[mirror_ubuntu-jammy-kernel.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 <keys/user-type.h>
#include <keys/big_key-type.h>
#include <crypto/aead.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)";

/*
 * 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[crypto_aead_ivsize(big_key_aead)];

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