| /* This is a module which is used for setting the TOS field of a packet. */ |
| #include <linux/module.h> |
| #include <linux/skbuff.h> |
| #include <linux/ip.h> |
| #include <net/checksum.h> |
| |
| #include <linux/netfilter_ipv4/ip_tables.h> |
| #include <linux/netfilter_ipv4/ipt_TOS.h> |
| |
| static unsigned int |
| target(struct sk_buff **pskb, |
| unsigned int hooknum, |
| const struct net_device *in, |
| const struct net_device *out, |
| const void *targinfo, |
| void *userinfo) |
| { |
| struct iphdr *iph = (*pskb)->nh.iph; |
| const struct ipt_tos_target_info *tosinfo = targinfo; |
| |
| if ((iph->tos & IPTOS_TOS_MASK) != tosinfo->tos) { |
| u_int16_t diffs[2]; |
| |
| /* raw socket (tcpdump) may have clone of incoming |
| skb: don't disturb it --RR */ |
| if (skb_cloned(*pskb) && !(*pskb)->sk) { |
| struct sk_buff *nskb = skb_copy(*pskb, GFP_ATOMIC); |
| if (!nskb) |
| return NF_DROP; |
| kfree_skb(*pskb); |
| *pskb = nskb; |
| iph = (*pskb)->nh.iph; |
| } |
| |
| diffs[0] = htons(iph->tos) ^ 0xFFFF; |
| iph->tos = (iph->tos & IPTOS_PREC_MASK) | tosinfo->tos; |
| diffs[1] = htons(iph->tos); |
| iph->check = csum_fold(csum_partial((char *)diffs, |
| sizeof(diffs), |
| iph->check^0xFFFF)); |
| (*pskb)->nfcache |= NFC_ALTERED; |
| } |
| return IPT_CONTINUE; |
| } |
| |
| static int |
| checkentry(const char *tablename, |
| const struct ipt_entry *e, |
| void *targinfo, |
| unsigned int targinfosize, |
| unsigned int hook_mask) |
| { |
| const u_int8_t tos = ((struct ipt_tos_target_info *)targinfo)->tos; |
| |
| if (targinfosize != IPT_ALIGN(sizeof(struct ipt_tos_target_info))) { |
| printk(KERN_WARNING "TOS: targinfosize %u != %Zu\n", |
| targinfosize, |
| IPT_ALIGN(sizeof(struct ipt_tos_target_info))); |
| return 0; |
| } |
| |
| if (strcmp(tablename, "mangle") != 0) { |
| printk(KERN_WARNING "TOS: can only be called from \"mangle\" table, not \"%s\"\n", tablename); |
| return 0; |
| } |
| |
| if (tos != IPTOS_LOWDELAY |
| && tos != IPTOS_THROUGHPUT |
| && tos != IPTOS_RELIABILITY |
| && tos != IPTOS_MINCOST |
| && tos != IPTOS_NORMALSVC) { |
| printk(KERN_WARNING "TOS: bad tos value %#x\n", tos); |
| return 0; |
| } |
| |
| return 1; |
| } |
| |
| static struct ipt_target ipt_tos_reg |
| = { { NULL, NULL }, "TOS", target, checkentry, NULL, THIS_MODULE }; |
| |
| static int __init init(void) |
| { |
| if (ipt_register_target(&ipt_tos_reg)) |
| return -EINVAL; |
| |
| return 0; |
| } |
| |
| static void __exit fini(void) |
| { |
| ipt_unregister_target(&ipt_tos_reg); |
| } |
| |
| module_init(init); |
| module_exit(fini); |
| MODULE_LICENSE("GPL"); |