crypto/asymmetric_keys/asym

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This source file includes following definitions.
tpm_loadkey2
tpm_flushspecific
tpm_unbind
tpm_sign
asym_tpm_describe
asym_tpm_destroy
definite_length
encode_tag_length
derive_pub_key
determine_akcipher
tpm_key_query
tpm_key_encrypt
tpm_key_decrypt
lookup_asn1
tpm_key_sign
tpm_key_eds_op
tpm_key_verify_signature
extract_key_parameters
tpm_key_create
   1 // SPDX-License-Identifier: GPL-2.0
   2 #define pr_fmt(fmt) "ASYM-TPM: "fmt
   3 #include <linux/slab.h>
   4 #include <linux/module.h>
   5 #include <linux/export.h>
   6 #include <linux/kernel.h>
   7 #include <linux/seq_file.h>
   8 #include <linux/scatterlist.h>
   9 #include <linux/tpm.h>
  10 #include <linux/tpm_command.h>
  11 #include <crypto/akcipher.h>
  12 #include <crypto/hash.h>
  13 #include <crypto/sha.h>
  14 #include <asm/unaligned.h>
  15 #include <keys/asymmetric-subtype.h>
  16 #include <keys/trusted.h>
  17 #include <crypto/asym_tpm_subtype.h>
  18 #include <crypto/public_key.h>
  19 
  20 #define TPM_ORD_FLUSHSPECIFIC   186
  21 #define TPM_ORD_LOADKEY2        65
  22 #define TPM_ORD_UNBIND          30
  23 #define TPM_ORD_SIGN            60
  24 #define TPM_LOADKEY2_SIZE               59
  25 #define TPM_FLUSHSPECIFIC_SIZE          18
  26 #define TPM_UNBIND_SIZE                 63
  27 #define TPM_SIGN_SIZE                   63
  28 
  29 #define TPM_RT_KEY                      0x00000001
  30 
  31 /*
  32  * Load a TPM key from the blob provided by userspace
  33  */
  34 static int tpm_loadkey2(struct tpm_buf *tb,
  35                         uint32_t keyhandle, unsigned char *keyauth,
  36                         const unsigned char *keyblob, int keybloblen,
  37                         uint32_t *newhandle)
  38 {
  39         unsigned char nonceodd[TPM_NONCE_SIZE];
  40         unsigned char enonce[TPM_NONCE_SIZE];
  41         unsigned char authdata[SHA1_DIGEST_SIZE];
  42         uint32_t authhandle = 0;
  43         unsigned char cont = 0;
  44         uint32_t ordinal;
  45         int ret;
  46 
  47         ordinal = htonl(TPM_ORD_LOADKEY2);
  48 
  49         /* session for loading the key */
  50         ret = oiap(tb, &authhandle, enonce);
  51         if (ret < 0) {
  52                 pr_info("oiap failed (%d)\n", ret);
  53                 return ret;
  54         }
  55 
  56         /* generate odd nonce */
  57         ret = tpm_get_random(NULL, nonceodd, TPM_NONCE_SIZE);
  58         if (ret < 0) {
  59                 pr_info("tpm_get_random failed (%d)\n", ret);
  60                 return ret;
  61         }
  62 
  63         /* calculate authorization HMAC value */
  64         ret = TSS_authhmac(authdata, keyauth, SHA1_DIGEST_SIZE, enonce,
  65                            nonceodd, cont, sizeof(uint32_t), &ordinal,
  66                            keybloblen, keyblob, 0, 0);
  67         if (ret < 0)
  68                 return ret;
  69 
  70         /* build the request buffer */
  71         INIT_BUF(tb);
  72         store16(tb, TPM_TAG_RQU_AUTH1_COMMAND);
  73         store32(tb, TPM_LOADKEY2_SIZE + keybloblen);
  74         store32(tb, TPM_ORD_LOADKEY2);
  75         store32(tb, keyhandle);
  76         storebytes(tb, keyblob, keybloblen);
  77         store32(tb, authhandle);
  78         storebytes(tb, nonceodd, TPM_NONCE_SIZE);
  79         store8(tb, cont);
  80         storebytes(tb, authdata, SHA1_DIGEST_SIZE);
  81 
  82         ret = trusted_tpm_send(tb->data, MAX_BUF_SIZE);
  83         if (ret < 0) {
  84                 pr_info("authhmac failed (%d)\n", ret);
  85                 return ret;
  86         }
  87 
  88         ret = TSS_checkhmac1(tb->data, ordinal, nonceodd, keyauth,
  89                              SHA1_DIGEST_SIZE, 0, 0);
  90         if (ret < 0) {
  91                 pr_info("TSS_checkhmac1 failed (%d)\n", ret);
  92                 return ret;
  93         }
  94 
  95         *newhandle = LOAD32(tb->data, TPM_DATA_OFFSET);
  96         return 0;
  97 }
  98 
  99 /*
 100  * Execute the FlushSpecific TPM command
 101  */
 102 static int tpm_flushspecific(struct tpm_buf *tb, uint32_t handle)
 103 {
 104         INIT_BUF(tb);
 105         store16(tb, TPM_TAG_RQU_COMMAND);
 106         store32(tb, TPM_FLUSHSPECIFIC_SIZE);
 107         store32(tb, TPM_ORD_FLUSHSPECIFIC);
 108         store32(tb, handle);
 109         store32(tb, TPM_RT_KEY);
 110 
 111         return trusted_tpm_send(tb->data, MAX_BUF_SIZE);
 112 }
 113 
 114 /*
 115  * Decrypt a blob provided by userspace using a specific key handle.
 116  * The handle is a well known handle or previously loaded by e.g. LoadKey2
 117  */
 118 static int tpm_unbind(struct tpm_buf *tb,
 119                         uint32_t keyhandle, unsigned char *keyauth,
 120                         const unsigned char *blob, uint32_t bloblen,
 121                         void *out, uint32_t outlen)
 122 {
 123         unsigned char nonceodd[TPM_NONCE_SIZE];
 124         unsigned char enonce[TPM_NONCE_SIZE];
 125         unsigned char authdata[SHA1_DIGEST_SIZE];
 126         uint32_t authhandle = 0;
 127         unsigned char cont = 0;
 128         uint32_t ordinal;
 129         uint32_t datalen;
 130         int ret;
 131 
 132         ordinal = htonl(TPM_ORD_UNBIND);
 133         datalen = htonl(bloblen);
 134 
 135         /* session for loading the key */
 136         ret = oiap(tb, &authhandle, enonce);
 137         if (ret < 0) {
 138                 pr_info("oiap failed (%d)\n", ret);
 139                 return ret;
 140         }
 141 
 142         /* generate odd nonce */
 143         ret = tpm_get_random(NULL, nonceodd, TPM_NONCE_SIZE);
 144         if (ret < 0) {
 145                 pr_info("tpm_get_random failed (%d)\n", ret);
 146                 return ret;
 147         }
 148 
 149         /* calculate authorization HMAC value */
 150         ret = TSS_authhmac(authdata, keyauth, SHA1_DIGEST_SIZE, enonce,
 151                            nonceodd, cont, sizeof(uint32_t), &ordinal,
 152                            sizeof(uint32_t), &datalen,
 153                            bloblen, blob, 0, 0);
 154         if (ret < 0)
 155                 return ret;
 156 
 157         /* build the request buffer */
 158         INIT_BUF(tb);
 159         store16(tb, TPM_TAG_RQU_AUTH1_COMMAND);
 160         store32(tb, TPM_UNBIND_SIZE + bloblen);
 161         store32(tb, TPM_ORD_UNBIND);
 162         store32(tb, keyhandle);
 163         store32(tb, bloblen);
 164         storebytes(tb, blob, bloblen);
 165         store32(tb, authhandle);
 166         storebytes(tb, nonceodd, TPM_NONCE_SIZE);
 167         store8(tb, cont);
 168         storebytes(tb, authdata, SHA1_DIGEST_SIZE);
 169 
 170         ret = trusted_tpm_send(tb->data, MAX_BUF_SIZE);
 171         if (ret < 0) {
 172                 pr_info("authhmac failed (%d)\n", ret);
 173                 return ret;
 174         }
 175 
 176         datalen = LOAD32(tb->data, TPM_DATA_OFFSET);
 177 
 178         ret = TSS_checkhmac1(tb->data, ordinal, nonceodd,
 179                              keyauth, SHA1_DIGEST_SIZE,
 180                              sizeof(uint32_t), TPM_DATA_OFFSET,
 181                              datalen, TPM_DATA_OFFSET + sizeof(uint32_t),
 182                              0, 0);
 183         if (ret < 0) {
 184                 pr_info("TSS_checkhmac1 failed (%d)\n", ret);
 185                 return ret;
 186         }
 187 
 188         memcpy(out, tb->data + TPM_DATA_OFFSET + sizeof(uint32_t),
 189                min(outlen, datalen));
 190 
 191         return datalen;
 192 }
 193 
 194 /*
 195  * Sign a blob provided by userspace (that has had the hash function applied)
 196  * using a specific key handle.  The handle is assumed to have been previously
 197  * loaded by e.g. LoadKey2.
 198  *
 199  * Note that the key signature scheme of the used key should be set to
 200  * TPM_SS_RSASSAPKCS1v15_DER.  This allows the hashed input to be of any size
 201  * up to key_length_in_bytes - 11 and not be limited to size 20 like the
 202  * TPM_SS_RSASSAPKCS1v15_SHA1 signature scheme.
 203  */
 204 static int tpm_sign(struct tpm_buf *tb,
 205                     uint32_t keyhandle, unsigned char *keyauth,
 206                     const unsigned char *blob, uint32_t bloblen,
 207                     void *out, uint32_t outlen)
 208 {
 209         unsigned char nonceodd[TPM_NONCE_SIZE];
 210         unsigned char enonce[TPM_NONCE_SIZE];
 211         unsigned char authdata[SHA1_DIGEST_SIZE];
 212         uint32_t authhandle = 0;
 213         unsigned char cont = 0;
 214         uint32_t ordinal;
 215         uint32_t datalen;
 216         int ret;
 217 
 218         ordinal = htonl(TPM_ORD_SIGN);
 219         datalen = htonl(bloblen);
 220 
 221         /* session for loading the key */
 222         ret = oiap(tb, &authhandle, enonce);
 223         if (ret < 0) {
 224                 pr_info("oiap failed (%d)\n", ret);
 225                 return ret;
 226         }
 227 
 228         /* generate odd nonce */
 229         ret = tpm_get_random(NULL, nonceodd, TPM_NONCE_SIZE);
 230         if (ret < 0) {
 231                 pr_info("tpm_get_random failed (%d)\n", ret);
 232                 return ret;
 233         }
 234 
 235         /* calculate authorization HMAC value */
 236         ret = TSS_authhmac(authdata, keyauth, SHA1_DIGEST_SIZE, enonce,
 237                            nonceodd, cont, sizeof(uint32_t), &ordinal,
 238                            sizeof(uint32_t), &datalen,
 239                            bloblen, blob, 0, 0);
 240         if (ret < 0)
 241                 return ret;
 242 
 243         /* build the request buffer */
 244         INIT_BUF(tb);
 245         store16(tb, TPM_TAG_RQU_AUTH1_COMMAND);
 246         store32(tb, TPM_SIGN_SIZE + bloblen);
 247         store32(tb, TPM_ORD_SIGN);
 248         store32(tb, keyhandle);
 249         store32(tb, bloblen);
 250         storebytes(tb, blob, bloblen);
 251         store32(tb, authhandle);
 252         storebytes(tb, nonceodd, TPM_NONCE_SIZE);
 253         store8(tb, cont);
 254         storebytes(tb, authdata, SHA1_DIGEST_SIZE);
 255 
 256         ret = trusted_tpm_send(tb->data, MAX_BUF_SIZE);
 257         if (ret < 0) {
 258                 pr_info("authhmac failed (%d)\n", ret);
 259                 return ret;
 260         }
 261 
 262         datalen = LOAD32(tb->data, TPM_DATA_OFFSET);
 263 
 264         ret = TSS_checkhmac1(tb->data, ordinal, nonceodd,
 265                              keyauth, SHA1_DIGEST_SIZE,
 266                              sizeof(uint32_t), TPM_DATA_OFFSET,
 267                              datalen, TPM_DATA_OFFSET + sizeof(uint32_t),
 268                              0, 0);
 269         if (ret < 0) {
 270                 pr_info("TSS_checkhmac1 failed (%d)\n", ret);
 271                 return ret;
 272         }
 273 
 274         memcpy(out, tb->data + TPM_DATA_OFFSET + sizeof(uint32_t),
 275                min(datalen, outlen));
 276 
 277         return datalen;
 278 }
 279 
 280 /* Room to fit two u32 zeros for algo id and parameters length. */
 281 #define SETKEY_PARAMS_SIZE (sizeof(u32) * 2)
 282 
 283 /*
 284  * Maximum buffer size for the BER/DER encoded public key.  The public key
 285  * is of the form SEQUENCE { INTEGER n, INTEGER e } where n is a maximum 2048
 286  * bit key and e is usually 65537
 287  * The encoding overhead is:
 288  * - max 4 bytes for SEQUENCE
 289  *   - max 4 bytes for INTEGER n type/length
 290  *     - 257 bytes of n
 291  *   - max 2 bytes for INTEGER e type/length
 292  *     - 3 bytes of e
 293  * - 4+4 of zeros for set_pub_key parameters (SETKEY_PARAMS_SIZE)
 294  */
 295 #define PUB_KEY_BUF_SIZE (4 + 4 + 257 + 2 + 3 + SETKEY_PARAMS_SIZE)
 296 
 297 /*
 298  * Provide a part of a description of the key for /proc/keys.
 299  */
 300 static void asym_tpm_describe(const struct key *asymmetric_key,
 301                               struct seq_file *m)
 302 {
 303         struct tpm_key *tk = asymmetric_key->payload.data[asym_crypto];
 304 
 305         if (!tk)
 306                 return;
 307 
 308         seq_printf(m, "TPM1.2/Blob");
 309 }
 310 
 311 static void asym_tpm_destroy(void *payload0, void *payload3)
 312 {
 313         struct tpm_key *tk = payload0;
 314 
 315         if (!tk)
 316                 return;
 317 
 318         kfree(tk->blob);
 319         tk->blob_len = 0;
 320 
 321         kfree(tk);
 322 }
 323 
 324 /* How many bytes will it take to encode the length */
 325 static inline uint32_t definite_length(uint32_t len)
 326 {
 327         if (len <= 127)
 328                 return 1;
 329         if (len <= 255)
 330                 return 2;
 331         return 3;
 332 }
 333 
 334 static inline uint8_t *encode_tag_length(uint8_t *buf, uint8_t tag,
 335                                          uint32_t len)
 336 {
 337         *buf++ = tag;
 338 
 339         if (len <= 127) {
 340                 buf[0] = len;
 341                 return buf + 1;
 342         }
 343 
 344         if (len <= 255) {
 345                 buf[0] = 0x81;
 346                 buf[1] = len;
 347                 return buf + 2;
 348         }
 349 
 350         buf[0] = 0x82;
 351         put_unaligned_be16(len, buf + 1);
 352         return buf + 3;
 353 }
 354 
 355 static uint32_t derive_pub_key(const void *pub_key, uint32_t len, uint8_t *buf)
 356 {
 357         uint8_t *cur = buf;
 358         uint32_t n_len = definite_length(len) + 1 + len + 1;
 359         uint32_t e_len = definite_length(3) + 1 + 3;
 360         uint8_t e[3] = { 0x01, 0x00, 0x01 };
 361 
 362         /* SEQUENCE */
 363         cur = encode_tag_length(cur, 0x30, n_len + e_len);
 364         /* INTEGER n */
 365         cur = encode_tag_length(cur, 0x02, len + 1);
 366         cur[0] = 0x00;
 367         memcpy(cur + 1, pub_key, len);
 368         cur += len + 1;
 369         cur = encode_tag_length(cur, 0x02, sizeof(e));
 370         memcpy(cur, e, sizeof(e));
 371         cur += sizeof(e);
 372         /* Zero parameters to satisfy set_pub_key ABI. */
 373         memset(cur, 0, SETKEY_PARAMS_SIZE);
 374 
 375         return cur - buf;
 376 }
 377 
 378 /*
 379  * Determine the crypto algorithm name.
 380  */
 381 static int determine_akcipher(const char *encoding, const char *hash_algo,
 382                               char alg_name[CRYPTO_MAX_ALG_NAME])
 383 {
 384         if (strcmp(encoding, "pkcs1") == 0) {
 385                 if (!hash_algo) {
 386                         strcpy(alg_name, "pkcs1pad(rsa)");
 387                         return 0;
 388                 }
 389 
 390                 if (snprintf(alg_name, CRYPTO_MAX_ALG_NAME, "pkcs1pad(rsa,%s)",
 391                              hash_algo) >= CRYPTO_MAX_ALG_NAME)
 392                         return -EINVAL;
 393 
 394                 return 0;
 395         }
 396 
 397         if (strcmp(encoding, "raw") == 0) {
 398                 strcpy(alg_name, "rsa");
 399                 return 0;
 400         }
 401 
 402         return -ENOPKG;
 403 }
 404 
 405 /*
 406  * Query information about a key.
 407  */
 408 static int tpm_key_query(const struct kernel_pkey_params *params,
 409                          struct kernel_pkey_query *info)
 410 {
 411         struct tpm_key *tk = params->key->payload.data[asym_crypto];
 412         int ret;
 413         char alg_name[CRYPTO_MAX_ALG_NAME];
 414         struct crypto_akcipher *tfm;
 415         uint8_t der_pub_key[PUB_KEY_BUF_SIZE];
 416         uint32_t der_pub_key_len;
 417         int len;
 418 
 419         /* TPM only works on private keys, public keys still done in software */
 420         ret = determine_akcipher(params->encoding, params->hash_algo, alg_name);
 421         if (ret < 0)
 422                 return ret;
 423 
 424         tfm = crypto_alloc_akcipher(alg_name, 0, 0);
 425         if (IS_ERR(tfm))
 426                 return PTR_ERR(tfm);
 427 
 428         der_pub_key_len = derive_pub_key(tk->pub_key, tk->pub_key_len,
 429                                          der_pub_key);
 430 
 431         ret = crypto_akcipher_set_pub_key(tfm, der_pub_key, der_pub_key_len);
 432         if (ret < 0)
 433                 goto error_free_tfm;
 434 
 435         len = crypto_akcipher_maxsize(tfm);
 436 
 437         info->key_size = tk->key_len;
 438         info->max_data_size = tk->key_len / 8;
 439         info->max_sig_size = len;
 440         info->max_enc_size = len;
 441         info->max_dec_size = tk->key_len / 8;
 442 
 443         info->supported_ops = KEYCTL_SUPPORTS_ENCRYPT |
 444                               KEYCTL_SUPPORTS_DECRYPT |
 445                               KEYCTL_SUPPORTS_VERIFY |
 446                               KEYCTL_SUPPORTS_SIGN;
 447 
 448         ret = 0;
 449 error_free_tfm:
 450         crypto_free_akcipher(tfm);
 451         pr_devel("<==%s() = %d\n", __func__, ret);
 452         return ret;
 453 }
 454 
 455 /*
 456  * Encryption operation is performed with the public key.  Hence it is done
 457  * in software
 458  */
 459 static int tpm_key_encrypt(struct tpm_key *tk,
 460                            struct kernel_pkey_params *params,
 461                            const void *in, void *out)
 462 {
 463         char alg_name[CRYPTO_MAX_ALG_NAME];
 464         struct crypto_akcipher *tfm;
 465         struct akcipher_request *req;
 466         struct crypto_wait cwait;
 467         struct scatterlist in_sg, out_sg;
 468         uint8_t der_pub_key[PUB_KEY_BUF_SIZE];
 469         uint32_t der_pub_key_len;
 470         int ret;
 471 
 472         pr_devel("==>%s()\n", __func__);
 473 
 474         ret = determine_akcipher(params->encoding, params->hash_algo, alg_name);
 475         if (ret < 0)
 476                 return ret;
 477 
 478         tfm = crypto_alloc_akcipher(alg_name, 0, 0);
 479         if (IS_ERR(tfm))
 480                 return PTR_ERR(tfm);
 481 
 482         der_pub_key_len = derive_pub_key(tk->pub_key, tk->pub_key_len,
 483                                          der_pub_key);
 484 
 485         ret = crypto_akcipher_set_pub_key(tfm, der_pub_key, der_pub_key_len);
 486         if (ret < 0)
 487                 goto error_free_tfm;
 488 
 489         ret = -ENOMEM;
 490         req = akcipher_request_alloc(tfm, GFP_KERNEL);
 491         if (!req)
 492                 goto error_free_tfm;
 493 
 494         sg_init_one(&in_sg, in, params->in_len);
 495         sg_init_one(&out_sg, out, params->out_len);
 496         akcipher_request_set_crypt(req, &in_sg, &out_sg, params->in_len,
 497                                    params->out_len);
 498         crypto_init_wait(&cwait);
 499         akcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG |
 500                                       CRYPTO_TFM_REQ_MAY_SLEEP,
 501                                       crypto_req_done, &cwait);
 502 
 503         ret = crypto_akcipher_encrypt(req);
 504         ret = crypto_wait_req(ret, &cwait);
 505 
 506         if (ret == 0)
 507                 ret = req->dst_len;
 508 
 509         akcipher_request_free(req);
 510 error_free_tfm:
 511         crypto_free_akcipher(tfm);
 512         pr_devel("<==%s() = %d\n", __func__, ret);
 513         return ret;
 514 }
 515 
 516 /*
 517  * Decryption operation is performed with the private key in the TPM.
 518  */
 519 static int tpm_key_decrypt(struct tpm_key *tk,
 520                            struct kernel_pkey_params *params,
 521                            const void *in, void *out)
 522 {
 523         struct tpm_buf *tb;
 524         uint32_t keyhandle;
 525         uint8_t srkauth[SHA1_DIGEST_SIZE];
 526         uint8_t keyauth[SHA1_DIGEST_SIZE];
 527         int r;
 528 
 529         pr_devel("==>%s()\n", __func__);
 530 
 531         if (params->hash_algo)
 532                 return -ENOPKG;
 533 
 534         if (strcmp(params->encoding, "pkcs1"))
 535                 return -ENOPKG;
 536 
 537         tb = kzalloc(sizeof(*tb), GFP_KERNEL);
 538         if (!tb)
 539                 return -ENOMEM;
 540 
 541         /* TODO: Handle a non-all zero SRK authorization */
 542         memset(srkauth, 0, sizeof(srkauth));
 543 
 544         r = tpm_loadkey2(tb, SRKHANDLE, srkauth,
 545                                 tk->blob, tk->blob_len, &keyhandle);
 546         if (r < 0) {
 547                 pr_devel("loadkey2 failed (%d)\n", r);
 548                 goto error;
 549         }
 550 
 551         /* TODO: Handle a non-all zero key authorization */
 552         memset(keyauth, 0, sizeof(keyauth));
 553 
 554         r = tpm_unbind(tb, keyhandle, keyauth,
 555                        in, params->in_len, out, params->out_len);
 556         if (r < 0)
 557                 pr_devel("tpm_unbind failed (%d)\n", r);
 558 
 559         if (tpm_flushspecific(tb, keyhandle) < 0)
 560                 pr_devel("flushspecific failed (%d)\n", r);
 561 
 562 error:
 563         kzfree(tb);
 564         pr_devel("<==%s() = %d\n", __func__, r);
 565         return r;
 566 }
 567 
 568 /*
 569  * Hash algorithm OIDs plus ASN.1 DER wrappings [RFC4880 sec 5.2.2].
 570  */
 571 static const u8 digest_info_md5[] = {
 572         0x30, 0x20, 0x30, 0x0c, 0x06, 0x08,
 573         0x2a, 0x86, 0x48, 0x86, 0xf7, 0x0d, 0x02, 0x05, /* OID */
 574         0x05, 0x00, 0x04, 0x10
 575 };
 576 
 577 static const u8 digest_info_sha1[] = {
 578         0x30, 0x21, 0x30, 0x09, 0x06, 0x05,
 579         0x2b, 0x0e, 0x03, 0x02, 0x1a,
 580         0x05, 0x00, 0x04, 0x14
 581 };
 582 
 583 static const u8 digest_info_rmd160[] = {
 584         0x30, 0x21, 0x30, 0x09, 0x06, 0x05,
 585         0x2b, 0x24, 0x03, 0x02, 0x01,
 586         0x05, 0x00, 0x04, 0x14
 587 };
 588 
 589 static const u8 digest_info_sha224[] = {
 590         0x30, 0x2d, 0x30, 0x0d, 0x06, 0x09,
 591         0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x04,
 592         0x05, 0x00, 0x04, 0x1c
 593 };
 594 
 595 static const u8 digest_info_sha256[] = {
 596         0x30, 0x31, 0x30, 0x0d, 0x06, 0x09,
 597         0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x01,
 598         0x05, 0x00, 0x04, 0x20
 599 };
 600 
 601 static const u8 digest_info_sha384[] = {
 602         0x30, 0x41, 0x30, 0x0d, 0x06, 0x09,
 603         0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x02,
 604         0x05, 0x00, 0x04, 0x30
 605 };
 606 
 607 static const u8 digest_info_sha512[] = {
 608         0x30, 0x51, 0x30, 0x0d, 0x06, 0x09,
 609         0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x03,
 610         0x05, 0x00, 0x04, 0x40
 611 };
 612 
 613 static const struct asn1_template {
 614         const char      *name;
 615         const u8        *data;
 616         size_t          size;
 617 } asn1_templates[] = {
 618 #define _(X) { #X, digest_info_##X, sizeof(digest_info_##X) }
 619         _(md5),
 620         _(sha1),
 621         _(rmd160),
 622         _(sha256),
 623         _(sha384),
 624         _(sha512),
 625         _(sha224),
 626         { NULL }
 627 #undef _
 628 };
 629 
 630 static const struct asn1_template *lookup_asn1(const char *name)
 631 {
 632         const struct asn1_template *p;
 633 
 634         for (p = asn1_templates; p->name; p++)
 635                 if (strcmp(name, p->name) == 0)
 636                         return p;
 637         return NULL;
 638 }
 639 
 640 /*
 641  * Sign operation is performed with the private key in the TPM.
 642  */
 643 static int tpm_key_sign(struct tpm_key *tk,
 644                         struct kernel_pkey_params *params,
 645                         const void *in, void *out)
 646 {
 647         struct tpm_buf *tb;
 648         uint32_t keyhandle;
 649         uint8_t srkauth[SHA1_DIGEST_SIZE];
 650         uint8_t keyauth[SHA1_DIGEST_SIZE];
 651         void *asn1_wrapped = NULL;
 652         uint32_t in_len = params->in_len;
 653         int r;
 654 
 655         pr_devel("==>%s()\n", __func__);
 656 
 657         if (strcmp(params->encoding, "pkcs1"))
 658                 return -ENOPKG;
 659 
 660         if (params->hash_algo) {
 661                 const struct asn1_template *asn1 =
 662                                                 lookup_asn1(params->hash_algo);
 663 
 664                 if (!asn1)
 665                         return -ENOPKG;
 666 
 667                 /* request enough space for the ASN.1 template + input hash */
 668                 asn1_wrapped = kzalloc(in_len + asn1->size, GFP_KERNEL);
 669                 if (!asn1_wrapped)
 670                         return -ENOMEM;
 671 
 672                 /* Copy ASN.1 template, then the input */
 673                 memcpy(asn1_wrapped, asn1->data, asn1->size);
 674                 memcpy(asn1_wrapped + asn1->size, in, in_len);
 675 
 676                 in = asn1_wrapped;
 677                 in_len += asn1->size;
 678         }
 679 
 680         if (in_len > tk->key_len / 8 - 11) {
 681                 r = -EOVERFLOW;
 682                 goto error_free_asn1_wrapped;
 683         }
 684 
 685         r = -ENOMEM;
 686         tb = kzalloc(sizeof(*tb), GFP_KERNEL);
 687         if (!tb)
 688                 goto error_free_asn1_wrapped;
 689 
 690         /* TODO: Handle a non-all zero SRK authorization */
 691         memset(srkauth, 0, sizeof(srkauth));
 692 
 693         r = tpm_loadkey2(tb, SRKHANDLE, srkauth,
 694                          tk->blob, tk->blob_len, &keyhandle);
 695         if (r < 0) {
 696                 pr_devel("loadkey2 failed (%d)\n", r);
 697                 goto error_free_tb;
 698         }
 699 
 700         /* TODO: Handle a non-all zero key authorization */
 701         memset(keyauth, 0, sizeof(keyauth));
 702 
 703         r = tpm_sign(tb, keyhandle, keyauth, in, in_len, out, params->out_len);
 704         if (r < 0)
 705                 pr_devel("tpm_sign failed (%d)\n", r);
 706 
 707         if (tpm_flushspecific(tb, keyhandle) < 0)
 708                 pr_devel("flushspecific failed (%d)\n", r);
 709 
 710 error_free_tb:
 711         kzfree(tb);
 712 error_free_asn1_wrapped:
 713         kfree(asn1_wrapped);
 714         pr_devel("<==%s() = %d\n", __func__, r);
 715         return r;
 716 }
 717 
 718 /*
 719  * Do encryption, decryption and signing ops.
 720  */
 721 static int tpm_key_eds_op(struct kernel_pkey_params *params,
 722                           const void *in, void *out)
 723 {
 724         struct tpm_key *tk = params->key->payload.data[asym_crypto];
 725         int ret = -EOPNOTSUPP;
 726 
 727         /* Perform the encryption calculation. */
 728         switch (params->op) {
 729         case kernel_pkey_encrypt:
 730                 ret = tpm_key_encrypt(tk, params, in, out);
 731                 break;
 732         case kernel_pkey_decrypt:
 733                 ret = tpm_key_decrypt(tk, params, in, out);
 734                 break;
 735         case kernel_pkey_sign:
 736                 ret = tpm_key_sign(tk, params, in, out);
 737                 break;
 738         default:
 739                 BUG();
 740         }
 741 
 742         return ret;
 743 }
 744 
 745 /*
 746  * Verify a signature using a public key.
 747  */
 748 static int tpm_key_verify_signature(const struct key *key,
 749                                     const struct public_key_signature *sig)
 750 {
 751         const struct tpm_key *tk = key->payload.data[asym_crypto];
 752         struct crypto_wait cwait;
 753         struct crypto_akcipher *tfm;
 754         struct akcipher_request *req;
 755         struct scatterlist src_sg[2];
 756         char alg_name[CRYPTO_MAX_ALG_NAME];
 757         uint8_t der_pub_key[PUB_KEY_BUF_SIZE];
 758         uint32_t der_pub_key_len;
 759         int ret;
 760 
 761         pr_devel("==>%s()\n", __func__);
 762 
 763         BUG_ON(!tk);
 764         BUG_ON(!sig);
 765         BUG_ON(!sig->s);
 766 
 767         if (!sig->digest)
 768                 return -ENOPKG;
 769 
 770         ret = determine_akcipher(sig->encoding, sig->hash_algo, alg_name);
 771         if (ret < 0)
 772                 return ret;
 773 
 774         tfm = crypto_alloc_akcipher(alg_name, 0, 0);
 775         if (IS_ERR(tfm))
 776                 return PTR_ERR(tfm);
 777 
 778         der_pub_key_len = derive_pub_key(tk->pub_key, tk->pub_key_len,
 779                                          der_pub_key);
 780 
 781         ret = crypto_akcipher_set_pub_key(tfm, der_pub_key, der_pub_key_len);
 782         if (ret < 0)
 783                 goto error_free_tfm;
 784 
 785         ret = -ENOMEM;
 786         req = akcipher_request_alloc(tfm, GFP_KERNEL);
 787         if (!req)
 788                 goto error_free_tfm;
 789 
 790         sg_init_table(src_sg, 2);
 791         sg_set_buf(&src_sg[0], sig->s, sig->s_size);
 792         sg_set_buf(&src_sg[1], sig->digest, sig->digest_size);
 793         akcipher_request_set_crypt(req, src_sg, NULL, sig->s_size,
 794                                    sig->digest_size);
 795         crypto_init_wait(&cwait);
 796         akcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG |
 797                                       CRYPTO_TFM_REQ_MAY_SLEEP,
 798                                       crypto_req_done, &cwait);
 799         ret = crypto_wait_req(crypto_akcipher_verify(req), &cwait);
 800 
 801         akcipher_request_free(req);
 802 error_free_tfm:
 803         crypto_free_akcipher(tfm);
 804         pr_devel("<==%s() = %d\n", __func__, ret);
 805         if (WARN_ON_ONCE(ret > 0))
 806                 ret = -EINVAL;
 807         return ret;
 808 }
 809 
 810 /*
 811  * Parse enough information out of TPM_KEY structure:
 812  * TPM_STRUCT_VER -> 4 bytes
 813  * TPM_KEY_USAGE -> 2 bytes
 814  * TPM_KEY_FLAGS -> 4 bytes
 815  * TPM_AUTH_DATA_USAGE -> 1 byte
 816  * TPM_KEY_PARMS -> variable
 817  * UINT32 PCRInfoSize -> 4 bytes
 818  * BYTE* -> PCRInfoSize bytes
 819  * TPM_STORE_PUBKEY
 820  * UINT32 encDataSize;
 821  * BYTE* -> encDataSize;
 822  *
 823  * TPM_KEY_PARMS:
 824  * TPM_ALGORITHM_ID -> 4 bytes
 825  * TPM_ENC_SCHEME -> 2 bytes
 826  * TPM_SIG_SCHEME -> 2 bytes
 827  * UINT32 parmSize -> 4 bytes
 828  * BYTE* -> variable
 829  */
 830 static int extract_key_parameters(struct tpm_key *tk)
 831 {
 832         const void *cur = tk->blob;
 833         uint32_t len = tk->blob_len;
 834         const void *pub_key;
 835         uint32_t sz;
 836         uint32_t key_len;
 837 
 838         if (len < 11)
 839                 return -EBADMSG;
 840 
 841         /* Ensure this is a legacy key */
 842         if (get_unaligned_be16(cur + 4) != 0x0015)
 843                 return -EBADMSG;
 844 
 845         /* Skip to TPM_KEY_PARMS */
 846         cur += 11;
 847         len -= 11;
 848 
 849         if (len < 12)
 850                 return -EBADMSG;
 851 
 852         /* Make sure this is an RSA key */
 853         if (get_unaligned_be32(cur) != 0x00000001)
 854                 return -EBADMSG;
 855 
 856         /* Make sure this is TPM_ES_RSAESPKCSv15 encoding scheme */
 857         if (get_unaligned_be16(cur + 4) != 0x0002)
 858                 return -EBADMSG;
 859 
 860         /* Make sure this is TPM_SS_RSASSAPKCS1v15_DER signature scheme */
 861         if (get_unaligned_be16(cur + 6) != 0x0003)
 862                 return -EBADMSG;
 863 
 864         sz = get_unaligned_be32(cur + 8);
 865         if (len < sz + 12)
 866                 return -EBADMSG;
 867 
 868         /* Move to TPM_RSA_KEY_PARMS */
 869         len -= 12;
 870         cur += 12;
 871 
 872         /* Grab the RSA key length */
 873         key_len = get_unaligned_be32(cur);
 874 
 875         switch (key_len) {
 876         case 512:
 877         case 1024:
 878         case 1536:
 879         case 2048:
 880                 break;
 881         default:
 882                 return -EINVAL;
 883         }
 884 
 885         /* Move just past TPM_KEY_PARMS */
 886         cur += sz;
 887         len -= sz;
 888 
 889         if (len < 4)
 890                 return -EBADMSG;
 891 
 892         sz = get_unaligned_be32(cur);
 893         if (len < 4 + sz)
 894                 return -EBADMSG;
 895 
 896         /* Move to TPM_STORE_PUBKEY */
 897         cur += 4 + sz;
 898         len -= 4 + sz;
 899 
 900         /* Grab the size of the public key, it should jive with the key size */
 901         sz = get_unaligned_be32(cur);
 902         if (sz > 256)
 903                 return -EINVAL;
 904 
 905         pub_key = cur + 4;
 906 
 907         tk->key_len = key_len;
 908         tk->pub_key = pub_key;
 909         tk->pub_key_len = sz;
 910 
 911         return 0;
 912 }
 913 
 914 /* Given the blob, parse it and load it into the TPM */
 915 struct tpm_key *tpm_key_create(const void *blob, uint32_t blob_len)
 916 {
 917         int r;
 918         struct tpm_key *tk;
 919 
 920         r = tpm_is_tpm2(NULL);
 921         if (r < 0)
 922                 goto error;
 923 
 924         /* We don't support TPM2 yet */
 925         if (r > 0) {
 926                 r = -ENODEV;
 927                 goto error;
 928         }
 929 
 930         r = -ENOMEM;
 931         tk = kzalloc(sizeof(struct tpm_key), GFP_KERNEL);
 932         if (!tk)
 933                 goto error;
 934 
 935         tk->blob = kmemdup(blob, blob_len, GFP_KERNEL);
 936         if (!tk->blob)
 937                 goto error_memdup;
 938 
 939         tk->blob_len = blob_len;
 940 
 941         r = extract_key_parameters(tk);
 942         if (r < 0)
 943                 goto error_extract;
 944 
 945         return tk;
 946 
 947 error_extract:
 948         kfree(tk->blob);
 949         tk->blob_len = 0;
 950 error_memdup:
 951         kfree(tk);
 952 error:
 953         return ERR_PTR(r);
 954 }
 955 EXPORT_SYMBOL_GPL(tpm_key_create);
 956 
 957 /*
 958  * TPM-based asymmetric key subtype
 959  */
 960 struct asymmetric_key_subtype asym_tpm_subtype = {
 961         .owner                  = THIS_MODULE,
 962         .name                   = "asym_tpm",
 963         .name_len               = sizeof("asym_tpm") - 1,
 964         .describe               = asym_tpm_describe,
 965         .destroy                = asym_tpm_destroy,
 966         .query                  = tpm_key_query,
 967         .eds_op                 = tpm_key_eds_op,
 968         .verify_signature       = tpm_key_verify_signature,
 969 };
 970 EXPORT_SYMBOL_GPL(asym_tpm_subtype);
 971 
 972 MODULE_DESCRIPTION("TPM based asymmetric key subtype");
 973 MODULE_AUTHOR("Intel Corporation");
 974 MODULE_LICENSE("GPL v2");
/* [<][>][^][v][top][bottom][index][help] */
root/crypto/asymmetric_keys/asym_tpm.c

DEFINITIONS
