[deliverable/linux.git] / security / integrity / ima / ima_policy.c

/*
 * 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 UNKNOWN			0
#define MEASURE			1	/* same as IMA_MEASURE */
#define DONT_MEASURE		2
#define MEASURE_MASK		3
#define APPRAISE		4	/* same as IMA_APPRAISE */
#define DONT_APPRAISE		8
#define APPRAISE_MASK		12

#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_measure_rule_entry {
	struct list_head list;
	int action;
	unsigned int flags;
	enum ima_hooks func;
	int mask;
	unsigned long fsmagic;
	uid_t uid;
	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, and .uid
 */

/*
 * 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_measure_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 LIST_HEAD(measure_default_rules);
static LIST_HEAD(measure_policy_rules);
static struct list_head *ima_measure;

static DEFINE_MUTEX(ima_measure_mutex);

static bool ima_use_tcb __initdata;
static int __init default_policy_setup(char *str)
{
	ima_use_tcb = 1;
	return 1;
}
__setup("ima_tcb", default_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_measure_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;
	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_measure_rule_entry *entry;
	int action = 0, actmask = flags | (flags << 1);

	list_for_each_entry(entry, ima_measure, list) {

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

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

		action |= (entry->action & (IMA_APPRAISE | IMA_MEASURE));
		actmask &= (entry->action & APPRAISE_MASK) ?
		    ~APPRAISE_MASK : ~MEASURE_MASK;
		if (!actmask)
			break;
	}

	return action;
}

/**
 * ima_init_policy - initialize the default measure rules.
 *
 * ima_measure points to either the measure_default_rules or the
 * the new measure_policy_rules.
 */
void __init ima_init_policy(void)
{
	int i, entries;

	/* if !ima_use_tcb set entries = 0 so we load NO default rules */
	if (ima_use_tcb)
		entries = ARRAY_SIZE(default_rules);
	else
		entries = 0;

	for (i = 0; i < entries; i++)
		list_add_tail(&default_rules[i].list, &measure_default_rules);
	ima_measure = &measure_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_measure == &measure_default_rules) {
		ima_measure = &measure_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_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
};

static match_table_t policy_tokens = {
	{Opt_measure, "measure"},
	{Opt_dont_measure, "dont_measure"},
	{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_err, NULL}
};

static int ima_lsm_rule_init(struct ima_measure_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_measure_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->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_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_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 measure_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_measure_rule_entry *entry;
	ssize_t result, len;
	int audit_info = 0;

	/* Prevent installed policy from changing */
	if (ima_measure != &measure_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_measure_mutex);
	list_add_tail(&entry->list, &measure_policy_rules);
	mutex_unlock(&ima_measure_mutex);

	return len;
}

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

	mutex_lock(&ima_measure_mutex);
	list_for_each_entry_safe(entry, tmp, &measure_policy_rules, list) {
		list_del(&entry->list);
		kfree(entry);
	}
	mutex_unlock(&ima_measure_mutex);
}
Commit	Line	Data
3323eec9 MZ	1	/*
	2	* Copyright (C) 2008 IBM Corporation
	3	* Author: Mimi Zohar <zohar@us.ibm.com>
	4	*
	5	* This program is free software; you can redistribute it and/or modify
	6	* it under the terms of the GNU General Public License as published by
	7	* the Free Software Foundation, version 2 of the License.
	8	*
	9	* ima_policy.c
	10	* - initialize default measure policy rules
	11	*
	12	*/
	13	#include <linux/module.h>
	14	#include <linux/list.h>
3323eec9 MZ	15	#include <linux/security.h>
3323eec9 MZ	16	#include <linux/magic.h>
4af4662f	17	#include <linux/parser.h>
5a0e3ad6	18	#include <linux/slab.h>
3323eec9 MZ	19
	20	#include "ima.h"
	21
	22	/* flags definitions */
	23	#define IMA_FUNC 0x0001
	24	#define IMA_MASK 0x0002
	25	#define IMA_FSMAGIC 0x0004
	26	#define IMA_UID 0x0008
	27
2fe5d6de MZ	28	#define UNKNOWN 0
	29	#define MEASURE 1 /* same as IMA_MEASURE */
	30	#define DONT_MEASURE 2
	31	#define MEASURE_MASK 3
	32	#define APPRAISE 4 /* same as IMA_APPRAISE */
	33	#define DONT_APPRAISE 8
	34	#define APPRAISE_MASK 12
4af4662f MZ	35
	36	#define MAX_LSM_RULES 6
	37	enum lsm_rule_types { LSM_OBJ_USER, LSM_OBJ_ROLE, LSM_OBJ_TYPE,
	38	LSM_SUBJ_USER, LSM_SUBJ_ROLE, LSM_SUBJ_TYPE
	39	};
3323eec9 MZ	40
	41	struct ima_measure_rule_entry {
	42	struct list_head list;
2fe5d6de	43	int action;
3323eec9 MZ	44	unsigned int flags;
	45	enum ima_hooks func;
	46	int mask;
	47	unsigned long fsmagic;
	48	uid_t uid;
4af4662f MZ	49	struct {
	50	void rule; / LSM file metadata specific */
	51	int type; /* audit type */
	52	} lsm[MAX_LSM_RULES];
3323eec9 MZ	53	};
3323eec9 MZ	54
5789ba3b EP	55	/*
5789ba3b EP	56	* Without LSM specific knowledge, the default policy can only be
4af4662f MZ	57	* written in terms of .action, .func, .mask, .fsmagic, and .uid
4af4662f MZ	58	*/
5789ba3b EP	59
	60	/*
	61	* The minimum rule set to allow for full TCB coverage. Measures all files
	62	* opened or mmap for exec and everything read by root. Dangerous because
	63	* normal users can easily run the machine out of memory simply building
	64	* and running executables.
	65	*/
3323eec9	66	static struct ima_measure_rule_entry default_rules[] = {
75834fc3	67	{.action = DONT_MEASURE,.fsmagic = PROC_SUPER_MAGIC,.flags = IMA_FSMAGIC},
3323eec9 MZ	68	{.action = DONT_MEASURE,.fsmagic = SYSFS_MAGIC,.flags = IMA_FSMAGIC},
	69	{.action = DONT_MEASURE,.fsmagic = DEBUGFS_MAGIC,.flags = IMA_FSMAGIC},
	70	{.action = DONT_MEASURE,.fsmagic = TMPFS_MAGIC,.flags = IMA_FSMAGIC},
4c2c3927	71	{.action = DONT_MEASURE,.fsmagic = RAMFS_MAGIC,.flags = IMA_FSMAGIC},
8445d64d DK	72	{.action = DONT_MEASURE,.fsmagic = DEVPTS_SUPER_MAGIC,.flags = IMA_FSMAGIC},
8445d64d DK	73	{.action = DONT_MEASURE,.fsmagic = BINFMTFS_MAGIC,.flags = IMA_FSMAGIC},
75834fc3 EP	74	{.action = DONT_MEASURE,.fsmagic = SECURITYFS_MAGIC,.flags = IMA_FSMAGIC},
75834fc3 EP	75	{.action = DONT_MEASURE,.fsmagic = SELINUX_MAGIC,.flags = IMA_FSMAGIC},
3323eec9 MZ	76	{.action = MEASURE,.func = FILE_MMAP,.mask = MAY_EXEC,
	77	.flags = IMA_FUNC \| IMA_MASK},
	78	{.action = MEASURE,.func = BPRM_CHECK,.mask = MAY_EXEC,
	79	.flags = IMA_FUNC \| IMA_MASK},
1e93d005	80	{.action = MEASURE,.func = FILE_CHECK,.mask = MAY_READ,.uid = 0,
5789ba3b	81	.flags = IMA_FUNC \| IMA_MASK \| IMA_UID},
3323eec9 MZ	82	};
	83
	84	static LIST_HEAD(measure_default_rules);
4af4662f	85	static LIST_HEAD(measure_policy_rules);
3323eec9 MZ	86	static struct list_head *ima_measure;
3323eec9 MZ	87
4af4662f MZ	88	static DEFINE_MUTEX(ima_measure_mutex);
4af4662f MZ	89
5789ba3b EP	90	static bool ima_use_tcb __initdata;
	91	static int __init default_policy_setup(char *str)
	92	{
	93	ima_use_tcb = 1;
	94	return 1;
	95	}
	96	__setup("ima_tcb", default_policy_setup);
	97
3323eec9 MZ	98	/**
	99	* ima_match_rules - determine whether an inode matches the measure rule.
	100	* @rule: a pointer to a rule
	101	* @inode: a pointer to an inode
	102	* @func: LIM hook identifier
	103	* @mask: requested action (MAY_READ \| MAY_WRITE \| MAY_APPEND \| MAY_EXEC)
	104	*
	105	* Returns true on rule match, false on failure.
	106	*/
	107	static bool ima_match_rules(struct ima_measure_rule_entry *rule,
	108	struct inode *inode, enum ima_hooks func, int mask)
	109	{
	110	struct task_struct *tsk = current;
3db59dd9	111	const struct cred *cred = current_cred();
4af4662f	112	int i;
3323eec9 MZ	113
	114	if ((rule->flags & IMA_FUNC) && rule->func != func)
	115	return false;
	116	if ((rule->flags & IMA_MASK) && rule->mask != mask)
	117	return false;
	118	if ((rule->flags & IMA_FSMAGIC)
	119	&& rule->fsmagic != inode->i_sb->s_magic)
	120	return false;
3db59dd9	121	if ((rule->flags & IMA_UID) && rule->uid != cred->uid)
3323eec9	122	return false;
4af4662f	123	for (i = 0; i < MAX_LSM_RULES; i++) {
53fc0e22	124	int rc = 0;
4af4662f MZ	125	u32 osid, sid;
	126
	127	if (!rule->lsm[i].rule)
	128	continue;
	129
	130	switch (i) {
	131	case LSM_OBJ_USER:
	132	case LSM_OBJ_ROLE:
	133	case LSM_OBJ_TYPE:
	134	security_inode_getsecid(inode, &osid);
	135	rc = security_filter_rule_match(osid,
	136	rule->lsm[i].type,
53fc0e22	137	Audit_equal,
4af4662f MZ	138	rule->lsm[i].rule,
	139	NULL);
	140	break;
	141	case LSM_SUBJ_USER:
	142	case LSM_SUBJ_ROLE:
	143	case LSM_SUBJ_TYPE:
	144	security_task_getsecid(tsk, &sid);
	145	rc = security_filter_rule_match(sid,
	146	rule->lsm[i].type,
53fc0e22	147	Audit_equal,
4af4662f MZ	148	rule->lsm[i].rule,
	149	NULL);
	150	default:
	151	break;
	152	}
	153	if (!rc)
	154	return false;
	155	}
3323eec9 MZ	156	return true;
	157	}
	158
	159	/**
	160	* ima_match_policy - decision based on LSM and other conditions
	161	* @inode: pointer to an inode for which the policy decision is being made
	162	* @func: IMA hook identifier
	163	* @mask: requested action (MAY_READ \| MAY_WRITE \| MAY_APPEND \| MAY_EXEC)
	164	*
	165	* Measure decision based on func/mask/fsmagic and LSM(subj/obj/type)
	166	* conditions.
	167	*
	168	* (There is no need for locking when walking the policy list,
	169	* as elements in the list are never deleted, nor does the list
	170	* change.)
	171	*/
2fe5d6de MZ	172	int ima_match_policy(struct inode *inode, enum ima_hooks func, int mask,
2fe5d6de MZ	173	int flags)
3323eec9 MZ	174	{
3323eec9 MZ	175	struct ima_measure_rule_entry *entry;
2fe5d6de	176	int action = 0, actmask = flags \| (flags << 1);
3323eec9 MZ	177
3323eec9 MZ	178	list_for_each_entry(entry, ima_measure, list) {
3323eec9	179
2fe5d6de MZ	180	if (!(entry->action & actmask))
	181	continue;
	182
	183	if (!ima_match_rules(entry, inode, func, mask))
	184	continue;
	185
	186	action \|= (entry->action & (IMA_APPRAISE \| IMA_MEASURE));
	187	actmask &= (entry->action & APPRAISE_MASK) ?
	188	~APPRAISE_MASK : ~MEASURE_MASK;
	189	if (!actmask)
	190	break;
3323eec9	191	}
2fe5d6de MZ	192
2fe5d6de MZ	193	return action;
3323eec9 MZ	194	}
	195
	196	/**
	197	* ima_init_policy - initialize the default measure rules.
	198	*
3323eec9	199	* ima_measure points to either the measure_default_rules or the
4af4662f	200	* the new measure_policy_rules.
3323eec9	201	*/
932995f0	202	void __init ima_init_policy(void)
3323eec9	203	{
5789ba3b EP	204	int i, entries;
	205
	206	/* if !ima_use_tcb set entries = 0 so we load NO default rules */
	207	if (ima_use_tcb)
	208	entries = ARRAY_SIZE(default_rules);
	209	else
	210	entries = 0;
3323eec9	211
5789ba3b	212	for (i = 0; i < entries; i++)
3323eec9 MZ	213	list_add_tail(&default_rules[i].list, &measure_default_rules);
	214	ima_measure = &measure_default_rules;
	215	}
4af4662f MZ	216
	217	/**
	218	* ima_update_policy - update default_rules with new measure rules
	219	*
	220	* Called on file .release to update the default rules with a complete new
	221	* policy. Once updated, the policy is locked, no additional rules can be
	222	* added to the policy.
	223	*/
	224	void ima_update_policy(void)
	225	{
	226	const char *op = "policy_update";
	227	const char *cause = "already exists";
	228	int result = 1;
	229	int audit_info = 0;
	230
	231	if (ima_measure == &measure_default_rules) {
	232	ima_measure = &measure_policy_rules;
	233	cause = "complete";
	234	result = 0;
	235	}
	236	integrity_audit_msg(AUDIT_INTEGRITY_STATUS, NULL,
	237	NULL, op, cause, result, audit_info);
	238	}
	239
	240	enum {
	241	Opt_err = -1,
	242	Opt_measure = 1, Opt_dont_measure,
	243	Opt_obj_user, Opt_obj_role, Opt_obj_type,
	244	Opt_subj_user, Opt_subj_role, Opt_subj_type,
	245	Opt_func, Opt_mask, Opt_fsmagic, Opt_uid
	246	};
	247
	248	static match_table_t policy_tokens = {
	249	{Opt_measure, "measure"},
	250	{Opt_dont_measure, "dont_measure"},
	251	{Opt_obj_user, "obj_user=%s"},
	252	{Opt_obj_role, "obj_role=%s"},
	253	{Opt_obj_type, "obj_type=%s"},
	254	{Opt_subj_user, "subj_user=%s"},
	255	{Opt_subj_role, "subj_role=%s"},
	256	{Opt_subj_type, "subj_type=%s"},
	257	{Opt_func, "func=%s"},
	258	{Opt_mask, "mask=%s"},
	259	{Opt_fsmagic, "fsmagic=%s"},
	260	{Opt_uid, "uid=%s"},
	261	{Opt_err, NULL}
	262	};
	263
	264	static int ima_lsm_rule_init(struct ima_measure_rule_entry *entry,
	265	char *args, int lsm_rule, int audit_type)
	266	{
	267	int result;
	268
7b62e162 EP	269	if (entry->lsm[lsm_rule].rule)
	270	return -EINVAL;
	271
4af4662f MZ	272	entry->lsm[lsm_rule].type = audit_type;
4af4662f MZ	273	result = security_filter_rule_init(entry->lsm[lsm_rule].type,
53fc0e22	274	Audit_equal, args,
4af4662f	275	&entry->lsm[lsm_rule].rule);
867c2026 MZ	276	if (!entry->lsm[lsm_rule].rule)
867c2026 MZ	277	return -EINVAL;
4af4662f MZ	278	return result;
	279	}
	280
2f1506cd EP	281	static void ima_log_string(struct audit_buffer ab, char key, char *value)
	282	{
	283	audit_log_format(ab, "%s=", key);
	284	audit_log_untrustedstring(ab, value);
	285	audit_log_format(ab, " ");
	286	}
	287
4af4662f MZ	288	static int ima_parse_rule(char rule, struct ima_measure_rule_entry entry)
	289	{
	290	struct audit_buffer *ab;
	291	char *p;
	292	int result = 0;
	293
523979ad	294	ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_INTEGRITY_RULE);
4af4662f	295
7b62e162	296	entry->uid = -1;
b9035b1f	297	entry->action = UNKNOWN;
28ef4002	298	while ((p = strsep(&rule, " \t")) != NULL) {
4af4662f MZ	299	substring_t args[MAX_OPT_ARGS];
	300	int token;
	301	unsigned long lnum;
	302
	303	if (result < 0)
	304	break;
28ef4002 EP	305	if ((p == '\0') \|\| (p == ' ') \|\| (*p == '\t'))
28ef4002 EP	306	continue;
4af4662f MZ	307	token = match_token(p, policy_tokens, args);
	308	switch (token) {
	309	case Opt_measure:
2f1506cd	310	ima_log_string(ab, "action", "measure");
7b62e162 EP	311
	312	if (entry->action != UNKNOWN)
	313	result = -EINVAL;
	314
4af4662f MZ	315	entry->action = MEASURE;
	316	break;
	317	case Opt_dont_measure:
2f1506cd	318	ima_log_string(ab, "action", "dont_measure");
7b62e162 EP	319
	320	if (entry->action != UNKNOWN)
	321	result = -EINVAL;
	322
4af4662f MZ	323	entry->action = DONT_MEASURE;
	324	break;
	325	case Opt_func:
2f1506cd	326	ima_log_string(ab, "func", args[0].from);
7b62e162 EP	327
	328	if (entry->func)
	329	result = -EINVAL;
	330
1e93d005 MZ	331	if (strcmp(args[0].from, "FILE_CHECK") == 0)
	332	entry->func = FILE_CHECK;
	333	/* PATH_CHECK is for backwards compat */
	334	else if (strcmp(args[0].from, "PATH_CHECK") == 0)
	335	entry->func = FILE_CHECK;
4af4662f MZ	336	else if (strcmp(args[0].from, "FILE_MMAP") == 0)
	337	entry->func = FILE_MMAP;
	338	else if (strcmp(args[0].from, "BPRM_CHECK") == 0)
	339	entry->func = BPRM_CHECK;
	340	else
	341	result = -EINVAL;
	342	if (!result)
	343	entry->flags \|= IMA_FUNC;
	344	break;
	345	case Opt_mask:
2f1506cd	346	ima_log_string(ab, "mask", args[0].from);
7b62e162 EP	347
	348	if (entry->mask)
	349	result = -EINVAL;
	350
4af4662f MZ	351	if ((strcmp(args[0].from, "MAY_EXEC")) == 0)
	352	entry->mask = MAY_EXEC;
	353	else if (strcmp(args[0].from, "MAY_WRITE") == 0)
	354	entry->mask = MAY_WRITE;
	355	else if (strcmp(args[0].from, "MAY_READ") == 0)
	356	entry->mask = MAY_READ;
	357	else if (strcmp(args[0].from, "MAY_APPEND") == 0)
	358	entry->mask = MAY_APPEND;
	359	else
	360	result = -EINVAL;
	361	if (!result)
	362	entry->flags \|= IMA_MASK;
	363	break;
	364	case Opt_fsmagic:
2f1506cd	365	ima_log_string(ab, "fsmagic", args[0].from);
7b62e162 EP	366
	367	if (entry->fsmagic) {
	368	result = -EINVAL;
	369	break;
	370	}
	371
4af4662f MZ	372	result = strict_strtoul(args[0].from, 16,
	373	&entry->fsmagic);
	374	if (!result)
	375	entry->flags \|= IMA_FSMAGIC;
	376	break;
	377	case Opt_uid:
2f1506cd	378	ima_log_string(ab, "uid", args[0].from);
7b62e162 EP	379
	380	if (entry->uid != -1) {
	381	result = -EINVAL;
	382	break;
	383	}
	384
4af4662f MZ	385	result = strict_strtoul(args[0].from, 10, &lnum);
	386	if (!result) {
	387	entry->uid = (uid_t) lnum;
	388	if (entry->uid != lnum)
	389	result = -EINVAL;
	390	else
	391	entry->flags \|= IMA_UID;
	392	}
	393	break;
	394	case Opt_obj_user:
2f1506cd	395	ima_log_string(ab, "obj_user", args[0].from);
4af4662f MZ	396	result = ima_lsm_rule_init(entry, args[0].from,
	397	LSM_OBJ_USER,
	398	AUDIT_OBJ_USER);
	399	break;
	400	case Opt_obj_role:
2f1506cd	401	ima_log_string(ab, "obj_role", args[0].from);
4af4662f MZ	402	result = ima_lsm_rule_init(entry, args[0].from,
	403	LSM_OBJ_ROLE,
	404	AUDIT_OBJ_ROLE);
	405	break;
	406	case Opt_obj_type:
2f1506cd	407	ima_log_string(ab, "obj_type", args[0].from);
4af4662f MZ	408	result = ima_lsm_rule_init(entry, args[0].from,
	409	LSM_OBJ_TYPE,
	410	AUDIT_OBJ_TYPE);
	411	break;
	412	case Opt_subj_user:
2f1506cd	413	ima_log_string(ab, "subj_user", args[0].from);
4af4662f MZ	414	result = ima_lsm_rule_init(entry, args[0].from,
	415	LSM_SUBJ_USER,
	416	AUDIT_SUBJ_USER);
	417	break;
	418	case Opt_subj_role:
2f1506cd	419	ima_log_string(ab, "subj_role", args[0].from);
4af4662f MZ	420	result = ima_lsm_rule_init(entry, args[0].from,
	421	LSM_SUBJ_ROLE,
	422	AUDIT_SUBJ_ROLE);
	423	break;
	424	case Opt_subj_type:
2f1506cd	425	ima_log_string(ab, "subj_type", args[0].from);
4af4662f MZ	426	result = ima_lsm_rule_init(entry, args[0].from,
	427	LSM_SUBJ_TYPE,
	428	AUDIT_SUBJ_TYPE);
	429	break;
	430	case Opt_err:
2f1506cd	431	ima_log_string(ab, "UNKNOWN", p);
e9d393bf	432	result = -EINVAL;
4af4662f MZ	433	break;
	434	}
	435	}
7b62e162	436	if (!result && (entry->action == UNKNOWN))
4af4662f MZ	437	result = -EINVAL;
4af4662f MZ	438
b0d5de4d	439	audit_log_format(ab, "res=%d", !result);
4af4662f MZ	440	audit_log_end(ab);
	441	return result;
	442	}
	443
	444	/**
	445	* ima_parse_add_rule - add a rule to measure_policy_rules
	446	* @rule - ima measurement policy rule
	447	*
	448	* Uses a mutex to protect the policy list from multiple concurrent writers.
6ccd0456	449	* Returns the length of the rule parsed, an error code on failure
4af4662f	450	*/
6ccd0456	451	ssize_t ima_parse_add_rule(char *rule)
4af4662f	452	{
523979ad	453	const char *op = "update_policy";
6ccd0456	454	char *p;
4af4662f	455	struct ima_measure_rule_entry *entry;
6ccd0456	456	ssize_t result, len;
4af4662f MZ	457	int audit_info = 0;
	458
	459	/* Prevent installed policy from changing */
	460	if (ima_measure != &measure_default_rules) {
	461	integrity_audit_msg(AUDIT_INTEGRITY_STATUS, NULL,
	462	NULL, op, "already exists",
	463	-EACCES, audit_info);
	464	return -EACCES;
	465	}
	466
	467	entry = kzalloc(sizeof(*entry), GFP_KERNEL);
	468	if (!entry) {
	469	integrity_audit_msg(AUDIT_INTEGRITY_STATUS, NULL,
	470	NULL, op, "-ENOMEM", -ENOMEM, audit_info);
	471	return -ENOMEM;
	472	}
	473
	474	INIT_LIST_HEAD(&entry->list);
	475
6ccd0456 EP	476	p = strsep(&rule, "\n");
6ccd0456 EP	477	len = strlen(p) + 1;
7233e3ee EP	478
	479	if (*p == '#') {
	480	kfree(entry);
	481	return len;
	482	}
	483
6ccd0456	484	result = ima_parse_rule(p, entry);
7233e3ee	485	if (result) {
4af4662f	486	kfree(entry);
523979ad MZ	487	integrity_audit_msg(AUDIT_INTEGRITY_STATUS, NULL,
	488	NULL, op, "invalid policy", result,
	489	audit_info);
7233e3ee	490	return result;
523979ad	491	}
7233e3ee EP	492
	493	mutex_lock(&ima_measure_mutex);
	494	list_add_tail(&entry->list, &measure_policy_rules);
	495	mutex_unlock(&ima_measure_mutex);
	496
	497	return len;
4af4662f MZ	498	}
	499
	500	/* ima_delete_rules called to cleanup invalid policy */
64c61d80	501	void ima_delete_rules(void)
4af4662f MZ	502	{
	503	struct ima_measure_rule_entry entry, tmp;
	504
	505	mutex_lock(&ima_measure_mutex);
	506	list_for_each_entry_safe(entry, tmp, &measure_policy_rules, list) {
	507	list_del(&entry->list);
	508	kfree(entry);
	509	}
	510	mutex_unlock(&ima_measure_mutex);
	511	}