Hi,
I have tried 3 solutions:
1. using nlh = (struct nlmsghdr *) skb_put(skb,
NLMSG_SPACE(MAX_PAYLOAD)); instead of nlh = (struct nlmsghdr
*)skb->data;
No kernel panic, but doesn't work (it is just like before)
2. with skb_copy_expand and skb_push like in the second example you
gave me, No kernel panic, but doesn't work (juste like before)
3. with the example of wwrap.c (your last idea), doest compile, or kernel panic
But i don't really now what I should put in *message type* argument in
NLMSG_PUT.
My code for last solution is bellow.
If never you have others ideas.
Thierry
------
struct sk_buff *skb = NULL;
struct nlmsghdr *nlh = NULL;
int err;
int size;
unsigned char * old_tail;
char * pos = NULL;
size = NLMSG_SPACE(MAX_PAYLOAD);
u32 pid;
//Creation de la netlink socket <=> socket()
nl_sk = netlink_kernel_create(NETLINK_IB, GROUP_IB, nl_ib_data_ready,
THIS_MODULE);
skb = alloc_skb(NLMSG_SPACE(MAX_PAYLOAD),GFP_KERNEL);
if (skb == NULL)
{
printk(KERN_ALERT "erreur\n");
return;
}
old_tail = skb -> tail;
//nlh = (struct nlmsghdr *)skb->data;
nlh = NLMSG_PUT(skb, 0, 0, 0, size-sizeof(*nlh));
int len = sizeof("Message du kernel =(");
pos = NLMSG_DATA(len);
memset(pos,0,len);
nlh->nlmsg_pid = 0; //Depuis le noyau
nlh->nlmsg_flags = 0;
strcpy(NLMSG_DATA(nlh), "Message du kernel =(");
NETLINK_CB(skb).pid = 0;
NETLINK_CB(skb).dst_pid = 0; //Multicast
NETLINK_CB(skb).dst_group = GROUP_IB;
nlh->nlmsg_len = skb->tail - old_tail;
//Envoi des donnees
printk( KERN_ALERT "j'envoi els donnees\n");
err = netlink_broadcast(nl_sk, skb, 0, GROUP_IB, GFP_KERNEL);
On Fri, Apr 10, 2009 at 2:29 PM, Peter Teoh <htmldeveloper@xxxxxxxxx> wrote:
> On Fri, Apr 10, 2009 at 4:12 AM, Thierry <chocapiiic.tiery@xxxxxxxxx> wrote:
>> Hi,
>>
>> I have tried to change groupId, with different value, but there should
>> be somethings wrong: the userspace prgm doesn't receive message.
>> I would like to know if there is a plugin for tcpdump or an way of
>> capture trafic on netlink socket, just like usual network socket in
>> order to see were is my problem: in kernel space code or userspace
>> code.
>> My program code is attached, with english commit (sorry for last mail).
>> I have also tried my code on differents kernel (redhat 4.4 with kernel
>> 2.6.9-42.ELsmp, centos52 kernel 2.6.18-92.1.22).
>>
>> If there is other ways to send information from kernel space to user space...
>> My aim is to capture data trafic from infiniband and dump trafic, for
>> example in a netlink socket. Then I will be able with a userspace code
>> to translate informations in .cap files.
>> Thats why I think netlink_broadcast is a good idea.
>>
>> I will be always looking at kernelnewbie mailinglsit for several month,
>>
>> Regards,
>>
>> Thierry
>>
>>
>>
>> --------------
>> kernel-level code
>>
>>
>> #include <linux/config.h>
>> #include <linux/socket.h>
>> #include <linux/kernel.h>
>> #include <linux/module.h>
>> #include <linux/netlink.h>
>> #include <net/sock.h>
>>
>> #define NETLINK_IB 24
>> #define MAX_PAYLOAD 1024
>> #define GROUP_IB 59
>>
>>
>> static struct sock *nl_sk = NULL;
>>
>> static void nl_ib_data_ready (struct sock *sk, int len)
>> {
>> wake_up_interruptible(sk->sk_sleep);
>> }
>>
>> static void netlink_ib_open()
>> {
>> struct sk_buff *skb = NULL;
>> struct nlmsghdr *nlh = NULL;
>> int err;
>> u32 pid;
>>
>> //Socket_create
>> nl_sk = netlink_kernel_create(NETLINK_IB, GROUP_IB, nl_ib_data_ready,
>> THIS_MODULE);
>>
>> skb = alloc_skb(NLMSG_SPACE(MAX_PAYLOAD),GFP_KERNEL);
>> nlh = (struct nlmsghdr *)skb->data;
>>
>> nlh->nlmsg_len = NLMSG_SPACE(MAX_PAYLOAD);
>> nlh->nlmsg_pid = 0; //from kernel
>> nlh->nlmsg_flags = 0;
>>
>> strcpy(NLMSG_DATA(nlh), "Message from kernel ");
>> NETLINK_CB(skb).pid = 0;
>> NETLINK_CB(skb).dst_pid = 0; //Multicast
>> NETLINK_CB(skb).dst_group = GROUP_IB;
>>
>> //data send
>> printk( KERN_ALERT "data sent\n");
>> netlink_broadcast(nl_sk, skb, 0, GROUP_IB, GFP_KERNEL);
>> sock_release(nl_sk->sk_socket);
>> }
>
> check this out:
>
> http://www.linuxjournal.com/article/7356
>
> read the comment, amazingly, someone else HAVE EXACTLY THE SAME
> PROBLEM as yours, and his comment:
>
> ========================
>
> here is missed one importang thing:
>
> before strcpy we should call
>
> skb_put(skb, NLMSG_SPACE(MAX_PAYLOAD))
>
> or change
>
>
> nlh = (struct nlmsghdr *)skb->data;
> nlh->nlmsg_len = NLMSG_SPACE(MAX_PAYLOAD);
> nlh->nlmsg_pid = 0; /* from kernel */
> nlh->nlmsg_flags = 0;
>
> ==========================
>
> and looking into kernel source:
>
> s = skb_copy_expand(skb, 8, 0, GFP_ATOMIC);
> skb_push(s, 8);
> s->data[0] = 'z';
> s->data[1] = 'y';
> s->data[2] = 'd';
> s->data[3] = 'a';
> s->data[4] = 's';
> printk("len1=%d, len2=%d", skb->len, s->len);
> netlink_broadcast(rtnl, s, 0, RTMGRP_LINK, GFP_ATOMIC);
>
>
> and this:
>
> /*ÌîдÊý¾Ý±¨Ïà¹ØÐÅÏ¢*/
> nlh = NLMSG_PUT(skb, 0, 0, WAI_K_MSG, size-sizeof(*nlh));
> pos = NLMSG_DATA(nlh);
> memset(pos, 0, len);
>
> /*´«Êäµ½Óû§¿Õ¼äµÄÊý¾Ý*/
> memcpy(pos, msg, len);
> /*¼ÆËã¾¹ý×Ö½Ú¶ÔÆäºóµÄÊý¾Ýʵ¼Ê³¤¶È*/
> nlh->nlmsg_len = skb->tail - old_tail;
> NETLINK_CB(skb).dst_group = COMMTYPE_GROUP;
> netlink_broadcast(netlink_sk, skb, 0, COMMTYPE_GROUP, GFP_ATOMIC);
>
> all having the same pattern as the comment.
>
> Hopefully this helps.
>
> --
> Regards,
> Peter Teoh
>
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