// SPDX-License-Identifier: GPL-2.0+ /* * Copyright (c) 2021 IBM Corporation */ #include #include #include #include #include #include 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; }; 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 crypto_sig *tfm, const void *src, unsigned int slen, const void *digest, unsigned int dlen) { struct ecc_ctx *ctx = crypto_sig_ctx(tfm); size_t bufsize = ctx->curve->g.ndigits * sizeof(u64); const struct ecdsa_raw_sig *sig = src; u64 hash[ECC_MAX_DIGITS]; if (unlikely(!ctx->pub_key_set)) return -EINVAL; if (slen != sizeof(*sig)) return -EINVAL; if (bufsize > dlen) bufsize = dlen; ecc_digits_from_bytes(digest, bufsize, hash, ctx->curve->g.ndigits); return _ecdsa_verify(ctx, hash, sig->r, sig->s); } 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_sig *tfm, const void *key, unsigned int keylen) { struct ecc_ctx *ctx = crypto_sig_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_sig *tfm) { struct ecc_ctx *ctx = crypto_sig_ctx(tfm); ecdsa_ecc_ctx_deinit(ctx); } static unsigned int ecdsa_key_size(struct crypto_sig *tfm) { struct ecc_ctx *ctx = crypto_sig_ctx(tfm); return DIV_ROUND_UP(ctx->curve->nbits, 8); } static unsigned int ecdsa_digest_size(struct crypto_sig *tfm) { /* * ECDSA key sizes are much smaller than RSA, and thus could * operate on (hashed) inputs that are larger than the key size. * E.g. SHA384-hashed input used with secp256r1 based keys. * Return the largest supported hash size (SHA512). */ return SHA512_DIGEST_SIZE; } static int ecdsa_nist_p521_init_tfm(struct crypto_sig *tfm) { struct ecc_ctx *ctx = crypto_sig_ctx(tfm); return ecdsa_ecc_ctx_init(ctx, ECC_CURVE_NIST_P521); } static struct sig_alg ecdsa_nist_p521 = { .verify = ecdsa_verify, .set_pub_key = ecdsa_set_pub_key, .key_size = ecdsa_key_size, .digest_size = ecdsa_digest_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_sig *tfm) { struct ecc_ctx *ctx = crypto_sig_ctx(tfm); return ecdsa_ecc_ctx_init(ctx, ECC_CURVE_NIST_P384); } static struct sig_alg ecdsa_nist_p384 = { .verify = ecdsa_verify, .set_pub_key = ecdsa_set_pub_key, .key_size = ecdsa_key_size, .digest_size = ecdsa_digest_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_sig *tfm) { struct ecc_ctx *ctx = crypto_sig_ctx(tfm); return ecdsa_ecc_ctx_init(ctx, ECC_CURVE_NIST_P256); } static struct sig_alg ecdsa_nist_p256 = { .verify = ecdsa_verify, .set_pub_key = ecdsa_set_pub_key, .key_size = ecdsa_key_size, .digest_size = ecdsa_digest_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_sig *tfm) { struct ecc_ctx *ctx = crypto_sig_ctx(tfm); return ecdsa_ecc_ctx_init(ctx, ECC_CURVE_NIST_P192); } static struct sig_alg ecdsa_nist_p192 = { .verify = ecdsa_verify, .set_pub_key = ecdsa_set_pub_key, .key_size = ecdsa_key_size, .digest_size = ecdsa_digest_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_sig(&ecdsa_nist_p192); ecdsa_nist_p192_registered = ret == 0; ret = crypto_register_sig(&ecdsa_nist_p256); if (ret) goto nist_p256_error; ret = crypto_register_sig(&ecdsa_nist_p384); if (ret) goto nist_p384_error; ret = crypto_register_sig(&ecdsa_nist_p521); if (ret) goto nist_p521_error; ret = crypto_register_template(&ecdsa_x962_tmpl); if (ret) goto x962_tmpl_error; ret = crypto_register_template(&ecdsa_p1363_tmpl); if (ret) goto p1363_tmpl_error; return 0; p1363_tmpl_error: crypto_unregister_template(&ecdsa_x962_tmpl); x962_tmpl_error: crypto_unregister_sig(&ecdsa_nist_p521); nist_p521_error: crypto_unregister_sig(&ecdsa_nist_p384); nist_p384_error: crypto_unregister_sig(&ecdsa_nist_p256); nist_p256_error: if (ecdsa_nist_p192_registered) crypto_unregister_sig(&ecdsa_nist_p192); return ret; } static void __exit ecdsa_exit(void) { crypto_unregister_template(&ecdsa_x962_tmpl); crypto_unregister_template(&ecdsa_p1363_tmpl); if (ecdsa_nist_p192_registered) crypto_unregister_sig(&ecdsa_nist_p192); crypto_unregister_sig(&ecdsa_nist_p256); crypto_unregister_sig(&ecdsa_nist_p384); crypto_unregister_sig(&ecdsa_nist_p521); } subsys_initcall(ecdsa_init); module_exit(ecdsa_exit); MODULE_LICENSE("GPL"); MODULE_AUTHOR("Stefan Berger "); 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");