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/init.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 <linux/lsm_hooks.h>
  26 #include "integrity.h"
  27
  28 static struct rb_root integrity_iint_tree = RB_ROOT;
  29 static DEFINE_RWLOCK(integrity_iint_lock);
  30 static struct kmem_cache *iint_cache __read_mostly;
  31
  32 struct dentry *integrity_dir;
  33
  34 /*
  35  * __integrity_iint_find - return the iint associated with an inode
  36  */
  37 static struct integrity_iint_cache *__integrity_iint_find(struct inode *inode)
  38 {
  39         struct integrity_iint_cache *iint;
  40         struct rb_node *n = integrity_iint_tree.rb_node;
  41
  42         while (n) {
  43                 iint = rb_entry(n, struct integrity_iint_cache, rb_node);
  44
  45                 if (inode < iint->inode)
  46                         n = n->rb_left;
  47                 else if (inode > iint->inode)
  48                         n = n->rb_right;
  49                 else
  50                         break;
  51         }
  52         if (!n)
  53                 return NULL;
  54
  55         return iint;
  56 }
  57
  58 /*
  59  * integrity_iint_find - return the iint associated with an inode
  60  */
  61 struct integrity_iint_cache *integrity_iint_find(struct inode *inode)
  62 {
  63         struct integrity_iint_cache *iint;
  64
  65         if (!IS_IMA(inode))
  66                 return NULL;
  67
  68         read_lock(&integrity_iint_lock);
  69         iint = __integrity_iint_find(inode);
  70         read_unlock(&integrity_iint_lock);
  71
  72         return iint;
  73 }
  74
  75 static void iint_free(struct integrity_iint_cache *iint)
  76 {
  77         kfree(iint->ima_hash);
  78         iint->ima_hash = NULL;
  79         iint->version = 0;
  80         iint->flags = 0UL;
  81         iint->atomic_flags = 0UL;
  82         iint->ima_file_status = INTEGRITY_UNKNOWN;
  83         iint->ima_mmap_status = INTEGRITY_UNKNOWN;
  84         iint->ima_bprm_status = INTEGRITY_UNKNOWN;
  85         iint->ima_read_status = INTEGRITY_UNKNOWN;
  86         iint->ima_creds_status = INTEGRITY_UNKNOWN;
  87         iint->evm_status = INTEGRITY_UNKNOWN;
  88         iint->measured_pcrs = 0;
  89         kmem_cache_free(iint_cache, iint);
  90 }
  91
  92 /**
  93  * integrity_inode_get - find or allocate an iint associated with an inode
  94  * @inode: pointer to the inode
  95  * @return: allocated iint
  96  *
  97  * Caller must lock i_mutex
  98  */
  99 struct integrity_iint_cache *integrity_inode_get(struct inode *inode)
 100 {
 101         struct rb_node **p;
 102         struct rb_node *node, *parent = NULL;
 103         struct integrity_iint_cache *iint, *test_iint;
 104
 105         iint = integrity_iint_find(inode);
 106         if (iint)
 107                 return iint;
 108
 109         iint = kmem_cache_alloc(iint_cache, GFP_NOFS);
 110         if (!iint)
 111                 return NULL;
 112
 113         write_lock(&integrity_iint_lock);
 114
 115         p = &integrity_iint_tree.rb_node;
 116         while (*p) {
 117                 parent = *p;
 118                 test_iint = rb_entry(parent, struct integrity_iint_cache,
 119                                      rb_node);
 120                 if (inode < test_iint->inode)
 121                         p = &(*p)->rb_left;
 122                 else
 123                         p = &(*p)->rb_right;
 124         }
 125
 126         iint->inode = inode;
 127         node = &iint->rb_node;
 128         inode->i_flags |= S_IMA;
 129         rb_link_node(node, parent, p);
 130         rb_insert_color(node, &integrity_iint_tree);
 131
 132         write_unlock(&integrity_iint_lock);
 133         return iint;
 134 }
 135
 136 /**
 137  * integrity_inode_free - called on security_inode_free
 138  * @inode: pointer to the inode
 139  *
 140  * Free the integrity information(iint) associated with an inode.
 141  */
 142 void integrity_inode_free(struct inode *inode)
 143 {
 144         struct integrity_iint_cache *iint;
 145
 146         if (!IS_IMA(inode))
 147                 return;
 148
 149         write_lock(&integrity_iint_lock);
 150         iint = __integrity_iint_find(inode);
 151         rb_erase(&iint->rb_node, &integrity_iint_tree);
 152         write_unlock(&integrity_iint_lock);
 153
 154         iint_free(iint);
 155 }
 156
 157 static void init_once(void *foo)
 158 {
 159         struct integrity_iint_cache *iint = foo;
 160
 161         memset(iint, 0, sizeof(*iint));
 162         iint->ima_file_status = INTEGRITY_UNKNOWN;
 163         iint->ima_mmap_status = INTEGRITY_UNKNOWN;
 164         iint->ima_bprm_status = INTEGRITY_UNKNOWN;
 165         iint->ima_read_status = INTEGRITY_UNKNOWN;
 166         iint->ima_creds_status = INTEGRITY_UNKNOWN;
 167         iint->evm_status = INTEGRITY_UNKNOWN;
 168         mutex_init(&iint->mutex);
 169 }
 170
 171 static int __init integrity_iintcache_init(void)
 172 {
 173         iint_cache =
 174             kmem_cache_create("iint_cache", sizeof(struct integrity_iint_cache),
 175                               0, SLAB_PANIC, init_once);
 176         return 0;
 177 }
 178 DEFINE_LSM(integrity) = {
 179         .name = "integrity",
 180         .init = integrity_iintcache_init,
 181 };
 182
 183
 184 /*
 185  * integrity_kernel_read - read data from the file
 186  *
 187  * This is a function for reading file content instead of kernel_read().
 188  * It does not perform locking checks to ensure it cannot be blocked.
 189  * It does not perform security checks because it is irrelevant for IMA.
 190  *
 191  */
 192 int integrity_kernel_read(struct file *file, loff_t offset,
 193                           void *addr, unsigned long count)
 194 {
 195         mm_segment_t old_fs;
 196         char __user *buf = (char __user *)addr;
 197         ssize_t ret;
 198
 199         if (!(file->f_mode & FMODE_READ))
 200                 return -EBADF;
 201
 202         old_fs = get_fs();
 203         set_fs(KERNEL_DS);
 204         ret = __vfs_read(file, buf, count, &offset);
 205         set_fs(old_fs);
 206
 207         return ret;
 208 }
 209
 210 /*
 211  * integrity_load_keys - load integrity keys hook
 212  *
 213  * Hooks is called from init/main.c:kernel_init_freeable()
 214  * when rootfs is ready
 215  */
 216 void __init integrity_load_keys(void)
 217 {
 218         ima_load_x509();
 219         evm_load_x509();
 220 }
 221
 222 static int __init integrity_fs_init(void)
 223 {
 224         integrity_dir = securityfs_create_dir("integrity", NULL);
 225         if (IS_ERR(integrity_dir)) {
 226                 int ret = PTR_ERR(integrity_dir);
 227
 228                 if (ret != -ENODEV)
 229                         pr_err("Unable to create integrity sysfs dir: %d\n",
 230                                ret);
 231                 integrity_dir = NULL;
 232                 return ret;
 233         }
 234
 235         return 0;
 236 }
 237
 238 late_initcall(integrity_fs_init)