mptcp: move from sha1 (v0) to sha256 (v1)

For simplicity's sake use directly sha256 primitives (and pull them
as a required build dep).
Add optional, boot-time self-tests for the hmac function.

Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Christoph Paasch <cpaasch@apple.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/mptcp/Kconfig b/net/mptcp/Kconfig
index c1a99f0..5db56d2 100644 (file)
--- a/net/mptcp/Kconfig
+++ b/net/mptcp/Kconfig
@@ -3,6 +3,7 @@ config MPTCP
        bool "MPTCP: Multipath TCP"
        depends on INET
        select SKB_EXTENSIONS
+       select CRYPTO_LIB_SHA256
        help
          Multipath TCP (MPTCP) connections send and receive data over multiple
          subflows in order to utilize multiple network paths. Each subflow
@@ -14,3 +15,12 @@ config MPTCP_IPV6
        depends on MPTCP
        select IPV6
        default y
+
+config MPTCP_HMAC_TEST
+       bool "Tests for MPTCP HMAC implementation"
+       default n
+       help
+         This option enable boot time self-test for the HMAC implementation
+         used by the MPTCP code
+
+         Say N if you are unsure.

diff --git a/net/mptcp/crypto.c b/net/mptcp/crypto.c
index bbd6d01..40d1bb1 100644 (file)
--- a/net/mptcp/crypto.c
+++ b/net/mptcp/crypto.c
@@ -21,67 +21,36 @@
  */
 
 #include <linux/kernel.h>
-#include <linux/cryptohash.h>
+#include <crypto/sha.h>
 #include <asm/unaligned.h>
 
 #include "protocol.h"
 
-struct sha1_state {
-       u32 workspace[SHA_WORKSPACE_WORDS];
-       u32 digest[SHA_DIGEST_WORDS];
-       unsigned int count;
-};
-
-static void sha1_init(struct sha1_state *state)
-{
-       sha_init(state->digest);
-       state->count = 0;
-}
-
-static void sha1_update(struct sha1_state *state, u8 *input)
-{
-       sha_transform(state->digest, input, state->workspace);
-       state->count += SHA_MESSAGE_BYTES;
-}
-
-static void sha1_pad_final(struct sha1_state *state, u8 *input,
-                          unsigned int length, __be32 *mptcp_hashed_key)
-{
-       int i;
-
-       input[length] = 0x80;
-       memset(&input[length + 1], 0, SHA_MESSAGE_BYTES - length - 9);
-       put_unaligned_be64((length + state->count) << 3,
-                          &input[SHA_MESSAGE_BYTES - 8]);
-
-       sha_transform(state->digest, input, state->workspace);
-       for (i = 0; i < SHA_DIGEST_WORDS; ++i)
-               put_unaligned_be32(state->digest[i], &mptcp_hashed_key[i]);
-
-       memzero_explicit(state->workspace, SHA_WORKSPACE_WORDS << 2);
-}
+#define SHA256_DIGEST_WORDS (SHA256_DIGEST_SIZE / 4)
 
 void mptcp_crypto_key_sha(u64 key, u32 *token, u64 *idsn)
 {
-       __be32 mptcp_hashed_key[SHA_DIGEST_WORDS];
-       u8 input[SHA_MESSAGE_BYTES];
-       struct sha1_state state;
+       __be32 mptcp_hashed_key[SHA256_DIGEST_WORDS];
+       __be64 input = cpu_to_be64(key);
+       struct sha256_state state;
 
-       sha1_init(&state);
-       put_unaligned_be64(key, input);
-       sha1_pad_final(&state, input, 8, mptcp_hashed_key);
+       sha256_init(&state);
+       sha256_update(&state, (__force u8 *)&input, sizeof(input));
+       sha256_final(&state, (u8 *)mptcp_hashed_key);
 
        if (token)
                *token = be32_to_cpu(mptcp_hashed_key[0]);
        if (idsn)
-               *idsn = be64_to_cpu(*((__be64 *)&mptcp_hashed_key[3]));
+               *idsn = be64_to_cpu(*((__be64 *)&mptcp_hashed_key[6]));
 }
 
 void mptcp_crypto_hmac_sha(u64 key1, u64 key2, u32 nonce1, u32 nonce2,
-                          u32 *hash_out)
+                          void *hmac)
 {
-       u8 input[SHA_MESSAGE_BYTES * 2];
-       struct sha1_state state;
+       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];
        int i;
@@ -96,17 +65,16 @@ void mptcp_crypto_hmac_sha(u64 key1, u64 key2, u32 nonce1, u32 nonce2,
        for (i = 0; i < 8; i++)
                input[i + 8] ^= key2be[i];
 
-       put_unaligned_be32(nonce1, &input[SHA_MESSAGE_BYTES]);
-       put_unaligned_be32(nonce2, &input[SHA_MESSAGE_BYTES + 4]);
+       put_unaligned_be32(nonce1, &input[SHA256_BLOCK_SIZE]);
+       put_unaligned_be32(nonce2, &input[SHA256_BLOCK_SIZE + 4]);
 
-       sha1_init(&state);
-       sha1_update(&state, input);
+       sha256_init(&state);
+       sha256_update(&state, input, SHA256_BLOCK_SIZE + 8);
 
        /* emit sha256(K1 || msg) on the second input block, so we can
         * reuse 'input' for the last hashing
         */
-       sha1_pad_final(&state, &input[SHA_MESSAGE_BYTES], 8,
-                      (__force __be32 *)&input[SHA_MESSAGE_BYTES]);
+       sha256_final(&state, &input[SHA256_BLOCK_SIZE]);
 
        /* Prepare second part of hmac */
        memset(input, 0x5C, SHA_MESSAGE_BYTES);
@@ -115,8 +83,70 @@ void mptcp_crypto_hmac_sha(u64 key1, u64 key2, u32 nonce1, u32 nonce2,
        for (i = 0; i < 8; i++)
                input[i + 8] ^= key2be[i];
 
-       sha1_init(&state);
-       sha1_update(&state, input);
-       sha1_pad_final(&state, &input[SHA_MESSAGE_BYTES], SHA_DIGEST_WORDS << 2,
-                      (__be32 *)hash_out);
+       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];
+}
+
+#ifdef CONFIG_MPTCP_HMAC_TEST
+struct test_cast {
+       char *key;
+       char *msg;
+       char *result;
+};
+
+/* we can't reuse RFC 4231 test vectors, as we have constraint on the
+ * input and key size, and we truncate the output.
+ */
+static struct test_cast tests[] = {
+       {
+               .key = "0b0b0b0b0b0b0b0b",
+               .msg = "48692054",
+               .result = "8385e24fb4235ac37556b6b886db106284a1da67",
+       },
+       {
+               .key = "aaaaaaaaaaaaaaaa",
+               .msg = "dddddddd",
+               .result = "2c5e219164ff1dca1c4a92318d847bb6b9d44492",
+       },
+       {
+               .key = "0102030405060708",
+               .msg = "cdcdcdcd",
+               .result = "e73b9ba9969969cefb04aa0d6df18ec2fcc075b6",
+       },
+};
+
+static int __init test_mptcp_crypto(void)
+{
+       char hmac[20], hmac_hex[41];
+       u32 nonce1, nonce2;
+       u64 key1, key2;
+       int i, j;
+
+       for (i = 0; i < ARRAY_SIZE(tests); ++i) {
+               /* mptcp hmap will convert to be before computing the hmac */
+               key1 = be64_to_cpu(*((__be64 *)&tests[i].key[0]));
+               key2 = be64_to_cpu(*((__be64 *)&tests[i].key[8]));
+               nonce1 = be32_to_cpu(*((__be32 *)&tests[i].msg[0]));
+               nonce2 = be32_to_cpu(*((__be32 *)&tests[i].msg[4]));
+
+               mptcp_crypto_hmac_sha(key1, key2, nonce1, nonce2, hmac);
+               for (j = 0; j < 20; ++j)
+                       sprintf(&hmac_hex[j << 1], "%02x", hmac[j] & 0xff);
+               hmac_hex[40] = 0;
+
+               if (memcmp(hmac_hex, tests[i].result, 40))
+                       pr_err("test %d failed, got %s expected %s", i,
+                              hmac_hex, tests[i].result);
+               else
+                       pr_info("test %d [ ok ]", i);
+       }
+       return 0;
 }
+
+late_initcall(test_mptcp_crypto);
+#endif

diff --git a/net/mptcp/options.c b/net/mptcp/options.c
index 1fa8496..1aec742 100644 (file)
--- a/net/mptcp/options.c
+++ b/net/mptcp/options.c
@@ -9,6 +9,11 @@
 #include <net/mptcp.h>
 #include "protocol.h"
 
+static bool mptcp_cap_flag_sha256(u8 flags)
+{
+       return (flags & MPTCP_CAP_FLAG_MASK) == MPTCP_CAP_HMAC_SHA256;
+}
+
 void mptcp_parse_option(const unsigned char *ptr, int opsize,
                        struct tcp_options_received *opt_rx)
 {
@@ -29,7 +34,7 @@ void mptcp_parse_option(const unsigned char *ptr, int opsize,
                        break;
 
                flags = *ptr++;
-               if (!((flags & MPTCP_CAP_FLAG_MASK) == MPTCP_CAP_HMAC_SHA1) ||
+               if (!mptcp_cap_flag_sha256(flags) ||
                    (flags & MPTCP_CAP_EXTENSIBILITY))
                        break;
 
@@ -399,7 +404,7 @@ void mptcp_write_options(__be32 *ptr, struct mptcp_out_options *opts)
                *ptr++ = htonl((TCPOPT_MPTCP << 24) | (len << 16) |
                               (MPTCPOPT_MP_CAPABLE << 12) |
                               (MPTCP_SUPPORTED_VERSION << 8) |
-                              MPTCP_CAP_HMAC_SHA1);
+                              MPTCP_CAP_HMAC_SHA256);
                put_unaligned_be64(opts->sndr_key, ptr);
                ptr += 2;
                if (OPTION_MPTCP_MPC_ACK & opts->suboptions) {

diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h
index a8fad7d..a355bb1 100644 (file)
--- a/net/mptcp/protocol.h
+++ b/net/mptcp/protocol.h
@@ -43,7 +43,7 @@
 #define MPTCP_VERSION_MASK     (0x0F)
 #define MPTCP_CAP_CHECKSUM_REQD        BIT(7)
 #define MPTCP_CAP_EXTENSIBILITY        BIT(6)
-#define MPTCP_CAP_HMAC_SHA1    BIT(0)
+#define MPTCP_CAP_HMAC_SHA256  BIT(0)
 #define MPTCP_CAP_FLAG_MASK    (0x3F)
 
 /* MPTCP DSS flags */
@@ -216,7 +216,7 @@ static inline void mptcp_crypto_key_gen_sha(u64 *key, u32 *token, u64 *idsn)
 }
 
 void mptcp_crypto_hmac_sha(u64 key1, u64 key2, u32 nonce1, u32 nonce2,
-                          u32 *hash_out);
+                          void *hash_out);
 
 static inline struct mptcp_ext *mptcp_get_ext(struct sk_buff *skb)
 {