qemu

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tap-linux.c (8908B)

      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 "qapi/error.h"
     35 #include "qemu/error-report.h"
     36 #include "qemu/cutils.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         warn_report("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     g_unix_set_fd_nonblocking(fd, true, NULL);
    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, Error **errp)
    150 {
    151     struct ifreq ifr;
    152     memset(&ifr, 0, sizeof(ifr));
    153 
    154     if (ioctl(fd, TUNGETIFF, &ifr) != 0) {
    155         /* TUNGETIFF is available since kernel v2.6.27 */
    156         error_setg_errno(errp, errno,
    157                          "Unable to query TUNGETIFF on FD %d", fd);
    158         return -1;
    159     }
    160 
    161     return ifr.ifr_flags & IFF_VNET_HDR;
    162 }
    163 
    164 int tap_probe_has_ufo(int fd)
    165 {
    166     unsigned offload;
    167 
    168     offload = TUN_F_CSUM | TUN_F_UFO;
    169 
    170     if (ioctl(fd, TUNSETOFFLOAD, offload) < 0)
    171         return 0;
    172 
    173     return 1;
    174 }
    175 
    176 /* Verify that we can assign given length */
    177 int tap_probe_vnet_hdr_len(int fd, int len)
    178 {
    179     int orig;
    180     if (ioctl(fd, TUNGETVNETHDRSZ, &orig) == -1) {
    181         return 0;
    182     }
    183     if (ioctl(fd, TUNSETVNETHDRSZ, &len) == -1) {
    184         return 0;
    185     }
    186     /* Restore original length: we can't handle failure. */
    187     if (ioctl(fd, TUNSETVNETHDRSZ, &orig) == -1) {
    188         fprintf(stderr, "TUNGETVNETHDRSZ ioctl() failed: %s. Exiting.\n",
    189                 strerror(errno));
    190         abort();
    191         return -errno;
    192     }
    193     return 1;
    194 }
    195 
    196 void tap_fd_set_vnet_hdr_len(int fd, int len)
    197 {
    198     if (ioctl(fd, TUNSETVNETHDRSZ, &len) == -1) {
    199         fprintf(stderr, "TUNSETVNETHDRSZ ioctl() failed: %s. Exiting.\n",
    200                 strerror(errno));
    201         abort();
    202     }
    203 }
    204 
    205 int tap_fd_set_vnet_le(int fd, int is_le)
    206 {
    207     int arg = is_le ? 1 : 0;
    208 
    209     if (!ioctl(fd, TUNSETVNETLE, &arg)) {
    210         return 0;
    211     }
    212 
    213     /* Check if our kernel supports TUNSETVNETLE */
    214     if (errno == EINVAL) {
    215         return -errno;
    216     }
    217 
    218     error_report("TUNSETVNETLE ioctl() failed: %s.", strerror(errno));
    219     abort();
    220 }
    221 
    222 int tap_fd_set_vnet_be(int fd, int is_be)
    223 {
    224     int arg = is_be ? 1 : 0;
    225 
    226     if (!ioctl(fd, TUNSETVNETBE, &arg)) {
    227         return 0;
    228     }
    229 
    230     /* Check if our kernel supports TUNSETVNETBE */
    231     if (errno == EINVAL) {
    232         return -errno;
    233     }
    234 
    235     error_report("TUNSETVNETBE ioctl() failed: %s.", strerror(errno));
    236     abort();
    237 }
    238 
    239 void tap_fd_set_offload(int fd, int csum, int tso4,
    240                         int tso6, int ecn, int ufo)
    241 {
    242     unsigned int offload = 0;
    243 
    244     /* Check if our kernel supports TUNSETOFFLOAD */
    245     if (ioctl(fd, TUNSETOFFLOAD, 0) != 0 && errno == EINVAL) {
    246         return;
    247     }
    248 
    249     if (csum) {
    250         offload |= TUN_F_CSUM;
    251         if (tso4)
    252             offload |= TUN_F_TSO4;
    253         if (tso6)
    254             offload |= TUN_F_TSO6;
    255         if ((tso4 || tso6) && ecn)
    256             offload |= TUN_F_TSO_ECN;
    257         if (ufo)
    258             offload |= TUN_F_UFO;
    259     }
    260 
    261     if (ioctl(fd, TUNSETOFFLOAD, offload) != 0) {
    262         offload &= ~TUN_F_UFO;
    263         if (ioctl(fd, TUNSETOFFLOAD, offload) != 0) {
    264             fprintf(stderr, "TUNSETOFFLOAD ioctl() failed: %s\n",
    265                     strerror(errno));
    266         }
    267     }
    268 }
    269 
    270 /* Enable a specific queue of tap. */
    271 int tap_fd_enable(int fd)
    272 {
    273     struct ifreq ifr;
    274     int ret;
    275 
    276     memset(&ifr, 0, sizeof(ifr));
    277 
    278     ifr.ifr_flags = IFF_ATTACH_QUEUE;
    279     ret = ioctl(fd, TUNSETQUEUE, (void *) &ifr);
    280 
    281     if (ret != 0) {
    282         error_report("could not enable queue");
    283     }
    284 
    285     return ret;
    286 }
    287 
    288 /* Disable a specific queue of tap/ */
    289 int tap_fd_disable(int fd)
    290 {
    291     struct ifreq ifr;
    292     int ret;
    293 
    294     memset(&ifr, 0, sizeof(ifr));
    295 
    296     ifr.ifr_flags = IFF_DETACH_QUEUE;
    297     ret = ioctl(fd, TUNSETQUEUE, (void *) &ifr);
    298 
    299     if (ret != 0) {
    300         error_report("could not disable queue");
    301     }
    302 
    303     return ret;
    304 }
    305 
    306 int tap_fd_get_ifname(int fd, char *ifname)
    307 {
    308     struct ifreq ifr;
    309 
    310     if (ioctl(fd, TUNGETIFF, &ifr) != 0) {
    311         error_report("TUNGETIFF ioctl() failed: %s",
    312                      strerror(errno));
    313         return -1;
    314     }
    315 
    316     pstrcpy(ifname, sizeof(ifr.ifr_name), ifr.ifr_name);
    317     return 0;
    318 }
    319 
    320 int tap_fd_set_steering_ebpf(int fd, int prog_fd)
    321 {
    322     if (ioctl(fd, TUNSETSTEERINGEBPF, (void *) &prog_fd) != 0) {
    323         error_report("Issue while setting TUNSETSTEERINGEBPF:"
    324                     " %s with fd: %d, prog_fd: %d",
    325                     strerror(errno), fd, prog_fd);
    326 
    327        return -1;
    328     }
    329 
    330     return 0;
    331 }