[linux-2.6-block.git] / security / keys / big_key.c

/* Large capacity key type
 *
 * Copyright (C) 2017 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
 * Copyright (C) 2013 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public Licence
 * as published by the Free Software Foundation; either version
 * 2 of the Licence, or (at your option) any later version.
 */

#define pr_fmt(fmt) "big_key: "fmt
#include <linux/init.h>
#include <linux/seq_file.h>
#include <linux/file.h>
#include <linux/shmem_fs.h>
#include <linux/err.h>
#include <linux/scatterlist.h>
#include <linux/random.h>
#include <linux/vmalloc.h>
#include <keys/user-type.h>
#include <keys/big_key-type.h>
#include <crypto/aead.h>
#include <crypto/gcm.h>

struct big_key_buf {
	unsigned int		nr_pages;
	void			*virt;
	struct scatterlist	*sg;
	struct page		*pages[];
};

/*
 * Layout of key payload words.
 */
enum {
	big_key_data,
	big_key_path,
	big_key_path_2nd_part,
	big_key_len,
};

/*
 * Crypto operation with big_key data
 */
enum big_key_op {
	BIG_KEY_ENC,
	BIG_KEY_DEC,
};

/*
 * If the data is under this limit, there's no point creating a shm file to
 * hold it as the permanently resident metadata for the shmem fs will be at
 * least as large as the data.
 */
#define BIG_KEY_FILE_THRESHOLD (sizeof(struct inode) + sizeof(struct dentry))

/*
 * Key size for big_key data encryption
 */
#define ENC_KEY_SIZE 32

/*
 * Authentication tag length
 */
#define ENC_AUTHTAG_SIZE 16

/*
 * big_key defined keys take an arbitrary string as the description and an
 * arbitrary blob of data as the payload
 */
struct key_type key_type_big_key = {
	.name			= "big_key",
	.preparse		= big_key_preparse,
	.free_preparse		= big_key_free_preparse,
	.instantiate		= generic_key_instantiate,
	.revoke			= big_key_revoke,
	.destroy		= big_key_destroy,
	.describe		= big_key_describe,
	.read			= big_key_read,
	/* no ->update(); don't add it without changing big_key_crypt() nonce */
};

/*
 * Crypto names for big_key data authenticated encryption
 */
static const char big_key_alg_name[] = "gcm(aes)";
#define BIG_KEY_IV_SIZE		GCM_AES_IV_SIZE

/*
 * Crypto algorithms for big_key data authenticated encryption
 */
static struct crypto_aead *big_key_aead;

/*
 * Since changing the key affects the entire object, we need a mutex.
 */
static DEFINE_MUTEX(big_key_aead_lock);

/*
 * Encrypt/decrypt big_key data
 */
static int big_key_crypt(enum big_key_op op, struct big_key_buf *buf, size_t datalen, u8 *key)
{
	int ret;
	struct aead_request *aead_req;
	/* We always use a zero nonce. The reason we can get away with this is
	 * because we're using a different randomly generated key for every
	 * different encryption. Notably, too, key_type_big_key doesn't define
	 * an .update function, so there's no chance we'll wind up reusing the
	 * key to encrypt updated data. Simply put: one key, one encryption.
	 */
	u8 zero_nonce[BIG_KEY_IV_SIZE];

	aead_req = aead_request_alloc(big_key_aead, GFP_KERNEL);
	if (!aead_req)
		return -ENOMEM;

	memset(zero_nonce, 0, sizeof(zero_nonce));
	aead_request_set_crypt(aead_req, buf->sg, buf->sg, datalen, zero_nonce);
	aead_request_set_callback(aead_req, CRYPTO_TFM_REQ_MAY_SLEEP, NULL, NULL);
	aead_request_set_ad(aead_req, 0);

	mutex_lock(&big_key_aead_lock);
	if (crypto_aead_setkey(big_key_aead, key, ENC_KEY_SIZE)) {
		ret = -EAGAIN;
		goto error;
	}
	if (op == BIG_KEY_ENC)
		ret = crypto_aead_encrypt(aead_req);
	else
		ret = crypto_aead_decrypt(aead_req);
error:
	mutex_unlock(&big_key_aead_lock);
	aead_request_free(aead_req);
	return ret;
}

/*
 * Free up the buffer.
 */
static void big_key_free_buffer(struct big_key_buf *buf)
{
	unsigned int i;

	if (buf->virt) {
		memset(buf->virt, 0, buf->nr_pages * PAGE_SIZE);
		vunmap(buf->virt);
	}

	for (i = 0; i < buf->nr_pages; i++)
		if (buf->pages[i])
			__free_page(buf->pages[i]);

	kfree(buf);
}

/*
 * Allocate a buffer consisting of a set of pages with a virtual mapping
 * applied over them.
 */
static void *big_key_alloc_buffer(size_t len)
{
	struct big_key_buf *buf;
	unsigned int npg = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
	unsigned int i, l;

	buf = kzalloc(sizeof(struct big_key_buf) +
		      sizeof(struct page) * npg +
		      sizeof(struct scatterlist) * npg,
		      GFP_KERNEL);
	if (!buf)
		return NULL;

	buf->nr_pages = npg;
	buf->sg = (void *)(buf->pages + npg);
	sg_init_table(buf->sg, npg);

	for (i = 0; i < buf->nr_pages; i++) {
		buf->pages[i] = alloc_page(GFP_KERNEL);
		if (!buf->pages[i])
			goto nomem;

		l = min_t(size_t, len, PAGE_SIZE);
		sg_set_page(&buf->sg[i], buf->pages[i], l, 0);
		len -= l;
	}

	buf->virt = vmap(buf->pages, buf->nr_pages, VM_MAP, PAGE_KERNEL);
	if (!buf->virt)
		goto nomem;

	return buf;

nomem:
	big_key_free_buffer(buf);
	return NULL;
}

/*
 * Preparse a big key
 */
int big_key_preparse(struct key_preparsed_payload *prep)
{
	struct big_key_buf *buf;
	struct path *path = (struct path *)&prep->payload.data[big_key_path];
	struct file *file;
	u8 *enckey;
	ssize_t written;
	size_t datalen = prep->datalen, enclen = datalen + ENC_AUTHTAG_SIZE;
	int ret;

	if (datalen <= 0 || datalen > 1024 * 1024 || !prep->data)
		return -EINVAL;

	/* Set an arbitrary quota */
	prep->quotalen = 16;

	prep->payload.data[big_key_len] = (void *)(unsigned long)datalen;

	if (datalen > BIG_KEY_FILE_THRESHOLD) {
		/* Create a shmem file to store the data in.  This will permit the data
		 * to be swapped out if needed.
		 *
		 * File content is stored encrypted with randomly generated key.
		 */
		loff_t pos = 0;

		buf = big_key_alloc_buffer(enclen);
		if (!buf)
			return -ENOMEM;
		memcpy(buf->virt, prep->data, datalen);

		/* generate random key */
		enckey = kmalloc(ENC_KEY_SIZE, GFP_KERNEL);
		if (!enckey) {
			ret = -ENOMEM;
			goto error;
		}
		ret = get_random_bytes_wait(enckey, ENC_KEY_SIZE);
		if (unlikely(ret))
			goto err_enckey;

		/* encrypt aligned data */
		ret = big_key_crypt(BIG_KEY_ENC, buf, datalen, enckey);
		if (ret)
			goto err_enckey;

		/* save aligned data to file */
		file = shmem_kernel_file_setup("", enclen, 0);
		if (IS_ERR(file)) {
			ret = PTR_ERR(file);
			goto err_enckey;
		}

		written = kernel_write(file, buf->virt, enclen, &pos);
		if (written != enclen) {
			ret = written;
			if (written >= 0)
				ret = -ENOMEM;
			goto err_fput;
		}

		/* Pin the mount and dentry to the key so that we can open it again
		 * later
		 */
		prep->payload.data[big_key_data] = enckey;
		*path = file->f_path;
		path_get(path);
		fput(file);
		big_key_free_buffer(buf);
	} else {
		/* Just store the data in a buffer */
		void *data = kmalloc(datalen, GFP_KERNEL);

		if (!data)
			return -ENOMEM;

		prep->payload.data[big_key_data] = data;
		memcpy(data, prep->data, prep->datalen);
	}
	return 0;

err_fput:
	fput(file);
err_enckey:
	kzfree(enckey);
error:
	big_key_free_buffer(buf);
	return ret;
}

/*
 * Clear preparsement.
 */
void big_key_free_preparse(struct key_preparsed_payload *prep)
{
	if (prep->datalen > BIG_KEY_FILE_THRESHOLD) {
		struct path *path = (struct path *)&prep->payload.data[big_key_path];

		path_put(path);
	}
	kzfree(prep->payload.data[big_key_data]);
}

/*
 * dispose of the links from a revoked keyring
 * - called with the key sem write-locked
 */
void big_key_revoke(struct key *key)
{
	struct path *path = (struct path *)&key->payload.data[big_key_path];

	/* clear the quota */
	key_payload_reserve(key, 0);
	if (key_is_positive(key) &&
	    (size_t)key->payload.data[big_key_len] > BIG_KEY_FILE_THRESHOLD)
		vfs_truncate(path, 0);
}

/*
 * dispose of the data dangling from the corpse of a big_key key
 */
void big_key_destroy(struct key *key)
{
	size_t datalen = (size_t)key->payload.data[big_key_len];

	if (datalen > BIG_KEY_FILE_THRESHOLD) {
		struct path *path = (struct path *)&key->payload.data[big_key_path];

		path_put(path);
		path->mnt = NULL;
		path->dentry = NULL;
	}
	kzfree(key->payload.data[big_key_data]);
	key->payload.data[big_key_data] = NULL;
}

/*
 * describe the big_key key
 */
void big_key_describe(const struct key *key, struct seq_file *m)
{
	size_t datalen = (size_t)key->payload.data[big_key_len];

	seq_puts(m, key->description);

	if (key_is_positive(key))
		seq_printf(m, ": %zu [%s]",
			   datalen,
			   datalen > BIG_KEY_FILE_THRESHOLD ? "file" : "buff");
}

/*
 * read the key data
 * - the key's semaphore is read-locked
 */
long big_key_read(const struct key *key, char __user *buffer, size_t buflen)
{
	size_t datalen = (size_t)key->payload.data[big_key_len];
	long ret;

	if (!buffer || buflen < datalen)
		return datalen;

	if (datalen > BIG_KEY_FILE_THRESHOLD) {
		struct big_key_buf *buf;
		struct path *path = (struct path *)&key->payload.data[big_key_path];
		struct file *file;
		u8 *enckey = (u8 *)key->payload.data[big_key_data];
		size_t enclen = datalen + ENC_AUTHTAG_SIZE;
		loff_t pos = 0;

		buf = big_key_alloc_buffer(enclen);
		if (!buf)
			return -ENOMEM;

		file = dentry_open(path, O_RDONLY, current_cred());
		if (IS_ERR(file)) {
			ret = PTR_ERR(file);
			goto error;
		}

		/* read file to kernel and decrypt */
		ret = kernel_read(file, buf->virt, enclen, &pos);
		if (ret >= 0 && ret != enclen) {
			ret = -EIO;
			goto err_fput;
		}

		ret = big_key_crypt(BIG_KEY_DEC, buf, enclen, enckey);
		if (ret)
			goto err_fput;

		ret = datalen;

		/* copy decrypted data to user */
		if (copy_to_user(buffer, buf->virt, datalen) != 0)
			ret = -EFAULT;

err_fput:
		fput(file);
error:
		big_key_free_buffer(buf);
	} else {
		ret = datalen;
		if (copy_to_user(buffer, key->payload.data[big_key_data],
				 datalen) != 0)
			ret = -EFAULT;
	}

	return ret;
}

/*
 * Register key type
 */
static int __init big_key_init(void)
{
	int ret;

	/* init block cipher */
	big_key_aead = crypto_alloc_aead(big_key_alg_name, 0, CRYPTO_ALG_ASYNC);
	if (IS_ERR(big_key_aead)) {
		ret = PTR_ERR(big_key_aead);
		pr_err("Can't alloc crypto: %d\n", ret);
		return ret;
	}

	if (unlikely(crypto_aead_ivsize(big_key_aead) != BIG_KEY_IV_SIZE)) {
		WARN(1, "big key algorithm changed?");
		ret = -EINVAL;
		goto free_aead;
	}

	ret = crypto_aead_setauthsize(big_key_aead, ENC_AUTHTAG_SIZE);
	if (ret < 0) {
		pr_err("Can't set crypto auth tag len: %d\n", ret);
		goto free_aead;
	}

	ret = register_key_type(&key_type_big_key);
	if (ret < 0) {
		pr_err("Can't register type: %d\n", ret);
		goto free_aead;
	}

	return 0;

free_aead:
	crypto_free_aead(big_key_aead);
	return ret;
}

late_initcall(big_key_init);
Commit	Line	Data
ab3c3587 DH	1	/* Large capacity key type
ab3c3587 DH	2	*
428490e3	3	* Copyright (C) 2017 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
ab3c3587 DH	4	* Copyright (C) 2013 Red Hat, Inc. All Rights Reserved.
	5	* Written by David Howells (dhowells@redhat.com)
	6	*
	7	* This program is free software; you can redistribute it and/or
	8	* modify it under the terms of the GNU General Public Licence
	9	* as published by the Free Software Foundation; either version
	10	* 2 of the Licence, or (at your option) any later version.
	11	*/
	12
7df3e59c	13	#define pr_fmt(fmt) "big_key: "fmt
ab3c3587 DH	14	#include <linux/init.h>
	15	#include <linux/seq_file.h>
	16	#include <linux/file.h>
	17	#include <linux/shmem_fs.h>
	18	#include <linux/err.h>
13100a72	19	#include <linux/scatterlist.h>
428490e3	20	#include <linux/random.h>
514c6032	21	#include <linux/vmalloc.h>
ab3c3587 DH	22	#include <keys/user-type.h>
ab3c3587 DH	23	#include <keys/big_key-type.h>
428490e3	24	#include <crypto/aead.h>
a964f395	25	#include <crypto/gcm.h>
ab3c3587	26
d9f4bb1a DH	27	struct big_key_buf {
	28	unsigned int nr_pages;
	29	void *virt;
	30	struct scatterlist *sg;
	31	struct page *pages[];
	32	};
	33
146aa8b1 DH	34	/*
	35	* Layout of key payload words.
	36	*/
	37	enum {
	38	big_key_data,
	39	big_key_path,
	40	big_key_path_2nd_part,
	41	big_key_len,
	42	};
	43
13100a72 KM	44	/*
	45	* Crypto operation with big_key data
	46	*/
	47	enum big_key_op {
	48	BIG_KEY_ENC,
	49	BIG_KEY_DEC,
	50	};
	51
ab3c3587 DH	52	/*
	53	* If the data is under this limit, there's no point creating a shm file to
	54	* hold it as the permanently resident metadata for the shmem fs will be at
	55	* least as large as the data.
	56	*/
	57	#define BIG_KEY_FILE_THRESHOLD (sizeof(struct inode) + sizeof(struct dentry))
	58
13100a72 KM	59	/*
	60	* Key size for big_key data encryption
	61	*/
428490e3 JD	62	#define ENC_KEY_SIZE 32
	63
	64	/*
	65	* Authentication tag length
	66	*/
	67	#define ENC_AUTHTAG_SIZE 16
13100a72	68
ab3c3587 DH	69	/*
	70	* big_key defined keys take an arbitrary string as the description and an
	71	* arbitrary blob of data as the payload
	72	*/
	73	struct key_type key_type_big_key = {
	74	.name = "big_key",
002edaf7 DH	75	.preparse = big_key_preparse,
	76	.free_preparse = big_key_free_preparse,
	77	.instantiate = generic_key_instantiate,
ab3c3587 DH	78	.revoke = big_key_revoke,
	79	.destroy = big_key_destroy,
	80	.describe = big_key_describe,
	81	.read = big_key_read,
428490e3	82	/* no ->update(); don't add it without changing big_key_crypt() nonce */
ab3c3587 DH	83	};
ab3c3587 DH	84
13100a72	85	/*
428490e3	86	* Crypto names for big_key data authenticated encryption
13100a72	87	*/
428490e3	88	static const char big_key_alg_name[] = "gcm(aes)";
a964f395	89	#define BIG_KEY_IV_SIZE GCM_AES_IV_SIZE
13100a72 KM	90
13100a72 KM	91	/*
428490e3	92	* Crypto algorithms for big_key data authenticated encryption
13100a72	93	*/
428490e3	94	static struct crypto_aead *big_key_aead;
13100a72 KM	95
13100a72 KM	96	/*
428490e3	97	* Since changing the key affects the entire object, we need a mutex.
13100a72	98	*/
428490e3	99	static DEFINE_MUTEX(big_key_aead_lock);
13100a72 KM	100
	101	/*
	102	* Encrypt/decrypt big_key data
	103	*/
d9f4bb1a	104	static int big_key_crypt(enum big_key_op op, struct big_key_buf buf, size_t datalen, u8 key)
13100a72	105	{
428490e3	106	int ret;
428490e3 JD	107	struct aead_request *aead_req;
	108	/* We always use a zero nonce. The reason we can get away with this is
	109	* because we're using a different randomly generated key for every
	110	* different encryption. Notably, too, key_type_big_key doesn't define
	111	* an .update function, so there's no chance we'll wind up reusing the
	112	* key to encrypt updated data. Simply put: one key, one encryption.
	113	*/
a964f395	114	u8 zero_nonce[BIG_KEY_IV_SIZE];
428490e3 JD	115
	116	aead_req = aead_request_alloc(big_key_aead, GFP_KERNEL);
	117	if (!aead_req)
	118	return -ENOMEM;
	119
	120	memset(zero_nonce, 0, sizeof(zero_nonce));
d9f4bb1a	121	aead_request_set_crypt(aead_req, buf->sg, buf->sg, datalen, zero_nonce);
428490e3 JD	122	aead_request_set_callback(aead_req, CRYPTO_TFM_REQ_MAY_SLEEP, NULL, NULL);
	123	aead_request_set_ad(aead_req, 0);
	124
	125	mutex_lock(&big_key_aead_lock);
	126	if (crypto_aead_setkey(big_key_aead, key, ENC_KEY_SIZE)) {
13100a72 KM	127	ret = -EAGAIN;
	128	goto error;
	129	}
13100a72	130	if (op == BIG_KEY_ENC)
428490e3	131	ret = crypto_aead_encrypt(aead_req);
13100a72	132	else
428490e3	133	ret = crypto_aead_decrypt(aead_req);
13100a72	134	error:
428490e3 JD	135	mutex_unlock(&big_key_aead_lock);
428490e3 JD	136	aead_request_free(aead_req);
13100a72 KM	137	return ret;
	138	}
	139
d9f4bb1a DH	140	/*
	141	* Free up the buffer.
	142	*/
	143	static void big_key_free_buffer(struct big_key_buf *buf)
	144	{
	145	unsigned int i;
	146
	147	if (buf->virt) {
	148	memset(buf->virt, 0, buf->nr_pages * PAGE_SIZE);
	149	vunmap(buf->virt);
	150	}
	151
	152	for (i = 0; i < buf->nr_pages; i++)
	153	if (buf->pages[i])
	154	__free_page(buf->pages[i]);
	155
	156	kfree(buf);
	157	}
	158
	159	/*
	160	* Allocate a buffer consisting of a set of pages with a virtual mapping
	161	* applied over them.
	162	*/
	163	static void *big_key_alloc_buffer(size_t len)
	164	{
	165	struct big_key_buf *buf;
	166	unsigned int npg = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
	167	unsigned int i, l;
	168
	169	buf = kzalloc(sizeof(struct big_key_buf) +
	170	sizeof(struct page) * npg +
	171	sizeof(struct scatterlist) * npg,
	172	GFP_KERNEL);
	173	if (!buf)
	174	return NULL;
	175
	176	buf->nr_pages = npg;
	177	buf->sg = (void *)(buf->pages + npg);
	178	sg_init_table(buf->sg, npg);
	179
	180	for (i = 0; i < buf->nr_pages; i++) {
	181	buf->pages[i] = alloc_page(GFP_KERNEL);
	182	if (!buf->pages[i])
	183	goto nomem;
	184
	185	l = min_t(size_t, len, PAGE_SIZE);
	186	sg_set_page(&buf->sg[i], buf->pages[i], l, 0);
	187	len -= l;
	188	}
	189
	190	buf->virt = vmap(buf->pages, buf->nr_pages, VM_MAP, PAGE_KERNEL);
	191	if (!buf->virt)
	192	goto nomem;
	193
	194	return buf;
	195
	196	nomem:
	197	big_key_free_buffer(buf);
	198	return NULL;
	199	}
	200
ab3c3587	201	/*
002edaf7	202	* Preparse a big key
ab3c3587	203	*/
002edaf7	204	int big_key_preparse(struct key_preparsed_payload *prep)
ab3c3587	205	{
d9f4bb1a	206	struct big_key_buf *buf;
146aa8b1	207	struct path path = (struct path )&prep->payload.data[big_key_path];
ab3c3587	208	struct file *file;
13100a72	209	u8 *enckey;
ab3c3587	210	ssize_t written;
d9f4bb1a	211	size_t datalen = prep->datalen, enclen = datalen + ENC_AUTHTAG_SIZE;
ab3c3587 DH	212	int ret;
ab3c3587 DH	213
ab3c3587	214	if (datalen <= 0 \|\| datalen > 1024 * 1024 \|\| !prep->data)
d9f4bb1a	215	return -EINVAL;
ab3c3587 DH	216
ab3c3587 DH	217	/* Set an arbitrary quota */
002edaf7	218	prep->quotalen = 16;
ab3c3587	219
146aa8b1	220	prep->payload.data[big_key_len] = (void *)(unsigned long)datalen;
ab3c3587 DH	221
	222	if (datalen > BIG_KEY_FILE_THRESHOLD) {
	223	/* Create a shmem file to store the data in. This will permit the data
	224	* to be swapped out if needed.
	225	*
13100a72	226	* File content is stored encrypted with randomly generated key.
ab3c3587	227	*/
e13ec939	228	loff_t pos = 0;
13100a72	229
d9f4bb1a DH	230	buf = big_key_alloc_buffer(enclen);
d9f4bb1a DH	231	if (!buf)
13100a72	232	return -ENOMEM;
d9f4bb1a	233	memcpy(buf->virt, prep->data, datalen);
13100a72 KM	234
	235	/* generate random key */
	236	enckey = kmalloc(ENC_KEY_SIZE, GFP_KERNEL);
	237	if (!enckey) {
	238	ret = -ENOMEM;
	239	goto error;
	240	}
428490e3 JD	241	ret = get_random_bytes_wait(enckey, ENC_KEY_SIZE);
428490e3 JD	242	if (unlikely(ret))
13100a72 KM	243	goto err_enckey;
	244
	245	/* encrypt aligned data */
d9f4bb1a	246	ret = big_key_crypt(BIG_KEY_ENC, buf, datalen, enckey);
13100a72 KM	247	if (ret)
	248	goto err_enckey;
	249
	250	/* save aligned data to file */
	251	file = shmem_kernel_file_setup("", enclen, 0);
d2b86970 WY	252	if (IS_ERR(file)) {
d2b86970 WY	253	ret = PTR_ERR(file);
13100a72	254	goto err_enckey;
d2b86970	255	}
ab3c3587	256
d9f4bb1a	257	written = kernel_write(file, buf->virt, enclen, &pos);
13100a72	258	if (written != enclen) {
97826c82	259	ret = written;
ab3c3587 DH	260	if (written >= 0)
	261	ret = -ENOMEM;
	262	goto err_fput;
	263	}
	264
	265	/* Pin the mount and dentry to the key so that we can open it again
	266	* later
	267	*/
13100a72	268	prep->payload.data[big_key_data] = enckey;
ab3c3587 DH	269	*path = file->f_path;
	270	path_get(path);
	271	fput(file);
d9f4bb1a	272	big_key_free_buffer(buf);
ab3c3587 DH	273	} else {
	274	/* Just store the data in a buffer */
	275	void *data = kmalloc(datalen, GFP_KERNEL);
13100a72	276
002edaf7 DH	277	if (!data)
002edaf7 DH	278	return -ENOMEM;
ab3c3587	279
146aa8b1 DH	280	prep->payload.data[big_key_data] = data;
146aa8b1 DH	281	memcpy(data, prep->data, prep->datalen);
ab3c3587 DH	282	}
	283	return 0;
	284
	285	err_fput:
	286	fput(file);
13100a72	287	err_enckey:
91080180	288	kzfree(enckey);
ab3c3587	289	error:
d9f4bb1a	290	big_key_free_buffer(buf);
ab3c3587 DH	291	return ret;
	292	}
	293
002edaf7 DH	294	/*
	295	* Clear preparsement.
	296	*/
	297	void big_key_free_preparse(struct key_preparsed_payload *prep)
	298	{
	299	if (prep->datalen > BIG_KEY_FILE_THRESHOLD) {
146aa8b1	300	struct path path = (struct path )&prep->payload.data[big_key_path];
13100a72	301
002edaf7	302	path_put(path);
002edaf7	303	}
91080180	304	kzfree(prep->payload.data[big_key_data]);
002edaf7 DH	305	}
002edaf7 DH	306
ab3c3587 DH	307	/*
	308	* dispose of the links from a revoked keyring
	309	* - called with the key sem write-locked
	310	*/
	311	void big_key_revoke(struct key *key)
	312	{
146aa8b1	313	struct path path = (struct path )&key->payload.data[big_key_path];
ab3c3587 DH	314
	315	/* clear the quota */
	316	key_payload_reserve(key, 0);
363b02da	317	if (key_is_positive(key) &&
146aa8b1	318	(size_t)key->payload.data[big_key_len] > BIG_KEY_FILE_THRESHOLD)
ab3c3587 DH	319	vfs_truncate(path, 0);
	320	}
	321
	322	/*
	323	* dispose of the data dangling from the corpse of a big_key key
	324	*/
	325	void big_key_destroy(struct key *key)
	326	{
146aa8b1 DH	327	size_t datalen = (size_t)key->payload.data[big_key_len];
146aa8b1 DH	328
13100a72	329	if (datalen > BIG_KEY_FILE_THRESHOLD) {
146aa8b1	330	struct path path = (struct path )&key->payload.data[big_key_path];
13100a72	331
ab3c3587 DH	332	path_put(path);
	333	path->mnt = NULL;
	334	path->dentry = NULL;
ab3c3587	335	}
91080180	336	kzfree(key->payload.data[big_key_data]);
13100a72	337	key->payload.data[big_key_data] = NULL;
ab3c3587 DH	338	}
	339
	340	/*
	341	* describe the big_key key
	342	*/
	343	void big_key_describe(const struct key key, struct seq_file m)
	344	{
146aa8b1	345	size_t datalen = (size_t)key->payload.data[big_key_len];
ab3c3587 DH	346
	347	seq_puts(m, key->description);
	348
363b02da	349	if (key_is_positive(key))
146aa8b1	350	seq_printf(m, ": %zu [%s]",
ab3c3587 DH	351	datalen,
	352	datalen > BIG_KEY_FILE_THRESHOLD ? "file" : "buff");
	353	}
	354
	355	/*
	356	* read the key data
	357	* - the key's semaphore is read-locked
	358	*/
	359	long big_key_read(const struct key key, char __user buffer, size_t buflen)
	360	{
146aa8b1	361	size_t datalen = (size_t)key->payload.data[big_key_len];
ab3c3587 DH	362	long ret;
	363
	364	if (!buffer \|\| buflen < datalen)
	365	return datalen;
	366
	367	if (datalen > BIG_KEY_FILE_THRESHOLD) {
d9f4bb1a	368	struct big_key_buf *buf;
146aa8b1	369	struct path path = (struct path )&key->payload.data[big_key_path];
ab3c3587	370	struct file *file;
13100a72	371	u8 enckey = (u8 )key->payload.data[big_key_data];
428490e3	372	size_t enclen = datalen + ENC_AUTHTAG_SIZE;
bdd1d2d3	373	loff_t pos = 0;
13100a72	374
d9f4bb1a DH	375	buf = big_key_alloc_buffer(enclen);
d9f4bb1a DH	376	if (!buf)
13100a72	377	return -ENOMEM;
ab3c3587 DH	378
ab3c3587 DH	379	file = dentry_open(path, O_RDONLY, current_cred());
13100a72 KM	380	if (IS_ERR(file)) {
	381	ret = PTR_ERR(file);
	382	goto error;
	383	}
ab3c3587	384
13100a72	385	/* read file to kernel and decrypt */
d9f4bb1a	386	ret = kernel_read(file, buf->virt, enclen, &pos);
13100a72	387	if (ret >= 0 && ret != enclen) {
ab3c3587	388	ret = -EIO;
13100a72 KM	389	goto err_fput;
	390	}
	391
d9f4bb1a	392	ret = big_key_crypt(BIG_KEY_DEC, buf, enclen, enckey);
13100a72 KM	393	if (ret)
	394	goto err_fput;
	395
	396	ret = datalen;
	397
	398	/* copy decrypted data to user */
d9f4bb1a	399	if (copy_to_user(buffer, buf->virt, datalen) != 0)
13100a72 KM	400	ret = -EFAULT;
	401
	402	err_fput:
	403	fput(file);
	404	error:
d9f4bb1a	405	big_key_free_buffer(buf);
ab3c3587 DH	406	} else {
ab3c3587 DH	407	ret = datalen;
146aa8b1 DH	408	if (copy_to_user(buffer, key->payload.data[big_key_data],
146aa8b1 DH	409	datalen) != 0)
ab3c3587 DH	410	ret = -EFAULT;
	411	}
	412
	413	return ret;
	414	}
	415
13100a72 KM	416	/*
	417	* Register key type
	418	*/
ab3c3587 DH	419	static int __init big_key_init(void)
ab3c3587 DH	420	{
7df3e59c	421	int ret;
13100a72	422
13100a72	423	/* init block cipher */
428490e3 JD	424	big_key_aead = crypto_alloc_aead(big_key_alg_name, 0, CRYPTO_ALG_ASYNC);
	425	if (IS_ERR(big_key_aead)) {
	426	ret = PTR_ERR(big_key_aead);
7df3e59c	427	pr_err("Can't alloc crypto: %d\n", ret);
428490e3 JD	428	return ret;
428490e3 JD	429	}
a964f395 TA	430
	431	if (unlikely(crypto_aead_ivsize(big_key_aead) != BIG_KEY_IV_SIZE)) {
	432	WARN(1, "big key algorithm changed?");
	433	ret = -EINVAL;
	434	goto free_aead;
	435	}
	436
428490e3 JD	437	ret = crypto_aead_setauthsize(big_key_aead, ENC_AUTHTAG_SIZE);
	438	if (ret < 0) {
	439	pr_err("Can't set crypto auth tag len: %d\n", ret);
	440	goto free_aead;
7df3e59c	441	}
7df3e59c DH	442
	443	ret = register_key_type(&key_type_big_key);
	444	if (ret < 0) {
	445	pr_err("Can't register type: %d\n", ret);
428490e3	446	goto free_aead;
13100a72 KM	447	}
	448
	449	return 0;
	450
428490e3 JD	451	free_aead:
428490e3 JD	452	crypto_free_aead(big_key_aead);
13100a72 KM	453	return ret;
	454	}
	455
7df3e59c	456	late_initcall(big_key_init);