net/tap-linux.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 #include "tap-linux.h"
  29 #include "net/tap.h"
  30
  31 #include <net/if.h>
  32 #include <sys/ioctl.h>
  33
  34 #include "sysemu/sysemu.h"
  35 #include "qemu-common.h"
  36 #include "qemu/error-report.h"
  37
  38 #define PATH_NET_TUN "/dev/net/tun"
  39
  40 int tap_open(char *ifname, int ifname_size, int *vnet_hdr,
  41              int vnet_hdr_required, int mq_required, Error **errp)
  42 {
  43     struct ifreq ifr;
  44     int fd, ret;
  45     int len = sizeof(struct virtio_net_hdr);
  46     unsigned int features;
  47
  48     TFR(fd = open(PATH_NET_TUN, O_RDWR));
  49     if (fd < 0) {
  50         error_setg_errno(errp, errno, "could not open %s", PATH_NET_TUN);
  51         return -1;
  52     }
  53     memset(&ifr, 0, sizeof(ifr));
  54     ifr.ifr_flags = IFF_TAP | IFF_NO_PI;
  55
  56     if (ioctl(fd, TUNGETFEATURES, &features) == -1) {
  57         error_report("warning: TUNGETFEATURES failed: %s", strerror(errno));
  58         features = 0;
  59     }
  60
  61     if (features & IFF_ONE_QUEUE) {
  62         ifr.ifr_flags |= IFF_ONE_QUEUE;
  63     }
  64
  65     if (*vnet_hdr) {
  66         if (features & IFF_VNET_HDR) {
  67             *vnet_hdr = 1;
  68             ifr.ifr_flags |= IFF_VNET_HDR;
  69         } else {
  70             *vnet_hdr = 0;
  71         }
  72
  73         if (vnet_hdr_required && !*vnet_hdr) {
  74             error_setg(errp, "vnet_hdr=1 requested, but no kernel "
  75                        "support for IFF_VNET_HDR available");
  76             close(fd);
  77             return -1;
  78         }
  79         /*
  80          * Make sure vnet header size has the default value: for a persistent
  81          * tap it might have been modified e.g. by another instance of qemu.
  82          * Ignore errors since old kernels do not support this ioctl: in this
  83          * case the header size implicitly has the correct value.
  84          */
  85         ioctl(fd, TUNSETVNETHDRSZ, &len);
  86     }
  87
  88     if (mq_required) {
  89         if (!(features & IFF_MULTI_QUEUE)) {
  90             error_setg(errp, "multiqueue required, but no kernel "
  91                        "support for IFF_MULTI_QUEUE available");
  92             close(fd);
  93             return -1;
  94         } else {
  95             ifr.ifr_flags |= IFF_MULTI_QUEUE;
  96         }
  97     }
  98
  99     if (ifname[0] != '\0')
 100         pstrcpy(ifr.ifr_name, IFNAMSIZ, ifname);
 101     else
 102         pstrcpy(ifr.ifr_name, IFNAMSIZ, "tap%d");
 103     ret = ioctl(fd, TUNSETIFF, (void *) &ifr);
 104     if (ret != 0) {
 105         if (ifname[0] != '\0') {
 106             error_setg_errno(errp, errno, "could not configure %s (%s)",
 107                              PATH_NET_TUN, ifr.ifr_name);
 108         } else {
 109             error_setg_errno(errp, errno, "could not configure %s",
 110                              PATH_NET_TUN);
 111         }
 112         close(fd);
 113         return -1;
 114     }
 115     pstrcpy(ifname, ifname_size, ifr.ifr_name);
 116     fcntl(fd, F_SETFL, O_NONBLOCK);
 117     return fd;
 118 }
 119
 120 /* sndbuf implements a kind of flow control for tap.
 121  * Unfortunately when it's enabled, and packets are sent
 122  * to other guests on the same host, the receiver
 123  * can lock up the transmitter indefinitely.
 124  *
 125  * To avoid packet loss, sndbuf should be set to a value lower than the tx
 126  * queue capacity of any destination network interface.
 127  * Ethernet NICs generally have txqueuelen=1000, so 1Mb is
 128  * a good value, given a 1500 byte MTU.
 129  */
 130 #define TAP_DEFAULT_SNDBUF 0
 131
 132 void tap_set_sndbuf(int fd, const NetdevTapOptions *tap, Error **errp)
 133 {
 134     int sndbuf;
 135
 136     sndbuf = !tap->has_sndbuf       ? TAP_DEFAULT_SNDBUF :
 137              tap->sndbuf > INT_MAX  ? INT_MAX :
 138              tap->sndbuf;
 139
 140     if (!sndbuf) {
 141         sndbuf = INT_MAX;
 142     }
 143
 144     if (ioctl(fd, TUNSETSNDBUF, &sndbuf) == -1 && tap->has_sndbuf) {
 145         error_setg_errno(errp, errno, "TUNSETSNDBUF ioctl failed");
 146     }
 147 }
 148
 149 int tap_probe_vnet_hdr(int fd)
 150 {
 151     struct ifreq ifr;
 152
 153     if (ioctl(fd, TUNGETIFF, &ifr) != 0) {
 154         error_report("TUNGETIFF ioctl() failed: %s", strerror(errno));
 155         return 0;
 156     }
 157
 158     return ifr.ifr_flags & IFF_VNET_HDR;
 159 }
 160
 161 int tap_probe_has_ufo(int fd)
 162 {
 163     unsigned offload;
 164
 165     offload = TUN_F_CSUM | TUN_F_UFO;
 166
 167     if (ioctl(fd, TUNSETOFFLOAD, offload) < 0)
 168         return 0;
 169
 170     return 1;
 171 }
 172
 173 /* Verify that we can assign given length */
 174 int tap_probe_vnet_hdr_len(int fd, int len)
 175 {
 176     int orig;
 177     if (ioctl(fd, TUNGETVNETHDRSZ, &orig) == -1) {
 178         return 0;
 179     }
 180     if (ioctl(fd, TUNSETVNETHDRSZ, &len) == -1) {
 181         return 0;
 182     }
 183     /* Restore original length: we can't handle failure. */
 184     if (ioctl(fd, TUNSETVNETHDRSZ, &orig) == -1) {
 185         fprintf(stderr, "TUNGETVNETHDRSZ ioctl() failed: %s. Exiting.\n",
 186                 strerror(errno));
 187         abort();
 188         return -errno;
 189     }
 190     return 1;
 191 }
 192
 193 void tap_fd_set_vnet_hdr_len(int fd, int len)
 194 {
 195     if (ioctl(fd, TUNSETVNETHDRSZ, &len) == -1) {
 196         fprintf(stderr, "TUNSETVNETHDRSZ ioctl() failed: %s. Exiting.\n",
 197                 strerror(errno));
 198         abort();
 199     }
 200 }
 201
 202 int tap_fd_set_vnet_le(int fd, int is_le)
 203 {
 204     int arg = is_le ? 1 : 0;
 205
 206     if (!ioctl(fd, TUNSETVNETLE, &arg)) {
 207         return 0;
 208     }
 209
 210     /* Check if our kernel supports TUNSETVNETLE */
 211     if (errno == EINVAL) {
 212         return -errno;
 213     }
 214
 215     error_report("TUNSETVNETLE ioctl() failed: %s.", strerror(errno));
 216     abort();
 217 }
 218
 219 int tap_fd_set_vnet_be(int fd, int is_be)
 220 {
 221     int arg = is_be ? 1 : 0;
 222
 223     if (!ioctl(fd, TUNSETVNETBE, &arg)) {
 224         return 0;
 225     }
 226
 227     /* Check if our kernel supports TUNSETVNETBE */
 228     if (errno == EINVAL) {
 229         return -errno;
 230     }
 231
 232     error_report("TUNSETVNETBE ioctl() failed: %s.", strerror(errno));
 233     abort();
 234 }
 235
 236 void tap_fd_set_offload(int fd, int csum, int tso4,
 237                         int tso6, int ecn, int ufo)
 238 {
 239     unsigned int offload = 0;
 240
 241     /* Check if our kernel supports TUNSETOFFLOAD */
 242     if (ioctl(fd, TUNSETOFFLOAD, 0) != 0 && errno == EINVAL) {
 243         return;
 244     }
 245
 246     if (csum) {
 247         offload |= TUN_F_CSUM;
 248         if (tso4)
 249             offload |= TUN_F_TSO4;
 250         if (tso6)
 251             offload |= TUN_F_TSO6;
 252         if ((tso4 || tso6) && ecn)
 253             offload |= TUN_F_TSO_ECN;
 254         if (ufo)
 255             offload |= TUN_F_UFO;
 256     }
 257
 258     if (ioctl(fd, TUNSETOFFLOAD, offload) != 0) {
 259         offload &= ~TUN_F_UFO;
 260         if (ioctl(fd, TUNSETOFFLOAD, offload) != 0) {
 261             fprintf(stderr, "TUNSETOFFLOAD ioctl() failed: %s\n",
 262                     strerror(errno));
 263         }
 264     }
 265 }
 266
 267 /* Enable a specific queue of tap. */
 268 int tap_fd_enable(int fd)
 269 {
 270     struct ifreq ifr;
 271     int ret;
 272
 273     memset(&ifr, 0, sizeof(ifr));
 274
 275     ifr.ifr_flags = IFF_ATTACH_QUEUE;
 276     ret = ioctl(fd, TUNSETQUEUE, (void *) &ifr);
 277
 278     if (ret != 0) {
 279         error_report("could not enable queue");
 280     }
 281
 282     return ret;
 283 }
 284
 285 /* Disable a specific queue of tap/ */
 286 int tap_fd_disable(int fd)
 287 {
 288     struct ifreq ifr;
 289     int ret;
 290
 291     memset(&ifr, 0, sizeof(ifr));
 292
 293     ifr.ifr_flags = IFF_DETACH_QUEUE;
 294     ret = ioctl(fd, TUNSETQUEUE, (void *) &ifr);
 295
 296     if (ret != 0) {
 297         error_report("could not disable queue");
 298     }
 299
 300     return ret;
 301 }
 302
 303 int tap_fd_get_ifname(int fd, char *ifname)
 304 {
 305     struct ifreq ifr;
 306
 307     if (ioctl(fd, TUNGETIFF, &ifr) != 0) {
 308         error_report("TUNGETIFF ioctl() failed: %s",
 309                      strerror(errno));
 310         return -1;
 311     }
 312
 313     pstrcpy(ifname, sizeof(ifr.ifr_name), ifr.ifr_name);
 314     return 0;
 315 }