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