| Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* Kernel module to match AH parameters. */ |
| 2 | /* (C) 1999-2000 Yon Uriarte <yon@astaro.de> |
| 3 | * |
| 4 | * This program is free software; you can redistribute it and/or modify |
| 5 | * it under the terms of the GNU General Public License version 2 as |
| 6 | * published by the Free Software Foundation. |
| 7 | */ |
| 8 | |
| 9 | #include <linux/module.h> |
| 10 | #include <linux/skbuff.h> |
| 11 | #include <linux/ip.h> |
| 12 | |
| 13 | #include <linux/netfilter_ipv4/ipt_ah.h> |
| 14 | #include <linux/netfilter_ipv4/ip_tables.h> |
| 15 | |
| 16 | MODULE_LICENSE("GPL"); |
| 17 | MODULE_AUTHOR("Yon Uriarte <yon@astaro.de>"); |
| 18 | MODULE_DESCRIPTION("iptables AH SPI match module"); |
| 19 | |
| 20 | #ifdef DEBUG_CONNTRACK |
| 21 | #define duprintf(format, args...) printk(format , ## args) |
| 22 | #else |
| 23 | #define duprintf(format, args...) |
| 24 | #endif |
| 25 | |
| 26 | /* Returns 1 if the spi is matched by the range, 0 otherwise */ |
| 27 | static inline int |
| 28 | spi_match(u_int32_t min, u_int32_t max, u_int32_t spi, int invert) |
| 29 | { |
| 30 | int r=0; |
| 31 | duprintf("ah spi_match:%c 0x%x <= 0x%x <= 0x%x",invert? '!':' ', |
| 32 | min,spi,max); |
| 33 | r=(spi >= min && spi <= max) ^ invert; |
| 34 | duprintf(" result %s\n",r? "PASS" : "FAILED"); |
| 35 | return r; |
| 36 | } |
| 37 | |
| 38 | static int |
| 39 | match(const struct sk_buff *skb, |
| 40 | const struct net_device *in, |
| 41 | const struct net_device *out, |
| 42 | const void *matchinfo, |
| 43 | int offset, |
| 44 | int *hotdrop) |
| 45 | { |
| 46 | struct ip_auth_hdr _ahdr, *ah; |
| 47 | const struct ipt_ah *ahinfo = matchinfo; |
| 48 | |
| 49 | /* Must not be a fragment. */ |
| 50 | if (offset) |
| 51 | return 0; |
| 52 | |
| 53 | ah = skb_header_pointer(skb, skb->nh.iph->ihl * 4, |
| 54 | sizeof(_ahdr), &_ahdr); |
| 55 | if (ah == NULL) { |
| 56 | /* We've been asked to examine this packet, and we |
| 57 | * can't. Hence, no choice but to drop. |
| 58 | */ |
| 59 | duprintf("Dropping evil AH tinygram.\n"); |
| 60 | *hotdrop = 1; |
| 61 | return 0; |
| 62 | } |
| 63 | |
| 64 | return spi_match(ahinfo->spis[0], ahinfo->spis[1], |
| 65 | ntohl(ah->spi), |
| 66 | !!(ahinfo->invflags & IPT_AH_INV_SPI)); |
| 67 | } |
| 68 | |
| 69 | /* Called when user tries to insert an entry of this type. */ |
| 70 | static int |
| 71 | checkentry(const char *tablename, |
| 72 | const struct ipt_ip *ip, |
| 73 | void *matchinfo, |
| 74 | unsigned int matchinfosize, |
| 75 | unsigned int hook_mask) |
| 76 | { |
| 77 | const struct ipt_ah *ahinfo = matchinfo; |
| 78 | |
| 79 | /* Must specify proto == AH, and no unknown invflags */ |
| 80 | if (ip->proto != IPPROTO_AH || (ip->invflags & IPT_INV_PROTO)) { |
| 81 | duprintf("ipt_ah: Protocol %u != %u\n", ip->proto, |
| 82 | IPPROTO_AH); |
| 83 | return 0; |
| 84 | } |
| 85 | if (matchinfosize != IPT_ALIGN(sizeof(struct ipt_ah))) { |
| 86 | duprintf("ipt_ah: matchsize %u != %u\n", |
| 87 | matchinfosize, IPT_ALIGN(sizeof(struct ipt_ah))); |
| 88 | return 0; |
| 89 | } |
| 90 | if (ahinfo->invflags & ~IPT_AH_INV_MASK) { |
| 91 | duprintf("ipt_ah: unknown flags %X\n", |
| 92 | ahinfo->invflags); |
| 93 | return 0; |
| 94 | } |
| 95 | |
| 96 | return 1; |
| 97 | } |
| 98 | |
| 99 | static struct ipt_match ah_match = { |
| 100 | .name = "ah", |
| 101 | .match = &match, |
| 102 | .checkentry = &checkentry, |
| 103 | .me = THIS_MODULE, |
| 104 | }; |
| 105 | |
| 106 | static int __init init(void) |
| 107 | { |
| 108 | return ipt_register_match(&ah_match); |
| 109 | } |
| 110 | |
| 111 | static void __exit cleanup(void) |
| 112 | { |
| 113 | ipt_unregister_match(&ah_match); |
| 114 | } |
| 115 | |
| 116 | module_init(init); |
| 117 | module_exit(cleanup); |