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/*
* Copyright (C) 2008 IBM Corporation
*
* Authors:
* 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.
*
* File: ima_iint.c
* - implements the IMA hooks: ima_inode_alloc, ima_inode_free
* - cache integrity information associated with an inode
* using a rbtree tree.
*/
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/spinlock.h>
#include <linux/rbtree.h>
#include "ima.h"
static struct rb_root ima_iint_tree = RB_ROOT;
static DEFINE_SPINLOCK(ima_iint_lock);
static struct kmem_cache *iint_cache __read_mostly;
int iint_initialized = 0;
/*
* __ima_iint_find - return the iint associated with an inode
*/
static struct ima_iint_cache *__ima_iint_find(struct inode *inode)
{
struct ima_iint_cache *iint;
struct rb_node *n = ima_iint_tree.rb_node;
assert_spin_locked(&ima_iint_lock);
while (n) {
iint = rb_entry(n, struct ima_iint_cache, rb_node);
if (inode < iint->inode)
n = n->rb_left;
else if (inode > iint->inode)
n = n->rb_right;
else
break;
}
if (!n)
return NULL;
return iint;
}
/*
* ima_iint_find_get - return the iint associated with an inode
*
* ima_iint_find_get gets a reference to the iint. Caller must
* remember to put the iint reference.
*/
struct ima_iint_cache *ima_iint_find_get(struct inode *inode)
{
struct ima_iint_cache *iint;
spin_lock(&ima_iint_lock);
iint = __ima_iint_find(inode);
if (iint)
kref_get(&iint->refcount);
spin_unlock(&ima_iint_lock);
return iint;
}
/**
* ima_inode_alloc - allocate an iint associated with an inode
* @inode: pointer to the inode
*/
int ima_inode_alloc(struct inode *inode)
{
struct rb_node **p;
struct rb_node *new_node, *parent = NULL;
struct ima_iint_cache *new_iint, *test_iint;
int rc;
new_iint = kmem_cache_alloc(iint_cache, GFP_NOFS);
if (!new_iint)
return -ENOMEM;
new_iint->inode = inode;
new_node = &new_iint->rb_node;
spin_lock(&ima_iint_lock);
p = &ima_iint_tree.rb_node;
while (*p) {
parent = *p;
test_iint = rb_entry(parent, struct ima_iint_cache, rb_node);
rc = -EEXIST;
if (inode < test_iint->inode)
p = &(*p)->rb_left;
else if (inode > test_iint->inode)
p = &(*p)->rb_right;
else
goto out_err;
}
rb_link_node(new_node, parent, p);
rb_insert_color(new_node, &ima_iint_tree);
spin_unlock(&ima_iint_lock);
return 0;
out_err:
spin_unlock(&ima_iint_lock);
kref_put(&new_iint->refcount, iint_free);
return rc;
}
/* iint_free - called when the iint refcount goes to zero */
void iint_free(struct kref *kref)
{
struct ima_iint_cache *iint = container_of(kref, struct ima_iint_cache,
refcount);
iint->version = 0;
iint->flags = 0UL;
kref_init(&iint->refcount);
kmem_cache_free(iint_cache, iint);
}
/**
* ima_inode_free - called on security_inode_free
* @inode: pointer to the inode
*
* Free the integrity information(iint) associated with an inode.
*/
void ima_inode_free(struct inode *inode)
{
struct ima_iint_cache *iint;
if (inode->i_readcount)
printk(KERN_INFO "%s: readcount: %u\n", __func__, inode->i_readcount);
inode->i_readcount = 0;
spin_lock(&ima_iint_lock);
iint = __ima_iint_find(inode);
if (iint)
rb_erase(&iint->rb_node, &ima_iint_tree);
spin_unlock(&ima_iint_lock);
if (iint)
kref_put(&iint->refcount, iint_free);
}
static void init_once(void *foo)
{
struct ima_iint_cache *iint = foo;
memset(iint, 0, sizeof *iint);
iint->version = 0;
iint->flags = 0UL;
mutex_init(&iint->mutex);
kref_init(&iint->refcount);
}
static int __init ima_iintcache_init(void)
{
iint_cache =
kmem_cache_create("iint_cache", sizeof(struct ima_iint_cache), 0,
SLAB_PANIC, init_once);
iint_initialized = 1;
return 0;
}
security_initcall(ima_iintcache_init);
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