内核与用户态通信

1、#include #include #include #include #include #include #include#define SOCKET_OPS_BASE#define SOCKET_OPS_SET #define SOCKET_OPS_GET#define SOCKET_OPS_MAX128( SOCKET_OPS_BASE )( SOCKET_OPS_BASE )( SOCKET_OPS_BASE + 1)#define KMSG"a message from kernel"For personal use only in study and resea

2、rch; not for commercial use netfilter 提供了 nf_register_sockopt() 和 nf_unregister_sockopt() 来动态登记或取消 sockopt 命令 字；打开一个网络 socket 后可以使用 set/getsockopt(2) 可实现用户空间与内核的通信，本质 和 ioctl 差不多， 区别在于 set/getsockopt 不用新建设备， 直接利用系统已有的 socket 类型就 可以进行，可用 setsockopt 函数向内核写数据，用 getsockopt 向内核读数据。module.c:<linux/modu

3、le.h><linux/kernel.h><linux/types.h><linux/string.h><linux/netfilter_ipv4.h><linux/init.h> <asm/uaccess.h>#define KMSG_LENsizeof ( "a message from kernel"MODULE_LICENSE ( "GPL" );staticintrecv_msg ( structsock * sk , int cmd, void_user* user

4、gnedintlen )intret= 0;printk ( KERN_INFO "sockopt: recv_msg()n" );unsiif ( cmd = SOCKET_OPS_SET )char umsg 64;int len = sizeof ( char )* 64;memset ( umsg , 0, len );umsg , ret );ret = copy_from_user ( umsg , user , len ); printk ( "recv_msg: umsg = %s. ret = %dn"return 0;static i

5、nt send_msg ( struct sock * sk , int cmd, void _user * user , int* len )int ret = 0;printk ( KERN_INFO "sockopt: send_msg()n" );if ( cmd = SOCKET_OPS_GET )ret = copy_to_user ( user , KMSG, KMSG_LEN);printk ( "send_msg: umsg = %s. ret = %d. successn", KMSG, ret )return 0;static st

6、ruct nf_sockopt_ops test_sockops . pf = PF_INET ,. set_optmin=SOCKET_OPS_SET ,. set_optmax=SOCKET_OPS_MAX ,. set = recv_msg ,. get_optmin=SOCKET_OPS_GET ,. get_optmax=SOCKET_OPS_MAX ,. get = send_msg ,. owner = THIS_MODULE ,;static int _initinit_sockopt ( void )printk ( KERN_INFO "sockopt: init

7、_sockopt()n" ); return nf_register_sockopt (& test_sockops );static void _exitfini_sockopt ( void );printk ( KERN_INFO "sockopt: fini_sockopt()n"nf_unregister_sockopt(& test_sockops );module_init( init_sockopt);module_exit( fini_sockopt);user.c:#include <unistd.h>#includ

8、e <stdio.h>#include <sys/socket.h>#include <linux/in.h>#include <string.h>#include <errno.h>#define SOCKET_OPS_BASE#define SOCKET_OPS_SET #define SOCKET_OPS_GET#define SOCKET_OPS_MAX128( SOCKET_OPS_BASE )( SOCKET_OPS_BASE )( SOCKET_OPS_BASE + 1)#define UMSG#define"

9、a message from userspace"UMSG_LEN sizeof ( "a message from userspace" char kmsg 64;int main ( void ) int sockfd int len ;int ret ;sockfd = socket ( AF_INET , SOCK_RAW, IPPROTO_RAW ); if ( sockfd < 0)printf ( "can not create a socketn" ); return - 1;/*call function recv_ms

10、g()*/ret = setsockopt ( sockfd , IPPROTO_IP , SOCKET_OPS_SET , UMSG, UMSG_L EN);printf( "setsockopt: ret = %d. msg = %sn", ret , UMSG);len = sizeof ( char )* 64 ;/*call function send_msg()*/ret = getsockopt ( sockfd , IPPROTO_IP , SOCKET_OPS_GET , kmsg , &len ); printf( "getsockop

11、t: ret = %d. msg = %sn", ret , kmsg );ifstrerror( ret !=0)printf( errno( "getsockopt error: errno = %d, errstr = %sn" );, errnoclose ( sockfd ); return 0;Makefile:TARGET = testOBJS = test.oMDIR = drivers/miscEXTRA_CFLAGS = -DEXPORT_SYMTABCURRENT = $(shell uname -r)KDIR = /lib/modules/

12、$(CURRENT) /buildPWD = $(shell pwd)DEST = /lib/modules/$(CURRENT) /kernel/$(MDIR)obj-m := $(TARGET) .o $(TARGET)-objs := module.o default :make -C $(KDIR) SUBDIRS= gcc -o user user.c$(TARGET) .o : $(OBJS)$(LD) $(LD_RFLAG) -r -o $ ifneq (, $(findstring 2.4.,$(CURRENT) install :su -c "cp -v $(TAR

13、GET) .o elseinstall :su -c "cp -v $(TARGET) .ko endif$(PWD) modules$(OBJS)$(DEST) && /sbin/depmod -a"$(DEST) && /sbin/depmod -a"clean-rm -rf *.o *.ko . $(TARGET) .ko.cmd .*.flags *.mod.c modules.order Module.symvers .tmp_versions-rm -rf protocol/*.o protocol/.*.o.cmd-rm -rf user-include$(KDIR) /Rules.make仅供个人用于学习、研究；不得用于商业用途。For personal use only in study and research; not for commercial use.Nur f u r den pers?nlichen fu r Studien, Forschung, zu kommerziellen Zwecken verwendet werden.Pour l ' e tude et la recherche uniquementa des fins personne