security/integrity/ima/ima_policy.c - kernel/msm-4.19 - Gitiles

 /*
  * Copyright (C) 2008 IBM Corporation
  * Author: Mimi Zohar <zohar@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.
  *
  * ima_policy.c
  * 	- initialize default measure policy rules
  *
  */
 #include <linux/module.h>
 #include <linux/list.h>
 #include <linux/security.h>
 #include <linux/magic.h>
 #include <linux/parser.h>
 #include <linux/slab.h>

 #include "ima.h"

 /* flags definitions */
 #define IMA_FUNC 	0x0001
 #define IMA_MASK 	0x0002
 #define IMA_FSMAGIC	0x0004
 #define IMA_UID		0x0008
 #define IMA_FOWNER	0x0010

 #define UNKNOWN		0
 #define MEASURE		0x0001	/* same as IMA_MEASURE */
 #define DONT_MEASURE	0x0002
 #define APPRAISE	0x0004	/* same as IMA_APPRAISE */
 #define DONT_APPRAISE	0x0008
 #define AUDIT		0x0040

 #define MAX_LSM_RULES 6
 enum lsm_rule_types { LSM_OBJ_USER, LSM_OBJ_ROLE, LSM_OBJ_TYPE,
 	LSM_SUBJ_USER, LSM_SUBJ_ROLE, LSM_SUBJ_TYPE
 };

 struct ima_rule_entry {
 	struct list_head list;
 	int action;
 	unsigned int flags;
 	enum ima_hooks func;
 	int mask;
 	unsigned long fsmagic;
 	uid_t uid;
 	uid_t fowner;
 	struct {
 		void *rule;	/* LSM file metadata specific */
 		int type;	/* audit type */
 	} lsm[MAX_LSM_RULES];
 };

 /*
  * Without LSM specific knowledge, the default policy can only be
  * written in terms of .action, .func, .mask, .fsmagic, .uid, and .fowner
  */

 /*
  * The minimum rule set to allow for full TCB coverage.  Measures all files
  * opened or mmap for exec and everything read by root.  Dangerous because
  * normal users can easily run the machine out of memory simply building
  * and running executables.
  */
 static struct ima_rule_entry default_rules[] = {
 	{.action = DONT_MEASURE,.fsmagic = PROC_SUPER_MAGIC,.flags = IMA_FSMAGIC},
 	{.action = DONT_MEASURE,.fsmagic = SYSFS_MAGIC,.flags = IMA_FSMAGIC},
 	{.action = DONT_MEASURE,.fsmagic = DEBUGFS_MAGIC,.flags = IMA_FSMAGIC},
 	{.action = DONT_MEASURE,.fsmagic = TMPFS_MAGIC,.flags = IMA_FSMAGIC},
 	{.action = DONT_MEASURE,.fsmagic = RAMFS_MAGIC,.flags = IMA_FSMAGIC},
 	{.action = DONT_MEASURE,.fsmagic = DEVPTS_SUPER_MAGIC,.flags = IMA_FSMAGIC},
 	{.action = DONT_MEASURE,.fsmagic = BINFMTFS_MAGIC,.flags = IMA_FSMAGIC},
 	{.action = DONT_MEASURE,.fsmagic = SECURITYFS_MAGIC,.flags = IMA_FSMAGIC},
 	{.action = DONT_MEASURE,.fsmagic = SELINUX_MAGIC,.flags = IMA_FSMAGIC},
 	{.action = MEASURE,.func = FILE_MMAP,.mask = MAY_EXEC,
 	 .flags = IMA_FUNC | IMA_MASK},
 	{.action = MEASURE,.func = BPRM_CHECK,.mask = MAY_EXEC,
 	 .flags = IMA_FUNC | IMA_MASK},
 	{.action = MEASURE,.func = FILE_CHECK,.mask = MAY_READ,.uid = 0,
 	 .flags = IMA_FUNC | IMA_MASK | IMA_UID},
 };

 static struct ima_rule_entry default_appraise_rules[] = {
 	{.action = DONT_APPRAISE,.fsmagic = PROC_SUPER_MAGIC,.flags = IMA_FSMAGIC},
 	{.action = DONT_APPRAISE,.fsmagic = SYSFS_MAGIC,.flags = IMA_FSMAGIC},
 	{.action = DONT_APPRAISE,.fsmagic = DEBUGFS_MAGIC,.flags = IMA_FSMAGIC},
 	{.action = DONT_APPRAISE,.fsmagic = TMPFS_MAGIC,.flags = IMA_FSMAGIC},
 	{.action = DONT_APPRAISE,.fsmagic = RAMFS_MAGIC,.flags = IMA_FSMAGIC},
 	{.action = DONT_APPRAISE,.fsmagic = DEVPTS_SUPER_MAGIC,.flags = IMA_FSMAGIC},
 	{.action = DONT_APPRAISE,.fsmagic = BINFMTFS_MAGIC,.flags = IMA_FSMAGIC},
 	{.action = DONT_APPRAISE,.fsmagic = SECURITYFS_MAGIC,.flags = IMA_FSMAGIC},
 	{.action = DONT_APPRAISE,.fsmagic = SELINUX_MAGIC,.flags = IMA_FSMAGIC},
 	{.action = DONT_APPRAISE,.fsmagic = CGROUP_SUPER_MAGIC,.flags = IMA_FSMAGIC},
 	{.action = APPRAISE,.fowner = 0,.flags = IMA_FOWNER},
 };

 static LIST_HEAD(ima_default_rules);
 static LIST_HEAD(ima_policy_rules);
 static struct list_head *ima_rules;

 static DEFINE_MUTEX(ima_rules_mutex);

 static bool ima_use_tcb __initdata;
 static int __init default_measure_policy_setup(char *str)
 {
 	ima_use_tcb = 1;
 	return 1;
 }
 __setup("ima_tcb", default_measure_policy_setup);

 static bool ima_use_appraise_tcb __initdata;
 static int __init default_appraise_policy_setup(char *str)
 {
 	ima_use_appraise_tcb = 1;
 	return 1;
 }
 __setup("ima_appraise_tcb", default_appraise_policy_setup);

 /**
  * ima_match_rules - determine whether an inode matches the measure rule.
  * @rule: a pointer to a rule
  * @inode: a pointer to an inode
  * @func: LIM hook identifier
  * @mask: requested action (MAY_READ | MAY_WRITE | MAY_APPEND | MAY_EXEC)
  *
  * Returns true on rule match, false on failure.
  */
 static bool ima_match_rules(struct ima_rule_entry *rule,
 			    struct inode *inode, enum ima_hooks func, int mask)
 {
 	struct task_struct *tsk = current;
 	const struct cred *cred = current_cred();
 	int i;

 	if ((rule->flags & IMA_FUNC) && rule->func != func)
 		return false;
 	if ((rule->flags & IMA_MASK) && rule->mask != mask)
 		return false;
 	if ((rule->flags & IMA_FSMAGIC)
 	    && rule->fsmagic != inode->i_sb->s_magic)
 		return false;
 	if ((rule->flags & IMA_UID) && rule->uid != cred->uid)
 		return false;
 	if ((rule->flags & IMA_FOWNER) && rule->fowner != inode->i_uid)
 		return false;
 	for (i = 0; i < MAX_LSM_RULES; i++) {
 		int rc = 0;
 		u32 osid, sid;

 		if (!rule->lsm[i].rule)
 			continue;

 		switch (i) {
 		case LSM_OBJ_USER:
 		case LSM_OBJ_ROLE:
 		case LSM_OBJ_TYPE:
 			security_inode_getsecid(inode, &osid);
 			rc = security_filter_rule_match(osid,
 							rule->lsm[i].type,
 							Audit_equal,
 							rule->lsm[i].rule,
 							NULL);
 			break;
 		case LSM_SUBJ_USER:
 		case LSM_SUBJ_ROLE:
 		case LSM_SUBJ_TYPE:
 			security_task_getsecid(tsk, &sid);
 			rc = security_filter_rule_match(sid,
 							rule->lsm[i].type,
 							Audit_equal,
 							rule->lsm[i].rule,
 							NULL);
 		default:
 			break;
 		}
 		if (!rc)
 			return false;
 	}
 	return true;
 }

 /**
  * ima_match_policy - decision based on LSM and other conditions
  * @inode: pointer to an inode for which the policy decision is being made
  * @func: IMA hook identifier
  * @mask: requested action (MAY_READ | MAY_WRITE | MAY_APPEND | MAY_EXEC)
  *
  * Measure decision based on func/mask/fsmagic and LSM(subj/obj/type)
  * conditions.
  *
  * (There is no need for locking when walking the policy list,
  * as elements in the list are never deleted, nor does the list
  * change.)
  */
 int ima_match_policy(struct inode *inode, enum ima_hooks func, int mask,
 		     int flags)
 {
 	struct ima_rule_entry *entry;
 	int action = 0, actmask = flags | (flags << 1);

 	list_for_each_entry(entry, ima_rules, list) {

 		if (!(entry->action & actmask))
 			continue;

 		if (!ima_match_rules(entry, inode, func, mask))
 			continue;

 		action |= entry->action & IMA_DO_MASK;
 		if (entry->action & IMA_DO_MASK)
 			actmask &= ~(entry->action | entry->action << 1);
 		else
 			actmask &= ~(entry->action | entry->action >> 1);

 		if (!actmask)
 			break;
 	}

 	return action;
 }

 /**
  * ima_init_policy - initialize the default measure rules.
  *
  * ima_rules points to either the ima_default_rules or the
  * the new ima_policy_rules.
  */
 void __init ima_init_policy(void)
 {
 	int i, measure_entries, appraise_entries;

 	/* if !ima_use_tcb set entries = 0 so we load NO default rules */
 	measure_entries = ima_use_tcb ? ARRAY_SIZE(default_rules) : 0;
 	appraise_entries = ima_use_appraise_tcb ?
 			 ARRAY_SIZE(default_appraise_rules) : 0;

 	for (i = 0; i < measure_entries + appraise_entries; i++) {
 		if (i < measure_entries)
 			list_add_tail(&default_rules[i].list,
 				      &ima_default_rules);
 		else {
 			int j = i - measure_entries;

 			list_add_tail(&default_appraise_rules[j].list,
 				      &ima_default_rules);
 		}
 	}

 	ima_rules = &ima_default_rules;
 }

 /**
  * ima_update_policy - update default_rules with new measure rules
  *
  * Called on file .release to update the default rules with a complete new
  * policy.  Once updated, the policy is locked, no additional rules can be
  * added to the policy.
  */
 void ima_update_policy(void)
 {
 	const char *op = "policy_update";
 	const char *cause = "already exists";
 	int result = 1;
 	int audit_info = 0;

 	if (ima_rules == &ima_default_rules) {
 		ima_rules = &ima_policy_rules;
 		cause = "complete";
 		result = 0;
 	}
 	integrity_audit_msg(AUDIT_INTEGRITY_STATUS, NULL,
 			    NULL, op, cause, result, audit_info);
 }

 enum {
 	Opt_err = -1,
 	Opt_measure = 1, Opt_dont_measure,
 	Opt_appraise, Opt_dont_appraise,
 	Opt_audit,
 	Opt_obj_user, Opt_obj_role, Opt_obj_type,
 	Opt_subj_user, Opt_subj_role, Opt_subj_type,
 	Opt_func, Opt_mask, Opt_fsmagic, Opt_uid, Opt_fowner
 };

 static match_table_t policy_tokens = {
 	{Opt_measure, "measure"},
 	{Opt_dont_measure, "dont_measure"},
 	{Opt_appraise, "appraise"},
 	{Opt_dont_appraise, "dont_appraise"},
 	{Opt_audit, "audit"},
 	{Opt_obj_user, "obj_user=%s"},
 	{Opt_obj_role, "obj_role=%s"},
 	{Opt_obj_type, "obj_type=%s"},
 	{Opt_subj_user, "subj_user=%s"},
 	{Opt_subj_role, "subj_role=%s"},
 	{Opt_subj_type, "subj_type=%s"},
 	{Opt_func, "func=%s"},
 	{Opt_mask, "mask=%s"},
 	{Opt_fsmagic, "fsmagic=%s"},
 	{Opt_uid, "uid=%s"},
 	{Opt_fowner, "fowner=%s"},
 	{Opt_err, NULL}
 };

 static int ima_lsm_rule_init(struct ima_rule_entry *entry,
 			     char *args, int lsm_rule, int audit_type)
 {
 	int result;

 	if (entry->lsm[lsm_rule].rule)
 		return -EINVAL;

 	entry->lsm[lsm_rule].type = audit_type;
 	result = security_filter_rule_init(entry->lsm[lsm_rule].type,
 					   Audit_equal, args,
 					   &entry->lsm[lsm_rule].rule);
 	if (!entry->lsm[lsm_rule].rule)
 		return -EINVAL;
 	return result;
 }

 static void ima_log_string(struct audit_buffer *ab, char *key, char *value)
 {
 	audit_log_format(ab, "%s=", key);
 	audit_log_untrustedstring(ab, value);
 	audit_log_format(ab, " ");
 }

 static int ima_parse_rule(char *rule, struct ima_rule_entry *entry)
 {
 	struct audit_buffer *ab;
 	char *p;
 	int result = 0;

 	ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_INTEGRITY_RULE);

 	entry->uid = -1;
 	entry->fowner = -1;
 	entry->action = UNKNOWN;
 	while ((p = strsep(&rule, " \t")) != NULL) {
 		substring_t args[MAX_OPT_ARGS];
 		int token;
 		unsigned long lnum;

 		if (result < 0)
 			break;
 		if ((*p == '\0') || (*p == ' ') || (*p == '\t'))
 			continue;
 		token = match_token(p, policy_tokens, args);
 		switch (token) {
 		case Opt_measure:
 			ima_log_string(ab, "action", "measure");

 			if (entry->action != UNKNOWN)
 				result = -EINVAL;

 			entry->action = MEASURE;
 			break;
 		case Opt_dont_measure:
 			ima_log_string(ab, "action", "dont_measure");

 			if (entry->action != UNKNOWN)
 				result = -EINVAL;

 			entry->action = DONT_MEASURE;
 			break;
 		case Opt_appraise:
 			ima_log_string(ab, "action", "appraise");

 			if (entry->action != UNKNOWN)
 				result = -EINVAL;

 			entry->action = APPRAISE;
 			break;
 		case Opt_dont_appraise:
 			ima_log_string(ab, "action", "dont_appraise");

 			if (entry->action != UNKNOWN)
 				result = -EINVAL;

 			entry->action = DONT_APPRAISE;
 			break;
 		case Opt_audit:
 			ima_log_string(ab, "action", "audit");

 			if (entry->action != UNKNOWN)
 				result = -EINVAL;

 			entry->action = AUDIT;
 			break;
 		case Opt_func:
 			ima_log_string(ab, "func", args[0].from);

 			if (entry->func)
 				result = -EINVAL;

 			if (strcmp(args[0].from, "FILE_CHECK") == 0)
 				entry->func = FILE_CHECK;
 			/* PATH_CHECK is for backwards compat */
 			else if (strcmp(args[0].from, "PATH_CHECK") == 0)
 				entry->func = FILE_CHECK;
 			else if (strcmp(args[0].from, "FILE_MMAP") == 0)
 				entry->func = FILE_MMAP;
 			else if (strcmp(args[0].from, "BPRM_CHECK") == 0)
 				entry->func = BPRM_CHECK;
 			else
 				result = -EINVAL;
 			if (!result)
 				entry->flags |= IMA_FUNC;
 			break;
 		case Opt_mask:
 			ima_log_string(ab, "mask", args[0].from);

 			if (entry->mask)
 				result = -EINVAL;

 			if ((strcmp(args[0].from, "MAY_EXEC")) == 0)
 				entry->mask = MAY_EXEC;
 			else if (strcmp(args[0].from, "MAY_WRITE") == 0)
 				entry->mask = MAY_WRITE;
 			else if (strcmp(args[0].from, "MAY_READ") == 0)
 				entry->mask = MAY_READ;
 			else if (strcmp(args[0].from, "MAY_APPEND") == 0)
 				entry->mask = MAY_APPEND;
 			else
 				result = -EINVAL;
 			if (!result)
 				entry->flags |= IMA_MASK;
 			break;
 		case Opt_fsmagic:
 			ima_log_string(ab, "fsmagic", args[0].from);

 			if (entry->fsmagic) {
 				result = -EINVAL;
 				break;
 			}

 			result = strict_strtoul(args[0].from, 16,
 						&entry->fsmagic);
 			if (!result)
 				entry->flags |= IMA_FSMAGIC;
 			break;
 		case Opt_uid:
 			ima_log_string(ab, "uid", args[0].from);

 			if (entry->uid != -1) {
 				result = -EINVAL;
 				break;
 			}

 			result = strict_strtoul(args[0].from, 10, &lnum);
 			if (!result) {
 				entry->uid = (uid_t) lnum;
 				if (entry->uid != lnum)
 					result = -EINVAL;
 				else
 					entry->flags |= IMA_UID;
 			}
 			break;
 		case Opt_fowner:
 			ima_log_string(ab, "fowner", args[0].from);

 			if (entry->fowner != -1) {
 				result = -EINVAL;
 				break;
 			}

 			result = strict_strtoul(args[0].from, 10, &lnum);
 			if (!result) {
 				entry->fowner = (uid_t) lnum;
 				if (entry->fowner != lnum)
 					result = -EINVAL;
 				else
 					entry->flags |= IMA_FOWNER;
 			}
 			break;
 		case Opt_obj_user:
 			ima_log_string(ab, "obj_user", args[0].from);
 			result = ima_lsm_rule_init(entry, args[0].from,
 						   LSM_OBJ_USER,
 						   AUDIT_OBJ_USER);
 			break;
 		case Opt_obj_role:
 			ima_log_string(ab, "obj_role", args[0].from);
 			result = ima_lsm_rule_init(entry, args[0].from,
 						   LSM_OBJ_ROLE,
 						   AUDIT_OBJ_ROLE);
 			break;
 		case Opt_obj_type:
 			ima_log_string(ab, "obj_type", args[0].from);
 			result = ima_lsm_rule_init(entry, args[0].from,
 						   LSM_OBJ_TYPE,
 						   AUDIT_OBJ_TYPE);
 			break;
 		case Opt_subj_user:
 			ima_log_string(ab, "subj_user", args[0].from);
 			result = ima_lsm_rule_init(entry, args[0].from,
 						   LSM_SUBJ_USER,
 						   AUDIT_SUBJ_USER);
 			break;
 		case Opt_subj_role:
 			ima_log_string(ab, "subj_role", args[0].from);
 			result = ima_lsm_rule_init(entry, args[0].from,
 						   LSM_SUBJ_ROLE,
 						   AUDIT_SUBJ_ROLE);
 			break;
 		case Opt_subj_type:
 			ima_log_string(ab, "subj_type", args[0].from);
 			result = ima_lsm_rule_init(entry, args[0].from,
 						   LSM_SUBJ_TYPE,
 						   AUDIT_SUBJ_TYPE);
 			break;
 		case Opt_err:
 			ima_log_string(ab, "UNKNOWN", p);
 			result = -EINVAL;
 			break;
 		}
 	}
 	if (!result && (entry->action == UNKNOWN))
 		result = -EINVAL;

 	audit_log_format(ab, "res=%d", !result);
 	audit_log_end(ab);
 	return result;
 }

 /**
  * ima_parse_add_rule - add a rule to ima_policy_rules
  * @rule - ima measurement policy rule
  *
  * Uses a mutex to protect the policy list from multiple concurrent writers.
  * Returns the length of the rule parsed, an error code on failure
  */
 ssize_t ima_parse_add_rule(char *rule)
 {
 	const char *op = "update_policy";
 	char *p;
 	struct ima_rule_entry *entry;
 	ssize_t result, len;
 	int audit_info = 0;

 	/* Prevent installed policy from changing */
 	if (ima_rules != &ima_default_rules) {
 		integrity_audit_msg(AUDIT_INTEGRITY_STATUS, NULL,
 				    NULL, op, "already exists",
 				    -EACCES, audit_info);
 		return -EACCES;
 	}

 	entry = kzalloc(sizeof(*entry), GFP_KERNEL);
 	if (!entry) {
 		integrity_audit_msg(AUDIT_INTEGRITY_STATUS, NULL,
 				    NULL, op, "-ENOMEM", -ENOMEM, audit_info);
 		return -ENOMEM;
 	}

 	INIT_LIST_HEAD(&entry->list);

 	p = strsep(&rule, "\n");
 	len = strlen(p) + 1;

 	if (*p == '#') {
 		kfree(entry);
 		return len;
 	}

 	result = ima_parse_rule(p, entry);
 	if (result) {
 		kfree(entry);
 		integrity_audit_msg(AUDIT_INTEGRITY_STATUS, NULL,
 				    NULL, op, "invalid policy", result,
 				    audit_info);
 		return result;
 	}

 	mutex_lock(&ima_rules_mutex);
 	list_add_tail(&entry->list, &ima_policy_rules);
 	mutex_unlock(&ima_rules_mutex);

 	return len;
 }

 /* ima_delete_rules called to cleanup invalid policy */
 void ima_delete_rules(void)
 {
 	struct ima_rule_entry *entry, *tmp;

 	mutex_lock(&ima_rules_mutex);
 	list_for_each_entry_safe(entry, tmp, &ima_policy_rules, list) {
 		list_del(&entry->list);
 		kfree(entry);
 	}
 	mutex_unlock(&ima_rules_mutex);
 }
	/*
	* Copyright (C) 2008 IBM Corporation
	* Author: Mimi Zohar <zohar@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.
	*
	* ima_policy.c
	* - initialize default measure policy rules
	*
	*/
	#include <linux/module.h>
	#include <linux/list.h>
	#include <linux/security.h>
	#include <linux/magic.h>
	#include <linux/parser.h>
	#include <linux/slab.h>

	#include "ima.h"

	/* flags definitions */
	#define IMA_FUNC 0x0001
	#define IMA_MASK 0x0002
	#define IMA_FSMAGIC 0x0004
	#define IMA_UID 0x0008
	#define IMA_FOWNER 0x0010

	#define UNKNOWN 0
	#define MEASURE 0x0001 /* same as IMA_MEASURE */
	#define DONT_MEASURE 0x0002
	#define APPRAISE 0x0004 /* same as IMA_APPRAISE */
	#define DONT_APPRAISE 0x0008
	#define AUDIT 0x0040

	#define MAX_LSM_RULES 6
	enum lsm_rule_types { LSM_OBJ_USER, LSM_OBJ_ROLE, LSM_OBJ_TYPE,
	LSM_SUBJ_USER, LSM_SUBJ_ROLE, LSM_SUBJ_TYPE
	};

	struct ima_rule_entry {
	struct list_head list;
	int action;
	unsigned int flags;
	enum ima_hooks func;
	int mask;
	unsigned long fsmagic;
	uid_t uid;
	uid_t fowner;
	struct {
	void rule; / LSM file metadata specific */
	int type; /* audit type */
	} lsm[MAX_LSM_RULES];
	};

	/*
	* Without LSM specific knowledge, the default policy can only be
	* written in terms of .action, .func, .mask, .fsmagic, .uid, and .fowner
	*/

	/*
	* The minimum rule set to allow for full TCB coverage. Measures all files
	* opened or mmap for exec and everything read by root. Dangerous because
	* normal users can easily run the machine out of memory simply building
	* and running executables.
	*/
	static struct ima_rule_entry default_rules[] = {
	{.action = DONT_MEASURE,.fsmagic = PROC_SUPER_MAGIC,.flags = IMA_FSMAGIC},
	{.action = DONT_MEASURE,.fsmagic = SYSFS_MAGIC,.flags = IMA_FSMAGIC},
	{.action = DONT_MEASURE,.fsmagic = DEBUGFS_MAGIC,.flags = IMA_FSMAGIC},
	{.action = DONT_MEASURE,.fsmagic = TMPFS_MAGIC,.flags = IMA_FSMAGIC},
	{.action = DONT_MEASURE,.fsmagic = RAMFS_MAGIC,.flags = IMA_FSMAGIC},
	{.action = DONT_MEASURE,.fsmagic = DEVPTS_SUPER_MAGIC,.flags = IMA_FSMAGIC},
	{.action = DONT_MEASURE,.fsmagic = BINFMTFS_MAGIC,.flags = IMA_FSMAGIC},
	{.action = DONT_MEASURE,.fsmagic = SECURITYFS_MAGIC,.flags = IMA_FSMAGIC},
	{.action = DONT_MEASURE,.fsmagic = SELINUX_MAGIC,.flags = IMA_FSMAGIC},
	{.action = MEASURE,.func = FILE_MMAP,.mask = MAY_EXEC,
	.flags = IMA_FUNC \| IMA_MASK},
	{.action = MEASURE,.func = BPRM_CHECK,.mask = MAY_EXEC,
	.flags = IMA_FUNC \| IMA_MASK},
	{.action = MEASURE,.func = FILE_CHECK,.mask = MAY_READ,.uid = 0,
	.flags = IMA_FUNC \| IMA_MASK \| IMA_UID},
	};

	static struct ima_rule_entry default_appraise_rules[] = {
	{.action = DONT_APPRAISE,.fsmagic = PROC_SUPER_MAGIC,.flags = IMA_FSMAGIC},
	{.action = DONT_APPRAISE,.fsmagic = SYSFS_MAGIC,.flags = IMA_FSMAGIC},
	{.action = DONT_APPRAISE,.fsmagic = DEBUGFS_MAGIC,.flags = IMA_FSMAGIC},
	{.action = DONT_APPRAISE,.fsmagic = TMPFS_MAGIC,.flags = IMA_FSMAGIC},
	{.action = DONT_APPRAISE,.fsmagic = RAMFS_MAGIC,.flags = IMA_FSMAGIC},
	{.action = DONT_APPRAISE,.fsmagic = DEVPTS_SUPER_MAGIC,.flags = IMA_FSMAGIC},
	{.action = DONT_APPRAISE,.fsmagic = BINFMTFS_MAGIC,.flags = IMA_FSMAGIC},
	{.action = DONT_APPRAISE,.fsmagic = SECURITYFS_MAGIC,.flags = IMA_FSMAGIC},
	{.action = DONT_APPRAISE,.fsmagic = SELINUX_MAGIC,.flags = IMA_FSMAGIC},
	{.action = DONT_APPRAISE,.fsmagic = CGROUP_SUPER_MAGIC,.flags = IMA_FSMAGIC},
	{.action = APPRAISE,.fowner = 0,.flags = IMA_FOWNER},
	};

	static LIST_HEAD(ima_default_rules);
	static LIST_HEAD(ima_policy_rules);
	static struct list_head *ima_rules;

	static DEFINE_MUTEX(ima_rules_mutex);

	static bool ima_use_tcb __initdata;
	static int __init default_measure_policy_setup(char *str)
	{
	ima_use_tcb = 1;
	return 1;
	}
	__setup("ima_tcb", default_measure_policy_setup);

	static bool ima_use_appraise_tcb __initdata;
	static int __init default_appraise_policy_setup(char *str)
	{
	ima_use_appraise_tcb = 1;
	return 1;
	}
	__setup("ima_appraise_tcb", default_appraise_policy_setup);

	/**
	* ima_match_rules - determine whether an inode matches the measure rule.
	* @rule: a pointer to a rule
	* @inode: a pointer to an inode
	* @func: LIM hook identifier
	* @mask: requested action (MAY_READ \| MAY_WRITE \| MAY_APPEND \| MAY_EXEC)
	*
	* Returns true on rule match, false on failure.
	*/
	static bool ima_match_rules(struct ima_rule_entry *rule,
	struct inode *inode, enum ima_hooks func, int mask)
	{
	struct task_struct *tsk = current;
	const struct cred *cred = current_cred();
	int i;

	if ((rule->flags & IMA_FUNC) && rule->func != func)
	return false;
	if ((rule->flags & IMA_MASK) && rule->mask != mask)
	return false;
	if ((rule->flags & IMA_FSMAGIC)
	&& rule->fsmagic != inode->i_sb->s_magic)
	return false;
	if ((rule->flags & IMA_UID) && rule->uid != cred->uid)
	return false;
	if ((rule->flags & IMA_FOWNER) && rule->fowner != inode->i_uid)
	return false;
	for (i = 0; i < MAX_LSM_RULES; i++) {
	int rc = 0;
	u32 osid, sid;

	if (!rule->lsm[i].rule)
	continue;

	switch (i) {
	case LSM_OBJ_USER:
	case LSM_OBJ_ROLE:
	case LSM_OBJ_TYPE:
	security_inode_getsecid(inode, &osid);
	rc = security_filter_rule_match(osid,
	rule->lsm[i].type,
	Audit_equal,
	rule->lsm[i].rule,
	NULL);
	break;
	case LSM_SUBJ_USER:
	case LSM_SUBJ_ROLE:
	case LSM_SUBJ_TYPE:
	security_task_getsecid(tsk, &sid);
	rc = security_filter_rule_match(sid,
	rule->lsm[i].type,
	Audit_equal,
	rule->lsm[i].rule,
	NULL);
	default:
	break;
	}
	if (!rc)
	return false;
	}
	return true;
	}

	/**
	* ima_match_policy - decision based on LSM and other conditions
	* @inode: pointer to an inode for which the policy decision is being made
	* @func: IMA hook identifier
	* @mask: requested action (MAY_READ \| MAY_WRITE \| MAY_APPEND \| MAY_EXEC)
	*
	* Measure decision based on func/mask/fsmagic and LSM(subj/obj/type)
	* conditions.
	*
	* (There is no need for locking when walking the policy list,
	* as elements in the list are never deleted, nor does the list
	* change.)
	*/
	int ima_match_policy(struct inode *inode, enum ima_hooks func, int mask,
	int flags)
	{
	struct ima_rule_entry *entry;
	int action = 0, actmask = flags \| (flags << 1);

	list_for_each_entry(entry, ima_rules, list) {

	if (!(entry->action & actmask))
	continue;

	if (!ima_match_rules(entry, inode, func, mask))
	continue;

	action \|= entry->action & IMA_DO_MASK;
	if (entry->action & IMA_DO_MASK)
	actmask &= ~(entry->action \| entry->action << 1);
	else
	actmask &= ~(entry->action \| entry->action >> 1);

	if (!actmask)
	break;
	}

	return action;
	}

	/**
	* ima_init_policy - initialize the default measure rules.
	*
	* ima_rules points to either the ima_default_rules or the
	* the new ima_policy_rules.
	*/
	void __init ima_init_policy(void)
	{
	int i, measure_entries, appraise_entries;

	/* if !ima_use_tcb set entries = 0 so we load NO default rules */
	measure_entries = ima_use_tcb ? ARRAY_SIZE(default_rules) : 0;
	appraise_entries = ima_use_appraise_tcb ?
	ARRAY_SIZE(default_appraise_rules) : 0;

	for (i = 0; i < measure_entries + appraise_entries; i++) {
	if (i < measure_entries)
	list_add_tail(&default_rules[i].list,
	&ima_default_rules);
	else {
	int j = i - measure_entries;

	list_add_tail(&default_appraise_rules[j].list,
	&ima_default_rules);
	}
	}

	ima_rules = &ima_default_rules;
	}

	/**
	* ima_update_policy - update default_rules with new measure rules
	*
	* Called on file .release to update the default rules with a complete new
	* policy. Once updated, the policy is locked, no additional rules can be
	* added to the policy.
	*/
	void ima_update_policy(void)
	{
	const char *op = "policy_update";
	const char *cause = "already exists";
	int result = 1;
	int audit_info = 0;

	if (ima_rules == &ima_default_rules) {
	ima_rules = &ima_policy_rules;
	cause = "complete";
	result = 0;
	}
	integrity_audit_msg(AUDIT_INTEGRITY_STATUS, NULL,
	NULL, op, cause, result, audit_info);
	}

	enum {
	Opt_err = -1,
	Opt_measure = 1, Opt_dont_measure,
	Opt_appraise, Opt_dont_appraise,
	Opt_audit,
	Opt_obj_user, Opt_obj_role, Opt_obj_type,
	Opt_subj_user, Opt_subj_role, Opt_subj_type,
	Opt_func, Opt_mask, Opt_fsmagic, Opt_uid, Opt_fowner
	};

	static match_table_t policy_tokens = {
	{Opt_measure, "measure"},
	{Opt_dont_measure, "dont_measure"},
	{Opt_appraise, "appraise"},
	{Opt_dont_appraise, "dont_appraise"},
	{Opt_audit, "audit"},
	{Opt_obj_user, "obj_user=%s"},
	{Opt_obj_role, "obj_role=%s"},
	{Opt_obj_type, "obj_type=%s"},
	{Opt_subj_user, "subj_user=%s"},
	{Opt_subj_role, "subj_role=%s"},
	{Opt_subj_type, "subj_type=%s"},
	{Opt_func, "func=%s"},
	{Opt_mask, "mask=%s"},
	{Opt_fsmagic, "fsmagic=%s"},
	{Opt_uid, "uid=%s"},
	{Opt_fowner, "fowner=%s"},
	{Opt_err, NULL}
	};

	static int ima_lsm_rule_init(struct ima_rule_entry *entry,
	char *args, int lsm_rule, int audit_type)
	{
	int result;

	if (entry->lsm[lsm_rule].rule)
	return -EINVAL;

	entry->lsm[lsm_rule].type = audit_type;
	result = security_filter_rule_init(entry->lsm[lsm_rule].type,
	Audit_equal, args,
	&entry->lsm[lsm_rule].rule);
	if (!entry->lsm[lsm_rule].rule)
	return -EINVAL;
	return result;
	}

	static void ima_log_string(struct audit_buffer ab, char key, char *value)
	{
	audit_log_format(ab, "%s=", key);
	audit_log_untrustedstring(ab, value);
	audit_log_format(ab, " ");
	}

	static int ima_parse_rule(char rule, struct ima_rule_entry entry)
	{
	struct audit_buffer *ab;
	char *p;
	int result = 0;

	ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_INTEGRITY_RULE);

	entry->uid = -1;
	entry->fowner = -1;
	entry->action = UNKNOWN;
	while ((p = strsep(&rule, " \t")) != NULL) {
	substring_t args[MAX_OPT_ARGS];
	int token;
	unsigned long lnum;

	if (result < 0)
	break;
	if ((p == '\0') \|\| (p == ' ') \|\| (*p == '\t'))
	continue;
	token = match_token(p, policy_tokens, args);
	switch (token) {
	case Opt_measure:
	ima_log_string(ab, "action", "measure");

	if (entry->action != UNKNOWN)
	result = -EINVAL;

	entry->action = MEASURE;
	break;
	case Opt_dont_measure:
	ima_log_string(ab, "action", "dont_measure");

	if (entry->action != UNKNOWN)
	result = -EINVAL;

	entry->action = DONT_MEASURE;
	break;
	case Opt_appraise:
	ima_log_string(ab, "action", "appraise");

	if (entry->action != UNKNOWN)
	result = -EINVAL;

	entry->action = APPRAISE;
	break;
	case Opt_dont_appraise:
	ima_log_string(ab, "action", "dont_appraise");

	if (entry->action != UNKNOWN)
	result = -EINVAL;

	entry->action = DONT_APPRAISE;
	break;
	case Opt_audit:
	ima_log_string(ab, "action", "audit");

	if (entry->action != UNKNOWN)
	result = -EINVAL;

	entry->action = AUDIT;
	break;
	case Opt_func:
	ima_log_string(ab, "func", args[0].from);

	if (entry->func)
	result = -EINVAL;

	if (strcmp(args[0].from, "FILE_CHECK") == 0)
	entry->func = FILE_CHECK;
	/* PATH_CHECK is for backwards compat */
	else if (strcmp(args[0].from, "PATH_CHECK") == 0)
	entry->func = FILE_CHECK;
	else if (strcmp(args[0].from, "FILE_MMAP") == 0)
	entry->func = FILE_MMAP;
	else if (strcmp(args[0].from, "BPRM_CHECK") == 0)
	entry->func = BPRM_CHECK;
	else
	result = -EINVAL;
	if (!result)
	entry->flags \|= IMA_FUNC;
	break;
	case Opt_mask:
	ima_log_string(ab, "mask", args[0].from);

	if (entry->mask)
	result = -EINVAL;

	if ((strcmp(args[0].from, "MAY_EXEC")) == 0)
	entry->mask = MAY_EXEC;
	else if (strcmp(args[0].from, "MAY_WRITE") == 0)
	entry->mask = MAY_WRITE;
	else if (strcmp(args[0].from, "MAY_READ") == 0)
	entry->mask = MAY_READ;
	else if (strcmp(args[0].from, "MAY_APPEND") == 0)
	entry->mask = MAY_APPEND;
	else
	result = -EINVAL;
	if (!result)
	entry->flags \|= IMA_MASK;
	break;
	case Opt_fsmagic:
	ima_log_string(ab, "fsmagic", args[0].from);

	if (entry->fsmagic) {
	result = -EINVAL;
	break;
	}

	result = strict_strtoul(args[0].from, 16,
	&entry->fsmagic);
	if (!result)
	entry->flags \|= IMA_FSMAGIC;
	break;
	case Opt_uid:
	ima_log_string(ab, "uid", args[0].from);

	if (entry->uid != -1) {
	result = -EINVAL;
	break;
	}

	result = strict_strtoul(args[0].from, 10, &lnum);
	if (!result) {
	entry->uid = (uid_t) lnum;
	if (entry->uid != lnum)
	result = -EINVAL;
	else
	entry->flags \|= IMA_UID;
	}
	break;
	case Opt_fowner:
	ima_log_string(ab, "fowner", args[0].from);

	if (entry->fowner != -1) {
	result = -EINVAL;
	break;
	}

	result = strict_strtoul(args[0].from, 10, &lnum);
	if (!result) {
	entry->fowner = (uid_t) lnum;
	if (entry->fowner != lnum)
	result = -EINVAL;
	else
	entry->flags \|= IMA_FOWNER;
	}
	break;
	case Opt_obj_user:
	ima_log_string(ab, "obj_user", args[0].from);
	result = ima_lsm_rule_init(entry, args[0].from,
	LSM_OBJ_USER,
	AUDIT_OBJ_USER);
	break;
	case Opt_obj_role:
	ima_log_string(ab, "obj_role", args[0].from);
	result = ima_lsm_rule_init(entry, args[0].from,
	LSM_OBJ_ROLE,
	AUDIT_OBJ_ROLE);
	break;
	case Opt_obj_type:
	ima_log_string(ab, "obj_type", args[0].from);
	result = ima_lsm_rule_init(entry, args[0].from,
	LSM_OBJ_TYPE,
	AUDIT_OBJ_TYPE);
	break;
	case Opt_subj_user:
	ima_log_string(ab, "subj_user", args[0].from);
	result = ima_lsm_rule_init(entry, args[0].from,
	LSM_SUBJ_USER,
	AUDIT_SUBJ_USER);
	break;
	case Opt_subj_role:
	ima_log_string(ab, "subj_role", args[0].from);
	result = ima_lsm_rule_init(entry, args[0].from,
	LSM_SUBJ_ROLE,
	AUDIT_SUBJ_ROLE);
	break;
	case Opt_subj_type:
	ima_log_string(ab, "subj_type", args[0].from);
	result = ima_lsm_rule_init(entry, args[0].from,
	LSM_SUBJ_TYPE,
	AUDIT_SUBJ_TYPE);
	break;
	case Opt_err:
	ima_log_string(ab, "UNKNOWN", p);
	result = -EINVAL;
	break;
	}
	}
	if (!result && (entry->action == UNKNOWN))
	result = -EINVAL;

	audit_log_format(ab, "res=%d", !result);
	audit_log_end(ab);
	return result;
	}

	/**
	* ima_parse_add_rule - add a rule to ima_policy_rules
	* @rule - ima measurement policy rule
	*
	* Uses a mutex to protect the policy list from multiple concurrent writers.
	* Returns the length of the rule parsed, an error code on failure
	*/
	ssize_t ima_parse_add_rule(char *rule)
	{
	const char *op = "update_policy";
	char *p;
	struct ima_rule_entry *entry;
	ssize_t result, len;
	int audit_info = 0;

	/* Prevent installed policy from changing */
	if (ima_rules != &ima_default_rules) {
	integrity_audit_msg(AUDIT_INTEGRITY_STATUS, NULL,
	NULL, op, "already exists",
	-EACCES, audit_info);
	return -EACCES;
	}

	entry = kzalloc(sizeof(*entry), GFP_KERNEL);
	if (!entry) {
	integrity_audit_msg(AUDIT_INTEGRITY_STATUS, NULL,
	NULL, op, "-ENOMEM", -ENOMEM, audit_info);
	return -ENOMEM;
	}

	INIT_LIST_HEAD(&entry->list);

	p = strsep(&rule, "\n");
	len = strlen(p) + 1;

	if (*p == '#') {
	kfree(entry);
	return len;
	}

	result = ima_parse_rule(p, entry);
	if (result) {
	kfree(entry);
	integrity_audit_msg(AUDIT_INTEGRITY_STATUS, NULL,
	NULL, op, "invalid policy", result,
	audit_info);
	return result;
	}

	mutex_lock(&ima_rules_mutex);
	list_add_tail(&entry->list, &ima_policy_rules);
	mutex_unlock(&ima_rules_mutex);

	return len;
	}

	/* ima_delete_rules called to cleanup invalid policy */
	void ima_delete_rules(void)
	{
	struct ima_rule_entry entry, tmp;

	mutex_lock(&ima_rules_mutex);
	list_for_each_entry_safe(entry, tmp, &ima_policy_rules, list) {
	list_del(&entry->list);
	kfree(entry);
	}
	mutex_unlock(&ima_rules_mutex);
	}