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/mount.h> 29 #include <linux/pagemap.h> 30 #include <linux/security.h> 31 #include <linux/smp_lock.h> 32 #include <linux/compat.h> 33 #include <linux/fs_stack.h> 34 #include "ecryptfs_kernel.h" 35 36 /** 37 * ecryptfs_llseek 38 * @file: File we are seeking in 39 * @offset: The offset to seek to 40 * @origin: 2 - offset from i_size; 1 - offset from f_pos 41 * 42 * Returns the position we have seeked to, or negative on error 43 */ 44 static loff_t ecryptfs_llseek(struct file *file, loff_t offset, int origin) 45 { 46 loff_t rv; 47 loff_t new_end_pos; 48 int rc; 49 int expanding_file = 0; 50 struct inode *inode = file->f_mapping->host; 51 52 /* If our offset is past the end of our file, we're going to 53 * need to grow it so we have a valid length of 0's */ 54 new_end_pos = offset; 55 switch (origin) { 56 case 2: 57 new_end_pos += i_size_read(inode); 58 expanding_file = 1; 59 break; 60 case 1: 61 new_end_pos += file->f_pos; 62 if (new_end_pos > i_size_read(inode)) { 63 ecryptfs_printk(KERN_DEBUG, "new_end_pos(=[0x%.16x]) " 64 "> i_size_read(inode)(=[0x%.16x])\n", 65 new_end_pos, i_size_read(inode)); 66 expanding_file = 1; 67 } 68 break; 69 default: 70 if (new_end_pos > i_size_read(inode)) { 71 ecryptfs_printk(KERN_DEBUG, "new_end_pos(=[0x%.16x]) " 72 "> i_size_read(inode)(=[0x%.16x])\n", 73 new_end_pos, i_size_read(inode)); 74 expanding_file = 1; 75 } 76 } 77 ecryptfs_printk(KERN_DEBUG, "new_end_pos = [0x%.16x]\n", new_end_pos); 78 if (expanding_file) { 79 rc = ecryptfs_truncate(file->f_path.dentry, new_end_pos); 80 if (rc) { 81 rv = rc; 82 ecryptfs_printk(KERN_ERR, "Error on attempt to " 83 "truncate to (higher) offset [0x%.16x];" 84 " rc = [%d]\n", new_end_pos, rc); 85 goto out; 86 } 87 } 88 rv = generic_file_llseek(file, offset, origin); 89 out: 90 return rv; 91 } 92 93 /** 94 * ecryptfs_read_update_atime 95 * 96 * generic_file_read updates the atime of upper layer inode. But, it 97 * doesn't give us a chance to update the atime of the lower layer 98 * inode. This function is a wrapper to generic_file_read. It 99 * updates the atime of the lower level inode if generic_file_read 100 * returns without any errors. This is to be used only for file reads. 101 * The function to be used for directory reads is ecryptfs_read. 102 */ 103 static ssize_t ecryptfs_read_update_atime(struct kiocb *iocb, 104 const struct iovec *iov, 105 unsigned long nr_segs, loff_t pos) 106 { 107 int rc; 108 struct dentry *lower_dentry; 109 struct vfsmount *lower_vfsmount; 110 struct file *file = iocb->ki_filp; 111 112 rc = generic_file_aio_read(iocb, iov, nr_segs, pos); 113 /* 114 * Even though this is a async interface, we need to wait 115 * for IO to finish to update atime 116 */ 117 if (-EIOCBQUEUED == rc) 118 rc = wait_on_sync_kiocb(iocb); 119 if (rc >= 0) { 120 lower_dentry = ecryptfs_dentry_to_lower(file->f_path.dentry); 121 lower_vfsmount = ecryptfs_dentry_to_lower_mnt(file->f_path.dentry); 122 touch_atime(lower_vfsmount, lower_dentry); 123 } 124 return rc; 125 } 126 127 struct ecryptfs_getdents_callback { 128 void *dirent; 129 struct dentry *dentry; 130 filldir_t filldir; 131 int err; 132 int filldir_called; 133 int entries_written; 134 }; 135 136 /* Inspired by generic filldir in fs/readir.c */ 137 static int 138 ecryptfs_filldir(void *dirent, const char *name, int namelen, loff_t offset, 139 u64 ino, unsigned int d_type) 140 { 141 struct ecryptfs_crypt_stat *crypt_stat; 142 struct ecryptfs_getdents_callback *buf = 143 (struct ecryptfs_getdents_callback *)dirent; 144 int rc; 145 int decoded_length; 146 char *decoded_name; 147 148 crypt_stat = ecryptfs_dentry_to_private(buf->dentry)->crypt_stat; 149 buf->filldir_called++; 150 decoded_length = ecryptfs_decode_filename(crypt_stat, name, namelen, 151 &decoded_name); 152 if (decoded_length < 0) { 153 rc = decoded_length; 154 goto out; 155 } 156 rc = buf->filldir(buf->dirent, decoded_name, decoded_length, offset, 157 ino, d_type); 158 kfree(decoded_name); 159 if (rc >= 0) 160 buf->entries_written++; 161 out: 162 return rc; 163 } 164 165 /** 166 * ecryptfs_readdir 167 * @file: The ecryptfs file struct 168 * @dirent: Directory entry 169 * @filldir: The filldir callback function 170 */ 171 static int ecryptfs_readdir(struct file *file, void *dirent, filldir_t filldir) 172 { 173 int rc; 174 struct file *lower_file; 175 struct inode *inode; 176 struct ecryptfs_getdents_callback buf; 177 178 lower_file = ecryptfs_file_to_lower(file); 179 lower_file->f_pos = file->f_pos; 180 inode = file->f_path.dentry->d_inode; 181 memset(&buf, 0, sizeof(buf)); 182 buf.dirent = dirent; 183 buf.dentry = file->f_path.dentry; 184 buf.filldir = filldir; 185 retry: 186 buf.filldir_called = 0; 187 buf.entries_written = 0; 188 buf.err = 0; 189 rc = vfs_readdir(lower_file, ecryptfs_filldir, (void *)&buf); 190 if (buf.err) 191 rc = buf.err; 192 if (buf.filldir_called && !buf.entries_written) 193 goto retry; 194 file->f_pos = lower_file->f_pos; 195 if (rc >= 0) 196 fsstack_copy_attr_atime(inode, lower_file->f_path.dentry->d_inode); 197 return rc; 198 } 199 200 struct kmem_cache *ecryptfs_file_info_cache; 201 202 int ecryptfs_open_lower_file(struct file **lower_file, 203 struct dentry *lower_dentry, 204 struct vfsmount *lower_mnt, int flags) 205 { 206 int rc = 0; 207 208 flags |= O_LARGEFILE; 209 dget(lower_dentry); 210 mntget(lower_mnt); 211 *lower_file = dentry_open(lower_dentry, lower_mnt, flags); 212 if (IS_ERR(*lower_file)) { 213 printk(KERN_ERR "Error opening lower file for lower_dentry " 214 "[0x%p], lower_mnt [0x%p], and flags [0x%x]\n", 215 lower_dentry, lower_mnt, flags); 216 rc = PTR_ERR(*lower_file); 217 *lower_file = NULL; 218 goto out; 219 } 220 out: 221 return rc; 222 } 223 224 int ecryptfs_close_lower_file(struct file *lower_file) 225 { 226 fput(lower_file); 227 return 0; 228 } 229 230 /** 231 * ecryptfs_open 232 * @inode: inode speciying file to open 233 * @file: Structure to return filled in 234 * 235 * Opens the file specified by inode. 236 * 237 * Returns zero on success; non-zero otherwise 238 */ 239 static int ecryptfs_open(struct inode *inode, struct file *file) 240 { 241 int rc = 0; 242 struct ecryptfs_crypt_stat *crypt_stat = NULL; 243 struct ecryptfs_mount_crypt_stat *mount_crypt_stat; 244 struct dentry *ecryptfs_dentry = file->f_path.dentry; 245 /* Private value of ecryptfs_dentry allocated in 246 * ecryptfs_lookup() */ 247 struct dentry *lower_dentry = ecryptfs_dentry_to_lower(ecryptfs_dentry); 248 struct inode *lower_inode = NULL; 249 struct file *lower_file = NULL; 250 struct vfsmount *lower_mnt; 251 struct ecryptfs_file_info *file_info; 252 int lower_flags; 253 254 mount_crypt_stat = &ecryptfs_superblock_to_private( 255 ecryptfs_dentry->d_sb)->mount_crypt_stat; 256 if ((mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED) 257 && ((file->f_flags & O_WRONLY) || (file->f_flags & O_RDWR) 258 || (file->f_flags & O_CREAT) || (file->f_flags & O_TRUNC) 259 || (file->f_flags & O_APPEND))) { 260 printk(KERN_WARNING "Mount has encrypted view enabled; " 261 "files may only be read\n"); 262 rc = -EPERM; 263 goto out; 264 } 265 /* Released in ecryptfs_release or end of function if failure */ 266 file_info = kmem_cache_zalloc(ecryptfs_file_info_cache, GFP_KERNEL); 267 ecryptfs_set_file_private(file, file_info); 268 if (!file_info) { 269 ecryptfs_printk(KERN_ERR, 270 "Error attempting to allocate memory\n"); 271 rc = -ENOMEM; 272 goto out; 273 } 274 lower_dentry = ecryptfs_dentry_to_lower(ecryptfs_dentry); 275 crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat; 276 mutex_lock(&crypt_stat->cs_mutex); 277 if (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED)) { 278 ecryptfs_printk(KERN_DEBUG, "Setting flags for stat...\n"); 279 /* Policy code enabled in future release */ 280 crypt_stat->flags |= ECRYPTFS_POLICY_APPLIED; 281 crypt_stat->flags |= ECRYPTFS_ENCRYPTED; 282 } 283 mutex_unlock(&crypt_stat->cs_mutex); 284 lower_flags = file->f_flags; 285 if ((lower_flags & O_ACCMODE) == O_WRONLY) 286 lower_flags = (lower_flags & O_ACCMODE) | O_RDWR; 287 if (file->f_flags & O_APPEND) 288 lower_flags &= ~O_APPEND; 289 lower_mnt = ecryptfs_dentry_to_lower_mnt(ecryptfs_dentry); 290 /* Corresponding fput() in ecryptfs_release() */ 291 if ((rc = ecryptfs_open_lower_file(&lower_file, lower_dentry, lower_mnt, 292 lower_flags))) { 293 ecryptfs_printk(KERN_ERR, "Error opening lower file\n"); 294 goto out_puts; 295 } 296 ecryptfs_set_file_lower(file, lower_file); 297 /* Isn't this check the same as the one in lookup? */ 298 lower_inode = lower_dentry->d_inode; 299 if (S_ISDIR(ecryptfs_dentry->d_inode->i_mode)) { 300 ecryptfs_printk(KERN_DEBUG, "This is a directory\n"); 301 crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED); 302 rc = 0; 303 goto out; 304 } 305 mutex_lock(&crypt_stat->cs_mutex); 306 if (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED) 307 || !(crypt_stat->flags & ECRYPTFS_KEY_VALID)) { 308 rc = ecryptfs_read_metadata(ecryptfs_dentry, lower_file); 309 if (rc) { 310 ecryptfs_printk(KERN_DEBUG, 311 "Valid headers not found\n"); 312 if (!(mount_crypt_stat->flags 313 & ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED)) { 314 rc = -EIO; 315 printk(KERN_WARNING "Attempt to read file that " 316 "is not in a valid eCryptfs format, " 317 "and plaintext passthrough mode is not " 318 "enabled; returning -EIO\n"); 319 mutex_unlock(&crypt_stat->cs_mutex); 320 goto out_puts; 321 } 322 rc = 0; 323 crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED); 324 mutex_unlock(&crypt_stat->cs_mutex); 325 goto out; 326 } 327 } 328 mutex_unlock(&crypt_stat->cs_mutex); 329 ecryptfs_printk(KERN_DEBUG, "inode w/ addr = [0x%p], i_ino = [0x%.16x] " 330 "size: [0x%.16x]\n", inode, inode->i_ino, 331 i_size_read(inode)); 332 ecryptfs_set_file_lower(file, lower_file); 333 goto out; 334 out_puts: 335 mntput(lower_mnt); 336 dput(lower_dentry); 337 kmem_cache_free(ecryptfs_file_info_cache, 338 ecryptfs_file_to_private(file)); 339 out: 340 return rc; 341 } 342 343 static int ecryptfs_flush(struct file *file, fl_owner_t td) 344 { 345 int rc = 0; 346 struct file *lower_file = NULL; 347 348 lower_file = ecryptfs_file_to_lower(file); 349 if (lower_file->f_op && lower_file->f_op->flush) 350 rc = lower_file->f_op->flush(lower_file, td); 351 return rc; 352 } 353 354 static int ecryptfs_release(struct inode *inode, struct file *file) 355 { 356 struct file *lower_file = ecryptfs_file_to_lower(file); 357 struct ecryptfs_file_info *file_info = ecryptfs_file_to_private(file); 358 struct inode *lower_inode = ecryptfs_inode_to_lower(inode); 359 int rc; 360 361 if ((rc = ecryptfs_close_lower_file(lower_file))) { 362 printk(KERN_ERR "Error closing lower_file\n"); 363 goto out; 364 } 365 inode->i_blocks = lower_inode->i_blocks; 366 kmem_cache_free(ecryptfs_file_info_cache, file_info); 367 out: 368 return rc; 369 } 370 371 static int 372 ecryptfs_fsync(struct file *file, struct dentry *dentry, int datasync) 373 { 374 struct file *lower_file = ecryptfs_file_to_lower(file); 375 struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry); 376 struct inode *lower_inode = lower_dentry->d_inode; 377 int rc = -EINVAL; 378 379 if (lower_inode->i_fop->fsync) { 380 mutex_lock(&lower_inode->i_mutex); 381 rc = lower_inode->i_fop->fsync(lower_file, lower_dentry, 382 datasync); 383 mutex_unlock(&lower_inode->i_mutex); 384 } 385 return rc; 386 } 387 388 static int ecryptfs_fasync(int fd, struct file *file, int flag) 389 { 390 int rc = 0; 391 struct file *lower_file = NULL; 392 393 lower_file = ecryptfs_file_to_lower(file); 394 if (lower_file->f_op && lower_file->f_op->fasync) 395 rc = lower_file->f_op->fasync(fd, lower_file, flag); 396 return rc; 397 } 398 399 static ssize_t ecryptfs_sendfile(struct file *file, loff_t * ppos, 400 size_t count, read_actor_t actor, void *target) 401 { 402 struct file *lower_file = NULL; 403 int rc = -EINVAL; 404 405 lower_file = ecryptfs_file_to_lower(file); 406 if (lower_file->f_op && lower_file->f_op->sendfile) 407 rc = lower_file->f_op->sendfile(lower_file, ppos, count, 408 actor, target); 409 410 return rc; 411 } 412 413 static int ecryptfs_ioctl(struct inode *inode, struct file *file, 414 unsigned int cmd, unsigned long arg); 415 416 const struct file_operations ecryptfs_dir_fops = { 417 .readdir = ecryptfs_readdir, 418 .ioctl = ecryptfs_ioctl, 419 .mmap = generic_file_mmap, 420 .open = ecryptfs_open, 421 .flush = ecryptfs_flush, 422 .release = ecryptfs_release, 423 .fsync = ecryptfs_fsync, 424 .fasync = ecryptfs_fasync, 425 .sendfile = ecryptfs_sendfile, 426 }; 427 428 const struct file_operations ecryptfs_main_fops = { 429 .llseek = ecryptfs_llseek, 430 .read = do_sync_read, 431 .aio_read = ecryptfs_read_update_atime, 432 .write = do_sync_write, 433 .aio_write = generic_file_aio_write, 434 .readdir = ecryptfs_readdir, 435 .ioctl = ecryptfs_ioctl, 436 .mmap = generic_file_mmap, 437 .open = ecryptfs_open, 438 .flush = ecryptfs_flush, 439 .release = ecryptfs_release, 440 .fsync = ecryptfs_fsync, 441 .fasync = ecryptfs_fasync, 442 .sendfile = ecryptfs_sendfile, 443 }; 444 445 static int 446 ecryptfs_ioctl(struct inode *inode, struct file *file, unsigned int cmd, 447 unsigned long arg) 448 { 449 int rc = 0; 450 struct file *lower_file = NULL; 451 452 if (ecryptfs_file_to_private(file)) 453 lower_file = ecryptfs_file_to_lower(file); 454 if (lower_file && lower_file->f_op && lower_file->f_op->ioctl) 455 rc = lower_file->f_op->ioctl(ecryptfs_inode_to_lower(inode), 456 lower_file, cmd, arg); 457 else 458 rc = -ENOTTY; 459 return rc; 460 } 461