wireguard: add processing of received cookie messages

Type: feature

Currently, if a handshake message is sent and a cookie message is
received in reply, the cookie message will be ignored. Thus, further
handshake messages will not have valid mac2 and handshake will not be
able to be completed.

With this change, process received cookie messages to be able to
calculate mac2 for further handshake messages sent. Cover this with
tests.

Signed-off-by: Alexander Chernavin <achernavin@netgate.com>
Change-Id: I6d51459778b7145be7077badec479b2aa85960b9

1 files changed, 103 insertions, 0 deletions

diff --git a/src/plugins/wireguard/wireguard_chachapoly.c b/src/plugins/wireguard/wireguard_chachapoly.c
new file mode 100644
index 00000000000..961b43f100d
--- /dev/null
+++ b/src/plugins/wireguard/wireguard_chachapoly.c
@@ -0,0 +1,103 @@
+/*
+ * Copyright (c) 2022 Rubicon Communications, LLC.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <wireguard/wireguard.h>
+#include <wireguard/wireguard_chachapoly.h>
+#include <wireguard/wireguard_hchacha20.h>
+
+bool
+wg_chacha20poly1305_calc (vlib_main_t *vm, u8 *src, u32 src_len, u8 *dst,
+			  u8 *aad, u32 aad_len, u64 nonce,
+			  vnet_crypto_op_id_t op_id,
+			  vnet_crypto_key_index_t key_index)
+{
+  vnet_crypto_op_t _op, *op = &_op;
+  u8 iv[12];
+  u8 tag_[NOISE_AUTHTAG_LEN] = {};
+  u8 src_[] = {};
+
+  clib_memset (iv, 0, 12);
+  clib_memcpy (iv + 4, &nonce, sizeof (nonce));
+
+  vnet_crypto_op_init (op, op_id);
+
+  op->tag_len = NOISE_AUTHTAG_LEN;
+  if (op_id == VNET_CRYPTO_OP_CHACHA20_POLY1305_DEC)
+    {
+      op->tag = src + src_len - NOISE_AUTHTAG_LEN;
+      src_len -= NOISE_AUTHTAG_LEN;
+      op->flags |= VNET_CRYPTO_OP_FLAG_HMAC_CHECK;
+    }
+  else
+    op->tag = tag_;
+
+  op->src = !src ? src_ : src;
+  op->len = src_len;
+
+  op->dst = dst;
+  op->key_index = key_index;
+  op->aad = aad;
+  op->aad_len = aad_len;
+  op->iv = iv;
+
+  vnet_crypto_process_ops (vm, op, 1);
+  if (op_id == VNET_CRYPTO_OP_CHACHA20_POLY1305_ENC)
+    {
+      clib_memcpy (dst + src_len, op->tag, NOISE_AUTHTAG_LEN);
+    }
+
+  return (op->status == VNET_CRYPTO_OP_STATUS_COMPLETED);
+}
+
+bool
+wg_xchacha20poly1305_decrypt (vlib_main_t *vm, u8 *src, u32 src_len, u8 *dst,
+			      u8 *aad, u32 aad_len,
+			      u8 nonce[XCHACHA20POLY1305_NONCE_SIZE],
+			      u8 key[CHACHA20POLY1305_KEY_SIZE])
+{
+  int ret, i;
+  u32 derived_key[CHACHA20POLY1305_KEY_SIZE / sizeof (u32)];
+  u64 h_nonce;
+
+  clib_memcpy (&h_nonce, nonce + 16, sizeof (h_nonce));
+  h_nonce = le64toh (h_nonce);
+  hchacha20 (derived_key, nonce, key);
+
+  for (i = 0; i < (sizeof (derived_key) / sizeof (derived_key[0])); i++)
+    (derived_key[i]) = htole32 ((derived_key[i]));
+
+  uint32_t key_idx;
+
+  key_idx =
+    vnet_crypto_key_add (vm, VNET_CRYPTO_ALG_CHACHA20_POLY1305,
+			 (uint8_t *) derived_key, CHACHA20POLY1305_KEY_SIZE);
+
+  ret =
+    wg_chacha20poly1305_calc (vm, src, src_len, dst, aad, aad_len, h_nonce,
+			      VNET_CRYPTO_OP_CHACHA20_POLY1305_DEC, key_idx);
+
+  vnet_crypto_key_del (vm, key_idx);
+  wg_secure_zero_memory (derived_key, CHACHA20POLY1305_KEY_SIZE);
+
+  return ret;
+}
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */