[deliverable/linux.git] / fs / ext4 / crypto_key.c

/*
 * linux/fs/ext4/crypto_key.c
 *
 * Copyright (C) 2015, Google, Inc.
 *
 * This contains encryption key functions for ext4
 *
 * Written by Michael Halcrow, Ildar Muslukhov, and Uday Savagaonkar, 2015.
 */

#include <keys/encrypted-type.h>
#include <keys/user-type.h>
#include <linux/random.h>
#include <linux/scatterlist.h>
#include <uapi/linux/keyctl.h>

#include "ext4.h"
#include "xattr.h"

static void derive_crypt_complete(struct crypto_async_request *req, int rc)
{
	struct ext4_completion_result *ecr = req->data;

	if (rc == -EINPROGRESS)
		return;

	ecr->res = rc;
	complete(&ecr->completion);
}

/**
 * ext4_derive_key_aes() - Derive a key using AES-128-ECB
 * @deriving_key: Encryption key used for derivatio.
 * @source_key:   Source key to which to apply derivation.
 * @derived_key:  Derived key.
 *
 * Return: Zero on success; non-zero otherwise.
 */
static int ext4_derive_key_aes(char deriving_key[EXT4_AES_128_ECB_KEY_SIZE],
			       char source_key[EXT4_AES_256_XTS_KEY_SIZE],
			       char derived_key[EXT4_AES_256_XTS_KEY_SIZE])
{
	int res = 0;
	struct ablkcipher_request *req = NULL;
	DECLARE_EXT4_COMPLETION_RESULT(ecr);
	struct scatterlist src_sg, dst_sg;
	struct crypto_ablkcipher *tfm = crypto_alloc_ablkcipher("ecb(aes)", 0,
								0);

	if (IS_ERR(tfm)) {
		res = PTR_ERR(tfm);
		tfm = NULL;
		goto out;
	}
	crypto_ablkcipher_set_flags(tfm, CRYPTO_TFM_REQ_WEAK_KEY);
	req = ablkcipher_request_alloc(tfm, GFP_NOFS);
	if (!req) {
		res = -ENOMEM;
		goto out;
	}
	ablkcipher_request_set_callback(req,
			CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
			derive_crypt_complete, &ecr);
	res = crypto_ablkcipher_setkey(tfm, deriving_key,
				       EXT4_AES_128_ECB_KEY_SIZE);
	if (res < 0)
		goto out;
	sg_init_one(&src_sg, source_key, EXT4_AES_256_XTS_KEY_SIZE);
	sg_init_one(&dst_sg, derived_key, EXT4_AES_256_XTS_KEY_SIZE);
	ablkcipher_request_set_crypt(req, &src_sg, &dst_sg,
				     EXT4_AES_256_XTS_KEY_SIZE, NULL);
	res = crypto_ablkcipher_encrypt(req);
	if (res == -EINPROGRESS || res == -EBUSY) {
		BUG_ON(req->base.data != &ecr);
		wait_for_completion(&ecr.completion);
		res = ecr.res;
	}

out:
	if (req)
		ablkcipher_request_free(req);
	if (tfm)
		crypto_free_ablkcipher(tfm);
	return res;
}

void ext4_free_encryption_info(struct inode *inode)
{
	struct ext4_inode_info *ei = EXT4_I(inode);
	struct ext4_crypt_info *ci = ei->i_crypt_info;

	if (!ci)
		return;

	if (ci->ci_keyring_key)
		key_put(ci->ci_keyring_key);
	crypto_free_ablkcipher(ci->ci_ctfm);
	memzero_explicit(&ci->ci_raw, sizeof(ci->ci_raw));
	kmem_cache_free(ext4_crypt_info_cachep, ci);
	ei->i_crypt_info = NULL;
}

int _ext4_get_encryption_info(struct inode *inode)
{
	struct ext4_inode_info *ei = EXT4_I(inode);
	struct ext4_crypt_info *crypt_info;
	char full_key_descriptor[EXT4_KEY_DESC_PREFIX_SIZE +
				 (EXT4_KEY_DESCRIPTOR_SIZE * 2) + 1];
	struct key *keyring_key = NULL;
	struct ext4_encryption_key *master_key;
	struct ext4_encryption_context ctx;
	struct user_key_payload *ukp;
	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
	int res;

	if (!ext4_read_workqueue) {
		res = ext4_init_crypto();
		if (res)
			return res;
	}

	if (ei->i_crypt_info) {
		if (!ei->i_crypt_info->ci_keyring_key ||
		    key_validate(ei->i_crypt_info->ci_keyring_key) == 0)
			return 0;
		ext4_free_encryption_info(inode);
	}

	res = ext4_xattr_get(inode, EXT4_XATTR_INDEX_ENCRYPTION,
				 EXT4_XATTR_NAME_ENCRYPTION_CONTEXT,
				 &ctx, sizeof(ctx));
	if (res < 0) {
		if (!DUMMY_ENCRYPTION_ENABLED(sbi))
			return res;
		ctx.contents_encryption_mode = EXT4_ENCRYPTION_MODE_AES_256_XTS;
		ctx.filenames_encryption_mode =
			EXT4_ENCRYPTION_MODE_AES_256_CTS;
		ctx.flags = 0;
	} else if (res != sizeof(ctx))
		return -EINVAL;
	res = 0;

	crypt_info = kmem_cache_alloc(ext4_crypt_info_cachep, GFP_KERNEL);
	if (!crypt_info)
		return -ENOMEM;

	ei->i_crypt_policy_flags = ctx.flags;
	crypt_info->ci_flags = ctx.flags;
	crypt_info->ci_data_mode = ctx.contents_encryption_mode;
	crypt_info->ci_filename_mode = ctx.filenames_encryption_mode;
	crypt_info->ci_ctfm = NULL;
	memcpy(crypt_info->ci_master_key, ctx.master_key_descriptor,
	       sizeof(crypt_info->ci_master_key));
	if (S_ISREG(inode->i_mode))
		crypt_info->ci_mode = ctx.contents_encryption_mode;
	else if (S_ISDIR(inode->i_mode) || S_ISLNK(inode->i_mode))
		crypt_info->ci_mode = ctx.filenames_encryption_mode;
	else {
		printk(KERN_ERR "ext4 crypto: Unsupported inode type.\n");
		BUG();
	}
	crypt_info->ci_size = ext4_encryption_key_size(crypt_info->ci_mode);
	BUG_ON(!crypt_info->ci_size);
	if (DUMMY_ENCRYPTION_ENABLED(sbi)) {
		memset(crypt_info->ci_raw, 0x42, EXT4_AES_256_XTS_KEY_SIZE);
		goto out;
	}
	memcpy(full_key_descriptor, EXT4_KEY_DESC_PREFIX,
	       EXT4_KEY_DESC_PREFIX_SIZE);
	sprintf(full_key_descriptor + EXT4_KEY_DESC_PREFIX_SIZE,
		"%*phN", EXT4_KEY_DESCRIPTOR_SIZE,
		ctx.master_key_descriptor);
	full_key_descriptor[EXT4_KEY_DESC_PREFIX_SIZE +
			    (2 * EXT4_KEY_DESCRIPTOR_SIZE)] = '\0';
	keyring_key = request_key(&key_type_logon, full_key_descriptor, NULL);
	if (IS_ERR(keyring_key)) {
		res = PTR_ERR(keyring_key);
		keyring_key = NULL;
		goto out;
	}
	BUG_ON(keyring_key->type != &key_type_logon);
	ukp = ((struct user_key_payload *)keyring_key->payload.data);
	if (ukp->datalen != sizeof(struct ext4_encryption_key)) {
		res = -EINVAL;
		goto out;
	}
	master_key = (struct ext4_encryption_key *)ukp->data;
	BUILD_BUG_ON(EXT4_AES_128_ECB_KEY_SIZE !=
		     EXT4_KEY_DERIVATION_NONCE_SIZE);
	BUG_ON(master_key->size != EXT4_AES_256_XTS_KEY_SIZE);
	res = ext4_derive_key_aes(ctx.nonce, master_key->raw,
				  crypt_info->ci_raw);
out:
	if (res < 0) {
		if (res == -ENOKEY)
			res = 0;
		kmem_cache_free(ext4_crypt_info_cachep, crypt_info);
	} else {
		ei->i_crypt_info = crypt_info;
		crypt_info->ci_keyring_key = keyring_key;
		keyring_key = NULL;
	}
	if (keyring_key)
		key_put(keyring_key);
	return res;
}

int ext4_has_encryption_key(struct inode *inode)
{
	struct ext4_inode_info *ei = EXT4_I(inode);

	return (ei->i_crypt_info != NULL);
}
Commit	Line	Data
88bd6ccd MH	1	/*
	2	* linux/fs/ext4/crypto_key.c
	3	*
	4	* Copyright (C) 2015, Google, Inc.
	5	*
	6	* This contains encryption key functions for ext4
	7	*
	8	* Written by Michael Halcrow, Ildar Muslukhov, and Uday Savagaonkar, 2015.
	9	*/
	10
	11	#include <keys/encrypted-type.h>
	12	#include <keys/user-type.h>
	13	#include <linux/random.h>
	14	#include <linux/scatterlist.h>
	15	#include <uapi/linux/keyctl.h>
	16
	17	#include "ext4.h"
	18	#include "xattr.h"
	19
	20	static void derive_crypt_complete(struct crypto_async_request *req, int rc)
	21	{
	22	struct ext4_completion_result *ecr = req->data;
	23
	24	if (rc == -EINPROGRESS)
	25	return;
	26
	27	ecr->res = rc;
	28	complete(&ecr->completion);
	29	}
	30
	31	/**
	32	* ext4_derive_key_aes() - Derive a key using AES-128-ECB
	33	* @deriving_key: Encryption key used for derivatio.
	34	* @source_key: Source key to which to apply derivation.
	35	* @derived_key: Derived key.
	36	*
	37	* Return: Zero on success; non-zero otherwise.
	38	*/
	39	static int ext4_derive_key_aes(char deriving_key[EXT4_AES_128_ECB_KEY_SIZE],
	40	char source_key[EXT4_AES_256_XTS_KEY_SIZE],
	41	char derived_key[EXT4_AES_256_XTS_KEY_SIZE])
	42	{
	43	int res = 0;
	44	struct ablkcipher_request *req = NULL;
	45	DECLARE_EXT4_COMPLETION_RESULT(ecr);
	46	struct scatterlist src_sg, dst_sg;
	47	struct crypto_ablkcipher *tfm = crypto_alloc_ablkcipher("ecb(aes)", 0,
	48	0);
	49
	50	if (IS_ERR(tfm)) {
	51	res = PTR_ERR(tfm);
	52	tfm = NULL;
	53	goto out;
	54	}
	55	crypto_ablkcipher_set_flags(tfm, CRYPTO_TFM_REQ_WEAK_KEY);
	56	req = ablkcipher_request_alloc(tfm, GFP_NOFS);
	57	if (!req) {
	58	res = -ENOMEM;
	59	goto out;
	60	}
	61	ablkcipher_request_set_callback(req,
	62	CRYPTO_TFM_REQ_MAY_BACKLOG \| CRYPTO_TFM_REQ_MAY_SLEEP,
	63	derive_crypt_complete, &ecr);
	64	res = crypto_ablkcipher_setkey(tfm, deriving_key,
65	EXT4_AES_128_ECB_KEY_SIZE);
66	if (res < 0)
67	goto out;
68	sg_init_one(&src_sg, source_key, EXT4_AES_256_XTS_KEY_SIZE);
69	sg_init_one(&dst_sg, derived_key, EXT4_AES_256_XTS_KEY_SIZE);
70	ablkcipher_request_set_crypt(req, &src_sg, &dst_sg,
71	EXT4_AES_256_XTS_KEY_SIZE, NULL);
72	res = crypto_ablkcipher_encrypt(req);
73	if (res == -EINPROGRESS \|\| res == -EBUSY) {
74	BUG_ON(req->base.data != &ecr);
75	wait_for_completion(&ecr.completion);
76	res = ecr.res;
77	}
78
79	out:
80	if (req)
81	ablkcipher_request_free(req);
82	if (tfm)
83	crypto_free_ablkcipher(tfm);
84	return res;
85	}
86
b7236e21 TT	87	void ext4_free_encryption_info(struct inode *inode)
	88	{
	89	struct ext4_inode_info *ei = EXT4_I(inode);
	90	struct ext4_crypt_info *ci = ei->i_crypt_info;
	91
	92	if (!ci)
	93	return;
	94
	95	if (ci->ci_keyring_key)
	96	key_put(ci->ci_keyring_key);
	97	crypto_free_ablkcipher(ci->ci_ctfm);
	98	memzero_explicit(&ci->ci_raw, sizeof(ci->ci_raw));
8ee03714	99	kmem_cache_free(ext4_crypt_info_cachep, ci);
b7236e21 TT	100	ei->i_crypt_info = NULL;
	101	}
	102
	103	int _ext4_get_encryption_info(struct inode *inode)
88bd6ccd MH	104	{
88bd6ccd MH	105	struct ext4_inode_info *ei = EXT4_I(inode);
b7236e21	106	struct ext4_crypt_info *crypt_info;
88bd6ccd MH	107	char full_key_descriptor[EXT4_KEY_DESC_PREFIX_SIZE +
	108	(EXT4_KEY_DESCRIPTOR_SIZE * 2) + 1];
	109	struct key *keyring_key = NULL;
	110	struct ext4_encryption_key *master_key;
	111	struct ext4_encryption_context ctx;
	112	struct user_key_payload *ukp;
6ddb2447	113	struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
b7236e21	114	int res;
88bd6ccd	115
8ee03714 TT	116	if (!ext4_read_workqueue) {
	117	res = ext4_init_crypto();
	118	if (res)
	119	return res;
	120	}
	121
b7236e21 TT	122	if (ei->i_crypt_info) {
	123	if (!ei->i_crypt_info->ci_keyring_key \|\|
	124	key_validate(ei->i_crypt_info->ci_keyring_key) == 0)
	125	return 0;
	126	ext4_free_encryption_info(inode);
88bd6ccd	127	}
b7236e21 TT	128
	129	res = ext4_xattr_get(inode, EXT4_XATTR_INDEX_ENCRYPTION,
	130	EXT4_XATTR_NAME_ENCRYPTION_CONTEXT,
	131	&ctx, sizeof(ctx));
	132	if (res < 0) {
	133	if (!DUMMY_ENCRYPTION_ENABLED(sbi))
	134	return res;
	135	ctx.contents_encryption_mode = EXT4_ENCRYPTION_MODE_AES_256_XTS;
	136	ctx.filenames_encryption_mode =
	137	EXT4_ENCRYPTION_MODE_AES_256_CTS;
	138	ctx.flags = 0;
	139	} else if (res != sizeof(ctx))
	140	return -EINVAL;
88bd6ccd MH	141	res = 0;
88bd6ccd MH	142
8ee03714	143	crypt_info = kmem_cache_alloc(ext4_crypt_info_cachep, GFP_KERNEL);
b7236e21 TT	144	if (!crypt_info)
	145	return -ENOMEM;
	146
a44cd7a0	147	ei->i_crypt_policy_flags = ctx.flags;
b7236e21 TT	148	crypt_info->ci_flags = ctx.flags;
	149	crypt_info->ci_data_mode = ctx.contents_encryption_mode;
	150	crypt_info->ci_filename_mode = ctx.filenames_encryption_mode;
	151	crypt_info->ci_ctfm = NULL;
	152	memcpy(crypt_info->ci_master_key, ctx.master_key_descriptor,
	153	sizeof(crypt_info->ci_master_key));
6ddb2447	154	if (S_ISREG(inode->i_mode))
e2881b1b	155	crypt_info->ci_mode = ctx.contents_encryption_mode;
6ddb2447	156	else if (S_ISDIR(inode->i_mode) \|\| S_ISLNK(inode->i_mode))
e2881b1b	157	crypt_info->ci_mode = ctx.filenames_encryption_mode;
6ddb2447 TT	158	else {
	159	printk(KERN_ERR "ext4 crypto: Unsupported inode type.\n");
	160	BUG();
	161	}
e2881b1b TT	162	crypt_info->ci_size = ext4_encryption_key_size(crypt_info->ci_mode);
e2881b1b TT	163	BUG_ON(!crypt_info->ci_size);
6ddb2447	164	if (DUMMY_ENCRYPTION_ENABLED(sbi)) {
e2881b1b	165	memset(crypt_info->ci_raw, 0x42, EXT4_AES_256_XTS_KEY_SIZE);
6ddb2447 TT	166	goto out;
6ddb2447 TT	167	}
88bd6ccd MH	168	memcpy(full_key_descriptor, EXT4_KEY_DESC_PREFIX,
	169	EXT4_KEY_DESC_PREFIX_SIZE);
	170	sprintf(full_key_descriptor + EXT4_KEY_DESC_PREFIX_SIZE,
	171	"%*phN", EXT4_KEY_DESCRIPTOR_SIZE,
	172	ctx.master_key_descriptor);
	173	full_key_descriptor[EXT4_KEY_DESC_PREFIX_SIZE +
	174	(2 * EXT4_KEY_DESCRIPTOR_SIZE)] = '\0';
	175	keyring_key = request_key(&key_type_logon, full_key_descriptor, NULL);
	176	if (IS_ERR(keyring_key)) {
	177	res = PTR_ERR(keyring_key);
	178	keyring_key = NULL;
	179	goto out;
	180	}
	181	BUG_ON(keyring_key->type != &key_type_logon);
	182	ukp = ((struct user_key_payload *)keyring_key->payload.data);
	183	if (ukp->datalen != sizeof(struct ext4_encryption_key)) {
	184	res = -EINVAL;
	185	goto out;
	186	}
	187	master_key = (struct ext4_encryption_key *)ukp->data;
88bd6ccd MH	188	BUILD_BUG_ON(EXT4_AES_128_ECB_KEY_SIZE !=
	189	EXT4_KEY_DERIVATION_NONCE_SIZE);
	190	BUG_ON(master_key->size != EXT4_AES_256_XTS_KEY_SIZE);
e2881b1b TT	191	res = ext4_derive_key_aes(ctx.nonce, master_key->raw,
e2881b1b TT	192	crypt_info->ci_raw);
88bd6ccd	193	out:
b7236e21 TT	194	if (res < 0) {
	195	if (res == -ENOKEY)
	196	res = 0;
8ee03714	197	kmem_cache_free(ext4_crypt_info_cachep, crypt_info);
b7236e21 TT	198	} else {
	199	ei->i_crypt_info = crypt_info;
	200	crypt_info->ci_keyring_key = keyring_key;
	201	keyring_key = NULL;
	202	}
88bd6ccd MH	203	if (keyring_key)
88bd6ccd MH	204	key_put(keyring_key);
88bd6ccd MH	205	return res;
	206	}
	207
	208	int ext4_has_encryption_key(struct inode *inode)
	209	{
	210	struct ext4_inode_info *ei = EXT4_I(inode);
88bd6ccd	211
b7236e21	212	return (ei->i_crypt_info != NULL);
88bd6ccd	213	}