net/tap.c

   1 /*
   2  * QEMU System Emulator
   3  *
   4  * Copyright (c) 2003-2008 Fabrice Bellard
   5  * Copyright (c) 2009 Red Hat, Inc.
   6  *
   7  * Permission is hereby granted, free of charge, to any person obtaining a copy
   8  * of this software and associated documentation files (the "Software"), to deal
   9  * in the Software without restriction, including without limitation the rights
  10  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  11  * copies of the Software, and to permit persons to whom the Software is
  12  * furnished to do so, subject to the following conditions:
  13  *
  14  * The above copyright notice and this permission notice shall be included in
  15  * all copies or substantial portions of the Software.
  16  *
  17  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  18  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  19  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
  20  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  21  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  22  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  23  * THE SOFTWARE.
  24  */
  25
  26 #include "qemu/osdep.h"
  27 #include "tap_int.h"
  28
  29
  30 #include <sys/ioctl.h>
  31 #include <sys/wait.h>
  32 #include <sys/socket.h>
  33 #include <net/if.h>
  34
  35 #include "net/eth.h"
  36 #include "net/net.h"
  37 #include "clients.h"
  38 #include "monitor/monitor.h"
  39 #include "sysemu/sysemu.h"
  40 #include "qapi/error.h"
  41 #include "qemu/cutils.h"
  42 #include "qemu/error-report.h"
  43 #include "qemu/main-loop.h"
  44 #include "qemu/sockets.h"
  45
  46 #include "net/tap.h"
  47
  48 #include "net/vhost_net.h"
  49
  50 typedef struct TAPState {
  51     NetClientState nc;
  52     int fd;
  53     char down_script[1024];
  54     char down_script_arg[128];
  55     uint8_t buf[NET_BUFSIZE];
  56     bool read_poll;
  57     bool write_poll;
  58     bool using_vnet_hdr;
  59     bool has_ufo;
  60     bool enabled;
  61     VHostNetState *vhost_net;
  62     unsigned host_vnet_hdr_len;
  63     Notifier exit;
  64 } TAPState;
  65
  66 static void launch_script(const char *setup_script, const char *ifname,
  67                           int fd, Error **errp);
  68
  69 static void tap_send(void *opaque);
  70 static void tap_writable(void *opaque);
  71
  72 static void tap_update_fd_handler(TAPState *s)
  73 {
  74     qemu_set_fd_handler(s->fd,
  75                         s->read_poll && s->enabled ? tap_send : NULL,
  76                         s->write_poll && s->enabled ? tap_writable : NULL,
  77                         s);
  78 }
  79
  80 static void tap_read_poll(TAPState *s, bool enable)
  81 {
  82     s->read_poll = enable;
  83     tap_update_fd_handler(s);
  84 }
  85
  86 static void tap_write_poll(TAPState *s, bool enable)
  87 {
  88     s->write_poll = enable;
  89     tap_update_fd_handler(s);
  90 }
  91
  92 static void tap_writable(void *opaque)
  93 {
  94     TAPState *s = opaque;
  95
  96     tap_write_poll(s, false);
  97
  98     qemu_flush_queued_packets(&s->nc);
  99 }
 100
 101 static ssize_t tap_write_packet(TAPState *s, const struct iovec *iov, int iovcnt)
 102 {
 103     ssize_t len;
 104
 105     do {
 106         len = writev(s->fd, iov, iovcnt);
 107     } while (len == -1 && errno == EINTR);
 108
 109     if (len == -1 && errno == EAGAIN) {
 110         tap_write_poll(s, true);
 111         return 0;
 112     }
 113
 114     return len;
 115 }
 116
 117 static ssize_t tap_receive_iov(NetClientState *nc, const struct iovec *iov,
 118                                int iovcnt)
 119 {
 120     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 121     const struct iovec *iovp = iov;
 122     struct iovec iov_copy[iovcnt + 1];
 123     struct virtio_net_hdr_mrg_rxbuf hdr = { };
 124
 125     if (s->host_vnet_hdr_len && !s->using_vnet_hdr) {
 126         iov_copy[0].iov_base = &hdr;
 127         iov_copy[0].iov_len =  s->host_vnet_hdr_len;
 128         memcpy(&iov_copy[1], iov, iovcnt * sizeof(*iov));
 129         iovp = iov_copy;
 130         iovcnt++;
 131     }
 132
 133     return tap_write_packet(s, iovp, iovcnt);
 134 }
 135
 136 static ssize_t tap_receive_raw(NetClientState *nc, const uint8_t *buf, size_t size)
 137 {
 138     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 139     struct iovec iov[2];
 140     int iovcnt = 0;
 141     struct virtio_net_hdr_mrg_rxbuf hdr = { };
 142
 143     if (s->host_vnet_hdr_len) {
 144         iov[iovcnt].iov_base = &hdr;
 145         iov[iovcnt].iov_len  = s->host_vnet_hdr_len;
 146         iovcnt++;
 147     }
 148
 149     iov[iovcnt].iov_base = (char *)buf;
 150     iov[iovcnt].iov_len  = size;
 151     iovcnt++;
 152
 153     return tap_write_packet(s, iov, iovcnt);
 154 }
 155
 156 static ssize_t tap_receive(NetClientState *nc, const uint8_t *buf, size_t size)
 157 {
 158     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 159     struct iovec iov[1];
 160
 161     if (s->host_vnet_hdr_len && !s->using_vnet_hdr) {
 162         return tap_receive_raw(nc, buf, size);
 163     }
 164
 165     iov[0].iov_base = (char *)buf;
 166     iov[0].iov_len  = size;
 167
 168     return tap_write_packet(s, iov, 1);
 169 }
 170
 171 #ifndef __sun__
 172 ssize_t tap_read_packet(int tapfd, uint8_t *buf, int maxlen)
 173 {
 174     return read(tapfd, buf, maxlen);
 175 }
 176 #endif
 177
 178 static void tap_send_completed(NetClientState *nc, ssize_t len)
 179 {
 180     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 181     tap_read_poll(s, true);
 182 }
 183
 184 static void tap_send(void *opaque)
 185 {
 186     TAPState *s = opaque;
 187     int size;
 188     int packets = 0;
 189
 190     while (true) {
 191         uint8_t *buf = s->buf;
 192         uint8_t min_pkt[ETH_ZLEN];
 193         size_t min_pktsz = sizeof(min_pkt);
 194
 195         size = tap_read_packet(s->fd, s->buf, sizeof(s->buf));
 196         if (size <= 0) {
 197             break;
 198         }
 199
 200         if (s->host_vnet_hdr_len && !s->using_vnet_hdr) {
 201             buf  += s->host_vnet_hdr_len;
 202             size -= s->host_vnet_hdr_len;
 203         }
 204
 205         if (net_peer_needs_padding(&s->nc)) {
 206             if (eth_pad_short_frame(min_pkt, &min_pktsz, buf, size)) {
 207                 buf = min_pkt;
 208                 size = min_pktsz;
 209             }
 210         }
 211
 212         size = qemu_send_packet_async(&s->nc, buf, size, tap_send_completed);
 213         if (size == 0) {
 214             tap_read_poll(s, false);
 215             break;
 216         } else if (size < 0) {
 217             break;
 218         }
 219
 220         /*
 221          * When the host keeps receiving more packets while tap_send() is
 222          * running we can hog the QEMU global mutex.  Limit the number of
 223          * packets that are processed per tap_send() callback to prevent
 224          * stalling the guest.
 225          */
 226         packets++;
 227         if (packets >= 50) {
 228             break;
 229         }
 230     }
 231 }
 232
 233 static bool tap_has_ufo(NetClientState *nc)
 234 {
 235     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 236
 237     assert(nc->info->type == NET_CLIENT_DRIVER_TAP);
 238
 239     return s->has_ufo;
 240 }
 241
 242 static bool tap_has_vnet_hdr(NetClientState *nc)
 243 {
 244     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 245
 246     assert(nc->info->type == NET_CLIENT_DRIVER_TAP);
 247
 248     return !!s->host_vnet_hdr_len;
 249 }
 250
 251 static bool tap_has_vnet_hdr_len(NetClientState *nc, int len)
 252 {
 253     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 254
 255     assert(nc->info->type == NET_CLIENT_DRIVER_TAP);
 256
 257     return !!tap_probe_vnet_hdr_len(s->fd, len);
 258 }
 259
 260 static void tap_set_vnet_hdr_len(NetClientState *nc, int len)
 261 {
 262     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 263
 264     assert(nc->info->type == NET_CLIENT_DRIVER_TAP);
 265     assert(len == sizeof(struct virtio_net_hdr_mrg_rxbuf) ||
 266            len == sizeof(struct virtio_net_hdr) ||
 267            len == sizeof(struct virtio_net_hdr_v1_hash));
 268
 269     tap_fd_set_vnet_hdr_len(s->fd, len);
 270     s->host_vnet_hdr_len = len;
 271 }
 272
 273 static void tap_using_vnet_hdr(NetClientState *nc, bool using_vnet_hdr)
 274 {
 275     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 276
 277     assert(nc->info->type == NET_CLIENT_DRIVER_TAP);
 278     assert(!!s->host_vnet_hdr_len == using_vnet_hdr);
 279
 280     s->using_vnet_hdr = using_vnet_hdr;
 281 }
 282
 283 static int tap_set_vnet_le(NetClientState *nc, bool is_le)
 284 {
 285     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 286
 287     return tap_fd_set_vnet_le(s->fd, is_le);
 288 }
 289
 290 static int tap_set_vnet_be(NetClientState *nc, bool is_be)
 291 {
 292     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 293
 294     return tap_fd_set_vnet_be(s->fd, is_be);
 295 }
 296
 297 static void tap_set_offload(NetClientState *nc, int csum, int tso4,
 298                      int tso6, int ecn, int ufo)
 299 {
 300     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 301     if (s->fd < 0) {
 302         return;
 303     }
 304
 305     tap_fd_set_offload(s->fd, csum, tso4, tso6, ecn, ufo);
 306 }
 307
 308 static void tap_exit_notify(Notifier *notifier, void *data)
 309 {
 310     TAPState *s = container_of(notifier, TAPState, exit);
 311     Error *err = NULL;
 312
 313     if (s->down_script[0]) {
 314         launch_script(s->down_script, s->down_script_arg, s->fd, &err);
 315         if (err) {
 316             error_report_err(err);
 317         }
 318     }
 319 }
 320
 321 static void tap_cleanup(NetClientState *nc)
 322 {
 323     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 324
 325     if (s->vhost_net) {
 326         vhost_net_cleanup(s->vhost_net);
 327         g_free(s->vhost_net);
 328         s->vhost_net = NULL;
 329     }
 330
 331     qemu_purge_queued_packets(nc);
 332
 333     tap_exit_notify(&s->exit, NULL);
 334     qemu_remove_exit_notifier(&s->exit);
 335
 336     tap_read_poll(s, false);
 337     tap_write_poll(s, false);
 338     close(s->fd);
 339     s->fd = -1;
 340 }
 341
 342 static void tap_poll(NetClientState *nc, bool enable)
 343 {
 344     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 345     tap_read_poll(s, enable);
 346     tap_write_poll(s, enable);
 347 }
 348
 349 static bool tap_set_steering_ebpf(NetClientState *nc, int prog_fd)
 350 {
 351     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 352     assert(nc->info->type == NET_CLIENT_DRIVER_TAP);
 353
 354     return tap_fd_set_steering_ebpf(s->fd, prog_fd) == 0;
 355 }
 356
 357 int tap_get_fd(NetClientState *nc)
 358 {
 359     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 360     assert(nc->info->type == NET_CLIENT_DRIVER_TAP);
 361     return s->fd;
 362 }
 363
 364 /* fd support */
 365
 366 static NetClientInfo net_tap_info = {
 367     .type = NET_CLIENT_DRIVER_TAP,
 368     .size = sizeof(TAPState),
 369     .receive = tap_receive,
 370     .receive_raw = tap_receive_raw,
 371     .receive_iov = tap_receive_iov,
 372     .poll = tap_poll,
 373     .cleanup = tap_cleanup,
 374     .has_ufo = tap_has_ufo,
 375     .has_vnet_hdr = tap_has_vnet_hdr,
 376     .has_vnet_hdr_len = tap_has_vnet_hdr_len,
 377     .using_vnet_hdr = tap_using_vnet_hdr,
 378     .set_offload = tap_set_offload,
 379     .set_vnet_hdr_len = tap_set_vnet_hdr_len,
 380     .set_vnet_le = tap_set_vnet_le,
 381     .set_vnet_be = tap_set_vnet_be,
 382     .set_steering_ebpf = tap_set_steering_ebpf,
 383 };
 384
 385 static TAPState *net_tap_fd_init(NetClientState *peer,
 386                                  const char *model,
 387                                  const char *name,
 388                                  int fd,
 389                                  int vnet_hdr)
 390 {
 391     NetClientState *nc;
 392     TAPState *s;
 393
 394     nc = qemu_new_net_client(&net_tap_info, peer, model, name);
 395
 396     s = DO_UPCAST(TAPState, nc, nc);
 397
 398     s->fd = fd;
 399     s->host_vnet_hdr_len = vnet_hdr ? sizeof(struct virtio_net_hdr) : 0;
 400     s->using_vnet_hdr = false;
 401     s->has_ufo = tap_probe_has_ufo(s->fd);
 402     s->enabled = true;
 403     tap_set_offload(&s->nc, 0, 0, 0, 0, 0);
 404     /*
 405      * Make sure host header length is set correctly in tap:
 406      * it might have been modified by another instance of qemu.
 407      */
 408     if (tap_probe_vnet_hdr_len(s->fd, s->host_vnet_hdr_len)) {
 409         tap_fd_set_vnet_hdr_len(s->fd, s->host_vnet_hdr_len);
 410     }
 411     tap_read_poll(s, true);
 412     s->vhost_net = NULL;
 413
 414     s->exit.notify = tap_exit_notify;
 415     qemu_add_exit_notifier(&s->exit);
 416
 417     return s;
 418 }
 419
 420 static void launch_script(const char *setup_script, const char *ifname,
 421                           int fd, Error **errp)
 422 {
 423     int pid, status;
 424     char *args[3];
 425     char **parg;
 426
 427     /* try to launch network script */
 428     pid = fork();
 429     if (pid < 0) {
 430         error_setg_errno(errp, errno, "could not launch network script %s",
 431                          setup_script);
 432         return;
 433     }
 434     if (pid == 0) {
 435         int open_max = sysconf(_SC_OPEN_MAX), i;
 436
 437         for (i = 3; i < open_max; i++) {
 438             if (i != fd) {
 439                 close(i);
 440             }
 441         }
 442         parg = args;
 443         *parg++ = (char *)setup_script;
 444         *parg++ = (char *)ifname;
 445         *parg = NULL;
 446         execv(setup_script, args);
 447         _exit(1);
 448     } else {
 449         while (waitpid(pid, &status, 0) != pid) {
 450             /* loop */
 451         }
 452
 453         if (WIFEXITED(status) && WEXITSTATUS(status) == 0) {
 454             return;
 455         }
 456         error_setg(errp, "network script %s failed with status %d",
 457                    setup_script, status);
 458     }
 459 }
 460
 461 static int recv_fd(int c)
 462 {
 463     int fd;
 464     uint8_t msgbuf[CMSG_SPACE(sizeof(fd))];
 465     struct msghdr msg = {
 466         .msg_control = msgbuf,
 467         .msg_controllen = sizeof(msgbuf),
 468     };
 469     struct cmsghdr *cmsg;
 470     struct iovec iov;
 471     uint8_t req[1];
 472     ssize_t len;
 473
 474     cmsg = CMSG_FIRSTHDR(&msg);
 475     cmsg->cmsg_level = SOL_SOCKET;
 476     cmsg->cmsg_type = SCM_RIGHTS;
 477     cmsg->cmsg_len = CMSG_LEN(sizeof(fd));
 478     msg.msg_controllen = cmsg->cmsg_len;
 479
 480     iov.iov_base = req;
 481     iov.iov_len = sizeof(req);
 482
 483     msg.msg_iov = &iov;
 484     msg.msg_iovlen = 1;
 485
 486     len = recvmsg(c, &msg, 0);
 487     if (len > 0) {
 488         memcpy(&fd, CMSG_DATA(cmsg), sizeof(fd));
 489         return fd;
 490     }
 491
 492     return len;
 493 }
 494
 495 static int net_bridge_run_helper(const char *helper, const char *bridge,
 496                                  Error **errp)
 497 {
 498     sigset_t oldmask, mask;
 499     g_autofree char *default_helper = NULL;
 500     int pid, status;
 501     char *args[5];
 502     char **parg;
 503     int sv[2];
 504
 505     sigemptyset(&mask);
 506     sigaddset(&mask, SIGCHLD);
 507     sigprocmask(SIG_BLOCK, &mask, &oldmask);
 508
 509     if (!helper) {
 510         helper = default_helper = get_relocated_path(DEFAULT_BRIDGE_HELPER);
 511     }
 512
 513     if (socketpair(PF_UNIX, SOCK_STREAM, 0, sv) == -1) {
 514         error_setg_errno(errp, errno, "socketpair() failed");
 515         return -1;
 516     }
 517
 518     /* try to launch bridge helper */
 519     pid = fork();
 520     if (pid < 0) {
 521         error_setg_errno(errp, errno, "Can't fork bridge helper");
 522         return -1;
 523     }
 524     if (pid == 0) {
 525         int open_max = sysconf(_SC_OPEN_MAX), i;
 526         char *fd_buf = NULL;
 527         char *br_buf = NULL;
 528         char *helper_cmd = NULL;
 529
 530         for (i = 3; i < open_max; i++) {
 531             if (i != sv[1]) {
 532                 close(i);
 533             }
 534         }
 535
 536         fd_buf = g_strdup_printf("%s%d", "--fd=", sv[1]);
 537
 538         if (strrchr(helper, ' ') || strrchr(helper, '\t')) {
 539             /* assume helper is a command */
 540
 541             if (strstr(helper, "--br=") == NULL) {
 542                 br_buf = g_strdup_printf("%s%s", "--br=", bridge);
 543             }
 544
 545             helper_cmd = g_strdup_printf("%s %s %s %s", helper,
 546                             "--use-vnet", fd_buf, br_buf ? br_buf : "");
 547
 548             parg = args;
 549             *parg++ = (char *)"sh";
 550             *parg++ = (char *)"-c";
 551             *parg++ = helper_cmd;
 552             *parg++ = NULL;
 553
 554             execv("/bin/sh", args);
 555             g_free(helper_cmd);
 556         } else {
 557             /* assume helper is just the executable path name */
 558
 559             br_buf = g_strdup_printf("%s%s", "--br=", bridge);
 560
 561             parg = args;
 562             *parg++ = (char *)helper;
 563             *parg++ = (char *)"--use-vnet";
 564             *parg++ = fd_buf;
 565             *parg++ = br_buf;
 566             *parg++ = NULL;
 567
 568             execv(helper, args);
 569         }
 570         g_free(fd_buf);
 571         g_free(br_buf);
 572         _exit(1);
 573
 574     } else {
 575         int fd;
 576         int saved_errno;
 577
 578         close(sv[1]);
 579
 580         do {
 581             fd = recv_fd(sv[0]);
 582         } while (fd == -1 && errno == EINTR);
 583         saved_errno = errno;
 584
 585         close(sv[0]);
 586
 587         while (waitpid(pid, &status, 0) != pid) {
 588             /* loop */
 589         }
 590         sigprocmask(SIG_SETMASK, &oldmask, NULL);
 591         if (fd < 0) {
 592             error_setg_errno(errp, saved_errno,
 593                              "failed to recv file descriptor");
 594             return -1;
 595         }
 596         if (!WIFEXITED(status) || WEXITSTATUS(status) != 0) {
 597             error_setg(errp, "bridge helper failed");
 598             return -1;
 599         }
 600         return fd;
 601     }
 602 }
 603
 604 int net_init_bridge(const Netdev *netdev, const char *name,
 605                     NetClientState *peer, Error **errp)
 606 {
 607     const NetdevBridgeOptions *bridge;
 608     const char *helper, *br;
 609     TAPState *s;
 610     int fd, vnet_hdr;
 611
 612     assert(netdev->type == NET_CLIENT_DRIVER_BRIDGE);
 613     bridge = &netdev->u.bridge;
 614     helper = bridge->has_helper ? bridge->helper : NULL;
 615     br     = bridge->has_br     ? bridge->br     : DEFAULT_BRIDGE_INTERFACE;
 616
 617     fd = net_bridge_run_helper(helper, br, errp);
 618     if (fd == -1) {
 619         return -1;
 620     }
 621
 622     qemu_set_nonblock(fd);
 623     vnet_hdr = tap_probe_vnet_hdr(fd, errp);
 624     if (vnet_hdr < 0) {
 625         close(fd);
 626         return -1;
 627     }
 628     s = net_tap_fd_init(peer, "bridge", name, fd, vnet_hdr);
 629
 630     snprintf(s->nc.info_str, sizeof(s->nc.info_str), "helper=%s,br=%s", helper,
 631              br);
 632
 633     return 0;
 634 }
 635
 636 static int net_tap_init(const NetdevTapOptions *tap, int *vnet_hdr,
 637                         const char *setup_script, char *ifname,
 638                         size_t ifname_sz, int mq_required, Error **errp)
 639 {
 640     Error *err = NULL;
 641     int fd, vnet_hdr_required;
 642
 643     if (tap->has_vnet_hdr) {
 644         *vnet_hdr = tap->vnet_hdr;
 645         vnet_hdr_required = *vnet_hdr;
 646     } else {
 647         *vnet_hdr = 1;
 648         vnet_hdr_required = 0;
 649     }
 650
 651     TFR(fd = tap_open(ifname, ifname_sz, vnet_hdr, vnet_hdr_required,
 652                       mq_required, errp));
 653     if (fd < 0) {
 654         return -1;
 655     }
 656
 657     if (setup_script &&
 658         setup_script[0] != '\0' &&
 659         strcmp(setup_script, "no") != 0) {
 660         launch_script(setup_script, ifname, fd, &err);
 661         if (err) {
 662             error_propagate(errp, err);
 663             close(fd);
 664             return -1;
 665         }
 666     }
 667
 668     return fd;
 669 }
 670
 671 #define MAX_TAP_QUEUES 1024
 672
 673 static void net_init_tap_one(const NetdevTapOptions *tap, NetClientState *peer,
 674                              const char *model, const char *name,
 675                              const char *ifname, const char *script,
 676                              const char *downscript, const char *vhostfdname,
 677                              int vnet_hdr, int fd, Error **errp)
 678 {
 679     Error *err = NULL;
 680     TAPState *s = net_tap_fd_init(peer, model, name, fd, vnet_hdr);
 681     int vhostfd;
 682
 683     tap_set_sndbuf(s->fd, tap, &err);
 684     if (err) {
 685         error_propagate(errp, err);
 686         return;
 687     }
 688
 689     if (tap->has_fd || tap->has_fds) {
 690         snprintf(s->nc.info_str, sizeof(s->nc.info_str), "fd=%d", fd);
 691     } else if (tap->has_helper) {
 692         snprintf(s->nc.info_str, sizeof(s->nc.info_str), "helper=%s",
 693                  tap->helper);
 694     } else {
 695         snprintf(s->nc.info_str, sizeof(s->nc.info_str),
 696                  "ifname=%s,script=%s,downscript=%s", ifname, script,
 697                  downscript);
 698
 699         if (strcmp(downscript, "no") != 0) {
 700             snprintf(s->down_script, sizeof(s->down_script), "%s", downscript);
 701             snprintf(s->down_script_arg, sizeof(s->down_script_arg),
 702                      "%s", ifname);
 703         }
 704     }
 705
 706     if (tap->has_vhost ? tap->vhost :
 707         vhostfdname || (tap->has_vhostforce && tap->vhostforce)) {
 708         VhostNetOptions options;
 709
 710         options.backend_type = VHOST_BACKEND_TYPE_KERNEL;
 711         options.net_backend = &s->nc;
 712         if (tap->has_poll_us) {
 713             options.busyloop_timeout = tap->poll_us;
 714         } else {
 715             options.busyloop_timeout = 0;
 716         }
 717
 718         if (vhostfdname) {
 719             int ret;
 720
 721             vhostfd = monitor_fd_param(monitor_cur(), vhostfdname, &err);
 722             if (vhostfd == -1) {
 723                 if (tap->has_vhostforce && tap->vhostforce) {
 724                     error_propagate(errp, err);
 725                 } else {
 726                     warn_report_err(err);
 727                 }
 728                 return;
 729             }
 730             ret = qemu_try_set_nonblock(vhostfd);
 731             if (ret < 0) {
 732                 error_setg_errno(errp, -ret, "%s: Can't use file descriptor %d",
 733                                  name, fd);
 734                 return;
 735             }
 736         } else {
 737             vhostfd = open("/dev/vhost-net", O_RDWR);
 738             if (vhostfd < 0) {
 739                 if (tap->has_vhostforce && tap->vhostforce) {
 740                     error_setg_errno(errp, errno,
 741                                      "tap: open vhost char device failed");
 742                 } else {
 743                     warn_report("tap: open vhost char device failed: %s",
 744                                 strerror(errno));
 745                 }
 746                 return;
 747             }
 748             qemu_set_nonblock(vhostfd);
 749         }
 750         options.opaque = (void *)(uintptr_t)vhostfd;
 751         options.nvqs = 2;
 752
 753         s->vhost_net = vhost_net_init(&options);
 754         if (!s->vhost_net) {
 755             if (tap->has_vhostforce && tap->vhostforce) {
 756                 error_setg(errp, VHOST_NET_INIT_FAILED);
 757             } else {
 758                 warn_report(VHOST_NET_INIT_FAILED);
 759             }
 760             return;
 761         }
 762     } else if (vhostfdname) {
 763         error_setg(errp, "vhostfd(s)= is not valid without vhost");
 764     }
 765 }
 766
 767 static int get_fds(char *str, char *fds[], int max)
 768 {
 769     char *ptr = str, *this;
 770     size_t len = strlen(str);
 771     int i = 0;
 772
 773     while (i < max && ptr < str + len) {
 774         this = strchr(ptr, ':');
 775
 776         if (this == NULL) {
 777             fds[i] = g_strdup(ptr);
 778         } else {
 779             fds[i] = g_strndup(ptr, this - ptr);
 780         }
 781
 782         i++;
 783         if (this == NULL) {
 784             break;
 785         } else {
 786             ptr = this + 1;
 787         }
 788     }
 789
 790     return i;
 791 }
 792
 793 int net_init_tap(const Netdev *netdev, const char *name,
 794                  NetClientState *peer, Error **errp)
 795 {
 796     const NetdevTapOptions *tap;
 797     int fd, vnet_hdr = 0, i = 0, queues;
 798     /* for the no-fd, no-helper case */
 799     const char *script;
 800     const char *downscript;
 801     Error *err = NULL;
 802     const char *vhostfdname;
 803     char ifname[128];
 804     int ret = 0;
 805
 806     assert(netdev->type == NET_CLIENT_DRIVER_TAP);
 807     tap = &netdev->u.tap;
 808     queues = tap->has_queues ? tap->queues : 1;
 809     vhostfdname = tap->has_vhostfd ? tap->vhostfd : NULL;
 810     script = tap->has_script ? tap->script : NULL;
 811     downscript = tap->has_downscript ? tap->downscript : NULL;
 812
 813     /* QEMU hubs do not support multiqueue tap, in this case peer is set.
 814      * For -netdev, peer is always NULL. */
 815     if (peer && (tap->has_queues || tap->has_fds || tap->has_vhostfds)) {
 816         error_setg(errp, "Multiqueue tap cannot be used with hubs");
 817         return -1;
 818     }
 819
 820     if (tap->has_fd) {
 821         if (tap->has_ifname || tap->has_script || tap->has_downscript ||
 822             tap->has_vnet_hdr || tap->has_helper || tap->has_queues ||
 823             tap->has_fds || tap->has_vhostfds) {
 824             error_setg(errp, "ifname=, script=, downscript=, vnet_hdr=, "
 825                        "helper=, queues=, fds=, and vhostfds= "
 826                        "are invalid with fd=");
 827             return -1;
 828         }
 829
 830         fd = monitor_fd_param(monitor_cur(), tap->fd, errp);
 831         if (fd == -1) {
 832             return -1;
 833         }
 834
 835         ret = qemu_try_set_nonblock(fd);
 836         if (ret < 0) {
 837             error_setg_errno(errp, -ret, "%s: Can't use file descriptor %d",
 838                              name, fd);
 839             close(fd);
 840             return -1;
 841         }
 842
 843         vnet_hdr = tap_probe_vnet_hdr(fd, errp);
 844         if (vnet_hdr < 0) {
 845             close(fd);
 846             return -1;
 847         }
 848
 849         net_init_tap_one(tap, peer, "tap", name, NULL,
 850                          script, downscript,
 851                          vhostfdname, vnet_hdr, fd, &err);
 852         if (err) {
 853             error_propagate(errp, err);
 854             close(fd);
 855             return -1;
 856         }
 857     } else if (tap->has_fds) {
 858         char **fds;
 859         char **vhost_fds;
 860         int nfds = 0, nvhosts = 0;
 861
 862         if (tap->has_ifname || tap->has_script || tap->has_downscript ||
 863             tap->has_vnet_hdr || tap->has_helper || tap->has_queues ||
 864             tap->has_vhostfd) {
 865             error_setg(errp, "ifname=, script=, downscript=, vnet_hdr=, "
 866                        "helper=, queues=, and vhostfd= "
 867                        "are invalid with fds=");
 868             return -1;
 869         }
 870
 871         fds = g_new0(char *, MAX_TAP_QUEUES);
 872         vhost_fds = g_new0(char *, MAX_TAP_QUEUES);
 873
 874         nfds = get_fds(tap->fds, fds, MAX_TAP_QUEUES);
 875         if (tap->has_vhostfds) {
 876             nvhosts = get_fds(tap->vhostfds, vhost_fds, MAX_TAP_QUEUES);
 877             if (nfds != nvhosts) {
 878                 error_setg(errp, "The number of fds passed does not match "
 879                            "the number of vhostfds passed");
 880                 ret = -1;
 881                 goto free_fail;
 882             }
 883         }
 884
 885         for (i = 0; i < nfds; i++) {
 886             fd = monitor_fd_param(monitor_cur(), fds[i], errp);
 887             if (fd == -1) {
 888                 ret = -1;
 889                 goto free_fail;
 890             }
 891
 892             ret = qemu_try_set_nonblock(fd);
 893             if (ret < 0) {
 894                 error_setg_errno(errp, -ret, "%s: Can't use file descriptor %d",
 895                                  name, fd);
 896                 goto free_fail;
 897             }
 898
 899             if (i == 0) {
 900                 vnet_hdr = tap_probe_vnet_hdr(fd, errp);
 901                 if (vnet_hdr < 0) {
 902                     ret = -1;
 903                     goto free_fail;
 904                 }
 905             } else if (vnet_hdr != tap_probe_vnet_hdr(fd, NULL)) {
 906                 error_setg(errp,
 907                            "vnet_hdr not consistent across given tap fds");
 908                 ret = -1;
 909                 goto free_fail;
 910             }
 911
 912             net_init_tap_one(tap, peer, "tap", name, ifname,
 913                              script, downscript,
 914                              tap->has_vhostfds ? vhost_fds[i] : NULL,
 915                              vnet_hdr, fd, &err);
 916             if (err) {
 917                 error_propagate(errp, err);
 918                 ret = -1;
 919                 goto free_fail;
 920             }
 921         }
 922
 923 free_fail:
 924         for (i = 0; i < nvhosts; i++) {
 925             g_free(vhost_fds[i]);
 926         }
 927         for (i = 0; i < nfds; i++) {
 928             g_free(fds[i]);
 929         }
 930         g_free(fds);
 931         g_free(vhost_fds);
 932         return ret;
 933     } else if (tap->has_helper) {
 934         if (tap->has_ifname || tap->has_script || tap->has_downscript ||
 935             tap->has_vnet_hdr || tap->has_queues || tap->has_vhostfds) {
 936             error_setg(errp, "ifname=, script=, downscript=, vnet_hdr=, "
 937                        "queues=, and vhostfds= are invalid with helper=");
 938             return -1;
 939         }
 940
 941         fd = net_bridge_run_helper(tap->helper,
 942                                    tap->has_br ?
 943                                    tap->br : DEFAULT_BRIDGE_INTERFACE,
 944                                    errp);
 945         if (fd == -1) {
 946             return -1;
 947         }
 948
 949         qemu_set_nonblock(fd);
 950         vnet_hdr = tap_probe_vnet_hdr(fd, errp);
 951         if (vnet_hdr < 0) {
 952             close(fd);
 953             return -1;
 954         }
 955
 956         net_init_tap_one(tap, peer, "bridge", name, ifname,
 957                          script, downscript, vhostfdname,
 958                          vnet_hdr, fd, &err);
 959         if (err) {
 960             error_propagate(errp, err);
 961             close(fd);
 962             return -1;
 963         }
 964     } else {
 965         g_autofree char *default_script = NULL;
 966         g_autofree char *default_downscript = NULL;
 967         if (tap->has_vhostfds) {
 968             error_setg(errp, "vhostfds= is invalid if fds= wasn't specified");
 969             return -1;
 970         }
 971
 972         if (!script) {
 973             script = default_script = get_relocated_path(DEFAULT_NETWORK_SCRIPT);
 974         }
 975         if (!downscript) {
 976             downscript = default_downscript =
 977                                  get_relocated_path(DEFAULT_NETWORK_DOWN_SCRIPT);
 978         }
 979
 980         if (tap->has_ifname) {
 981             pstrcpy(ifname, sizeof ifname, tap->ifname);
 982         } else {
 983             ifname[0] = '\0';
 984         }
 985
 986         for (i = 0; i < queues; i++) {
 987             fd = net_tap_init(tap, &vnet_hdr, i >= 1 ? "no" : script,
 988                               ifname, sizeof ifname, queues > 1, errp);
 989             if (fd == -1) {
 990                 return -1;
 991             }
 992
 993             if (queues > 1 && i == 0 && !tap->has_ifname) {
 994                 if (tap_fd_get_ifname(fd, ifname)) {
 995                     error_setg(errp, "Fail to get ifname");
 996                     close(fd);
 997                     return -1;
 998                 }
 999             }
1000
1001             net_init_tap_one(tap, peer, "tap", name, ifname,
1002                              i >= 1 ? "no" : script,
1003                              i >= 1 ? "no" : downscript,
1004                              vhostfdname, vnet_hdr, fd, &err);
1005             if (err) {
1006                 error_propagate(errp, err);
1007                 close(fd);
1008                 return -1;
1009             }
1010         }
1011     }
1012
1013     return 0;
1014 }
1015
1016 VHostNetState *tap_get_vhost_net(NetClientState *nc)
1017 {
1018     TAPState *s = DO_UPCAST(TAPState, nc, nc);
1019     assert(nc->info->type == NET_CLIENT_DRIVER_TAP);
1020     return s->vhost_net;
1021 }
1022
1023 int tap_enable(NetClientState *nc)
1024 {
1025     TAPState *s = DO_UPCAST(TAPState, nc, nc);
1026     int ret;
1027
1028     if (s->enabled) {
1029         return 0;
1030     } else {
1031         ret = tap_fd_enable(s->fd);
1032         if (ret == 0) {
1033             s->enabled = true;
1034             tap_update_fd_handler(s);
1035         }
1036         return ret;
1037     }
1038 }
1039
1040 int tap_disable(NetClientState *nc)
1041 {
1042     TAPState *s = DO_UPCAST(TAPState, nc, nc);
1043     int ret;
1044
1045     if (s->enabled == 0) {
1046         return 0;
1047     } else {
1048         ret = tap_fd_disable(s->fd);
1049         if (ret == 0) {
1050             qemu_purge_queued_packets(nc);
1051             s->enabled = false;
1052             tap_update_fd_handler(s);
1053         }
1054         return ret;
1055     }
1056 }