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
,
12 const struct net_device
*in
, const struct net_device
*out
,
13 unsigned int hooknum
, const struct xt_target
*target
,
16 const struct arpt_mangle
*mangle
= targinfo
;
18 unsigned char *arpptr
;
21 if (skb_shared(*pskb
) || skb_cloned(*pskb
)) {
24 nskb
= skb_copy(*pskb
, GFP_ATOMIC
);
28 skb_set_owner_w(nskb
, (*pskb
)->sk
);
33 arp
= (*pskb
)->nh
.arph
;
34 arpptr
= (*pskb
)->nh
.raw
+ sizeof(*arp
);
37 /* We assume that pln and hln were checked in the match */
38 if (mangle
->flags
& ARPT_MANGLE_SDEV
) {
39 if (ARPT_DEV_ADDR_LEN_MAX
< hln
||
40 (arpptr
+ hln
> (**pskb
).tail
))
42 memcpy(arpptr
, mangle
->src_devaddr
, hln
);
45 if (mangle
->flags
& ARPT_MANGLE_SIP
) {
46 if (ARPT_MANGLE_ADDR_LEN_MAX
< pln
||
47 (arpptr
+ pln
> (**pskb
).tail
))
49 memcpy(arpptr
, &mangle
->u_s
.src_ip
, pln
);
52 if (mangle
->flags
& ARPT_MANGLE_TDEV
) {
53 if (ARPT_DEV_ADDR_LEN_MAX
< hln
||
54 (arpptr
+ hln
> (**pskb
).tail
))
56 memcpy(arpptr
, mangle
->tgt_devaddr
, hln
);
59 if (mangle
->flags
& ARPT_MANGLE_TIP
) {
60 if (ARPT_MANGLE_ADDR_LEN_MAX
< pln
||
61 (arpptr
+ pln
> (**pskb
).tail
))
63 memcpy(arpptr
, &mangle
->u_t
.tgt_ip
, pln
);
65 return mangle
->target
;
69 checkentry(const char *tablename
, const void *e
, const struct xt_target
*target
,
70 void *targinfo
, unsigned int targinfosize
, unsigned int hook_mask
)
72 const struct arpt_mangle
*mangle
= targinfo
;
74 if (mangle
->flags
& ~ARPT_MANGLE_MASK
||
75 !(mangle
->flags
& ARPT_MANGLE_MASK
))
78 if (mangle
->target
!= NF_DROP
&& mangle
->target
!= NF_ACCEPT
&&
79 mangle
->target
!= ARPT_CONTINUE
)
84 static struct arpt_target arpt_mangle_reg
= {
87 .targetsize
= sizeof(struct arpt_mangle
),
88 .checkentry
= checkentry
,
92 static int __init
arpt_mangle_init(void)
94 if (arpt_register_target(&arpt_mangle_reg
))
100 static void __exit
arpt_mangle_fini(void)
102 arpt_unregister_target(&arpt_mangle_reg
);
105 module_init(arpt_mangle_init
);
106 module_exit(arpt_mangle_fini
);