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 #define ima_iint_delete ima_inode_free
  23
  24 RADIX_TREE(ima_iint_store, GFP_ATOMIC);
  25 DEFINE_SPINLOCK(ima_iint_lock);
  26
  27 static struct kmem_cache *iint_cache __read_mostly;
  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 /* Allocate memory for the iint associated with the inode
  49  * from the iint_cache slab, initialize the iint, and
  50  * insert it into the radix tree.
  51  *
  52  * On success return a pointer to the iint; on failure return NULL.
  53  */
  54 struct ima_iint_cache *ima_iint_insert(struct inode *inode)
  55 {
  56         struct ima_iint_cache *iint = NULL;
  57         int rc = 0;
  58
  59         if (!ima_initialized)
  60                 return iint;
  61         iint = kmem_cache_alloc(iint_cache, GFP_KERNEL);
  62         if (!iint)
  63                 return iint;
  64
  65         rc = radix_tree_preload(GFP_KERNEL);
  66         if (rc < 0)
  67                 goto out;
  68
  69         spin_lock(&ima_iint_lock);
  70         rc = radix_tree_insert(&ima_iint_store, (unsigned long)inode, iint);
  71         spin_unlock(&ima_iint_lock);
  72 out:
  73         if (rc < 0) {
  74                 kmem_cache_free(iint_cache, iint);
  75                 if (rc == -EEXIST) {
  76                         iint = radix_tree_lookup(&ima_iint_store,
  77                                                  (unsigned long)inode);
  78                 } else
  79                         iint = NULL;
  80         }
  81         radix_tree_preload_end();
  82         return iint;
  83 }
  84
  85 /**
  86  * ima_inode_alloc - allocate an iint associated with an inode
  87  * @inode: pointer to the inode
  88  *
  89  * Return 0 on success, 1 on failure.
  90  */
  91 int ima_inode_alloc(struct inode *inode)
  92 {
  93         struct ima_iint_cache *iint;
  94
  95         if (!ima_initialized)
  96                 return 0;
  97
  98         iint = ima_iint_insert(inode);
  99         if (!iint)
 100                 return 1;
 101         return 0;
 102 }
 103
 104 /* ima_iint_find_insert_get - get the iint associated with an inode
 105  *
 106  * Most insertions are done at inode_alloc, except those allocated
 107  * before late_initcall. When the iint does not exist, allocate it,
 108  * initialize and insert it, and increment the iint refcount.
 109  *
 110  * (Can't initialize at security_initcall before any inodes are
 111  * allocated, got to wait at least until proc_init.)
 112  *
 113  *  Return the iint.
 114  */
 115 struct ima_iint_cache *ima_iint_find_insert_get(struct inode *inode)
 116 {
 117         struct ima_iint_cache *iint = NULL;
 118
 119         iint = ima_iint_find_get(inode);
 120         if (iint)
 121                 return iint;
 122
 123         iint = ima_iint_insert(inode);
 124         if (iint)
 125                 kref_get(&iint->refcount);
 126
 127         return iint;
 128 }
 129 EXPORT_SYMBOL_GPL(ima_iint_find_insert_get);
 130
 131 /* iint_free - called when the iint refcount goes to zero */
 132 void iint_free(struct kref *kref)
 133 {
 134         struct ima_iint_cache *iint = container_of(kref, struct ima_iint_cache,
 135                                                    refcount);
 136         iint->version = 0;
 137         iint->flags = 0UL;
 138         if (iint->readcount != 0) {
 139                 printk(KERN_INFO "%s: readcount: %ld\n", __FUNCTION__,
 140                        iint->readcount);
 141                 iint->readcount = 0;
 142         }
 143         if (iint->writecount != 0) {
 144                 printk(KERN_INFO "%s: writecount: %ld\n", __FUNCTION__,
 145                        iint->writecount);
 146                 iint->writecount = 0;
 147         }
 148         if (iint->opencount != 0) {
 149                 printk(KERN_INFO "%s: opencount: %ld\n", __FUNCTION__,
 150                        iint->opencount);
 151                 iint->opencount = 0;
 152         }
 153         kref_set(&iint->refcount, 1);
 154         kmem_cache_free(iint_cache, iint);
 155 }
 156
 157 void iint_rcu_free(struct rcu_head *rcu_head)
 158 {
 159         struct ima_iint_cache *iint = container_of(rcu_head,
 160                                                    struct ima_iint_cache, rcu);
 161         kref_put(&iint->refcount, iint_free);
 162 }
 163
 164 /**
 165  * ima_iint_delete - called on integrity_inode_free
 166  * @inode: pointer to the inode
 167  *
 168  * Free the integrity information(iint) associated with an inode.
 169  */
 170 void ima_iint_delete(struct inode *inode)
 171 {
 172         struct ima_iint_cache *iint;
 173
 174         if (!ima_initialized)
 175                 return;
 176         spin_lock(&ima_iint_lock);
 177         iint = radix_tree_delete(&ima_iint_store, (unsigned long)inode);
 178         spin_unlock(&ima_iint_lock);
 179         if (iint)
 180                 call_rcu(&iint->rcu, iint_rcu_free);
 181 }
 182
 183 static void init_once(void *foo)
 184 {
 185         struct ima_iint_cache *iint = foo;
 186
 187         memset(iint, 0, sizeof *iint);
 188         iint->version = 0;
 189         iint->flags = 0UL;
 190         mutex_init(&iint->mutex);
 191         iint->readcount = 0;
 192         iint->writecount = 0;
 193         iint->opencount = 0;
 194         kref_set(&iint->refcount, 1);
 195 }
 196
 197 void ima_iintcache_init(void)
 198 {
 199         iint_cache =
 200             kmem_cache_create("iint_cache", sizeof(struct ima_iint_cache), 0,
 201                               SLAB_PANIC, init_once);
 202 }