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
  36 #include "ask-password-api.h"
  37
  38 int ask_password_tty(
  39                 const char *message,
  40                 usec_t until,
  41                 const char *flag_file,
  42                 char **_passphrase) {
  43
  44         struct termios old_termios, new_termios;
  45         char passphrase[LINE_MAX];
  46         size_t p = 0;
  47         int r, ttyfd = -1, notify = -1;
  48         struct pollfd pollfd[2];
  49         bool reset_tty = false;
  50         enum {
  51                 POLL_TTY,
  52                 POLL_INOTIFY
  53         };
  54
  55         assert(message);
  56         assert(_passphrase);
  57
  58         if (flag_file) {
  59                 if ((notify = inotify_init1(IN_CLOEXEC|IN_NONBLOCK)) < 0) {
  60                         r = -errno;
  61                         goto finish;
  62                 }
  63
  64                 if (inotify_add_watch(notify, flag_file, IN_ATTRIB /* for the link count */) < 0) {
  65                         r = -errno;
  66                         goto finish;
  67                 }
  68         }
  69
  70         if ((ttyfd = open("/dev/tty", O_RDWR|O_NOCTTY|O_CLOEXEC)) >= 0) {
  71
  72                 if (tcgetattr(ttyfd, &old_termios) < 0) {
  73                         r = -errno;
  74                         goto finish;
  75                 }
  76
  77                 loop_write(ttyfd, "\x1B[1m", 4, false);
  78                 loop_write(ttyfd, message, strlen(message), false);
  79                 loop_write(ttyfd, " ", 1, false);
  80                 loop_write(ttyfd, "\x1B[0m", 4, false);
  81
  82                 new_termios = old_termios;
  83                 new_termios.c_lflag &= ~(ICANON|ECHO);
  84                 new_termios.c_cc[VMIN] = 1;
  85                 new_termios.c_cc[VTIME] = 0;
  86
  87                 if (tcsetattr(ttyfd, TCSADRAIN, &new_termios) < 0) {
  88                         r = -errno;
  89                         goto finish;
  90                 }
  91
  92                 reset_tty = true;
  93         }
  94
  95         zero(pollfd);
  96
  97         pollfd[POLL_TTY].fd = ttyfd >= 0 ? ttyfd : STDIN_FILENO;
  98         pollfd[POLL_TTY].events = POLLIN;
  99         pollfd[POLL_INOTIFY].fd = notify;
 100         pollfd[POLL_INOTIFY].events = POLLIN;
 101
 102         for (;;) {
 103                 char c;
 104                 int sleep_for = -1, k;
 105                 ssize_t n;
 106
 107                 if (until > 0) {
 108                         usec_t y;
 109
 110                         y = now(CLOCK_MONOTONIC);
 111
 112                         if (y > until) {
 113                                 r = -ETIMEDOUT;
 114                                 goto finish;
 115                         }
 116
 117                         sleep_for = (int) ((until - y) / USEC_PER_MSEC);
 118                 }
 119
 120                 if (flag_file)
 121                         if (access(flag_file, F_OK) < 0) {
 122                                 r = -errno;
 123                                 goto finish;
 124                         }
 125
 126                 if ((k = poll(pollfd, notify > 0 ? 2 : 1, sleep_for)) < 0) {
 127
 128                         if (errno == EINTR)
 129                                 continue;
 130
 131                         r = -errno;
 132                         goto finish;
 133                 } else if (k == 0) {
 134                         r = -ETIMEDOUT;
 135                         goto finish;
 136                 }
 137
 138                 if (notify > 0 && pollfd[POLL_INOTIFY].revents != 0)
 139                         flush_fd(notify);
 140
 141                 if (pollfd[POLL_TTY].revents == 0)
 142                         continue;
 143
 144                 if ((n = read(ttyfd >= 0 ? ttyfd : STDIN_FILENO, &c, 1)) < 0) {
 145
 146                         if (errno == EINTR || errno == EAGAIN)
 147                                 continue;
 148
 149                         r = -errno;
 150                         goto finish;
 151
 152                 } else if (n == 0)
 153                         break;
 154
 155                 if (c == '\n')
 156                         break;
 157                 else if (c == 21) {
 158
 159                         while (p > 0) {
 160                                 p--;
 161
 162                                 if (ttyfd >= 0)
 163                                         loop_write(ttyfd, "\b \b", 3, false);
 164                         }
 165
 166                 } else if (c == '\b' || c == 127) {
 167                         if (p > 0) {
 168                                 p--;
 169
 170                                 if (ttyfd >= 0)
 171                                         loop_write(ttyfd, "\b \b", 3, false);
 172                         }
 173                 } else {
 174                         passphrase[p++] = c;
 175
 176                         if (ttyfd >= 0)
 177                                 loop_write(ttyfd, "*", 1, false);
 178                 }
 179         }
 180
 181         if (ttyfd >= 0)
 182                 loop_write(ttyfd, "\n", 1, false);
 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                 if (reset_tty)
 199                         tcsetattr(ttyfd, TCSADRAIN, &old_termios);
 200
 201                 close_nointr_nofail(ttyfd);
 202         }
 203
 204         return r;
 205 }
 206
 207 static int create_socket(char **name) {
 208         int fd;
 209         union {
 210                 struct sockaddr sa;
 211                 struct sockaddr_un un;
 212         } sa;
 213         int one = 1, r;
 214         char *c;
 215
 216         assert(name);
 217
 218         if ((fd = socket(AF_UNIX, SOCK_DGRAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0)) < 0) {
 219                 log_error("socket() failed: %m");
 220                 return -errno;
 221         }
 222
 223         zero(sa);
 224         sa.un.sun_family = AF_UNIX;
 225         snprintf(sa.un.sun_path, sizeof(sa.un.sun_path)-1, "/dev/.systemd/ask-password/sck.%llu", random_ull());
 226
 227         if (bind(fd, &sa.sa, offsetof(struct sockaddr_un, sun_path) + strlen(sa.un.sun_path)) < 0) {
 228                 r = -errno;
 229                 log_error("bind() failed: %m");
 230                 goto fail;
 231         }
 232
 233         if (setsockopt(fd, SOL_SOCKET, SO_PASSCRED, &one, sizeof(one)) < 0) {
 234                 r = -errno;
 235                 log_error("SO_PASSCRED failed: %m");
 236                 goto fail;
 237         }
 238
 239         if (!(c = strdup(sa.un.sun_path))) {
 240                 r = -ENOMEM;
 241                 log_error("Out of memory");
 242                 goto fail;
 243         }
 244
 245         *name = c;
 246         return fd;
 247
 248 fail:
 249         close_nointr_nofail(fd);
 250
 251         return r;
 252 }
 253
 254
 255 int ask_password_agent(
 256                 const char *message,
 257                 const char *icon,
 258                 usec_t until,
 259                 char **_passphrase) {
 260
 261         enum {
 262                 FD_SOCKET,
 263                 FD_SIGNAL,
 264                 _FD_MAX
 265         };
 266
 267         char temp[] = "/dev/.systemd/ask-password/tmp.XXXXXX";
 268         char final[sizeof(temp)] = "";
 269         int fd = -1, r;
 270         FILE *f = NULL;
 271         char *socket_name = NULL;
 272         int socket_fd = -1, signal_fd = -1;
 273         sigset_t mask;
 274         struct pollfd pollfd[_FD_MAX];
 275
 276         mkdir_p("/dev/.systemd/ask-password", 0755);
 277
 278         if ((fd = mkostemp(temp, O_CLOEXEC|O_CREAT|O_WRONLY)) < 0) {
 279                 log_error("Failed to create password file: %m");
 280                 r = -errno;
 281                 goto finish;
 282         }
 283
 284         fchmod(fd, 0644);
 285
 286         if (!(f = fdopen(fd, "w"))) {
 287                 log_error("Failed to allocate FILE: %m");
 288                 r = -errno;
 289                 goto finish;
 290         }
 291
 292         fd = -1;
 293
 294         assert_se(sigemptyset(&mask) == 0);
 295         sigset_add_many(&mask, SIGINT, SIGTERM, -1);
 296         assert_se(sigprocmask(SIG_SETMASK, &mask, NULL) == 0);
 297
 298         if ((signal_fd = signalfd(-1, &mask, SFD_NONBLOCK|SFD_CLOEXEC)) < 0) {
 299                 log_error("signalfd(): %m");
 300                 r = -errno;
 301                 goto finish;
 302         }
 303
 304         if ((socket_fd = create_socket(&socket_name)) < 0) {
 305                 r = socket_fd;
 306                 goto finish;
 307         }
 308
 309         fprintf(f,
 310                 "[Ask]\n"
 311                 "PID=%lu\n"
 312                 "Socket=%s\n"
 313                 "NotAfter=%llu\n",
 314                 (unsigned long) getpid(),
 315                 socket_name,
 316                 (unsigned long long) until);
 317
 318         if (message)
 319                 fprintf(f, "Message=%s\n", message);
 320
 321         if (icon)
 322                 fprintf(f, "Icon=%s\n", icon);
 323
 324         fflush(f);
 325
 326         if (ferror(f)) {
 327                 log_error("Failed to write query file: %m");
 328                 r = -errno;
 329                 goto finish;
 330         }
 331
 332         memcpy(final, temp, sizeof(temp));
 333
 334         final[sizeof(final)-11] = 'a';
 335         final[sizeof(final)-10] = 's';
 336         final[sizeof(final)-9] = 'k';
 337
 338         if (rename(temp, final) < 0) {
 339                 log_error("Failed to rename query file: %m");
 340                 r = -errno;
 341                 goto finish;
 342         }
 343
 344         zero(pollfd);
 345         pollfd[FD_SOCKET].fd = socket_fd;
 346         pollfd[FD_SOCKET].events = POLLIN;
 347         pollfd[FD_SIGNAL].fd = signal_fd;
 348         pollfd[FD_SIGNAL].events = POLLIN;
 349
 350         for (;;) {
 351                 char passphrase[LINE_MAX+1];
 352                 struct msghdr msghdr;
 353                 struct iovec iovec;
 354                 struct ucred *ucred;
 355                 union {
 356                         struct cmsghdr cmsghdr;
 357                         uint8_t buf[CMSG_SPACE(sizeof(struct ucred))];
 358                 } control;
 359                 ssize_t n;
 360                 int k;
 361                 usec_t t;
 362
 363                 t = now(CLOCK_MONOTONIC);
 364
 365                 if (until <= t) {
 366                         log_notice("Timed out");
 367                         r = -ETIME;
 368                         goto finish;
 369                 }
 370
 371                 if ((k = poll(pollfd, _FD_MAX, until-t/USEC_PER_MSEC)) < 0) {
 372
 373                         if (errno == EINTR)
 374                                 continue;
 375
 376                         log_error("poll() failed: %m");
 377                         r = -errno;
 378                         goto finish;
 379                 }
 380
 381                 if (k <= 0) {
 382                         log_notice("Timed out");
 383                         r = -ETIME;
 384                         goto finish;
 385                 }
 386
 387                 if (pollfd[FD_SIGNAL].revents & POLLIN)
 388                         break;
 389
 390                 if (pollfd[FD_SOCKET].revents != POLLIN) {
 391                         log_error("Unexpected poll() event.");
 392                         r = -EIO;
 393                         goto finish;
 394                 }
 395
 396                 zero(iovec);
 397                 iovec.iov_base = passphrase;
 398                 iovec.iov_len = sizeof(passphrase)-1;
 399
 400                 zero(control);
 401                 zero(msghdr);
 402                 msghdr.msg_iov = &iovec;
 403                 msghdr.msg_iovlen = 1;
 404                 msghdr.msg_control = &control;
 405                 msghdr.msg_controllen = sizeof(control);
 406
 407                 if ((n = recvmsg(socket_fd, &msghdr, 0)) < 0) {
 408
 409                         if (errno == EAGAIN ||
 410                             errno == EINTR)
 411                                 continue;
 412
 413                         log_error("recvmsg() failed: %m");
 414                         r = -errno;
 415                         goto finish;
 416                 }
 417
 418                 if (n <= 0) {
 419                         log_error("Message too short");
 420                         continue;
 421                 }
 422
 423                 if (msghdr.msg_controllen < CMSG_LEN(sizeof(struct ucred)) ||
 424                     control.cmsghdr.cmsg_level != SOL_SOCKET ||
 425                     control.cmsghdr.cmsg_type != SCM_CREDENTIALS ||
 426                     control.cmsghdr.cmsg_len != CMSG_LEN(sizeof(struct ucred))) {
 427                         log_warning("Received message without credentials. Ignoring.");
 428                         continue;
 429                 }
 430
 431                 ucred = (struct ucred*) CMSG_DATA(&control.cmsghdr);
 432                 if (ucred->uid != 0) {
 433                         log_warning("Got request from unprivileged user. Ignoring.");
 434                         continue;
 435                 }
 436
 437                 if (passphrase[0] == '+') {
 438                         passphrase[n] = 0;
 439
 440                         if (!(*_passphrase = strdup(passphrase+1))) {
 441                                 r = -ENOMEM;
 442                                 goto finish;
 443                         }
 444
 445                 } else if (passphrase[0] == '-') {
 446                         r = -ECANCELED;
 447                         goto finish;
 448                 } else {
 449                         log_error("Invalid packet");
 450                         continue;
 451                 }
 452
 453                 break;
 454         }
 455
 456         r = 0;
 457
 458 finish:
 459         if (fd >= 0)
 460                 close_nointr_nofail(fd);
 461
 462         if (socket_name) {
 463                 unlink(socket_name);
 464                 free(socket_name);
 465         }
 466
 467         if (socket_fd >= 0)
 468                 close_nointr_nofail(socket_fd);
 469
 470         if (signal_fd >= 0)
 471                 close_nointr_nofail(signal_fd);
 472
 473         if (f)
 474                 fclose(f);
 475
 476         unlink(temp);
 477
 478         if (final[0])
 479                 unlink(final);
 480
 481         return r;
 482 }
 483
 484 int ask_password_auto(const char *message, const char *icon, usec_t until, char **_passphrase) {
 485         assert(message);
 486         assert(_passphrase);
 487
 488         if (isatty(STDIN_FILENO))
 489                 return ask_password_tty(message, until, NULL, _passphrase);
 490         else
 491                 return ask_password_agent(message, icon, until, _passphrase);
 492 }