xref: /qemu/net/tap.c (revision 5281d757efa6e40d74ce124be048b08d43887555)

/*
 * 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 "net/tap.h"

#include "config-host.h"

#include <signal.h>
#include <sys/ioctl.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include <net/if.h>

#include "net.h"
#include "sysemu.h"
#include "qemu-char.h"
#include "qemu-common.h"

#ifdef __linux__
#include "net/tap-linux.h"
#endif

#ifdef __NetBSD__
#include <net/if_tap.h>
#endif

#ifdef CONFIG_BSD
#if defined(__FreeBSD__) || defined(__DragonFly__)
#include <libutil.h>
#else
#include <util.h>
#endif
#elif defined (__GLIBC__) && defined (__FreeBSD_kernel__)
#include <freebsd/stdlib.h>
#endif

#if defined(__OpenBSD__)
#include <util.h>
#endif

#ifdef __sun__
#include <sys/stat.h>
#include <sys/ethernet.h>
#include <sys/sockio.h>
#include <netinet/arp.h>
#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/ip.h>
#include <netinet/ip_icmp.h> // must come after ip.h
#include <netinet/udp.h>
#include <netinet/tcp.h>
#include <net/if.h>
#include <syslog.h>
#include <stropts.h>
#endif

#if !defined(_AIX)

/* Maximum GSO packet size (64k) plus plenty of room for
 * the ethernet and virtio_net headers
 */
#define TAP_BUFSIZE (4096 + 65536)

typedef struct TAPState {
    VLANClientState *vc;
    int fd;
    char down_script[1024];
    char down_script_arg[128];
    uint8_t buf[TAP_BUFSIZE];
    unsigned int read_poll : 1;
    unsigned int write_poll : 1;
    unsigned int has_vnet_hdr : 1;
    unsigned int using_vnet_hdr : 1;
    unsigned int has_ufo: 1;
} TAPState;

static int launch_script(const char *setup_script, const char *ifname, int fd);

static int tap_can_send(void *opaque);
static void tap_send(void *opaque);
static void tap_writable(void *opaque);

static void tap_update_fd_handler(TAPState *s)
{
    qemu_set_fd_handler2(s->fd,
                         s->read_poll  ? tap_can_send : NULL,
                         s->read_poll  ? tap_send     : NULL,
                         s->write_poll ? tap_writable : NULL,
                         s);
}

static void tap_read_poll(TAPState *s, int enable)
{
    s->read_poll = !!enable;
    tap_update_fd_handler(s);
}

static void tap_write_poll(TAPState *s, int enable)
{
    s->write_poll = !!enable;
    tap_update_fd_handler(s);
}

static void tap_writable(void *opaque)
{
    TAPState *s = opaque;

    tap_write_poll(s, 0);

    qemu_flush_queued_packets(s->vc);
}

static ssize_t tap_write_packet(TAPState *s, const struct iovec *iov, int iovcnt)
{
    ssize_t len;

    do {
        len = writev(s->fd, iov, iovcnt);
    } while (len == -1 && errno == EINTR);

    if (len == -1 && errno == EAGAIN) {
        tap_write_poll(s, 1);
        return 0;
    }

    return len;
}

static ssize_t tap_receive_iov(VLANClientState *vc, const struct iovec *iov,
                               int iovcnt)
{
    TAPState *s = vc->opaque;
    const struct iovec *iovp = iov;
    struct iovec iov_copy[iovcnt + 1];
    struct virtio_net_hdr hdr = { 0, };

    if (s->has_vnet_hdr && !s->using_vnet_hdr) {
        iov_copy[0].iov_base = &hdr;
        iov_copy[0].iov_len =  sizeof(hdr);
        memcpy(&iov_copy[1], iov, iovcnt * sizeof(*iov));
        iovp = iov_copy;
        iovcnt++;
    }

    return tap_write_packet(s, iovp, iovcnt);
}

static ssize_t tap_receive_raw(VLANClientState *vc, const uint8_t *buf, size_t size)
{
    TAPState *s = vc->opaque;
    struct iovec iov[2];
    int iovcnt = 0;
    struct virtio_net_hdr hdr = { 0, };

    if (s->has_vnet_hdr) {
        iov[iovcnt].iov_base = &hdr;
        iov[iovcnt].iov_len  = sizeof(hdr);
        iovcnt++;
    }

    iov[iovcnt].iov_base = (char *)buf;
    iov[iovcnt].iov_len  = size;
    iovcnt++;

    return tap_write_packet(s, iov, iovcnt);
}

static ssize_t tap_receive(VLANClientState *vc, const uint8_t *buf, size_t size)
{
    TAPState *s = vc->opaque;
    struct iovec iov[1];

    if (s->has_vnet_hdr && !s->using_vnet_hdr) {
        return tap_receive_raw(vc, buf, size);
    }

    iov[0].iov_base = (char *)buf;
    iov[0].iov_len  = size;

    return tap_write_packet(s, iov, 1);
}

static int tap_can_send(void *opaque)
{
    TAPState *s = opaque;

    return qemu_can_send_packet(s->vc);
}

#ifdef __sun__
static ssize_t tap_read_packet(int tapfd, uint8_t *buf, int maxlen)
{
    struct strbuf sbuf;
    int f = 0;

    sbuf.maxlen = maxlen;
    sbuf.buf = (char *)buf;

    return getmsg(tapfd, NULL, &sbuf, &f) >= 0 ? sbuf.len : -1;
}
#else
static ssize_t tap_read_packet(int tapfd, uint8_t *buf, int maxlen)
{
    return read(tapfd, buf, maxlen);
}
#endif

static void tap_send_completed(VLANClientState *vc, ssize_t len)
{
    TAPState *s = vc->opaque;
    tap_read_poll(s, 1);
}

static void tap_send(void *opaque)
{
    TAPState *s = opaque;
    int size;

    do {
        uint8_t *buf = s->buf;

        size = tap_read_packet(s->fd, s->buf, sizeof(s->buf));
        if (size <= 0) {
            break;
        }

        if (s->has_vnet_hdr && !s->using_vnet_hdr) {
            buf  += sizeof(struct virtio_net_hdr);
            size -= sizeof(struct virtio_net_hdr);
        }

        size = qemu_send_packet_async(s->vc, buf, size, tap_send_completed);
        if (size == 0) {
            tap_read_poll(s, 0);
        }
    } while (size > 0);
}

/* 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 default, given a 1500 byte MTU.
 */
#define TAP_DEFAULT_SNDBUF 1024*1024

static int tap_set_sndbuf(TAPState *s, QemuOpts *opts)
{
    int sndbuf;

    sndbuf = qemu_opt_get_size(opts, "sndbuf", TAP_DEFAULT_SNDBUF);
    if (!sndbuf) {
        sndbuf = INT_MAX;
    }

    if (ioctl(s->fd, TUNSETSNDBUF, &sndbuf) == -1 && qemu_opt_get(opts, "sndbuf")) {
        qemu_error("TUNSETSNDBUF ioctl failed: %s\n", strerror(errno));
        return -1;
    }
    return 0;
}

int tap_has_ufo(VLANClientState *vc)
{
    TAPState *s = vc->opaque;

    assert(vc->type == NET_CLIENT_TYPE_TAP);

    return s->has_ufo;
}

int tap_has_vnet_hdr(VLANClientState *vc)
{
    TAPState *s = vc->opaque;

    assert(vc->type == NET_CLIENT_TYPE_TAP);

    return s->has_vnet_hdr;
}

void tap_using_vnet_hdr(VLANClientState *vc, int using_vnet_hdr)
{
    TAPState *s = vc->opaque;

    using_vnet_hdr = using_vnet_hdr != 0;

    assert(vc->type == NET_CLIENT_TYPE_TAP);
    assert(s->has_vnet_hdr == using_vnet_hdr);

    s->using_vnet_hdr = using_vnet_hdr;
}

static int tap_probe_vnet_hdr(int fd)
{
    struct ifreq ifr;

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

    return ifr.ifr_flags & IFF_VNET_HDR;
}

void tap_set_offload(VLANClientState *vc, int csum, int tso4,
                     int tso6, int ecn, int ufo)
{
    TAPState *s = vc->opaque;
    unsigned int offload = 0;

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

static void tap_cleanup(VLANClientState *vc)
{
    TAPState *s = vc->opaque;

    qemu_purge_queued_packets(vc);

    if (s->down_script[0])
        launch_script(s->down_script, s->down_script_arg, s->fd);

    tap_read_poll(s, 0);
    tap_write_poll(s, 0);
    close(s->fd);
    qemu_free(s);
}

/* fd support */

static TAPState *net_tap_fd_init(VLANState *vlan,
                                 const char *model,
                                 const char *name,
                                 int fd,
                                 int vnet_hdr)
{
    TAPState *s;
    unsigned int offload;

    s = qemu_mallocz(sizeof(TAPState));
    s->fd = fd;
    s->has_vnet_hdr = vnet_hdr != 0;
    s->using_vnet_hdr = 0;
    s->vc = qemu_new_vlan_client(NET_CLIENT_TYPE_TAP,
                                 vlan, NULL, model, name, NULL,
                                 tap_receive, tap_receive_raw,
                                 tap_receive_iov, tap_cleanup, s);
    s->has_ufo = 0;
    /* Check if tap supports UFO */
    offload = TUN_F_CSUM | TUN_F_UFO;
    if (ioctl(s->fd, TUNSETOFFLOAD, offload) == 0)
       s->has_ufo = 1;
    tap_set_offload(s->vc, 0, 0, 0, 0, 0);
    tap_read_poll(s, 1);
    return s;
}

#if defined (CONFIG_BSD) || defined (__FreeBSD_kernel__)
static int tap_open(char *ifname, int ifname_size,
                    int *vnet_hdr, int vnet_hdr_required)
{
    int fd;
    char *dev;
    struct stat s;

    TFR(fd = open("/dev/tap", O_RDWR));
    if (fd < 0) {
        fprintf(stderr, "warning: could not open /dev/tap: no virtual network emulation\n");
        return -1;
    }

    fstat(fd, &s);
    dev = devname(s.st_rdev, S_IFCHR);
    pstrcpy(ifname, ifname_size, dev);

    fcntl(fd, F_SETFL, O_NONBLOCK);
    return fd;
}
#elif defined(__sun__)
#define TUNNEWPPA       (('T'<<16) | 0x0001)
/*
 * Allocate TAP device, returns opened fd.
 * Stores dev name in the first arg(must be large enough).
 */
static int tap_alloc(char *dev, size_t dev_size)
{
    int tap_fd, if_fd, ppa = -1;
    static int ip_fd = 0;
    char *ptr;

    static int arp_fd = 0;
    int ip_muxid, arp_muxid;
    struct strioctl  strioc_if, strioc_ppa;
    int link_type = I_PLINK;;
    struct lifreq ifr;
    char actual_name[32] = "";

    memset(&ifr, 0x0, sizeof(ifr));

    if( *dev ){
       ptr = dev;
       while( *ptr && !qemu_isdigit((int)*ptr) ) ptr++;
       ppa = atoi(ptr);
    }

    /* Check if IP device was opened */
    if( ip_fd )
       close(ip_fd);

    TFR(ip_fd = open("/dev/udp", O_RDWR, 0));
    if (ip_fd < 0) {
       syslog(LOG_ERR, "Can't open /dev/ip (actually /dev/udp)");
       return -1;
    }

    TFR(tap_fd = open("/dev/tap", O_RDWR, 0));
    if (tap_fd < 0) {
       syslog(LOG_ERR, "Can't open /dev/tap");
       return -1;
    }

    /* Assign a new PPA and get its unit number. */
    strioc_ppa.ic_cmd = TUNNEWPPA;
    strioc_ppa.ic_timout = 0;
    strioc_ppa.ic_len = sizeof(ppa);
    strioc_ppa.ic_dp = (char *)&ppa;
    if ((ppa = ioctl (tap_fd, I_STR, &strioc_ppa)) < 0)
       syslog (LOG_ERR, "Can't assign new interface");

    TFR(if_fd = open("/dev/tap", O_RDWR, 0));
    if (if_fd < 0) {
       syslog(LOG_ERR, "Can't open /dev/tap (2)");
       return -1;
    }
    if(ioctl(if_fd, I_PUSH, "ip") < 0){
       syslog(LOG_ERR, "Can't push IP module");
       return -1;
    }

    if (ioctl(if_fd, SIOCGLIFFLAGS, &ifr) < 0)
	syslog(LOG_ERR, "Can't get flags\n");

    snprintf (actual_name, 32, "tap%d", ppa);
    pstrcpy(ifr.lifr_name, sizeof(ifr.lifr_name), actual_name);

    ifr.lifr_ppa = ppa;
    /* Assign ppa according to the unit number returned by tun device */

    if (ioctl (if_fd, SIOCSLIFNAME, &ifr) < 0)
        syslog (LOG_ERR, "Can't set PPA %d", ppa);
    if (ioctl(if_fd, SIOCGLIFFLAGS, &ifr) <0)
        syslog (LOG_ERR, "Can't get flags\n");
    /* Push arp module to if_fd */
    if (ioctl (if_fd, I_PUSH, "arp") < 0)
        syslog (LOG_ERR, "Can't push ARP module (2)");

    /* Push arp module to ip_fd */
    if (ioctl (ip_fd, I_POP, NULL) < 0)
        syslog (LOG_ERR, "I_POP failed\n");
    if (ioctl (ip_fd, I_PUSH, "arp") < 0)
        syslog (LOG_ERR, "Can't push ARP module (3)\n");
    /* Open arp_fd */
    TFR(arp_fd = open ("/dev/tap", O_RDWR, 0));
    if (arp_fd < 0)
       syslog (LOG_ERR, "Can't open %s\n", "/dev/tap");

    /* Set ifname to arp */
    strioc_if.ic_cmd = SIOCSLIFNAME;
    strioc_if.ic_timout = 0;
    strioc_if.ic_len = sizeof(ifr);
    strioc_if.ic_dp = (char *)&ifr;
    if (ioctl(arp_fd, I_STR, &strioc_if) < 0){
        syslog (LOG_ERR, "Can't set ifname to arp\n");
    }

    if((ip_muxid = ioctl(ip_fd, I_LINK, if_fd)) < 0){
       syslog(LOG_ERR, "Can't link TAP device to IP");
       return -1;
    }

    if ((arp_muxid = ioctl (ip_fd, link_type, arp_fd)) < 0)
        syslog (LOG_ERR, "Can't link TAP device to ARP");

    close (if_fd);

    memset(&ifr, 0x0, sizeof(ifr));
    pstrcpy(ifr.lifr_name, sizeof(ifr.lifr_name), actual_name);
    ifr.lifr_ip_muxid  = ip_muxid;
    ifr.lifr_arp_muxid = arp_muxid;

    if (ioctl (ip_fd, SIOCSLIFMUXID, &ifr) < 0)
    {
      ioctl (ip_fd, I_PUNLINK , arp_muxid);
      ioctl (ip_fd, I_PUNLINK, ip_muxid);
      syslog (LOG_ERR, "Can't set multiplexor id");
    }

    snprintf(dev, dev_size, "tap%d", ppa);
    return tap_fd;
}

static int tap_open(char *ifname, int ifname_size,
                    int *vnet_hdr, int vnet_hdr_required)
{
    char  dev[10]="";
    int fd;
    if( (fd = tap_alloc(dev, sizeof(dev))) < 0 ){
       fprintf(stderr, "Cannot allocate TAP device\n");
       return -1;
    }
    pstrcpy(ifname, ifname_size, dev);
    fcntl(fd, F_SETFL, O_NONBLOCK);
    return fd;
}
#elif defined (_AIX)
static int tap_open(char *ifname, int ifname_size,
                    int *vnet_hdr, int vnet_hdr_required)
{
    fprintf (stderr, "no tap on AIX\n");
    return -1;
}
#else
static int tap_open(char *ifname, int ifname_size,
                    int *vnet_hdr, int vnet_hdr_required)
{
    struct ifreq ifr;
    int fd, ret;

    TFR(fd = open("/dev/net/tun", O_RDWR));
    if (fd < 0) {
        fprintf(stderr, "warning: could not open /dev/net/tun: no virtual network emulation\n");
        return -1;
    }
    memset(&ifr, 0, sizeof(ifr));
    ifr.ifr_flags = IFF_TAP | IFF_NO_PI;

    if (*vnet_hdr) {
        unsigned int features;

        if (ioctl(fd, TUNGETFEATURES, &features) == 0 &&
            features & IFF_VNET_HDR) {
            *vnet_hdr = 1;
            ifr.ifr_flags |= IFF_VNET_HDR;
        }

        if (vnet_hdr_required && !*vnet_hdr) {
            qemu_error("vnet_hdr=1 requested, but no kernel "
                       "support for IFF_VNET_HDR available");
            close(fd);
            return -1;
        }
    }

    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) {
        fprintf(stderr, "warning: could not configure /dev/net/tun: no virtual network emulation\n");
        close(fd);
        return -1;
    }
    pstrcpy(ifname, ifname_size, ifr.ifr_name);
    fcntl(fd, F_SETFL, O_NONBLOCK);
    return fd;
}
#endif

static int launch_script(const char *setup_script, const char *ifname, int fd)
{
    sigset_t oldmask, mask;
    int pid, status;
    char *args[3];
    char **parg;

    sigemptyset(&mask);
    sigaddset(&mask, SIGCHLD);
    sigprocmask(SIG_BLOCK, &mask, &oldmask);

    /* try to launch network script */
    pid = fork();
    if (pid == 0) {
        int open_max = sysconf(_SC_OPEN_MAX), i;

        for (i = 0; i < open_max; i++) {
            if (i != STDIN_FILENO &&
                i != STDOUT_FILENO &&
                i != STDERR_FILENO &&
                i != fd) {
                close(i);
            }
        }
        parg = args;
        *parg++ = (char *)setup_script;
        *parg++ = (char *)ifname;
        *parg++ = NULL;
        execv(setup_script, args);
        _exit(1);
    } else if (pid > 0) {
        while (waitpid(pid, &status, 0) != pid) {
            /* loop */
        }
        sigprocmask(SIG_SETMASK, &oldmask, NULL);

        if (WIFEXITED(status) && WEXITSTATUS(status) == 0) {
            return 0;
        }
    }
    fprintf(stderr, "%s: could not launch network script\n", setup_script);
    return -1;
}

static int net_tap_init(QemuOpts *opts, int *vnet_hdr)
{
    int fd, vnet_hdr_required;
    char ifname[128] = {0,};
    const char *setup_script;

    if (qemu_opt_get(opts, "ifname")) {
        pstrcpy(ifname, sizeof(ifname), qemu_opt_get(opts, "ifname"));
    }

    *vnet_hdr = qemu_opt_get_bool(opts, "vnet_hdr", 1);
    if (qemu_opt_get(opts, "vnet_hdr")) {
        vnet_hdr_required = *vnet_hdr;
    } else {
        vnet_hdr_required = 0;
    }

    TFR(fd = tap_open(ifname, sizeof(ifname), vnet_hdr, vnet_hdr_required));
    if (fd < 0) {
        return -1;
    }

    setup_script = qemu_opt_get(opts, "script");
    if (setup_script &&
        setup_script[0] != '\0' &&
        strcmp(setup_script, "no") != 0 &&
        launch_script(setup_script, ifname, fd)) {
        close(fd);
        return -1;
    }

    qemu_opt_set(opts, "ifname", ifname);

    return fd;
}

int net_init_tap(QemuOpts *opts, Monitor *mon, const char *name, VLANState *vlan)
{
    TAPState *s;
    int fd, vnet_hdr;

    if (qemu_opt_get(opts, "fd")) {
        if (qemu_opt_get(opts, "ifname") ||
            qemu_opt_get(opts, "script") ||
            qemu_opt_get(opts, "downscript") ||
            qemu_opt_get(opts, "vnet_hdr")) {
            qemu_error("ifname=, script=, downscript= and vnet_hdr= is invalid with fd=\n");
            return -1;
        }

        fd = net_handle_fd_param(mon, qemu_opt_get(opts, "fd"));
        if (fd == -1) {
            return -1;
        }

        fcntl(fd, F_SETFL, O_NONBLOCK);

        vnet_hdr = tap_probe_vnet_hdr(fd);
    } else {
        if (!qemu_opt_get(opts, "script")) {
            qemu_opt_set(opts, "script", DEFAULT_NETWORK_SCRIPT);
        }

        if (!qemu_opt_get(opts, "downscript")) {
            qemu_opt_set(opts, "downscript", DEFAULT_NETWORK_DOWN_SCRIPT);
        }

        fd = net_tap_init(opts, &vnet_hdr);
    }

    s = net_tap_fd_init(vlan, "tap", name, fd, vnet_hdr);
    if (!s) {
        close(fd);
        return -1;
    }

    if (tap_set_sndbuf(s, opts) < 0) {
        return -1;
    }

    if (qemu_opt_get(opts, "fd")) {
        snprintf(s->vc->info_str, sizeof(s->vc->info_str), "fd=%d", fd);
    } else {
        const char *ifname, *script, *downscript;

        ifname     = qemu_opt_get(opts, "ifname");
        script     = qemu_opt_get(opts, "script");
        downscript = qemu_opt_get(opts, "downscript");

        snprintf(s->vc->info_str, sizeof(s->vc->info_str),
                 "ifname=%s,script=%s,downscript=%s",
                 ifname, script, downscript);

        if (strcmp(downscript, "no") != 0) {
            snprintf(s->down_script, sizeof(s->down_script), "%s", downscript);
            snprintf(s->down_script_arg, sizeof(s->down_script_arg), "%s", ifname);
        }
    }

    if (vlan) {
        vlan->nb_host_devs++;
    }

    return 0;
}

#endif /* !defined(_AIX) */