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

/*
 * Copyright (C) 2005-2010 IBM Corporation
 *
 * Author:
 * 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_main.c
 *	implements evm_inode_setxattr, evm_inode_post_setxattr,
 *	evm_inode_removexattr, and evm_verifyxattr
 */

#include <linux/module.h>
#include <linux/crypto.h>
#include <linux/xattr.h>
#include <linux/integrity.h>
#include <linux/evm.h>
#include <crypto/hash.h>
#include "evm.h"

int evm_initialized;

char *evm_hmac = "hmac(sha1)";
char *evm_hash = "sha1";

char *evm_config_xattrnames[] = {
#ifdef CONFIG_SECURITY_SELINUX
	XATTR_NAME_SELINUX,
#endif
#ifdef CONFIG_SECURITY_SMACK
	XATTR_NAME_SMACK,
#endif
	XATTR_NAME_CAPS,
	NULL
};

static int evm_fixmode;
static int __init evm_set_fixmode(char *str)
{
	if (strncmp(str, "fix", 3) == 0)
		evm_fixmode = 1;
	return 0;
}
__setup("evm=", evm_set_fixmode);

static int evm_find_protected_xattrs(struct dentry *dentry)
{
	struct inode *inode = dentry->d_inode;
	char **xattr;
	int error;
	int count = 0;

	if (!inode->i_op || !inode->i_op->getxattr)
		return -EOPNOTSUPP;

	for (xattr = evm_config_xattrnames; *xattr != NULL; xattr++) {
		error = inode->i_op->getxattr(dentry, *xattr, NULL, 0);
		if (error < 0) {
			if (error == -ENODATA)
				continue;
			return error;
		}
		count++;
	}

	return count;
}

/*
 * evm_verify_hmac - calculate and compare the HMAC with the EVM xattr
 *
 * Compute the HMAC on the dentry's protected set of extended attributes
 * and compare it against the stored security.evm xattr.
 *
 * For performance:
 * - use the previoulsy retrieved xattr value and length to calculate the
 *   HMAC.)
 * - cache the verification result in the iint, when available.
 *
 * Returns integrity status
 */
static enum integrity_status evm_verify_hmac(struct dentry *dentry,
					     const char *xattr_name,
					     char *xattr_value,
					     size_t xattr_value_len,
					     struct integrity_iint_cache *iint)
{
	struct evm_ima_xattr_data *xattr_data = NULL;
	struct evm_ima_xattr_data calc;
	enum integrity_status evm_status = INTEGRITY_PASS;
	int rc, xattr_len;

	if (iint && iint->evm_status == INTEGRITY_PASS)
		return iint->evm_status;

	/* if status is not PASS, try to check again - against -ENOMEM */

	/* first need to know the sig type */
	rc = vfs_getxattr_alloc(dentry, XATTR_NAME_EVM, (char **)&xattr_data, 0,
				GFP_NOFS);
	if (rc <= 0) {
		if (rc == 0)
			evm_status = INTEGRITY_FAIL; /* empty */
		else if (rc == -ENODATA) {
			rc = evm_find_protected_xattrs(dentry);
			if (rc > 0)
				evm_status = INTEGRITY_NOLABEL;
			else if (rc == 0)
				evm_status = INTEGRITY_NOXATTRS; /* new file */
		}
		goto out;
	}

	xattr_len = rc - 1;

	/* check value type */
	switch (xattr_data->type) {
	case EVM_XATTR_HMAC:
		rc = evm_calc_hmac(dentry, xattr_name, xattr_value,
				   xattr_value_len, calc.digest);
		if (rc)
			break;
		rc = memcmp(xattr_data->digest, calc.digest,
			    sizeof(calc.digest));
		if (rc)
			rc = -EINVAL;
		break;
	case EVM_IMA_XATTR_DIGSIG:
		rc = evm_calc_hash(dentry, xattr_name, xattr_value,
				xattr_value_len, calc.digest);
		if (rc)
			break;
		rc = integrity_digsig_verify(INTEGRITY_KEYRING_EVM,
					xattr_data->digest, xattr_len,
					calc.digest, sizeof(calc.digest));
		if (!rc) {
			/* we probably want to replace rsa with hmac here */
			evm_update_evmxattr(dentry, xattr_name, xattr_value,
				   xattr_value_len);
		}
		break;
	default:
		rc = -EINVAL;
		break;
	}

	if (rc)
		evm_status = (rc == -ENODATA) ?
				INTEGRITY_NOXATTRS : INTEGRITY_FAIL;
out:
	if (iint)
		iint->evm_status = evm_status;
	kfree(xattr_data);
	return evm_status;
}

static int evm_protected_xattr(const char *req_xattr_name)
{
	char **xattrname;
	int namelen;
	int found = 0;

	namelen = strlen(req_xattr_name);
	for (xattrname = evm_config_xattrnames; *xattrname != NULL; xattrname++) {
		if ((strlen(*xattrname) == namelen)
		    && (strncmp(req_xattr_name, *xattrname, namelen) == 0)) {
			found = 1;
			break;
		}
		if (strncmp(req_xattr_name,
			    *xattrname + XATTR_SECURITY_PREFIX_LEN,
			    strlen(req_xattr_name)) == 0) {
			found = 1;
			break;
		}
	}
	return found;
}

/**
 * evm_verifyxattr - verify the integrity of the requested xattr
 * @dentry: object of the verify xattr
 * @xattr_name: requested xattr
 * @xattr_value: requested xattr value
 * @xattr_value_len: requested xattr value length
 *
 * Calculate the HMAC for the given dentry and verify it against the stored
 * security.evm xattr. For performance, use the xattr value and length
 * previously retrieved to calculate the HMAC.
 *
 * Returns the xattr integrity status.
 *
 * This function requires the caller to lock the inode's i_mutex before it
 * is executed.
 */
enum integrity_status evm_verifyxattr(struct dentry *dentry,
				      const char *xattr_name,
				      void *xattr_value, size_t xattr_value_len,
				      struct integrity_iint_cache *iint)
{
	if (!evm_initialized || !evm_protected_xattr(xattr_name))
		return INTEGRITY_UNKNOWN;

	if (!iint) {
		iint = integrity_iint_find(dentry->d_inode);
		if (!iint)
			return INTEGRITY_UNKNOWN;
	}
	return evm_verify_hmac(dentry, xattr_name, xattr_value,
				 xattr_value_len, iint);
}
EXPORT_SYMBOL_GPL(evm_verifyxattr);

/*
 * evm_verify_current_integrity - verify the dentry's metadata integrity
 * @dentry: pointer to the affected dentry
 *
 * Verify and return the dentry's metadata integrity. The exceptions are
 * before EVM is initialized or in 'fix' mode.
 */
static enum integrity_status evm_verify_current_integrity(struct dentry *dentry)
{
	struct inode *inode = dentry->d_inode;

	if (!evm_initialized || !S_ISREG(inode->i_mode) || evm_fixmode)
		return 0;
	return evm_verify_hmac(dentry, NULL, NULL, 0, NULL);
}

/*
 * evm_protect_xattr - protect the EVM extended attribute
 *
 * Prevent security.evm from being modified or removed without the
 * necessary permissions or when the existing value is invalid.
 *
 * The posix xattr acls are 'system' prefixed, which normally would not
 * affect security.evm.  An interesting side affect of writing posix xattr
 * acls is their modifying of the i_mode, which is included in security.evm.
 * For posix xattr acls only, permit security.evm, even if it currently
 * doesn't exist, to be updated.
 */
static int evm_protect_xattr(struct dentry *dentry, const char *xattr_name,
			     const void *xattr_value, size_t xattr_value_len)
{
	enum integrity_status evm_status;

	if (strcmp(xattr_name, XATTR_NAME_EVM) == 0) {
		if (!capable(CAP_SYS_ADMIN))
			return -EPERM;
	} else if (!evm_protected_xattr(xattr_name)) {
		if (!posix_xattr_acl(xattr_name))
			return 0;
		evm_status = evm_verify_current_integrity(dentry);
		if ((evm_status == INTEGRITY_PASS) ||
		    (evm_status == INTEGRITY_NOXATTRS))
			return 0;
		return -EPERM;
	}
	evm_status = evm_verify_current_integrity(dentry);
	return evm_status == INTEGRITY_PASS ? 0 : -EPERM;
}

/**
 * evm_inode_setxattr - protect the EVM extended attribute
 * @dentry: pointer to the affected dentry
 * @xattr_name: pointer to the affected extended attribute name
 * @xattr_value: pointer to the new extended attribute value
 * @xattr_value_len: pointer to the new extended attribute value length
 *
 * Updating 'security.evm' requires CAP_SYS_ADMIN privileges and that
 * the current value is valid.
 */
int evm_inode_setxattr(struct dentry *dentry, const char *xattr_name,
		       const void *xattr_value, size_t xattr_value_len)
{
	return evm_protect_xattr(dentry, xattr_name, xattr_value,
				 xattr_value_len);
}

/**
 * evm_inode_removexattr - protect the EVM extended attribute
 * @dentry: pointer to the affected dentry
 * @xattr_name: pointer to the affected extended attribute name
 *
 * Removing 'security.evm' requires CAP_SYS_ADMIN privileges and that
 * the current value is valid.
 */
int evm_inode_removexattr(struct dentry *dentry, const char *xattr_name)
{
	return evm_protect_xattr(dentry, xattr_name, NULL, 0);
}

/**
 * evm_inode_post_setxattr - update 'security.evm' to reflect the changes
 * @dentry: pointer to the affected dentry
 * @xattr_name: pointer to the affected extended attribute name
 * @xattr_value: pointer to the new extended attribute value
 * @xattr_value_len: pointer to the new extended attribute value length
 *
 * Update the HMAC stored in 'security.evm' to reflect the change.
 *
 * No need to take the i_mutex lock here, as this function is called from
 * __vfs_setxattr_noperm().  The caller of which has taken the inode's
 * i_mutex lock.
 */
void evm_inode_post_setxattr(struct dentry *dentry, const char *xattr_name,
			     const void *xattr_value, size_t xattr_value_len)
{
	if (!evm_initialized || (!evm_protected_xattr(xattr_name)
				 && !posix_xattr_acl(xattr_name)))
		return;

	evm_update_evmxattr(dentry, xattr_name, xattr_value, xattr_value_len);
	return;
}

/**
 * evm_inode_post_removexattr - update 'security.evm' after removing the xattr
 * @dentry: pointer to the affected dentry
 * @xattr_name: pointer to the affected extended attribute name
 *
 * Update the HMAC stored in 'security.evm' to reflect removal of the xattr.
 */
void evm_inode_post_removexattr(struct dentry *dentry, const char *xattr_name)
{
	struct inode *inode = dentry->d_inode;

	if (!evm_initialized || !evm_protected_xattr(xattr_name))
		return;

	mutex_lock(&inode->i_mutex);
	evm_update_evmxattr(dentry, xattr_name, NULL, 0);
	mutex_unlock(&inode->i_mutex);
	return;
}

/**
 * evm_inode_setattr - prevent updating an invalid EVM extended attribute
 * @dentry: pointer to the affected dentry
 */
int evm_inode_setattr(struct dentry *dentry, struct iattr *attr)
{
	unsigned int ia_valid = attr->ia_valid;
	enum integrity_status evm_status;

	if (!(ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID)))
		return 0;
	evm_status = evm_verify_current_integrity(dentry);
	if ((evm_status == INTEGRITY_PASS) ||
	    (evm_status == INTEGRITY_NOXATTRS))
		return 0;
	return -EPERM;
}

/**
 * evm_inode_post_setattr - update 'security.evm' after modifying metadata
 * @dentry: pointer to the affected dentry
 * @ia_valid: for the UID and GID status
 *
 * For now, update the HMAC stored in 'security.evm' to reflect UID/GID
 * changes.
 *
 * This function is called from notify_change(), which expects the caller
 * to lock the inode's i_mutex.
 */
void evm_inode_post_setattr(struct dentry *dentry, int ia_valid)
{
	if (!evm_initialized)
		return;

	if (ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID))
		evm_update_evmxattr(dentry, NULL, NULL, 0);
	return;
}

/*
 * evm_inode_init_security - initializes security.evm
 */
int evm_inode_init_security(struct inode *inode,
				 const struct xattr *lsm_xattr,
				 struct xattr *evm_xattr)
{
	struct evm_ima_xattr_data *xattr_data;
	int rc;

	if (!evm_initialized || !evm_protected_xattr(lsm_xattr->name))
		return 0;

	xattr_data = kzalloc(sizeof(*xattr_data), GFP_NOFS);
	if (!xattr_data)
		return -ENOMEM;

	xattr_data->type = EVM_XATTR_HMAC;
	rc = evm_init_hmac(inode, lsm_xattr, xattr_data->digest);
	if (rc < 0)
		goto out;

	evm_xattr->value = xattr_data;
	evm_xattr->value_len = sizeof(*xattr_data);
	evm_xattr->name = kstrdup(XATTR_EVM_SUFFIX, GFP_NOFS);
	return 0;
out:
	kfree(xattr_data);
	return rc;
}
EXPORT_SYMBOL_GPL(evm_inode_init_security);

static int __init init_evm(void)
{
	int error;

	error = evm_init_secfs();
	if (error < 0) {
		printk(KERN_INFO "EVM: Error registering secfs\n");
		goto err;
	}

	return 0;
err:
	return error;
}

static void __exit cleanup_evm(void)
{
	evm_cleanup_secfs();
	if (hmac_tfm)
		crypto_free_shash(hmac_tfm);
	if (hash_tfm)
		crypto_free_shash(hash_tfm);
}

/*
 * evm_display_config - list the EVM protected security extended attributes
 */
static int __init evm_display_config(void)
{
	char **xattrname;

	for (xattrname = evm_config_xattrnames; *xattrname != NULL; xattrname++)
		printk(KERN_INFO "EVM: %s\n", *xattrname);
	return 0;
}

pure_initcall(evm_display_config);
late_initcall(init_evm);

MODULE_DESCRIPTION("Extended Verification Module");
MODULE_LICENSE("GPL");
Commit	Line	Data
66dbc325 MZ	1	/*
	2	* Copyright (C) 2005-2010 IBM Corporation
	3	*
	4	* Author:
	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_main.c
	13	* implements evm_inode_setxattr, evm_inode_post_setxattr,
	14	* evm_inode_removexattr, and evm_verifyxattr
	15	*/
	16
	17	#include <linux/module.h>
	18	#include <linux/crypto.h>
	19	#include <linux/xattr.h>
	20	#include <linux/integrity.h>
3e1be52d	21	#include <linux/evm.h>
d46eb369	22	#include <crypto/hash.h>
66dbc325 MZ	23	#include "evm.h"
	24
	25	int evm_initialized;
	26
	27	char *evm_hmac = "hmac(sha1)";
15647eb3	28	char *evm_hash = "sha1";
66dbc325 MZ	29
	30	char *evm_config_xattrnames[] = {
	31	#ifdef CONFIG_SECURITY_SELINUX
	32	XATTR_NAME_SELINUX,
	33	#endif
	34	#ifdef CONFIG_SECURITY_SMACK
	35	XATTR_NAME_SMACK,
	36	#endif
	37	XATTR_NAME_CAPS,
	38	NULL
	39	};
	40
7102ebcd MZ	41	static int evm_fixmode;
	42	static int __init evm_set_fixmode(char *str)
	43	{
	44	if (strncmp(str, "fix", 3) == 0)
	45	evm_fixmode = 1;
	46	return 0;
	47	}
	48	__setup("evm=", evm_set_fixmode);
	49
15647eb3 DK	50	static int evm_find_protected_xattrs(struct dentry *dentry)
	51	{
	52	struct inode *inode = dentry->d_inode;
	53	char **xattr;
	54	int error;
	55	int count = 0;
	56
	57	if (!inode->i_op \|\| !inode->i_op->getxattr)
	58	return -EOPNOTSUPP;
	59
	60	for (xattr = evm_config_xattrnames; *xattr != NULL; xattr++) {
	61	error = inode->i_op->getxattr(dentry, *xattr, NULL, 0);
	62	if (error < 0) {
	63	if (error == -ENODATA)
	64	continue;
	65	return error;
	66	}
	67	count++;
	68	}
	69
	70	return count;
	71	}
	72
66dbc325 MZ	73	/*
	74	* evm_verify_hmac - calculate and compare the HMAC with the EVM xattr
	75	*
	76	* Compute the HMAC on the dentry's protected set of extended attributes
7102ebcd MZ	77	* and compare it against the stored security.evm xattr.
	78	*
	79	* For performance:
	80	* - use the previoulsy retrieved xattr value and length to calculate the
	81	* HMAC.)
	82	* - cache the verification result in the iint, when available.
66dbc325 MZ	83	*
	84	* Returns integrity status
	85	*/
	86	static enum integrity_status evm_verify_hmac(struct dentry *dentry,
	87	const char *xattr_name,
	88	char *xattr_value,
	89	size_t xattr_value_len,
	90	struct integrity_iint_cache *iint)
	91	{
15647eb3 DK	92	struct evm_ima_xattr_data *xattr_data = NULL;
15647eb3 DK	93	struct evm_ima_xattr_data calc;
566be59a	94	enum integrity_status evm_status = INTEGRITY_PASS;
15647eb3	95	int rc, xattr_len;
66dbc325	96
7102ebcd	97	if (iint && iint->evm_status == INTEGRITY_PASS)
24e0198e	98	return iint->evm_status;
66dbc325	99
6d38ca01 DK	100	/* if status is not PASS, try to check again - against -ENOMEM */
6d38ca01 DK	101
15647eb3 DK	102	/* first need to know the sig type */
	103	rc = vfs_getxattr_alloc(dentry, XATTR_NAME_EVM, (char **)&xattr_data, 0,
	104	GFP_NOFS);
	105	if (rc <= 0) {
	106	if (rc == 0)
	107	evm_status = INTEGRITY_FAIL; /* empty */
	108	else if (rc == -ENODATA) {
	109	rc = evm_find_protected_xattrs(dentry);
	110	if (rc > 0)
	111	evm_status = INTEGRITY_NOLABEL;
	112	else if (rc == 0)
	113	evm_status = INTEGRITY_NOXATTRS; /* new file */
	114	}
566be59a MZ	115	goto out;
566be59a MZ	116	}
66dbc325	117
15647eb3 DK	118	xattr_len = rc - 1;
	119
	120	/* check value type */
	121	switch (xattr_data->type) {
	122	case EVM_XATTR_HMAC:
	123	rc = evm_calc_hmac(dentry, xattr_name, xattr_value,
	124	xattr_value_len, calc.digest);
	125	if (rc)
	126	break;
	127	rc = memcmp(xattr_data->digest, calc.digest,
	128	sizeof(calc.digest));
	129	if (rc)
	130	rc = -EINVAL;
	131	break;
	132	case EVM_IMA_XATTR_DIGSIG:
	133	rc = evm_calc_hash(dentry, xattr_name, xattr_value,
	134	xattr_value_len, calc.digest);
	135	if (rc)
	136	break;
	137	rc = integrity_digsig_verify(INTEGRITY_KEYRING_EVM,
	138	xattr_data->digest, xattr_len,
	139	calc.digest, sizeof(calc.digest));
	140	if (!rc) {
	141	/* we probably want to replace rsa with hmac here */
	142	evm_update_evmxattr(dentry, xattr_name, xattr_value,
	143	xattr_value_len);
	144	}
	145	break;
	146	default:
	147	rc = -EINVAL;
	148	break;
	149	}
	150
	151	if (rc)
	152	evm_status = (rc == -ENODATA) ?
	153	INTEGRITY_NOXATTRS : INTEGRITY_FAIL;
7102ebcd MZ	154	out:
	155	if (iint)
	156	iint->evm_status = evm_status;
15647eb3	157	kfree(xattr_data);
7102ebcd	158	return evm_status;
66dbc325 MZ	159	}
	160
	161	static int evm_protected_xattr(const char *req_xattr_name)
	162	{
	163	char **xattrname;
	164	int namelen;
	165	int found = 0;
	166
	167	namelen = strlen(req_xattr_name);
	168	for (xattrname = evm_config_xattrnames; *xattrname != NULL; xattrname++) {
	169	if ((strlen(*xattrname) == namelen)
	170	&& (strncmp(req_xattr_name, *xattrname, namelen) == 0)) {
	171	found = 1;
	172	break;
	173	}
cb723180 MZ	174	if (strncmp(req_xattr_name,
	175	*xattrname + XATTR_SECURITY_PREFIX_LEN,
	176	strlen(req_xattr_name)) == 0) {
	177	found = 1;
	178	break;
	179	}
66dbc325 MZ	180	}
	181	return found;
	182	}
	183
	184	/**
	185	* evm_verifyxattr - verify the integrity of the requested xattr
	186	* @dentry: object of the verify xattr
	187	* @xattr_name: requested xattr
	188	* @xattr_value: requested xattr value
	189	* @xattr_value_len: requested xattr value length
	190	*
	191	* Calculate the HMAC for the given dentry and verify it against the stored
	192	* security.evm xattr. For performance, use the xattr value and length
	193	* previously retrieved to calculate the HMAC.
	194	*
	195	* Returns the xattr integrity status.
	196	*
	197	* This function requires the caller to lock the inode's i_mutex before it
	198	* is executed.
	199	*/
	200	enum integrity_status evm_verifyxattr(struct dentry *dentry,
	201	const char *xattr_name,
2960e6cb DK	202	void *xattr_value, size_t xattr_value_len,
2960e6cb DK	203	struct integrity_iint_cache *iint)
66dbc325	204	{
66dbc325 MZ	205	if (!evm_initialized \|\| !evm_protected_xattr(xattr_name))
	206	return INTEGRITY_UNKNOWN;
	207
2960e6cb DK	208	if (!iint) {
	209	iint = integrity_iint_find(dentry->d_inode);
	210	if (!iint)
	211	return INTEGRITY_UNKNOWN;
	212	}
	213	return evm_verify_hmac(dentry, xattr_name, xattr_value,
66dbc325	214	xattr_value_len, iint);
66dbc325 MZ	215	}
	216	EXPORT_SYMBOL_GPL(evm_verifyxattr);
	217
7102ebcd MZ	218	/*
	219	* evm_verify_current_integrity - verify the dentry's metadata integrity
	220	* @dentry: pointer to the affected dentry
	221	*
	222	* Verify and return the dentry's metadata integrity. The exceptions are
	223	* before EVM is initialized or in 'fix' mode.
	224	*/
	225	static enum integrity_status evm_verify_current_integrity(struct dentry *dentry)
	226	{
	227	struct inode *inode = dentry->d_inode;
	228
	229	if (!evm_initialized \|\| !S_ISREG(inode->i_mode) \|\| evm_fixmode)
	230	return 0;
	231	return evm_verify_hmac(dentry, NULL, NULL, 0, NULL);
	232	}
	233
a924ce0b MZ	234	/*
	235	* evm_protect_xattr - protect the EVM extended attribute
	236	*
bf6d0f5d MZ	237	* Prevent security.evm from being modified or removed without the
	238	* necessary permissions or when the existing value is invalid.
	239	*
	240	* The posix xattr acls are 'system' prefixed, which normally would not
	241	* affect security.evm. An interesting side affect of writing posix xattr
	242	* acls is their modifying of the i_mode, which is included in security.evm.
	243	* For posix xattr acls only, permit security.evm, even if it currently
	244	* doesn't exist, to be updated.
a924ce0b MZ	245	*/
	246	static int evm_protect_xattr(struct dentry dentry, const char xattr_name,
	247	const void *xattr_value, size_t xattr_value_len)
	248	{
	249	enum integrity_status evm_status;
	250
	251	if (strcmp(xattr_name, XATTR_NAME_EVM) == 0) {
	252	if (!capable(CAP_SYS_ADMIN))
	253	return -EPERM;
bf6d0f5d MZ	254	} else if (!evm_protected_xattr(xattr_name)) {
	255	if (!posix_xattr_acl(xattr_name))
	256	return 0;
	257	evm_status = evm_verify_current_integrity(dentry);
	258	if ((evm_status == INTEGRITY_PASS) \|\|
566be59a	259	(evm_status == INTEGRITY_NOXATTRS))
bf6d0f5d MZ	260	return 0;
	261	return -EPERM;
	262	}
a924ce0b MZ	263	evm_status = evm_verify_current_integrity(dentry);
	264	return evm_status == INTEGRITY_PASS ? 0 : -EPERM;
	265	}
	266
66dbc325 MZ	267	/**
	268	* evm_inode_setxattr - protect the EVM extended attribute
	269	* @dentry: pointer to the affected dentry
	270	* @xattr_name: pointer to the affected extended attribute name
	271	* @xattr_value: pointer to the new extended attribute value
	272	* @xattr_value_len: pointer to the new extended attribute value length
	273	*
7102ebcd MZ	274	* Updating 'security.evm' requires CAP_SYS_ADMIN privileges and that
7102ebcd MZ	275	* the current value is valid.
66dbc325 MZ	276	*/
	277	int evm_inode_setxattr(struct dentry dentry, const char xattr_name,
	278	const void *xattr_value, size_t xattr_value_len)
	279	{
a924ce0b MZ	280	return evm_protect_xattr(dentry, xattr_name, xattr_value,
a924ce0b MZ	281	xattr_value_len);
66dbc325 MZ	282	}
	283
	284	/**
	285	* evm_inode_removexattr - protect the EVM extended attribute
	286	* @dentry: pointer to the affected dentry
	287	* @xattr_name: pointer to the affected extended attribute name
	288	*
7102ebcd MZ	289	* Removing 'security.evm' requires CAP_SYS_ADMIN privileges and that
7102ebcd MZ	290	* the current value is valid.
66dbc325 MZ	291	*/
	292	int evm_inode_removexattr(struct dentry dentry, const char xattr_name)
	293	{
a924ce0b	294	return evm_protect_xattr(dentry, xattr_name, NULL, 0);
66dbc325 MZ	295	}
	296
	297	/**
	298	* evm_inode_post_setxattr - update 'security.evm' to reflect the changes
	299	* @dentry: pointer to the affected dentry
	300	* @xattr_name: pointer to the affected extended attribute name
	301	* @xattr_value: pointer to the new extended attribute value
	302	* @xattr_value_len: pointer to the new extended attribute value length
	303	*
	304	* Update the HMAC stored in 'security.evm' to reflect the change.
	305	*
	306	* No need to take the i_mutex lock here, as this function is called from
	307	* __vfs_setxattr_noperm(). The caller of which has taken the inode's
	308	* i_mutex lock.
	309	*/
	310	void evm_inode_post_setxattr(struct dentry dentry, const char xattr_name,
	311	const void *xattr_value, size_t xattr_value_len)
	312	{
bf6d0f5d MZ	313	if (!evm_initialized \|\| (!evm_protected_xattr(xattr_name)
bf6d0f5d MZ	314	&& !posix_xattr_acl(xattr_name)))
66dbc325 MZ	315	return;
	316
	317	evm_update_evmxattr(dentry, xattr_name, xattr_value, xattr_value_len);
	318	return;
	319	}
	320
	321	/**
	322	* evm_inode_post_removexattr - update 'security.evm' after removing the xattr
	323	* @dentry: pointer to the affected dentry
	324	* @xattr_name: pointer to the affected extended attribute name
	325	*
	326	* Update the HMAC stored in 'security.evm' to reflect removal of the xattr.
	327	*/
	328	void evm_inode_post_removexattr(struct dentry dentry, const char xattr_name)
	329	{
	330	struct inode *inode = dentry->d_inode;
	331
	332	if (!evm_initialized \|\| !evm_protected_xattr(xattr_name))
	333	return;
	334
	335	mutex_lock(&inode->i_mutex);
	336	evm_update_evmxattr(dentry, xattr_name, NULL, 0);
	337	mutex_unlock(&inode->i_mutex);
	338	return;
	339	}
	340
817b54aa MZ	341	/**
	342	* evm_inode_setattr - prevent updating an invalid EVM extended attribute
	343	* @dentry: pointer to the affected dentry
	344	*/
	345	int evm_inode_setattr(struct dentry dentry, struct iattr attr)
	346	{
	347	unsigned int ia_valid = attr->ia_valid;
	348	enum integrity_status evm_status;
	349
a924ce0b	350	if (!(ia_valid & (ATTR_MODE \| ATTR_UID \| ATTR_GID)))
817b54aa MZ	351	return 0;
817b54aa MZ	352	evm_status = evm_verify_current_integrity(dentry);
566be59a MZ	353	if ((evm_status == INTEGRITY_PASS) \|\|
	354	(evm_status == INTEGRITY_NOXATTRS))
	355	return 0;
	356	return -EPERM;
817b54aa MZ	357	}
817b54aa MZ	358
66dbc325 MZ	359	/**
	360	* evm_inode_post_setattr - update 'security.evm' after modifying metadata
	361	* @dentry: pointer to the affected dentry
	362	* @ia_valid: for the UID and GID status
	363	*
	364	* For now, update the HMAC stored in 'security.evm' to reflect UID/GID
	365	* changes.
	366	*
	367	* This function is called from notify_change(), which expects the caller
	368	* to lock the inode's i_mutex.
	369	*/
	370	void evm_inode_post_setattr(struct dentry *dentry, int ia_valid)
	371	{
	372	if (!evm_initialized)
	373	return;
	374
	375	if (ia_valid & (ATTR_MODE \| ATTR_UID \| ATTR_GID))
	376	evm_update_evmxattr(dentry, NULL, NULL, 0);
	377	return;
	378	}
	379
cb723180 MZ	380	/*
	381	* evm_inode_init_security - initializes security.evm
	382	*/
	383	int evm_inode_init_security(struct inode *inode,
	384	const struct xattr *lsm_xattr,
	385	struct xattr *evm_xattr)
	386	{
	387	struct evm_ima_xattr_data *xattr_data;
	388	int rc;
	389
	390	if (!evm_initialized \|\| !evm_protected_xattr(lsm_xattr->name))
5a4730ba	391	return 0;
cb723180 MZ	392
	393	xattr_data = kzalloc(sizeof(*xattr_data), GFP_NOFS);
	394	if (!xattr_data)
	395	return -ENOMEM;
	396
	397	xattr_data->type = EVM_XATTR_HMAC;
	398	rc = evm_init_hmac(inode, lsm_xattr, xattr_data->digest);
	399	if (rc < 0)
	400	goto out;
	401
	402	evm_xattr->value = xattr_data;
	403	evm_xattr->value_len = sizeof(*xattr_data);
	404	evm_xattr->name = kstrdup(XATTR_EVM_SUFFIX, GFP_NOFS);
	405	return 0;
	406	out:
	407	kfree(xattr_data);
	408	return rc;
	409	}
	410	EXPORT_SYMBOL_GPL(evm_inode_init_security);
	411
66dbc325 MZ	412	static int __init init_evm(void)
	413	{
	414	int error;
	415
66dbc325 MZ	416	error = evm_init_secfs();
	417	if (error < 0) {
	418	printk(KERN_INFO "EVM: Error registering secfs\n");
	419	goto err;
	420	}
15647eb3 DK	421
15647eb3 DK	422	return 0;
66dbc325 MZ	423	err:
	424	return error;
	425	}
	426
	427	static void __exit cleanup_evm(void)
	428	{
	429	evm_cleanup_secfs();
d46eb369 DK	430	if (hmac_tfm)
d46eb369 DK	431	crypto_free_shash(hmac_tfm);
15647eb3 DK	432	if (hash_tfm)
15647eb3 DK	433	crypto_free_shash(hash_tfm);
66dbc325 MZ	434	}
	435
	436	/*
	437	* evm_display_config - list the EVM protected security extended attributes
	438	*/
	439	static int __init evm_display_config(void)
	440	{
	441	char **xattrname;
	442
	443	for (xattrname = evm_config_xattrnames; *xattrname != NULL; xattrname++)
	444	printk(KERN_INFO "EVM: %s\n", *xattrname);
	445	return 0;
	446	}
	447
	448	pure_initcall(evm_display_config);
	449	late_initcall(init_evm);
	450
	451	MODULE_DESCRIPTION("Extended Verification Module");
	452	MODULE_LICENSE("GPL");