made siphash more generic and finished cookie calculation code

src/siphash24.c

@@ -4,6 +4,7 @@
    <jeanphilippe.aumasson@gmail.com>
    Copyright (c) 2012-2014 Daniel J. Bernstein <djb@cr.yp.to>
    Copyright (c) 2016 Maximilian Muenchow <maximilian.muenchow@teamspeak.com>
+   Copyright (c) 2016 Niels Werensteijn <niels.werensteijn@teamspeak.com>
    To the extent possible under law, the author(s) have dedicated all copyright
    and related and neighboring rights to this software to the public domain
    worldwide. This software is distributed without any warranty.
@@ -13,7 +14,7 @@
    <http://creativecommons.org/publicdomain/zero/1.0/>.
 */
 
-#include <linux/kernel.h>
+#include "siphash24.h"
 
 
 /* default: SipHash-2-4 */
@@ -58,57 +59,129 @@
 #define TRACE
 #endif
 
-// it is assumed that every parameter is in LE
-int ts3init_siphash(u64 *out, const u8 *in, u64 inlen, u64 k0, u64 k1) {
+void ts3init_siphash_setup(struct ts3init_siphash_state* state, u64 k0, u64 k1)
+{
   /* "somepseudorandomlygeneratedbytes" */
-  u64 v0 = 0x736f6d6570736575ULL;
-  u64 v1 = 0x646f72616e646f6dULL;
-  u64 v2 = 0x6c7967656e657261ULL;
-  u64 v3 = 0x7465646279746573ULL;
-  u64 b;
-  u64 m;
-  int i;
-  const u8 *end = in + inlen - (inlen % sizeof(u64));
-  const int left = inlen & 7;
+  state->v0 = 0x736f6d6570736575ULL;
+  state->v1 = 0x646f72616e646f6dULL;
+  state->v2 = 0x6c7967656e657261ULL;
+  state->v3 = 0x7465646279746573ULL;
+  state->len= 0;
   k0 = le64_to_cpu(k0);
   k1 = le64_to_cpu(k1);
-  b = ((u64)inlen) << 56;
-  v3 ^= k1;
-  v2 ^= k0;
-  v1 ^= k1;
-  v0 ^= k0;
-
-  for (; in != end; in += 8) {
-    m = U8TO64_LE(in);
-    v3 ^= m;
-
-    TRACE;
-    for (i = 0; i < cROUNDS; ++i)
-      SIPROUND;
-
-    v0 ^= m;
-  }
-
-  switch (left) {
-  case 7:
-    b |= ((u64)in[6]) << 48;
-  case 6:
-    b |= ((u64)in[5]) << 40;
-  case 5:
-    b |= ((u64)in[4]) << 32;
-  case 4:
-    b |= ((u64)in[3]) << 24;
-  case 3:
-    b |= ((u64)in[2]) << 16;
-  case 2:
-    b |= ((u64)in[1]) << 8;
-  case 1:
-    b |= ((u64)in[0]);
-    break;
-  case 0:
-    break;
-  }
+  state->v3 ^= k1;
+  state->v2 ^= k0;
+  state->v1 ^= k1;
+  state->v0 ^= k0;
+}
+
+void ts3init_siphash_update(struct ts3init_siphash_state* state, const u8 *in, size_t inlen)
+{
+    size_t next_byte = state->len % 8;
+    size_t left;
+    const u8* end = in + inlen;
+    int i;
+    u64 m, v0, v1, v2, v3;
+
+    state->len += inlen;
+    m = state->m;
+    v0 = state->v0;
+    v1 = state->v1;
+    v2 = state->v2;
+    v3 = state->v3;
+        
+    switch (next_byte)
+    {
+    case 1:
+        m |= ((u64)(*in++)) << 8;
+        if (in==end) goto __exit_update;
+    case 2:
+        m |= ((u64)(*in++)) << 16;
+        if (in==end) goto __exit_update;
+    case 3:
+        m |= ((u64)(*in++)) << 24;
+        if (in==end) goto __exit_update;
+    case 4:
+        m |= ((u64)(*in++)) << 32;
+        if (in==end) goto __exit_update;
+    case 5:
+        m |= ((u64)(*in++)) << 40;
+        if (in==end) goto __exit_update;
+    case 6:
+        m |= ((u64)(*in++)) << 48;
+        if (in==end) goto __exit_update;
+    case 7:
+        m |= ((u64)(*in++)) << 56;
+       
+        v3 ^= m;
+
+        TRACE;
+        for (i = 0; i < cROUNDS; ++i)
+          SIPROUND;
+
+        v0 ^= m;
+    case 0:
+        break;
+    }
+    
+    left = (end-in) % 8;
+    end -= left;
+    
+    for (; in != end; in += 8)
+    {
+        m = U8TO64_LE(in);
+        v3 ^= m;
+
+        TRACE;
+        for (i = 0; i < cROUNDS; ++i)
+            SIPROUND;
+
+        v0 ^= m;
+    }
+    
+    m=0;
+    switch(left)
+    {
+        case 7:
+            m |= ((u64)(in[6])) << 48;
+        case 6:
+            m |= ((u64)(in[5])) << 40;
+        case 5:
+            m |= ((u64)(in[4])) << 32;
+        case 4:
+            m |= ((u64)(in[3])) << 24;
+        case 3:
+            m |= ((u64)(in[2])) << 16;
+        case 2:
+            m |= ((u64)(in[1])) << 8;
+        case 1:
+            m |= ((u64)(in[0]));
+        case 0:
+            break;
+    }
+    
+__exit_update:    
+    state->m = m;
+    state->v0 = v0;
+    state->v1 = v1;
+    state->v2 = v2;
+    state->v3 = v3;
+}
+
+u64 ts3init_siphash_finalize(struct ts3init_siphash_state* state)
+{
+  u64 b = state->len << 56;
+  u64 v0, v1, v2, v3;
+  int i;
+
+  b |= state->m;
+
 
+  v0 = state->v0;
+  v1 = state->v1;
+  v2 = state->v2;
+  v3 = state->v3;
+  
   v3 ^= b;
 
   TRACE;
@@ -123,9 +196,6 @@ int ts3init_siphash(u64 *out, const u8 *in, u64 inlen, u64 k0, u64 k1) {
     SIPROUND;
 
   b = v0 ^ v1 ^ v2 ^ v3;
-  *out = cpu_to_le64(b);
-
-
-  return 0;
+  return cpu_to_le64(b);
 }
 

src/ts3init_cookie.c

@@ -16,6 +16,8 @@
 #include <linux/crypto.h>
 #include <linux/err.h>
 #include <linux/scatterlist.h>
+#include <linux/netfilter/x_tables.h>
+#include "siphash24.h"
 #include "ts3init_cookie.h"
 
 static void check_update_seed_cache(time_t time, __u8 index, 
@@ -80,7 +82,7 @@ __u64* ts3init_get_cookie_seed(time_t current_time, __u8 packet_index,
     /* get cache time of packet */
     current_cache_time = current_time & ~((time_t)3);
     packet_cache_time = current_cache_time 
-		- ((current_cache_index ^ packet_cache_index)*4);
+        - ((current_cache_index ^ packet_cache_index)*4);
 
     /* make sure the cache is up-to-date */
     check_update_seed_cache(packet_cache_time, packet_cache_index, cache,
@@ -90,3 +92,41 @@ __u64* ts3init_get_cookie_seed(time_t current_time, __u8 packet_index,
     return cache->seed64 + ((SIP_KEY_SIZE/sizeof(__u64)) * packet_index );
 }
 
+int ts3init_calculate_cookie(const struct sk_buff *skb, struct xt_action_param *par, struct udphdr *udp, u64 k0, u64 k1, __u64* out)
+{
+    int addr_offset;
+    int addr_len;
+    void* addr_data;
+    __u8 addr_buf[2*16];
+    struct ts3init_siphash_state hash_state;
+
+    switch (par->family)
+    {
+    case NFPROTO_IPV4:
+        addr_offset = 12; /*offset to src and dst address in ipv4 header */
+        addr_len = 2*4; /*size of ipv4 address is 4 bytes */
+        break;
+
+    case NFPROTO_IPV6:
+        addr_offset = 8; /*offset to src and dst address in ipv6 header */
+        addr_len = 2*16; /*size of ipv6 address is 16 bytes */
+        break;
+    default:
+        printk(KERN_ERR KBUILD_MODNAME ": invalid family\n");
+        return -EINVAL;
+    }
+
+    addr_data = skb_header_pointer(skb, skb->network_header+addr_offset, addr_len, addr_buf);
+    if (!addr_data)
+    {
+        printk(KERN_ERR KBUILD_MODNAME ": could not load ip addresses\n");
+        return -EINVAL;
+    }
+ 
+    ts3init_siphash_setup(&hash_state, k0, k1);
+    ts3init_siphash_update(&hash_state, (u8 *)addr_data, addr_len);
+    ts3init_siphash_update(&hash_state, (u8 *)&udp->source, 4);
+    *out = ts3init_siphash_finalize(&hash_state);
+    
+    return 0;
+}

src/ts3init_cookie.h

@@ -20,4 +20,8 @@ __u64* ts3init_get_cookie_seed(time_t current_time, __u8 packet_index,
                 struct xt_ts3init_cookie_cache* cache,
                 const __u8* cookie_seed);
 
+int ts3init_calculate_cookie(const struct sk_buff *skb,
+                struct xt_action_param *par, struct udphdr *udp,
+                u64 k0, u64 k1, __u64* out);
+                
 #endif /* _TS3INIT_COOKIE_H */

src/ts3init_match.c

@@ -190,6 +190,7 @@ ts3init_get_puzzle_mt(const struct sk_buff *skb, struct xt_action_param *par)
         struct ts3init_cache_t* cache;
         struct ts3_init_header* ts3_header = header_data.ts3_header;
         __u64* cookie_seed, cookie_seed0, cookie_seed1;
+        __u64 cookie, packet_cookie;
 
         unsigned long jifs;
         time_t current_unix_time;
@@ -218,12 +219,18 @@ ts3init_get_puzzle_mt(const struct sk_buff *skb, struct xt_action_param *par)
 
         /* use cookie_seed and ipaddress and port to create a hash
          * (cookie) for this connection */
-        /* TODO: implement using sipHash */ 
+        if (ts3init_calculate_cookie(skb, par, header_data.udp, cookie_seed0, cookie_seed1, &cookie))
+            return false; /*something went wrong*/
 
         /* compare cookie with payload bytes 0-7. if equal, cookie
          * is valid */
-        /*if (memcmp(cookie, ts3_header->payload, 8) != 0) return false;*/
-
+         
+        packet_cookie = (((u64)((ts3_header->payload)[0])) | ((u64)((ts3_header->payload)[1]) << 8) |
+           ((u64)((ts3_header->payload)[2]) << 16) | ((u64)((ts3_header->payload)[3]) << 24) |
+           ((u64)((ts3_header->payload)[4]) << 32) | ((u64)((ts3_header->payload)[5]) << 40) |
+           ((u64)((ts3_header->payload)[6]) << 48) | ((u64)((ts3_header->payload)[7]) << 56));
+           
+        if (packet_cookie != cookie) return false;
     }
     return true;
 }