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_RWLOCK(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         while (n) {
  39                 iint = rb_entry(n, struct integrity_iint_cache, rb_node);
  40
  41                 if (inode < iint->inode)
  42                         n = n->rb_left;
  43                 else if (inode > iint->inode)
  44                         n = n->rb_right;
  45                 else
  46                         break;
  47         }
  48         if (!n)
  49                 return NULL;
  50
  51         return iint;
  52 }
  53
  54 /*
  55  * integrity_iint_find - return the iint associated with an inode
  56  */
  57 struct integrity_iint_cache *integrity_iint_find(struct inode *inode)
  58 {
  59         struct integrity_iint_cache *iint;
  60
  61         if (!IS_IMA(inode))
  62                 return NULL;
  63
  64         read_lock(&integrity_iint_lock);
  65         iint = __integrity_iint_find(inode);
  66         read_unlock(&integrity_iint_lock);
  67
  68         return iint;
  69 }
  70
  71 static void iint_free(struct integrity_iint_cache *iint)
  72 {
  73         iint->version = 0;
  74         iint->flags = 0UL;
  75         iint->ima_status = INTEGRITY_UNKNOWN;
  76         iint->evm_status = INTEGRITY_UNKNOWN;
  77         kmem_cache_free(iint_cache, iint);
  78 }
  79
  80 /**
  81  * integrity_inode_get - find or allocate an iint associated with an inode
  82  * @inode: pointer to the inode
  83  * @return: allocated iint
  84  *
  85  * Caller must lock i_mutex
  86  */
  87 struct integrity_iint_cache *integrity_inode_get(struct inode *inode)
  88 {
  89         struct rb_node **p;
  90         struct rb_node *node, *parent = NULL;
  91         struct integrity_iint_cache *iint, *test_iint;
  92
  93         iint = integrity_iint_find(inode);
  94         if (iint)
  95                 return iint;
  96
  97         iint = kmem_cache_alloc(iint_cache, GFP_NOFS);
  98         if (!iint)
  99                 return NULL;
 100
 101         write_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                 if (inode < test_iint->inode)
 109                         p = &(*p)->rb_left;
 110                 else
 111                         p = &(*p)->rb_right;
 112         }
 113
 114         iint->inode = inode;
 115         node = &iint->rb_node;
 116         inode->i_flags |= S_IMA;
 117         rb_link_node(node, parent, p);
 118         rb_insert_color(node, &integrity_iint_tree);
 119
 120         write_unlock(&integrity_iint_lock);
 121         return iint;
 122 }
 123
 124 /**
 125  * integrity_inode_free - called on security_inode_free
 126  * @inode: pointer to the inode
 127  *
 128  * Free the integrity information(iint) associated with an inode.
 129  */
 130 void integrity_inode_free(struct inode *inode)
 131 {
 132         struct integrity_iint_cache *iint;
 133
 134         if (!IS_IMA(inode))
 135                 return;
 136
 137         write_lock(&integrity_iint_lock);
 138         iint = __integrity_iint_find(inode);
 139         rb_erase(&iint->rb_node, &integrity_iint_tree);
 140         write_unlock(&integrity_iint_lock);
 141
 142         iint_free(iint);
 143 }
 144
 145 static void init_once(void *foo)
 146 {
 147         struct integrity_iint_cache *iint = foo;
 148
 149         memset(iint, 0, sizeof *iint);
 150         iint->version = 0;
 151         iint->flags = 0UL;
 152         iint->ima_status = INTEGRITY_UNKNOWN;
 153         iint->evm_status = INTEGRITY_UNKNOWN;
 154 }
 155
 156 static int __init integrity_iintcache_init(void)
 157 {
 158         iint_cache =
 159             kmem_cache_create("iint_cache", sizeof(struct integrity_iint_cache),
 160                               0, SLAB_PANIC, init_once);
 161         iint_initialized = 1;
 162         return 0;
 163 }
 164 security_initcall(integrity_iintcache_init);