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 #include <stddef.h>
  37
  38 #include "log.h"
  39 #include "macro.h"
  40 #include "util.h"
  41
  42 static const char *arg_icon = NULL;
  43 static const char *arg_message = NULL;
  44 static bool arg_use_tty = true;
  45 static usec_t arg_timeout = 60 * USEC_PER_SEC;
  46
  47 static int create_socket(char **name) {
  48         int fd;
  49         union {
  50                 struct sockaddr sa;
  51                 struct sockaddr_un un;
  52         } sa;
  53         int one = 1, r;
  54         char *c;
  55
  56         assert(name);
  57
  58         if ((fd = socket(AF_UNIX, SOCK_DGRAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0)) < 0) {
  59                 log_error("socket() failed: %m");
  60                 return -errno;
  61         }
  62
  63         zero(sa);
  64         sa.un.sun_family = AF_UNIX;
  65         snprintf(sa.un.sun_path, sizeof(sa.un.sun_path)-1, "/dev/.systemd/ask-password/sck.%llu", random_ull());
  66
  67         if (bind(fd, &sa.sa, offsetof(struct sockaddr_un, sun_path) + strlen(sa.un.sun_path)) < 0) {
  68                 r = -errno;
  69                 log_error("bind() failed: %m");
  70                 goto fail;
  71         }
  72
  73         if (setsockopt(fd, SOL_SOCKET, SO_PASSCRED, &one, sizeof(one)) < 0) {
  74                 r = -errno;
  75                 log_error("SO_PASSCRED failed: %m");
  76                 goto fail;
  77         }
  78
  79         if (!(c = strdup(sa.un.sun_path))) {
  80                 r = -ENOMEM;
  81                 log_error("Out of memory");
  82                 goto fail;
  83         }
  84
  85         *name = c;
  86         return fd;
  87
  88 fail:
  89         close_nointr_nofail(fd);
  90
  91         return r;
  92 }
  93
  94 static int help(void) {
  95
  96         printf("%s [OPTIONS...] MESSAGE\n\n"
  97                "Query the user for a system passphrase, via the TTY or an UI agent.\n\n"
  98                "  -h --help         Show this help\n"
  99                "     --icon=NAME    Icon name\n"
 100                "     --timeout=SEC Timeout in sec\n"
 101                "     --no-tty       Ask question via agent even on TTY\n",
 102                program_invocation_short_name);
 103
 104         return 0;
 105 }
 106
 107 static int parse_argv(int argc, char *argv[]) {
 108
 109         enum {
 110                 ARG_ICON = 0x100,
 111                 ARG_TIMEOUT,
 112                 ARG_NO_TTY
 113         };
 114
 115         static const struct option options[] = {
 116                 { "help",      no_argument,       NULL, 'h'         },
 117                 { "icon",      required_argument, NULL, ARG_ICON    },
 118                 { "timeout",   required_argument, NULL, ARG_TIMEOUT },
 119                 { "no-tty",    no_argument,       NULL, ARG_NO_TTY  },
 120                 { NULL,        0,                 NULL, 0           }
 121         };
 122
 123         int c;
 124
 125         assert(argc >= 0);
 126         assert(argv);
 127
 128         while ((c = getopt_long(argc, argv, "h", options, NULL)) >= 0) {
 129
 130                 switch (c) {
 131
 132                 case 'h':
 133                         help();
 134                         return 0;
 135
 136                 case ARG_ICON:
 137                         arg_icon = optarg;
 138                         break;
 139
 140                 case ARG_TIMEOUT:
 141                         if (parse_usec(optarg, &arg_timeout) < 0 || arg_timeout <= 0) {
 142                                 log_error("Failed to parse --timeout parameter %s", optarg);
 143                                 return -EINVAL;
 144                         }
 145                         break;
 146
 147                 case ARG_NO_TTY:
 148                         arg_use_tty = false;
 149                         break;
 150
 151                 case '?':
 152                         return -EINVAL;
 153
 154                 default:
 155                         log_error("Unknown option code %c", c);
 156                         return -EINVAL;
 157                 }
 158         }
 159
 160         if (optind != argc-1) {
 161                 help();
 162                 return -EINVAL;
 163         }
 164
 165         arg_message = argv[optind];
 166         return 1;
 167 }
 168
 169 static int ask_agent(void) {
 170         char temp[] = "/dev/.systemd/ask-password/tmp.XXXXXX";
 171         char final[sizeof(temp)] = "";
 172         int fd = -1, r;
 173         FILE *f = NULL;
 174         char *socket_name = NULL;
 175         int socket_fd = -1, signal_fd;
 176         sigset_t mask;
 177         usec_t not_after;
 178
 179         mkdir_p("/dev/.systemd/ask-password", 0755);
 180
 181         if ((fd = mkostemp(temp, O_CLOEXEC|O_CREAT|O_WRONLY)) < 0) {
 182                 log_error("Failed to create password file: %m");
 183                 r = -errno;
 184                 goto finish;
 185         }
 186
 187         fchmod(fd, 0644);
 188
 189         if (!(f = fdopen(fd, "w"))) {
 190                 log_error("Failed to allocate FILE: %m");
 191                 r = -errno;
 192                 goto finish;
 193         }
 194
 195         fd = -1;
 196
 197         assert_se(sigemptyset(&mask) == 0);
 198         sigset_add_many(&mask, SIGINT, SIGTERM, -1);
 199         assert_se(sigprocmask(SIG_SETMASK, &mask, NULL) == 0);
 200
 201         if ((signal_fd = signalfd(-1, &mask, SFD_NONBLOCK|SFD_CLOEXEC)) < 0) {
 202                 log_error("signalfd(): %m");
 203                 r = -errno;
 204                 goto finish;
 205         }
 206
 207         if ((socket_fd = create_socket(&socket_name)) < 0) {
 208                 r = socket_fd;
 209                 goto finish;
 210         }
 211
 212         not_after = now(CLOCK_MONOTONIC) + arg_timeout;
 213
 214         fprintf(f,
 215                 "[Ask]\n"
 216                 "PID=%lu\n"
 217                 "Socket=%s\n"
 218                 "NotAfter=%llu\n",
 219                 (unsigned long) getpid(),
 220                 socket_name,
 221                 (unsigned long long) not_after);
 222
 223         if (arg_message)
 224                 fprintf(f, "Message=%s\n", arg_message);
 225
 226         if (arg_icon)
 227                 fprintf(f, "Icon=%s\n", arg_icon);
 228
 229         fflush(f);
 230
 231         if (ferror(f)) {
 232                 log_error("Failed to write query file: %m");
 233                 r = -errno;
 234                 goto finish;
 235         }
 236
 237         memcpy(final, temp, sizeof(temp));
 238
 239         final[sizeof(final)-11] = 'a';
 240         final[sizeof(final)-10] = 's';
 241         final[sizeof(final)-9] = 'k';
 242
 243         if (rename(temp, final) < 0) {
 244                 log_error("Failed to rename query file: %m");
 245                 r = -errno;
 246                 goto finish;
 247         }
 248
 249         for (;;) {
 250                 enum {
 251                         FD_SOCKET,
 252                         FD_SIGNAL,
 253                         _FD_MAX
 254                 };
 255
 256                 char passphrase[LINE_MAX+1];
 257                 struct msghdr msghdr;
 258                 struct iovec iovec;
 259                 struct ucred *ucred;
 260                 union {
 261                         struct cmsghdr cmsghdr;
 262                         uint8_t buf[CMSG_SPACE(sizeof(struct ucred))];
 263                 } control;
 264                 ssize_t n;
 265                 struct pollfd pollfd[_FD_MAX];
 266                 int k;
 267
 268                 zero(pollfd);
 269                 pollfd[FD_SOCKET].fd = socket_fd;
 270                 pollfd[FD_SOCKET].events = POLLIN;
 271                 pollfd[FD_SIGNAL].fd = signal_fd;
 272                 pollfd[FD_SIGNAL].events = POLLIN;
 273
 274                 if ((k = poll(pollfd, 2, arg_timeout/USEC_PER_MSEC)) < 0) {
 275
 276                         if (errno == EINTR)
 277                                 continue;
 278
 279                         log_error("poll() failed: %m");
 280                         r = -errno;
 281                         goto finish;
 282                 }
 283
 284                 if (k <= 0) {
 285                         log_notice("Timed out");
 286                         r = -ETIME;
 287                         goto finish;
 288                 }
 289
 290                 if (pollfd[FD_SIGNAL].revents & POLLIN)
 291                         break;
 292
 293                 if (pollfd[FD_SOCKET].revents != POLLIN) {
 294                         log_error("Unexpected poll() event.");
 295                         r = -EIO;
 296                         goto finish;
 297                 }
 298
 299                 zero(iovec);
 300                 iovec.iov_base = passphrase;
 301                 iovec.iov_len = sizeof(passphrase)-1;
 302
 303                 zero(control);
 304                 zero(msghdr);
 305                 msghdr.msg_iov = &iovec;
 306                 msghdr.msg_iovlen = 1;
 307                 msghdr.msg_control = &control;
 308                 msghdr.msg_controllen = sizeof(control);
 309
 310                 if ((n = recvmsg(socket_fd, &msghdr, 0)) < 0) {
 311
 312                         if (errno == EAGAIN ||
 313                             errno == EINTR)
 314                                 continue;
 315
 316                         log_error("recvmsg() failed: %m");
 317                         r = -errno;
 318                         goto finish;
 319                 }
 320
 321                 if (n <= 0) {
 322                         log_error("Message too short");
 323                         continue;
 324                 }
 325
 326                 if (msghdr.msg_controllen < CMSG_LEN(sizeof(struct ucred)) ||
 327                     control.cmsghdr.cmsg_level != SOL_SOCKET ||
 328                     control.cmsghdr.cmsg_type != SCM_CREDENTIALS ||
 329                     control.cmsghdr.cmsg_len != CMSG_LEN(sizeof(struct ucred))) {
 330                         log_warning("Received message without credentials. Ignoring.");
 331                         continue;
 332                 }
 333
 334                 ucred = (struct ucred*) CMSG_DATA(&control.cmsghdr);
 335                 if (ucred->uid != 0) {
 336                         log_warning("Got request from unprivileged user. Ignoring.");
 337                         continue;
 338                 }
 339
 340                 if (passphrase[0] == '+') {
 341                         passphrase[n] = 0;
 342                         fputs(passphrase+1, stdout);
 343                         fflush(stdout);
 344                 } else if (passphrase[0] == '-') {
 345                         r = -ECANCELED;
 346                         goto finish;
 347                 } else {
 348                         log_error("Invalid packet");
 349                         continue;
 350                 }
 351
 352                 break;
 353         }
 354
 355         r = 0;
 356
 357 finish:
 358         if (fd >= 0)
 359                 close_nointr_nofail(fd);
 360
 361         if (socket_name) {
 362                 unlink(socket_name);
 363                 free(socket_name);
 364         }
 365
 366         if (socket_fd >= 0)
 367                 close_nointr_nofail(socket_fd);
 368
 369         if (f)
 370                 fclose(f);
 371
 372         unlink(temp);
 373
 374         if (final[0])
 375                 unlink(final);
 376
 377         return r;
 378 }
 379
 380 int main(int argc, char *argv[]) {
 381         int r;
 382
 383         log_parse_environment();
 384         log_open();
 385
 386         if ((r = parse_argv(argc, argv)) <= 0)
 387                 goto finish;
 388
 389         if (arg_use_tty && isatty(STDIN_FILENO)) {
 390                 char *password = NULL;
 391
 392                 if ((r = ask_password_tty(arg_message, now(CLOCK_MONOTONIC) + arg_timeout, NULL, &password)) >= 0) {
 393                         fputs(password, stdout);
 394                         fflush(stdout);
 395                         free(password);
 396                 }
 397
 398         } else
 399                 r = ask_agent();
 400
 401 finish:
 402         return r < 0 ? EXIT_FAILURE : EXIT_SUCCESS;
 403 }