Loading...
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 | // SPDX-License-Identifier: GPL-2.0-or-later /* ECDH key-agreement protocol * * Copyright (c) 2016, Intel Corporation * Authors: Salvator Benedetto <salvatore.benedetto@intel.com> */ #include <linux/module.h> #include <crypto/internal/kpp.h> #include <crypto/kpp.h> #include <crypto/ecdh.h> #include <linux/scatterlist.h> #include "ecc.h" struct ecdh_ctx { unsigned int curve_id; unsigned int ndigits; u64 private_key[ECC_MAX_DIGITS]; }; static inline struct ecdh_ctx *ecdh_get_ctx(struct crypto_kpp *tfm) { return kpp_tfm_ctx(tfm); } static unsigned int ecdh_supported_curve(unsigned int curve_id) { switch (curve_id) { case ECC_CURVE_NIST_P192: return ECC_CURVE_NIST_P192_DIGITS; case ECC_CURVE_NIST_P256: return ECC_CURVE_NIST_P256_DIGITS; default: return 0; } } static int ecdh_set_secret(struct crypto_kpp *tfm, const void *buf, unsigned int len) { struct ecdh_ctx *ctx = ecdh_get_ctx(tfm); struct ecdh params; unsigned int ndigits; if (crypto_ecdh_decode_key(buf, len, ¶ms) < 0) return -EINVAL; ndigits = ecdh_supported_curve(params.curve_id); if (!ndigits) return -EINVAL; ctx->curve_id = params.curve_id; ctx->ndigits = ndigits; if (!params.key || !params.key_size) return ecc_gen_privkey(ctx->curve_id, ctx->ndigits, ctx->private_key); if (ecc_is_key_valid(ctx->curve_id, ctx->ndigits, (const u64 *)params.key, params.key_size) < 0) return -EINVAL; memcpy(ctx->private_key, params.key, params.key_size); return 0; } static int ecdh_compute_value(struct kpp_request *req) { struct crypto_kpp *tfm = crypto_kpp_reqtfm(req); struct ecdh_ctx *ctx = ecdh_get_ctx(tfm); u64 *public_key; u64 *shared_secret = NULL; void *buf; size_t copied, nbytes, public_key_sz; int ret = -ENOMEM; nbytes = ctx->ndigits << ECC_DIGITS_TO_BYTES_SHIFT; /* Public part is a point thus it has both coordinates */ public_key_sz = 2 * nbytes; public_key = kmalloc(public_key_sz, GFP_KERNEL); if (!public_key) return -ENOMEM; if (req->src) { shared_secret = kmalloc(nbytes, GFP_KERNEL); if (!shared_secret) goto free_pubkey; /* from here on it's invalid parameters */ ret = -EINVAL; /* must have exactly two points to be on the curve */ if (public_key_sz != req->src_len) goto free_all; copied = sg_copy_to_buffer(req->src, sg_nents_for_len(req->src, public_key_sz), public_key, public_key_sz); if (copied != public_key_sz) goto free_all; ret = crypto_ecdh_shared_secret(ctx->curve_id, ctx->ndigits, ctx->private_key, public_key, shared_secret); buf = shared_secret; } else { ret = ecc_make_pub_key(ctx->curve_id, ctx->ndigits, ctx->private_key, public_key); buf = public_key; nbytes = public_key_sz; } if (ret < 0) goto free_all; /* might want less than we've got */ nbytes = min_t(size_t, nbytes, req->dst_len); copied = sg_copy_from_buffer(req->dst, sg_nents_for_len(req->dst, nbytes), buf, nbytes); if (copied != nbytes) ret = -EINVAL; /* fall through */ free_all: kzfree(shared_secret); free_pubkey: kfree(public_key); return ret; } static unsigned int ecdh_max_size(struct crypto_kpp *tfm) { struct ecdh_ctx *ctx = ecdh_get_ctx(tfm); /* Public key is made of two coordinates, add one to the left shift */ return ctx->ndigits << (ECC_DIGITS_TO_BYTES_SHIFT + 1); } static struct kpp_alg ecdh = { .set_secret = ecdh_set_secret, .generate_public_key = ecdh_compute_value, .compute_shared_secret = ecdh_compute_value, .max_size = ecdh_max_size, .base = { .cra_name = "ecdh", .cra_driver_name = "ecdh-generic", .cra_priority = 100, .cra_module = THIS_MODULE, .cra_ctxsize = sizeof(struct ecdh_ctx), }, }; static int ecdh_init(void) { return crypto_register_kpp(&ecdh); } static void ecdh_exit(void) { crypto_unregister_kpp(&ecdh); } subsys_initcall(ecdh_init); module_exit(ecdh_exit); MODULE_ALIAS_CRYPTO("ecdh"); MODULE_LICENSE("GPL"); MODULE_DESCRIPTION("ECDH generic algorithm"); |