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/*
* Copyright (C) 2007-2012 Red Hat, Inc.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library. If not, see
* <http://www.gnu.org/licenses/>.
*
* Authors:
* Mark McLoughlin <markmc@redhat.com>
* Daniel P. Berrange <berrange@redhat.com>
*/
#include <config.h>
#include "virmacaddr.h"
#include "virnetdevtap.h"
#include "virnetdev.h"
#include "virnetdevbridge.h"
#include "virnetdevopenvswitch.h"
#include "virterror_internal.h"
#include "virfile.h"
#include "virterror_internal.h"
#include "memory.h"
#include "logging.h"
#include "util.h"
#include <sys/ioctl.h>
#include <net/if.h>
#include <fcntl.h>
#ifdef __linux__
# include <linux/if_tun.h> /* IFF_TUN, IFF_NO_PI */
#endif
#define VIR_FROM_THIS VIR_FROM_NONE
/**
* virNetDevProbeVnetHdr:
* @tapfd: a tun/tap file descriptor
*
* Check whether it is safe to enable the IFF_VNET_HDR flag on the
* tap interface.
*
* Setting IFF_VNET_HDR enables QEMU's virtio_net driver to allow
* guests to pass larger (GSO) packets, with partial checksums, to
* the host. This greatly increases the achievable throughput.
*
* It is only useful to enable this when we're setting up a virtio
* interface. And it is only *safe* to enable it when we know for
* sure that a) qemu has support for IFF_VNET_HDR and b) the running
* kernel implements the TUNGETIFF ioctl(), which qemu needs to query
* the supplied tapfd.
*
* Returns 1 if VnetHdr is supported, 0 if not supported
*/
#ifdef IFF_VNET_HDR
static int
virNetDevProbeVnetHdr(int tapfd)
{
# if defined(IFF_VNET_HDR) && defined(TUNGETFEATURES) && defined(TUNGETIFF)
unsigned int features;
struct ifreq dummy;
if (ioctl(tapfd, TUNGETFEATURES, &features) != 0) {
VIR_INFO("Not enabling IFF_VNET_HDR; "
"TUNGETFEATURES ioctl() not implemented");
return 0;
}
if (!(features & IFF_VNET_HDR)) {
VIR_INFO("Not enabling IFF_VNET_HDR; "
"TUNGETFEATURES ioctl() reports no IFF_VNET_HDR");
return 0;
}
/* The kernel will always return -1 at this point.
* If TUNGETIFF is not implemented then errno == EBADFD.
*/
if (ioctl(tapfd, TUNGETIFF, &dummy) != -1 || errno != EBADFD) {
VIR_INFO("Not enabling IFF_VNET_HDR; "
"TUNGETIFF ioctl() not implemented");
return 0;
}
VIR_INFO("Enabling IFF_VNET_HDR");
return 1;
# else
(void) tapfd;
VIR_INFO("Not enabling IFF_VNET_HDR; disabled at build time");
return 0;
# endif
}
#endif
#ifdef TUNSETIFF
/**
* virNetDevTapCreate:
* @ifname: the interface name
* @tapfd: file descriptor return value for the new tap device
* @flags: OR of virNetDevTapCreateFlags. Only one flag is recognized:
*
* VIR_NETDEV_TAP_CREATE_VNET_HDR
* - Enable IFF_VNET_HDR on the tap device
* VIR_NETDEV_TAP_CREATE_PERSIST
* - The device will persist after the file descriptor is closed
*
* Creates a tap interface.
* If the @tapfd parameter is supplied, the open tap device file descriptor
* will be returned, otherwise the TAP device will be closed. The caller must
* use virNetDevTapDelete to remove a persistent TAP device when it is no
* longer needed.
*
* Returns 0 in case of success or -1 on failure.
*/
int virNetDevTapCreate(char **ifname,
int *tapfd,
unsigned int flags)
{
int fd;
struct ifreq ifr;
int ret = -1;
if ((fd = open("/dev/net/tun", O_RDWR)) < 0) {
virReportSystemError(errno, "%s",
_("Unable to open /dev/net/tun, is tun module loaded?"));
return -1;
}
memset(&ifr, 0, sizeof(ifr));
ifr.ifr_flags = IFF_TAP|IFF_NO_PI;
# ifdef IFF_VNET_HDR
if ((flags & VIR_NETDEV_TAP_CREATE_VNET_HDR) &&
virNetDevProbeVnetHdr(fd))
ifr.ifr_flags |= IFF_VNET_HDR;
# endif
if (virStrcpyStatic(ifr.ifr_name, *ifname) == NULL) {
virReportSystemError(ERANGE,
_("Network interface name '%s' is too long"),
*ifname);
goto cleanup;
}
if (ioctl(fd, TUNSETIFF, &ifr) < 0) {
virReportSystemError(errno,
_("Unable to create tap device %s"),
NULLSTR(*ifname));
goto cleanup;
}
if ((flags & VIR_NETDEV_TAP_CREATE_PERSIST) &&
(errno = ioctl(fd, TUNSETPERSIST, 1))) {
virReportSystemError(errno,
_("Unable to set tap device %s to persistent"),
NULLSTR(*ifname));
goto cleanup;
}
VIR_FREE(*ifname);
if (!(*ifname = strdup(ifr.ifr_name))) {
virReportOOMError();
goto cleanup;
}
if (tapfd)
*tapfd = fd;
else
VIR_FORCE_CLOSE(fd);
ret = 0;
cleanup:
if (ret < 0)
VIR_FORCE_CLOSE(fd);
return ret;
}
int virNetDevTapDelete(const char *ifname)
{
struct ifreq try;
int fd;
int ret = -1;
if ((fd = open("/dev/net/tun", O_RDWR)) < 0) {
virReportSystemError(errno, "%s",
_("Unable to open /dev/net/tun, is tun module loaded?"));
return -1;
}
memset(&try, 0, sizeof(struct ifreq));
try.ifr_flags = IFF_TAP|IFF_NO_PI;
if (virStrcpyStatic(try.ifr_name, ifname) == NULL) {
virReportSystemError(ERANGE,
_("Network interface name '%s' is too long"),
ifname);
goto cleanup;
}
if (ioctl(fd, TUNSETIFF, &try) < 0) {
virReportSystemError(errno, "%s",
_("Unable to associate TAP device"));
goto cleanup;
}
if (ioctl(fd, TUNSETPERSIST, 0) < 0) {
virReportSystemError(errno, "%s",
_("Unable to make TAP device non-persistent"));
goto cleanup;
}
ret = 0;
cleanup:
VIR_FORCE_CLOSE(fd);
return ret;
}
#else /* ! TUNSETIFF */
int virNetDevTapCreate(char **ifname ATTRIBUTE_UNUSED,
int *tapfd ATTRIBUTE_UNUSED,
unsigned int flags ATTRIBUTE_UNUSED)
{
virReportSystemError(ENOSYS, "%s",
_("Unable to create TAP devices on this platform"));
return -1;
}
int virNetDevTapDelete(const char *ifname ATTRIBUTE_UNUSED)
{
virReportSystemError(ENOSYS, "%s",
_("Unable to delete TAP devices on this platform"));
return -1;
}
#endif /* ! TUNSETIFF */
/**
* virNetDevTapCreateInBridgePort:
* @brname: the bridge name
* @ifname: the interface name (or name template)
* @macaddr: desired MAC address
* @tapfd: file descriptor return value for the new tap device
* @virtPortProfile: bridge/port specific configuration
* @flags: OR of virNetDevTapCreateFlags:
* VIR_NETDEV_TAP_CREATE_IFUP
* - Bring the interface up
* VIR_NETDEV_TAP_CREATE_VNET_HDR
* - Enable IFF_VNET_HDR on the tap device
* VIR_NETDEV_TAP_CREATE_USE_MAC_FOR_BRIDGE
* - Set this interface's MAC as the bridge's MAC address
* VIR_NETDEV_TAP_CREATE_PERSIST
* - The device will persist after the file descriptor is closed
*
* This function creates a new tap device on a bridge. @ifname can be either
* a fixed name or a name template with '%d' for dynamic name allocation.
* in either case the final name for the bridge will be stored in @ifname.
* If the @tapfd parameter is supplied, the open tap device file descriptor
* will be returned, otherwise the TAP device will be closed. The caller must
* use virNetDevTapDelete to remove a persistent TAP device when it is no
* longer needed.
*
* Returns 0 in case of success or -1 on failure
*/
int virNetDevTapCreateInBridgePort(const char *brname,
char **ifname,
const virMacAddrPtr macaddr,
const unsigned char *vmuuid,
int *tapfd,
virNetDevVPortProfilePtr virtPortProfile,
virNetDevVlanPtr virtVlan,
unsigned int flags)
{
virMacAddr tapmac;
if (virNetDevTapCreate(ifname, tapfd, flags) < 0)
return -1;
/* We need to set the interface MAC before adding it
* to the bridge, because the bridge assumes the lowest
* MAC of all enslaved interfaces & we don't want it
* seeing the kernel allocate random MAC for the TAP
* device before we set our static MAC.
*/
virMacAddrSet(&tapmac, macaddr);
if (!(flags & VIR_NETDEV_TAP_CREATE_USE_MAC_FOR_BRIDGE)) {
if (macaddr->addr[0] == 0xFE) {
/* For normal use, the tap device's MAC address cannot
* match the MAC address used by the guest. This results
* in "received packet on vnetX with own address as source
* address" error logs from the kernel.
*/
virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
_("Unable to use MAC address starting with "
"reserved value 0xFE - '%02X:%02X:%02X:%02X:%02X:%02X' - "),
macaddr->addr[0], macaddr->addr[1],
macaddr->addr[2], macaddr->addr[3],
macaddr->addr[4], macaddr->addr[5]);
goto error;
}
tapmac.addr[0] = 0xFE; /* Discourage bridge from using TAP dev MAC */
}
if (virNetDevSetMAC(*ifname, &tapmac) < 0)
goto error;
/* We need to set the interface MTU before adding it
* to the bridge, because the bridge will have its
* MTU adjusted automatically when we add the new interface.
*/
if (virNetDevSetMTUFromDevice(*ifname, brname) < 0)
goto error;
if (virtPortProfile) {
if (virNetDevOpenvswitchAddPort(brname, *ifname, macaddr, vmuuid,
virtPortProfile, virtVlan) < 0) {
goto error;
}
} else {
if (virNetDevBridgeAddPort(brname, *ifname) < 0)
goto error;
}
if (virNetDevSetOnline(*ifname, !!(flags & VIR_NETDEV_TAP_CREATE_IFUP)) < 0)
goto error;
return 0;
error:
if (tapfd)
VIR_FORCE_CLOSE(*tapfd);
return -1;
}
|