net/tap-linux.c - qemu - Git at Google

 /*
  * QEMU System Emulator
  *
  * Copyright (c) 2003-2008 Fabrice Bellard
  * Copyright (c) 2009 Red Hat, Inc.
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
  * in the Software without restriction, including without limitation the rights
  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  * copies of the Software, and to permit persons to whom the Software is
  * furnished to do so, subject to the following conditions:
  *
  * The above copyright notice and this permission notice shall be included in
  * all copies or substantial portions of the Software.
  *
  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  * THE SOFTWARE.
  */

 #include "tap_int.h"
 #include "tap-linux.h"
 #include "net/tap.h"

 #include <net/if.h>
 #include <sys/ioctl.h>

 #include "sysemu/sysemu.h"
 #include "qemu-common.h"
 #include "qemu/error-report.h"

 #define PATH_NET_TUN "/dev/net/tun"

 int tap_open(char *ifname, int ifname_size, int *vnet_hdr,
              int vnet_hdr_required, int mq_required, Error **errp)
 {
     struct ifreq ifr;
     int fd, ret;
     int len = sizeof(struct virtio_net_hdr);
     unsigned int features;

     TFR(fd = open(PATH_NET_TUN, O_RDWR));
     if (fd < 0) {
         error_setg_errno(errp, errno, "could not open %s", PATH_NET_TUN);
         return -1;
     }
     memset(&ifr, 0, sizeof(ifr));
     ifr.ifr_flags = IFF_TAP | IFF_NO_PI;

     if (ioctl(fd, TUNGETFEATURES, &features) == -1) {
         error_report("warning: TUNGETFEATURES failed: %s", strerror(errno));
         features = 0;
     }

     if (features & IFF_ONE_QUEUE) {
         ifr.ifr_flags |= IFF_ONE_QUEUE;
     }

     if (*vnet_hdr) {
         if (features & IFF_VNET_HDR) {
             *vnet_hdr = 1;
             ifr.ifr_flags |= IFF_VNET_HDR;
         } else {
             *vnet_hdr = 0;
         }

         if (vnet_hdr_required && !*vnet_hdr) {
             error_setg(errp, "vnet_hdr=1 requested, but no kernel "
                        "support for IFF_VNET_HDR available");
             close(fd);
             return -1;
         }
         /*
          * Make sure vnet header size has the default value: for a persistent
          * tap it might have been modified e.g. by another instance of qemu.
          * Ignore errors since old kernels do not support this ioctl: in this
          * case the header size implicitly has the correct value.
          */
         ioctl(fd, TUNSETVNETHDRSZ, &len);
     }

     if (mq_required) {
         if (!(features & IFF_MULTI_QUEUE)) {
             error_setg(errp, "multiqueue required, but no kernel "
                        "support for IFF_MULTI_QUEUE available");
             close(fd);
             return -1;
         } else {
             ifr.ifr_flags |= IFF_MULTI_QUEUE;
         }
     }

     if (ifname[0] != '\0')
         pstrcpy(ifr.ifr_name, IFNAMSIZ, ifname);
     else
         pstrcpy(ifr.ifr_name, IFNAMSIZ, "tap%d");
     ret = ioctl(fd, TUNSETIFF, (void *) &ifr);
     if (ret != 0) {
         if (ifname[0] != '\0') {
             error_setg_errno(errp, errno, "could not configure %s (%s)",
                              PATH_NET_TUN, ifr.ifr_name);
         } else {
             error_setg_errno(errp, errno, "could not configure %s",
                              PATH_NET_TUN);
         }
         close(fd);
         return -1;
     }
     pstrcpy(ifname, ifname_size, ifr.ifr_name);
     fcntl(fd, F_SETFL, O_NONBLOCK);
     return fd;
 }

 /* sndbuf implements a kind of flow control for tap.
  * Unfortunately when it's enabled, and packets are sent
  * to other guests on the same host, the receiver
  * can lock up the transmitter indefinitely.
  *
  * To avoid packet loss, sndbuf should be set to a value lower than the tx
  * queue capacity of any destination network interface.
  * Ethernet NICs generally have txqueuelen=1000, so 1Mb is
  * a good value, given a 1500 byte MTU.
  */
 #define TAP_DEFAULT_SNDBUF 0

 void tap_set_sndbuf(int fd, const NetdevTapOptions *tap, Error **errp)
 {
     int sndbuf;

     sndbuf = !tap->has_sndbuf       ? TAP_DEFAULT_SNDBUF :
              tap->sndbuf > INT_MAX  ? INT_MAX :
              tap->sndbuf;

     if (!sndbuf) {
         sndbuf = INT_MAX;
     }

     if (ioctl(fd, TUNSETSNDBUF, &sndbuf) == -1 && tap->has_sndbuf) {
         error_setg_errno(errp, errno, "TUNSETSNDBUF ioctl failed");
     }
 }

 int tap_probe_vnet_hdr(int fd)
 {
     struct ifreq ifr;

     if (ioctl(fd, TUNGETIFF, &ifr) != 0) {
         error_report("TUNGETIFF ioctl() failed: %s", strerror(errno));
         return 0;
     }

     return ifr.ifr_flags & IFF_VNET_HDR;
 }

 int tap_probe_has_ufo(int fd)
 {
     unsigned offload;

     offload = TUN_F_CSUM | TUN_F_UFO;

     if (ioctl(fd, TUNSETOFFLOAD, offload) < 0)
         return 0;

     return 1;
 }

 /* Verify that we can assign given length */
 int tap_probe_vnet_hdr_len(int fd, int len)
 {
     int orig;
     if (ioctl(fd, TUNGETVNETHDRSZ, &orig) == -1) {
         return 0;
     }
     if (ioctl(fd, TUNSETVNETHDRSZ, &len) == -1) {
         return 0;
     }
     /* Restore original length: we can't handle failure. */
     if (ioctl(fd, TUNSETVNETHDRSZ, &orig) == -1) {
         fprintf(stderr, "TUNGETVNETHDRSZ ioctl() failed: %s. Exiting.\n",
                 strerror(errno));
         abort();
         return -errno;
     }
     return 1;
 }

 void tap_fd_set_vnet_hdr_len(int fd, int len)
 {
     if (ioctl(fd, TUNSETVNETHDRSZ, &len) == -1) {
         fprintf(stderr, "TUNSETVNETHDRSZ ioctl() failed: %s. Exiting.\n",
                 strerror(errno));
         abort();
     }
 }

 int tap_fd_set_vnet_le(int fd, int is_le)
 {
     int arg = is_le ? 1 : 0;

     if (!ioctl(fd, TUNSETVNETLE, &arg)) {
         return 0;
     }

     /* Check if our kernel supports TUNSETVNETLE */
     if (errno == EINVAL) {
         return -errno;
     }

     error_report("TUNSETVNETLE ioctl() failed: %s.\n", strerror(errno));
     abort();
 }

 int tap_fd_set_vnet_be(int fd, int is_be)
 {
     int arg = is_be ? 1 : 0;

     if (!ioctl(fd, TUNSETVNETBE, &arg)) {
         return 0;
     }

     /* Check if our kernel supports TUNSETVNETBE */
     if (errno == EINVAL) {
         return -errno;
     }

     error_report("TUNSETVNETBE ioctl() failed: %s.\n", strerror(errno));
     abort();
 }

 void tap_fd_set_offload(int fd, int csum, int tso4,
                         int tso6, int ecn, int ufo)
 {
     unsigned int offload = 0;

     /* Check if our kernel supports TUNSETOFFLOAD */
     if (ioctl(fd, TUNSETOFFLOAD, 0) != 0 && errno == EINVAL) {
         return;
     }

     if (csum) {
         offload |= TUN_F_CSUM;
         if (tso4)
             offload |= TUN_F_TSO4;
         if (tso6)
             offload |= TUN_F_TSO6;
         if ((tso4 || tso6) && ecn)
             offload |= TUN_F_TSO_ECN;
         if (ufo)
             offload |= TUN_F_UFO;
     }

     if (ioctl(fd, TUNSETOFFLOAD, offload) != 0) {
         offload &= ~TUN_F_UFO;
         if (ioctl(fd, TUNSETOFFLOAD, offload) != 0) {
             fprintf(stderr, "TUNSETOFFLOAD ioctl() failed: %s\n",
                     strerror(errno));
         }
     }
 }

 /* Enable a specific queue of tap. */
 int tap_fd_enable(int fd)
 {
     struct ifreq ifr;
     int ret;

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

     ifr.ifr_flags = IFF_ATTACH_QUEUE;
     ret = ioctl(fd, TUNSETQUEUE, (void *) &ifr);

     if (ret != 0) {
         error_report("could not enable queue");
     }

     return ret;
 }

 /* Disable a specific queue of tap/ */
 int tap_fd_disable(int fd)
 {
     struct ifreq ifr;
     int ret;

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

     ifr.ifr_flags = IFF_DETACH_QUEUE;
     ret = ioctl(fd, TUNSETQUEUE, (void *) &ifr);

     if (ret != 0) {
         error_report("could not disable queue");
     }

     return ret;
 }

 int tap_fd_get_ifname(int fd, char *ifname)
 {
     struct ifreq ifr;

     if (ioctl(fd, TUNGETIFF, &ifr) != 0) {
         error_report("TUNGETIFF ioctl() failed: %s",
                      strerror(errno));
         return -1;
     }

     pstrcpy(ifname, sizeof(ifr.ifr_name), ifr.ifr_name);
     return 0;
 }
	/*
	* QEMU System Emulator
	*
	* Copyright (c) 2003-2008 Fabrice Bellard
	* Copyright (c) 2009 Red Hat, Inc.
	*
	* Permission is hereby granted, free of charge, to any person obtaining a copy
	* of this software and associated documentation files (the "Software"), to deal
	* in the Software without restriction, including without limitation the rights
	* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
	* copies of the Software, and to permit persons to whom the Software is
	* furnished to do so, subject to the following conditions:
	*
	* The above copyright notice and this permission notice shall be included in
	* all copies or substantial portions of the Software.
	*
	* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
	* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
	* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
	* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
	* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
	* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
	* THE SOFTWARE.
	*/

	#include "tap_int.h"
	#include "tap-linux.h"
	#include "net/tap.h"

	#include <net/if.h>
	#include <sys/ioctl.h>

	#include "sysemu/sysemu.h"
	#include "qemu-common.h"
	#include "qemu/error-report.h"

	#define PATH_NET_TUN "/dev/net/tun"

	int tap_open(char ifname, int ifname_size, int vnet_hdr,
	int vnet_hdr_required, int mq_required, Error **errp)
	{
	struct ifreq ifr;
	int fd, ret;
	int len = sizeof(struct virtio_net_hdr);
	unsigned int features;

	TFR(fd = open(PATH_NET_TUN, O_RDWR));
	if (fd < 0) {
	error_setg_errno(errp, errno, "could not open %s", PATH_NET_TUN);
	return -1;
	}
	memset(&ifr, 0, sizeof(ifr));
	ifr.ifr_flags = IFF_TAP \| IFF_NO_PI;

	if (ioctl(fd, TUNGETFEATURES, &features) == -1) {
	error_report("warning: TUNGETFEATURES failed: %s", strerror(errno));
	features = 0;
	}

	if (features & IFF_ONE_QUEUE) {
	ifr.ifr_flags \|= IFF_ONE_QUEUE;
	}

	if (*vnet_hdr) {
	if (features & IFF_VNET_HDR) {
	*vnet_hdr = 1;
	ifr.ifr_flags \|= IFF_VNET_HDR;
	} else {
	*vnet_hdr = 0;
	}

	if (vnet_hdr_required && !*vnet_hdr) {
	error_setg(errp, "vnet_hdr=1 requested, but no kernel "
	"support for IFF_VNET_HDR available");
	close(fd);
	return -1;
	}
	/*
	* Make sure vnet header size has the default value: for a persistent
	* tap it might have been modified e.g. by another instance of qemu.
	* Ignore errors since old kernels do not support this ioctl: in this
	* case the header size implicitly has the correct value.
	*/
	ioctl(fd, TUNSETVNETHDRSZ, &len);
	}

	if (mq_required) {
	if (!(features & IFF_MULTI_QUEUE)) {
	error_setg(errp, "multiqueue required, but no kernel "
	"support for IFF_MULTI_QUEUE available");
	close(fd);
	return -1;
	} else {
	ifr.ifr_flags \|= IFF_MULTI_QUEUE;
	}
	}

	if (ifname[0] != '\0')
	pstrcpy(ifr.ifr_name, IFNAMSIZ, ifname);
	else
	pstrcpy(ifr.ifr_name, IFNAMSIZ, "tap%d");
	ret = ioctl(fd, TUNSETIFF, (void *) &ifr);
	if (ret != 0) {
	if (ifname[0] != '\0') {
	error_setg_errno(errp, errno, "could not configure %s (%s)",
	PATH_NET_TUN, ifr.ifr_name);
	} else {
	error_setg_errno(errp, errno, "could not configure %s",
	PATH_NET_TUN);
	}
	close(fd);
	return -1;
	}
	pstrcpy(ifname, ifname_size, ifr.ifr_name);
	fcntl(fd, F_SETFL, O_NONBLOCK);
	return fd;
	}

	/* sndbuf implements a kind of flow control for tap.
	* Unfortunately when it's enabled, and packets are sent
	* to other guests on the same host, the receiver
	* can lock up the transmitter indefinitely.
	*
	* To avoid packet loss, sndbuf should be set to a value lower than the tx
	* queue capacity of any destination network interface.
	* Ethernet NICs generally have txqueuelen=1000, so 1Mb is
	* a good value, given a 1500 byte MTU.
	*/
	#define TAP_DEFAULT_SNDBUF 0

	void tap_set_sndbuf(int fd, const NetdevTapOptions tap, Error *errp)
	{
	int sndbuf;

	sndbuf = !tap->has_sndbuf ? TAP_DEFAULT_SNDBUF :
	tap->sndbuf > INT_MAX ? INT_MAX :
	tap->sndbuf;

	if (!sndbuf) {
	sndbuf = INT_MAX;
	}

	if (ioctl(fd, TUNSETSNDBUF, &sndbuf) == -1 && tap->has_sndbuf) {
	error_setg_errno(errp, errno, "TUNSETSNDBUF ioctl failed");
	}
	}

	int tap_probe_vnet_hdr(int fd)
	{
	struct ifreq ifr;

	if (ioctl(fd, TUNGETIFF, &ifr) != 0) {
	error_report("TUNGETIFF ioctl() failed: %s", strerror(errno));
	return 0;
	}

	return ifr.ifr_flags & IFF_VNET_HDR;
	}

	int tap_probe_has_ufo(int fd)
	{
	unsigned offload;

	offload = TUN_F_CSUM \| TUN_F_UFO;

	if (ioctl(fd, TUNSETOFFLOAD, offload) < 0)
	return 0;

	return 1;
	}

	/* Verify that we can assign given length */
	int tap_probe_vnet_hdr_len(int fd, int len)
	{
	int orig;
	if (ioctl(fd, TUNGETVNETHDRSZ, &orig) == -1) {
	return 0;
	}
	if (ioctl(fd, TUNSETVNETHDRSZ, &len) == -1) {
	return 0;
	}
	/* Restore original length: we can't handle failure. */
	if (ioctl(fd, TUNSETVNETHDRSZ, &orig) == -1) {
	fprintf(stderr, "TUNGETVNETHDRSZ ioctl() failed: %s. Exiting.\n",
	strerror(errno));
	abort();
	return -errno;
	}
	return 1;
	}

	void tap_fd_set_vnet_hdr_len(int fd, int len)
	{
	if (ioctl(fd, TUNSETVNETHDRSZ, &len) == -1) {
	fprintf(stderr, "TUNSETVNETHDRSZ ioctl() failed: %s. Exiting.\n",
	strerror(errno));
	abort();
	}
	}

	int tap_fd_set_vnet_le(int fd, int is_le)
	{
	int arg = is_le ? 1 : 0;

	if (!ioctl(fd, TUNSETVNETLE, &arg)) {
	return 0;
	}

	/* Check if our kernel supports TUNSETVNETLE */
	if (errno == EINVAL) {
	return -errno;
	}

	error_report("TUNSETVNETLE ioctl() failed: %s.\n", strerror(errno));
	abort();
	}

	int tap_fd_set_vnet_be(int fd, int is_be)
	{
	int arg = is_be ? 1 : 0;

	if (!ioctl(fd, TUNSETVNETBE, &arg)) {
	return 0;
	}

	/* Check if our kernel supports TUNSETVNETBE */
	if (errno == EINVAL) {
	return -errno;
	}

	error_report("TUNSETVNETBE ioctl() failed: %s.\n", strerror(errno));
	abort();
	}

	void tap_fd_set_offload(int fd, int csum, int tso4,
	int tso6, int ecn, int ufo)
	{
	unsigned int offload = 0;

	/* Check if our kernel supports TUNSETOFFLOAD */
	if (ioctl(fd, TUNSETOFFLOAD, 0) != 0 && errno == EINVAL) {
	return;
	}

	if (csum) {
	offload \|= TUN_F_CSUM;
	if (tso4)
	offload \|= TUN_F_TSO4;
	if (tso6)
	offload \|= TUN_F_TSO6;
	if ((tso4 \|\| tso6) && ecn)
	offload \|= TUN_F_TSO_ECN;
	if (ufo)
	offload \|= TUN_F_UFO;
	}

	if (ioctl(fd, TUNSETOFFLOAD, offload) != 0) {
	offload &= ~TUN_F_UFO;
	if (ioctl(fd, TUNSETOFFLOAD, offload) != 0) {
	fprintf(stderr, "TUNSETOFFLOAD ioctl() failed: %s\n",
	strerror(errno));
	}
	}
	}

	/* Enable a specific queue of tap. */
	int tap_fd_enable(int fd)
	{
	struct ifreq ifr;
	int ret;

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

	ifr.ifr_flags = IFF_ATTACH_QUEUE;
	ret = ioctl(fd, TUNSETQUEUE, (void *) &ifr);

	if (ret != 0) {
	error_report("could not enable queue");
	}

	return ret;
	}

	/* Disable a specific queue of tap/ */
	int tap_fd_disable(int fd)
	{
	struct ifreq ifr;
	int ret;

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

	ifr.ifr_flags = IFF_DETACH_QUEUE;
	ret = ioctl(fd, TUNSETQUEUE, (void *) &ifr);

	if (ret != 0) {
	error_report("could not disable queue");
	}

	return ret;
	}

	int tap_fd_get_ifname(int fd, char *ifname)
	{
	struct ifreq ifr;

	if (ioctl(fd, TUNGETIFF, &ifr) != 0) {
	error_report("TUNGETIFF ioctl() failed: %s",
	strerror(errno));
	return -1;
	}

	pstrcpy(ifname, sizeof(ifr.ifr_name), ifr.ifr_name);
	return 0;
	}