Linux添加新协议

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添加协议号

​ \include\linux\socket.h中定义了地址协议族，修改AF_MAX+1（地址协议族数），并加上自己的协议族

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#define AF_KCM		41	/* Kernel Connection Multiplexor*/
#define AF_QIPCRTR	42	/* Qualcomm IPC Router          */
#define AF_AS       43  /* 新协议*/

#define AF_MAX		44	/* For now.. */

#define PF_AS       AF_AS  /* 新协议*/

/* Protocol families, same as address families. */
#define PF_UNSPEC	AF_UNSPEC
#define PF_UNIX		AF_UNIX
#define PF_LOCAL	AF_LOCAL

​ 通过添加协议号的方式，需要重新编译内核

编译内核

下载linux源码，进入源码根目录编译

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su
make menuconfig
make -j 32
make modules_install
make install
make headers_install INSTALL_HDR_PATH=/usr

然后重启，查看新内核版本

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zjw@ubuntu:~$ uname -r
4.10.0

添加新协议模块

添加一个空协议 aproto.c，大部分函数是空函数。根据/net/rds.c修改的，将原来rds改成as，AF_INET改成AF_AS

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#include <linux/module.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/gfp.h>
#include <linux/in.h>
#include <linux/poll.h>
#include <net/sock.h>
#include <linux/init.h>

static int as_release(struct socket *sock)
{
	return 0;
}
static int as_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
{
	return 0;
}
static int as_getname(struct socket *sock, struct sockaddr *uaddr,
		       int *uaddr_len, int peer)
{
	return 0;
}
static int as_sendmsg(struct socket *sock, struct msghdr *msg, size_t payload_len)
{
	int ret =0;
	return ret;
}
static int as_recvmsg(struct socket *sock, struct msghdr *msg, size_t size, int msg_flags)
{
	int ret =0;
	return ret;	
}
static unsigned int as_poll(struct file *file, struct socket *sock,
			     poll_table *wait)
{
	int ret = 0;
	return ret;
}
static int as_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
{
	return -ENOIOCTLCMD;
}

static int as_setsockopt(struct socket *sock, int level, int optname,
			  char __user *optval, unsigned int optlen)
{
	int ret =0 ;
	return ret;
}

static int as_getsockopt(struct socket *sock, int level, int optname,
			  char __user *optval, int __user *optlen)
{
	int ret = 0;
	return ret;

}
static int as_connect(struct socket *sock, struct sockaddr *uaddr,
		       int addr_len, int flags)
{
	int ret =0 ;
	return ret;
}

static struct proto as_proto = {
	.name	  = "A_PROTO",
	.owner	  = THIS_MODULE,
	.obj_size = sizeof(struct sock),
};

static const struct proto_ops as_proto_ops = {
	.family =	AF_AS, // 自定义协议族
	.owner =	THIS_MODULE,
	.release =	as_release,
	.bind =		as_bind,
	.connect =	as_connect,
	.socketpair =	sock_no_socketpair,
	.accept =	sock_no_accept,
	.getname =	as_getname,
	.poll =		as_poll,
	.ioctl =	as_ioctl,
	.listen =	sock_no_listen,
	.shutdown =	sock_no_shutdown,
	.setsockopt =	as_setsockopt,
	.getsockopt =	as_getsockopt,
	.sendmsg =	as_sendmsg, 
	.recvmsg =	as_recvmsg, 
	.mmap =		sock_no_mmap,
	.sendpage =	sock_no_sendpage,
};


static int __as_create(struct socket *sock, struct sock *sk, int protocol)
{
	struct as_sock *as;

	sock_init_data(sock, sk);
	sock->ops		= &as_proto_ops;
	sk->sk_protocol		= protocol;
	return 0;
}

static int as_create(struct net *net, struct socket *sock, int protocol,
		      int kern)
{
	struct sock *sk;

	if (sock->type != SOCK_SEQPACKET || protocol)
		return -ESOCKTNOSUPPORT;

	sk = sk_alloc(net, AF_AS, GFP_ATOMIC, &as_proto, kern);
	if (!sk)
		return -ENOMEM;

	return __as_create(sock, sk, protocol);
}


static const struct net_proto_family as_family_ops = {
	.family =	AF_AS,
	.create =	as_create,
	.owner	=	THIS_MODULE,
};


static int __init as_init(void)
{
	int ret;
	printk(KERN_INFO "as_init\n");

	ret = proto_register(&as_proto, 1); //注册协议
	if (ret)
	{
		printk(KERN_ERR "proto_register ERROR\n");
		goto out;
	}
	ret = sock_register(&as_family_ops);
	if (ret)
	{
		printk(KERN_ERR "sock_register ERROR\n");
		goto out;
	}
	goto out;
	printk(KERN_INFO "device has been registered\n");
out:
	return ret;
}

static void __exit as_exit(void){
   printk(KERN_INFO "aproto exit\n");
}

module_init(as_init);
module_exit(as_exit);

#define DRV_RELDATE     "2017/12/07"
MODULE_AUTHOR("Jingwei Zheng");
MODULE_DESCRIPTION("AS:A NEW PROTOCOL" DRV_RELDATE);

应用程序

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#define AF_AS 43
...
socket_fd = socket(AF_AS, SOCK_SEQPACKET, 0)
...