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 #define IMA_MAX_NESTING (FILESYSTEM_MAX_STACK_DEPTH+1) 70 71 /* 72 * It is not clear that IMA should be nested at all, but as long is it measures 73 * files both on overlayfs and on underlying fs, we need to annotate the iint 74 * mutex to avoid lockdep false positives related to IMA + overlayfs. 75 * See ovl_lockdep_annotate_inode_mutex_key() for more details. 76 */ 77 static inline void iint_lockdep_annotate(struct integrity_iint_cache *iint, 78 struct inode *inode) 79 { 80 #ifdef CONFIG_LOCKDEP 81 static struct lock_class_key iint_mutex_key[IMA_MAX_NESTING]; 82 83 int depth = inode->i_sb->s_stack_depth; 84 85 if (WARN_ON_ONCE(depth < 0 || depth >= IMA_MAX_NESTING)) 86 depth = 0; 87 88 lockdep_set_class(&iint->mutex, &iint_mutex_key[depth]); 89 #endif 90 } 91 92 static void iint_init_always(struct integrity_iint_cache *iint, 93 struct inode *inode) 94 { 95 iint->ima_hash = NULL; 96 iint->version = 0; 97 iint->flags = 0UL; 98 iint->atomic_flags = 0UL; 99 iint->ima_file_status = INTEGRITY_UNKNOWN; 100 iint->ima_mmap_status = INTEGRITY_UNKNOWN; 101 iint->ima_bprm_status = INTEGRITY_UNKNOWN; 102 iint->ima_read_status = INTEGRITY_UNKNOWN; 103 iint->ima_creds_status = INTEGRITY_UNKNOWN; 104 iint->evm_status = INTEGRITY_UNKNOWN; 105 iint->measured_pcrs = 0; 106 mutex_init(&iint->mutex); 107 iint_lockdep_annotate(iint, inode); 108 } 109 110 static void iint_free(struct integrity_iint_cache *iint) 111 { 112 kfree(iint->ima_hash); 113 mutex_destroy(&iint->mutex); 114 kmem_cache_free(iint_cache, iint); 115 } 116 117 /** 118 * integrity_inode_get - find or allocate an iint associated with an inode 119 * @inode: pointer to the inode 120 * @return: allocated iint 121 * 122 * Caller must lock i_mutex 123 */ 124 struct integrity_iint_cache *integrity_inode_get(struct inode *inode) 125 { 126 struct rb_node **p; 127 struct rb_node *node, *parent = NULL; 128 struct integrity_iint_cache *iint, *test_iint; 129 130 iint = integrity_iint_find(inode); 131 if (iint) 132 return iint; 133 134 iint = kmem_cache_alloc(iint_cache, GFP_NOFS); 135 if (!iint) 136 return NULL; 137 138 iint_init_always(iint, inode); 139 140 write_lock(&integrity_iint_lock); 141 142 p = &integrity_iint_tree.rb_node; 143 while (*p) { 144 parent = *p; 145 test_iint = rb_entry(parent, struct integrity_iint_cache, 146 rb_node); 147 if (inode < test_iint->inode) { 148 p = &(*p)->rb_left; 149 } else if (inode > test_iint->inode) { 150 p = &(*p)->rb_right; 151 } else { 152 write_unlock(&integrity_iint_lock); 153 kmem_cache_free(iint_cache, iint); 154 return test_iint; 155 } 156 } 157 158 iint->inode = inode; 159 node = &iint->rb_node; 160 inode->i_flags |= S_IMA; 161 rb_link_node(node, parent, p); 162 rb_insert_color(node, &integrity_iint_tree); 163 164 write_unlock(&integrity_iint_lock); 165 return iint; 166 } 167 168 /** 169 * integrity_inode_free - called on security_inode_free 170 * @inode: pointer to the inode 171 * 172 * Free the integrity information(iint) associated with an inode. 173 */ 174 void integrity_inode_free(struct inode *inode) 175 { 176 struct integrity_iint_cache *iint; 177 178 if (!IS_IMA(inode)) 179 return; 180 181 write_lock(&integrity_iint_lock); 182 iint = __integrity_iint_find(inode); 183 rb_erase(&iint->rb_node, &integrity_iint_tree); 184 write_unlock(&integrity_iint_lock); 185 186 iint_free(iint); 187 } 188 189 static void iint_init_once(void *foo) 190 { 191 struct integrity_iint_cache *iint = (struct integrity_iint_cache *) foo; 192 193 memset(iint, 0, sizeof(*iint)); 194 } 195 196 static int __init integrity_iintcache_init(void) 197 { 198 iint_cache = 199 kmem_cache_create("iint_cache", sizeof(struct integrity_iint_cache), 200 0, SLAB_PANIC, iint_init_once); 201 return 0; 202 } 203 DEFINE_LSM(integrity) = { 204 .name = "integrity", 205 .init = integrity_iintcache_init, 206 .order = LSM_ORDER_LAST, 207 }; 208 209 210 /* 211 * integrity_kernel_read - read data from the file 212 * 213 * This is a function for reading file content instead of kernel_read(). 214 * It does not perform locking checks to ensure it cannot be blocked. 215 * It does not perform security checks because it is irrelevant for IMA. 216 * 217 */ 218 int integrity_kernel_read(struct file *file, loff_t offset, 219 void *addr, unsigned long count) 220 { 221 return __kernel_read(file, addr, count, &offset); 222 } 223 224 /* 225 * integrity_load_keys - load integrity keys hook 226 * 227 * Hooks is called from init/main.c:kernel_init_freeable() 228 * when rootfs is ready 229 */ 230 void __init integrity_load_keys(void) 231 { 232 ima_load_x509(); 233 234 if (!IS_ENABLED(CONFIG_IMA_LOAD_X509)) 235 evm_load_x509(); 236 } 237 238 static int __init integrity_fs_init(void) 239 { 240 integrity_dir = securityfs_create_dir("integrity", NULL); 241 if (IS_ERR(integrity_dir)) { 242 int ret = PTR_ERR(integrity_dir); 243 244 if (ret != -ENODEV) 245 pr_err("Unable to create integrity sysfs dir: %d\n", 246 ret); 247 integrity_dir = NULL; 248 return ret; 249 } 250 251 return 0; 252 } 253 254 late_initcall(integrity_fs_init) 255