[deliverable/linux.git] / fs / f2fs / crypto_key.c

/*
 * linux/fs/f2fs/crypto_key.c
 *
 * Copied from linux/fs/f2fs/crypto_key.c
 *
 * Copyright (C) 2015, Google, Inc.
 *
 * This contains encryption key functions for f2fs
 *
 * 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 <crypto/hash.h>
#include <linux/f2fs_fs.h>

#include "f2fs.h"
#include "xattr.h"

static void derive_crypt_complete(struct crypto_async_request *req, int rc)
{
	struct f2fs_completion_result *ecr = req->data;

	if (rc == -EINPROGRESS)
		return;

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

/**
 * f2fs_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 f2fs_derive_key_aes(char deriving_key[F2FS_AES_128_ECB_KEY_SIZE],
				char source_key[F2FS_AES_256_XTS_KEY_SIZE],
				char derived_key[F2FS_AES_256_XTS_KEY_SIZE])
{
	int res = 0;
	struct ablkcipher_request *req = NULL;
	DECLARE_F2FS_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,
				F2FS_AES_128_ECB_KEY_SIZE);
	if (res < 0)
		goto out;

	sg_init_one(&src_sg, source_key, F2FS_AES_256_XTS_KEY_SIZE);
	sg_init_one(&dst_sg, derived_key, F2FS_AES_256_XTS_KEY_SIZE);
	ablkcipher_request_set_crypt(req, &src_sg, &dst_sg,
					F2FS_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;
}

static void f2fs_free_crypt_info(struct f2fs_crypt_info *ci)
{
	if (!ci)
		return;

	key_put(ci->ci_keyring_key);
	crypto_free_ablkcipher(ci->ci_ctfm);
	kmem_cache_free(f2fs_crypt_info_cachep, ci);
}

void f2fs_free_encryption_info(struct inode *inode, struct f2fs_crypt_info *ci)
{
	struct f2fs_inode_info *fi = F2FS_I(inode);
	struct f2fs_crypt_info *prev;

	if (ci == NULL)
		ci = ACCESS_ONCE(fi->i_crypt_info);
	if (ci == NULL)
		return;
	prev = cmpxchg(&fi->i_crypt_info, ci, NULL);
	if (prev != ci)
		return;

	f2fs_free_crypt_info(ci);
}

int _f2fs_get_encryption_info(struct inode *inode)
{
	struct f2fs_inode_info *fi = F2FS_I(inode);
	struct f2fs_crypt_info *crypt_info;
	char full_key_descriptor[F2FS_KEY_DESC_PREFIX_SIZE +
				(F2FS_KEY_DESCRIPTOR_SIZE * 2) + 1];
	struct key *keyring_key = NULL;
	struct f2fs_encryption_key *master_key;
	struct f2fs_encryption_context ctx;
	struct user_key_payload *ukp;
	struct crypto_ablkcipher *ctfm;
	const char *cipher_str;
	char raw_key[F2FS_MAX_KEY_SIZE];
	char mode;
	int res;

	res = f2fs_crypto_initialize();
	if (res)
		return res;
retry:
	crypt_info = ACCESS_ONCE(fi->i_crypt_info);
	if (crypt_info) {
		if (!crypt_info->ci_keyring_key ||
				key_validate(crypt_info->ci_keyring_key) == 0)
			return 0;
		f2fs_free_encryption_info(inode, crypt_info);
		goto retry;
	}

	res = f2fs_getxattr(inode, F2FS_XATTR_INDEX_ENCRYPTION,
				F2FS_XATTR_NAME_ENCRYPTION_CONTEXT,
				&ctx, sizeof(ctx), NULL);
	if (res < 0)
		return res;
	else if (res != sizeof(ctx))
		return -EINVAL;
	res = 0;

	crypt_info = kmem_cache_alloc(f2fs_crypt_info_cachep, GFP_NOFS);
	if (!crypt_info)
		return -ENOMEM;

	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;
	crypt_info->ci_keyring_key = NULL;
	memcpy(crypt_info->ci_master_key, ctx.master_key_descriptor,
				sizeof(crypt_info->ci_master_key));
	if (S_ISREG(inode->i_mode))
		mode = crypt_info->ci_data_mode;
	else if (S_ISDIR(inode->i_mode) || S_ISLNK(inode->i_mode))
		mode = crypt_info->ci_filename_mode;
	else
		BUG();

	switch (mode) {
	case F2FS_ENCRYPTION_MODE_AES_256_XTS:
		cipher_str = "xts(aes)";
		break;
	case F2FS_ENCRYPTION_MODE_AES_256_CTS:
		cipher_str = "cts(cbc(aes))";
		break;
	default:
		printk_once(KERN_WARNING
			    "f2fs: unsupported key mode %d (ino %u)\n",
			    mode, (unsigned) inode->i_ino);
		res = -ENOKEY;
		goto out;
	}

	memcpy(full_key_descriptor, F2FS_KEY_DESC_PREFIX,
					F2FS_KEY_DESC_PREFIX_SIZE);
	sprintf(full_key_descriptor + F2FS_KEY_DESC_PREFIX_SIZE,
					"%*phN", F2FS_KEY_DESCRIPTOR_SIZE,
					ctx.master_key_descriptor);
	full_key_descriptor[F2FS_KEY_DESC_PREFIX_SIZE +
					(2 * F2FS_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;
	}
	crypt_info->ci_keyring_key = keyring_key;
	BUG_ON(keyring_key->type != &key_type_logon);
	ukp = ((struct user_key_payload *)keyring_key->payload.data);
	if (ukp->datalen != sizeof(struct f2fs_encryption_key)) {
		res = -EINVAL;
		goto out;
	}
	master_key = (struct f2fs_encryption_key *)ukp->data;
	BUILD_BUG_ON(F2FS_AES_128_ECB_KEY_SIZE !=
				F2FS_KEY_DERIVATION_NONCE_SIZE);
	BUG_ON(master_key->size != F2FS_AES_256_XTS_KEY_SIZE);
	res = f2fs_derive_key_aes(ctx.nonce, master_key->raw,
				  raw_key);
	if (res)
		goto out;

	ctfm = crypto_alloc_ablkcipher(cipher_str, 0, 0);
	if (!ctfm || IS_ERR(ctfm)) {
		res = ctfm ? PTR_ERR(ctfm) : -ENOMEM;
		printk(KERN_DEBUG
		       "%s: error %d (inode %u) allocating crypto tfm\n",
		       __func__, res, (unsigned) inode->i_ino);
		goto out;
	}
	crypt_info->ci_ctfm = ctfm;
	crypto_ablkcipher_clear_flags(ctfm, ~0);
	crypto_tfm_set_flags(crypto_ablkcipher_tfm(ctfm),
			     CRYPTO_TFM_REQ_WEAK_KEY);
	res = crypto_ablkcipher_setkey(ctfm, raw_key,
					f2fs_encryption_key_size(mode));
	if (res)
		goto out;

	memzero_explicit(raw_key, sizeof(raw_key));
	if (cmpxchg(&fi->i_crypt_info, NULL, crypt_info) != NULL) {
		f2fs_free_crypt_info(crypt_info);
		goto retry;
	}
	return 0;

out:
	if (res == -ENOKEY && !S_ISREG(inode->i_mode))
		res = 0;

	f2fs_free_crypt_info(crypt_info);
	memzero_explicit(raw_key, sizeof(raw_key));
	return res;
}

int f2fs_has_encryption_key(struct inode *inode)
{
	struct f2fs_inode_info *fi = F2FS_I(inode);

	return (fi->i_crypt_info != NULL);
}
Commit	Line	Data
0adda907 JK	1	/*
	2	* linux/fs/f2fs/crypto_key.c
	3	*
	4	* Copied from linux/fs/f2fs/crypto_key.c
	5	*
	6	* Copyright (C) 2015, Google, Inc.
	7	*
	8	* This contains encryption key functions for f2fs
	9	*
	10	* Written by Michael Halcrow, Ildar Muslukhov, and Uday Savagaonkar, 2015.
	11	*/
	12	#include <keys/encrypted-type.h>
	13	#include <keys/user-type.h>
	14	#include <linux/random.h>
	15	#include <linux/scatterlist.h>
	16	#include <uapi/linux/keyctl.h>
	17	#include <crypto/hash.h>
	18	#include <linux/f2fs_fs.h>
	19
	20	#include "f2fs.h"
	21	#include "xattr.h"
	22
	23	static void derive_crypt_complete(struct crypto_async_request *req, int rc)
	24	{
	25	struct f2fs_completion_result *ecr = req->data;
	26
	27	if (rc == -EINPROGRESS)
	28	return;
	29
	30	ecr->res = rc;
	31	complete(&ecr->completion);
	32	}
	33
	34	/**
	35	* f2fs_derive_key_aes() - Derive a key using AES-128-ECB
	36	* @deriving_key: Encryption key used for derivatio.
	37	* @source_key: Source key to which to apply derivation.
	38	* @derived_key: Derived key.
	39	*
	40	* Return: Zero on success; non-zero otherwise.
	41	*/
	42	static int f2fs_derive_key_aes(char deriving_key[F2FS_AES_128_ECB_KEY_SIZE],
	43	char source_key[F2FS_AES_256_XTS_KEY_SIZE],
	44	char derived_key[F2FS_AES_256_XTS_KEY_SIZE])
	45	{
	46	int res = 0;
	47	struct ablkcipher_request *req = NULL;
	48	DECLARE_F2FS_COMPLETION_RESULT(ecr);
	49	struct scatterlist src_sg, dst_sg;
	50	struct crypto_ablkcipher *tfm = crypto_alloc_ablkcipher("ecb(aes)", 0,
	51	0);
	52
	53	if (IS_ERR(tfm)) {
	54	res = PTR_ERR(tfm);
	55	tfm = NULL;
	56	goto out;
	57	}
	58	crypto_ablkcipher_set_flags(tfm, CRYPTO_TFM_REQ_WEAK_KEY);
	59	req = ablkcipher_request_alloc(tfm, GFP_NOFS);
	60	if (!req) {
	61	res = -ENOMEM;
	62	goto out;
	63	}
	64	ablkcipher_request_set_callback(req,
65	CRYPTO_TFM_REQ_MAY_BACKLOG \| CRYPTO_TFM_REQ_MAY_SLEEP,
66	derive_crypt_complete, &ecr);
67	res = crypto_ablkcipher_setkey(tfm, deriving_key,
68	F2FS_AES_128_ECB_KEY_SIZE);
69	if (res < 0)
70	goto out;
71
72	sg_init_one(&src_sg, source_key, F2FS_AES_256_XTS_KEY_SIZE);
73	sg_init_one(&dst_sg, derived_key, F2FS_AES_256_XTS_KEY_SIZE);
74	ablkcipher_request_set_crypt(req, &src_sg, &dst_sg,
75	F2FS_AES_256_XTS_KEY_SIZE, NULL);
76	res = crypto_ablkcipher_encrypt(req);
77	if (res == -EINPROGRESS \|\| res == -EBUSY) {
78	BUG_ON(req->base.data != &ecr);
79	wait_for_completion(&ecr.completion);
80	res = ecr.res;
81	}
82	out:
83	if (req)
84	ablkcipher_request_free(req);
85	if (tfm)
86	crypto_free_ablkcipher(tfm);
87	return res;
88	}
89
26bf3dc7	90	static void f2fs_free_crypt_info(struct f2fs_crypt_info *ci)
0adda907	91	{
0adda907 JK	92	if (!ci)
	93	return;
	94
92859a5e	95	key_put(ci->ci_keyring_key);
0adda907	96	crypto_free_ablkcipher(ci->ci_ctfm);
8bacf6de	97	kmem_cache_free(f2fs_crypt_info_cachep, ci);
26bf3dc7 JK	98	}
	99
	100	void f2fs_free_encryption_info(struct inode inode, struct f2fs_crypt_info ci)
	101	{
	102	struct f2fs_inode_info *fi = F2FS_I(inode);
	103	struct f2fs_crypt_info *prev;
	104
	105	if (ci == NULL)
	106	ci = ACCESS_ONCE(fi->i_crypt_info);
	107	if (ci == NULL)
	108	return;
	109	prev = cmpxchg(&fi->i_crypt_info, ci, NULL);
	110	if (prev != ci)
	111	return;
	112
	113	f2fs_free_crypt_info(ci);
0adda907 JK	114	}
	115
	116	int _f2fs_get_encryption_info(struct inode *inode)
	117	{
	118	struct f2fs_inode_info *fi = F2FS_I(inode);
	119	struct f2fs_crypt_info *crypt_info;
	120	char full_key_descriptor[F2FS_KEY_DESC_PREFIX_SIZE +
	121	(F2FS_KEY_DESCRIPTOR_SIZE * 2) + 1];
	122	struct key *keyring_key = NULL;
	123	struct f2fs_encryption_key *master_key;
	124	struct f2fs_encryption_context ctx;
	125	struct user_key_payload *ukp;
26bf3dc7 JK	126	struct crypto_ablkcipher *ctfm;
	127	const char *cipher_str;
	128	char raw_key[F2FS_MAX_KEY_SIZE];
	129	char mode;
0adda907 JK	130	int res;
0adda907 JK	131
cfc4d971 JK	132	res = f2fs_crypto_initialize();
	133	if (res)
	134	return res;
26bf3dc7 JK	135	retry:
	136	crypt_info = ACCESS_ONCE(fi->i_crypt_info);
	137	if (crypt_info) {
	138	if (!crypt_info->ci_keyring_key \|\|
	139	key_validate(crypt_info->ci_keyring_key) == 0)
0adda907	140	return 0;
26bf3dc7 JK	141	f2fs_free_encryption_info(inode, crypt_info);
26bf3dc7 JK	142	goto retry;
0adda907 JK	143	}
	144
	145	res = f2fs_getxattr(inode, F2FS_XATTR_INDEX_ENCRYPTION,
	146	F2FS_XATTR_NAME_ENCRYPTION_CONTEXT,
	147	&ctx, sizeof(ctx), NULL);
	148	if (res < 0)
	149	return res;
	150	else if (res != sizeof(ctx))
	151	return -EINVAL;
	152	res = 0;
	153
8bacf6de	154	crypt_info = kmem_cache_alloc(f2fs_crypt_info_cachep, GFP_NOFS);
0adda907 JK	155	if (!crypt_info)
	156	return -ENOMEM;
	157
	158	crypt_info->ci_flags = ctx.flags;
	159	crypt_info->ci_data_mode = ctx.contents_encryption_mode;
	160	crypt_info->ci_filename_mode = ctx.filenames_encryption_mode;
	161	crypt_info->ci_ctfm = NULL;
26bf3dc7	162	crypt_info->ci_keyring_key = NULL;
0adda907 JK	163	memcpy(crypt_info->ci_master_key, ctx.master_key_descriptor,
	164	sizeof(crypt_info->ci_master_key));
	165	if (S_ISREG(inode->i_mode))
26bf3dc7	166	mode = crypt_info->ci_data_mode;
0adda907	167	else if (S_ISDIR(inode->i_mode) \|\| S_ISLNK(inode->i_mode))
26bf3dc7	168	mode = crypt_info->ci_filename_mode;
640778fb	169	else
0adda907	170	BUG();
640778fb	171
26bf3dc7 JK	172	switch (mode) {
	173	case F2FS_ENCRYPTION_MODE_AES_256_XTS:
	174	cipher_str = "xts(aes)";
	175	break;
	176	case F2FS_ENCRYPTION_MODE_AES_256_CTS:
	177	cipher_str = "cts(cbc(aes))";
	178	break;
	179	default:
	180	printk_once(KERN_WARNING
	181	"f2fs: unsupported key mode %d (ino %u)\n",
	182	mode, (unsigned) inode->i_ino);
	183	res = -ENOKEY;
	184	goto out;
	185	}
0adda907 JK	186
	187	memcpy(full_key_descriptor, F2FS_KEY_DESC_PREFIX,
	188	F2FS_KEY_DESC_PREFIX_SIZE);
	189	sprintf(full_key_descriptor + F2FS_KEY_DESC_PREFIX_SIZE,
	190	"%*phN", F2FS_KEY_DESCRIPTOR_SIZE,
	191	ctx.master_key_descriptor);
	192	full_key_descriptor[F2FS_KEY_DESC_PREFIX_SIZE +
	193	(2 * F2FS_KEY_DESCRIPTOR_SIZE)] = '\0';
	194	keyring_key = request_key(&key_type_logon, full_key_descriptor, NULL);
	195	if (IS_ERR(keyring_key)) {
	196	res = PTR_ERR(keyring_key);
	197	keyring_key = NULL;
	198	goto out;
	199	}
26bf3dc7	200	crypt_info->ci_keyring_key = keyring_key;
0adda907 JK	201	BUG_ON(keyring_key->type != &key_type_logon);
	202	ukp = ((struct user_key_payload *)keyring_key->payload.data);
	203	if (ukp->datalen != sizeof(struct f2fs_encryption_key)) {
	204	res = -EINVAL;
	205	goto out;
	206	}
	207	master_key = (struct f2fs_encryption_key *)ukp->data;
	208	BUILD_BUG_ON(F2FS_AES_128_ECB_KEY_SIZE !=
	209	F2FS_KEY_DERIVATION_NONCE_SIZE);
	210	BUG_ON(master_key->size != F2FS_AES_256_XTS_KEY_SIZE);
	211	res = f2fs_derive_key_aes(ctx.nonce, master_key->raw,
26bf3dc7 JK	212	raw_key);
	213	if (res)
	214	goto out;
	215
	216	ctfm = crypto_alloc_ablkcipher(cipher_str, 0, 0);
	217	if (!ctfm \|\| IS_ERR(ctfm)) {
	218	res = ctfm ? PTR_ERR(ctfm) : -ENOMEM;
	219	printk(KERN_DEBUG
	220	"%s: error %d (inode %u) allocating crypto tfm\n",
	221	__func__, res, (unsigned) inode->i_ino);
	222	goto out;
0adda907	223	}
26bf3dc7 JK	224	crypt_info->ci_ctfm = ctfm;
	225	crypto_ablkcipher_clear_flags(ctfm, ~0);
	226	crypto_tfm_set_flags(crypto_ablkcipher_tfm(ctfm),
	227	CRYPTO_TFM_REQ_WEAK_KEY);
	228	res = crypto_ablkcipher_setkey(ctfm, raw_key,
	229	f2fs_encryption_key_size(mode));
	230	if (res)
	231	goto out;
	232
	233	memzero_explicit(raw_key, sizeof(raw_key));
	234	if (cmpxchg(&fi->i_crypt_info, NULL, crypt_info) != NULL) {
	235	f2fs_free_crypt_info(crypt_info);
	236	goto retry;
	237	}
	238	return 0;
	239
	240	out:
	241	if (res == -ENOKEY && !S_ISREG(inode->i_mode))
	242	res = 0;
	243
	244	f2fs_free_crypt_info(crypt_info);
	245	memzero_explicit(raw_key, sizeof(raw_key));
0adda907 JK	246	return res;
	247	}
	248
	249	int f2fs_has_encryption_key(struct inode *inode)
	250	{
	251	struct f2fs_inode_info *fi = F2FS_I(inode);
	252
	253	return (fi->i_crypt_info != NULL);
	254	}