src/shared/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 Lesser General Public License as published by
  10   the Free Software Foundation; either version 2.1 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   Lesser General Public License for more details.
  17
  18   You should have received a copy of the GNU Lesser 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 }