proc_net.c
#include <net/net_namespace.h>
#include <linux/module.h> /* Specifically, a module */
#include <linux/kernel.h> /* We're doing kernel work */
#include <linux/proc_fs.h> /* Necessary because we use the proc fs */
#define procfs_name "helloworld"
struct proc_dir_entry *Our_Proc_File;
int
procfile_read(char *buffer,
char **buffer_location,
off_t offset, int buffer_length, int *eof, void *data)
{
int ret;
printk(KERN_INFO "procfile_read (/proc/%s) called\n", procfs_name);
/*
* We give all of our information in one go, so if the
* user asks us if we have more information the
* answer should always be no.
*
* This is important because the standard read
* function from the library would continue to issue
* the read system call until the kernel replies
* that it has no more information, or until its
* buffer is filled.
*/
if (offset > 0) {
printk(KERN_INFO "offset > 0\n");
/* we have finished to read, return 0 */
ret = 0;
} else {
/* fill the buffer, return the buffer size */
printk(KERN_INFO "offset <= 0\n");
ret = sprintf(buffer, "HelloWorld!\n");
}
return ret;
}
int init_module()
{
Our_Proc_File = create_proc_entry(procfs_name, 0644, init_net.proc_net);
if (Our_Proc_File == NULL) {
remove_proc_entry(procfs_name, init_net.proc_net);
printk(KERN_ALERT "Error: Could not initialize /proc/%s\n",
procfs_name);
return -ENOMEM;
}
Our_Proc_File->read_proc = procfile_read;
Our_Proc_File->owner = THIS_MODULE;
Our_Proc_File->mode = S_IFREG | S_IRUGO;
Our_Proc_File->uid = 0;
Our_Proc_File->gid = 0;
Our_Proc_File->size = 37;
printk(KERN_INFO "/proc/net/%s created\n", procfs_name);
return 0; /* everything is ok */
}
void cleanup_module()
{
remove_proc_entry(procfs_name, init_net.proc_net);
printk(KERN_INFO "/proc/net/%s removed\n", procfs_name);
}
Makefile
obj-m := proc_net.o
KDIR := /lib/modules/$(shell uname -r)/build
PWD := $(shell pwd)
default:
$(MAKE) -C $(KDIR) M=$(PWD) modules
clean:
$(RM) *.o *.mod.c *.ko *.symvers *.markers *.order
[root@zj:~/Desktop/net/proc]# cat /proc/net/helloworld
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