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