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                         return iint;
  47         }
  48
  49         return NULL;
  50 }
  51
  52 /*
  53  * integrity_iint_find - return the iint associated with an inode
  54  */
  55 struct integrity_iint_cache *integrity_iint_find(struct inode *inode)
  56 {
  57         struct integrity_iint_cache *iint;
  58
  59         if (!IS_IMA(inode))
  60                 return NULL;
  61
  62         read_lock(&integrity_iint_lock);
  63         iint = __integrity_iint_find(inode);
  64         read_unlock(&integrity_iint_lock);
  65
  66         return iint;
  67 }
  68
  69 static void iint_free(struct integrity_iint_cache *iint)
  70 {
  71         kfree(iint->ima_hash);
  72         iint->ima_hash = NULL;
  73         iint->version = 0;
  74         iint->flags = 0UL;
  75         iint->atomic_flags = 0UL;
  76         iint->ima_file_status = INTEGRITY_UNKNOWN;
  77         iint->ima_mmap_status = INTEGRITY_UNKNOWN;
  78         iint->ima_bprm_status = INTEGRITY_UNKNOWN;
  79         iint->ima_read_status = INTEGRITY_UNKNOWN;
  80         iint->evm_status = INTEGRITY_UNKNOWN;
  81         iint->measured_pcrs = 0;
  82         kmem_cache_free(iint_cache, iint);
  83 }
  84
  85 /**
  86  * integrity_inode_get - find or allocate an iint associated with an inode
  87  * @inode: pointer to the inode
  88  * @return: allocated iint
  89  *
  90  * Caller must lock i_mutex
  91  */
  92 struct integrity_iint_cache *integrity_inode_get(struct inode *inode)
  93 {
  94         struct rb_node **p;
  95         struct rb_node *node, *parent = NULL;
  96         struct integrity_iint_cache *iint, *test_iint;
  97
  98         iint = integrity_iint_find(inode);
  99         if (iint)
 100                 return iint;
 101
 102         iint = kmem_cache_alloc(iint_cache, GFP_NOFS);
 103         if (!iint)
 104                 return NULL;
 105
 106         write_lock(&integrity_iint_lock);
 107
 108         p = &integrity_iint_tree.rb_node;
 109         while (*p) {
 110                 parent = *p;
 111                 test_iint = rb_entry(parent, struct integrity_iint_cache,
 112                                      rb_node);
 113                 if (inode < test_iint->inode) {
 114                         p = &(*p)->rb_left;
 115                 } else if (inode > test_iint->inode) {
 116                         p = &(*p)->rb_right;
 117                 } else {
 118                         write_unlock(&integrity_iint_lock);
 119                         kmem_cache_free(iint_cache, iint);
 120                         return test_iint;
 121                 }
 122         }
 123
 124         iint->inode = inode;
 125         node = &iint->rb_node;
 126         inode->i_flags |= S_IMA;
 127         rb_link_node(node, parent, p);
 128         rb_insert_color(node, &integrity_iint_tree);
 129
 130         write_unlock(&integrity_iint_lock);
 131         return iint;
 132 }
 133
 134 /**
 135  * integrity_inode_free - called on security_inode_free
 136  * @inode: pointer to the inode
 137  *
 138  * Free the integrity information(iint) associated with an inode.
 139  */
 140 void integrity_inode_free(struct inode *inode)
 141 {
 142         struct integrity_iint_cache *iint;
 143
 144         if (!IS_IMA(inode))
 145                 return;
 146
 147         write_lock(&integrity_iint_lock);
 148         iint = __integrity_iint_find(inode);
 149         rb_erase(&iint->rb_node, &integrity_iint_tree);
 150         write_unlock(&integrity_iint_lock);
 151
 152         iint_free(iint);
 153 }
 154
 155 static void init_once(void *foo)
 156 {
 157         struct integrity_iint_cache *iint = foo;
 158
 159         memset(iint, 0, sizeof(*iint));
 160         iint->version = 0;
 161         iint->flags = 0UL;
 162         iint->atomic_flags = 0;
 163         iint->ima_file_status = INTEGRITY_UNKNOWN;
 164         iint->ima_mmap_status = INTEGRITY_UNKNOWN;
 165         iint->ima_bprm_status = INTEGRITY_UNKNOWN;
 166         iint->ima_read_status = INTEGRITY_UNKNOWN;
 167         iint->evm_status = INTEGRITY_UNKNOWN;
 168         iint->measured_pcrs = 0;
 169         mutex_init(&iint->mutex);
 170 }
 171
 172 static int __init integrity_iintcache_init(void)
 173 {
 174         iint_cache =
 175             kmem_cache_create("iint_cache", sizeof(struct integrity_iint_cache),
 176                               0, SLAB_PANIC, init_once);
 177         return 0;
 178 }
 179 security_initcall(integrity_iintcache_init);
 180
 181
 182 /*
 183  * integrity_kernel_read - read data from the file
 184  *
 185  * This is a function for reading file content instead of kernel_read().
 186  * It does not perform locking checks to ensure it cannot be blocked.
 187  * It does not perform security checks because it is irrelevant for IMA.
 188  *
 189  */
 190 int integrity_kernel_read(struct file *file, loff_t offset,
 191                           void *addr, unsigned long count)
 192 {
 193         mm_segment_t old_fs;
 194         char __user *buf = (char __user *)addr;
 195         ssize_t ret;
 196
 197         if (!(file->f_mode & FMODE_READ))
 198                 return -EBADF;
 199
 200         old_fs = get_fs();
 201         set_fs(get_ds());
 202         ret = __vfs_read(file, buf, count, &offset);
 203         set_fs(old_fs);
 204
 205         return ret;
 206 }
 207
 208 /*
 209  * integrity_read_file - read entire file content into the buffer
 210  *
 211  * This is function opens a file, allocates the buffer of required
 212  * size, read entire file content to the buffer and closes the file
 213  *
 214  * It is used only by init code.
 215  *
 216  */
 217 int __init integrity_read_file(const char *path, char **data)
 218 {
 219         struct file *file;
 220         loff_t size;
 221         char *buf;
 222         int rc = -EINVAL;
 223
 224         if (!path || !*path)
 225                 return -EINVAL;
 226
 227         file = filp_open(path, O_RDONLY, 0);
 228         if (IS_ERR(file)) {
 229                 rc = PTR_ERR(file);
 230                 pr_err("Unable to open file: %s (%d)", path, rc);
 231                 return rc;
 232         }
 233
 234         size = i_size_read(file_inode(file));
 235         if (size <= 0)
 236                 goto out;
 237
 238         buf = kmalloc(size, GFP_KERNEL);
 239         if (!buf) {
 240                 rc = -ENOMEM;
 241                 goto out;
 242         }
 243
 244         rc = integrity_kernel_read(file, 0, buf, size);
 245         if (rc == size) {
 246                 *data = buf;
 247         } else {
 248                 kfree(buf);
 249                 if (rc >= 0)
 250                         rc = -EIO;
 251         }
 252 out:
 253         fput(file);
 254         return rc;
 255 }
 256
 257 /*
 258  * integrity_load_keys - load integrity keys hook
 259  *
 260  * Hooks is called from init/main.c:kernel_init_freeable()
 261  * when rootfs is ready
 262  */
 263 void __init integrity_load_keys(void)
 264 {
 265         ima_load_x509();
 266         evm_load_x509();
 267 }