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