[linux-2.6-block.git] / fs / crypto / keysetup_v1.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Key setup for v1 encryption policies
 *
 * Copyright 2015, 2019 Google LLC
 */

/*
 * This file implements compatibility functions for the original encryption
 * policy version ("v1"), including:
 *
 * - Deriving per-file keys using the AES-128-ECB based KDF
 *   (rather than the new method of using HKDF-SHA512)
 *
 * - Retrieving fscrypt master keys from process-subscribed keyrings
 *   (rather than the new method of using a filesystem-level keyring)
 *
 * - Handling policies with the DIRECT_KEY flag set using a master key table
 *   (rather than the new method of implementing DIRECT_KEY with per-mode keys
 *    managed alongside the master keys in the filesystem-level keyring)
 */

#include <crypto/algapi.h>
#include <crypto/skcipher.h>
#include <keys/user-type.h>
#include <linux/hashtable.h>
#include <linux/scatterlist.h>

#include "fscrypt_private.h"

/* Table of keys referenced by DIRECT_KEY policies */
static DEFINE_HASHTABLE(fscrypt_direct_keys, 6); /* 6 bits = 64 buckets */
static DEFINE_SPINLOCK(fscrypt_direct_keys_lock);

/*
 * v1 key derivation function.  This generates the derived key by encrypting the
 * master key with AES-128-ECB using the nonce as the AES key.  This provides a
 * unique derived key with sufficient entropy for each inode.  However, it's
 * nonstandard, non-extensible, doesn't evenly distribute the entropy from the
 * master key, and is trivially reversible: an attacker who compromises a
 * derived key can "decrypt" it to get back to the master key, then derive any
 * other key.  For all new code, use HKDF instead.
 *
 * The master key must be at least as long as the derived key.  If the master
 * key is longer, then only the first 'derived_keysize' bytes are used.
 */
static int derive_key_aes(const u8 *master_key,
			  const u8 nonce[FS_KEY_DERIVATION_NONCE_SIZE],
			  u8 *derived_key, unsigned int derived_keysize)
{
	int res = 0;
	struct skcipher_request *req = NULL;
	DECLARE_CRYPTO_WAIT(wait);
	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_FORBID_WEAK_KEYS);
	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,
			crypto_req_done, &wait);
	res = crypto_skcipher_setkey(tfm, nonce, FS_KEY_DERIVATION_NONCE_SIZE);
	if (res < 0)
		goto out;

	sg_init_one(&src_sg, master_key, derived_keysize);
	sg_init_one(&dst_sg, derived_key, derived_keysize);
	skcipher_request_set_crypt(req, &src_sg, &dst_sg, derived_keysize,
				   NULL);
	res = crypto_wait_req(crypto_skcipher_encrypt(req), &wait);
out:
	skcipher_request_free(req);
	crypto_free_skcipher(tfm);
	return res;
}

/*
 * Search the current task's subscribed keyrings for a "logon" key with
 * description prefix:descriptor, and if found acquire a read lock on it and
 * return a pointer to its validated payload in *payload_ret.
 */
static struct key *
find_and_lock_process_key(const char *prefix,
			  const u8 descriptor[FSCRYPT_KEY_DESCRIPTOR_SIZE],
			  unsigned int min_keysize,
			  const struct fscrypt_key **payload_ret)
{
	char *description;
	struct key *key;
	const struct user_key_payload *ukp;
	const struct fscrypt_key *payload;

	description = kasprintf(GFP_NOFS, "%s%*phN", prefix,
				FSCRYPT_KEY_DESCRIPTOR_SIZE, descriptor);
	if (!description)
		return ERR_PTR(-ENOMEM);

	key = request_key(&key_type_logon, description, NULL);
	kfree(description);
	if (IS_ERR(key))
		return key;

	down_read(&key->sem);
	ukp = user_key_payload_locked(key);

	if (!ukp) /* was the key revoked before we acquired its semaphore? */
		goto invalid;

	payload = (const struct fscrypt_key *)ukp->data;

	if (ukp->datalen != sizeof(struct fscrypt_key) ||
	    payload->size < 1 || payload->size > FSCRYPT_MAX_KEY_SIZE) {
		fscrypt_warn(NULL,
			     "key with description '%s' has invalid payload",
			     key->description);
		goto invalid;
	}

	if (payload->size < min_keysize) {
		fscrypt_warn(NULL,
			     "key with description '%s' is too short (got %u bytes, need %u+ bytes)",
			     key->description, payload->size, min_keysize);
		goto invalid;
	}

	*payload_ret = payload;
	return key;

invalid:
	up_read(&key->sem);
	key_put(key);
	return ERR_PTR(-ENOKEY);
}

/* Master key referenced by DIRECT_KEY policy */
struct fscrypt_direct_key {
	struct hlist_node		dk_node;
	refcount_t			dk_refcount;
	const struct fscrypt_mode	*dk_mode;
	struct crypto_skcipher		*dk_ctfm;
	u8				dk_descriptor[FSCRYPT_KEY_DESCRIPTOR_SIZE];
	u8				dk_raw[FSCRYPT_MAX_KEY_SIZE];
};

static void free_direct_key(struct fscrypt_direct_key *dk)
{
	if (dk) {
		crypto_free_skcipher(dk->dk_ctfm);
		kzfree(dk);
	}
}

void fscrypt_put_direct_key(struct fscrypt_direct_key *dk)
{
	if (!refcount_dec_and_lock(&dk->dk_refcount, &fscrypt_direct_keys_lock))
		return;
	hash_del(&dk->dk_node);
	spin_unlock(&fscrypt_direct_keys_lock);

	free_direct_key(dk);
}

/*
 * Find/insert the given key into the fscrypt_direct_keys table.  If found, it
 * is returned with elevated refcount, and 'to_insert' is freed if non-NULL.  If
 * not found, 'to_insert' is inserted and returned if it's non-NULL; otherwise
 * NULL is returned.
 */
static struct fscrypt_direct_key *
find_or_insert_direct_key(struct fscrypt_direct_key *to_insert,
			  const u8 *raw_key, const struct fscrypt_info *ci)
{
	unsigned long hash_key;
	struct fscrypt_direct_key *dk;

	/*
	 * Careful: to avoid potentially leaking secret key bytes via timing
	 * information, we must key the hash table by descriptor rather than by
	 * raw key, and use crypto_memneq() when comparing raw keys.
	 */

	BUILD_BUG_ON(sizeof(hash_key) > FSCRYPT_KEY_DESCRIPTOR_SIZE);
	memcpy(&hash_key, ci->ci_policy.v1.master_key_descriptor,
	       sizeof(hash_key));

	spin_lock(&fscrypt_direct_keys_lock);
	hash_for_each_possible(fscrypt_direct_keys, dk, dk_node, hash_key) {
		if (memcmp(ci->ci_policy.v1.master_key_descriptor,
			   dk->dk_descriptor, FSCRYPT_KEY_DESCRIPTOR_SIZE) != 0)
			continue;
		if (ci->ci_mode != dk->dk_mode)
			continue;
		if (crypto_memneq(raw_key, dk->dk_raw, ci->ci_mode->keysize))
			continue;
		/* using existing tfm with same (descriptor, mode, raw_key) */
		refcount_inc(&dk->dk_refcount);
		spin_unlock(&fscrypt_direct_keys_lock);
		free_direct_key(to_insert);
		return dk;
	}
	if (to_insert)
		hash_add(fscrypt_direct_keys, &to_insert->dk_node, hash_key);
	spin_unlock(&fscrypt_direct_keys_lock);
	return to_insert;
}

/* Prepare to encrypt directly using the master key in the given mode */
static struct fscrypt_direct_key *
fscrypt_get_direct_key(const struct fscrypt_info *ci, const u8 *raw_key)
{
	struct fscrypt_direct_key *dk;
	int err;

	/* Is there already a tfm for this key? */
	dk = find_or_insert_direct_key(NULL, raw_key, ci);
	if (dk)
		return dk;

	/* Nope, allocate one. */
	dk = kzalloc(sizeof(*dk), GFP_NOFS);
	if (!dk)
		return ERR_PTR(-ENOMEM);
	refcount_set(&dk->dk_refcount, 1);
	dk->dk_mode = ci->ci_mode;
	dk->dk_ctfm = fscrypt_allocate_skcipher(ci->ci_mode, raw_key,
						ci->ci_inode);
	if (IS_ERR(dk->dk_ctfm)) {
		err = PTR_ERR(dk->dk_ctfm);
		dk->dk_ctfm = NULL;
		goto err_free_dk;
	}
	memcpy(dk->dk_descriptor, ci->ci_policy.v1.master_key_descriptor,
	       FSCRYPT_KEY_DESCRIPTOR_SIZE);
	memcpy(dk->dk_raw, raw_key, ci->ci_mode->keysize);

	return find_or_insert_direct_key(dk, raw_key, ci);

err_free_dk:
	free_direct_key(dk);
	return ERR_PTR(err);
}

/* v1 policy, DIRECT_KEY: use the master key directly */
static int setup_v1_file_key_direct(struct fscrypt_info *ci,
				    const u8 *raw_master_key)
{
	const struct fscrypt_mode *mode = ci->ci_mode;
	struct fscrypt_direct_key *dk;

	if (!fscrypt_mode_supports_direct_key(mode)) {
		fscrypt_warn(ci->ci_inode,
			     "Direct key mode not allowed with %s",
			     mode->friendly_name);
		return -EINVAL;
	}

	if (ci->ci_policy.v1.contents_encryption_mode !=
	    ci->ci_policy.v1.filenames_encryption_mode) {
		fscrypt_warn(ci->ci_inode,
			     "Direct key mode not allowed with different contents and filenames modes");
		return -EINVAL;
	}

	/* ESSIV implies 16-byte IVs which implies !DIRECT_KEY */
	if (WARN_ON(mode->needs_essiv))
		return -EINVAL;

	dk = fscrypt_get_direct_key(ci, raw_master_key);
	if (IS_ERR(dk))
		return PTR_ERR(dk);
	ci->ci_direct_key = dk;
	ci->ci_ctfm = dk->dk_ctfm;
	return 0;
}

/* v1 policy, !DIRECT_KEY: derive the file's encryption key */
static int setup_v1_file_key_derived(struct fscrypt_info *ci,
				     const u8 *raw_master_key)
{
	u8 *derived_key;
	int err;

	/*
	 * This cannot be a stack buffer because it will be passed to the
	 * scatterlist crypto API during derive_key_aes().
	 */
	derived_key = kmalloc(ci->ci_mode->keysize, GFP_NOFS);
	if (!derived_key)
		return -ENOMEM;

	err = derive_key_aes(raw_master_key, ci->ci_nonce,
			     derived_key, ci->ci_mode->keysize);
	if (err)
		goto out;

	err = fscrypt_set_derived_key(ci, derived_key);
out:
	kzfree(derived_key);
	return err;
}

int fscrypt_setup_v1_file_key(struct fscrypt_info *ci, const u8 *raw_master_key)
{
	if (ci->ci_policy.v1.flags & FSCRYPT_POLICY_FLAG_DIRECT_KEY)
		return setup_v1_file_key_direct(ci, raw_master_key);
	else
		return setup_v1_file_key_derived(ci, raw_master_key);
}

int fscrypt_setup_v1_file_key_via_subscribed_keyrings(struct fscrypt_info *ci)
{
	struct key *key;
	const struct fscrypt_key *payload;
	int err;

	key = find_and_lock_process_key(FSCRYPT_KEY_DESC_PREFIX,
					ci->ci_policy.v1.master_key_descriptor,
					ci->ci_mode->keysize, &payload);
	if (key == ERR_PTR(-ENOKEY) && ci->ci_inode->i_sb->s_cop->key_prefix) {
		key = find_and_lock_process_key(ci->ci_inode->i_sb->s_cop->key_prefix,
						ci->ci_policy.v1.master_key_descriptor,
						ci->ci_mode->keysize, &payload);
	}
	if (IS_ERR(key))
		return PTR_ERR(key);

	err = fscrypt_setup_v1_file_key(ci, payload->raw);
	up_read(&key->sem);
	key_put(key);
	return err;
}
Commit	Line	Data
0109ce76 EB	1	// SPDX-License-Identifier: GPL-2.0
	2	/*
	3	* Key setup for v1 encryption policies
	4	*
	5	* Copyright 2015, 2019 Google LLC
	6	*/
	7
	8	/*
	9	* This file implements compatibility functions for the original encryption
	10	* policy version ("v1"), including:
	11	*
	12	* - Deriving per-file keys using the AES-128-ECB based KDF
	13	* (rather than the new method of using HKDF-SHA512)
	14	*
	15	* - Retrieving fscrypt master keys from process-subscribed keyrings
	16	* (rather than the new method of using a filesystem-level keyring)
	17	*
	18	* - Handling policies with the DIRECT_KEY flag set using a master key table
	19	* (rather than the new method of implementing DIRECT_KEY with per-mode keys
	20	* managed alongside the master keys in the filesystem-level keyring)
	21	*/
	22
	23	#include <crypto/algapi.h>
	24	#include <crypto/skcipher.h>
	25	#include <keys/user-type.h>
	26	#include <linux/hashtable.h>
	27	#include <linux/scatterlist.h>
	28
	29	#include "fscrypt_private.h"
	30
	31	/* Table of keys referenced by DIRECT_KEY policies */
	32	static DEFINE_HASHTABLE(fscrypt_direct_keys, 6); /* 6 bits = 64 buckets */
	33	static DEFINE_SPINLOCK(fscrypt_direct_keys_lock);
	34
	35	/*
	36	* v1 key derivation function. This generates the derived key by encrypting the
	37	* master key with AES-128-ECB using the nonce as the AES key. This provides a
	38	* unique derived key with sufficient entropy for each inode. However, it's
	39	* nonstandard, non-extensible, doesn't evenly distribute the entropy from the
	40	* master key, and is trivially reversible: an attacker who compromises a
	41	* derived key can "decrypt" it to get back to the master key, then derive any
	42	* other key. For all new code, use HKDF instead.
	43	*
	44	* The master key must be at least as long as the derived key. If the master
	45	* key is longer, then only the first 'derived_keysize' bytes are used.
	46	*/
	47	static int derive_key_aes(const u8 *master_key,
	48	const u8 nonce[FS_KEY_DERIVATION_NONCE_SIZE],
	49	u8 *derived_key, unsigned int derived_keysize)
	50	{
	51	int res = 0;
	52	struct skcipher_request *req = NULL;
	53	DECLARE_CRYPTO_WAIT(wait);
	54	struct scatterlist src_sg, dst_sg;
	55	struct crypto_skcipher *tfm = crypto_alloc_skcipher("ecb(aes)", 0, 0);
	56
	57	if (IS_ERR(tfm)) {
	58	res = PTR_ERR(tfm);
	59	tfm = NULL;
	60	goto out;
	61	}
	62	crypto_skcipher_set_flags(tfm, CRYPTO_TFM_REQ_FORBID_WEAK_KEYS);
	63	req = skcipher_request_alloc(tfm, GFP_NOFS);
	64	if (!req) {
65	res = -ENOMEM;
66	goto out;
67	}
68	skcipher_request_set_callback(req,
69	CRYPTO_TFM_REQ_MAY_BACKLOG \| CRYPTO_TFM_REQ_MAY_SLEEP,
70	crypto_req_done, &wait);
71	res = crypto_skcipher_setkey(tfm, nonce, FS_KEY_DERIVATION_NONCE_SIZE);
72	if (res < 0)
73	goto out;
74
75	sg_init_one(&src_sg, master_key, derived_keysize);
76	sg_init_one(&dst_sg, derived_key, derived_keysize);
77	skcipher_request_set_crypt(req, &src_sg, &dst_sg, derived_keysize,
78	NULL);
79	res = crypto_wait_req(crypto_skcipher_encrypt(req), &wait);
80	out:
81	skcipher_request_free(req);
82	crypto_free_skcipher(tfm);
83	return res;
84	}
85
86	/*
87	* Search the current task's subscribed keyrings for a "logon" key with
88	* description prefix:descriptor, and if found acquire a read lock on it and
89	* return a pointer to its validated payload in *payload_ret.
90	*/
91	static struct key *
92	find_and_lock_process_key(const char *prefix,
93	const u8 descriptor[FSCRYPT_KEY_DESCRIPTOR_SIZE],
94	unsigned int min_keysize,
95	const struct fscrypt_key **payload_ret)
96	{
97	char *description;
98	struct key *key;
99	const struct user_key_payload *ukp;
100	const struct fscrypt_key *payload;
101
102	description = kasprintf(GFP_NOFS, "%s%*phN", prefix,
103	FSCRYPT_KEY_DESCRIPTOR_SIZE, descriptor);
104	if (!description)
105	return ERR_PTR(-ENOMEM);
106
107	key = request_key(&key_type_logon, description, NULL);
108	kfree(description);
109	if (IS_ERR(key))
110	return key;
111
112	down_read(&key->sem);
113	ukp = user_key_payload_locked(key);
114
115	if (!ukp) /* was the key revoked before we acquired its semaphore? */
116	goto invalid;
117
118	payload = (const struct fscrypt_key *)ukp->data;
119
120	if (ukp->datalen != sizeof(struct fscrypt_key) \|\|
121	payload->size < 1 \|\| payload->size > FSCRYPT_MAX_KEY_SIZE) {
122	fscrypt_warn(NULL,
123	"key with description '%s' has invalid payload",
124	key->description);
125	goto invalid;
126	}
127
128	if (payload->size < min_keysize) {
129	fscrypt_warn(NULL,
130	"key with description '%s' is too short (got %u bytes, need %u+ bytes)",
131	key->description, payload->size, min_keysize);
132	goto invalid;
133	}
134
135	*payload_ret = payload;
136	return key;
137
138	invalid:
139	up_read(&key->sem);
140	key_put(key);
141	return ERR_PTR(-ENOKEY);
142	}
143
144	/* Master key referenced by DIRECT_KEY policy */
145	struct fscrypt_direct_key {
146	struct hlist_node dk_node;
147	refcount_t dk_refcount;
148	const struct fscrypt_mode *dk_mode;
149	struct crypto_skcipher *dk_ctfm;
150	u8 dk_descriptor[FSCRYPT_KEY_DESCRIPTOR_SIZE];
151	u8 dk_raw[FSCRYPT_MAX_KEY_SIZE];
152	};
153
154	static void free_direct_key(struct fscrypt_direct_key *dk)
155	{
156	if (dk) {
157	crypto_free_skcipher(dk->dk_ctfm);
158	kzfree(dk);
159	}
160	}
161
162	void fscrypt_put_direct_key(struct fscrypt_direct_key *dk)
163	{
164	if (!refcount_dec_and_lock(&dk->dk_refcount, &fscrypt_direct_keys_lock))
165	return;
166	hash_del(&dk->dk_node);
167	spin_unlock(&fscrypt_direct_keys_lock);
168
169	free_direct_key(dk);
170	}
171
172	/*
173	* Find/insert the given key into the fscrypt_direct_keys table. If found, it
174	* is returned with elevated refcount, and 'to_insert' is freed if non-NULL. If
175	* not found, 'to_insert' is inserted and returned if it's non-NULL; otherwise
176	* NULL is returned.
177	*/
178	static struct fscrypt_direct_key *
179	find_or_insert_direct_key(struct fscrypt_direct_key *to_insert,
180	const u8 raw_key, const struct fscrypt_info ci)
181	{
182	unsigned long hash_key;
183	struct fscrypt_direct_key *dk;
184
185	/*
186	* Careful: to avoid potentially leaking secret key bytes via timing
187	* information, we must key the hash table by descriptor rather than by
188	* raw key, and use crypto_memneq() when comparing raw keys.
189	*/
190
191	BUILD_BUG_ON(sizeof(hash_key) > FSCRYPT_KEY_DESCRIPTOR_SIZE);
5dae460c EB	192	memcpy(&hash_key, ci->ci_policy.v1.master_key_descriptor,
5dae460c EB	193	sizeof(hash_key));
0109ce76 EB	194
	195	spin_lock(&fscrypt_direct_keys_lock);
	196	hash_for_each_possible(fscrypt_direct_keys, dk, dk_node, hash_key) {
5dae460c EB	197	if (memcmp(ci->ci_policy.v1.master_key_descriptor,
5dae460c EB	198	dk->dk_descriptor, FSCRYPT_KEY_DESCRIPTOR_SIZE) != 0)
0109ce76 EB	199	continue;
	200	if (ci->ci_mode != dk->dk_mode)
	201	continue;
	202	if (crypto_memneq(raw_key, dk->dk_raw, ci->ci_mode->keysize))
	203	continue;
	204	/* using existing tfm with same (descriptor, mode, raw_key) */
	205	refcount_inc(&dk->dk_refcount);
	206	spin_unlock(&fscrypt_direct_keys_lock);
	207	free_direct_key(to_insert);
	208	return dk;
	209	}
	210	if (to_insert)
	211	hash_add(fscrypt_direct_keys, &to_insert->dk_node, hash_key);
	212	spin_unlock(&fscrypt_direct_keys_lock);
	213	return to_insert;
	214	}
	215
	216	/* Prepare to encrypt directly using the master key in the given mode */
	217	static struct fscrypt_direct_key *
	218	fscrypt_get_direct_key(const struct fscrypt_info ci, const u8 raw_key)
	219	{
	220	struct fscrypt_direct_key *dk;
	221	int err;
	222
	223	/* Is there already a tfm for this key? */
	224	dk = find_or_insert_direct_key(NULL, raw_key, ci);
	225	if (dk)
	226	return dk;
	227
	228	/* Nope, allocate one. */
	229	dk = kzalloc(sizeof(*dk), GFP_NOFS);
	230	if (!dk)
	231	return ERR_PTR(-ENOMEM);
	232	refcount_set(&dk->dk_refcount, 1);
	233	dk->dk_mode = ci->ci_mode;
	234	dk->dk_ctfm = fscrypt_allocate_skcipher(ci->ci_mode, raw_key,
	235	ci->ci_inode);
	236	if (IS_ERR(dk->dk_ctfm)) {
	237	err = PTR_ERR(dk->dk_ctfm);
	238	dk->dk_ctfm = NULL;
	239	goto err_free_dk;
	240	}
5dae460c	241	memcpy(dk->dk_descriptor, ci->ci_policy.v1.master_key_descriptor,
0109ce76 EB	242	FSCRYPT_KEY_DESCRIPTOR_SIZE);
	243	memcpy(dk->dk_raw, raw_key, ci->ci_mode->keysize);
	244
	245	return find_or_insert_direct_key(dk, raw_key, ci);
	246
	247	err_free_dk:
	248	free_direct_key(dk);
	249	return ERR_PTR(err);
	250	}
	251
	252	/* v1 policy, DIRECT_KEY: use the master key directly */
	253	static int setup_v1_file_key_direct(struct fscrypt_info *ci,
	254	const u8 *raw_master_key)
	255	{
	256	const struct fscrypt_mode *mode = ci->ci_mode;
	257	struct fscrypt_direct_key *dk;
	258
	259	if (!fscrypt_mode_supports_direct_key(mode)) {
	260	fscrypt_warn(ci->ci_inode,
	261	"Direct key mode not allowed with %s",
	262	mode->friendly_name);
	263	return -EINVAL;
	264	}
	265
5dae460c EB	266	if (ci->ci_policy.v1.contents_encryption_mode !=
5dae460c EB	267	ci->ci_policy.v1.filenames_encryption_mode) {
0109ce76 EB	268	fscrypt_warn(ci->ci_inode,
	269	"Direct key mode not allowed with different contents and filenames modes");
	270	return -EINVAL;
	271	}
	272
	273	/* ESSIV implies 16-byte IVs which implies !DIRECT_KEY */
	274	if (WARN_ON(mode->needs_essiv))
	275	return -EINVAL;
	276
	277	dk = fscrypt_get_direct_key(ci, raw_master_key);
	278	if (IS_ERR(dk))
	279	return PTR_ERR(dk);
	280	ci->ci_direct_key = dk;
	281	ci->ci_ctfm = dk->dk_ctfm;
	282	return 0;
	283	}
	284
	285	/* v1 policy, !DIRECT_KEY: derive the file's encryption key */
	286	static int setup_v1_file_key_derived(struct fscrypt_info *ci,
	287	const u8 *raw_master_key)
	288	{
	289	u8 *derived_key;
	290	int err;
	291
	292	/*
	293	* This cannot be a stack buffer because it will be passed to the
	294	* scatterlist crypto API during derive_key_aes().
	295	*/
	296	derived_key = kmalloc(ci->ci_mode->keysize, GFP_NOFS);
	297	if (!derived_key)
	298	return -ENOMEM;
	299
	300	err = derive_key_aes(raw_master_key, ci->ci_nonce,
	301	derived_key, ci->ci_mode->keysize);
	302	if (err)
	303	goto out;
	304
	305	err = fscrypt_set_derived_key(ci, derived_key);
	306	out:
	307	kzfree(derived_key);
	308	return err;
	309	}
	310
	311	int fscrypt_setup_v1_file_key(struct fscrypt_info ci, const u8 raw_master_key)
	312	{
5dae460c	313	if (ci->ci_policy.v1.flags & FSCRYPT_POLICY_FLAG_DIRECT_KEY)
0109ce76 EB	314	return setup_v1_file_key_direct(ci, raw_master_key);
	315	else
	316	return setup_v1_file_key_derived(ci, raw_master_key);
	317	}
	318
	319	int fscrypt_setup_v1_file_key_via_subscribed_keyrings(struct fscrypt_info *ci)
	320	{
	321	struct key *key;
	322	const struct fscrypt_key *payload;
	323	int err;
	324
	325	key = find_and_lock_process_key(FSCRYPT_KEY_DESC_PREFIX,
5dae460c	326	ci->ci_policy.v1.master_key_descriptor,
0109ce76 EB	327	ci->ci_mode->keysize, &payload);
	328	if (key == ERR_PTR(-ENOKEY) && ci->ci_inode->i_sb->s_cop->key_prefix) {
	329	key = find_and_lock_process_key(ci->ci_inode->i_sb->s_cop->key_prefix,
5dae460c	330	ci->ci_policy.v1.master_key_descriptor,
0109ce76 EB	331	ci->ci_mode->keysize, &payload);
	332	}
	333	if (IS_ERR(key))
	334	return PTR_ERR(key);
	335
	336	err = fscrypt_setup_v1_file_key(ci, payload->raw);
	337	up_read(&key->sem);
	338	key_put(key);
	339	return err;
	340	}