[linux-2.6-block.git] / security / integrity / evm / evm_crypto.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2005-2010 IBM Corporation
 *
 * Authors:
 * Mimi Zohar <zohar@us.ibm.com>
 * Kylene Hall <kjhall@us.ibm.com>
 *
 * File: evm_crypto.c
 *	 Using root's kernel master key (kmk), calculate the HMAC
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/export.h>
#include <linux/crypto.h>
#include <linux/xattr.h>
#include <linux/evm.h>
#include <keys/encrypted-type.h>
#include <crypto/hash.h>
#include <crypto/hash_info.h>
#include "evm.h"

#define EVMKEY "evm-key"
#define MAX_KEY_SIZE 128
static unsigned char evmkey[MAX_KEY_SIZE];
static const int evmkey_len = MAX_KEY_SIZE;

struct crypto_shash *hmac_tfm;
static struct crypto_shash *evm_tfm[HASH_ALGO__LAST];

static DEFINE_MUTEX(mutex);

#define EVM_SET_KEY_BUSY 0

static unsigned long evm_set_key_flags;

static const char evm_hmac[] = "hmac(sha1)";

/**
 * evm_set_key() - set EVM HMAC key from the kernel
 * @key: pointer to a buffer with the key data
 * @size: length of the key data
 *
 * This function allows setting the EVM HMAC key from the kernel
 * without using the "encrypted" key subsystem keys. It can be used
 * by the crypto HW kernel module which has its own way of managing
 * keys.
 *
 * key length should be between 32 and 128 bytes long
 */
int evm_set_key(void *key, size_t keylen)
{
	int rc;

	rc = -EBUSY;
	if (test_and_set_bit(EVM_SET_KEY_BUSY, &evm_set_key_flags))
		goto busy;
	rc = -EINVAL;
	if (keylen > MAX_KEY_SIZE)
		goto inval;
	memcpy(evmkey, key, keylen);
	evm_initialized |= EVM_INIT_HMAC;
	pr_info("key initialized\n");
	return 0;
inval:
	clear_bit(EVM_SET_KEY_BUSY, &evm_set_key_flags);
busy:
	pr_err("key initialization failed\n");
	return rc;
}
EXPORT_SYMBOL_GPL(evm_set_key);

static struct shash_desc *init_desc(char type, uint8_t hash_algo)
{
	long rc;
	const char *algo;
	struct crypto_shash **tfm;
	struct shash_desc *desc;

	if (type == EVM_XATTR_HMAC) {
		if (!(evm_initialized & EVM_INIT_HMAC)) {
			pr_err_once("HMAC key is not set\n");
			return ERR_PTR(-ENOKEY);
		}
		tfm = &hmac_tfm;
		algo = evm_hmac;
	} else {
		if (hash_algo >= HASH_ALGO__LAST)
			return ERR_PTR(-EINVAL);

		tfm = &evm_tfm[hash_algo];
		algo = hash_algo_name[hash_algo];
	}

	if (*tfm == NULL) {
		mutex_lock(&mutex);
		if (*tfm)
			goto out;
		*tfm = crypto_alloc_shash(algo, 0, CRYPTO_NOLOAD);
		if (IS_ERR(*tfm)) {
			rc = PTR_ERR(*tfm);
			pr_err("Can not allocate %s (reason: %ld)\n", algo, rc);
			*tfm = NULL;
			mutex_unlock(&mutex);
			return ERR_PTR(rc);
		}
		if (type == EVM_XATTR_HMAC) {
			rc = crypto_shash_setkey(*tfm, evmkey, evmkey_len);
			if (rc) {
				crypto_free_shash(*tfm);
				*tfm = NULL;
				mutex_unlock(&mutex);
				return ERR_PTR(rc);
			}
		}
out:
		mutex_unlock(&mutex);
	}

	desc = kmalloc(sizeof(*desc) + crypto_shash_descsize(*tfm),
			GFP_KERNEL);
	if (!desc)
		return ERR_PTR(-ENOMEM);

	desc->tfm = *tfm;

	rc = crypto_shash_init(desc);
	if (rc) {
		kfree(desc);
		return ERR_PTR(rc);
	}
	return desc;
}

/* Protect against 'cutting & pasting' security.evm xattr, include inode
 * specific info.
 *
 * (Additional directory/file metadata needs to be added for more complete
 * protection.)
 */
static void hmac_add_misc(struct shash_desc *desc, struct inode *inode,
			  char type, char *digest)
{
	struct h_misc {
		unsigned long ino;
		__u32 generation;
		uid_t uid;
		gid_t gid;
		umode_t mode;
	} hmac_misc;

	memset(&hmac_misc, 0, sizeof(hmac_misc));
	/* Don't include the inode or generation number in portable
	 * signatures
	 */
	if (type != EVM_XATTR_PORTABLE_DIGSIG) {
		hmac_misc.ino = inode->i_ino;
		hmac_misc.generation = inode->i_generation;
	}
	/* The hmac uid and gid must be encoded in the initial user
	 * namespace (not the filesystems user namespace) as encoding
	 * them in the filesystems user namespace allows an attack
	 * where first they are written in an unprivileged fuse mount
	 * of a filesystem and then the system is tricked to mount the
	 * filesystem for real on next boot and trust it because
	 * everything is signed.
	 */
	hmac_misc.uid = from_kuid(&init_user_ns, inode->i_uid);
	hmac_misc.gid = from_kgid(&init_user_ns, inode->i_gid);
	hmac_misc.mode = inode->i_mode;
	crypto_shash_update(desc, (const u8 *)&hmac_misc, sizeof(hmac_misc));
	if ((evm_hmac_attrs & EVM_ATTR_FSUUID) &&
	    type != EVM_XATTR_PORTABLE_DIGSIG)
		crypto_shash_update(desc, (u8 *)&inode->i_sb->s_uuid, UUID_SIZE);
	crypto_shash_final(desc, digest);
}

/*
 * Calculate the HMAC value across the set of protected security xattrs.
 *
 * Instead of retrieving the requested xattr, for performance, calculate
 * the hmac using the requested xattr value. Don't alloc/free memory for
 * each xattr, but attempt to re-use the previously allocated memory.
 */
static int evm_calc_hmac_or_hash(struct dentry *dentry,
				 const char *req_xattr_name,
				 const char *req_xattr_value,
				 size_t req_xattr_value_len,
				 uint8_t type, struct evm_digest *data)
{
	struct inode *inode = d_backing_inode(dentry);
	struct xattr_list *xattr;
	struct shash_desc *desc;
	size_t xattr_size = 0;
	char *xattr_value = NULL;
	int error;
	int size;
	bool ima_present = false;

	if (!(inode->i_opflags & IOP_XATTR) ||
	    inode->i_sb->s_user_ns != &init_user_ns)
		return -EOPNOTSUPP;

	desc = init_desc(type, data->hdr.algo);
	if (IS_ERR(desc))
		return PTR_ERR(desc);

	data->hdr.length = crypto_shash_digestsize(desc->tfm);

	error = -ENODATA;
	list_for_each_entry_rcu(xattr, &evm_config_xattrnames, list) {
		bool is_ima = false;

		if (strcmp(xattr->name, XATTR_NAME_IMA) == 0)
			is_ima = true;

		if ((req_xattr_name && req_xattr_value)
		    && !strcmp(xattr->name, req_xattr_name)) {
			error = 0;
			crypto_shash_update(desc, (const u8 *)req_xattr_value,
					     req_xattr_value_len);
			if (is_ima)
				ima_present = true;
			continue;
		}
		size = vfs_getxattr_alloc(dentry, xattr->name,
					  &xattr_value, xattr_size, GFP_NOFS);
		if (size == -ENOMEM) {
			error = -ENOMEM;
			goto out;
		}
		if (size < 0)
			continue;

		error = 0;
		xattr_size = size;
		crypto_shash_update(desc, (const u8 *)xattr_value, xattr_size);
		if (is_ima)
			ima_present = true;
	}
	hmac_add_misc(desc, inode, type, data->digest);

	/* Portable EVM signatures must include an IMA hash */
	if (type == EVM_XATTR_PORTABLE_DIGSIG && !ima_present)
		return -EPERM;
out:
	kfree(xattr_value);
	kfree(desc);
	return error;
}

int evm_calc_hmac(struct dentry *dentry, const char *req_xattr_name,
		  const char *req_xattr_value, size_t req_xattr_value_len,
		  struct evm_digest *data)
{
	return evm_calc_hmac_or_hash(dentry, req_xattr_name, req_xattr_value,
				    req_xattr_value_len, EVM_XATTR_HMAC, data);
}

int evm_calc_hash(struct dentry *dentry, const char *req_xattr_name,
		  const char *req_xattr_value, size_t req_xattr_value_len,
		  char type, struct evm_digest *data)
{
	return evm_calc_hmac_or_hash(dentry, req_xattr_name, req_xattr_value,
				     req_xattr_value_len, type, data);
}

static int evm_is_immutable(struct dentry *dentry, struct inode *inode)
{
	const struct evm_ima_xattr_data *xattr_data = NULL;
	struct integrity_iint_cache *iint;
	int rc = 0;

	iint = integrity_iint_find(inode);
	if (iint && (iint->flags & EVM_IMMUTABLE_DIGSIG))
		return 1;

	/* Do this the hard way */
	rc = vfs_getxattr_alloc(dentry, XATTR_NAME_EVM, (char **)&xattr_data, 0,
				GFP_NOFS);
	if (rc <= 0) {
		if (rc == -ENODATA)
			return 0;
		return rc;
	}
	if (xattr_data->type == EVM_XATTR_PORTABLE_DIGSIG)
		rc = 1;
	else
		rc = 0;

	kfree(xattr_data);
	return rc;
}


/*
 * Calculate the hmac and update security.evm xattr
 *
 * Expects to be called with i_mutex locked.
 */
int evm_update_evmxattr(struct dentry *dentry, const char *xattr_name,
			const char *xattr_value, size_t xattr_value_len)
{
	struct inode *inode = d_backing_inode(dentry);
	struct evm_digest data;
	int rc = 0;

	/*
	 * Don't permit any transformation of the EVM xattr if the signature
	 * is of an immutable type
	 */
	rc = evm_is_immutable(dentry, inode);
	if (rc < 0)
		return rc;
	if (rc)
		return -EPERM;

	data.hdr.algo = HASH_ALGO_SHA1;
	rc = evm_calc_hmac(dentry, xattr_name, xattr_value,
			   xattr_value_len, &data);
	if (rc == 0) {
		data.hdr.xattr.sha1.type = EVM_XATTR_HMAC;
		rc = __vfs_setxattr_noperm(dentry, XATTR_NAME_EVM,
					   &data.hdr.xattr.data[1],
					   SHA1_DIGEST_SIZE + 1, 0);
	} else if (rc == -ENODATA && (inode->i_opflags & IOP_XATTR)) {
		rc = __vfs_removexattr(dentry, XATTR_NAME_EVM);
	}
	return rc;
}

int evm_init_hmac(struct inode *inode, const struct xattr *lsm_xattr,
		  char *hmac_val)
{
	struct shash_desc *desc;

	desc = init_desc(EVM_XATTR_HMAC, HASH_ALGO_SHA1);
	if (IS_ERR(desc)) {
		pr_info("init_desc failed\n");
		return PTR_ERR(desc);
	}

	crypto_shash_update(desc, lsm_xattr->value, lsm_xattr->value_len);
	hmac_add_misc(desc, inode, EVM_XATTR_HMAC, hmac_val);
	kfree(desc);
	return 0;
}

/*
 * Get the key from the TPM for the SHA1-HMAC
 */
int evm_init_key(void)
{
	struct key *evm_key;
	struct encrypted_key_payload *ekp;
	int rc;

	evm_key = request_key(&key_type_encrypted, EVMKEY, NULL);
	if (IS_ERR(evm_key))
		return -ENOENT;

	down_read(&evm_key->sem);
	ekp = evm_key->payload.data[0];

	rc = evm_set_key(ekp->decrypted_data, ekp->decrypted_datalen);

	/* burn the original key contents */
	memset(ekp->decrypted_data, 0, ekp->decrypted_datalen);
	up_read(&evm_key->sem);
	key_put(evm_key);
	return rc;
}
Commit	Line	Data
b886d83c	1	// SPDX-License-Identifier: GPL-2.0-only
66dbc325 MZ	2	/*
	3	* Copyright (C) 2005-2010 IBM Corporation
	4	*
	5	* Authors:
	6	* Mimi Zohar <zohar@us.ibm.com>
	7	* Kylene Hall <kjhall@us.ibm.com>
	8	*
66dbc325 MZ	9	* File: evm_crypto.c
	10	* Using root's kernel master key (kmk), calculate the HMAC
	11	*/
	12
20ee451f JP	13	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
20ee451f JP	14
876979c9	15	#include <linux/export.h>
66dbc325 MZ	16	#include <linux/crypto.h>
66dbc325 MZ	17	#include <linux/xattr.h>
76266763	18	#include <linux/evm.h>
66dbc325	19	#include <keys/encrypted-type.h>
d46eb369	20	#include <crypto/hash.h>
5feeb611	21	#include <crypto/hash_info.h>
66dbc325 MZ	22	#include "evm.h"
	23
	24	#define EVMKEY "evm-key"
	25	#define MAX_KEY_SIZE 128
	26	static unsigned char evmkey[MAX_KEY_SIZE];
b2724d58	27	static const int evmkey_len = MAX_KEY_SIZE;
66dbc325	28
d46eb369	29	struct crypto_shash *hmac_tfm;
5feeb611	30	static struct crypto_shash *evm_tfm[HASH_ALGO__LAST];
d46eb369	31
97426f98 DK	32	static DEFINE_MUTEX(mutex);
97426f98 DK	33
76266763 DK	34	#define EVM_SET_KEY_BUSY 0
	35
	36	static unsigned long evm_set_key_flags;
	37
b2724d58	38	static const char evm_hmac[] = "hmac(sha1)";
1a82cee3	39
76266763 DK	40	/**
	41	* evm_set_key() - set EVM HMAC key from the kernel
	42	* @key: pointer to a buffer with the key data
	43	* @size: length of the key data
	44	*
	45	* This function allows setting the EVM HMAC key from the kernel
	46	* without using the "encrypted" key subsystem keys. It can be used
	47	* by the crypto HW kernel module which has its own way of managing
	48	* keys.
	49	*
	50	* key length should be between 32 and 128 bytes long
	51	*/
	52	int evm_set_key(void *key, size_t keylen)
	53	{
	54	int rc;
	55
	56	rc = -EBUSY;
	57	if (test_and_set_bit(EVM_SET_KEY_BUSY, &evm_set_key_flags))
	58	goto busy;
	59	rc = -EINVAL;
	60	if (keylen > MAX_KEY_SIZE)
	61	goto inval;
	62	memcpy(evmkey, key, keylen);
	63	evm_initialized \|= EVM_INIT_HMAC;
	64	pr_info("key initialized\n");
	65	return 0;
	66	inval:
	67	clear_bit(EVM_SET_KEY_BUSY, &evm_set_key_flags);
	68	busy:
	69	pr_err("key initialization failed\n");
	70	return rc;
	71	}
	72	EXPORT_SYMBOL_GPL(evm_set_key);
	73
5feeb611	74	static struct shash_desc *init_desc(char type, uint8_t hash_algo)
66dbc325	75	{
143b01d3	76	long rc;
5feeb611	77	const char *algo;
15647eb3	78	struct crypto_shash **tfm;
d46eb369 DK	79	struct shash_desc *desc;
d46eb369 DK	80
15647eb3	81	if (type == EVM_XATTR_HMAC) {
26ddabfe	82	if (!(evm_initialized & EVM_INIT_HMAC)) {
0485d066	83	pr_err_once("HMAC key is not set\n");
26ddabfe DK	84	return ERR_PTR(-ENOKEY);
26ddabfe DK	85	}
15647eb3 DK	86	tfm = &hmac_tfm;
	87	algo = evm_hmac;
	88	} else {
221be106 RS	89	if (hash_algo >= HASH_ALGO__LAST)
	90	return ERR_PTR(-EINVAL);
	91
5feeb611 MG	92	tfm = &evm_tfm[hash_algo];
5feeb611 MG	93	algo = hash_algo_name[hash_algo];
15647eb3 DK	94	}
	95
	96	if (*tfm == NULL) {
97426f98	97	mutex_lock(&mutex);
143b01d3	98	if (*tfm)
97426f98	99	goto out;
3d234b33	100	*tfm = crypto_alloc_shash(algo, 0, CRYPTO_NOLOAD);
15647eb3	101	if (IS_ERR(*tfm)) {
15647eb3	102	rc = PTR_ERR(*tfm);
143b01d3	103	pr_err("Can not allocate %s (reason: %ld)\n", algo, rc);
15647eb3	104	*tfm = NULL;
97426f98	105	mutex_unlock(&mutex);
d46eb369 DK	106	return ERR_PTR(rc);
d46eb369 DK	107	}
88d7ed35 DK	108	if (type == EVM_XATTR_HMAC) {
	109	rc = crypto_shash_setkey(*tfm, evmkey, evmkey_len);
	110	if (rc) {
	111	crypto_free_shash(*tfm);
	112	*tfm = NULL;
143b01d3	113	mutex_unlock(&mutex);
88d7ed35 DK	114	return ERR_PTR(rc);
88d7ed35 DK	115	}
d21b5945	116	}
97426f98 DK	117	out:
97426f98 DK	118	mutex_unlock(&mutex);
66dbc325	119	}
d46eb369	120
15647eb3	121	desc = kmalloc(sizeof(desc) + crypto_shash_descsize(tfm),
d46eb369 DK	122	GFP_KERNEL);
	123	if (!desc)
	124	return ERR_PTR(-ENOMEM);
	125
15647eb3	126	desc->tfm = *tfm;
d46eb369	127
d46eb369	128	rc = crypto_shash_init(desc);
d46eb369 DK	129	if (rc) {
	130	kfree(desc);
	131	return ERR_PTR(rc);
	132	}
	133	return desc;
66dbc325 MZ	134	}
	135
	136	/* Protect against 'cutting & pasting' security.evm xattr, include inode
	137	* specific info.
	138	*
	139	* (Additional directory/file metadata needs to be added for more complete
	140	* protection.)
	141	*/
d46eb369	142	static void hmac_add_misc(struct shash_desc desc, struct inode inode,
50b97748	143	char type, char *digest)
66dbc325 MZ	144	{
	145	struct h_misc {
	146	unsigned long ino;
	147	__u32 generation;
	148	uid_t uid;
	149	gid_t gid;
	150	umode_t mode;
	151	} hmac_misc;
66dbc325	152
2bb930ab	153	memset(&hmac_misc, 0, sizeof(hmac_misc));
50b97748 MG	154	/* Don't include the inode or generation number in portable
	155	* signatures
	156	*/
	157	if (type != EVM_XATTR_PORTABLE_DIGSIG) {
	158	hmac_misc.ino = inode->i_ino;
	159	hmac_misc.generation = inode->i_generation;
	160	}
19339c25 EB	161	/* The hmac uid and gid must be encoded in the initial user
	162	* namespace (not the filesystems user namespace) as encoding
	163	* them in the filesystems user namespace allows an attack
	164	* where first they are written in an unprivileged fuse mount
	165	* of a filesystem and then the system is tricked to mount the
	166	* filesystem for real on next boot and trust it because
	167	* everything is signed.
	168	*/
	169	hmac_misc.uid = from_kuid(&init_user_ns, inode->i_uid);
	170	hmac_misc.gid = from_kgid(&init_user_ns, inode->i_gid);
66dbc325	171	hmac_misc.mode = inode->i_mode;
2bb930ab	172	crypto_shash_update(desc, (const u8 *)&hmac_misc, sizeof(hmac_misc));
50b97748 MG	173	if ((evm_hmac_attrs & EVM_ATTR_FSUUID) &&
50b97748 MG	174	type != EVM_XATTR_PORTABLE_DIGSIG)
e7fde070	175	crypto_shash_update(desc, (u8 *)&inode->i_sb->s_uuid, UUID_SIZE);
d46eb369	176	crypto_shash_final(desc, digest);
66dbc325 MZ	177	}
	178
	179	/*
	180	* Calculate the HMAC value across the set of protected security xattrs.
	181	*
	182	* Instead of retrieving the requested xattr, for performance, calculate
	183	* the hmac using the requested xattr value. Don't alloc/free memory for
	184	* each xattr, but attempt to re-use the previously allocated memory.
	185	*/
15647eb3	186	static int evm_calc_hmac_or_hash(struct dentry *dentry,
5feeb611 MG	187	const char *req_xattr_name,
	188	const char *req_xattr_value,
	189	size_t req_xattr_value_len,
	190	uint8_t type, struct evm_digest *data)
66dbc325	191	{
c6f493d6	192	struct inode *inode = d_backing_inode(dentry);
21af7663	193	struct xattr_list *xattr;
d46eb369	194	struct shash_desc *desc;
66dbc325 MZ	195	size_t xattr_size = 0;
	196	char *xattr_value = NULL;
	197	int error;
	198	int size;
50b97748	199	bool ima_present = false;
66dbc325	200
a3a5c966 SF	201	if (!(inode->i_opflags & IOP_XATTR) \|\|
a3a5c966 SF	202	inode->i_sb->s_user_ns != &init_user_ns)
66dbc325	203	return -EOPNOTSUPP;
5d6c3191	204
5feeb611	205	desc = init_desc(type, data->hdr.algo);
d46eb369 DK	206	if (IS_ERR(desc))
d46eb369 DK	207	return PTR_ERR(desc);
66dbc325	208
5feeb611 MG	209	data->hdr.length = crypto_shash_digestsize(desc->tfm);
5feeb611 MG	210
66dbc325	211	error = -ENODATA;
fa516b66	212	list_for_each_entry_rcu(xattr, &evm_config_xattrnames, list) {
50b97748 MG	213	bool is_ima = false;
50b97748 MG	214
21af7663	215	if (strcmp(xattr->name, XATTR_NAME_IMA) == 0)
50b97748 MG	216	is_ima = true;
50b97748 MG	217
66dbc325	218	if ((req_xattr_name && req_xattr_value)
21af7663	219	&& !strcmp(xattr->name, req_xattr_name)) {
66dbc325	220	error = 0;
d46eb369 DK	221	crypto_shash_update(desc, (const u8 *)req_xattr_value,
d46eb369 DK	222	req_xattr_value_len);
50b97748 MG	223	if (is_ima)
50b97748 MG	224	ima_present = true;
66dbc325 MZ	225	continue;
66dbc325 MZ	226	}
21af7663	227	size = vfs_getxattr_alloc(dentry, xattr->name,
66dbc325 MZ	228	&xattr_value, xattr_size, GFP_NOFS);
	229	if (size == -ENOMEM) {
	230	error = -ENOMEM;
	231	goto out;
	232	}
	233	if (size < 0)
	234	continue;
	235
	236	error = 0;
	237	xattr_size = size;
d46eb369	238	crypto_shash_update(desc, (const u8 *)xattr_value, xattr_size);
50b97748 MG	239	if (is_ima)
50b97748 MG	240	ima_present = true;
66dbc325	241	}
5feeb611	242	hmac_add_misc(desc, inode, type, data->digest);
d46eb369	243
50b97748 MG	244	/* Portable EVM signatures must include an IMA hash */
	245	if (type == EVM_XATTR_PORTABLE_DIGSIG && !ima_present)
	246	return -EPERM;
66dbc325	247	out:
d46eb369 DK	248	kfree(xattr_value);
d46eb369 DK	249	kfree(desc);
66dbc325 MZ	250	return error;
	251	}
	252
15647eb3 DK	253	int evm_calc_hmac(struct dentry dentry, const char req_xattr_name,
15647eb3 DK	254	const char *req_xattr_value, size_t req_xattr_value_len,
5feeb611	255	struct evm_digest *data)
15647eb3 DK	256	{
15647eb3 DK	257	return evm_calc_hmac_or_hash(dentry, req_xattr_name, req_xattr_value,
5feeb611	258	req_xattr_value_len, EVM_XATTR_HMAC, data);
15647eb3 DK	259	}
	260
	261	int evm_calc_hash(struct dentry dentry, const char req_xattr_name,
	262	const char *req_xattr_value, size_t req_xattr_value_len,
5feeb611	263	char type, struct evm_digest *data)
15647eb3 DK	264	{
15647eb3 DK	265	return evm_calc_hmac_or_hash(dentry, req_xattr_name, req_xattr_value,
5feeb611	266	req_xattr_value_len, type, data);
50b97748 MG	267	}
	268
	269	static int evm_is_immutable(struct dentry dentry, struct inode inode)
	270	{
	271	const struct evm_ima_xattr_data *xattr_data = NULL;
	272	struct integrity_iint_cache *iint;
	273	int rc = 0;
	274
	275	iint = integrity_iint_find(inode);
	276	if (iint && (iint->flags & EVM_IMMUTABLE_DIGSIG))
	277	return 1;
	278
	279	/* Do this the hard way */
	280	rc = vfs_getxattr_alloc(dentry, XATTR_NAME_EVM, (char **)&xattr_data, 0,
	281	GFP_NOFS);
	282	if (rc <= 0) {
	283	if (rc == -ENODATA)
	284	return 0;
	285	return rc;
	286	}
	287	if (xattr_data->type == EVM_XATTR_PORTABLE_DIGSIG)
	288	rc = 1;
	289	else
	290	rc = 0;
	291
	292	kfree(xattr_data);
	293	return rc;
15647eb3 DK	294	}
15647eb3 DK	295
50b97748	296
66dbc325 MZ	297	/*
	298	* Calculate the hmac and update security.evm xattr
	299	*
	300	* Expects to be called with i_mutex locked.
	301	*/
	302	int evm_update_evmxattr(struct dentry dentry, const char xattr_name,
	303	const char *xattr_value, size_t xattr_value_len)
	304	{
c6f493d6	305	struct inode *inode = d_backing_inode(dentry);
5feeb611	306	struct evm_digest data;
66dbc325 MZ	307	int rc = 0;
66dbc325 MZ	308
50b97748 MG	309	/*
	310	* Don't permit any transformation of the EVM xattr if the signature
	311	* is of an immutable type
	312	*/
	313	rc = evm_is_immutable(dentry, inode);
	314	if (rc < 0)
	315	return rc;
	316	if (rc)
	317	return -EPERM;
	318
5feeb611	319	data.hdr.algo = HASH_ALGO_SHA1;
66dbc325	320	rc = evm_calc_hmac(dentry, xattr_name, xattr_value,
5feeb611	321	xattr_value_len, &data);
6be5cc52	322	if (rc == 0) {
5feeb611	323	data.hdr.xattr.sha1.type = EVM_XATTR_HMAC;
66dbc325	324	rc = __vfs_setxattr_noperm(dentry, XATTR_NAME_EVM,
5feeb611 MG	325	&data.hdr.xattr.data[1],
5feeb611 MG	326	SHA1_DIGEST_SIZE + 1, 0);
5d6c3191 AG	327	} else if (rc == -ENODATA && (inode->i_opflags & IOP_XATTR)) {
5d6c3191 AG	328	rc = __vfs_removexattr(dentry, XATTR_NAME_EVM);
a67adb99	329	}
66dbc325 MZ	330	return rc;
	331	}
	332
cb723180 MZ	333	int evm_init_hmac(struct inode inode, const struct xattr lsm_xattr,
	334	char *hmac_val)
	335	{
d46eb369	336	struct shash_desc *desc;
cb723180	337
5feeb611	338	desc = init_desc(EVM_XATTR_HMAC, HASH_ALGO_SHA1);
d46eb369	339	if (IS_ERR(desc)) {
20ee451f	340	pr_info("init_desc failed\n");
d46eb369	341	return PTR_ERR(desc);
cb723180 MZ	342	}
cb723180 MZ	343
d46eb369	344	crypto_shash_update(desc, lsm_xattr->value, lsm_xattr->value_len);
50b97748	345	hmac_add_misc(desc, inode, EVM_XATTR_HMAC, hmac_val);
d46eb369	346	kfree(desc);
cb723180 MZ	347	return 0;
	348	}
	349
66dbc325 MZ	350	/*
	351	* Get the key from the TPM for the SHA1-HMAC
	352	*/
	353	int evm_init_key(void)
	354	{
	355	struct key *evm_key;
	356	struct encrypted_key_payload *ekp;
76266763	357	int rc;
66dbc325 MZ	358
	359	evm_key = request_key(&key_type_encrypted, EVMKEY, NULL);
	360	if (IS_ERR(evm_key))
	361	return -ENOENT;
	362
	363	down_read(&evm_key->sem);
146aa8b1	364	ekp = evm_key->payload.data[0];
76266763 DK	365
	366	rc = evm_set_key(ekp->decrypted_data, ekp->decrypted_datalen);
	367
66dbc325 MZ	368	/* burn the original key contents */
	369	memset(ekp->decrypted_data, 0, ekp->decrypted_datalen);
	370	up_read(&evm_key->sem);
	371	key_put(evm_key);
	372	return rc;
	373	}