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
  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 int ask_password_tty(
  40                 const char *message,
  41                 usec_t until,
  42                 const char *flag_file,
  43                 char **_passphrase) {
  44
  45         struct termios old_termios, new_termios;
  46         char passphrase[LINE_MAX];
  47         size_t p = 0;
  48         int r, ttyfd = -1, notify = -1;
  49         struct pollfd pollfd[2];
  50         bool reset_tty = false;
  51         enum {
  52                 POLL_TTY,
  53                 POLL_INOTIFY
  54         };
  55
  56         assert(message);
  57         assert(_passphrase);
  58
  59         if (flag_file) {
  60                 if ((notify = inotify_init1(IN_CLOEXEC|IN_NONBLOCK)) < 0) {
  61                         r = -errno;
  62                         goto finish;
  63                 }
  64
  65                 if (inotify_add_watch(notify, flag_file, IN_ATTRIB /* for the link count */) < 0) {
  66                         r = -errno;
  67                         goto finish;
  68                 }
  69         }
  70
  71         if ((ttyfd = open("/dev/tty", O_RDWR|O_NOCTTY|O_CLOEXEC)) >= 0) {
  72
  73                 if (tcgetattr(ttyfd, &old_termios) < 0) {
  74                         r = -errno;
  75                         goto finish;
  76                 }
  77
  78                 loop_write(ttyfd, "\x1B[1m", 4, false);
  79                 loop_write(ttyfd, message, strlen(message), false);
  80                 loop_write(ttyfd, " ", 1, false);
  81                 loop_write(ttyfd, "\x1B[0m", 4, false);
  82
  83                 new_termios = old_termios;
  84                 new_termios.c_lflag &= ~(ICANON|ECHO);
  85                 new_termios.c_cc[VMIN] = 1;
  86                 new_termios.c_cc[VTIME] = 0;
  87
  88                 if (tcsetattr(ttyfd, TCSADRAIN, &new_termios) < 0) {
  89                         r = -errno;
  90                         goto finish;
  91                 }
  92
  93                 reset_tty = true;
  94         }
  95
  96         zero(pollfd);
  97
  98         pollfd[POLL_TTY].fd = ttyfd >= 0 ? ttyfd : STDIN_FILENO;
  99         pollfd[POLL_TTY].events = POLLIN;
 100         pollfd[POLL_INOTIFY].fd = notify;
 101         pollfd[POLL_INOTIFY].events = POLLIN;
 102
 103         for (;;) {
 104                 char c;
 105                 int sleep_for = -1, k;
 106                 ssize_t n;
 107
 108                 if (until > 0) {
 109                         usec_t y;
 110
 111                         y = now(CLOCK_MONOTONIC);
 112
 113                         if (y > until) {
 114                                 r = -ETIME;
 115                                 goto finish;
 116                         }
 117
 118                         sleep_for = (int) ((until - y) / USEC_PER_MSEC);
 119                 }
 120
 121                 if (flag_file)
 122                         if (access(flag_file, F_OK) < 0) {
 123                                 r = -errno;
 124                                 goto finish;
 125                         }
 126
 127                 if ((k = poll(pollfd, notify > 0 ? 2 : 1, sleep_for)) < 0) {
 128
 129                         if (errno == EINTR)
 130                                 continue;
 131
 132                         r = -errno;
 133                         goto finish;
 134                 } else if (k == 0) {
 135                         r = -ETIME;
 136                         goto finish;
 137                 }
 138
 139                 if (notify > 0 && pollfd[POLL_INOTIFY].revents != 0)
 140                         flush_fd(notify);
 141
 142                 if (pollfd[POLL_TTY].revents == 0)
 143                         continue;
 144
 145                 if ((n = read(ttyfd >= 0 ? ttyfd : STDIN_FILENO, &c, 1)) < 0) {
 146
 147                         if (errno == EINTR || errno == EAGAIN)
 148                                 continue;
 149
 150                         r = -errno;
 151                         goto finish;
 152
 153                 } else if (n == 0)
 154                         break;
 155
 156                 if (c == '\n')
 157                         break;
 158                 else if (c == 21) {
 159
 160                         while (p > 0) {
 161                                 p--;
 162
 163                                 if (ttyfd >= 0)
 164                                         loop_write(ttyfd, "\b \b", 3, false);
 165                         }
 166
 167                 } else if (c == '\b' || c == 127) {
 168                         if (p > 0) {
 169                                 p--;
 170
 171                                 if (ttyfd >= 0)
 172                                         loop_write(ttyfd, "\b \b", 3, false);
 173                         }
 174                 } else {
 175                         passphrase[p++] = c;
 176
 177                         if (ttyfd >= 0)
 178                                 loop_write(ttyfd, "*", 1, false);
 179                 }
 180         }
 181
 182         if (ttyfd >= 0)
 183
 184         passphrase[p] = 0;
 185
 186         if (!(*_passphrase = strdup(passphrase))) {
 187                 r = -ENOMEM;
 188                 goto finish;
 189         }
 190
 191         r = 0;
 192
 193 finish:
 194         if (notify >= 0)
 195                 close_nointr_nofail(notify);
 196
 197         if (ttyfd >= 0) {
 198
 199                 if (reset_tty) {
 200                         loop_write(ttyfd, "\n", 1, false);
 201                         tcsetattr(ttyfd, TCSADRAIN, &old_termios);
 202                 }
 203
 204                 close_nointr_nofail(ttyfd);
 205         }
 206
 207         return r;
 208 }
 209
 210 static int create_socket(char **name) {
 211         int fd;
 212         union {
 213                 struct sockaddr sa;
 214                 struct sockaddr_un un;
 215         } sa;
 216         int one = 1, r;
 217         char *c;
 218
 219         assert(name);
 220
 221         if ((fd = socket(AF_UNIX, SOCK_DGRAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0)) < 0) {
 222                 log_error("socket() failed: %m");
 223                 return -errno;
 224         }
 225
 226         zero(sa);
 227         sa.un.sun_family = AF_UNIX;
 228         snprintf(sa.un.sun_path, sizeof(sa.un.sun_path)-1, "/dev/.systemd/ask-password/sck.%llu", random_ull());
 229
 230         if (bind(fd, &sa.sa, offsetof(struct sockaddr_un, sun_path) + strlen(sa.un.sun_path)) < 0) {
 231                 r = -errno;
 232                 log_error("bind() failed: %m");
 233                 goto fail;
 234         }
 235
 236         if (setsockopt(fd, SOL_SOCKET, SO_PASSCRED, &one, sizeof(one)) < 0) {
 237                 r = -errno;
 238                 log_error("SO_PASSCRED failed: %m");
 239                 goto fail;
 240         }
 241
 242         if (!(c = strdup(sa.un.sun_path))) {
 243                 r = -ENOMEM;
 244                 log_error("Out of memory");
 245                 goto fail;
 246         }
 247
 248         *name = c;
 249         return fd;
 250
 251 fail:
 252         close_nointr_nofail(fd);
 253
 254         return r;
 255 }
 256
 257 int ask_password_agent(
 258                 const char *message,
 259                 const char *icon,
 260                 usec_t until,
 261                 bool accept_cached,
 262                 char ***_passphrases) {
 263
 264         enum {
 265                 FD_SOCKET,
 266                 FD_SIGNAL,
 267                 _FD_MAX
 268         };
 269
 270         char temp[] = "/dev/.systemd/ask-password/tmp.XXXXXX";
 271         char final[sizeof(temp)] = "";
 272         int fd = -1, r;
 273         FILE *f = NULL;
 274         char *socket_name = NULL;
 275         int socket_fd = -1, signal_fd = -1;
 276         sigset_t mask;
 277         struct pollfd pollfd[_FD_MAX];
 278
 279         assert(_passphrases);
 280
 281         mkdir_p("/dev/.systemd/ask-password", 0755);
 282
 283         if ((fd = mkostemp(temp, O_CLOEXEC|O_CREAT|O_WRONLY)) < 0) {
 284                 log_error("Failed to create password file: %m");
 285                 r = -errno;
 286                 goto finish;
 287         }
 288
 289         fchmod(fd, 0644);
 290
 291         if (!(f = fdopen(fd, "w"))) {
 292                 log_error("Failed to allocate FILE: %m");
 293                 r = -errno;
 294                 goto finish;
 295         }
 296
 297         fd = -1;
 298
 299         assert_se(sigemptyset(&mask) == 0);
 300         sigset_add_many(&mask, SIGINT, SIGTERM, -1);
 301         assert_se(sigprocmask(SIG_SETMASK, &mask, NULL) == 0);
 302
 303         if ((signal_fd = signalfd(-1, &mask, SFD_NONBLOCK|SFD_CLOEXEC)) < 0) {
 304                 log_error("signalfd(): %m");
 305                 r = -errno;
 306                 goto finish;
 307         }
 308
 309         if ((socket_fd = create_socket(&socket_name)) < 0) {
 310                 r = socket_fd;
 311                 goto finish;
 312         }
 313
 314         fprintf(f,
 315                 "[Ask]\n"
 316                 "PID=%lu\n"
 317                 "Socket=%s\n"
 318                 "AcceptCached=%i\n"
 319                 "NotAfter=%llu\n",
 320                 (unsigned long) getpid(),
 321                 socket_name,
 322                 accept_cached ? 1 : 0,
 323                 (unsigned long long) until);
 324
 325         if (message)
 326                 fprintf(f, "Message=%s\n", message);
 327
 328         if (icon)
 329                 fprintf(f, "Icon=%s\n", icon);
 330
 331         fflush(f);
 332
 333         if (ferror(f)) {
 334                 log_error("Failed to write query file: %m");
 335                 r = -errno;
 336                 goto finish;
 337         }
 338
 339         memcpy(final, temp, sizeof(temp));
 340
 341         final[sizeof(final)-11] = 'a';
 342         final[sizeof(final)-10] = 's';
 343         final[sizeof(final)-9] = 'k';
 344
 345         if (rename(temp, final) < 0) {
 346                 log_error("Failed to rename query file: %m");
 347                 r = -errno;
 348                 goto finish;
 349         }
 350
 351         zero(pollfd);
 352         pollfd[FD_SOCKET].fd = socket_fd;
 353         pollfd[FD_SOCKET].events = POLLIN;
 354         pollfd[FD_SIGNAL].fd = signal_fd;
 355         pollfd[FD_SIGNAL].events = POLLIN;
 356
 357         for (;;) {
 358                 char passphrase[LINE_MAX+1];
 359                 struct msghdr msghdr;
 360                 struct iovec iovec;
 361                 struct ucred *ucred;
 362                 union {
 363                         struct cmsghdr cmsghdr;
 364                         uint8_t buf[CMSG_SPACE(sizeof(struct ucred))];
 365                 } control;
 366                 ssize_t n;
 367                 int k;
 368                 usec_t t;
 369
 370                 t = now(CLOCK_MONOTONIC);
 371
 372                 if (until <= t) {
 373                         log_notice("Timed out");
 374                         r = -ETIME;
 375                         goto finish;
 376                 }
 377
 378                 if ((k = poll(pollfd, _FD_MAX, (until-t)/USEC_PER_MSEC)) < 0) {
 379
 380                         if (errno == EINTR)
 381                                 continue;
 382
 383                         log_error("poll() failed: %m");
 384                         r = -errno;
 385                         goto finish;
 386                 }
 387
 388                 if (k <= 0) {
 389                         log_notice("Timed out");
 390                         r = -ETIME;
 391                         goto finish;
 392                 }
 393
 394                 if (pollfd[FD_SIGNAL].revents & POLLIN) {
 395                         r = -EINTR;
 396                         goto finish;
 397                 }
 398
 399                 if (pollfd[FD_SOCKET].revents != POLLIN) {
 400                         log_error("Unexpected poll() event.");
 401                         r = -EIO;
 402                         goto finish;
 403                 }
 404
 405                 zero(iovec);
 406                 iovec.iov_base = passphrase;
 407                 iovec.iov_len = sizeof(passphrase);
 408
 409                 zero(control);
 410                 zero(msghdr);
 411                 msghdr.msg_iov = &iovec;
 412                 msghdr.msg_iovlen = 1;
 413                 msghdr.msg_control = &control;
 414                 msghdr.msg_controllen = sizeof(control);
 415
 416                 if ((n = recvmsg(socket_fd, &msghdr, 0)) < 0) {
 417
 418                         if (errno == EAGAIN ||
 419                             errno == EINTR)
 420                                 continue;
 421
 422                         log_error("recvmsg() failed: %m");
 423                         r = -errno;
 424                         goto finish;
 425                 }
 426
 427                 if (n <= 0) {
 428                         log_error("Message too short");
 429                         continue;
 430                 }
 431
 432                 if (msghdr.msg_controllen < CMSG_LEN(sizeof(struct ucred)) ||
 433                     control.cmsghdr.cmsg_level != SOL_SOCKET ||
 434                     control.cmsghdr.cmsg_type != SCM_CREDENTIALS ||
 435                     control.cmsghdr.cmsg_len != CMSG_LEN(sizeof(struct ucred))) {
 436                         log_warning("Received message without credentials. Ignoring.");
 437                         continue;
 438                 }
 439
 440                 ucred = (struct ucred*) CMSG_DATA(&control.cmsghdr);
 441                 if (ucred->uid != 0) {
 442                         log_warning("Got request from unprivileged user. Ignoring.");
 443                         continue;
 444                 }
 445
 446                 if (passphrase[0] == '+') {
 447                         char **l;
 448
 449                         if (!(l = strv_parse_nulstr(passphrase+1, n-1))) {
 450                                 r = -ENOMEM;
 451                                 goto finish;
 452                         }
 453
 454                         if (strv_length(l) <= 0) {
 455                                 strv_free(l);
 456                                 log_error("Invalid packet");
 457                                 continue;
 458                         }
 459
 460                         *_passphrases = l;
 461
 462                 } else if (passphrase[0] == '-') {
 463                         r = -ECANCELED;
 464                         goto finish;
 465                 } else {
 466                         log_error("Invalid packet");
 467                         continue;
 468                 }
 469
 470                 break;
 471         }
 472
 473         r = 0;
 474
 475 finish:
 476         if (fd >= 0)
 477                 close_nointr_nofail(fd);
 478
 479         if (socket_name) {
 480                 unlink(socket_name);
 481                 free(socket_name);
 482         }
 483
 484         if (socket_fd >= 0)
 485                 close_nointr_nofail(socket_fd);
 486
 487         if (signal_fd >= 0)
 488                 close_nointr_nofail(signal_fd);
 489
 490         if (f)
 491                 fclose(f);
 492
 493         unlink(temp);
 494
 495         if (final[0])
 496                 unlink(final);
 497
 498         return r;
 499 }
 500
 501 int ask_password_auto(const char *message, const char *icon, usec_t until, bool accept_cached, char ***_passphrases) {
 502         assert(message);
 503         assert(_passphrases);
 504
 505         if (isatty(STDIN_FILENO)) {
 506                 int r;
 507                 char *s = NULL, **l = NULL;
 508
 509                 if ((r = ask_password_tty(message, until, NULL, &s)) < 0)
 510                         return r;
 511
 512                 l = strv_new(s, NULL);
 513                 free(s);
 514
 515                 if (!l)
 516                         return -ENOMEM;
 517
 518                 *_passphrases = l;
 519                 return r;
 520
 521         } else
 522                 return ask_password_agent(message, icon, until, accept_cached, _passphrases);
 523 }