security/integrity/iint.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (C) 2008 IBM Corporation
   4  *
   5  * Authors:
   6  * Mimi Zohar <zohar@us.ibm.com>
   7  *
   8  * File: integrity_iint.c
   9  *      - implements the integrity hooks: integrity_inode_alloc,
  10  *        integrity_inode_free
  11  *      - cache integrity information associated with an inode
  12  *        using a rbtree tree.
  13  */
  14 #include <linux/slab.h>
  15 #include <linux/init.h>
  16 #include <linux/spinlock.h>
  17 #include <linux/rbtree.h>
  18 #include <linux/file.h>
  19 #include <linux/uaccess.h>
  20 #include <linux/security.h>
  21 #include <linux/lsm_hooks.h>
  22 #include "integrity.h"
  23
  24 static struct rb_root integrity_iint_tree = RB_ROOT;
  25 static DEFINE_RWLOCK(integrity_iint_lock);
  26 static struct kmem_cache *iint_cache __read_mostly;
  27
  28 struct dentry *integrity_dir;
  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->ima_creds_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         /*
 100          * The integrity's "iint_cache" is initialized at security_init(),
 101          * unless it is not included in the ordered list of LSMs enabled
 102          * on the boot command line.
 103          */
 104         if (!iint_cache)
 105                 panic("%s: lsm=integrity required.\n", __func__);
 106
 107         iint = integrity_iint_find(inode);
 108         if (iint)
 109                 return iint;
 110
 111         iint = kmem_cache_alloc(iint_cache, GFP_NOFS);
 112         if (!iint)
 113                 return NULL;
 114
 115         write_lock(&integrity_iint_lock);
 116
 117         p = &integrity_iint_tree.rb_node;
 118         while (*p) {
 119                 parent = *p;
 120                 test_iint = rb_entry(parent, struct integrity_iint_cache,
 121                                      rb_node);
 122                 if (inode < test_iint->inode) {
 123                         p = &(*p)->rb_left;
 124                 } else if (inode > test_iint->inode) {
 125                         p = &(*p)->rb_right;
 126                 } else {
 127                         write_unlock(&integrity_iint_lock);
 128                         kmem_cache_free(iint_cache, iint);
 129                         return test_iint;
 130                 }
 131         }
 132
 133         iint->inode = inode;
 134         node = &iint->rb_node;
 135         inode->i_flags |= S_IMA;
 136         rb_link_node(node, parent, p);
 137         rb_insert_color(node, &integrity_iint_tree);
 138
 139         write_unlock(&integrity_iint_lock);
 140         return iint;
 141 }
 142
 143 /**
 144  * integrity_inode_free - called on security_inode_free
 145  * @inode: pointer to the inode
 146  *
 147  * Free the integrity information(iint) associated with an inode.
 148  */
 149 void integrity_inode_free(struct inode *inode)
 150 {
 151         struct integrity_iint_cache *iint;
 152
 153         if (!IS_IMA(inode))
 154                 return;
 155
 156         write_lock(&integrity_iint_lock);
 157         iint = __integrity_iint_find(inode);
 158         rb_erase(&iint->rb_node, &integrity_iint_tree);
 159         write_unlock(&integrity_iint_lock);
 160
 161         iint_free(iint);
 162 }
 163
 164 static void init_once(void *foo)
 165 {
 166         struct integrity_iint_cache *iint = (struct integrity_iint_cache *) foo;
 167
 168         memset(iint, 0, sizeof(*iint));
 169         iint->ima_file_status = INTEGRITY_UNKNOWN;
 170         iint->ima_mmap_status = INTEGRITY_UNKNOWN;
 171         iint->ima_bprm_status = INTEGRITY_UNKNOWN;
 172         iint->ima_read_status = INTEGRITY_UNKNOWN;
 173         iint->ima_creds_status = INTEGRITY_UNKNOWN;
 174         iint->evm_status = INTEGRITY_UNKNOWN;
 175         mutex_init(&iint->mutex);
 176 }
 177
 178 static int __init integrity_iintcache_init(void)
 179 {
 180         iint_cache =
 181             kmem_cache_create("iint_cache", sizeof(struct integrity_iint_cache),
 182                               0, SLAB_PANIC, init_once);
 183         return 0;
 184 }
 185 DEFINE_LSM(integrity) = {
 186         .name = "integrity",
 187         .init = integrity_iintcache_init,
 188 };
 189
 190
 191 /*
 192  * integrity_kernel_read - read data from the file
 193  *
 194  * This is a function for reading file content instead of kernel_read().
 195  * It does not perform locking checks to ensure it cannot be blocked.
 196  * It does not perform security checks because it is irrelevant for IMA.
 197  *
 198  */
 199 int integrity_kernel_read(struct file *file, loff_t offset,
 200                           void *addr, unsigned long count)
 201 {
 202         return __kernel_read(file, addr, count, &offset);
 203 }
 204
 205 /*
 206  * integrity_load_keys - load integrity keys hook
 207  *
 208  * Hooks is called from init/main.c:kernel_init_freeable()
 209  * when rootfs is ready
 210  */
 211 void __init integrity_load_keys(void)
 212 {
 213         ima_load_x509();
 214
 215         if (!IS_ENABLED(CONFIG_IMA_LOAD_X509))
 216                 evm_load_x509();
 217 }
 218
 219 static int __init integrity_fs_init(void)
 220 {
 221         integrity_dir = securityfs_create_dir("integrity", NULL);
 222         if (IS_ERR(integrity_dir)) {
 223                 int ret = PTR_ERR(integrity_dir);
 224
 225                 if (ret != -ENODEV)
 226                         pr_err("Unable to create integrity sysfs dir: %d\n",
 227                                ret);
 228                 integrity_dir = NULL;
 229                 return ret;
 230         }
 231
 232         return 0;
 233 }
 234
 235 late_initcall(integrity_fs_init)