EVP_PKEY & DH: Make DH EVP_PKEY_CTX parameter ctrls / setters more available

EVP_PKEY_CTX_set_dh_ functions were only available when DH was enabled
('no-dsa' not configured).  However, that makes it impossible to use
these functions with an engine or a provider that happens to implement
DH.  This change solves that problem by shuffling these functions to
more appropriate places.

By consequence, there are a number of places where we can remove the
check of OPENSSL_NO_DH.  This requires some re-arrangements of
internal tables to translate between numeric identities and names.

Partially fixes #13550

Reviewed-by: Tomas Mraz <tmraz@fedoraproject.org>
(Merged from https://github.com/openssl/openssl/pull/13589)

1 files changed, 583 insertions, 0 deletions

diff --git a/crypto/evp/dh_ctrl.c b/crypto/evp/dh_ctrl.c
new file mode 100644
index 0000000000..64492389b7
--- /dev/null
+++ b/crypto/evp/dh_ctrl.c
@@ -0,0 +1,583 @@
+/*
+ * Copyright 2020 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 <stdio.h>
+#include <string.h>
+#include <openssl/core_names.h>
+#include <openssl/params.h>
+#include <openssl/err.h>
+#include <openssl/dh.h>
+#include "crypto/dh.h"
+#include "crypto/evp.h"
+
+static int dh_paramgen_check(EVP_PKEY_CTX *ctx)
+{
+    if (ctx == NULL || !EVP_PKEY_CTX_IS_GEN_OP(ctx)) {
+        ERR_raise(ERR_LIB_EVP, EVP_R_COMMAND_NOT_SUPPORTED);
+        /* Uses the same return values as EVP_PKEY_CTX_ctrl */
+        return -2;
+    }
+    /* If key type not DH return error */
+    if (ctx->pmeth != NULL
+        && ctx->pmeth->pkey_id != EVP_PKEY_DH
+        && ctx->pmeth->pkey_id != EVP_PKEY_DHX)
+        return -1;
+    return 1;
+}
+
+static int dh_param_derive_check(EVP_PKEY_CTX *ctx)
+{
+    if (ctx == NULL || !EVP_PKEY_CTX_IS_DERIVE_OP(ctx)) {
+        ERR_raise(ERR_LIB_EVP, EVP_R_COMMAND_NOT_SUPPORTED);
+        /* Uses the same return values as EVP_PKEY_CTX_ctrl */
+        return -2;
+    }
+    /* If key type not DH return error */
+    if (ctx->pmeth != NULL
+        && ctx->pmeth->pkey_id != EVP_PKEY_DH
+        && ctx->pmeth->pkey_id != EVP_PKEY_DHX)
+        return -1;
+    return 1;
+}
+
+int EVP_PKEY_CTX_set_dh_paramgen_gindex(EVP_PKEY_CTX *ctx, int gindex)
+{
+    int ret;
+    OSSL_PARAM params[2], *p = params;
+
+    if ((ret = dh_paramgen_check(ctx)) <= 0)
+        return ret;
+
+    *p++ = OSSL_PARAM_construct_int(OSSL_PKEY_PARAM_FFC_GINDEX, &gindex);
+    *p = OSSL_PARAM_construct_end();
+
+    return EVP_PKEY_CTX_set_params(ctx, params);
+}
+
+int EVP_PKEY_CTX_set_dh_paramgen_seed(EVP_PKEY_CTX *ctx,
+                                      const unsigned char *seed,
+                                      size_t seedlen)
+{
+    int ret;
+    OSSL_PARAM params[2], *p = params;
+
+    if ((ret = dh_paramgen_check(ctx)) <= 0)
+        return ret;
+
+    *p++ = OSSL_PARAM_construct_octet_string(OSSL_PKEY_PARAM_FFC_SEED,
+                                             (void *)seed, seedlen);
+    *p = OSSL_PARAM_construct_end();
+
+    return EVP_PKEY_CTX_set_params(ctx, params);
+}
+
+int EVP_PKEY_CTX_set_dh_paramgen_type(EVP_PKEY_CTX *ctx, int typ)
+{
+    int ret;
+    OSSL_PARAM params[2], *p = params;
+    const char *name;
+
+    if ((ret = dh_paramgen_check(ctx)) <= 0)
+        return ret;
+
+    /* TODO(3.0): Remove this eventually when no more legacy */
+    if (ctx->op.keymgmt.genctx == NULL)
+        return EVP_PKEY_CTX_ctrl(ctx, EVP_PKEY_DH, EVP_PKEY_OP_PARAMGEN,
+                                 EVP_PKEY_CTRL_DH_PARAMGEN_TYPE, typ, NULL);
+
+    name = dh_gen_type_id2name(typ);
+    if (name == NULL)
+        return 0;
+    *p++ = OSSL_PARAM_construct_utf8_string(OSSL_PKEY_PARAM_FFC_TYPE,
+                                            (char *) name, 0);
+    *p = OSSL_PARAM_construct_end();
+
+    return EVP_PKEY_CTX_set_params(ctx, params);
+}
+
+int EVP_PKEY_CTX_set_dh_paramgen_prime_len(EVP_PKEY_CTX *ctx, int pbits)
+{
+    int ret;
+    OSSL_PARAM params[2], *p = params;
+    size_t bits = pbits;
+
+    if ((ret = dh_paramgen_check(ctx)) <= 0)
+        return ret;
+
+    /* TODO(3.0): Remove this eventually when no more legacy */
+    if (ctx->op.keymgmt.genctx == NULL)
+        return EVP_PKEY_CTX_ctrl(ctx, EVP_PKEY_DH, EVP_PKEY_OP_PARAMGEN,
+                                 EVP_PKEY_CTRL_DH_PARAMGEN_PRIME_LEN, pbits,
+                                 NULL);
+    *p++ = OSSL_PARAM_construct_size_t(OSSL_PKEY_PARAM_FFC_PBITS, &bits);
+    *p = OSSL_PARAM_construct_end();
+    return EVP_PKEY_CTX_set_params(ctx, params);
+}
+
+int EVP_PKEY_CTX_set_dh_paramgen_subprime_len(EVP_PKEY_CTX *ctx, int qbits)
+{
+    int ret;
+    OSSL_PARAM params[2], *p = params;
+    size_t bits2 = qbits;
+
+    if ((ret = dh_paramgen_check(ctx)) <= 0)
+        return ret;
+
+    /* TODO(3.0): Remove this eventually when no more legacy */
+    if (ctx->op.keymgmt.genctx == NULL)
+        return EVP_PKEY_CTX_ctrl(ctx, EVP_PKEY_DH, EVP_PKEY_OP_PARAMGEN,
+                                 EVP_PKEY_CTRL_DH_PARAMGEN_SUBPRIME_LEN, qbits,
+                                 NULL);
+    *p++ = OSSL_PARAM_construct_size_t(OSSL_PKEY_PARAM_FFC_QBITS, &bits2);
+    *p = OSSL_PARAM_construct_end();
+
+    return EVP_PKEY_CTX_set_params(ctx, params);
+}
+
+int EVP_PKEY_CTX_set_dh_paramgen_generator(EVP_PKEY_CTX *ctx, int gen)
+{
+    int ret;
+    OSSL_PARAM params[2], *p = params;
+
+    if ((ret = dh_paramgen_check(ctx)) <= 0)
+        return ret;
+
+    /* TODO(3.0): Remove this eventually when no more legacy */
+    if (ctx->op.keymgmt.genctx == NULL)
+        return EVP_PKEY_CTX_ctrl(ctx, EVP_PKEY_DH, EVP_PKEY_OP_PARAMGEN,
+                                 EVP_PKEY_CTRL_DH_PARAMGEN_GENERATOR, gen, NULL);
+    *p++ = OSSL_PARAM_construct_int(OSSL_PKEY_PARAM_DH_GENERATOR, &gen);
+    *p = OSSL_PARAM_construct_end();
+
+    return EVP_PKEY_CTX_set_params(ctx, params);
+}
+
+int EVP_PKEY_CTX_set_dh_rfc5114(EVP_PKEY_CTX *ctx, int gen)
+{
+    int ret;
+    OSSL_PARAM params[2], *p = params;
+    const char *name;
+
+    if ((ret = dh_paramgen_check(ctx)) <= 0)
+        return ret;
+
+    /* TODO(3.0): Remove this eventually when no more legacy */
+    if (ctx->op.keymgmt.genctx == NULL)
+        return EVP_PKEY_CTX_ctrl(ctx, EVP_PKEY_DHX, EVP_PKEY_OP_PARAMGEN,
+                                 EVP_PKEY_CTRL_DH_RFC5114, gen, NULL);
+    name = ossl_ffc_named_group_get_name(ossl_ffc_uid_to_dh_named_group(gen));
+    if (name == NULL)
+        return 0;
+
+    *p++ = OSSL_PARAM_construct_utf8_string(OSSL_PKEY_PARAM_GROUP_NAME,
+                                            (void *)name, 0);
+    *p = OSSL_PARAM_construct_end();
+    return EVP_PKEY_CTX_set_params(ctx, params);
+}
+
+int EVP_PKEY_CTX_set_dhx_rfc5114(EVP_PKEY_CTX *ctx, int gen)
+{
+    return EVP_PKEY_CTX_set_dh_rfc5114(ctx, gen);
+}
+
+int EVP_PKEY_CTX_set_dh_nid(EVP_PKEY_CTX *ctx, int nid)
+{
+    int ret;
+    OSSL_PARAM params[2], *p = params;
+    const char *name;
+
+    if ((ret = dh_paramgen_check(ctx)) <= 0)
+        return ret;
+
+    /* TODO(3.0): Remove this eventually when no more legacy */
+    if (ctx->op.keymgmt.genctx == NULL)
+        return EVP_PKEY_CTX_ctrl(ctx, EVP_PKEY_DH,
+                                 EVP_PKEY_OP_PARAMGEN | EVP_PKEY_OP_KEYGEN,
+                                 EVP_PKEY_CTRL_DH_NID, nid, NULL);
+    name = ossl_ffc_named_group_get_name(ossl_ffc_uid_to_dh_named_group(nid));
+    if (name == NULL)
+        return 0;
+
+    *p++ = OSSL_PARAM_construct_utf8_string(OSSL_PKEY_PARAM_GROUP_NAME,
+                                            (void *)name, 0);
+    *p = OSSL_PARAM_construct_end();
+    return EVP_PKEY_CTX_set_params(ctx, params);
+}
+
+int EVP_PKEY_CTX_set_dh_pad(EVP_PKEY_CTX *ctx, int pad)
+{
+    OSSL_PARAM dh_pad_params[2];
+    unsigned int upad = pad;
+
+    /* We use EVP_PKEY_CTX_ctrl return values */
+    if (ctx == NULL || !EVP_PKEY_CTX_IS_DERIVE_OP(ctx)) {
+        ERR_raise(ERR_LIB_EVP, EVP_R_COMMAND_NOT_SUPPORTED);
+        return -2;
+    }
+
+    /* TODO(3.0): Remove this eventually when no more legacy */
+    if (ctx->op.kex.exchprovctx == NULL)
+        return EVP_PKEY_CTX_ctrl(ctx, EVP_PKEY_DH, EVP_PKEY_OP_DERIVE,
+                                 EVP_PKEY_CTRL_DH_PAD, pad, NULL);
+
+    dh_pad_params[0] = OSSL_PARAM_construct_uint(OSSL_EXCHANGE_PARAM_PAD, &upad);
+    dh_pad_params[1] = OSSL_PARAM_construct_end();
+
+    return EVP_PKEY_CTX_set_params(ctx, dh_pad_params);
+}
+
+int EVP_PKEY_CTX_set_dh_kdf_type(EVP_PKEY_CTX *ctx, int kdf)
+{
+    int ret;
+    const char *kdf_type;
+    OSSL_PARAM params[2], *p = params;
+
+    ret = dh_param_derive_check(ctx);
+    if (ret != 1)
+        return ret;
+
+    /* TODO(3.0): Remove this eventually when no more legacy */
+    if (ctx->op.kex.exchprovctx == NULL)
+        return EVP_PKEY_CTX_ctrl(ctx, EVP_PKEY_DHX, EVP_PKEY_OP_DERIVE,
+                                 EVP_PKEY_CTRL_DH_KDF_TYPE, kdf, NULL);
+    switch (kdf) {
+        case EVP_PKEY_DH_KDF_NONE:
+            kdf_type = "";
+            break;
+        case EVP_PKEY_DH_KDF_X9_42:
+            kdf_type = OSSL_KDF_NAME_X942KDF_ASN1;
+            break;
+        default:
+            return -2;
+    }
+    *p++ = OSSL_PARAM_construct_utf8_string(OSSL_EXCHANGE_PARAM_KDF_TYPE,
+                                            /*
+                                             * Cast away the const. This is read
+                                             * only so should be safe
+                                             */
+                                            (char *)kdf_type, 0);
+    *p = OSSL_PARAM_construct_end();
+
+    ret = evp_pkey_ctx_set_params_strict(ctx, params);
+    if (ret == -2) {
+        ERR_raise(ERR_LIB_EVP, EVP_R_COMMAND_NOT_SUPPORTED);
+        /* Uses the same return values as EVP_PKEY_CTX_ctrl */
+        return -2;
+    }
+
+    return ret;
+}
+
+int EVP_PKEY_CTX_get_dh_kdf_type(EVP_PKEY_CTX *ctx)
+{
+    int ret;
+    char kdf_type[80]; /* 80 should be big enough */
+    OSSL_PARAM params[2], *p = params;
+
+    ret = dh_param_derive_check(ctx);
+    if (ret != 1)
+        return ret;
+
+    /* TODO(3.0): Remove this eventually when no more legacy */
+    if (ctx->op.kex.exchprovctx == NULL)
+        return EVP_PKEY_CTX_ctrl(ctx, EVP_PKEY_DHX, EVP_PKEY_OP_DERIVE,
+                                 EVP_PKEY_CTRL_DH_KDF_TYPE, -2, NULL);
+    *p++ = OSSL_PARAM_construct_utf8_string(OSSL_EXCHANGE_PARAM_KDF_TYPE,
+                                            kdf_type, sizeof(kdf_type));
+    *p = OSSL_PARAM_construct_end();
+
+    ret = evp_pkey_ctx_get_params_strict(ctx, params);
+    if (ret == -2) {
+        ERR_raise(ERR_LIB_EVP, EVP_R_COMMAND_NOT_SUPPORTED);
+        /* Uses the same return values as EVP_PKEY_CTX_ctrl */
+        return -2;
+    } else if (ret != 1) {
+        return -1;
+    }
+
+    if (kdf_type[0] == '\0')
+        return EVP_PKEY_DH_KDF_NONE;
+    else if (strcmp(kdf_type, OSSL_KDF_NAME_X942KDF_ASN1) == 0)
+        return EVP_PKEY_DH_KDF_X9_42;
+
+    return -1;
+}
+
+int EVP_PKEY_CTX_set0_dh_kdf_oid(EVP_PKEY_CTX *ctx, ASN1_OBJECT *oid)
+{
+    int ret;
+    OSSL_PARAM params[2], *p = params;
+    const char *oid_name;
+
+    ret = dh_param_derive_check(ctx);
+    if (ret != 1)
+        return ret;
+
+    /* TODO(3.0): Remove this eventually when no more legacy */
+    if (ctx->op.kex.exchprovctx == NULL)
+        return EVP_PKEY_CTX_ctrl(ctx, EVP_PKEY_DHX, EVP_PKEY_OP_DERIVE,
+                                 EVP_PKEY_CTRL_DH_KDF_OID, 0, (void *)(oid));
+    oid_name = OBJ_nid2sn(OBJ_obj2nid(oid));
+
+    *p++ = OSSL_PARAM_construct_utf8_string(OSSL_KDF_PARAM_CEK_ALG,
+                                            (char *)oid_name, 0);
+    *p = OSSL_PARAM_construct_end();
+    ret = evp_pkey_ctx_set_params_strict(ctx, params);
+    if (ret == -2) {
+        ERR_raise(ERR_LIB_EVP, EVP_R_COMMAND_NOT_SUPPORTED);
+        /* Uses the same return values as EVP_PKEY_CTX_ctrl */
+        return -2;
+    }
+
+    return ret;
+}
+
+int EVP_PKEY_CTX_get0_dh_kdf_oid(EVP_PKEY_CTX *ctx, ASN1_OBJECT **oid)
+{
+    int ret, nid;
+    OSSL_PARAM params[2], *p = params;
+    char oid_name[80]; /* 80 should be big enough */
+
+    ret = dh_param_derive_check(ctx);
+    if (ret != 1)
+        return ret;
+
+    /* TODO(3.0): Remove this eventually when no more legacy */
+    if (ctx->op.kex.exchprovctx == NULL)
+        return EVP_PKEY_CTX_ctrl(ctx, EVP_PKEY_DHX, EVP_PKEY_OP_DERIVE,
+                                 EVP_PKEY_CTRL_GET_DH_KDF_OID, 0, (void *)(oid));
+    *p++ = OSSL_PARAM_construct_utf8_string(OSSL_KDF_PARAM_CEK_ALG,
+                                            oid_name, sizeof(oid_name));
+    *p = OSSL_PARAM_construct_end();
+
+    ret = evp_pkey_ctx_get_params_strict(ctx, params);
+    if (ret == -2) {
+        ERR_raise(ERR_LIB_EVP, EVP_R_COMMAND_NOT_SUPPORTED);
+        /* Uses the same return values as EVP_PKEY_CTX_ctrl */
+        return -2;
+    } else if (ret != 1) {
+        return -1;
+    }
+    nid = OBJ_sn2nid(oid_name);
+    if (nid == NID_undef)
+        nid = OBJ_ln2nid(oid_name);
+    *oid = (nid == NID_undef ? NULL : OBJ_nid2obj(nid));
+    return *oid != NULL;
+}
+
+int EVP_PKEY_CTX_set_dh_kdf_md(EVP_PKEY_CTX *ctx, const EVP_MD *md)
+{
+    int ret;
+    OSSL_PARAM params[2], *p = params;
+    const char *md_name = NULL;
+
+    ret = dh_param_derive_check(ctx);
+    if (ret != 1)
+        return ret;
+
+    /* TODO(3.0): Remove this eventually when no more legacy */
+    if (ctx->op.kex.exchprovctx == NULL)
+        return EVP_PKEY_CTX_ctrl(ctx, EVP_PKEY_DHX, EVP_PKEY_OP_DERIVE,
+                                 EVP_PKEY_CTRL_DH_KDF_MD, 0, (void *)(md));
+    md_name = (md == NULL) ? "" : EVP_MD_name(md);
+
+    *p++ = OSSL_PARAM_construct_utf8_string(OSSL_EXCHANGE_PARAM_KDF_DIGEST,
+                                            /*
+                                             * Cast away the const. This is read
+                                             * only so should be safe
+                                             */
+                                            (char *)md_name, 0);
+    *p = OSSL_PARAM_construct_end();
+
+    ret = evp_pkey_ctx_set_params_strict(ctx, params);
+    if (ret == -2) {
+        ERR_raise(ERR_LIB_EVP, EVP_R_COMMAND_NOT_SUPPORTED);
+        /* Uses the same return values as EVP_PKEY_CTX_ctrl */
+        return -2;
+    }
+    return ret;
+}
+
+int EVP_PKEY_CTX_get_dh_kdf_md(EVP_PKEY_CTX *ctx, const EVP_MD **pmd)
+{
+    int ret;
+    char name[80] = "";  /* 80 should be big enough */
+    OSSL_PARAM params[2], *p = params;
+
+    ret = dh_param_derive_check(ctx);
+    if (ret != 1)
+        return ret;
+
+    /* TODO(3.0): Remove this eventually when no more legacy */
+    if (ctx->op.kex.exchprovctx == NULL)
+        return EVP_PKEY_CTX_ctrl(ctx, EVP_PKEY_DHX, EVP_PKEY_OP_DERIVE,
+                                 EVP_PKEY_CTRL_GET_DH_KDF_MD, 0, (void *)(pmd));
+    *p++ = OSSL_PARAM_construct_utf8_string(OSSL_EXCHANGE_PARAM_KDF_DIGEST,
+                                            name, sizeof(name));
+    *p = OSSL_PARAM_construct_end();
+
+    ret = evp_pkey_ctx_get_params_strict(ctx, params);
+    if (ret == -2) {
+        ERR_raise(ERR_LIB_EVP, EVP_R_COMMAND_NOT_SUPPORTED);
+        /* Uses the same return values as EVP_PKEY_CTX_ctrl */
+        return -2;
+    } else if (ret != 1) {
+        return -1;
+    }
+
+    /* May be NULL meaning "unknown" */
+    *pmd = EVP_get_digestbyname(name);
+
+    return 1;
+}
+
+int EVP_PKEY_CTX_set_dh_kdf_outlen(EVP_PKEY_CTX *ctx, int inlen)
+{
+    int ret;
+    size_t len = inlen;
+    OSSL_PARAM params[2], *p = params;
+
+    ret = dh_param_derive_check(ctx);
+    if (ret != 1)
+        return ret;
+
+    /* TODO(3.0): Remove this eventually when no more legacy */
+    if (ctx->op.kex.exchprovctx == NULL)
+        return EVP_PKEY_CTX_ctrl(ctx, EVP_PKEY_DHX, EVP_PKEY_OP_DERIVE,
+                                 EVP_PKEY_CTRL_DH_KDF_OUTLEN, inlen, NULL);
+    if (inlen <= 0) {
+        /*
+         * This would ideally be -1 or 0, but we have to retain compatibility
+         * with legacy behaviour of EVP_PKEY_CTX_ctrl() which returned -2 if
+         * in <= 0
+         */
+        return -2;
+    }
+
+    *p++ = OSSL_PARAM_construct_size_t(OSSL_EXCHANGE_PARAM_KDF_OUTLEN,
+                                       &len);
+    *p = OSSL_PARAM_construct_end();
+
+    ret = evp_pkey_ctx_set_params_strict(ctx, params);
+    if (ret == -2) {
+        ERR_raise(ERR_LIB_EVP, EVP_R_COMMAND_NOT_SUPPORTED);
+        /* Uses the same return values as EVP_PKEY_CTX_ctrl */
+        return -2;
+    }
+    return ret;
+}
+
+int EVP_PKEY_CTX_get_dh_kdf_outlen(EVP_PKEY_CTX *ctx, int *plen)
+{
+    int ret;
+    size_t len = UINT_MAX;
+    OSSL_PARAM params[2], *p = params;
+
+    ret = dh_param_derive_check(ctx);
+    if (ret != 1)
+        return ret;
+
+    /* TODO(3.0): Remove this eventually when no more legacy */
+    if (ctx->op.kex.exchprovctx == NULL)
+        return EVP_PKEY_CTX_ctrl(ctx, EVP_PKEY_DHX, EVP_PKEY_OP_DERIVE,
+                                 EVP_PKEY_CTRL_GET_DH_KDF_OUTLEN, 0,
+                                 (void *)(plen));
+    *p++ = OSSL_PARAM_construct_size_t(OSSL_EXCHANGE_PARAM_KDF_OUTLEN,
+                                       &len);
+    *p = OSSL_PARAM_construct_end();
+
+    ret = evp_pkey_ctx_get_params_strict(ctx, params);
+    if (ret == -2) {
+        ERR_raise(ERR_LIB_EVP, EVP_R_COMMAND_NOT_SUPPORTED);
+        /* Uses the same return values as EVP_PKEY_CTX_ctrl */
+        return -2;
+    } else if (ret != 1) {
+        return -1;
+    }
+
+    if (len > INT_MAX)
+        return -1;
+
+    *plen = (int)len;
+
+    return 1;
+}
+
+int EVP_PKEY_CTX_set0_dh_kdf_ukm(EVP_PKEY_CTX *ctx, unsigned char *ukm, int len)
+{
+    int ret;
+    OSSL_PARAM params[2], *p = params;
+
+    if (len <= 0)
+        return -1;
+
+    ret = dh_param_derive_check(ctx);
+    if (ret != 1)
+        return ret;
+
+    /* TODO(3.0): Remove this eventually when no more legacy */
+    if (ctx->op.kex.exchprovctx == NULL)
+        return EVP_PKEY_CTX_ctrl(ctx, EVP_PKEY_DHX, EVP_PKEY_OP_DERIVE,
+                                 EVP_PKEY_CTRL_DH_KDF_UKM, len, (void *)(ukm));
+
+    *p++ = OSSL_PARAM_construct_octet_string(OSSL_EXCHANGE_PARAM_KDF_UKM,
+                                            /*
+                                             * Cast away the const. This is read
+                                             * only so should be safe
+                                             */
+                                            (void *)ukm,
+                                            (size_t)len);
+    *p = OSSL_PARAM_construct_end();
+
+    ret = evp_pkey_ctx_set_params_strict(ctx, params);
+    if (ret == -2) {
+        ERR_raise(ERR_LIB_EVP, EVP_R_COMMAND_NOT_SUPPORTED);
+        /* Uses the same return values as EVP_PKEY_CTX_ctrl */
+        return -2;
+    }
+    if (ret == 1)
+        OPENSSL_free(ukm);
+    return ret;
+}
+
+int EVP_PKEY_CTX_get0_dh_kdf_ukm(EVP_PKEY_CTX *ctx, unsigned char **pukm)
+{
+    int ret;
+    size_t ukmlen;
+    OSSL_PARAM params[3], *p = params;
+
+    ret = dh_param_derive_check(ctx);
+    if (ret != 1)
+        return ret;
+
+    /* TODO(3.0): Remove this eventually when no more legacy */
+    if (ctx->op.kex.exchprovctx == NULL)
+        return EVP_PKEY_CTX_ctrl(ctx, EVP_PKEY_DHX, EVP_PKEY_OP_DERIVE,
+                                 EVP_PKEY_CTRL_GET_DH_KDF_UKM, 0, (void *)(pukm));
+
+    *p++ = OSSL_PARAM_construct_octet_ptr(OSSL_EXCHANGE_PARAM_KDF_UKM,
+                                          (void **)pukm, 0);
+    *p++ = OSSL_PARAM_construct_size_t(OSSL_EXCHANGE_PARAM_KDF_UKM_LEN,
+                                       &ukmlen);
+    *p = OSSL_PARAM_construct_end();
+
+    ret = evp_pkey_ctx_get_params_strict(ctx, params);
+    if (ret == -2) {
+        ERR_raise(ERR_LIB_EVP, EVP_R_COMMAND_NOT_SUPPORTED);
+        /* Uses the same return values as EVP_PKEY_CTX_ctrl */
+        return -2;
+    } else if (ret != 1) {
+        return -1;
+    }
+
+    if (ukmlen > INT_MAX)
+        return -1;
+
+    return (int)ukmlen;
+}