Merge branch 'debian/experimental-2.5'

1 files changed, 98 insertions, 17 deletions

diff --git a/src/openvpn/tls_crypt.h b/src/openvpn/tls_crypt.h
index 05fcc4e..2e127f2 100644
--- a/src/openvpn/tls_crypt.h
+++ b/src/openvpn/tls_crypt.h
@@ -22,15 +22,13 @@
  */
 
 /**
- * @defgroup tls_crypt Control channel encryption (--tls-crypt)
+ * @defgroup tls_crypt Control channel encryption (--tls-crypt, --tls-crypt-v2)
  * @ingroup control_tls
  * @{
  *
- * @par
  * Control channel encryption uses a pre-shared static key (like the --tls-auth
  * key) to encrypt control channel packets.
  *
- * @par
  * Encrypting control channel packets has three main advantages:
  *  - It provides more privacy by hiding the certificate used for the TLS
  *    connection.
@@ -38,11 +36,20 @@
  *  - It provides "poor-man's" post-quantum security, against attackers who
  *    will never know the pre-shared key (i.e. no forward secrecy).
  *
- * @par Specification
+ * --tls-crypt uses a tls-auth-style group key, where all servers and clients
+ * share the same group key. --tls-crypt-v2 adds support for client-specific
+ * keys, where all servers share the same client-key encryption key, and each
+ * clients receives a unique client key, both in plaintext and in encrypted
+ * form.  When connecting to a server, the client sends the encrypted key to
+ * the server in the first packet (P_CONTROL_HARD_RESET_CLIENT_V3). The server
+ * then decrypts that key, and both parties can use the same client-specific
+ * key for tls-crypt packets. See doc/tls-crypt-v2.txt for more details.
+ *
+ * @par On-the-wire tls-crypt packet specification
+ * @parblock
  * Control channel encryption is based on the SIV construction [0], to achieve
  * nonce misuse-resistant authenticated encryption:
  *
- * @par
  * \code{.unparsed}
  * msg      = control channel plaintext
  * header   = opcode (1 byte) || session_id (8 bytes) || packet_id (8 bytes)
@@ -57,28 +64,27 @@
  * output   = Header || Tag || Ciph
  * \endcode
  *
- * @par
  * This boils down to the following on-the-wire packet format:
  *
- * @par
  * \code{.unparsed}
  * - opcode - || - session_id - || - packet_id - || auth_tag || * payload *
  * \endcode
  *
- * @par
  * Where
  * <tt>- XXX -</tt> means authenticated, and
  * <tt>* XXX *</tt> means authenticated and encrypted.
+ *
+ * @endparblock
  */
 
 #ifndef TLSCRYPT_H
 #define TLSCRYPT_H
 
-#ifdef ENABLE_CRYPTO
-
+#include "base64.h"
 #include "buffer.h"
 #include "crypto.h"
 #include "session_id.h"
+#include "ssl_common.h"
 
 #define TLS_CRYPT_TAG_SIZE (256/8)
 #define TLS_CRYPT_PID_SIZE (sizeof(packet_id_type) + sizeof(net_time_t))
@@ -88,18 +94,28 @@
 #define TLS_CRYPT_OFF_TAG (TLS_CRYPT_OFF_PID + TLS_CRYPT_PID_SIZE)
 #define TLS_CRYPT_OFF_CT (TLS_CRYPT_OFF_TAG + TLS_CRYPT_TAG_SIZE)
 
+#define TLS_CRYPT_V2_MAX_WKC_LEN (1024)
+#define TLS_CRYPT_V2_CLIENT_KEY_LEN (2048 / 8)
+#define TLS_CRYPT_V2_SERVER_KEY_LEN (sizeof(struct key))
+#define TLS_CRYPT_V2_TAG_SIZE (TLS_CRYPT_TAG_SIZE)
+#define TLS_CRYPT_V2_MAX_METADATA_LEN (unsigned)(TLS_CRYPT_V2_MAX_WKC_LEN \
+                                                 - (TLS_CRYPT_V2_CLIENT_KEY_LEN + TLS_CRYPT_V2_TAG_SIZE \
+                                                    + sizeof(uint16_t)))
+#define TLS_CRYPT_V2_MAX_B64_METADATA_LEN \
+    OPENVPN_BASE64_LENGTH(TLS_CRYPT_V2_MAX_METADATA_LEN - 1)
+
 /**
  * Initialize a key_ctx_bi structure for use with --tls-crypt.
  *
  * @param key           The key context to initialize
- * @param key_file      The file to read the key from (or the inline tag to
- *                      indicate and inline key).
- * @param key_inline    Array containing (zero-terminated) inline key, or NULL
- *                      if not used.
+ * @param key_file      The file to read the key from or the key itself if
+ *                      key_inline is true.
+ * @param key_inline    True if key_file contains an inline key, False
+ *                      otherwise.
  * @param tls_server    Must be set to true is this is a TLS server instance.
  */
 void tls_crypt_init_key(struct key_ctx_bi *key, const char *key_file,
-                        const char *key_inline, bool tls_server);
+                        bool key_inline, bool tls_server);
 
 /**
  * Returns the maximum overhead (in bytes) added to the destination buffer by
@@ -140,8 +156,73 @@ bool tls_crypt_wrap(const struct buffer *src, struct buffer *dst,
 bool tls_crypt_unwrap(const struct buffer *src, struct buffer *dst,
                       struct crypto_options *opt);
 
-/** @} */
+/**
+ * Initialize a tls-crypt-v2 server key (used to encrypt/decrypt client keys).
+ *
+ * @param key           Key structure to be initialized.  Must be non-NULL.
+ * @parem encrypt       If true, initialize the key structure for encryption,
+ *                      otherwise for decryption.
+ * @param key_file      File path of the key file to load or the key itself if
+ *                      key_inline is true.
+ * @param key_inline    True if key_file contains an inline key, False
+ *                      otherwise.
+ *
+ */
+void tls_crypt_v2_init_server_key(struct key_ctx *key_ctx, bool encrypt,
+                                  const char *key_file, bool key_inline);
+
+/**
+ * Initialize a tls-crypt-v2 client key.
+ *
+ * @param key               Key structure to be initialized with the client
+ *                          key.
+ * @param wrapped_key_buf   Returns buffer containing the wrapped key that will
+ *                          be sent to the server when connecting.  Caller must
+ *                          free this buffer when no longer needed.
+ * @param key_file          File path of the key file to load or the key itself
+ *                          if key_inline is true.
+ * @param key_inline        True if key_file contains an inline key, False
+ *                          otherwise.
+ */
+void tls_crypt_v2_init_client_key(struct key_ctx_bi *key,
+                                  struct buffer *wrapped_key_buf,
+                                  const char *key_file, bool key_inline);
+
+/**
+ * Extract a tls-crypt-v2 client key from a P_CONTROL_HARD_RESET_CLIENT_V3
+ * message, and load the key into the supplied tls wrap context.
+ *
+ * @param buf   Buffer containing a received P_CONTROL_HARD_RESET_CLIENT_V3
+ *              message.
+ * @param ctx   tls-wrap context to be initialized with the client key.
+ *
+ * @returns true if a key was successfully extracted.
+ */
+bool tls_crypt_v2_extract_client_key(struct buffer *buf,
+                                     struct tls_wrap_ctx *ctx,
+                                     const struct tls_options *opt);
+
+/**
+ * Generate a tls-crypt-v2 server key, and write to file.
+ *
+ * @param filename          Filename of the server key file to create.
+ */
+void tls_crypt_v2_write_server_key_file(const char *filename);
+
+/**
+ * Generate a tls-crypt-v2 client key, and write to file.
+ *
+ * @param filename          Filename of the client key file to create.
+ * @param b64_metadata      Base64 metadata to be included in the client key.
+ * @param key_file          File path of the server key to use for wrapping the
+ *                          client key or the key itself if key_inline is true.
+ * @param key_inline        True if key_file contains an inline key, False
+ *                          otherwise.
+ */
+void tls_crypt_v2_write_client_key_file(const char *filename,
+                                        const char *b64_metadata,
+                                        const char *key_file, bool key_inline);
 
-#endif /* ENABLE_CRYPTO */
+/** @} */
 
 #endif /* TLSCRYPT_H */