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