security/smack/smack_access.c - kernel/msm-4.9 - Gitiles

 /*
  * Copyright (C) 2007 Casey Schaufler <casey@schaufler-ca.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.
  *
  * Author:
  *      Casey Schaufler <casey@schaufler-ca.com>
  *
  */

 #include <linux/types.h>
 #include <linux/slab.h>
 #include <linux/fs.h>
 #include <linux/sched.h>
 #include "smack.h"

 struct smack_known smack_known_huh = {
 	.smk_known	= "?",
 	.smk_secid	= 2,
 };

 struct smack_known smack_known_hat = {
 	.smk_known	= "^",
 	.smk_secid	= 3,
 };

 struct smack_known smack_known_star = {
 	.smk_known	= "*",
 	.smk_secid	= 4,
 };

 struct smack_known smack_known_floor = {
 	.smk_known	= "_",
 	.smk_secid	= 5,
 };

 struct smack_known smack_known_invalid = {
 	.smk_known	= "",
 	.smk_secid	= 6,
 };

 struct smack_known smack_known_web = {
 	.smk_known	= "@",
 	.smk_secid	= 7,
 };

 LIST_HEAD(smack_known_list);

 /*
  * The initial value needs to be bigger than any of the
  * known values above.
  */
 static u32 smack_next_secid = 10;

 /*
  * what events do we log
  * can be overwritten at run-time by /smack/logging
  */
 int log_policy = SMACK_AUDIT_DENIED;

 /**
  * smk_access_entry - look up matching access rule
  * @subject_label: a pointer to the subject's Smack label
  * @object_label: a pointer to the object's Smack label
  * @rule_list: the list of rules to search
  *
  * This function looks up the subject/object pair in the
  * access rule list and returns the access mode. If no
  * entry is found returns -ENOENT.
  *
  * NOTE:
  *
  * Earlier versions of this function allowed for labels that
  * were not on the label list. This was done to allow for
  * labels to come over the network that had never been seen
  * before on this host. Unless the receiving socket has the
  * star label this will always result in a failure check. The
  * star labeled socket case is now handled in the networking
  * hooks so there is no case where the label is not on the
  * label list. Checking to see if the address of two labels
  * is the same is now a reliable test.
  *
  * Do the object check first because that is more
  * likely to differ.
  *
  * Allowing write access implies allowing locking.
  */
 int smk_access_entry(char *subject_label, char *object_label,
 			struct list_head *rule_list)
 {
 	int may = -ENOENT;
 	struct smack_rule *srp;

 	list_for_each_entry_rcu(srp, rule_list, list) {
 		if (srp->smk_object->smk_known == object_label &&
 		    srp->smk_subject->smk_known == subject_label) {
 			may = srp->smk_access;
 			break;
 		}
 	}

 	/*
 	 * MAY_WRITE implies MAY_LOCK.
 	 */
 	if ((may & MAY_WRITE) == MAY_WRITE)
 		may |= MAY_LOCK;
 	return may;
 }

 /**
  * smk_access - determine if a subject has a specific access to an object
  * @subject: a pointer to the subject's Smack label entry
  * @object: a pointer to the object's Smack label entry
  * @request: the access requested, in "MAY" format
  * @a : a pointer to the audit data
  *
  * This function looks up the subject/object pair in the
  * access rule list and returns 0 if the access is permitted,
  * non zero otherwise.
  *
  * Smack labels are shared on smack_list
  */
 int smk_access(struct smack_known *subject, struct smack_known *object,
 	       int request, struct smk_audit_info *a)
 {
 	int may = MAY_NOT;
 	int rc = 0;

 	/*
 	 * Hardcoded comparisons.
 	 */
 	/*
 	 * A star subject can't access any object.
 	 */
 	if (subject == &smack_known_star) {
 		rc = -EACCES;
 		goto out_audit;
 	}
 	/*
 	 * An internet object can be accessed by any subject.
 	 * Tasks cannot be assigned the internet label.
 	 * An internet subject can access any object.
 	 */
 	if (object == &smack_known_web || subject == &smack_known_web)
 		goto out_audit;
 	/*
 	 * A star object can be accessed by any subject.
 	 */
 	if (object == &smack_known_star)
 		goto out_audit;
 	/*
 	 * An object can be accessed in any way by a subject
 	 * with the same label.
 	 */
 	if (subject->smk_known == object->smk_known)
 		goto out_audit;
 	/*
 	 * A hat subject can read or lock any object.
 	 * A floor object can be read or locked by any subject.
 	 */
 	if ((request & MAY_ANYREAD) == request ||
 	    (request & MAY_LOCK) == request) {
 		if (object == &smack_known_floor)
 			goto out_audit;
 		if (subject == &smack_known_hat)
 			goto out_audit;
 	}
 	/*
 	 * Beyond here an explicit relationship is required.
 	 * If the requested access is contained in the available
 	 * access (e.g. read is included in readwrite) it's
 	 * good. A negative response from smk_access_entry()
 	 * indicates there is no entry for this pair.
 	 */
 	rcu_read_lock();
 	may = smk_access_entry(subject->smk_known, object->smk_known,
 			       &subject->smk_rules);
 	rcu_read_unlock();

 	if (may <= 0 || (request & may) != request) {
 		rc = -EACCES;
 		goto out_audit;
 	}
 #ifdef CONFIG_SECURITY_SMACK_BRINGUP
 	/*
 	 * Return a positive value if using bringup mode.
 	 * This allows the hooks to identify checks that
 	 * succeed because of "b" rules.
 	 */
 	if (may & MAY_BRINGUP)
 		rc = SMACK_BRINGUP_ALLOW;
 #endif

 out_audit:

 #ifdef CONFIG_SECURITY_SMACK_BRINGUP
 	if (rc < 0) {
 		if (object == smack_unconfined)
 			rc = SMACK_UNCONFINED_OBJECT;
 		if (subject == smack_unconfined)
 			rc = SMACK_UNCONFINED_SUBJECT;
 	}
 #endif

 #ifdef CONFIG_AUDIT
 	if (a)
 		smack_log(subject->smk_known, object->smk_known,
 			  request, rc, a);
 #endif

 	return rc;
 }

 /**
  * smk_tskacc - determine if a task has a specific access to an object
  * @tsp: a pointer to the subject's task
  * @obj_known: a pointer to the object's label entry
  * @mode: the access requested, in "MAY" format
  * @a : common audit data
  *
  * This function checks the subject task's label/object label pair
  * in the access rule list and returns 0 if the access is permitted,
  * non zero otherwise. It allows that the task may have the capability
  * to override the rules.
  */
 int smk_tskacc(struct task_smack *tsp, struct smack_known *obj_known,
 	       u32 mode, struct smk_audit_info *a)
 {
 	struct smack_known *sbj_known = smk_of_task(tsp);
 	int may;
 	int rc;

 	/*
 	 * Check the global rule list
 	 */
 	rc = smk_access(sbj_known, obj_known, mode, NULL);
 	if (rc >= 0) {
 		/*
 		 * If there is an entry in the task's rule list
 		 * it can further restrict access.
 		 */
 		may = smk_access_entry(sbj_known->smk_known,
 				       obj_known->smk_known,
 				       &tsp->smk_rules);
 		if (may < 0)
 			goto out_audit;
 		if ((mode & may) == mode)
 			goto out_audit;
 		rc = -EACCES;
 	}

 	/*
 	 * Allow for priviliged to override policy.
 	 */
 	if (rc != 0 && smack_privileged(CAP_MAC_OVERRIDE))
 		rc = 0;

 out_audit:
 #ifdef CONFIG_AUDIT
 	if (a)
 		smack_log(sbj_known->smk_known, obj_known->smk_known,
 			  mode, rc, a);
 #endif
 	return rc;
 }

 /**
  * smk_curacc - determine if current has a specific access to an object
  * @obj_known: a pointer to the object's Smack label entry
  * @mode: the access requested, in "MAY" format
  * @a : common audit data
  *
  * This function checks the current subject label/object label pair
  * in the access rule list and returns 0 if the access is permitted,
  * non zero otherwise. It allows that current may have the capability
  * to override the rules.
  */
 int smk_curacc(struct smack_known *obj_known,
 	       u32 mode, struct smk_audit_info *a)
 {
 	struct task_smack *tsp = current_security();

 	return smk_tskacc(tsp, obj_known, mode, a);
 }

 #ifdef CONFIG_AUDIT
 /**
  * smack_str_from_perm : helper to transalate an int to a
  * readable string
  * @string : the string to fill
  * @access : the int
  *
  */
 static inline void smack_str_from_perm(char *string, int access)
 {
 	int i = 0;

 	if (access & MAY_READ)
 		string[i++] = 'r';
 	if (access & MAY_WRITE)
 		string[i++] = 'w';
 	if (access & MAY_EXEC)
 		string[i++] = 'x';
 	if (access & MAY_APPEND)
 		string[i++] = 'a';
 	if (access & MAY_TRANSMUTE)
 		string[i++] = 't';
 	if (access & MAY_LOCK)
 		string[i++] = 'l';
 	string[i] = '\0';
 }
 /**
  * smack_log_callback - SMACK specific information
  * will be called by generic audit code
  * @ab : the audit_buffer
  * @a  : audit_data
  *
  */
 static void smack_log_callback(struct audit_buffer *ab, void *a)
 {
 	struct common_audit_data *ad = a;
 	struct smack_audit_data *sad = ad->smack_audit_data;
 	audit_log_format(ab, "lsm=SMACK fn=%s action=%s",
 			 ad->smack_audit_data->function,
 			 sad->result ? "denied" : "granted");
 	audit_log_format(ab, " subject=");
 	audit_log_untrustedstring(ab, sad->subject);
 	audit_log_format(ab, " object=");
 	audit_log_untrustedstring(ab, sad->object);
 	if (sad->request[0] == '\0')
 		audit_log_format(ab, " labels_differ");
 	else
 		audit_log_format(ab, " requested=%s", sad->request);
 }

 /**
  *  smack_log - Audit the granting or denial of permissions.
  *  @subject_label : smack label of the requester
  *  @object_label  : smack label of the object being accessed
  *  @request: requested permissions
  *  @result: result from smk_access
  *  @a:  auxiliary audit data
  *
  * Audit the granting or denial of permissions in accordance
  * with the policy.
  */
 void smack_log(char *subject_label, char *object_label, int request,
 	       int result, struct smk_audit_info *ad)
 {
 #ifdef CONFIG_SECURITY_SMACK_BRINGUP
 	char request_buffer[SMK_NUM_ACCESS_TYPE + 5];
 #else
 	char request_buffer[SMK_NUM_ACCESS_TYPE + 1];
 #endif
 	struct smack_audit_data *sad;
 	struct common_audit_data *a = &ad->a;

 	/* check if we have to log the current event */
 	if (result < 0 && (log_policy & SMACK_AUDIT_DENIED) == 0)
 		return;
 	if (result == 0 && (log_policy & SMACK_AUDIT_ACCEPT) == 0)
 		return;

 	sad = a->smack_audit_data;

 	if (sad->function == NULL)
 		sad->function = "unknown";

 	/* end preparing the audit data */
 	smack_str_from_perm(request_buffer, request);
 	sad->subject = subject_label;
 	sad->object  = object_label;
 #ifdef CONFIG_SECURITY_SMACK_BRINGUP
 	/*
 	 * The result may be positive in bringup mode.
 	 * A positive result is an allow, but not for normal reasons.
 	 * Mark it as successful, but don't filter it out even if
 	 * the logging policy says to do so.
 	 */
 	if (result == SMACK_UNCONFINED_SUBJECT)
 		strcat(request_buffer, "(US)");
 	else if (result == SMACK_UNCONFINED_OBJECT)
 		strcat(request_buffer, "(UO)");

 	if (result > 0)
 		result = 0;
 #endif
 	sad->request = request_buffer;
 	sad->result  = result;

 	common_lsm_audit(a, smack_log_callback, NULL);
 }
 #else /* #ifdef CONFIG_AUDIT */
 void smack_log(char *subject_label, char *object_label, int request,
                int result, struct smk_audit_info *ad)
 {
 }
 #endif

 DEFINE_MUTEX(smack_known_lock);

 struct hlist_head smack_known_hash[SMACK_HASH_SLOTS];

 /**
  * smk_insert_entry - insert a smack label into a hash map,
  *
  * this function must be called under smack_known_lock
  */
 void smk_insert_entry(struct smack_known *skp)
 {
 	unsigned int hash;
 	struct hlist_head *head;

 	hash = full_name_hash(skp->smk_known, strlen(skp->smk_known));
 	head = &smack_known_hash[hash & (SMACK_HASH_SLOTS - 1)];

 	hlist_add_head_rcu(&skp->smk_hashed, head);
 	list_add_rcu(&skp->list, &smack_known_list);
 }

 /**
  * smk_find_entry - find a label on the list, return the list entry
  * @string: a text string that might be a Smack label
  *
  * Returns a pointer to the entry in the label list that
  * matches the passed string or NULL if not found.
  */
 struct smack_known *smk_find_entry(const char *string)
 {
 	unsigned int hash;
 	struct hlist_head *head;
 	struct smack_known *skp;

 	hash = full_name_hash(string, strlen(string));
 	head = &smack_known_hash[hash & (SMACK_HASH_SLOTS - 1)];

 	hlist_for_each_entry_rcu(skp, head, smk_hashed)
 		if (strcmp(skp->smk_known, string) == 0)
 			return skp;

 	return NULL;
 }

 /**
  * smk_parse_smack - parse smack label from a text string
  * @string: a text string that might contain a Smack label
  * @len: the maximum size, or zero if it is NULL terminated.
  *
  * Returns a pointer to the clean label or an error code.
  */
 char *smk_parse_smack(const char *string, int len)
 {
 	char *smack;
 	int i;

 	if (len <= 0)
 		len = strlen(string) + 1;

 	/*
 	 * Reserve a leading '-' as an indicator that
 	 * this isn't a label, but an option to interfaces
 	 * including /smack/cipso and /smack/cipso2
 	 */
 	if (string[0] == '-')
 		return ERR_PTR(-EINVAL);

 	for (i = 0; i < len; i++)
 		if (string[i] > '~' || string[i] <= ' ' || string[i] == '/' ||
 		    string[i] == '"' || string[i] == '\\' || string[i] == '\'')
 			break;

 	if (i == 0 || i >= SMK_LONGLABEL)
 		return ERR_PTR(-EINVAL);

 	smack = kzalloc(i + 1, GFP_KERNEL);
 	if (smack == NULL)
 		return ERR_PTR(-ENOMEM);

 	strncpy(smack, string, i);

 	return smack;
 }

 /**
  * smk_netlbl_mls - convert a catset to netlabel mls categories
  * @catset: the Smack categories
  * @sap: where to put the netlabel categories
  *
  * Allocates and fills attr.mls
  * Returns 0 on success, error code on failure.
  */
 int smk_netlbl_mls(int level, char *catset, struct netlbl_lsm_secattr *sap,
 			int len)
 {
 	unsigned char *cp;
 	unsigned char m;
 	int cat;
 	int rc;
 	int byte;

 	sap->flags |= NETLBL_SECATTR_MLS_CAT;
 	sap->attr.mls.lvl = level;
 	sap->attr.mls.cat = NULL;

 	for (cat = 1, cp = catset, byte = 0; byte < len; cp++, byte++)
 		for (m = 0x80; m != 0; m >>= 1, cat++) {
 			if ((m & *cp) == 0)
 				continue;
 			rc = netlbl_catmap_setbit(&sap->attr.mls.cat,
 						  cat, GFP_ATOMIC);
 			if (rc < 0) {
 				netlbl_catmap_free(sap->attr.mls.cat);
 				return rc;
 			}
 		}

 	return 0;
 }

 /**
  * smk_import_entry - import a label, return the list entry
  * @string: a text string that might be a Smack label
  * @len: the maximum size, or zero if it is NULL terminated.
  *
  * Returns a pointer to the entry in the label list that
  * matches the passed string, adding it if necessary,
  * or an error code.
  */
 struct smack_known *smk_import_entry(const char *string, int len)
 {
 	struct smack_known *skp;
 	char *smack;
 	int slen;
 	int rc;

 	smack = smk_parse_smack(string, len);
 	if (IS_ERR(smack))
 		return ERR_CAST(smack);

 	mutex_lock(&smack_known_lock);

 	skp = smk_find_entry(smack);
 	if (skp != NULL)
 		goto freeout;

 	skp = kzalloc(sizeof(*skp), GFP_KERNEL);
 	if (skp == NULL) {
 		skp = ERR_PTR(-ENOMEM);
 		goto freeout;
 	}

 	skp->smk_known = smack;
 	skp->smk_secid = smack_next_secid++;
 	skp->smk_netlabel.domain = skp->smk_known;
 	skp->smk_netlabel.flags =
 		NETLBL_SECATTR_DOMAIN | NETLBL_SECATTR_MLS_LVL;
 	/*
 	 * If direct labeling works use it.
 	 * Otherwise use mapped labeling.
 	 */
 	slen = strlen(smack);
 	if (slen < SMK_CIPSOLEN)
 		rc = smk_netlbl_mls(smack_cipso_direct, skp->smk_known,
 			       &skp->smk_netlabel, slen);
 	else
 		rc = smk_netlbl_mls(smack_cipso_mapped, (char *)&skp->smk_secid,
 			       &skp->smk_netlabel, sizeof(skp->smk_secid));

 	if (rc >= 0) {
 		INIT_LIST_HEAD(&skp->smk_rules);
 		mutex_init(&skp->smk_rules_lock);
 		/*
 		 * Make sure that the entry is actually
 		 * filled before putting it on the list.
 		 */
 		smk_insert_entry(skp);
 		goto unlockout;
 	}
 	/*
 	 * smk_netlbl_mls failed.
 	 */
 	kfree(skp);
 	skp = ERR_PTR(rc);
 freeout:
 	kfree(smack);
 unlockout:
 	mutex_unlock(&smack_known_lock);

 	return skp;
 }

 /**
  * smack_from_secid - find the Smack label associated with a secid
  * @secid: an integer that might be associated with a Smack label
  *
  * Returns a pointer to the appropriate Smack label entry if there is one,
  * otherwise a pointer to the invalid Smack label.
  */
 struct smack_known *smack_from_secid(const u32 secid)
 {
 	struct smack_known *skp;

 	rcu_read_lock();
 	list_for_each_entry_rcu(skp, &smack_known_list, list) {
 		if (skp->smk_secid == secid) {
 			rcu_read_unlock();
 			return skp;
 		}
 	}

 	/*
 	 * If we got this far someone asked for the translation
 	 * of a secid that is not on the list.
 	 */
 	rcu_read_unlock();
 	return &smack_known_invalid;
 }

 /*
  * Unless a process is running with one of these labels
  * even having CAP_MAC_OVERRIDE isn't enough to grant
  * privilege to violate MAC policy. If no labels are
  * designated (the empty list case) capabilities apply to
  * everyone.
  */
 LIST_HEAD(smack_onlycap_list);
 DEFINE_MUTEX(smack_onlycap_lock);

 /*
  * Is the task privileged and allowed to be privileged
  * by the onlycap rule.
  *
  * Returns 1 if the task is allowed to be privileged, 0 if it's not.
  */
 int smack_privileged(int cap)
 {
 	struct smack_known *skp = smk_of_current();
 	struct smack_onlycap *sop;

 	if (!capable(cap))
 		return 0;

 	rcu_read_lock();
 	if (list_empty(&smack_onlycap_list)) {
 		rcu_read_unlock();
 		return 1;
 	}

 	list_for_each_entry_rcu(sop, &smack_onlycap_list, list) {
 		if (sop->smk_label == skp) {
 			rcu_read_unlock();
 			return 1;
 		}
 	}
 	rcu_read_unlock();

 	return 0;
 }
	/*
	* Copyright (C) 2007 Casey Schaufler <casey@schaufler-ca.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.
	*
	* Author:
	* Casey Schaufler <casey@schaufler-ca.com>
	*
	*/

	#include <linux/types.h>
	#include <linux/slab.h>
	#include <linux/fs.h>
	#include <linux/sched.h>
	#include "smack.h"

	struct smack_known smack_known_huh = {
	.smk_known = "?",
	.smk_secid = 2,
	};

	struct smack_known smack_known_hat = {
	.smk_known = "^",
	.smk_secid = 3,
	};

	struct smack_known smack_known_star = {
	.smk_known = "*",
	.smk_secid = 4,
	};

	struct smack_known smack_known_floor = {
	.smk_known = "_",
	.smk_secid = 5,
	};

	struct smack_known smack_known_invalid = {
	.smk_known = "",
	.smk_secid = 6,
	};

	struct smack_known smack_known_web = {
	.smk_known = "@",
	.smk_secid = 7,
	};

	LIST_HEAD(smack_known_list);

	/*
	* The initial value needs to be bigger than any of the
	* known values above.
	*/
	static u32 smack_next_secid = 10;

	/*
	* what events do we log
	* can be overwritten at run-time by /smack/logging
	*/
	int log_policy = SMACK_AUDIT_DENIED;

	/**
	* smk_access_entry - look up matching access rule
	* @subject_label: a pointer to the subject's Smack label
	* @object_label: a pointer to the object's Smack label
	* @rule_list: the list of rules to search
	*
	* This function looks up the subject/object pair in the
	* access rule list and returns the access mode. If no
	* entry is found returns -ENOENT.
	*
	* NOTE:
	*
	* Earlier versions of this function allowed for labels that
	* were not on the label list. This was done to allow for
	* labels to come over the network that had never been seen
	* before on this host. Unless the receiving socket has the
	* star label this will always result in a failure check. The
	* star labeled socket case is now handled in the networking
	* hooks so there is no case where the label is not on the
	* label list. Checking to see if the address of two labels
	* is the same is now a reliable test.
	*
	* Do the object check first because that is more
	* likely to differ.
	*
	* Allowing write access implies allowing locking.
	*/
	int smk_access_entry(char subject_label, char object_label,
	struct list_head *rule_list)
	{
	int may = -ENOENT;
	struct smack_rule *srp;

	list_for_each_entry_rcu(srp, rule_list, list) {
	if (srp->smk_object->smk_known == object_label &&
	srp->smk_subject->smk_known == subject_label) {
	may = srp->smk_access;
	break;
	}
	}

	/*
	* MAY_WRITE implies MAY_LOCK.
	*/
	if ((may & MAY_WRITE) == MAY_WRITE)
	may \|= MAY_LOCK;
	return may;
	}

	/**
	* smk_access - determine if a subject has a specific access to an object
	* @subject: a pointer to the subject's Smack label entry
	* @object: a pointer to the object's Smack label entry
	* @request: the access requested, in "MAY" format
	* @a : a pointer to the audit data
	*
	* This function looks up the subject/object pair in the
	* access rule list and returns 0 if the access is permitted,
	* non zero otherwise.
	*
	* Smack labels are shared on smack_list
	*/
	int smk_access(struct smack_known subject, struct smack_known object,
	int request, struct smk_audit_info *a)
	{
	int may = MAY_NOT;
	int rc = 0;

	/*
	* Hardcoded comparisons.
	*/
	/*
	* A star subject can't access any object.
	*/
	if (subject == &smack_known_star) {
	rc = -EACCES;
	goto out_audit;
	}
	/*
	* An internet object can be accessed by any subject.
	* Tasks cannot be assigned the internet label.
	* An internet subject can access any object.
	*/
	if (object == &smack_known_web \|\| subject == &smack_known_web)
	goto out_audit;
	/*
	* A star object can be accessed by any subject.
	*/
	if (object == &smack_known_star)
	goto out_audit;
	/*
	* An object can be accessed in any way by a subject
	* with the same label.
	*/
	if (subject->smk_known == object->smk_known)
	goto out_audit;
	/*
	* A hat subject can read or lock any object.
	* A floor object can be read or locked by any subject.
	*/
	if ((request & MAY_ANYREAD) == request \|\|
	(request & MAY_LOCK) == request) {
	if (object == &smack_known_floor)
	goto out_audit;
	if (subject == &smack_known_hat)
	goto out_audit;
	}
	/*
	* Beyond here an explicit relationship is required.
	* If the requested access is contained in the available
	* access (e.g. read is included in readwrite) it's
	* good. A negative response from smk_access_entry()
	* indicates there is no entry for this pair.
	*/
	rcu_read_lock();
	may = smk_access_entry(subject->smk_known, object->smk_known,
	&subject->smk_rules);
	rcu_read_unlock();

	if (may <= 0 \|\| (request & may) != request) {
	rc = -EACCES;
	goto out_audit;
	}
	#ifdef CONFIG_SECURITY_SMACK_BRINGUP
	/*
	* Return a positive value if using bringup mode.
	* This allows the hooks to identify checks that
	* succeed because of "b" rules.
	*/
	if (may & MAY_BRINGUP)
	rc = SMACK_BRINGUP_ALLOW;
	#endif

	out_audit:

	#ifdef CONFIG_SECURITY_SMACK_BRINGUP
	if (rc < 0) {
	if (object == smack_unconfined)
	rc = SMACK_UNCONFINED_OBJECT;
	if (subject == smack_unconfined)
	rc = SMACK_UNCONFINED_SUBJECT;
	}
	#endif

	#ifdef CONFIG_AUDIT
	if (a)
	smack_log(subject->smk_known, object->smk_known,
	request, rc, a);
	#endif

	return rc;
	}

	/**
	* smk_tskacc - determine if a task has a specific access to an object
	* @tsp: a pointer to the subject's task
	* @obj_known: a pointer to the object's label entry
	* @mode: the access requested, in "MAY" format
	* @a : common audit data
	*
	* This function checks the subject task's label/object label pair
	* in the access rule list and returns 0 if the access is permitted,
	* non zero otherwise. It allows that the task may have the capability
	* to override the rules.
	*/
	int smk_tskacc(struct task_smack tsp, struct smack_known obj_known,
	u32 mode, struct smk_audit_info *a)
	{
	struct smack_known *sbj_known = smk_of_task(tsp);
	int may;
	int rc;

	/*
	* Check the global rule list
	*/
	rc = smk_access(sbj_known, obj_known, mode, NULL);
	if (rc >= 0) {
	/*
	* If there is an entry in the task's rule list
	* it can further restrict access.
	*/
	may = smk_access_entry(sbj_known->smk_known,
	obj_known->smk_known,
	&tsp->smk_rules);
	if (may < 0)
	goto out_audit;
	if ((mode & may) == mode)
	goto out_audit;
	rc = -EACCES;
	}

	/*
	* Allow for priviliged to override policy.
	*/
	if (rc != 0 && smack_privileged(CAP_MAC_OVERRIDE))
	rc = 0;

	out_audit:
	#ifdef CONFIG_AUDIT
	if (a)
	smack_log(sbj_known->smk_known, obj_known->smk_known,
	mode, rc, a);
	#endif
	return rc;
	}

	/**
	* smk_curacc - determine if current has a specific access to an object
	* @obj_known: a pointer to the object's Smack label entry
	* @mode: the access requested, in "MAY" format
	* @a : common audit data
	*
	* This function checks the current subject label/object label pair
	* in the access rule list and returns 0 if the access is permitted,
	* non zero otherwise. It allows that current may have the capability
	* to override the rules.
	*/
	int smk_curacc(struct smack_known *obj_known,
	u32 mode, struct smk_audit_info *a)
	{
	struct task_smack *tsp = current_security();

	return smk_tskacc(tsp, obj_known, mode, a);
	}

	#ifdef CONFIG_AUDIT
	/**
	* smack_str_from_perm : helper to transalate an int to a
	* readable string
	* @string : the string to fill
	* @access : the int
	*
	*/
	static inline void smack_str_from_perm(char *string, int access)
	{
	int i = 0;

	if (access & MAY_READ)
	string[i++] = 'r';
	if (access & MAY_WRITE)
	string[i++] = 'w';
	if (access & MAY_EXEC)
	string[i++] = 'x';
	if (access & MAY_APPEND)
	string[i++] = 'a';
	if (access & MAY_TRANSMUTE)
	string[i++] = 't';
	if (access & MAY_LOCK)
	string[i++] = 'l';
	string[i] = '\0';
	}
	/**
	* smack_log_callback - SMACK specific information
	* will be called by generic audit code
	* @ab : the audit_buffer
	* @a : audit_data
	*
	*/
	static void smack_log_callback(struct audit_buffer ab, void a)
	{
	struct common_audit_data *ad = a;
	struct smack_audit_data *sad = ad->smack_audit_data;
	audit_log_format(ab, "lsm=SMACK fn=%s action=%s",
	ad->smack_audit_data->function,
	sad->result ? "denied" : "granted");
	audit_log_format(ab, " subject=");
	audit_log_untrustedstring(ab, sad->subject);
	audit_log_format(ab, " object=");
	audit_log_untrustedstring(ab, sad->object);
	if (sad->request[0] == '\0')
	audit_log_format(ab, " labels_differ");
	else
	audit_log_format(ab, " requested=%s", sad->request);
	}

	/**
	* smack_log - Audit the granting or denial of permissions.
	* @subject_label : smack label of the requester
	* @object_label : smack label of the object being accessed
	* @request: requested permissions
	* @result: result from smk_access
	* @a: auxiliary audit data
	*
	* Audit the granting or denial of permissions in accordance
	* with the policy.
	*/
	void smack_log(char subject_label, char object_label, int request,
	int result, struct smk_audit_info *ad)
	{
	#ifdef CONFIG_SECURITY_SMACK_BRINGUP
	char request_buffer[SMK_NUM_ACCESS_TYPE + 5];
	#else
	char request_buffer[SMK_NUM_ACCESS_TYPE + 1];
	#endif
	struct smack_audit_data *sad;
	struct common_audit_data *a = &ad->a;

	/* check if we have to log the current event */
	if (result < 0 && (log_policy & SMACK_AUDIT_DENIED) == 0)
	return;
	if (result == 0 && (log_policy & SMACK_AUDIT_ACCEPT) == 0)
	return;

	sad = a->smack_audit_data;

	if (sad->function == NULL)
	sad->function = "unknown";

	/* end preparing the audit data */
	smack_str_from_perm(request_buffer, request);
	sad->subject = subject_label;
	sad->object = object_label;
	#ifdef CONFIG_SECURITY_SMACK_BRINGUP
	/*
	* The result may be positive in bringup mode.
	* A positive result is an allow, but not for normal reasons.
	* Mark it as successful, but don't filter it out even if
	* the logging policy says to do so.
	*/
	if (result == SMACK_UNCONFINED_SUBJECT)
	strcat(request_buffer, "(US)");
	else if (result == SMACK_UNCONFINED_OBJECT)
	strcat(request_buffer, "(UO)");

	if (result > 0)
	result = 0;
	#endif
	sad->request = request_buffer;
	sad->result = result;

	common_lsm_audit(a, smack_log_callback, NULL);
	}
	#else /* #ifdef CONFIG_AUDIT */
	void smack_log(char subject_label, char object_label, int request,
	int result, struct smk_audit_info *ad)
	{
	}
	#endif

	DEFINE_MUTEX(smack_known_lock);

	struct hlist_head smack_known_hash[SMACK_HASH_SLOTS];

	/**
	* smk_insert_entry - insert a smack label into a hash map,
	*
	* this function must be called under smack_known_lock
	*/
	void smk_insert_entry(struct smack_known *skp)
	{
	unsigned int hash;
	struct hlist_head *head;

	hash = full_name_hash(skp->smk_known, strlen(skp->smk_known));
	head = &smack_known_hash[hash & (SMACK_HASH_SLOTS - 1)];

	hlist_add_head_rcu(&skp->smk_hashed, head);
	list_add_rcu(&skp->list, &smack_known_list);
	}

	/**
	* smk_find_entry - find a label on the list, return the list entry
	* @string: a text string that might be a Smack label
	*
	* Returns a pointer to the entry in the label list that
	* matches the passed string or NULL if not found.
	*/
	struct smack_known smk_find_entry(const char string)
	{
	unsigned int hash;
	struct hlist_head *head;
	struct smack_known *skp;

	hash = full_name_hash(string, strlen(string));
	head = &smack_known_hash[hash & (SMACK_HASH_SLOTS - 1)];

	hlist_for_each_entry_rcu(skp, head, smk_hashed)
	if (strcmp(skp->smk_known, string) == 0)
	return skp;

	return NULL;
	}

	/**
	* smk_parse_smack - parse smack label from a text string
	* @string: a text string that might contain a Smack label
	* @len: the maximum size, or zero if it is NULL terminated.
	*
	* Returns a pointer to the clean label or an error code.
	*/
	char smk_parse_smack(const char string, int len)
	{
	char *smack;
	int i;

	if (len <= 0)
	len = strlen(string) + 1;

	/*
	* Reserve a leading '-' as an indicator that
	* this isn't a label, but an option to interfaces
	* including /smack/cipso and /smack/cipso2
	*/
	if (string[0] == '-')
	return ERR_PTR(-EINVAL);

	for (i = 0; i < len; i++)
	if (string[i] > '~' \|\| string[i] <= ' ' \|\| string[i] == '/' \|\|
	string[i] == '"' \|\| string[i] == '\\' \|\| string[i] == '\'')
	break;

	if (i == 0 \|\| i >= SMK_LONGLABEL)
	return ERR_PTR(-EINVAL);

	smack = kzalloc(i + 1, GFP_KERNEL);
	if (smack == NULL)
	return ERR_PTR(-ENOMEM);

	strncpy(smack, string, i);

	return smack;
	}

	/**
	* smk_netlbl_mls - convert a catset to netlabel mls categories
	* @catset: the Smack categories
	* @sap: where to put the netlabel categories
	*
	* Allocates and fills attr.mls
	* Returns 0 on success, error code on failure.
	*/
	int smk_netlbl_mls(int level, char catset, struct netlbl_lsm_secattr sap,
	int len)
	{
	unsigned char *cp;
	unsigned char m;
	int cat;
	int rc;
	int byte;

	sap->flags \|= NETLBL_SECATTR_MLS_CAT;
	sap->attr.mls.lvl = level;
	sap->attr.mls.cat = NULL;

	for (cat = 1, cp = catset, byte = 0; byte < len; cp++, byte++)
	for (m = 0x80; m != 0; m >>= 1, cat++) {
	if ((m & *cp) == 0)
	continue;
	rc = netlbl_catmap_setbit(&sap->attr.mls.cat,
	cat, GFP_ATOMIC);
	if (rc < 0) {
	netlbl_catmap_free(sap->attr.mls.cat);
	return rc;
	}
	}

	return 0;
	}

	/**
	* smk_import_entry - import a label, return the list entry
	* @string: a text string that might be a Smack label
	* @len: the maximum size, or zero if it is NULL terminated.
	*
	* Returns a pointer to the entry in the label list that
	* matches the passed string, adding it if necessary,
	* or an error code.
	*/
	struct smack_known smk_import_entry(const char string, int len)
	{
	struct smack_known *skp;
	char *smack;
	int slen;
	int rc;

	smack = smk_parse_smack(string, len);
	if (IS_ERR(smack))
	return ERR_CAST(smack);

	mutex_lock(&smack_known_lock);

	skp = smk_find_entry(smack);
	if (skp != NULL)
	goto freeout;

	skp = kzalloc(sizeof(*skp), GFP_KERNEL);
	if (skp == NULL) {
	skp = ERR_PTR(-ENOMEM);
	goto freeout;
	}

	skp->smk_known = smack;
	skp->smk_secid = smack_next_secid++;
	skp->smk_netlabel.domain = skp->smk_known;
	skp->smk_netlabel.flags =
	NETLBL_SECATTR_DOMAIN \| NETLBL_SECATTR_MLS_LVL;
	/*
	* If direct labeling works use it.
	* Otherwise use mapped labeling.
	*/
	slen = strlen(smack);
	if (slen < SMK_CIPSOLEN)
	rc = smk_netlbl_mls(smack_cipso_direct, skp->smk_known,
	&skp->smk_netlabel, slen);
	else
	rc = smk_netlbl_mls(smack_cipso_mapped, (char *)&skp->smk_secid,
	&skp->smk_netlabel, sizeof(skp->smk_secid));

	if (rc >= 0) {
	INIT_LIST_HEAD(&skp->smk_rules);
	mutex_init(&skp->smk_rules_lock);
	/*
	* Make sure that the entry is actually
	* filled before putting it on the list.
	*/
	smk_insert_entry(skp);
	goto unlockout;
	}
	/*
	* smk_netlbl_mls failed.
	*/
	kfree(skp);
	skp = ERR_PTR(rc);
	freeout:
	kfree(smack);
	unlockout:
	mutex_unlock(&smack_known_lock);

	return skp;
	}

	/**
	* smack_from_secid - find the Smack label associated with a secid
	* @secid: an integer that might be associated with a Smack label
	*
	* Returns a pointer to the appropriate Smack label entry if there is one,
	* otherwise a pointer to the invalid Smack label.
	*/
	struct smack_known *smack_from_secid(const u32 secid)
	{
	struct smack_known *skp;

	rcu_read_lock();
	list_for_each_entry_rcu(skp, &smack_known_list, list) {
	if (skp->smk_secid == secid) {
	rcu_read_unlock();
	return skp;
	}
	}

	/*
	* If we got this far someone asked for the translation
	* of a secid that is not on the list.
	*/
	rcu_read_unlock();
	return &smack_known_invalid;
	}

	/*
	* Unless a process is running with one of these labels
	* even having CAP_MAC_OVERRIDE isn't enough to grant
	* privilege to violate MAC policy. If no labels are
	* designated (the empty list case) capabilities apply to
	* everyone.
	*/
	LIST_HEAD(smack_onlycap_list);
	DEFINE_MUTEX(smack_onlycap_lock);

	/*
	* Is the task privileged and allowed to be privileged
	* by the onlycap rule.
	*
	* Returns 1 if the task is allowed to be privileged, 0 if it's not.
	*/
	int smack_privileged(int cap)
	{
	struct smack_known *skp = smk_of_current();
	struct smack_onlycap *sop;

	if (!capable(cap))
	return 0;

	rcu_read_lock();
	if (list_empty(&smack_onlycap_list)) {
	rcu_read_unlock();
	return 1;
	}

	list_for_each_entry_rcu(sop, &smack_onlycap_list, list) {
	if (sop->smk_label == skp) {
	rcu_read_unlock();
	return 1;
	}
	}
	rcu_read_unlock();

	return 0;
	}