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 15 struct ecdh_ctx { 16 unsigned int curve_id; 17 unsigned int ndigits; 18 u64 private_key[ECC_MAX_DIGITS]; 19 }; 20 21 static inline struct ecdh_ctx *ecdh_get_ctx(struct crypto_kpp *tfm) 22 { 23 return kpp_tfm_ctx(tfm); 24 } 25 26 static 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 55 static 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 */ 116 free_all: 117 kfree_sensitive(shared_secret); 118 free_pubkey: 119 kfree(public_key); 120 return ret; 121 } 122 123 static 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 } 130 131 static 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 } 140 141 static 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 }; 155 156 static 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 } 165 166 static 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 }; 180 181 static 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 } 190 191 static 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 }; 205 206 static bool ecdh_nist_p192_registered; 207 208 static 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; 225 226 nist_p384_error: 227 crypto_unregister_kpp(&ecdh_nist_p256); 228 229 nist_p256_error: 230 if (ecdh_nist_p192_registered) 231 crypto_unregister_kpp(&ecdh_nist_p192); 232 return ret; 233 } 234 235 static 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 } 242 243 subsys_initcall(ecdh_init); 244 module_exit(ecdh_exit); 245 MODULE_ALIAS_CRYPTO("ecdh"); 246 MODULE_LICENSE("GPL"); 247 MODULE_DESCRIPTION("ECDH generic algorithm"); 248