/* module that allows mangling of the arp payload */
#include <linux/module.h>
+#include <linux/netfilter.h>
#include <linux/netfilter_arp/arpt_mangle.h>
#include <net/sock.h>
MODULE_DESCRIPTION("arptables arp payload mangle target");
static unsigned int
-target(struct sk_buff **pskb,
+target(struct sk_buff *skb,
const struct net_device *in, const struct net_device *out,
unsigned int hooknum, const struct xt_target *target,
const void *targinfo)
{
const struct arpt_mangle *mangle = targinfo;
- struct arphdr *arp;
+ const struct arphdr *arp;
unsigned char *arpptr;
int pln, hln;
- if (skb_shared(*pskb) || skb_cloned(*pskb)) {
- struct sk_buff *nskb;
+ if (!skb_make_writable(skb, skb->len))
+ return NF_DROP;
- nskb = skb_copy(*pskb, GFP_ATOMIC);
- if (!nskb)
- return NF_DROP;
- if ((*pskb)->sk)
- skb_set_owner_w(nskb, (*pskb)->sk);
- kfree_skb(*pskb);
- *pskb = nskb;
- }
-
- arp = arp_hdr(*pskb);
- arpptr = skb_network_header(*pskb) + sizeof(*arp);
+ arp = arp_hdr(skb);
+ arpptr = skb_network_header(skb) + sizeof(*arp);
pln = arp->ar_pln;
hln = arp->ar_hln;
/* We assume that pln and hln were checked in the match */
if (mangle->flags & ARPT_MANGLE_SDEV) {
if (ARPT_DEV_ADDR_LEN_MAX < hln ||
- (arpptr + hln > skb_tail_pointer(*pskb)))
+ (arpptr + hln > skb_tail_pointer(skb)))
return NF_DROP;
memcpy(arpptr, mangle->src_devaddr, hln);
}
arpptr += hln;
if (mangle->flags & ARPT_MANGLE_SIP) {
if (ARPT_MANGLE_ADDR_LEN_MAX < pln ||
- (arpptr + pln > skb_tail_pointer(*pskb)))
+ (arpptr + pln > skb_tail_pointer(skb)))
return NF_DROP;
memcpy(arpptr, &mangle->u_s.src_ip, pln);
}
arpptr += pln;
if (mangle->flags & ARPT_MANGLE_TDEV) {
if (ARPT_DEV_ADDR_LEN_MAX < hln ||
- (arpptr + hln > skb_tail_pointer(*pskb)))
+ (arpptr + hln > skb_tail_pointer(skb)))
return NF_DROP;
memcpy(arpptr, mangle->tgt_devaddr, hln);
}
arpptr += hln;
if (mangle->flags & ARPT_MANGLE_TIP) {
if (ARPT_MANGLE_ADDR_LEN_MAX < pln ||
- (arpptr + pln > skb_tail_pointer(*pskb)))
+ (arpptr + pln > skb_tail_pointer(skb)))
return NF_DROP;
memcpy(arpptr, &mangle->u_t.tgt_ip, pln);
}
return mangle->target;
}
-static int
+static bool
checkentry(const char *tablename, const void *e, const struct xt_target *target,
void *targinfo, unsigned int hook_mask)
{
if (mangle->flags & ~ARPT_MANGLE_MASK ||
!(mangle->flags & ARPT_MANGLE_MASK))
- return 0;
+ return false;
if (mangle->target != NF_DROP && mangle->target != NF_ACCEPT &&
mangle->target != ARPT_CONTINUE)
- return 0;
- return 1;
+ return false;
+ return true;
}
-static struct arpt_target arpt_mangle_reg = {
+static struct xt_target arpt_mangle_reg __read_mostly = {
.name = "mangle",
+ .family = NF_ARP,
.target = target,
.targetsize = sizeof(struct arpt_mangle),
.checkentry = checkentry,
static int __init arpt_mangle_init(void)
{
- if (arpt_register_target(&arpt_mangle_reg))
- return -EINVAL;
-
- return 0;
+ return xt_register_target(&arpt_mangle_reg);
}
static void __exit arpt_mangle_fini(void)
{
- arpt_unregister_target(&arpt_mangle_reg);
+ xt_unregister_target(&arpt_mangle_reg);
}
module_init(arpt_mangle_init);