libvirt/src/util/virnetdevmacvlan.c

/*
 * Copyright (C) 2010-2011 Red Hat, Inc.
 * Copyright (C) 2010 IBM Corporation
 *
 * 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, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307  USA
 *
 * Authors:
 *     Stefan Berger <stefanb@us.ibm.com>
 *
 * Notes:
 * netlink: http://lovezutto.googlepages.com/netlink.pdf
 *          iproute2 package
 *
 */

#include <config.h>


#include "virnetdevmacvlan.h"
#include "util.h"
#include "virterror_internal.h"

#define VIR_FROM_THIS VIR_FROM_NET

#define macvtapError(code, ...)                                         \
    virReportErrorHelper(VIR_FROM_NET, code, __FILE__,                  \
                         __FUNCTION__, __LINE__, __VA_ARGS__)


VIR_ENUM_IMPL(virNetDevMacVLanMode, VIR_NETDEV_MACVLAN_MODE_LAST,
              "vepa",
              "private",
              "bridge",
              "passthrough")

#if WITH_MACVTAP

# include <stdint.h>
# include <stdio.h>
# include <errno.h>
# include <fcntl.h>
# include <sys/socket.h>
# include <sys/ioctl.h>

# include <linux/if.h>
# include <linux/if_tun.h>

/* Older kernels lacked this enum value.  */
# if !HAVE_DECL_MACVLAN_MODE_PASSTHRU
#  define MACVLAN_MODE_PASSTHRU 8
# endif

# include "memory.h"
# include "logging.h"
# include "interface.h"
# include "uuid.h"
# include "virfile.h"
# include "netlink.h"
# include "virnetdev.h"

# define MACVTAP_NAME_PREFIX	"macvtap"
# define MACVTAP_NAME_PATTERN	"macvtap%d"

/**
 * virNetDevMacVLanTapOpen:
 * Open the macvtap's tap device.
 * @ifname: Name of the macvtap interface
 * @retries : Number of retries in case udev for example may need to be
 *            waited for to create the tap chardev
 * Returns negative value in case of error, the file descriptor otherwise.
 */
static
int virNetDevMacVLanTapOpen(const char *ifname,
                            int retries)
{
    FILE *file;
    char path[64];
    int ifindex;
    char tapname[50];
    int tapfd;

    if (snprintf(path, sizeof(path),
                 "/sys/class/net/%s/ifindex", ifname) >= sizeof(path)) {
        virReportSystemError(errno,
                             "%s",
                             _("buffer for ifindex path is too small"));
        return -1;
    }

    file = fopen(path, "r");

    if (!file) {
        virReportSystemError(errno,
                             _("cannot open macvtap file %s to determine "
                               "interface index"), path);
        return -1;
    }

    if (fscanf(file, "%d", &ifindex) != 1) {
        virReportSystemError(errno,
                             "%s",_("cannot determine macvtap's tap device "
                             "interface index"));
        VIR_FORCE_FCLOSE(file);
        return -1;
    }

    VIR_FORCE_FCLOSE(file);

    if (snprintf(tapname, sizeof(tapname),
                 "/dev/tap%d", ifindex) >= sizeof(tapname)) {
        virReportSystemError(errno,
                             "%s",
                             _("internal buffer for tap device is too small"));
        return -1;
    }

    while (1) {
        /* may need to wait for udev to be done */
        tapfd = open(tapname, O_RDWR);
        if (tapfd < 0 && retries > 0) {
            retries--;
            usleep(20000);
            continue;
        }
        break;
    }

    if (tapfd < 0)
        virReportSystemError(errno,
                             _("cannot open macvtap tap device %s"),
                             tapname);

    return tapfd;
}


/**
 * virNetDevMacVLanTapSetup:
 * @tapfd: file descriptor of the macvtap tap
 * @vnet_hdr: 1 to enable IFF_VNET_HDR, 0 to disable it
 *
 * Returns 0 on success, -1 in case of fatal error, error code otherwise.
 *
 * Turn the IFF_VNET_HDR flag, if requested and available, make sure
 * it's off in the other cases.
 * A fatal error is defined as the VNET_HDR flag being set but it cannot
 * be turned off for some reason. This is reported with -1. Other fatal
 * error is not being able to read the interface flags. In that case the
 * macvtap device should not be used.
 */
static int
virNetDevMacVLanTapSetup(int tapfd, int vnet_hdr)
{
    unsigned int features;
    struct ifreq ifreq;
    short new_flags = 0;
    int rc_on_fail = 0;
    const char *errmsg = NULL;

    memset(&ifreq, 0, sizeof(ifreq));

    if (ioctl(tapfd, TUNGETIFF, &ifreq) < 0) {
        virReportSystemError(errno, "%s",
                             _("cannot get interface flags on macvtap tap"));
        return -1;
    }

    new_flags = ifreq.ifr_flags;

    if ((ifreq.ifr_flags & IFF_VNET_HDR) && !vnet_hdr) {
        new_flags = ifreq.ifr_flags & ~IFF_VNET_HDR;
        rc_on_fail = -1;
        errmsg = _("cannot clean IFF_VNET_HDR flag on macvtap tap");
    } else if ((ifreq.ifr_flags & IFF_VNET_HDR) == 0 && vnet_hdr) {
        if (ioctl(tapfd, TUNGETFEATURES, &features) < 0) {
            virReportSystemError(errno, "%s",
                   _("cannot get feature flags on macvtap tap"));
            return -1;
        }
        if ((features & IFF_VNET_HDR)) {
            new_flags = ifreq.ifr_flags | IFF_VNET_HDR;
            errmsg = _("cannot set IFF_VNET_HDR flag on macvtap tap");
        }
    }

    if (new_flags != ifreq.ifr_flags) {
        ifreq.ifr_flags = new_flags;
        if (ioctl(tapfd, TUNSETIFF, &ifreq) < 0) {
            virReportSystemError(errno, "%s", errmsg);
            return rc_on_fail;
        }
    }

    return 0;
}


static const uint32_t modeMap[VIR_NETDEV_MACVLAN_MODE_LAST] = {
    [VIR_NETDEV_MACVLAN_MODE_VEPA] = MACVLAN_MODE_VEPA,
    [VIR_NETDEV_MACVLAN_MODE_PRIVATE] = MACVLAN_MODE_PRIVATE,
    [VIR_NETDEV_MACVLAN_MODE_BRIDGE] = MACVLAN_MODE_BRIDGE,
    [VIR_NETDEV_MACVLAN_MODE_PASSTHRU] = MACVLAN_MODE_PASSTHRU,
};

/**
 * virNetDevMacVLanCreate:
 * Create an instance of a macvtap device and open its tap character
 * device.
 * @tgifname: Interface name that the macvtap is supposed to have. May
 *    be NULL if this function is supposed to choose a name
 * @macaddress: The MAC address for the macvtap device
 * @linkdev: The interface name of the NIC to connect to the external bridge
 * @mode: int describing the mode for 'bridge', 'vepa', 'private' or 'passthru'.
 * @vnet_hdr: 1 to enable IFF_VNET_HDR, 0 to disable it
 * @vmuuid: The UUID of the VM the macvtap belongs to
 * @virtPortProfile: pointer to object holding the virtual port profile data
 * @res_ifname: Pointer to a string pointer where the actual name of the
 *     interface will be stored into if everything succeeded. It is up
 *     to the caller to free the string.
 *
 * Returns file descriptor of the tap device in case of success,
 * negative value otherwise with error reported.
 *
 */
int virNetDevMacVLanCreate(const char *tgifname,
                           const unsigned char *macaddress,
                           const char *linkdev,
                           enum virNetDevMacVLanMode mode,
                           int vnet_hdr,
                           const unsigned char *vmuuid,
                           virNetDevVPortProfilePtr virtPortProfile,
                           char **res_ifname,
                           enum virNetDevVPortProfileOp vmOp,
                           char *stateDir,
                           virNetDevBandwidthPtr bandwidth)
{
    const char *type = "macvtap";
    int c, rc;
    char ifname[IFNAMSIZ];
    int retries, do_retry = 0;
    uint32_t macvtapMode;
    const char *cr_ifname;
    int ifindex;

    macvtapMode = modeMap[mode];

    *res_ifname = NULL;

    VIR_DEBUG("%s: VM OPERATION: %s", __FUNCTION__, virNetDevVPortProfileOpTypeToString(vmOp));

    /** Note: When using PASSTHROUGH mode with MACVTAP devices the link
     * device's MAC address must be set to the VMs MAC address. In
     * order to not confuse the first switch or bridge in line this MAC
     * address must be reset when the VM is shut down.
     * This is especially important when using SRIOV capable cards that
     * emulate their switch in firmware.
     */
    if (mode == VIR_NETDEV_MACVLAN_MODE_PASSTHRU) {
        if (ifaceReplaceMacAddress(macaddress, linkdev, stateDir) < 0) {
            return -1;
        }
    }

    if (tgifname) {
        if(ifaceGetIndex(false, tgifname, &ifindex) == 0) {
            if (STRPREFIX(tgifname,
                          MACVTAP_NAME_PREFIX)) {
                goto create_name;
            }
            virReportSystemError(errno,
                                 _("Interface %s already exists"), tgifname);
            return -1;
        }
        cr_ifname = tgifname;
        rc = ifaceMacvtapLinkAdd(type, macaddress, 6, tgifname, linkdev,
                                 macvtapMode, &do_retry);
        if (rc < 0)
            return -1;
    } else {
create_name:
        retries = 5;
        for (c = 0; c < 8192; c++) {
            snprintf(ifname, sizeof(ifname), MACVTAP_NAME_PATTERN, c);
            if (ifaceGetIndex(false, ifname, &ifindex) == -ENODEV) {
                rc = ifaceMacvtapLinkAdd(type, macaddress, 6, ifname, linkdev,
                                         macvtapMode, &do_retry);
                if (rc == 0)
                    break;

                if (do_retry && --retries)
                    continue;
                return -1;
            }
        }
        cr_ifname = ifname;
    }

    if (virNetDevVPortProfileAssociate(cr_ifname,
                                       virtPortProfile,
                                       macaddress,
                                       linkdev,
                                       vmuuid, vmOp) < 0) {
        rc = -1;
        goto link_del_exit;
    }

    if (virNetDevSetOnline(cr_ifname, true) < 0) {
        rc = -1;
        goto disassociate_exit;
    }

    rc = virNetDevMacVLanTapOpen(cr_ifname, 10);
    if (rc >= 0) {
        if (virNetDevMacVLanTapSetup(rc, vnet_hdr) < 0) {
            VIR_FORCE_CLOSE(rc); /* sets rc to -1 */
            goto disassociate_exit;
        }
        *res_ifname = strdup(cr_ifname);
    } else
        goto disassociate_exit;

    if (virNetDevBandwidthSet(cr_ifname, bandwidth) < 0) {
        macvtapError(VIR_ERR_INTERNAL_ERROR,
                     _("cannot set bandwidth limits on %s"),
                     cr_ifname);
        rc = -1;
        goto disassociate_exit;
    }


    return rc;

disassociate_exit:
    ignore_value(virNetDevVPortProfileDisassociate(cr_ifname,
                                                   virtPortProfile,
                                                   macaddress,
                                                   linkdev,
                                                   vmOp));

link_del_exit:
    ifaceLinkDel(cr_ifname);

    return rc;
}


/**
 * delMacvtap:
 * @ifname : The name of the macvtap interface
 * @linkdev: The interface name of the NIC to connect to the external bridge
 * @virtPortProfile: pointer to object holding the virtual port profile data
 *
 * Delete an interface given its name. Disassociate
 * it with the switch if port profile parameters
 * were provided.
 */
int virNetDevMacVLanDelete(const char *ifname,
                           const unsigned char *macaddr,
                           const char *linkdev,
                           int mode,
                           virNetDevVPortProfilePtr virtPortProfile,
                           char *stateDir)
{
    int ret = 0;
    if (mode == VIR_NETDEV_MACVLAN_MODE_PASSTHRU) {
        ifaceRestoreMacAddress(linkdev, stateDir);
    }

    if (ifname) {
        if (virNetDevVPortProfileDisassociate(ifname,
                                              virtPortProfile,
                                              macaddr,
                                              linkdev,
                                              VIR_NETDEV_VPORT_PROFILE_OP_DESTROY) < 0)
            ret = -1;
        if (ifaceLinkDel(ifname) < 0)
            ret = -1;
    }
    return ret;
}

#else /* ! WITH_MACVTAP */
int virNetDevMacVLanCreate(const char *ifname ATTRIBUTE_UNUSED,
                           const unsigned char *macaddress ATTRIBUTE_UNUSED,
                           const char *linkdev ATTRIBUTE_UNUSED,
                           enum virNetDevMacVLanMode mode ATTRIBUTE_UNUSED,
                           int vnet_hdr ATTRIBUTE_UNUSED,
                           const unsigned char *vmuuid ATTRIBUTE_UNUSED,
                           virNetDevVPortProfilePtr virtPortProfile ATTRIBUTE_UNUSED,
                           char **res_ifname ATTRIBUTE_UNUSED,
                           enum virNetDevVPortProfileOp vmop ATTRIBUTE_UNUSED,
                           char *stateDir ATTRIBUTE_UNUSED,
                           virNetDevBandwidthPtr bandwidth ATTRIBUTE_UNUSED)
{
    virReportSystemError(ENOSYS, "%s",
                         _("Cannot create macvlan devices on this platform"));
    return -1;
}

int virNetDevMacVLanDelete(const char *ifname ATTRIBUTE_UNUSED,
                           const unsigned char *macaddress ATTRIBUTE_UNUSED,
                           const char *linkdev ATTRIBUTE_UNUSED,
                           int mode ATTRIBUTE_UNUSED,
                           virNetDevVPortProfilePtr virtPortProfile ATTRIBUTE_UNUSED,
                           char *stateDir ATTRIBUTE_UNUSED)
{
    virReportSystemError(ENOSYS, "%s",
                         _("Cannot create macvlan devices on this platform"));
    return -1;
}
#endif /* ! WITH_MACVTAP */