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 <linux/security.h>
  25 #include "integrity.h"
  26
  27 static struct rb_root integrity_iint_tree = RB_ROOT;
  28 static DEFINE_RWLOCK(integrity_iint_lock);
  29 static struct kmem_cache *iint_cache __read_mostly;
  30
  31 struct dentry *integrity_dir;
  32
  33 /*
  34  * __integrity_iint_find - return the iint associated with an inode
  35  */
  36 static struct integrity_iint_cache *__integrity_iint_find(struct inode *inode)
  37 {
  38         struct integrity_iint_cache *iint;
  39         struct rb_node *n = integrity_iint_tree.rb_node;
  40
  41         while (n) {
  42                 iint = rb_entry(n, struct integrity_iint_cache, rb_node);
  43
  44                 if (inode < iint->inode)
  45                         n = n->rb_left;
  46                 else if (inode > iint->inode)
  47                         n = n->rb_right;
  48                 else
  49                         break;
  50         }
  51         if (!n)
  52                 return NULL;
  53
  54         return iint;
  55 }
  56
  57 /*
  58  * integrity_iint_find - return the iint associated with an inode
  59  */
  60 struct integrity_iint_cache *integrity_iint_find(struct inode *inode)
  61 {
  62         struct integrity_iint_cache *iint;
  63
  64         if (!IS_IMA(inode))
  65                 return NULL;
  66
  67         read_lock(&integrity_iint_lock);
  68         iint = __integrity_iint_find(inode);
  69         read_unlock(&integrity_iint_lock);
  70
  71         return iint;
  72 }
  73
  74 static void iint_free(struct integrity_iint_cache *iint)
  75 {
  76         kfree(iint->ima_hash);
  77         iint->ima_hash = NULL;
  78         iint->version = 0;
  79         iint->flags = 0UL;
  80         iint->atomic_flags = 0UL;
  81         iint->ima_file_status = INTEGRITY_UNKNOWN;
  82         iint->ima_mmap_status = INTEGRITY_UNKNOWN;
  83         iint->ima_bprm_status = INTEGRITY_UNKNOWN;
  84         iint->ima_read_status = INTEGRITY_UNKNOWN;
  85         iint->ima_creds_status = INTEGRITY_UNKNOWN;
  86         iint->evm_status = INTEGRITY_UNKNOWN;
  87         iint->measured_pcrs = 0;
  88         kmem_cache_free(iint_cache, iint);
  89 }
  90
  91 /**
  92  * integrity_inode_get - find or allocate an iint associated with an inode
  93  * @inode: pointer to the inode
  94  * @return: allocated iint
  95  *
  96  * Caller must lock i_mutex
  97  */
  98 struct integrity_iint_cache *integrity_inode_get(struct inode *inode)
  99 {
 100         struct rb_node **p;
 101         struct rb_node *node, *parent = NULL;
 102         struct integrity_iint_cache *iint, *test_iint;
 103
 104         iint = integrity_iint_find(inode);
 105         if (iint)
 106                 return iint;
 107
 108         iint = kmem_cache_alloc(iint_cache, GFP_NOFS);
 109         if (!iint)
 110                 return NULL;
 111
 112         write_lock(&integrity_iint_lock);
 113
 114         p = &integrity_iint_tree.rb_node;
 115         while (*p) {
 116                 parent = *p;
 117                 test_iint = rb_entry(parent, struct integrity_iint_cache,
 118                                      rb_node);
 119                 if (inode < test_iint->inode)
 120                         p = &(*p)->rb_left;
 121                 else
 122                         p = &(*p)->rb_right;
 123         }
 124
 125         iint->inode = inode;
 126         node = &iint->rb_node;
 127         inode->i_flags |= S_IMA;
 128         rb_link_node(node, parent, p);
 129         rb_insert_color(node, &integrity_iint_tree);
 130
 131         write_unlock(&integrity_iint_lock);
 132         return iint;
 133 }
 134
 135 /**
 136  * integrity_inode_free - called on security_inode_free
 137  * @inode: pointer to the inode
 138  *
 139  * Free the integrity information(iint) associated with an inode.
 140  */
 141 void integrity_inode_free(struct inode *inode)
 142 {
 143         struct integrity_iint_cache *iint;
 144
 145         if (!IS_IMA(inode))
 146                 return;
 147
 148         write_lock(&integrity_iint_lock);
 149         iint = __integrity_iint_find(inode);
 150         rb_erase(&iint->rb_node, &integrity_iint_tree);
 151         write_unlock(&integrity_iint_lock);
 152
 153         iint_free(iint);
 154 }
 155
 156 static void init_once(void *foo)
 157 {
 158         struct integrity_iint_cache *iint = foo;
 159
 160         memset(iint, 0, sizeof(*iint));
 161         iint->ima_file_status = INTEGRITY_UNKNOWN;
 162         iint->ima_mmap_status = INTEGRITY_UNKNOWN;
 163         iint->ima_bprm_status = INTEGRITY_UNKNOWN;
 164         iint->ima_read_status = INTEGRITY_UNKNOWN;
 165         iint->ima_creds_status = INTEGRITY_UNKNOWN;
 166         iint->evm_status = INTEGRITY_UNKNOWN;
 167         mutex_init(&iint->mutex);
 168 }
 169
 170 static int __init integrity_iintcache_init(void)
 171 {
 172         iint_cache =
 173             kmem_cache_create("iint_cache", sizeof(struct integrity_iint_cache),
 174                               0, SLAB_PANIC, init_once);
 175         return 0;
 176 }
 177 security_initcall(integrity_iintcache_init);
 178
 179
 180 /*
 181  * integrity_kernel_read - read data from the file
 182  *
 183  * This is a function for reading file content instead of kernel_read().
 184  * It does not perform locking checks to ensure it cannot be blocked.
 185  * It does not perform security checks because it is irrelevant for IMA.
 186  *
 187  */
 188 int integrity_kernel_read(struct file *file, loff_t offset,
 189                           void *addr, unsigned long count)
 190 {
 191         mm_segment_t old_fs;
 192         char __user *buf = (char __user *)addr;
 193         ssize_t ret;
 194
 195         if (!(file->f_mode & FMODE_READ))
 196                 return -EBADF;
 197
 198         old_fs = get_fs();
 199         set_fs(get_ds());
 200         ret = __vfs_read(file, buf, count, &offset);
 201         set_fs(old_fs);
 202
 203         return ret;
 204 }
 205
 206 /*
 207  * integrity_load_keys - load integrity keys hook
 208  *
 209  * Hooks is called from init/main.c:kernel_init_freeable()
 210  * when rootfs is ready
 211  */
 212 void __init integrity_load_keys(void)
 213 {
 214         ima_load_x509();
 215         evm_load_x509();
 216 }
 217
 218 static int __init integrity_fs_init(void)
 219 {
 220         integrity_dir = securityfs_create_dir("integrity", NULL);
 221         if (IS_ERR(integrity_dir)) {
 222                 int ret = PTR_ERR(integrity_dir);
 223
 224                 if (ret != -ENODEV)
 225                         pr_err("Unable to create integrity sysfs dir: %d\n",
 226                                ret);
 227                 integrity_dir = NULL;
 228                 return ret;
 229         }
 230
 231         return 0;
 232 }
 233
 234 late_initcall(integrity_fs_init)