[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
 * @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;
	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 hexademical string.
 * (pr_debug is limited to 64 bytes.)
 */
static void dump_security_xattr(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
}

/*
 * 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, user_space_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;

		/*
		 * 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;

			if (req_xattr_value_len < 64)
				pr_debug("%s: (%zu) [%*phN]\n", req_xattr_name,
					 req_xattr_value_len,
					 (int)req_xattr_value_len,
					 req_xattr_value);
			else
				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;

		if (xattr_size < 64)
			pr_debug("%s: (%zu) [%*phN]", xattr->name, xattr_size,
				 (int)xattr_size, xattr_value);
		else
			dump_security_xattr(xattr->name, xattr_value,
					    xattr_size);
	}
	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(&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_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
87ac3d00 MZ	13	#define pr_fmt(fmt) "EVM: "fmt
87ac3d00 MZ	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
4c41186f	29	static 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;
51dd64bb	78	struct crypto_shash *tfm, tmp_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	}
15647eb3 DK	95
84338569 DC	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);
97426f98	113	mutex_unlock(&mutex);
d46eb369 DK	114	return ERR_PTR(rc);
d46eb369 DK	115	}
66dbc325	116	}
84338569 DC	117	*tfm = tmp_tfm;
	118	unlock:
	119	mutex_unlock(&mutex);
	120	alloc:
15647eb3	121	desc = kmalloc(sizeof(desc) + crypto_shash_descsize(tfm),
d46eb369	122	GFP_KERNEL);
51dd64bb	123	if (!desc)
d46eb369 DK	124	return ERR_PTR(-ENOMEM);
d46eb369 DK	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);
87ac3d00 MZ	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 hexademical string.
	184	* (pr_debug is limited to 64 bytes.)
	185	*/
	186	static void dump_security_xattr(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
66dbc325 MZ	201	}
	202
	203	/*
	204	* Calculate the HMAC value across the set of protected security xattrs.
	205	*
	206	* Instead of retrieving the requested xattr, for performance, calculate
	207	* the hmac using the requested xattr value. Don't alloc/free memory for
	208	* each xattr, but attempt to re-use the previously allocated memory.
	209	*/
15647eb3	210	static int evm_calc_hmac_or_hash(struct dentry *dentry,
5feeb611 MG	211	const char *req_xattr_name,
	212	const char *req_xattr_value,
	213	size_t req_xattr_value_len,
	214	uint8_t type, struct evm_digest *data)
66dbc325	215	{
c6f493d6	216	struct inode *inode = d_backing_inode(dentry);
21af7663	217	struct xattr_list *xattr;
d46eb369	218	struct shash_desc *desc;
66dbc325 MZ	219	size_t xattr_size = 0;
	220	char *xattr_value = NULL;
	221	int error;
907a399d	222	int size, user_space_size;
50b97748	223	bool ima_present = false;
66dbc325	224
a3a5c966 SF	225	if (!(inode->i_opflags & IOP_XATTR) \|\|
a3a5c966 SF	226	inode->i_sb->s_user_ns != &init_user_ns)
66dbc325	227	return -EOPNOTSUPP;
5d6c3191	228
5feeb611	229	desc = init_desc(type, data->hdr.algo);
d46eb369 DK	230	if (IS_ERR(desc))
d46eb369 DK	231	return PTR_ERR(desc);
66dbc325	232
5feeb611 MG	233	data->hdr.length = crypto_shash_digestsize(desc->tfm);
5feeb611 MG	234
66dbc325	235	error = -ENODATA;
770f6058	236	list_for_each_entry_lockless(xattr, &evm_config_xattrnames, list) {
50b97748 MG	237	bool is_ima = false;
50b97748 MG	238
21af7663	239	if (strcmp(xattr->name, XATTR_NAME_IMA) == 0)
50b97748 MG	240	is_ima = true;
50b97748 MG	241
8c7a703e RS	242	/*
	243	* Skip non-enabled xattrs for locally calculated
	244	* signatures/HMACs.
	245	*/
	246	if (type != EVM_XATTR_PORTABLE_DIGSIG && !xattr->enabled)
	247	continue;
	248
66dbc325	249	if ((req_xattr_name && req_xattr_value)
21af7663	250	&& !strcmp(xattr->name, req_xattr_name)) {
66dbc325	251	error = 0;
d46eb369 DK	252	crypto_shash_update(desc, (const u8 *)req_xattr_value,
d46eb369 DK	253	req_xattr_value_len);
50b97748 MG	254	if (is_ima)
50b97748 MG	255	ima_present = true;
87ac3d00 MZ	256
	257	if (req_xattr_value_len < 64)
	258	pr_debug("%s: (%zu) [%*phN]\n", req_xattr_name,
	259	req_xattr_value_len,
	260	(int)req_xattr_value_len,
	261	req_xattr_value);
	262	else
	263	dump_security_xattr(req_xattr_name,
	264	req_xattr_value,
	265	req_xattr_value_len);
66dbc325 MZ	266	continue;
66dbc325 MZ	267	}
4609e1f1	268	size = vfs_getxattr_alloc(&nop_mnt_idmap, dentry, xattr->name,
66dbc325 MZ	269	&xattr_value, xattr_size, GFP_NOFS);
	270	if (size == -ENOMEM) {
	271	error = -ENOMEM;
	272	goto out;
	273	}
	274	if (size < 0)
	275	continue;
	276
4609e1f1	277	user_space_size = vfs_getxattr(&nop_mnt_idmap, dentry,
907a399d RS	278	xattr->name, NULL, 0);
	279	if (user_space_size != size)
	280	pr_debug("file %s: xattr %s size mismatch (kernel: %d, user: %d)\n",
	281	dentry->d_name.name, xattr->name, size,
	282	user_space_size);
66dbc325 MZ	283	error = 0;
66dbc325 MZ	284	xattr_size = size;
d46eb369	285	crypto_shash_update(desc, (const u8 *)xattr_value, xattr_size);
50b97748 MG	286	if (is_ima)
50b97748 MG	287	ima_present = true;
87ac3d00 MZ	288
	289	if (xattr_size < 64)
	290	pr_debug("%s: (%zu) [%*phN]", xattr->name, xattr_size,
	291	(int)xattr_size, xattr_value);
	292	else
	293	dump_security_xattr(xattr->name, xattr_value,
	294	xattr_size);
66dbc325	295	}
5feeb611	296	hmac_add_misc(desc, inode, type, data->digest);
d46eb369	297
50b97748 MG	298	/* Portable EVM signatures must include an IMA hash */
50b97748 MG	299	if (type == EVM_XATTR_PORTABLE_DIGSIG && !ima_present)
0c4395fb	300	error = -EPERM;
66dbc325	301	out:
d46eb369 DK	302	kfree(xattr_value);
d46eb369 DK	303	kfree(desc);
66dbc325 MZ	304	return error;
	305	}
	306
15647eb3 DK	307	int evm_calc_hmac(struct dentry dentry, const char req_xattr_name,
15647eb3 DK	308	const char *req_xattr_value, size_t req_xattr_value_len,
5feeb611	309	struct evm_digest *data)
15647eb3 DK	310	{
15647eb3 DK	311	return evm_calc_hmac_or_hash(dentry, req_xattr_name, req_xattr_value,
5feeb611	312	req_xattr_value_len, EVM_XATTR_HMAC, data);
15647eb3 DK	313	}
	314
	315	int evm_calc_hash(struct dentry dentry, const char req_xattr_name,
	316	const char *req_xattr_value, size_t req_xattr_value_len,
5feeb611	317	char type, struct evm_digest *data)
15647eb3 DK	318	{
15647eb3 DK	319	return evm_calc_hmac_or_hash(dentry, req_xattr_name, req_xattr_value,
5feeb611	320	req_xattr_value_len, type, data);
50b97748 MG	321	}
	322
	323	static int evm_is_immutable(struct dentry dentry, struct inode inode)
	324	{
	325	const struct evm_ima_xattr_data *xattr_data = NULL;
	326	struct integrity_iint_cache *iint;
	327	int rc = 0;
	328
	329	iint = integrity_iint_find(inode);
	330	if (iint && (iint->flags & EVM_IMMUTABLE_DIGSIG))
	331	return 1;
	332
	333	/* Do this the hard way */
4609e1f1	334	rc = vfs_getxattr_alloc(&nop_mnt_idmap, dentry, XATTR_NAME_EVM,
c7c7a1a1	335	(char **)&xattr_data, 0, GFP_NOFS);
50b97748 MG	336	if (rc <= 0) {
50b97748 MG	337	if (rc == -ENODATA)
f6fbd8cb PM	338	rc = 0;
f6fbd8cb PM	339	goto out;
50b97748 MG	340	}
	341	if (xattr_data->type == EVM_XATTR_PORTABLE_DIGSIG)
	342	rc = 1;
	343	else
	344	rc = 0;
	345
f6fbd8cb	346	out:
50b97748 MG	347	kfree(xattr_data);
50b97748 MG	348	return rc;
15647eb3 DK	349	}
15647eb3 DK	350
50b97748	351
66dbc325 MZ	352	/*
	353	* Calculate the hmac and update security.evm xattr
	354	*
	355	* Expects to be called with i_mutex locked.
	356	*/
	357	int evm_update_evmxattr(struct dentry dentry, const char xattr_name,
	358	const char *xattr_value, size_t xattr_value_len)
	359	{
c6f493d6	360	struct inode *inode = d_backing_inode(dentry);
5feeb611	361	struct evm_digest data;
66dbc325 MZ	362	int rc = 0;
66dbc325 MZ	363
50b97748 MG	364	/*
	365	* Don't permit any transformation of the EVM xattr if the signature
	366	* is of an immutable type
	367	*/
	368	rc = evm_is_immutable(dentry, inode);
	369	if (rc < 0)
	370	return rc;
	371	if (rc)
	372	return -EPERM;
	373
5feeb611	374	data.hdr.algo = HASH_ALGO_SHA1;
66dbc325	375	rc = evm_calc_hmac(dentry, xattr_name, xattr_value,
5feeb611	376	xattr_value_len, &data);
6be5cc52	377	if (rc == 0) {
5feeb611	378	data.hdr.xattr.sha1.type = EVM_XATTR_HMAC;
c7c7a1a1 TA	379	rc = __vfs_setxattr_noperm(&init_user_ns, dentry,
c7c7a1a1 TA	380	XATTR_NAME_EVM,
5feeb611 MG	381	&data.hdr.xattr.data[1],
5feeb611 MG	382	SHA1_DIGEST_SIZE + 1, 0);
5d6c3191	383	} else if (rc == -ENODATA && (inode->i_opflags & IOP_XATTR)) {
c7c7a1a1	384	rc = __vfs_removexattr(&init_user_ns, dentry, XATTR_NAME_EVM);
a67adb99	385	}
66dbc325 MZ	386	return rc;
	387	}
	388
cb723180 MZ	389	int evm_init_hmac(struct inode inode, const struct xattr lsm_xattr,
	390	char *hmac_val)
	391	{
d46eb369	392	struct shash_desc *desc;
cb723180	393
5feeb611	394	desc = init_desc(EVM_XATTR_HMAC, HASH_ALGO_SHA1);
d46eb369	395	if (IS_ERR(desc)) {
20ee451f	396	pr_info("init_desc failed\n");
d46eb369	397	return PTR_ERR(desc);
cb723180 MZ	398	}
cb723180 MZ	399
d46eb369	400	crypto_shash_update(desc, lsm_xattr->value, lsm_xattr->value_len);
50b97748	401	hmac_add_misc(desc, inode, EVM_XATTR_HMAC, hmac_val);
d46eb369	402	kfree(desc);
cb723180 MZ	403	return 0;
	404	}
	405
66dbc325 MZ	406	/*
	407	* Get the key from the TPM for the SHA1-HMAC
	408	*/
	409	int evm_init_key(void)
	410	{
	411	struct key *evm_key;
	412	struct encrypted_key_payload *ekp;
76266763	413	int rc;
66dbc325	414
028db3e2	415	evm_key = request_key(&key_type_encrypted, EVMKEY, NULL);
66dbc325 MZ	416	if (IS_ERR(evm_key))
	417	return -ENOENT;
	418
	419	down_read(&evm_key->sem);
146aa8b1	420	ekp = evm_key->payload.data[0];
76266763 DK	421
	422	rc = evm_set_key(ekp->decrypted_data, ekp->decrypted_datalen);
	423
66dbc325 MZ	424	/* burn the original key contents */
	425	memset(ekp->decrypted_data, 0, ekp->decrypted_datalen);
	426	up_read(&evm_key->sem);
	427	key_put(evm_key);
	428	return rc;
	429	}