| /* Kernel module to match AH parameters. */ |
| /* (C) 1999-2000 Yon Uriarte <yon@astaro.de> |
| * |
| * 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 |
| * published by the Free Software Foundation. |
| */ |
| |
| #include <linux/module.h> |
| #include <linux/skbuff.h> |
| #include <linux/ip.h> |
| |
| #include <linux/netfilter_ipv4/ipt_ah.h> |
| #include <linux/netfilter_ipv4/ip_tables.h> |
| |
| MODULE_LICENSE("GPL"); |
| MODULE_AUTHOR("Yon Uriarte <yon@astaro.de>"); |
| MODULE_DESCRIPTION("iptables AH SPI match module"); |
| |
| #ifdef DEBUG_CONNTRACK |
| #define duprintf(format, args...) printk(format , ## args) |
| #else |
| #define duprintf(format, args...) |
| #endif |
| |
| /* Returns 1 if the spi is matched by the range, 0 otherwise */ |
| static inline int |
| spi_match(u_int32_t min, u_int32_t max, u_int32_t spi, int invert) |
| { |
| int r=0; |
| duprintf("ah spi_match:%c 0x%x <= 0x%x <= 0x%x",invert? '!':' ', |
| min,spi,max); |
| r=(spi >= min && spi <= max) ^ invert; |
| duprintf(" result %s\n",r? "PASS" : "FAILED"); |
| return r; |
| } |
| |
| 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) |
| { |
| struct ip_auth_hdr _ahdr, *ah; |
| const struct ipt_ah *ahinfo = matchinfo; |
| |
| /* Must not be a fragment. */ |
| if (offset) |
| return 0; |
| |
| ah = skb_header_pointer(skb, skb->nh.iph->ihl * 4, |
| sizeof(_ahdr), &_ahdr); |
| if (ah == NULL) { |
| /* We've been asked to examine this packet, and we |
| * can't. Hence, no choice but to drop. |
| */ |
| duprintf("Dropping evil AH tinygram.\n"); |
| *hotdrop = 1; |
| return 0; |
| } |
| |
| return spi_match(ahinfo->spis[0], ahinfo->spis[1], |
| ntohl(ah->spi), |
| !!(ahinfo->invflags & IPT_AH_INV_SPI)); |
| } |
| |
| /* Called when user tries to insert an entry of this type. */ |
| static int |
| checkentry(const char *tablename, |
| const struct ipt_ip *ip, |
| void *matchinfo, |
| unsigned int matchinfosize, |
| unsigned int hook_mask) |
| { |
| const struct ipt_ah *ahinfo = matchinfo; |
| |
| /* Must specify proto == AH, and no unknown invflags */ |
| if (ip->proto != IPPROTO_AH || (ip->invflags & IPT_INV_PROTO)) { |
| duprintf("ipt_ah: Protocol %u != %u\n", ip->proto, |
| IPPROTO_AH); |
| return 0; |
| } |
| if (matchinfosize != IPT_ALIGN(sizeof(struct ipt_ah))) { |
| duprintf("ipt_ah: matchsize %u != %u\n", |
| matchinfosize, IPT_ALIGN(sizeof(struct ipt_ah))); |
| return 0; |
| } |
| if (ahinfo->invflags & ~IPT_AH_INV_MASK) { |
| duprintf("ipt_ah: unknown flags %X\n", |
| ahinfo->invflags); |
| return 0; |
| } |
| |
| return 1; |
| } |
| |
| static struct ipt_match ah_match = { |
| .name = "ah", |
| .match = &match, |
| .checkentry = &checkentry, |
| .me = THIS_MODULE, |
| }; |
| |
| static int __init init(void) |
| { |
| return ipt_register_match(&ah_match); |
| } |
| |
| static void __exit cleanup(void) |
| { |
| ipt_unregister_match(&ah_match); |
| } |
| |
| module_init(init); |
| module_exit(cleanup); |