src/ask-password-api.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 #include <stdbool.h>
  22 #include <termios.h>
  23 #include <unistd.h>
  24 #include <sys/poll.h>
  25 #include <sys/inotify.h>
  26 #include <errno.h>
  27 #include <fcntl.h>
  28 #include <sys/socket.h>
  29 #include <string.h>
  30 #include <sys/un.h>
  31 #include <stddef.h>
  32 #include <sys/signalfd.h>
  33
  34 #include "util.h"
  35 #include "strv.h"
  36
  37 #include "ask-password-api.h"
  38
  39 static void backspace_chars(int ttyfd, size_t p) {
  40
  41         if (ttyfd < 0)
  42                 return;
  43
  44         while (p > 0) {
  45                 p--;
  46
  47                 loop_write(ttyfd, "\b \b", 3, false);
  48         }
  49 }
  50
  51 int ask_password_tty(
  52                 const char *message,
  53                 usec_t until,
  54                 const char *flag_file,
  55                 char **_passphrase) {
  56
  57         struct termios old_termios, new_termios;
  58         char passphrase[LINE_MAX];
  59         size_t p = 0;
  60         int r, ttyfd = -1, notify = -1;
  61         struct pollfd pollfd[2];
  62         bool reset_tty = false;
  63         bool silent_mode = false;
  64         bool dirty = false;
  65         enum {
  66                 POLL_TTY,
  67                 POLL_INOTIFY
  68         };
  69
  70         assert(message);
  71         assert(_passphrase);
  72
  73         if (flag_file) {
  74                 if ((notify = inotify_init1(IN_CLOEXEC|IN_NONBLOCK)) < 0) {
  75                         r = -errno;
  76                         goto finish;
  77                 }
  78
  79                 if (inotify_add_watch(notify, flag_file, IN_ATTRIB /* for the link count */) < 0) {
  80                         r = -errno;
  81                         goto finish;
  82                 }
  83         }
  84
  85         if ((ttyfd = open("/dev/tty", O_RDWR|O_NOCTTY|O_CLOEXEC)) >= 0) {
  86
  87                 if (tcgetattr(ttyfd, &old_termios) < 0) {
  88                         r = -errno;
  89                         goto finish;
  90                 }
  91
  92                 loop_write(ttyfd, ANSI_HIGHLIGHT_ON, sizeof(ANSI_HIGHLIGHT_ON)-1, false);
  93                 loop_write(ttyfd, message, strlen(message), false);
  94                 loop_write(ttyfd, " ", 1, false);
  95                 loop_write(ttyfd, ANSI_HIGHLIGHT_OFF, sizeof(ANSI_HIGHLIGHT_OFF)-1, false);
  96
  97                 new_termios = old_termios;
  98                 new_termios.c_lflag &= ~(ICANON|ECHO);
  99                 new_termios.c_cc[VMIN] = 1;
 100                 new_termios.c_cc[VTIME] = 0;
 101
 102                 if (tcsetattr(ttyfd, TCSADRAIN, &new_termios) < 0) {
 103                         r = -errno;
 104                         goto finish;
 105                 }
 106
 107                 reset_tty = true;
 108         }
 109
 110         zero(pollfd);
 111
 112         pollfd[POLL_TTY].fd = ttyfd >= 0 ? ttyfd : STDIN_FILENO;
 113         pollfd[POLL_TTY].events = POLLIN;
 114         pollfd[POLL_INOTIFY].fd = notify;
 115         pollfd[POLL_INOTIFY].events = POLLIN;
 116
 117         for (;;) {
 118                 char c;
 119                 int sleep_for = -1, k;
 120                 ssize_t n;
 121
 122                 if (until > 0) {
 123                         usec_t y;
 124
 125                         y = now(CLOCK_MONOTONIC);
 126
 127                         if (y > until) {
 128                                 r = -ETIME;
 129                                 goto finish;
 130                         }
 131
 132                         sleep_for = (int) ((until - y) / USEC_PER_MSEC);
 133                 }
 134
 135                 if (flag_file)
 136                         if (access(flag_file, F_OK) < 0) {
 137                                 r = -errno;
 138                                 goto finish;
 139                         }
 140
 141                 if ((k = poll(pollfd, notify > 0 ? 2 : 1, sleep_for)) < 0) {
 142
 143                         if (errno == EINTR)
 144                                 continue;
 145
 146                         r = -errno;
 147                         goto finish;
 148                 } else if (k == 0) {
 149                         r = -ETIME;
 150                         goto finish;
 151                 }
 152
 153                 if (notify > 0 && pollfd[POLL_INOTIFY].revents != 0)
 154                         flush_fd(notify);
 155
 156                 if (pollfd[POLL_TTY].revents == 0)
 157                         continue;
 158
 159                 if ((n = read(ttyfd >= 0 ? ttyfd : STDIN_FILENO, &c, 1)) < 0) {
 160
 161                         if (errno == EINTR || errno == EAGAIN)
 162                                 continue;
 163
 164                         r = -errno;
 165                         goto finish;
 166
 167                 } else if (n == 0)
 168                         break;
 169
 170                 if (c == '\n')
 171                         break;
 172                 else if (c == 21) { /* C-u */
 173
 174                         if (!silent_mode)
 175                                 backspace_chars(ttyfd, p);
 176                         p = 0;
 177
 178                 } else if (c == '\b' || c == 127) {
 179
 180                         if (p > 0) {
 181
 182                                 if (!silent_mode)
 183                                         backspace_chars(ttyfd, 1);
 184
 185                                 p--;
 186                         } else if (!dirty && !silent_mode) {
 187
 188                                 silent_mode = true;
 189
 190                                 /* There are two ways to enter silent
 191                                  * mode. Either by pressing backspace
 192                                  * as first key (and only as first key),
 193                                  * or ... */
 194                                 if (ttyfd >= 0)
 195                                         loop_write(ttyfd, "(no echo) ", 10, false);
 196
 197                         } else if (ttyfd >= 0)
 198                                 loop_write(ttyfd, "\a", 1, false);
 199
 200                 } else if (c == '\t' && !silent_mode) {
 201
 202                         backspace_chars(ttyfd, p);
 203                         silent_mode = true;
 204
 205                         /* ... or by pressing TAB at any time. */
 206
 207                         if (ttyfd >= 0)
 208                                 loop_write(ttyfd, "(no echo) ", 10, false);
 209                 } else {
 210                         passphrase[p++] = c;
 211
 212                         if (!silent_mode && ttyfd >= 0)
 213                                 loop_write(ttyfd, "*", 1, false);
 214
 215                         dirty = true;
 216                 }
 217         }
 218
 219         passphrase[p] = 0;
 220
 221         if (!(*_passphrase = strdup(passphrase))) {
 222                 r = -ENOMEM;
 223                 goto finish;
 224         }
 225
 226         r = 0;
 227
 228 finish:
 229         if (notify >= 0)
 230                 close_nointr_nofail(notify);
 231
 232         if (ttyfd >= 0) {
 233
 234                 if (reset_tty) {
 235                         loop_write(ttyfd, "\n", 1, false);
 236                         tcsetattr(ttyfd, TCSADRAIN, &old_termios);
 237                 }
 238
 239                 close_nointr_nofail(ttyfd);
 240         }
 241
 242         return r;
 243 }
 244
 245 static int create_socket(char **name) {
 246         int fd;
 247         union {
 248                 struct sockaddr sa;
 249                 struct sockaddr_un un;
 250         } sa;
 251         int one = 1, r;
 252         char *c;
 253         mode_t u;
 254
 255         assert(name);
 256
 257         if ((fd = socket(AF_UNIX, SOCK_DGRAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0)) < 0) {
 258                 log_error("socket() failed: %m");
 259                 return -errno;
 260         }
 261
 262         zero(sa);
 263         sa.un.sun_family = AF_UNIX;
 264         snprintf(sa.un.sun_path, sizeof(sa.un.sun_path)-1, "/run/systemd/ask-password/sck.%llu", random_ull());
 265
 266         u = umask(0177);
 267         r = bind(fd, &sa.sa, offsetof(struct sockaddr_un, sun_path) + strlen(sa.un.sun_path));
 268         umask(u);
 269
 270         if (r < 0) {
 271                 r = -errno;
 272                 log_error("bind() failed: %m");
 273                 goto fail;
 274         }
 275
 276         if (setsockopt(fd, SOL_SOCKET, SO_PASSCRED, &one, sizeof(one)) < 0) {
 277                 r = -errno;
 278                 log_error("SO_PASSCRED failed: %m");
 279                 goto fail;
 280         }
 281
 282         if (!(c = strdup(sa.un.sun_path))) {
 283                 r = -ENOMEM;
 284                 log_error("Out of memory");
 285                 goto fail;
 286         }
 287
 288         *name = c;
 289         return fd;
 290
 291 fail:
 292         close_nointr_nofail(fd);
 293
 294         return r;
 295 }
 296
 297 int ask_password_agent(
 298                 const char *message,
 299                 const char *icon,
 300                 usec_t until,
 301                 bool accept_cached,
 302                 char ***_passphrases) {
 303
 304         enum {
 305                 FD_SOCKET,
 306                 FD_SIGNAL,
 307                 _FD_MAX
 308         };
 309
 310         char temp[] = "/run/systemd/ask-password/tmp.XXXXXX";
 311         char final[sizeof(temp)] = "";
 312         int fd = -1, r;
 313         FILE *f = NULL;
 314         char *socket_name = NULL;
 315         int socket_fd = -1, signal_fd = -1;
 316         sigset_t mask, oldmask;
 317         struct pollfd pollfd[_FD_MAX];
 318         mode_t u;
 319
 320         assert(_passphrases);
 321
 322         assert_se(sigemptyset(&mask) == 0);
 323         sigset_add_many(&mask, SIGINT, SIGTERM, -1);
 324         assert_se(sigprocmask(SIG_BLOCK, &mask, &oldmask) == 0);
 325
 326         mkdir_p("/run/systemd/ask-password", 0755);
 327
 328         u = umask(0022);
 329         fd = mkostemp(temp, O_CLOEXEC|O_CREAT|O_WRONLY);
 330         umask(u);
 331
 332         if (fd < 0) {
 333                 log_error("Failed to create password file: %m");
 334                 r = -errno;
 335                 goto finish;
 336         }
 337
 338         fchmod(fd, 0644);
 339
 340         if (!(f = fdopen(fd, "w"))) {
 341                 log_error("Failed to allocate FILE: %m");
 342                 r = -errno;
 343                 goto finish;
 344         }
 345
 346         fd = -1;
 347
 348         if ((signal_fd = signalfd(-1, &mask, SFD_NONBLOCK|SFD_CLOEXEC)) < 0) {
 349                 log_error("signalfd(): %m");
 350                 r = -errno;
 351                 goto finish;
 352         }
 353
 354         if ((socket_fd = create_socket(&socket_name)) < 0) {
 355                 r = socket_fd;
 356                 goto finish;
 357         }
 358
 359         fprintf(f,
 360                 "[Ask]\n"
 361                 "PID=%lu\n"
 362                 "Socket=%s\n"
 363                 "AcceptCached=%i\n"
 364                 "NotAfter=%llu\n",
 365                 (unsigned long) getpid(),
 366                 socket_name,
 367                 accept_cached ? 1 : 0,
 368                 (unsigned long long) until);
 369
 370         if (message)
 371                 fprintf(f, "Message=%s\n", message);
 372
 373         if (icon)
 374                 fprintf(f, "Icon=%s\n", icon);
 375
 376         fflush(f);
 377
 378         if (ferror(f)) {
 379                 log_error("Failed to write query file: %m");
 380                 r = -errno;
 381                 goto finish;
 382         }
 383
 384         memcpy(final, temp, sizeof(temp));
 385
 386         final[sizeof(final)-11] = 'a';
 387         final[sizeof(final)-10] = 's';
 388         final[sizeof(final)-9] = 'k';
 389
 390         if (rename(temp, final) < 0) {
 391                 log_error("Failed to rename query file: %m");
 392                 r = -errno;
 393                 goto finish;
 394         }
 395
 396         zero(pollfd);
 397         pollfd[FD_SOCKET].fd = socket_fd;
 398         pollfd[FD_SOCKET].events = POLLIN;
 399         pollfd[FD_SIGNAL].fd = signal_fd;
 400         pollfd[FD_SIGNAL].events = POLLIN;
 401
 402         for (;;) {
 403                 char passphrase[LINE_MAX+1];
 404                 struct msghdr msghdr;
 405                 struct iovec iovec;
 406                 struct ucred *ucred;
 407                 union {
 408                         struct cmsghdr cmsghdr;
 409                         uint8_t buf[CMSG_SPACE(sizeof(struct ucred))];
 410                 } control;
 411                 ssize_t n;
 412                 int k;
 413                 usec_t t;
 414
 415                 t = now(CLOCK_MONOTONIC);
 416
 417                 if (until > 0 && until <= t) {
 418                         log_notice("Timed out");
 419                         r = -ETIME;
 420                         goto finish;
 421                 }
 422
 423                 if ((k = poll(pollfd, _FD_MAX, until > 0 ? (int) ((until-t)/USEC_PER_MSEC) : -1)) < 0) {
 424
 425                         if (errno == EINTR)
 426                                 continue;
 427
 428                         log_error("poll() failed: %m");
 429                         r = -errno;
 430                         goto finish;
 431                 }
 432
 433                 if (k <= 0) {
 434                         log_notice("Timed out");
 435                         r = -ETIME;
 436                         goto finish;
 437                 }
 438
 439                 if (pollfd[FD_SIGNAL].revents & POLLIN) {
 440                         r = -EINTR;
 441                         goto finish;
 442                 }
 443
 444                 if (pollfd[FD_SOCKET].revents != POLLIN) {
 445                         log_error("Unexpected poll() event.");
 446                         r = -EIO;
 447                         goto finish;
 448                 }
 449
 450                 zero(iovec);
 451                 iovec.iov_base = passphrase;
 452                 iovec.iov_len = sizeof(passphrase);
 453
 454                 zero(control);
 455                 zero(msghdr);
 456                 msghdr.msg_iov = &iovec;
 457                 msghdr.msg_iovlen = 1;
 458                 msghdr.msg_control = &control;
 459                 msghdr.msg_controllen = sizeof(control);
 460
 461                 if ((n = recvmsg(socket_fd, &msghdr, 0)) < 0) {
 462
 463                         if (errno == EAGAIN ||
 464                             errno == EINTR)
 465                                 continue;
 466
 467                         log_error("recvmsg() failed: %m");
 468                         r = -errno;
 469                         goto finish;
 470                 }
 471
 472                 if (n <= 0) {
 473                         log_error("Message too short");
 474                         continue;
 475                 }
 476
 477                 if (msghdr.msg_controllen < CMSG_LEN(sizeof(struct ucred)) ||
 478                     control.cmsghdr.cmsg_level != SOL_SOCKET ||
 479                     control.cmsghdr.cmsg_type != SCM_CREDENTIALS ||
 480                     control.cmsghdr.cmsg_len != CMSG_LEN(sizeof(struct ucred))) {
 481                         log_warning("Received message without credentials. Ignoring.");
 482                         continue;
 483                 }
 484
 485                 ucred = (struct ucred*) CMSG_DATA(&control.cmsghdr);
 486                 if (ucred->uid != 0) {
 487                         log_warning("Got request from unprivileged user. Ignoring.");
 488                         continue;
 489                 }
 490
 491                 if (passphrase[0] == '+') {
 492                         char **l;
 493
 494                         if (n == 1)
 495                                 l = strv_new("", NULL);
 496                         else
 497                                 l = strv_parse_nulstr(passphrase+1, n-1);
 498                                 /* An empty message refers to the empty password */
 499
 500                         if (!l) {
 501                                 r = -ENOMEM;
 502                                 goto finish;
 503                         }
 504
 505                         if (strv_length(l) <= 0) {
 506                                 strv_free(l);
 507                                 log_error("Invalid packet");
 508                                 continue;
 509                         }
 510
 511                         *_passphrases = l;
 512
 513                 } else if (passphrase[0] == '-') {
 514                         r = -ECANCELED;
 515                         goto finish;
 516                 } else {
 517                         log_error("Invalid packet");
 518                         continue;
 519                 }
 520
 521                 break;
 522         }
 523
 524         r = 0;
 525
 526 finish:
 527         if (fd >= 0)
 528                 close_nointr_nofail(fd);
 529
 530         if (socket_name) {
 531                 unlink(socket_name);
 532                 free(socket_name);
 533         }
 534
 535         if (socket_fd >= 0)
 536                 close_nointr_nofail(socket_fd);
 537
 538         if (signal_fd >= 0)
 539                 close_nointr_nofail(signal_fd);
 540
 541         if (f)
 542                 fclose(f);
 543
 544         unlink(temp);
 545
 546         if (final[0])
 547                 unlink(final);
 548
 549         assert_se(sigprocmask(SIG_SETMASK, &oldmask, NULL) == 0);
 550
 551         return r;
 552 }
 553
 554 int ask_password_auto(const char *message, const char *icon, usec_t until, bool accept_cached, char ***_passphrases) {
 555         assert(message);
 556         assert(_passphrases);
 557
 558         if (isatty(STDIN_FILENO)) {
 559                 int r;
 560                 char *s = NULL, **l = NULL;
 561
 562                 if ((r = ask_password_tty(message, until, NULL, &s)) < 0)
 563                         return r;
 564
 565                 l = strv_new(s, NULL);
 566                 free(s);
 567
 568                 if (!l)
 569                         return -ENOMEM;
 570
 571                 *_passphrases = l;
 572                 return r;
 573
 574         } else
 575                 return ask_password_agent(message, icon, until, accept_cached, _passphrases);
 576 }