qemu-nbd.c

   1 /*
   2  *  Copyright (C) 2005  Anthony Liguori <anthony@codemonkey.ws>
   3  *
   4  *  Network Block Device
   5  *
   6  *  This program is free software; you can redistribute it and/or modify
   7  *  it under the terms of the GNU General Public License as published by
   8  *  the Free Software Foundation; under version 2 of the License.
   9  *
  10  *  This program is distributed in the hope that it will be useful,
  11  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  *  GNU General Public License for more details.
  14  *
  15  *  You should have received a copy of the GNU General Public License
  16  *  along with this program; if not, see <http://www.gnu.org/licenses/>.
  17  */
  18
  19 #include "qemu-common.h"
  20 #include "block/block.h"
  21 #include "block/nbd.h"
  22 #include "qemu/main-loop.h"
  23
  24 #include <stdarg.h>
  25 #include <stdio.h>
  26 #include <getopt.h>
  27 #include <err.h>
  28 #include <sys/types.h>
  29 #include <sys/socket.h>
  30 #include <netinet/in.h>
  31 #include <netinet/tcp.h>
  32 #include <arpa/inet.h>
  33 #include <signal.h>
  34 #include <libgen.h>
  35 #include <pthread.h>
  36
  37 #define SOCKET_PATH          "/var/lock/qemu-nbd-%s"
  38 #define QEMU_NBD_OPT_CACHE   1
  39 #define QEMU_NBD_OPT_AIO     2
  40 #define QEMU_NBD_OPT_DISCARD 3
  41
  42 static NBDExport *exp;
  43 static int verbose;
  44 static char *srcpath;
  45 static char *sockpath;
  46 static int persistent = 0;
  47 static enum { RUNNING, TERMINATE, TERMINATING, TERMINATED } state;
  48 static int shared = 1;
  49 static int nb_fds;
  50
  51 static void usage(const char *name)
  52 {
  53     (printf) (
  54 "Usage: %s [OPTIONS] FILE\n"
  55 "QEMU Disk Network Block Device Server\n"
  56 "\n"
  57 "  -h, --help           display this help and exit\n"
  58 "  -V, --version        output version information and exit\n"
  59 "\n"
  60 "Connection properties:\n"
  61 "  -p, --port=PORT      port to listen on (default `%d')\n"
  62 "  -b, --bind=IFACE     interface to bind to (default `0.0.0.0')\n"
  63 "  -k, --socket=PATH    path to the unix socket\n"
  64 "                       (default '"SOCKET_PATH"')\n"
  65 "  -e, --shared=NUM     device can be shared by NUM clients (default '1')\n"
  66 "  -t, --persistent     don't exit on the last connection\n"
  67 "  -v, --verbose        display extra debugging information\n"
  68 "\n"
  69 "Exposing part of the image:\n"
  70 "  -o, --offset=OFFSET  offset into the image\n"
  71 "  -P, --partition=NUM  only expose partition NUM\n"
  72 "\n"
  73 #ifdef __linux__
  74 "Kernel NBD client support:\n"
  75 "  -c, --connect=DEV    connect FILE to the local NBD device DEV\n"
  76 "  -d, --disconnect     disconnect the specified device\n"
  77 "\n"
  78 #endif
  79 "\n"
  80 "Block device options:\n"
  81 "  -r, --read-only      export read-only\n"
  82 "  -s, --snapshot       use snapshot file\n"
  83 "  -n, --nocache        disable host cache\n"
  84 "      --cache=MODE     set cache mode (none, writeback, ...)\n"
  85 #ifdef CONFIG_LINUX_AIO
  86 "      --aio=MODE       set AIO mode (native or threads)\n"
  87 #endif
  88 "\n"
  89 "Report bugs to <qemu-devel@nongnu.org>\n"
  90     , name, NBD_DEFAULT_PORT, "DEVICE");
  91 }
  92
  93 static void version(const char *name)
  94 {
  95     printf(
  96 "%s version 0.0.1\n"
  97 "Written by Anthony Liguori.\n"
  98 "\n"
  99 "Copyright (C) 2006 Anthony Liguori <anthony@codemonkey.ws>.\n"
 100 "This is free software; see the source for copying conditions.  There is NO\n"
 101 "warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.\n"
 102     , name);
 103 }
 104
 105 struct partition_record
 106 {
 107     uint8_t bootable;
 108     uint8_t start_head;
 109     uint32_t start_cylinder;
 110     uint8_t start_sector;
 111     uint8_t system;
 112     uint8_t end_head;
 113     uint8_t end_cylinder;
 114     uint8_t end_sector;
 115     uint32_t start_sector_abs;
 116     uint32_t nb_sectors_abs;
 117 };
 118
 119 static void read_partition(uint8_t *p, struct partition_record *r)
 120 {
 121     r->bootable = p[0];
 122     r->start_head = p[1];
 123     r->start_cylinder = p[3] | ((p[2] << 2) & 0x0300);
 124     r->start_sector = p[2] & 0x3f;
 125     r->system = p[4];
 126     r->end_head = p[5];
 127     r->end_cylinder = p[7] | ((p[6] << 2) & 0x300);
 128     r->end_sector = p[6] & 0x3f;
 129     r->start_sector_abs = p[8] | p[9] << 8 | p[10] << 16 | p[11] << 24;
 130     r->nb_sectors_abs = p[12] | p[13] << 8 | p[14] << 16 | p[15] << 24;
 131 }
 132
 133 static int find_partition(BlockDriverState *bs, int partition,
 134                           off_t *offset, off_t *size)
 135 {
 136     struct partition_record mbr[4];
 137     uint8_t data[512];
 138     int i;
 139     int ext_partnum = 4;
 140     int ret;
 141
 142     if ((ret = bdrv_read(bs, 0, data, 1)) < 0) {
 143         errno = -ret;
 144         err(EXIT_FAILURE, "error while reading");
 145     }
 146
 147     if (data[510] != 0x55 || data[511] != 0xaa) {
 148         return -EINVAL;
 149     }
 150
 151     for (i = 0; i < 4; i++) {
 152         read_partition(&data[446 + 16 * i], &mbr[i]);
 153
 154         if (!mbr[i].nb_sectors_abs)
 155             continue;
 156
 157         if (mbr[i].system == 0xF || mbr[i].system == 0x5) {
 158             struct partition_record ext[4];
 159             uint8_t data1[512];
 160             int j;
 161
 162             if ((ret = bdrv_read(bs, mbr[i].start_sector_abs, data1, 1)) < 0) {
 163                 errno = -ret;
 164                 err(EXIT_FAILURE, "error while reading");
 165             }
 166
 167             for (j = 0; j < 4; j++) {
 168                 read_partition(&data1[446 + 16 * j], &ext[j]);
 169                 if (!ext[j].nb_sectors_abs)
 170                     continue;
 171
 172                 if ((ext_partnum + j + 1) == partition) {
 173                     *offset = (uint64_t)ext[j].start_sector_abs << 9;
 174                     *size = (uint64_t)ext[j].nb_sectors_abs << 9;
 175                     return 0;
 176                 }
 177             }
 178             ext_partnum += 4;
 179         } else if ((i + 1) == partition) {
 180             *offset = (uint64_t)mbr[i].start_sector_abs << 9;
 181             *size = (uint64_t)mbr[i].nb_sectors_abs << 9;
 182             return 0;
 183         }
 184     }
 185
 186     return -ENOENT;
 187 }
 188
 189 static void termsig_handler(int signum)
 190 {
 191     state = TERMINATE;
 192     qemu_notify_event();
 193 }
 194
 195 static void *show_parts(void *arg)
 196 {
 197     char *device = arg;
 198     int nbd;
 199
 200     /* linux just needs an open() to trigger
 201      * the partition table update
 202      * but remember to load the module with max_part != 0 :
 203      *     modprobe nbd max_part=63
 204      */
 205     nbd = open(device, O_RDWR);
 206     if (nbd >= 0) {
 207         close(nbd);
 208     }
 209     return NULL;
 210 }
 211
 212 static void *nbd_client_thread(void *arg)
 213 {
 214     char *device = arg;
 215     off_t size;
 216     size_t blocksize;
 217     uint32_t nbdflags;
 218     int fd, sock;
 219     int ret;
 220     pthread_t show_parts_thread;
 221
 222     sock = unix_socket_outgoing(sockpath);
 223     if (sock < 0) {
 224         goto out;
 225     }
 226
 227     ret = nbd_receive_negotiate(sock, NULL, &nbdflags,
 228                                 &size, &blocksize);
 229     if (ret < 0) {
 230         goto out;
 231     }
 232
 233     fd = open(device, O_RDWR);
 234     if (fd < 0) {
 235         /* Linux-only, we can use %m in printf.  */
 236         fprintf(stderr, "Failed to open %s: %m", device);
 237         goto out;
 238     }
 239
 240     ret = nbd_init(fd, sock, nbdflags, size, blocksize);
 241     if (ret < 0) {
 242         goto out;
 243     }
 244
 245     /* update partition table */
 246     pthread_create(&show_parts_thread, NULL, show_parts, device);
 247
 248     if (verbose) {
 249         fprintf(stderr, "NBD device %s is now connected to %s\n",
 250                 device, srcpath);
 251     } else {
 252         /* Close stderr so that the qemu-nbd process exits.  */
 253         dup2(STDOUT_FILENO, STDERR_FILENO);
 254     }
 255
 256     ret = nbd_client(fd);
 257     if (ret) {
 258         goto out;
 259     }
 260     close(fd);
 261     kill(getpid(), SIGTERM);
 262     return (void *) EXIT_SUCCESS;
 263
 264 out:
 265     kill(getpid(), SIGTERM);
 266     return (void *) EXIT_FAILURE;
 267 }
 268
 269 static int nbd_can_accept(void *opaque)
 270 {
 271     return nb_fds < shared;
 272 }
 273
 274 static void nbd_export_closed(NBDExport *exp)
 275 {
 276     assert(state == TERMINATING);
 277     state = TERMINATED;
 278 }
 279
 280 static void nbd_client_closed(NBDClient *client)
 281 {
 282     nb_fds--;
 283     if (nb_fds == 0 && !persistent && state == RUNNING) {
 284         state = TERMINATE;
 285     }
 286     qemu_notify_event();
 287     nbd_client_put(client);
 288 }
 289
 290 static void nbd_accept(void *opaque)
 291 {
 292     int server_fd = (uintptr_t) opaque;
 293     struct sockaddr_in addr;
 294     socklen_t addr_len = sizeof(addr);
 295
 296     int fd = accept(server_fd, (struct sockaddr *)&addr, &addr_len);
 297     if (state >= TERMINATE) {
 298         close(fd);
 299         return;
 300     }
 301
 302     if (fd >= 0 && nbd_client_new(exp, fd, nbd_client_closed)) {
 303         nb_fds++;
 304     }
 305 }
 306
 307 int main(int argc, char **argv)
 308 {
 309     BlockDriverState *bs;
 310     BlockDriver *drv;
 311     off_t dev_offset = 0;
 312     uint32_t nbdflags = 0;
 313     bool disconnect = false;
 314     const char *bindto = "0.0.0.0";
 315     char *device = NULL;
 316     int port = NBD_DEFAULT_PORT;
 317     off_t fd_size;
 318     const char *sopt = "hVb:o:p:rsnP:c:dvk:e:f:t";
 319     struct option lopt[] = {
 320         { "help", 0, NULL, 'h' },
 321         { "version", 0, NULL, 'V' },
 322         { "bind", 1, NULL, 'b' },
 323         { "port", 1, NULL, 'p' },
 324         { "socket", 1, NULL, 'k' },
 325         { "offset", 1, NULL, 'o' },
 326         { "read-only", 0, NULL, 'r' },
 327         { "partition", 1, NULL, 'P' },
 328         { "connect", 1, NULL, 'c' },
 329         { "disconnect", 0, NULL, 'd' },
 330         { "snapshot", 0, NULL, 's' },
 331         { "nocache", 0, NULL, 'n' },
 332         { "cache", 1, NULL, QEMU_NBD_OPT_CACHE },
 333 #ifdef CONFIG_LINUX_AIO
 334         { "aio", 1, NULL, QEMU_NBD_OPT_AIO },
 335 #endif
 336         { "discard", 1, NULL, QEMU_NBD_OPT_DISCARD },
 337         { "shared", 1, NULL, 'e' },
 338         { "format", 1, NULL, 'f' },
 339         { "persistent", 0, NULL, 't' },
 340         { "verbose", 0, NULL, 'v' },
 341         { NULL, 0, NULL, 0 }
 342     };
 343     int ch;
 344     int opt_ind = 0;
 345     int li;
 346     char *end;
 347     int flags = BDRV_O_RDWR;
 348     int partition = -1;
 349     int ret;
 350     int fd;
 351     bool seen_cache = false;
 352     bool seen_discard = false;
 353 #ifdef CONFIG_LINUX_AIO
 354     bool seen_aio = false;
 355 #endif
 356     pthread_t client_thread;
 357     const char *fmt = NULL;
 358
 359     /* The client thread uses SIGTERM to interrupt the server.  A signal
 360      * handler ensures that "qemu-nbd -v -c" exits with a nice status code.
 361      */
 362     struct sigaction sa_sigterm;
 363     memset(&sa_sigterm, 0, sizeof(sa_sigterm));
 364     sa_sigterm.sa_handler = termsig_handler;
 365     sigaction(SIGTERM, &sa_sigterm, NULL);
 366
 367     while ((ch = getopt_long(argc, argv, sopt, lopt, &opt_ind)) != -1) {
 368         switch (ch) {
 369         case 's':
 370             flags |= BDRV_O_SNAPSHOT;
 371             break;
 372         case 'n':
 373             optarg = (char *) "none";
 374             /* fallthrough */
 375         case QEMU_NBD_OPT_CACHE:
 376             if (seen_cache) {
 377                 errx(EXIT_FAILURE, "-n and --cache can only be specified once");
 378             }
 379             seen_cache = true;
 380             if (bdrv_parse_cache_flags(optarg, &flags) == -1) {
 381                 errx(EXIT_FAILURE, "Invalid cache mode `%s'", optarg);
 382             }
 383             break;
 384 #ifdef CONFIG_LINUX_AIO
 385         case QEMU_NBD_OPT_AIO:
 386             if (seen_aio) {
 387                 errx(EXIT_FAILURE, "--aio can only be specified once");
 388             }
 389             seen_aio = true;
 390             if (!strcmp(optarg, "native")) {
 391                 flags |= BDRV_O_NATIVE_AIO;
 392             } else if (!strcmp(optarg, "threads")) {
 393                 /* this is the default */
 394             } else {
 395                errx(EXIT_FAILURE, "invalid aio mode `%s'", optarg);
 396             }
 397             break;
 398 #endif
 399         case QEMU_NBD_OPT_DISCARD:
 400             if (seen_discard) {
 401                 errx(EXIT_FAILURE, "--discard can only be specified once");
 402             }
 403             seen_discard = true;
 404             if (bdrv_parse_discard_flags(optarg, &flags) == -1) {
 405                 errx(EXIT_FAILURE, "Invalid discard mode `%s'", optarg);
 406             }
 407             break;
 408         case 'b':
 409             bindto = optarg;
 410             break;
 411         case 'p':
 412             li = strtol(optarg, &end, 0);
 413             if (*end) {
 414                 errx(EXIT_FAILURE, "Invalid port `%s'", optarg);
 415             }
 416             if (li < 1 || li > 65535) {
 417                 errx(EXIT_FAILURE, "Port out of range `%s'", optarg);
 418             }
 419             port = (uint16_t)li;
 420             break;
 421         case 'o':
 422                 dev_offset = strtoll (optarg, &end, 0);
 423             if (*end) {
 424                 errx(EXIT_FAILURE, "Invalid offset `%s'", optarg);
 425             }
 426             if (dev_offset < 0) {
 427                 errx(EXIT_FAILURE, "Offset must be positive `%s'", optarg);
 428             }
 429             break;
 430         case 'r':
 431             nbdflags |= NBD_FLAG_READ_ONLY;
 432             flags &= ~BDRV_O_RDWR;
 433             break;
 434         case 'P':
 435             partition = strtol(optarg, &end, 0);
 436             if (*end)
 437                 errx(EXIT_FAILURE, "Invalid partition `%s'", optarg);
 438             if (partition < 1 || partition > 8)
 439                 errx(EXIT_FAILURE, "Invalid partition %d", partition);
 440             break;
 441         case 'k':
 442             sockpath = optarg;
 443             if (sockpath[0] != '/')
 444                 errx(EXIT_FAILURE, "socket path must be absolute\n");
 445             break;
 446         case 'd':
 447             disconnect = true;
 448             break;
 449         case 'c':
 450             device = optarg;
 451             break;
 452         case 'e':
 453             shared = strtol(optarg, &end, 0);
 454             if (*end) {
 455                 errx(EXIT_FAILURE, "Invalid shared device number '%s'", optarg);
 456             }
 457             if (shared < 1) {
 458                 errx(EXIT_FAILURE, "Shared device number must be greater than 0\n");
 459             }
 460             break;
 461         case 'f':
 462             fmt = optarg;
 463             break;
 464         case 't':
 465             persistent = 1;
 466             break;
 467         case 'v':
 468             verbose = 1;
 469             break;
 470         case 'V':
 471             version(argv[0]);
 472             exit(0);
 473             break;
 474         case 'h':
 475             usage(argv[0]);
 476             exit(0);
 477             break;
 478         case '?':
 479             errx(EXIT_FAILURE, "Try `%s --help' for more information.",
 480                  argv[0]);
 481         }
 482     }
 483
 484     if ((argc - optind) != 1) {
 485         errx(EXIT_FAILURE, "Invalid number of argument.\n"
 486              "Try `%s --help' for more information.",
 487              argv[0]);
 488     }
 489
 490     if (disconnect) {
 491         fd = open(argv[optind], O_RDWR);
 492         if (fd < 0) {
 493             err(EXIT_FAILURE, "Cannot open %s", argv[optind]);
 494         }
 495         nbd_disconnect(fd);
 496
 497         close(fd);
 498
 499         printf("%s disconnected\n", argv[optind]);
 500
 501         return 0;
 502     }
 503
 504     if (device && !verbose) {
 505         int stderr_fd[2];
 506         pid_t pid;
 507         int ret;
 508
 509         if (qemu_pipe(stderr_fd) < 0) {
 510             err(EXIT_FAILURE, "Error setting up communication pipe");
 511         }
 512
 513         /* Now daemonize, but keep a communication channel open to
 514          * print errors and exit with the proper status code.
 515          */
 516         pid = fork();
 517         if (pid == 0) {
 518             close(stderr_fd[0]);
 519             ret = qemu_daemon(1, 0);
 520
 521             /* Temporarily redirect stderr to the parent's pipe...  */
 522             dup2(stderr_fd[1], STDERR_FILENO);
 523             if (ret < 0) {
 524                 err(EXIT_FAILURE, "Failed to daemonize");
 525             }
 526
 527             /* ... close the descriptor we inherited and go on.  */
 528             close(stderr_fd[1]);
 529         } else {
 530             bool errors = false;
 531             char *buf;
 532
 533             /* In the parent.  Print error messages from the child until
 534              * it closes the pipe.
 535              */
 536             close(stderr_fd[1]);
 537             buf = g_malloc(1024);
 538             while ((ret = read(stderr_fd[0], buf, 1024)) > 0) {
 539                 errors = true;
 540                 ret = qemu_write_full(STDERR_FILENO, buf, ret);
 541                 if (ret < 0) {
 542                     exit(EXIT_FAILURE);
 543                 }
 544             }
 545             if (ret < 0) {
 546                 err(EXIT_FAILURE, "Cannot read from daemon");
 547             }
 548
 549             /* Usually the daemon should not print any message.
 550              * Exit with zero status in that case.
 551              */
 552             exit(errors);
 553         }
 554     }
 555
 556     if (device != NULL && sockpath == NULL) {
 557         sockpath = g_malloc(128);
 558         snprintf(sockpath, 128, SOCKET_PATH, basename(device));
 559     }
 560
 561     qemu_init_main_loop();
 562     bdrv_init();
 563     atexit(bdrv_close_all);
 564
 565     if (fmt) {
 566         drv = bdrv_find_format(fmt);
 567         if (!drv) {
 568             errx(EXIT_FAILURE, "Unknown file format '%s'", fmt);
 569         }
 570     } else {
 571         drv = NULL;
 572     }
 573
 574     bs = bdrv_new("hda");
 575     srcpath = argv[optind];
 576     ret = bdrv_open(bs, srcpath, NULL, flags, drv);
 577     if (ret < 0) {
 578         errno = -ret;
 579         err(EXIT_FAILURE, "Failed to bdrv_open '%s'", argv[optind]);
 580     }
 581
 582     fd_size = bdrv_getlength(bs);
 583
 584     if (partition != -1) {
 585         ret = find_partition(bs, partition, &dev_offset, &fd_size);
 586         if (ret < 0) {
 587             errno = -ret;
 588             err(EXIT_FAILURE, "Could not find partition %d", partition);
 589         }
 590     }
 591
 592     exp = nbd_export_new(bs, dev_offset, fd_size, nbdflags, nbd_export_closed);
 593
 594     if (sockpath) {
 595         fd = unix_socket_incoming(sockpath);
 596     } else {
 597         fd = tcp_socket_incoming(bindto, port);
 598     }
 599
 600     if (fd < 0) {
 601         return 1;
 602     }
 603
 604     if (device) {
 605         int ret;
 606
 607         ret = pthread_create(&client_thread, NULL, nbd_client_thread, device);
 608         if (ret != 0) {
 609             errx(EXIT_FAILURE, "Failed to create client thread: %s",
 610                  strerror(ret));
 611         }
 612     } else {
 613         /* Shut up GCC warnings.  */
 614         memset(&client_thread, 0, sizeof(client_thread));
 615     }
 616
 617     qemu_set_fd_handler2(fd, nbd_can_accept, nbd_accept, NULL,
 618                          (void *)(uintptr_t)fd);
 619
 620     /* now when the initialization is (almost) complete, chdir("/")
 621      * to free any busy filesystems */
 622     if (chdir("/") < 0) {
 623         err(EXIT_FAILURE, "Could not chdir to root directory");
 624     }
 625
 626     state = RUNNING;
 627     do {
 628         main_loop_wait(false);
 629         if (state == TERMINATE) {
 630             state = TERMINATING;
 631             nbd_export_close(exp);
 632             nbd_export_put(exp);
 633             exp = NULL;
 634         }
 635     } while (state != TERMINATED);
 636
 637     bdrv_close(bs);
 638     if (sockpath) {
 639         unlink(sockpath);
 640     }
 641
 642     if (device) {
 643         void *ret;
 644         pthread_join(client_thread, &ret);
 645         exit(ret != NULL);
 646     } else {
 647         exit(EXIT_SUCCESS);
 648     }
 649 }