[linux-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) "EVM: "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;

static 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
 * @keylen: 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;
	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)
		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);

	pr_debug("hmac_misc: (%zu) [%*phN]\n", sizeof(struct h_misc),
		 (int)sizeof(struct h_misc), &hmac_misc);
}

/*
 * Dump large security xattr values as a continuous ascii hexadecimal string.
 * (pr_debug is limited to 64 bytes.)
 */
static void dump_security_xattr_l(const char *prefix, const void *src,
				  size_t count)
{
#if defined(DEBUG) || defined(CONFIG_DYNAMIC_DEBUG)
	char *asciihex, *p;

	p = asciihex = kmalloc(count * 2 + 1, GFP_KERNEL);
	if (!asciihex)
		return;

	p = bin2hex(p, src, count);
	*p = 0;
	pr_debug("%s: (%zu) %.*s\n", prefix, count, (int)count * 2, asciihex);
	kfree(asciihex);
#endif
}

static void dump_security_xattr(const char *name, const char *value,
				size_t value_len)
{
	if (value_len < 64)
		pr_debug("%s: (%zu) [%*phN]\n", name, value_len,
			 (int)value_len, value);
	else
		dump_security_xattr_l(name, value, value_len);
}

/*
 * 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 evm_iint_cache *iint)
{
	struct inode *inode = d_inode(d_real(dentry, D_REAL_METADATA));
	struct xattr_list *xattr;
	struct shash_desc *desc;
	size_t xattr_size = 0;
	char *xattr_value = NULL;
	int error;
	int size, user_space_size;
	bool ima_present = false;
	u64 i_version = 0;

	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;

		/*
		 * Skip non-enabled xattrs for locally calculated
		 * signatures/HMACs.
		 */
		if (type != EVM_XATTR_PORTABLE_DIGSIG && !xattr->enabled)
			continue;

		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;

			dump_security_xattr(req_xattr_name,
					    req_xattr_value,
					    req_xattr_value_len);
			continue;
		}
		size = vfs_getxattr_alloc(&nop_mnt_idmap, dentry, xattr->name,
					  &xattr_value, xattr_size, GFP_NOFS);
		if (size == -ENOMEM) {
			error = -ENOMEM;
			goto out;
		}
		if (size < 0)
			continue;

		user_space_size = vfs_getxattr(&nop_mnt_idmap, dentry,
					       xattr->name, NULL, 0);
		if (user_space_size != size)
			pr_debug("file %s: xattr %s size mismatch (kernel: %d, user: %d)\n",
				 dentry->d_name.name, xattr->name, size,
				 user_space_size);
		error = 0;
		xattr_size = size;
		crypto_shash_update(desc, (const u8 *)xattr_value, xattr_size);
		if (is_ima)
			ima_present = true;

		dump_security_xattr(xattr->name, xattr_value, xattr_size);
	}
	hmac_add_misc(desc, inode, type, data->digest);

	if (inode != d_backing_inode(dentry) && iint) {
		if (IS_I_VERSION(inode))
			i_version = inode_query_iversion(inode);
		integrity_inode_attrs_store(&iint->metadata_inode, i_version,
					    inode);
	}

	/* 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, struct evm_iint_cache *iint)
{
	return evm_calc_hmac_or_hash(dentry, req_xattr_name, req_xattr_value,
				    req_xattr_value_len, EVM_XATTR_HMAC, data,
				    iint);
}

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, struct evm_iint_cache *iint)
{
	return evm_calc_hmac_or_hash(dentry, req_xattr_name, req_xattr_value,
				     req_xattr_value_len, type, data, iint);
}

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

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

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

out:
	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_iint_cache *iint = evm_iint_inode(inode);
	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, iint);
	if (rc == 0) {
		data.hdr.xattr.sha1.type = EVM_XATTR_HMAC;
		rc = __vfs_setxattr_noperm(&nop_mnt_idmap, 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(&nop_mnt_idmap, dentry, XATTR_NAME_EVM);
	}
	return rc;
}

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

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

	for (xattr = xattrs; xattr->name; xattr++) {
		if (!evm_protected_xattr(xattr->name))
			continue;

		crypto_shash_update(desc, xattr->value, 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
	1	// SPDX-License-Identifier: GPL-2.0-only
	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	*
	9	* File: evm_crypto.c
	10	* Using root's kernel master key (kmk), calculate the HMAC
	11	*/
	12
	13	#define pr_fmt(fmt) "EVM: "fmt
	14
	15	#include <linux/export.h>
	16	#include <linux/crypto.h>
	17	#include <linux/xattr.h>
	18	#include <linux/evm.h>
	19	#include <keys/encrypted-type.h>
	20	#include <crypto/hash.h>
	21	#include <crypto/hash_info.h>
	22	#include "evm.h"
	23
	24	#define EVMKEY "evm-key"
	25	#define MAX_KEY_SIZE 128
	26	static unsigned char evmkey[MAX_KEY_SIZE];
	27	static const int evmkey_len = MAX_KEY_SIZE;
	28
	29	static struct crypto_shash *hmac_tfm;
	30	static struct crypto_shash *evm_tfm[HASH_ALGO__LAST];
	31
	32	static DEFINE_MUTEX(mutex);
	33
	34	#define EVM_SET_KEY_BUSY 0
	35
	36	static unsigned long evm_set_key_flags;
	37
	38	static const char evm_hmac[] = "hmac(sha1)";
	39
	40	/**
	41	* evm_set_key() - set EVM HMAC key from the kernel
	42	* @key: pointer to a buffer with the key data
	43	* @keylen: 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
	74	static struct shash_desc *init_desc(char type, uint8_t hash_algo)
	75	{
	76	long rc;
	77	const char *algo;
	78	struct crypto_shash *tfm, tmp_tfm;
	79	struct shash_desc *desc;
	80
	81	if (type == EVM_XATTR_HMAC) {
	82	if (!(evm_initialized & EVM_INIT_HMAC)) {
	83	pr_err_once("HMAC key is not set\n");
	84	return ERR_PTR(-ENOKEY);
	85	}
	86	tfm = &hmac_tfm;
	87	algo = evm_hmac;
	88	} else {
	89	if (hash_algo >= HASH_ALGO__LAST)
	90	return ERR_PTR(-EINVAL);
	91
	92	tfm = &evm_tfm[hash_algo];
	93	algo = hash_algo_name[hash_algo];
	94	}
	95
	96	if (*tfm)
	97	goto alloc;
	98	mutex_lock(&mutex);
	99	if (*tfm)
	100	goto unlock;
	101
	102	tmp_tfm = crypto_alloc_shash(algo, 0, CRYPTO_NOLOAD);
	103	if (IS_ERR(tmp_tfm)) {
	104	pr_err("Can not allocate %s (reason: %ld)\n", algo,
	105	PTR_ERR(tmp_tfm));
	106	mutex_unlock(&mutex);
	107	return ERR_CAST(tmp_tfm);
	108	}
	109	if (type == EVM_XATTR_HMAC) {
	110	rc = crypto_shash_setkey(tmp_tfm, evmkey, evmkey_len);
	111	if (rc) {
	112	crypto_free_shash(tmp_tfm);
	113	mutex_unlock(&mutex);
	114	return ERR_PTR(rc);
	115	}
	116	}
	117	*tfm = tmp_tfm;
	118	unlock:
	119	mutex_unlock(&mutex);
	120	alloc:
	121	desc = kmalloc(sizeof(desc) + crypto_shash_descsize(tfm),
	122	GFP_KERNEL);
	123	if (!desc)
	124	return ERR_PTR(-ENOMEM);
	125
	126	desc->tfm = *tfm;
	127
	128	rc = crypto_shash_init(desc);
	129	if (rc) {
	130	kfree(desc);
	131	return ERR_PTR(rc);
	132	}
	133	return desc;
	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	*/
	142	static void hmac_add_misc(struct shash_desc desc, struct inode inode,
	143	char type, char *digest)
	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;
	152
	153	memset(&hmac_misc, 0, sizeof(hmac_misc));
	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	}
	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);
	171	hmac_misc.mode = inode->i_mode;
	172	crypto_shash_update(desc, (const u8 *)&hmac_misc, sizeof(hmac_misc));
	173	if ((evm_hmac_attrs & EVM_ATTR_FSUUID) &&
	174	type != EVM_XATTR_PORTABLE_DIGSIG)
	175	crypto_shash_update(desc, (u8 *)&inode->i_sb->s_uuid, UUID_SIZE);
	176	crypto_shash_final(desc, digest);
	177
	178	pr_debug("hmac_misc: (%zu) [%*phN]\n", sizeof(struct h_misc),
	179	(int)sizeof(struct h_misc), &hmac_misc);
	180	}
	181
	182	/*
	183	* Dump large security xattr values as a continuous ascii hexadecimal string.
	184	* (pr_debug is limited to 64 bytes.)
	185	*/
	186	static void dump_security_xattr_l(const char prefix, const void src,
	187	size_t count)
	188	{
	189	#if defined(DEBUG) \|\| defined(CONFIG_DYNAMIC_DEBUG)
	190	char asciihex, p;
	191
	192	p = asciihex = kmalloc(count * 2 + 1, GFP_KERNEL);
	193	if (!asciihex)
	194	return;
	195
	196	p = bin2hex(p, src, count);
	197	*p = 0;
	198	pr_debug("%s: (%zu) %.s\n", prefix, count, (int)count 2, asciihex);
	199	kfree(asciihex);
	200	#endif
	201	}
	202
	203	static void dump_security_xattr(const char name, const char value,
	204	size_t value_len)
	205	{
	206	if (value_len < 64)
	207	pr_debug("%s: (%zu) [%*phN]\n", name, value_len,
	208	(int)value_len, value);
	209	else
	210	dump_security_xattr_l(name, value, value_len);
	211	}
	212
	213	/*
	214	* Calculate the HMAC value across the set of protected security xattrs.
	215	*
	216	* Instead of retrieving the requested xattr, for performance, calculate
	217	* the hmac using the requested xattr value. Don't alloc/free memory for
	218	* each xattr, but attempt to re-use the previously allocated memory.
	219	*/
	220	static int evm_calc_hmac_or_hash(struct dentry *dentry,
	221	const char *req_xattr_name,
	222	const char *req_xattr_value,
	223	size_t req_xattr_value_len,
	224	uint8_t type, struct evm_digest *data,
	225	struct evm_iint_cache *iint)
	226	{
	227	struct inode *inode = d_inode(d_real(dentry, D_REAL_METADATA));
	228	struct xattr_list *xattr;
	229	struct shash_desc *desc;
	230	size_t xattr_size = 0;
	231	char *xattr_value = NULL;
	232	int error;
	233	int size, user_space_size;
	234	bool ima_present = false;
	235	u64 i_version = 0;
	236
	237	if (!(inode->i_opflags & IOP_XATTR) \|\|
	238	inode->i_sb->s_user_ns != &init_user_ns)
	239	return -EOPNOTSUPP;
	240
	241	desc = init_desc(type, data->hdr.algo);
	242	if (IS_ERR(desc))
	243	return PTR_ERR(desc);
	244
	245	data->hdr.length = crypto_shash_digestsize(desc->tfm);
	246
	247	error = -ENODATA;
	248	list_for_each_entry_lockless(xattr, &evm_config_xattrnames, list) {
	249	bool is_ima = false;
	250
	251	if (strcmp(xattr->name, XATTR_NAME_IMA) == 0)
	252	is_ima = true;
	253
	254	/*
	255	* Skip non-enabled xattrs for locally calculated
	256	* signatures/HMACs.
	257	*/
	258	if (type != EVM_XATTR_PORTABLE_DIGSIG && !xattr->enabled)
	259	continue;
	260
	261	if ((req_xattr_name && req_xattr_value)
	262	&& !strcmp(xattr->name, req_xattr_name)) {
	263	error = 0;
	264	crypto_shash_update(desc, (const u8 *)req_xattr_value,
	265	req_xattr_value_len);
	266	if (is_ima)
	267	ima_present = true;
	268
	269	dump_security_xattr(req_xattr_name,
	270	req_xattr_value,
	271	req_xattr_value_len);
	272	continue;
	273	}
	274	size = vfs_getxattr_alloc(&nop_mnt_idmap, dentry, xattr->name,
	275	&xattr_value, xattr_size, GFP_NOFS);
	276	if (size == -ENOMEM) {
	277	error = -ENOMEM;
	278	goto out;
	279	}
	280	if (size < 0)
	281	continue;
	282
	283	user_space_size = vfs_getxattr(&nop_mnt_idmap, dentry,
	284	xattr->name, NULL, 0);
	285	if (user_space_size != size)
	286	pr_debug("file %s: xattr %s size mismatch (kernel: %d, user: %d)\n",
	287	dentry->d_name.name, xattr->name, size,
	288	user_space_size);
	289	error = 0;
	290	xattr_size = size;
	291	crypto_shash_update(desc, (const u8 *)xattr_value, xattr_size);
	292	if (is_ima)
	293	ima_present = true;
	294
	295	dump_security_xattr(xattr->name, xattr_value, xattr_size);
	296	}
	297	hmac_add_misc(desc, inode, type, data->digest);
	298
	299	if (inode != d_backing_inode(dentry) && iint) {
	300	if (IS_I_VERSION(inode))
	301	i_version = inode_query_iversion(inode);
	302	integrity_inode_attrs_store(&iint->metadata_inode, i_version,
	303	inode);
	304	}
	305
	306	/* Portable EVM signatures must include an IMA hash */
	307	if (type == EVM_XATTR_PORTABLE_DIGSIG && !ima_present)
	308	error = -EPERM;
	309	out:
	310	kfree(xattr_value);
	311	kfree(desc);
	312	return error;
	313	}
	314
	315	int evm_calc_hmac(struct dentry dentry, const char req_xattr_name,
	316	const char *req_xattr_value, size_t req_xattr_value_len,
	317	struct evm_digest data, struct evm_iint_cache iint)
	318	{
	319	return evm_calc_hmac_or_hash(dentry, req_xattr_name, req_xattr_value,
	320	req_xattr_value_len, EVM_XATTR_HMAC, data,
	321	iint);
	322	}
	323
	324	int evm_calc_hash(struct dentry dentry, const char req_xattr_name,
	325	const char *req_xattr_value, size_t req_xattr_value_len,
	326	char type, struct evm_digest data, struct evm_iint_cache iint)
	327	{
	328	return evm_calc_hmac_or_hash(dentry, req_xattr_name, req_xattr_value,
	329	req_xattr_value_len, type, data, iint);
	330	}
	331
	332	static int evm_is_immutable(struct dentry dentry, struct inode inode)
	333	{
	334	const struct evm_ima_xattr_data *xattr_data = NULL;
	335	struct evm_iint_cache *iint;
	336	int rc = 0;
	337
	338	iint = evm_iint_inode(inode);
	339	if (iint && (iint->flags & EVM_IMMUTABLE_DIGSIG))
	340	return 1;
	341
	342	/* Do this the hard way */
	343	rc = vfs_getxattr_alloc(&nop_mnt_idmap, dentry, XATTR_NAME_EVM,
	344	(char **)&xattr_data, 0, GFP_NOFS);
	345	if (rc <= 0) {
	346	if (rc == -ENODATA)
	347	rc = 0;
	348	goto out;
	349	}
	350	if (xattr_data->type == EVM_XATTR_PORTABLE_DIGSIG)
	351	rc = 1;
	352	else
	353	rc = 0;
	354
	355	out:
	356	kfree(xattr_data);
	357	return rc;
	358	}
	359
	360
	361	/*
	362	* Calculate the hmac and update security.evm xattr
	363	*
	364	* Expects to be called with i_mutex locked.
	365	*/
	366	int evm_update_evmxattr(struct dentry dentry, const char xattr_name,
	367	const char *xattr_value, size_t xattr_value_len)
	368	{
	369	struct inode *inode = d_backing_inode(dentry);
	370	struct evm_iint_cache *iint = evm_iint_inode(inode);
	371	struct evm_digest data;
	372	int rc = 0;
	373
	374	/*
	375	* Don't permit any transformation of the EVM xattr if the signature
	376	* is of an immutable type
	377	*/
	378	rc = evm_is_immutable(dentry, inode);
	379	if (rc < 0)
	380	return rc;
	381	if (rc)
	382	return -EPERM;
	383
	384	data.hdr.algo = HASH_ALGO_SHA1;
	385	rc = evm_calc_hmac(dentry, xattr_name, xattr_value,
	386	xattr_value_len, &data, iint);
	387	if (rc == 0) {
	388	data.hdr.xattr.sha1.type = EVM_XATTR_HMAC;
	389	rc = __vfs_setxattr_noperm(&nop_mnt_idmap, dentry,
	390	XATTR_NAME_EVM,
	391	&data.hdr.xattr.data[1],
	392	SHA1_DIGEST_SIZE + 1, 0);
	393	} else if (rc == -ENODATA && (inode->i_opflags & IOP_XATTR)) {
	394	rc = __vfs_removexattr(&nop_mnt_idmap, dentry, XATTR_NAME_EVM);
	395	}
	396	return rc;
	397	}
	398
	399	int evm_init_hmac(struct inode inode, const struct xattr xattrs,
	400	char *hmac_val)
	401	{
	402	struct shash_desc *desc;
	403	const struct xattr *xattr;
	404
	405	desc = init_desc(EVM_XATTR_HMAC, HASH_ALGO_SHA1);
	406	if (IS_ERR(desc)) {
	407	pr_info("init_desc failed\n");
	408	return PTR_ERR(desc);
	409	}
	410
	411	for (xattr = xattrs; xattr->name; xattr++) {
	412	if (!evm_protected_xattr(xattr->name))
	413	continue;
	414
	415	crypto_shash_update(desc, xattr->value, xattr->value_len);
	416	}
	417
	418	hmac_add_misc(desc, inode, EVM_XATTR_HMAC, hmac_val);
	419	kfree(desc);
	420	return 0;
	421	}
	422
	423	/*
	424	* Get the key from the TPM for the SHA1-HMAC
	425	*/
	426	int evm_init_key(void)
	427	{
	428	struct key *evm_key;
	429	struct encrypted_key_payload *ekp;
	430	int rc;
	431
	432	evm_key = request_key(&key_type_encrypted, EVMKEY, NULL);
	433	if (IS_ERR(evm_key))
	434	return -ENOENT;
	435
	436	down_read(&evm_key->sem);
	437	ekp = evm_key->payload.data[0];
	438
	439	rc = evm_set_key(ekp->decrypted_data, ekp->decrypted_datalen);
	440
	441	/* burn the original key contents */
	442	memset(ekp->decrypted_data, 0, ekp->decrypted_datalen);
	443	up_read(&evm_key->sem);
	444	key_put(evm_key);
	445	return rc;
	446	}