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     Error *local_err = NULL;
 359
 360     /* The client thread uses SIGTERM to interrupt the server.  A signal
 361      * handler ensures that "qemu-nbd -v -c" exits with a nice status code.
 362      */
 363     struct sigaction sa_sigterm;
 364     memset(&sa_sigterm, 0, sizeof(sa_sigterm));
 365     sa_sigterm.sa_handler = termsig_handler;
 366     sigaction(SIGTERM, &sa_sigterm, NULL);
 367
 368     while ((ch = getopt_long(argc, argv, sopt, lopt, &opt_ind)) != -1) {
 369         switch (ch) {
 370         case 's':
 371             flags |= BDRV_O_SNAPSHOT;
 372             break;
 373         case 'n':
 374             optarg = (char *) "none";
 375             /* fallthrough */
 376         case QEMU_NBD_OPT_CACHE:
 377             if (seen_cache) {
 378                 errx(EXIT_FAILURE, "-n and --cache can only be specified once");
 379             }
 380             seen_cache = true;
 381             if (bdrv_parse_cache_flags(optarg, &flags) == -1) {
 382                 errx(EXIT_FAILURE, "Invalid cache mode `%s'", optarg);
 383             }
 384             break;
 385 #ifdef CONFIG_LINUX_AIO
 386         case QEMU_NBD_OPT_AIO:
 387             if (seen_aio) {
 388                 errx(EXIT_FAILURE, "--aio can only be specified once");
 389             }
 390             seen_aio = true;
 391             if (!strcmp(optarg, "native")) {
 392                 flags |= BDRV_O_NATIVE_AIO;
 393             } else if (!strcmp(optarg, "threads")) {
 394                 /* this is the default */
 395             } else {
 396                errx(EXIT_FAILURE, "invalid aio mode `%s'", optarg);
 397             }
 398             break;
 399 #endif
 400         case QEMU_NBD_OPT_DISCARD:
 401             if (seen_discard) {
 402                 errx(EXIT_FAILURE, "--discard can only be specified once");
 403             }
 404             seen_discard = true;
 405             if (bdrv_parse_discard_flags(optarg, &flags) == -1) {
 406                 errx(EXIT_FAILURE, "Invalid discard mode `%s'", optarg);
 407             }
 408             break;
 409         case 'b':
 410             bindto = optarg;
 411             break;
 412         case 'p':
 413             li = strtol(optarg, &end, 0);
 414             if (*end) {
 415                 errx(EXIT_FAILURE, "Invalid port `%s'", optarg);
 416             }
 417             if (li < 1 || li > 65535) {
 418                 errx(EXIT_FAILURE, "Port out of range `%s'", optarg);
 419             }
 420             port = (uint16_t)li;
 421             break;
 422         case 'o':
 423                 dev_offset = strtoll (optarg, &end, 0);
 424             if (*end) {
 425                 errx(EXIT_FAILURE, "Invalid offset `%s'", optarg);
 426             }
 427             if (dev_offset < 0) {
 428                 errx(EXIT_FAILURE, "Offset must be positive `%s'", optarg);
 429             }
 430             break;
 431         case 'r':
 432             nbdflags |= NBD_FLAG_READ_ONLY;
 433             flags &= ~BDRV_O_RDWR;
 434             break;
 435         case 'P':
 436             partition = strtol(optarg, &end, 0);
 437             if (*end)
 438                 errx(EXIT_FAILURE, "Invalid partition `%s'", optarg);
 439             if (partition < 1 || partition > 8)
 440                 errx(EXIT_FAILURE, "Invalid partition %d", partition);
 441             break;
 442         case 'k':
 443             sockpath = optarg;
 444             if (sockpath[0] != '/')
 445                 errx(EXIT_FAILURE, "socket path must be absolute\n");
 446             break;
 447         case 'd':
 448             disconnect = true;
 449             break;
 450         case 'c':
 451             device = optarg;
 452             break;
 453         case 'e':
 454             shared = strtol(optarg, &end, 0);
 455             if (*end) {
 456                 errx(EXIT_FAILURE, "Invalid shared device number '%s'", optarg);
 457             }
 458             if (shared < 1) {
 459                 errx(EXIT_FAILURE, "Shared device number must be greater than 0\n");
 460             }
 461             break;
 462         case 'f':
 463             fmt = optarg;
 464             break;
 465         case 't':
 466             persistent = 1;
 467             break;
 468         case 'v':
 469             verbose = 1;
 470             break;
 471         case 'V':
 472             version(argv[0]);
 473             exit(0);
 474             break;
 475         case 'h':
 476             usage(argv[0]);
 477             exit(0);
 478             break;
 479         case '?':
 480             errx(EXIT_FAILURE, "Try `%s --help' for more information.",
 481                  argv[0]);
 482         }
 483     }
 484
 485     if ((argc - optind) != 1) {
 486         errx(EXIT_FAILURE, "Invalid number of argument.\n"
 487              "Try `%s --help' for more information.",
 488              argv[0]);
 489     }
 490
 491     if (disconnect) {
 492         fd = open(argv[optind], O_RDWR);
 493         if (fd < 0) {
 494             err(EXIT_FAILURE, "Cannot open %s", argv[optind]);
 495         }
 496         nbd_disconnect(fd);
 497
 498         close(fd);
 499
 500         printf("%s disconnected\n", argv[optind]);
 501
 502         return 0;
 503     }
 504
 505     if (device && !verbose) {
 506         int stderr_fd[2];
 507         pid_t pid;
 508         int ret;
 509
 510         if (qemu_pipe(stderr_fd) < 0) {
 511             err(EXIT_FAILURE, "Error setting up communication pipe");
 512         }
 513
 514         /* Now daemonize, but keep a communication channel open to
 515          * print errors and exit with the proper status code.
 516          */
 517         pid = fork();
 518         if (pid == 0) {
 519             close(stderr_fd[0]);
 520             ret = qemu_daemon(1, 0);
 521
 522             /* Temporarily redirect stderr to the parent's pipe...  */
 523             dup2(stderr_fd[1], STDERR_FILENO);
 524             if (ret < 0) {
 525                 err(EXIT_FAILURE, "Failed to daemonize");
 526             }
 527
 528             /* ... close the descriptor we inherited and go on.  */
 529             close(stderr_fd[1]);
 530         } else {
 531             bool errors = false;
 532             char *buf;
 533
 534             /* In the parent.  Print error messages from the child until
 535              * it closes the pipe.
 536              */
 537             close(stderr_fd[1]);
 538             buf = g_malloc(1024);
 539             while ((ret = read(stderr_fd[0], buf, 1024)) > 0) {
 540                 errors = true;
 541                 ret = qemu_write_full(STDERR_FILENO, buf, ret);
 542                 if (ret < 0) {
 543                     exit(EXIT_FAILURE);
 544                 }
 545             }
 546             if (ret < 0) {
 547                 err(EXIT_FAILURE, "Cannot read from daemon");
 548             }
 549
 550             /* Usually the daemon should not print any message.
 551              * Exit with zero status in that case.
 552              */
 553             exit(errors);
 554         }
 555     }
 556
 557     if (device != NULL && sockpath == NULL) {
 558         sockpath = g_malloc(128);
 559         snprintf(sockpath, 128, SOCKET_PATH, basename(device));
 560     }
 561
 562     qemu_init_main_loop();
 563     bdrv_init();
 564     atexit(bdrv_close_all);
 565
 566     if (fmt) {
 567         drv = bdrv_find_format(fmt);
 568         if (!drv) {
 569             errx(EXIT_FAILURE, "Unknown file format '%s'", fmt);
 570         }
 571     } else {
 572         drv = NULL;
 573     }
 574
 575     bs = bdrv_new("hda");
 576     srcpath = argv[optind];
 577     ret = bdrv_open(bs, srcpath, NULL, flags, drv, &local_err);
 578     if (ret < 0) {
 579         errno = -ret;
 580         err(EXIT_FAILURE, "Failed to bdrv_open '%s': %s", argv[optind],
 581             error_get_pretty(local_err));
 582     }
 583
 584     fd_size = bdrv_getlength(bs);
 585
 586     if (partition != -1) {
 587         ret = find_partition(bs, partition, &dev_offset, &fd_size);
 588         if (ret < 0) {
 589             errno = -ret;
 590             err(EXIT_FAILURE, "Could not find partition %d", partition);
 591         }
 592     }
 593
 594     exp = nbd_export_new(bs, dev_offset, fd_size, nbdflags, nbd_export_closed);
 595
 596     if (sockpath) {
 597         fd = unix_socket_incoming(sockpath);
 598     } else {
 599         fd = tcp_socket_incoming(bindto, port);
 600     }
 601
 602     if (fd < 0) {
 603         return 1;
 604     }
 605
 606     if (device) {
 607         int ret;
 608
 609         ret = pthread_create(&client_thread, NULL, nbd_client_thread, device);
 610         if (ret != 0) {
 611             errx(EXIT_FAILURE, "Failed to create client thread: %s",
 612                  strerror(ret));
 613         }
 614     } else {
 615         /* Shut up GCC warnings.  */
 616         memset(&client_thread, 0, sizeof(client_thread));
 617     }
 618
 619     qemu_set_fd_handler2(fd, nbd_can_accept, nbd_accept, NULL,
 620                          (void *)(uintptr_t)fd);
 621
 622     /* now when the initialization is (almost) complete, chdir("/")
 623      * to free any busy filesystems */
 624     if (chdir("/") < 0) {
 625         err(EXIT_FAILURE, "Could not chdir to root directory");
 626     }
 627
 628     state = RUNNING;
 629     do {
 630         main_loop_wait(false);
 631         if (state == TERMINATE) {
 632             state = TERMINATING;
 633             nbd_export_close(exp);
 634             nbd_export_put(exp);
 635             exp = NULL;
 636         }
 637     } while (state != TERMINATED);
 638
 639     bdrv_close(bs);
 640     if (sockpath) {
 641         unlink(sockpath);
 642     }
 643
 644     if (device) {
 645         void *ret;
 646         pthread_join(client_thread, &ret);
 647         exit(ret != NULL);
 648     } else {
 649         exit(EXIT_SUCCESS);
 650     }
 651 }