd);
 553         pollfd[FD_SOCKET].fd = socket_fd;
 554         pollfd[FD_SOCKET].events = POLLIN;
 555         pollfd[FD_SIGNAL].fd = signal_fd;
 556         pollfd[FD_SIGNAL].events = POLLIN;
 557
 558         for (;;) {
 559                 char passphrase[LINE_MAX+1];
 560                 struct msghdr msghdr;
 561                 struct iovec iovec;
 562                 struct ucred *ucred;
 563                 union {
 564                         struct cmsghdr cmsghdr;
 565                         uint8_t buf[CMSG_SPACE(sizeof(struct ucred))];
 566                 } control;
 567                 ssize_t n;
 568                 int k;
 569                 usec_t t;
 570
 571                 t = now(CLOCK_MONOTONIC);
 572
 573                 if (until > 0 && until <= t) {
 574                         r = -ETIME;
 575                         goto finish;
 576                 }
 577
 578                 k = poll(pollfd, _FD_MAX, until > 0 ? (int) ((until-t)/USEC_PER_MSEC) : -1);
 579                 if (k < 0) {
 580                         if (errno == EINTR)
 581                                 continue;
 582
 583                         r = -errno;
 584                         goto finish;
 585                 }
 586
 587                 if (k <= 0) {
 588                         r = -ETIME;
 589                         goto finish;
 590                 }
 591
 592                 if (pollfd[FD_SIGNAL].revents & POLLIN) {
 593                         r = -EINTR;
 594                         goto finish;
 595                 }
 596
 597                 if (pollfd[FD_SOCKET].revents != POLLIN) {
 598                         r = -EIO;
 599                         goto finish;
 600                 }
 601
 602                 zero(iovec);
 603                 iovec.iov_base = passphrase;
 604                 iovec.iov_len = sizeof(passphrase);
 605
 606                 zero(control);
 607                 zero(msghdr);
 608                 msghdr.msg_iov = &iovec;
 609                 msghdr.msg_iovlen = 1;
 610                 msghdr.msg_control = &control;
 611                 msghdr.msg_controllen = sizeof(control);
 612
 613                 n = recvmsg(socket_fd, &msghdr, 0);
 614                 if (n < 0) {
 615                         if (errno == EAGAIN ||
 616                             errno == EINTR)
 617                                 continue;
 618
 619                         r = -errno;
 620                         goto finish;
 621                 }
 622
 623                 cmsg_close_all(&msghdr);
 624
 625                 if (n <= 0) {
 626                         log_debug("Message too short");
 627                         continue;
 628                 }
 629
 630                 if (msghdr.msg_controllen < CMSG_LEN(sizeof(struct ucred)) ||
 631                     control.cmsghdr.cmsg_level != SOL_SOCKET ||
 632                     control.cmsghdr.cmsg_type != SCM_CREDENTIALS ||
 633                     control.cmsghdr.cmsg_len != CMSG_LEN(sizeof(struct ucred))) {
 634                         log_debug("Received message without credentials. Ignoring.");
 635                         continue;
 636                 }
 637
 638                 ucred = (struct ucred*) CMSG_DATA(&control.cmsghdr);
 639                 if (ucred->uid != 0) {
 640                         log_debug("Got request from unprivileged user. Ignoring.");
 641                         continue;
 642                 }
 643
 644                 if (passphrase[0] == '+') {
 645                         /* An empty message refers to the empty password */
 646                         if (n == 1)
 647                                 l = strv_new("", NULL);
 648                         else
 649                                 l = strv_parse_nulstr(passphrase+1, n-1);
 650                         memory_erase(passphrase, n);
 651                         if (!l) {
 652                                 r = -ENOMEM;
 653                                 goto finish;
 654                         }
 655
 656                         if (strv_length(l) <= 0) {
 657                                 l = strv_free(l);
 658                                 log_debug("Invalid packet");
 659                                 continue;
 660                         }
 661
 662                         break;
 663                 }
 664
 665                 if (passphrase[0] == '-') {
 666                         r = -ECANCELED;
 667                         goto finish;
 668                 }
 669
 670                 log_debug("Invalid packet");
 671         }
 672
 673         if (keyname)
 674                 (void) add_to_keyring_and_log(keyname, flags, l);
 675
 676         *ret = l;
 677         l = NULL;
 678         r = 0;
 679
 680 finish:
 681         if (socket_name)
 682                 (void) unlink(socket_name);
 683
 684         (void) unlink(temp);
 685
 686         if (final[0])
 687                 (void) unlink(final);
 688
 689         assert_se(sigprocmask(SIG_SETMASK, &oldmask, NULL) == 0);
 690         return r;
 691 }
 692
 693 int ask_password_auto(
 694                 const char *message,
 695                 const char *icon,
 696                 const char *id,
 697                 const char *keyname,
 698                 usec_t until,
 699                 AskPasswordFlags flags,
 700                 char ***ret) {
 701
 702         int r;
 703
 704         assert(ret);
 705
 706         if ((flags & ASK_PASSWORD_ACCEPT_CACHED) && keyname) {
 707                 r = ask_password_keyring(keyname, flags, ret);
 708                 if (r != -ENOKEY)
 709                         return r;
 710         }
 711
 712         if (!(flags & ASK_PASSWORD_NO_TTY) && isatty(STDIN_FILENO)) {
 713                 char *s = NULL, **l = NULL;
 714
 715                 r = ask_password_tty(message, keyname, until, flags, NULL, &s);
 716                 if (r < 0)
 717                         return r;
 718
 719                 r = strv_push(&l, s);
 720                 if (r < 0) {
 721                         string_erase(s);
 722                         free(s);
 723                         return -ENOMEM;
 724                 }
 725
 726                 *ret = l;
 727                 return 0;
 728         }
 729
 730         if (!(flags & ASK_PASSWORD_NO_AGENT))
 731                 return ask_password_agent(message, icon, id, keyname, until, flags, ret);
 732
 733         return -EUNATCH;
 734 }