src/drivers/linux/tap.c

   1 /*
   2  * Copyright (C) 2010 Piotr Jaroszyński <p.jaroszynski@gmail.com>
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public License as
   6  * published by the Free Software Foundation; either version 2 of the
   7  * License, or any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful, but
  10  * WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write to the Free Software
  16  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  17  */
  18
  19 #include <errno.h>
  20 #include <string.h>
  21 #include <stdio.h>
  22 #include <linux_api.h>
  23 #include <ipxe/list.h>
  24 #include <ipxe/linux.h>
  25 #include <ipxe/malloc.h>
  26 #include <ipxe/device.h>
  27 #include <ipxe/netdevice.h>
  28 #include <ipxe/iobuf.h>
  29 #include <ipxe/ethernet.h>
  30 #include <ipxe/settings.h>
  31 #include <ipxe/socket.h>
  32
  33 /* This hack prevents pre-2.6.32 headers from redefining struct sockaddr */
  34 #define __GLIBC__ 2
  35 #include <linux/socket.h>
  36 #undef __GLIBC__
  37 #include <linux/if.h>
  38 #include <linux/if_ether.h>
  39 #include <linux/if_tun.h>
  40
  41 #define RX_BUF_SIZE 1536
  42
  43 /** @file
  44  *
  45  * The TAP driver.
  46  *
  47  * The TAP is a Virtual Ethernet network device.
  48  */
  49
  50 struct tap_nic {
  51         /** Tap interface name */
  52         char * interface;
  53         /** File descriptor of the opened tap device */
  54         int fd;
  55 };
  56
  57 /** Open the TAP device */
  58 static int tap_open(struct net_device * netdev)
  59 {
  60         struct tap_nic * nic = netdev->priv;
  61         struct ifreq ifr;
  62         int ret;
  63
  64         nic->fd = linux_open("/dev/net/tun", O_RDWR);
  65         if (nic->fd < 0) {
  66                 DBGC(nic, "tap %p open('/dev/net/tun') = %d (%s)\n", nic, nic->fd, linux_strerror(linux_errno));
  67                 return nic->fd;
  68         }
  69
  70         memset(&ifr, 0, sizeof(ifr));
  71         /* IFF_NO_PI for no extra packet information */
  72         ifr.ifr_flags = IFF_TAP | IFF_NO_PI;
  73         strncpy(ifr.ifr_name, nic->interface, IFNAMSIZ);
  74         DBGC(nic, "tap %p interface = '%s'\n", nic, nic->interface);
  75
  76         ret = linux_ioctl(nic->fd, TUNSETIFF, &ifr);
  77
  78         if (ret != 0) {
  79                 DBGC(nic, "tap %p ioctl(%d, ...) = %d (%s)\n", nic, nic->fd, ret, linux_strerror(linux_errno));
  80                 linux_close(nic->fd);
  81                 return ret;
  82         }
  83
  84         /* Set nonblocking mode to make tap_poll easier */
  85         ret = linux_fcntl(nic->fd, F_SETFL, O_NONBLOCK);
  86
  87         if (ret != 0) {
  88                 DBGC(nic, "tap %p fcntl(%d, ...) = %d (%s)\n", nic, nic->fd, ret, linux_strerror(linux_errno));
  89                 linux_close(nic->fd);
  90                 return ret;
  91         }
  92
  93         return 0;
  94 }
  95
  96 /** Close the TAP device */
  97 static void tap_close(struct net_device *netdev)
  98 {
  99         struct tap_nic * nic = netdev->priv;
 100         linux_close(nic->fd);
 101 }
 102
 103 /**
 104  * Transmit an ethernet packet.
 105  *
 106  * The packet can be written to the TAP device and marked as complete immediately.
 107  */
 108 static int tap_transmit(struct net_device *netdev, struct io_buffer *iobuf)
 109 {
 110         struct tap_nic * nic = netdev->priv;
 111         int rc;
 112
 113         /* Pad and align packet */
 114         iob_pad(iobuf, ETH_ZLEN);
 115
 116         rc = linux_write(nic->fd, iobuf->data, iobuf->tail - iobuf->data);
 117         DBGC2(nic, "tap %p wrote %d bytes\n", nic, rc);
 118         netdev_tx_complete(netdev, iobuf);
 119
 120         return 0;
 121 }
 122
 123 /** Poll for new packets */
 124 static void tap_poll(struct net_device *netdev)
 125 {
 126         struct tap_nic * nic = netdev->priv;
 127         struct pollfd pfd;
 128         struct io_buffer * iobuf;
 129         int r;
 130
 131         pfd.fd = nic->fd;
 132         pfd.events = POLLIN;
 133         if (linux_poll(&pfd, 1, 0) == -1) {
 134                 DBGC(nic, "tap %p poll failed (%s)\n", nic, linux_strerror(linux_errno));
 135                 return;
 136         }
 137         if ((pfd.revents & POLLIN) == 0)
 138                 return;
 139
 140         /* At this point we know there is at least one new packet to be read */
 141
 142         iobuf = alloc_iob(RX_BUF_SIZE);
 143         if (! iobuf)
 144                 goto allocfail;
 145
 146         while ((r = linux_read(nic->fd, iobuf->data, RX_BUF_SIZE)) > 0) {
 147                 DBGC2(nic, "tap %p read %d bytes\n", nic, r);
 148
 149                 iob_put(iobuf, r);
 150                 netdev_rx(netdev, iobuf);
 151
 152                 iobuf = alloc_iob(RX_BUF_SIZE);
 153                 if (! iobuf)
 154                         goto allocfail;
 155         }
 156
 157         free_iob(iobuf);
 158         return;
 159
 160 allocfail:
 161         DBGC(nic, "tap %p alloc_iob failed\n", nic);
 162 }
 163
 164 /**
 165  * Set irq.
 166  *
 167  * Not used on linux, provide a dummy implementation.
 168  */
 169 static void tap_irq(struct net_device *netdev, int enable)
 170 {
 171         struct tap_nic *nic = netdev->priv;
 172
 173         DBGC(nic, "tap %p irq enable = %d\n", nic, enable);
 174 }
 175
 176 /** Tap operations */
 177 static struct net_device_operations tap_operations = {
 178         .open           = tap_open,
 179         .close          = tap_close,
 180         .transmit       = tap_transmit,
 181         .poll           = tap_poll,
 182         .irq            = tap_irq,
 183 };
 184
 185 /** Handle a device request for the tap driver */
 186 static int tap_probe(struct linux_device *device, struct linux_device_request *request)
 187 {
 188         struct linux_setting *if_setting;
 189         struct net_device *netdev;
 190         struct tap_nic *nic;
 191         int rc;
 192
 193         netdev = alloc_etherdev(sizeof(*nic));
 194         if (! netdev)
 195                 return -ENOMEM;
 196
 197         netdev_init(netdev, &tap_operations);
 198         nic = netdev->priv;
 199         linux_set_drvdata(device, netdev);
 200         netdev->dev = &device->dev;
 201         memset(nic, 0, sizeof(*nic));
 202
 203         /* Look for the mandatory if setting */
 204         if_setting = linux_find_setting("if", &request->settings);
 205
 206         /* No if setting */
 207         if (! if_setting) {
 208                 printf("tap missing a mandatory if setting\n");
 209                 rc = -EINVAL;
 210                 goto err_settings;
 211         }
 212
 213         nic->interface = if_setting->value;
 214         snprintf ( device->dev.name, sizeof ( device->dev.name ), "%s",
 215                    nic->interface );
 216         device->dev.desc.bus_type = BUS_TYPE_TAP;
 217         if_setting->applied = 1;
 218
 219         /* Apply rest of the settings */
 220         linux_apply_settings(&request->settings, &netdev->settings.settings);
 221
 222         /* Register network device */
 223         if ((rc = register_netdev(netdev)) != 0)
 224                 goto err_register;
 225
 226         netdev_link_up(netdev);
 227
 228         return 0;
 229
 230 err_settings:
 231         unregister_netdev(netdev);
 232 err_register:
 233         netdev_nullify(netdev);
 234         netdev_put(netdev);
 235         return rc;
 236 }
 237
 238 /** Remove the device */
 239 static void tap_remove(struct linux_device *device)
 240 {
 241         struct net_device *netdev = linux_get_drvdata(device);
 242         unregister_netdev(netdev);
 243         netdev_nullify(netdev);
 244         netdev_put(netdev);
 245 }
 246
 247 /** Tap linux_driver */
 248 struct linux_driver tap_driver __linux_driver = {
 249         .name = "tap",
 250         .probe = tap_probe,
 251         .remove = tap_remove,
 252         .can_probe = 1,
 253 };