Running the following code,I want to accept IP packets are defined but dropping all packets.. where is the my error? please help me
struct iphdr* iph = ip_hdr(skb);
struct sk_buff *sb = *skb;
struct in_addr masterIP;
masterIP.s_addr = htonl (in_aton("192.168.1.10"));
iph->saddr = masterIP.s_addr;
return NF_ACCEPT;
Related
I'm working on writing a kernel hwmon driver module for a chip that communicates over LPC (ISA style bus). I have the following code so far
umode_t qnap_ec_is_visible(const void* data, enum hwmon_sensor_types type, u32 attr, int channel)
{
}
int qnap_ec_read(struct device* dev, enum hwmon_sensor_types type, u32 attr, int channel, long* val)
{
}
int qnap_ec_write(struct device* dev, enum hwmon_sensor_types type, u32 attr, int channel, long val)
{
}
static const struct hwmon_ops qnap_ec_ops = {
.is_visible = qnap_ec_is_visible,
.read = qnap_ec_read,
.write = qnap_ec_write
};
static const struct hwmon_channel_info *qnap_ec_channel_info[] = {
HWMON_CHANNEL_INFO(pwm, HWMON_PWM_INPUT),
HWMON_CHANNEL_INFO(fan, HWMON_F_INPUT),
HWMON_CHANNEL_INFO(temp, HWMON_T_INPUT),
NULL
};
static const struct hwmon_chip_info qnap_ec_chip_info = {
.ops = &qnap_ec_ops,
.info = qnap_ec_channel_info
};
static int qnap_ec_probe(struct platform_device* platform_dev)
{
struct device* dev;
dev = devm_hwmon_device_register_with_info(&platform_dev->dev, "qnap_ec_hwmon", NULL,
&qnap_ec_chip_info, NULL);
return PTR_ERR_OR_ZERO(dev);
}
static const struct of_device_id qnap_ec_of_match[] = {
{ .compatible = "???" },
{}
};
MODULE_DEVICE_TABLE(of, qnap_ec_of_match);
static struct platform_driver qnap_ec_driver = {
.driver = {
.name = "qnap_ec_hwmon",
.of_match_table = qnap_ec_of_match
},
.probe = qnap_ec_probe
};
module_platform_driver(qnap_ec_driver);
however I'm pretty sure this approach (using a device ID and having the kernel call the probe function when it finds that device ID on the system) won't work for something on the LPC bus. The IT87 driver which also communicates over the LPC bus uses __init/__exit functions to enter the driver, however, that driver is very large and probably not an ideal example of a simple driver module. Are there any examples available of how to write a basic (ie: no real functionality just the skeleton) kernel hwmon driver for a LPC device? Some of the things I can't find answers for, for example, is if I use the __init/__exit functions, can I still register the driver using the devm_hwmon_device_register_with_info function or do I need to use another approach (the it87 driver for example uses the platform_driver_register function, but I'm not sure why since there doesn't seem to be any documentation on the correct approach for LPC devices).
Disclaimer - I have to admit that it's the 1'st time I'm using this kernel interface (socket).
I'm currently working on a design of a kernel module that is based on a netlink socket .
I'm using Ubuntu14.04 and linux kernel 4.
As a starter, I wanted to make sure that I can use the netlink socket in both directions.
I've written an application that does the following:
1) User send a message to kernel via the netlink socket.
2) Kernel, upon receiving the message – sends "ABCD" string message to a workqueue.
3) When the "ABCD" message is received by the workqueue, it calls a function (named - my_wq_function) which send it back to the user space via netlink socket.
4) In the user space I'm using a recvmsg function (blocking until a message is received) and displays the "ABCD" message.
My problem is that the return value from the recvmsg function is 20 (instead of 4), and the data itself (i.e. NLMSG_DATA) is empty.
During the debug I tried to change the message to "ABCD1234" and got a return value of 24 bytes, however the data is still empty.
I also verified that my entire path until the point of sending the "ABCD" from kernel to the socket is OK.
Not sure what I'm doing wrong here & will highly appreciate your help.
Thanks in advance, MotiC.
my code example can be found below:
User space code:
printf("netlink receiver thread started...\n");
nlh_rcv = (struct nlmsghdr *)malloc(NLMSG_SPACE(MAX_PAYLOAD));
while(true) //endless loop on netlink socket
{
memset(nlh_rcv, 0, NLMSG_SPACE(MAX_PAYLOAD));
iov_rcv.iov_base = (void *)nlh_rcv;
iov_rcv.iov_len = nlh_rcv->nlmsg_len;
msg_rcv.msg_name = (void *)&dest_addr;
msg_rcv.msg_namelen = sizeof(dest_addr);
msg_rcv.msg_iov = &iov;
msg_rcv.msg_iovlen = 1;
ret=recvmsg(sock_fd, &msg_rcv, 0);
printf("errno=%i bytes=%i message from kernel: %s\n",errno, ret, (char*)NLMSG_DATA(nlh_rcv));
uint8_t mymsg[100];
memcpy(mymsg, NLMSG_DATA(nlh_rcv), 100);
printf("message from kernel: %s\n",mymsg);
}
Kernel space code:
#include <linux/module.h> /* Needed by all modules */
#include <linux/kernel.h> /* Needed for KERN_INFO */
#include <linux/init.h> /* Needed for the macros */
#include <net/sock.h>
#include <linux/socket.h>
#include <linux/net.h>
#include <asm/types.h>
#include <linux/netlink.h>
#include <linux/skbuff.h>
#include <linux/workqueue.h>
MODULE_LICENSE("GPL");
#include "rf_Kdriver_main.h"
//------ definitions ------------------------------------------------------------------------------------------------------------
#define NETLINK_USER 31
#define MAX_PAYLOAD 1024 /* maximum payload size*/
struct sock *nl_sk = NULL;
struct nlmsghdr *nlh;
struct nlmsghdr *nlh_out;
struct sk_buff *skb_out;
char buf_to_user[100];
int pid;
//------------------------------------------------------------------------------------------------------------------------------
struct workqueue_struct *my_wq;
typedef struct {
struct work_struct my_work;
uint8_t msg_to_pc[128];
uint8_t msg_len;
} my_work_t;
my_work_t *work, *work2;
//-----------------------------------------------------------------------------------------------------------------------------
static void my_wq_function( struct work_struct *work)
{
int res;
my_work_t *my_work = (my_work_t *)work;
skb_out = nlmsg_new(my_work->msg_len,0);
if (!skb_out)
{
printk("Failed to allocate new skb\n");
return;
}
nlh_out = nlmsg_put(skb_out, 0, 0, NLMSG_DONE,my_work->msg_len, 0);
NETLINK_CB(skb_out).dst_group = 0;
memcpy((char*)NLMSG_DATA(nlh_out), my_work->msg_to_pc , my_work->msg_len);
printk( "dequeue message to pc=%s len=%i\n", (char*)NLMSG_DATA(nlh_out), (int)strlen((char*)NLMSG_DATA(nlh_out)));
res = nlmsg_unicast(nl_sk, skb_out, pid);
if (res<0)
printk("Failed to send message from kernel to user\n");
kfree( (void *)work );
return;
}
//-----------------------------------------------------------------------------------------------------------------------------
int send_up_msg_to_workque(uint8_t msg_to_pc[], uint8_t msg_len)
{
int ret=0;
work = (my_work_t *)kmalloc(sizeof(my_work_t), GFP_KERNEL);
if (work) {
INIT_WORK( (struct work_struct *)work, my_wq_function );
memcpy(work->msg_to_pc, msg_to_pc, msg_len);
work->msg_len = msg_len;
ret = queue_work( my_wq, /*(struct work_struct *)RR*/work );
printk("kuku ret=%i msg=%s\n",ret,work->msg_to_pc);
}
return ret;
}
//------------------------------------------------------------------------------------------------------------------------------
static void netlink_recv_msg(struct sk_buff *skb)
{
char *msg = "ABCD1234";
printk(KERN_INFO "Entering: %s\n", __FUNCTION__);
nlh=(struct nlmsghdr*)skb->data;
printk(KERN_INFO "Netlink at kernel received msg payload: %s\n",(char*)NLMSG_DATA(nlh));
//rr
pid = nlh->nlmsg_pid;
send_up_msg_to_workque((uint8_t*) msg, strlen(msg));
}
//-------------------------------------------------------------------------------------------------------------------------------------
struct netlink_kernel_cfg cfg = {
.input = netlink_recv_msg,
};
static int __init rf_driver_start(void)
{
printk(KERN_INFO "Loading RF Driver module1...\n");
my_wq = create_workqueue("my_queue");
if (!my_wq)
{
printk("Failed to create work queue\n");
}
printk("Entering: %s\n",__FUNCTION__);
nl_sk = netlink_kernel_create(&init_net, NETLINK_USER, &cfg);
if(!nl_sk)
{
printk(KERN_ALERT "Error creating socket.\n");
return -10;
}
return 0;
}
//--------------------------------------------------------------------------------------------------------------
static void __exit rf_driver_end(void)
{
netlink_kernel_release(nl_sk);
flush_workqueue(my_wq);
destroy_workqueue(my_wq);
printk(KERN_INFO "RF Driver exit...\n");
}
module_init(rf_driver_start);
module_exit(rf_driver_end);
Update,
I changed my user space function to:
char buf[100];
ret=recv(sock_fd, buf, 100, 0);
instead of:
ret=recvmsg(sock_fd, &msg_rcv, 0);
and it works...
does anyone have an idea regarding this strange behavior ?
Thanks.
Can you please paste complete userspace code.
I guess 'len' int this code is the issue:
memset(nlh_rcv, 0, NLMSG_SPACE(MAX_PAYLOAD));
iov_rcv.iov_len = nlh_rcv->nlmsg_len; << check to what value is it getting initialized.
I'm trying to print TCP address but I'm getting "Dereferencing pointer to incomplete type" error. I think iphdr typecasting is not working. How do I fix this issue?
unsigned int hook_func(unsigned int hooknum,
struct sk_buff *skb,
const struct net_device *in,
const struct net_device *out,
int (*okfn)(struct sk_buff *))
{
struct iphdr *ip_header; // ip header struct
if (!skb)
return NF_ACCEPT;
ip_header = (struct iphdr *)skb_network_header(skb); /* I think this is not working */
printk("addr : %lu.\n",ip_header->saddr);
return NF_ACCEPT;
}
int init_module()
{
printk(KERN_INFO "initialize kernel module\n");
/* Fill in our hook structure */
nfho.hook = hook_func; /* Handler function */
nfho.hooknum = NF_INET_PRE_ROUTING; /* First hook for IPv4 */
nfho.pf = PF_INET;
nfho.priority = NF_IP_PRI_FIRST; /* Make our function first */
nf_register_hook(&nfho);
return 0;
}
For dereferece pointer of type struct iphdr you need
#include <linux/ip.h>
(Actually, this type is defined in include/uapi/linux/ip.h, but usually headers under uapi/ are included via other ones.)
I create my RPC Protocol with PB like:
enum EMessages {
E_MSG_METHOD_CONNECT = 0x8001,
E_MSG_EVENT_CONNECT = 0xA001,
...
}
struct MsgHeader {
required int32 sessionRef = 1;
required int32 transactionId = 2;
required int32 status = 3;
}
struct MSG_METHOD_CONNECT {
optional Messages opCode = 1 [default = E_MSG_METHOD_CONNECT];
required MsgHeader header = 2;
.. other fields ..
}
Now, I defined an interface and a template class to add a level of indirection:
class IMessage {
virtual INT getOpCode() = 0;
virtual STRING getName() = 0;
virtual size_t getSize() = 0;
virtual INT SerializeToString(STRING& out) = 0;
virtual INT ParseFromString(STRING& in) = 0;
....
}
template<class MESSAGE>
class IMessageImpl : public IMessage {
protected:
MESSAGE m_Message; ///< The Message Implementation
public:
virtual MESSAGE& getMessage() = 0;
};
And I will use it as:
IMessageImpl<MSG_METHOD_CONNECT> MsgConnect;
Now, when I receive the data from an endpoint I need, of course, to deserialize it according with the message opCode.
Reading this article I'm thinking to use a type map like boost::mpl::map but, since I never use it, I'm searching for some suggestions.
<< ------------------------ [EDIT] ------------------------ >>
Regarding the code above, I try to code it in the following way:
template<class MESSAGE>
class PBMessage : public IMessageImpl<MESSAGE>
{
public:
PBMessage() {};
/* ... other methods ... */
};
// Map of types. The key is the Message opCode
typedef typename mpl::map< mpl::pair<mpl::int_[100], PBMessage<MSG_METHOD_CONNECT> >,
mpl::pair<mpl::int_[101], PBMessage<MSG_EVENT_CONNECT> >,
> TMessageMap;
// The Message type
template < typename MessageMap, int opCode >
typedef typename mpl::at<MessageMap, mpl::int_<opCode> >::type::value TMessage;
And, to create a message from a received buffer I try to code (take it as pseudo-code):
class PBMessageFactory : public IMessageFactory {
public:
IMessage* createMessage(CHAR* buff, UINT size) {
int opCode = buff[0];
TMessage<TMessageMap, opCode> msg;
msg.ParseFromString( STRING(buff) );
}
};
But with no success...Is there someone could give me some suggestions how to retrieve types from a mpl::map?
Thanks,
Daniele.
I working on some code in the linux kernel (2.4) and for some reason kmalloc returns the same address (I believe it only happens after the middle of the test). I checked that no calls to kfree were made between the calls to kmalloc (i.e memory is still in use).
maybe I'm out of memory ? (kmalloc didn't return NULL...)
any ideas on how such a thing can happen ?
thanks in advance for the help!
code:
typedef struct
{
char* buffer;
int read_count;
int write_count;
struct semaphore read_sm;
struct semaphore write_sm;
int reader_ready;
int writer_ready;
int createTimeStamp;
} data_buffer_t ;
typedef struct vsf_t vsf_t;
struct vsf_t
{
int minor;
int type;
int open_count;
int waiting_pid;
data_buffer_t* data;
list_t proc_list;
vsf_t* otherSide_vsf;
int real_create_time_stamp;
};
int create_vsf(struct inode *inode, struct file *filp, struct vsf_command_parameters* parms)
{
...
buff_data = allocate_buffer();
if (buff_data == NULL)
{
kfree(this_vsfRead);
kfree(this_vsfWrite);
return -ENOMEM;
}
...
}
data_buffer_t* allocate_buffer()
{
...
data_buffer_t* this_buff = (data_buffer_t*)kmalloc(sizeof(data_buffer_t), GFP_KERNEL);
if (this_buff == NULL)
{
printk( KERN_WARNING "failure at allocating memory\n" );
return NULL;
}
...
return this_buff;
}
*I print after every kmalloc and kfree,I'm absolutely sure that no kfree is called between kmalloc's (that return the same adress)
I don't know what kmalloc's data structures look like but you could imagine this happening if a previous double free caused a cycle in a linked list of buffers. Further frees could still chain on additional distinct buffers (able to be reallocated) but once those were exhausted that last buffer would be returned indefinitely.