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openssl/crypto/ec/ec_pmeth.c
Matt Caswell 5dc6489bb6 Update our EVP_PKEY_METHODs to get low level keys via public APIs 
It is possible to call built-in EVP_PKEY_METHOD functions with a provided
key. For example this might occur if a custom EVP_PKEY_METHOD is in use
that wraps a built-in EVP_PKEY_METHOD. Therefore our EVP_PKEY_METHOD
functions should not assume that we are using a legacy key. Instead we
get the low level key using EVP_PKEY_get0_RSA() or other similar functions.
This "does the right thing" if the key is actually provided.

Reviewed-by: Paul Dale <pauli@openssl.org>
Reviewed-by: Nicola Tuveri <nic.tuv@gmail.com>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/16118)
2021-07-22 13:52:46 +02:00

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/*
* Copyright 2006-2021 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
*/
/*
* ECDH and ECDSA low level APIs are deprecated for public use, but still ok
* for internal use.
*/
#include "internal/deprecated.h"
#include <stdio.h>
#include "internal/cryptlib.h"
#include <openssl/asn1t.h>
#include <openssl/x509.h>
#include <openssl/ec.h>
#include "ec_local.h"
#include <openssl/evp.h>
#include "crypto/evp.h"
/* EC pkey context structure */
typedef struct {
/* Key and paramgen group */
EC_GROUP *gen_group;
/* message digest */
const EVP_MD *md;
/* Duplicate key if custom cofactor needed */
EC_KEY *co_key;
/* Cofactor mode */
signed char cofactor_mode;
/* KDF (if any) to use for ECDH */
char kdf_type;
/* Message digest to use for key derivation */
const EVP_MD *kdf_md;
/* User key material */
unsigned char *kdf_ukm;
size_t kdf_ukmlen;
/* KDF output length */
size_t kdf_outlen;
} EC_PKEY_CTX;
static int pkey_ec_init(EVP_PKEY_CTX *ctx)
{
EC_PKEY_CTX *dctx;
if ((dctx = OPENSSL_zalloc(sizeof(*dctx))) == NULL) {
ERR_raise(ERR_LIB_EC, ERR_R_MALLOC_FAILURE);
return 0;
}
dctx->cofactor_mode = -1;
dctx->kdf_type = EVP_PKEY_ECDH_KDF_NONE;
ctx->data = dctx;
return 1;
}
static int pkey_ec_copy(EVP_PKEY_CTX *dst, const EVP_PKEY_CTX *src)
{
EC_PKEY_CTX *dctx, *sctx;
if (!pkey_ec_init(dst))
return 0;
sctx = src->data;
dctx = dst->data;
if (sctx->gen_group) {
dctx->gen_group = EC_GROUP_dup(sctx->gen_group);
if (!dctx->gen_group)
return 0;
}
dctx->md = sctx->md;
if (sctx->co_key) {
dctx->co_key = EC_KEY_dup(sctx->co_key);
if (!dctx->co_key)
return 0;
}
dctx->kdf_type = sctx->kdf_type;
dctx->kdf_md = sctx->kdf_md;
dctx->kdf_outlen = sctx->kdf_outlen;
if (sctx->kdf_ukm) {
dctx->kdf_ukm = OPENSSL_memdup(sctx->kdf_ukm, sctx->kdf_ukmlen);
if (!dctx->kdf_ukm)
return 0;
} else
dctx->kdf_ukm = NULL;
dctx->kdf_ukmlen = sctx->kdf_ukmlen;
return 1;
}
static void pkey_ec_cleanup(EVP_PKEY_CTX *ctx)
{
EC_PKEY_CTX *dctx = ctx->data;
if (dctx != NULL) {
EC_GROUP_free(dctx->gen_group);
EC_KEY_free(dctx->co_key);
OPENSSL_free(dctx->kdf_ukm);
OPENSSL_free(dctx);
ctx->data = NULL;
}
}
static int pkey_ec_sign(EVP_PKEY_CTX *ctx, unsigned char *sig, size_t *siglen,
const unsigned char *tbs, size_t tbslen)
{
int ret, type;
unsigned int sltmp;
EC_PKEY_CTX *dctx = ctx->data;
/*
* Discard const. Its marked as const because this may be a cached copy of
* the "real" key. These calls don't make any modifications that need to
* be reflected back in the "original" key.
*/
EC_KEY *ec = (EC_KEY *)EVP_PKEY_get0_EC_KEY(ctx->pkey);
const int sig_sz = ECDSA_size(ec);
/* ensure cast to size_t is safe */
if (!ossl_assert(sig_sz > 0))
return 0;
if (sig == NULL) {
*siglen = (size_t)sig_sz;
return 1;
}
if (*siglen < (size_t)sig_sz) {
ERR_raise(ERR_LIB_EC, EC_R_BUFFER_TOO_SMALL);
return 0;
}
type = (dctx->md != NULL) ? EVP_MD_get_type(dctx->md) : NID_sha1;
ret = ECDSA_sign(type, tbs, tbslen, sig, &sltmp, ec);
if (ret <= 0)
return ret;
*siglen = (size_t)sltmp;
return 1;
}
static int pkey_ec_verify(EVP_PKEY_CTX *ctx,
const unsigned char *sig, size_t siglen,
const unsigned char *tbs, size_t tbslen)
{
int ret, type;
EC_PKEY_CTX *dctx = ctx->data;
/*
* Discard const. Its marked as const because this may be a cached copy of
* the "real" key. These calls don't make any modifications that need to
* be reflected back in the "original" key.
*/
EC_KEY *ec = (EC_KEY *)EVP_PKEY_get0_EC_KEY(ctx->pkey);
if (dctx->md)
type = EVP_MD_get_type(dctx->md);
else
type = NID_sha1;
ret = ECDSA_verify(type, tbs, tbslen, sig, siglen, ec);
return ret;
}
#ifndef OPENSSL_NO_EC
static int pkey_ec_derive(EVP_PKEY_CTX *ctx, unsigned char *key, size_t *keylen)
{
int ret;
size_t outlen;
const EC_POINT *pubkey = NULL;
EC_KEY *eckey;
const EC_KEY *eckeypub;
EC_PKEY_CTX *dctx = ctx->data;
if (ctx->pkey == NULL || ctx->peerkey == NULL) {
ERR_raise(ERR_LIB_EC, EC_R_KEYS_NOT_SET);
return 0;
}
eckeypub = EVP_PKEY_get0_EC_KEY(ctx->peerkey);
if (eckeypub == NULL) {
ERR_raise(ERR_LIB_EC, EC_R_KEYS_NOT_SET);
return 0;
}
eckey = dctx->co_key ? dctx->co_key
: (EC_KEY *)EVP_PKEY_get0_EC_KEY(ctx->pkey);
if (!key) {
const EC_GROUP *group;
group = EC_KEY_get0_group(eckey);
if (group == NULL)
return 0;
*keylen = (EC_GROUP_get_degree(group) + 7) / 8;
return 1;
}
pubkey = EC_KEY_get0_public_key(eckeypub);
/*
* NB: unlike PKCS#3 DH, if *outlen is less than maximum size this is not
* an error, the result is truncated.
*/
outlen = *keylen;
ret = ECDH_compute_key(key, outlen, pubkey, eckey, 0);
if (ret <= 0)
return 0;
*keylen = ret;
return 1;
}
static int pkey_ec_kdf_derive(EVP_PKEY_CTX *ctx,
unsigned char *key, size_t *keylen)
{
EC_PKEY_CTX *dctx = ctx->data;
unsigned char *ktmp = NULL;
size_t ktmplen;
int rv = 0;
if (dctx->kdf_type == EVP_PKEY_ECDH_KDF_NONE)
return pkey_ec_derive(ctx, key, keylen);
if (!key) {
*keylen = dctx->kdf_outlen;
return 1;
}
if (*keylen != dctx->kdf_outlen)
return 0;
if (!pkey_ec_derive(ctx, NULL, &ktmplen))
return 0;
if ((ktmp = OPENSSL_malloc(ktmplen)) == NULL) {
ERR_raise(ERR_LIB_EC, ERR_R_MALLOC_FAILURE);
return 0;
}
if (!pkey_ec_derive(ctx, ktmp, &ktmplen))
goto err;
/* Do KDF stuff */
if (!ossl_ecdh_kdf_X9_63(key, *keylen, ktmp, ktmplen,
dctx->kdf_ukm, dctx->kdf_ukmlen, dctx->kdf_md,
ctx->libctx, ctx->propquery))
goto err;
rv = 1;
err:
OPENSSL_clear_free(ktmp, ktmplen);
return rv;
}
#endif
static int pkey_ec_ctrl(EVP_PKEY_CTX *ctx, int type, int p1, void *p2)
{
EC_PKEY_CTX *dctx = ctx->data;
EC_GROUP *group;
switch (type) {
case EVP_PKEY_CTRL_EC_PARAMGEN_CURVE_NID:
group = EC_GROUP_new_by_curve_name(p1);
if (group == NULL) {
ERR_raise(ERR_LIB_EC, EC_R_INVALID_CURVE);
return 0;
}
EC_GROUP_free(dctx->gen_group);
dctx->gen_group = group;
return 1;
case EVP_PKEY_CTRL_EC_PARAM_ENC:
if (!dctx->gen_group) {
ERR_raise(ERR_LIB_EC, EC_R_NO_PARAMETERS_SET);
return 0;
}
EC_GROUP_set_asn1_flag(dctx->gen_group, p1);
return 1;
#ifndef OPENSSL_NO_EC
case EVP_PKEY_CTRL_EC_ECDH_COFACTOR:
if (p1 == -2) {
if (dctx->cofactor_mode != -1)
return dctx->cofactor_mode;
else {
const EC_KEY *ec_key = EVP_PKEY_get0_EC_KEY(ctx->pkey);
return EC_KEY_get_flags(ec_key) & EC_FLAG_COFACTOR_ECDH ? 1 : 0;
}
} else if (p1 < -1 || p1 > 1)
return -2;
dctx->cofactor_mode = p1;
if (p1 != -1) {
EC_KEY *ec_key = (EC_KEY *)EVP_PKEY_get0_EC_KEY(ctx->pkey);
/*
* We discarded the "const" above. This will only work if the key is
* a "real" legacy key, and not a cached copy of a provided key
*/
if (evp_pkey_is_provided(ctx->pkey)) {
ERR_raise(ERR_LIB_EC, ERR_R_UNSUPPORTED);
return 0;
}
if (!ec_key->group)
return -2;
/* If cofactor is 1 cofactor mode does nothing */
if (BN_is_one(ec_key->group->cofactor))
return 1;
if (!dctx->co_key) {
dctx->co_key = EC_KEY_dup(ec_key);
if (!dctx->co_key)
return 0;
}
if (p1)
EC_KEY_set_flags(dctx->co_key, EC_FLAG_COFACTOR_ECDH);
else
EC_KEY_clear_flags(dctx->co_key, EC_FLAG_COFACTOR_ECDH);
} else {
EC_KEY_free(dctx->co_key);
dctx->co_key = NULL;
}
return 1;
#endif
case EVP_PKEY_CTRL_EC_KDF_TYPE:
if (p1 == -2)
return dctx->kdf_type;
if (p1 != EVP_PKEY_ECDH_KDF_NONE && p1 != EVP_PKEY_ECDH_KDF_X9_63)
return -2;
dctx->kdf_type = p1;
return 1;
case EVP_PKEY_CTRL_EC_KDF_MD:
dctx->kdf_md = p2;
return 1;
case EVP_PKEY_CTRL_GET_EC_KDF_MD:
*(const EVP_MD **)p2 = dctx->kdf_md;
return 1;
case EVP_PKEY_CTRL_EC_KDF_OUTLEN:
if (p1 <= 0)
return -2;
dctx->kdf_outlen = (size_t)p1;
return 1;
case EVP_PKEY_CTRL_GET_EC_KDF_OUTLEN:
*(int *)p2 = dctx->kdf_outlen;
return 1;
case EVP_PKEY_CTRL_EC_KDF_UKM:
OPENSSL_free(dctx->kdf_ukm);
dctx->kdf_ukm = p2;
if (p2)
dctx->kdf_ukmlen = p1;
else
dctx->kdf_ukmlen = 0;
return 1;
case EVP_PKEY_CTRL_GET_EC_KDF_UKM:
*(unsigned char **)p2 = dctx->kdf_ukm;
return dctx->kdf_ukmlen;
case EVP_PKEY_CTRL_MD:
if (EVP_MD_get_type((const EVP_MD *)p2) != NID_sha1 &&
EVP_MD_get_type((const EVP_MD *)p2) != NID_ecdsa_with_SHA1 &&
EVP_MD_get_type((const EVP_MD *)p2) != NID_sha224 &&
EVP_MD_get_type((const EVP_MD *)p2) != NID_sha256 &&
EVP_MD_get_type((const EVP_MD *)p2) != NID_sha384 &&
EVP_MD_get_type((const EVP_MD *)p2) != NID_sha512 &&
EVP_MD_get_type((const EVP_MD *)p2) != NID_sha3_224 &&
EVP_MD_get_type((const EVP_MD *)p2) != NID_sha3_256 &&
EVP_MD_get_type((const EVP_MD *)p2) != NID_sha3_384 &&
EVP_MD_get_type((const EVP_MD *)p2) != NID_sha3_512 &&
EVP_MD_get_type((const EVP_MD *)p2) != NID_sm3) {
ERR_raise(ERR_LIB_EC, EC_R_INVALID_DIGEST_TYPE);
return 0;
}
dctx->md = p2;
return 1;
case EVP_PKEY_CTRL_GET_MD:
*(const EVP_MD **)p2 = dctx->md;
return 1;
case EVP_PKEY_CTRL_PEER_KEY:
/* Default behaviour is OK */
case EVP_PKEY_CTRL_DIGESTINIT:
case EVP_PKEY_CTRL_PKCS7_SIGN:
case EVP_PKEY_CTRL_CMS_SIGN:
return 1;
default:
return -2;
}
}
static int pkey_ec_ctrl_str(EVP_PKEY_CTX *ctx,
const char *type, const char *value)
{
if (strcmp(type, "ec_paramgen_curve") == 0) {
int nid;
nid = EC_curve_nist2nid(value);
if (nid == NID_undef)
nid = OBJ_sn2nid(value);
if (nid == NID_undef)
nid = OBJ_ln2nid(value);
if (nid == NID_undef) {
ERR_raise(ERR_LIB_EC, EC_R_INVALID_CURVE);
return 0;
}
return EVP_PKEY_CTX_set_ec_paramgen_curve_nid(ctx, nid);
} else if (strcmp(type, "ec_param_enc") == 0) {
int param_enc;
if (strcmp(value, "explicit") == 0)
param_enc = 0;
else if (strcmp(value, "named_curve") == 0)
param_enc = OPENSSL_EC_NAMED_CURVE;
else
return -2;
return EVP_PKEY_CTX_set_ec_param_enc(ctx, param_enc);
} else if (strcmp(type, "ecdh_kdf_md") == 0) {
const EVP_MD *md;
if ((md = EVP_get_digestbyname(value)) == NULL) {
ERR_raise(ERR_LIB_EC, EC_R_INVALID_DIGEST);
return 0;
}
return EVP_PKEY_CTX_set_ecdh_kdf_md(ctx, md);
} else if (strcmp(type, "ecdh_cofactor_mode") == 0) {
int co_mode;
co_mode = atoi(value);
return EVP_PKEY_CTX_set_ecdh_cofactor_mode(ctx, co_mode);
}
return -2;
}
static int pkey_ec_paramgen(EVP_PKEY_CTX *ctx, EVP_PKEY *pkey)
{
EC_KEY *ec = NULL;
EC_PKEY_CTX *dctx = ctx->data;
int ret;
if (dctx->gen_group == NULL) {
ERR_raise(ERR_LIB_EC, EC_R_NO_PARAMETERS_SET);
return 0;
}
ec = EC_KEY_new();
if (ec == NULL)
return 0;
if (!(ret = EC_KEY_set_group(ec, dctx->gen_group))
|| !ossl_assert(ret = EVP_PKEY_assign_EC_KEY(pkey, ec)))
EC_KEY_free(ec);
return ret;
}
static int pkey_ec_keygen(EVP_PKEY_CTX *ctx, EVP_PKEY *pkey)
{
EC_KEY *ec = NULL;
EC_PKEY_CTX *dctx = ctx->data;
int ret;
if (ctx->pkey == NULL && dctx->gen_group == NULL) {
ERR_raise(ERR_LIB_EC, EC_R_NO_PARAMETERS_SET);
return 0;
}
ec = EC_KEY_new();
if (ec == NULL)
return 0;
if (!ossl_assert(EVP_PKEY_assign_EC_KEY(pkey, ec))) {
EC_KEY_free(ec);
return 0;
}
/* Note: if error is returned, we count on caller to free pkey->pkey.ec */
if (ctx->pkey != NULL)
ret = EVP_PKEY_copy_parameters(pkey, ctx->pkey);
else
ret = EC_KEY_set_group(ec, dctx->gen_group);
return ret ? EC_KEY_generate_key(ec) : 0;
}
static const EVP_PKEY_METHOD ec_pkey_meth = {
EVP_PKEY_EC,
0,
pkey_ec_init,
pkey_ec_copy,
pkey_ec_cleanup,
0,
pkey_ec_paramgen,
0,
pkey_ec_keygen,
0,
pkey_ec_sign,
0,
pkey_ec_verify,
0, 0,
0, 0, 0, 0,
0,
0,
0,
0,
0,
#ifndef OPENSSL_NO_EC
pkey_ec_kdf_derive,
#else
0,
#endif
pkey_ec_ctrl,
pkey_ec_ctrl_str
};
const EVP_PKEY_METHOD *ossl_ec_pkey_method(void)
{
return &ec_pkey_meth;
}
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