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

/*
 * Copyright (C) 2005-2010 IBM Corporation
 *
 * Authors:
 * Mimi Zohar <zohar@us.ibm.com>
 * Kylene Hall <kjhall@us.ibm.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, version 2 of the License.
 *
 * File: evm_crypto.c
 *	 Using root's kernel master key (kmk), calculate the HMAC
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.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 {
		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_ALG_ASYNC | 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;
	desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP;

	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, &inode->i_sb->s_uuid.b[0],
				    sizeof(inode->i_sb->s_uuid));
	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
66dbc325 MZ	1	/*
	2	* Copyright (C) 2005-2010 IBM Corporation
	3	*
	4	* Authors:
	5	* Mimi Zohar <zohar@us.ibm.com>
	6	* Kylene Hall <kjhall@us.ibm.com>
	7	*
	8	* This program is free software; you can redistribute it and/or modify
	9	* it under the terms of the GNU General Public License as published by
	10	* the Free Software Foundation, version 2 of the License.
	11	*
	12	* File: evm_crypto.c
	13	* Using root's kernel master key (kmk), calculate the HMAC
	14	*/
	15
20ee451f JP	16	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
20ee451f JP	17
66dbc325 MZ	18	#include <linux/module.h>
	19	#include <linux/crypto.h>
	20	#include <linux/xattr.h>
76266763	21	#include <linux/evm.h>
66dbc325	22	#include <keys/encrypted-type.h>
d46eb369	23	#include <crypto/hash.h>
5feeb611	24	#include <crypto/hash_info.h>
66dbc325 MZ	25	#include "evm.h"
	26
	27	#define EVMKEY "evm-key"
	28	#define MAX_KEY_SIZE 128
	29	static unsigned char evmkey[MAX_KEY_SIZE];
b2724d58	30	static const int evmkey_len = MAX_KEY_SIZE;
66dbc325	31
d46eb369	32	struct crypto_shash *hmac_tfm;
5feeb611	33	static struct crypto_shash *evm_tfm[HASH_ALGO__LAST];
d46eb369	34
97426f98 DK	35	static DEFINE_MUTEX(mutex);
97426f98 DK	36
76266763 DK	37	#define EVM_SET_KEY_BUSY 0
	38
	39	static unsigned long evm_set_key_flags;
	40
b2724d58	41	static const char evm_hmac[] = "hmac(sha1)";
1a82cee3	42
76266763 DK	43	/**
	44	* evm_set_key() - set EVM HMAC key from the kernel
	45	* @key: pointer to a buffer with the key data
	46	* @size: length of the key data
	47	*
	48	* This function allows setting the EVM HMAC key from the kernel
	49	* without using the "encrypted" key subsystem keys. It can be used
	50	* by the crypto HW kernel module which has its own way of managing
	51	* keys.
	52	*
	53	* key length should be between 32 and 128 bytes long
	54	*/
	55	int evm_set_key(void *key, size_t keylen)
	56	{
	57	int rc;
	58
	59	rc = -EBUSY;
	60	if (test_and_set_bit(EVM_SET_KEY_BUSY, &evm_set_key_flags))
	61	goto busy;
	62	rc = -EINVAL;
	63	if (keylen > MAX_KEY_SIZE)
	64	goto inval;
	65	memcpy(evmkey, key, keylen);
	66	evm_initialized \|= EVM_INIT_HMAC;
	67	pr_info("key initialized\n");
	68	return 0;
	69	inval:
	70	clear_bit(EVM_SET_KEY_BUSY, &evm_set_key_flags);
	71	busy:
	72	pr_err("key initialization failed\n");
	73	return rc;
	74	}
	75	EXPORT_SYMBOL_GPL(evm_set_key);
	76
5feeb611	77	static struct shash_desc *init_desc(char type, uint8_t hash_algo)
66dbc325	78	{
143b01d3	79	long rc;
5feeb611	80	const char *algo;
15647eb3	81	struct crypto_shash **tfm;
d46eb369 DK	82	struct shash_desc *desc;
d46eb369 DK	83
15647eb3	84	if (type == EVM_XATTR_HMAC) {
26ddabfe	85	if (!(evm_initialized & EVM_INIT_HMAC)) {
0485d066	86	pr_err_once("HMAC key is not set\n");
26ddabfe DK	87	return ERR_PTR(-ENOKEY);
26ddabfe DK	88	}
15647eb3 DK	89	tfm = &hmac_tfm;
	90	algo = evm_hmac;
	91	} else {
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;
e2861fa7 MG	100	*tfm = crypto_alloc_shash(algo, 0,
e2861fa7 MG	101	CRYPTO_ALG_ASYNC \| CRYPTO_NOLOAD);
15647eb3	102	if (IS_ERR(*tfm)) {
15647eb3	103	rc = PTR_ERR(*tfm);
143b01d3	104	pr_err("Can not allocate %s (reason: %ld)\n", algo, rc);
15647eb3	105	*tfm = NULL;
97426f98	106	mutex_unlock(&mutex);
d46eb369 DK	107	return ERR_PTR(rc);
d46eb369 DK	108	}
88d7ed35 DK	109	if (type == EVM_XATTR_HMAC) {
	110	rc = crypto_shash_setkey(*tfm, evmkey, evmkey_len);
	111	if (rc) {
	112	crypto_free_shash(*tfm);
	113	*tfm = NULL;
143b01d3	114	mutex_unlock(&mutex);
88d7ed35 DK	115	return ERR_PTR(rc);
88d7ed35 DK	116	}
d21b5945	117	}
97426f98 DK	118	out:
97426f98 DK	119	mutex_unlock(&mutex);
66dbc325	120	}
d46eb369	121
15647eb3	122	desc = kmalloc(sizeof(desc) + crypto_shash_descsize(tfm),
d46eb369 DK	123	GFP_KERNEL);
	124	if (!desc)
	125	return ERR_PTR(-ENOMEM);
	126
15647eb3	127	desc->tfm = *tfm;
d46eb369 DK	128	desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP;
d46eb369 DK	129
d46eb369	130	rc = crypto_shash_init(desc);
d46eb369 DK	131	if (rc) {
	132	kfree(desc);
	133	return ERR_PTR(rc);
	134	}
	135	return desc;
66dbc325 MZ	136	}
	137
	138	/* Protect against 'cutting & pasting' security.evm xattr, include inode
	139	* specific info.
	140	*
	141	* (Additional directory/file metadata needs to be added for more complete
	142	* protection.)
	143	*/
d46eb369	144	static void hmac_add_misc(struct shash_desc desc, struct inode inode,
50b97748	145	char type, char *digest)
66dbc325 MZ	146	{
	147	struct h_misc {
	148	unsigned long ino;
	149	__u32 generation;
	150	uid_t uid;
	151	gid_t gid;
	152	umode_t mode;
	153	} hmac_misc;
66dbc325	154
2bb930ab	155	memset(&hmac_misc, 0, sizeof(hmac_misc));
50b97748 MG	156	/* Don't include the inode or generation number in portable
	157	* signatures
	158	*/
	159	if (type != EVM_XATTR_PORTABLE_DIGSIG) {
	160	hmac_misc.ino = inode->i_ino;
	161	hmac_misc.generation = inode->i_generation;
	162	}
19339c25 EB	163	/* The hmac uid and gid must be encoded in the initial user
	164	* namespace (not the filesystems user namespace) as encoding
	165	* them in the filesystems user namespace allows an attack
	166	* where first they are written in an unprivileged fuse mount
	167	* of a filesystem and then the system is tricked to mount the
	168	* filesystem for real on next boot and trust it because
	169	* everything is signed.
	170	*/
	171	hmac_misc.uid = from_kuid(&init_user_ns, inode->i_uid);
	172	hmac_misc.gid = from_kgid(&init_user_ns, inode->i_gid);
66dbc325	173	hmac_misc.mode = inode->i_mode;
2bb930ab	174	crypto_shash_update(desc, (const u8 *)&hmac_misc, sizeof(hmac_misc));
50b97748 MG	175	if ((evm_hmac_attrs & EVM_ATTR_FSUUID) &&
50b97748 MG	176	type != EVM_XATTR_PORTABLE_DIGSIG)
85787090	177	crypto_shash_update(desc, &inode->i_sb->s_uuid.b[0],
74de6684	178	sizeof(inode->i_sb->s_uuid));
d46eb369	179	crypto_shash_final(desc, digest);
66dbc325 MZ	180	}
	181
	182	/*
	183	* Calculate the HMAC value across the set of protected security xattrs.
	184	*
	185	* Instead of retrieving the requested xattr, for performance, calculate
	186	* the hmac using the requested xattr value. Don't alloc/free memory for
	187	* each xattr, but attempt to re-use the previously allocated memory.
	188	*/
15647eb3	189	static int evm_calc_hmac_or_hash(struct dentry *dentry,
5feeb611 MG	190	const char *req_xattr_name,
	191	const char *req_xattr_value,
	192	size_t req_xattr_value_len,
	193	uint8_t type, struct evm_digest *data)
66dbc325	194	{
c6f493d6	195	struct inode *inode = d_backing_inode(dentry);
21af7663	196	struct xattr_list *xattr;
d46eb369	197	struct shash_desc *desc;
66dbc325 MZ	198	size_t xattr_size = 0;
	199	char *xattr_value = NULL;
	200	int error;
	201	int size;
50b97748	202	bool ima_present = false;
66dbc325	203
a3a5c966 SF	204	if (!(inode->i_opflags & IOP_XATTR) \|\|
a3a5c966 SF	205	inode->i_sb->s_user_ns != &init_user_ns)
66dbc325	206	return -EOPNOTSUPP;
5d6c3191	207
5feeb611	208	desc = init_desc(type, data->hdr.algo);
d46eb369 DK	209	if (IS_ERR(desc))
d46eb369 DK	210	return PTR_ERR(desc);
66dbc325	211
5feeb611 MG	212	data->hdr.length = crypto_shash_digestsize(desc->tfm);
5feeb611 MG	213
66dbc325	214	error = -ENODATA;
fa516b66	215	list_for_each_entry_rcu(xattr, &evm_config_xattrnames, list) {
50b97748 MG	216	bool is_ima = false;
50b97748 MG	217
21af7663	218	if (strcmp(xattr->name, XATTR_NAME_IMA) == 0)
50b97748 MG	219	is_ima = true;
50b97748 MG	220
66dbc325	221	if ((req_xattr_name && req_xattr_value)
21af7663	222	&& !strcmp(xattr->name, req_xattr_name)) {
66dbc325	223	error = 0;
d46eb369 DK	224	crypto_shash_update(desc, (const u8 *)req_xattr_value,
d46eb369 DK	225	req_xattr_value_len);
50b97748 MG	226	if (is_ima)
50b97748 MG	227	ima_present = true;
66dbc325 MZ	228	continue;
66dbc325 MZ	229	}
21af7663	230	size = vfs_getxattr_alloc(dentry, xattr->name,
66dbc325 MZ	231	&xattr_value, xattr_size, GFP_NOFS);
	232	if (size == -ENOMEM) {
	233	error = -ENOMEM;
	234	goto out;
	235	}
	236	if (size < 0)
	237	continue;
	238
	239	error = 0;
	240	xattr_size = size;
d46eb369	241	crypto_shash_update(desc, (const u8 *)xattr_value, xattr_size);
50b97748 MG	242	if (is_ima)
50b97748 MG	243	ima_present = true;
66dbc325	244	}
5feeb611	245	hmac_add_misc(desc, inode, type, data->digest);
d46eb369	246
50b97748 MG	247	/* Portable EVM signatures must include an IMA hash */
	248	if (type == EVM_XATTR_PORTABLE_DIGSIG && !ima_present)
	249	return -EPERM;
66dbc325	250	out:
d46eb369 DK	251	kfree(xattr_value);
d46eb369 DK	252	kfree(desc);
66dbc325 MZ	253	return error;
	254	}
	255
15647eb3 DK	256	int evm_calc_hmac(struct dentry dentry, const char req_xattr_name,
15647eb3 DK	257	const char *req_xattr_value, size_t req_xattr_value_len,
5feeb611	258	struct evm_digest *data)
15647eb3 DK	259	{
15647eb3 DK	260	return evm_calc_hmac_or_hash(dentry, req_xattr_name, req_xattr_value,
5feeb611	261	req_xattr_value_len, EVM_XATTR_HMAC, data);
15647eb3 DK	262	}
	263
	264	int evm_calc_hash(struct dentry dentry, const char req_xattr_name,
	265	const char *req_xattr_value, size_t req_xattr_value_len,
5feeb611	266	char type, struct evm_digest *data)
15647eb3 DK	267	{
15647eb3 DK	268	return evm_calc_hmac_or_hash(dentry, req_xattr_name, req_xattr_value,
5feeb611	269	req_xattr_value_len, type, data);
50b97748 MG	270	}
	271
	272	static int evm_is_immutable(struct dentry dentry, struct inode inode)
	273	{
	274	const struct evm_ima_xattr_data *xattr_data = NULL;
	275	struct integrity_iint_cache *iint;
	276	int rc = 0;
	277
	278	iint = integrity_iint_find(inode);
	279	if (iint && (iint->flags & EVM_IMMUTABLE_DIGSIG))
	280	return 1;
	281
	282	/* Do this the hard way */
	283	rc = vfs_getxattr_alloc(dentry, XATTR_NAME_EVM, (char **)&xattr_data, 0,
	284	GFP_NOFS);
	285	if (rc <= 0) {
	286	if (rc == -ENODATA)
	287	return 0;
	288	return rc;
	289	}
	290	if (xattr_data->type == EVM_XATTR_PORTABLE_DIGSIG)
	291	rc = 1;
	292	else
	293	rc = 0;
	294
	295	kfree(xattr_data);
	296	return rc;
15647eb3 DK	297	}
15647eb3 DK	298
50b97748	299
66dbc325 MZ	300	/*
	301	* Calculate the hmac and update security.evm xattr
	302	*
	303	* Expects to be called with i_mutex locked.
	304	*/
	305	int evm_update_evmxattr(struct dentry dentry, const char xattr_name,
	306	const char *xattr_value, size_t xattr_value_len)
	307	{
c6f493d6	308	struct inode *inode = d_backing_inode(dentry);
5feeb611	309	struct evm_digest data;
66dbc325 MZ	310	int rc = 0;
66dbc325 MZ	311
50b97748 MG	312	/*
	313	* Don't permit any transformation of the EVM xattr if the signature
	314	* is of an immutable type
	315	*/
	316	rc = evm_is_immutable(dentry, inode);
	317	if (rc < 0)
	318	return rc;
	319	if (rc)
	320	return -EPERM;
	321
5feeb611	322	data.hdr.algo = HASH_ALGO_SHA1;
66dbc325	323	rc = evm_calc_hmac(dentry, xattr_name, xattr_value,
5feeb611	324	xattr_value_len, &data);
6be5cc52	325	if (rc == 0) {
5feeb611	326	data.hdr.xattr.sha1.type = EVM_XATTR_HMAC;
66dbc325	327	rc = __vfs_setxattr_noperm(dentry, XATTR_NAME_EVM,
5feeb611 MG	328	&data.hdr.xattr.data[1],
5feeb611 MG	329	SHA1_DIGEST_SIZE + 1, 0);
5d6c3191 AG	330	} else if (rc == -ENODATA && (inode->i_opflags & IOP_XATTR)) {
5d6c3191 AG	331	rc = __vfs_removexattr(dentry, XATTR_NAME_EVM);
a67adb99	332	}
66dbc325 MZ	333	return rc;
	334	}
	335
cb723180 MZ	336	int evm_init_hmac(struct inode inode, const struct xattr lsm_xattr,
	337	char *hmac_val)
	338	{
d46eb369	339	struct shash_desc *desc;
cb723180	340
5feeb611	341	desc = init_desc(EVM_XATTR_HMAC, HASH_ALGO_SHA1);
d46eb369	342	if (IS_ERR(desc)) {
20ee451f	343	pr_info("init_desc failed\n");
d46eb369	344	return PTR_ERR(desc);
cb723180 MZ	345	}
cb723180 MZ	346
d46eb369	347	crypto_shash_update(desc, lsm_xattr->value, lsm_xattr->value_len);
50b97748	348	hmac_add_misc(desc, inode, EVM_XATTR_HMAC, hmac_val);
d46eb369	349	kfree(desc);
cb723180 MZ	350	return 0;
	351	}
	352
66dbc325 MZ	353	/*
	354	* Get the key from the TPM for the SHA1-HMAC
	355	*/
	356	int evm_init_key(void)
	357	{
	358	struct key *evm_key;
	359	struct encrypted_key_payload *ekp;
76266763	360	int rc;
66dbc325 MZ	361
	362	evm_key = request_key(&key_type_encrypted, EVMKEY, NULL);
	363	if (IS_ERR(evm_key))
	364	return -ENOENT;
	365
	366	down_read(&evm_key->sem);
146aa8b1	367	ekp = evm_key->payload.data[0];
76266763 DK	368
	369	rc = evm_set_key(ekp->decrypted_data, ekp->decrypted_datalen);
	370
66dbc325 MZ	371	/* burn the original key contents */
	372	memset(ekp->decrypted_data, 0, ekp->decrypted_datalen);
	373	up_read(&evm_key->sem);
	374	key_put(evm_key);
	375	return rc;
	376	}