Linux中与内核通信的Netlink机制（实例）

<span style="color:rgb(0,0,0);"><font face="Courier New"><span style="color:rgb(0,0,255);">extern</span> <span style="color:rgb(0,0,255);">struct</span> sock <span style="color:rgb(0,0,204);">*</span>netlink_kernel_create<span style="color:rgb(0,0,204);">(</span><span style="color:rgb(0,0,255);">struct</span> net <span style="color:rgb(0,0,204);">*</span>net<span style="color:rgb(0,0,204);">,</span><br />                     <span style="color:rgb(0,0,255);">int</span> unit<span style="color:rgb(0,0,204);">,</span><span style="color:rgb(0,0,255);">unsigned</span> <span style="color:rgb(0,0,255);">int</span> groups<span style="color:rgb(0,0,204);">,</span><br />                     <span style="color:rgb(0,0,255);">void</span> <span style="color:rgb(0,0,204);">(</span><span style="color:rgb(0,0,204);">*</span>input<span style="color:rgb(0,0,204);">)</span><span style="color:rgb(0,0,204);">(</span><span style="color:rgb(0,0,255);">struct</span> sk_buff <span style="color:rgb(0,0,204);">*</span>skb<span style="color:rgb(0,0,204);">)</span><span style="color:rgb(0,0,204);">,</span><br />                     <span style="color:rgb(0,0,255);">struct</span> mutex <span style="color:rgb(0,0,204);">*</span>cb_mutex<span style="color:rgb(0,0,204);">,</span><br />                     <span style="color:rgb(0,0,255);">struct</span> module <span style="color:rgb(0,0,204);">*</span>module<span style="color:rgb(0,0,204);">)</span><span style="color:rgb(0,0,204);">;</span><br /></font></span>

<span style="color:rgb(0,0,0);"><font face="Courier New">audit_sock <span style="color:rgb(0,0,204);">=</span> netlink_kernel_create<span style="color:rgb(0,0,204);">(</span><span style="color:rgb(0,0,204);">&</span>init_net<span style="color:rgb(0,0,204);">,</span> NETLINK_AUDIT<span style="color:rgb(0,0,204);">,</span> 0<span style="color:rgb(0,0,204);">,</span><br />                                      audit_receive<span style="color:rgb(0,0,204);">,</span> <span style="color:rgb(255,0,0);">NULL</span><span style="color:rgb(0,0,204);">,</span> THIS_MODULE<span style="color:rgb(0,0,204);">)</span><span style="color:rgb(0,0,204);">;</span><br /></font></span>

<span style="color:rgb(0,0,0);"><font face="Courier New"><span style="color:rgb(0,0,255);">int</span> netlink_unicast<span style="color:rgb(0,0,204);">(</span><span style="color:rgb(0,0,255);">struct</span> sock <span style="color:rgb(0,0,204);">*</span>ssk<span style="color:rgb(0,0,204);">,</span> <span style="color:rgb(0,0,255);">struct</span> sk_buff <span style="color:rgb(0,0,204);">*</span>skb<span style="color:rgb(0,0,204);">,</span> u32 pid<span style="color:rgb(0,0,204);">,</span> <span style="color:rgb(0,0,255);">int</span> nonblock<span style="color:rgb(0,0,204);">)</span></font></span>

<span style="color:rgb(0,0,0);"><font face="Courier New"><span style="color:rgb(0,0,255);">extern</span> <span style="color:rgb(0,0,255);">struct</span> sock <span style="color:rgb(0,0,204);">*</span>netlink_kernel_create<span style="color:rgb(0,0,204);">(</span><span style="color:rgb(0,0,255);">struct</span> net <span style="color:rgb(0,0,204);">*</span>net<span style="color:rgb(0,0,204);">,</span><br />                                     <span style="color:rgb(0,0,255);">int</span> unit<span style="color:rgb(0,0,204);">,</span><span style="color:rgb(0,0,255);">unsigned</span> <span style="color:rgb(0,0,255);">int</span> groups<span style="color:rgb(0,0,204);">,</span><br />                                     <span style="color:rgb(0,0,255);">void</span> <span style="color:rgb(0,0,204);">(</span><span style="color:rgb(0,0,204);">*</span>input<span style="color:rgb(0,0,204);">)</span><span style="color:rgb(0,0,204);">(</span><span style="color:rgb(0,0,255);">struct</span> sk_buff <span style="color:rgb(0,0,204);">*</span>skb<span style="color:rgb(0,0,204);">)</span><span style="color:rgb(0,0,204);">,</span><br />                                     <span style="color:rgb(0,0,255);">struct</span> mutex <span style="color:rgb(0,0,204);">*</span>cb_mutex<span style="color:rgb(0,0,204);">,</span><br />                                     <span style="color:rgb(0,0,255);">struct</span> module <span style="color:rgb(0,0,204);">*</span>module<span style="color:rgb(0,0,204);">)</span><span style="color:rgb(0,0,204);">;</span></font></span>

<span style="color:rgb(0,0,0);"><font face="Courier New">nlsk <span style="color:rgb(0,0,204);">=</span> netlink_kernel_create<span style="color:rgb(0,0,204);">(</span>net<span style="color:rgb(0,0,204);">,</span> NETLINK_XFRM<span style="color:rgb(0,0,204);">,</span> XFRMNLGRP_MAX<span style="color:rgb(0,0,204);">,</span><br />                                 xfrm_netlink_rcv<span style="color:rgb(0,0,204);">,</span> <span style="color:rgb(255,0,0);">NULL</span><span style="color:rgb(0,0,204);">,</span> THIS_MODULE<span style="color:rgb(0,0,204);">)</span><span style="color:rgb(0,0,204);">;</span><br /> <br /><br /><span style="color:rgb(0,0,255);">static</span> <span style="color:rgb(0,0,255);">void</span> xfrm_netlink_rcv<span style="color:rgb(0,0,204);">(</span><span style="color:rgb(0,0,255);">struct</span> sk_buff <span style="color:rgb(0,0,204);">*</span>skb<span style="color:rgb(0,0,204);">)</span><br /><span style="color:rgb(0,0,204);">{</span><br />       mutex_lock<span style="color:rgb(0,0,204);">(</span><span style="color:rgb(0,0,204);">&</span>xfrm_cfg_mutex<span style="color:rgb(0,0,204);">)</span><span style="color:rgb(0,0,204);">;</span><br /><br />       netlink_rcv_skb<span style="color:rgb(0,0,204);">(</span>skb<span style="color:rgb(0,0,204);">,</span> <span style="color:rgb(0,0,204);">&</span>xfrm_user_rcv_msg<span style="color:rgb(0,0,204);">)</span><span style="color:rgb(0,0,204);">;</span><br />       mutex_unlock<span style="color:rgb(0,0,204);">(</span><span style="color:rgb(0,0,204);">&</span>xfrm_cfg_mutex<span style="color:rgb(0,0,204);">)</span><span style="color:rgb(0,0,204);">;</span><br /><span style="color:rgb(0,0,204);">}</span><br />在netlink_rcv_skb<span style="color:rgb(0,0,204);">(</span><span style="color:rgb(0,0,204);">)</span>函数中进行接收处理。<br /> <br /><br /><span style="color:rgb(0,0,255);">int</span> netlink_broadcast<span style="color:rgb(0,0,204);">(</span><span style="color:rgb(0,0,255);">struct</span> sock <span style="color:rgb(0,0,204);">*</span>ssk<span style="color:rgb(0,0,204);">,</span> <span style="color:rgb(0,0,255);">struct</span> sk_buff <span style="color:rgb(0,0,204);">*</span>skb<span style="color:rgb(0,0,204);">,</span> u32 pid<span style="color:rgb(0,0,204);">,</span><br />                    u32 group<span style="color:rgb(0,0,204);">,</span> gfp_t allocation<span style="color:rgb(0,0,204);">)</span><br /></font></span>

<span style="color:rgb(0,0,0);"><font face="Courier New">NETLINK_CB<span style="color:rgb(0,0,204);">(</span>skb<span style="color:rgb(0,0,204);">)</span><span style="color:rgb(0,0,204);">.</span>pid <span style="color:rgb(0,0,204);">=</span> 0<span style="color:rgb(0,0,204);">;</span><br /><br />NETLINK_CB<span style="color:rgb(0,0,204);">(</span>skb<span style="color:rgb(0,0,204);">)</span><span style="color:rgb(0,0,204);">.</span>dst_pid <span style="color:rgb(0,0,204);">=</span> 0<span style="color:rgb(0,0,204);">;</span><br /><br />NETLINK_CB<span style="color:rgb(0,0,204);">(</span>skb<span style="color:rgb(0,0,204);">)</span><span style="color:rgb(0,0,204);">.</span>dst_group <span style="color:rgb(0,0,204);">=</span> 1<span style="color:rgb(0,0,204);">;</span><br /></font></span>