1 /** 2 * eCryptfs: Linux filesystem encryption layer 3 * 4 * Copyright (C) 1997-2004 Erez Zadok 5 * Copyright (C) 2001-2004 Stony Brook University 6 * Copyright (C) 2004-2007 International Business Machines Corp. 7 * Author(s): Michael A. Halcrow <mhalcrow@us.ibm.com> 8 * Michael C. Thompson <mcthomps@us.ibm.com> 9 * 10 * This program is free software; you can redistribute it and/or 11 * modify it under the terms of the GNU General Public License as 12 * published by the Free Software Foundation; either version 2 of the 13 * License, or (at your option) any later version. 14 * 15 * This program is distributed in the hope that it will be useful, but 16 * WITHOUT ANY WARRANTY; without even the implied warranty of 17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 18 * General Public License for more details. 19 * 20 * You should have received a copy of the GNU General Public License 21 * along with this program; if not, write to the Free Software 22 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 23 * 02111-1307, USA. 24 */ 25 26 #include <linux/file.h> 27 #include <linux/poll.h> 28 #include <linux/slab.h> 29 #include <linux/mount.h> 30 #include <linux/pagemap.h> 31 #include <linux/security.h> 32 #include <linux/compat.h> 33 #include <linux/fs_stack.h> 34 #include "ecryptfs_kernel.h" 35 36 /** 37 * ecryptfs_read_update_atime 38 * 39 * generic_file_read updates the atime of upper layer inode. But, it 40 * doesn't give us a chance to update the atime of the lower layer 41 * inode. This function is a wrapper to generic_file_read. It 42 * updates the atime of the lower level inode if generic_file_read 43 * returns without any errors. This is to be used only for file reads. 44 * The function to be used for directory reads is ecryptfs_read. 45 */ 46 static ssize_t ecryptfs_read_update_atime(struct kiocb *iocb, 47 const struct iovec *iov, 48 unsigned long nr_segs, loff_t pos) 49 { 50 ssize_t rc; 51 struct path lower; 52 struct file *file = iocb->ki_filp; 53 54 rc = generic_file_aio_read(iocb, iov, nr_segs, pos); 55 /* 56 * Even though this is a async interface, we need to wait 57 * for IO to finish to update atime 58 */ 59 if (-EIOCBQUEUED == rc) 60 rc = wait_on_sync_kiocb(iocb); 61 if (rc >= 0) { 62 lower.dentry = ecryptfs_dentry_to_lower(file->f_path.dentry); 63 lower.mnt = ecryptfs_dentry_to_lower_mnt(file->f_path.dentry); 64 touch_atime(&lower); 65 } 66 return rc; 67 } 68 69 struct ecryptfs_getdents_callback { 70 void *dirent; 71 struct dentry *dentry; 72 filldir_t filldir; 73 int filldir_called; 74 int entries_written; 75 }; 76 77 /* Inspired by generic filldir in fs/readdir.c */ 78 static int 79 ecryptfs_filldir(void *dirent, const char *lower_name, int lower_namelen, 80 loff_t offset, u64 ino, unsigned int d_type) 81 { 82 struct ecryptfs_getdents_callback *buf = 83 (struct ecryptfs_getdents_callback *)dirent; 84 size_t name_size; 85 char *name; 86 int rc; 87 88 buf->filldir_called++; 89 rc = ecryptfs_decode_and_decrypt_filename(&name, &name_size, 90 buf->dentry, lower_name, 91 lower_namelen); 92 if (rc) { 93 printk(KERN_ERR "%s: Error attempting to decode and decrypt " 94 "filename [%s]; rc = [%d]\n", __func__, lower_name, 95 rc); 96 goto out; 97 } 98 rc = buf->filldir(buf->dirent, name, name_size, offset, ino, d_type); 99 kfree(name); 100 if (rc >= 0) 101 buf->entries_written++; 102 out: 103 return rc; 104 } 105 106 /** 107 * ecryptfs_readdir 108 * @file: The eCryptfs directory file 109 * @dirent: Directory entry handle 110 * @filldir: The filldir callback function 111 */ 112 static int ecryptfs_readdir(struct file *file, void *dirent, filldir_t filldir) 113 { 114 int rc; 115 struct file *lower_file; 116 struct inode *inode; 117 struct ecryptfs_getdents_callback buf; 118 119 lower_file = ecryptfs_file_to_lower(file); 120 lower_file->f_pos = file->f_pos; 121 inode = file->f_path.dentry->d_inode; 122 memset(&buf, 0, sizeof(buf)); 123 buf.dirent = dirent; 124 buf.dentry = file->f_path.dentry; 125 buf.filldir = filldir; 126 buf.filldir_called = 0; 127 buf.entries_written = 0; 128 rc = vfs_readdir(lower_file, ecryptfs_filldir, (void *)&buf); 129 file->f_pos = lower_file->f_pos; 130 if (rc < 0) 131 goto out; 132 if (buf.filldir_called && !buf.entries_written) 133 goto out; 134 if (rc >= 0) 135 fsstack_copy_attr_atime(inode, 136 lower_file->f_path.dentry->d_inode); 137 out: 138 return rc; 139 } 140 141 static void ecryptfs_vma_close(struct vm_area_struct *vma) 142 { 143 filemap_write_and_wait(vma->vm_file->f_mapping); 144 } 145 146 static const struct vm_operations_struct ecryptfs_file_vm_ops = { 147 .close = ecryptfs_vma_close, 148 .fault = filemap_fault, 149 }; 150 151 static int ecryptfs_file_mmap(struct file *file, struct vm_area_struct *vma) 152 { 153 int rc; 154 155 rc = generic_file_mmap(file, vma); 156 if (!rc) 157 vma->vm_ops = &ecryptfs_file_vm_ops; 158 159 return rc; 160 } 161 162 struct kmem_cache *ecryptfs_file_info_cache; 163 164 /** 165 * ecryptfs_open 166 * @inode: inode speciying file to open 167 * @file: Structure to return filled in 168 * 169 * Opens the file specified by inode. 170 * 171 * Returns zero on success; non-zero otherwise 172 */ 173 static int ecryptfs_open(struct inode *inode, struct file *file) 174 { 175 int rc = 0; 176 struct ecryptfs_crypt_stat *crypt_stat = NULL; 177 struct ecryptfs_mount_crypt_stat *mount_crypt_stat; 178 struct dentry *ecryptfs_dentry = file->f_path.dentry; 179 /* Private value of ecryptfs_dentry allocated in 180 * ecryptfs_lookup() */ 181 struct dentry *lower_dentry; 182 struct ecryptfs_file_info *file_info; 183 184 mount_crypt_stat = &ecryptfs_superblock_to_private( 185 ecryptfs_dentry->d_sb)->mount_crypt_stat; 186 if ((mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED) 187 && ((file->f_flags & O_WRONLY) || (file->f_flags & O_RDWR) 188 || (file->f_flags & O_CREAT) || (file->f_flags & O_TRUNC) 189 || (file->f_flags & O_APPEND))) { 190 printk(KERN_WARNING "Mount has encrypted view enabled; " 191 "files may only be read\n"); 192 rc = -EPERM; 193 goto out; 194 } 195 /* Released in ecryptfs_release or end of function if failure */ 196 file_info = kmem_cache_zalloc(ecryptfs_file_info_cache, GFP_KERNEL); 197 ecryptfs_set_file_private(file, file_info); 198 if (!file_info) { 199 ecryptfs_printk(KERN_ERR, 200 "Error attempting to allocate memory\n"); 201 rc = -ENOMEM; 202 goto out; 203 } 204 lower_dentry = ecryptfs_dentry_to_lower(ecryptfs_dentry); 205 crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat; 206 mutex_lock(&crypt_stat->cs_mutex); 207 if (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED)) { 208 ecryptfs_printk(KERN_DEBUG, "Setting flags for stat...\n"); 209 /* Policy code enabled in future release */ 210 crypt_stat->flags |= (ECRYPTFS_POLICY_APPLIED 211 | ECRYPTFS_ENCRYPTED); 212 } 213 mutex_unlock(&crypt_stat->cs_mutex); 214 rc = ecryptfs_get_lower_file(ecryptfs_dentry, inode); 215 if (rc) { 216 printk(KERN_ERR "%s: Error attempting to initialize " 217 "the lower file for the dentry with name " 218 "[%s]; rc = [%d]\n", __func__, 219 ecryptfs_dentry->d_name.name, rc); 220 goto out_free; 221 } 222 if ((ecryptfs_inode_to_private(inode)->lower_file->f_flags & O_ACCMODE) 223 == O_RDONLY && (file->f_flags & O_ACCMODE) != O_RDONLY) { 224 rc = -EPERM; 225 printk(KERN_WARNING "%s: Lower file is RO; eCryptfs " 226 "file must hence be opened RO\n", __func__); 227 goto out_put; 228 } 229 ecryptfs_set_file_lower( 230 file, ecryptfs_inode_to_private(inode)->lower_file); 231 if (S_ISDIR(ecryptfs_dentry->d_inode->i_mode)) { 232 ecryptfs_printk(KERN_DEBUG, "This is a directory\n"); 233 mutex_lock(&crypt_stat->cs_mutex); 234 crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED); 235 mutex_unlock(&crypt_stat->cs_mutex); 236 rc = 0; 237 goto out; 238 } 239 mutex_lock(&crypt_stat->cs_mutex); 240 if (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED) 241 || !(crypt_stat->flags & ECRYPTFS_KEY_VALID)) { 242 rc = ecryptfs_read_metadata(ecryptfs_dentry); 243 if (rc) { 244 ecryptfs_printk(KERN_DEBUG, 245 "Valid headers not found\n"); 246 if (!(mount_crypt_stat->flags 247 & ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED)) { 248 rc = -EIO; 249 printk(KERN_WARNING "Either the lower file " 250 "is not in a valid eCryptfs format, " 251 "or the key could not be retrieved. " 252 "Plaintext passthrough mode is not " 253 "enabled; returning -EIO\n"); 254 mutex_unlock(&crypt_stat->cs_mutex); 255 goto out_put; 256 } 257 rc = 0; 258 crypt_stat->flags &= ~(ECRYPTFS_I_SIZE_INITIALIZED 259 | ECRYPTFS_ENCRYPTED); 260 mutex_unlock(&crypt_stat->cs_mutex); 261 goto out; 262 } 263 } 264 mutex_unlock(&crypt_stat->cs_mutex); 265 ecryptfs_printk(KERN_DEBUG, "inode w/ addr = [0x%p], i_ino = " 266 "[0x%.16lx] size: [0x%.16llx]\n", inode, inode->i_ino, 267 (unsigned long long)i_size_read(inode)); 268 goto out; 269 out_put: 270 ecryptfs_put_lower_file(inode); 271 out_free: 272 kmem_cache_free(ecryptfs_file_info_cache, 273 ecryptfs_file_to_private(file)); 274 out: 275 return rc; 276 } 277 278 static int ecryptfs_flush(struct file *file, fl_owner_t td) 279 { 280 return file->f_mode & FMODE_WRITE 281 ? filemap_write_and_wait(file->f_mapping) : 0; 282 } 283 284 static int ecryptfs_release(struct inode *inode, struct file *file) 285 { 286 ecryptfs_put_lower_file(inode); 287 kmem_cache_free(ecryptfs_file_info_cache, 288 ecryptfs_file_to_private(file)); 289 return 0; 290 } 291 292 static int 293 ecryptfs_fsync(struct file *file, loff_t start, loff_t end, int datasync) 294 { 295 int rc = 0; 296 297 rc = generic_file_fsync(file, start, end, datasync); 298 if (rc) 299 goto out; 300 rc = vfs_fsync_range(ecryptfs_file_to_lower(file), start, end, 301 datasync); 302 out: 303 return rc; 304 } 305 306 static int ecryptfs_fasync(int fd, struct file *file, int flag) 307 { 308 int rc = 0; 309 struct file *lower_file = NULL; 310 311 lower_file = ecryptfs_file_to_lower(file); 312 if (lower_file->f_op && lower_file->f_op->fasync) 313 rc = lower_file->f_op->fasync(fd, lower_file, flag); 314 return rc; 315 } 316 317 static long 318 ecryptfs_unlocked_ioctl(struct file *file, unsigned int cmd, unsigned long arg) 319 { 320 struct file *lower_file = NULL; 321 long rc = -ENOTTY; 322 323 if (ecryptfs_file_to_private(file)) 324 lower_file = ecryptfs_file_to_lower(file); 325 if (lower_file && lower_file->f_op && lower_file->f_op->unlocked_ioctl) 326 rc = lower_file->f_op->unlocked_ioctl(lower_file, cmd, arg); 327 return rc; 328 } 329 330 #ifdef CONFIG_COMPAT 331 static long 332 ecryptfs_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg) 333 { 334 struct file *lower_file = NULL; 335 long rc = -ENOIOCTLCMD; 336 337 if (ecryptfs_file_to_private(file)) 338 lower_file = ecryptfs_file_to_lower(file); 339 if (lower_file && lower_file->f_op && lower_file->f_op->compat_ioctl) 340 rc = lower_file->f_op->compat_ioctl(lower_file, cmd, arg); 341 return rc; 342 } 343 #endif 344 345 const struct file_operations ecryptfs_dir_fops = { 346 .readdir = ecryptfs_readdir, 347 .read = generic_read_dir, 348 .unlocked_ioctl = ecryptfs_unlocked_ioctl, 349 #ifdef CONFIG_COMPAT 350 .compat_ioctl = ecryptfs_compat_ioctl, 351 #endif 352 .open = ecryptfs_open, 353 .flush = ecryptfs_flush, 354 .release = ecryptfs_release, 355 .fsync = ecryptfs_fsync, 356 .fasync = ecryptfs_fasync, 357 .splice_read = generic_file_splice_read, 358 .llseek = default_llseek, 359 }; 360 361 const struct file_operations ecryptfs_main_fops = { 362 .llseek = generic_file_llseek, 363 .read = do_sync_read, 364 .aio_read = ecryptfs_read_update_atime, 365 .write = do_sync_write, 366 .aio_write = generic_file_aio_write, 367 .readdir = ecryptfs_readdir, 368 .unlocked_ioctl = ecryptfs_unlocked_ioctl, 369 #ifdef CONFIG_COMPAT 370 .compat_ioctl = ecryptfs_compat_ioctl, 371 #endif 372 .mmap = ecryptfs_file_mmap, 373 .open = ecryptfs_open, 374 .flush = ecryptfs_flush, 375 .release = ecryptfs_release, 376 .fsync = ecryptfs_fsync, 377 .fasync = ecryptfs_fasync, 378 .splice_read = generic_file_splice_read, 379 }; 380