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/slab.h>
  18 #include <linux/module.h>
  19 #include <linux/spinlock.h>
  20 #include <linux/radix-tree.h>
  21 #include "ima.h"
  22
  23 RADIX_TREE(ima_iint_store, GFP_ATOMIC);
  24 DEFINE_SPINLOCK(ima_iint_lock);
  25 static struct kmem_cache *iint_cache __read_mostly;
  26
  27 int iint_initialized = 0;
  28
  29 /* ima_iint_find_get - return the iint associated with an inode
  30  *
  31  * ima_iint_find_get gets a reference to the iint. Caller must
  32  * remember to put the iint reference.
  33  */
  34 struct ima_iint_cache *ima_iint_find_get(struct inode *inode)
  35 {
  36         struct ima_iint_cache *iint;
  37
  38         rcu_read_lock();
  39         iint = radix_tree_lookup(&ima_iint_store, (unsigned long)inode);
  40         if (!iint)
  41                 goto out;
  42         kref_get(&iint->refcount);
  43 out:
  44         rcu_read_unlock();
  45         return iint;
  46 }
  47
  48 /**
  49  * ima_inode_alloc - allocate an iint associated with an inode
  50  * @inode: pointer to the inode
  51  */
  52 int ima_inode_alloc(struct inode *inode)
  53 {
  54         struct ima_iint_cache *iint = NULL;
  55         int rc = 0;
  56
  57         iint = kmem_cache_alloc(iint_cache, GFP_NOFS);
  58         if (!iint)
  59                 return -ENOMEM;
  60
  61         rc = radix_tree_preload(GFP_NOFS);
  62         if (rc < 0)
  63                 goto out;
  64
  65         spin_lock(&ima_iint_lock);
  66         rc = radix_tree_insert(&ima_iint_store, (unsigned long)inode, iint);
  67         spin_unlock(&ima_iint_lock);
  68         radix_tree_preload_end();
  69 out:
  70         if (rc < 0)
  71                 kmem_cache_free(iint_cache, iint);
  72
  73         return rc;
  74 }
  75
  76 /* iint_free - called when the iint refcount goes to zero */
  77 void iint_free(struct kref *kref)
  78 {
  79         struct ima_iint_cache *iint = container_of(kref, struct ima_iint_cache,
  80                                                    refcount);
  81         iint->version = 0;
  82         iint->flags = 0UL;
  83         if (iint->readcount != 0) {
  84                 printk(KERN_INFO "%s: readcount: %ld\n", __func__,
  85                        iint->readcount);
  86                 iint->readcount = 0;
  87         }
  88         if (iint->writecount != 0) {
  89                 printk(KERN_INFO "%s: writecount: %ld\n", __func__,
  90                        iint->writecount);
  91                 iint->writecount = 0;
  92         }
  93         if (iint->opencount != 0) {
  94                 printk(KERN_INFO "%s: opencount: %ld\n", __func__,
  95                        iint->opencount);
  96                 iint->opencount = 0;
  97         }
  98         kref_init(&iint->refcount);
  99         kmem_cache_free(iint_cache, iint);
 100 }
 101
 102 void iint_rcu_free(struct rcu_head *rcu_head)
 103 {
 104         struct ima_iint_cache *iint = container_of(rcu_head,
 105                                                    struct ima_iint_cache, rcu);
 106         kref_put(&iint->refcount, iint_free);
 107 }
 108
 109 /**
 110  * ima_inode_free - called on security_inode_free
 111  * @inode: pointer to the inode
 112  *
 113  * Free the integrity information(iint) associated with an inode.
 114  */
 115 void ima_inode_free(struct inode *inode)
 116 {
 117         struct ima_iint_cache *iint;
 118
 119         spin_lock(&ima_iint_lock);
 120         iint = radix_tree_delete(&ima_iint_store, (unsigned long)inode);
 121         spin_unlock(&ima_iint_lock);
 122         if (iint)
 123                 call_rcu(&iint->rcu, iint_rcu_free);
 124 }
 125
 126 static void init_once(void *foo)
 127 {
 128         struct ima_iint_cache *iint = foo;
 129
 130         memset(iint, 0, sizeof *iint);
 131         iint->version = 0;
 132         iint->flags = 0UL;
 133         mutex_init(&iint->mutex);
 134         iint->readcount = 0;
 135         iint->writecount = 0;
 136         iint->opencount = 0;
 137         kref_init(&iint->refcount);
 138 }
 139
 140 static int __init ima_iintcache_init(void)
 141 {
 142         iint_cache =
 143             kmem_cache_create("iint_cache", sizeof(struct ima_iint_cache), 0,
 144                               SLAB_PANIC, init_once);
 145         iint_initialized = 1;
 146         return 0;
 147 }
 148 security_initcall(ima_iintcache_init);