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92 lines
2.6 KiB
92 lines
2.6 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/kernel.h> |
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#include <linux/time.h> |
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#include <linux/crypto.h> |
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#include <linux/err.h> |
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#include <linux/scatterlist.h> |
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#include "ts3init_cookie.h" |
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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* cookie_seed) |
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{ |
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struct hash_desc desc; |
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struct scatterlist sg[2]; |
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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(cookie_seed[60] + __le32 time) */ |
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seed_hash_time = cpu_to_le32( (__u32)time); |
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sg_init_table(sg, ARRAY_SIZE(sg)); |
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sg_set_buf(&sg[0], cookie_seed, 60); |
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sg_set_buf(&sg[1], &seed_hash_time, 4); |
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desc.tfm = crypto_alloc_hash("sha512", 0, 0); |
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desc.flags = 0; |
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if (IS_ERR(desc.tfm)) |
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{ |
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printk(KERN_ERR KBUILD_MODNAME ": could not alloc sha512\n"); |
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return; |
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} |
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ret = crypto_hash_init(&desc); |
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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_hash_digest(&desc, sg, 64, cache->seed + 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 digest sha512\n"); |
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return; |
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} |
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crypto_free_hash(desc.tfm); |
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} |
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__u8* 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* cookie_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 >> 2) & 1; |
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packet_cache_index = packet_index >> 2 /* &1 */; |
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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_index == packet_cache_index ? |
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current_cache_time : current_cache_time - (1*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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cookie_seed); |
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/* return the proper seed */ |
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return cache->seed + (SIP_KEY_SIZE * packet_index ); |
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} |
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