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         iint->ima_status = INTEGRITY_UNKNOWN;
  78         iint->evm_status = INTEGRITY_UNKNOWN;
  79         kmem_cache_free(iint_cache, iint);
  80 }
  81
  82 /**
  83  * integrity_inode_alloc - allocate an iint associated with an inode
  84  * @inode: pointer to the inode
  85  */
  86 int integrity_inode_alloc(struct inode *inode)
  87 {
  88         struct rb_node **p;
  89         struct rb_node *new_node, *parent = NULL;
  90         struct integrity_iint_cache *new_iint, *test_iint;
  91         int rc;
  92
  93         new_iint = kmem_cache_alloc(iint_cache, GFP_NOFS);
  94         if (!new_iint)
  95                 return -ENOMEM;
  96
  97         new_iint->inode = inode;
  98         new_node = &new_iint->rb_node;
  99
 100         mutex_lock(&inode->i_mutex);    /* i_flags */
 101         spin_lock(&integrity_iint_lock);
 102
 103         p = &integrity_iint_tree.rb_node;
 104         while (*p) {
 105                 parent = *p;
 106                 test_iint = rb_entry(parent, struct integrity_iint_cache,
 107                                      rb_node);
 108                 rc = -EEXIST;
 109                 if (inode < test_iint->inode)
 110                         p = &(*p)->rb_left;
 111                 else if (inode > test_iint->inode)
 112                         p = &(*p)->rb_right;
 113                 else
 114                         goto out_err;
 115         }
 116
 117         inode->i_flags |= S_IMA;
 118         rb_link_node(new_node, parent, p);
 119         rb_insert_color(new_node, &integrity_iint_tree);
 120
 121         spin_unlock(&integrity_iint_lock);
 122         mutex_unlock(&inode->i_mutex);  /* i_flags */
 123
 124         return 0;
 125 out_err:
 126         spin_unlock(&integrity_iint_lock);
 127         mutex_unlock(&inode->i_mutex);  /* i_flags */
 128         iint_free(new_iint);
 129
 130         return rc;
 131 }
 132
 133 /**
 134  * integrity_inode_free - called on security_inode_free
 135  * @inode: pointer to the inode
 136  *
 137  * Free the integrity information(iint) associated with an inode.
 138  */
 139 void integrity_inode_free(struct inode *inode)
 140 {
 141         struct integrity_iint_cache *iint;
 142
 143         if (!IS_IMA(inode))
 144                 return;
 145
 146         spin_lock(&integrity_iint_lock);
 147         iint = __integrity_iint_find(inode);
 148         rb_erase(&iint->rb_node, &integrity_iint_tree);
 149         spin_unlock(&integrity_iint_lock);
 150
 151         iint_free(iint);
 152 }
 153
 154 static void init_once(void *foo)
 155 {
 156         struct integrity_iint_cache *iint = foo;
 157
 158         memset(iint, 0, sizeof *iint);
 159         iint->version = 0;
 160         iint->flags = 0UL;
 161         iint->ima_status = INTEGRITY_UNKNOWN;
 162         iint->evm_status = INTEGRITY_UNKNOWN;
 163 }
 164
 165 static int __init integrity_iintcache_init(void)
 166 {
 167         iint_cache =
 168             kmem_cache_create("iint_cache", sizeof(struct integrity_iint_cache),
 169                               0, SLAB_PANIC, init_once);
 170         iint_initialized = 1;
 171         return 0;
 172 }
 173 security_initcall(integrity_iintcache_init);