Add Makefile and netlink_logger module for custom netlink messaging

Makefile

@@ -0,0 +1,16 @@
+obj-m += netlink_logger.o
+
+KDIR := /lib/modules/$(shell uname -r)/build
+PWD := $(shell pwd)
+
+all:
+	$(MAKE) -C $(KDIR) M=$(PWD) modules
+
+clean:
+	$(MAKE) -C $(KDIR) M=$(PWD) clean
+
+load:
+	sudo insmod netlink_logger.ko
+	
+unload:
+	sudo rmmod netlink_logger

netlink_logger.c

@@ -0,0 +1,54 @@
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/netlink.h>
+#include <net/sock.h>
+#include <linux/skbuff.h>
+
+#define NETLINK_USER_CUSTOM 31
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Leo");
+MODULE_DESCRIPTION("Netlink message logger for custom protocol");
+
+static struct sock *nl_sk = NULL;
+
+static void netlink_recv_msg(struct sk_buff *skb)
+{
+    struct nlmsghdr *nlh;
+    char *payload;
+
+    if (!skb)
+        return;
+
+    nlh = nlmsg_hdr(skb);
+    payload = (char *)nlmsg_data(nlh);
+
+    pr_info("[netlink_logger] Received netlink msg: %s\n", payload);
+}
+
+static int __init netlink_logger_init(void)
+{
+    struct netlink_kernel_cfg cfg = {
+        .input = netlink_recv_msg,
+    };
+
+    nl_sk = netlink_kernel_create(&init_net, NETLINK_USER_CUSTOM, &cfg);
+    if (!nl_sk) {
+        pr_err("[netlink_logger] Failed to create netlink socket\n");
+        return -ENOMEM;
+    }
+
+    pr_info("[netlink_logger] Netlink logger module loaded (protocol: %d)\n", NETLINK_USER_CUSTOM);
+    return 0;
+}
+
+static void __exit netlink_logger_exit(void)
+{
+    if (nl_sk)
+        netlink_kernel_release(nl_sk);
+    pr_info("[netlink_logger] Module unloaded\n");
+}
+
+module_init(netlink_logger_init);
+module_exit(netlink_logger_exit);