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, "\x1B[1m", 4, false);
  93                 loop_write(ttyfd, message, strlen(message), false);
  94                 loop_write(ttyfd, " ", 1, false);
  95                 loop_write(ttyfd, "\x1B[0m", 4, 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
 254         assert(name);
 255
 256         if ((fd = socket(AF_UNIX, SOCK_DGRAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0)) < 0) {
 257                 log_error("socket() failed: %m");
 258                 return -errno;
 259         }
 260
 261         zero(sa);
 262         sa.un.sun_family = AF_UNIX;
 263         snprintf(sa.un.sun_path, sizeof(sa.un.sun_path)-1, "/run/systemd/ask-password/sck.%llu", random_ull());
 264
 265         if (bind(fd, &sa.sa, offsetof(struct sockaddr_un, sun_path) + strlen(sa.un.sun_path)) < 0) {
 266                 r = -errno;
 267                 log_error("bind() failed: %m");
 268                 goto fail;
 269         }
 270
 271         if (setsockopt(fd, SOL_SOCKET, SO_PASSCRED, &one, sizeof(one)) < 0) {
 272                 r = -errno;
 273                 log_error("SO_PASSCRED failed: %m");
 274                 goto fail;
 275         }
 276
 277         if (!(c = strdup(sa.un.sun_path))) {
 278                 r = -ENOMEM;
 279                 log_error("Out of memory");
 280                 goto fail;
 281         }
 282
 283         *name = c;
 284         return fd;
 285
 286 fail:
 287         close_nointr_nofail(fd);
 288
 289         return r;
 290 }
 291
 292 int ask_password_agent(
 293                 const char *message,
 294                 const char *icon,
 295                 usec_t until,
 296                 bool accept_cached,
 297                 char ***_passphrases) {
 298
 299         enum {
 300                 FD_SOCKET,
 301                 FD_SIGNAL,
 302                 _FD_MAX
 303         };
 304
 305         char temp[] = "/run/systemd/ask-password/tmp.XXXXXX";
 306         char final[sizeof(temp)] = "";
 307         int fd = -1, r;
 308         FILE *f = NULL;
 309         char *socket_name = NULL;
 310         int socket_fd = -1, signal_fd = -1;
 311         sigset_t mask, oldmask;
 312         struct pollfd pollfd[_FD_MAX];
 313
 314         assert(_passphrases);
 315
 316         assert_se(sigemptyset(&mask) == 0);
 317         sigset_add_many(&mask, SIGINT, SIGTERM, -1);
 318         assert_se(sigprocmask(SIG_BLOCK, &mask, &oldmask) == 0);
 319
 320         mkdir_p("/run/systemd/ask-password", 0755);
 321
 322         if ((fd = mkostemp(temp, O_CLOEXEC|O_CREAT|O_WRONLY)) < 0) {
 323                 log_error("Failed to create password file: %m");
 324                 r = -errno;
 325                 goto finish;
 326         }
 327
 328         fchmod(fd, 0644);
 329
 330         if (!(f = fdopen(fd, "w"))) {
 331                 log_error("Failed to allocate FILE: %m");
 332                 r = -errno;
 333                 goto finish;
 334         }
 335
 336         fd = -1;
 337
 338         if ((signal_fd = signalfd(-1, &mask, SFD_NONBLOCK|SFD_CLOEXEC)) < 0) {
 339                 log_error("signalfd(): %m");
 340                 r = -errno;
 341                 goto finish;
 342         }
 343
 344         if ((socket_fd = create_socket(&socket_name)) < 0) {
 345                 r = socket_fd;
 346                 goto finish;
 347         }
 348
 349         fprintf(f,
 350                 "[Ask]\n"
 351                 "PID=%lu\n"
 352                 "Socket=%s\n"
 353                 "AcceptCached=%i\n"
 354                 "NotAfter=%llu\n",
 355                 (unsigned long) getpid(),
 356                 socket_name,
 357                 accept_cached ? 1 : 0,
 358                 (unsigned long long) until);
 359
 360         if (message)
 361                 fprintf(f, "Message=%s\n", message);
 362
 363         if (icon)
 364                 fprintf(f, "Icon=%s\n", icon);
 365
 366         fflush(f);
 367
 368         if (ferror(f)) {
 369                 log_error("Failed to write query file: %m");
 370                 r = -errno;
 371                 goto finish;
 372         }
 373
 374         memcpy(final, temp, sizeof(temp));
 375
 376         final[sizeof(final)-11] = 'a';
 377         final[sizeof(final)-10] = 's';
 378         final[sizeof(final)-9] = 'k';
 379
 380         if (rename(temp, final) < 0) {
 381                 log_error("Failed to rename query file: %m");
 382                 r = -errno;
 383                 goto finish;
 384         }
 385
 386         zero(pollfd);
 387         pollfd[FD_SOCKET].fd = socket_fd;
 388         pollfd[FD_SOCKET].events = POLLIN;
 389         pollfd[FD_SIGNAL].fd = signal_fd;
 390         pollfd[FD_SIGNAL].events = POLLIN;
 391
 392         for (;;) {
 393                 char passphrase[LINE_MAX+1];
 394                 struct msghdr msghdr;
 395                 struct iovec iovec;
 396                 struct ucred *ucred;
 397                 union {
 398                         struct cmsghdr cmsghdr;
 399                         uint8_t buf[CMSG_SPACE(sizeof(struct ucred))];
 400                 } control;
 401                 ssize_t n;
 402                 int k;
 403                 usec_t t;
 404
 405                 t = now(CLOCK_MONOTONIC);
 406
 407                 if (until > 0 && until <= t) {
 408                         log_notice("Timed out");
 409                         r = -ETIME;
 410                         goto finish;
 411                 }
 412
 413                 if ((k = poll(pollfd, _FD_MAX, until > 0 ? (int) ((until-t)/USEC_PER_MSEC) : -1)) < 0) {
 414
 415                         if (errno == EINTR)
 416                                 continue;
 417
 418                         log_error("poll() failed: %m");
 419                         r = -errno;
 420                         goto finish;
 421                 }
 422
 423                 if (k <= 0) {
 424                         log_notice("Timed out");
 425                         r = -ETIME;
 426                         goto finish;
 427                 }
 428
 429                 if (pollfd[FD_SIGNAL].revents & POLLIN) {
 430                         r = -EINTR;
 431                         goto finish;
 432                 }
 433
 434                 if (pollfd[FD_SOCKET].revents != POLLIN) {
 435                         log_error("Unexpected poll() event.");
 436                         r = -EIO;
 437                         goto finish;
 438                 }
 439
 440                 zero(iovec);
 441                 iovec.iov_base = passphrase;
 442                 iovec.iov_len = sizeof(passphrase);
 443
 444                 zero(control);
 445                 zero(msghdr);
 446                 msghdr.msg_iov = &iovec;
 447                 msghdr.msg_iovlen = 1;
 448                 msghdr.msg_control = &control;
 449                 msghdr.msg_controllen = sizeof(control);
 450
 451                 if ((n = recvmsg(socket_fd, &msghdr, 0)) < 0) {
 452
 453                         if (errno == EAGAIN ||
 454                             errno == EINTR)
 455                                 continue;
 456
 457                         log_error("recvmsg() failed: %m");
 458                         r = -errno;
 459                         goto finish;
 460                 }
 461
 462                 if (n <= 0) {
 463                         log_error("Message too short");
 464                         continue;
 465                 }
 466
 467                 if (msghdr.msg_controllen < CMSG_LEN(sizeof(struct ucred)) ||
 468                     control.cmsghdr.cmsg_level != SOL_SOCKET ||
 469                     control.cmsghdr.cmsg_type != SCM_CREDENTIALS ||
 470                     control.cmsghdr.cmsg_len != CMSG_LEN(sizeof(struct ucred))) {
 471                         log_warning("Received message without credentials. Ignoring.");
 472                         continue;
 473                 }
 474
 475                 ucred = (struct ucred*) CMSG_DATA(&control.cmsghdr);
 476                 if (ucred->uid != 0) {
 477                         log_warning("Got request from unprivileged user. Ignoring.");
 478                         continue;
 479                 }
 480
 481                 if (passphrase[0] == '+') {
 482                         char **l;
 483
 484                         if (n == 1)
 485                                 l = strv_new("", NULL);
 486                         else
 487                                 l = strv_parse_nulstr(passphrase+1, n-1);
 488                                 /* An empty message refers to the empty password */
 489
 490                         if (!l) {
 491                                 r = -ENOMEM;
 492                                 goto finish;
 493                         }
 494
 495                         if (strv_length(l) <= 0) {
 496                                 strv_free(l);
 497                                 log_error("Invalid packet");
 498                                 continue;
 499                         }
 500
 501                         *_passphrases = l;
 502
 503                 } else if (passphrase[0] == '-') {
 504                         r = -ECANCELED;
 505                         goto finish;
 506                 } else {
 507                         log_error("Invalid packet");
 508                         continue;
 509                 }
 510
 511                 break;
 512         }
 513
 514         r = 0;
 515
 516 finish:
 517         if (fd >= 0)
 518                 close_nointr_nofail(fd);
 519
 520         if (socket_name) {
 521                 unlink(socket_name);
 522                 free(socket_name);
 523         }
 524
 525         if (socket_fd >= 0)
 526                 close_nointr_nofail(socket_fd);
 527
 528         if (signal_fd >= 0)
 529                 close_nointr_nofail(signal_fd);
 530
 531         if (f)
 532                 fclose(f);
 533
 534         unlink(temp);
 535
 536         if (final[0])
 537                 unlink(final);
 538
 539         assert_se(sigprocmask(SIG_SETMASK, &oldmask, NULL) == 0);
 540
 541         return r;
 542 }
 543
 544 int ask_password_auto(const char *message, const char *icon, usec_t until, bool accept_cached, char ***_passphrases) {
 545         assert(message);
 546         assert(_passphrases);
 547
 548         if (isatty(STDIN_FILENO)) {
 549                 int r;
 550                 char *s = NULL, **l = NULL;
 551
 552                 if ((r = ask_password_tty(message, until, NULL, &s)) < 0)
 553                         return r;
 554
 555                 l = strv_new(s, NULL);
 556                 free(s);
 557
 558                 if (!l)
 559                         return -ENOMEM;
 560
 561                 *_passphrases = l;
 562                 return r;
 563
 564         } else
 565                 return ask_password_agent(message, icon, until, accept_cached, _passphrases);
 566 }