crypto/asymmetric_keys/public_key.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /* In-software asymmetric public-key crypto subtype
   3  *
   4  * See Documentation/crypto/asymmetric-keys.rst
   5  *
   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: "fmt
  11 #include <linux/module.h>
  12 #include <linux/export.h>
  13 #include <linux/kernel.h>
  14 #include <linux/slab.h>
  15 #include <linux/seq_file.h>
  16 #include <linux/scatterlist.h>
  17 #include <keys/asymmetric-subtype.h>
  18 #include <crypto/public_key.h>
  19 #include <crypto/akcipher.h>
  20 #include <crypto/sm2.h>
  21 #include <crypto/sm3_base.h>
  22
  23 MODULE_DESCRIPTION("In-software asymmetric public-key subtype");
  24 MODULE_AUTHOR("Red Hat, Inc.");
  25 MODULE_LICENSE("GPL");
  26
  27 /*
  28  * Provide a part of a description of the key for /proc/keys.
  29  */
  30 static 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  */
  42 void public_key_free(struct public_key *key)
  43 {
  44         if (key) {
  45                 kfree(key->key);
  46                 kfree(key->params);
  47                 kfree(key);
  48         }
  49 }
  50 EXPORT_SYMBOL_GPL(public_key_free);
  51
  52 /*
  53  * Destroy a public key algorithm key.
  54  */
  55 static void public_key_destroy(void *payload0, void *payload3)
  56 {
  57         public_key_free(payload0);
  58         public_key_signature_free(payload3);
  59 }
  60
  61 /*
  62  * Determine the crypto algorithm name.
  63  */
  64 static
  65 int software_key_determine_akcipher(const char *encoding,
  66                                     const char *hash_algo,
  67                                     const struct public_key *pkey,
  68                                     char alg_name[CRYPTO_MAX_ALG_NAME])
  69 {
  70         int n;
  71
  72         if (strcmp(encoding, "pkcs1") == 0) {
  73                 /* The data wangled by the RSA algorithm is typically padded
  74                  * and encoded in some manner, such as EMSA-PKCS1-1_5 [RFC3447
  75                  * sec 8.2].
  76                  */
  77                 if (!hash_algo)
  78                         n = snprintf(alg_name, CRYPTO_MAX_ALG_NAME,
  79                                      "pkcs1pad(%s)",
  80                                      pkey->pkey_algo);
  81                 else
  82                         n = snprintf(alg_name, CRYPTO_MAX_ALG_NAME,
  83                                      "pkcs1pad(%s,%s)",
  84                                      pkey->pkey_algo, hash_algo);
  85                 return n >= CRYPTO_MAX_ALG_NAME ? -EINVAL : 0;
  86         }
  87
  88         if (strcmp(encoding, "raw") == 0) {
  89                 strcpy(alg_name, pkey->pkey_algo);
  90                 return 0;
  91         }
  92
  93         return -ENOPKG;
  94 }
  95
  96 static u8 *pkey_pack_u32(u8 *dst, u32 val)
  97 {
  98         memcpy(dst, &val, sizeof(val));
  99         return dst + sizeof(val);
 100 }
 101
 102 /*
 103  * Query information about a key.
 104  */
 105 static int software_key_query(const struct kernel_pkey_params *params,
 106                               struct kernel_pkey_query *info)
 107 {
 108         struct crypto_akcipher *tfm;
 109         struct public_key *pkey = params->key->payload.data[asym_crypto];
 110         char alg_name[CRYPTO_MAX_ALG_NAME];
 111         u8 *key, *ptr;
 112         int ret, len;
 113
 114         ret = software_key_determine_akcipher(params->encoding,
 115                                               params->hash_algo,
 116                                               pkey, alg_name);
 117         if (ret < 0)
 118                 return ret;
 119
 120         tfm = crypto_alloc_akcipher(alg_name, 0, 0);
 121         if (IS_ERR(tfm))
 122                 return PTR_ERR(tfm);
 123
 124         ret = -ENOMEM;
 125         key = kmalloc(pkey->keylen + sizeof(u32) * 2 + pkey->paramlen,
 126                       GFP_KERNEL);
 127         if (!key)
 128                 goto error_free_tfm;
 129         memcpy(key, pkey->key, pkey->keylen);
 130         ptr = key + pkey->keylen;
 131         ptr = pkey_pack_u32(ptr, pkey->algo);
 132         ptr = pkey_pack_u32(ptr, pkey->paramlen);
 133         memcpy(ptr, pkey->params, pkey->paramlen);
 134
 135         if (pkey->key_is_private)
 136                 ret = crypto_akcipher_set_priv_key(tfm, key, pkey->keylen);
 137         else
 138                 ret = crypto_akcipher_set_pub_key(tfm, key, pkey->keylen);
 139         if (ret < 0)
 140                 goto error_free_key;
 141
 142         len = crypto_akcipher_maxsize(tfm);
 143         info->key_size = len * 8;
 144         info->max_data_size = len;
 145         info->max_sig_size = len;
 146         info->max_enc_size = len;
 147         info->max_dec_size = len;
 148         info->supported_ops = (KEYCTL_SUPPORTS_ENCRYPT |
 149                                KEYCTL_SUPPORTS_VERIFY);
 150         if (pkey->key_is_private)
 151                 info->supported_ops |= (KEYCTL_SUPPORTS_DECRYPT |
 152                                         KEYCTL_SUPPORTS_SIGN);
 153         ret = 0;
 154
 155 error_free_key:
 156         kfree(key);
 157 error_free_tfm:
 158         crypto_free_akcipher(tfm);
 159         pr_devel("<==%s() = %d\n", __func__, ret);
 160         return ret;
 161 }
 162
 163 /*
 164  * Do encryption, decryption and signing ops.
 165  */
 166 static int software_key_eds_op(struct kernel_pkey_params *params,
 167                                const void *in, void *out)
 168 {
 169         const struct public_key *pkey = params->key->payload.data[asym_crypto];
 170         struct akcipher_request *req;
 171         struct crypto_akcipher *tfm;
 172         struct crypto_wait cwait;
 173         struct scatterlist in_sg, out_sg;
 174         char alg_name[CRYPTO_MAX_ALG_NAME];
 175         char *key, *ptr;
 176         int ret;
 177
 178         pr_devel("==>%s()\n", __func__);
 179
 180         ret = software_key_determine_akcipher(params->encoding,
 181                                               params->hash_algo,
 182                                               pkey, alg_name);
 183         if (ret < 0)
 184                 return ret;
 185
 186         tfm = crypto_alloc_akcipher(alg_name, 0, 0);
 187         if (IS_ERR(tfm))
 188                 return PTR_ERR(tfm);
 189
 190         ret = -ENOMEM;
 191         req = akcipher_request_alloc(tfm, GFP_KERNEL);
 192         if (!req)
 193                 goto error_free_tfm;
 194
 195         key = kmalloc(pkey->keylen + sizeof(u32) * 2 + pkey->paramlen,
 196                       GFP_KERNEL);
 197         if (!key)
 198                 goto error_free_req;
 199
 200         memcpy(key, pkey->key, pkey->keylen);
 201         ptr = key + pkey->keylen;
 202         ptr = pkey_pack_u32(ptr, pkey->algo);
 203         ptr = pkey_pack_u32(ptr, pkey->paramlen);
 204         memcpy(ptr, pkey->params, pkey->paramlen);
 205
 206         if (pkey->key_is_private)
 207                 ret = crypto_akcipher_set_priv_key(tfm, key, pkey->keylen);
 208         else
 209                 ret = crypto_akcipher_set_pub_key(tfm, key, pkey->keylen);
 210         if (ret)
 211                 goto error_free_key;
 212
 213         sg_init_one(&in_sg, in, params->in_len);
 214         sg_init_one(&out_sg, out, params->out_len);
 215         akcipher_request_set_crypt(req, &in_sg, &out_sg, params->in_len,
 216                                    params->out_len);
 217         crypto_init_wait(&cwait);
 218         akcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG |
 219                                       CRYPTO_TFM_REQ_MAY_SLEEP,
 220                                       crypto_req_done, &cwait);
 221
 222         /* Perform the encryption calculation. */
 223         switch (params->op) {
 224         case kernel_pkey_encrypt:
 225                 ret = crypto_akcipher_encrypt(req);
 226                 break;
 227         case kernel_pkey_decrypt:
 228                 ret = crypto_akcipher_decrypt(req);
 229                 break;
 230         case kernel_pkey_sign:
 231                 ret = crypto_akcipher_sign(req);
 232                 break;
 233         default:
 234                 BUG();
 235         }
 236
 237         ret = crypto_wait_req(ret, &cwait);
 238         if (ret == 0)
 239                 ret = req->dst_len;
 240
 241 error_free_key:
 242         kfree(key);
 243 error_free_req:
 244         akcipher_request_free(req);
 245 error_free_tfm:
 246         crypto_free_akcipher(tfm);
 247         pr_devel("<==%s() = %d\n", __func__, ret);
 248         return ret;
 249 }
 250
 251 #if IS_REACHABLE(CONFIG_CRYPTO_SM2)
 252 static int cert_sig_digest_update(const struct public_key_signature *sig,
 253                                   struct crypto_akcipher *tfm_pkey)
 254 {
 255         struct crypto_shash *tfm;
 256         struct shash_desc *desc;
 257         size_t desc_size;
 258         unsigned char dgst[SM3_DIGEST_SIZE];
 259         int ret;
 260
 261         BUG_ON(!sig->data);
 262
 263         ret = sm2_compute_z_digest(tfm_pkey, SM2_DEFAULT_USERID,
 264                                         SM2_DEFAULT_USERID_LEN, dgst);
 265         if (ret)
 266                 return ret;
 267
 268         tfm = crypto_alloc_shash(sig->hash_algo, 0, 0);
 269         if (IS_ERR(tfm))
 270                 return PTR_ERR(tfm);
 271
 272         desc_size = crypto_shash_descsize(tfm) + sizeof(*desc);
 273         desc = kzalloc(desc_size, GFP_KERNEL);
 274         if (!desc) {
 275                 ret = -ENOMEM;
 276                 goto error_free_tfm;
 277         }
 278
 279         desc->tfm = tfm;
 280
 281         ret = crypto_shash_init(desc);
 282         if (ret < 0)
 283                 goto error_free_desc;
 284
 285         ret = crypto_shash_update(desc, dgst, SM3_DIGEST_SIZE);
 286         if (ret < 0)
 287                 goto error_free_desc;
 288
 289         ret = crypto_shash_finup(desc, sig->data, sig->data_size, sig->digest);
 290
 291 error_free_desc:
 292         kfree(desc);
 293 error_free_tfm:
 294         crypto_free_shash(tfm);
 295         return ret;
 296 }
 297 #else
 298 static inline int cert_sig_digest_update(
 299         const struct public_key_signature *sig,
 300         struct crypto_akcipher *tfm_pkey)
 301 {
 302         return -ENOTSUPP;
 303 }
 304 #endif /* ! IS_REACHABLE(CONFIG_CRYPTO_SM2) */
 305
 306 /*
 307  * Verify a signature using a public key.
 308  */
 309 int public_key_verify_signature(const struct public_key *pkey,
 310                                 const struct public_key_signature *sig)
 311 {
 312         struct crypto_wait cwait;
 313         struct crypto_akcipher *tfm;
 314         struct akcipher_request *req;
 315         struct scatterlist src_sg[2];
 316         char alg_name[CRYPTO_MAX_ALG_NAME];
 317         char *key, *ptr;
 318         int ret;
 319
 320         pr_devel("==>%s()\n", __func__);
 321
 322         BUG_ON(!pkey);
 323         BUG_ON(!sig);
 324         BUG_ON(!sig->s);
 325
 326         ret = software_key_determine_akcipher(sig->encoding,
 327                                               sig->hash_algo,
 328                                               pkey, alg_name);
 329         if (ret < 0)
 330                 return ret;
 331
 332         tfm = crypto_alloc_akcipher(alg_name, 0, 0);
 333         if (IS_ERR(tfm))
 334                 return PTR_ERR(tfm);
 335
 336         ret = -ENOMEM;
 337         req = akcipher_request_alloc(tfm, GFP_KERNEL);
 338         if (!req)
 339                 goto error_free_tfm;
 340
 341         key = kmalloc(pkey->keylen + sizeof(u32) * 2 + pkey->paramlen,
 342                       GFP_KERNEL);
 343         if (!key)
 344                 goto error_free_req;
 345
 346         memcpy(key, pkey->key, pkey->keylen);
 347         ptr = key + pkey->keylen;
 348         ptr = pkey_pack_u32(ptr, pkey->algo);
 349         ptr = pkey_pack_u32(ptr, pkey->paramlen);
 350         memcpy(ptr, pkey->params, pkey->paramlen);
 351
 352         if (pkey->key_is_private)
 353                 ret = crypto_akcipher_set_priv_key(tfm, key, pkey->keylen);
 354         else
 355                 ret = crypto_akcipher_set_pub_key(tfm, key, pkey->keylen);
 356         if (ret)
 357                 goto error_free_key;
 358
 359         if (strcmp(sig->pkey_algo, "sm2") == 0 && sig->data_size) {
 360                 ret = cert_sig_digest_update(sig, tfm);
 361                 if (ret)
 362                         goto error_free_key;
 363         }
 364
 365         sg_init_table(src_sg, 2);
 366         sg_set_buf(&src_sg[0], sig->s, sig->s_size);
 367         sg_set_buf(&src_sg[1], sig->digest, sig->digest_size);
 368         akcipher_request_set_crypt(req, src_sg, NULL, sig->s_size,
 369                                    sig->digest_size);
 370         crypto_init_wait(&cwait);
 371         akcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG |
 372                                       CRYPTO_TFM_REQ_MAY_SLEEP,
 373                                       crypto_req_done, &cwait);
 374         ret = crypto_wait_req(crypto_akcipher_verify(req), &cwait);
 375
 376 error_free_key:
 377         kfree(key);
 378 error_free_req:
 379         akcipher_request_free(req);
 380 error_free_tfm:
 381         crypto_free_akcipher(tfm);
 382         pr_devel("<==%s() = %d\n", __func__, ret);
 383         if (WARN_ON_ONCE(ret > 0))
 384                 ret = -EINVAL;
 385         return ret;
 386 }
 387 EXPORT_SYMBOL_GPL(public_key_verify_signature);
 388
 389 static int public_key_verify_signature_2(const struct key *key,
 390                                          const struct public_key_signature *sig)
 391 {
 392         const struct public_key *pk = key->payload.data[asym_crypto];
 393         return public_key_verify_signature(pk, sig);
 394 }
 395
 396 /*
 397  * Public key algorithm asymmetric key subtype
 398  */
 399 struct asymmetric_key_subtype public_key_subtype = {
 400         .owner                  = THIS_MODULE,
 401         .name                   = "public_key",
 402         .name_len               = sizeof("public_key") - 1,
 403         .describe               = public_key_describe,
 404         .destroy                = public_key_destroy,
 405         .query                  = software_key_query,
 406         .eds_op                 = software_key_eds_op,
 407         .verify_signature       = public_key_verify_signature_2,
 408 };
 409 EXPORT_SYMBOL_GPL(public_key_subtype);