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_module_status = INTEGRITY_UNKNOWN; 81 iint->evm_status = INTEGRITY_UNKNOWN; 82 kmem_cache_free(iint_cache, iint); 83 } 84 85 /** 86 * integrity_inode_get - find or allocate an iint associated with an inode 87 * @inode: pointer to the inode 88 * @return: allocated iint 89 * 90 * Caller must lock i_mutex 91 */ 92 struct integrity_iint_cache *integrity_inode_get(struct inode *inode) 93 { 94 struct rb_node **p; 95 struct rb_node *node, *parent = NULL; 96 struct integrity_iint_cache *iint, *test_iint; 97 98 iint = integrity_iint_find(inode); 99 if (iint) 100 return iint; 101 102 iint = kmem_cache_alloc(iint_cache, GFP_NOFS); 103 if (!iint) 104 return NULL; 105 106 write_lock(&integrity_iint_lock); 107 108 p = &integrity_iint_tree.rb_node; 109 while (*p) { 110 parent = *p; 111 test_iint = rb_entry(parent, struct integrity_iint_cache, 112 rb_node); 113 if (inode < test_iint->inode) 114 p = &(*p)->rb_left; 115 else 116 p = &(*p)->rb_right; 117 } 118 119 iint->inode = inode; 120 node = &iint->rb_node; 121 inode->i_flags |= S_IMA; 122 rb_link_node(node, parent, p); 123 rb_insert_color(node, &integrity_iint_tree); 124 125 write_unlock(&integrity_iint_lock); 126 return iint; 127 } 128 129 /** 130 * integrity_inode_free - called on security_inode_free 131 * @inode: pointer to the inode 132 * 133 * Free the integrity information(iint) associated with an inode. 134 */ 135 void integrity_inode_free(struct inode *inode) 136 { 137 struct integrity_iint_cache *iint; 138 139 if (!IS_IMA(inode)) 140 return; 141 142 write_lock(&integrity_iint_lock); 143 iint = __integrity_iint_find(inode); 144 rb_erase(&iint->rb_node, &integrity_iint_tree); 145 write_unlock(&integrity_iint_lock); 146 147 iint_free(iint); 148 } 149 150 static void init_once(void *foo) 151 { 152 struct integrity_iint_cache *iint = foo; 153 154 memset(iint, 0, sizeof(*iint)); 155 iint->version = 0; 156 iint->flags = 0UL; 157 iint->ima_file_status = INTEGRITY_UNKNOWN; 158 iint->ima_mmap_status = INTEGRITY_UNKNOWN; 159 iint->ima_bprm_status = INTEGRITY_UNKNOWN; 160 iint->ima_module_status = INTEGRITY_UNKNOWN; 161 iint->evm_status = INTEGRITY_UNKNOWN; 162 } 163 164 static int __init integrity_iintcache_init(void) 165 { 166 iint_cache = 167 kmem_cache_create("iint_cache", sizeof(struct integrity_iint_cache), 168 0, SLAB_PANIC, init_once); 169 return 0; 170 } 171 security_initcall(integrity_iintcache_init); 172 173 174 /* 175 * integrity_kernel_read - read data from the file 176 * 177 * This is a function for reading file content instead of kernel_read(). 178 * It does not perform locking checks to ensure it cannot be blocked. 179 * It does not perform security checks because it is irrelevant for IMA. 180 * 181 */ 182 int integrity_kernel_read(struct file *file, loff_t offset, 183 char *addr, unsigned long count) 184 { 185 mm_segment_t old_fs; 186 char __user *buf = (char __user *)addr; 187 ssize_t ret; 188 189 if (!(file->f_mode & FMODE_READ)) 190 return -EBADF; 191 192 old_fs = get_fs(); 193 set_fs(get_ds()); 194 ret = __vfs_read(file, buf, count, &offset); 195 set_fs(old_fs); 196 197 return ret; 198 } 199 200 /* 201 * integrity_read_file - read entire file content into the buffer 202 * 203 * This is function opens a file, allocates the buffer of required 204 * size, read entire file content to the buffer and closes the file 205 * 206 * It is used only by init code. 207 * 208 */ 209 int __init integrity_read_file(const char *path, char **data) 210 { 211 struct file *file; 212 loff_t size; 213 char *buf; 214 int rc = -EINVAL; 215 216 file = filp_open(path, O_RDONLY, 0); 217 if (IS_ERR(file)) { 218 rc = PTR_ERR(file); 219 pr_err("Unable to open file: %s (%d)", path, rc); 220 return rc; 221 } 222 223 size = i_size_read(file_inode(file)); 224 if (size <= 0) 225 goto out; 226 227 buf = kmalloc(size, GFP_KERNEL); 228 if (!buf) { 229 rc = -ENOMEM; 230 goto out; 231 } 232 233 rc = integrity_kernel_read(file, 0, buf, size); 234 if (rc < 0) 235 kfree(buf); 236 else if (rc != size) 237 rc = -EIO; 238 else 239 *data = buf; 240 out: 241 fput(file); 242 return rc; 243 } 244 245 /* 246 * integrity_load_keys - load integrity keys hook 247 * 248 * Hooks is called from init/main.c:kernel_init_freeable() 249 * when rootfs is ready 250 */ 251 void __init integrity_load_keys(void) 252 { 253 ima_load_x509(); 254 } 255