1 /* module that allows mangling of the arp payload */
2 #include <linux/module.h>
3 #include <linux/netfilter_arp/arpt_mangle.h>
7 MODULE_AUTHOR("Bart De Schuymer <bdschuym@pandora.be>");
8 MODULE_DESCRIPTION("arptables arp payload mangle target");
11 target(struct sk_buff
**pskb
, const struct net_device
*in
,
12 const struct net_device
*out
, unsigned int hooknum
, const void *targinfo
,
15 const struct arpt_mangle
*mangle
= targinfo
;
17 unsigned char *arpptr
;
20 if (skb_shared(*pskb
) || skb_cloned(*pskb
)) {
23 nskb
= skb_copy(*pskb
, GFP_ATOMIC
);
27 skb_set_owner_w(nskb
, (*pskb
)->sk
);
32 arp
= (*pskb
)->nh
.arph
;
33 arpptr
= (*pskb
)->nh
.raw
+ sizeof(*arp
);
36 /* We assume that pln and hln were checked in the match */
37 if (mangle
->flags
& ARPT_MANGLE_SDEV
) {
38 if (ARPT_DEV_ADDR_LEN_MAX
< hln
||
39 (arpptr
+ hln
> (**pskb
).tail
))
41 memcpy(arpptr
, mangle
->src_devaddr
, hln
);
44 if (mangle
->flags
& ARPT_MANGLE_SIP
) {
45 if (ARPT_MANGLE_ADDR_LEN_MAX
< pln
||
46 (arpptr
+ pln
> (**pskb
).tail
))
48 memcpy(arpptr
, &mangle
->u_s
.src_ip
, pln
);
51 if (mangle
->flags
& ARPT_MANGLE_TDEV
) {
52 if (ARPT_DEV_ADDR_LEN_MAX
< hln
||
53 (arpptr
+ hln
> (**pskb
).tail
))
55 memcpy(arpptr
, mangle
->tgt_devaddr
, hln
);
58 if (mangle
->flags
& ARPT_MANGLE_TIP
) {
59 if (ARPT_MANGLE_ADDR_LEN_MAX
< pln
||
60 (arpptr
+ pln
> (**pskb
).tail
))
62 memcpy(arpptr
, &mangle
->u_t
.tgt_ip
, pln
);
64 return mangle
->target
;
68 checkentry(const char *tablename
, const void *e
, void *targinfo
,
69 unsigned int targinfosize
, unsigned int hook_mask
)
71 const struct arpt_mangle
*mangle
= targinfo
;
73 if (mangle
->flags
& ~ARPT_MANGLE_MASK
||
74 !(mangle
->flags
& ARPT_MANGLE_MASK
))
77 if (mangle
->target
!= NF_DROP
&& mangle
->target
!= NF_ACCEPT
&&
78 mangle
->target
!= ARPT_CONTINUE
)
83 static struct arpt_target arpt_mangle_reg
87 .checkentry
= checkentry
,
91 static int __init
init(void)
93 if (arpt_register_target(&arpt_mangle_reg
))
99 static void __exit
fini(void)
101 arpt_unregister_target(&arpt_mangle_reg
);