1/*
   2 * Copyright (C) 2010 IBM Corporation
   3 * Copyright (C) 2010 Politecnico di Torino, Italy
   4 *                    TORSEC group -- http://security.polito.it
   5 *
   6 * Authors:
   7 * Mimi Zohar <zohar@us.ibm.com>
   8 * Roberto Sassu <roberto.sassu@polito.it>
   9 *
  10 * This program is free software; you can redistribute it and/or modify
  11 * it under the terms of the GNU General Public License as published by
  12 * the Free Software Foundation, version 2 of the License.
  13 *
  14 * See Documentation/security/keys-trusted-encrypted.txt
  15 */
  16
  17#include <linux/uaccess.h>
  18#include <linux/module.h>
  19#include <linux/init.h>
  20#include <linux/slab.h>
  21#include <linux/parser.h>
  22#include <linux/string.h>
  23#include <linux/err.h>
  24#include <keys/user-type.h>
  25#include <keys/trusted-type.h>
  26#include <keys/encrypted-type.h>
  27#include <linux/key-type.h>
  28#include <linux/random.h>
  29#include <linux/rcupdate.h>
  30#include <linux/scatterlist.h>
  31#include <linux/ctype.h>
  32#include <crypto/hash.h>
  33#include <crypto/sha.h>
  34#include <crypto/skcipher.h>
  35
  36#include "encrypted.h"
  37#include "ecryptfs_format.h"
  38
  39static const char KEY_TRUSTED_PREFIX[] = "trusted:";
  40static const char KEY_USER_PREFIX[] = "user:";
  41static const char hash_alg[] = "sha256";
  42static const char hmac_alg[] = "hmac(sha256)";
  43static const char blkcipher_alg[] = "cbc(aes)";
  44static const char key_format_default[] = "default";
  45static const char key_format_ecryptfs[] = "ecryptfs";
  46static unsigned int ivsize;
  47static int blksize;
  48
  49#define KEY_TRUSTED_PREFIX_LEN (sizeof (KEY_TRUSTED_PREFIX) - 1)
  50#define KEY_USER_PREFIX_LEN (sizeof (KEY_USER_PREFIX) - 1)
  51#define KEY_ECRYPTFS_DESC_LEN 16
  52#define HASH_SIZE SHA256_DIGEST_SIZE
  53#define MAX_DATA_SIZE 4096
  54#define MIN_DATA_SIZE  20
  55
  56struct sdesc {
  57	struct shash_desc shash;
  58	char ctx[];
  59};
  60
  61static struct crypto_shash *hashalg;
  62static struct crypto_shash *hmacalg;
  63
  64enum {
  65	Opt_err = -1, Opt_new, Opt_load, Opt_update
  66};
  67
  68enum {
  69	Opt_error = -1, Opt_default, Opt_ecryptfs
  70};
  71
  72static const match_table_t key_format_tokens = {
  73	{Opt_default, "default"},
  74	{Opt_ecryptfs, "ecryptfs"},
  75	{Opt_error, NULL}
  76};
  77
  78static const match_table_t key_tokens = {
  79	{Opt_new, "new"},
  80	{Opt_load, "load"},
  81	{Opt_update, "update"},
  82	{Opt_err, NULL}
  83};
  84
  85static int aes_get_sizes(void)
  86{
  87	struct crypto_skcipher *tfm;
  88
  89	tfm = crypto_alloc_skcipher(blkcipher_alg, 0, CRYPTO_ALG_ASYNC);
  90	if (IS_ERR(tfm)) {
  91		pr_err("encrypted_key: failed to alloc_cipher (%ld)\n",
  92		       PTR_ERR(tfm));
  93		return PTR_ERR(tfm);
  94	}
  95	ivsize = crypto_skcipher_ivsize(tfm);
  96	blksize = crypto_skcipher_blocksize(tfm);
  97	crypto_free_skcipher(tfm);
  98	return 0;
  99}
 100
 101/*
 102 * valid_ecryptfs_desc - verify the description of a new/loaded encrypted key
 103 *
 104 * The description of a encrypted key with format 'ecryptfs' must contain
 105 * exactly 16 hexadecimal characters.
 106 *
 107 */
 108static int valid_ecryptfs_desc(const char *ecryptfs_desc)
 109{
 110	int i;
 111
 112	if (strlen(ecryptfs_desc) != KEY_ECRYPTFS_DESC_LEN) {
 113		pr_err("encrypted_key: key description must be %d hexadecimal "
 114		       "characters long\n", KEY_ECRYPTFS_DESC_LEN);
 115		return -EINVAL;
 116	}
 117
 118	for (i = 0; i < KEY_ECRYPTFS_DESC_LEN; i++) {
 119		if (!isxdigit(ecryptfs_desc[i])) {
 120			pr_err("encrypted_key: key description must contain "
 121			       "only hexadecimal characters\n");
 122			return -EINVAL;
 123		}
 124	}
 125
 126	return 0;
 127}
 128
 129/*
 130 * valid_master_desc - verify the 'key-type:desc' of a new/updated master-key
 131 *
 132 * key-type:= "trusted:" | "user:"
 133 * desc:= master-key description
 134 *
 135 * Verify that 'key-type' is valid and that 'desc' exists. On key update,
 136 * only the master key description is permitted to change, not the key-type.
 137 * The key-type remains constant.
 138 *
 139 * On success returns 0, otherwise -EINVAL.
 140 */
 141static int valid_master_desc(const char *new_desc, const char *orig_desc)
 142{
 143	if (!memcmp(new_desc, KEY_TRUSTED_PREFIX, KEY_TRUSTED_PREFIX_LEN)) {
 144		if (strlen(new_desc) == KEY_TRUSTED_PREFIX_LEN)
 145			goto out;
 146		if (orig_desc)
 147			if (memcmp(new_desc, orig_desc, KEY_TRUSTED_PREFIX_LEN))
 148				goto out;
 149	} else if (!memcmp(new_desc, KEY_USER_PREFIX, KEY_USER_PREFIX_LEN)) {
 150		if (strlen(new_desc) == KEY_USER_PREFIX_LEN)
 151			goto out;
 152		if (orig_desc)
 153			if (memcmp(new_desc, orig_desc, KEY_USER_PREFIX_LEN))
 154				goto out;
 155	} else
 156		goto out;
 157	return 0;
 158out:
 159	return -EINVAL;
 160}
 161
 162/*
 163 * datablob_parse - parse the keyctl data
 164 *
 165 * datablob format:
 166 * new [<format>] <master-key name> <decrypted data length>
 167 * load [<format>] <master-key name> <decrypted data length>
 168 *     <encrypted iv + data>
 169 * update <new-master-key name>
 170 *
 171 * Tokenizes a copy of the keyctl data, returning a pointer to each token,
 172 * which is null terminated.
 173 *
 174 * On success returns 0, otherwise -EINVAL.
 175 */
 176static int datablob_parse(char *datablob, const char **format,
 177			  char **master_desc, char **decrypted_datalen,
 178			  char **hex_encoded_iv)
 179{
 180	substring_t args[MAX_OPT_ARGS];
 181	int ret = -EINVAL;
 182	int key_cmd;
 183	int key_format;
 184	char *p, *keyword;
 185
 186	keyword = strsep(&datablob, " \t");
 187	if (!keyword) {
 188		pr_info("encrypted_key: insufficient parameters specified\n");
 189		return ret;
 190	}
 191	key_cmd = match_token(keyword, key_tokens, args);
 192
 193	/* Get optional format: default | ecryptfs */
 194	p = strsep(&datablob, " \t");
 195	if (!p) {
 196		pr_err("encrypted_key: insufficient parameters specified\n");
 197		return ret;
 198	}
 199
 200	key_format = match_token(p, key_format_tokens, args);
 201	switch (key_format) {
 202	case Opt_ecryptfs:
 203	case Opt_default:
 204		*format = p;
 205		*master_desc = strsep(&datablob, " \t");
 206		break;
 207	case Opt_error:
 208		*master_desc = p;
 209		break;
 210	}
 211
 212	if (!*master_desc) {
 213		pr_info("encrypted_key: master key parameter is missing\n");
 214		goto out;
 215	}
 216
 217	if (valid_master_desc(*master_desc, NULL) < 0) {
 218		pr_info("encrypted_key: master key parameter \'%s\' "
 219			"is invalid\n", *master_desc);
 220		goto out;
 221	}
 222
 223	if (decrypted_datalen) {
 224		*decrypted_datalen = strsep(&datablob, " \t");
 225		if (!*decrypted_datalen) {
 226			pr_info("encrypted_key: keylen parameter is missing\n");
 227			goto out;
 228		}
 229	}
 230
 231	switch (key_cmd) {
 232	case Opt_new:
 233		if (!decrypted_datalen) {
 234			pr_info("encrypted_key: keyword \'%s\' not allowed "
 235				"when called from .update method\n", keyword);
 236			break;
 237		}
 238		ret = 0;
 239		break;
 240	case Opt_load:
 241		if (!decrypted_datalen) {
 242			pr_info("encrypted_key: keyword \'%s\' not allowed "
 243				"when called from .update method\n", keyword);
 244			break;
 245		}
 246		*hex_encoded_iv = strsep(&datablob, " \t");
 247		if (!*hex_encoded_iv) {
 248			pr_info("encrypted_key: hex blob is missing\n");
 249			break;
 250		}
 251		ret = 0;
 252		break;
 253	case Opt_update:
 254		if (decrypted_datalen) {
 255			pr_info("encrypted_key: keyword \'%s\' not allowed "
 256				"when called from .instantiate method\n",
 257				keyword);
 258			break;
 259		}
 260		ret = 0;
 261		break;
 262	case Opt_err:
 263		pr_info("encrypted_key: keyword \'%s\' not recognized\n",
 264			keyword);
 265		break;
 266	}
 267out:
 268	return ret;
 269}
 270
 271/*
 272 * datablob_format - format as an ascii string, before copying to userspace
 273 */
 274static char *datablob_format(struct encrypted_key_payload *epayload,
 275			     size_t asciiblob_len)
 276{
 277	char *ascii_buf, *bufp;
 278	u8 *iv = epayload->iv;
 279	int len;
 280	int i;
 281
 282	ascii_buf = kmalloc(asciiblob_len + 1, GFP_KERNEL);
 283	if (!ascii_buf)
 284		goto out;
 285
 286	ascii_buf[asciiblob_len] = '\0';
 287
 288	/* copy datablob master_desc and datalen strings */
 289	len = sprintf(ascii_buf, "%s %s %s ", epayload->format,
 290		      epayload->master_desc, epayload->datalen);
 291
 292	/* convert the hex encoded iv, encrypted-data and HMAC to ascii */
 293	bufp = &ascii_buf[len];
 294	for (i = 0; i < (asciiblob_len - len) / 2; i++)
 295		bufp = hex_byte_pack(bufp, iv[i]);
 296out:
 297	return ascii_buf;
 298}
 299
 300/*
 301 * request_user_key - request the user key
 302 *
 303 * Use a user provided key to encrypt/decrypt an encrypted-key.
 304 */
 305static struct key *request_user_key(const char *master_desc, const u8 **master_key,
 306				    size_t *master_keylen)
 307{
 308	const struct user_key_payload *upayload;
 309	struct key *ukey;
 310
 311	ukey = request_key(&key_type_user, master_desc, NULL);
 312	if (IS_ERR(ukey))
 313		goto error;
 314
 315	down_read(&ukey->sem);
 316	upayload = user_key_payload(ukey);
 317	*master_key = upayload->data;
 318	*master_keylen = upayload->datalen;
 319error:
 320	return ukey;
 321}
 322
 323static struct sdesc *alloc_sdesc(struct crypto_shash *alg)
 324{
 325	struct sdesc *sdesc;
 326	int size;
 327
 328	size = sizeof(struct shash_desc) + crypto_shash_descsize(alg);
 329	sdesc = kmalloc(size, GFP_KERNEL);
 330	if (!sdesc)
 331		return ERR_PTR(-ENOMEM);
 332	sdesc->shash.tfm = alg;
 333	sdesc->shash.flags = 0x0;
 334	return sdesc;
 335}
 336
 337static int calc_hmac(u8 *digest, const u8 *key, unsigned int keylen,
 338		     const u8 *buf, unsigned int buflen)
 339{
 340	struct sdesc *sdesc;
 341	int ret;
 342
 343	sdesc = alloc_sdesc(hmacalg);
 344	if (IS_ERR(sdesc)) {
 345		pr_info("encrypted_key: can't alloc %s\n", hmac_alg);
 346		return PTR_ERR(sdesc);
 347	}
 348
 349	ret = crypto_shash_setkey(hmacalg, key, keylen);
 350	if (!ret)
 351		ret = crypto_shash_digest(&sdesc->shash, buf, buflen, digest);
 352	kfree(sdesc);
 353	return ret;
 354}
 355
 356static int calc_hash(u8 *digest, const u8 *buf, unsigned int buflen)
 357{
 358	struct sdesc *sdesc;
 359	int ret;
 360
 361	sdesc = alloc_sdesc(hashalg);
 362	if (IS_ERR(sdesc)) {
 363		pr_info("encrypted_key: can't alloc %s\n", hash_alg);
 364		return PTR_ERR(sdesc);
 365	}
 366
 367	ret = crypto_shash_digest(&sdesc->shash, buf, buflen, digest);
 368	kfree(sdesc);
 369	return ret;
 370}
 371
 372enum derived_key_type { ENC_KEY, AUTH_KEY };
 373
 374/* Derive authentication/encryption key from trusted key */
 375static int get_derived_key(u8 *derived_key, enum derived_key_type key_type,
 376			   const u8 *master_key, size_t master_keylen)
 377{
 378	u8 *derived_buf;
 379	unsigned int derived_buf_len;
 380	int ret;
 381
 382	derived_buf_len = strlen("AUTH_KEY") + 1 + master_keylen;
 383	if (derived_buf_len < HASH_SIZE)
 384		derived_buf_len = HASH_SIZE;
 385
 386	derived_buf = kzalloc(derived_buf_len, GFP_KERNEL);
 387	if (!derived_buf) {
 388		pr_err("encrypted_key: out of memory\n");
 389		return -ENOMEM;
 390	}
 391	if (key_type)
 392		strcpy(derived_buf, "AUTH_KEY");
 393	else
 394		strcpy(derived_buf, "ENC_KEY");
 395
 396	memcpy(derived_buf + strlen(derived_buf) + 1, master_key,
 397	       master_keylen);
 398	ret = calc_hash(derived_key, derived_buf, derived_buf_len);
 399	kfree(derived_buf);
 400	return ret;
 401}
 402
 403static struct skcipher_request *init_skcipher_req(const u8 *key,
 404						  unsigned int key_len)
 405{
 406	struct skcipher_request *req;
 407	struct crypto_skcipher *tfm;
 408	int ret;
 409
 410	tfm = crypto_alloc_skcipher(blkcipher_alg, 0, CRYPTO_ALG_ASYNC);
 411	if (IS_ERR(tfm)) {
 412		pr_err("encrypted_key: failed to load %s transform (%ld)\n",
 413		       blkcipher_alg, PTR_ERR(tfm));
 414		return ERR_CAST(tfm);
 415	}
 416
 417	ret = crypto_skcipher_setkey(tfm, key, key_len);
 418	if (ret < 0) {
 419		pr_err("encrypted_key: failed to setkey (%d)\n", ret);
 420		crypto_free_skcipher(tfm);
 421		return ERR_PTR(ret);
 422	}
 423
 424	req = skcipher_request_alloc(tfm, GFP_KERNEL);
 425	if (!req) {
 426		pr_err("encrypted_key: failed to allocate request for %s\n",
 427		       blkcipher_alg);
 428		crypto_free_skcipher(tfm);
 429		return ERR_PTR(-ENOMEM);
 430	}
 431
 432	skcipher_request_set_callback(req, 0, NULL, NULL);
 433	return req;
 434}
 435
 436static struct key *request_master_key(struct encrypted_key_payload *epayload,
 437				      const u8 **master_key, size_t *master_keylen)
 438{
 439	struct key *mkey = NULL;
 440
 441	if (!strncmp(epayload->master_desc, KEY_TRUSTED_PREFIX,
 442		     KEY_TRUSTED_PREFIX_LEN)) {
 443		mkey = request_trusted_key(epayload->master_desc +
 444					   KEY_TRUSTED_PREFIX_LEN,
 445					   master_key, master_keylen);
 446	} else if (!strncmp(epayload->master_desc, KEY_USER_PREFIX,
 447			    KEY_USER_PREFIX_LEN)) {
 448		mkey = request_user_key(epayload->master_desc +
 449					KEY_USER_PREFIX_LEN,
 450					master_key, master_keylen);
 451	} else
 452		goto out;
 453
 454	if (IS_ERR(mkey)) {
 455		int ret = PTR_ERR(mkey);
 456
 457		if (ret == -ENOTSUPP)
 458			pr_info("encrypted_key: key %s not supported",
 459				epayload->master_desc);
 460		else
 461			pr_info("encrypted_key: key %s not found",
 462				epayload->master_desc);
 463		goto out;
 464	}
 465
 466	dump_master_key(*master_key, *master_keylen);
 467out:
 468	return mkey;
 469}
 470
 471/* Before returning data to userspace, encrypt decrypted data. */
 472static int derived_key_encrypt(struct encrypted_key_payload *epayload,
 473			       const u8 *derived_key,
 474			       unsigned int derived_keylen)
 475{
 476	struct scatterlist sg_in[2];
 477	struct scatterlist sg_out[1];
 478	struct crypto_skcipher *tfm;
 479	struct skcipher_request *req;
 480	unsigned int encrypted_datalen;
 481	unsigned int padlen;
 482	char pad[16];
 483	int ret;
 484
 485	encrypted_datalen = roundup(epayload->decrypted_datalen, blksize);
 486	padlen = encrypted_datalen - epayload->decrypted_datalen;
 487
 488	req = init_skcipher_req(derived_key, derived_keylen);
 489	ret = PTR_ERR(req);
 490	if (IS_ERR(req))
 491		goto out;
 492	dump_decrypted_data(epayload);
 493
 494	memset(pad, 0, sizeof pad);
 495	sg_init_table(sg_in, 2);
 496	sg_set_buf(&sg_in[0], epayload->decrypted_data,
 497		   epayload->decrypted_datalen);
 498	sg_set_buf(&sg_in[1], pad, padlen);
 499
 500	sg_init_table(sg_out, 1);
 501	sg_set_buf(sg_out, epayload->encrypted_data, encrypted_datalen);
 502
 503	skcipher_request_set_crypt(req, sg_in, sg_out, encrypted_datalen,
 504				   epayload->iv);
 505	ret = crypto_skcipher_encrypt(req);
 506	tfm = crypto_skcipher_reqtfm(req);
 507	skcipher_request_free(req);
 508	crypto_free_skcipher(tfm);
 509	if (ret < 0)
 510		pr_err("encrypted_key: failed to encrypt (%d)\n", ret);
 511	else
 512		dump_encrypted_data(epayload, encrypted_datalen);
 513out:
 514	return ret;
 515}
 516
 517static int datablob_hmac_append(struct encrypted_key_payload *epayload,
 518				const u8 *master_key, size_t master_keylen)
 519{
 520	u8 derived_key[HASH_SIZE];
 521	u8 *digest;
 522	int ret;
 523
 524	ret = get_derived_key(derived_key, AUTH_KEY, master_key, master_keylen);
 525	if (ret < 0)
 526		goto out;
 527
 528	digest = epayload->format + epayload->datablob_len;
 529	ret = calc_hmac(digest, derived_key, sizeof derived_key,
 530			epayload->format, epayload->datablob_len);
 531	if (!ret)
 532		dump_hmac(NULL, digest, HASH_SIZE);
 533out:
 534	return ret;
 535}
 536
 537/* verify HMAC before decrypting encrypted key */
 538static int datablob_hmac_verify(struct encrypted_key_payload *epayload,
 539				const u8 *format, const u8 *master_key,
 540				size_t master_keylen)
 541{
 542	u8 derived_key[HASH_SIZE];
 543	u8 digest[HASH_SIZE];
 544	int ret;
 545	char *p;
 546	unsigned short len;
 547
 548	ret = get_derived_key(derived_key, AUTH_KEY, master_key, master_keylen);
 549	if (ret < 0)
 550		goto out;
 551
 552	len = epayload->datablob_len;
 553	if (!format) {
 554		p = epayload->master_desc;
 555		len -= strlen(epayload->format) + 1;
 556	} else
 557		p = epayload->format;
 558
 559	ret = calc_hmac(digest, derived_key, sizeof derived_key, p, len);
 560	if (ret < 0)
 561		goto out;
 562	ret = memcmp(digest, epayload->format + epayload->datablob_len,
 563		     sizeof digest);
 564	if (ret) {
 565		ret = -EINVAL;
 566		dump_hmac("datablob",
 567			  epayload->format + epayload->datablob_len,
 568			  HASH_SIZE);
 569		dump_hmac("calc", digest, HASH_SIZE);
 570	}
 571out:
 572	return ret;
 573}
 574
 575static int derived_key_decrypt(struct encrypted_key_payload *epayload,
 576			       const u8 *derived_key,
 577			       unsigned int derived_keylen)
 578{
 579	struct scatterlist sg_in[1];
 580	struct scatterlist sg_out[2];
 581	struct crypto_skcipher *tfm;
 582	struct skcipher_request *req;
 583	unsigned int encrypted_datalen;
 584	char pad[16];
 585	int ret;
 586
 587	encrypted_datalen = roundup(epayload->decrypted_datalen, blksize);
 588	req = init_skcipher_req(derived_key, derived_keylen);
 589	ret = PTR_ERR(req);
 590	if (IS_ERR(req))
 591		goto out;
 592	dump_encrypted_data(epayload, encrypted_datalen);
 593
 594	memset(pad, 0, sizeof pad);
 595	sg_init_table(sg_in, 1);
 596	sg_init_table(sg_out, 2);
 597	sg_set_buf(sg_in, epayload->encrypted_data, encrypted_datalen);
 598	sg_set_buf(&sg_out[0], epayload->decrypted_data,
 599		   epayload->decrypted_datalen);
 600	sg_set_buf(&sg_out[1], pad, sizeof pad);
 601
 602	skcipher_request_set_crypt(req, sg_in, sg_out, encrypted_datalen,
 603				   epayload->iv);
 604	ret = crypto_skcipher_decrypt(req);
 605	tfm = crypto_skcipher_reqtfm(req);
 606	skcipher_request_free(req);
 607	crypto_free_skcipher(tfm);
 608	if (ret < 0)
 609		goto out;
 610	dump_decrypted_data(epayload);
 611out:
 612	return ret;
 613}
 614
 615/* Allocate memory for decrypted key and datablob. */
 616static struct encrypted_key_payload *encrypted_key_alloc(struct key *key,
 617							 const char *format,
 618							 const char *master_desc,
 619							 const char *datalen)
 620{
 621	struct encrypted_key_payload *epayload = NULL;
 622	unsigned short datablob_len;
 623	unsigned short decrypted_datalen;
 624	unsigned short payload_datalen;
 625	unsigned int encrypted_datalen;
 626	unsigned int format_len;
 627	long dlen;
 628	int ret;
 629
 630	ret = kstrtol(datalen, 10, &dlen);
 631	if (ret < 0 || dlen < MIN_DATA_SIZE || dlen > MAX_DATA_SIZE)
 632		return ERR_PTR(-EINVAL);
 633
 634	format_len = (!format) ? strlen(key_format_default) : strlen(format);
 635	decrypted_datalen = dlen;
 636	payload_datalen = decrypted_datalen;
 637	if (format && !strcmp(format, key_format_ecryptfs)) {
 638		if (dlen != ECRYPTFS_MAX_KEY_BYTES) {
 639			pr_err("encrypted_key: keylen for the ecryptfs format "
 640			       "must be equal to %d bytes\n",
 641			       ECRYPTFS_MAX_KEY_BYTES);
 642			return ERR_PTR(-EINVAL);
 643		}
 644		decrypted_datalen = ECRYPTFS_MAX_KEY_BYTES;
 645		payload_datalen = sizeof(struct ecryptfs_auth_tok);
 646	}
 647
 648	encrypted_datalen = roundup(decrypted_datalen, blksize);
 649
 650	datablob_len = format_len + 1 + strlen(master_desc) + 1
 651	    + strlen(datalen) + 1 + ivsize + 1 + encrypted_datalen;
 652
 653	ret = key_payload_reserve(key, payload_datalen + datablob_len
 654				  + HASH_SIZE + 1);
 655	if (ret < 0)
 656		return ERR_PTR(ret);
 657
 658	epayload = kzalloc(sizeof(*epayload) + payload_datalen +
 659			   datablob_len + HASH_SIZE + 1, GFP_KERNEL);
 660	if (!epayload)
 661		return ERR_PTR(-ENOMEM);
 662
 663	epayload->payload_datalen = payload_datalen;
 664	epayload->decrypted_datalen = decrypted_datalen;
 665	epayload->datablob_len = datablob_len;
 666	return epayload;
 667}
 668
 669static int encrypted_key_decrypt(struct encrypted_key_payload *epayload,
 670				 const char *format, const char *hex_encoded_iv)
 671{
 672	struct key *mkey;
 673	u8 derived_key[HASH_SIZE];
 674	const u8 *master_key;
 675	u8 *hmac;
 676	const char *hex_encoded_data;
 677	unsigned int encrypted_datalen;
 678	size_t master_keylen;
 679	size_t asciilen;
 680	int ret;
 681
 682	encrypted_datalen = roundup(epayload->decrypted_datalen, blksize);
 683	asciilen = (ivsize + 1 + encrypted_datalen + HASH_SIZE) * 2;
 684	if (strlen(hex_encoded_iv) != asciilen)
 685		return -EINVAL;
 686
 687	hex_encoded_data = hex_encoded_iv + (2 * ivsize) + 2;
 688	ret = hex2bin(epayload->iv, hex_encoded_iv, ivsize);
 689	if (ret < 0)
 690		return -EINVAL;
 691	ret = hex2bin(epayload->encrypted_data, hex_encoded_data,
 692		      encrypted_datalen);
 693	if (ret < 0)
 694		return -EINVAL;
 695
 696	hmac = epayload->format + epayload->datablob_len;
 697	ret = hex2bin(hmac, hex_encoded_data + (encrypted_datalen * 2),
 698		      HASH_SIZE);
 699	if (ret < 0)
 700		return -EINVAL;
 701
 702	mkey = request_master_key(epayload, &master_key, &master_keylen);
 703	if (IS_ERR(mkey))
 704		return PTR_ERR(mkey);
 705
 706	ret = datablob_hmac_verify(epayload, format, master_key, master_keylen);
 707	if (ret < 0) {
 708		pr_err("encrypted_key: bad hmac (%d)\n", ret);
 709		goto out;
 710	}
 711
 712	ret = get_derived_key(derived_key, ENC_KEY, master_key, master_keylen);
 713	if (ret < 0)
 714		goto out;
 715
 716	ret = derived_key_decrypt(epayload, derived_key, sizeof derived_key);
 717	if (ret < 0)
 718		pr_err("encrypted_key: failed to decrypt key (%d)\n", ret);
 719out:
 720	up_read(&mkey->sem);
 721	key_put(mkey);
 722	return ret;
 723}
 724
 725static void __ekey_init(struct encrypted_key_payload *epayload,
 726			const char *format, const char *master_desc,
 727			const char *datalen)
 728{
 729	unsigned int format_len;
 730
 731	format_len = (!format) ? strlen(key_format_default) : strlen(format);
 732	epayload->format = epayload->payload_data + epayload->payload_datalen;
 733	epayload->master_desc = epayload->format + format_len + 1;
 734	epayload->datalen = epayload->master_desc + strlen(master_desc) + 1;
 735	epayload->iv = epayload->datalen + strlen(datalen) + 1;
 736	epayload->encrypted_data = epayload->iv + ivsize + 1;
 737	epayload->decrypted_data = epayload->payload_data;
 738
 739	if (!format)
 740		memcpy(epayload->format, key_format_default, format_len);
 741	else {
 742		if (!strcmp(format, key_format_ecryptfs))
 743			epayload->decrypted_data =
 744				ecryptfs_get_auth_tok_key((struct ecryptfs_auth_tok *)epayload->payload_data);
 745
 746		memcpy(epayload->format, format, format_len);
 747	}
 748
 749	memcpy(epayload->master_desc, master_desc, strlen(master_desc));
 750	memcpy(epayload->datalen, datalen, strlen(datalen));
 751}
 752
 753/*
 754 * encrypted_init - initialize an encrypted key
 755 *
 756 * For a new key, use a random number for both the iv and data
 757 * itself.  For an old key, decrypt the hex encoded data.
 758 */
 759static int encrypted_init(struct encrypted_key_payload *epayload,
 760			  const char *key_desc, const char *format,
 761			  const char *master_desc, const char *datalen,
 762			  const char *hex_encoded_iv)
 763{
 764	int ret = 0;
 765
 766	if (format && !strcmp(format, key_format_ecryptfs)) {
 767		ret = valid_ecryptfs_desc(key_desc);
 768		if (ret < 0)
 769			return ret;
 770
 771		ecryptfs_fill_auth_tok((struct ecryptfs_auth_tok *)epayload->payload_data,
 772				       key_desc);
 773	}
 774
 775	__ekey_init(epayload, format, master_desc, datalen);
 776	if (!hex_encoded_iv) {
 777		get_random_bytes(epayload->iv, ivsize);
 778
 779		get_random_bytes(epayload->decrypted_data,
 780				 epayload->decrypted_datalen);
 781	} else
 782		ret = encrypted_key_decrypt(epayload, format, hex_encoded_iv);
 783	return ret;
 784}
 785
 786/*
 787 * encrypted_instantiate - instantiate an encrypted key
 788 *
 789 * Decrypt an existing encrypted datablob or create a new encrypted key
 790 * based on a kernel random number.
 791 *
 792 * On success, return 0. Otherwise return errno.
 793 */
 794static int encrypted_instantiate(struct key *key,
 795				 struct key_preparsed_payload *prep)
 796{
 797	struct encrypted_key_payload *epayload = NULL;
 798	char *datablob = NULL;
 799	const char *format = NULL;
 800	char *master_desc = NULL;
 801	char *decrypted_datalen = NULL;
 802	char *hex_encoded_iv = NULL;
 803	size_t datalen = prep->datalen;
 804	int ret;
 805
 806	if (datalen <= 0 || datalen > 32767 || !prep->data)
 807		return -EINVAL;
 808
 809	datablob = kmalloc(datalen + 1, GFP_KERNEL);
 810	if (!datablob)
 811		return -ENOMEM;
 812	datablob[datalen] = 0;
 813	memcpy(datablob, prep->data, datalen);
 814	ret = datablob_parse(datablob, &format, &master_desc,
 815			     &decrypted_datalen, &hex_encoded_iv);
 816	if (ret < 0)
 817		goto out;
 818
 819	epayload = encrypted_key_alloc(key, format, master_desc,
 820				       decrypted_datalen);
 821	if (IS_ERR(epayload)) {
 822		ret = PTR_ERR(epayload);
 823		goto out;
 824	}
 825	ret = encrypted_init(epayload, key->description, format, master_desc,
 826			     decrypted_datalen, hex_encoded_iv);
 827	if (ret < 0) {
 828		kfree(epayload);
 829		goto out;
 830	}
 831
 832	rcu_assign_keypointer(key, epayload);
 833out:
 834	kfree(datablob);
 835	return ret;
 836}
 837
 838static void encrypted_rcu_free(struct rcu_head *rcu)
 839{
 840	struct encrypted_key_payload *epayload;
 841
 842	epayload = container_of(rcu, struct encrypted_key_payload, rcu);
 843	memset(epayload->decrypted_data, 0, epayload->decrypted_datalen);
 844	kfree(epayload);
 845}
 846
 847/*
 848 * encrypted_update - update the master key description
 849 *
 850 * Change the master key description for an existing encrypted key.
 851 * The next read will return an encrypted datablob using the new
 852 * master key description.
 853 *
 854 * On success, return 0. Otherwise return errno.
 855 */
 856static int encrypted_update(struct key *key, struct key_preparsed_payload *prep)
 857{
 858	struct encrypted_key_payload *epayload = key->payload.data[0];
 859	struct encrypted_key_payload *new_epayload;
 860	char *buf;
 861	char *new_master_desc = NULL;
 862	const char *format = NULL;
 863	size_t datalen = prep->datalen;
 864	int ret = 0;
 865
 866	if (test_bit(KEY_FLAG_NEGATIVE, &key->flags))
 867		return -ENOKEY;
 868	if (datalen <= 0 || datalen > 32767 || !prep->data)
 869		return -EINVAL;
 870
 871	buf = kmalloc(datalen + 1, GFP_KERNEL);
 872	if (!buf)
 873		return -ENOMEM;
 874
 875	buf[datalen] = 0;
 876	memcpy(buf, prep->data, datalen);
 877	ret = datablob_parse(buf, &format, &new_master_desc, NULL, NULL);
 878	if (ret < 0)
 879		goto out;
 880
 881	ret = valid_master_desc(new_master_desc, epayload->master_desc);
 882	if (ret < 0)
 883		goto out;
 884
 885	new_epayload = encrypted_key_alloc(key, epayload->format,
 886					   new_master_desc, epayload->datalen);
 887	if (IS_ERR(new_epayload)) {
 888		ret = PTR_ERR(new_epayload);
 889		goto out;
 890	}
 891
 892	__ekey_init(new_epayload, epayload->format, new_master_desc,
 893		    epayload->datalen);
 894
 895	memcpy(new_epayload->iv, epayload->iv, ivsize);
 896	memcpy(new_epayload->payload_data, epayload->payload_data,
 897	       epayload->payload_datalen);
 898
 899	rcu_assign_keypointer(key, new_epayload);
 900	call_rcu(&epayload->rcu, encrypted_rcu_free);
 901out:
 902	kfree(buf);
 903	return ret;
 904}
 905
 906/*
 907 * encrypted_read - format and copy the encrypted data to userspace
 908 *
 909 * The resulting datablob format is:
 910 * <master-key name> <decrypted data length> <encrypted iv> <encrypted data>
 911 *
 912 * On success, return to userspace the encrypted key datablob size.
 913 */
 914static long encrypted_read(const struct key *key, char __user *buffer,
 915			   size_t buflen)
 916{
 917	struct encrypted_key_payload *epayload;
 918	struct key *mkey;
 919	const u8 *master_key;
 920	size_t master_keylen;
 921	char derived_key[HASH_SIZE];
 922	char *ascii_buf;
 923	size_t asciiblob_len;
 924	int ret;
 925
 926	epayload = rcu_dereference_key(key);
 927
 928	/* returns the hex encoded iv, encrypted-data, and hmac as ascii */
 929	asciiblob_len = epayload->datablob_len + ivsize + 1
 930	    + roundup(epayload->decrypted_datalen, blksize)
 931	    + (HASH_SIZE * 2);
 932
 933	if (!buffer || buflen < asciiblob_len)
 934		return asciiblob_len;
 935
 936	mkey = request_master_key(epayload, &master_key, &master_keylen);
 937	if (IS_ERR(mkey))
 938		return PTR_ERR(mkey);
 939
 940	ret = get_derived_key(derived_key, ENC_KEY, master_key, master_keylen);
 941	if (ret < 0)
 942		goto out;
 943
 944	ret = derived_key_encrypt(epayload, derived_key, sizeof derived_key);
 945	if (ret < 0)
 946		goto out;
 947
 948	ret = datablob_hmac_append(epayload, master_key, master_keylen);
 949	if (ret < 0)
 950		goto out;
 951
 952	ascii_buf = datablob_format(epayload, asciiblob_len);
 953	if (!ascii_buf) {
 954		ret = -ENOMEM;
 955		goto out;
 956	}
 957
 958	up_read(&mkey->sem);
 959	key_put(mkey);
 960
 961	if (copy_to_user(buffer, ascii_buf, asciiblob_len) != 0)
 962		ret = -EFAULT;
 963	kfree(ascii_buf);
 964
 965	return asciiblob_len;
 966out:
 967	up_read(&mkey->sem);
 968	key_put(mkey);
 969	return ret;
 970}
 971
 972/*
 973 * encrypted_destroy - before freeing the key, clear the decrypted data
 974 *
 975 * Before freeing the key, clear the memory containing the decrypted
 976 * key data.
 977 */
 978static void encrypted_destroy(struct key *key)
 979{
 980	struct encrypted_key_payload *epayload = key->payload.data[0];
 981
 982	if (!epayload)
 983		return;
 984
 985	memset(epayload->decrypted_data, 0, epayload->decrypted_datalen);
 986	kfree(key->payload.data[0]);
 987}
 988
 989struct key_type key_type_encrypted = {
 990	.name = "encrypted",
 991	.instantiate = encrypted_instantiate,
 992	.update = encrypted_update,
 993	.destroy = encrypted_destroy,
 994	.describe = user_describe,
 995	.read = encrypted_read,
 996};
 997EXPORT_SYMBOL_GPL(key_type_encrypted);
 998
 999static void encrypted_shash_release(void)
1000{
1001	if (hashalg)
1002		crypto_free_shash(hashalg);
1003	if (hmacalg)
1004		crypto_free_shash(hmacalg);
1005}
1006
1007static int __init encrypted_shash_alloc(void)
1008{
1009	int ret;
1010
1011	hmacalg = crypto_alloc_shash(hmac_alg, 0, CRYPTO_ALG_ASYNC);
1012	if (IS_ERR(hmacalg)) {
1013		pr_info("encrypted_key: could not allocate crypto %s\n",
1014			hmac_alg);
1015		return PTR_ERR(hmacalg);
1016	}
1017
1018	hashalg = crypto_alloc_shash(hash_alg, 0, CRYPTO_ALG_ASYNC);
1019	if (IS_ERR(hashalg)) {
1020		pr_info("encrypted_key: could not allocate crypto %s\n",
1021			hash_alg);
1022		ret = PTR_ERR(hashalg);
1023		goto hashalg_fail;
1024	}
1025
1026	return 0;
1027
1028hashalg_fail:
1029	crypto_free_shash(hmacalg);
1030	return ret;
1031}
1032
1033static int __init init_encrypted(void)
1034{
1035	int ret;
1036
1037	ret = encrypted_shash_alloc();
1038	if (ret < 0)
1039		return ret;
1040	ret = aes_get_sizes();
1041	if (ret < 0)
1042		goto out;
1043	ret = register_key_type(&key_type_encrypted);
1044	if (ret < 0)
1045		goto out;
1046	return 0;
1047out:
1048	encrypted_shash_release();
1049	return ret;
1050
1051}
1052
1053static void __exit cleanup_encrypted(void)
1054{
1055	encrypted_shash_release();
1056	unregister_key_type(&key_type_encrypted);
1057}
1058
1059late_initcall(init_encrypted);
1060module_exit(cleanup_encrypted);
1061
1062MODULE_LICENSE("GPL");