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authorAlberto Gonzalez Iniesta <agi@inittab.org>2016-11-21 09:37:33 +0100
committerAlberto Gonzalez Iniesta <agi@inittab.org>2016-11-21 09:37:33 +0100
commit20c8675ba46bda97330a4117c459a59a9f1c465e (patch)
treed888c714fb61947dd79dc44b64a4aaae2f70bfb7 /src/openvpn/crypto.h
parentffca24bed7a03d95585ad02278667abe75d8b272 (diff)
New upstream version 2.4~beta1upstream/2.4_beta1
Diffstat (limited to 'src/openvpn/crypto.h')
-rw-r--r--src/openvpn/crypto.h162
1 files changed, 109 insertions, 53 deletions
diff --git a/src/openvpn/crypto.h b/src/openvpn/crypto.h
index e489827..ff90745 100644
--- a/src/openvpn/crypto.h
+++ b/src/openvpn/crypto.h
@@ -86,6 +86,30 @@
* <tt> [ HMAC ] [ - IV - ] [ * packet payload * ] </tt>
*
* @par
+ * <b>GCM data channel crypto format</b> \n
+ * GCM modes are only supported in TLS mode. In these modes, the IV consists of
+ * the 32-bit packet counter followed by data from the HMAC key. The HMAC key
+ * can be used as IV, since in GCM and CCM modes the HMAC key is not used for
+ * the HMAC. The packet counter may not roll over within a single TLS sessions.
+ * This results in a unique IV for each packet, as required by GCM.
+ *
+ * @par
+ * The HMAC key data is pre-shared during the connection setup, and thus can be
+ * omitted in on-the-wire packets, saving 8 bytes per packet (for GCM and CCM).
+ *
+ * @par
+ * In GCM mode, P_DATA_V2 headers (the opcode and peer-id) are also
+ * authenticated as Additional Data.
+ *
+ * @par
+ * <i>GCM IV format:</i> \n
+ * <tt> [ - packet ID - ] [ - HMAC key data - ] </tt>\n
+ * <i>P_DATA_V1 GCM data channel crypto format:</i> \n
+ * <tt> [ opcode ] [ - packet ID - ] [ TAG ] [ * packet payload * ] </tt>
+ * <i>P_DATA_V2 GCM data channel crypto format:</i> \n
+ * <tt> [ - opcode/peer-id - ] [ - packet ID - ] [ TAG ] [ * packet payload * ] </tt>
+ *
+ * @par
* <b>No-crypto data channel format</b> \n
* In no-crypto mode (\c \-\-cipher \c none is specified), both TLS-mode and
* static key mode are supported. No encryption will be performed on the packet,
@@ -108,6 +132,11 @@
#include "packet_id.h"
#include "mtu.h"
+/** Wrapper struct to pass around MD5 digests */
+struct md5_digest {
+ uint8_t digest[MD5_DIGEST_LENGTH];
+};
+
/*
* Defines a key type and key length for both cipher and HMAC.
*/
@@ -133,13 +162,16 @@ struct key
/**
- * Container for one set of OpenSSL cipher and/or HMAC contexts.
+ * Container for one set of cipher and/or HMAC contexts.
* @ingroup control_processor
*/
struct key_ctx
{
cipher_ctx_t *cipher; /**< Generic cipher %context. */
- hmac_ctx_t *hmac; /**< Generic HMAC %context. */
+ hmac_ctx_t *hmac; /**< Generic HMAC %context. */
+ uint8_t implicit_iv[OPENVPN_MAX_IV_LENGTH];
+ /**< The implicit part of the IV */
+ size_t implicit_iv_len; /**< The length of implicit_iv */
};
#define KEY_DIRECTION_BIDIRECTIONAL 0 /* same keys for both directions */
@@ -190,10 +222,11 @@ struct key_direction_state
*/
struct key_ctx_bi
{
- struct key_ctx encrypt; /**< OpenSSL cipher and/or HMAC contexts
- * for sending direction. */
- struct key_ctx decrypt; /**< OpenSSL cipher and/or HMAC contexts
- * for receiving direction. */
+ struct key_ctx encrypt; /**< Cipher and/or HMAC contexts for sending
+ * direction. */
+ struct key_ctx decrypt; /**< cipher and/or HMAC contexts for
+ * receiving direction. */
+ bool initialized;
};
/**
@@ -202,11 +235,11 @@ struct key_ctx_bi
*/
struct crypto_options
{
- struct key_ctx_bi *key_ctx_bi;
+ struct key_ctx_bi key_ctx_bi;
/**< OpenSSL cipher and HMAC contexts for
* both sending and receiving
* directions. */
- struct packet_id *packet_id; /**< Current packet ID state for both
+ struct packet_id packet_id; /**< Current packet ID state for both
* sending and receiving directions. */
struct packet_id_persist *pid_persist;
/**< Persistent packet ID state for
@@ -233,6 +266,15 @@ struct crypto_options
* security operation functions. */
};
+#define CRYPT_ERROR(format) \
+ do { msg (D_CRYPT_ERRORS, "%s: " format, error_prefix); goto error_exit; } while (false)
+
+/**
+ * Minimal IV length for AEAD mode ciphers (in bytes):
+ * 4-byte packet id + 8 bytes implicit IV.
+ */
+#define OPENVPN_AEAD_MIN_IV_LEN (sizeof (packet_id_type) + 8)
+
#define RKF_MUST_SUCCEED (1<<0)
#define RKF_INLINE (1<<1)
void read_key_file (struct key2 *key2, const char *file, const unsigned int flags);
@@ -257,9 +299,20 @@ bool write_key (const struct key *key, const struct key_type *kt,
int read_key (struct key *key, const struct key_type *kt, struct buffer *buf);
+/**
+ * Initialize a key_type structure with.
+ *
+ * @param kt The struct key_type to initialize
+ * @param ciphername The name of the cipher to use
+ * @param authname The name of the HMAC digest to use
+ * @param keysize The length of the cipher key to use, in bytes. Only valid
+ * for ciphers that support variable length keys.
+ * @param tls_mode Specifies wether we are running in TLS mode, which allows
+ * more ciphers than static key mode.
+ * @param warn Print warnings when null cipher / auth is used.
+ */
void init_key_type (struct key_type *kt, const char *ciphername,
- bool ciphername_defined, const char *authname, bool authname_defined,
- int keysize, bool cfb_ofb_allowed, bool warn);
+ const char *authname, int keysize, bool tls_mode, bool warn);
/*
* Key context functions
@@ -296,18 +349,16 @@ void free_key_ctx_bi (struct key_ctx_bi *ctx);
*
* @param buf - The %buffer containing the packet on which to
* perform security operations.
- * @param work - A working %buffer.
+ * @param work - An initialized working %buffer.
* @param opt - The security parameter state for this VPN tunnel.
- * @param frame - The packet geometry parameters for this VPN
- * tunnel.
+ *
* @return This function returns void.\n On return, the \a buf argument
* will point to the resulting %buffer. This %buffer will either
* contain the processed packet ready for sending, or be empty if an
* error occurred.
*/
void openvpn_encrypt (struct buffer *buf, struct buffer work,
- const struct crypto_options *opt,
- const struct frame* frame);
+ struct crypto_options *opt);
/**
@@ -333,6 +384,8 @@ void openvpn_encrypt (struct buffer *buf, struct buffer work,
* @param opt - The security parameter state for this VPN tunnel.
* @param frame - The packet geometry parameters for this VPN
* tunnel.
+ * @param ad_start - A pointer into buf, indicating from where to start
+ * authenticating additional data (AEAD mode only).
*
* @return
* @li True, if the packet was authenticated and decrypted successfully.
@@ -342,18 +395,35 @@ void openvpn_encrypt (struct buffer *buf, struct buffer work,
* an error occurred.
*/
bool openvpn_decrypt (struct buffer *buf, struct buffer work,
- const struct crypto_options *opt,
- const struct frame* frame);
+ struct crypto_options *opt, const struct frame* frame,
+ const uint8_t *ad_start);
/** @} name Functions for performing security operations on data channel packets */
+/**
+ * Check packet ID for replay, and perform replay administration.
+ *
+ * @param opt Crypto options for this packet, contains replay state.
+ * @param pin Packet ID read from packet.
+ * @param error_prefix Prefix to use when printing error messages.
+ * @param gc Garbage collector to use.
+ *
+ * @return true if packet ID is validated to be not a replay, false otherwise.
+ */
+bool crypto_check_replay(struct crypto_options *opt,
+ const struct packet_id_net *pin, const char *error_prefix,
+ struct gc_arena *gc);
+
+
+/** Calculate crypto overhead and adjust frame to account for that */
void crypto_adjust_frame_parameters(struct frame *frame,
const struct key_type* kt,
- bool cipher_defined,
bool use_iv,
bool packet_id,
bool packet_id_long_form);
+/** Return the worst-case OpenVPN crypto overhead (in bytes) */
+size_t crypto_max_overhead(void);
/* Minimum length of the nonce used by the PRNG */
#define NONCE_SECRET_LEN_MIN 16
@@ -392,7 +462,7 @@ void prng_bytes (uint8_t *output, int len);
void prng_uninit ();
-void test_crypto (const struct crypto_options *co, struct frame* f);
+void test_crypto (struct crypto_options *co, struct frame* f);
/* key direction functions */
@@ -413,45 +483,31 @@ void key2_print (const struct key2* k,
const char* prefix0,
const char* prefix1);
-#ifdef ENABLE_SSL
-
-#define GHK_INLINE (1<<0)
-void get_tls_handshake_key (const struct key_type *key_type,
- struct key_ctx_bi *ctx,
- const char *passphrase_file,
- const int key_direction,
- const unsigned int flags);
-
-#else
-
-void init_ssl_lib (void);
-void free_ssl_lib (void);
-
-#endif /* ENABLE_SSL */
+void crypto_read_openvpn_key (const struct key_type *key_type,
+ struct key_ctx_bi *ctx, const char *key_file, const char *key_inline,
+ const int key_direction, const char *key_name, const char *opt_name);
/*
- * md5 functions
+ * Inline functions
*/
-struct md5_state {
- md_ctx_t ctx;
-};
-
-struct md5_digest {
- uint8_t digest [MD5_DIGEST_LENGTH];
-};
-
-const char *md5sum(uint8_t *buf, int len, int n_print_chars, struct gc_arena *gc);
-void md5_state_init (struct md5_state *s);
-void md5_state_update (struct md5_state *s, void *data, size_t len);
-void md5_state_final (struct md5_state *s, struct md5_digest *out);
-void md5_digest_clear (struct md5_digest *digest);
-bool md5_digest_defined (const struct md5_digest *digest);
-bool md5_digest_equal (const struct md5_digest *d1, const struct md5_digest *d2);
-
-/*
- * Inline functions
+/**
+ * As memcmp(), but constant-time.
+ * Returns 0 when data is equal, non-zero otherwise.
*/
+static inline int
+memcmp_constant_time (const void *a, const void *b, size_t size) {
+ const uint8_t * a1 = a;
+ const uint8_t * b1 = b;
+ int ret = 0;
+ size_t i;
+
+ for (i = 0; i < size; i++) {
+ ret |= *a1++ ^ *b1++;
+ }
+
+ return ret;
+}
static inline bool
key_ctx_bi_defined(const struct key_ctx_bi* key)