175 lines
3.6 KiB
C
175 lines
3.6 KiB
C
/*
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* Copyright (C) 2008 IBM Corporation
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*
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* Authors:
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* Mimi Zohar <zohar@us.ibm.com>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation, version 2 of the
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* License.
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*
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* File: ima_iint.c
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* - implements the IMA hooks: ima_inode_alloc, ima_inode_free
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* - cache integrity information associated with an inode
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* using a rbtree tree.
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*/
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#include <linux/slab.h>
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#include <linux/module.h>
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#include <linux/spinlock.h>
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#include <linux/rbtree.h>
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#include "ima.h"
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static struct rb_root ima_iint_tree = RB_ROOT;
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static DEFINE_SPINLOCK(ima_iint_lock);
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static struct kmem_cache *iint_cache __read_mostly;
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int iint_initialized = 0;
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/*
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* __ima_iint_find - return the iint associated with an inode
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*/
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static struct ima_iint_cache *__ima_iint_find(struct inode *inode)
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{
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struct ima_iint_cache *iint;
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struct rb_node *n = ima_iint_tree.rb_node;
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assert_spin_locked(&ima_iint_lock);
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while (n) {
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iint = rb_entry(n, struct ima_iint_cache, rb_node);
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if (inode < iint->inode)
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n = n->rb_left;
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else if (inode > iint->inode)
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n = n->rb_right;
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else
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break;
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}
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if (!n)
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return NULL;
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return iint;
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}
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/*
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* ima_iint_find - return the iint associated with an inode
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*/
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struct ima_iint_cache *ima_iint_find(struct inode *inode)
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{
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struct ima_iint_cache *iint;
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if (!IS_IMA(inode))
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return NULL;
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spin_lock(&ima_iint_lock);
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iint = __ima_iint_find(inode);
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spin_unlock(&ima_iint_lock);
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return iint;
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}
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static void iint_free(struct ima_iint_cache *iint)
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{
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iint->version = 0;
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iint->flags = 0UL;
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kmem_cache_free(iint_cache, iint);
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}
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/**
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* ima_inode_alloc - allocate an iint associated with an inode
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* @inode: pointer to the inode
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*/
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int ima_inode_alloc(struct inode *inode)
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{
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struct rb_node **p;
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struct rb_node *new_node, *parent = NULL;
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struct ima_iint_cache *new_iint, *test_iint;
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int rc;
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new_iint = kmem_cache_alloc(iint_cache, GFP_NOFS);
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if (!new_iint)
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return -ENOMEM;
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new_iint->inode = inode;
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new_node = &new_iint->rb_node;
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mutex_lock(&inode->i_mutex); /* i_flags */
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spin_lock(&ima_iint_lock);
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p = &ima_iint_tree.rb_node;
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while (*p) {
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parent = *p;
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test_iint = rb_entry(parent, struct ima_iint_cache, rb_node);
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rc = -EEXIST;
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if (inode < test_iint->inode)
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p = &(*p)->rb_left;
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else if (inode > test_iint->inode)
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p = &(*p)->rb_right;
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else
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goto out_err;
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}
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inode->i_flags |= S_IMA;
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rb_link_node(new_node, parent, p);
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rb_insert_color(new_node, &ima_iint_tree);
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spin_unlock(&ima_iint_lock);
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mutex_unlock(&inode->i_mutex); /* i_flags */
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return 0;
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out_err:
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spin_unlock(&ima_iint_lock);
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mutex_unlock(&inode->i_mutex); /* i_flags */
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iint_free(new_iint);
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return rc;
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}
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/**
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* ima_inode_free - called on security_inode_free
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* @inode: pointer to the inode
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*
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* Free the integrity information(iint) associated with an inode.
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*/
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void ima_inode_free(struct inode *inode)
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{
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struct ima_iint_cache *iint;
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if (inode->i_readcount)
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printk(KERN_INFO "%s: readcount: %u\n", __func__, inode->i_readcount);
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inode->i_readcount = 0;
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if (!IS_IMA(inode))
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return;
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spin_lock(&ima_iint_lock);
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iint = __ima_iint_find(inode);
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rb_erase(&iint->rb_node, &ima_iint_tree);
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spin_unlock(&ima_iint_lock);
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iint_free(iint);
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}
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static void init_once(void *foo)
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{
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struct ima_iint_cache *iint = foo;
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memset(iint, 0, sizeof *iint);
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iint->version = 0;
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iint->flags = 0UL;
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mutex_init(&iint->mutex);
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}
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static int __init ima_iintcache_init(void)
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{
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iint_cache =
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kmem_cache_create("iint_cache", sizeof(struct ima_iint_cache), 0,
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SLAB_PANIC, init_once);
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iint_initialized = 1;
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return 0;
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}
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security_initcall(ima_iintcache_init);
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