net/mptcp/crypto.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /* Multipath TCP cryptographic functions
   3  * Copyright (c) 2017 - 2019, Intel Corporation.
   4  *
   5  * Note: This code is based on mptcp_ctrl.c, mptcp_ipv4.c, and
   6  *       mptcp_ipv6 from multipath-tcp.org, authored by:
   7  *
   8  *       Sébastien Barré <sebastien.barre@uclouvain.be>
   9  *       Christoph Paasch <christoph.paasch@uclouvain.be>
  10  *       Jaakko Korkeaniemi <jaakko.korkeaniemi@aalto.fi>
  11  *       Gregory Detal <gregory.detal@uclouvain.be>
  12  *       Fabien Duchêne <fabien.duchene@uclouvain.be>
  13  *       Andreas Seelinger <Andreas.Seelinger@rwth-aachen.de>
  14  *       Lavkesh Lahngir <lavkesh51@gmail.com>
  15  *       Andreas Ripke <ripke@neclab.eu>
  16  *       Vlad Dogaru <vlad.dogaru@intel.com>
  17  *       Octavian Purdila <octavian.purdila@intel.com>
  18  *       John Ronan <jronan@tssg.org>
  19  *       Catalin Nicutar <catalin.nicutar@gmail.com>
  20  *       Brandon Heller <brandonh@stanford.edu>
  21  */
  22
  23 #include <linux/kernel.h>
  24 #include <crypto/sha.h>
  25 #include <asm/unaligned.h>
  26
  27 #include "protocol.h"
  28
  29 #define SHA256_DIGEST_WORDS (SHA256_DIGEST_SIZE / 4)
  30
  31 void mptcp_crypto_key_sha(u64 key, u32 *token, u64 *idsn)
  32 {
  33         __be32 mptcp_hashed_key[SHA256_DIGEST_WORDS];
  34         __be64 input = cpu_to_be64(key);
  35         struct sha256_state state;
  36
  37         sha256_init(&state);
  38         sha256_update(&state, (__force u8 *)&input, sizeof(input));
  39         sha256_final(&state, (u8 *)mptcp_hashed_key);
  40
  41         if (token)
  42                 *token = be32_to_cpu(mptcp_hashed_key[0]);
  43         if (idsn)
  44                 *idsn = be64_to_cpu(*((__be64 *)&mptcp_hashed_key[6]));
  45 }
  46
  47 void mptcp_crypto_hmac_sha(u64 key1, u64 key2, u8 *msg, int len, void *hmac)
  48 {
  49         u8 input[SHA256_BLOCK_SIZE + SHA256_DIGEST_SIZE];
  50         __be32 mptcp_hashed_key[SHA256_DIGEST_WORDS];
  51         __be32 *hash_out = (__force __be32 *)hmac;
  52         struct sha256_state state;
  53         u8 key1be[8];
  54         u8 key2be[8];
  55         int i;
  56
  57         if (WARN_ON_ONCE(len > SHA256_DIGEST_SIZE))
  58                 len = SHA256_DIGEST_SIZE;
  59
  60         put_unaligned_be64(key1, key1be);
  61         put_unaligned_be64(key2, key2be);
  62
  63         /* Generate key xored with ipad */
  64         memset(input, 0x36, SHA_MESSAGE_BYTES);
  65         for (i = 0; i < 8; i++)
  66                 input[i] ^= key1be[i];
  67         for (i = 0; i < 8; i++)
  68                 input[i + 8] ^= key2be[i];
  69
  70         memcpy(&input[SHA256_BLOCK_SIZE], msg, len);
  71
  72         sha256_init(&state);
  73         sha256_update(&state, input, SHA256_BLOCK_SIZE + len);
  74
  75         /* emit sha256(K1 || msg) on the second input block, so we can
  76          * reuse 'input' for the last hashing
  77          */
  78         sha256_final(&state, &input[SHA256_BLOCK_SIZE]);
  79
  80         /* Prepare second part of hmac */
  81         memset(input, 0x5C, SHA_MESSAGE_BYTES);
  82         for (i = 0; i < 8; i++)
  83                 input[i] ^= key1be[i];
  84         for (i = 0; i < 8; i++)
  85                 input[i + 8] ^= key2be[i];
  86
  87         sha256_init(&state);
  88         sha256_update(&state, input, SHA256_BLOCK_SIZE + SHA256_DIGEST_SIZE);
  89         sha256_final(&state, (u8 *)mptcp_hashed_key);
  90
  91         /* takes only first 160 bits */
  92         for (i = 0; i < 5; i++)
  93                 hash_out[i] = mptcp_hashed_key[i];
  94 }
  95
  96 #ifdef CONFIG_MPTCP_HMAC_TEST
  97 struct test_cast {
  98         char *key;
  99         char *msg;
 100         char *result;
 101 };
 102
 103 /* we can't reuse RFC 4231 test vectors, as we have constraint on the
 104  * input and key size, and we truncate the output.
 105  */
 106 static struct test_cast tests[] = {
 107         {
 108                 .key = "0b0b0b0b0b0b0b0b",
 109                 .msg = "48692054",
 110                 .result = "8385e24fb4235ac37556b6b886db106284a1da67",
 111         },
 112         {
 113                 .key = "aaaaaaaaaaaaaaaa",
 114                 .msg = "dddddddd",
 115                 .result = "2c5e219164ff1dca1c4a92318d847bb6b9d44492",
 116         },
 117         {
 118                 .key = "0102030405060708",
 119                 .msg = "cdcdcdcd",
 120                 .result = "e73b9ba9969969cefb04aa0d6df18ec2fcc075b6",
 121         },
 122 };
 123
 124 static int __init test_mptcp_crypto(void)
 125 {
 126         char hmac[20], hmac_hex[41];
 127         u32 nonce1, nonce2;
 128         u64 key1, key2;
 129         u8 msg[8];
 130         int i, j;
 131
 132         for (i = 0; i < ARRAY_SIZE(tests); ++i) {
 133                 /* mptcp hmap will convert to be before computing the hmac */
 134                 key1 = be64_to_cpu(*((__be64 *)&tests[i].key[0]));
 135                 key2 = be64_to_cpu(*((__be64 *)&tests[i].key[8]));
 136                 nonce1 = be32_to_cpu(*((__be32 *)&tests[i].msg[0]));
 137                 nonce2 = be32_to_cpu(*((__be32 *)&tests[i].msg[4]));
 138
 139                 put_unaligned_be32(nonce1, &msg[0]);
 140                 put_unaligned_be32(nonce2, &msg[4]);
 141
 142                 mptcp_crypto_hmac_sha(key1, key2, msg, 8, hmac);
 143                 for (j = 0; j < 20; ++j)
 144                         sprintf(&hmac_hex[j << 1], "%02x", hmac[j] & 0xff);
 145                 hmac_hex[40] = 0;
 146
 147                 if (memcmp(hmac_hex, tests[i].result, 40))
 148                         pr_err("test %d failed, got %s expected %s", i,
 149                                hmac_hex, tests[i].result);
 150                 else
 151                         pr_info("test %d [ ok ]", i);
 152         }
 153         return 0;
 154 }
 155
 156 late_initcall(test_mptcp_crypto);
 157 #endif