This prepares for reusing this code from the mbedtls pkcs11 implementation.
The change itself should not have any functional impact.
Signed-off-by: Steffan Karger <steffan.kar...@fox-it.com>
---
src/openvpn/ssl_mbedtls.c | 115 ++++++++++++++++++++++++----------------------
src/openvpn/ssl_mbedtls.h | 41 +++++++++++++++--
2 files changed, 98 insertions(+), 58 deletions(-)
diff --git a/src/openvpn/ssl_mbedtls.c b/src/openvpn/ssl_mbedtls.c
index 6d023af..0cf89a8 100644
--- a/src/openvpn/ssl_mbedtls.c
+++ b/src/openvpn/ssl_mbedtls.c
@@ -146,12 +146,6 @@ tls_ctx_free(struct tls_root_ctx *ctx)
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)
{
@@ -413,13 +407,6 @@ tls_ctx_load_priv_file(struct tls_root_ctx *ctx, const
char *priv_key_file,
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.
@@ -446,11 +433,9 @@ external_pkcs1_sign( void *ctx_voidptr,
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;
+ uint8_t *to_sign = NULL;
+ size_t asn_len = 0, oid_size = 0;
const char *oid = NULL;
if (NULL == ctx)
@@ -486,12 +471,14 @@ external_pkcs1_sign( void *ctx_voidptr,
asn_len = 10 + oid_size;
}
- sig_len = ctx->signature_length;
- if ( (SIZE_MAX - hashlen) < asn_len || (hashlen + asn_len) > sig_len)
+ 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)
{
/*
@@ -516,34 +503,16 @@ external_pkcs1_sign( void *ctx_voidptr,
*p++ = MBEDTLS_ASN1_OCTET_STRING;
*p++ = hashlen;
- /* Determine added ASN length */
- asn_len = p - sig;
+ /* Double-check ASN length */
+ ASSERT(asn_len == p - to_sign);
}
/* 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;
- }
+ memcpy(p, hash, hashlen);
- /* 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)
+ /* 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;
@@ -552,14 +521,7 @@ external_pkcs1_sign( void *ctx_voidptr,
rv = 0;
done:
- if (in_b64)
- {
- free(in_b64);
- }
- if (out_b64)
- {
- free(out_b64);
- }
+ free(to_sign);
return rv;
}
@@ -572,7 +534,8 @@ external_key_len(void *vctx)
}
int
-tls_ctx_use_management_external_key(struct tls_root_ctx *ctx)
+tls_ctx_use_external_signing_func(struct tls_root_ctx *ctx,
+ external_sign_func sign_func, void *sign_ctx)
{
ASSERT(NULL != ctx);
@@ -582,11 +545,12 @@ tls_ctx_use_management_external_key(struct tls_root_ctx
*ctx)
return 0;
}
- ALLOC_OBJ_CLEAR(ctx->external_key, struct external_context);
- ctx->external_key->signature_length =
mbedtls_pk_get_len(&ctx->crt_chain->pk);
+ 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,
+ if (!mbed_ok(mbedtls_pk_setup_rsa_alt(ctx->priv_key, &ctx->external_key,
NULL, external_pkcs1_sign,
external_key_len)))
{
return 0;
@@ -594,6 +558,47 @@ tls_ctx_use_management_external_key(struct tls_root_ctx
*ctx)
return 1;
}
+
+#ifdef MANAGMENT_EXTERNAL_KEY
+
+/** 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;
+ }
+
+ if (!(dst_b64 = management_query_rsa_sig(management, src_b64)))
+ {
+ 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 MANAGMENT_EXTERNAL_KEY */
void
diff --git a/src/openvpn/ssl_mbedtls.h b/src/openvpn/ssl_mbedtls.h
index f69b610..2b76cc6 100644
--- a/src/openvpn/ssl_mbedtls.h
+++ b/src/openvpn/ssl_mbedtls.h
@@ -58,6 +58,30 @@ typedef struct {
} bio_ctx;
/**
+ * External signing function prototype. A function pointer to a function
+ * implementing this prototype is provided to
+ * tls_ctx_use_external_signing_func().
+ *
+ * @param sign_ctx The context for the signing function.
+ * @param src The data to be signed,
+ * @param src_len The length of src, in bytes.
+ * @param dst The destination buffer for the signature.
+ * @param dst_len The length of the destination buffer.
+ *
+ * @return true if signing succeeded, false otherwise.
+ */
+typedef bool (*external_sign_func)(
+ void *sign_ctx, const void *src, size_t src_size,
+ void *dst, size_t dst_size);
+
+/** Context used by external_pkcs1_sign() */
+struct external_context {
+ size_t signature_length;
+ external_sign_func sign;
+ void *sign_ctx;
+};
+
+/**
* Structure that wraps the TLS context. Contents differ depending on the
* SSL library used.
*
@@ -78,9 +102,7 @@ struct tls_root_ctx {
#if defined(ENABLE_PKCS11)
mbedtls_pkcs11_context *priv_key_pkcs11; /**< PKCS11 private key */
#endif
-#ifdef MANAGMENT_EXTERNAL_KEY
- struct external_context *external_key; /**< Management external key */
-#endif
+ struct external_context external_key; /**< External key context */
int *allowed_ciphers; /**< List of allowed ciphers for this
connection */
};
@@ -90,5 +112,18 @@ struct key_state_ssl {
bio_ctx bio_ctx;
};
+/**
+ * Call the supplied signing function to create a TLS signature during the
+ * TLS handshake.
+ *
+ * @param ctx TLS context to use.
+ * @param sign_func Signing function to call.
+ * @param sign_ctx Context for the sign function.
+ *
+ * @return 0 if successful, 1 if an error occurred.
+ */
+int tls_ctx_use_external_signing_func(struct tls_root_ctx *ctx,
+ external_sign_func sign_func,
+ void *sign_ctx);
#endif /* SSL_MBEDTLS_H_ */
--
2.7.4
------------------------------------------------------------------------------
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