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mptcp: move from sha1 (v0) to sha256 (v1)
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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>
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@davem330
Paolo Abeni authored and davem330 committed Jan 24, 2020
1 parent 048d19d commit 65492c5
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Showing 4 changed files with 104 additions and 59 deletions.
10 changes: 10 additions & 0 deletions net/mptcp/Kconfig
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Original file line number Diff line number Diff line change
Expand Up @@ -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
Expand All @@ -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.
140 changes: 85 additions & 55 deletions net/mptcp/crypto.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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;
Expand All @@ -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);
Expand All @@ -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
9 changes: 7 additions & 2 deletions net/mptcp/options.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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)
{
Expand All @@ -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;

Expand Down Expand Up @@ -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) {
Expand Down
4 changes: 2 additions & 2 deletions net/mptcp/protocol.h
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Original file line number Diff line number Diff line change
Expand Up @@ -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 */
Expand Down Expand Up @@ -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)
{
Expand Down

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