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                         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->atomic_flags = 0UL;
  78         iint->ima_file_status = INTEGRITY_UNKNOWN;
  79         iint->ima_mmap_status = INTEGRITY_UNKNOWN;
  80         iint->ima_bprm_status = INTEGRITY_UNKNOWN;
  81         iint->ima_read_status = INTEGRITY_UNKNOWN;
  82         iint->ima_creds_status = INTEGRITY_UNKNOWN;
  83         iint->evm_status = INTEGRITY_UNKNOWN;
  84         iint->measured_pcrs = 0;
  85         kmem_cache_free(iint_cache, iint);
  86 }
  87
  88 /**
  89  * integrity_inode_get - find or allocate an iint associated with an inode
  90  * @inode: pointer to the inode
  91  * @return: allocated iint
  92  *
  93  * Caller must lock i_mutex
  94  */
  95 struct integrity_iint_cache *integrity_inode_get(struct inode *inode)
  96 {
  97         struct rb_node **p;
  98         struct rb_node *node, *parent = NULL;
  99         struct integrity_iint_cache *iint, *test_iint;
 100
 101         /*
 102          * The integrity's "iint_cache" is initialized at security_init(),
 103          * unless it is not included in the ordered list of LSMs enabled
 104          * on the boot command line.
 105          */
 106         if (!iint_cache)
 107                 panic("%s: lsm=integrity required.\n", __func__);
 108
 109         iint = integrity_iint_find(inode);
 110         if (iint)
 111                 return iint;
 112
 113         iint = kmem_cache_alloc(iint_cache, GFP_NOFS);
 114         if (!iint)
 115                 return NULL;
 116
 117         write_lock(&integrity_iint_lock);
 118
 119         p = &integrity_iint_tree.rb_node;
 120         while (*p) {
 121                 parent = *p;
 122                 test_iint = rb_entry(parent, struct integrity_iint_cache,
 123                                      rb_node);
 124                 if (inode < test_iint->inode)
 125                         p = &(*p)->rb_left;
 126                 else
 127                         p = &(*p)->rb_right;
 128         }
 129
 130         iint->inode = inode;
 131         node = &iint->rb_node;
 132         inode->i_flags |= S_IMA;
 133         rb_link_node(node, parent, p);
 134         rb_insert_color(node, &integrity_iint_tree);
 135
 136         write_unlock(&integrity_iint_lock);
 137         return iint;
 138 }
 139
 140 /**
 141  * integrity_inode_free - called on security_inode_free
 142  * @inode: pointer to the inode
 143  *
 144  * Free the integrity information(iint) associated with an inode.
 145  */
 146 void integrity_inode_free(struct inode *inode)
 147 {
 148         struct integrity_iint_cache *iint;
 149
 150         if (!IS_IMA(inode))
 151                 return;
 152
 153         write_lock(&integrity_iint_lock);
 154         iint = __integrity_iint_find(inode);
 155         rb_erase(&iint->rb_node, &integrity_iint_tree);
 156         write_unlock(&integrity_iint_lock);
 157
 158         iint_free(iint);
 159 }
 160
 161 static void init_once(void *foo)
 162 {
 163         struct integrity_iint_cache *iint = (struct integrity_iint_cache *) foo;
 164
 165         memset(iint, 0, sizeof(*iint));
 166         iint->ima_file_status = INTEGRITY_UNKNOWN;
 167         iint->ima_mmap_status = INTEGRITY_UNKNOWN;
 168         iint->ima_bprm_status = INTEGRITY_UNKNOWN;
 169         iint->ima_read_status = INTEGRITY_UNKNOWN;
 170         iint->ima_creds_status = INTEGRITY_UNKNOWN;
 171         iint->evm_status = INTEGRITY_UNKNOWN;
 172         mutex_init(&iint->mutex);
 173 }
 174
 175 static int __init integrity_iintcache_init(void)
 176 {
 177         iint_cache =
 178             kmem_cache_create("iint_cache", sizeof(struct integrity_iint_cache),
 179                               0, SLAB_PANIC, init_once);
 180         return 0;
 181 }
 182 DEFINE_LSM(integrity) = {
 183         .name = "integrity",
 184         .init = integrity_iintcache_init,
 185 };
 186
 187
 188 /*
 189  * integrity_kernel_read - read data from the file
 190  *
 191  * This is a function for reading file content instead of kernel_read().
 192  * It does not perform locking checks to ensure it cannot be blocked.
 193  * It does not perform security checks because it is irrelevant for IMA.
 194  *
 195  */
 196 int integrity_kernel_read(struct file *file, loff_t offset,
 197                           void *addr, unsigned long count)
 198 {
 199         return __kernel_read(file, addr, count, &offset);
 200 }
 201
 202 /*
 203  * integrity_load_keys - load integrity keys hook
 204  *
 205  * Hooks is called from init/main.c:kernel_init_freeable()
 206  * when rootfs is ready
 207  */
 208 void __init integrity_load_keys(void)
 209 {
 210         ima_load_x509();
 211         evm_load_x509();
 212 }
 213
 214 static int __init integrity_fs_init(void)
 215 {
 216         integrity_dir = securityfs_create_dir("integrity", NULL);
 217         if (IS_ERR(integrity_dir)) {
 218                 int ret = PTR_ERR(integrity_dir);
 219
 220                 if (ret != -ENODEV)
 221                         pr_err("Unable to create integrity sysfs dir: %d\n",
 222                                ret);
 223                 integrity_dir = NULL;
 224                 return ret;
 225         }
 226
 227         return 0;
 228 }
 229
 230 late_initcall(integrity_fs_init)