127 lines
3.6 KiB
C
127 lines
3.6 KiB
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/audit.h>
|
|
#include <linux/security.h>
|
|
#include <linux/magic.h>
|
|
|
|
#include "ima.h"
|
|
|
|
/* flags definitions */
|
|
#define IMA_FUNC 0x0001
|
|
#define IMA_MASK 0x0002
|
|
#define IMA_FSMAGIC 0x0004
|
|
#define IMA_UID 0x0008
|
|
|
|
enum ima_action { DONT_MEASURE, MEASURE };
|
|
|
|
struct ima_measure_rule_entry {
|
|
struct list_head list;
|
|
enum ima_action action;
|
|
unsigned int flags;
|
|
enum ima_hooks func;
|
|
int mask;
|
|
unsigned long fsmagic;
|
|
uid_t uid;
|
|
};
|
|
|
|
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 = SECURITYFS_MAGIC,
|
|
.flags = IMA_FSMAGIC},
|
|
{.action = DONT_MEASURE,.fsmagic = 0xF97CFF8C,.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 = PATH_CHECK,.mask = MAY_READ,.uid = 0,
|
|
.flags = IMA_FUNC | IMA_MASK | IMA_UID}
|
|
};
|
|
|
|
static LIST_HEAD(measure_default_rules);
|
|
static struct list_head *ima_measure;
|
|
|
|
/**
|
|
* 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;
|
|
|
|
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 != tsk->cred->uid)
|
|
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)
|
|
{
|
|
struct ima_measure_rule_entry *entry;
|
|
|
|
list_for_each_entry(entry, ima_measure, list) {
|
|
bool rc;
|
|
|
|
rc = ima_match_rules(entry, inode, func, mask);
|
|
if (rc)
|
|
return entry->action;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* ima_init_policy - initialize the default measure rules.
|
|
*
|
|
* (Could use the default_rules directly, but in policy patch
|
|
* ima_measure points to either the measure_default_rules or the
|
|
* the new measure_policy_rules.)
|
|
*/
|
|
void ima_init_policy(void)
|
|
{
|
|
int i;
|
|
|
|
for (i = 0; i < ARRAY_SIZE(default_rules); i++)
|
|
list_add_tail(&default_rules[i].list, &measure_default_rules);
|
|
ima_measure = &measure_default_rules;
|
|
}
|