mptcp: use untruncated hash in ADD_ADDR HMAC

There is some ambiguity in the RFC as to whether the ADD_ADDR HMAC is
the rightmost 64 bits of the entire hash or of the leftmost 160 bits
of the hash.  The intention, as clarified with the author of the RFC,
is the entire hash.

This change returns the entire hash from
mptcp_crypto_hmac_sha (instead of only the first 160 bits), and moves
any truncation/selection operation on the hash to the caller.

Fixes: 12555a2d97e5 ("mptcp: use rightmost 64 bits in ADD_ADDR HMAC")
Reviewed-by: Christoph Paasch <cpaasch@apple.com>
Reviewed-by: Mat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: Todd Malsbary <todd.malsbary@linux.intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 9 insertions, 15 deletions

diff --git a/net/mptcp/crypto.c b/net/mptcp/crypto.c
index c151628bd416..0f5a414a9366 100644
--- a/net/mptcp/crypto.c
+++ b/net/mptcp/crypto.c
@@ -47,8 +47,6 @@ void mptcp_crypto_key_sha(u64 key, u32 *token, u64 *idsn)
 void mptcp_crypto_hmac_sha(u64 key1, u64 key2, u8 *msg, int len, void *hmac)
 {
 	u8 input[SHA256_BLOCK_SIZE + SHA256_DIGEST_SIZE];
-	__be32 mptcp_hashed_key[SHA256_DIGEST_WORDS];
-	__be32 *hash_out = (__force __be32 *)hmac;
 	struct sha256_state state;
 	u8 key1be[8];
 	u8 key2be[8];
@@ -86,11 +84,7 @@ void mptcp_crypto_hmac_sha(u64 key1, u64 key2, u8 *msg, int len, void *hmac)
 
 	sha256_init(&state);
 	sha256_update(&state, input, SHA256_BLOCK_SIZE + SHA256_DIGEST_SIZE);
-	sha256_final(&state, (u8 *)mptcp_hashed_key);
-
-	/* takes only first 160 bits */
-	for (i = 0; i < 5; i++)
-		hash_out[i] = mptcp_hashed_key[i];
+	sha256_final(&state, (u8 *)hmac);
 }
 
 #ifdef CONFIG_MPTCP_HMAC_TEST
@@ -101,29 +95,29 @@ struct test_cast {
 };
 
 /* we can't reuse RFC 4231 test vectors, as we have constraint on the
- * input and key size, and we truncate the output.
+ * input and key size.
  */
 static struct test_cast tests[] = {
 	{
 		.key = "0b0b0b0b0b0b0b0b",
 		.msg = "48692054",
-		.result = "8385e24fb4235ac37556b6b886db106284a1da67",
+		.result = "8385e24fb4235ac37556b6b886db106284a1da671699f46db1f235ec622dcafa",
 	},
 	{
 		.key = "aaaaaaaaaaaaaaaa",
 		.msg = "dddddddd",
-		.result = "2c5e219164ff1dca1c4a92318d847bb6b9d44492",
+		.result = "2c5e219164ff1dca1c4a92318d847bb6b9d44492984e1eb71aff9022f71046e9",
 	},
 	{
 		.key = "0102030405060708",
 		.msg = "cdcdcdcd",
-		.result = "e73b9ba9969969cefb04aa0d6df18ec2fcc075b6",
+		.result = "e73b9ba9969969cefb04aa0d6df18ec2fcc075b6f23b4d8c4da736a5dbbc6e7d",
 	},
 };
 
 static int __init test_mptcp_crypto(void)
 {
-	char hmac[20], hmac_hex[41];
+	char hmac[32], hmac_hex[65];
 	u32 nonce1, nonce2;
 	u64 key1, key2;
 	u8 msg[8];
@@ -140,11 +134,11 @@ static int __init test_mptcp_crypto(void)
 		put_unaligned_be32(nonce2, &msg[4]);
 
 		mptcp_crypto_hmac_sha(key1, key2, msg, 8, hmac);
-		for (j = 0; j < 20; ++j)
+		for (j = 0; j < 32; ++j)
 			sprintf(&hmac_hex[j << 1], "%02x", hmac[j] & 0xff);
-		hmac_hex[40] = 0;
+		hmac_hex[64] = 0;
 
-		if (memcmp(hmac_hex, tests[i].result, 40))
+		if (memcmp(hmac_hex, tests[i].result, 64))
 			pr_err("test %d failed, got %s expected %s", i,
 			       hmac_hex, tests[i].result);
 		else