xref: /openbmc/qemu/net/tap.c (revision 9edc6313da34699ebd2bae4573ea22339b26450a)
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-common.h"
42  #include "qemu/cutils.h"
43  #include "qemu/error-report.h"
44  #include "qemu/main-loop.h"
45  #include "qemu/sockets.h"
46  
47  #include "net/tap.h"
48  
49  #include "net/vhost_net.h"
50  
51  typedef struct TAPState {
52      NetClientState nc;
53      int fd;
54      char down_script[1024];
55      char down_script_arg[128];
56      uint8_t buf[NET_BUFSIZE];
57      bool read_poll;
58      bool write_poll;
59      bool using_vnet_hdr;
60      bool has_ufo;
61      bool enabled;
62      VHostNetState *vhost_net;
63      unsigned host_vnet_hdr_len;
64      Notifier exit;
65  } TAPState;
66  
67  static void launch_script(const char *setup_script, const char *ifname,
68                            int fd, Error **errp);
69  
70  static void tap_send(void *opaque);
71  static void tap_writable(void *opaque);
72  
73  static void tap_update_fd_handler(TAPState *s)
74  {
75      qemu_set_fd_handler(s->fd,
76                          s->read_poll && s->enabled ? tap_send : NULL,
77                          s->write_poll && s->enabled ? tap_writable : NULL,
78                          s);
79  }
80  
81  static void tap_read_poll(TAPState *s, bool enable)
82  {
83      s->read_poll = enable;
84      tap_update_fd_handler(s);
85  }
86  
87  static void tap_write_poll(TAPState *s, bool enable)
88  {
89      s->write_poll = enable;
90      tap_update_fd_handler(s);
91  }
92  
93  static void tap_writable(void *opaque)
94  {
95      TAPState *s = opaque;
96  
97      tap_write_poll(s, false);
98  
99      qemu_flush_queued_packets(&s->nc);
100  }
101  
102  static ssize_t tap_write_packet(TAPState *s, const struct iovec *iov, int iovcnt)
103  {
104      ssize_t len;
105  
106      do {
107          len = writev(s->fd, iov, iovcnt);
108      } while (len == -1 && errno == EINTR);
109  
110      if (len == -1 && errno == EAGAIN) {
111          tap_write_poll(s, true);
112          return 0;
113      }
114  
115      return len;
116  }
117  
118  static ssize_t tap_receive_iov(NetClientState *nc, const struct iovec *iov,
119                                 int iovcnt)
120  {
121      TAPState *s = DO_UPCAST(TAPState, nc, nc);
122      const struct iovec *iovp = iov;
123      struct iovec iov_copy[iovcnt + 1];
124      struct virtio_net_hdr_mrg_rxbuf hdr = { };
125  
126      if (s->host_vnet_hdr_len && !s->using_vnet_hdr) {
127          iov_copy[0].iov_base = &hdr;
128          iov_copy[0].iov_len =  s->host_vnet_hdr_len;
129          memcpy(&iov_copy[1], iov, iovcnt * sizeof(*iov));
130          iovp = iov_copy;
131          iovcnt++;
132      }
133  
134      return tap_write_packet(s, iovp, iovcnt);
135  }
136  
137  static ssize_t tap_receive_raw(NetClientState *nc, const uint8_t *buf, size_t size)
138  {
139      TAPState *s = DO_UPCAST(TAPState, nc, nc);
140      struct iovec iov[2];
141      int iovcnt = 0;
142      struct virtio_net_hdr_mrg_rxbuf hdr = { };
143  
144      if (s->host_vnet_hdr_len) {
145          iov[iovcnt].iov_base = &hdr;
146          iov[iovcnt].iov_len  = s->host_vnet_hdr_len;
147          iovcnt++;
148      }
149  
150      iov[iovcnt].iov_base = (char *)buf;
151      iov[iovcnt].iov_len  = size;
152      iovcnt++;
153  
154      return tap_write_packet(s, iov, iovcnt);
155  }
156  
157  static ssize_t tap_receive(NetClientState *nc, const uint8_t *buf, size_t size)
158  {
159      TAPState *s = DO_UPCAST(TAPState, nc, nc);
160      struct iovec iov[1];
161  
162      if (s->host_vnet_hdr_len && !s->using_vnet_hdr) {
163          return tap_receive_raw(nc, buf, size);
164      }
165  
166      iov[0].iov_base = (char *)buf;
167      iov[0].iov_len  = size;
168  
169      return tap_write_packet(s, iov, 1);
170  }
171  
172  #ifndef __sun__
173  ssize_t tap_read_packet(int tapfd, uint8_t *buf, int maxlen)
174  {
175      return read(tapfd, buf, maxlen);
176  }
177  #endif
178  
179  static void tap_send_completed(NetClientState *nc, ssize_t len)
180  {
181      TAPState *s = DO_UPCAST(TAPState, nc, nc);
182      tap_read_poll(s, true);
183  }
184  
185  static void tap_send(void *opaque)
186  {
187      TAPState *s = opaque;
188      int size;
189      int packets = 0;
190  
191      while (true) {
192          uint8_t *buf = s->buf;
193          uint8_t min_pkt[ETH_ZLEN];
194          size_t min_pktsz = sizeof(min_pkt);
195  
196          size = tap_read_packet(s->fd, s->buf, sizeof(s->buf));
197          if (size <= 0) {
198              break;
199          }
200  
201          if (s->host_vnet_hdr_len && !s->using_vnet_hdr) {
202              buf  += s->host_vnet_hdr_len;
203              size -= s->host_vnet_hdr_len;
204          }
205  
206          if (net_peer_needs_padding(&s->nc)) {
207              if (eth_pad_short_frame(min_pkt, &min_pktsz, buf, size)) {
208                  buf = min_pkt;
209                  size = min_pktsz;
210              }
211          }
212  
213          size = qemu_send_packet_async(&s->nc, buf, size, tap_send_completed);
214          if (size == 0) {
215              tap_read_poll(s, false);
216              break;
217          } else if (size < 0) {
218              break;
219          }
220  
221          /*
222           * When the host keeps receiving more packets while tap_send() is
223           * running we can hog the QEMU global mutex.  Limit the number of
224           * packets that are processed per tap_send() callback to prevent
225           * stalling the guest.
226           */
227          packets++;
228          if (packets >= 50) {
229              break;
230          }
231      }
232  }
233  
234  static bool tap_has_ufo(NetClientState *nc)
235  {
236      TAPState *s = DO_UPCAST(TAPState, nc, nc);
237  
238      assert(nc->info->type == NET_CLIENT_DRIVER_TAP);
239  
240      return s->has_ufo;
241  }
242  
243  static bool tap_has_vnet_hdr(NetClientState *nc)
244  {
245      TAPState *s = DO_UPCAST(TAPState, nc, nc);
246  
247      assert(nc->info->type == NET_CLIENT_DRIVER_TAP);
248  
249      return !!s->host_vnet_hdr_len;
250  }
251  
252  static bool tap_has_vnet_hdr_len(NetClientState *nc, int len)
253  {
254      TAPState *s = DO_UPCAST(TAPState, nc, nc);
255  
256      assert(nc->info->type == NET_CLIENT_DRIVER_TAP);
257  
258      return !!tap_probe_vnet_hdr_len(s->fd, len);
259  }
260  
261  static void tap_set_vnet_hdr_len(NetClientState *nc, int len)
262  {
263      TAPState *s = DO_UPCAST(TAPState, nc, nc);
264  
265      assert(nc->info->type == NET_CLIENT_DRIVER_TAP);
266      assert(len == sizeof(struct virtio_net_hdr_mrg_rxbuf) ||
267             len == sizeof(struct virtio_net_hdr) ||
268             len == sizeof(struct virtio_net_hdr_v1_hash));
269  
270      tap_fd_set_vnet_hdr_len(s->fd, len);
271      s->host_vnet_hdr_len = len;
272  }
273  
274  static void tap_using_vnet_hdr(NetClientState *nc, bool using_vnet_hdr)
275  {
276      TAPState *s = DO_UPCAST(TAPState, nc, nc);
277  
278      assert(nc->info->type == NET_CLIENT_DRIVER_TAP);
279      assert(!!s->host_vnet_hdr_len == using_vnet_hdr);
280  
281      s->using_vnet_hdr = using_vnet_hdr;
282  }
283  
284  static int tap_set_vnet_le(NetClientState *nc, bool is_le)
285  {
286      TAPState *s = DO_UPCAST(TAPState, nc, nc);
287  
288      return tap_fd_set_vnet_le(s->fd, is_le);
289  }
290  
291  static int tap_set_vnet_be(NetClientState *nc, bool is_be)
292  {
293      TAPState *s = DO_UPCAST(TAPState, nc, nc);
294  
295      return tap_fd_set_vnet_be(s->fd, is_be);
296  }
297  
298  static void tap_set_offload(NetClientState *nc, int csum, int tso4,
299                       int tso6, int ecn, int ufo)
300  {
301      TAPState *s = DO_UPCAST(TAPState, nc, nc);
302      if (s->fd < 0) {
303          return;
304      }
305  
306      tap_fd_set_offload(s->fd, csum, tso4, tso6, ecn, ufo);
307  }
308  
309  static void tap_exit_notify(Notifier *notifier, void *data)
310  {
311      TAPState *s = container_of(notifier, TAPState, exit);
312      Error *err = NULL;
313  
314      if (s->down_script[0]) {
315          launch_script(s->down_script, s->down_script_arg, s->fd, &err);
316          if (err) {
317              error_report_err(err);
318          }
319      }
320  }
321  
322  static void tap_cleanup(NetClientState *nc)
323  {
324      TAPState *s = DO_UPCAST(TAPState, nc, nc);
325  
326      if (s->vhost_net) {
327          vhost_net_cleanup(s->vhost_net);
328          g_free(s->vhost_net);
329          s->vhost_net = NULL;
330      }
331  
332      qemu_purge_queued_packets(nc);
333  
334      tap_exit_notify(&s->exit, NULL);
335      qemu_remove_exit_notifier(&s->exit);
336  
337      tap_read_poll(s, false);
338      tap_write_poll(s, false);
339      close(s->fd);
340      s->fd = -1;
341  }
342  
343  static void tap_poll(NetClientState *nc, bool enable)
344  {
345      TAPState *s = DO_UPCAST(TAPState, nc, nc);
346      tap_read_poll(s, enable);
347      tap_write_poll(s, enable);
348  }
349  
350  static bool tap_set_steering_ebpf(NetClientState *nc, int prog_fd)
351  {
352      TAPState *s = DO_UPCAST(TAPState, nc, nc);
353      assert(nc->info->type == NET_CLIENT_DRIVER_TAP);
354  
355      return tap_fd_set_steering_ebpf(s->fd, prog_fd) == 0;
356  }
357  
358  int tap_get_fd(NetClientState *nc)
359  {
360      TAPState *s = DO_UPCAST(TAPState, nc, nc);
361      assert(nc->info->type == NET_CLIENT_DRIVER_TAP);
362      return s->fd;
363  }
364  
365  /* fd support */
366  
367  static NetClientInfo net_tap_info = {
368      .type = NET_CLIENT_DRIVER_TAP,
369      .size = sizeof(TAPState),
370      .receive = tap_receive,
371      .receive_raw = tap_receive_raw,
372      .receive_iov = tap_receive_iov,
373      .poll = tap_poll,
374      .cleanup = tap_cleanup,
375      .has_ufo = tap_has_ufo,
376      .has_vnet_hdr = tap_has_vnet_hdr,
377      .has_vnet_hdr_len = tap_has_vnet_hdr_len,
378      .using_vnet_hdr = tap_using_vnet_hdr,
379      .set_offload = tap_set_offload,
380      .set_vnet_hdr_len = tap_set_vnet_hdr_len,
381      .set_vnet_le = tap_set_vnet_le,
382      .set_vnet_be = tap_set_vnet_be,
383      .set_steering_ebpf = tap_set_steering_ebpf,
384  };
385  
386  static TAPState *net_tap_fd_init(NetClientState *peer,
387                                   const char *model,
388                                   const char *name,
389                                   int fd,
390                                   int vnet_hdr)
391  {
392      NetClientState *nc;
393      TAPState *s;
394  
395      nc = qemu_new_net_client(&net_tap_info, peer, model, name);
396  
397      s = DO_UPCAST(TAPState, nc, nc);
398  
399      s->fd = fd;
400      s->host_vnet_hdr_len = vnet_hdr ? sizeof(struct virtio_net_hdr) : 0;
401      s->using_vnet_hdr = false;
402      s->has_ufo = tap_probe_has_ufo(s->fd);
403      s->enabled = true;
404      tap_set_offload(&s->nc, 0, 0, 0, 0, 0);
405      /*
406       * Make sure host header length is set correctly in tap:
407       * it might have been modified by another instance of qemu.
408       */
409      if (tap_probe_vnet_hdr_len(s->fd, s->host_vnet_hdr_len)) {
410          tap_fd_set_vnet_hdr_len(s->fd, s->host_vnet_hdr_len);
411      }
412      tap_read_poll(s, true);
413      s->vhost_net = NULL;
414  
415      s->exit.notify = tap_exit_notify;
416      qemu_add_exit_notifier(&s->exit);
417  
418      return s;
419  }
420  
421  static void launch_script(const char *setup_script, const char *ifname,
422                            int fd, Error **errp)
423  {
424      int pid, status;
425      char *args[3];
426      char **parg;
427  
428      /* try to launch network script */
429      pid = fork();
430      if (pid < 0) {
431          error_setg_errno(errp, errno, "could not launch network script %s",
432                           setup_script);
433          return;
434      }
435      if (pid == 0) {
436          int open_max = sysconf(_SC_OPEN_MAX), i;
437  
438          for (i = 3; i < open_max; i++) {
439              if (i != fd) {
440                  close(i);
441              }
442          }
443          parg = args;
444          *parg++ = (char *)setup_script;
445          *parg++ = (char *)ifname;
446          *parg = NULL;
447          execv(setup_script, args);
448          _exit(1);
449      } else {
450          while (waitpid(pid, &status, 0) != pid) {
451              /* loop */
452          }
453  
454          if (WIFEXITED(status) && WEXITSTATUS(status) == 0) {
455              return;
456          }
457          error_setg(errp, "network script %s failed with status %d",
458                     setup_script, status);
459      }
460  }
461  
462  static int recv_fd(int c)
463  {
464      int fd;
465      uint8_t msgbuf[CMSG_SPACE(sizeof(fd))];
466      struct msghdr msg = {
467          .msg_control = msgbuf,
468          .msg_controllen = sizeof(msgbuf),
469      };
470      struct cmsghdr *cmsg;
471      struct iovec iov;
472      uint8_t req[1];
473      ssize_t len;
474  
475      cmsg = CMSG_FIRSTHDR(&msg);
476      cmsg->cmsg_level = SOL_SOCKET;
477      cmsg->cmsg_type = SCM_RIGHTS;
478      cmsg->cmsg_len = CMSG_LEN(sizeof(fd));
479      msg.msg_controllen = cmsg->cmsg_len;
480  
481      iov.iov_base = req;
482      iov.iov_len = sizeof(req);
483  
484      msg.msg_iov = &iov;
485      msg.msg_iovlen = 1;
486  
487      len = recvmsg(c, &msg, 0);
488      if (len > 0) {
489          memcpy(&fd, CMSG_DATA(cmsg), sizeof(fd));
490          return fd;
491      }
492  
493      return len;
494  }
495  
496  static int net_bridge_run_helper(const char *helper, const char *bridge,
497                                   Error **errp)
498  {
499      sigset_t oldmask, mask;
500      g_autofree char *default_helper = NULL;
501      int pid, status;
502      char *args[5];
503      char **parg;
504      int sv[2];
505  
506      sigemptyset(&mask);
507      sigaddset(&mask, SIGCHLD);
508      sigprocmask(SIG_BLOCK, &mask, &oldmask);
509  
510      if (!helper) {
511          helper = default_helper = get_relocated_path(DEFAULT_BRIDGE_HELPER);
512      }
513  
514      if (socketpair(PF_UNIX, SOCK_STREAM, 0, sv) == -1) {
515          error_setg_errno(errp, errno, "socketpair() failed");
516          return -1;
517      }
518  
519      /* try to launch bridge helper */
520      pid = fork();
521      if (pid < 0) {
522          error_setg_errno(errp, errno, "Can't fork bridge helper");
523          return -1;
524      }
525      if (pid == 0) {
526          int open_max = sysconf(_SC_OPEN_MAX), i;
527          char *fd_buf = NULL;
528          char *br_buf = NULL;
529          char *helper_cmd = NULL;
530  
531          for (i = 3; i < open_max; i++) {
532              if (i != sv[1]) {
533                  close(i);
534              }
535          }
536  
537          fd_buf = g_strdup_printf("%s%d", "--fd=", sv[1]);
538  
539          if (strrchr(helper, ' ') || strrchr(helper, '\t')) {
540              /* assume helper is a command */
541  
542              if (strstr(helper, "--br=") == NULL) {
543                  br_buf = g_strdup_printf("%s%s", "--br=", bridge);
544              }
545  
546              helper_cmd = g_strdup_printf("%s %s %s %s", helper,
547                              "--use-vnet", fd_buf, br_buf ? br_buf : "");
548  
549              parg = args;
550              *parg++ = (char *)"sh";
551              *parg++ = (char *)"-c";
552              *parg++ = helper_cmd;
553              *parg++ = NULL;
554  
555              execv("/bin/sh", args);
556              g_free(helper_cmd);
557          } else {
558              /* assume helper is just the executable path name */
559  
560              br_buf = g_strdup_printf("%s%s", "--br=", bridge);
561  
562              parg = args;
563              *parg++ = (char *)helper;
564              *parg++ = (char *)"--use-vnet";
565              *parg++ = fd_buf;
566              *parg++ = br_buf;
567              *parg++ = NULL;
568  
569              execv(helper, args);
570          }
571          g_free(fd_buf);
572          g_free(br_buf);
573          _exit(1);
574  
575      } else {
576          int fd;
577          int saved_errno;
578  
579          close(sv[1]);
580  
581          do {
582              fd = recv_fd(sv[0]);
583          } while (fd == -1 && errno == EINTR);
584          saved_errno = errno;
585  
586          close(sv[0]);
587  
588          while (waitpid(pid, &status, 0) != pid) {
589              /* loop */
590          }
591          sigprocmask(SIG_SETMASK, &oldmask, NULL);
592          if (fd < 0) {
593              error_setg_errno(errp, saved_errno,
594                               "failed to recv file descriptor");
595              return -1;
596          }
597          if (!WIFEXITED(status) || WEXITSTATUS(status) != 0) {
598              error_setg(errp, "bridge helper failed");
599              return -1;
600          }
601          return fd;
602      }
603  }
604  
605  int net_init_bridge(const Netdev *netdev, const char *name,
606                      NetClientState *peer, Error **errp)
607  {
608      const NetdevBridgeOptions *bridge;
609      const char *helper, *br;
610      TAPState *s;
611      int fd, vnet_hdr;
612  
613      assert(netdev->type == NET_CLIENT_DRIVER_BRIDGE);
614      bridge = &netdev->u.bridge;
615      helper = bridge->has_helper ? bridge->helper : NULL;
616      br     = bridge->has_br     ? bridge->br     : DEFAULT_BRIDGE_INTERFACE;
617  
618      fd = net_bridge_run_helper(helper, br, errp);
619      if (fd == -1) {
620          return -1;
621      }
622  
623      qemu_set_nonblock(fd);
624      vnet_hdr = tap_probe_vnet_hdr(fd, errp);
625      if (vnet_hdr < 0) {
626          close(fd);
627          return -1;
628      }
629      s = net_tap_fd_init(peer, "bridge", name, fd, vnet_hdr);
630  
631      snprintf(s->nc.info_str, sizeof(s->nc.info_str), "helper=%s,br=%s", helper,
632               br);
633  
634      return 0;
635  }
636  
637  static int net_tap_init(const NetdevTapOptions *tap, int *vnet_hdr,
638                          const char *setup_script, char *ifname,
639                          size_t ifname_sz, int mq_required, Error **errp)
640  {
641      Error *err = NULL;
642      int fd, vnet_hdr_required;
643  
644      if (tap->has_vnet_hdr) {
645          *vnet_hdr = tap->vnet_hdr;
646          vnet_hdr_required = *vnet_hdr;
647      } else {
648          *vnet_hdr = 1;
649          vnet_hdr_required = 0;
650      }
651  
652      TFR(fd = tap_open(ifname, ifname_sz, vnet_hdr, vnet_hdr_required,
653                        mq_required, errp));
654      if (fd < 0) {
655          return -1;
656      }
657  
658      if (setup_script &&
659          setup_script[0] != '\0' &&
660          strcmp(setup_script, "no") != 0) {
661          launch_script(setup_script, ifname, fd, &err);
662          if (err) {
663              error_propagate(errp, err);
664              close(fd);
665              return -1;
666          }
667      }
668  
669      return fd;
670  }
671  
672  #define MAX_TAP_QUEUES 1024
673  
674  static void net_init_tap_one(const NetdevTapOptions *tap, NetClientState *peer,
675                               const char *model, const char *name,
676                               const char *ifname, const char *script,
677                               const char *downscript, const char *vhostfdname,
678                               int vnet_hdr, int fd, Error **errp)
679  {
680      Error *err = NULL;
681      TAPState *s = net_tap_fd_init(peer, model, name, fd, vnet_hdr);
682      int vhostfd;
683  
684      tap_set_sndbuf(s->fd, tap, &err);
685      if (err) {
686          error_propagate(errp, err);
687          return;
688      }
689  
690      if (tap->has_fd || tap->has_fds) {
691          snprintf(s->nc.info_str, sizeof(s->nc.info_str), "fd=%d", fd);
692      } else if (tap->has_helper) {
693          snprintf(s->nc.info_str, sizeof(s->nc.info_str), "helper=%s",
694                   tap->helper);
695      } else {
696          snprintf(s->nc.info_str, sizeof(s->nc.info_str),
697                   "ifname=%s,script=%s,downscript=%s", ifname, script,
698                   downscript);
699  
700          if (strcmp(downscript, "no") != 0) {
701              snprintf(s->down_script, sizeof(s->down_script), "%s", downscript);
702              snprintf(s->down_script_arg, sizeof(s->down_script_arg),
703                       "%s", ifname);
704          }
705      }
706  
707      if (tap->has_vhost ? tap->vhost :
708          vhostfdname || (tap->has_vhostforce && tap->vhostforce)) {
709          VhostNetOptions options;
710  
711          options.backend_type = VHOST_BACKEND_TYPE_KERNEL;
712          options.net_backend = &s->nc;
713          if (tap->has_poll_us) {
714              options.busyloop_timeout = tap->poll_us;
715          } else {
716              options.busyloop_timeout = 0;
717          }
718  
719          if (vhostfdname) {
720              int ret;
721  
722              vhostfd = monitor_fd_param(monitor_cur(), vhostfdname, &err);
723              if (vhostfd == -1) {
724                  if (tap->has_vhostforce && tap->vhostforce) {
725                      error_propagate(errp, err);
726                  } else {
727                      warn_report_err(err);
728                  }
729                  return;
730              }
731              ret = qemu_try_set_nonblock(vhostfd);
732              if (ret < 0) {
733                  error_setg_errno(errp, -ret, "%s: Can't use file descriptor %d",
734                                   name, fd);
735                  return;
736              }
737          } else {
738              vhostfd = open("/dev/vhost-net", O_RDWR);
739              if (vhostfd < 0) {
740                  if (tap->has_vhostforce && tap->vhostforce) {
741                      error_setg_errno(errp, errno,
742                                       "tap: open vhost char device failed");
743                  } else {
744                      warn_report("tap: open vhost char device failed: %s",
745                                  strerror(errno));
746                  }
747                  return;
748              }
749              qemu_set_nonblock(vhostfd);
750          }
751          options.opaque = (void *)(uintptr_t)vhostfd;
752          options.nvqs = 2;
753  
754          s->vhost_net = vhost_net_init(&options);
755          if (!s->vhost_net) {
756              if (tap->has_vhostforce && tap->vhostforce) {
757                  error_setg(errp, VHOST_NET_INIT_FAILED);
758              } else {
759                  warn_report(VHOST_NET_INIT_FAILED);
760              }
761              return;
762          }
763      } else if (vhostfdname) {
764          error_setg(errp, "vhostfd(s)= is not valid without vhost");
765      }
766  }
767  
768  static int get_fds(char *str, char *fds[], int max)
769  {
770      char *ptr = str, *this;
771      size_t len = strlen(str);
772      int i = 0;
773  
774      while (i < max && ptr < str + len) {
775          this = strchr(ptr, ':');
776  
777          if (this == NULL) {
778              fds[i] = g_strdup(ptr);
779          } else {
780              fds[i] = g_strndup(ptr, this - ptr);
781          }
782  
783          i++;
784          if (this == NULL) {
785              break;
786          } else {
787              ptr = this + 1;
788          }
789      }
790  
791      return i;
792  }
793  
794  int net_init_tap(const Netdev *netdev, const char *name,
795                   NetClientState *peer, Error **errp)
796  {
797      const NetdevTapOptions *tap;
798      int fd, vnet_hdr = 0, i = 0, queues;
799      /* for the no-fd, no-helper case */
800      const char *script;
801      const char *downscript;
802      Error *err = NULL;
803      const char *vhostfdname;
804      char ifname[128];
805      int ret = 0;
806  
807      assert(netdev->type == NET_CLIENT_DRIVER_TAP);
808      tap = &netdev->u.tap;
809      queues = tap->has_queues ? tap->queues : 1;
810      vhostfdname = tap->has_vhostfd ? tap->vhostfd : NULL;
811      script = tap->has_script ? tap->script : NULL;
812      downscript = tap->has_downscript ? tap->downscript : NULL;
813  
814      /* QEMU hubs do not support multiqueue tap, in this case peer is set.
815       * For -netdev, peer is always NULL. */
816      if (peer && (tap->has_queues || tap->has_fds || tap->has_vhostfds)) {
817          error_setg(errp, "Multiqueue tap cannot be used with hubs");
818          return -1;
819      }
820  
821      if (tap->has_fd) {
822          if (tap->has_ifname || tap->has_script || tap->has_downscript ||
823              tap->has_vnet_hdr || tap->has_helper || tap->has_queues ||
824              tap->has_fds || tap->has_vhostfds) {
825              error_setg(errp, "ifname=, script=, downscript=, vnet_hdr=, "
826                         "helper=, queues=, fds=, and vhostfds= "
827                         "are invalid with fd=");
828              return -1;
829          }
830  
831          fd = monitor_fd_param(monitor_cur(), tap->fd, errp);
832          if (fd == -1) {
833              return -1;
834          }
835  
836          ret = qemu_try_set_nonblock(fd);
837          if (ret < 0) {
838              error_setg_errno(errp, -ret, "%s: Can't use file descriptor %d",
839                               name, fd);
840              close(fd);
841              return -1;
842          }
843  
844          vnet_hdr = tap_probe_vnet_hdr(fd, errp);
845          if (vnet_hdr < 0) {
846              close(fd);
847              return -1;
848          }
849  
850          net_init_tap_one(tap, peer, "tap", name, NULL,
851                           script, downscript,
852                           vhostfdname, vnet_hdr, fd, &err);
853          if (err) {
854              error_propagate(errp, err);
855              close(fd);
856              return -1;
857          }
858      } else if (tap->has_fds) {
859          char **fds;
860          char **vhost_fds;
861          int nfds = 0, nvhosts = 0;
862  
863          if (tap->has_ifname || tap->has_script || tap->has_downscript ||
864              tap->has_vnet_hdr || tap->has_helper || tap->has_queues ||
865              tap->has_vhostfd) {
866              error_setg(errp, "ifname=, script=, downscript=, vnet_hdr=, "
867                         "helper=, queues=, and vhostfd= "
868                         "are invalid with fds=");
869              return -1;
870          }
871  
872          fds = g_new0(char *, MAX_TAP_QUEUES);
873          vhost_fds = g_new0(char *, MAX_TAP_QUEUES);
874  
875          nfds = get_fds(tap->fds, fds, MAX_TAP_QUEUES);
876          if (tap->has_vhostfds) {
877              nvhosts = get_fds(tap->vhostfds, vhost_fds, MAX_TAP_QUEUES);
878              if (nfds != nvhosts) {
879                  error_setg(errp, "The number of fds passed does not match "
880                             "the number of vhostfds passed");
881                  ret = -1;
882                  goto free_fail;
883              }
884          }
885  
886          for (i = 0; i < nfds; i++) {
887              fd = monitor_fd_param(monitor_cur(), fds[i], errp);
888              if (fd == -1) {
889                  ret = -1;
890                  goto free_fail;
891              }
892  
893              ret = qemu_try_set_nonblock(fd);
894              if (ret < 0) {
895                  error_setg_errno(errp, -ret, "%s: Can't use file descriptor %d",
896                                   name, fd);
897                  goto free_fail;
898              }
899  
900              if (i == 0) {
901                  vnet_hdr = tap_probe_vnet_hdr(fd, errp);
902                  if (vnet_hdr < 0) {
903                      ret = -1;
904                      goto free_fail;
905                  }
906              } else if (vnet_hdr != tap_probe_vnet_hdr(fd, NULL)) {
907                  error_setg(errp,
908                             "vnet_hdr not consistent across given tap fds");
909                  ret = -1;
910                  goto free_fail;
911              }
912  
913              net_init_tap_one(tap, peer, "tap", name, ifname,
914                               script, downscript,
915                               tap->has_vhostfds ? vhost_fds[i] : NULL,
916                               vnet_hdr, fd, &err);
917              if (err) {
918                  error_propagate(errp, err);
919                  ret = -1;
920                  goto free_fail;
921              }
922          }
923  
924  free_fail:
925          for (i = 0; i < nvhosts; i++) {
926              g_free(vhost_fds[i]);
927          }
928          for (i = 0; i < nfds; i++) {
929              g_free(fds[i]);
930          }
931          g_free(fds);
932          g_free(vhost_fds);
933          return ret;
934      } else if (tap->has_helper) {
935          if (tap->has_ifname || tap->has_script || tap->has_downscript ||
936              tap->has_vnet_hdr || tap->has_queues || tap->has_vhostfds) {
937              error_setg(errp, "ifname=, script=, downscript=, vnet_hdr=, "
938                         "queues=, and vhostfds= are invalid with helper=");
939              return -1;
940          }
941  
942          fd = net_bridge_run_helper(tap->helper,
943                                     tap->has_br ?
944                                     tap->br : DEFAULT_BRIDGE_INTERFACE,
945                                     errp);
946          if (fd == -1) {
947              return -1;
948          }
949  
950          qemu_set_nonblock(fd);
951          vnet_hdr = tap_probe_vnet_hdr(fd, errp);
952          if (vnet_hdr < 0) {
953              close(fd);
954              return -1;
955          }
956  
957          net_init_tap_one(tap, peer, "bridge", name, ifname,
958                           script, downscript, vhostfdname,
959                           vnet_hdr, fd, &err);
960          if (err) {
961              error_propagate(errp, err);
962              close(fd);
963              return -1;
964          }
965      } else {
966          g_autofree char *default_script = NULL;
967          g_autofree char *default_downscript = NULL;
968          if (tap->has_vhostfds) {
969              error_setg(errp, "vhostfds= is invalid if fds= wasn't specified");
970              return -1;
971          }
972  
973          if (!script) {
974              script = default_script = get_relocated_path(DEFAULT_NETWORK_SCRIPT);
975          }
976          if (!downscript) {
977              downscript = default_downscript =
978                                   get_relocated_path(DEFAULT_NETWORK_DOWN_SCRIPT);
979          }
980  
981          if (tap->has_ifname) {
982              pstrcpy(ifname, sizeof ifname, tap->ifname);
983          } else {
984              ifname[0] = '\0';
985          }
986  
987          for (i = 0; i < queues; i++) {
988              fd = net_tap_init(tap, &vnet_hdr, i >= 1 ? "no" : script,
989                                ifname, sizeof ifname, queues > 1, errp);
990              if (fd == -1) {
991                  return -1;
992              }
993  
994              if (queues > 1 && i == 0 && !tap->has_ifname) {
995                  if (tap_fd_get_ifname(fd, ifname)) {
996                      error_setg(errp, "Fail to get ifname");
997                      close(fd);
998                      return -1;
999                  }
1000              }
1001  
1002              net_init_tap_one(tap, peer, "tap", name, ifname,
1003                               i >= 1 ? "no" : script,
1004                               i >= 1 ? "no" : downscript,
1005                               vhostfdname, vnet_hdr, fd, &err);
1006              if (err) {
1007                  error_propagate(errp, err);
1008                  close(fd);
1009                  return -1;
1010              }
1011          }
1012      }
1013  
1014      return 0;
1015  }
1016  
1017  VHostNetState *tap_get_vhost_net(NetClientState *nc)
1018  {
1019      TAPState *s = DO_UPCAST(TAPState, nc, nc);
1020      assert(nc->info->type == NET_CLIENT_DRIVER_TAP);
1021      return s->vhost_net;
1022  }
1023  
1024  int tap_enable(NetClientState *nc)
1025  {
1026      TAPState *s = DO_UPCAST(TAPState, nc, nc);
1027      int ret;
1028  
1029      if (s->enabled) {
1030          return 0;
1031      } else {
1032          ret = tap_fd_enable(s->fd);
1033          if (ret == 0) {
1034              s->enabled = true;
1035              tap_update_fd_handler(s);
1036          }
1037          return ret;
1038      }
1039  }
1040  
1041  int tap_disable(NetClientState *nc)
1042  {
1043      TAPState *s = DO_UPCAST(TAPState, nc, nc);
1044      int ret;
1045  
1046      if (s->enabled == 0) {
1047          return 0;
1048      } else {
1049          ret = tap_fd_disable(s->fd);
1050          if (ret == 0) {
1051              qemu_purge_queued_packets(nc);
1052              s->enabled = false;
1053              tap_update_fd_handler(s);
1054          }
1055          return ret;
1056      }
1057  }
1058