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 <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 "formats-util.h"
  36 #include "mkdir.h"
  37 #include "strv.h"
  38 #include "random-util.h"
  39
  40 #include "ask-password-api.h"
  41
  42 static void backspace_chars(int ttyfd, size_t p) {
  43
  44         if (ttyfd < 0)
  45                 return;
  46
  47         while (p > 0) {
  48                 p--;
  49
  50                 loop_write(ttyfd, "\b \b", 3, false);
  51         }
  52 }
  53
  54 int ask_password_tty(
  55                 const char *message,
  56                 usec_t until,
  57                 bool echo,
  58                 const char *flag_file,
  59                 char **_passphrase) {
  60
  61         struct termios old_termios, new_termios;
  62         char passphrase[LINE_MAX], *x;
  63         size_t p = 0;
  64         int r;
  65         _cleanup_close_ int ttyfd = -1, notify = -1;
  66         struct pollfd pollfd[2];
  67         bool reset_tty = false;
  68         bool silent_mode = false;
  69         bool dirty = false;
  70         enum {
  71                 POLL_TTY,
  72                 POLL_INOTIFY
  73         };
  74
  75         assert(message);
  76         assert(_passphrase);
  77
  78         if (flag_file) {
  79                 notify = inotify_init1(IN_CLOEXEC|IN_NONBLOCK);
  80                 if (notify < 0) {
  81                         r = -errno;
  82                         goto finish;
  83                 }
  84
  85                 if (inotify_add_watch(notify, flag_file, IN_ATTRIB /* for the link count */) < 0) {
  86                         r = -errno;
  87                         goto finish;
  88                 }
  89         }
  90
  91         ttyfd = open("/dev/tty", O_RDWR|O_NOCTTY|O_CLOEXEC);
  92         if (ttyfd >= 0) {
  93
  94                 if (tcgetattr(ttyfd, &old_termios) < 0) {
  95                         r = -errno;
  96                         goto finish;
  97                 }
  98
  99                 loop_write(ttyfd, ANSI_HIGHLIGHT_ON, sizeof(ANSI_HIGHLIGHT_ON)-1, false);
 100                 loop_write(ttyfd, message, strlen(message), false);
 101                 loop_write(ttyfd, " ", 1, false);
 102                 loop_write(ttyfd, ANSI_HIGHLIGHT_OFF, sizeof(ANSI_HIGHLIGHT_OFF)-1, false);
 103
 104                 new_termios = old_termios;
 105                 new_termios.c_lflag &= ~(ICANON|ECHO);
 106                 new_termios.c_cc[VMIN] = 1;
 107                 new_termios.c_cc[VTIME] = 0;
 108
 109                 if (tcsetattr(ttyfd, TCSADRAIN, &new_termios) < 0) {
 110                         r = -errno;
 111                         goto finish;
 112                 }
 113
 114                 reset_tty = true;
 115         }
 116
 117         zero(pollfd);
 118         pollfd[POLL_TTY].fd = ttyfd >= 0 ? ttyfd : STDIN_FILENO;
 119         pollfd[POLL_TTY].events = POLLIN;
 120         pollfd[POLL_INOTIFY].fd = notify;
 121         pollfd[POLL_INOTIFY].events = POLLIN;
 122
 123         for (;;) {
 124                 char c;
 125                 int sleep_for = -1, k;
 126                 ssize_t n;
 127
 128                 if (until > 0) {
 129                         usec_t y;
 130
 131                         y = now(CLOCK_MONOTONIC);
 132
 133                         if (y > until) {
 134                                 r = -ETIME;
 135                                 goto finish;
 136                         }
 137
 138                         sleep_for = (int) ((until - y) / USEC_PER_MSEC);
 139                 }
 140
 141                 if (flag_file)
 142                         if (access(flag_file, F_OK) < 0) {
 143                                 r = -errno;
 144                                 goto finish;
 145                         }
 146
 147                 k = poll(pollfd, notify > 0 ? 2 : 1, sleep_for);
 148                 if (k < 0) {
 149                         if (errno == EINTR)
 150                                 continue;
 151
 152                         r = -errno;
 153                         goto finish;
 154                 } else if (k == 0) {
 155                         r = -ETIME;
 156                         goto finish;
 157                 }
 158
 159                 if (notify > 0 && pollfd[POLL_INOTIFY].revents != 0)
 160                         flush_fd(notify);
 161
 162                 if (pollfd[POLL_TTY].revents == 0)
 163                         continue;
 164
 165                 n = read(ttyfd >= 0 ? ttyfd : STDIN_FILENO, &c, 1);
 166                 if (n < 0) {
 167                         if (errno == EINTR || errno == EAGAIN)
 168                                 continue;
 169
 170                         r = -errno;
 171                         goto finish;
 172
 173                 } else if (n == 0)
 174                         break;
 175
 176                 if (c == '\n')
 177                         break;
 178                 else if (c == 21) { /* C-u */
 179
 180                         if (!silent_mode)
 181                                 backspace_chars(ttyfd, p);
 182                         p = 0;
 183
 184                 } else if (c == '\b' || c == 127) {
 185
 186                         if (p > 0) {
 187
 188                                 if (!silent_mode)
 189                                         backspace_chars(ttyfd, 1);
 190
 191                                 p--;
 192                         } else if (!dirty && !silent_mode) {
 193
 194                                 silent_mode = true;
 195
 196                                 /* There are two ways to enter silent
 197                                  * mode. Either by pressing backspace
 198                                  * as first key (and only as first key),
 199                                  * or ... */
 200                                 if (ttyfd >= 0)
 201                                         loop_write(ttyfd, "(no echo) ", 10, false);
 202
 203                         } else if (ttyfd >= 0)
 204                                 loop_write(ttyfd, "\a", 1, false);
 205
 206                 } else if (c == '\t' && !silent_mode) {
 207
 208                         backspace_chars(ttyfd, p);
 209                         silent_mode = true;
 210
 211                         /* ... or by pressing TAB at any time. */
 212
 213                         if (ttyfd >= 0)
 214                                 loop_write(ttyfd, "(no echo) ", 10, false);
 215                 } else {
 216                         if (p >= sizeof(passphrase)-1) {
 217                                 loop_write(ttyfd, "\a", 1, false);
 218                                 continue;
 219                         }
 220
 221                         passphrase[p++] = c;
 222
 223                         if (!silent_mode && ttyfd >= 0)
 224                                 loop_write(ttyfd, echo ? &c : "*", 1, false);
 225
 226                         dirty = true;
 227                 }
 228         }
 229
 230         x = strndup(passphrase, p);
 231         if (!x) {
 232                 r = -ENOMEM;
 233                 goto finish;
 234         }
 235
 236         *_passphrase = x;
 237         r = 0;
 238
 239 finish:
 240         if (ttyfd >= 0 && reset_tty) {
 241                 loop_write(ttyfd, "\n", 1, false);
 242                 tcsetattr(ttyfd, TCSADRAIN, &old_termios);
 243         }
 244
 245         return r;
 246 }
 247
 248 static int create_socket(char **name) {
 249         int fd;
 250         union {
 251                 struct sockaddr sa;
 252                 struct sockaddr_un un;
 253         } sa = {
 254                 .un.sun_family = AF_UNIX,
 255         };
 256         int one = 1;
 257         int r = 0;
 258         char *c;
 259
 260         assert(name);
 261
 262         fd = socket(AF_UNIX, SOCK_DGRAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0);
 263         if (fd < 0)
 264                 return log_error_errno(errno, "socket() failed: %m");
 265
 266         snprintf(sa.un.sun_path, sizeof(sa.un.sun_path)-1, "/run/systemd/ask-password/sck.%" PRIx64, random_u64());
 267
 268         RUN_WITH_UMASK(0177) {
 269                 r = bind(fd, &sa.sa, offsetof(struct sockaddr_un, sun_path) + strlen(sa.un.sun_path));
 270         }
 271
 272         if (r < 0) {
 273                 r = -errno;
 274                 log_error_errno(errno, "bind(%s) failed: %m", sa.un.sun_path);
 275                 goto fail;
 276         }
 277
 278         if (setsockopt(fd, SOL_SOCKET, SO_PASSCRED, &one, sizeof(one)) < 0) {
 279                 r = -errno;
 280                 log_error_errno(errno, "SO_PASSCRED failed: %m");
 281                 goto fail;
 282         }
 283
 284         c = strdup(sa.un.sun_path);
 285         if (!c) {
 286                 r = log_oom();
 287                 goto fail;
 288         }
 289
 290         *name = c;
 291         return fd;
 292
 293 fail:
 294         safe_close(fd);
 295
 296         return r;
 297 }
 298
 299 int ask_password_agent(
 300                 const char *message,
 301                 const char *icon,
 302                 const char *id,
 303                 usec_t until,
 304                 bool echo,
 305                 bool accept_cached,
 306                 char ***_passphrases) {
 307
 308         enum {
 309                 FD_SOCKET,
 310                 FD_SIGNAL,
 311                 _FD_MAX
 312         };
 313
 314         char temp[] = "/run/systemd/ask-password/tmp.XXXXXX";
 315         char final[sizeof(temp)] = "";
 316         _cleanup_fclose_ FILE *f = NULL;
 317         _cleanup_free_ char *socket_name = NULL;
 318         _cleanup_close_ int socket_fd = -1, signal_fd = -1, fd = -1;
 319         sigset_t mask, oldmask;
 320         struct pollfd pollfd[_FD_MAX];
 321         int r;
 322
 323         assert(_passphrases);
 324
 325         assert_se(sigemptyset(&mask) == 0);
 326         sigset_add_many(&mask, SIGINT, SIGTERM, -1);
 327         assert_se(sigprocmask(SIG_BLOCK, &mask, &oldmask) == 0);
 328
 329         mkdir_p_label("/run/systemd/ask-password", 0755);
 330
 331         fd = mkostemp_safe(temp, O_WRONLY|O_CLOEXEC);
 332         if (fd < 0) {
 333                 log_error_errno(errno, "Failed to create password file: %m");
 334                 r = -errno;
 335                 goto finish;
 336         }
 337
 338         fchmod(fd, 0644);
 339
 340         f = fdopen(fd, "w");
 341         if (!f) {
 342                 log_error_errno(errno, "Failed to allocate FILE: %m");
 343                 r = -errno;
 344                 goto finish;
 345         }
 346
 347         fd = -1;
 348
 349         signal_fd = signalfd(-1, &mask, SFD_NONBLOCK|SFD_CLOEXEC);
 350         if (signal_fd < 0) {
 351                 log_error_errno(errno, "signalfd(): %m");
 352                 r = -errno;
 353                 goto finish;
 354         }
 355
 356         socket_fd = create_socket(&socket_name);
 357         if (socket_fd < 0) {
 358                 r = socket_fd;
 359                 goto finish;
 360         }
 361
 362         fprintf(f,
 363                 "[Ask]\n"
 364                 "PID="PID_FMT"\n"
 365                 "Socket=%s\n"
 366                 "AcceptCached=%i\n"
 367                 "Echo=%i\n"
 368                 "NotAfter="USEC_FMT"\n",
 369                 getpid(),
 370                 socket_name,
 371                 accept_cached ? 1 : 0,
 372                 echo ? 1 : 0,
 373                 until);
 374
 375         if (message)
 376                 fprintf(f, "Message=%s\n", message);
 377
 378         if (icon)
 379                 fprintf(f, "Icon=%s\n", icon);
 380
 381         if (id)
 382                 fprintf(f, "Id=%s\n", id);
 383
 384         fflush(f);
 385
 386         if (ferror(f)) {
 387                 log_error_errno(errno, "Failed to write query file: %m");
 388                 r = -errno;
 389                 goto finish;
 390         }
 391
 392         memcpy(final, temp, sizeof(temp));
 393
 394         final[sizeof(final)-11] = 'a';
 395         final[sizeof(final)-10] = 's';
 396         final[sizeof(final)-9] = 'k';
 397
 398         if (rename(temp, final) < 0) {
 399                 log_error_errno(errno, "Failed to rename query file: %m");
 400                 r = -errno;
 401                 goto finish;
 402         }
 403
 404         zero(pollfd);
 405         pollfd[FD_SOCKET].fd = socket_fd;
 406         pollfd[FD_SOCKET].events = POLLIN;
 407         pollfd[FD_SIGNAL].fd = signal_fd;
 408         pollfd[FD_SIGNAL].events = POLLIN;
 409
 410         for (;;) {
 411                 char passphrase[LINE_MAX+1];
 412                 struct msghdr msghdr;
 413                 struct iovec iovec;
 414                 struct ucred *ucred;
 415                 union {
 416                         struct cmsghdr cmsghdr;
 417                         uint8_t buf[CMSG_SPACE(sizeof(struct ucred))];
 418                 } control;
 419                 ssize_t n;
 420                 int k;
 421                 usec_t t;
 422
 423                 t = now(CLOCK_MONOTONIC);
 424
 425                 if (until > 0 && until <= t) {
 426                         log_notice("Timed out");
 427                         r = -ETIME;
 428                         goto finish;
 429                 }
 430
 431                 k = poll(pollfd, _FD_MAX, until > 0 ? (int) ((until-t)/USEC_PER_MSEC) : -1);
 432                 if (k < 0) {
 433                         if (errno == EINTR)
 434                                 continue;
 435
 436                         log_error_errno(errno, "poll() failed: %m");
 437                         r = -errno;
 438                         goto finish;
 439                 }
 440
 441                 if (k <= 0) {
 442                         log_notice("Timed out");
 443                         r = -ETIME;
 444                         goto finish;
 445                 }
 446
 447                 if (pollfd[FD_SIGNAL].revents & POLLIN) {
 448                         r = -EINTR;
 449                         goto finish;
 450                 }
 451
 452                 if (pollfd[FD_SOCKET].revents != POLLIN) {
 453                         log_error("Unexpected poll() event.");
 454                         r = -EIO;
 455                         goto finish;
 456                 }
 457
 458                 zero(iovec);
 459                 iovec.iov_base = passphrase;
 460                 iovec.iov_len = sizeof(passphrase);
 461
 462                 zero(control);
 463                 zero(msghdr);
 464                 msghdr.msg_iov = &iovec;
 465                 msghdr.msg_iovlen = 1;
 466                 msghdr.msg_control = &control;
 467                 msghdr.msg_controllen = sizeof(control);
 468
 469                 n = recvmsg(socket_fd, &msghdr, 0);
 470                 if (n < 0) {
 471                         if (errno == EAGAIN ||
 472                             errno == EINTR)
 473                                 continue;
 474
 475                         log_error_errno(errno, "recvmsg() failed: %m");
 476                         r = -errno;
 477                         goto finish;
 478                 }
 479
 480                 cmsg_close_all(&msghdr);
 481
 482                 if (n <= 0) {
 483                         log_error("Message too short");
 484                         continue;
 485                 }
 486
 487                 if (msghdr.msg_controllen < CMSG_LEN(sizeof(struct ucred)) ||
 488                     control.cmsghdr.cmsg_level != SOL_SOCKET ||
 489                     control.cmsghdr.cmsg_type != SCM_CREDENTIALS ||
 490                     control.cmsghdr.cmsg_len != CMSG_LEN(sizeof(struct ucred))) {
 491                         log_warning("Received message without credentials. Ignoring.");
 492                         continue;
 493                 }
 494
 495                 ucred = (struct ucred*) CMSG_DATA(&control.cmsghdr);
 496                 if (ucred->uid != 0) {
 497                         log_warning("Got request from unprivileged user. Ignoring.");
 498                         continue;
 499                 }
 500
 501                 if (passphrase[0] == '+') {
 502                         char **l;
 503
 504                         if (n == 1)
 505                                 l = strv_new("", NULL);
 506                         else
 507                                 l = strv_parse_nulstr(passphrase+1, n-1);
 508                                 /* An empty message refers to the empty password */
 509
 510                         if (!l) {
 511                                 r = -ENOMEM;
 512                                 goto finish;
 513                         }
 514
 515                         if (strv_length(l) <= 0) {
 516                                 strv_free(l);
 517                                 log_error("Invalid packet");
 518                                 continue;
 519                         }
 520
 521                         *_passphrases = l;
 522
 523                 } else if (passphrase[0] == '-') {
 524                         r = -ECANCELED;
 525                         goto finish;
 526                 } else {
 527                         log_error("Invalid packet");
 528                         continue;
 529                 }
 530
 531                 break;
 532         }
 533
 534         r = 0;
 535
 536 finish:
 537         if (socket_name)
 538                 unlink(socket_name);
 539
 540         unlink(temp);
 541
 542         if (final[0])
 543                 unlink(final);
 544
 545         assert_se(sigprocmask(SIG_SETMASK, &oldmask, NULL) == 0);
 546
 547         return r;
 548 }
 549
 550 int ask_password_auto(const char *message, const char *icon, const char *id,
 551                       usec_t until, bool accept_cached, char ***_passphrases) {
 552         assert(message);
 553         assert(_passphrases);
 554
 555         if (isatty(STDIN_FILENO)) {
 556                 int r;
 557                 char *s = NULL, **l = NULL;
 558
 559                 r = ask_password_tty(message, until, false, NULL, &s);
 560                 if (r < 0)
 561                         return r;
 562
 563                 r = strv_consume(&l, s);
 564                 if (r < 0)
 565                         return r;
 566
 567                 *_passphrases = l;
 568                 return r;
 569         } else
 570                 return ask_password_agent(message, icon, id, until, false, accept_cached, _passphrases);
 571 }