linux/security/integrity/iint.c
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   1/*
   2 * Copyright (C) 2008 IBM Corporation
   3 *
   4 * Authors:
   5 * Mimi Zohar <zohar@us.ibm.com>
   6 *
   7 * This program is free software; you can redistribute it and/or
   8 * modify it under the terms of the GNU General Public License as
   9 * published by the Free Software Foundation, version 2 of the
  10 * License.
  11 *
  12 * File: integrity_iint.c
  13 *      - implements the integrity hooks: integrity_inode_alloc,
  14 *        integrity_inode_free
  15 *      - cache integrity information associated with an inode
  16 *        using a rbtree tree.
  17 */
  18#include <linux/slab.h>
  19#include <linux/module.h>
  20#include <linux/spinlock.h>
  21#include <linux/rbtree.h>
  22#include "integrity.h"
  23
  24static struct rb_root integrity_iint_tree = RB_ROOT;
  25static DEFINE_RWLOCK(integrity_iint_lock);
  26static struct kmem_cache *iint_cache __read_mostly;
  27
  28int iint_initialized;
  29
  30/*
  31 * __integrity_iint_find - return the iint associated with an inode
  32 */
  33static struct integrity_iint_cache *__integrity_iint_find(struct inode *inode)
  34{
  35        struct integrity_iint_cache *iint;
  36        struct rb_node *n = integrity_iint_tree.rb_node;
  37
  38        while (n) {
  39                iint = rb_entry(n, struct integrity_iint_cache, rb_node);
  40
  41                if (inode < iint->inode)
  42                        n = n->rb_left;
  43                else if (inode > iint->inode)
  44                        n = n->rb_right;
  45                else
  46                        break;
  47        }
  48        if (!n)
  49                return NULL;
  50
  51        return iint;
  52}
  53
  54/*
  55 * integrity_iint_find - return the iint associated with an inode
  56 */
  57struct integrity_iint_cache *integrity_iint_find(struct inode *inode)
  58{
  59        struct integrity_iint_cache *iint;
  60
  61        if (!IS_IMA(inode))
  62                return NULL;
  63
  64        read_lock(&integrity_iint_lock);
  65        iint = __integrity_iint_find(inode);
  66        read_unlock(&integrity_iint_lock);
  67
  68        return iint;
  69}
  70
  71static void iint_free(struct integrity_iint_cache *iint)
  72{
  73        iint->version = 0;
  74        iint->flags = 0UL;
  75        iint->ima_status = INTEGRITY_UNKNOWN;
  76        iint->evm_status = INTEGRITY_UNKNOWN;
  77        kmem_cache_free(iint_cache, iint);
  78}
  79
  80/**
  81 * integrity_inode_get - find or allocate an iint associated with an inode
  82 * @inode: pointer to the inode
  83 * @return: allocated iint
  84 *
  85 * Caller must lock i_mutex
  86 */
  87struct integrity_iint_cache *integrity_inode_get(struct inode *inode)
  88{
  89        struct rb_node **p;
  90        struct rb_node *node, *parent = NULL;
  91        struct integrity_iint_cache *iint, *test_iint;
  92
  93        iint = integrity_iint_find(inode);
  94        if (iint)
  95                return iint;
  96
  97        iint = kmem_cache_alloc(iint_cache, GFP_NOFS);
  98        if (!iint)
  99                return NULL;
 100
 101        write_lock(&integrity_iint_lock);
 102
 103        p = &integrity_iint_tree.rb_node;
 104        while (*p) {
 105                parent = *p;
 106                test_iint = rb_entry(parent, struct integrity_iint_cache,
 107                                     rb_node);
 108                if (inode < test_iint->inode)
 109                        p = &(*p)->rb_left;
 110                else
 111                        p = &(*p)->rb_right;
 112        }
 113
 114        iint->inode = inode;
 115        node = &iint->rb_node;
 116        inode->i_flags |= S_IMA;
 117        rb_link_node(node, parent, p);
 118        rb_insert_color(node, &integrity_iint_tree);
 119
 120        write_unlock(&integrity_iint_lock);
 121        return iint;
 122}
 123
 124/**
 125 * integrity_inode_free - called on security_inode_free
 126 * @inode: pointer to the inode
 127 *
 128 * Free the integrity information(iint) associated with an inode.
 129 */
 130void integrity_inode_free(struct inode *inode)
 131{
 132        struct integrity_iint_cache *iint;
 133
 134        if (!IS_IMA(inode))
 135                return;
 136
 137        write_lock(&integrity_iint_lock);
 138        iint = __integrity_iint_find(inode);
 139        rb_erase(&iint->rb_node, &integrity_iint_tree);
 140        write_unlock(&integrity_iint_lock);
 141
 142        iint_free(iint);
 143}
 144
 145static void init_once(void *foo)
 146{
 147        struct integrity_iint_cache *iint = foo;
 148
 149        memset(iint, 0, sizeof *iint);
 150        iint->version = 0;
 151        iint->flags = 0UL;
 152        iint->ima_status = INTEGRITY_UNKNOWN;
 153        iint->evm_status = INTEGRITY_UNKNOWN;
 154}
 155
 156static int __init integrity_iintcache_init(void)
 157{
 158        iint_cache =
 159            kmem_cache_create("iint_cache", sizeof(struct integrity_iint_cache),
 160                              0, SLAB_PANIC, init_once);
 161        iint_initialized = 1;
 162        return 0;
 163}
 164security_initcall(integrity_iintcache_init);
 165
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