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         iint = integrity_iint_find(inode);
 102         if (iint)
 103                 return iint;
 104
 105         iint = kmem_cache_alloc(iint_cache, GFP_NOFS);
 106         if (!iint)
 107                 return NULL;
 108
 109         write_lock(&integrity_iint_lock);
 110
 111         p = &integrity_iint_tree.rb_node;
 112         while (*p) {
 113                 parent = *p;
 114                 test_iint = rb_entry(parent, struct integrity_iint_cache,
 115                                      rb_node);
 116                 if (inode < test_iint->inode)
 117                         p = &(*p)->rb_left;
 118                 else
 119                         p = &(*p)->rb_right;
 120         }
 121
 122         iint->inode = inode;
 123         node = &iint->rb_node;
 124         inode->i_flags |= S_IMA;
 125         rb_link_node(node, parent, p);
 126         rb_insert_color(node, &integrity_iint_tree);
 127
 128         write_unlock(&integrity_iint_lock);
 129         return iint;
 130 }
 131
 132 /**
 133  * integrity_inode_free - called on security_inode_free
 134  * @inode: pointer to the inode
 135  *
 136  * Free the integrity information(iint) associated with an inode.
 137  */
 138 void integrity_inode_free(struct inode *inode)
 139 {
 140         struct integrity_iint_cache *iint;
 141
 142         if (!IS_IMA(inode))
 143                 return;
 144
 145         write_lock(&integrity_iint_lock);
 146         iint = __integrity_iint_find(inode);
 147         rb_erase(&iint->rb_node, &integrity_iint_tree);
 148         write_unlock(&integrity_iint_lock);
 149
 150         iint_free(iint);
 151 }
 152
 153 static void init_once(void *foo)
 154 {
 155         struct integrity_iint_cache *iint = foo;
 156
 157         memset(iint, 0, sizeof(*iint));
 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->ima_creds_status = INTEGRITY_UNKNOWN;
 163         iint->evm_status = INTEGRITY_UNKNOWN;
 164         mutex_init(&iint->mutex);
 165 }
 166
 167 static int __init integrity_iintcache_init(void)
 168 {
 169         iint_cache =
 170             kmem_cache_create("iint_cache", sizeof(struct integrity_iint_cache),
 171                               0, SLAB_PANIC, init_once);
 172         return 0;
 173 }
 174 DEFINE_LSM(integrity) = {
 175         .name = "integrity",
 176         .init = integrity_iintcache_init,
 177 };
 178
 179
 180 /*
 181  * integrity_kernel_read - read data from the file
 182  *
 183  * This is a function for reading file content instead of kernel_read().
 184  * It does not perform locking checks to ensure it cannot be blocked.
 185  * It does not perform security checks because it is irrelevant for IMA.
 186  *
 187  */
 188 int integrity_kernel_read(struct file *file, loff_t offset,
 189                           void *addr, unsigned long count)
 190 {
 191         mm_segment_t old_fs;
 192         char __user *buf = (char __user *)addr;
 193         ssize_t ret;
 194
 195         if (!(file->f_mode & FMODE_READ))
 196                 return -EBADF;
 197
 198         old_fs = get_fs();
 199         set_fs(KERNEL_DS);
 200         ret = __vfs_read(file, buf, count, &offset);
 201         set_fs(old_fs);
 202
 203         return ret;
 204 }
 205
 206 /*
 207  * integrity_load_keys - load integrity keys hook
 208  *
 209  * Hooks is called from init/main.c:kernel_init_freeable()
 210  * when rootfs is ready
 211  */
 212 void __init integrity_load_keys(void)
 213 {
 214         ima_load_x509();
 215         evm_load_x509();
 216 }
 217
 218 static int __init integrity_fs_init(void)
 219 {
 220         integrity_dir = securityfs_create_dir("integrity", NULL);
 221         if (IS_ERR(integrity_dir)) {
 222                 int ret = PTR_ERR(integrity_dir);
 223
 224                 if (ret != -ENODEV)
 225                         pr_err("Unable to create integrity sysfs dir: %d\n",
 226                                ret);
 227                 integrity_dir = NULL;
 228                 return ret;
 229         }
 230
 231         return 0;
 232 }
 233
 234 late_initcall(integrity_fs_init)