af_packet.c

Go to the documentation of this file.

/*
 * Copyright (C) 2016 David Decotigny <ddecotig@gmail.com>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2 of the
 * License, or any later version.
 *
 * This program 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
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 */
 
#include <errno.h>
#include <string.h>
#include <stdio.h>
#include <ipxe/linux_api.h>
#include <ipxe/list.h>
#include <ipxe/linux.h>
#include <ipxe/malloc.h>
#include <ipxe/device.h>
#include <ipxe/netdevice.h>
#include <ipxe/iobuf.h>
#include <ipxe/ethernet.h>
#include <ipxe/settings.h>
#include <ipxe/socket.h>
 
/* This hack prevents pre-2.6.32 headers from redefining struct sockaddr */
#define _SYS_SOCKET_H
#define __GLIBC__ 2
#include <linux/socket.h>
#include <linux/if.h>
#include <linux/if_ether.h>
#include <linux/if_packet.h>
#undef __GLIBC__
#include <byteswap.h>
 
/* linux-specifc syscall params */
#define LINUX_AF_PACKET 17
#define LINUX_SOCK_RAW 3
#define LINUX_SIOCGIFINDEX 0x8933
#define LINUX_SIOCGIFHWADDR 0x8927
 
#define RX_BUF_SIZE 1536
 
/** @file
 *
 * The AF_PACKET driver.
 *
 * Bind to an existing linux network interface.
 */
 
struct af_packet_nic {
        /** Linux network interface name */
        char * ifname;
        /** Packet socket descriptor */
        int fd;
        /** ifindex */
        int ifindex;
};
 
/** Open the linux interface */
static int af_packet_nic_open ( struct net_device * netdev )
{
        struct af_packet_nic * nic = netdev->priv;
        struct sockaddr_ll socket_address;
        struct ifreq if_data;
        int ret;
 
        nic->fd = linux_socket(LINUX_AF_PACKET, LINUX_SOCK_RAW,
                               htons(ETH_P_ALL));
        if (nic->fd < 0) {
                DBGC(nic, "af_packet %p socket(AF_PACKET) = %d (%s)\n",
                     nic, nic->fd, linux_strerror(linux_errno));
                return nic->fd;
        }
 
        /* resolve ifindex of ifname */
        memset(&if_data, 0, sizeof(if_data));
        strncpy(if_data.ifr_name, nic->ifname, sizeof(if_data.ifr_name));
        ret = linux_ioctl(nic->fd, LINUX_SIOCGIFINDEX, &if_data);
        if (ret < 0) {
                DBGC(nic, "af_packet %p ioctl(SIOCGIFINDEX) = %d (%s)\n",
                     nic, ret, linux_strerror(linux_errno));
                linux_close(nic->fd);
                return ret;
        }
 
        nic->ifindex = if_data.ifr_ifindex;
 
        /* bind to interface */
        memset(&socket_address, 0, sizeof(socket_address));
        socket_address.sll_family = LINUX_AF_PACKET;
        socket_address.sll_ifindex = nic->ifindex;
        socket_address.sll_protocol = htons(ETH_P_ALL);
        ret = linux_bind(nic->fd, (void *) &socket_address,
                         sizeof(socket_address));
        if (ret == -1) {
                DBGC(nic, "af_packet %p bind() = %d (%s)\n",
                     nic, ret, linux_strerror(linux_errno));
                linux_close(nic->fd);
                return ret;
        }
 
        /* Set nonblocking mode to make af_packet_nic_poll() easier */
        ret = linux_fcntl(nic->fd, F_SETFL, O_NONBLOCK);
        if (ret != 0) {
                DBGC(nic, "af_packet %p fcntl(%d, ...) = %d (%s)\n",
                     nic, nic->fd, ret, linux_strerror(linux_errno));
                linux_close(nic->fd);
                return ret;
        }
 
        return 0;
}
 
/** Close the packet socket */
static void af_packet_nic_close ( struct net_device *netdev )
{
        struct af_packet_nic * nic = netdev->priv;
        linux_close(nic->fd);
}
 
/**
 * Transmit an ethernet packet.
 *
 * The packet can be written to the socket and marked as complete immediately.
 */
static int af_packet_nic_transmit ( struct net_device *netdev,
                                    struct io_buffer *iobuf )
{
        struct af_packet_nic * nic = netdev->priv;
        struct sockaddr_ll socket_address;
        const struct ethhdr * eh;
        int rc;
 
        memset(&socket_address, 0, sizeof(socket_address));
        socket_address.sll_family = LINUX_AF_PACKET;
        socket_address.sll_ifindex = nic->ifindex;
        socket_address.sll_halen = ETH_ALEN;
 
        eh = iobuf->data;
        memcpy(socket_address.sll_addr, eh->h_dest, ETH_ALEN);
 
        rc = linux_sendto(nic->fd, iobuf->data, iobuf->tail - iobuf->data,
                          0, (struct sockaddr *)&socket_address,
                          sizeof(socket_address));
 
        DBGC2(nic, "af_packet %p wrote %d bytes\n", nic, rc);
        netdev_tx_complete(netdev, iobuf);
 
        return 0;
}
 
/** Poll for new packets */
static void af_packet_nic_poll ( struct net_device *netdev )
{
        struct af_packet_nic * nic = netdev->priv;
        struct pollfd pfd;
        struct io_buffer * iobuf;
        int r;
 
        pfd.fd = nic->fd;
        pfd.events = POLLIN;
        if (linux_poll(&pfd, 1, 0) == -1) {
                DBGC(nic, "af_packet %p poll failed (%s)\n",
                     nic, linux_strerror(linux_errno));
                return;
        }
        if ((pfd.revents & POLLIN) == 0)
                return;
 
        /* At this point we know there is at least one new packet to be read */
 
        iobuf = alloc_iob(RX_BUF_SIZE);
        if (! iobuf)
                goto allocfail;
 
        while ((r = linux_read(nic->fd, iobuf->data, RX_BUF_SIZE)) > 0) {
                DBGC2(nic, "af_packet %p read %d bytes\n", nic, r);
 
                iob_put(iobuf, r);
                netdev_rx(netdev, iobuf);
 
                iobuf = alloc_iob(RX_BUF_SIZE);
                if (! iobuf)
                        goto allocfail;
        }
 
        free_iob(iobuf);
        return;
 
allocfail:
        DBGC(nic, "af_packet %p alloc_iob failed\n", nic);
}
 
/**
 * Set irq.
 *
 * Not used on linux, provide a dummy implementation.
 */
static void af_packet_nic_irq ( struct net_device *netdev, int enable )
{
        struct af_packet_nic *nic = netdev->priv;
 
        DBGC(nic, "af_packet %p irq enable = %d\n", nic, enable);
}
 
 
static int af_packet_update_properties ( struct net_device *netdev )
{
        struct af_packet_nic *nic = netdev->priv;
        struct ifreq if_data;
        int ret;
 
        /* retrieve default MAC address */
        int fd = linux_socket(LINUX_AF_PACKET, LINUX_SOCK_RAW, 0);
        if (fd < 0) {
                DBGC(nic, "af_packet %p cannot create raw socket (%s)\n",
                     nic, linux_strerror(linux_errno));
                return fd;
        }
 
        /* retrieve host's MAC address */
        memset(&if_data, 0, sizeof(if_data));
        strncpy(if_data.ifr_name, nic->ifname, sizeof(if_data.ifr_name));
        ret = linux_ioctl(fd, LINUX_SIOCGIFHWADDR, &if_data);
        if (ret < 0) {
                DBGC(nic, "af_packet %p cannot get mac addr (%s)\n",
                     nic, linux_strerror(linux_errno));
                linux_close(fd);
                return ret;
        }
 
        linux_close(fd);
        /* struct sockaddr = { u16 family, u8 pad[14] (equiv. sa_data) }; */
        memcpy(netdev->ll_addr, if_data.ifr_hwaddr.pad, ETH_ALEN);
        return 0;
}
 
/** AF_PACKET operations */
static struct net_device_operations af_packet_nic_operations = {
        .open           = af_packet_nic_open,
        .close          = af_packet_nic_close,
        .transmit       = af_packet_nic_transmit,
        .poll           = af_packet_nic_poll,
        .irq            = af_packet_nic_irq,
};
 
/** Handle a device request for the af_packet driver */
static int af_packet_nic_probe ( struct linux_device *device,
                                 struct linux_device_request *request )
{
        struct linux_setting *if_setting;
        struct net_device *netdev;
        struct af_packet_nic *nic;
        int rc;
 
        netdev = alloc_etherdev(sizeof(*nic));
        if (! netdev)
                return -ENOMEM;
 
        netdev_init(netdev, &af_packet_nic_operations);
        nic = netdev->priv;
        linux_set_drvdata(device, netdev);
        netdev->dev = &device->dev;
 
        memset(nic, 0, sizeof(*nic));
 
        /* Look for the mandatory if setting */
        if_setting = linux_find_setting("if", &request->settings);
 
        /* No if setting */
        if (! if_setting) {
                printf("af_packet missing a mandatory if setting\n");
                rc = -EINVAL;
                goto err_settings;
        }
 
        nic->ifname = if_setting->value;
        snprintf ( device->dev.name, sizeof ( device->dev.name ), "%s",
                   nic->ifname );
        device->dev.desc.bus_type = BUS_TYPE_TAP;
        af_packet_update_properties(netdev);
        if_setting->applied = 1;
 
        /* Apply rest of the settings */
        linux_apply_settings(&request->settings, &netdev->settings.settings);
 
        /* Register network device */
        if ((rc = register_netdev(netdev)) != 0)
                goto err_register;
 
        netdev_link_up(netdev);
 
        return 0;
 
        unregister_netdev(netdev);
err_register:
err_settings:
        netdev_nullify(netdev);
        netdev_put(netdev);
        return rc;
}
 
/** Remove the device */
static void af_packet_nic_remove ( struct linux_device *device )
{
        struct net_device *netdev = linux_get_drvdata(device);
        unregister_netdev(netdev);
        netdev_nullify(netdev);
        netdev_put(netdev);
}
 
/** AF_PACKET linux_driver */
struct linux_driver af_packet_nic_driver __linux_driver = {
        .name = "af_packet",
        .probe = af_packet_nic_probe,
        .remove = af_packet_nic_remove,
};
 
/* Generate build rules */
LINUX_ROM ( "af_packet", "AF_PACKET binding NIC" );