482 lines · c
1// SPDX-License-Identifier: GPL-2.0-or-later2/* In-software asymmetric public-key crypto subtype3 *4 * See Documentation/crypto/asymmetric-keys.rst5 *6 * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.7 * Written by David Howells (dhowells@redhat.com)8 */9 10#define pr_fmt(fmt) "PKEY: "fmt11#include <crypto/akcipher.h>12#include <crypto/public_key.h>13#include <crypto/sig.h>14#include <keys/asymmetric-subtype.h>15#include <linux/asn1.h>16#include <linux/err.h>17#include <linux/kernel.h>18#include <linux/module.h>19#include <linux/seq_file.h>20#include <linux/slab.h>21#include <linux/string.h>22 23MODULE_DESCRIPTION("In-software asymmetric public-key subtype");24MODULE_AUTHOR("Red Hat, Inc.");25MODULE_LICENSE("GPL");26 27/*28 * Provide a part of a description of the key for /proc/keys.29 */30static void public_key_describe(const struct key *asymmetric_key,31 struct seq_file *m)32{33 struct public_key *key = asymmetric_key->payload.data[asym_crypto];34 35 if (key)36 seq_printf(m, "%s.%s", key->id_type, key->pkey_algo);37}38 39/*40 * Destroy a public key algorithm key.41 */42void public_key_free(struct public_key *key)43{44 if (key) {45 kfree_sensitive(key->key);46 kfree(key->params);47 kfree(key);48 }49}50EXPORT_SYMBOL_GPL(public_key_free);51 52/*53 * Destroy a public key algorithm key.54 */55static void public_key_destroy(void *payload0, void *payload3)56{57 public_key_free(payload0);58 public_key_signature_free(payload3);59}60 61/*62 * Given a public_key, and an encoding and hash_algo to be used for signing63 * and/or verification with that key, determine the name of the corresponding64 * akcipher algorithm. Also check that encoding and hash_algo are allowed.65 */66static int67software_key_determine_akcipher(const struct public_key *pkey,68 const char *encoding, const char *hash_algo,69 char alg_name[CRYPTO_MAX_ALG_NAME], bool *sig,70 enum kernel_pkey_operation op)71{72 int n;73 74 *sig = true;75 76 if (!encoding)77 return -EINVAL;78 79 if (strcmp(pkey->pkey_algo, "rsa") == 0) {80 /*81 * RSA signatures usually use EMSA-PKCS1-1_5 [RFC3447 sec 8.2].82 */83 if (strcmp(encoding, "pkcs1") == 0) {84 *sig = op == kernel_pkey_sign ||85 op == kernel_pkey_verify;86 if (!hash_algo) {87 n = snprintf(alg_name, CRYPTO_MAX_ALG_NAME,88 "pkcs1pad(%s)",89 pkey->pkey_algo);90 } else {91 n = snprintf(alg_name, CRYPTO_MAX_ALG_NAME,92 "pkcs1pad(%s,%s)",93 pkey->pkey_algo, hash_algo);94 }95 return n >= CRYPTO_MAX_ALG_NAME ? -EINVAL : 0;96 }97 if (strcmp(encoding, "raw") != 0)98 return -EINVAL;99 /*100 * Raw RSA cannot differentiate between different hash101 * algorithms.102 */103 if (hash_algo)104 return -EINVAL;105 *sig = false;106 } else if (strncmp(pkey->pkey_algo, "ecdsa", 5) == 0) {107 if (strcmp(encoding, "x962") != 0)108 return -EINVAL;109 /*110 * ECDSA signatures are taken over a raw hash, so they don't111 * differentiate between different hash algorithms. That means112 * that the verifier should hard-code a specific hash algorithm.113 * Unfortunately, in practice ECDSA is used with multiple SHAs,114 * so we have to allow all of them and not just one.115 */116 if (!hash_algo)117 return -EINVAL;118 if (strcmp(hash_algo, "sha1") != 0 &&119 strcmp(hash_algo, "sha224") != 0 &&120 strcmp(hash_algo, "sha256") != 0 &&121 strcmp(hash_algo, "sha384") != 0 &&122 strcmp(hash_algo, "sha512") != 0 &&123 strcmp(hash_algo, "sha3-256") != 0 &&124 strcmp(hash_algo, "sha3-384") != 0 &&125 strcmp(hash_algo, "sha3-512") != 0)126 return -EINVAL;127 } else if (strcmp(pkey->pkey_algo, "ecrdsa") == 0) {128 if (strcmp(encoding, "raw") != 0)129 return -EINVAL;130 if (!hash_algo)131 return -EINVAL;132 if (strcmp(hash_algo, "streebog256") != 0 &&133 strcmp(hash_algo, "streebog512") != 0)134 return -EINVAL;135 } else {136 /* Unknown public key algorithm */137 return -ENOPKG;138 }139 if (strscpy(alg_name, pkey->pkey_algo, CRYPTO_MAX_ALG_NAME) < 0)140 return -EINVAL;141 return 0;142}143 144static u8 *pkey_pack_u32(u8 *dst, u32 val)145{146 memcpy(dst, &val, sizeof(val));147 return dst + sizeof(val);148}149 150/*151 * Query information about a key.152 */153static int software_key_query(const struct kernel_pkey_params *params,154 struct kernel_pkey_query *info)155{156 struct crypto_akcipher *tfm;157 struct public_key *pkey = params->key->payload.data[asym_crypto];158 char alg_name[CRYPTO_MAX_ALG_NAME];159 struct crypto_sig *sig;160 u8 *key, *ptr;161 int ret, len;162 bool issig;163 164 ret = software_key_determine_akcipher(pkey, params->encoding,165 params->hash_algo, alg_name,166 &issig, kernel_pkey_sign);167 if (ret < 0)168 return ret;169 170 key = kmalloc(pkey->keylen + sizeof(u32) * 2 + pkey->paramlen,171 GFP_KERNEL);172 if (!key)173 return -ENOMEM;174 175 memcpy(key, pkey->key, pkey->keylen);176 ptr = key + pkey->keylen;177 ptr = pkey_pack_u32(ptr, pkey->algo);178 ptr = pkey_pack_u32(ptr, pkey->paramlen);179 memcpy(ptr, pkey->params, pkey->paramlen);180 181 if (issig) {182 sig = crypto_alloc_sig(alg_name, 0, 0);183 if (IS_ERR(sig)) {184 ret = PTR_ERR(sig);185 goto error_free_key;186 }187 188 if (pkey->key_is_private)189 ret = crypto_sig_set_privkey(sig, key, pkey->keylen);190 else191 ret = crypto_sig_set_pubkey(sig, key, pkey->keylen);192 if (ret < 0)193 goto error_free_tfm;194 195 len = crypto_sig_maxsize(sig);196 197 info->supported_ops = KEYCTL_SUPPORTS_VERIFY;198 if (pkey->key_is_private)199 info->supported_ops |= KEYCTL_SUPPORTS_SIGN;200 201 if (strcmp(params->encoding, "pkcs1") == 0) {202 info->supported_ops |= KEYCTL_SUPPORTS_ENCRYPT;203 if (pkey->key_is_private)204 info->supported_ops |= KEYCTL_SUPPORTS_DECRYPT;205 }206 } else {207 tfm = crypto_alloc_akcipher(alg_name, 0, 0);208 if (IS_ERR(tfm)) {209 ret = PTR_ERR(tfm);210 goto error_free_key;211 }212 213 if (pkey->key_is_private)214 ret = crypto_akcipher_set_priv_key(tfm, key, pkey->keylen);215 else216 ret = crypto_akcipher_set_pub_key(tfm, key, pkey->keylen);217 if (ret < 0)218 goto error_free_tfm;219 220 len = crypto_akcipher_maxsize(tfm);221 222 info->supported_ops = KEYCTL_SUPPORTS_ENCRYPT;223 if (pkey->key_is_private)224 info->supported_ops |= KEYCTL_SUPPORTS_DECRYPT;225 }226 227 info->key_size = len * 8;228 229 if (strncmp(pkey->pkey_algo, "ecdsa", 5) == 0) {230 int slen = len;231 /*232 * ECDSA key sizes are much smaller than RSA, and thus could233 * operate on (hashed) inputs that are larger than key size.234 * For example SHA384-hashed input used with secp256r1235 * based keys. Set max_data_size to be at least as large as236 * the largest supported hash size (SHA512)237 */238 info->max_data_size = 64;239 240 /*241 * Verify takes ECDSA-Sig (described in RFC 5480) as input,242 * which is actually 2 'key_size'-bit integers encoded in243 * ASN.1. Account for the ASN.1 encoding overhead here.244 *245 * NIST P192/256/384 may prepend a '0' to a coordinate to246 * indicate a positive integer. NIST P521 never needs it.247 */248 if (strcmp(pkey->pkey_algo, "ecdsa-nist-p521") != 0)249 slen += 1;250 /* Length of encoding the x & y coordinates */251 slen = 2 * (slen + 2);252 /*253 * If coordinate encoding takes at least 128 bytes then an254 * additional byte for length encoding is needed.255 */256 info->max_sig_size = 1 + (slen >= 128) + 1 + slen;257 } else {258 info->max_data_size = len;259 info->max_sig_size = len;260 }261 262 info->max_enc_size = len;263 info->max_dec_size = len;264 265 ret = 0;266 267error_free_tfm:268 if (issig)269 crypto_free_sig(sig);270 else271 crypto_free_akcipher(tfm);272error_free_key:273 kfree_sensitive(key);274 pr_devel("<==%s() = %d\n", __func__, ret);275 return ret;276}277 278/*279 * Do encryption, decryption and signing ops.280 */281static int software_key_eds_op(struct kernel_pkey_params *params,282 const void *in, void *out)283{284 const struct public_key *pkey = params->key->payload.data[asym_crypto];285 char alg_name[CRYPTO_MAX_ALG_NAME];286 struct crypto_akcipher *tfm;287 struct crypto_sig *sig;288 char *key, *ptr;289 bool issig;290 int ksz;291 int ret;292 293 pr_devel("==>%s()\n", __func__);294 295 ret = software_key_determine_akcipher(pkey, params->encoding,296 params->hash_algo, alg_name,297 &issig, params->op);298 if (ret < 0)299 return ret;300 301 key = kmalloc(pkey->keylen + sizeof(u32) * 2 + pkey->paramlen,302 GFP_KERNEL);303 if (!key)304 return -ENOMEM;305 306 memcpy(key, pkey->key, pkey->keylen);307 ptr = key + pkey->keylen;308 ptr = pkey_pack_u32(ptr, pkey->algo);309 ptr = pkey_pack_u32(ptr, pkey->paramlen);310 memcpy(ptr, pkey->params, pkey->paramlen);311 312 if (issig) {313 sig = crypto_alloc_sig(alg_name, 0, 0);314 if (IS_ERR(sig)) {315 ret = PTR_ERR(sig);316 goto error_free_key;317 }318 319 if (pkey->key_is_private)320 ret = crypto_sig_set_privkey(sig, key, pkey->keylen);321 else322 ret = crypto_sig_set_pubkey(sig, key, pkey->keylen);323 if (ret)324 goto error_free_tfm;325 326 ksz = crypto_sig_maxsize(sig);327 } else {328 tfm = crypto_alloc_akcipher(alg_name, 0, 0);329 if (IS_ERR(tfm)) {330 ret = PTR_ERR(tfm);331 goto error_free_key;332 }333 334 if (pkey->key_is_private)335 ret = crypto_akcipher_set_priv_key(tfm, key, pkey->keylen);336 else337 ret = crypto_akcipher_set_pub_key(tfm, key, pkey->keylen);338 if (ret)339 goto error_free_tfm;340 341 ksz = crypto_akcipher_maxsize(tfm);342 }343 344 ret = -EINVAL;345 346 /* Perform the encryption calculation. */347 switch (params->op) {348 case kernel_pkey_encrypt:349 if (issig)350 break;351 ret = crypto_akcipher_sync_encrypt(tfm, in, params->in_len,352 out, params->out_len);353 break;354 case kernel_pkey_decrypt:355 if (issig)356 break;357 ret = crypto_akcipher_sync_decrypt(tfm, in, params->in_len,358 out, params->out_len);359 break;360 case kernel_pkey_sign:361 if (!issig)362 break;363 ret = crypto_sig_sign(sig, in, params->in_len,364 out, params->out_len);365 break;366 default:367 BUG();368 }369 370 if (ret == 0)371 ret = ksz;372 373error_free_tfm:374 if (issig)375 crypto_free_sig(sig);376 else377 crypto_free_akcipher(tfm);378error_free_key:379 kfree_sensitive(key);380 pr_devel("<==%s() = %d\n", __func__, ret);381 return ret;382}383 384/*385 * Verify a signature using a public key.386 */387int public_key_verify_signature(const struct public_key *pkey,388 const struct public_key_signature *sig)389{390 char alg_name[CRYPTO_MAX_ALG_NAME];391 struct crypto_sig *tfm;392 char *key, *ptr;393 bool issig;394 int ret;395 396 pr_devel("==>%s()\n", __func__);397 398 BUG_ON(!pkey);399 BUG_ON(!sig);400 BUG_ON(!sig->s);401 402 /*403 * If the signature specifies a public key algorithm, it *must* match404 * the key's actual public key algorithm.405 *406 * Small exception: ECDSA signatures don't specify the curve, but ECDSA407 * keys do. So the strings can mismatch slightly in that case:408 * "ecdsa-nist-*" for the key, but "ecdsa" for the signature.409 */410 if (sig->pkey_algo) {411 if (strcmp(pkey->pkey_algo, sig->pkey_algo) != 0 &&412 (strncmp(pkey->pkey_algo, "ecdsa-", 6) != 0 ||413 strcmp(sig->pkey_algo, "ecdsa") != 0))414 return -EKEYREJECTED;415 }416 417 ret = software_key_determine_akcipher(pkey, sig->encoding,418 sig->hash_algo, alg_name,419 &issig, kernel_pkey_verify);420 if (ret < 0)421 return ret;422 423 tfm = crypto_alloc_sig(alg_name, 0, 0);424 if (IS_ERR(tfm))425 return PTR_ERR(tfm);426 427 key = kmalloc(pkey->keylen + sizeof(u32) * 2 + pkey->paramlen,428 GFP_KERNEL);429 if (!key) {430 ret = -ENOMEM;431 goto error_free_tfm;432 }433 434 memcpy(key, pkey->key, pkey->keylen);435 ptr = key + pkey->keylen;436 ptr = pkey_pack_u32(ptr, pkey->algo);437 ptr = pkey_pack_u32(ptr, pkey->paramlen);438 memcpy(ptr, pkey->params, pkey->paramlen);439 440 if (pkey->key_is_private)441 ret = crypto_sig_set_privkey(tfm, key, pkey->keylen);442 else443 ret = crypto_sig_set_pubkey(tfm, key, pkey->keylen);444 if (ret)445 goto error_free_key;446 447 ret = crypto_sig_verify(tfm, sig->s, sig->s_size,448 sig->digest, sig->digest_size);449 450error_free_key:451 kfree_sensitive(key);452error_free_tfm:453 crypto_free_sig(tfm);454 pr_devel("<==%s() = %d\n", __func__, ret);455 if (WARN_ON_ONCE(ret > 0))456 ret = -EINVAL;457 return ret;458}459EXPORT_SYMBOL_GPL(public_key_verify_signature);460 461static int public_key_verify_signature_2(const struct key *key,462 const struct public_key_signature *sig)463{464 const struct public_key *pk = key->payload.data[asym_crypto];465 return public_key_verify_signature(pk, sig);466}467 468/*469 * Public key algorithm asymmetric key subtype470 */471struct asymmetric_key_subtype public_key_subtype = {472 .owner = THIS_MODULE,473 .name = "public_key",474 .name_len = sizeof("public_key") - 1,475 .describe = public_key_describe,476 .destroy = public_key_destroy,477 .query = software_key_query,478 .eds_op = software_key_eds_op,479 .verify_signature = public_key_verify_signature_2,480};481EXPORT_SYMBOL_GPL(public_key_subtype);482