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, 90 insertions, 0 deletions

diff --git a/src/plugins/wireguard/wireguard_hchacha20.h b/src/plugins/wireguard/wireguard_hchacha20.h
new file mode 100644
index 00000000000..a2d139621c9
--- /dev/null
+++ b/src/plugins/wireguard/wireguard_hchacha20.h
@@ -0,0 +1,90 @@
+/*
+ * 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.
+ */
+
+/*
+ * chacha-merged.c version 20080118
+ * D. J. Bernstein
+ * Public domain.
+ */
+
+#ifndef __included_wg_hchacha20_h__
+#define __included_wg_hchacha20_h__
+
+#include <vlib/vlib.h>
+
+/* clang-format off */
+#define U32C(v) (v##U)
+#define U32V(v) ((u32)(v) & U32C(0xFFFFFFFF))
+
+#define ROTL32(v, n) \
+  (U32V((v) << (n)) | ((v) >> (32 - (n))))
+
+#define U8TO32_LITTLE(p) \
+  (((u32)((p)[0])      ) | \
+   ((u32)((p)[1]) <<  8) | \
+   ((u32)((p)[2]) << 16) | \
+   ((u32)((p)[3]) << 24))
+
+#define ROTATE(v,c) (ROTL32(v,c))
+#define XOR(v,w) ((v) ^ (w))
+#define PLUS(v,w) (U32V((v) + (w)))
+
+#define QUARTERROUND(a,b,c,d) \
+  a = PLUS(a,b); d = ROTATE(XOR(d,a),16); \
+  c = PLUS(c,d); b = ROTATE(XOR(b,c),12); \
+  a = PLUS(a,b); d = ROTATE(XOR(d,a), 8); \
+  c = PLUS(c,d); b = ROTATE(XOR(b,c), 7);
+/* clang-format on */
+
+static const char sigma[16] = "expand 32-byte k";
+
+static inline void
+hchacha20 (u32 derived_key[8], const u8 nonce[16], const u8 key[32])
+{
+  int i;
+  u32 x[] = { U8TO32_LITTLE (sigma + 0), U8TO32_LITTLE (sigma + 4),
+	      U8TO32_LITTLE (sigma + 8), U8TO32_LITTLE (sigma + 12),
+	      U8TO32_LITTLE (key + 0),	 U8TO32_LITTLE (key + 4),
+	      U8TO32_LITTLE (key + 8),	 U8TO32_LITTLE (key + 12),
+	      U8TO32_LITTLE (key + 16),	 U8TO32_LITTLE (key + 20),
+	      U8TO32_LITTLE (key + 24),	 U8TO32_LITTLE (key + 28),
+	      U8TO32_LITTLE (nonce + 0), U8TO32_LITTLE (nonce + 4),
+	      U8TO32_LITTLE (nonce + 8), U8TO32_LITTLE (nonce + 12) };
+
+  for (i = 20; i > 0; i -= 2)
+    {
+      QUARTERROUND (x[0], x[4], x[8], x[12])
+      QUARTERROUND (x[1], x[5], x[9], x[13])
+      QUARTERROUND (x[2], x[6], x[10], x[14])
+      QUARTERROUND (x[3], x[7], x[11], x[15])
+      QUARTERROUND (x[0], x[5], x[10], x[15])
+      QUARTERROUND (x[1], x[6], x[11], x[12])
+      QUARTERROUND (x[2], x[7], x[8], x[13])
+      QUARTERROUND (x[3], x[4], x[9], x[14])
+    }
+
+  clib_memcpy (derived_key + 0, x + 0, sizeof (u32) * 4);
+  clib_memcpy (derived_key + 4, x + 12, sizeof (u32) * 4);
+}
+
+#endif /* __included_wg_hchacha20_h__ */
+
+/*
+ * fd.io coding-style-patch-verification: ON
+ *
+ * Local Variables:
+ * eval: (c-set-style "gnu")
+ * End:
+ */