src/ask-password.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 <sys/socket.h>
  23 #include <sys/poll.h>
  24 #include <sys/types.h>
  25 #include <assert.h>
  26 #include <string.h>
  27 #include <errno.h>
  28 #include <unistd.h>
  29 #include <fcntl.h>
  30 #include <sys/un.h>
  31 #include <sys/stat.h>
  32 #include <sys/signalfd.h>
  33 #include <getopt.h>
  34 #include <termios.h>
  35 #include <limits.h>
  36
  37 #include "log.h"
  38 #include "macro.h"
  39 #include "util.h"
  40
  41 static const char *arg_icon = NULL;
  42 static const char *arg_message = NULL;
  43 static bool arg_use_tty = true;
  44 static usec_t arg_timeout = 60 * USEC_PER_SEC;
  45
  46 static int create_socket(char **name) {
  47         int fd;
  48         union {
  49                 struct sockaddr sa;
  50                 struct sockaddr_un un;
  51         } sa;
  52         int one = 1, r;
  53         char *c;
  54
  55         assert(name);
  56
  57         if ((fd = socket(AF_UNIX, SOCK_DGRAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0)) < 0) {
  58                 log_error("socket() failed: %m");
  59                 return -errno;
  60         }
  61
  62         zero(sa);
  63         sa.un.sun_family = AF_UNIX;
  64         snprintf(sa.un.sun_path+1, sizeof(sa.un.sun_path)-1, "/org/freedesktop/systemd1/ask-password/%llu", random_ull());
  65
  66         if (bind(fd, &sa.sa, sizeof(sa_family_t) + 1 + strlen(sa.un.sun_path+1)) < 0) {
  67                 r = -errno;
  68                 log_error("bind() failed: %m");
  69                 goto fail;
  70         }
  71
  72         if (setsockopt(fd, SOL_SOCKET, SO_PASSCRED, &one, sizeof(one)) < 0) {
  73                 r = -errno;
  74                 log_error("SO_PASSCRED failed: %m");
  75                 goto fail;
  76         }
  77
  78         if (!(c = strdup(sa.un.sun_path+1))) {
  79                 r = -ENOMEM;
  80                 log_error("Out of memory");
  81                 goto fail;
  82         }
  83
  84         *name = c;
  85         return fd;
  86
  87 fail:
  88         close_nointr_nofail(fd);
  89
  90         return r;
  91 }
  92
  93 static int help(void) {
  94
  95         printf("%s [OPTIONS...] MESSAGE\n\n"
  96                "Query the user for a system passphrase, via the TTY or an UI agent.\n\n"
  97                "  -h --help         Show this help\n"
  98                "     --icon=NAME    Icon name\n"
  99                "     --timeout=USEC Timeout in usec\n"
 100                "     --no-tty       Ask question via agent even on TTY\n",
 101                program_invocation_short_name);
 102
 103         return 0;
 104 }
 105
 106 static int parse_argv(int argc, char *argv[]) {
 107
 108         enum {
 109                 ARG_ICON = 0x100,
 110                 ARG_TIMEOUT,
 111                 ARG_NO_TTY
 112         };
 113
 114         static const struct option options[] = {
 115                 { "help",      no_argument,       NULL, 'h'         },
 116                 { "icon",      required_argument, NULL, ARG_ICON    },
 117                 { "timeout",   required_argument, NULL, ARG_TIMEOUT },
 118                 { "no-tty",    no_argument,       NULL, ARG_NO_TTY  },
 119                 { NULL,        0,                 NULL, 0           }
 120         };
 121
 122         int c;
 123
 124         assert(argc >= 0);
 125         assert(argv);
 126
 127         while ((c = getopt_long(argc, argv, "h", options, NULL)) >= 0) {
 128
 129                 switch (c) {
 130
 131                 case 'h':
 132                         help();
 133                         return 0;
 134
 135                 case ARG_ICON:
 136                         arg_icon = optarg;
 137                         break;
 138
 139                 case ARG_TIMEOUT:
 140                         if (parse_usec(optarg, &arg_timeout) < 0 || arg_timeout <= 0) {
 141                                 log_error("Failed to parse --timeout parameter %s", optarg);
 142                                 return -EINVAL;
 143                         }
 144                         break;
 145
 146                 case ARG_NO_TTY:
 147                         arg_use_tty = false;
 148                         break;
 149
 150                 case '?':
 151                         return -EINVAL;
 152
 153                 default:
 154                         log_error("Unknown option code %c", c);
 155                         return -EINVAL;
 156                 }
 157         }
 158
 159         if (optind != argc-1) {
 160                 help();
 161                 return -EINVAL;
 162         }
 163
 164         arg_message = argv[optind];
 165         return 1;
 166 }
 167
 168 static int ask_agent(void) {
 169         char temp[] = "/dev/.systemd/ask-password/tmp.XXXXXX";
 170         char final[sizeof(temp)] = "";
 171         int fd = -1, r;
 172         FILE *f = NULL;
 173         char *socket_name = NULL;
 174         int socket_fd = -1, signal_fd;
 175         sigset_t mask;
 176         usec_t not_after;
 177
 178         if ((fd = mkostemp(temp, O_CLOEXEC|O_CREAT|O_WRONLY)) < 0) {
 179                 log_error("Failed to create password file: %m");
 180                 r = -errno;
 181                 goto finish;
 182         }
 183
 184         fchmod(fd, 0644);
 185
 186         if (!(f = fdopen(fd, "w"))) {
 187                 log_error("Failed to allocate FILE: %m");
 188                 r = -errno;
 189                 goto finish;
 190         }
 191
 192         fd = -1;
 193
 194         assert_se(sigemptyset(&mask) == 0);
 195         sigset_add_many(&mask, SIGINT, SIGTERM, -1);
 196         assert_se(sigprocmask(SIG_SETMASK, &mask, NULL) == 0);
 197
 198         if ((signal_fd = signalfd(-1, &mask, SFD_NONBLOCK|SFD_CLOEXEC)) < 0) {
 199                 log_error("signalfd(): %m");
 200                 r = -errno;
 201                 goto finish;
 202         }
 203
 204         if ((socket_fd = create_socket(&socket_name)) < 0) {
 205                 r = socket_fd;
 206                 goto finish;
 207         }
 208
 209         not_after = now(CLOCK_MONOTONIC) + arg_timeout;
 210
 211         fprintf(f,
 212                 "[Ask]\n"
 213                 "Socket=%s\n"
 214                 "NotAfter=%llu\n",
 215                 socket_name,
 216                 (unsigned long long) not_after);
 217
 218         if (arg_message)
 219                 fprintf(f, "Message=%s\n", arg_message);
 220
 221         if (arg_icon)
 222                 fprintf(f, "Icon=%s\n", arg_icon);
 223
 224         fflush(f);
 225
 226         if (ferror(f)) {
 227                 log_error("Failed to write query file: %m");
 228                 r = -errno;
 229                 goto finish;
 230         }
 231
 232         memcpy(final, temp, sizeof(temp));
 233
 234         final[sizeof(final)-11] = 'a';
 235         final[sizeof(final)-10] = 's';
 236         final[sizeof(final)-9] = 'k';
 237
 238         if (rename(temp, final) < 0) {
 239                 log_error("Failed to rename query file: %m");
 240                 r = -errno;
 241                 goto finish;
 242         }
 243
 244         for (;;) {
 245                 enum {
 246                         FD_SOCKET,
 247                         FD_SIGNAL,
 248                         _FD_MAX
 249                 };
 250
 251                 char passphrase[LINE_MAX+1];
 252                 struct msghdr msghdr;
 253                 struct iovec iovec;
 254                 struct ucred *ucred;
 255                 union {
 256                         struct cmsghdr cmsghdr;
 257                         uint8_t buf[CMSG_SPACE(sizeof(struct ucred))];
 258                 } control;
 259                 ssize_t n;
 260                 struct pollfd pollfd[_FD_MAX];
 261                 int k;
 262
 263                 zero(pollfd);
 264                 pollfd[FD_SOCKET].fd = socket_fd;
 265                 pollfd[FD_SOCKET].events = POLLIN;
 266                 pollfd[FD_SIGNAL].fd = signal_fd;
 267                 pollfd[FD_SIGNAL].events = POLLIN;
 268
 269                 if ((k = poll(pollfd, 2, arg_timeout/USEC_PER_MSEC)) < 0) {
 270
 271                         if (errno == EINTR)
 272                                 continue;
 273
 274                         log_error("poll() failed: %m");
 275                         r = -errno;
 276                         goto finish;
 277                 }
 278
 279                 if (k <= 0) {
 280                         log_notice("Timed out");
 281                         r = -ETIME;
 282                         goto finish;
 283                 }
 284
 285                 if (pollfd[FD_SIGNAL].revents & POLLIN)
 286                         break;
 287
 288                 if (pollfd[FD_SOCKET].revents != POLLIN) {
 289                         log_error("Unexpected poll() event.");
 290                         r = -EIO;
 291                         goto finish;
 292                 }
 293
 294                 zero(iovec);
 295                 iovec.iov_base = passphrase;
 296                 iovec.iov_len = sizeof(passphrase)-1;
 297
 298                 zero(control);
 299                 zero(msghdr);
 300                 msghdr.msg_iov = &iovec;
 301                 msghdr.msg_iovlen = 1;
 302                 msghdr.msg_control = &control;
 303                 msghdr.msg_controllen = sizeof(control);
 304
 305                 if ((n = recvmsg(socket_fd, &msghdr, 0)) < 0) {
 306
 307                         if (errno == EAGAIN ||
 308                             errno == EINTR)
 309                                 continue;
 310
 311                         log_error("recvmsg() failed: %m");
 312                         r = -errno;
 313                         goto finish;
 314                 }
 315
 316                 if (n <= 0) {
 317                         log_error("Message too short");
 318                         continue;
 319                 }
 320
 321                 if (msghdr.msg_controllen < CMSG_LEN(sizeof(struct ucred)) ||
 322                     control.cmsghdr.cmsg_level != SOL_SOCKET ||
 323                     control.cmsghdr.cmsg_type != SCM_CREDENTIALS ||
 324                     control.cmsghdr.cmsg_len != CMSG_LEN(sizeof(struct ucred))) {
 325                         log_warning("Received message without credentials. Ignoring.");
 326                         continue;
 327                 }
 328
 329                 ucred = (struct ucred*) CMSG_DATA(&control.cmsghdr);
 330                 if (ucred->uid != 0) {
 331                         log_warning("Got request from unprivileged user. Ignoring.");
 332                         continue;
 333                 }
 334
 335                 if (passphrase[0] == '+') {
 336                         passphrase[n] = 0;
 337                         fputs(passphrase+1, stdout);
 338                         fflush(stdout);
 339                 } else if (passphrase[0] == '-') {
 340                         r = -ECANCELED;
 341                         goto finish;
 342                 } else {
 343                         log_error("Invalid packet");
 344                         continue;
 345                 }
 346
 347                 break;
 348         }
 349
 350         r = 0;
 351
 352 finish:
 353         if (fd >= 0)
 354                 close_nointr_nofail(fd);
 355
 356         if (socket_fd >= 0)
 357                 close_nointr_nofail(socket_fd);
 358
 359         if (f)
 360                 fclose(f);
 361
 362         unlink(temp);
 363
 364         if (final[0])
 365                 unlink(final);
 366
 367         return r;
 368 }
 369
 370 static int ask_tty(void) {
 371         struct termios old_termios, new_termios;
 372         char passphrase[LINE_MAX];
 373         FILE *ttyf;
 374
 375         if (!(ttyf = fopen("/dev/tty", "w"))) {
 376                 log_error("Failed to open /dev/tty: %m");
 377                 return -errno;
 378         }
 379
 380         fputs("\x1B[1m", ttyf);
 381         fprintf(ttyf, "%s: ", arg_message);
 382         fputs("\x1B[0m", ttyf);
 383         fflush(ttyf);
 384
 385         if (tcgetattr(STDIN_FILENO, &old_termios) >= 0) {
 386
 387                 new_termios = old_termios;
 388
 389                 new_termios.c_lflag &= ~(ICANON|ECHO);
 390                 new_termios.c_cc[VMIN] = 1;
 391                 new_termios.c_cc[VTIME] = 0;
 392
 393                 if (tcsetattr(STDIN_FILENO, TCSADRAIN, &new_termios) >= 0) {
 394                         size_t p = 0;
 395                         int r = 0;
 396
 397                         for (;;) {
 398                                 size_t k;
 399                                 char c;
 400
 401                                 k = fread(&c, 1, 1, stdin);
 402
 403                                 if (k <= 0) {
 404                                         r = -EIO;
 405                                         break;
 406                                 }
 407
 408                                 if (c == '\n')
 409                                         break;
 410                                 else if (c == '\b' || c == 127) {
 411                                         if (p > 0) {
 412                                                 p--;
 413                                                 fputs("\b \b", ttyf);
 414                                         }
 415                                 } else {
 416                                         passphrase[p++] = c;
 417                                         fputc('*', ttyf);
 418                                 }
 419
 420                                 fflush(ttyf);
 421                         }
 422
 423                         fputc('\n', ttyf);
 424                         fclose(ttyf);
 425                         tcsetattr(STDIN_FILENO, TCSADRAIN, &old_termios);
 426
 427                         if (r < 0)
 428                                 return -EIO;
 429
 430                         passphrase[p] = 0;
 431
 432                         fputs(passphrase, stdout);
 433                         fflush(stdout);
 434                         return 0;
 435                 }
 436
 437         }
 438
 439         fclose(ttyf);
 440
 441         if (!fgets(passphrase, sizeof(passphrase), stdin)) {
 442                 log_error("Failed to read password.");
 443                 return -EIO;
 444         }
 445
 446         truncate_nl(passphrase);
 447         fputs(passphrase, stdout);
 448         fflush(stdout);
 449
 450         return 0;
 451 }
 452
 453 int main(int argc, char *argv[]) {
 454         int r;
 455
 456         log_parse_environment();
 457         log_open();
 458
 459         if ((r = parse_argv(argc, argv)) <= 0)
 460                 goto finish;
 461
 462         if (arg_use_tty && isatty(STDIN_FILENO))
 463                 r = ask_tty();
 464         else
 465                 r = ask_agent();
 466
 467 finish:
 468         return r < 0 ? EXIT_FAILURE : EXIT_SUCCESS;
 469 }