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 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->evm_status = INTEGRITY_UNKNOWN; 83 iint->measured_pcrs = 0; 84 kmem_cache_free(iint_cache, iint); 85 } 86 87 /** 88 * integrity_inode_get - find or allocate an iint associated with an inode 89 * @inode: pointer to the inode 90 * @return: allocated iint 91 * 92 * Caller must lock i_mutex 93 */ 94 struct integrity_iint_cache *integrity_inode_get(struct inode *inode) 95 { 96 struct rb_node **p; 97 struct rb_node *node, *parent = NULL; 98 struct integrity_iint_cache *iint, *test_iint; 99 100 iint = integrity_iint_find(inode); 101 if (iint) 102 return iint; 103 104 iint = kmem_cache_alloc(iint_cache, GFP_NOFS); 105 if (!iint) 106 return NULL; 107 108 write_lock(&integrity_iint_lock); 109 110 p = &integrity_iint_tree.rb_node; 111 while (*p) { 112 parent = *p; 113 test_iint = rb_entry(parent, struct integrity_iint_cache, 114 rb_node); 115 if (inode < test_iint->inode) 116 p = &(*p)->rb_left; 117 else 118 p = &(*p)->rb_right; 119 } 120 121 iint->inode = inode; 122 node = &iint->rb_node; 123 inode->i_flags |= S_IMA; 124 rb_link_node(node, parent, p); 125 rb_insert_color(node, &integrity_iint_tree); 126 127 write_unlock(&integrity_iint_lock); 128 return iint; 129 } 130 131 /** 132 * integrity_inode_free - called on security_inode_free 133 * @inode: pointer to the inode 134 * 135 * Free the integrity information(iint) associated with an inode. 136 */ 137 void integrity_inode_free(struct inode *inode) 138 { 139 struct integrity_iint_cache *iint; 140 141 if (!IS_IMA(inode)) 142 return; 143 144 write_lock(&integrity_iint_lock); 145 iint = __integrity_iint_find(inode); 146 rb_erase(&iint->rb_node, &integrity_iint_tree); 147 write_unlock(&integrity_iint_lock); 148 149 iint_free(iint); 150 } 151 152 static void init_once(void *foo) 153 { 154 struct integrity_iint_cache *iint = foo; 155 156 memset(iint, 0, sizeof(*iint)); 157 iint->ima_file_status = INTEGRITY_UNKNOWN; 158 iint->ima_mmap_status = INTEGRITY_UNKNOWN; 159 iint->ima_bprm_status = INTEGRITY_UNKNOWN; 160 iint->ima_read_status = INTEGRITY_UNKNOWN; 161 iint->evm_status = INTEGRITY_UNKNOWN; 162 mutex_init(&iint->mutex); 163 } 164 165 static int __init integrity_iintcache_init(void) 166 { 167 iint_cache = 168 kmem_cache_create("iint_cache", sizeof(struct integrity_iint_cache), 169 0, SLAB_PANIC, init_once); 170 return 0; 171 } 172 security_initcall(integrity_iintcache_init); 173 174 175 /* 176 * integrity_kernel_read - read data from the file 177 * 178 * This is a function for reading file content instead of kernel_read(). 179 * It does not perform locking checks to ensure it cannot be blocked. 180 * It does not perform security checks because it is irrelevant for IMA. 181 * 182 */ 183 int integrity_kernel_read(struct file *file, loff_t offset, 184 void *addr, unsigned long count) 185 { 186 mm_segment_t old_fs; 187 char __user *buf = (char __user *)addr; 188 ssize_t ret; 189 190 if (!(file->f_mode & FMODE_READ)) 191 return -EBADF; 192 193 old_fs = get_fs(); 194 set_fs(get_ds()); 195 ret = __vfs_read(file, buf, count, &offset); 196 set_fs(old_fs); 197 198 return ret; 199 } 200 201 /* 202 * integrity_load_keys - load integrity keys hook 203 * 204 * Hooks is called from init/main.c:kernel_init_freeable() 205 * when rootfs is ready 206 */ 207 void __init integrity_load_keys(void) 208 { 209 ima_load_x509(); 210 evm_load_x509(); 211 } 212