Why I can't compile a simple netfilter hook module?
I'm using this Makefile: *obj-m += hello.o all: make -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules clean: make -C /lib/modules/$(shell uname -r)/build M=$(PWD) clean* The hello.c is this: *#include <linux/kernel.h> #include <linux/module.h> #include <linux/netfilter.h> #include <linux/netfilter_ipv4.h> static struct nf_hook_ops nfho; //struct holding set of hook function options //function to be called by hook 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 *)) { printk(KERN_INFO "packet dropped\n"); //log to var/log/messages return NF_DROP; //drops the packet } //Called when module loaded using 'insmod' int init_module() { nfho.hook = hook_func; //function to call when conditions below met nfho.hooknum = NF_IP_PRE_ROUTING; //called right after packet recieved, first hook in Netfilter nfho.pf = PF_INET; //IPV4 packets nfho.priority = NF_IP_PRI_FIRST; //set to highest priority over all other hook functions nf_register_hook(&nfho); //register hook return 0; //return 0 for success } //Called when module unloaded using 'rmmod' void cleanup_module() { nf_unregister_hook(&nfho); //cleanup – unregister hook }* Here are the error message: *$ make make -C /lib/modules/3.3.2-6.fc16.x86_64/build M=/home/fabio/Desktop/modules modules make[1]: Entering directory `/usr/src/kernels/3.3.2-6.fc16.x86_64' CC [M] /home/fabio/Desktop/modules/hello.o /home/fabio/Desktop/modules/hello.c: In function ‘init_module’: /home/fabio/Desktop/modules/hello.c:18:13: warning: assignment from incompatible pointer type [enabled by default] /home/fabio/Desktop/modules/hello.c:19:18: error: ‘NF_IP_PRE_ROUTING’ undeclared (first use in this function) /home/fabio/Desktop/modules/hello.c:19:18: note: each undeclared identifier is reported only once for each function it appears in make[2]: *** [/home/fabio/Desktop/modules/hello.o] Error 1 make[1]: *** [_module_/home/fabio/Desktop/modules] Error 2 make[1]: Leaving directory `/usr/src/kernels/3.3.2-6.fc16.x86_64' make: *** [all] Error 2*
On Tue, May 8, 2012 at 9:37 AM, Chir0n <io.chir0n@gmail.com> wrote:
I'm using this Makefile:
*obj-m += hello.o
all: make -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules
clean: make -C /lib/modules/$(shell uname -r)/build M=$(PWD) clean*
The hello.c is this:
*#include <linux/kernel.h> #include <linux/module.h> #include <linux/netfilter.h> #include <linux/netfilter_ipv4.h>
static struct nf_hook_ops nfho; //struct holding set of hook function options
//function to be called by hook 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 *)) { printk(KERN_INFO "packet dropped\n"); //log to var/log/messages return NF_DROP; //drops the packet }
//Called when module loaded using 'insmod' int init_module() { nfho.hook = hook_func; //function to call when conditions below met nfho.hooknum = NF_IP_PRE_ROUTING; //called right after packet recieved, first hook in Netfilter nfho.pf = PF_INET; //IPV4 packets nfho.priority = NF_IP_PRI_FIRST; //set to highest priority over all other hook functions nf_register_hook(&nfho); //register hook
return 0; //return 0 for success }
//Called when module unloaded using 'rmmod' void cleanup_module() { nf_unregister_hook(&nfho); //cleanup – unregister hook }*
Here are the error message:
*$ make make -C /lib/modules/3.3.2-6.fc16.x86_64/build M=/home/fabio/Desktop/modules modules make[1]: Entering directory `/usr/src/kernels/3.3.2-6.fc16.x86_64' CC [M] /home/fabio/Desktop/modules/hello.o /home/fabio/Desktop/modules/hello.c: In function ‘init_module’: /home/fabio/Desktop/modules/hello.c:18:13: warning: assignment from incompatible pointer type [enabled by default] /home/fabio/Desktop/modules/hello.c:19:18: error: ‘NF_IP_PRE_ROUTING’ undeclared (first use in this function) /home/fabio/Desktop/modules/hello.c:19:18: note: each undeclared identifier is reported only once for each function it appears in make[2]: *** [/home/fabio/Desktop/modules/hello.o] Error 1 make[1]: *** [_module_/home/fabio/Desktop/modules] Error 2 make[1]: Leaving directory `/usr/src/kernels/3.3.2-6.fc16.x86_64' make: *** [all] Error 2*
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Hi,
You need to include header which defines "*NF_IP_PRE_ROUTING"* * * *- *Rohan
On Tue, 2012-05-08 at 09:49 +0530, rohan puri wrote:
On Tue, May 8, 2012 at 9:37 AM, Chir0n <io.chir0n@gmail.com> wrote: I'm using this Makefile:
obj-m += hello.o
all: make -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules
clean: make -C /lib/modules/$(shell uname -r)/build M=$(PWD) clean
The hello.c is this:
#include <linux/kernel.h> #include <linux/module.h> #include <linux/netfilter.h> #include <linux/netfilter_ipv4.h>
static struct nf_hook_ops nfho; //struct holding set of hook function options
//function to be called by hook 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 *)) { printk(KERN_INFO "packet dropped\n"); //log to var/log/messages return NF_DROP; //drops the packet }
//Called when module loaded using 'insmod' int init_module() { nfho.hook = hook_func; //function to call when conditions below met nfho.hooknum = NF_IP_PRE_ROUTING; //called right after packet recieved, first hook in Netfilter nfho.pf = PF_INET; //IPV4 packets nfho.priority = NF_IP_PRI_FIRST; //set to highest priority over all other hook functions nf_register_hook(&nfho); //register hook
return 0; //return 0 for success }
//Called when module unloaded using 'rmmod' void cleanup_module() { nf_unregister_hook(&nfho); //cleanup – unregister hook }
Here are the error message:
$ make make -C /lib/modules/3.3.2-6.fc16.x86_64/build M=/home/fabio/Desktop/modules modules make[1]: Entering directory `/usr/src/kernels/3.3.2-6.fc16.x86_64' CC [M] /home/fabio/Desktop/modules/hello.o /home/fabio/Desktop/modules/hello.c: In function ‘init_module’: /home/fabio/Desktop/modules/hello.c:18:13: warning: assignment from incompatible pointer type [enabled by default] /home/fabio/Desktop/modules/hello.c:19:18: error: ‘NF_IP_PRE_ROUTING’ undeclared (first use in this function) /home/fabio/Desktop/modules/hello.c:19:18: note: each undeclared identifier is reported only once for each function it appears in make[2]: *** [/home/fabio/Desktop/modules/hello.o] Error 1 make[1]: *** [_module_/home/fabio/Desktop/modules] Error 2 make[1]: Leaving directory `/usr/src/kernels/3.3.2-6.fc16.x86_64' make: *** [all] Error 2
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Hi,
You need to include header which defines "NF_IP_PRE_ROUTING"
- Rohan
Hi, But I have declared this header: #include <linux/netfilter_ipv4.h>
On Tue, May 8, 2012 at 9:37 AM, Chir0n <io.chir0n@gmail.com> wrote:
I'm using this Makefile:
*obj-m += hello.o
all: make -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules
clean: make -C /lib/modules/$(shell uname -r)/build M=$(PWD) clean*
The hello.c is this:
*#include <linux/kernel.h> #include <linux/module.h> #include <linux/netfilter.h> #include <linux/netfilter_ipv4.h>
static struct nf_hook_ops nfho; //struct holding set of hook function options
//function to be called by hook 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 *)) { printk(KERN_INFO "packet dropped\n"); //log to var/log/messages return NF_DROP; //drops the packet }
//Called when module loaded using 'insmod' int init_module() { nfho.hook = hook_func; //function to call when conditions below met nfho.hooknum = NF_IP_PRE_ROUTING; //called right after packet recieved, first hook in Netfilter nfho.pf = PF_INET; //IPV4 packets nfho.priority = NF_IP_PRI_FIRST; //set to highest priority over all other hook functions nf_register_hook(&nfho); //register hook
return 0; //return 0 for success }
//Called when module unloaded using 'rmmod' void cleanup_module() { nf_unregister_hook(&nfho); //cleanup – unregister hook }*
Here are the error message:
*$ make make -C /lib/modules/3.3.2-6.fc16.x86_64/build M=/home/fabio/Desktop/modules modules make[1]: Entering directory `/usr/src/kernels/3.3.2-6.fc16.x86_64' CC [M] /home/fabio/Desktop/modules/hello.o /home/fabio/Desktop/modules/hello.c: In function ‘init_module’: /home/fabio/Desktop/modules/hello.c:18:13: warning: assignment from incompatible pointer type [enabled by default] *
you may have declared the header, thn check whether the path is correct or the symbol name spelling.
* /home/fabio/Desktop/modules/hello.c:19:18: error: ‘NF_IP_PRE_ROUTING’ undeclared (first use in this function) /home/fabio/Desktop/modules/hello.c:19:18: note: each undeclared identifier is reported only once for each function it appears in make[2]: *** [/home/fabio/Desktop/modules/hello.o] Error 1 make[1]: *** [_module_/home/fabio/Desktop/modules] Error 2 make[1]: Leaving directory `/usr/src/kernels/3.3.2-6.fc16.x86_64' make: *** [all] Error 2*
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Also dont delete previous mail thread contents.
- Rohan
what is your kernel version? maybe you should use NF_INET_PRE_ROUTING instead. 2012-05-22 c265n46 发件人：Chir0n 发送时间：2012-05-08 12:14 主题：Why I can't compile a simple netfilter hook module? 收件人："kernelnewbies"<kernelnewbies@kernelnewbies.org> 抄送： I'm using this Makefile: obj-m += hello.o all: make -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules clean: make -C /lib/modules/$(shell uname -r)/build M=$(PWD) clean The hello.c is this: #include <linux/kernel.h> #include <linux/module.h> #include <linux/netfilter.h> #include <linux/netfilter_ipv4.h> static struct nf_hook_ops nfho; //struct holding set of hook function options //function to be called by hook 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 *)) { printk(KERN_INFO "packet dropped\n"); //log to var/log/messages return NF_DROP; //drops the packet } //Called when module loaded using 'insmod' int init_module() { nfho.hook = hook_func; //function to call when conditions below met nfho.hooknum = NF_IP_PRE_ROUTING; //called right after packet recieved, first hook in Netfilter nfho.pf = PF_INET; //IPV4 packets nfho.priority = NF_IP_PRI_FIRST; //set to highest priority over all other hook functions nf_register_hook(&nfho); //register hook return 0; //return 0 for success } //Called when module unloaded using 'rmmod' void cleanup_module() { nf_unregister_hook(&nfho); //cleanup – unregister hook } Here are the error message: $ make make -C /lib/modules/3.3.2-6.fc16.x86_64/build M=/home/fabio/Desktop/modules modules make[1]: Entering directory `/usr/src/kernels/3.3.2-6.fc16.x86_64' CC [M] /home/fabio/Desktop/modules/hello.o /home/fabio/Desktop/modules/hello.c: In function ‘init_module’: /home/fabio/Desktop/modules/hello.c:18:13: warning: assignment from incompatible pointer type [enabled by default] /home/fabio/Desktop/modules/hello.c:19:18: error: ‘NF_IP_PRE_ROUTING’ undeclared (first use in this function) /home/fabio/Desktop/modules/hello.c:19:18: note: each undeclared identifier is reported only once for each function it appears in make[2]: *** [/home/fabio/Desktop/modules/hello.o] Error 1 make[1]: *** [_module_/home/fabio/Desktop/modules] Error 2 make[1]: Leaving directory `/usr/src/kernels/3.3.2-6.fc16.x86_64' make: *** [all] Error 2
On Tue, May 08, 2012 at 01:07:43AM -0300, Chir0n wrote:
/home/fabio/Desktop/modules/hello.c:19:18: error: ‘NF_IP_PRE_ROUTING’ undeclared (first use in this function)
This symbol is declared in a section that's "only for userspace compatibility" (netfilter_ipv4.h, line 10). HTH, Jonathan Neuschäfer
participants (5)
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c265n46 -
Chir0n -
Dexter
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Jonathan Neuschäfer -
rohan puri