security/integrity/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: 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
  24 static struct rb_root integrity_iint_tree = RB_ROOT;
  25 static DEFINE_SPINLOCK(integrity_iint_lock);
  26 static struct kmem_cache *iint_cache __read_mostly;
  27
  28 int iint_initialized;
  29
  30 /*
  31  * __integrity_iint_find - return the iint associated with an inode
  32  */
  33 static 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         assert_spin_locked(&integrity_iint_lock);
  39
  40         while (n) {
  41                 iint = rb_entry(n, struct integrity_iint_cache, rb_node);
  42
  43                 if (inode < iint->inode)
  44                         n = n->rb_left;
  45                 else if (inode > iint->inode)
  46                         n = n->rb_right;
  47                 else
  48                         break;
  49         }
  50         if (!n)
  51                 return NULL;
  52
  53         return iint;
  54 }
  55
  56 /*
  57  * integrity_iint_find - return the iint associated with an inode
  58  */
  59 struct integrity_iint_cache *integrity_iint_find(struct inode *inode)
  60 {
  61         struct integrity_iint_cache *iint;
  62
  63         if (!IS_IMA(inode))
  64                 return NULL;
  65
  66         spin_lock(&integrity_iint_lock);
  67         iint = __integrity_iint_find(inode);
  68         spin_unlock(&integrity_iint_lock);
  69
  70         return iint;
  71 }
  72
  73 static void iint_free(struct integrity_iint_cache *iint)
  74 {
  75         iint->version = 0;
  76         iint->flags = 0UL;
  77         kmem_cache_free(iint_cache, iint);
  78 }
  79
  80 /**
  81  * integrity_inode_alloc - allocate an iint associated with an inode
  82  * @inode: pointer to the inode
  83  */
  84 int integrity_inode_alloc(struct inode *inode)
  85 {
  86         struct rb_node **p;
  87         struct rb_node *new_node, *parent = NULL;
  88         struct integrity_iint_cache *new_iint, *test_iint;
  89         int rc;
  90
  91         new_iint = kmem_cache_alloc(iint_cache, GFP_NOFS);
  92         if (!new_iint)
  93                 return -ENOMEM;
  94
  95         new_iint->inode = inode;
  96         new_node = &new_iint->rb_node;
  97
  98         mutex_lock(&inode->i_mutex);    /* i_flags */
  99         spin_lock(&integrity_iint_lock);
 100
 101         p = &integrity_iint_tree.rb_node;
 102         while (*p) {
 103                 parent = *p;
 104                 test_iint = rb_entry(parent, struct integrity_iint_cache,
 105                                      rb_node);
 106                 rc = -EEXIST;
 107                 if (inode < test_iint->inode)
 108                         p = &(*p)->rb_left;
 109                 else if (inode > test_iint->inode)
 110                         p = &(*p)->rb_right;
 111                 else
 112                         goto out_err;
 113         }
 114
 115         inode->i_flags |= S_IMA;
 116         rb_link_node(new_node, parent, p);
 117         rb_insert_color(new_node, &integrity_iint_tree);
 118
 119         spin_unlock(&integrity_iint_lock);
 120         mutex_unlock(&inode->i_mutex);  /* i_flags */
 121
 122         return 0;
 123 out_err:
 124         spin_unlock(&integrity_iint_lock);
 125         mutex_unlock(&inode->i_mutex);  /* i_flags */
 126         iint_free(new_iint);
 127
 128         return rc;
 129 }
 130
 131 /**
 132  * integrity_inode_free - called on security_inode_free
 133  * @inode: pointer to the inode
 134  *
 135  * Free the integrity information(iint) associated with an inode.
 136  */
 137 void integrity_inode_free(struct inode *inode)
 138 {
 139         struct integrity_iint_cache *iint;
 140
 141         if (!IS_IMA(inode))
 142                 return;
 143
 144         spin_lock(&integrity_iint_lock);
 145         iint = __integrity_iint_find(inode);
 146         rb_erase(&iint->rb_node, &integrity_iint_tree);
 147         spin_unlock(&integrity_iint_lock);
 148
 149         iint_free(iint);
 150 }
 151
 152 static void init_once(void *foo)
 153 {
 154         struct integrity_iint_cache *iint = foo;
 155
 156         memset(iint, 0, sizeof *iint);
 157         iint->version = 0;
 158         iint->flags = 0UL;
 159         mutex_init(&iint->mutex);
 160         iint->evm_status = INTEGRITY_UNKNOWN;
 161 }
 162
 163 static int __init integrity_iintcache_init(void)
 164 {
 165         iint_cache =
 166             kmem_cache_create("iint_cache", sizeof(struct integrity_iint_cache),
 167                               0, SLAB_PANIC, init_once);
 168         iint_initialized = 1;
 169         return 0;
 170 }
 171 security_initcall(integrity_iintcache_init);