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->ima_file_status = INTEGRITY_UNKNOWN;
  78         iint->ima_mmap_status = INTEGRITY_UNKNOWN;
  79         iint->ima_bprm_status = INTEGRITY_UNKNOWN;
  80         iint->ima_read_status = INTEGRITY_UNKNOWN;
  81         iint->evm_status = INTEGRITY_UNKNOWN;
  82         iint->measured_pcrs = 0;
  83         kmem_cache_free(iint_cache, iint);
  84 }
  85
  86 /**
  87  * integrity_inode_get - find or allocate an iint associated with an inode
  88  * @inode: pointer to the inode
  89  * @return: allocated iint
  90  *
  91  * Caller must lock i_mutex
  92  */
  93 struct integrity_iint_cache *integrity_inode_get(struct inode *inode)
  94 {
  95         struct rb_node **p;
  96         struct rb_node *node, *parent = NULL;
  97         struct integrity_iint_cache *iint, *test_iint;
  98
  99         iint = integrity_iint_find(inode);
 100         if (iint)
 101                 return iint;
 102
 103         iint = kmem_cache_alloc(iint_cache, GFP_NOFS);
 104         if (!iint)
 105                 return NULL;
 106
 107         write_lock(&integrity_iint_lock);
 108
 109         p = &integrity_iint_tree.rb_node;
 110         while (*p) {
 111                 parent = *p;
 112                 test_iint = rb_entry(parent, struct integrity_iint_cache,
 113                                      rb_node);
 114                 if (inode < test_iint->inode)
 115                         p = &(*p)->rb_left;
 116                 else
 117                         p = &(*p)->rb_right;
 118         }
 119
 120         iint->inode = inode;
 121         node = &iint->rb_node;
 122         inode->i_flags |= S_IMA;
 123         rb_link_node(node, parent, p);
 124         rb_insert_color(node, &integrity_iint_tree);
 125
 126         write_unlock(&integrity_iint_lock);
 127         return iint;
 128 }
 129
 130 /**
 131  * integrity_inode_free - called on security_inode_free
 132  * @inode: pointer to the inode
 133  *
 134  * Free the integrity information(iint) associated with an inode.
 135  */
 136 void integrity_inode_free(struct inode *inode)
 137 {
 138         struct integrity_iint_cache *iint;
 139
 140         if (!IS_IMA(inode))
 141                 return;
 142
 143         write_lock(&integrity_iint_lock);
 144         iint = __integrity_iint_find(inode);
 145         rb_erase(&iint->rb_node, &integrity_iint_tree);
 146         write_unlock(&integrity_iint_lock);
 147
 148         iint_free(iint);
 149 }
 150
 151 static void init_once(void *foo)
 152 {
 153         struct integrity_iint_cache *iint = foo;
 154
 155         memset(iint, 0, sizeof(*iint));
 156         iint->version = 0;
 157         iint->flags = 0UL;
 158         iint->ima_file_status = INTEGRITY_UNKNOWN;
 159         iint->ima_mmap_status = INTEGRITY_UNKNOWN;
 160         iint->ima_bprm_status = INTEGRITY_UNKNOWN;
 161         iint->ima_read_status = INTEGRITY_UNKNOWN;
 162         iint->evm_status = INTEGRITY_UNKNOWN;
 163         iint->measured_pcrs = 0;
 164 }
 165
 166 static int __init integrity_iintcache_init(void)
 167 {
 168         iint_cache =
 169             kmem_cache_create("iint_cache", sizeof(struct integrity_iint_cache),
 170                               0, SLAB_PANIC, init_once);
 171         return 0;
 172 }
 173 security_initcall(integrity_iintcache_init);
 174
 175
 176 /*
 177  * integrity_kernel_read - read data from the file
 178  *
 179  * This is a function for reading file content instead of kernel_read().
 180  * It does not perform locking checks to ensure it cannot be blocked.
 181  * It does not perform security checks because it is irrelevant for IMA.
 182  *
 183  */
 184 int integrity_kernel_read(struct file *file, loff_t offset,
 185                           void *addr, unsigned long count)
 186 {
 187         mm_segment_t old_fs;
 188         char __user *buf = (char __user *)addr;
 189         ssize_t ret;
 190
 191         if (!(file->f_mode & FMODE_READ))
 192                 return -EBADF;
 193
 194         old_fs = get_fs();
 195         set_fs(get_ds());
 196         ret = __vfs_read(file, buf, count, &offset);
 197         set_fs(old_fs);
 198
 199         return ret;
 200 }
 201
 202 /*
 203  * integrity_read_file - read entire file content into the buffer
 204  *
 205  * This is function opens a file, allocates the buffer of required
 206  * size, read entire file content to the buffer and closes the file
 207  *
 208  * It is used only by init code.
 209  *
 210  */
 211 int __init integrity_read_file(const char *path, char **data)
 212 {
 213         struct file *file;
 214         loff_t size;
 215         char *buf;
 216         int rc = -EINVAL;
 217
 218         if (!path || !*path)
 219                 return -EINVAL;
 220
 221         file = filp_open(path, O_RDONLY, 0);
 222         if (IS_ERR(file)) {
 223                 rc = PTR_ERR(file);
 224                 pr_err("Unable to open file: %s (%d)", path, rc);
 225                 return rc;
 226         }
 227
 228         size = i_size_read(file_inode(file));
 229         if (size <= 0)
 230                 goto out;
 231
 232         buf = kmalloc(size, GFP_KERNEL);
 233         if (!buf) {
 234                 rc = -ENOMEM;
 235                 goto out;
 236         }
 237
 238         rc = integrity_kernel_read(file, 0, buf, size);
 239         if (rc == size) {
 240                 *data = buf;
 241         } else {
 242                 kfree(buf);
 243                 if (rc >= 0)
 244                         rc = -EIO;
 245         }
 246 out:
 247         fput(file);
 248         return rc;
 249 }
 250
 251 /*
 252  * integrity_load_keys - load integrity keys hook
 253  *
 254  * Hooks is called from init/main.c:kernel_init_freeable()
 255  * when rootfs is ready
 256  */
 257 void __init integrity_load_keys(void)
 258 {
 259         ima_load_x509();
 260         evm_load_x509();
 261 }