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![Herbert Xu](/assets/img/avatar_default.png)
The header file algapi.h includes skbuff.h unnecessarily since all we need is a forward declaration for struct sk_buff. This patch removes that inclusion. Unfortunately skbuff.h pulls in a lot of things and drivers over the years have come to rely on it so this patch adds a lot of missing inclusions that result from this. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
297 lines
8.4 KiB
C
297 lines
8.4 KiB
C
// SPDX-License-Identifier: GPL-2.0+
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/*
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* Elliptic Curve (Russian) Digital Signature Algorithm for Cryptographic API
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*
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* Copyright (c) 2019 Vitaly Chikunov <vt@altlinux.org>
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*
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* References:
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* GOST 34.10-2018, GOST R 34.10-2012, RFC 7091, ISO/IEC 14888-3:2018.
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*
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* Historical references:
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* GOST R 34.10-2001, RFC 4357, ISO/IEC 14888-3:2006/Amd 1:2010.
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the Free
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* Software Foundation; either version 2 of the License, or (at your option)
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* any later version.
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*/
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#include <linux/module.h>
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#include <linux/crypto.h>
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#include <crypto/streebog.h>
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#include <crypto/internal/akcipher.h>
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#include <crypto/akcipher.h>
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#include <linux/oid_registry.h>
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#include <linux/scatterlist.h>
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#include "ecrdsa_params.asn1.h"
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#include "ecrdsa_pub_key.asn1.h"
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#include "ecc.h"
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#include "ecrdsa_defs.h"
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#define ECRDSA_MAX_SIG_SIZE (2 * 512 / 8)
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#define ECRDSA_MAX_DIGITS (512 / 64)
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struct ecrdsa_ctx {
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enum OID algo_oid; /* overall public key oid */
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enum OID curve_oid; /* parameter */
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enum OID digest_oid; /* parameter */
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const struct ecc_curve *curve; /* curve from oid */
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unsigned int digest_len; /* parameter (bytes) */
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const char *digest; /* digest name from oid */
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unsigned int key_len; /* @key length (bytes) */
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const char *key; /* raw public key */
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struct ecc_point pub_key;
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u64 _pubp[2][ECRDSA_MAX_DIGITS]; /* point storage for @pub_key */
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};
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static const struct ecc_curve *get_curve_by_oid(enum OID oid)
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{
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switch (oid) {
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case OID_gostCPSignA:
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case OID_gostTC26Sign256B:
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return &gost_cp256a;
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case OID_gostCPSignB:
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case OID_gostTC26Sign256C:
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return &gost_cp256b;
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case OID_gostCPSignC:
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case OID_gostTC26Sign256D:
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return &gost_cp256c;
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case OID_gostTC26Sign512A:
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return &gost_tc512a;
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case OID_gostTC26Sign512B:
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return &gost_tc512b;
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/* The following two aren't implemented: */
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case OID_gostTC26Sign256A:
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case OID_gostTC26Sign512C:
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default:
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return NULL;
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}
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}
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static int ecrdsa_verify(struct akcipher_request *req)
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{
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struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
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struct ecrdsa_ctx *ctx = akcipher_tfm_ctx(tfm);
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unsigned char sig[ECRDSA_MAX_SIG_SIZE];
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unsigned char digest[STREEBOG512_DIGEST_SIZE];
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unsigned int ndigits = req->dst_len / sizeof(u64);
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u64 r[ECRDSA_MAX_DIGITS]; /* witness (r) */
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u64 _r[ECRDSA_MAX_DIGITS]; /* -r */
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u64 s[ECRDSA_MAX_DIGITS]; /* second part of sig (s) */
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u64 e[ECRDSA_MAX_DIGITS]; /* h \mod q */
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u64 *v = e; /* e^{-1} \mod q */
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u64 z1[ECRDSA_MAX_DIGITS];
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u64 *z2 = _r;
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struct ecc_point cc = ECC_POINT_INIT(s, e, ndigits); /* reuse s, e */
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/*
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* Digest value, digest algorithm, and curve (modulus) should have the
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* same length (256 or 512 bits), public key and signature should be
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* twice bigger.
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*/
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if (!ctx->curve ||
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!ctx->digest ||
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!req->src ||
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!ctx->pub_key.x ||
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req->dst_len != ctx->digest_len ||
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req->dst_len != ctx->curve->g.ndigits * sizeof(u64) ||
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ctx->pub_key.ndigits != ctx->curve->g.ndigits ||
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req->dst_len * 2 != req->src_len ||
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WARN_ON(req->src_len > sizeof(sig)) ||
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WARN_ON(req->dst_len > sizeof(digest)))
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return -EBADMSG;
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sg_copy_to_buffer(req->src, sg_nents_for_len(req->src, req->src_len),
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sig, req->src_len);
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sg_pcopy_to_buffer(req->src,
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sg_nents_for_len(req->src,
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req->src_len + req->dst_len),
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digest, req->dst_len, req->src_len);
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vli_from_be64(s, sig, ndigits);
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vli_from_be64(r, sig + ndigits * sizeof(u64), ndigits);
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/* Step 1: verify that 0 < r < q, 0 < s < q */
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if (vli_is_zero(r, ndigits) ||
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vli_cmp(r, ctx->curve->n, ndigits) == 1 ||
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vli_is_zero(s, ndigits) ||
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vli_cmp(s, ctx->curve->n, ndigits) == 1)
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return -EKEYREJECTED;
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/* Step 2: calculate hash (h) of the message (passed as input) */
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/* Step 3: calculate e = h \mod q */
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vli_from_le64(e, digest, ndigits);
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if (vli_cmp(e, ctx->curve->n, ndigits) == 1)
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vli_sub(e, e, ctx->curve->n, ndigits);
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if (vli_is_zero(e, ndigits))
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e[0] = 1;
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/* Step 4: calculate v = e^{-1} \mod q */
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vli_mod_inv(v, e, ctx->curve->n, ndigits);
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/* Step 5: calculate z_1 = sv \mod q, z_2 = -rv \mod q */
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vli_mod_mult_slow(z1, s, v, ctx->curve->n, ndigits);
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vli_sub(_r, ctx->curve->n, r, ndigits);
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vli_mod_mult_slow(z2, _r, v, ctx->curve->n, ndigits);
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/* Step 6: calculate point C = z_1P + z_2Q, and R = x_c \mod q */
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ecc_point_mult_shamir(&cc, z1, &ctx->curve->g, z2, &ctx->pub_key,
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ctx->curve);
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if (vli_cmp(cc.x, ctx->curve->n, ndigits) == 1)
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vli_sub(cc.x, cc.x, ctx->curve->n, ndigits);
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/* Step 7: if R == r signature is valid */
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if (!vli_cmp(cc.x, r, ndigits))
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return 0;
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else
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return -EKEYREJECTED;
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}
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int ecrdsa_param_curve(void *context, size_t hdrlen, unsigned char tag,
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const void *value, size_t vlen)
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{
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struct ecrdsa_ctx *ctx = context;
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ctx->curve_oid = look_up_OID(value, vlen);
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if (!ctx->curve_oid)
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return -EINVAL;
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ctx->curve = get_curve_by_oid(ctx->curve_oid);
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return 0;
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}
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/* Optional. If present should match expected digest algo OID. */
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int ecrdsa_param_digest(void *context, size_t hdrlen, unsigned char tag,
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const void *value, size_t vlen)
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{
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struct ecrdsa_ctx *ctx = context;
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int digest_oid = look_up_OID(value, vlen);
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if (digest_oid != ctx->digest_oid)
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return -EINVAL;
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return 0;
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}
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int ecrdsa_parse_pub_key(void *context, size_t hdrlen, unsigned char tag,
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const void *value, size_t vlen)
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{
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struct ecrdsa_ctx *ctx = context;
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ctx->key = value;
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ctx->key_len = vlen;
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return 0;
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}
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static u8 *ecrdsa_unpack_u32(u32 *dst, void *src)
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{
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memcpy(dst, src, sizeof(u32));
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return src + sizeof(u32);
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}
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/* Parse BER encoded subjectPublicKey. */
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static int ecrdsa_set_pub_key(struct crypto_akcipher *tfm, const void *key,
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unsigned int keylen)
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{
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struct ecrdsa_ctx *ctx = akcipher_tfm_ctx(tfm);
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unsigned int ndigits;
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u32 algo, paramlen;
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u8 *params;
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int err;
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err = asn1_ber_decoder(&ecrdsa_pub_key_decoder, ctx, key, keylen);
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if (err < 0)
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return err;
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/* Key parameters is in the key after keylen. */
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params = ecrdsa_unpack_u32(¶mlen,
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ecrdsa_unpack_u32(&algo, (u8 *)key + keylen));
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if (algo == OID_gost2012PKey256) {
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ctx->digest = "streebog256";
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ctx->digest_oid = OID_gost2012Digest256;
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ctx->digest_len = 256 / 8;
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} else if (algo == OID_gost2012PKey512) {
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ctx->digest = "streebog512";
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ctx->digest_oid = OID_gost2012Digest512;
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ctx->digest_len = 512 / 8;
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} else
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return -ENOPKG;
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ctx->algo_oid = algo;
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/* Parse SubjectPublicKeyInfo.AlgorithmIdentifier.parameters. */
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err = asn1_ber_decoder(&ecrdsa_params_decoder, ctx, params, paramlen);
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if (err < 0)
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return err;
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/*
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* Sizes of algo (set in digest_len) and curve should match
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* each other.
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*/
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if (!ctx->curve ||
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ctx->curve->g.ndigits * sizeof(u64) != ctx->digest_len)
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return -ENOPKG;
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/*
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* Key is two 256- or 512-bit coordinates which should match
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* curve size.
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*/
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if ((ctx->key_len != (2 * 256 / 8) &&
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ctx->key_len != (2 * 512 / 8)) ||
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ctx->key_len != ctx->curve->g.ndigits * sizeof(u64) * 2)
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return -ENOPKG;
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ndigits = ctx->key_len / sizeof(u64) / 2;
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ctx->pub_key = ECC_POINT_INIT(ctx->_pubp[0], ctx->_pubp[1], ndigits);
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vli_from_le64(ctx->pub_key.x, ctx->key, ndigits);
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vli_from_le64(ctx->pub_key.y, ctx->key + ndigits * sizeof(u64),
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ndigits);
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if (ecc_is_pubkey_valid_partial(ctx->curve, &ctx->pub_key))
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return -EKEYREJECTED;
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return 0;
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}
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static unsigned int ecrdsa_max_size(struct crypto_akcipher *tfm)
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{
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struct ecrdsa_ctx *ctx = akcipher_tfm_ctx(tfm);
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/*
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* Verify doesn't need any output, so it's just informational
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* for keyctl to determine the key bit size.
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*/
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return ctx->pub_key.ndigits * sizeof(u64);
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}
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static void ecrdsa_exit_tfm(struct crypto_akcipher *tfm)
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{
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}
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static struct akcipher_alg ecrdsa_alg = {
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.verify = ecrdsa_verify,
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.set_pub_key = ecrdsa_set_pub_key,
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.max_size = ecrdsa_max_size,
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.exit = ecrdsa_exit_tfm,
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.base = {
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.cra_name = "ecrdsa",
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.cra_driver_name = "ecrdsa-generic",
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.cra_priority = 100,
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.cra_module = THIS_MODULE,
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.cra_ctxsize = sizeof(struct ecrdsa_ctx),
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},
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};
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static int __init ecrdsa_mod_init(void)
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{
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return crypto_register_akcipher(&ecrdsa_alg);
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}
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static void __exit ecrdsa_mod_fini(void)
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{
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crypto_unregister_akcipher(&ecrdsa_alg);
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}
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module_init(ecrdsa_mod_init);
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module_exit(ecrdsa_mod_fini);
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Vitaly Chikunov <vt@altlinux.org>");
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MODULE_DESCRIPTION("EC-RDSA generic algorithm");
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MODULE_ALIAS_CRYPTO("ecrdsa-generic");
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