1// SPDX-License-Identifier: GPL-2.0-or-later 2/* ECDH key-agreement protocol 3 * 4 * Copyright (c) 2016, Intel Corporation 5 * Authors: Salvator Benedetto <salvatore.benedetto@intel.com> 6 */ 7 8#include <linux/module.h> 9#include <crypto/internal/ecc.h> 10#include <crypto/internal/kpp.h> 11#include <crypto/kpp.h> 12#include <crypto/ecdh.h> 13#include <linux/scatterlist.h> 14 15struct ecdh_ctx { 16 unsigned int curve_id; 17 unsigned int ndigits; 18 u64 private_key[ECC_MAX_DIGITS]; 19}; 20 21static inline struct ecdh_ctx *ecdh_get_ctx(struct crypto_kpp *tfm) 22{ 23 return kpp_tfm_ctx(tfm); 24} 25 26static int ecdh_set_secret(struct crypto_kpp *tfm, const void *buf, 27 unsigned int len) 28{ 29 struct ecdh_ctx *ctx = ecdh_get_ctx(tfm); 30 struct ecdh params; 31 int ret = 0; 32 33 if (crypto_ecdh_decode_key(buf, len, ¶ms) < 0 || 34 params.key_size > sizeof(u64) * ctx->ndigits) 35 return -EINVAL; 36 37 memset(ctx->private_key, 0, sizeof(ctx->private_key)); 38 39 if (!params.key || !params.key_size) 40 return ecc_gen_privkey(ctx->curve_id, ctx->ndigits, 41 ctx->private_key); 42 43 ecc_digits_from_bytes(params.key, params.key_size, 44 ctx->private_key, ctx->ndigits); 45 46 if (ecc_is_key_valid(ctx->curve_id, ctx->ndigits, 47 ctx->private_key, params.key_size) < 0) { 48 memzero_explicit(ctx->private_key, params.key_size); 49 ret = -EINVAL; 50 } 51 52 return ret; 53} 54 55static int ecdh_compute_value(struct kpp_request *req) 56{ 57 struct crypto_kpp *tfm = crypto_kpp_reqtfm(req); 58 struct ecdh_ctx *ctx = ecdh_get_ctx(tfm); 59 u64 *public_key; 60 u64 *shared_secret = NULL; 61 void *buf; 62 size_t copied, nbytes, public_key_sz; 63 int ret = -ENOMEM; 64 65 nbytes = ctx->ndigits << ECC_DIGITS_TO_BYTES_SHIFT; 66 /* Public part is a point thus it has both coordinates */ 67 public_key_sz = 2 * nbytes; 68 69 public_key = kmalloc(public_key_sz, GFP_KERNEL); 70 if (!public_key) 71 return -ENOMEM; 72 73 if (req->src) { 74 shared_secret = kmalloc(nbytes, GFP_KERNEL); 75 if (!shared_secret) 76 goto free_pubkey; 77 78 /* from here on it's invalid parameters */ 79 ret = -EINVAL; 80 81 /* must have exactly two points to be on the curve */ 82 if (public_key_sz != req->src_len) 83 goto free_all; 84 85 copied = sg_copy_to_buffer(req->src, 86 sg_nents_for_len(req->src, 87 public_key_sz), 88 public_key, public_key_sz); 89 if (copied != public_key_sz) 90 goto free_all; 91 92 ret = crypto_ecdh_shared_secret(ctx->curve_id, ctx->ndigits, 93 ctx->private_key, public_key, 94 shared_secret); 95 96 buf = shared_secret; 97 } else { 98 ret = ecc_make_pub_key(ctx->curve_id, ctx->ndigits, 99 ctx->private_key, public_key); 100 buf = public_key; 101 nbytes = public_key_sz; 102 } 103 104 if (ret < 0) 105 goto free_all; 106 107 /* might want less than we've got */ 108 nbytes = min_t(size_t, nbytes, req->dst_len); 109 copied = sg_copy_from_buffer(req->dst, sg_nents_for_len(req->dst, 110 nbytes), 111 buf, nbytes); 112 if (copied != nbytes) 113 ret = -EINVAL; 114 115 /* fall through */ 116free_all: 117 kfree_sensitive(shared_secret); 118free_pubkey: 119 kfree(public_key); 120 return ret; 121} 122 123static unsigned int ecdh_max_size(struct crypto_kpp *tfm) 124{ 125 struct ecdh_ctx *ctx = ecdh_get_ctx(tfm); 126 127 /* Public key is made of two coordinates, add one to the left shift */ 128 return ctx->ndigits << (ECC_DIGITS_TO_BYTES_SHIFT + 1); 129} 130 131static int ecdh_nist_p192_init_tfm(struct crypto_kpp *tfm) 132{ 133 struct ecdh_ctx *ctx = ecdh_get_ctx(tfm); 134 135 ctx->curve_id = ECC_CURVE_NIST_P192; 136 ctx->ndigits = ECC_CURVE_NIST_P192_DIGITS; 137 138 return 0; 139} 140 141static struct kpp_alg ecdh_nist_p192 = { 142 .set_secret = ecdh_set_secret, 143 .generate_public_key = ecdh_compute_value, 144 .compute_shared_secret = ecdh_compute_value, 145 .max_size = ecdh_max_size, 146 .init = ecdh_nist_p192_init_tfm, 147 .base = { 148 .cra_name = "ecdh-nist-p192", 149 .cra_driver_name = "ecdh-nist-p192-generic", 150 .cra_priority = 100, 151 .cra_module = THIS_MODULE, 152 .cra_ctxsize = sizeof(struct ecdh_ctx), 153 }, 154}; 155 156static int ecdh_nist_p256_init_tfm(struct crypto_kpp *tfm) 157{ 158 struct ecdh_ctx *ctx = ecdh_get_ctx(tfm); 159 160 ctx->curve_id = ECC_CURVE_NIST_P256; 161 ctx->ndigits = ECC_CURVE_NIST_P256_DIGITS; 162 163 return 0; 164} 165 166static struct kpp_alg ecdh_nist_p256 = { 167 .set_secret = ecdh_set_secret, 168 .generate_public_key = ecdh_compute_value, 169 .compute_shared_secret = ecdh_compute_value, 170 .max_size = ecdh_max_size, 171 .init = ecdh_nist_p256_init_tfm, 172 .base = { 173 .cra_name = "ecdh-nist-p256", 174 .cra_driver_name = "ecdh-nist-p256-generic", 175 .cra_priority = 100, 176 .cra_module = THIS_MODULE, 177 .cra_ctxsize = sizeof(struct ecdh_ctx), 178 }, 179}; 180 181static int ecdh_nist_p384_init_tfm(struct crypto_kpp *tfm) 182{ 183 struct ecdh_ctx *ctx = ecdh_get_ctx(tfm); 184 185 ctx->curve_id = ECC_CURVE_NIST_P384; 186 ctx->ndigits = ECC_CURVE_NIST_P384_DIGITS; 187 188 return 0; 189} 190 191static struct kpp_alg ecdh_nist_p384 = { 192 .set_secret = ecdh_set_secret, 193 .generate_public_key = ecdh_compute_value, 194 .compute_shared_secret = ecdh_compute_value, 195 .max_size = ecdh_max_size, 196 .init = ecdh_nist_p384_init_tfm, 197 .base = { 198 .cra_name = "ecdh-nist-p384", 199 .cra_driver_name = "ecdh-nist-p384-generic", 200 .cra_priority = 100, 201 .cra_module = THIS_MODULE, 202 .cra_ctxsize = sizeof(struct ecdh_ctx), 203 }, 204}; 205 206static bool ecdh_nist_p192_registered; 207 208static int __init ecdh_init(void) 209{ 210 int ret; 211 212 /* NIST p192 will fail to register in FIPS mode */ 213 ret = crypto_register_kpp(&ecdh_nist_p192); 214 ecdh_nist_p192_registered = ret == 0; 215 216 ret = crypto_register_kpp(&ecdh_nist_p256); 217 if (ret) 218 goto nist_p256_error; 219 220 ret = crypto_register_kpp(&ecdh_nist_p384); 221 if (ret) 222 goto nist_p384_error; 223 224 return 0; 225 226nist_p384_error: 227 crypto_unregister_kpp(&ecdh_nist_p256); 228 229nist_p256_error: 230 if (ecdh_nist_p192_registered) 231 crypto_unregister_kpp(&ecdh_nist_p192); 232 return ret; 233} 234 235static void __exit ecdh_exit(void) 236{ 237 if (ecdh_nist_p192_registered) 238 crypto_unregister_kpp(&ecdh_nist_p192); 239 crypto_unregister_kpp(&ecdh_nist_p256); 240 crypto_unregister_kpp(&ecdh_nist_p384); 241} 242 243subsys_initcall(ecdh_init); 244module_exit(ecdh_exit); 245MODULE_ALIAS_CRYPTO("ecdh"); 246MODULE_LICENSE("GPL"); 247MODULE_DESCRIPTION("ECDH generic algorithm"); 248