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         enum {
  65                 POLL_TTY,
  66                 POLL_INOTIFY
  67         };
  68
  69         assert(message);
  70         assert(_passphrase);
  71
  72         if (flag_file) {
  73                 if ((notify = inotify_init1(IN_CLOEXEC|IN_NONBLOCK)) < 0) {
  74                         r = -errno;
  75                         goto finish;
  76                 }
  77
  78                 if (inotify_add_watch(notify, flag_file, IN_ATTRIB /* for the link count */) < 0) {
  79                         r = -errno;
  80                         goto finish;
  81                 }
  82         }
  83
  84         if ((ttyfd = open("/dev/tty", O_RDWR|O_NOCTTY|O_CLOEXEC)) >= 0) {
  85
  86                 if (tcgetattr(ttyfd, &old_termios) < 0) {
  87                         r = -errno;
  88                         goto finish;
  89                 }
  90
  91                 loop_write(ttyfd, "\x1B[1m", 4, false);
  92                 loop_write(ttyfd, message, strlen(message), false);
  93                 loop_write(ttyfd, " ", 1, false);
  94                 loop_write(ttyfd, "\x1B[0m", 4, false);
  95
  96                 new_termios = old_termios;
  97                 new_termios.c_lflag &= ~(ICANON|ECHO);
  98                 new_termios.c_cc[VMIN] = 1;
  99                 new_termios.c_cc[VTIME] = 0;
 100
 101                 if (tcsetattr(ttyfd, TCSADRAIN, &new_termios) < 0) {
 102                         r = -errno;
 103                         goto finish;
 104                 }
 105
 106                 reset_tty = true;
 107         }
 108
 109         zero(pollfd);
 110
 111         pollfd[POLL_TTY].fd = ttyfd >= 0 ? ttyfd : STDIN_FILENO;
 112         pollfd[POLL_TTY].events = POLLIN;
 113         pollfd[POLL_INOTIFY].fd = notify;
 114         pollfd[POLL_INOTIFY].events = POLLIN;
 115
 116         for (;;) {
 117                 char c;
 118                 int sleep_for = -1, k;
 119                 ssize_t n;
 120
 121                 if (until > 0) {
 122                         usec_t y;
 123
 124                         y = now(CLOCK_MONOTONIC);
 125
 126                         if (y > until) {
 127                                 r = -ETIME;
 128                                 goto finish;
 129                         }
 130
 131                         sleep_for = (int) ((until - y) / USEC_PER_MSEC);
 132                 }
 133
 134                 if (flag_file)
 135                         if (access(flag_file, F_OK) < 0) {
 136                                 r = -errno;
 137                                 goto finish;
 138                         }
 139
 140                 if ((k = poll(pollfd, notify > 0 ? 2 : 1, sleep_for)) < 0) {
 141
 142                         if (errno == EINTR)
 143                                 continue;
 144
 145                         r = -errno;
 146                         goto finish;
 147                 } else if (k == 0) {
 148                         r = -ETIME;
 149                         goto finish;
 150                 }
 151
 152                 if (notify > 0 && pollfd[POLL_INOTIFY].revents != 0)
 153                         flush_fd(notify);
 154
 155                 if (pollfd[POLL_TTY].revents == 0)
 156                         continue;
 157
 158                 if ((n = read(ttyfd >= 0 ? ttyfd : STDIN_FILENO, &c, 1)) < 0) {
 159
 160                         if (errno == EINTR || errno == EAGAIN)
 161                                 continue;
 162
 163                         r = -errno;
 164                         goto finish;
 165
 166                 } else if (n == 0)
 167                         break;
 168
 169                 if (c == '\n')
 170                         break;
 171                 else if (c == 21) { /* C-u */
 172
 173                         if (!silent_mode)
 174                                 backspace_chars(ttyfd, p);
 175                         p = 0;
 176
 177                 } else if (c == '\b' || c == 127) {
 178
 179                         if (p > 0) {
 180
 181                                 if (!silent_mode)
 182                                         backspace_chars(ttyfd, 1);
 183
 184                                 p--;
 185                         } else if (ttyfd >= 0)
 186                                 loop_write(ttyfd, "\a", 1, false);
 187
 188                 } else if (c == '\t' && !silent_mode) {
 189
 190                         backspace_chars(ttyfd, p);
 191                         silent_mode = true;
 192
 193                         if (ttyfd >= 0)
 194                                 loop_write(ttyfd, "(no echo) ", 10, false);
 195                 } else {
 196                         passphrase[p++] = c;
 197
 198                         if (!silent_mode && ttyfd >= 0)
 199                                 loop_write(ttyfd, "*", 1, false);
 200                 }
 201         }
 202
 203         passphrase[p] = 0;
 204
 205         if (!(*_passphrase = strdup(passphrase))) {
 206                 r = -ENOMEM;
 207                 goto finish;
 208         }
 209
 210         r = 0;
 211
 212 finish:
 213         if (notify >= 0)
 214                 close_nointr_nofail(notify);
 215
 216         if (ttyfd >= 0) {
 217
 218                 if (reset_tty) {
 219                         loop_write(ttyfd, "\n", 1, false);
 220                         tcsetattr(ttyfd, TCSADRAIN, &old_termios);
 221                 }
 222
 223                 close_nointr_nofail(ttyfd);
 224         }
 225
 226         return r;
 227 }
 228
 229 static int create_socket(char **name) {
 230         int fd;
 231         union {
 232                 struct sockaddr sa;
 233                 struct sockaddr_un un;
 234         } sa;
 235         int one = 1, r;
 236         char *c;
 237
 238         assert(name);
 239
 240         if ((fd = socket(AF_UNIX, SOCK_DGRAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0)) < 0) {
 241                 log_error("socket() failed: %m");
 242                 return -errno;
 243         }
 244
 245         zero(sa);
 246         sa.un.sun_family = AF_UNIX;
 247         snprintf(sa.un.sun_path, sizeof(sa.un.sun_path)-1, "/run/systemd/ask-password/sck.%llu", random_ull());
 248
 249         if (bind(fd, &sa.sa, offsetof(struct sockaddr_un, sun_path) + strlen(sa.un.sun_path)) < 0) {
 250                 r = -errno;
 251                 log_error("bind() failed: %m");
 252                 goto fail;
 253         }
 254
 255         if (setsockopt(fd, SOL_SOCKET, SO_PASSCRED, &one, sizeof(one)) < 0) {
 256                 r = -errno;
 257                 log_error("SO_PASSCRED failed: %m");
 258                 goto fail;
 259         }
 260
 261         if (!(c = strdup(sa.un.sun_path))) {
 262                 r = -ENOMEM;
 263                 log_error("Out of memory");
 264                 goto fail;
 265         }
 266
 267         *name = c;
 268         return fd;
 269
 270 fail:
 271         close_nointr_nofail(fd);
 272
 273         return r;
 274 }
 275
 276 int ask_password_agent(
 277                 const char *message,
 278                 const char *icon,
 279                 usec_t until,
 280                 bool accept_cached,
 281                 char ***_passphrases) {
 282
 283         enum {
 284                 FD_SOCKET,
 285                 FD_SIGNAL,
 286                 _FD_MAX
 287         };
 288
 289         char temp[] = "/run/systemd/ask-password/tmp.XXXXXX";
 290         char final[sizeof(temp)] = "";
 291         int fd = -1, r;
 292         FILE *f = NULL;
 293         char *socket_name = NULL;
 294         int socket_fd = -1, signal_fd = -1;
 295         sigset_t mask, oldmask;
 296         struct pollfd pollfd[_FD_MAX];
 297
 298         assert(_passphrases);
 299
 300         assert_se(sigemptyset(&mask) == 0);
 301         sigset_add_many(&mask, SIGINT, SIGTERM, -1);
 302         assert_se(sigprocmask(SIG_BLOCK, &mask, &oldmask) == 0);
 303
 304         mkdir_p("/run/systemd/ask-password", 0755);
 305
 306         if ((fd = mkostemp(temp, O_CLOEXEC|O_CREAT|O_WRONLY)) < 0) {
 307                 log_error("Failed to create password file: %m");
 308                 r = -errno;
 309                 goto finish;
 310         }
 311
 312         fchmod(fd, 0644);
 313
 314         if (!(f = fdopen(fd, "w"))) {
 315                 log_error("Failed to allocate FILE: %m");
 316                 r = -errno;
 317                 goto finish;
 318         }
 319
 320         fd = -1;
 321
 322         if ((signal_fd = signalfd(-1, &mask, SFD_NONBLOCK|SFD_CLOEXEC)) < 0) {
 323                 log_error("signalfd(): %m");
 324                 r = -errno;
 325                 goto finish;
 326         }
 327
 328         if ((socket_fd = create_socket(&socket_name)) < 0) {
 329                 r = socket_fd;
 330                 goto finish;
 331         }
 332
 333         fprintf(f,
 334                 "[Ask]\n"
 335                 "PID=%lu\n"
 336                 "Socket=%s\n"
 337                 "AcceptCached=%i\n"
 338                 "NotAfter=%llu\n",
 339                 (unsigned long) getpid(),
 340                 socket_name,
 341                 accept_cached ? 1 : 0,
 342                 (unsigned long long) until);
 343
 344         if (message)
 345                 fprintf(f, "Message=%s\n", message);
 346
 347         if (icon)
 348                 fprintf(f, "Icon=%s\n", icon);
 349
 350         fflush(f);
 351
 352         if (ferror(f)) {
 353                 log_error("Failed to write query file: %m");
 354                 r = -errno;
 355                 goto finish;
 356         }
 357
 358         memcpy(final, temp, sizeof(temp));
 359
 360         final[sizeof(final)-11] = 'a';
 361         final[sizeof(final)-10] = 's';
 362         final[sizeof(final)-9] = 'k';
 363
 364         if (rename(temp, final) < 0) {
 365                 log_error("Failed to rename query file: %m");
 366                 r = -errno;
 367                 goto finish;
 368         }
 369
 370         zero(pollfd);
 371         pollfd[FD_SOCKET].fd = socket_fd;
 372         pollfd[FD_SOCKET].events = POLLIN;
 373         pollfd[FD_SIGNAL].fd = signal_fd;
 374         pollfd[FD_SIGNAL].events = POLLIN;
 375
 376         for (;;) {
 377                 char passphrase[LINE_MAX+1];
 378                 struct msghdr msghdr;
 379                 struct iovec iovec;
 380                 struct ucred *ucred;
 381                 union {
 382                         struct cmsghdr cmsghdr;
 383                         uint8_t buf[CMSG_SPACE(sizeof(struct ucred))];
 384                 } control;
 385                 ssize_t n;
 386                 int k;
 387                 usec_t t;
 388
 389                 t = now(CLOCK_MONOTONIC);
 390
 391                 if (until <= t) {
 392                         log_notice("Timed out");
 393                         r = -ETIME;
 394                         goto finish;
 395                 }
 396
 397                 if ((k = poll(pollfd, _FD_MAX, (until-t)/USEC_PER_MSEC)) < 0) {
 398
 399                         if (errno == EINTR)
 400                                 continue;
 401
 402                         log_error("poll() failed: %m");
 403                         r = -errno;
 404                         goto finish;
 405                 }
 406
 407                 if (k <= 0) {
 408                         log_notice("Timed out");
 409                         r = -ETIME;
 410                         goto finish;
 411                 }
 412
 413                 if (pollfd[FD_SIGNAL].revents & POLLIN) {
 414                         r = -EINTR;
 415                         goto finish;
 416                 }
 417
 418                 if (pollfd[FD_SOCKET].revents != POLLIN) {
 419                         log_error("Unexpected poll() event.");
 420                         r = -EIO;
 421                         goto finish;
 422                 }
 423
 424                 zero(iovec);
 425                 iovec.iov_base = passphrase;
 426                 iovec.iov_len = sizeof(passphrase);
 427
 428                 zero(control);
 429                 zero(msghdr);
 430                 msghdr.msg_iov = &iovec;
 431                 msghdr.msg_iovlen = 1;
 432                 msghdr.msg_control = &control;
 433                 msghdr.msg_controllen = sizeof(control);
 434
 435                 if ((n = recvmsg(socket_fd, &msghdr, 0)) < 0) {
 436
 437                         if (errno == EAGAIN ||
 438                             errno == EINTR)
 439                                 continue;
 440
 441                         log_error("recvmsg() failed: %m");
 442                         r = -errno;
 443                         goto finish;
 444                 }
 445
 446                 if (n <= 0) {
 447                         log_error("Message too short");
 448                         continue;
 449                 }
 450
 451                 if (msghdr.msg_controllen < CMSG_LEN(sizeof(struct ucred)) ||
 452                     control.cmsghdr.cmsg_level != SOL_SOCKET ||
 453                     control.cmsghdr.cmsg_type != SCM_CREDENTIALS ||
 454                     control.cmsghdr.cmsg_len != CMSG_LEN(sizeof(struct ucred))) {
 455                         log_warning("Received message without credentials. Ignoring.");
 456                         continue;
 457                 }
 458
 459                 ucred = (struct ucred*) CMSG_DATA(&control.cmsghdr);
 460                 if (ucred->uid != 0) {
 461                         log_warning("Got request from unprivileged user. Ignoring.");
 462                         continue;
 463                 }
 464
 465                 if (passphrase[0] == '+') {
 466                         char **l;
 467
 468                         if (!(l = strv_parse_nulstr(passphrase+1, n-1))) {
 469                                 r = -ENOMEM;
 470                                 goto finish;
 471                         }
 472
 473                         if (strv_length(l) <= 0) {
 474                                 strv_free(l);
 475                                 log_error("Invalid packet");
 476                                 continue;
 477                         }
 478
 479                         *_passphrases = l;
 480
 481                 } else if (passphrase[0] == '-') {
 482                         r = -ECANCELED;
 483                         goto finish;
 484                 } else {
 485                         log_error("Invalid packet");
 486                         continue;
 487                 }
 488
 489                 break;
 490         }
 491
 492         r = 0;
 493
 494 finish:
 495         if (fd >= 0)
 496                 close_nointr_nofail(fd);
 497
 498         if (socket_name) {
 499                 unlink(socket_name);
 500                 free(socket_name);
 501         }
 502
 503         if (socket_fd >= 0)
 504                 close_nointr_nofail(socket_fd);
 505
 506         if (signal_fd >= 0)
 507                 close_nointr_nofail(signal_fd);
 508
 509         if (f)
 510                 fclose(f);
 511
 512         unlink(temp);
 513
 514         if (final[0])
 515                 unlink(final);
 516
 517         assert_se(sigprocmask(SIG_SETMASK, &oldmask, NULL) == 0);
 518
 519         return r;
 520 }
 521
 522 int ask_password_auto(const char *message, const char *icon, usec_t until, bool accept_cached, char ***_passphrases) {
 523         assert(message);
 524         assert(_passphrases);
 525
 526         if (isatty(STDIN_FILENO)) {
 527                 int r;
 528                 char *s = NULL, **l = NULL;
 529
 530                 if ((r = ask_password_tty(message, until, NULL, &s)) < 0)
 531                         return r;
 532
 533                 l = strv_new(s, NULL);
 534                 free(s);
 535
 536                 if (!l)
 537                         return -ENOMEM;
 538
 539                 *_passphrases = l;
 540                 return r;
 541
 542         } else
 543                 return ask_password_agent(message, icon, until, accept_cached, _passphrases);
 544 }