linux/security/integrity/iint.c
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   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
  24static struct rb_root integrity_iint_tree = RB_ROOT;
  25static DEFINE_RWLOCK(integrity_iint_lock);
  26static struct kmem_cache *iint_cache __read_mostly;
  27
  28struct dentry *integrity_dir;
  29
  30/*
  31 * __integrity_iint_find - return the iint associated with an inode
  32 */
  33static 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 */
  57struct 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
  71static 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 */
  95struct 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 */
 146void 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
 161static 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
 175static 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}
 182DEFINE_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 */
 196int 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 */
 208void __init integrity_load_keys(void)
 209{
 210        ima_load_x509();
 211
 212        if (!IS_ENABLED(CONFIG_IMA_LOAD_X509))
 213                evm_load_x509();
 214}
 215
 216static int __init integrity_fs_init(void)
 217{
 218        integrity_dir = securityfs_create_dir("integrity", NULL);
 219        if (IS_ERR(integrity_dir)) {
 220                int ret = PTR_ERR(integrity_dir);
 221
 222                if (ret != -ENODEV)
 223                        pr_err("Unable to create integrity sysfs dir: %d\n",
 224                               ret);
 225                integrity_dir = NULL;
 226                return ret;
 227        }
 228
 229        return 0;
 230}
 231
 232late_initcall(integrity_fs_init)
 233