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 "net/tap.h"
  27
  28 #include "config-host.h"
  29
  30 #include <signal.h>
  31 #include <sys/ioctl.h>
  32 #include <sys/stat.h>
  33 #include <sys/wait.h>
  34 #include <sys/socket.h>
  35 #include <net/if.h>
  36
  37 #include "net.h"
  38 #include "sysemu.h"
  39 #include "qemu-char.h"
  40 #include "qemu-common.h"
  41 #include "qemu-error.h"
  42
  43 #include "net/tap-linux.h"
  44
  45 /* Maximum GSO packet size (64k) plus plenty of room for
  46  * the ethernet and virtio_net headers
  47  */
  48 #define TAP_BUFSIZE (4096 + 65536)
  49
  50 typedef struct TAPState {
  51     VLANClientState nc;
  52     int fd;
  53     char down_script[1024];
  54     char down_script_arg[128];
  55     uint8_t buf[TAP_BUFSIZE];
  56     unsigned int read_poll : 1;
  57     unsigned int write_poll : 1;
  58     unsigned int has_vnet_hdr : 1;
  59     unsigned int using_vnet_hdr : 1;
  60     unsigned int has_ufo: 1;
  61 } TAPState;
  62
  63 static int launch_script(const char *setup_script, const char *ifname, int fd);
  64
  65 static int tap_can_send(void *opaque);
  66 static void tap_send(void *opaque);
  67 static void tap_writable(void *opaque);
  68
  69 static void tap_update_fd_handler(TAPState *s)
  70 {
  71     qemu_set_fd_handler2(s->fd,
  72                          s->read_poll  ? tap_can_send : NULL,
  73                          s->read_poll  ? tap_send     : NULL,
  74                          s->write_poll ? tap_writable : NULL,
  75                          s);
  76 }
  77
  78 static void tap_read_poll(TAPState *s, int enable)
  79 {
  80     s->read_poll = !!enable;
  81     tap_update_fd_handler(s);
  82 }
  83
  84 static void tap_write_poll(TAPState *s, int enable)
  85 {
  86     s->write_poll = !!enable;
  87     tap_update_fd_handler(s);
  88 }
  89
  90 static void tap_writable(void *opaque)
  91 {
  92     TAPState *s = opaque;
  93
  94     tap_write_poll(s, 0);
  95
  96     qemu_flush_queued_packets(&s->nc);
  97 }
  98
  99 static ssize_t tap_write_packet(TAPState *s, const struct iovec *iov, int iovcnt)
 100 {
 101     ssize_t len;
 102
 103     do {
 104         len = writev(s->fd, iov, iovcnt);
 105     } while (len == -1 && errno == EINTR);
 106
 107     if (len == -1 && errno == EAGAIN) {
 108         tap_write_poll(s, 1);
 109         return 0;
 110     }
 111
 112     return len;
 113 }
 114
 115 static ssize_t tap_receive_iov(VLANClientState *nc, const struct iovec *iov,
 116                                int iovcnt)
 117 {
 118     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 119     const struct iovec *iovp = iov;
 120     struct iovec iov_copy[iovcnt + 1];
 121     struct virtio_net_hdr hdr = { 0, };
 122
 123     if (s->has_vnet_hdr && !s->using_vnet_hdr) {
 124         iov_copy[0].iov_base = &hdr;
 125         iov_copy[0].iov_len =  sizeof(hdr);
 126         memcpy(&iov_copy[1], iov, iovcnt * sizeof(*iov));
 127         iovp = iov_copy;
 128         iovcnt++;
 129     }
 130
 131     return tap_write_packet(s, iovp, iovcnt);
 132 }
 133
 134 static ssize_t tap_receive_raw(VLANClientState *nc, const uint8_t *buf, size_t size)
 135 {
 136     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 137     struct iovec iov[2];
 138     int iovcnt = 0;
 139     struct virtio_net_hdr hdr = { 0, };
 140
 141     if (s->has_vnet_hdr) {
 142         iov[iovcnt].iov_base = &hdr;
 143         iov[iovcnt].iov_len  = sizeof(hdr);
 144         iovcnt++;
 145     }
 146
 147     iov[iovcnt].iov_base = (char *)buf;
 148     iov[iovcnt].iov_len  = size;
 149     iovcnt++;
 150
 151     return tap_write_packet(s, iov, iovcnt);
 152 }
 153
 154 static ssize_t tap_receive(VLANClientState *nc, const uint8_t *buf, size_t size)
 155 {
 156     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 157     struct iovec iov[1];
 158
 159     if (s->has_vnet_hdr && !s->using_vnet_hdr) {
 160         return tap_receive_raw(nc, buf, size);
 161     }
 162
 163     iov[0].iov_base = (char *)buf;
 164     iov[0].iov_len  = size;
 165
 166     return tap_write_packet(s, iov, 1);
 167 }
 168
 169 static int tap_can_send(void *opaque)
 170 {
 171     TAPState *s = opaque;
 172
 173     return qemu_can_send_packet(&s->nc);
 174 }
 175
 176 #ifndef __sun__
 177 ssize_t tap_read_packet(int tapfd, uint8_t *buf, int maxlen)
 178 {
 179     return read(tapfd, buf, maxlen);
 180 }
 181 #endif
 182
 183 static void tap_send_completed(VLANClientState *nc, ssize_t len)
 184 {
 185     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 186     tap_read_poll(s, 1);
 187 }
 188
 189 static void tap_send(void *opaque)
 190 {
 191     TAPState *s = opaque;
 192     int size;
 193
 194     do {
 195         uint8_t *buf = s->buf;
 196
 197         size = tap_read_packet(s->fd, s->buf, sizeof(s->buf));
 198         if (size <= 0) {
 199             break;
 200         }
 201
 202         if (s->has_vnet_hdr && !s->using_vnet_hdr) {
 203             buf  += sizeof(struct virtio_net_hdr);
 204             size -= sizeof(struct virtio_net_hdr);
 205         }
 206
 207         size = qemu_send_packet_async(&s->nc, buf, size, tap_send_completed);
 208         if (size == 0) {
 209             tap_read_poll(s, 0);
 210         }
 211     } while (size > 0 && qemu_can_send_packet(&s->nc));
 212 }
 213
 214 int tap_has_ufo(VLANClientState *nc)
 215 {
 216     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 217
 218     assert(nc->info->type == NET_CLIENT_TYPE_TAP);
 219
 220     return s->has_ufo;
 221 }
 222
 223 int tap_has_vnet_hdr(VLANClientState *nc)
 224 {
 225     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 226
 227     assert(nc->info->type == NET_CLIENT_TYPE_TAP);
 228
 229     return s->has_vnet_hdr;
 230 }
 231
 232 void tap_using_vnet_hdr(VLANClientState *nc, int using_vnet_hdr)
 233 {
 234     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 235
 236     using_vnet_hdr = using_vnet_hdr != 0;
 237
 238     assert(nc->info->type == NET_CLIENT_TYPE_TAP);
 239     assert(s->has_vnet_hdr == using_vnet_hdr);
 240
 241     s->using_vnet_hdr = using_vnet_hdr;
 242 }
 243
 244 void tap_set_offload(VLANClientState *nc, int csum, int tso4,
 245                      int tso6, int ecn, int ufo)
 246 {
 247     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 248
 249     return tap_fd_set_offload(s->fd, csum, tso4, tso6, ecn, ufo);
 250 }
 251
 252 static void tap_cleanup(VLANClientState *nc)
 253 {
 254     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 255
 256     qemu_purge_queued_packets(nc);
 257
 258     if (s->down_script[0])
 259         launch_script(s->down_script, s->down_script_arg, s->fd);
 260
 261     tap_read_poll(s, 0);
 262     tap_write_poll(s, 0);
 263     close(s->fd);
 264 }
 265
 266 static void tap_poll(VLANClientState *nc, bool enable)
 267 {
 268     TAPState *s = DO_UPCAST(TAPState, nc, nc);
 269     tap_read_poll(s, enable);
 270     tap_write_poll(s, enable);
 271 }
 272
 273 /* fd support */
 274
 275 static NetClientInfo net_tap_info = {
 276     .type = NET_CLIENT_TYPE_TAP,
 277     .size = sizeof(TAPState),
 278     .receive = tap_receive,
 279     .receive_raw = tap_receive_raw,
 280     .receive_iov = tap_receive_iov,
 281     .poll = tap_poll,
 282     .cleanup = tap_cleanup,
 283 };
 284
 285 static TAPState *net_tap_fd_init(VLANState *vlan,
 286                                  const char *model,
 287                                  const char *name,
 288                                  int fd,
 289                                  int vnet_hdr)
 290 {
 291     VLANClientState *nc;
 292     TAPState *s;
 293
 294     nc = qemu_new_net_client(&net_tap_info, vlan, NULL, model, name);
 295
 296     s = DO_UPCAST(TAPState, nc, nc);
 297
 298     s->fd = fd;
 299     s->has_vnet_hdr = vnet_hdr != 0;
 300     s->using_vnet_hdr = 0;
 301     s->has_ufo = tap_probe_has_ufo(s->fd);
 302     tap_set_offload(&s->nc, 0, 0, 0, 0, 0);
 303     tap_read_poll(s, 1);
 304     return s;
 305 }
 306
 307 static int launch_script(const char *setup_script, const char *ifname, int fd)
 308 {
 309     sigset_t oldmask, mask;
 310     int pid, status;
 311     char *args[3];
 312     char **parg;
 313
 314     sigemptyset(&mask);
 315     sigaddset(&mask, SIGCHLD);
 316     sigprocmask(SIG_BLOCK, &mask, &oldmask);
 317
 318     /* try to launch network script */
 319     pid = fork();
 320     if (pid == 0) {
 321         int open_max = sysconf(_SC_OPEN_MAX), i;
 322
 323         for (i = 0; i < open_max; i++) {
 324             if (i != STDIN_FILENO &&
 325                 i != STDOUT_FILENO &&
 326                 i != STDERR_FILENO &&
 327                 i != fd) {
 328                 close(i);
 329             }
 330         }
 331         parg = args;
 332         *parg++ = (char *)setup_script;
 333         *parg++ = (char *)ifname;
 334         *parg++ = NULL;
 335         execv(setup_script, args);
 336         _exit(1);
 337     } else if (pid > 0) {
 338         while (waitpid(pid, &status, 0) != pid) {
 339             /* loop */
 340         }
 341         sigprocmask(SIG_SETMASK, &oldmask, NULL);
 342
 343         if (WIFEXITED(status) && WEXITSTATUS(status) == 0) {
 344             return 0;
 345         }
 346     }
 347     fprintf(stderr, "%s: could not launch network script\n", setup_script);
 348     return -1;
 349 }
 350
 351 static int net_tap_init(QemuOpts *opts, int *vnet_hdr)
 352 {
 353     int fd, vnet_hdr_required;
 354     char ifname[128] = {0,};
 355     const char *setup_script;
 356
 357     if (qemu_opt_get(opts, "ifname")) {
 358         pstrcpy(ifname, sizeof(ifname), qemu_opt_get(opts, "ifname"));
 359     }
 360
 361     *vnet_hdr = qemu_opt_get_bool(opts, "vnet_hdr", 1);
 362     if (qemu_opt_get(opts, "vnet_hdr")) {
 363         vnet_hdr_required = *vnet_hdr;
 364     } else {
 365         vnet_hdr_required = 0;
 366     }
 367
 368     TFR(fd = tap_open(ifname, sizeof(ifname), vnet_hdr, vnet_hdr_required));
 369     if (fd < 0) {
 370         return -1;
 371     }
 372
 373     setup_script = qemu_opt_get(opts, "script");
 374     if (setup_script &&
 375         setup_script[0] != '\0' &&
 376         strcmp(setup_script, "no") != 0 &&
 377         launch_script(setup_script, ifname, fd)) {
 378         close(fd);
 379         return -1;
 380     }
 381
 382     qemu_opt_set(opts, "ifname", ifname);
 383
 384     return fd;
 385 }
 386
 387 int net_init_tap(QemuOpts *opts, Monitor *mon, const char *name, VLANState *vlan)
 388 {
 389     TAPState *s;
 390     int fd, vnet_hdr = 0;
 391
 392     if (qemu_opt_get(opts, "fd")) {
 393         if (qemu_opt_get(opts, "ifname") ||
 394             qemu_opt_get(opts, "script") ||
 395             qemu_opt_get(opts, "downscript") ||
 396             qemu_opt_get(opts, "vnet_hdr")) {
 397             error_report("ifname=, script=, downscript= and vnet_hdr= is invalid with fd=");
 398             return -1;
 399         }
 400
 401         fd = net_handle_fd_param(mon, qemu_opt_get(opts, "fd"));
 402         if (fd == -1) {
 403             return -1;
 404         }
 405
 406         fcntl(fd, F_SETFL, O_NONBLOCK);
 407
 408         vnet_hdr = tap_probe_vnet_hdr(fd);
 409     } else {
 410         if (!qemu_opt_get(opts, "script")) {
 411             qemu_opt_set(opts, "script", DEFAULT_NETWORK_SCRIPT);
 412         }
 413
 414         if (!qemu_opt_get(opts, "downscript")) {
 415             qemu_opt_set(opts, "downscript", DEFAULT_NETWORK_DOWN_SCRIPT);
 416         }
 417
 418         fd = net_tap_init(opts, &vnet_hdr);
 419         if (fd == -1) {
 420             return -1;
 421         }
 422     }
 423
 424     s = net_tap_fd_init(vlan, "tap", name, fd, vnet_hdr);
 425     if (!s) {
 426         close(fd);
 427         return -1;
 428     }
 429
 430     if (tap_set_sndbuf(s->fd, opts) < 0) {
 431         return -1;
 432     }
 433
 434     if (qemu_opt_get(opts, "fd")) {
 435         snprintf(s->nc.info_str, sizeof(s->nc.info_str), "fd=%d", fd);
 436     } else {
 437         const char *ifname, *script, *downscript;
 438
 439         ifname     = qemu_opt_get(opts, "ifname");
 440         script     = qemu_opt_get(opts, "script");
 441         downscript = qemu_opt_get(opts, "downscript");
 442
 443         snprintf(s->nc.info_str, sizeof(s->nc.info_str),
 444                  "ifname=%s,script=%s,downscript=%s",
 445                  ifname, script, downscript);
 446
 447         if (strcmp(downscript, "no") != 0) {
 448             snprintf(s->down_script, sizeof(s->down_script), "%s", downscript);
 449             snprintf(s->down_script_arg, sizeof(s->down_script_arg), "%s", ifname);
 450         }
 451     }
 452
 453     return 0;
 454 }