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 <linux/file.h>
  23 #include <linux/uaccess.h>
  24 #include "integrity.h"
  25
  26 static struct rb_root integrity_iint_tree = RB_ROOT;
  27 static DEFINE_RWLOCK(integrity_iint_lock);
  28 static struct kmem_cache *iint_cache __read_mostly;
  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         kfree(iint->ima_hash);
  74         iint->ima_hash = NULL;
  75         iint->version = 0;
  76         iint->flags = 0UL;
  77         iint->atomic_flags = 0UL;
  78         iint->ima_file_status = INTEGRITY_UNKNOWN;
  79         iint->ima_mmap_status = INTEGRITY_UNKNOWN;
  80         iint->ima_bprm_status = INTEGRITY_UNKNOWN;
  81         iint->ima_read_status = INTEGRITY_UNKNOWN;
  82         iint->evm_status = INTEGRITY_UNKNOWN;
  83         iint->measured_pcrs = 0;
  84         kmem_cache_free(iint_cache, iint);
  85 }
  86
  87 /**
  88  * integrity_inode_get - find or allocate an iint associated with an inode
  89  * @inode: pointer to the inode
  90  * @return: allocated iint
  91  *
  92  * Caller must lock i_mutex
  93  */
  94 struct integrity_iint_cache *integrity_inode_get(struct inode *inode)
  95 {
  96         struct rb_node **p;
  97         struct rb_node *node, *parent = NULL;
  98         struct integrity_iint_cache *iint, *test_iint;
  99
 100         iint = integrity_iint_find(inode);
 101         if (iint)
 102                 return iint;
 103
 104         iint = kmem_cache_alloc(iint_cache, GFP_NOFS);
 105         if (!iint)
 106                 return NULL;
 107
 108         write_lock(&integrity_iint_lock);
 109
 110         p = &integrity_iint_tree.rb_node;
 111         while (*p) {
 112                 parent = *p;
 113                 test_iint = rb_entry(parent, struct integrity_iint_cache,
 114                                      rb_node);
 115                 if (inode < test_iint->inode)
 116                         p = &(*p)->rb_left;
 117                 else
 118                         p = &(*p)->rb_right;
 119         }
 120
 121         iint->inode = inode;
 122         node = &iint->rb_node;
 123         inode->i_flags |= S_IMA;
 124         rb_link_node(node, parent, p);
 125         rb_insert_color(node, &integrity_iint_tree);
 126
 127         write_unlock(&integrity_iint_lock);
 128         return iint;
 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         write_lock(&integrity_iint_lock);
 145         iint = __integrity_iint_find(inode);
 146         rb_erase(&iint->rb_node, &integrity_iint_tree);
 147         write_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->ima_file_status = INTEGRITY_UNKNOWN;
 158         iint->ima_mmap_status = INTEGRITY_UNKNOWN;
 159         iint->ima_bprm_status = INTEGRITY_UNKNOWN;
 160         iint->ima_read_status = INTEGRITY_UNKNOWN;
 161         iint->evm_status = INTEGRITY_UNKNOWN;
 162         mutex_init(&iint->mutex);
 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         return 0;
 171 }
 172 security_initcall(integrity_iintcache_init);
 173
 174
 175 /*
 176  * integrity_kernel_read - read data from the file
 177  *
 178  * This is a function for reading file content instead of kernel_read().
 179  * It does not perform locking checks to ensure it cannot be blocked.
 180  * It does not perform security checks because it is irrelevant for IMA.
 181  *
 182  */
 183 int integrity_kernel_read(struct file *file, loff_t offset,
 184                           void *addr, unsigned long count)
 185 {
 186         mm_segment_t old_fs;
 187         char __user *buf = (char __user *)addr;
 188         ssize_t ret;
 189
 190         if (!(file->f_mode & FMODE_READ))
 191                 return -EBADF;
 192
 193         old_fs = get_fs();
 194         set_fs(get_ds());
 195         ret = __vfs_read(file, buf, count, &offset);
 196         set_fs(old_fs);
 197
 198         return ret;
 199 }
 200
 201 /*
 202  * integrity_load_keys - load integrity keys hook
 203  *
 204  * Hooks is called from init/main.c:kernel_init_freeable()
 205  * when rootfs is ready
 206  */
 207 void __init integrity_load_keys(void)
 208 {
 209         ima_load_x509();
 210         evm_load_x509();
 211 }