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third-party-mirror / openvpn / 92ce3321a75769a6656fae341f9b86ad033e9f2d / . / src / openvpn / ssl_mbedtls.c
blob: 0fe70e45aa6f3b1389753e2a220cad607e606944 [file] [log] [blame]
/*
* 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) 2002-2021 OpenVPN Inc <sales@openvpn.net>
* Copyright (C) 2010-2021 Fox Crypto B.V. <openvpn@foxcrypto.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; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 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_MBEDTLS)
#include "errlevel.h"
#include "ssl_backend.h"
#include "base64.h"
#include "buffer.h"
#include "misc.h"
#include "manage.h"
#include "pkcs11_backend.h"
#include "ssl_common.h"
#include <mbedtls/havege.h>
#include "ssl_verify_mbedtls.h"
#include <mbedtls/debug.h>
#include <mbedtls/error.h>
#include <mbedtls/version.h>
#if MBEDTLS_VERSION_NUMBER >= 0x02040000
#include <mbedtls/net_sockets.h>
#else
#include <mbedtls/net.h>
#endif
#include <mbedtls/oid.h>
#include <mbedtls/pem.h>
static const mbedtls_x509_crt_profile openvpn_x509_crt_profile_legacy =
{
/* Hashes from SHA-1 and above */
MBEDTLS_X509_ID_FLAG( MBEDTLS_MD_SHA1 )
|MBEDTLS_X509_ID_FLAG( MBEDTLS_MD_RIPEMD160 )
|MBEDTLS_X509_ID_FLAG( MBEDTLS_MD_SHA224 )
|MBEDTLS_X509_ID_FLAG( MBEDTLS_MD_SHA256 )
|MBEDTLS_X509_ID_FLAG( MBEDTLS_MD_SHA384 )
|MBEDTLS_X509_ID_FLAG( MBEDTLS_MD_SHA512 ),
0xFFFFFFF, /* Any PK alg */
0xFFFFFFF, /* Any curve */
1024, /* RSA-1024 and larger */
};
static const mbedtls_x509_crt_profile openvpn_x509_crt_profile_preferred =
{
/* SHA-2 and above */
MBEDTLS_X509_ID_FLAG( MBEDTLS_MD_SHA224 )
|MBEDTLS_X509_ID_FLAG( MBEDTLS_MD_SHA256 )
|MBEDTLS_X509_ID_FLAG( MBEDTLS_MD_SHA384 )
|MBEDTLS_X509_ID_FLAG( MBEDTLS_MD_SHA512 ),
0xFFFFFFF, /* Any PK alg */
0xFFFFFFF, /* Any curve */
2048, /* RSA-2048 and larger */
};
#define openvpn_x509_crt_profile_suiteb mbedtls_x509_crt_profile_suiteb;
void
tls_init_lib(void)
{
}
void
tls_free_lib(void)
{
}
void
tls_clear_error(void)
{
}
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)
pkcs11h_certificate_freeCertificate(ctx->pkcs11_cert);
#endif
if (ctx->allowed_ciphers)
{
free(ctx->allowed_ciphers);
}
if (ctx->groups)
{
free(ctx->groups);
}
CLEAR(*ctx);
ctx->initialised = false;
}
}
bool
tls_ctx_initialised(struct tls_root_ctx *ctx)
{
ASSERT(NULL != ctx);
return ctx->initialised;
}
#ifdef HAVE_EXPORT_KEYING_MATERIAL
int
mbedtls_ssl_export_keys_cb(void *p_expkey, const unsigned char *ms,
const unsigned char *kb, size_t maclen,
size_t keylen, size_t ivlen,
const unsigned char client_random[32],
const unsigned char server_random[32],
mbedtls_tls_prf_types tls_prf_type)
{
struct tls_session *session = p_expkey;
struct key_state_ssl *ks_ssl = &session->key[KS_PRIMARY].ks_ssl;
unsigned char client_server_random[64];
ks_ssl->exported_key_material = gc_malloc(session->opt->ekm_size,
true, NULL);
memcpy(client_server_random, client_random, 32);
memcpy(client_server_random + 32, server_random, 32);
const size_t ms_len = sizeof(ks_ssl->ctx->session->master);
int ret = mbedtls_ssl_tls_prf(tls_prf_type, ms, ms_len,
session->opt->ekm_label, client_server_random,
sizeof(client_server_random), ks_ssl->exported_key_material,
session->opt->ekm_size);
if (!mbed_ok(ret))
{
secure_memzero(ks_ssl->exported_key_material, session->opt->ekm_size);
}
secure_memzero(client_server_random, sizeof(client_server_random));
return ret;
}
#endif /* HAVE_EXPORT_KEYING_MATERIAL */
void
key_state_export_keying_material(struct key_state_ssl *ssl,
struct tls_session *session)
{
if (ssl->exported_key_material)
{
unsigned int size = session->opt->ekm_size;
struct gc_arena gc = gc_new();
unsigned int len = (size * 2) + 2;
const char *key = format_hex_ex(ssl->exported_key_material,
size, len, 0, NULL, &gc);
setenv_str(session->opt->es, "exported_keying_material", key);
dmsg(D_TLS_DEBUG_MED, "%s: exported keying material: %s",
__func__, key);
gc_free(&gc);
}
}
bool
tls_ctx_set_options(struct tls_root_ctx *ctx, unsigned int ssl_flags)
{
return true;
}
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_tls13(struct tls_root_ctx *ctx, const char *ciphers)
{
if (ciphers == NULL)
{
/* Nothing to do, return without warning message */
return;
}
msg(M_WARN, "mbed TLS does not support setting tls-ciphersuites. "
"Ignoring TLS 1.3 cipher list: %s", ciphers);
}
void
tls_ctx_restrict_ciphers(struct tls_root_ctx *ctx, const char *ciphers)
{
char *tmp_ciphers, *tmp_ciphers_orig, *token;
if (NULL == ciphers)
{
return; /* Nothing to do */
}
ASSERT(NULL != ctx);
/* Get number of ciphers */
int cipher_count = get_num_elements(ciphers, ':');
/* Allocate an array for them */
ALLOC_ARRAY_CLEAR(ctx->allowed_ciphers, int, cipher_count+1)
/* Parse allowed ciphers, getting IDs */
int 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_set_cert_profile(struct tls_root_ctx *ctx, const char *profile)
{
if (!profile || 0 == strcmp(profile, "legacy"))
{
ctx->cert_profile = openvpn_x509_crt_profile_legacy;
}
else if (0 == strcmp(profile, "preferred"))
{
ctx->cert_profile = openvpn_x509_crt_profile_preferred;
}
else if (0 == strcmp(profile, "suiteb"))
{
ctx->cert_profile = openvpn_x509_crt_profile_suiteb;
}
else
{
msg(M_FATAL, "ERROR: Invalid cert profile: %s", profile);
}
}
void
tls_ctx_set_tls_groups(struct tls_root_ctx *ctx, const char *groups)
{
ASSERT(ctx);
struct gc_arena gc = gc_new();
/* Get number of groups and allocate an array in ctx */
int groups_count = get_num_elements(groups, ':');
ALLOC_ARRAY_CLEAR(ctx->groups, mbedtls_ecp_group_id, groups_count + 1)
/* Parse allowed ciphers, getting IDs */
int i = 0;
char *tmp_groups = string_alloc(groups, &gc);
const char *token;
while ((token = strsep(&tmp_groups, ":")))
{
const mbedtls_ecp_curve_info *ci =
mbedtls_ecp_curve_info_from_name(token);
if (!ci)
{
msg(M_WARN, "Warning unknown curve/group specified: %s", token);
}
else
{
ctx->groups[i] = ci->grp_id;
i++;
}
}
ctx->groups[i] = MBEDTLS_ECP_DP_NONE;
gc_free(&gc);
}
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,
bool dh_inline)
{
if (dh_inline)
{
if (!mbed_ok(mbedtls_dhm_parse_dhm(ctx->dhm_ctx,
(const unsigned char *) dh_file,
strlen(dh_file) + 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,
bool 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,
bool cert_inline)
{
ASSERT(NULL != ctx);
if (!ctx->crt_chain)
{
ALLOC_OBJ_CLEAR(ctx->crt_chain, mbedtls_x509_crt);
}
if (cert_inline)
{
if (!mbed_ok(mbedtls_x509_crt_parse(ctx->crt_chain,
(const unsigned char *)cert_file,
strlen(cert_file) + 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,
bool priv_key_inline)
{
int status;
ASSERT(NULL != ctx);
if (!ctx->priv_key)
{
ALLOC_OBJ_CLEAR(ctx->priv_key, mbedtls_pk_context);
}
if (priv_key_inline)
{
status = mbedtls_pk_parse_key(ctx->priv_key,
(const unsigned char *) priv_key_file,
strlen(priv_key_file) + 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_file,
strlen(priv_key_file) + 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",
print_key_filename(priv_key_file, priv_key_inline));
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;
}
/**
* 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;
int rv;
uint8_t *to_sign = NULL;
size_t asn_len = 0, oid_size = 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;
}
if ((SIZE_MAX - hashlen) < asn_len
|| ctx->signature_length < (asn_len + hashlen))
{
return MBEDTLS_ERR_RSA_BAD_INPUT_DATA;
}
ALLOC_ARRAY_CLEAR(to_sign, uint8_t, asn_len + hashlen);
uint8_t *p = to_sign;
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;
/* Double-check ASN length */
ASSERT(asn_len == p - to_sign);
}
/* Copy the hash to be signed */
memcpy(p, hash, hashlen);
/* Call external signature function */
if (!ctx->sign(ctx->sign_ctx, to_sign, asn_len + hashlen, sig,
ctx->signature_length))
{
rv = MBEDTLS_ERR_RSA_PRIVATE_FAILED;
goto done;
}
rv = 0;
done:
free(to_sign);
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_signing_func(struct tls_root_ctx *ctx,
external_sign_func sign_func, void *sign_ctx)
{
ASSERT(NULL != ctx);
if (ctx->crt_chain == NULL)
{
msg(M_WARN, "ERROR: external key requires a certificate.");
return 1;
}
if (mbedtls_pk_get_type(&ctx->crt_chain->pk) != MBEDTLS_PK_RSA)
{
msg(M_WARN, "ERROR: external key with mbed TLS requires a "
"certificate with an RSA key.");
return 1;
}
ctx->external_key.signature_length = mbedtls_pk_get_len(&ctx->crt_chain->pk);
ctx->external_key.sign = sign_func;
ctx->external_key.sign_ctx = sign_ctx;
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 1;
}
return 0;
}
#ifdef ENABLE_MANAGEMENT
/** Query the management interface for a signature, see external_sign_func. */
static bool
management_sign_func(void *sign_ctx, const void *src, size_t src_len,
void *dst, size_t dst_len)
{
bool ret = false;
char *src_b64 = NULL;
char *dst_b64 = NULL;
if (!management || (openvpn_base64_encode(src, src_len, &src_b64) <= 0))
{
goto cleanup;
}
/*
* We only support RSA external keys and PKCS1 signatures at the moment
* in mbed TLS, so the signature parameter is hardcoded to this encoding
*/
if (!(dst_b64 = management_query_pk_sig(management, src_b64,
"RSA_PKCS1_PADDING")))
{
goto cleanup;
}
if (openvpn_base64_decode(dst_b64, dst, dst_len) != dst_len)
{
goto cleanup;
}
ret = true;
cleanup:
free(src_b64);
free(dst_b64);
return ret;
}
int
tls_ctx_use_management_external_key(struct tls_root_ctx *ctx)
{
return tls_ctx_use_external_signing_func(ctx, management_sign_func, NULL);
}
#endif /* ifdef ENABLE_MANAGEMENT */
void
tls_ctx_load_ca(struct tls_root_ctx *ctx, const char *ca_file,
bool 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 && ca_inline)
{
if (!mbed_ok(mbedtls_x509_crt_parse(ctx->ca_chain,
(const unsigned char *) ca_file,
strlen(ca_file) + 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,
bool extra_certs_inline)
{
ASSERT(NULL != ctx);
if (!ctx->crt_chain)
{
ALLOC_OBJ_CLEAR(ctx->crt_chain, mbedtls_x509_crt);
}
if (extra_certs_inline)
{
if (!mbed_ok(mbedtls_x509_crt_parse(ctx->crt_chain,
(const unsigned char *) extra_certs_file,
strlen(extra_certs_file) + 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)
{
const md_kt_t *sha256_kt = md_kt_get("SHA256");
mbedtls_x509_crt *cert = ctx->crt_chain;
if (!md_full(sha256_kt, cert->tbs.p, cert->tbs.len, sha256_hash))
{
msg(M_WARN, "WARNING: failed to personalise random");
}
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
backend_tls_ctx_reload_crl(struct tls_root_ctx *ctx, const char *crl_file,
bool crl_inline)
{
ASSERT(crl_file);
if (ctx->crl == NULL)
{
ALLOC_OBJ_CLEAR(ctx->crl, mbedtls_x509_crl);
}
mbedtls_x509_crl_free(ctx->crl);
if (crl_inline)
{
if (!mbed_ok(mbedtls_x509_crl_parse(ctx->crl,
(const unsigned char *)crl_file,
strlen(crl_file) + 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 */
ALLOC_OBJ_CLEAR(ks_ssl->ssl_config, mbedtls_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
/* We only want to have mbed TLS generate debug level logging when we would
* also display it.
* In fact mbed TLS 2.25.0 crashes generating debug log if Curve25591 is
* selected for DH (https://github.com/ARMmbed/mbedtls/issues/4208) */
if (session->opt->ssl_flags & SSLF_TLS_DEBUG_ENABLED)
{
mbedtls_debug_set_threshold(3);
}
else
{
mbedtls_debug_set_threshold(2);
}
#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());
mbedtls_ssl_conf_cert_profile(ks_ssl->ssl_config, &ssl_ctx->cert_profile);
if (ssl_ctx->allowed_ciphers)
{
mbedtls_ssl_conf_ciphersuites(ks_ssl->ssl_config, ssl_ctx->allowed_ciphers);
}
if (ssl_ctx->groups)
{
mbedtls_ssl_conf_curves(ks_ssl->ssl_config, ssl_ctx->groups);
}
/* Disable TLS renegotiations if the mbedtls library supports that feature.
* OpenVPN's renegotiation creates new SSL sessions and does not depend on
* this feature and TLS renegotiations have been problematic in the past. */
#if defined(MBEDTLS_SSL_RENEGOTIATION)
mbedtls_ssl_conf_renegotiation(ks_ssl->ssl_config, MBEDTLS_SSL_RENEGOTIATION_DISABLED);
#endif /* MBEDTLS_SSL_RENEGOTIATION */
/* 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 (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))
{
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);
}
}
#ifdef HAVE_EXPORT_KEYING_MATERIAL
/* Initialize keying material exporter */
if (session->opt->ekm_size)
{
mbedtls_ssl_conf_export_keys_ext_cb(ks_ssl->ssl_config,
mbedtls_ssl_export_keys_cb, session);
}
#endif
/* 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 */
ALLOC_OBJ_CLEAR(ks_ssl->bio_ctx, 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)
{
free(ks_ssl->exported_key_material);
if (ks_ssl->ctx)
{
mbedtls_ssl_free(ks_ssl->ctx);
free(ks_ssl->ctx);
}
if (ks_ssl->ssl_config)
{
mbedtls_ssl_config_free(ks_ssl->ssl_config);
free(ks_ssl->ssl_config);
}
if (ks_ssl->bio_ctx)
{
buf_free_entries(&ks_ssl->bio_ctx->in);
buf_free_entries(&ks_ssl->bio_ctx->out);
free(ks_ssl->bio_ctx);
}
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_list(const char *cipher_list,
const char *tls_cert_profile,
bool tls13)
{
if (tls13)
{
/* mbed TLS has no TLS 1.3 support currently */
return;
}
struct tls_root_ctx tls_ctx;
const int *ciphers = mbedtls_ssl_list_ciphersuites();
tls_ctx_server_new(&tls_ctx);
tls_ctx_set_cert_profile(&tls_ctx, tls_cert_profile);
tls_ctx_restrict_ciphers(&tls_ctx, cipher_list);
if (tls_ctx.allowed_ciphers)
{
ciphers = tls_ctx.allowed_ciphers;
}
while (*ciphers != 0)
{
printf("%s\n", mbedtls_ssl_get_ciphersuite_name(*ciphers));
ciphers++;
}
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_MBEDTLS) */