Hi,
I'm a netlink newbie developing a kernel module (as stated above) for 2.6.x kernels.
I'm simply truing to pass a(any) message between the user space and the kernel.
The changes to the netlink APIs from kernel to kernel are confusing.
Below is my kernel code:
Code:
#include
#include
#include
#include
#include
#include
#include
#include
#include
#define NETLINK_TEST 17
#define VFW_GROUP 0
#define MSG_SIZE NLMSG_SPACE(1024)
static struct sock *nl_sk = NULL;
static void nltest_rcv(struct sock *sk, int len)
{
struct sk_buff *nl_skb;
struct nlmsghdr *nl_hdr;
int pid;
while ((nl_skb = skb_dequeue(&sk->sk_receive_queue)) != NULL) {
nl_hdr = (struct nlmsghdr *)nl_skb->data;
pid = nl_hdr->nlmsg_pid;
printk(KERN_ALERT "*** Message from user with PID: (pid = %d) is %s\n", pid, (char*)NLMSG_DATA(nl_hdr));
nl_skb = alloc_skb(MSG_SIZE, in_interrupt() ? GFP_ATOMIC : GFP_KERNEL);
skb_put(nl_skb, MSG_SIZE);
nl_hdr = (struct nlmsghdr *)nl_skb->data;
nl_hdr->nlmsg_len = MSG_SIZE;
nl_hdr->nlmsg_pid = pid;
nl_hdr->nlmsg_flags = 0;
strcpy(NLMSG_DATA(nl_hdr), "HELLO HELLO HELLO");
NETLINK_CB(nl_skb).pid = 0;
NETLINK_CB(nl_skb).dst_pid = pid;
NETLINK_CB(nl_skb).dst_group = VFW_GROUP;
netlink_unicast(nl_sk, nl_skb, pid, 0);
kfree_skb(nl_skb);
}
}
/* LXR reference:http://lxr.linux.no/#linux+v2.6.26.7/net/netlink/af_netlink.c#L1358
struct sock * netlink_kernel_create
(struct net *net, int unit, unsigned int groups,void (*input)(struct sk_buff *skb),struct mutex *cb_mutex, struct module *module)
*/
static int __init nltest_init(void)
{
struct net *net;
printk(KERN_ALERT "INIT/START: nltest\n");
nl_sk = netlink_kernel_create(net,NETLINK_TEST, VFW_GROUP, nltest_rcv, 0, THIS_MODULE);
if (!nl_sk) {
printk(KERN_ALERT "ERROR: nltest - netlink_kernel_create() failed\n");
return -1;
}
return 0;
}
static void __exit nltest_exit(void)
{
printk(KERN_ALERT "EXIT: nltest\n");
sock_release(nl_sk->sk_socket);
return;
}
module_init(nltest_init);
module_exit(nltest_exit);
MODULE_DESCRIPTION("Module_Test_Netlink");
MODULE_LICENSE("GPL");
when I run a make on this file, it shows the following errors:
root@ubuntu:/home/p# make
make -C /lib/modules/2.6.27-15-generic/build M=/home/p modules
make[1]: Entering directory `/usr/src/linux-headers-2.6.27-15-generic'
CC [M] /home/priyanka/kern.o
/home/p/kern.c: In function ‘nltest_rcv’:
/home/p/kern.c:37: error: ‘struct netlink_skb_parms’ has no member named ‘dst_pid’
/home/p/kern.c: In function ‘nltest_init’:
/home/p/kern.c:54: warning: passing argument 4 of ‘netlink_kernel_create’ from incompatible pointer type
make[2]: *** [/home/p/kern.o] Error 1
make[1]: *** [_module_/home/p] Error 2
make[1]: Leaving directory `/usr/src/linux-headers-2.6.27-15-generic'
make: *** [all] Error 2
The two errors are for
1. netlink_kernel_create function
2. struct netlink_skb_parms
Can anyone help me figure out how to solve these errors?
Thanks!
