how to get ip options in lsm hook function -- security_socket_recvmsg?

cyyuanml@sonata.iscas.ac.cn

hi,now i can add labels in ip options in security_socket_sendmsg.
But can i do get ip options in security_socket_recvmsg ?
i try it in security_socket_recvmsg :
----------------------------------------------------------------------
	struct sock *sk = sock->sk;
	struct inet_opt *inet=inet_sk(sk);
	struct ip_options *opt = NULL;

	opt = inet->opt;
	saddr_skb=inet->saddr;
	if ( !opt ){
		printk("daddr : %x\n",inet->daddr);
		printk("dport : %d\n",inet->dport);
		printk("source ip: %x\n",saddr_skb);
		printk("sport : %d\n",inet->sport);
		printk("inet->opt : %d\n",inet->opt);
		printk (KERN_INFO "opt == NULL in smos_socket_recvmsg! \n");
		return 0; // 22, Invalid argument
	} else        
    		return secopt_socket_check_ip_options((char *)opt);
----------------------------------------------------------------------
BUT opt=NULL. 

another question is in security_ip_decode_options function :
 static int security_ip_decode_options (struct sk_buff *skb, const char
*optptr,
				    unsigned char **pp_ptr) 
i can not know the meaning of pp_ptr.can somebody explain it clearly ?
it's explained in lsm as:
 * pp_ptr contains the 
 * parameter problem pointer. Returns 0 on success. A non-zero return
value will 
 * cause an ICMP parameter problem message to be generated and
transmitted to the 
 * sender. The pp_ptr parameter may be used to point to the offending
option
 * parameter. 
	
thanx!
                                                                            							yuan

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