[mirror_ubuntu-jammy-kernel.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
 */

#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, *tmp_tfm = NULL;
	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)
		goto alloc;
	mutex_lock(&mutex);
	if (*tfm)
		goto unlock;

	tmp_tfm = crypto_alloc_shash(algo, 0, CRYPTO_NOLOAD);
	if (IS_ERR(tmp_tfm)) {
		pr_err("Can not allocate %s (reason: %ld)\n", algo,
		       PTR_ERR(tmp_tfm));
		mutex_unlock(&mutex);
		return ERR_CAST(tmp_tfm);
	}
	if (type == EVM_XATTR_HMAC) {
		rc = crypto_shash_setkey(tmp_tfm, evmkey, evmkey_len);
		if (rc) {
			crypto_free_shash(tmp_tfm);
			mutex_unlock(&mutex);
			return ERR_PTR(rc);
		}
	}
	*tfm = tmp_tfm;
unlock:
	mutex_unlock(&mutex);
alloc:
	desc = kmalloc(sizeof(*desc) + crypto_shash_descsize(*tfm),
			GFP_KERNEL);
	if (!desc) {
		crypto_free_shash(tmp_tfm);
		return ERR_PTR(-ENOMEM);
	}

	desc->tfm = *tfm;

	rc = crypto_shash_init(desc);
	if (rc) {
		crypto_free_shash(tmp_tfm);
		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_lockless(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(&init_user_ns, 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)
		error = -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(&init_user_ns, 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(&init_user_ns, 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(&init_user_ns, 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
876979c9	13	#include <linux/export.h>
66dbc325 MZ	14	#include <linux/crypto.h>
66dbc325 MZ	15	#include <linux/xattr.h>
76266763	16	#include <linux/evm.h>
66dbc325	17	#include <keys/encrypted-type.h>
d46eb369	18	#include <crypto/hash.h>
5feeb611	19	#include <crypto/hash_info.h>
66dbc325 MZ	20	#include "evm.h"
	21
	22	#define EVMKEY "evm-key"
	23	#define MAX_KEY_SIZE 128
	24	static unsigned char evmkey[MAX_KEY_SIZE];
b2724d58	25	static const int evmkey_len = MAX_KEY_SIZE;
66dbc325	26
d46eb369	27	struct crypto_shash *hmac_tfm;
5feeb611	28	static struct crypto_shash *evm_tfm[HASH_ALGO__LAST];
d46eb369	29
97426f98 DK	30	static DEFINE_MUTEX(mutex);
97426f98 DK	31
76266763 DK	32	#define EVM_SET_KEY_BUSY 0
	33
	34	static unsigned long evm_set_key_flags;
	35
b2724d58	36	static const char evm_hmac[] = "hmac(sha1)";
1a82cee3	37
76266763 DK	38	/**
	39	* evm_set_key() - set EVM HMAC key from the kernel
	40	* @key: pointer to a buffer with the key data
	41	* @size: length of the key data
	42	*
	43	* This function allows setting the EVM HMAC key from the kernel
	44	* without using the "encrypted" key subsystem keys. It can be used
	45	* by the crypto HW kernel module which has its own way of managing
	46	* keys.
	47	*
	48	* key length should be between 32 and 128 bytes long
	49	*/
	50	int evm_set_key(void *key, size_t keylen)
	51	{
	52	int rc;
	53
	54	rc = -EBUSY;
	55	if (test_and_set_bit(EVM_SET_KEY_BUSY, &evm_set_key_flags))
	56	goto busy;
	57	rc = -EINVAL;
	58	if (keylen > MAX_KEY_SIZE)
	59	goto inval;
	60	memcpy(evmkey, key, keylen);
	61	evm_initialized \|= EVM_INIT_HMAC;
	62	pr_info("key initialized\n");
	63	return 0;
	64	inval:
	65	clear_bit(EVM_SET_KEY_BUSY, &evm_set_key_flags);
	66	busy:
	67	pr_err("key initialization failed\n");
	68	return rc;
	69	}
	70	EXPORT_SYMBOL_GPL(evm_set_key);
	71
5feeb611	72	static struct shash_desc *init_desc(char type, uint8_t hash_algo)
66dbc325	73	{
143b01d3	74	long rc;
5feeb611	75	const char *algo;
ccf11dba	76	struct crypto_shash *tfm, tmp_tfm = NULL;
d46eb369 DK	77	struct shash_desc *desc;
d46eb369 DK	78
15647eb3	79	if (type == EVM_XATTR_HMAC) {
26ddabfe	80	if (!(evm_initialized & EVM_INIT_HMAC)) {
0485d066	81	pr_err_once("HMAC key is not set\n");
26ddabfe DK	82	return ERR_PTR(-ENOKEY);
26ddabfe DK	83	}
15647eb3 DK	84	tfm = &hmac_tfm;
	85	algo = evm_hmac;
	86	} else {
221be106 RS	87	if (hash_algo >= HASH_ALGO__LAST)
	88	return ERR_PTR(-EINVAL);
	89
5feeb611 MG	90	tfm = &evm_tfm[hash_algo];
5feeb611 MG	91	algo = hash_algo_name[hash_algo];
15647eb3 DK	92	}
15647eb3 DK	93
84338569 DC	94	if (*tfm)
	95	goto alloc;
	96	mutex_lock(&mutex);
	97	if (*tfm)
	98	goto unlock;
	99
	100	tmp_tfm = crypto_alloc_shash(algo, 0, CRYPTO_NOLOAD);
	101	if (IS_ERR(tmp_tfm)) {
	102	pr_err("Can not allocate %s (reason: %ld)\n", algo,
	103	PTR_ERR(tmp_tfm));
	104	mutex_unlock(&mutex);
	105	return ERR_CAST(tmp_tfm);
	106	}
	107	if (type == EVM_XATTR_HMAC) {
	108	rc = crypto_shash_setkey(tmp_tfm, evmkey, evmkey_len);
	109	if (rc) {
	110	crypto_free_shash(tmp_tfm);
97426f98	111	mutex_unlock(&mutex);
d46eb369 DK	112	return ERR_PTR(rc);
d46eb369 DK	113	}
66dbc325	114	}
84338569 DC	115	*tfm = tmp_tfm;
	116	unlock:
	117	mutex_unlock(&mutex);
	118	alloc:
15647eb3	119	desc = kmalloc(sizeof(desc) + crypto_shash_descsize(tfm),
d46eb369	120	GFP_KERNEL);
ccf11dba DL	121	if (!desc) {
ccf11dba DL	122	crypto_free_shash(tmp_tfm);
d46eb369	123	return ERR_PTR(-ENOMEM);
ccf11dba	124	}
d46eb369	125
15647eb3	126	desc->tfm = *tfm;
d46eb369	127
d46eb369	128	rc = crypto_shash_init(desc);
d46eb369	129	if (rc) {
ccf11dba	130	crypto_free_shash(tmp_tfm);
d46eb369 DK	131	kfree(desc);
	132	return ERR_PTR(rc);
	133	}
	134	return desc;
66dbc325 MZ	135	}
	136
	137	/* Protect against 'cutting & pasting' security.evm xattr, include inode
	138	* specific info.
	139	*
	140	* (Additional directory/file metadata needs to be added for more complete
	141	* protection.)
	142	*/
d46eb369	143	static void hmac_add_misc(struct shash_desc desc, struct inode inode,
50b97748	144	char type, char *digest)
66dbc325 MZ	145	{
	146	struct h_misc {
	147	unsigned long ino;
	148	__u32 generation;
	149	uid_t uid;
	150	gid_t gid;
	151	umode_t mode;
	152	} hmac_misc;
66dbc325	153
2bb930ab	154	memset(&hmac_misc, 0, sizeof(hmac_misc));
50b97748 MG	155	/* Don't include the inode or generation number in portable
	156	* signatures
	157	*/
	158	if (type != EVM_XATTR_PORTABLE_DIGSIG) {
	159	hmac_misc.ino = inode->i_ino;
	160	hmac_misc.generation = inode->i_generation;
	161	}
19339c25 EB	162	/* The hmac uid and gid must be encoded in the initial user
	163	* namespace (not the filesystems user namespace) as encoding
	164	* them in the filesystems user namespace allows an attack
	165	* where first they are written in an unprivileged fuse mount
	166	* of a filesystem and then the system is tricked to mount the
	167	* filesystem for real on next boot and trust it because
	168	* everything is signed.
	169	*/
	170	hmac_misc.uid = from_kuid(&init_user_ns, inode->i_uid);
	171	hmac_misc.gid = from_kgid(&init_user_ns, inode->i_gid);
66dbc325	172	hmac_misc.mode = inode->i_mode;
2bb930ab	173	crypto_shash_update(desc, (const u8 *)&hmac_misc, sizeof(hmac_misc));
50b97748 MG	174	if ((evm_hmac_attrs & EVM_ATTR_FSUUID) &&
50b97748 MG	175	type != EVM_XATTR_PORTABLE_DIGSIG)
e7fde070	176	crypto_shash_update(desc, (u8 *)&inode->i_sb->s_uuid, UUID_SIZE);
d46eb369	177	crypto_shash_final(desc, digest);
66dbc325 MZ	178	}
	179
	180	/*
	181	* Calculate the HMAC value across the set of protected security xattrs.
	182	*
	183	* Instead of retrieving the requested xattr, for performance, calculate
	184	* the hmac using the requested xattr value. Don't alloc/free memory for
	185	* each xattr, but attempt to re-use the previously allocated memory.
	186	*/
15647eb3	187	static int evm_calc_hmac_or_hash(struct dentry *dentry,
5feeb611 MG	188	const char *req_xattr_name,
	189	const char *req_xattr_value,
	190	size_t req_xattr_value_len,
	191	uint8_t type, struct evm_digest *data)
66dbc325	192	{
c6f493d6	193	struct inode *inode = d_backing_inode(dentry);
21af7663	194	struct xattr_list *xattr;
d46eb369	195	struct shash_desc *desc;
66dbc325 MZ	196	size_t xattr_size = 0;
	197	char *xattr_value = NULL;
	198	int error;
	199	int size;
50b97748	200	bool ima_present = false;
66dbc325	201
a3a5c966 SF	202	if (!(inode->i_opflags & IOP_XATTR) \|\|
a3a5c966 SF	203	inode->i_sb->s_user_ns != &init_user_ns)
66dbc325	204	return -EOPNOTSUPP;
5d6c3191	205
5feeb611	206	desc = init_desc(type, data->hdr.algo);
d46eb369 DK	207	if (IS_ERR(desc))
d46eb369 DK	208	return PTR_ERR(desc);
66dbc325	209
5feeb611 MG	210	data->hdr.length = crypto_shash_digestsize(desc->tfm);
5feeb611 MG	211
66dbc325	212	error = -ENODATA;
770f6058	213	list_for_each_entry_lockless(xattr, &evm_config_xattrnames, list) {
50b97748 MG	214	bool is_ima = false;
50b97748 MG	215
21af7663	216	if (strcmp(xattr->name, XATTR_NAME_IMA) == 0)
50b97748 MG	217	is_ima = true;
50b97748 MG	218
66dbc325	219	if ((req_xattr_name && req_xattr_value)
21af7663	220	&& !strcmp(xattr->name, req_xattr_name)) {
66dbc325	221	error = 0;
d46eb369 DK	222	crypto_shash_update(desc, (const u8 *)req_xattr_value,
d46eb369 DK	223	req_xattr_value_len);
50b97748 MG	224	if (is_ima)
50b97748 MG	225	ima_present = true;
66dbc325 MZ	226	continue;
66dbc325 MZ	227	}
c7c7a1a1	228	size = vfs_getxattr_alloc(&init_user_ns, dentry, xattr->name,
66dbc325 MZ	229	&xattr_value, xattr_size, GFP_NOFS);
	230	if (size == -ENOMEM) {
	231	error = -ENOMEM;
	232	goto out;
	233	}
	234	if (size < 0)
	235	continue;
	236
	237	error = 0;
	238	xattr_size = size;
d46eb369	239	crypto_shash_update(desc, (const u8 *)xattr_value, xattr_size);
50b97748 MG	240	if (is_ima)
50b97748 MG	241	ima_present = true;
66dbc325	242	}
5feeb611	243	hmac_add_misc(desc, inode, type, data->digest);
d46eb369	244
50b97748 MG	245	/* Portable EVM signatures must include an IMA hash */
50b97748 MG	246	if (type == EVM_XATTR_PORTABLE_DIGSIG && !ima_present)
0c4395fb	247	error = -EPERM;
66dbc325	248	out:
d46eb369 DK	249	kfree(xattr_value);
d46eb369 DK	250	kfree(desc);
66dbc325 MZ	251	return error;
	252	}
	253
15647eb3 DK	254	int evm_calc_hmac(struct dentry dentry, const char req_xattr_name,
15647eb3 DK	255	const char *req_xattr_value, size_t req_xattr_value_len,
5feeb611	256	struct evm_digest *data)
15647eb3 DK	257	{
15647eb3 DK	258	return evm_calc_hmac_or_hash(dentry, req_xattr_name, req_xattr_value,
5feeb611	259	req_xattr_value_len, EVM_XATTR_HMAC, data);
15647eb3 DK	260	}
	261
	262	int evm_calc_hash(struct dentry dentry, const char req_xattr_name,
	263	const char *req_xattr_value, size_t req_xattr_value_len,
5feeb611	264	char type, struct evm_digest *data)
15647eb3 DK	265	{
15647eb3 DK	266	return evm_calc_hmac_or_hash(dentry, req_xattr_name, req_xattr_value,
5feeb611	267	req_xattr_value_len, type, data);
50b97748 MG	268	}
	269
	270	static int evm_is_immutable(struct dentry dentry, struct inode inode)
	271	{
	272	const struct evm_ima_xattr_data *xattr_data = NULL;
	273	struct integrity_iint_cache *iint;
	274	int rc = 0;
	275
	276	iint = integrity_iint_find(inode);
	277	if (iint && (iint->flags & EVM_IMMUTABLE_DIGSIG))
	278	return 1;
	279
	280	/* Do this the hard way */
c7c7a1a1 TA	281	rc = vfs_getxattr_alloc(&init_user_ns, dentry, XATTR_NAME_EVM,
c7c7a1a1 TA	282	(char **)&xattr_data, 0, GFP_NOFS);
50b97748 MG	283	if (rc <= 0) {
	284	if (rc == -ENODATA)
	285	return 0;
	286	return rc;
	287	}
	288	if (xattr_data->type == EVM_XATTR_PORTABLE_DIGSIG)
	289	rc = 1;
	290	else
	291	rc = 0;
	292
	293	kfree(xattr_data);
	294	return rc;
15647eb3 DK	295	}
15647eb3 DK	296
50b97748	297
66dbc325 MZ	298	/*
	299	* Calculate the hmac and update security.evm xattr
	300	*
	301	* Expects to be called with i_mutex locked.
	302	*/
	303	int evm_update_evmxattr(struct dentry dentry, const char xattr_name,
	304	const char *xattr_value, size_t xattr_value_len)
	305	{
c6f493d6	306	struct inode *inode = d_backing_inode(dentry);
5feeb611	307	struct evm_digest data;
66dbc325 MZ	308	int rc = 0;
66dbc325 MZ	309
50b97748 MG	310	/*
	311	* Don't permit any transformation of the EVM xattr if the signature
	312	* is of an immutable type
	313	*/
	314	rc = evm_is_immutable(dentry, inode);
	315	if (rc < 0)
	316	return rc;
	317	if (rc)
	318	return -EPERM;
	319
5feeb611	320	data.hdr.algo = HASH_ALGO_SHA1;
66dbc325	321	rc = evm_calc_hmac(dentry, xattr_name, xattr_value,
5feeb611	322	xattr_value_len, &data);
6be5cc52	323	if (rc == 0) {
5feeb611	324	data.hdr.xattr.sha1.type = EVM_XATTR_HMAC;
c7c7a1a1 TA	325	rc = __vfs_setxattr_noperm(&init_user_ns, dentry,
c7c7a1a1 TA	326	XATTR_NAME_EVM,
5feeb611 MG	327	&data.hdr.xattr.data[1],
5feeb611 MG	328	SHA1_DIGEST_SIZE + 1, 0);
5d6c3191	329	} else if (rc == -ENODATA && (inode->i_opflags & IOP_XATTR)) {
c7c7a1a1	330	rc = __vfs_removexattr(&init_user_ns, dentry, XATTR_NAME_EVM);
a67adb99	331	}
66dbc325 MZ	332	return rc;
	333	}
	334
cb723180 MZ	335	int evm_init_hmac(struct inode inode, const struct xattr lsm_xattr,
	336	char *hmac_val)
	337	{
d46eb369	338	struct shash_desc *desc;
cb723180	339
5feeb611	340	desc = init_desc(EVM_XATTR_HMAC, HASH_ALGO_SHA1);
d46eb369	341	if (IS_ERR(desc)) {
20ee451f	342	pr_info("init_desc failed\n");
d46eb369	343	return PTR_ERR(desc);
cb723180 MZ	344	}
cb723180 MZ	345
d46eb369	346	crypto_shash_update(desc, lsm_xattr->value, lsm_xattr->value_len);
50b97748	347	hmac_add_misc(desc, inode, EVM_XATTR_HMAC, hmac_val);
d46eb369	348	kfree(desc);
cb723180 MZ	349	return 0;
	350	}
	351
66dbc325 MZ	352	/*
	353	* Get the key from the TPM for the SHA1-HMAC
	354	*/
	355	int evm_init_key(void)
	356	{
	357	struct key *evm_key;
	358	struct encrypted_key_payload *ekp;
76266763	359	int rc;
66dbc325	360
028db3e2	361	evm_key = request_key(&key_type_encrypted, EVMKEY, NULL);
66dbc325 MZ	362	if (IS_ERR(evm_key))
	363	return -ENOENT;
	364
	365	down_read(&evm_key->sem);
146aa8b1	366	ekp = evm_key->payload.data[0];
76266763 DK	367
	368	rc = evm_set_key(ekp->decrypted_data, ekp->decrypted_datalen);
	369
66dbc325 MZ	370	/* burn the original key contents */
	371	memset(ekp->decrypted_data, 0, ekp->decrypted_datalen);
	372	up_read(&evm_key->sem);
	373	key_put(evm_key);
	374	return rc;
	375	}