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 "mkdir.h"
  36 #include "strv.h"
  37
  38 #include "ask-password-api.h"
  39
  40 static void backspace_chars(int ttyfd, size_t p) {
  41
  42         if (ttyfd < 0)
  43                 return;
  44
  45         while (p > 0) {
  46                 p--;
  47
  48                 loop_write(ttyfd, "\b \b", 3, false);
  49         }
  50 }
  51
  52 int ask_password_tty(
  53                 const char *message,
  54                 usec_t until,
  55                 const char *flag_file,
  56                 char **_passphrase) {
  57
  58         struct termios old_termios, new_termios;
  59         char passphrase[LINE_MAX];
  60         size_t p = 0;
  61         int r, ttyfd = -1, notify = -1;
  62         struct pollfd pollfd[2];
  63         bool reset_tty = false;
  64         bool silent_mode = false;
  65         bool dirty = false;
  66         enum {
  67                 POLL_TTY,
  68                 POLL_INOTIFY
  69         };
  70
  71         assert(message);
  72         assert(_passphrase);
  73
  74         if (flag_file) {
  75                 if ((notify = inotify_init1(IN_CLOEXEC|IN_NONBLOCK)) < 0) {
  76                         r = -errno;
  77                         goto finish;
  78                 }
  79
  80                 if (inotify_add_watch(notify, flag_file, IN_ATTRIB /* for the link count */) < 0) {
  81                         r = -errno;
  82                         goto finish;
  83                 }
  84         }
  85
  86         if ((ttyfd = open("/dev/tty", O_RDWR|O_NOCTTY|O_CLOEXEC)) >= 0) {
  87
  88                 if (tcgetattr(ttyfd, &old_termios) < 0) {
  89                         r = -errno;
  90                         goto finish;
  91                 }
  92
  93                 loop_write(ttyfd, ANSI_HIGHLIGHT_ON, sizeof(ANSI_HIGHLIGHT_ON)-1, false);
  94                 loop_write(ttyfd, message, strlen(message), false);
  95                 loop_write(ttyfd, " ", 1, false);
  96                 loop_write(ttyfd, ANSI_HIGHLIGHT_OFF, sizeof(ANSI_HIGHLIGHT_OFF)-1, false);
  97
  98                 new_termios = old_termios;
  99                 new_termios.c_lflag &= ~(ICANON|ECHO);
 100                 new_termios.c_cc[VMIN] = 1;
 101                 new_termios.c_cc[VTIME] = 0;
 102
 103                 if (tcsetattr(ttyfd, TCSADRAIN, &new_termios) < 0) {
 104                         r = -errno;
 105                         goto finish;
 106                 }
 107
 108                 reset_tty = true;
 109         }
 110
 111         zero(pollfd);
 112
 113         pollfd[POLL_TTY].fd = ttyfd >= 0 ? ttyfd : STDIN_FILENO;
 114         pollfd[POLL_TTY].events = POLLIN;
 115         pollfd[POLL_INOTIFY].fd = notify;
 116         pollfd[POLL_INOTIFY].events = POLLIN;
 117
 118         for (;;) {
 119                 char c;
 120                 int sleep_for = -1, k;
 121                 ssize_t n;
 122
 123                 if (until > 0) {
 124                         usec_t y;
 125
 126                         y = now(CLOCK_MONOTONIC);
 127
 128                         if (y > until) {
 129                                 r = -ETIME;
 130                                 goto finish;
 131                         }
 132
 133                         sleep_for = (int) ((until - y) / USEC_PER_MSEC);
 134                 }
 135
 136                 if (flag_file)
 137                         if (access(flag_file, F_OK) < 0) {
 138                                 r = -errno;
 139                                 goto finish;
 140                         }
 141
 142                 if ((k = poll(pollfd, notify > 0 ? 2 : 1, sleep_for)) < 0) {
 143
 144                         if (errno == EINTR)
 145                                 continue;
 146
 147                         r = -errno;
 148                         goto finish;
 149                 } else if (k == 0) {
 150                         r = -ETIME;
 151                         goto finish;
 152                 }
 153
 154                 if (notify > 0 && pollfd[POLL_INOTIFY].revents != 0)
 155                         flush_fd(notify);
 156
 157                 if (pollfd[POLL_TTY].revents == 0)
 158                         continue;
 159
 160                 if ((n = read(ttyfd >= 0 ? ttyfd : STDIN_FILENO, &c, 1)) < 0) {
 161
 162                         if (errno == EINTR || errno == EAGAIN)
 163                                 continue;
 164
 165                         r = -errno;
 166                         goto finish;
 167
 168                 } else if (n == 0)
 169                         break;
 170
 171                 if (c == '\n')
 172                         break;
 173                 else if (c == 21) { /* C-u */
 174
 175                         if (!silent_mode)
 176                                 backspace_chars(ttyfd, p);
 177                         p = 0;
 178
 179                 } else if (c == '\b' || c == 127) {
 180
 181                         if (p > 0) {
 182
 183                                 if (!silent_mode)
 184                                         backspace_chars(ttyfd, 1);
 185
 186                                 p--;
 187                         } else if (!dirty && !silent_mode) {
 188
 189                                 silent_mode = true;
 190
 191                                 /* There are two ways to enter silent
 192                                  * mode. Either by pressing backspace
 193                                  * as first key (and only as first key),
 194                                  * or ... */
 195                                 if (ttyfd >= 0)
 196                                         loop_write(ttyfd, "(no echo) ", 10, false);
 197
 198                         } else if (ttyfd >= 0)
 199                                 loop_write(ttyfd, "\a", 1, false);
 200
 201                 } else if (c == '\t' && !silent_mode) {
 202
 203                         backspace_chars(ttyfd, p);
 204                         silent_mode = true;
 205
 206                         /* ... or by pressing TAB at any time. */
 207
 208                         if (ttyfd >= 0)
 209                                 loop_write(ttyfd, "(no echo) ", 10, false);
 210                 } else {
 211                         passphrase[p++] = c;
 212
 213                         if (!silent_mode && ttyfd >= 0)
 214                                 loop_write(ttyfd, "*", 1, false);
 215
 216                         dirty = true;
 217                 }
 218         }
 219
 220         passphrase[p] = 0;
 221
 222         if (!(*_passphrase = strdup(passphrase))) {
 223                 r = -ENOMEM;
 224                 goto finish;
 225         }
 226
 227         r = 0;
 228
 229 finish:
 230         if (notify >= 0)
 231                 close_nointr_nofail(notify);
 232
 233         if (ttyfd >= 0) {
 234
 235                 if (reset_tty) {
 236                         loop_write(ttyfd, "\n", 1, false);
 237                         tcsetattr(ttyfd, TCSADRAIN, &old_termios);
 238                 }
 239
 240                 close_nointr_nofail(ttyfd);
 241         }
 242
 243         return r;
 244 }
 245
 246 static int create_socket(char **name) {
 247         int fd;
 248         union {
 249                 struct sockaddr sa;
 250                 struct sockaddr_un un;
 251         } sa;
 252         int one = 1, r;
 253         char *c;
 254         mode_t u;
 255
 256         assert(name);
 257
 258         if ((fd = socket(AF_UNIX, SOCK_DGRAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0)) < 0) {
 259                 log_error("socket() failed: %m");
 260                 return -errno;
 261         }
 262
 263         zero(sa);
 264         sa.un.sun_family = AF_UNIX;
 265         snprintf(sa.un.sun_path, sizeof(sa.un.sun_path)-1, "/run/systemd/ask-password/sck.%llu", random_ull());
 266
 267         u = umask(0177);
 268         r = bind(fd, &sa.sa, offsetof(struct sockaddr_un, sun_path) + strlen(sa.un.sun_path));
 269         umask(u);
 270
 271         if (r < 0) {
 272                 r = -errno;
 273                 log_error("bind() failed: %m");
 274                 goto fail;
 275         }
 276
 277         if (setsockopt(fd, SOL_SOCKET, SO_PASSCRED, &one, sizeof(one)) < 0) {
 278                 r = -errno;
 279                 log_error("SO_PASSCRED failed: %m");
 280                 goto fail;
 281         }
 282
 283         if (!(c = strdup(sa.un.sun_path))) {
 284                 r = -ENOMEM;
 285                 log_error("Out of memory");
 286                 goto fail;
 287         }
 288
 289         *name = c;
 290         return fd;
 291
 292 fail:
 293         close_nointr_nofail(fd);
 294
 295         return r;
 296 }
 297
 298 int ask_password_agent(
 299                 const char *message,
 300                 const char *icon,
 301                 usec_t until,
 302                 bool accept_cached,
 303                 char ***_passphrases) {
 304
 305         enum {
 306                 FD_SOCKET,
 307                 FD_SIGNAL,
 308                 _FD_MAX
 309         };
 310
 311         char temp[] = "/run/systemd/ask-password/tmp.XXXXXX";
 312         char final[sizeof(temp)] = "";
 313         int fd = -1, r;
 314         FILE *f = NULL;
 315         char *socket_name = NULL;
 316         int socket_fd = -1, signal_fd = -1;
 317         sigset_t mask, oldmask;
 318         struct pollfd pollfd[_FD_MAX];
 319         mode_t u;
 320
 321         assert(_passphrases);
 322
 323         assert_se(sigemptyset(&mask) == 0);
 324         sigset_add_many(&mask, SIGINT, SIGTERM, -1);
 325         assert_se(sigprocmask(SIG_BLOCK, &mask, &oldmask) == 0);
 326
 327         mkdir_p("/run/systemd/ask-password", 0755);
 328
 329         u = umask(0022);
 330         fd = mkostemp(temp, O_CLOEXEC|O_CREAT|O_WRONLY);
 331         umask(u);
 332
 333         if (fd < 0) {
 334                 log_error("Failed to create password file: %m");
 335                 r = -errno;
 336                 goto finish;
 337         }
 338
 339         fchmod(fd, 0644);
 340
 341         if (!(f = fdopen(fd, "w"))) {
 342                 log_error("Failed to allocate FILE: %m");
 343                 r = -errno;
 344                 goto finish;
 345         }
 346
 347         fd = -1;
 348
 349         if ((signal_fd = signalfd(-1, &mask, SFD_NONBLOCK|SFD_CLOEXEC)) < 0) {
 350                 log_error("signalfd(): %m");
 351                 r = -errno;
 352                 goto finish;
 353         }
 354
 355         if ((socket_fd = create_socket(&socket_name)) < 0) {
 356                 r = socket_fd;
 357                 goto finish;
 358         }
 359
 360         fprintf(f,
 361                 "[Ask]\n"
 362                 "PID=%lu\n"
 363                 "Socket=%s\n"
 364                 "AcceptCached=%i\n"
 365                 "NotAfter=%llu\n",
 366                 (unsigned long) getpid(),
 367                 socket_name,
 368                 accept_cached ? 1 : 0,
 369                 (unsigned long long) until);
 370
 371         if (message)
 372                 fprintf(f, "Message=%s\n", message);
 373
 374         if (icon)
 375                 fprintf(f, "Icon=%s\n", icon);
 376
 377         fflush(f);
 378
 379         if (ferror(f)) {
 380                 log_error("Failed to write query file: %m");
 381                 r = -errno;
 382                 goto finish;
 383         }
 384
 385         memcpy(final, temp, sizeof(temp));
 386
 387         final[sizeof(final)-11] = 'a';
 388         final[sizeof(final)-10] = 's';
 389         final[sizeof(final)-9] = 'k';
 390
 391         if (rename(temp, final) < 0) {
 392                 log_error("Failed to rename query file: %m");
 393                 r = -errno;
 394                 goto finish;
 395         }
 396
 397         zero(pollfd);
 398         pollfd[FD_SOCKET].fd = socket_fd;
 399         pollfd[FD_SOCKET].events = POLLIN;
 400         pollfd[FD_SIGNAL].fd = signal_fd;
 401         pollfd[FD_SIGNAL].events = POLLIN;
 402
 403         for (;;) {
 404                 char passphrase[LINE_MAX+1];
 405                 struct msghdr msghdr;
 406                 struct iovec iovec;
 407                 struct ucred *ucred;
 408                 union {
 409                         struct cmsghdr cmsghdr;
 410                         uint8_t buf[CMSG_SPACE(sizeof(struct ucred))];
 411                 } control;
 412                 ssize_t n;
 413                 int k;
 414                 usec_t t;
 415
 416                 t = now(CLOCK_MONOTONIC);
 417
 418                 if (until > 0 && until <= t) {
 419                         log_notice("Timed out");
 420                         r = -ETIME;
 421                         goto finish;
 422                 }
 423
 424                 if ((k = poll(pollfd, _FD_MAX, until > 0 ? (int) ((until-t)/USEC_PER_MSEC) : -1)) < 0) {
 425
 426                         if (errno == EINTR)
 427                                 continue;
 428
 429                         log_error("poll() failed: %m");
 430                         r = -errno;
 431                         goto finish;
 432                 }
 433
 434                 if (k <= 0) {
 435                         log_notice("Timed out");
 436                         r = -ETIME;
 437                         goto finish;
 438                 }
 439
 440                 if (pollfd[FD_SIGNAL].revents & POLLIN) {
 441                         r = -EINTR;
 442                         goto finish;
 443                 }
 444
 445                 if (pollfd[FD_SOCKET].revents != POLLIN) {
 446                         log_error("Unexpected poll() event.");
 447                         r = -EIO;
 448                         goto finish;
 449                 }
 450
 451                 zero(iovec);
 452                 iovec.iov_base = passphrase;
 453                 iovec.iov_len = sizeof(passphrase);
 454
 455                 zero(control);
 456                 zero(msghdr);
 457                 msghdr.msg_iov = &iovec;
 458                 msghdr.msg_iovlen = 1;
 459                 msghdr.msg_control = &control;
 460                 msghdr.msg_controllen = sizeof(control);
 461
 462                 if ((n = recvmsg(socket_fd, &msghdr, 0)) < 0) {
 463
 464                         if (errno == EAGAIN ||
 465                             errno == EINTR)
 466                                 continue;
 467
 468                         log_error("recvmsg() failed: %m");
 469                         r = -errno;
 470                         goto finish;
 471                 }
 472
 473                 if (n <= 0) {
 474                         log_error("Message too short");
 475                         continue;
 476                 }
 477
 478                 if (msghdr.msg_controllen < CMSG_LEN(sizeof(struct ucred)) ||
 479                     control.cmsghdr.cmsg_level != SOL_SOCKET ||
 480                     control.cmsghdr.cmsg_type != SCM_CREDENTIALS ||
 481                     control.cmsghdr.cmsg_len != CMSG_LEN(sizeof(struct ucred))) {
 482                         log_warning("Received message without credentials. Ignoring.");
 483                         continue;
 484                 }
 485
 486                 ucred = (struct ucred*) CMSG_DATA(&control.cmsghdr);
 487                 if (ucred->uid != 0) {
 488                         log_warning("Got request from unprivileged user. Ignoring.");
 489                         continue;
 490                 }
 491
 492                 if (passphrase[0] == '+') {
 493                         char **l;
 494
 495                         if (n == 1)
 496                                 l = strv_new("", NULL);
 497                         else
 498                                 l = strv_parse_nulstr(passphrase+1, n-1);
 499                                 /* An empty message refers to the empty password */
 500
 501                         if (!l) {
 502                                 r = -ENOMEM;
 503                                 goto finish;
 504                         }
 505
 506                         if (strv_length(l) <= 0) {
 507                                 strv_free(l);
 508                                 log_error("Invalid packet");
 509                                 continue;
 510                         }
 511
 512                         *_passphrases = l;
 513
 514                 } else if (passphrase[0] == '-') {
 515                         r = -ECANCELED;
 516                         goto finish;
 517                 } else {
 518                         log_error("Invalid packet");
 519                         continue;
 520                 }
 521
 522                 break;
 523         }
 524
 525         r = 0;
 526
 527 finish:
 528         if (fd >= 0)
 529                 close_nointr_nofail(fd);
 530
 531         if (socket_name) {
 532                 unlink(socket_name);
 533                 free(socket_name);
 534         }
 535
 536         if (socket_fd >= 0)
 537                 close_nointr_nofail(socket_fd);
 538
 539         if (signal_fd >= 0)
 540                 close_nointr_nofail(signal_fd);
 541
 542         if (f)
 543                 fclose(f);
 544
 545         unlink(temp);
 546
 547         if (final[0])
 548                 unlink(final);
 549
 550         assert_se(sigprocmask(SIG_SETMASK, &oldmask, NULL) == 0);
 551
 552         return r;
 553 }
 554
 555 int ask_password_auto(const char *message, const char *icon, usec_t until, bool accept_cached, char ***_passphrases) {
 556         assert(message);
 557         assert(_passphrases);
 558
 559         if (isatty(STDIN_FILENO)) {
 560                 int r;
 561                 char *s = NULL, **l = NULL;
 562
 563                 if ((r = ask_password_tty(message, until, NULL, &s)) < 0)
 564                         return r;
 565
 566                 l = strv_new(s, NULL);
 567                 free(s);
 568
 569                 if (!l)
 570                         return -ENOMEM;
 571
 572                 *_passphrases = l;
 573                 return r;
 574
 575         } else
 576                 return ask_password_agent(message, icon, until, accept_cached, _passphrases);
 577 }