| poplinux |
07-16-2014 03:35 AM |
netlink question in kernel space.
3 Attachment(s)
Dear Sir.
Now, I'm try to study netlink subsystem in linux kernel.(Ver 2.6.32.27)
And, I'm found very useful size, See below.
http://www.linuxfoundation.org/colla..._netlink_howto
So. I'm create two kernel module.
new_netlink_family.ko : add new netlink family to kernel.
example_on_kernel.ko : Send netlink msg to new netlink family.
When insmod example_on_kernel.ko, I'm want to see "doc_exmpl_echo() : called"
But, I'm can't see this message.
Please help me.
file name : new_netlink_family.c
Code:
1 #include <linux/kernel.h>
2 #include <linux/init.h>
3 #include <net/genetlink.h>
4 #include "new_netlink_family.h"
5
6
7 /* handler */
8 static int doc_exmpl_echo(struct sk_buff *skb,
9 struct genl_info *info)
10 {
11 printk(KERN_ALERT "%s() : called\n", __FUNCTION__);
12 return 0;
13 };
14
15 /* Operation definition */
16 static struct genl_ops doc_exmpl_gnl_ops_echo = {
17 .cmd = DOC_EXMPL_C_ECHO,
18 .flags = 0,
19 .policy = doc_exmpl_genl_policy,
20 .doit = doc_exmpl_echo,
21 .dumpit = NULL,
22 };
23
24
25 static int new_netlink_family_init(void)
26 {
27 int ret;
28
29 printk(KERN_ALERT "%s() : called\n", __FUNCTION__);
30
31 ret = genl_register_family(&doc_exmpl_gnl_family);
32 if (ret != 0){
33 printk(KERN_ALERT "%s() : genl_register_family() fail\n", __FUNCTION__);
34 goto FAILURE;
35 }
36
37 ret = genl_register_ops(&doc_exmpl_gnl_family, &doc_exmpl_gnl_ops_echo);
38 if (ret != 0){
39 printk(KERN_ALERT "%s() : genl_register_ops() fail\n", __FUNCTION__);
40
41 ret = genl_unregister_family(&doc_exmpl_gnl_family);
42 goto FAILURE;
43 }
44
45 return 0;
46
47 FAILURE:
48 return -ENOMEM;
49 }
50
51 void example_netlink_exit(void)
52 {
53 int ret;
54
55 ret = genl_unregister_ops(&doc_exmpl_gnl_family, &doc_exmpl_gnl_ops_echo);
56 ret = genl_unregister_family(&doc_exmpl_gnl_family);
57 }
58
59
60
61 module_init(new_netlink_family_init);
62 module_exit(example_netlink_exit);
63 MODULE_LICENSE("Dual BSD/GPL");
file name : new_netlink_family.h
Code:
1 #ifndef __NEW_NETLINK_FAMILY_H__
2 #define __NEW_NETLINK_FAMILY_H__
3
4 /* attributes */
5 enum {
6 DOC_EXMPL_A_UNSPEC,
7 DOC_EXMPL_A_MSG,
8 __DOC_EXMPL_A_MAX,
9 };
10
11 #define DOC_EXMPL_A_MAX (__DOC_EXMPL_A_MAX-1)
12
13 /* attribute policy */
14 static struct nla_policy doc_exmpl_genl_policy[DOC_EXMPL_A_MAX+1] = {
15 [DOC_EXMPL_A_MSG] = {.type = NLA_NUL_STRING},
16 };
17
18
19 /* family defination */
20 static struct genl_family doc_exmpl_gnl_family = {
21 .id = GENL_ID_GENERATE,
22 .hdrsize = 0,
23 .name = "DOC_EXMPL",
24 .version = 1,
25 .maxattr = DOC_EXMPL_A_MAX,
26 };
27
28
29 /* commands */
30 enum {
31 DOC_EXMPL_C_UNSPEC,
32 DOC_EXMPL_C_ECHO,
33 __DOC_EXMPL_C_MAX,
34 };
35
36 #define DOC_EXMPL_C_MAX (__DOC_EXMPL_C_MAX -1)
37
38 #endif /* __NEW_NETLINK_FAMILY_H__ */
file name : example_on_kernel.c
Code:
1 #include <net/netlink.h>
2 #include <net/genetlink.h>
3
4 #include "new_netlink_family.h"
5
6 #if 0
7 /* family defination */
8 static struct genl_family doc_exmpl_gnl_family = {
9 .id = GENL_ID_GENERATE,
10 .hdrsize = 0,
11 .name = "DOC_EXMPL",
12 .version = 1,
13 .maxattr = DOC_EXMPL_A_MAX,
14 };
15 #endif
16
17 static int __msg_test(const char *msg)
18 {
19 int rc;
20 void *msg_head = NULL;
21 struct sk_buff *skb = NULL;
22
23 printk(KERN_ALERT "%s() : called\n", __FUNCTION__);
24
25 skb = genlmsg_new(NLMSG_GOODSIZE, GFP_KERNEL);
26 if (skb == NULL){
27 printk(KERN_ALERT "%s() : genlmsg_new() fail\n", __FUNCTION__);
28 rc = -ENOMEM;
29 goto FAILURE;
30 }
31
32 /* Create the message headers */
33 msg_head = genlmsg_put(skb, 0, 0, &doc_exmpl_gnl_family, 0, DOC_EXMPL_C_ECHO);
34 if (msg_head == NULL){
35 printk(KERN_ALERT "%s() : genlmsg_put() fail\n", __FUNCTION__);
36 rc = -ENOMEM;
37 goto FAILURE;
38 }
39
40 /* add a DOC_EXMPL_A_MSG attribute */
41 rc = nla_put_string(skb, DOC_EXMPL_A_MSG, msg);
42 if (rc != 0){
43 printk(KERN_ALERT "%s() : nla_put_string() fail\n", __FUNCTION__);
44 rc = -ENOMEM;
45 goto FAILURE;
46 }
47
48 /* finalize the message */
49 rc = genlmsg_end(skb, msg_head);
50 if (rc < 0){
51 printk(KERN_ALERT "%s() : genlmsg_end() fail\n", __FUNCTION__);
52 rc = -ENOMEM;
53 goto FAILURE;
54 }
55
56 rc = genlmsg_unicast(&init_net, skb, 0);
57 if (rc != 0){
58 printk(KERN_ALERT "%s() : genlmsg_unicast() fail\n", __FUNCTION__);
59 rc = -ENOMEM;
60 goto FAILURE;
61 }
62
63 return 0;
64
65 FAILURE:
66 /* skb free api 필요함 */
67 nlmsg_free(skb);
68 return rc;
69 };
70
71 int example_on_kernel_init(void)
72 {
73 int ret = 0;
74
75 printk(KERN_ALERT "%s() : called\n", __FUNCTION__);
76
77 ret = __msg_test("BABO");
78 if (ret < 0){
79 printk(KERN_ALERT "%s() : __msg_test is fail [ %d ]\n", __FUNCTION__, ret);
80 return -ENOMEM;
81 }
82
83 return 0;
84 }
85
86 void example_on_kernel_exit(void)
87 {
88 }
89
90 module_init(example_on_kernel_init);
91 module_exit(example_on_kernel_exit);
92
93 MODULE_LICENSE("Dual BSD/GPL");
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