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 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         bool silent_mode = false;
  52         enum {
  53                 POLL_TTY,
  54                 POLL_INOTIFY
  55         };
  56
  57         assert(message);
  58         assert(_passphrase);
  59
  60         if (flag_file) {
  61                 if ((notify = inotify_init1(IN_CLOEXEC|IN_NONBLOCK)) < 0) {
  62                         r = -errno;
  63                         goto finish;
  64                 }
  65
  66                 if (inotify_add_watch(notify, flag_file, IN_ATTRIB /* for the link count */) < 0) {
  67                         r = -errno;
  68                         goto finish;
  69                 }
  70         }
  71
  72         if ((ttyfd = open("/dev/tty", O_RDWR|O_NOCTTY|O_CLOEXEC)) >= 0) {
  73
  74                 if (tcgetattr(ttyfd, &old_termios) < 0) {
  75                         r = -errno;
  76                         goto finish;
  77                 }
  78
  79                 loop_write(ttyfd, "\x1B[1m", 4, false);
  80                 loop_write(ttyfd, message, strlen(message), false);
  81                 loop_write(ttyfd, " ", 1, false);
  82                 loop_write(ttyfd, "\x1B[0m", 4, false);
  83
  84                 new_termios = old_termios;
  85                 new_termios.c_lflag &= ~(ICANON|ECHO);
  86                 new_termios.c_cc[VMIN] = 1;
  87                 new_termios.c_cc[VTIME] = 0;
  88
  89                 if (tcsetattr(ttyfd, TCSADRAIN, &new_termios) < 0) {
  90                         r = -errno;
  91                         goto finish;
  92                 }
  93
  94                 reset_tty = true;
  95         }
  96
  97         zero(pollfd);
  98
  99         pollfd[POLL_TTY].fd = ttyfd >= 0 ? ttyfd : STDIN_FILENO;
 100         pollfd[POLL_TTY].events = POLLIN;
 101         pollfd[POLL_INOTIFY].fd = notify;
 102         pollfd[POLL_INOTIFY].events = POLLIN;
 103
 104         for (;;) {
 105                 char c;
 106                 int sleep_for = -1, k;
 107                 ssize_t n;
 108
 109                 if (until > 0) {
 110                         usec_t y;
 111
 112                         y = now(CLOCK_MONOTONIC);
 113
 114                         if (y > until) {
 115                                 r = -ETIME;
 116                                 goto finish;
 117                         }
 118
 119                         sleep_for = (int) ((until - y) / USEC_PER_MSEC);
 120                 }
 121
 122                 if (flag_file)
 123                         if (access(flag_file, F_OK) < 0) {
 124                                 r = -errno;
 125                                 goto finish;
 126                         }
 127
 128                 if ((k = poll(pollfd, notify > 0 ? 2 : 1, sleep_for)) < 0) {
 129
 130                         if (errno == EINTR)
 131                                 continue;
 132
 133                         r = -errno;
 134                         goto finish;
 135                 } else if (k == 0) {
 136                         r = -ETIME;
 137                         goto finish;
 138                 }
 139
 140                 if (notify > 0 && pollfd[POLL_INOTIFY].revents != 0)
 141                         flush_fd(notify);
 142
 143                 if (pollfd[POLL_TTY].revents == 0)
 144                         continue;
 145
 146                 if ((n = read(ttyfd >= 0 ? ttyfd : STDIN_FILENO, &c, 1)) < 0) {
 147
 148                         if (errno == EINTR || errno == EAGAIN)
 149                                 continue;
 150
 151                         r = -errno;
 152                         goto finish;
 153
 154                 } else if (n == 0)
 155                         break;
 156
 157                 if (c == '\n')
 158                         break;
 159                 else if (c == 21) {
 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 && !silent_mode) {
 169                                 silent_mode = true;
 170                                 loop_write(ttyfd, "(no echo) ", 10, false);
 171                         } else if (p > 0) {
 172                                 p--;
 173
 174                                 if (ttyfd >= 0)
 175                                         loop_write(ttyfd, "\b \b", 3, false);
 176                         }
 177                 } else {
 178                         passphrase[p++] = c;
 179
 180                         if (!silent_mode && ttyfd >= 0)
 181                                 loop_write(ttyfd, "*", 1, false);
 182                 }
 183         }
 184
 185         passphrase[p] = 0;
 186
 187         if (!(*_passphrase = strdup(passphrase))) {
 188                 r = -ENOMEM;
 189                 goto finish;
 190         }
 191
 192         r = 0;
 193
 194 finish:
 195         if (notify >= 0)
 196                 close_nointr_nofail(notify);
 197
 198         if (ttyfd >= 0) {
 199
 200                 if (reset_tty) {
 201                         loop_write(ttyfd, "\n", 1, false);
 202                         tcsetattr(ttyfd, TCSADRAIN, &old_termios);
 203                 }
 204
 205                 close_nointr_nofail(ttyfd);
 206         }
 207
 208         return r;
 209 }
 210
 211 static int create_socket(char **name) {
 212         int fd;
 213         union {
 214                 struct sockaddr sa;
 215                 struct sockaddr_un un;
 216         } sa;
 217         int one = 1, r;
 218         char *c;
 219
 220         assert(name);
 221
 222         if ((fd = socket(AF_UNIX, SOCK_DGRAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0)) < 0) {
 223                 log_error("socket() failed: %m");
 224                 return -errno;
 225         }
 226
 227         zero(sa);
 228         sa.un.sun_family = AF_UNIX;
 229         snprintf(sa.un.sun_path, sizeof(sa.un.sun_path)-1, "/run/systemd/ask-password/sck.%llu", random_ull());
 230
 231         if (bind(fd, &sa.sa, offsetof(struct sockaddr_un, sun_path) + strlen(sa.un.sun_path)) < 0) {
 232                 r = -errno;
 233                 log_error("bind() failed: %m");
 234                 goto fail;
 235         }
 236
 237         if (setsockopt(fd, SOL_SOCKET, SO_PASSCRED, &one, sizeof(one)) < 0) {
 238                 r = -errno;
 239                 log_error("SO_PASSCRED failed: %m");
 240                 goto fail;
 241         }
 242
 243         if (!(c = strdup(sa.un.sun_path))) {
 244                 r = -ENOMEM;
 245                 log_error("Out of memory");
 246                 goto fail;
 247         }
 248
 249         *name = c;
 250         return fd;
 251
 252 fail:
 253         close_nointr_nofail(fd);
 254
 255         return r;
 256 }
 257
 258 int ask_password_agent(
 259                 const char *message,
 260                 const char *icon,
 261                 usec_t until,
 262                 bool accept_cached,
 263                 char ***_passphrases) {
 264
 265         enum {
 266                 FD_SOCKET,
 267                 FD_SIGNAL,
 268                 _FD_MAX
 269         };
 270
 271         char temp[] = "/run/systemd/ask-password/tmp.XXXXXX";
 272         char final[sizeof(temp)] = "";
 273         int fd = -1, r;
 274         FILE *f = NULL;
 275         char *socket_name = NULL;
 276         int socket_fd = -1, signal_fd = -1;
 277         sigset_t mask, oldmask;
 278         struct pollfd pollfd[_FD_MAX];
 279
 280         assert(_passphrases);
 281
 282         assert_se(sigemptyset(&mask) == 0);
 283         sigset_add_many(&mask, SIGINT, SIGTERM, -1);
 284         assert_se(sigprocmask(SIG_BLOCK, &mask, &oldmask) == 0);
 285
 286         mkdir_p("/run/systemd/ask-password", 0755);
 287
 288         if ((fd = mkostemp(temp, O_CLOEXEC|O_CREAT|O_WRONLY)) < 0) {
 289                 log_error("Failed to create password file: %m");
 290                 r = -errno;
 291                 goto finish;
 292         }
 293
 294         fchmod(fd, 0644);
 295
 296         if (!(f = fdopen(fd, "w"))) {
 297                 log_error("Failed to allocate FILE: %m");
 298                 r = -errno;
 299                 goto finish;
 300         }
 301
 302         fd = -1;
 303
 304         if ((signal_fd = signalfd(-1, &mask, SFD_NONBLOCK|SFD_CLOEXEC)) < 0) {
 305                 log_error("signalfd(): %m");
 306                 r = -errno;
 307                 goto finish;
 308         }
 309
 310         if ((socket_fd = create_socket(&socket_name)) < 0) {
 311                 r = socket_fd;
 312                 goto finish;
 313         }
 314
 315         fprintf(f,
 316                 "[Ask]\n"
 317                 "PID=%lu\n"
 318                 "Socket=%s\n"
 319                 "AcceptCached=%i\n"
 320                 "NotAfter=%llu\n",
 321                 (unsigned long) getpid(),
 322                 socket_name,
 323                 accept_cached ? 1 : 0,
 324                 (unsigned long long) until);
 325
 326         if (message)
 327                 fprintf(f, "Message=%s\n", message);
 328
 329         if (icon)
 330                 fprintf(f, "Icon=%s\n", icon);
 331
 332         fflush(f);
 333
 334         if (ferror(f)) {
 335                 log_error("Failed to write query file: %m");
 336                 r = -errno;
 337                 goto finish;
 338         }
 339
 340         memcpy(final, temp, sizeof(temp));
 341
 342         final[sizeof(final)-11] = 'a';
 343         final[sizeof(final)-10] = 's';
 344         final[sizeof(final)-9] = 'k';
 345
 346         if (rename(temp, final) < 0) {
 347                 log_error("Failed to rename query file: %m");
 348                 r = -errno;
 349                 goto finish;
 350         }
 351
 352         zero(pollfd);
 353         pollfd[FD_SOCKET].fd = socket_fd;
 354         pollfd[FD_SOCKET].events = POLLIN;
 355         pollfd[FD_SIGNAL].fd = signal_fd;
 356         pollfd[FD_SIGNAL].events = POLLIN;
 357
 358         for (;;) {
 359                 char passphrase[LINE_MAX+1];
 360                 struct msghdr msghdr;
 361                 struct iovec iovec;
 362                 struct ucred *ucred;
 363                 union {
 364                         struct cmsghdr cmsghdr;
 365                         uint8_t buf[CMSG_SPACE(sizeof(struct ucred))];
 366                 } control;
 367                 ssize_t n;
 368                 int k;
 369                 usec_t t;
 370
 371                 t = now(CLOCK_MONOTONIC);
 372
 373                 if (until <= t) {
 374                         log_notice("Timed out");
 375                         r = -ETIME;
 376                         goto finish;
 377                 }
 378
 379                 if ((k = poll(pollfd, _FD_MAX, (until-t)/USEC_PER_MSEC)) < 0) {
 380
 381                         if (errno == EINTR)
 382                                 continue;
 383
 384                         log_error("poll() failed: %m");
 385                         r = -errno;
 386                         goto finish;
 387                 }
 388
 389                 if (k <= 0) {
 390                         log_notice("Timed out");
 391                         r = -ETIME;
 392                         goto finish;
 393                 }
 394
 395                 if (pollfd[FD_SIGNAL].revents & POLLIN) {
 396                         r = -EINTR;
 397                         goto finish;
 398                 }
 399
 400                 if (pollfd[FD_SOCKET].revents != POLLIN) {
 401                         log_error("Unexpected poll() event.");
 402                         r = -EIO;
 403                         goto finish;
 404                 }
 405
 406                 zero(iovec);
 407                 iovec.iov_base = passphrase;
 408                 iovec.iov_len = sizeof(passphrase);
 409
 410                 zero(control);
 411                 zero(msghdr);
 412                 msghdr.msg_iov = &iovec;
 413                 msghdr.msg_iovlen = 1;
 414                 msghdr.msg_control = &control;
 415                 msghdr.msg_controllen = sizeof(control);
 416
 417                 if ((n = recvmsg(socket_fd, &msghdr, 0)) < 0) {
 418
 419                         if (errno == EAGAIN ||
 420                             errno == EINTR)
 421                                 continue;
 422
 423                         log_error("recvmsg() failed: %m");
 424                         r = -errno;
 425                         goto finish;
 426                 }
 427
 428                 if (n <= 0) {
 429                         log_error("Message too short");
 430                         continue;
 431                 }
 432
 433                 if (msghdr.msg_controllen < CMSG_LEN(sizeof(struct ucred)) ||
 434                     control.cmsghdr.cmsg_level != SOL_SOCKET ||
 435                     control.cmsghdr.cmsg_type != SCM_CREDENTIALS ||
 436                     control.cmsghdr.cmsg_len != CMSG_LEN(sizeof(struct ucred))) {
 437                         log_warning("Received message without credentials. Ignoring.");
 438                         continue;
 439                 }
 440
 441                 ucred = (struct ucred*) CMSG_DATA(&control.cmsghdr);
 442                 if (ucred->uid != 0) {
 443                         log_warning("Got request from unprivileged user. Ignoring.");
 444                         continue;
 445                 }
 446
 447                 if (passphrase[0] == '+') {
 448                         char **l;
 449
 450                         if (!(l = strv_parse_nulstr(passphrase+1, n-1))) {
 451                                 r = -ENOMEM;
 452                                 goto finish;
 453                         }
 454
 455                         if (strv_length(l) <= 0) {
 456                                 strv_free(l);
 457                                 log_error("Invalid packet");
 458                                 continue;
 459                         }
 460
 461                         *_passphrases = l;
 462
 463                 } else if (passphrase[0] == '-') {
 464                         r = -ECANCELED;
 465                         goto finish;
 466                 } else {
 467                         log_error("Invalid packet");
 468                         continue;
 469                 }
 470
 471                 break;
 472         }
 473
 474         r = 0;
 475
 476 finish:
 477         if (fd >= 0)
 478                 close_nointr_nofail(fd);
 479
 480         if (socket_name) {
 481                 unlink(socket_name);
 482                 free(socket_name);
 483         }
 484
 485         if (socket_fd >= 0)
 486                 close_nointr_nofail(socket_fd);
 487
 488         if (signal_fd >= 0)
 489                 close_nointr_nofail(signal_fd);
 490
 491         if (f)
 492                 fclose(f);
 493
 494         unlink(temp);
 495
 496         if (final[0])
 497                 unlink(final);
 498
 499         assert_se(sigprocmask(SIG_SETMASK, &oldmask, NULL) == 0);
 500
 501         return r;
 502 }
 503
 504 int ask_password_auto(const char *message, const char *icon, usec_t until, bool accept_cached, char ***_passphrases) {
 505         assert(message);
 506         assert(_passphrases);
 507
 508         if (isatty(STDIN_FILENO)) {
 509                 int r;
 510                 char *s = NULL, **l = NULL;
 511
 512                 if ((r = ask_password_tty(message, until, NULL, &s)) < 0)
 513                         return r;
 514
 515                 l = strv_new(s, NULL);
 516                 free(s);
 517
 518                 if (!l)
 519                         return -ENOMEM;
 520
 521                 *_passphrases = l;
 522                 return r;
 523
 524         } else
 525                 return ask_password_agent(message, icon, until, accept_cached, _passphrases);
 526 }