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158 lines
4.6 KiB
158 lines
4.6 KiB
/* |
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* "ts3init" extension for Xtables |
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* |
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* Description: A module to aid in ts3 spoof protection |
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* This is the "cookie" related code |
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* |
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* Authors: |
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* Niels Werensteijn <niels werensteijn [at] teampseak com>, 2016-10-03 |
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* |
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* This program is free software; you can redistribute it and/or modify it |
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* under the terms of the GNU General Public License; either version 2 |
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* or 3 of the License, as published by the Free Software Foundation. |
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*/ |
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#include <linux/init.h> |
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#include <linux/version.h> |
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#include <linux/kernel.h> |
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#include <linux/time.h> |
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#include <crypto/hash.h> |
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#include <linux/err.h> |
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#include <linux/scatterlist.h> |
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#include <linux/netfilter/x_tables.h> |
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#include <linux/ip.h> |
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#include <linux/ipv6.h> |
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#include <linux/udp.h> |
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#include "siphash24.h" |
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#include "ts3init_random_seed.h" |
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#include "ts3init_cookie.h" |
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#ifndef HAS_CRYPTO_HASH_INFO |
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#define TS3_SHA_512_NAME "sha512" |
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#else |
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#include <crypto/hash_info.h> |
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#define TS3_SHA_512_NAME hash_algo_name[HASH_ALGO_SHA512] |
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#endif |
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#if LINUX_VERSION_CODE < KERNEL_VERSION(3, 18, 0) |
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#define SHASH_DESC_ON_STACK(shash, ctx) \ |
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char __##shash##_desc[sizeof(struct shash_desc) + \ |
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crypto_shash_descsize(ctx)] CRYPTO_MINALIGN_ATTR; \ |
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struct shash_desc *shash = (struct shash_desc *)__##shash##_desc |
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#endif |
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static struct crypto_shash *sha512_tfm; |
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static void check_update_seed_cache(time_t time, __u8 index, |
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struct xt_ts3init_cookie_cache* cache, |
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const __u8* random_seed) |
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{ |
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int ret; |
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__le32 seed_hash_time; |
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if (time == cache->time[index]) return; |
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/* We need to update the cache. */ |
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/* seed = sha512(random_seed[RANDOM_SEED_LEN] + __le32 time) */ |
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seed_hash_time = cpu_to_le32( (__u32)time); |
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{ |
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SHASH_DESC_ON_STACK(shash, sha512_tfm); |
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shash->tfm = sha512_tfm; |
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shash->flags = 0; |
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ret = crypto_shash_init(shash); |
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if (ret != 0) |
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{ |
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printk(KERN_ERR KBUILD_MODNAME ": could not initalize sha512\n"); |
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return; |
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} |
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ret = crypto_shash_update(shash, random_seed, RANDOM_SEED_LEN); |
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if (ret != 0) |
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{ |
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printk(KERN_ERR KBUILD_MODNAME ": could not update sha512\n"); |
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return; |
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} |
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ret = crypto_shash_finup(shash, (u8*)&seed_hash_time, 4, |
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cache->seed8 + index * SHA512_SIZE); |
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if (ret != 0) |
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{ |
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printk(KERN_ERR KBUILD_MODNAME ": could not finup sha512\n"); |
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return; |
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} |
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cache->time[index] = time; |
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} |
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} |
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__u64* ts3init_get_cookie_seed(time_t current_time, __u8 packet_index, |
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struct xt_ts3init_cookie_cache* cache, |
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const __u8* random_seed) |
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{ |
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__u8 current_cache_index; |
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__u8 packet_cache_index; |
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time_t current_cache_time; |
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time_t packet_cache_time; |
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if (packet_index >= 8) return NULL; |
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current_cache_index = (current_time % 8) / 4; |
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packet_cache_index = packet_index / 4; |
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/* get cache time of packet */ |
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current_cache_time = current_time & ~((time_t)3); |
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packet_cache_time = current_cache_time |
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- ((current_cache_index ^ packet_cache_index)*4); |
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/* make sure the cache is up-to-date */ |
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check_update_seed_cache(packet_cache_time, packet_cache_index, cache, |
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random_seed); |
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/* return the proper seed */ |
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return cache->seed64 + ((SIP_KEY_SIZE/sizeof(__u64)) * packet_index ); |
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} |
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int ts3init_calculate_cookie_ipv6(const struct ipv6hdr *ip, const struct udphdr *udp, |
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__u64 k0, __u64 k1, __u64* out) |
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{ |
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struct ts3init_siphash_state hash_state; |
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ts3init_siphash_setup(&hash_state, k0, k1); |
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ts3init_siphash_update(&hash_state, (u8 *)&ip->saddr, sizeof(ip->saddr) * 2); |
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ts3init_siphash_update(&hash_state, (u8 *)&udp->source, 4); |
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*out = ts3init_siphash_finalize(&hash_state); |
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return 0; |
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} |
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int ts3init_calculate_cookie_ipv4(const struct iphdr *ip, const struct udphdr *udp, |
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__u64 k0, __u64 k1, __u64* out) |
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{ |
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struct ts3init_siphash_state hash_state; |
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ts3init_siphash_setup(&hash_state, k0, k1); |
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ts3init_siphash_update(&hash_state, (u8 *)&ip->saddr, sizeof(ip->saddr) * 2); |
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ts3init_siphash_update(&hash_state, (u8 *)&udp->source, 4); |
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*out = ts3init_siphash_finalize(&hash_state); |
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return 0; |
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} |
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int __init ts3init_cookie_init(void) |
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{ |
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sha512_tfm = crypto_alloc_shash(TS3_SHA_512_NAME, 0, 0); |
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if (IS_ERR(sha512_tfm)) |
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{ |
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printk(KERN_ERR KBUILD_MODNAME ": could not alloc sha512\n"); |
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return (int) PTR_ERR(sha512_tfm); |
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} |
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return 0; |
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} |
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void ts3init_cookie_exit(void) |
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{ |
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crypto_free_shash(sha512_tfm); |
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} |
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