projects / deliverable / linux.git / blame
| Commit | Line | Data |
|---|---|---|
| 1da177e4 LT |
1 | /* module that allows mangling of the arp payload */ |
| 2 | #include <linux/module.h> | |
| 3 | #include <linux/netfilter_arp/arpt_mangle.h> | |
| 4 | #include <net/sock.h> | |
| 5 | ||
| 6 | MODULE_LICENSE("GPL"); | |
| 7 | MODULE_AUTHOR("Bart De Schuymer <bdschuym@pandora.be>"); | |
| 8 | MODULE_DESCRIPTION("arptables arp payload mangle target"); | |
| 9 | ||
| 10 | static unsigned int | |
| 11 | target(struct sk_buff **pskb, unsigned int hooknum, const struct net_device *in, | |
| 12 | const struct net_device *out, const void *targinfo, void *userinfo) | |
| 13 | { | |
| 14 | const struct arpt_mangle *mangle = targinfo; | |
| 15 | struct arphdr *arp; | |
| 16 | unsigned char *arpptr; | |
| 17 | int pln, hln; | |
| 18 | ||
| 19 | if (skb_shared(*pskb) || skb_cloned(*pskb)) { | |
| 20 | struct sk_buff *nskb; | |
| 21 | ||
| 22 | nskb = skb_copy(*pskb, GFP_ATOMIC); | |
| 23 | if (!nskb) | |
| 24 | return NF_DROP; | |
| 25 | if ((*pskb)->sk) | |
| 26 | skb_set_owner_w(nskb, (*pskb)->sk); | |
| 27 | kfree_skb(*pskb); | |
| 28 | *pskb = nskb; | |
| 29 | } | |
| 30 | ||
| 31 | arp = (*pskb)->nh.arph; | |
| 32 | arpptr = (*pskb)->nh.raw + sizeof(*arp); | |
| 33 | pln = arp->ar_pln; | |
| 34 | hln = arp->ar_hln; | |
| 35 | /* We assume that pln and hln were checked in the match */ | |
| 36 | if (mangle->flags & ARPT_MANGLE_SDEV) { | |
| 37 | if (ARPT_DEV_ADDR_LEN_MAX < hln || | |
| 38 | (arpptr + hln > (**pskb).tail)) | |
| 39 | return NF_DROP; | |
| 40 | memcpy(arpptr, mangle->src_devaddr, hln); | |
| 41 | } | |
| 42 | arpptr += hln; | |
| 43 | if (mangle->flags & ARPT_MANGLE_SIP) { | |
| 44 | if (ARPT_MANGLE_ADDR_LEN_MAX < pln || | |
| 45 | (arpptr + pln > (**pskb).tail)) | |
| 46 | return NF_DROP; | |
| 47 | memcpy(arpptr, &mangle->u_s.src_ip, pln); | |
| 48 | } | |
| 49 | arpptr += pln; | |
| 50 | if (mangle->flags & ARPT_MANGLE_TDEV) { | |
| 51 | if (ARPT_DEV_ADDR_LEN_MAX < hln || | |
| 52 | (arpptr + hln > (**pskb).tail)) | |
| 53 | return NF_DROP; | |
| 54 | memcpy(arpptr, mangle->tgt_devaddr, hln); | |
| 55 | } | |
| 56 | arpptr += hln; | |
| 57 | if (mangle->flags & ARPT_MANGLE_TIP) { | |
| 58 | if (ARPT_MANGLE_ADDR_LEN_MAX < pln || | |
| 59 | (arpptr + pln > (**pskb).tail)) | |
| 60 | return NF_DROP; | |
| 61 | memcpy(arpptr, &mangle->u_t.tgt_ip, pln); | |
| 62 | } | |
| 63 | return mangle->target; | |
| 64 | } | |
| 65 | ||
| 66 | static int | |
| 67 | checkentry(const char *tablename, const struct arpt_entry *e, void *targinfo, | |
| 68 | unsigned int targinfosize, unsigned int hook_mask) | |
| 69 | { | |
| 70 | const struct arpt_mangle *mangle = targinfo; | |
| 71 | ||
| 72 | if (mangle->flags & ~ARPT_MANGLE_MASK || | |
| 73 | !(mangle->flags & ARPT_MANGLE_MASK)) | |
| 74 | return 0; | |
| 75 | ||
| 76 | if (mangle->target != NF_DROP && mangle->target != NF_ACCEPT && | |
| 77 | mangle->target != ARPT_CONTINUE) | |
| 78 | return 0; | |
| 79 | return 1; | |
| 80 | } | |
| 81 | ||
| 82 | static struct arpt_target arpt_mangle_reg | |
| 83 | = { | |
| 84 | .name = "mangle", | |
| 85 | .target = target, | |
| 86 | .checkentry = checkentry, | |
| 87 | .me = THIS_MODULE, | |
| 88 | }; | |
| 89 | ||
| 90 | static int __init init(void) | |
| 91 | { | |
| 92 | if (arpt_register_target(&arpt_mangle_reg)) | |
| 93 | return -EINVAL; | |
| 94 | ||
| 95 | return 0; | |
| 96 | } | |
| 97 | ||
| 98 | static void __exit fini(void) | |
| 99 | { | |
| 100 | arpt_unregister_target(&arpt_mangle_reg); | |
| 101 | } | |
| 102 | ||
| 103 | module_init(init); | |
| 104 | module_exit(fini); |