Linux kernel 将数据包从IP层传递到设备驱动程序

我试图将一个sk_buff数据包从协议栈的IP层传递到我创建并注册的设备驱动程序。设备驱动程序的代码如下所示：

    #include<linux/module.h>
    #include<linux/netdevice.h>
    #include<linux/kernel.h>
    #include<linux/skbuff.h>
    #include<linux/pci.h>
    #include<linux/interrupt.h>
    struct net_device *my_dev;
    static netdev_tx_t veth_xmit(struct sk_buff *skb, struct net_device *dev)
    {
           printk(KERN_INFO "I got a packet");    
           return NETDEV_TX_OK;
    }
    static int veth_open(struct net_device *dev)
    {

                  memcpy(dev->dev_addr, "\0ABCD0", ETH_ALEN);
                  netif_start_queue(dev);

                  return 0;
    }


    int veth_close(struct net_device *dev)
    {
           printk("releasing mydev\n");
           netif_stop_queue(dev);
           return 0;
    }

    int veth_dev_init(struct net_device *dev)
    {
           printk("initialising\n");
           return 0;
    }

    static struct net_device_ops veth_ops = {

     .ndo_init         = veth_dev_init,
     .ndo_open         = veth_open,
     .ndo_stop         = veth_close,
     .ndo_start_xmit   = veth_xmit,

       };
   int veth_init()
   {
   int ret,i;
   my_dev = alloc_netdev(sizeof(struct net_device), "my_dev", ether_setup);
   if (my_dev == NULL)
    return -ENOMEM; 
   my_dev->netdev_ops = &veth_ops;
       register_netdev(my_dev);
       return 0;
   }
   void veth_exit()
   {
    unregister_netdev(my_dev);
    free_netdev(my_dev);
   }

   module_init(veth_init);
   module_exit(veth_exit);

---

但是数据包没有通过，当我尝试加载此测试模块时，系统显示致命错误并终止进程。您能给我建议一个解决这个问题的好方法吗？

因为您的代码显示您只是将skb分配为

   struct sk_buff *skb;
   void generate_send()
   {
   skb=alloc_skb(skb,2);
   skb->data[0]='m';//just to check
       skb->dev="my_dev";
       dev_queue_xmit(skb);
   }

因此，无法检查alloc_skb（）是否成功分配存储。您只需设置这个（skb）结构的dev和data参数。但是如果您在文件/net/core/dev.c中看到函数dev_queue_xmit（）的源代码，您将得到返回值为正值但并不意味着数据包已被传输的结果

因此，首先尝试创建整个数据包作为其UDP/TCP报头、IP报头和协议建议的数据。然后将skb的字段设置为整个新创建的数据包。 现在尝试发送它，您将得到结果

如需参考，请尝试->

skb = alloc_skb(len, GFP_ATOMIC);
if (!skb)
        return;

skb_put(skb, len);

skb_push(skb, sizeof(*udph));
skb_reset_transport_header(skb);
udph = udp_hdr(skb);
udph->source = htons(....);
udph->dest = htons(...);
udph->len = htons(udp_len);
udph->check = 0;
udph->check = csum_tcpudp_magic(local_ip,
                                remote_ip,
                                udp_len, IPPROTO_UDP,
                                csum_partial(udph, udp_len, 0));

if (udph->check == 0)
        udph->check = CSUM_MANGLED_0;

skb_push(skb, sizeof(*iph));
skb_reset_network_header(skb);
iph = ip_hdr(skb);

/* iph->version = 4; iph->ihl = 5; */
put_unaligned(0x45, (unsigned char *)iph);
iph->tos      = 0;
put_unaligned(htons(ip_len), &(iph->tot_len));
iph->id       = htons(atomic_inc_return(&ip_ident));
iph->frag_off = 0;
iph->ttl      = 64;
iph->protocol = IPPROTO_UDP;
iph->check    = 0;
put_unaligned(local_ip, &(iph->saddr));
put_unaligned(remote_ip, &(iph->daddr));
iph->check    = ip_fast_csum((unsigned char *)iph, iph->ihl);

eth = (struct ethhdr *) skb_push(skb, ETH_HLEN);
skb_reset_mac_header(skb);
skb->protocol = eth->h_proto = htons(ETH_P_IP);
memcpy(eth->h_source, dev->dev_addr, ETH_ALEN);
memcpy(eth->h_dest, remote_mac, ETH_ALEN);

skb->dev = dev;


dev_queue_xmit(skb);

---

根据需要更改字段…

是否可以添加代码来检查

dev_queue_xmit

的返回值？它将在出错时返回一个否定代码。也许你可以检查它是否真的在排队等待传输或抛出错误。我已经更改了代码，从数据包传输的位置，dev_get_by_name（&init_net，“my_dev”）；现在，紧急错误已被删除，但dev_queue_xmit（）返回2，这是网络拥塞消息。现在如何摆脱它，从司机那里接过包裹？我不确定

dev_queue_xmit

正是因为这个原因以及其他原因才允许丢弃数据包。我在这方面经验不足。这突出了在操作Linux的skbuff例程时使用它们的重要性。如果你不这样做，内部的内务变量就不能保持理智，你会得到奇怪的bug。

skb = alloc_skb(len, GFP_ATOMIC);
if (!skb)
        return;

skb_put(skb, len);

skb_push(skb, sizeof(*udph));
skb_reset_transport_header(skb);
udph = udp_hdr(skb);
udph->source = htons(....);
udph->dest = htons(...);
udph->len = htons(udp_len);
udph->check = 0;
udph->check = csum_tcpudp_magic(local_ip,
                                remote_ip,
                                udp_len, IPPROTO_UDP,
                                csum_partial(udph, udp_len, 0));

if (udph->check == 0)
        udph->check = CSUM_MANGLED_0;

skb_push(skb, sizeof(*iph));
skb_reset_network_header(skb);
iph = ip_hdr(skb);

/* iph->version = 4; iph->ihl = 5; */
put_unaligned(0x45, (unsigned char *)iph);
iph->tos      = 0;
put_unaligned(htons(ip_len), &(iph->tot_len));
iph->id       = htons(atomic_inc_return(&ip_ident));
iph->frag_off = 0;
iph->ttl      = 64;
iph->protocol = IPPROTO_UDP;
iph->check    = 0;
put_unaligned(local_ip, &(iph->saddr));
put_unaligned(remote_ip, &(iph->daddr));
iph->check    = ip_fast_csum((unsigned char *)iph, iph->ihl);

eth = (struct ethhdr *) skb_push(skb, ETH_HLEN);
skb_reset_mac_header(skb);
skb->protocol = eth->h_proto = htons(ETH_P_IP);
memcpy(eth->h_source, dev->dev_addr, ETH_ALEN);
memcpy(eth->h_dest, remote_mac, ETH_ALEN);

skb->dev = dev;


dev_queue_xmit(skb);