diff options
Diffstat (limited to '')
| -rw-r--r-- | crypto/ecdsa.c | 376 |
1 files changed, 376 insertions, 0 deletions
diff --git a/crypto/ecdsa.c b/crypto/ecdsa.c new file mode 100644 index 000000000..fbd76498a --- /dev/null +++ b/crypto/ecdsa.c @@ -0,0 +1,376 @@ +// 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 keylen = ndigits * sizeof(u64); + ssize_t diff = vlen - keylen; + const char *d = value; + u8 rs[ECC_MAX_BYTES]; + + 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, which we add + */ + 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 >= keylen) + return -EINVAL; + + if (diff) { + /* leading zeros not given in 'value' */ + memset(rs, 0, -diff); + } + + memcpy(&rs[-diff], d, vlen); + + ecc_swap_digits((u64 *)rs, 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 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 keylen = ctx->curve->g.ndigits * sizeof(u64); + struct ecdsa_signature_ctx sig_ctx = { + .curve = ctx->curve, + }; + u8 rawhash[ECC_MAX_BYTES]; + u64 hash[ECC_MAX_DIGITS]; + unsigned char *buffer; + ssize_t diff; + 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 the hash is shorter then we will add leading zeros to fit to ndigits */ + diff = keylen - req->dst_len; + if (diff >= 0) { + if (diff) + memset(rawhash, 0, diff); + memcpy(&rawhash[diff], buffer + req->src_len, req->dst_len); + } else if (diff < 0) { + /* given hash is longer, we take the left-most bytes */ + memcpy(&rawhash, buffer + req->src_len, keylen); + } + + ecc_swap_digits((u64 *)rawhash, 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 key given the raw uncompressed key data from an X509 + * certificate. The key data contain the concatenated X and Y coordinates of + * the public key. + */ +static int ecdsa_set_pub_key(struct crypto_akcipher *tfm, const void *key, unsigned int keylen) +{ + struct ecc_ctx *ctx = akcipher_tfm_ctx(tfm); + const unsigned char *d = key; + const u64 *digits = (const u64 *)&d[1]; + unsigned int ndigits; + int ret; + + ret = ecdsa_ecc_ctx_reset(ctx); + if (ret < 0) + return ret; + + if (keylen < 1 || (((keylen - 1) >> 1) % sizeof(u64)) != 0) + return -EINVAL; + /* we only accept uncompressed format indicated by '4' */ + if (d[0] != 4) + return -EINVAL; + + keylen--; + ndigits = (keylen >> 1) / sizeof(u64); + if (ndigits != ctx->curve->g.ndigits) + return -EINVAL; + + ecc_swap_digits(digits, ctx->pub_key.x, ndigits); + ecc_swap_digits(&digits[ndigits], 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 ctx->pub_key.ndigits << ECC_DIGITS_TO_BYTES_SHIFT; +} + +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; + + return 0; + +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); +} + +subsys_initcall(ecdsa_init); +module_exit(ecdsa_exit); + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Stefan Berger <stefanb@linux.ibm.com>"); +MODULE_DESCRIPTION("ECDSA generic algorithm"); +MODULE_ALIAS_CRYPTO("ecdsa-generic"); |