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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.c
parentffca24bed7a03d95585ad02278667abe75d8b272 (diff)
New upstream version 2.4~beta1upstream/2.4_beta1
Diffstat (limited to 'src/openvpn/crypto.c')
-rw-r--r--src/openvpn/crypto.c821
1 files changed, 518 insertions, 303 deletions
diff --git a/src/openvpn/crypto.c b/src/openvpn/crypto.c
index 400bf11..05622ce 100644
--- a/src/openvpn/crypto.c
+++ b/src/openvpn/crypto.c
@@ -6,7 +6,7 @@
* packet compression.
*
* Copyright (C) 2002-2010 OpenVPN Technologies, Inc. <sales@openvpn.net>
- * Copyright (C) 2010 Fox Crypto B.V. <openvpn@fox-it.com>
+ * Copyright (C) 2010-2016 Fox Crypto B.V. <openvpn@fox-it.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2
@@ -35,7 +35,8 @@
#include "crypto.h"
#include "error.h"
-#include "misc.h"
+#include "integer.h"
+#include "platform.h"
#include "memdbg.h"
@@ -62,38 +63,114 @@
* happen unless the frame parameters are wrong.
*/
-#define CRYPT_ERROR(format) \
- do { msg (D_CRYPT_ERRORS, "%s: " format, error_prefix); goto error_exit; } while (false)
+static void
+openvpn_encrypt_aead (struct buffer *buf, struct buffer work,
+ struct crypto_options *opt) {
+#ifdef HAVE_AEAD_CIPHER_MODES
+ struct gc_arena gc;
+ int outlen = 0;
+ const struct key_ctx *ctx = &opt->key_ctx_bi.encrypt;
+ uint8_t *mac_out = NULL;
+ const cipher_kt_t *cipher_kt = cipher_ctx_get_cipher_kt (ctx->cipher);
+ const int mac_len = cipher_kt_tag_size (cipher_kt);
+
+ /* IV, packet-ID and implicit IV required for this mode. */
+ ASSERT (ctx->cipher);
+ ASSERT (cipher_kt_mode_aead (cipher_kt));
+ ASSERT (opt->flags & CO_USE_IV);
+ ASSERT (packet_id_initialized(&opt->packet_id));
-/**
- * As memcmp(), but constant-time.
- * Returns 0 when data is equal, non-zero otherwise.
- */
-static 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++;
+ gc_init (&gc);
+
+ /* Prepare IV */
+ {
+ struct buffer iv_buffer;
+ struct packet_id_net pin;
+ uint8_t iv[OPENVPN_MAX_IV_LENGTH];
+ const int iv_len = cipher_ctx_iv_length (ctx->cipher);
+
+ ASSERT (iv_len >= OPENVPN_AEAD_MIN_IV_LEN && iv_len <= OPENVPN_MAX_IV_LENGTH);
+
+ memset(iv, 0, sizeof(iv));
+ buf_set_write (&iv_buffer, iv, iv_len);
+
+ /* IV starts with packet id to make the IV unique for packet */
+ packet_id_alloc_outgoing (&opt->packet_id.send, &pin, false);
+ ASSERT (packet_id_write (&pin, &iv_buffer, false, false));
+
+ /* Remainder of IV consists of implicit part (unique per session) */
+ ASSERT (buf_write (&iv_buffer, ctx->implicit_iv, ctx->implicit_iv_len));
+ ASSERT (iv_buffer.len == iv_len);
+
+ /* Write explicit part of IV to work buffer */
+ ASSERT (buf_write(&work, iv, iv_len - ctx->implicit_iv_len));
+ dmsg (D_PACKET_CONTENT, "ENCRYPT IV: %s", format_hex (iv, iv_len, 0, &gc));
+
+ /* Init cipher_ctx with IV. key & keylen are already initialized */
+ ASSERT (cipher_ctx_reset(ctx->cipher, iv));
}
- return ret;
+ /* Reserve space for authentication tag */
+ mac_out = buf_write_alloc (&work, mac_len);
+ ASSERT (mac_out);
+
+ dmsg (D_PACKET_CONTENT, "ENCRYPT FROM: %s", format_hex (BPTR (buf), BLEN (buf), 80, &gc));
+
+ /* Buffer overflow check */
+ if (!buf_safe (&work, buf->len + cipher_ctx_block_size(ctx->cipher)))
+ {
+ msg (D_CRYPT_ERRORS,
+ "ENCRYPT: buffer size error, bc=%d bo=%d bl=%d wc=%d wo=%d wl=%d",
+ buf->capacity, buf->offset, buf->len, work.capacity, work.offset,
+ work.len);
+ goto err;
+ }
+
+ /* For AEAD ciphers, authenticate Additional Data, including opcode */
+ ASSERT (cipher_ctx_update_ad (ctx->cipher, BPTR (&work), BLEN (&work) - mac_len));
+ dmsg (D_PACKET_CONTENT, "ENCRYPT AD: %s",
+ format_hex (BPTR (&work), BLEN (&work) - mac_len, 0, &gc));
+
+ /* Encrypt packet ID, payload */
+ ASSERT (cipher_ctx_update (ctx->cipher, BEND (&work), &outlen, BPTR (buf), BLEN (buf)));
+ ASSERT (buf_inc_len (&work, outlen));
+
+ /* Flush the encryption buffer */
+ ASSERT (cipher_ctx_final (ctx->cipher, BEND (&work), &outlen));
+ ASSERT (buf_inc_len (&work, outlen));
+
+ /* Write authentication tag */
+ ASSERT (cipher_ctx_get_tag (ctx->cipher, mac_out, mac_len));
+
+ *buf = work;
+
+ dmsg (D_PACKET_CONTENT, "ENCRYPT TO: %s", format_hex (BPTR (buf), BLEN (buf), 80, &gc));
+
+ gc_free (&gc);
+ return;
+
+err:
+ crypto_clear_error();
+ buf->len = 0;
+ gc_free (&gc);
+ return;
+#else /* HAVE_AEAD_CIPHER_MODES */
+ ASSERT (0);
+#endif
}
-void
-openvpn_encrypt (struct buffer *buf, struct buffer work,
- const struct crypto_options *opt,
- const struct frame* frame)
+static void
+openvpn_encrypt_v1 (struct buffer *buf, struct buffer work,
+ struct crypto_options *opt)
{
struct gc_arena gc;
gc_init (&gc);
- if (buf->len > 0 && opt->key_ctx_bi)
+ if (buf->len > 0 && opt)
{
- struct key_ctx *ctx = &opt->key_ctx_bi->encrypt;
+ const struct key_ctx *ctx = &opt->key_ctx_bi.encrypt;
+ uint8_t *mac_out = NULL;
+ const uint8_t *hmac_start = NULL;
/* Do Encrypt from buf -> work */
if (ctx->cipher)
@@ -103,6 +180,14 @@ openvpn_encrypt (struct buffer *buf, struct buffer work,
const cipher_kt_t *cipher_kt = cipher_ctx_get_cipher_kt (ctx->cipher);
int outlen;
+ /* Reserve space for HMAC */
+ if (ctx->hmac)
+ {
+ mac_out = buf_write_alloc (&work, hmac_ctx_size(ctx->hmac));
+ ASSERT (mac_out);
+ hmac_start = BEND(&work);
+ }
+
if (cipher_kt_mode_cbc(cipher_kt))
{
CLEAR (iv_buf);
@@ -111,11 +196,11 @@ openvpn_encrypt (struct buffer *buf, struct buffer work,
if (opt->flags & CO_USE_IV)
prng_bytes (iv_buf, iv_size);
- /* Put packet ID in plaintext buffer or IV, depending on cipher mode */
- if (opt->packet_id)
+ /* Put packet ID in plaintext buffer */
+ if (packet_id_initialized(&opt->packet_id))
{
struct packet_id_net pin;
- packet_id_alloc_outgoing (&opt->packet_id->send, &pin, BOOL_CAST (opt->flags & CO_PACKET_ID_LONG_FORM));
+ packet_id_alloc_outgoing (&opt->packet_id.send, &pin, BOOL_CAST (opt->flags & CO_PACKET_ID_LONG_FORM));
ASSERT (packet_id_write (&pin, buf, BOOL_CAST (opt->flags & CO_PACKET_ID_LONG_FORM), true));
}
}
@@ -124,10 +209,11 @@ openvpn_encrypt (struct buffer *buf, struct buffer work,
struct packet_id_net pin;
struct buffer b;
- ASSERT (opt->flags & CO_USE_IV); /* IV and packet-ID required */
- ASSERT (opt->packet_id); /* for this mode. */
+ /* IV and packet-ID required for this mode. */
+ ASSERT (opt->flags & CO_USE_IV);
+ ASSERT (packet_id_initialized(&opt->packet_id));
- packet_id_alloc_outgoing (&opt->packet_id->send, &pin, true);
+ packet_id_alloc_outgoing (&opt->packet_id.send, &pin, true);
memset (iv_buf, 0, iv_size);
buf_set_write (&b, iv_buf, iv_size);
ASSERT (packet_id_write (&pin, &b, true, false));
@@ -137,12 +223,12 @@ openvpn_encrypt (struct buffer *buf, struct buffer work,
ASSERT (0);
}
- /* initialize work buffer with FRAME_HEADROOM bytes of prepend capacity */
- ASSERT (buf_init (&work, FRAME_HEADROOM (frame)));
-
/* set the IV pseudo-randomly */
if (opt->flags & CO_USE_IV)
- dmsg (D_PACKET_CONTENT, "ENCRYPT IV: %s", format_hex (iv_buf, iv_size, 0, &gc));
+ {
+ ASSERT (buf_write(&work, iv_buf, iv_size));
+ dmsg (D_PACKET_CONTENT, "ENCRYPT IV: %s", format_hex (iv_buf, iv_size, 0, &gc));
+ }
dmsg (D_PACKET_CONTENT, "ENCRYPT FROM: %s",
format_hex (BPTR (buf), BLEN (buf), 80, &gc));
@@ -165,52 +251,50 @@ openvpn_encrypt (struct buffer *buf, struct buffer work,
}
/* Encrypt packet ID, payload */
- ASSERT (cipher_ctx_update (ctx->cipher, BPTR (&work), &outlen, BPTR (buf), BLEN (buf)));
+ ASSERT (cipher_ctx_update (ctx->cipher, BEND (&work), &outlen, BPTR (buf), BLEN (buf)));
ASSERT (buf_inc_len(&work, outlen));
/* Flush the encryption buffer */
- ASSERT (cipher_ctx_final(ctx->cipher, BPTR (&work) + outlen, &outlen));
+ ASSERT (cipher_ctx_final(ctx->cipher, BEND (&work), &outlen));
ASSERT (buf_inc_len(&work, outlen));
/* For all CBC mode ciphers, check the last block is complete */
ASSERT (cipher_kt_mode (cipher_kt) != OPENVPN_MODE_CBC ||
outlen == iv_size);
-
- /* prepend the IV to the ciphertext */
- if (opt->flags & CO_USE_IV)
- {
- uint8_t *output = buf_prepend (&work, iv_size);
- ASSERT (output);
- memcpy (output, iv_buf, iv_size);
- }
-
- dmsg (D_PACKET_CONTENT, "ENCRYPT TO: %s",
- format_hex (BPTR (&work), BLEN (&work), 80, &gc));
}
else /* No Encryption */
{
- if (opt->packet_id)
+ if (packet_id_initialized(&opt->packet_id))
{
struct packet_id_net pin;
- packet_id_alloc_outgoing (&opt->packet_id->send, &pin, BOOL_CAST (opt->flags & CO_PACKET_ID_LONG_FORM));
+ packet_id_alloc_outgoing (&opt->packet_id.send, &pin, BOOL_CAST (opt->flags & CO_PACKET_ID_LONG_FORM));
ASSERT (packet_id_write (&pin, buf, BOOL_CAST (opt->flags & CO_PACKET_ID_LONG_FORM), true));
}
+ if (ctx->hmac)
+ {
+ hmac_start = BPTR(buf);
+ ASSERT (mac_out = buf_prepend (buf, hmac_ctx_size(ctx->hmac)));
+ }
+ if (BLEN(&work)) {
+ buf_write_prepend(buf, BPTR(&work), BLEN(&work));
+ }
work = *buf;
}
/* HMAC the ciphertext (or plaintext if !cipher) */
if (ctx->hmac)
{
- uint8_t *output = NULL;
-
hmac_ctx_reset (ctx->hmac);
- hmac_ctx_update (ctx->hmac, BPTR(&work), BLEN(&work));
- output = buf_prepend (&work, hmac_ctx_size(ctx->hmac));
- ASSERT (output);
- hmac_ctx_final (ctx->hmac, output);
+ hmac_ctx_update (ctx->hmac, hmac_start, BEND(&work) - hmac_start);
+ hmac_ctx_final (ctx->hmac, mac_out);
+ dmsg (D_PACKET_CONTENT, "ENCRYPT HMAC: %s",
+ format_hex (mac_out, hmac_ctx_size(ctx->hmac), 80, &gc));
}
*buf = work;
+
+ dmsg (D_PACKET_CONTENT, "ENCRYPT TO: %s",
+ format_hex (BPTR (&work), BLEN (&work), 80, &gc));
}
gc_free (&gc);
@@ -223,6 +307,47 @@ err:
return;
}
+void
+openvpn_encrypt (struct buffer *buf, struct buffer work,
+ struct crypto_options *opt)
+{
+ if (buf->len > 0 && opt)
+ {
+ const cipher_kt_t *cipher_kt =
+ cipher_ctx_get_cipher_kt(opt->key_ctx_bi.encrypt.cipher);
+
+ if (cipher_kt_mode_aead (cipher_kt))
+ openvpn_encrypt_aead(buf, work, opt);
+ else
+ openvpn_encrypt_v1(buf, work, opt);
+ }
+}
+
+bool crypto_check_replay(struct crypto_options *opt,
+ const struct packet_id_net *pin, const char *error_prefix,
+ struct gc_arena *gc) {
+ bool ret = false;
+ packet_id_reap_test (&opt->packet_id.rec);
+ if (packet_id_test (&opt->packet_id.rec, pin))
+ {
+ packet_id_add (&opt->packet_id.rec, pin);
+ if (opt->pid_persist && (opt->flags & CO_PACKET_ID_LONG_FORM))
+ packet_id_persist_save_obj (opt->pid_persist, &opt->packet_id);
+ ret = true;
+ }
+ else
+ {
+ if (!(opt->flags & CO_MUTE_REPLAY_WARNINGS))
+ {
+ msg (D_REPLAY_ERRORS, "%s: bad packet ID (may be a replay): %s -- "
+ "see the man page entry for --no-replay and --replay-window for "
+ "more info or silence this warning with --mute-replay-warnings",
+ error_prefix, packet_id_net_print (pin, true, gc));
+ }
+ }
+ return ret;
+}
+
/*
* If (opt->flags & CO_USE_IV) is not NULL, we will read an IV from the packet.
*
@@ -231,21 +356,169 @@ err:
* On success, buf is set to point to plaintext, true
* is returned.
*/
-bool
-openvpn_decrypt (struct buffer *buf, struct buffer work,
- const struct crypto_options *opt,
- const struct frame* frame)
+static bool
+openvpn_decrypt_aead (struct buffer *buf, struct buffer work,
+ struct crypto_options *opt, const struct frame* frame,
+ const uint8_t *ad_start)
+{
+#ifdef HAVE_AEAD_CIPHER_MODES
+ static const char error_prefix[] = "AEAD Decrypt error";
+ struct packet_id_net pin = { 0 };
+ const struct key_ctx *ctx = &opt->key_ctx_bi.decrypt;
+ const cipher_kt_t *cipher_kt = cipher_ctx_get_cipher_kt (ctx->cipher);
+ uint8_t *tag_ptr = NULL;
+ int tag_size = 0;
+ int outlen;
+ struct gc_arena gc;
+
+ gc_init (&gc);
+
+ ASSERT (opt);
+ ASSERT (frame);
+ ASSERT (buf->len > 0);
+ ASSERT (ctx->cipher);
+ ASSERT (cipher_kt_mode_aead (cipher_kt));
+
+ dmsg (D_PACKET_CONTENT, "DECRYPT FROM: %s",
+ format_hex (BPTR (buf), BLEN (buf), 80, &gc));
+
+ ASSERT (ad_start >= buf->data && ad_start <= BPTR (buf));
+
+ ASSERT (buf_init (&work, FRAME_HEADROOM_ADJ (frame, FRAME_HEADROOM_MARKER_DECRYPT)));
+
+ /* IV and Packet ID required for this mode */
+ ASSERT (packet_id_initialized (&opt->packet_id));
+ ASSERT (opt->flags & CO_USE_IV);
+
+ /* Combine IV from explicit part from packet and implicit part from context */
+ {
+ uint8_t iv[OPENVPN_MAX_IV_LENGTH] = { 0 };
+ const int iv_len = cipher_ctx_iv_length (ctx->cipher);
+ const size_t packet_iv_len = iv_len - ctx->implicit_iv_len;
+
+ ASSERT (ctx->implicit_iv_len <= iv_len);
+ if (buf->len + ctx->implicit_iv_len < iv_len)
+ CRYPT_ERROR ("missing IV info");
+
+ memcpy (iv, BPTR(buf), packet_iv_len);
+ memcpy (iv + packet_iv_len, ctx->implicit_iv, ctx->implicit_iv_len);
+
+ dmsg (D_PACKET_CONTENT, "DECRYPT IV: %s", format_hex (iv, iv_len, 0, &gc));
+
+ /* Load IV, ctx->cipher was already initialized with key & keylen */
+ if (!cipher_ctx_reset (ctx->cipher, iv))
+ {
+ CRYPT_ERROR ("cipher init failed");
+ }
+ }
+
+ /* Read packet ID from packet */
+ if (!packet_id_read (&pin, buf, false))
+ {
+ CRYPT_ERROR ("error reading packet-id");
+ }
+
+ /* keep the tag value to feed in later */
+ tag_size = cipher_kt_tag_size(cipher_kt);
+ if (buf->len < tag_size)
+ {
+ CRYPT_ERROR ("missing tag");
+ }
+ tag_ptr = BPTR(buf);
+ ASSERT (buf_advance (buf, tag_size));
+ dmsg (D_PACKET_CONTENT, "DECRYPT MAC: %s", format_hex (tag_ptr, tag_size, 0, &gc));
+#if defined(ENABLE_CRYPTO_OPENSSL) && OPENSSL_VERSION_NUMBER < 0x10001040L
+ /* OpenSSL <= 1.0.1c bug requires set tag before processing ciphertext */
+ if (!EVP_CIPHER_CTX_ctrl (ctx->cipher, EVP_CTRL_GCM_SET_TAG, tag_size, tag_ptr))
+ {
+ CRYPT_ERROR ("setting tag failed");
+ }
+#endif
+
+ if (buf->len < 1)
+ {
+ CRYPT_ERROR ("missing payload");
+ }
+
+ dmsg (D_PACKET_CONTENT, "DECRYPT FROM: %s", format_hex (BPTR(buf), BLEN(buf), 0, &gc));
+
+ /* Buffer overflow check (should never fail) */
+ if (!buf_safe (&work, buf->len + cipher_ctx_block_size(ctx->cipher)))
+ {
+ CRYPT_ERROR ("potential buffer overflow");
+ }
+
+ {
+ /* feed in tag and the authenticated data */
+ const int ad_size = BPTR (buf) - ad_start - tag_size;
+ ASSERT (cipher_ctx_update_ad (ctx->cipher, ad_start, ad_size));
+ dmsg (D_PACKET_CONTENT, "DECRYPT AD: %s",
+ format_hex (BPTR (buf) - ad_size - tag_size, ad_size, 0, &gc));
+ }
+
+ /* Decrypt and authenticate packet */
+ if (!cipher_ctx_update (ctx->cipher, BPTR (&work), &outlen, BPTR (buf),
+ BLEN (buf)))
+ {
+ CRYPT_ERROR ("cipher update failed");
+ }
+ ASSERT (buf_inc_len (&work, outlen));
+ if (!cipher_ctx_final_check_tag (ctx->cipher, BPTR (&work) + outlen,
+ &outlen, tag_ptr, tag_size))
+ {
+ CRYPT_ERROR ("cipher final failed");
+ }
+ ASSERT (buf_inc_len (&work, outlen));
+
+ dmsg (D_PACKET_CONTENT, "DECRYPT TO: %s",
+ format_hex (BPTR (&work), BLEN (&work), 80, &gc));
+
+ if (!crypto_check_replay (opt, &pin, error_prefix, &gc))
+ {
+ goto error_exit;
+ }
+
+ *buf = work;
+
+ gc_free (&gc);
+ return true;
+
+ error_exit:
+ crypto_clear_error();
+ buf->len = 0;
+ gc_free (&gc);
+ return false;
+#else /* HAVE_AEAD_CIPHER_MODES */
+ ASSERT (0);
+ return false;
+#endif
+}
+
+/*
+ * If (opt->flags & CO_USE_IV) is not NULL, we will read an IV from the packet.
+ *
+ * Set buf->len to 0 and return false on decrypt error.
+ *
+ * On success, buf is set to point to plaintext, true
+ * is returned.
+ */
+static bool
+openvpn_decrypt_v1 (struct buffer *buf, struct buffer work,
+ struct crypto_options *opt, const struct frame* frame)
{
static const char error_prefix[] = "Authenticate/Decrypt packet error";
struct gc_arena gc;
gc_init (&gc);
- if (buf->len > 0 && opt->key_ctx_bi)
+ if (buf->len > 0 && opt)
{
- struct key_ctx *ctx = &opt->key_ctx_bi->decrypt;
+ const struct key_ctx *ctx = &opt->key_ctx_bi.decrypt;
struct packet_id_net pin;
bool have_pin = false;
+ dmsg (D_PACKET_CONTENT, "DECRYPT FROM: %s",
+ format_hex (BPTR (buf), BLEN (buf), 80, &gc));
+
/* Verify the HMAC */
if (ctx->hmac)
{
@@ -325,7 +598,7 @@ openvpn_decrypt (struct buffer *buf, struct buffer work,
{
if (cipher_kt_mode_cbc(cipher_kt))
{
- if (opt->packet_id)
+ if (packet_id_initialized(&opt->packet_id))
{
if (!packet_id_read (&pin, &work, BOOL_CAST (opt->flags & CO_PACKET_ID_LONG_FORM)))
CRYPT_ERROR ("error reading CBC packet-id");
@@ -336,8 +609,9 @@ openvpn_decrypt (struct buffer *buf, struct buffer work,
{
struct buffer b;
- ASSERT (opt->flags & CO_USE_IV); /* IV and packet-ID required */
- ASSERT (opt->packet_id); /* for this mode. */
+ /* IV and packet-ID required for this mode. */
+ ASSERT (opt->flags & CO_USE_IV);
+ ASSERT (packet_id_initialized(&opt->packet_id));
buf_set_read (&b, iv_buf, iv_size);
if (!packet_id_read (&pin, &b, true))
@@ -353,7 +627,7 @@ openvpn_decrypt (struct buffer *buf, struct buffer work,
else
{
work = *buf;
- if (opt->packet_id)
+ if (packet_id_initialized(&opt->packet_id))
{
if (!packet_id_read (&pin, &work, BOOL_CAST (opt->flags & CO_PACKET_ID_LONG_FORM)))
CRYPT_ERROR ("error reading packet-id");
@@ -361,22 +635,9 @@ openvpn_decrypt (struct buffer *buf, struct buffer work,
}
}
- if (have_pin)
+ if (have_pin && !crypto_check_replay(opt, &pin, error_prefix, &gc))
{
- packet_id_reap_test (&opt->packet_id->rec);
- if (packet_id_test (&opt->packet_id->rec, &pin))
- {
- packet_id_add (&opt->packet_id->rec, &pin);
- if (opt->pid_persist && (opt->flags & CO_PACKET_ID_LONG_FORM))
- packet_id_persist_save_obj (opt->pid_persist, opt->packet_id);
- }
- else
- {
- if (!(opt->flags & CO_MUTE_REPLAY_WARNINGS))
- msg (D_REPLAY_ERRORS, "%s: bad packet ID (may be a replay): %s -- see the man page entry for --no-replay and --replay-window for more info or silence this warning with --mute-replay-warnings",
- error_prefix, packet_id_net_print (&pin, true, &gc));
- goto error_exit;
- }
+ goto error_exit;
}
*buf = work;
}
@@ -391,14 +652,36 @@ openvpn_decrypt (struct buffer *buf, struct buffer work,
return false;
}
-/*
- * How many bytes will we add to frame buffer for a given
- * set of crypto options?
- */
+
+bool
+openvpn_decrypt (struct buffer *buf, struct buffer work,
+ struct crypto_options *opt, const struct frame* frame,
+ const uint8_t *ad_start)
+{
+ bool ret = false;
+
+ if (buf->len > 0 && opt)
+ {
+ const struct key_ctx *ctx = &opt->key_ctx_bi.decrypt;
+ if (cipher_kt_mode_aead (cipher_ctx_get_cipher_kt (ctx->cipher)))
+ {
+ ret = openvpn_decrypt_aead (buf, work, opt, frame, ad_start);
+ }
+ else
+ {
+ ret = openvpn_decrypt_v1 (buf, work, opt, frame);
+ }
+ }
+ else
+ {
+ ret = true;
+ }
+ return ret;
+}
+
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)
@@ -408,11 +691,14 @@ crypto_adjust_frame_parameters(struct frame *frame,
if (packet_id)
crypto_overhead += packet_id_size (packet_id_long_form);
- if (cipher_defined)
+ if (kt->cipher)
{
if (use_iv)
crypto_overhead += cipher_kt_iv_size (kt->cipher);
+ if (cipher_kt_mode_aead (kt->cipher))
+ crypto_overhead += cipher_kt_tag_size (kt->cipher);
+
/* extra block required by cipher_ctx_update() */
crypto_overhead += cipher_kt_block_size (kt->cipher);
}
@@ -421,8 +707,16 @@ crypto_adjust_frame_parameters(struct frame *frame,
frame_add_to_extra_frame (frame, crypto_overhead);
- msg(D_MTU_DEBUG, "%s: Adjusting frame parameters for crypto by %zu bytes",
- __func__, crypto_overhead);
+ msg(D_MTU_DEBUG, "%s: Adjusting frame parameters for crypto by %u bytes",
+ __func__, (unsigned int) crypto_overhead);
+}
+
+size_t
+crypto_max_overhead(void)
+{
+ return packet_id_size(true) + OPENVPN_MAX_IV_LENGTH +
+ OPENVPN_MAX_CIPHER_BLOCK_SIZE +
+ max_int (OPENVPN_MAX_HMAC_SIZE, OPENVPN_AEAD_TAG_LENGTH);
}
/*
@@ -430,39 +724,55 @@ crypto_adjust_frame_parameters(struct frame *frame,
*/
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)
{
+ bool aead_cipher = false;
+
+ ASSERT(ciphername);
+ ASSERT(authname);
+
CLEAR (*kt);
- if (ciphername && ciphername_defined)
+ if (strcmp (ciphername, "none") != 0)
{
kt->cipher = cipher_kt_get (translate_cipher_name_from_openvpn(ciphername));
+ if (!kt->cipher)
+ {
+ msg (M_FATAL, "Cipher %s not supported", ciphername);
+ }
+
kt->cipher_length = cipher_kt_key_size (kt->cipher);
if (keysize > 0 && keysize <= MAX_CIPHER_KEY_LENGTH)
kt->cipher_length = keysize;
/* check legal cipher mode */
- {
- if (!(cipher_kt_mode_cbc(kt->cipher)
+ aead_cipher = cipher_kt_mode_aead(kt->cipher);
+ if (!(cipher_kt_mode_cbc(kt->cipher)
+ || (tls_mode && aead_cipher)
#ifdef ENABLE_OFB_CFB_MODE
- || (cfb_ofb_allowed && cipher_kt_mode_ofb_cfb(kt->cipher))
+ || (tls_mode && cipher_kt_mode_ofb_cfb(kt->cipher))
#endif
- ))
- msg (M_FATAL, "Cipher '%s' mode not supported", ciphername);
- }
+ ))
+ msg (M_FATAL, "Cipher '%s' mode not supported", ciphername);
+
+ if (OPENVPN_MAX_CIPHER_BLOCK_SIZE < cipher_kt_block_size(kt->cipher))
+ msg (M_FATAL, "Cipher '%s' not allowed: block size too big.", ciphername);
}
else
{
if (warn)
msg (M_WARN, "******* WARNING *******: null cipher specified, no encryption will be used");
}
- if (authname && authname_defined)
+ if (strcmp (authname, "none") != 0)
{
- kt->digest = md_kt_get (authname);
- kt->hmac_length = md_kt_size (kt->digest);
+ if (!aead_cipher) { /* Ignore auth for AEAD ciphers */
+ kt->digest = md_kt_get (authname);
+ kt->hmac_length = md_kt_size (kt->digest);
+
+ if (OPENVPN_MAX_HMAC_SIZE < kt->hmac_length)
+ msg (M_FATAL, "HMAC '%s' not allowed: digest size too big.", authname);
+ }
}
- else
+ else if (!aead_cipher)
{
if (warn)
msg (M_WARN, "******* WARNING *******: null MAC specified, no authentication will be used");
@@ -486,15 +796,21 @@ init_key_ctx (struct key_ctx *ctx, struct key *key,
msg (D_HANDSHAKE, "%s: Cipher '%s' initialized with %d bit key",
prefix,
- cipher_kt_name(kt->cipher),
+ translate_cipher_name_to_openvpn(cipher_kt_name(kt->cipher)),
kt->cipher_length *8);
dmsg (D_SHOW_KEYS, "%s: CIPHER KEY: %s", prefix,
format_hex (key->cipher, kt->cipher_length, 0, &gc));
dmsg (D_CRYPTO_DEBUG, "%s: CIPHER block_size=%d iv_size=%d",
- prefix,
- cipher_kt_block_size(kt->cipher),
- cipher_kt_iv_size(kt->cipher));
+ prefix, cipher_kt_block_size(kt->cipher),
+ cipher_kt_iv_size(kt->cipher));
+ if (cipher_kt_block_size(kt->cipher) < 128/8)
+ {
+ msg (M_WARN, "WARNING: INSECURE cipher with block size less than 128"
+ " bit (%d bit). This allows attacks like SWEET32. Mitigate by "
+ "using a --cipher with a larger block size (e.g. AES-256-CBC).",
+ cipher_kt_block_size(kt->cipher)*8);
+ }
}
if (kt->digest && kt->hmac_length > 0)
{
@@ -532,6 +848,7 @@ free_key_ctx (struct key_ctx *ctx)
free(ctx->hmac);
ctx->hmac = NULL;
}
+ ctx->implicit_iv_len = 0;
}
void
@@ -541,7 +858,6 @@ free_key_ctx_bi (struct key_ctx_bi *ctx)
free_key_ctx(&ctx->decrypt);
}
-
static bool
key_is_zero (struct key *key, const struct key_type *kt)
{
@@ -621,8 +937,10 @@ check_replay_iv_consistency (const struct key_type *kt, bool packet_id, bool use
{
ASSERT(kt);
- if (cipher_kt_mode_ofb_cfb(kt->cipher) && !(packet_id && use_iv))
- msg (M_FATAL, "--no-replay or --no-iv cannot be used with a CFB or OFB mode cipher");
+ if (!(packet_id && use_iv) && (cipher_kt_mode_ofb_cfb(kt->cipher) ||
+ cipher_kt_mode_aead(kt->cipher)))
+ msg (M_FATAL, "--no-replay or --no-iv cannot be used with a CFB, OFB or "
+ "AEAD mode cipher");
}
/*
@@ -688,7 +1006,7 @@ key2_print (const struct key2* k,
}
void
-test_crypto (const struct crypto_options *co, struct frame* frame)
+test_crypto (struct crypto_options *co, struct frame* frame)
{
int i, j;
struct gc_arena gc = gc_new ();
@@ -697,10 +1015,35 @@ test_crypto (const struct crypto_options *co, struct frame* frame)
struct buffer encrypt_workspace = alloc_buf_gc (BUF_SIZE (frame), &gc);
struct buffer decrypt_workspace = alloc_buf_gc (BUF_SIZE (frame), &gc);
struct buffer buf = clear_buf();
+ void *buf_p;
/* init work */
ASSERT (buf_init (&work, FRAME_HEADROOM (frame)));
+#ifdef HAVE_AEAD_CIPHER_MODES
+ /* init implicit IV */
+ {
+ const cipher_kt_t *cipher =
+ cipher_ctx_get_cipher_kt(co->key_ctx_bi.encrypt.cipher);
+
+ if (cipher_kt_mode_aead(cipher))
+ {
+ size_t impl_iv_len = cipher_kt_iv_size(cipher) - sizeof(packet_id_type);
+ ASSERT (cipher_kt_iv_size(cipher) <= OPENVPN_MAX_IV_LENGTH);
+ ASSERT (cipher_kt_iv_size(cipher) >= OPENVPN_AEAD_MIN_IV_LEN);
+
+ /* Generate dummy implicit IV */
+ ASSERT (rand_bytes(co->key_ctx_bi.encrypt.implicit_iv,
+ OPENVPN_MAX_IV_LENGTH));
+ co->key_ctx_bi.encrypt.implicit_iv_len = impl_iv_len;
+
+ memcpy(co->key_ctx_bi.decrypt.implicit_iv,
+ co->key_ctx_bi.encrypt.implicit_iv, OPENVPN_MAX_IV_LENGTH);
+ co->key_ctx_bi.decrypt.implicit_iv_len = impl_iv_len;
+ }
+ }
+#endif
+
msg (M_INFO, "Entering " PACKAGE_NAME " crypto self-test mode.");
for (i = 1; i <= TUN_MTU_SIZE (frame); ++i)
{
@@ -718,13 +1061,18 @@ test_crypto (const struct crypto_options *co, struct frame* frame)
/* copy source to input buf */
buf = work;
- memcpy (buf_write_alloc (&buf, BLEN (&src)), BPTR (&src), BLEN (&src));
+ buf_p = buf_write_alloc (&buf, BLEN (&src));
+ ASSERT(buf_p);
+ memcpy (buf_p, BPTR (&src), BLEN (&src));
+
+ /* initialize work buffer with FRAME_HEADROOM bytes of prepend capacity */
+ ASSERT (buf_init (&encrypt_workspace, FRAME_HEADROOM (frame)));
/* encrypt */
- openvpn_encrypt (&buf, encrypt_workspace, co, frame);
+ openvpn_encrypt (&buf, encrypt_workspace, co);
/* decrypt */
- openvpn_decrypt (&buf, decrypt_workspace, co, frame);
+ openvpn_decrypt (&buf, decrypt_workspace, co, frame, BPTR (&buf));
/* compare */
if (buf.len != src.len)
@@ -741,90 +1089,47 @@ test_crypto (const struct crypto_options *co, struct frame* frame)
gc_free (&gc);
}
-#ifdef ENABLE_SSL
-
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)
+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)
{
- if (passphrase_file && key_type->hmac_length)
- {
- struct key2 key2;
- struct key_type kt = *key_type;
- struct key_direction_state kds;
-
- /* for control channel we are only authenticating, not encrypting */
- kt.cipher_length = 0;
- kt.cipher = NULL;
-
- if (flags & GHK_INLINE)
- {
- /* key was specified inline, key text is in passphrase_file */
- read_key_file (&key2, passphrase_file, RKF_INLINE|RKF_MUST_SUCCEED);
-
- /* succeeded? */
- if (key2.n == 2)
- msg (M_INFO, "Control Channel Authentication: tls-auth using INLINE static key file");
- else
- msg (M_FATAL, "INLINE tls-auth file lacks the requisite 2 keys");
- }
- else
- {
- /* first try to parse as an OpenVPN static key file */
- read_key_file (&key2, passphrase_file, 0);
-
- /* succeeded? */
- if (key2.n == 2)
- {
- msg (M_INFO,
- "Control Channel Authentication: using '%s' as a " PACKAGE_NAME " static key file",
- passphrase_file);
- }
- else
- {
- int hash_size;
-
- CLEAR (key2);
-
- /* failed, now try to get hash from a freeform file */
- hash_size = read_passphrase_hash (passphrase_file,
- kt.digest,
- key2.keys[0].hmac,
- MAX_HMAC_KEY_LENGTH);
- ASSERT (hash_size == kt.hmac_length);
+ struct key2 key2;
+ struct key_direction_state kds;
+ char log_prefix[128] = { 0 };
- /* suceeded */
- key2.n = 1;
+ if (key_inline)
+ {
+ read_key_file (&key2, key_inline, RKF_MUST_SUCCEED|RKF_INLINE);
+ }
+ else
+ {
+ read_key_file (&key2, key_file, RKF_MUST_SUCCEED);
+ }
- msg (M_INFO,
- "Control Channel Authentication: using '%s' as a free-form passphrase file",
- passphrase_file);
- msg (M_WARN, "DEPRECATED OPTION: Using freeform files for tls-auth is deprecated and is not supported in OpenVPN 2.4 or newer versions");
- }
- }
- /* handle key direction */
+ if (key2.n != 2)
+ {
+ msg (M_ERR, "File '%s' does not have OpenVPN Static Key format. Using "
+ "free-form passphrase file is not supported anymore.", key_file);
+ }
- key_direction_state_init (&kds, key_direction);
- must_have_n_keys (passphrase_file, "tls-auth", &key2, kds.need_keys);
+ /* check for and fix highly unlikely key problems */
+ verify_fix_key2 (&key2, key_type, key_file);
- /* initialize hmac key in both directions */
+ /* handle key direction */
+ key_direction_state_init (&kds, key_direction);
+ must_have_n_keys (key_file, opt_name, &key2, kds.need_keys);
- init_key_ctx (&ctx->encrypt, &key2.keys[kds.out_key], &kt, OPENVPN_OP_ENCRYPT,
- "Outgoing Control Channel Authentication");
- init_key_ctx (&ctx->decrypt, &key2.keys[kds.in_key], &kt, OPENVPN_OP_DECRYPT,
- "Incoming Control Channel Authentication");
+ /* initialize key in both directions */
+ openvpn_snprintf (log_prefix, sizeof (log_prefix), "Outgoing %s", key_name);
+ init_key_ctx (&ctx->encrypt, &key2.keys[kds.out_key], key_type,
+ OPENVPN_OP_ENCRYPT, log_prefix);
+ openvpn_snprintf (log_prefix, sizeof (log_prefix), "Incoming %s", key_name);
+ init_key_ctx (&ctx->decrypt, &key2.keys[kds.in_key], key_type,
+ OPENVPN_OP_DECRYPT, log_prefix);
- CLEAR (key2);
- }
- else
- {
- CLEAR (*ctx);
- }
+ CLEAR (key2);
}
-#endif
/* header and footer for static key file */
static const char static_key_head[] = "-----BEGIN OpenVPN Static key V1-----";
@@ -1002,9 +1307,6 @@ read_key_file (struct key2 *key2, const char *file, const unsigned int flags)
if (!(flags & RKF_INLINE))
buf_clear (&in);
- if (key2->n)
- warn_if_group_others_accessible (error_filename);
-
#if 0
/* DEBUGGING */
{
@@ -1028,55 +1330,6 @@ read_key_file (struct key2 *key2, const char *file, const unsigned int flags)
gc_free (&gc);
}
-int
-read_passphrase_hash (const char *passphrase_file,
- const md_kt_t *digest,
- uint8_t *output,
- int len)
-{
- unsigned int outlen = 0;
- md_ctx_t md;
-
- ASSERT (len >= md_kt_size(digest));
- memset (output, 0, len);
-
- md_ctx_init(&md, digest);
-
- /* read passphrase file */
- {
- const int min_passphrase_size = 8;
- uint8_t buf[64];
- int total_size = 0;
- int fd = platform_open (passphrase_file, O_RDONLY, 0);
-
- if (fd == -1)
- msg (M_ERR, "Cannot open passphrase file: '%s'", passphrase_file);
-
- for (;;)
- {
- int size = read (fd, buf, sizeof (buf));
- if (size == 0)
- break;
- if (size == -1)
- msg (M_ERR, "Read error on passphrase file: '%s'",
- passphrase_file);
- md_ctx_update(&md, buf, size);
- total_size += size;
- }
- close (fd);
-
- warn_if_group_others_accessible (passphrase_file);
-
- if (total_size < min_passphrase_size)
- msg (M_FATAL,
- "Passphrase file '%s' is too small (must have at least %d characters)",
- passphrase_file, min_passphrase_size);
- }
- md_ctx_final(&md, output);
- md_ctx_cleanup(&md);
- return md_kt_size(digest);
-}
-
/*
* Write key to file, return number of random bits
* written.
@@ -1367,7 +1620,6 @@ prng_bytes (uint8_t *output, int len)
const int md_size = md_kt_size (nonce_md);
while (len > 0)
{
- unsigned int outlen = 0;
const int blen = min_int (len, md_size);
md_full(nonce_md, nonce_data, md_size + nonce_secret_len, nonce_data);
memcpy (output, nonce_data, blen);
@@ -1397,79 +1649,42 @@ get_random()
return l;
}
-#ifndef ENABLE_SSL
+static const cipher_name_pair *
+get_cipher_name_pair(const char *cipher_name) {
+ const cipher_name_pair *pair;
+ size_t i = 0;
-void
-init_ssl_lib (void)
-{
- crypto_init_lib ();
-}
+ /* Search for a cipher name translation */
+ for (; i < cipher_name_translation_table_count; i++)
+ {
+ pair = &cipher_name_translation_table[i];
+ if (0 == strcmp (cipher_name, pair->openvpn_name) ||
+ 0 == strcmp (cipher_name, pair->lib_name))
+ return pair;
+ }
-void
-free_ssl_lib (void)
-{
- crypto_uninit_lib ();
- prng_uninit();
+ /* Nothing found, return null */
+ return NULL;
}
-#endif /* ENABLE_SSL */
-
-/*
- * md5 functions
- */
-
const char *
-md5sum (uint8_t *buf, int len, int n_print_chars, struct gc_arena *gc)
-{
- uint8_t digest[MD5_DIGEST_LENGTH];
- const md_kt_t *md5_kt = md_kt_get("MD5");
-
- md_full(md5_kt, buf, len, digest);
-
- return format_hex (digest, MD5_DIGEST_LENGTH, n_print_chars, gc);
-}
-
-void
-md5_state_init (struct md5_state *s)
-{
- const md_kt_t *md5_kt = md_kt_get("MD5");
-
- md_ctx_init(&s->ctx, md5_kt);
-}
+translate_cipher_name_from_openvpn (const char *cipher_name) {
+ const cipher_name_pair *pair = get_cipher_name_pair(cipher_name);
-void
-md5_state_update (struct md5_state *s, void *data, size_t len)
-{
- md_ctx_update(&s->ctx, data, len);
-}
+ if (NULL == pair)
+ return cipher_name;
-void
-md5_state_final (struct md5_state *s, struct md5_digest *out)
-{
- md_ctx_final(&s->ctx, out->digest);
- md_ctx_cleanup(&s->ctx);
+ return pair->lib_name;
}
-void
-md5_digest_clear (struct md5_digest *digest)
-{
- CLEAR (*digest);
-}
+const char *
+translate_cipher_name_to_openvpn (const char *cipher_name) {
+ const cipher_name_pair *pair = get_cipher_name_pair(cipher_name);
-bool
-md5_digest_defined (const struct md5_digest *digest)
-{
- int i;
- for (i = 0; i < MD5_DIGEST_LENGTH; ++i)
- if (digest->digest[i])
- return true;
- return false;
-}
+ if (NULL == pair)
+ return cipher_name;
-bool
-md5_digest_equal (const struct md5_digest *d1, const struct md5_digest *d2)
-{
- return memcmp(d1->digest, d2->digest, MD5_DIGEST_LENGTH) == 0;
+ return pair->openvpn_name;
}
#endif /* ENABLE_CRYPTO */