security/integrity/ima/ima_iint.c

   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: ima_iint.c
  13  *      - implements the IMA hooks: ima_inode_alloc, ima_inode_free
  14  *      - cache integrity information associated with an inode
  15  *        using a radix tree.
  16  */
  17 #include <linux/module.h>
  18 #include <linux/spinlock.h>
  19 #include <linux/radix-tree.h>
  20 #include "ima.h"
  21
  22 RADIX_TREE(ima_iint_store, GFP_ATOMIC);
  23 DEFINE_SPINLOCK(ima_iint_lock);
  24
  25 static struct kmem_cache *iint_cache __read_mostly;
  26
  27 /* ima_iint_find_get - return the iint associated with an inode
  28  *
  29  * ima_iint_find_get gets a reference to the iint. Caller must
  30  * remember to put the iint reference.
  31  */
  32 struct ima_iint_cache *ima_iint_find_get(struct inode *inode)
  33 {
  34         struct ima_iint_cache *iint;
  35
  36         rcu_read_lock();
  37         iint = radix_tree_lookup(&ima_iint_store, (unsigned long)inode);
  38         if (!iint)
  39                 goto out;
  40         kref_get(&iint->refcount);
  41 out:
  42         rcu_read_unlock();
  43         return iint;
  44 }
  45
  46 /**
  47  * ima_inode_alloc - allocate an iint associated with an inode
  48  * @inode: pointer to the inode
  49  */
  50 int ima_inode_alloc(struct inode *inode)
  51 {
  52         struct ima_iint_cache *iint = NULL;
  53         int rc = 0;
  54
  55         iint = kmem_cache_alloc(iint_cache, GFP_NOFS);
  56         if (!iint)
  57                 return -ENOMEM;
  58
  59         rc = radix_tree_preload(GFP_NOFS);
  60         if (rc < 0)
  61                 goto out;
  62
  63         spin_lock(&ima_iint_lock);
  64         rc = radix_tree_insert(&ima_iint_store, (unsigned long)inode, iint);
  65         spin_unlock(&ima_iint_lock);
  66         radix_tree_preload_end();
  67 out:
  68         if (rc < 0)
  69                 kmem_cache_free(iint_cache, iint);
  70
  71         return rc;
  72 }
  73
  74 /* iint_free - called when the iint refcount goes to zero */
  75 void iint_free(struct kref *kref)
  76 {
  77         struct ima_iint_cache *iint = container_of(kref, struct ima_iint_cache,
  78                                                    refcount);
  79         iint->version = 0;
  80         iint->flags = 0UL;
  81         if (iint->readcount != 0) {
  82                 printk(KERN_INFO "%s: readcount: %ld\n", __FUNCTION__,
  83                        iint->readcount);
  84                 iint->readcount = 0;
  85         }
  86         if (iint->writecount != 0) {
  87                 printk(KERN_INFO "%s: writecount: %ld\n", __FUNCTION__,
  88                        iint->writecount);
  89                 iint->writecount = 0;
  90         }
  91         if (iint->opencount != 0) {
  92                 printk(KERN_INFO "%s: opencount: %ld\n", __FUNCTION__,
  93                        iint->opencount);
  94                 iint->opencount = 0;
  95         }
  96         kref_set(&iint->refcount, 1);
  97         kmem_cache_free(iint_cache, iint);
  98 }
  99
 100 void iint_rcu_free(struct rcu_head *rcu_head)
 101 {
 102         struct ima_iint_cache *iint = container_of(rcu_head,
 103                                                    struct ima_iint_cache, rcu);
 104         kref_put(&iint->refcount, iint_free);
 105 }
 106
 107 /**
 108  * ima_inode_free - called on security_inode_free
 109  * @inode: pointer to the inode
 110  *
 111  * Free the integrity information(iint) associated with an inode.
 112  */
 113 void ima_inode_free(struct inode *inode)
 114 {
 115         struct ima_iint_cache *iint;
 116
 117         spin_lock(&ima_iint_lock);
 118         iint = radix_tree_delete(&ima_iint_store, (unsigned long)inode);
 119         spin_unlock(&ima_iint_lock);
 120         if (iint)
 121                 call_rcu(&iint->rcu, iint_rcu_free);
 122 }
 123
 124 static void init_once(void *foo)
 125 {
 126         struct ima_iint_cache *iint = foo;
 127
 128         memset(iint, 0, sizeof *iint);
 129         iint->version = 0;
 130         iint->flags = 0UL;
 131         mutex_init(&iint->mutex);
 132         iint->readcount = 0;
 133         iint->writecount = 0;
 134         iint->opencount = 0;
 135         kref_set(&iint->refcount, 1);
 136 }
 137
 138 static int __init ima_iintcache_init(void)
 139 {
 140         iint_cache =
 141             kmem_cache_create("iint_cache", sizeof(struct ima_iint_cache), 0,
 142                               SLAB_PANIC, init_once);
 143         return 0;
 144 }
 145 security_initcall(ima_iintcache_init);