[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/skcipher.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 skcipher_request *req = NULL;
	DECLARE_F2FS_COMPLETION_RESULT(ecr);
	struct scatterlist src_sg, dst_sg;
	struct crypto_skcipher *tfm = crypto_alloc_skcipher("ecb(aes)", 0, 0);

	if (IS_ERR(tfm)) {
		res = PTR_ERR(tfm);
		tfm = NULL;
		goto out;
	}
	crypto_skcipher_set_flags(tfm, CRYPTO_TFM_REQ_WEAK_KEY);
	req = skcipher_request_alloc(tfm, GFP_NOFS);
	if (!req) {
		res = -ENOMEM;
		goto out;
	}
	skcipher_request_set_callback(req,
			CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
			derive_crypt_complete, &ecr);
	res = crypto_skcipher_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);
	skcipher_request_set_crypt(req, &src_sg, &dst_sg,
					F2FS_AES_256_XTS_KEY_SIZE, NULL);
	res = crypto_skcipher_encrypt(req);
	if (res == -EINPROGRESS || res == -EBUSY) {
		BUG_ON(req->base.data != &ecr);
		wait_for_completion(&ecr.completion);
		res = ecr.res;
	}
out:
	skcipher_request_free(req);
	crypto_free_skcipher(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_skcipher(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;
	const struct user_key_payload *ukp;
	struct crypto_skcipher *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 = user_key_payload(keyring_key);
	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_skcipher(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_skcipher_clear_flags(ctfm, ~0);
	crypto_skcipher_set_flags(ctfm, CRYPTO_TFM_REQ_WEAK_KEY);
	res = crypto_skcipher_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>
2731a944	17	#include <crypto/skcipher.h>
0adda907 JK	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;
2731a944	47	struct skcipher_request *req = NULL;
0adda907 JK	48	DECLARE_F2FS_COMPLETION_RESULT(ecr);
0adda907 JK	49	struct scatterlist src_sg, dst_sg;
2731a944	50	struct crypto_skcipher *tfm = crypto_alloc_skcipher("ecb(aes)", 0, 0);
0adda907 JK	51
	52	if (IS_ERR(tfm)) {
	53	res = PTR_ERR(tfm);
	54	tfm = NULL;
	55	goto out;
	56	}
2731a944 HX	57	crypto_skcipher_set_flags(tfm, CRYPTO_TFM_REQ_WEAK_KEY);
2731a944 HX	58	req = skcipher_request_alloc(tfm, GFP_NOFS);
0adda907 JK	59	if (!req) {
	60	res = -ENOMEM;
	61	goto out;
	62	}
2731a944	63	skcipher_request_set_callback(req,
0adda907 JK	64	CRYPTO_TFM_REQ_MAY_BACKLOG \| CRYPTO_TFM_REQ_MAY_SLEEP,
0adda907 JK	65	derive_crypt_complete, &ecr);
2731a944	66	res = crypto_skcipher_setkey(tfm, deriving_key,
0adda907 JK	67	F2FS_AES_128_ECB_KEY_SIZE);
	68	if (res < 0)
	69	goto out;
	70
	71	sg_init_one(&src_sg, source_key, F2FS_AES_256_XTS_KEY_SIZE);
	72	sg_init_one(&dst_sg, derived_key, F2FS_AES_256_XTS_KEY_SIZE);
2731a944	73	skcipher_request_set_crypt(req, &src_sg, &dst_sg,
0adda907	74	F2FS_AES_256_XTS_KEY_SIZE, NULL);
2731a944	75	res = crypto_skcipher_encrypt(req);
0adda907 JK	76	if (res == -EINPROGRESS \|\| res == -EBUSY) {
	77	BUG_ON(req->base.data != &ecr);
	78	wait_for_completion(&ecr.completion);
	79	res = ecr.res;
	80	}
	81	out:
2731a944 HX	82	skcipher_request_free(req);
2731a944 HX	83	crypto_free_skcipher(tfm);
0adda907 JK	84	return res;
	85	}
	86
26bf3dc7	87	static void f2fs_free_crypt_info(struct f2fs_crypt_info *ci)
0adda907	88	{
0adda907 JK	89	if (!ci)
	90	return;
	91
92859a5e	92	key_put(ci->ci_keyring_key);
2731a944	93	crypto_free_skcipher(ci->ci_ctfm);
8bacf6de	94	kmem_cache_free(f2fs_crypt_info_cachep, ci);
26bf3dc7 JK	95	}
	96
	97	void f2fs_free_encryption_info(struct inode inode, struct f2fs_crypt_info ci)
	98	{
	99	struct f2fs_inode_info *fi = F2FS_I(inode);
	100	struct f2fs_crypt_info *prev;
	101
	102	if (ci == NULL)
	103	ci = ACCESS_ONCE(fi->i_crypt_info);
	104	if (ci == NULL)
	105	return;
	106	prev = cmpxchg(&fi->i_crypt_info, ci, NULL);
	107	if (prev != ci)
	108	return;
	109
	110	f2fs_free_crypt_info(ci);
0adda907 JK	111	}
	112
	113	int _f2fs_get_encryption_info(struct inode *inode)
	114	{
	115	struct f2fs_inode_info *fi = F2FS_I(inode);
	116	struct f2fs_crypt_info *crypt_info;
	117	char full_key_descriptor[F2FS_KEY_DESC_PREFIX_SIZE +
	118	(F2FS_KEY_DESCRIPTOR_SIZE * 2) + 1];
	119	struct key *keyring_key = NULL;
	120	struct f2fs_encryption_key *master_key;
	121	struct f2fs_encryption_context ctx;
146aa8b1	122	const struct user_key_payload *ukp;
2731a944	123	struct crypto_skcipher *ctfm;
26bf3dc7 JK	124	const char *cipher_str;
	125	char raw_key[F2FS_MAX_KEY_SIZE];
	126	char mode;
0adda907 JK	127	int res;
0adda907 JK	128
cfc4d971 JK	129	res = f2fs_crypto_initialize();
	130	if (res)
	131	return res;
26bf3dc7 JK	132	retry:
	133	crypt_info = ACCESS_ONCE(fi->i_crypt_info);
	134	if (crypt_info) {
	135	if (!crypt_info->ci_keyring_key \|\|
	136	key_validate(crypt_info->ci_keyring_key) == 0)
0adda907	137	return 0;
26bf3dc7 JK	138	f2fs_free_encryption_info(inode, crypt_info);
26bf3dc7 JK	139	goto retry;
0adda907 JK	140	}
	141
	142	res = f2fs_getxattr(inode, F2FS_XATTR_INDEX_ENCRYPTION,
	143	F2FS_XATTR_NAME_ENCRYPTION_CONTEXT,
	144	&ctx, sizeof(ctx), NULL);
	145	if (res < 0)
	146	return res;
	147	else if (res != sizeof(ctx))
	148	return -EINVAL;
	149	res = 0;
	150
8bacf6de	151	crypt_info = kmem_cache_alloc(f2fs_crypt_info_cachep, GFP_NOFS);
0adda907 JK	152	if (!crypt_info)
	153	return -ENOMEM;
	154
	155	crypt_info->ci_flags = ctx.flags;
	156	crypt_info->ci_data_mode = ctx.contents_encryption_mode;
	157	crypt_info->ci_filename_mode = ctx.filenames_encryption_mode;
	158	crypt_info->ci_ctfm = NULL;
26bf3dc7	159	crypt_info->ci_keyring_key = NULL;
0adda907 JK	160	memcpy(crypt_info->ci_master_key, ctx.master_key_descriptor,
	161	sizeof(crypt_info->ci_master_key));
	162	if (S_ISREG(inode->i_mode))
26bf3dc7	163	mode = crypt_info->ci_data_mode;
0adda907	164	else if (S_ISDIR(inode->i_mode) \|\| S_ISLNK(inode->i_mode))
26bf3dc7	165	mode = crypt_info->ci_filename_mode;
640778fb	166	else
0adda907	167	BUG();
640778fb	168
26bf3dc7 JK	169	switch (mode) {
	170	case F2FS_ENCRYPTION_MODE_AES_256_XTS:
	171	cipher_str = "xts(aes)";
	172	break;
	173	case F2FS_ENCRYPTION_MODE_AES_256_CTS:
	174	cipher_str = "cts(cbc(aes))";
	175	break;
	176	default:
	177	printk_once(KERN_WARNING
	178	"f2fs: unsupported key mode %d (ino %u)\n",
	179	mode, (unsigned) inode->i_ino);
	180	res = -ENOKEY;
	181	goto out;
	182	}
0adda907 JK	183
	184	memcpy(full_key_descriptor, F2FS_KEY_DESC_PREFIX,
	185	F2FS_KEY_DESC_PREFIX_SIZE);
	186	sprintf(full_key_descriptor + F2FS_KEY_DESC_PREFIX_SIZE,
	187	"%*phN", F2FS_KEY_DESCRIPTOR_SIZE,
	188	ctx.master_key_descriptor);
	189	full_key_descriptor[F2FS_KEY_DESC_PREFIX_SIZE +
	190	(2 * F2FS_KEY_DESCRIPTOR_SIZE)] = '\0';
	191	keyring_key = request_key(&key_type_logon, full_key_descriptor, NULL);
	192	if (IS_ERR(keyring_key)) {
	193	res = PTR_ERR(keyring_key);
	194	keyring_key = NULL;
	195	goto out;
	196	}
26bf3dc7	197	crypt_info->ci_keyring_key = keyring_key;
0adda907	198	BUG_ON(keyring_key->type != &key_type_logon);
146aa8b1	199	ukp = user_key_payload(keyring_key);
0adda907 JK	200	if (ukp->datalen != sizeof(struct f2fs_encryption_key)) {
	201	res = -EINVAL;
	202	goto out;
	203	}
	204	master_key = (struct f2fs_encryption_key *)ukp->data;
	205	BUILD_BUG_ON(F2FS_AES_128_ECB_KEY_SIZE !=
	206	F2FS_KEY_DERIVATION_NONCE_SIZE);
	207	BUG_ON(master_key->size != F2FS_AES_256_XTS_KEY_SIZE);
	208	res = f2fs_derive_key_aes(ctx.nonce, master_key->raw,
26bf3dc7 JK	209	raw_key);
	210	if (res)
	211	goto out;
	212
2731a944	213	ctfm = crypto_alloc_skcipher(cipher_str, 0, 0);
26bf3dc7 JK	214	if (!ctfm \|\| IS_ERR(ctfm)) {
	215	res = ctfm ? PTR_ERR(ctfm) : -ENOMEM;
	216	printk(KERN_DEBUG
	217	"%s: error %d (inode %u) allocating crypto tfm\n",
	218	__func__, res, (unsigned) inode->i_ino);
	219	goto out;
0adda907	220	}
26bf3dc7	221	crypt_info->ci_ctfm = ctfm;
2731a944 HX	222	crypto_skcipher_clear_flags(ctfm, ~0);
	223	crypto_skcipher_set_flags(ctfm, CRYPTO_TFM_REQ_WEAK_KEY);
	224	res = crypto_skcipher_setkey(ctfm, raw_key,
	225	f2fs_encryption_key_size(mode));
26bf3dc7 JK	226	if (res)
	227	goto out;
	228
	229	memzero_explicit(raw_key, sizeof(raw_key));
	230	if (cmpxchg(&fi->i_crypt_info, NULL, crypt_info) != NULL) {
	231	f2fs_free_crypt_info(crypt_info);
	232	goto retry;
	233	}
	234	return 0;
	235
	236	out:
	237	if (res == -ENOKEY && !S_ISREG(inode->i_mode))
	238	res = 0;
	239
	240	f2fs_free_crypt_info(crypt_info);
	241	memzero_explicit(raw_key, sizeof(raw_key));
0adda907 JK	242	return res;
	243	}
	244
	245	int f2fs_has_encryption_key(struct inode *inode)
	246	{
	247	struct f2fs_inode_info *fi = F2FS_I(inode);
	248
	249	return (fi->i_crypt_info != NULL);
	250	}