从内核模块内部发送原始以太网数据包

Question

我发现我需要在内核模块中构建一个新的sk_buff结构并将其传递给我的网络设备,但我无法弄清楚的是如何为简单的原始以太网数据包设置结构变量.

这一定很简单,但我真的很感激,如果有人能给我一个如何将sk_buff放在一起的示例代码.

Answer 1

看看在函数packet_sendmsg_spkt中net/packet/af_packet.c寻找灵感.struct sock如果你没有插座,困难的部分是...

编辑:添加了基本代码shell:

int sendpacket(struct socket *sock, struct net_device *dev, __be16 proto, void *data, size_t len)
{
    struct sock *sk = sock->sk;
    struct sk_buff *skb;

    if (!(dev->flags & IFF_UP))
        return -ENETDOWN;

    if (len > dev->mtu + dev->hard_header_len)
        return -EMSGSIZE;

    skb = sock_wmalloc(sk, len + LL_RESERVED_SPACE(dev), 0, GFP_KERNEL);

    if (skb == NULL)
        return -ENOBUFS;

    /* FIXME: Save some space for broken drivers that write a
     * hard header at transmission time by themselves. PPP is the
     * notable one here. This should really be fixed at the driver level.
     */
    skb_reserve(skb, LL_RESERVED_SPACE(dev));
    skb_reset_network_header(skb);

    /* Try to align data part correctly */
    if (dev->header_ops) {
        skb->data -= dev->hard_header_len;
        skb->tail -= dev->hard_header_len;
        if (len < dev->hard_header_len)
            skb_reset_network_header(skb);
    }

    memcpy(skb_put(skb, len), data, len);
    skb->protocol = proto;
    skb->dev = dev;
    skb->priority = sk->sk_priority;

    dev_queue_xmit(skb);

    return len;
}