cachepc-qemu

Fork of AMDESE/qemu with changes for cachepc side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-qemu
Log | Files | Refs | Submodules | LICENSE | sfeed.txt

tap-linux.c (8888B)

      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 "qemu-common.h"
     28#include "tap_int.h"
     29#include "tap-linux.h"
     30#include "net/tap.h"
     31
     32#include <net/if.h>
     33#include <sys/ioctl.h>
     34
     35#include "qapi/error.h"
     36#include "qemu/error-report.h"
     37#include "qemu/cutils.h"
     38
     39#define PATH_NET_TUN "/dev/net/tun"
     40
     41int tap_open(char *ifname, int ifname_size, int *vnet_hdr,
     42             int vnet_hdr_required, int mq_required, Error **errp)
     43{
     44    struct ifreq ifr;
     45    int fd, ret;
     46    int len = sizeof(struct virtio_net_hdr);
     47    unsigned int features;
     48
     49    TFR(fd = open(PATH_NET_TUN, O_RDWR));
     50    if (fd < 0) {
     51        error_setg_errno(errp, errno, "could not open %s", PATH_NET_TUN);
     52        return -1;
     53    }
     54    memset(&ifr, 0, sizeof(ifr));
     55    ifr.ifr_flags = IFF_TAP | IFF_NO_PI;
     56
     57    if (ioctl(fd, TUNGETFEATURES, &features) == -1) {
     58        warn_report("TUNGETFEATURES failed: %s", strerror(errno));
     59        features = 0;
     60    }
     61
     62    if (features & IFF_ONE_QUEUE) {
     63        ifr.ifr_flags |= IFF_ONE_QUEUE;
     64    }
     65
     66    if (*vnet_hdr) {
     67        if (features & IFF_VNET_HDR) {
     68            *vnet_hdr = 1;
     69            ifr.ifr_flags |= IFF_VNET_HDR;
     70        } else {
     71            *vnet_hdr = 0;
     72        }
     73
     74        if (vnet_hdr_required && !*vnet_hdr) {
     75            error_setg(errp, "vnet_hdr=1 requested, but no kernel "
     76                       "support for IFF_VNET_HDR available");
     77            close(fd);
     78            return -1;
     79        }
     80        /*
     81         * Make sure vnet header size has the default value: for a persistent
     82         * tap it might have been modified e.g. by another instance of qemu.
     83         * Ignore errors since old kernels do not support this ioctl: in this
     84         * case the header size implicitly has the correct value.
     85         */
     86        ioctl(fd, TUNSETVNETHDRSZ, &len);
     87    }
     88
     89    if (mq_required) {
     90        if (!(features & IFF_MULTI_QUEUE)) {
     91            error_setg(errp, "multiqueue required, but no kernel "
     92                       "support for IFF_MULTI_QUEUE available");
     93            close(fd);
     94            return -1;
     95        } else {
     96            ifr.ifr_flags |= IFF_MULTI_QUEUE;
     97        }
     98    }
     99
    100    if (ifname[0] != '\0')
    101        pstrcpy(ifr.ifr_name, IFNAMSIZ, ifname);
    102    else
    103        pstrcpy(ifr.ifr_name, IFNAMSIZ, "tap%d");
    104    ret = ioctl(fd, TUNSETIFF, (void *) &ifr);
    105    if (ret != 0) {
    106        if (ifname[0] != '\0') {
    107            error_setg_errno(errp, errno, "could not configure %s (%s)",
    108                             PATH_NET_TUN, ifr.ifr_name);
    109        } else {
    110            error_setg_errno(errp, errno, "could not configure %s",
    111                             PATH_NET_TUN);
    112        }
    113        close(fd);
    114        return -1;
    115    }
    116    pstrcpy(ifname, ifname_size, ifr.ifr_name);
    117    fcntl(fd, F_SETFL, O_NONBLOCK);
    118    return fd;
    119}
    120
    121/* sndbuf implements a kind of flow control for tap.
    122 * Unfortunately when it's enabled, and packets are sent
    123 * to other guests on the same host, the receiver
    124 * can lock up the transmitter indefinitely.
    125 *
    126 * To avoid packet loss, sndbuf should be set to a value lower than the tx
    127 * queue capacity of any destination network interface.
    128 * Ethernet NICs generally have txqueuelen=1000, so 1Mb is
    129 * a good value, given a 1500 byte MTU.
    130 */
    131#define TAP_DEFAULT_SNDBUF 0
    132
    133void tap_set_sndbuf(int fd, const NetdevTapOptions *tap, Error **errp)
    134{
    135    int sndbuf;
    136
    137    sndbuf = !tap->has_sndbuf       ? TAP_DEFAULT_SNDBUF :
    138             tap->sndbuf > INT_MAX  ? INT_MAX :
    139             tap->sndbuf;
    140
    141    if (!sndbuf) {
    142        sndbuf = INT_MAX;
    143    }
    144
    145    if (ioctl(fd, TUNSETSNDBUF, &sndbuf) == -1 && tap->has_sndbuf) {
    146        error_setg_errno(errp, errno, "TUNSETSNDBUF ioctl failed");
    147    }
    148}
    149
    150int tap_probe_vnet_hdr(int fd, Error **errp)
    151{
    152    struct ifreq 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
    164int 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 */
    177int 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
    196void 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
    205int 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
    222int 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
    239void 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. */
    271int 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/ */
    289int 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
    306int 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
    320int 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}