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dd8ac030fb
libvirt/src/util/virnetdevtap.c
Laine Stump dd8ac030fb util: add MTU arg to virNetDevTapCreateInBridgePort() 
virNetDevTapCreateInBridgePort() has always set the new tap device to
the current MTU of the bridge it's being attached to. There is one
case where we will want to set the new tap device to a different
(usually larger) MTU - if that's done with the very first device added
to the bridge, the bridge's MTU will be set to the device's MTU. This
patch allows for that possibility by adding "int mtu" to the arg list
for virNetDevTapCreateInBridgePort(), but all callers are sending -1,
so it doesn't yet have any effect.

Since the requested MTU isn't necessarily what is used in the end (for
example, if there is no MTU requested, the tap device will be set to
the current MTU of the bridge), and the hypervisor may want to know
the actual MTU used, we also return the actual MTU to the caller (if
actualMTU is non-NULL).
2017-02-07 13:45:08 -05:00

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/*
* Copyright (C) 2007-2014 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 "virnetdevmidonet.h"
#include "virnetdevopenvswitch.h"
#include "virerror.h"
#include "virfile.h"
#include "viralloc.h"
#include "virlog.h"
#include "virstring.h"
#include "datatypes.h"
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <regex.h>
#include <dirent.h>
#include <sys/types.h>
#include <sys/ioctl.h>
#include <net/if.h>
#include <fcntl.h>
#ifdef __linux__
# include <linux/if_tun.h> /* IFF_TUN, IFF_NO_PI */
#elif defined(__FreeBSD__)
# include <net/if_tap.h>
#endif
#if defined(HAVE_GETIFADDRS) && defined(AF_LINK)
# include <ifaddrs.h>
#endif
#define VIR_FROM_THIS VIR_FROM_NONE
VIR_LOG_INIT("util.netdevtap");
/**
* virNetDevTapGetName:
* @tapfd: a tun/tap file descriptor
* @ifname: a pointer that will receive the interface name
*
* Retrieve the interface name given a file descriptor for a tun/tap
* interface.
*
* Returns 0 if the interface name is successfully queried, -1 otherwise
*/
int
virNetDevTapGetName(int tapfd ATTRIBUTE_UNUSED, char **ifname ATTRIBUTE_UNUSED)
{
#ifdef TUNGETIFF
struct ifreq ifr;
if (ioctl(tapfd, TUNGETIFF, &ifr) < 0) {
virReportSystemError(errno, "%s",
_("Unable to query tap interface name"));
return -1;
}
return VIR_STRDUP(*ifname, ifr.ifr_name) < 0 ? -1 : 0;
#else
return -1;
#endif
}
/**
* virNetDevTapGetRealDeviceName:
* @ifname: the interface name
*
* Lookup real interface name (i.e. name of the device entry in /dev),
* because e.g. on FreeBSD if we rename tap device to vnetN its device
* entry still remains unchanged (/dev/tapX), but bhyve needs a name
* that matches /dev entry.
*
* Returns the proper interface name or NULL if no corresponding interface
* found.
*/
char*
virNetDevTapGetRealDeviceName(char *ifname ATTRIBUTE_UNUSED)
{
#ifdef TAPGIFNAME
char *ret = NULL;
struct dirent *dp;
DIR *dirp = NULL;
char *devpath = NULL;
int fd;
if (virDirOpen(&dirp, "/dev") < 0)
return NULL;
while (virDirRead(dirp, &dp, "/dev") > 0) {
if (STRPREFIX(dp->d_name, "tap")) {
struct ifreq ifr;
if (virAsprintf(&devpath, "/dev/%s", dp->d_name) < 0)
goto cleanup;
if ((fd = open(devpath, O_RDWR)) < 0) {
if (errno == EBUSY) {
VIR_FREE(devpath);
continue;
}
virReportSystemError(errno, _("Unable to open '%s'"), devpath);
goto cleanup;
}
if (ioctl(fd, TAPGIFNAME, (void *)&ifr) < 0) {
virReportSystemError(errno, "%s",
_("Unable to query tap interface name"));
goto cleanup;
}
if (STREQ(ifname, ifr.ifr_name)) {
/* we can ignore the return value
* because we still have nothing
* to do but return;
*/
ignore_value(VIR_STRDUP(ret, dp->d_name));
goto cleanup;
}
VIR_FREE(devpath);
VIR_FORCE_CLOSE(fd);
}
}
cleanup:
VIR_FREE(devpath);
VIR_FORCE_CLOSE(fd);
VIR_DIR_CLOSE(dirp);
return ret;
#else
return NULL;
#endif
}
/**
* 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
* @tunpath: path to the tun device (if NULL, /dev/net/tun is used)
* @tapfds: array of file descriptors return value for the new tap device
* @tapfdSize: number of file descriptors in @tapfd
* @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. The caller must use virNetDevTapDelete to
* remove a persistent TAP device when it is no longer needed. In case
* @tapfdSize is greater than one, multiqueue extension is requested
* from kernel.
*
* Returns 0 in case of success or -1 on failure.
*/
int virNetDevTapCreate(char **ifname,
const char *tunpath,
int *tapfd,
size_t tapfdSize,
unsigned int flags)
{
size_t i;
struct ifreq ifr;
int ret = -1;
int fd;
if (!tunpath)
tunpath = "/dev/net/tun";
memset(&ifr, 0, sizeof(ifr));
for (i = 0; i < tapfdSize; i++) {
if ((fd = open(tunpath, O_RDWR)) < 0) {
virReportSystemError(errno,
_("Unable to open %s, is tun module loaded?"),
tunpath);
goto cleanup;
}
memset(&ifr, 0, sizeof(ifr));
ifr.ifr_flags = IFF_TAP | IFF_NO_PI;
/* If tapfdSize is greater than one, request multiqueue */
if (tapfdSize > 1) {
# ifdef IFF_MULTI_QUEUE
ifr.ifr_flags |= IFF_MULTI_QUEUE;
# else
virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
_("Multiqueue devices are not supported on this system"));
goto cleanup;
# endif
}
# 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 (i == 0) {
/* In case we are looping more than once, set other
* TAPs to have the same name */
VIR_FREE(*ifname);
if (VIR_STRDUP(*ifname, ifr.ifr_name) < 0)
goto cleanup;
}
if ((flags & VIR_NETDEV_TAP_CREATE_PERSIST) &&
ioctl(fd, TUNSETPERSIST, 1) < 0) {
virReportSystemError(errno,
_("Unable to set tap device %s to persistent"),
NULLSTR(*ifname));
goto cleanup;
}
tapfd[i] = fd;
}
ret = 0;
cleanup:
if (ret < 0) {
VIR_FORCE_CLOSE(fd);
while (i--)
VIR_FORCE_CLOSE(tapfd[i]);
}
return ret;
}
int virNetDevTapDelete(const char *ifname,
const char *tunpath)
{
struct ifreq try;
int fd;
int ret = -1;
if (!tunpath)
tunpath = "/dev/net/tun";
if ((fd = open(tunpath, O_RDWR)) < 0) {
virReportSystemError(errno,
_("Unable to open %s, is tun module loaded?"),
tunpath);
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;
}
#elif defined(SIOCIFCREATE2) && defined(SIOCIFDESTROY) && defined(IF_MAXUNIT)
int virNetDevTapCreate(char **ifname,
const char *tunpath ATTRIBUTE_UNUSED,
int *tapfd,
size_t tapfdSize,
unsigned int flags ATTRIBUTE_UNUSED)
{
int s;
struct ifreq ifr;
int ret = -1;
char *newifname = NULL;
if (tapfdSize > 1) {
virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
_("Multiqueue devices are not supported on this system"));
goto cleanup;
}
/* As FreeBSD determines interface type by name,
* we have to create 'tap' interface first and
* then rename it to 'vnet'
*/
if ((s = virNetDevSetupControl("tap", &ifr)) < 0)
return -1;
if (ioctl(s, SIOCIFCREATE2, &ifr) < 0) {
virReportSystemError(errno, "%s",
_("Unable to create tap device"));
goto cleanup;
}
/* In case we were given exact interface name (e.g. 'vnetN'),
* we just rename to it. If we have format string like
* 'vnet%d', we need to find the first available name that
* matches this pattern
*/
if (strstr(*ifname, "%d") != NULL) {
size_t i;
for (i = 0; i <= IF_MAXUNIT; i++) {
char *newname;
if (virAsprintf(&newname, *ifname, i) < 0)
goto cleanup;
if (virNetDevExists(newname) == 0) {
newifname = newname;
break;
}
VIR_FREE(newname);
}
if (newifname) {
VIR_FREE(*ifname);
*ifname = newifname;
} else {
virReportError(VIR_ERR_INTERNAL_ERROR,
_("Failed to generate new name for interface %s"),
ifr.ifr_name);
goto cleanup;
}
}
if (tapfd) {
char *dev_path = NULL;
if (virAsprintf(&dev_path, "/dev/%s", ifr.ifr_name) < 0)
goto cleanup;
if ((*tapfd = open(dev_path, O_RDWR)) < 0) {
virReportSystemError(errno,
_("Unable to open %s"),
dev_path);
VIR_FREE(dev_path);
goto cleanup;
}
VIR_FREE(dev_path);
}
if (virNetDevSetName(ifr.ifr_name, *ifname) == -1)
goto cleanup;
ret = 0;
cleanup:
VIR_FORCE_CLOSE(s);
return ret;
}
int virNetDevTapDelete(const char *ifname,
const char *tunpath ATTRIBUTE_UNUSED)
{
int s;
struct ifreq ifr;
int ret = -1;
if ((s = virNetDevSetupControl(ifname, &ifr)) < 0)
return -1;
if (ioctl(s, SIOCIFDESTROY, &ifr) < 0) {
virReportSystemError(errno,
_("Unable to remove tap device %s"),
ifname);
goto cleanup;
}
ret = 0;
cleanup:
VIR_FORCE_CLOSE(s);
return ret;
}
#else
int virNetDevTapCreate(char **ifname ATTRIBUTE_UNUSED,
const char *tunpath ATTRIBUTE_UNUSED,
int *tapfd ATTRIBUTE_UNUSED,
size_t tapfdSize 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,
const char *tunpath ATTRIBUTE_UNUSED)
{
virReportSystemError(ENOSYS, "%s",
_("Unable to delete TAP devices on this platform"));
return -1;
}
#endif
/**
* virNetDevTapCreateInBridgePort:
* @brname: the bridge name
* @ifname: the interface name (or name template)
* @macaddr: desired MAC address
* @tunpath: path to the tun device (if NULL, /dev/net/tun is used)
* @tapfd: array of file descriptor return value for the new tap device
* @tapfdSize: number of file descriptors in @tapfd
* @virtPortProfile: bridge/port specific configuration
* @mtu: requested MTU for port (or 0 for "default")
* @actualMTU: MTU actually set for port (after accounting for bridge's MTU)
* @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 virMacAddr *macaddr,
const unsigned char *vmuuid,
const char *tunpath,
int *tapfd,
size_t tapfdSize,
virNetDevVPortProfilePtr virtPortProfile,
virNetDevVlanPtr virtVlan,
unsigned int mtu,
unsigned int *actualMTU,
unsigned int flags)
{
virMacAddr tapmac;
char macaddrstr[VIR_MAC_STRING_BUFLEN];
size_t i;
if (virNetDevTapCreate(ifname, tunpath, tapfd, tapfdSize, 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 - '%s' - "),
virMacAddrFormat(macaddr, macaddrstr));
goto error;
}
tapmac.addr[0] = 0xFE; /* Discourage bridge from using TAP dev MAC */
}
if (virNetDevSetMAC(*ifname, &tapmac) < 0)
goto error;
/* If an MTU is specified for the new device, set it before
* attaching the device to the bridge, as it may affect the MTU of
* the bridge (in particular if it is the first device attached to
* the bridge, or if it is smaller than the current MTU of the
* bridge). If MTU isn't specified for the new device (i.e. 0),
* we need to set the interface MTU to the current MTU of the
* bridge (to avoid inadvertantly changing the bridge's MTU).
*/
if (mtu > 0) {
if (virNetDevSetMTU(*ifname, mtu) < 0)
goto error;
} else {
if (virNetDevSetMTUFromDevice(*ifname, brname) < 0)
goto error;
}
if (actualMTU) {
int retMTU = virNetDevGetMTU(*ifname);
if (retMTU < 0)
goto error;
*actualMTU = retMTU;
}
if (virtPortProfile) {
if (virtPortProfile->virtPortType == VIR_NETDEV_VPORT_PROFILE_MIDONET) {
if (virNetDevMidonetBindPort(*ifname, virtPortProfile) < 0)
goto error;
} else if (virtPortProfile->virtPortType == VIR_NETDEV_VPORT_PROFILE_OPENVSWITCH) {
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:
for (i = 0; i < tapfdSize && tapfd[i] >= 0; i++)
VIR_FORCE_CLOSE(tapfd[i]);
return -1;
}
/*-------------------- interface stats --------------------*/
/* Just reads the named interface, so not Xen or QEMU-specific.
* NB. Caller must check that libvirt user is trying to query
* the interface of a domain they own. We do no such checking.
*/
#ifdef __linux__
int
virNetDevTapInterfaceStats(const char *ifname,
virDomainInterfaceStatsPtr stats)
{
int ifname_len;
FILE *fp;
char line[256], *colon;
fp = fopen("/proc/net/dev", "r");
if (!fp) {
virReportSystemError(errno, "%s",
_("Could not open /proc/net/dev"));
return -1;
}
ifname_len = strlen(ifname);
while (fgets(line, sizeof(line), fp)) {
long long dummy;
long long rx_bytes;
long long rx_packets;
long long rx_errs;
long long rx_drop;
long long tx_bytes;
long long tx_packets;
long long tx_errs;
long long tx_drop;
/* The line looks like:
* " eth0:..."
* Split it at the colon.
*/
colon = strchr(line, ':');
if (!colon) continue;
*colon = '\0';
if (colon-ifname_len >= line &&
STREQ(colon-ifname_len, ifname)) {
/* IMPORTANT NOTE!
* /proc/net/dev vif<domid>.nn sees the network from the point
* of view of dom0 / hypervisor. So bytes TRANSMITTED by dom0
* are bytes RECEIVED by the domain. That's why the TX/RX fields
* appear to be swapped here.
*/
if (sscanf(colon+1,
"%lld %lld %lld %lld %lld %lld %lld %lld %lld %lld %lld %lld %lld %lld %lld %lld",
&tx_bytes, &tx_packets, &tx_errs, &tx_drop,
&dummy, &dummy, &dummy, &dummy,
&rx_bytes, &rx_packets, &rx_errs, &rx_drop,
&dummy, &dummy, &dummy, &dummy) != 16)
continue;
stats->rx_bytes = rx_bytes;
stats->rx_packets = rx_packets;
stats->rx_errs = rx_errs;
stats->rx_drop = rx_drop;
stats->tx_bytes = tx_bytes;
stats->tx_packets = tx_packets;
stats->tx_errs = tx_errs;
stats->tx_drop = tx_drop;
VIR_FORCE_FCLOSE(fp);
return 0;
}
}
VIR_FORCE_FCLOSE(fp);
virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
_("/proc/net/dev: Interface not found"));
return -1;
}
#elif defined(HAVE_GETIFADDRS) && defined(AF_LINK)
int
virNetDevTapInterfaceStats(const char *ifname,
virDomainInterfaceStatsPtr stats)
{
struct ifaddrs *ifap, *ifa;
struct if_data *ifd;
int ret = -1;
if (getifaddrs(&ifap) < 0) {
virReportSystemError(errno, "%s",
_("Could not get interface list"));
return -1;
}
for (ifa = ifap; ifa; ifa = ifa->ifa_next) {
if (ifa->ifa_addr->sa_family != AF_LINK)
continue;
if (STREQ(ifa->ifa_name, ifname)) {
ifd = (struct if_data *)ifa->ifa_data;
stats->tx_bytes = ifd->ifi_ibytes;
stats->tx_packets = ifd->ifi_ipackets;
stats->tx_errs = ifd->ifi_ierrors;
stats->tx_drop = ifd->ifi_iqdrops;
stats->rx_bytes = ifd->ifi_obytes;
stats->rx_packets = ifd->ifi_opackets;
stats->rx_errs = ifd->ifi_oerrors;
# ifdef HAVE_STRUCT_IF_DATA_IFI_OQDROPS
stats->rx_drop = ifd->ifi_oqdrops;
# else
stats->rx_drop = 0;
# endif
ret = 0;
break;
}
}
if (ret < 0)
virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
_("Interface not found"));
freeifaddrs(ifap);
return ret;
}
#else
int
virNetDevTapInterfaceStats(const char *ifname ATTRIBUTE_UNUSED,
virDomainInterfaceStatsPtr stats ATTRIBUTE_UNUSED)
{
virReportError(VIR_ERR_OPERATION_INVALID, "%s",
_("interface stats not implemented on this platform"));
return -1;
}
#endif /* __linux__ */
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