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->ima_file_status = INTEGRITY_UNKNOWN; 78 iint->ima_mmap_status = INTEGRITY_UNKNOWN; 79 iint->ima_bprm_status = INTEGRITY_UNKNOWN; 80 iint->ima_read_status = INTEGRITY_UNKNOWN; 81 iint->evm_status = INTEGRITY_UNKNOWN; 82 iint->measured_pcrs = 0; 83 kmem_cache_free(iint_cache, iint); 84 } 85 86 /** 87 * integrity_inode_get - find or allocate an iint associated with an inode 88 * @inode: pointer to the inode 89 * @return: allocated iint 90 * 91 * Caller must lock i_mutex 92 */ 93 struct integrity_iint_cache *integrity_inode_get(struct inode *inode) 94 { 95 struct rb_node **p; 96 struct rb_node *node, *parent = NULL; 97 struct integrity_iint_cache *iint, *test_iint; 98 99 iint = integrity_iint_find(inode); 100 if (iint) 101 return iint; 102 103 iint = kmem_cache_alloc(iint_cache, GFP_NOFS); 104 if (!iint) 105 return NULL; 106 107 write_lock(&integrity_iint_lock); 108 109 p = &integrity_iint_tree.rb_node; 110 while (*p) { 111 parent = *p; 112 test_iint = rb_entry(parent, struct integrity_iint_cache, 113 rb_node); 114 if (inode < test_iint->inode) 115 p = &(*p)->rb_left; 116 else 117 p = &(*p)->rb_right; 118 } 119 120 iint->inode = inode; 121 node = &iint->rb_node; 122 inode->i_flags |= S_IMA; 123 rb_link_node(node, parent, p); 124 rb_insert_color(node, &integrity_iint_tree); 125 126 write_unlock(&integrity_iint_lock); 127 return iint; 128 } 129 130 /** 131 * integrity_inode_free - called on security_inode_free 132 * @inode: pointer to the inode 133 * 134 * Free the integrity information(iint) associated with an inode. 135 */ 136 void integrity_inode_free(struct inode *inode) 137 { 138 struct integrity_iint_cache *iint; 139 140 if (!IS_IMA(inode)) 141 return; 142 143 write_lock(&integrity_iint_lock); 144 iint = __integrity_iint_find(inode); 145 rb_erase(&iint->rb_node, &integrity_iint_tree); 146 write_unlock(&integrity_iint_lock); 147 148 iint_free(iint); 149 } 150 151 static void init_once(void *foo) 152 { 153 struct integrity_iint_cache *iint = foo; 154 155 memset(iint, 0, sizeof(*iint)); 156 iint->version = 0; 157 iint->flags = 0UL; 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->evm_status = INTEGRITY_UNKNOWN; 163 iint->measured_pcrs = 0; 164 } 165 166 static int __init integrity_iintcache_init(void) 167 { 168 iint_cache = 169 kmem_cache_create("iint_cache", sizeof(struct integrity_iint_cache), 170 0, SLAB_PANIC, init_once); 171 return 0; 172 } 173 security_initcall(integrity_iintcache_init); 174 175 176 /* 177 * integrity_kernel_read - read data from the file 178 * 179 * This is a function for reading file content instead of kernel_read(). 180 * It does not perform locking checks to ensure it cannot be blocked. 181 * It does not perform security checks because it is irrelevant for IMA. 182 * 183 */ 184 int integrity_kernel_read(struct file *file, loff_t offset, 185 void *addr, unsigned long count) 186 { 187 mm_segment_t old_fs; 188 char __user *buf = (char __user *)addr; 189 ssize_t ret; 190 191 if (!(file->f_mode & FMODE_READ)) 192 return -EBADF; 193 194 old_fs = get_fs(); 195 set_fs(get_ds()); 196 ret = __vfs_read(file, buf, count, &offset); 197 set_fs(old_fs); 198 199 return ret; 200 } 201 202 /* 203 * integrity_read_file - read entire file content into the buffer 204 * 205 * This is function opens a file, allocates the buffer of required 206 * size, read entire file content to the buffer and closes the file 207 * 208 * It is used only by init code. 209 * 210 */ 211 int __init integrity_read_file(const char *path, char **data) 212 { 213 struct file *file; 214 loff_t size; 215 char *buf; 216 int rc = -EINVAL; 217 218 if (!path || !*path) 219 return -EINVAL; 220 221 file = filp_open(path, O_RDONLY, 0); 222 if (IS_ERR(file)) { 223 rc = PTR_ERR(file); 224 pr_err("Unable to open file: %s (%d)", path, rc); 225 return rc; 226 } 227 228 size = i_size_read(file_inode(file)); 229 if (size <= 0) 230 goto out; 231 232 buf = kmalloc(size, GFP_KERNEL); 233 if (!buf) { 234 rc = -ENOMEM; 235 goto out; 236 } 237 238 rc = integrity_kernel_read(file, 0, buf, size); 239 if (rc == size) { 240 *data = buf; 241 } else { 242 kfree(buf); 243 if (rc >= 0) 244 rc = -EIO; 245 } 246 out: 247 fput(file); 248 return rc; 249 } 250 251 /* 252 * integrity_load_keys - load integrity keys hook 253 * 254 * Hooks is called from init/main.c:kernel_init_freeable() 255 * when rootfs is ready 256 */ 257 void __init integrity_load_keys(void) 258 { 259 ima_load_x509(); 260 evm_load_x509(); 261 } 262