e3fe0ae129
According to SP800-56A section 5.6.2.1, the public key to be processed for the DH operation shall be checked for appropriateness. The check shall covers the full verification test in case the domain parameter Q is provided as defined in SP800-56A section 5.6.2.3.1. If Q is not provided, the partial check according to SP800-56A section 5.6.2.3.2 is performed. The full verification test requires the presence of the domain parameter Q. Thus, the patch adds the support to handle Q. It is permissible to not provide the Q value as part of the domain parameters. This implies that the interface is still backwards-compatible where so far only P and G are to be provided. However, if Q is provided, it is imported. Without the test, the NIST ACVP testing fails. After adding this check, the NIST ACVP testing passes. Testing without providing the Q domain parameter has been performed to verify the interface has not changed. Signed-off-by: Stephan Mueller <smueller@chronox.de> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
244 lines
4.9 KiB
C
244 lines
4.9 KiB
C
/* Diffie-Hellman Key Agreement Method [RFC2631]
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*
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* Copyright (c) 2016, Intel Corporation
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* Authors: Salvatore Benedetto <salvatore.benedetto@intel.com>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#include <linux/module.h>
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#include <crypto/internal/kpp.h>
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#include <crypto/kpp.h>
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#include <crypto/dh.h>
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#include <linux/mpi.h>
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struct dh_ctx {
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MPI p; /* Value is guaranteed to be set. */
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MPI q; /* Value is optional. */
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MPI g; /* Value is guaranteed to be set. */
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MPI xa; /* Value is guaranteed to be set. */
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};
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static void dh_clear_ctx(struct dh_ctx *ctx)
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{
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mpi_free(ctx->p);
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mpi_free(ctx->q);
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mpi_free(ctx->g);
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mpi_free(ctx->xa);
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memset(ctx, 0, sizeof(*ctx));
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}
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/*
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* If base is g we compute the public key
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* ya = g^xa mod p; [RFC2631 sec 2.1.1]
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* else if base if the counterpart public key we compute the shared secret
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* ZZ = yb^xa mod p; [RFC2631 sec 2.1.1]
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*/
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static int _compute_val(const struct dh_ctx *ctx, MPI base, MPI val)
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{
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/* val = base^xa mod p */
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return mpi_powm(val, base, ctx->xa, ctx->p);
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}
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static inline struct dh_ctx *dh_get_ctx(struct crypto_kpp *tfm)
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{
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return kpp_tfm_ctx(tfm);
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}
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static int dh_check_params_length(unsigned int p_len)
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{
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return (p_len < 1536) ? -EINVAL : 0;
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}
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static int dh_set_params(struct dh_ctx *ctx, struct dh *params)
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{
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if (dh_check_params_length(params->p_size << 3))
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return -EINVAL;
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ctx->p = mpi_read_raw_data(params->p, params->p_size);
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if (!ctx->p)
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return -EINVAL;
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if (params->q && params->q_size) {
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ctx->q = mpi_read_raw_data(params->q, params->q_size);
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if (!ctx->q)
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return -EINVAL;
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}
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ctx->g = mpi_read_raw_data(params->g, params->g_size);
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if (!ctx->g)
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return -EINVAL;
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return 0;
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}
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static int dh_set_secret(struct crypto_kpp *tfm, const void *buf,
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unsigned int len)
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{
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struct dh_ctx *ctx = dh_get_ctx(tfm);
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struct dh params;
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/* Free the old MPI key if any */
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dh_clear_ctx(ctx);
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if (crypto_dh_decode_key(buf, len, ¶ms) < 0)
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goto err_clear_ctx;
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if (dh_set_params(ctx, ¶ms) < 0)
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goto err_clear_ctx;
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ctx->xa = mpi_read_raw_data(params.key, params.key_size);
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if (!ctx->xa)
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goto err_clear_ctx;
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return 0;
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err_clear_ctx:
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dh_clear_ctx(ctx);
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return -EINVAL;
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}
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/*
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* SP800-56A public key verification:
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*
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* * If Q is provided as part of the domain paramenters, a full validation
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* according to SP800-56A section 5.6.2.3.1 is performed.
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*
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* * If Q is not provided, a partial validation according to SP800-56A section
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* 5.6.2.3.2 is performed.
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*/
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static int dh_is_pubkey_valid(struct dh_ctx *ctx, MPI y)
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{
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if (unlikely(!ctx->p))
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return -EINVAL;
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/*
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* Step 1: Verify that 2 <= y <= p - 2.
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*
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* The upper limit check is actually y < p instead of y < p - 1
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* as the mpi_sub_ui function is yet missing.
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*/
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if (mpi_cmp_ui(y, 1) < 1 || mpi_cmp(y, ctx->p) >= 0)
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return -EINVAL;
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/* Step 2: Verify that 1 = y^q mod p */
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if (ctx->q) {
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MPI val = mpi_alloc(0);
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int ret;
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if (!val)
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return -ENOMEM;
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ret = mpi_powm(val, y, ctx->q, ctx->p);
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if (ret) {
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mpi_free(val);
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return ret;
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}
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ret = mpi_cmp_ui(val, 1);
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mpi_free(val);
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if (ret != 0)
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return -EINVAL;
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}
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return 0;
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}
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static int dh_compute_value(struct kpp_request *req)
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{
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struct crypto_kpp *tfm = crypto_kpp_reqtfm(req);
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struct dh_ctx *ctx = dh_get_ctx(tfm);
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MPI base, val = mpi_alloc(0);
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int ret = 0;
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int sign;
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if (!val)
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return -ENOMEM;
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if (unlikely(!ctx->xa)) {
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ret = -EINVAL;
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goto err_free_val;
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}
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if (req->src) {
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base = mpi_read_raw_from_sgl(req->src, req->src_len);
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if (!base) {
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ret = -EINVAL;
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goto err_free_val;
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}
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ret = dh_is_pubkey_valid(ctx, base);
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if (ret)
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goto err_free_val;
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} else {
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base = ctx->g;
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}
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ret = _compute_val(ctx, base, val);
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if (ret)
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goto err_free_base;
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ret = mpi_write_to_sgl(val, req->dst, req->dst_len, &sign);
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if (ret)
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goto err_free_base;
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if (sign < 0)
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ret = -EBADMSG;
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err_free_base:
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if (req->src)
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mpi_free(base);
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err_free_val:
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mpi_free(val);
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return ret;
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}
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static unsigned int dh_max_size(struct crypto_kpp *tfm)
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{
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struct dh_ctx *ctx = dh_get_ctx(tfm);
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return mpi_get_size(ctx->p);
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}
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static void dh_exit_tfm(struct crypto_kpp *tfm)
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{
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struct dh_ctx *ctx = dh_get_ctx(tfm);
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dh_clear_ctx(ctx);
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}
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static struct kpp_alg dh = {
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.set_secret = dh_set_secret,
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.generate_public_key = dh_compute_value,
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.compute_shared_secret = dh_compute_value,
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.max_size = dh_max_size,
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.exit = dh_exit_tfm,
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.base = {
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.cra_name = "dh",
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.cra_driver_name = "dh-generic",
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.cra_priority = 100,
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.cra_module = THIS_MODULE,
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.cra_ctxsize = sizeof(struct dh_ctx),
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},
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};
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static int dh_init(void)
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{
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return crypto_register_kpp(&dh);
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}
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static void dh_exit(void)
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{
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crypto_unregister_kpp(&dh);
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}
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module_init(dh_init);
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module_exit(dh_exit);
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MODULE_ALIAS_CRYPTO("dh");
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MODULE_LICENSE("GPL");
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MODULE_DESCRIPTION("DH generic algorithm");
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