-/* iptables module for the IPv4 and TCP ECN bits, Version 1.5
+/* IP tables module for matching the value of the IPv4 and TCP ECN bits
+ *
+ * ipt_ecn.c,v 1.3 2002/05/29 15:09:00 laforge Exp
+ *
+ * (C) 2002 by Harald Welte <laforge@gnumonks.org>
*
- * (C) 2002 by Harald Welte <laforge@netfilter.org>
- *
* This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 as
+ * it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
- *
- * ipt_ECN.c,v 1.5 2002/08/18 19:36:51 laforge Exp
-*/
+ */
#include <linux/module.h>
#include <linux/skbuff.h>
-#include <linux/ip.h>
#include <linux/tcp.h>
-#include <net/checksum.h>
#include <linux/netfilter_ipv4/ip_tables.h>
-#include <linux/netfilter_ipv4/ipt_ECN.h>
+#include <linux/netfilter_ipv4/ipt_ecn.h>
-MODULE_LICENSE("GPL");
MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
-MODULE_DESCRIPTION("iptables ECN modification module");
+MODULE_DESCRIPTION("iptables ECN matching module");
+MODULE_LICENSE("GPL");
-/* set ECT codepoint from IP header.
- * return 0 if there was an error. */
-static inline int
-set_ect_ip(struct sk_buff **pskb, const struct ipt_ECN_info *einfo)
+static inline int match_ip(const struct sk_buff *skb,
+ const struct ipt_ecn_info *einfo)
{
- if (((*pskb)->nh.iph->tos & IPT_ECN_IP_MASK)
- != (einfo->ip_ect & IPT_ECN_IP_MASK)) {
- u_int16_t diffs[2];
-
- if (!skb_ip_make_writable(pskb, sizeof(struct iphdr)))
- return 0;
-
- diffs[0] = htons((*pskb)->nh.iph->tos) ^ 0xFFFF;
- (*pskb)->nh.iph->tos &= ~IPT_ECN_IP_MASK;
- (*pskb)->nh.iph->tos |= (einfo->ip_ect & IPT_ECN_IP_MASK);
- diffs[1] = htons((*pskb)->nh.iph->tos);
- (*pskb)->nh.iph->check
- = csum_fold(csum_partial((char *)diffs,
- sizeof(diffs),
- (*pskb)->nh.iph->check
- ^0xFFFF));
- (*pskb)->nfcache |= NFC_ALTERED;
- }
- return 1;
+ return ((skb->nh.iph->tos&IPT_ECN_IP_MASK) == einfo->ip_ect);
}
-/* Return 0 if there was an error. */
-static inline int
-set_ect_tcp(struct sk_buff **pskb, const struct ipt_ECN_info *einfo, int inward)
+static inline int match_tcp(const struct sk_buff *skb,
+ const struct ipt_ecn_info *einfo,
+ int *hotdrop)
{
struct tcphdr tcph;
- u_int16_t diffs[2];
- /* Not enought header? */
- if (skb_copy_bits(*pskb, (*pskb)->nh.iph->ihl*4, &tcph, sizeof(tcph))
- < 0)
+ /* In practice, TCP match does this, so can't fail. But let's
+ be good citizens. */
+ if (skb_copy_bits(skb, skb->nh.iph->ihl*4, &tcph, sizeof(tcph)) < 0) {
+ *hotdrop = 0;
return 0;
+ }
- diffs[0] = ((u_int16_t *)&tcph)[6];
- if (einfo->operation & IPT_ECN_OP_SET_ECE)
- tcph.ece = einfo->proto.tcp.ece;
-
- if (einfo->operation & IPT_ECN_OP_SET_CWR)
- tcph.cwr = einfo->proto.tcp.cwr;
- diffs[1] = ((u_int16_t *)&tcph)[6];
+ if (einfo->operation & IPT_ECN_OP_MATCH_ECE) {
+ if (einfo->invert & IPT_ECN_OP_MATCH_ECE) {
+ if (tcph.ece == 1)
+ return 0;
+ } else {
+ if (tcph.ece == 0)
+ return 0;
+ }
+ }
- /* Only mangle if it's changed. */
- if (diffs[0] != diffs[1]) {
- diffs[0] = diffs[0] ^ 0xFFFF;
- if (!skb_ip_make_writable(pskb,
- (*pskb)->nh.iph->ihl*4+sizeof(tcph)))
- return 0;
- if ((*pskb)->ip_summed != CHECKSUM_HW)
- tcph.check = csum_fold(csum_partial((char *)diffs,
- sizeof(diffs),
- tcph.check^0xFFFF));
- memcpy((*pskb)->data + (*pskb)->nh.iph->ihl*4,
- &tcph, sizeof(tcph));
- if ((*pskb)->ip_summed == CHECKSUM_HW)
- if (skb_checksum_help(pskb, inward))
+ if (einfo->operation & IPT_ECN_OP_MATCH_CWR) {
+ if (einfo->invert & IPT_ECN_OP_MATCH_CWR) {
+ if (tcph.cwr == 1)
+ return 0;
+ } else {
+ if (tcph.cwr == 0)
return 0;
- (*pskb)->nfcache |= NFC_ALTERED;
+ }
}
+
return 1;
}
-static unsigned int
-target(struct sk_buff **pskb,
- const struct net_device *in,
- const struct net_device *out,
- unsigned int hooknum,
- const void *targinfo,
- void *userinfo)
+static int match(const struct sk_buff *skb, const struct net_device *in,
+ const struct net_device *out, const void *matchinfo,
+ int offset, int *hotdrop)
{
- const struct ipt_ECN_info *einfo = targinfo;
+ const struct ipt_ecn_info *info = matchinfo;
- if (einfo->operation & IPT_ECN_OP_SET_IP)
- if (!set_ect_ip(pskb, einfo))
- return NF_DROP;
+ if (info->operation & IPT_ECN_OP_MATCH_IP)
+ if (!match_ip(skb, info))
+ return 0;
- if (einfo->operation & (IPT_ECN_OP_SET_ECE | IPT_ECN_OP_SET_CWR)
- && (*pskb)->nh.iph->protocol == IPPROTO_TCP)
- if (!set_ect_tcp(pskb, einfo, (out == NULL)))
- return NF_DROP;
+ if (info->operation & (IPT_ECN_OP_MATCH_ECE|IPT_ECN_OP_MATCH_CWR)) {
+ if (skb->nh.iph->protocol != IPPROTO_TCP)
+ return 0;
+ if (!match_tcp(skb, info, hotdrop))
+ return 0;
+ }
- return IPT_CONTINUE;
+ return 1;
}
-static int
-checkentry(const char *tablename,
- const struct ipt_entry *e,
- void *targinfo,
- unsigned int targinfosize,
- unsigned int hook_mask)
+static int checkentry(const char *tablename, const struct ipt_ip *ip,
+ void *matchinfo, unsigned int matchsize,
+ unsigned int hook_mask)
{
- const struct ipt_ECN_info *einfo = (struct ipt_ECN_info *)targinfo;
+ const struct ipt_ecn_info *info = matchinfo;
- if (targinfosize != IPT_ALIGN(sizeof(struct ipt_ECN_info))) {
- printk(KERN_WARNING "ECN: targinfosize %u != %Zu\n",
- targinfosize,
- IPT_ALIGN(sizeof(struct ipt_ECN_info)));
+ if (matchsize != IPT_ALIGN(sizeof(struct ipt_ecn_info)))
return 0;
- }
- if (strcmp(tablename, "mangle") != 0) {
- printk(KERN_WARNING "ECN: can only be called from \"mangle\" table, not \"%s\"\n", tablename);
+ if (info->operation & IPT_ECN_OP_MATCH_MASK)
return 0;
- }
- if (einfo->operation & IPT_ECN_OP_MASK) {
- printk(KERN_WARNING "ECN: unsupported ECN operation %x\n",
- einfo->operation);
+ if (info->invert & IPT_ECN_OP_MATCH_MASK)
return 0;
- }
- if (einfo->ip_ect & ~IPT_ECN_IP_MASK) {
- printk(KERN_WARNING "ECN: new ECT codepoint %x out of mask\n",
- einfo->ip_ect);
- return 0;
- }
- if ((einfo->operation & (IPT_ECN_OP_SET_ECE|IPT_ECN_OP_SET_CWR))
- && e->ip.proto != IPPROTO_TCP) {
- printk(KERN_WARNING "ECN: cannot use TCP operations on a "
- "non-tcp rule\n");
+ if (info->operation & (IPT_ECN_OP_MATCH_ECE|IPT_ECN_OP_MATCH_CWR)
+ && ip->proto != IPPROTO_TCP) {
+ printk(KERN_WARNING "ipt_ecn: can't match TCP bits in rule for"
+ " non-tcp packets\n");
return 0;
}
return 1;
}
-static struct ipt_target ipt_ecn_reg = {
- .name = "ECN",
- .target = target,
- .checkentry = checkentry,
+static struct ipt_match ecn_match = {
+ .name = "ecn",
+ .match = &match,
+ .checkentry = &checkentry,
.me = THIS_MODULE,
};
static int __init init(void)
{
- return ipt_register_target(&ipt_ecn_reg);
+ return ipt_register_match(&ecn_match);
}
static void __exit fini(void)
{
- ipt_unregister_target(&ipt_ecn_reg);
+ ipt_unregister_match(&ecn_match);
}
module_init(init);