// SPDX-License-Identifier: GPL-2.0+
/*
* Copyright (c) 2021 IBM Corporation
*/
#include <linux/module.h>
#include <crypto/internal/akcipher.h>
#include <crypto/internal/ecc.h>
#include <crypto/akcipher.h>
#include <crypto/ecdh.h>
#include <linux/asn1_decoder.h>
#include <linux/scatterlist.h>
#include "ecdsasignature.asn1.h"
struct ecc_ctx {
unsigned int curve_id;
const struct ecc_curve *curve;
bool pub_key_set;
u64 x[ECC_MAX_DIGITS]; /* pub key x and y coordinates */
u64 y[ECC_MAX_DIGITS];
struct ecc_point pub_key;
};
struct ecdsa_signature_ctx {
const struct ecc_curve *curve;
u64 r[ECC_MAX_DIGITS];
u64 s[ECC_MAX_DIGITS];
};
/*
* Get the r and s components of a signature from the X509 certificate.
*/
static int ecdsa_get_signature_rs(u64 *dest, size_t hdrlen, unsigned char tag,
const void *value, size_t vlen, unsigned int ndigits)
{
size_t bufsize = ndigits * sizeof(u64);
ssize_t diff = vlen - bufsize;
const char *d = value;
if (!value || !vlen)
return -EINVAL;
/* diff = 0: 'value' has exacly the right size
* diff > 0: 'value' has too many bytes; one leading zero is allowed that
* makes the value a positive integer; error on more
* diff < 0: 'value' is missing leading zeros
*/
if (diff > 0) {
/* skip over leading zeros that make 'value' a positive int */
if (*d == 0) {
vlen -= 1;
diff--;
d++;
}
if (diff)
return -EINVAL;
}
if (-diff >= bufsize)
return -EINVAL;
ecc_digits_from_bytes(d, vlen, dest, ndigits);
return 0;
}
int ecdsa_get_signature_r(void *context, size_t hdrlen, unsigned char tag,
const void *value, size_t vlen)
{
struct ecdsa_signature_ctx *sig = context;
return ecdsa_get_signature_rs(sig->r, hdrlen, tag, value, vlen,
sig->curve->g.ndigits);
}
int ecdsa_get_signature_s(void *context, size_t hdrlen, unsigned char tag,
const void *value, size_t vlen)
{
struct ecdsa_signature_ctx *sig = context;
return ecdsa_get_signature_rs(sig->s, hdrlen, tag, value, vlen,
sig->curve->g.ndigits);
}
static int _ecdsa_verify(struct ecc_ctx *ctx, const u64 *hash, const u64 *r, const u64 *s)
{
const struct ecc_curve *curve = ctx->curve;
unsigned int ndigits = curve->g.ndigits;
u64 s1[ECC_MAX_DIGITS];
u64 u1[ECC_MAX_DIGITS];
u64 u2[ECC_MAX_DIGITS];
u64 x1[ECC_MAX_DIGITS];
u64 y1[ECC_MAX_DIGITS];
struct ecc_point res = ECC_POINT_INIT(x1, y1, ndigits);
/* 0 < r < n and 0 < s < n */
if (vli_is_zero(r, ndigits) || vli_cmp(r, curve->n, ndigits) >= 0 ||
vli_is_zero(s, ndigits) || vli_cmp(s, curve->n, ndigits) >= 0)
return -EBADMSG;
/* hash is given */
pr_devel("hash : %016llx %016llx ... %016llx\n",
hash[ndigits - 1], hash[ndigits - 2], hash[0]);
/* s1 = (s^-1) mod n */
vli_mod_inv(s1, s, curve->n, ndigits);
/* u1 = (hash * s1) mod n */
vli_mod_mult_slow(u1, hash, s1, curve->n, ndigits);
/* u2 = (r * s1) mod n */
vli_mod_mult_slow(u2, r, s1, curve->n, ndigits);
/* res = u1*G + u2 * pub_key */
ecc_point_mult_shamir(&res, u1, &curve->g, u2, &ctx->pub_key, curve);
/* res.x = res.x mod n (if res.x > order) */
if (unlikely(vli_cmp(res.x, curve->n, ndigits) == 1))
/* faster alternative for NIST p521, p384, p256 & p192 */
vli_sub(res.x, res.x, curve->n, ndigits);
if (!vli_cmp(res.x, r, ndigits))
return 0;
return -EKEYREJECTED;
}
/*
* Verify an ECDSA signature.
*/
static int ecdsa_verify(struct akcipher_request *req)
{
struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
struct ecc_ctx *ctx = akcipher_tfm_ctx(tfm);
size_t bufsize = ctx->curve->g.ndigits * sizeof(u64);
struct ecdsa_signature_ctx sig_ctx = {
.curve = ctx->curve,
};
u64 hash[ECC_MAX_DIGITS];
unsigned char *buffer;
int ret;
if (unlikely(!ctx->pub_key_set))
return -EINVAL;
buffer = kmalloc(req->src_len + req->dst_len, GFP_KERNEL);
if (!buffer)
return -ENOMEM;
sg_pcopy_to_buffer(req->src,
sg_nents_for_len(req->src, req->src_len + req->dst_len),
buffer, req->src_len + req->dst_len, 0);
ret = asn1_ber_decoder(&ecdsasignature_decoder, &sig_ctx,
buffer, req->src_len);
if (ret < 0)
goto error;
if (bufsize > req->dst_len)
bufsize = req->dst_len;
ecc_digits_from_bytes(buffer + req->src_len, bufsize,
hash, ctx->curve->g.ndigits);
ret = _ecdsa_verify(ctx, hash, sig_ctx.r, sig_ctx.s);
error:
kfree(buffer);
return ret;
}
static int ecdsa_ecc_ctx_init(struct ecc_ctx *ctx, unsigned int curve_id)
{
ctx->curve_id = curve_id;
ctx->curve = ecc_get_curve(curve_id);
if (!ctx->curve)
return -EINVAL;
return 0;
}
static void ecdsa_ecc_ctx_deinit(struct ecc_ctx *ctx)
{
ctx->pub_key_set = false;
}
static int ecdsa_ecc_ctx_reset(struct ecc_ctx *ctx)
{
unsigned int curve_id = ctx->curve_id;
int ret;
ecdsa_ecc_ctx_deinit(ctx);
ret = ecdsa_ecc_ctx_init(ctx, curve_id);
if (ret == 0)
ctx->pub_key = ECC_POINT_INIT(ctx->x, ctx->y,
ctx->curve->g.ndigits);
return ret;
}
/*
* Set the public ECC key as defined by RFC5480 section 2.2 "Subject Public
* Key". Only the uncompressed format is supported.
*/
static int ecdsa_set_pub_key(struct crypto_akcipher *tfm, const void *key, unsigned int keylen)
{
struct ecc_ctx *ctx = akcipher_tfm_ctx(tfm);
unsigned int digitlen, ndigits;
const unsigned char *d = key;
int ret;
ret = ecdsa_ecc_ctx_reset(ctx);
if (ret < 0)
return ret;
if (keylen < 1 || ((keylen - 1) & 1) != 0)
return -EINVAL;
/* we only accept uncompressed format indicated by '4' */
if (d[0] != 4)
return -EINVAL;
keylen--;
digitlen = keylen >> 1;
ndigits = DIV_ROUND_UP(digitlen, sizeof(u64));
if (ndigits != ctx->curve->g.ndigits)
return -EINVAL;
d++;
ecc_digits_from_bytes(d, digitlen, ctx->pub_key.x, ndigits);
ecc_digits_from_bytes(&d[digitlen], digitlen, ctx->pub_key.y, ndigits);
ret = ecc_is_pubkey_valid_full(ctx->curve, &ctx->pub_key);
ctx->pub_key_set = ret == 0;
return ret;
}
static void ecdsa_exit_tfm(struct crypto_akcipher *tfm)
{
struct ecc_ctx *ctx = akcipher_tfm_ctx(tfm);
ecdsa_ecc_ctx_deinit(ctx);
}
static unsigned int ecdsa_max_size(struct crypto_akcipher *tfm)
{
struct ecc_ctx *ctx = akcipher_tfm_ctx(tfm);
return DIV_ROUND_UP(ctx->curve->nbits, 8);
}
static int ecdsa_nist_p521_init_tfm(struct crypto_akcipher *tfm)
{
struct ecc_ctx *ctx = akcipher_tfm_ctx(tfm);
return ecdsa_ecc_ctx_init(ctx, ECC_CURVE_NIST_P521);
}
static struct akcipher_alg ecdsa_nist_p521 = {
.verify = ecdsa_verify,
.set_pub_key = ecdsa_set_pub_key,
.max_size = ecdsa_max_size,
.init = ecdsa_nist_p521_init_tfm,
.exit = ecdsa_exit_tfm,
.base = {
.cra_name = "ecdsa-nist-p521",
.cra_driver_name = "ecdsa-nist-p521-generic",
.cra_priority = 100,
.cra_module = THIS_MODULE,
.cra_ctxsize = sizeof(struct ecc_ctx),
},
};
static int ecdsa_nist_p384_init_tfm(struct crypto_akcipher *tfm)
{
struct ecc_ctx *ctx = akcipher_tfm_ctx(tfm);
return ecdsa_ecc_ctx_init(ctx, ECC_CURVE_NIST_P384);
}
static struct akcipher_alg ecdsa_nist_p384 = {
.verify = ecdsa_verify,
.set_pub_key = ecdsa_set_pub_key,
.max_size = ecdsa_max_size,
.init = ecdsa_nist_p384_init_tfm,
.exit = ecdsa_exit_tfm,
.base = {
.cra_name = "ecdsa-nist-p384",
.cra_driver_name = "ecdsa-nist-p384-generic",
.cra_priority = 100,
.cra_module = THIS_MODULE,
.cra_ctxsize = sizeof(struct ecc_ctx),
},
};
static int ecdsa_nist_p256_init_tfm(struct crypto_akcipher *tfm)
{
struct ecc_ctx *ctx = akcipher_tfm_ctx(tfm);
return ecdsa_ecc_ctx_init(ctx, ECC_CURVE_NIST_P256);
}
static struct akcipher_alg ecdsa_nist_p256 = {
.verify = ecdsa_verify,
.set_pub_key = ecdsa_set_pub_key,
.max_size = ecdsa_max_size,
.init = ecdsa_nist_p256_init_tfm,
.exit = ecdsa_exit_tfm,
.base = {
.cra_name = "ecdsa-nist-p256",
.cra_driver_name = "ecdsa-nist-p256-generic",
.cra_priority = 100,
.cra_module = THIS_MODULE,
.cra_ctxsize = sizeof(struct ecc_ctx),
},
};
static int ecdsa_nist_p192_init_tfm(struct crypto_akcipher *tfm)
{
struct ecc_ctx *ctx = akcipher_tfm_ctx(tfm);
return ecdsa_ecc_ctx_init(ctx, ECC_CURVE_NIST_P192);
}
static struct akcipher_alg ecdsa_nist_p192 = {
.verify = ecdsa_verify,
.set_pub_key = ecdsa_set_pub_key,
.max_size = ecdsa_max_size,
.init = ecdsa_nist_p192_init_tfm,
.exit = ecdsa_exit_tfm,
.base = {
.cra_name = "ecdsa-nist-p192",
.cra_driver_name = "ecdsa-nist-p192-generic",
.cra_priority = 100,
.cra_module = THIS_MODULE,
.cra_ctxsize = sizeof(struct ecc_ctx),
},
};
static bool ecdsa_nist_p192_registered;
static int __init ecdsa_init(void)
{
int ret;
/* NIST p192 may not be available in FIPS mode */
ret = crypto_register_akcipher(&ecdsa_nist_p192);
ecdsa_nist_p192_registered = ret == 0;
ret = crypto_register_akcipher(&ecdsa_nist_p256);
if (ret)
goto nist_p256_error;
ret = crypto_register_akcipher(&ecdsa_nist_p384);
if (ret)
goto nist_p384_error;
ret = crypto_register_akcipher(&ecdsa_nist_p521);
if (ret)
goto nist_p521_error;
return 0;
nist_p521_error:
crypto_unregister_akcipher(&ecdsa_nist_p384);
nist_p384_error:
crypto_unregister_akcipher(&ecdsa_nist_p256);
nist_p256_error:
if (ecdsa_nist_p192_registered)
crypto_unregister_akcipher(&ecdsa_nist_p192);
return ret;
}
static void __exit ecdsa_exit(void)
{
if (ecdsa_nist_p192_registered)
crypto_unregister_akcipher(&ecdsa_nist_p192);
crypto_unregister_akcipher(&ecdsa_nist_p256);
crypto_unregister_akcipher(&ecdsa_nist_p384);
crypto_unregister_akcipher(&ecdsa_nist_p521);
}
subsys_initcall(ecdsa_init);
module_exit(ecdsa_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Stefan Berger <[email protected]>");
MODULE_DESCRIPTION("ECDSA generic algorithm");
MODULE_ALIAS_CRYPTO("ecdsa-nist-p192");
MODULE_ALIAS_CRYPTO("ecdsa-nist-p256");
MODULE_ALIAS_CRYPTO("ecdsa-nist-p384");
MODULE_ALIAS_CRYPTO("ecdsa-nist-p521");
MODULE_ALIAS_CRYPTO("ecdsa-generic");
Codebase Browser
linux