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/*
* Generic loadable firewalls. At the moment only IP will actually
* use these, but people can add the others as they are needed.
*
* Authors: Dave Bonn (for IP)
* much hacked by: Alan Cox
*/
#include <linux/module.h>
#include <linux/config.h>
#include <linux/skbuff.h>
#include <linux/firewall.h>
static int firewall_lock=0;
static int firewall_policy[NPROTO];
static struct firewall_ops *firewall_chain[NPROTO];
/*
* Register a firewall
*/
int register_firewall(int pf, struct firewall_ops *fw)
{
struct firewall_ops **p;
if(pf<0||pf>=NPROTO)
return -EINVAL;
/*
* Don't allow two people to adjust at once.
*/
while(firewall_lock)
schedule();
firewall_lock=1;
p=&firewall_chain[pf];
while(*p)
{
if(fw->fw_priority > (*p)->fw_priority)
break;
p=&((*p)->next);
}
/*
* We need to use a memory barrier to make sure that this
* works correctly even in SMP with weakly ordered writes.
*
* This is atomic wrt interrupts (and generally walking the
* chain), but not wrt itself (so you can't call this from
* an interrupt. Not that you'd want to).
*/
fw->next=*p;
mb();
*p = fw;
/*
* And release the sleep lock
*/
firewall_lock=0;
return 0;
}
/*
* Unregister a firewall
*/
int unregister_firewall(int pf, struct firewall_ops *fw)
{
struct firewall_ops **nl;
if(pf<0||pf>=NPROTO)
return -EINVAL;
/*
* Don't allow two people to adjust at once.
*/
while(firewall_lock)
schedule();
firewall_lock=1;
nl=&firewall_chain[pf];
while(*nl!=NULL)
{
if(*nl==fw)
{
struct firewall_ops *f=fw->next;
*nl = f;
firewall_lock=0;
return 0;
}
nl=&((*nl)->next);
}
firewall_lock=0;
return -ENOENT;
}
int call_fw_firewall(int pf, struct device *dev, void *phdr, void *arg)
{
struct firewall_ops *fw=firewall_chain[pf];
while(fw!=NULL)
{
int rc=fw->fw_forward(fw,pf,dev,phdr,arg);
if(rc!=FW_SKIP)
return rc;
fw=fw->next;
}
return firewall_policy[pf];
}
/*
* Actual invocation of the chains
*/
int call_in_firewall(int pf, struct device *dev, void *phdr, void *arg)
{
struct firewall_ops *fw=firewall_chain[pf];
while(fw!=NULL)
{
int rc=fw->fw_input(fw,pf,dev,phdr,arg);
if(rc!=FW_SKIP)
return rc;
fw=fw->next;
}
return firewall_policy[pf];
}
int call_out_firewall(int pf, struct device *dev, void *phdr, void *arg)
{
struct firewall_ops *fw=firewall_chain[pf];
while(fw!=NULL)
{
int rc=fw->fw_output(fw,pf,dev,phdr,arg);
if(rc!=FW_SKIP)
return rc;
fw=fw->next;
}
/* alan, is this right? */
return firewall_policy[pf];
}
static struct symbol_table firewall_syms = {
#include <linux/symtab_begin.h>
X(register_firewall),
X(unregister_firewall),
X(call_in_firewall),
X(call_out_firewall),
X(call_fw_firewall),
#include <linux/symtab_end.h>
};
void fwchain_init(void)
{
int i;
for(i=0;i<NPROTO;i++)
firewall_policy[i]=FW_ACCEPT;
register_symtab(&firewall_syms);
}
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