New upstream version 2.4~beta1upstream/2.4_beta1

1 files changed, 1226 insertions, 0 deletions

diff --git a/src/openvpn/ssl_mbedtls.c b/src/openvpn/ssl_mbedtls.c
new file mode 100644
index 0000000..7fa35a7
--- /dev/null
+++ b/src/openvpn/ssl_mbedtls.c
@@ -0,0 +1,1226 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single TCP/UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             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) 2006-2010, Brainspark B.V.
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2
+ *  as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program (see the file COPYING included with this
+ *  distribution); if not, write to the Free Software Foundation, Inc.,
+ *  59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+/**
+ * @file Control Channel mbed TLS Backend
+ */
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#elif defined(_MSC_VER)
+#include "config-msvc.h"
+#endif
+
+#include "syshead.h"
+
+#if defined(ENABLE_CRYPTO) && defined(ENABLE_CRYPTO_MBEDTLS)
+
+#include "errlevel.h"
+#include "ssl_backend.h"
+#include "base64.h"
+#include "buffer.h"
+#include "misc.h"
+#include "manage.h"
+#include "ssl_common.h"
+
+#include <mbedtls/havege.h>
+
+#include "ssl_verify_mbedtls.h"
+#include <mbedtls/debug.h>
+#include <mbedtls/error.h>
+#include <mbedtls/net.h>
+#include <mbedtls/oid.h>
+#include <mbedtls/pem.h>
+#include <mbedtls/sha256.h>
+#include <mbedtls/version.h>
+
+void
+tls_init_lib()
+{
+}
+
+void
+tls_free_lib()
+{
+}
+
+void
+tls_clear_error()
+{
+}
+
+void
+tls_ctx_server_new(struct tls_root_ctx *ctx)
+{
+  ASSERT(NULL != ctx);
+  CLEAR(*ctx);
+
+  ALLOC_OBJ_CLEAR(ctx->dhm_ctx, mbedtls_dhm_context);
+
+  ALLOC_OBJ_CLEAR(ctx->ca_chain, mbedtls_x509_crt);
+
+  ctx->endpoint = MBEDTLS_SSL_IS_SERVER;
+  ctx->initialised = true;
+}
+
+void
+tls_ctx_client_new(struct tls_root_ctx *ctx)
+{
+  ASSERT(NULL != ctx);
+  CLEAR(*ctx);
+
+  ALLOC_OBJ_CLEAR(ctx->dhm_ctx, mbedtls_dhm_context);
+  ALLOC_OBJ_CLEAR(ctx->ca_chain, mbedtls_x509_crt);
+
+  ctx->endpoint = MBEDTLS_SSL_IS_CLIENT;
+  ctx->initialised = true;
+}
+
+void
+tls_ctx_free(struct tls_root_ctx *ctx)
+{
+  if (ctx)
+    {
+      mbedtls_pk_free(ctx->priv_key);
+      if (ctx->priv_key)
+	free(ctx->priv_key);
+
+      mbedtls_x509_crt_free(ctx->ca_chain);
+      if (ctx->ca_chain)
+	free(ctx->ca_chain);
+
+      mbedtls_x509_crt_free(ctx->crt_chain);
+      if (ctx->crt_chain)
+	free(ctx->crt_chain);
+
+      mbedtls_dhm_free(ctx->dhm_ctx);
+      if (ctx->dhm_ctx)
+	free(ctx->dhm_ctx);
+
+      mbedtls_x509_crl_free(ctx->crl);
+      if (ctx->crl)
+	{
+	  free(ctx->crl);
+	}
+
+#if defined(ENABLE_PKCS11)
+      if (ctx->priv_key_pkcs11 != NULL) {
+	  mbedtls_pkcs11_priv_key_free(ctx->priv_key_pkcs11);
+	  free(ctx->priv_key_pkcs11);
+      }
+#endif
+#if defined(MANAGMENT_EXTERNAL_KEY)
+      if (ctx->external_key != NULL)
+          free(ctx->external_key);
+#endif
+
+      if (ctx->allowed_ciphers)
+	free(ctx->allowed_ciphers);
+
+      CLEAR(*ctx);
+
+      ctx->initialised = false;
+
+    }
+}
+
+bool
+tls_ctx_initialised(struct tls_root_ctx *ctx)
+{
+  ASSERT(NULL != ctx);
+  return ctx->initialised;
+}
+
+void
+key_state_export_keying_material(struct key_state_ssl *ssl,
+                                 struct tls_session *session)
+{
+}
+
+void
+tls_ctx_set_options (struct tls_root_ctx *ctx, unsigned int ssl_flags)
+{
+}
+
+static const char *
+tls_translate_cipher_name (const char * cipher_name) {
+  const tls_cipher_name_pair * pair = tls_get_cipher_name_pair(cipher_name, strlen(cipher_name));
+
+  if (NULL == pair)
+    {
+      // No translation found, return original
+      return cipher_name;
+    }
+
+  if (0 != strcmp(cipher_name, pair->iana_name))
+    {
+      // Deprecated name found, notify user
+      msg(M_WARN, "Deprecated cipher suite name '%s', please use IANA name '%s'", pair->openssl_name, pair->iana_name);
+    }
+
+  return pair->iana_name;
+}
+
+void
+tls_ctx_restrict_ciphers(struct tls_root_ctx *ctx, const char *ciphers)
+{
+  char *tmp_ciphers, *tmp_ciphers_orig, *token;
+  int i, cipher_count;
+  int ciphers_len;
+
+  if (NULL == ciphers)
+    return; /* Nothing to do */
+
+  ciphers_len = strlen (ciphers);
+
+  ASSERT (NULL != ctx);
+  ASSERT (0 != ciphers_len);
+
+  /* Get number of ciphers */
+  for (i = 0, cipher_count = 1; i < ciphers_len; i++)
+    if (ciphers[i] == ':')
+      cipher_count++;
+
+  /* Allocate an array for them */
+  ALLOC_ARRAY_CLEAR(ctx->allowed_ciphers, int, cipher_count+1)
+
+  /* Parse allowed ciphers, getting IDs */
+  i = 0;
+  tmp_ciphers_orig = tmp_ciphers = string_alloc (ciphers, NULL);
+
+  token = strtok (tmp_ciphers, ":");
+  while(token)
+    {
+      ctx->allowed_ciphers[i] = mbedtls_ssl_get_ciphersuite_id (
+	  tls_translate_cipher_name (token));
+      if (0 != ctx->allowed_ciphers[i])
+	i++;
+      token = strtok (NULL, ":");
+    }
+  free(tmp_ciphers_orig);
+}
+
+void
+tls_ctx_check_cert_time (const struct tls_root_ctx *ctx)
+{
+  ASSERT (ctx);
+  if (ctx->crt_chain == NULL)
+    {
+      return; /* Nothing to check if there is no certificate */
+    }
+
+  if (mbedtls_x509_time_is_future (&ctx->crt_chain->valid_from))
+    {
+      msg (M_WARN, "WARNING: Your certificate is not yet valid!");
+    }
+
+  if (mbedtls_x509_time_is_past (&ctx->crt_chain->valid_to))
+    {
+      msg (M_WARN, "WARNING: Your certificate has expired!");
+    }
+}
+
+void
+tls_ctx_load_dh_params (struct tls_root_ctx *ctx, const char *dh_file,
+    const char *dh_inline
+    )
+{
+  if (!strcmp (dh_file, INLINE_FILE_TAG) && dh_inline)
+    {
+      if (!mbed_ok(mbedtls_dhm_parse_dhm(ctx->dhm_ctx,
+	  (const unsigned char *) dh_inline, strlen(dh_inline)+1)))
+	msg (M_FATAL, "Cannot read inline DH parameters");
+  }
+else
+  {
+    if (!mbed_ok(mbedtls_dhm_parse_dhmfile(ctx->dhm_ctx, dh_file)))
+      msg (M_FATAL, "Cannot read DH parameters from file %s", dh_file);
+  }
+
+  msg (D_TLS_DEBUG_LOW, "Diffie-Hellman initialized with " counter_format " bit key",
+      (counter_type) 8 * mbedtls_mpi_size(&ctx->dhm_ctx->P));
+}
+
+void
+tls_ctx_load_ecdh_params (struct tls_root_ctx *ctx, const char *curve_name
+    )
+{
+    if (NULL != curve_name)
+      msg(M_WARN, "WARNING: mbed TLS builds do not support specifying an ECDH "
+                  "curve, using default curves.");
+}
+
+int
+tls_ctx_load_pkcs12(struct tls_root_ctx *ctx, const char *pkcs12_file,
+    const char *pkcs12_file_inline,
+    bool load_ca_file
+    )
+{
+  msg(M_FATAL, "PKCS #12 files not yet supported for mbed TLS.");
+  return 0;
+}
+
+#ifdef ENABLE_CRYPTOAPI
+void
+tls_ctx_load_cryptoapi(struct tls_root_ctx *ctx, const char *cryptoapi_cert)
+{
+  msg(M_FATAL, "Windows CryptoAPI not yet supported for mbed TLS.");
+}
+#endif /* _WIN32 */
+
+void
+tls_ctx_load_cert_file (struct tls_root_ctx *ctx, const char *cert_file,
+    const char *cert_inline
+    )
+{
+  ASSERT(NULL != ctx);
+
+  if (!ctx->crt_chain)
+    {
+      ALLOC_OBJ_CLEAR(ctx->crt_chain, mbedtls_x509_crt);
+    }
+
+  if (!strcmp (cert_file, INLINE_FILE_TAG) && cert_inline)
+    {
+      if (!mbed_ok(mbedtls_x509_crt_parse(ctx->crt_chain,
+	  (const unsigned char *) cert_inline, strlen(cert_inline)+1)))
+        msg (M_FATAL, "Cannot load inline certificate file");
+    }
+  else
+    {
+      if (!mbed_ok(mbedtls_x509_crt_parse_file(ctx->crt_chain, cert_file)))
+	{
+	  msg (M_FATAL, "Cannot load certificate file %s", cert_file);
+	}
+    }
+}
+
+int
+tls_ctx_load_priv_file (struct tls_root_ctx *ctx, const char *priv_key_file,
+    const char *priv_key_inline
+    )
+{
+  int status;
+  ASSERT(NULL != ctx);
+
+  if (!ctx->priv_key)
+    {
+      ALLOC_OBJ_CLEAR(ctx->priv_key, mbedtls_pk_context);
+    }
+
+  if (!strcmp (priv_key_file, INLINE_FILE_TAG) && priv_key_inline)
+    {
+      status = mbedtls_pk_parse_key(ctx->priv_key,
+	  (const unsigned char *) priv_key_inline, strlen(priv_key_inline)+1,
+	  NULL, 0);
+
+      if (MBEDTLS_ERR_PK_PASSWORD_REQUIRED == status)
+	{
+	  char passbuf[512] = {0};
+	  pem_password_callback(passbuf, 512, 0, NULL);
+	  status = mbedtls_pk_parse_key(ctx->priv_key,
+	      (const unsigned char *) priv_key_inline,
+	      strlen(priv_key_inline)+1, (unsigned char *) passbuf,
+	      strlen(passbuf));
+	}
+    }
+  else
+    {
+      status = mbedtls_pk_parse_keyfile(ctx->priv_key, priv_key_file, NULL);
+      if (MBEDTLS_ERR_PK_PASSWORD_REQUIRED == status)
+	{
+	  char passbuf[512] = {0};
+	  pem_password_callback(passbuf, 512, 0, NULL);
+	  status = mbedtls_pk_parse_keyfile(ctx->priv_key, priv_key_file, passbuf);
+	}
+    }
+  if (!mbed_ok(status))
+    {
+#ifdef ENABLE_MANAGEMENT
+      if (management && (MBEDTLS_ERR_PK_PASSWORD_MISMATCH == status))
+	  management_auth_failure (management, UP_TYPE_PRIVATE_KEY, NULL);
+#endif
+      msg (M_WARN, "Cannot load private key file %s", priv_key_file);
+      return 1;
+    }
+
+  if (!mbed_ok(mbedtls_pk_check_pair(&ctx->crt_chain->pk, ctx->priv_key)))
+    {
+      msg (M_WARN, "Private key does not match the certificate");
+      return 1;
+    }
+
+  return 0;
+}
+
+#ifdef MANAGMENT_EXTERNAL_KEY
+
+
+struct external_context {
+  size_t signature_length;
+};
+
+/**
+ * external_pkcs1_sign implements a mbed TLS rsa_sign_func callback, that uses
+ * the management interface to request an RSA signature for the supplied hash.
+ *
+ * @param ctx_voidptr   Management external key context.
+ * @param f_rng         (Unused)
+ * @param p_rng         (Unused)
+ * @param mode          RSA mode (should be RSA_PRIVATE).
+ * @param md_alg        Message digest ('hash') algorithm type.
+ * @param hashlen       Length of hash (overridden by length specified by md_alg
+ *                      if md_alg != MBEDTLS_MD_NONE).
+ * @param hash          The digest ('hash') to sign. Should have a size
+ *                      matching the length of md_alg (if != MBEDTLS_MD_NONE),
+ *                      or hashlen otherwise.
+ * @param sig           Buffer that returns the signature. Should be at least of
+ *                      size ctx->signature_length.
+ *
+ * @return 0 on success, non-zero mbed TLS error code on failure.
+ */
+static inline int external_pkcs1_sign( void *ctx_voidptr,
+    int (*f_rng)(void *, unsigned char *, size_t), void *p_rng, int mode,
+    mbedtls_md_type_t md_alg, unsigned int hashlen, const unsigned char *hash,
+    unsigned char *sig )
+{
+  struct external_context * const ctx = ctx_voidptr;
+  char *in_b64 = NULL;
+  char *out_b64 = NULL;
+  int rv;
+  unsigned char *p = sig;
+  size_t asn_len = 0, oid_size = 0, sig_len = 0;
+  const char *oid = NULL;
+
+  if( NULL == ctx )
+    return MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
+
+  if( MBEDTLS_RSA_PRIVATE != mode )
+    return MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
+
+  /*
+   * Support a wide range of hashes. TLSv1.1 and before only need SIG_RSA_RAW,
+   * but TLSv1.2 needs the full suite of hashes.
+   *
+   * This code has been taken from mbed TLS pkcs11_sign(), under the GPLv2.0+.
+   */
+  if( md_alg != MBEDTLS_MD_NONE )
+    {
+      const mbedtls_md_info_t *md_info = mbedtls_md_info_from_type( md_alg );
+      if( md_info == NULL )
+        return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
+
+      if (!mbed_ok(mbedtls_oid_get_oid_by_md( md_alg, &oid, &oid_size )))
+        return( MBEDTLS_ERR_RSA_BAD_INPUT_DATA );
+
+      hashlen = mbedtls_md_get_size( md_info );
+      asn_len = 10 + oid_size;
+    }
+
+  sig_len = ctx->signature_length;
+  if ( (SIZE_MAX - hashlen) < asn_len || (hashlen + asn_len) > sig_len )
+    return MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
+
+  if( md_alg != MBEDTLS_MD_NONE )
+    {
+      /*
+       * DigestInfo ::= SEQUENCE {
+       *   digestAlgorithm DigestAlgorithmIdentifier,
+       *   digest Digest }
+       *
+       * DigestAlgorithmIdentifier ::= AlgorithmIdentifier
+       *
+       * Digest ::= OCTET STRING
+       */
+      *p++ = MBEDTLS_ASN1_SEQUENCE | MBEDTLS_ASN1_CONSTRUCTED;
+      *p++ = (unsigned char) ( 0x08 + oid_size + hashlen );
+      *p++ = MBEDTLS_ASN1_SEQUENCE | MBEDTLS_ASN1_CONSTRUCTED;
+      *p++ = (unsigned char) ( 0x04 + oid_size );
+      *p++ = MBEDTLS_ASN1_OID;
+      *p++ = oid_size & 0xFF;
+      memcpy( p, oid, oid_size );
+      p += oid_size;
+      *p++ = MBEDTLS_ASN1_NULL;
+      *p++ = 0x00;
+      *p++ = MBEDTLS_ASN1_OCTET_STRING;
+      *p++ = hashlen;
+
+      /* Determine added ASN length */
+      asn_len = p - sig;
+  }
+
+  /* Copy the hash to be signed */
+  memcpy( p, hash, hashlen );
+
+  /* convert 'from' to base64 */
+  if (openvpn_base64_encode (sig, asn_len + hashlen, &in_b64) <= 0)
+    {
+      rv = MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
+      goto done;
+    }
+
+  /* call MI for signature */
+  if (management)
+    out_b64 = management_query_rsa_sig (management, in_b64);
+  if (!out_b64)
+    {
+      rv = MBEDTLS_ERR_RSA_PRIVATE_FAILED;
+      goto done;
+    }
+
+  /* decode base64 signature to binary and verify length */
+  if ( openvpn_base64_decode (out_b64, sig, ctx->signature_length) !=
+       ctx->signature_length )
+    {
+      rv = MBEDTLS_ERR_RSA_PRIVATE_FAILED;
+      goto done;
+    }
+
+  rv = 0;
+
+done:
+  if (in_b64)
+    free (in_b64);
+  if (out_b64)
+    free (out_b64);
+  return rv;
+}
+
+static inline size_t external_key_len(void *vctx)
+{
+  struct external_context * const ctx = vctx;
+
+  return ctx->signature_length;
+}
+
+int
+tls_ctx_use_external_private_key (struct tls_root_ctx *ctx,
+    const char *cert_file, const char *cert_file_inline)
+{
+  ASSERT(NULL != ctx);
+
+  tls_ctx_load_cert_file(ctx, cert_file, cert_file_inline);
+
+  if (ctx->crt_chain == NULL)
+    return 0;
+
+  ALLOC_OBJ_CLEAR (ctx->external_key, struct external_context);
+  ctx->external_key->signature_length = mbedtls_pk_get_len (&ctx->crt_chain->pk);
+
+  ALLOC_OBJ_CLEAR (ctx->priv_key, mbedtls_pk_context);
+  if (!mbed_ok (mbedtls_pk_setup_rsa_alt (ctx->priv_key, ctx->external_key,
+	    NULL, external_pkcs1_sign, external_key_len)))
+    return 0;
+
+  return 1;
+}
+#endif
+
+void tls_ctx_load_ca (struct tls_root_ctx *ctx, const char *ca_file,
+    const char *ca_inline, const char *ca_path, bool tls_server
+    )
+{
+  if (ca_path)
+      msg(M_FATAL, "ERROR: mbed TLS cannot handle the capath directive");
+
+  if (ca_file && !strcmp (ca_file, INLINE_FILE_TAG) && ca_inline)
+    {
+      if (!mbed_ok (mbedtls_x509_crt_parse (ctx->ca_chain,
+	  (const unsigned char *) ca_inline, strlen(ca_inline)+1)))
+	msg (M_FATAL, "Cannot load inline CA certificates");
+    }
+  else
+    {
+      /* Load CA file for verifying peer supplied certificate */
+      if (!mbed_ok (mbedtls_x509_crt_parse_file (ctx->ca_chain, ca_file)))
+	msg (M_FATAL, "Cannot load CA certificate file %s", ca_file);
+    }
+}
+
+void
+tls_ctx_load_extra_certs (struct tls_root_ctx *ctx, const char *extra_certs_file,
+    const char *extra_certs_inline
+    )
+{
+  ASSERT(NULL != ctx);
+
+  if (!ctx->crt_chain)
+    {
+      ALLOC_OBJ_CLEAR (ctx->crt_chain, mbedtls_x509_crt);
+    }
+
+  if (!strcmp (extra_certs_file, INLINE_FILE_TAG) && extra_certs_inline)
+    {
+      if (!mbed_ok(mbedtls_x509_crt_parse(ctx->crt_chain,
+          (const unsigned char *) extra_certs_inline,
+	  strlen(extra_certs_inline)+1)))
+        msg (M_FATAL, "Cannot load inline extra-certs file");
+    }
+  else
+    {
+      if (!mbed_ok(mbedtls_x509_crt_parse_file(ctx->crt_chain, extra_certs_file)))
+	msg (M_FATAL, "Cannot load extra-certs file: %s", extra_certs_file);
+    }
+}
+
+/* **************************************
+ *
+ * Key-state specific functions
+ *
+ ***************************************/
+
+/*
+ * "Endless buffer"
+ */
+
+static inline void buf_free_entry(buffer_entry *entry)
+{
+  if (NULL != entry)
+    {
+      free(entry->data);
+      free(entry);
+    }
+}
+
+static void buf_free_entries(endless_buffer *buf)
+{
+  while(buf->first_block)
+    {
+      buffer_entry *cur_block = buf->first_block;
+      buf->first_block = cur_block->next_block;
+      buf_free_entry(cur_block);
+    }
+  buf->last_block = NULL;
+}
+
+static int endless_buf_read( endless_buffer *in, unsigned char * out, size_t out_len )
+{
+  size_t read_len = 0;
+
+  if (in->first_block == NULL)
+    return MBEDTLS_ERR_SSL_WANT_READ;
+
+  while (in->first_block != NULL && read_len < out_len)
+    {
+      int block_len = in->first_block->length - in->data_start;
+      if (block_len <= out_len - read_len)
+	{
+	  buffer_entry *cur_entry = in->first_block;
+	  memcpy(out + read_len, cur_entry->data + in->data_start,
+	      block_len);
+
+	  read_len += block_len;
+
+	  in->first_block = cur_entry->next_block;
+	  in->data_start = 0;
+
+	  if (in->first_block == NULL)
+	    in->last_block = NULL;
+
+	  buf_free_entry(cur_entry);
+	}
+      else
+	{
+	  memcpy(out + read_len, in->first_block->data + in->data_start,
+	      out_len - read_len);
+	  in->data_start += out_len - read_len;
+	  read_len = out_len;
+	}
+    }
+
+  return read_len;
+}
+
+static int endless_buf_write( endless_buffer *out, const unsigned char *in, size_t len )
+{
+  buffer_entry *new_block = malloc(sizeof(buffer_entry));
+  if (NULL == new_block)
+    return MBEDTLS_ERR_NET_SEND_FAILED;
+
+  new_block->data = malloc(len);
+  if (NULL == new_block->data)
+    {
+      free(new_block);
+      return MBEDTLS_ERR_NET_SEND_FAILED;
+    }
+
+  new_block->length = len;
+  new_block->next_block = NULL;
+
+  memcpy(new_block->data, in, len);
+
+  if (NULL == out->first_block)
+    out->first_block = new_block;
+
+  if (NULL != out->last_block)
+    out->last_block->next_block = new_block;
+
+  out->last_block = new_block;
+
+  return len;
+}
+
+static int ssl_bio_read( void *ctx, unsigned char *out, size_t out_len)
+{
+  bio_ctx *my_ctx = (bio_ctx *) ctx;
+  return endless_buf_read (&my_ctx->in, out, out_len);
+}
+
+static int ssl_bio_write( void *ctx, const unsigned char *in, size_t in_len)
+{
+  bio_ctx *my_ctx = (bio_ctx *) ctx;
+  return endless_buf_write (&my_ctx->out, in, in_len);
+}
+
+static void my_debug( void *ctx, int level, const char *file, int line,
+    const char *str )
+{
+  int my_loglevel = (level < 3) ? D_TLS_DEBUG_MED : D_TLS_DEBUG;
+  msg (my_loglevel, "mbed TLS msg (%s:%d): %s", file, line, str);
+}
+
+/*
+ * Further personalise the RNG using a hash of the public key
+ */
+void tls_ctx_personalise_random(struct tls_root_ctx *ctx)
+{
+  static char old_sha256_hash[32] = {0};
+  unsigned char sha256_hash[32] = {0};
+  mbedtls_ctr_drbg_context *cd_ctx = rand_ctx_get();
+
+  if (NULL != ctx->crt_chain)
+    {
+      mbedtls_x509_crt *cert = ctx->crt_chain;
+
+      mbedtls_sha256(cert->tbs.p, cert->tbs.len, sha256_hash, false);
+      if ( 0 != memcmp(old_sha256_hash, sha256_hash, sizeof(sha256_hash)))
+	{
+	  mbedtls_ctr_drbg_update(cd_ctx, sha256_hash, 32);
+	  memcpy(old_sha256_hash, sha256_hash, sizeof(old_sha256_hash));
+	}
+    }
+}
+
+int
+tls_version_max(void)
+{
+#if defined(MBEDTLS_SSL_MAJOR_VERSION_3) && defined(MBEDTLS_SSL_MINOR_VERSION_3)
+  return TLS_VER_1_2;
+#elif defined(MBEDTLS_SSL_MAJOR_VERSION_3) && defined(MBEDTLS_SSL_MINOR_VERSION_2)
+  return TLS_VER_1_1;
+#else
+  return TLS_VER_1_0;
+#endif
+}
+
+/**
+ * Convert an OpenVPN tls-version variable to mbed TLS format (i.e. a major and
+ * minor ssl version number).
+ *
+ * @param tls_ver	The tls-version variable to convert.
+ * @param major		Returns the TLS major version in mbed TLS format.
+ * 			Must be a valid pointer.
+ * @param minor		Returns the TLS minor version in mbed TLS format.
+ * 			Must be a valid pointer.
+ */
+static void tls_version_to_major_minor(int tls_ver, int *major, int *minor) {
+  ASSERT(major);
+  ASSERT(minor);
+
+  switch (tls_ver)
+  {
+    case TLS_VER_1_0:
+      *major = MBEDTLS_SSL_MAJOR_VERSION_3;
+      *minor = MBEDTLS_SSL_MINOR_VERSION_1;
+      break;
+    case TLS_VER_1_1:
+      *major = MBEDTLS_SSL_MAJOR_VERSION_3;
+      *minor = MBEDTLS_SSL_MINOR_VERSION_2;
+      break;
+    case TLS_VER_1_2:
+      *major = MBEDTLS_SSL_MAJOR_VERSION_3;
+      *minor = MBEDTLS_SSL_MINOR_VERSION_3;
+      break;
+    default:
+      msg(M_FATAL, "%s: invalid TLS version %d", __func__, tls_ver);
+      break;
+  }
+}
+
+void
+tls_ctx_reload_crl(struct tls_root_ctx *ctx, const char *crl_file,
+    const char *crl_inline)
+{
+  ASSERT (crl_file);
+
+  if (ctx->crl == NULL)
+    {
+      ALLOC_OBJ_CLEAR(ctx->crl, mbedtls_x509_crl);
+    }
+  mbedtls_x509_crl_free(ctx->crl);
+
+  if (!strcmp (crl_file, INLINE_FILE_TAG) && crl_inline)
+    {
+      if (!mbed_ok(mbedtls_x509_crl_parse(ctx->crl,
+	(const unsigned char *)crl_inline, strlen(crl_inline)+1)))
+	{
+	  msg (M_WARN, "CRL: cannot parse inline CRL");
+	  goto err;
+	}
+    }
+  else
+    {
+      if (!mbed_ok(mbedtls_x509_crl_parse_file(ctx->crl, crl_file)))
+	{
+	  msg (M_WARN, "CRL: cannot read CRL from file %s", crl_file);
+	  goto err;
+	}
+    }
+  return;
+
+err:
+  mbedtls_x509_crl_free(ctx->crl);
+}
+
+void key_state_ssl_init(struct key_state_ssl *ks_ssl,
+    const struct tls_root_ctx *ssl_ctx, bool is_server, struct tls_session *session)
+{
+  ASSERT(NULL != ssl_ctx);
+  ASSERT(ks_ssl);
+  CLEAR(*ks_ssl);
+
+  /* Initialise SSL config */
+  mbedtls_ssl_config_init(&ks_ssl->ssl_config);
+  mbedtls_ssl_config_defaults(&ks_ssl->ssl_config, ssl_ctx->endpoint,
+      MBEDTLS_SSL_TRANSPORT_STREAM, MBEDTLS_SSL_PRESET_DEFAULT);
+#ifdef MBEDTLS_DEBUG_C
+  mbedtls_debug_set_threshold(3);
+#endif
+  mbedtls_ssl_conf_dbg (&ks_ssl->ssl_config, my_debug, NULL);
+  mbedtls_ssl_conf_rng (&ks_ssl->ssl_config, mbedtls_ctr_drbg_random,
+      rand_ctx_get());
+
+  if (ssl_ctx->allowed_ciphers)
+    mbedtls_ssl_conf_ciphersuites (&ks_ssl->ssl_config, ssl_ctx->allowed_ciphers);
+
+  /* Disable record splitting (for now).  OpenVPN assumes records are sent
+   * unfragmented, and changing that will require thorough review and
+   * testing.  Since OpenVPN is not susceptible to BEAST, we can just
+   * disable record splitting as a quick fix. */
+#if defined(MBEDTLS_SSL_CBC_RECORD_SPLITTING)
+  mbedtls_ssl_conf_cbc_record_splitting (&ks_ssl->ssl_config,
+      MBEDTLS_SSL_CBC_RECORD_SPLITTING_DISABLED);
+#endif /* MBEDTLS_SSL_CBC_RECORD_SPLITTING */
+
+  /* Initialise authentication information */
+  if (is_server)
+    mbed_ok (mbedtls_ssl_conf_dh_param_ctx(&ks_ssl->ssl_config,
+	ssl_ctx->dhm_ctx));
+
+  mbed_ok (mbedtls_ssl_conf_own_cert(&ks_ssl->ssl_config, ssl_ctx->crt_chain,
+      ssl_ctx->priv_key));
+
+  /* Initialise SSL verification */
+#if P2MP_SERVER
+  if (session->opt->ssl_flags & SSLF_CLIENT_CERT_OPTIONAL)
+    {
+      mbedtls_ssl_conf_authmode(&ks_ssl->ssl_config, MBEDTLS_SSL_VERIFY_OPTIONAL);
+    }
+  else if (!(session->opt->ssl_flags & SSLF_CLIENT_CERT_NOT_REQUIRED))
+#endif
+  {
+    mbedtls_ssl_conf_authmode (&ks_ssl->ssl_config, MBEDTLS_SSL_VERIFY_REQUIRED);
+  }
+  mbedtls_ssl_conf_verify (&ks_ssl->ssl_config, verify_callback, session);
+
+  /* TODO: mbed TLS does not currently support sending the CA chain to the client */
+  mbedtls_ssl_conf_ca_chain (&ks_ssl->ssl_config, ssl_ctx->ca_chain, ssl_ctx->crl);
+
+  /* Initialize minimum TLS version */
+  {
+    const int tls_version_min =
+	(session->opt->ssl_flags >> SSLF_TLS_VERSION_MIN_SHIFT) &
+	SSLF_TLS_VERSION_MIN_MASK;
+
+    /* default to TLS 1.0 */
+    int major = MBEDTLS_SSL_MAJOR_VERSION_3;
+    int minor = MBEDTLS_SSL_MINOR_VERSION_1;
+
+    if (tls_version_min > TLS_VER_UNSPEC)
+      tls_version_to_major_minor(tls_version_min, &major, &minor);
+
+    mbedtls_ssl_conf_min_version(&ks_ssl->ssl_config, major, minor);
+  }
+
+  /* Initialize maximum TLS version */
+  {
+    const int tls_version_max =
+	(session->opt->ssl_flags >> SSLF_TLS_VERSION_MAX_SHIFT) &
+	SSLF_TLS_VERSION_MAX_MASK;
+
+    if (tls_version_max > TLS_VER_UNSPEC)
+      {
+	int major, minor;
+	tls_version_to_major_minor(tls_version_max, &major, &minor);
+	mbedtls_ssl_conf_max_version(&ks_ssl->ssl_config, major, minor);
+      }
+  }
+
+  /* Initialise SSL context */
+  ALLOC_OBJ_CLEAR(ks_ssl->ctx, mbedtls_ssl_context);
+  mbedtls_ssl_init(ks_ssl->ctx);
+  mbedtls_ssl_setup(ks_ssl->ctx, &ks_ssl->ssl_config);
+
+  /* Initialise BIOs */
+  CLEAR (ks_ssl->bio_ctx);
+  mbedtls_ssl_set_bio (ks_ssl->ctx, &ks_ssl->bio_ctx, ssl_bio_write,
+      ssl_bio_read, NULL);
+}
+
+void
+key_state_ssl_free(struct key_state_ssl *ks_ssl)
+{
+  if (ks_ssl) {
+      if (ks_ssl->ctx)
+	{
+	  mbedtls_ssl_free(ks_ssl->ctx);
+	  free(ks_ssl->ctx);
+	}
+      mbedtls_ssl_config_free(&ks_ssl->ssl_config);
+      buf_free_entries(&ks_ssl->bio_ctx.in);
+      buf_free_entries(&ks_ssl->bio_ctx.out);
+      CLEAR(*ks_ssl);
+  }
+}
+
+int
+key_state_write_plaintext (struct key_state_ssl *ks, struct buffer *buf)
+{
+  int retval = 0;
+
+  ASSERT (buf);
+
+  retval = key_state_write_plaintext_const(ks, BPTR(buf), BLEN(buf));
+
+  if (1 == retval)
+    {
+      memset (BPTR (buf), 0, BLEN (buf)); /* erase data just written */
+      buf->len = 0;
+    }
+
+  return retval;
+}
+
+int
+key_state_write_plaintext_const (struct key_state_ssl *ks, const uint8_t *data, int len)
+{
+  int retval = 0;
+  perf_push (PERF_BIO_WRITE_PLAINTEXT);
+
+  ASSERT (NULL != ks);
+  ASSERT (len >= 0);
+
+  if (0 == len)
+    {
+      perf_pop ();
+      return 0;
+    }
+
+  ASSERT (data);
+
+  retval = mbedtls_ssl_write(ks->ctx, data, len);
+
+  if (retval < 0)
+    {
+      perf_pop ();
+      if (MBEDTLS_ERR_SSL_WANT_WRITE == retval || MBEDTLS_ERR_SSL_WANT_READ == retval)
+	return 0;
+      mbed_log_err (D_TLS_ERRORS, retval,
+	  "TLS ERROR: write tls_write_plaintext_const error");
+      return -1;
+    }
+
+  if (retval != len)
+    {
+      msg (D_TLS_ERRORS,
+	  "TLS ERROR: write tls_write_plaintext_const incomplete %d/%d",
+	  retval, len);
+      perf_pop ();
+      return -1;
+    }
+
+  /* successful write */
+  dmsg (D_HANDSHAKE_VERBOSE, "write tls_write_plaintext_const %d bytes", retval);
+
+  perf_pop ();
+  return 1;
+}
+
+int
+key_state_read_ciphertext (struct key_state_ssl *ks, struct buffer *buf,
+    int maxlen)
+{
+  int retval = 0;
+  int len = 0;
+
+  perf_push (PERF_BIO_READ_CIPHERTEXT);
+
+  ASSERT (NULL != ks);
+  ASSERT (buf);
+  ASSERT (buf->len >= 0);
+
+  if (buf->len)
+    {
+      perf_pop ();
+      return 0;
+    }
+
+  len = buf_forward_capacity (buf);
+  if (maxlen < len)
+    len = maxlen;
+
+  retval = endless_buf_read(&ks->bio_ctx.out, BPTR(buf), len);
+
+  /* Error during read, check for retry error */
+  if (retval < 0)
+    {
+      perf_pop ();
+      if (MBEDTLS_ERR_SSL_WANT_WRITE == retval || MBEDTLS_ERR_SSL_WANT_READ == retval)
+	return 0;
+      mbed_log_err (D_TLS_ERRORS, retval, "TLS_ERROR: read tls_read_ciphertext error");
+      buf->len = 0;
+      return -1;
+    }
+  /* Nothing read, try again */
+  if (0 == retval)
+    {
+      buf->len = 0;
+      perf_pop ();
+      return 0;
+    }
+
+  /* successful read */
+  dmsg (D_HANDSHAKE_VERBOSE, "read tls_read_ciphertext %d bytes", retval);
+  buf->len = retval;
+  perf_pop ();
+  return 1;
+}
+
+int
+key_state_write_ciphertext (struct key_state_ssl *ks, struct buffer *buf)
+{
+  int retval = 0;
+  perf_push (PERF_BIO_WRITE_CIPHERTEXT);
+
+  ASSERT (NULL != ks);
+  ASSERT (buf);
+  ASSERT (buf->len >= 0);
+
+  if (0 == buf->len)
+    {
+      perf_pop ();
+      return 0;
+    }
+
+  retval = endless_buf_write(&ks->bio_ctx.in, BPTR(buf), buf->len);
+
+  if (retval < 0)
+    {
+      perf_pop ();
+
+      if (MBEDTLS_ERR_SSL_WANT_WRITE == retval || MBEDTLS_ERR_SSL_WANT_READ == retval)
+	return 0;
+      mbed_log_err (D_TLS_ERRORS, retval,
+	  "TLS ERROR: write tls_write_ciphertext error");
+      return -1;
+    }
+
+  if (retval != buf->len)
+    {
+      msg (D_TLS_ERRORS, "TLS ERROR: write tls_write_ciphertext incomplete %d/%d",
+	  retval, buf->len);
+      perf_pop ();
+      return -1;
+    }
+
+  /* successful write */
+  dmsg (D_HANDSHAKE_VERBOSE, "write tls_write_ciphertext %d bytes", retval);
+
+  memset (BPTR (buf), 0, BLEN (buf)); /* erase data just written */
+  buf->len = 0;
+
+  perf_pop ();
+  return 1;
+}
+
+int
+key_state_read_plaintext (struct key_state_ssl *ks, struct buffer *buf,
+    int maxlen)
+{
+  int retval = 0;
+  int len = 0;
+
+  perf_push (PERF_BIO_READ_PLAINTEXT);
+
+  ASSERT (NULL != ks);
+  ASSERT (buf);
+  ASSERT (buf->len >= 0);
+
+  if (buf->len)
+    {
+      perf_pop ();
+      return 0;
+    }
+
+  len = buf_forward_capacity (buf);
+  if (maxlen < len)
+    len = maxlen;
+
+  retval = mbedtls_ssl_read(ks->ctx, BPTR(buf), len);
+
+  /* Error during read, check for retry error */
+  if (retval < 0)
+    {
+      if (MBEDTLS_ERR_SSL_WANT_WRITE == retval || MBEDTLS_ERR_SSL_WANT_READ == retval)
+	return 0;
+      mbed_log_err (D_TLS_ERRORS, retval, "TLS_ERROR: read tls_read_plaintext error");
+      buf->len = 0;
+      perf_pop ();
+      return -1;
+    }
+  /* Nothing read, try again */
+  if (0 == retval)
+    {
+      buf->len = 0;
+      perf_pop ();
+      return 0;
+    }
+
+  /* successful read */
+  dmsg (D_HANDSHAKE_VERBOSE, "read tls_read_plaintext %d bytes", retval);
+  buf->len = retval;
+
+  perf_pop ();
+  return 1;
+}
+
+/* **************************************
+ *
+ * Information functions
+ *
+ * Print information for the end user.
+ *
+ ***************************************/
+void
+print_details (struct key_state_ssl * ks_ssl, const char *prefix)
+{
+  const mbedtls_x509_crt *cert;
+  char s1[256];
+  char s2[256];
+
+  s1[0] = s2[0] = 0;
+  openvpn_snprintf (s1, sizeof (s1), "%s %s, cipher %s",
+		    prefix,
+		    mbedtls_ssl_get_version (ks_ssl->ctx),
+		    mbedtls_ssl_get_ciphersuite (ks_ssl->ctx));
+
+  cert = mbedtls_ssl_get_peer_cert (ks_ssl->ctx);
+  if (cert != NULL)
+    {
+      openvpn_snprintf (s2, sizeof (s2), ", %u bit key",
+	  (unsigned int) mbedtls_pk_get_bitlen (&cert->pk));
+    }
+
+  msg (D_HANDSHAKE, "%s%s", s1, s2);
+}
+
+void
+show_available_tls_ciphers (const char *cipher_list)
+{
+  struct tls_root_ctx tls_ctx;
+  const int *ciphers = mbedtls_ssl_list_ciphersuites ();
+
+  tls_ctx_server_new(&tls_ctx);
+  tls_ctx_restrict_ciphers(&tls_ctx, cipher_list);
+
+  if (tls_ctx.allowed_ciphers)
+    ciphers = tls_ctx.allowed_ciphers;
+
+#ifndef ENABLE_SMALL
+  printf ("Available TLS Ciphers,\n");
+  printf ("listed in order of preference:\n\n");
+#endif
+
+  while (*ciphers != 0)
+    {
+      printf ("%s\n", mbedtls_ssl_get_ciphersuite_name (*ciphers));
+      ciphers++;
+    }
+  printf ("\n" SHOW_TLS_CIPHER_LIST_WARNING);
+
+  tls_ctx_free(&tls_ctx);
+}
+
+void
+show_available_curves (void)
+{
+  const mbedtls_ecp_curve_info *pcurve = mbedtls_ecp_curve_list ();
+
+  if (NULL == pcurve)
+    msg (M_FATAL, "Cannot retrieve curve list from mbed TLS");
+
+  /* Print curve list */
+  printf ("Available Elliptic curves, listed in order of preference:\n\n");
+  while (MBEDTLS_ECP_DP_NONE != pcurve->grp_id)
+    {
+      printf("%s\n", pcurve->name);
+      pcurve++;
+    }
+}
+
+void
+get_highest_preference_tls_cipher (char *buf, int size)
+{
+  const char *cipher_name;
+  const int *ciphers = mbedtls_ssl_list_ciphersuites();
+  if (*ciphers == 0)
+    msg (M_FATAL, "Cannot retrieve list of supported SSL ciphers.");
+
+  cipher_name = mbedtls_ssl_get_ciphersuite_name(*ciphers);
+  strncpynt (buf, cipher_name, size);
+}
+
+const char *
+get_ssl_library_version(void)
+{
+    static char mbedtls_version[30];
+    unsigned int pv = mbedtls_version_get_number();
+    sprintf( mbedtls_version, "mbed TLS %d.%d.%d",
+		(pv>>24)&0xff, (pv>>16)&0xff, (pv>>8)&0xff );
+    return mbedtls_version;
+}
+
+#endif /* defined(ENABLE_CRYPTO) && defined(ENABLE_CRYPTO_MBEDTLS) */