mirror of
https://github.com/team-infusion-developers/android_kernel_samsung_msm8976.git
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176 lines
4.6 KiB
C
176 lines
4.6 KiB
C
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/* iptables module for the IPv4 and TCP ECN bits, Version 1.5
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*
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* (C) 2002 by Harald Welte <laforge@netfilter.org>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* ipt_ECN.c,v 1.5 2002/08/18 19:36:51 laforge Exp
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*/
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#include <linux/module.h>
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#include <linux/skbuff.h>
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#include <linux/ip.h>
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#include <linux/tcp.h>
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#include <net/checksum.h>
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#include <linux/netfilter_ipv4/ip_tables.h>
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#include <linux/netfilter_ipv4/ipt_ECN.h>
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
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MODULE_DESCRIPTION("iptables ECN modification module");
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/* set ECT codepoint from IP header.
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* return 0 if there was an error. */
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static inline int
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set_ect_ip(struct sk_buff **pskb, const struct ipt_ECN_info *einfo)
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{
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if (((*pskb)->nh.iph->tos & IPT_ECN_IP_MASK)
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!= (einfo->ip_ect & IPT_ECN_IP_MASK)) {
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u_int16_t diffs[2];
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if (!skb_ip_make_writable(pskb, sizeof(struct iphdr)))
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return 0;
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diffs[0] = htons((*pskb)->nh.iph->tos) ^ 0xFFFF;
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(*pskb)->nh.iph->tos &= ~IPT_ECN_IP_MASK;
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(*pskb)->nh.iph->tos |= (einfo->ip_ect & IPT_ECN_IP_MASK);
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diffs[1] = htons((*pskb)->nh.iph->tos);
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(*pskb)->nh.iph->check
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= csum_fold(csum_partial((char *)diffs,
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sizeof(diffs),
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(*pskb)->nh.iph->check
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^0xFFFF));
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(*pskb)->nfcache |= NFC_ALTERED;
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}
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return 1;
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}
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/* Return 0 if there was an error. */
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static inline int
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set_ect_tcp(struct sk_buff **pskb, const struct ipt_ECN_info *einfo, int inward)
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{
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struct tcphdr _tcph, *tcph;
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u_int16_t diffs[2];
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/* Not enought header? */
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tcph = skb_header_pointer(*pskb, (*pskb)->nh.iph->ihl*4,
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sizeof(_tcph), &_tcph);
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if (!tcph)
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return 0;
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if (!(einfo->operation & IPT_ECN_OP_SET_ECE
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|| tcph->ece == einfo->proto.tcp.ece)
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&& (!(einfo->operation & IPT_ECN_OP_SET_CWR
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|| tcph->cwr == einfo->proto.tcp.cwr)))
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return 1;
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if (!skb_ip_make_writable(pskb, (*pskb)->nh.iph->ihl*4+sizeof(*tcph)))
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return 0;
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tcph = (void *)(*pskb)->nh.iph + (*pskb)->nh.iph->ihl*4;
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diffs[0] = ((u_int16_t *)tcph)[6];
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if (einfo->operation & IPT_ECN_OP_SET_ECE)
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tcph->ece = einfo->proto.tcp.ece;
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if (einfo->operation & IPT_ECN_OP_SET_CWR)
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tcph->cwr = einfo->proto.tcp.cwr;
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diffs[1] = ((u_int16_t *)tcph)[6];
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diffs[0] = diffs[0] ^ 0xFFFF;
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if ((*pskb)->ip_summed != CHECKSUM_HW)
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tcph->check = csum_fold(csum_partial((char *)diffs,
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sizeof(diffs),
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tcph->check^0xFFFF));
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else
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if (skb_checksum_help(*pskb, inward))
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return 0;
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(*pskb)->nfcache |= NFC_ALTERED;
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return 1;
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}
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static unsigned int
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target(struct sk_buff **pskb,
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const struct net_device *in,
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const struct net_device *out,
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unsigned int hooknum,
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const void *targinfo,
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void *userinfo)
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{
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const struct ipt_ECN_info *einfo = targinfo;
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if (einfo->operation & IPT_ECN_OP_SET_IP)
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if (!set_ect_ip(pskb, einfo))
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return NF_DROP;
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if (einfo->operation & (IPT_ECN_OP_SET_ECE | IPT_ECN_OP_SET_CWR)
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&& (*pskb)->nh.iph->protocol == IPPROTO_TCP)
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if (!set_ect_tcp(pskb, einfo, (out == NULL)))
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return NF_DROP;
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return IPT_CONTINUE;
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}
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static int
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checkentry(const char *tablename,
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const struct ipt_entry *e,
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void *targinfo,
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unsigned int targinfosize,
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unsigned int hook_mask)
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{
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const struct ipt_ECN_info *einfo = (struct ipt_ECN_info *)targinfo;
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if (targinfosize != IPT_ALIGN(sizeof(struct ipt_ECN_info))) {
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printk(KERN_WARNING "ECN: targinfosize %u != %Zu\n",
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targinfosize,
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IPT_ALIGN(sizeof(struct ipt_ECN_info)));
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return 0;
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}
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if (strcmp(tablename, "mangle") != 0) {
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printk(KERN_WARNING "ECN: can only be called from \"mangle\" table, not \"%s\"\n", tablename);
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return 0;
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}
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if (einfo->operation & IPT_ECN_OP_MASK) {
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printk(KERN_WARNING "ECN: unsupported ECN operation %x\n",
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einfo->operation);
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return 0;
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}
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if (einfo->ip_ect & ~IPT_ECN_IP_MASK) {
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printk(KERN_WARNING "ECN: new ECT codepoint %x out of mask\n",
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einfo->ip_ect);
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return 0;
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}
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if ((einfo->operation & (IPT_ECN_OP_SET_ECE|IPT_ECN_OP_SET_CWR))
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&& (e->ip.proto != IPPROTO_TCP || (e->ip.invflags & IPT_INV_PROTO))) {
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printk(KERN_WARNING "ECN: cannot use TCP operations on a "
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"non-tcp rule\n");
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return 0;
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}
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return 1;
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}
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static struct ipt_target ipt_ecn_reg = {
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.name = "ECN",
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.target = target,
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.checkentry = checkentry,
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.me = THIS_MODULE,
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};
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static int __init init(void)
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{
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return ipt_register_target(&ipt_ecn_reg);
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}
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static void __exit fini(void)
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{
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ipt_unregister_target(&ipt_ecn_reg);
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}
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module_init(init);
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module_exit(fini);
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