mptcp: Add key generation and token tree

Generate the local keys, IDSN, and token when creating a new socket.
Introduce the token tree to track all tokens in use using a radix tree
with the MPTCP token itself as the index.

Override the rebuild_header callback in inet_connection_sock_af_ops for
creating the local key on a new outgoing connection.

Override the init_req callback of tcp_request_sock_ops for creating the
local key on a new incoming connection.

Will be used to obtain the MPTCP parent socket to handle incoming joins.

Co-developed-by: Davide Caratti <dcaratti@redhat.com>
Signed-off-by: Davide Caratti <dcaratti@redhat.com>
Co-developed-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Florian Westphal <fw@strlen.de>
Co-developed-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Peter Krystad <peter.krystad@linux.intel.com>
Signed-off-by: Christoph Paasch <cpaasch@apple.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 122 insertions, 0 deletions

diff --git a/net/mptcp/crypto.c b/net/mptcp/crypto.c
new file mode 100644
index 000000000000..bbd6d01af211
--- /dev/null
+++ b/net/mptcp/crypto.c
@@ -0,0 +1,122 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Multipath TCP cryptographic functions
+ * Copyright (c) 2017 - 2019, Intel Corporation.
+ *
+ * Note: This code is based on mptcp_ctrl.c, mptcp_ipv4.c, and
+ *       mptcp_ipv6 from multipath-tcp.org, authored by:
+ *
+ *       Sébastien Barré <sebastien.barre@uclouvain.be>
+ *       Christoph Paasch <christoph.paasch@uclouvain.be>
+ *       Jaakko Korkeaniemi <jaakko.korkeaniemi@aalto.fi>
+ *       Gregory Detal <gregory.detal@uclouvain.be>
+ *       Fabien Duchêne <fabien.duchene@uclouvain.be>
+ *       Andreas Seelinger <Andreas.Seelinger@rwth-aachen.de>
+ *       Lavkesh Lahngir <lavkesh51@gmail.com>
+ *       Andreas Ripke <ripke@neclab.eu>
+ *       Vlad Dogaru <vlad.dogaru@intel.com>
+ *       Octavian Purdila <octavian.purdila@intel.com>
+ *       John Ronan <jronan@tssg.org>
+ *       Catalin Nicutar <catalin.nicutar@gmail.com>
+ *       Brandon Heller <brandonh@stanford.edu>
+ */
+
+#include <linux/kernel.h>
+#include <linux/cryptohash.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);
+}
+
+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;
+
+	sha1_init(&state);
+	put_unaligned_be64(key, input);
+	sha1_pad_final(&state, input, 8, mptcp_hashed_key);
+
+	if (token)
+		*token = be32_to_cpu(mptcp_hashed_key[0]);
+	if (idsn)
+		*idsn = be64_to_cpu(*((__be64 *)&mptcp_hashed_key[3]));
+}
+
+void mptcp_crypto_hmac_sha(u64 key1, u64 key2, u32 nonce1, u32 nonce2,
+			   u32 *hash_out)
+{
+	u8 input[SHA_MESSAGE_BYTES * 2];
+	struct sha1_state state;
+	u8 key1be[8];
+	u8 key2be[8];
+	int i;
+
+	put_unaligned_be64(key1, key1be);
+	put_unaligned_be64(key2, key2be);
+
+	/* Generate key xored with ipad */
+	memset(input, 0x36, SHA_MESSAGE_BYTES);
+	for (i = 0; i < 8; i++)
+		input[i] ^= key1be[i];
+	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]);
+
+	sha1_init(&state);
+	sha1_update(&state, input);
+
+	/* 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]);
+
+	/* Prepare second part of hmac */
+	memset(input, 0x5C, SHA_MESSAGE_BYTES);
+	for (i = 0; i < 8; i++)
+		input[i] ^= key1be[i];
+	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);
+}