Make the EVP Key Exchange code provider aware

We introduce a new EVP_KEYEXCH type to represent key exchange algorithms
and refactor the existing code to use it where available.

Reviewed-by: Paul Dale <paul.dale@oracle.com>
(Merged from https://github.com/openssl/openssl/pull/9266)

1 files changed, 354 insertions, 0 deletions

diff --git a/crypto/evp/exchange.c b/crypto/evp/exchange.c
new file mode 100644
index 0000000000..655d5a1c86
--- /dev/null
+++ b/crypto/evp/exchange.c
@@ -0,0 +1,354 @@
+/*
+ * Copyright 2019 The OpenSSL Project Authors. All Rights Reserved.
+ *
+ * Licensed under the Apache License 2.0 (the "License").  You may not use
+ * this file except in compliance with the License.  You can obtain a copy
+ * in the file LICENSE in the source distribution or at
+ * https://www.openssl.org/source/license.html
+ */
+
+#include <openssl/crypto.h>
+#include <openssl/evp.h>
+#include <openssl/err.h>
+#include "internal/refcount.h"
+#include "internal/evp_int.h"
+#include "internal/provider.h"
+#include "evp_locl.h"
+
+static EVP_KEYEXCH *evp_keyexch_new(OSSL_PROVIDER *prov)
+{
+    EVP_KEYEXCH *exchange = OPENSSL_zalloc(sizeof(EVP_KEYEXCH));
+
+    exchange->lock = CRYPTO_THREAD_lock_new();
+    if (exchange->lock == NULL) {
+        OPENSSL_free(exchange);
+        return NULL;
+    }
+    exchange->prov = prov;
+    ossl_provider_up_ref(prov);
+    exchange->refcnt = 1;
+
+    return exchange;
+}
+
+static void *evp_keyexch_from_dispatch(const OSSL_DISPATCH *fns,
+                                       OSSL_PROVIDER *prov)
+{
+    EVP_KEYEXCH *exchange = NULL;
+    int fncnt = 0;
+
+    if ((exchange = evp_keyexch_new(prov)) == NULL)
+        return NULL;
+
+    for (; fns->function_id != 0; fns++) {
+        switch (fns->function_id) {
+        case OSSL_FUNC_KEYEXCH_NEWCTX:
+            if (exchange->newctx != NULL)
+                break;
+            exchange->newctx = OSSL_get_OP_keyexch_newctx(fns);
+            fncnt++;
+            break;
+        case OSSL_FUNC_KEYEXCH_INIT:
+            if (exchange->init != NULL)
+                break;
+            exchange->init = OSSL_get_OP_keyexch_init(fns);
+            fncnt++;
+            break;
+        case OSSL_FUNC_KEYEXCH_SET_PEER:
+            if (exchange->set_peer != NULL)
+                break;
+            exchange->set_peer = OSSL_get_OP_keyexch_set_peer(fns);
+            break;
+        case OSSL_FUNC_KEYEXCH_DERIVE:
+            if (exchange->derive != NULL)
+                break;
+            exchange->derive = OSSL_get_OP_keyexch_derive(fns);
+            fncnt++;
+            break;
+        case OSSL_FUNC_KEYEXCH_FREECTX:
+            if (exchange->freectx != NULL)
+                break;
+            exchange->freectx = OSSL_get_OP_keyexch_freectx(fns);
+            fncnt++;
+            break;
+        case OSSL_FUNC_KEYEXCH_DUPCTX:
+            if (exchange->dupctx != NULL)
+                break;
+            exchange->dupctx = OSSL_get_OP_keyexch_dupctx(fns);
+            break;
+        }
+    }
+    if (fncnt != 4) {
+        /*
+         * In order to be a consistent set of functions we must have at least
+         * a complete set of "exchange" functions: init, derive, newctx,
+         * and freectx. The dupctx and set_peer functions are optional.
+         */
+        EVP_KEYEXCH_free(exchange);
+        EVPerr(EVP_F_EVP_KEYEXCH_FROM_DISPATCH,
+               EVP_R_INVALID_PROVIDER_FUNCTIONS);
+        return NULL;
+    }
+
+    return exchange;
+}
+
+void EVP_KEYEXCH_free(EVP_KEYEXCH *exchange)
+{
+    if (exchange != NULL) {
+        int i;
+
+        CRYPTO_DOWN_REF(&exchange->refcnt, &i, exchange->lock);
+        if (i > 0)
+            return;
+        ossl_provider_free(exchange->prov);
+        CRYPTO_THREAD_lock_free(exchange->lock);
+        OPENSSL_free(exchange);
+    }
+}
+
+int EVP_KEYEXCH_up_ref(EVP_KEYEXCH *exchange)
+{
+    int ref = 0;
+
+    CRYPTO_UP_REF(&exchange->refcnt, &ref, exchange->lock);
+    return 1;
+}
+
+EVP_KEYEXCH *EVP_KEYEXCH_fetch(OPENSSL_CTX *ctx, const char *algorithm,
+                               const char *properties)
+{
+    return evp_generic_fetch(ctx, OSSL_OP_KEYEXCH, algorithm, properties,
+                             evp_keyexch_from_dispatch,
+                             (int (*)(void *))EVP_KEYEXCH_up_ref,
+                             (void (*)(void *))EVP_KEYEXCH_free);
+}
+
+int EVP_PKEY_derive_init_ex(EVP_PKEY_CTX *ctx, EVP_KEYEXCH *exchange)
+{
+    int ret;
+    OSSL_PARAM *param = NULL;
+    size_t paramsz = 0;
+
+    ctx->operation = EVP_PKEY_OP_DERIVE;
+
+    if (ctx->engine != NULL)
+        goto legacy;
+
+    if (exchange != NULL) {
+        if (!EVP_KEYEXCH_up_ref(exchange))
+            goto err;
+    } else {
+        int nid = ctx->pkey != NULL ? ctx->pkey->type : ctx->pmeth->pkey_id;
+
+        /*
+         * TODO(3.0): Check for legacy handling. Remove this once all all
+         * algorithms are moved to providers.
+         */
+        if (ctx->pkey != NULL) {
+            switch (ctx->pkey->type) {
+#if 0
+            case EVP_PKEY_DH:
+                break;
+#endif
+            default:
+                goto legacy;
+            }
+            exchange = EVP_KEYEXCH_fetch(NULL, OBJ_nid2sn(nid), NULL);
+        } else {
+            goto legacy;
+        }
+
+        if (exchange == NULL) {
+            EVPerr(EVP_F_EVP_PKEY_DERIVE_INIT_EX, EVP_R_INITIALIZATION_ERROR);
+            goto err;
+        }
+    }
+
+    if (ctx->exchprovctx != NULL && ctx->exchange != NULL)
+        ctx->exchange->freectx(ctx->exchprovctx);
+    EVP_KEYEXCH_free(ctx->exchange);
+    ctx->exchange = exchange;
+    if (ctx->pkey != NULL) {
+        param = evp_pkey_to_param(ctx->pkey, &paramsz);
+        if (param == NULL) {
+            EVPerr(EVP_F_EVP_PKEY_DERIVE_INIT_EX, EVP_R_INITIALIZATION_ERROR);
+            goto err;
+        }
+    }
+    ctx->exchprovctx = exchange->newctx(ossl_provider_ctx(exchange->prov));
+    if (ctx->exchprovctx == NULL) {
+        OPENSSL_secure_clear_free(param, paramsz);
+        EVPerr(EVP_F_EVP_PKEY_DERIVE_INIT_EX, EVP_R_INITIALIZATION_ERROR);
+        goto err;
+    }
+    ret = exchange->init(ctx->exchprovctx, param);
+    /*
+     * TODO(3.0): Really we should detect whether to call OPENSSL_free or
+     * OPENSSL_secure_clear_free based on the presence of a private key or not.
+     * Since we always expect a private key to be present we just call
+     * OPENSSL_secure_clear_free for now.
+     */
+    OPENSSL_secure_clear_free(param, paramsz);
+
+    return ret ? 1 : 0;
+ err:
+    ctx->operation = EVP_PKEY_OP_UNDEFINED;
+    return 0;
+
+ legacy:
+    if (ctx == NULL || ctx->pmeth == NULL || ctx->pmeth->derive == NULL) {
+        EVPerr(EVP_F_EVP_PKEY_DERIVE_INIT_EX,
+               EVP_R_OPERATION_NOT_SUPPORTED_FOR_THIS_KEYTYPE);
+        return -2;
+    }
+
+    if (ctx->pmeth->derive_init == NULL)
+        return 1;
+    ret = ctx->pmeth->derive_init(ctx);
+    if (ret <= 0)
+        ctx->operation = EVP_PKEY_OP_UNDEFINED;
+    return ret;
+}
+
+int EVP_PKEY_derive_init(EVP_PKEY_CTX *ctx)
+{
+    return EVP_PKEY_derive_init_ex(ctx, NULL);
+}
+
+int EVP_PKEY_derive_set_peer(EVP_PKEY_CTX *ctx, EVP_PKEY *peer)
+{
+    int ret;
+    OSSL_PARAM *param = NULL;
+
+    if (ctx == NULL) {
+        EVPerr(EVP_F_EVP_PKEY_DERIVE_SET_PEER,
+               EVP_R_OPERATION_NOT_SUPPORTED_FOR_THIS_KEYTYPE);
+        return -2;
+    }
+
+    if (ctx->exchprovctx == NULL)
+        goto legacy;
+
+    if (ctx->operation != EVP_PKEY_OP_DERIVE) {
+        EVPerr(EVP_F_EVP_PKEY_DERIVE_SET_PEER,
+               EVP_R_OPERATON_NOT_INITIALIZED);
+        return -1;
+    }
+
+    if (ctx->exchange->set_peer == NULL) {
+        EVPerr(EVP_F_EVP_PKEY_DERIVE_SET_PEER,
+               EVP_R_OPERATION_NOT_SUPPORTED_FOR_THIS_KEYTYPE);
+        return -2;
+    }
+
+    param = evp_pkey_to_param(peer, NULL);
+    if (param == NULL) {
+        EVPerr(EVP_F_EVP_PKEY_DERIVE_SET_PEER, ERR_R_INTERNAL_ERROR);
+        return 0;
+    }
+    ret = ctx->exchange->set_peer(ctx->exchprovctx, param);
+    /*
+     * TODO(3.0): Really we should detect whether to call OPENSSL_free or
+     * OPENSSL_secure_clear_free based on the presence of a private key or not.
+     * Since we always expect a public key to be present we just call
+     * OPENSSL_free for now.
+     */
+    OPENSSL_free(param);
+
+    return ret;
+
+ legacy:
+    if (ctx->pmeth == NULL
+        || !(ctx->pmeth->derive != NULL
+             || ctx->pmeth->encrypt != NULL
+             || ctx->pmeth->decrypt != NULL)
+        || ctx->pmeth->ctrl == NULL) {
+        EVPerr(EVP_F_EVP_PKEY_DERIVE_SET_PEER,
+               EVP_R_OPERATION_NOT_SUPPORTED_FOR_THIS_KEYTYPE);
+        return -2;
+    }
+    if (ctx->operation != EVP_PKEY_OP_DERIVE
+        && ctx->operation != EVP_PKEY_OP_ENCRYPT
+        && ctx->operation != EVP_PKEY_OP_DECRYPT) {
+        EVPerr(EVP_F_EVP_PKEY_DERIVE_SET_PEER,
+               EVP_R_OPERATON_NOT_INITIALIZED);
+        return -1;
+    }
+
+    ret = ctx->pmeth->ctrl(ctx, EVP_PKEY_CTRL_PEER_KEY, 0, peer);
+
+    if (ret <= 0)
+        return ret;
+
+    if (ret == 2)
+        return 1;
+
+    if (ctx->pkey == NULL) {
+        EVPerr(EVP_F_EVP_PKEY_DERIVE_SET_PEER, EVP_R_NO_KEY_SET);
+        return -1;
+    }
+
+    if (ctx->pkey->type != peer->type) {
+        EVPerr(EVP_F_EVP_PKEY_DERIVE_SET_PEER, EVP_R_DIFFERENT_KEY_TYPES);
+        return -1;
+    }
+
+    /*
+     * For clarity.  The error is if parameters in peer are
+     * present (!missing) but don't match.  EVP_PKEY_cmp_parameters may return
+     * 1 (match), 0 (don't match) and -2 (comparison is not defined).  -1
+     * (different key types) is impossible here because it is checked earlier.
+     * -2 is OK for us here, as well as 1, so we can check for 0 only.
+     */
+    if (!EVP_PKEY_missing_parameters(peer) &&
+        !EVP_PKEY_cmp_parameters(ctx->pkey, peer)) {
+        EVPerr(EVP_F_EVP_PKEY_DERIVE_SET_PEER, EVP_R_DIFFERENT_PARAMETERS);
+        return -1;
+    }
+
+    EVP_PKEY_free(ctx->peerkey);
+    ctx->peerkey = peer;
+
+    ret = ctx->pmeth->ctrl(ctx, EVP_PKEY_CTRL_PEER_KEY, 1, peer);
+
+    if (ret <= 0) {
+        ctx->peerkey = NULL;
+        return ret;
+    }
+
+    EVP_PKEY_up_ref(peer);
+    return 1;
+}
+
+int EVP_PKEY_derive(EVP_PKEY_CTX *ctx, unsigned char *key, size_t *pkeylen)
+{
+    int ret;
+
+    if (ctx == NULL) {
+        EVPerr(EVP_F_EVP_PKEY_DERIVE,
+               EVP_R_OPERATION_NOT_SUPPORTED_FOR_THIS_KEYTYPE);
+        return -2;
+    }
+
+    if (ctx->operation != EVP_PKEY_OP_DERIVE) {
+        EVPerr(EVP_F_EVP_PKEY_DERIVE, EVP_R_OPERATON_NOT_INITIALIZED);
+        return -1;
+    }
+
+    if (ctx->exchprovctx == NULL)
+        goto legacy;
+
+    ret = ctx->exchange->derive(ctx->exchprovctx, key, pkeylen, SIZE_MAX);
+
+    return ret;
+ legacy:
+    if (ctx ==  NULL || ctx->pmeth == NULL || ctx->pmeth->derive == NULL) {
+        EVPerr(EVP_F_EVP_PKEY_DERIVE,
+               EVP_R_OPERATION_NOT_SUPPORTED_FOR_THIS_KEYTYPE);
+        return -2;
+    }
+
+    M_check_autoarg(ctx, key, pkeylen, EVP_F_EVP_PKEY_DERIVE)
+        return ctx->pmeth->derive(ctx, key, pkeylen);
+}