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 struct kmem_cache *ecryptfs_file_info_cache; 142 143 static int read_or_initialize_metadata(struct dentry *dentry) 144 { 145 struct inode *inode = dentry->d_inode; 146 struct ecryptfs_mount_crypt_stat *mount_crypt_stat; 147 struct ecryptfs_crypt_stat *crypt_stat; 148 int rc; 149 150 crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat; 151 mount_crypt_stat = &ecryptfs_superblock_to_private( 152 inode->i_sb)->mount_crypt_stat; 153 mutex_lock(&crypt_stat->cs_mutex); 154 155 if (crypt_stat->flags & ECRYPTFS_POLICY_APPLIED && 156 crypt_stat->flags & ECRYPTFS_KEY_VALID) { 157 rc = 0; 158 goto out; 159 } 160 161 rc = ecryptfs_read_metadata(dentry); 162 if (!rc) 163 goto out; 164 165 if (mount_crypt_stat->flags & ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED) { 166 crypt_stat->flags &= ~(ECRYPTFS_I_SIZE_INITIALIZED 167 | ECRYPTFS_ENCRYPTED); 168 rc = 0; 169 goto out; 170 } 171 172 if (!(mount_crypt_stat->flags & ECRYPTFS_XATTR_METADATA_ENABLED) && 173 !i_size_read(ecryptfs_inode_to_lower(inode))) { 174 rc = ecryptfs_initialize_file(dentry, inode); 175 if (!rc) 176 goto out; 177 } 178 179 rc = -EIO; 180 out: 181 mutex_unlock(&crypt_stat->cs_mutex); 182 return rc; 183 } 184 185 /** 186 * ecryptfs_open 187 * @inode: inode speciying file to open 188 * @file: Structure to return filled in 189 * 190 * Opens the file specified by inode. 191 * 192 * Returns zero on success; non-zero otherwise 193 */ 194 static int ecryptfs_open(struct inode *inode, struct file *file) 195 { 196 int rc = 0; 197 struct ecryptfs_crypt_stat *crypt_stat = NULL; 198 struct ecryptfs_mount_crypt_stat *mount_crypt_stat; 199 struct dentry *ecryptfs_dentry = file->f_path.dentry; 200 /* Private value of ecryptfs_dentry allocated in 201 * ecryptfs_lookup() */ 202 struct dentry *lower_dentry; 203 struct ecryptfs_file_info *file_info; 204 205 mount_crypt_stat = &ecryptfs_superblock_to_private( 206 ecryptfs_dentry->d_sb)->mount_crypt_stat; 207 if ((mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED) 208 && ((file->f_flags & O_WRONLY) || (file->f_flags & O_RDWR) 209 || (file->f_flags & O_CREAT) || (file->f_flags & O_TRUNC) 210 || (file->f_flags & O_APPEND))) { 211 printk(KERN_WARNING "Mount has encrypted view enabled; " 212 "files may only be read\n"); 213 rc = -EPERM; 214 goto out; 215 } 216 /* Released in ecryptfs_release or end of function if failure */ 217 file_info = kmem_cache_zalloc(ecryptfs_file_info_cache, GFP_KERNEL); 218 ecryptfs_set_file_private(file, file_info); 219 if (!file_info) { 220 ecryptfs_printk(KERN_ERR, 221 "Error attempting to allocate memory\n"); 222 rc = -ENOMEM; 223 goto out; 224 } 225 lower_dentry = ecryptfs_dentry_to_lower(ecryptfs_dentry); 226 crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat; 227 mutex_lock(&crypt_stat->cs_mutex); 228 if (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED)) { 229 ecryptfs_printk(KERN_DEBUG, "Setting flags for stat...\n"); 230 /* Policy code enabled in future release */ 231 crypt_stat->flags |= (ECRYPTFS_POLICY_APPLIED 232 | ECRYPTFS_ENCRYPTED); 233 } 234 mutex_unlock(&crypt_stat->cs_mutex); 235 rc = ecryptfs_get_lower_file(ecryptfs_dentry, inode); 236 if (rc) { 237 printk(KERN_ERR "%s: Error attempting to initialize " 238 "the lower file for the dentry with name " 239 "[%s]; rc = [%d]\n", __func__, 240 ecryptfs_dentry->d_name.name, rc); 241 goto out_free; 242 } 243 if ((ecryptfs_inode_to_private(inode)->lower_file->f_flags & O_ACCMODE) 244 == O_RDONLY && (file->f_flags & O_ACCMODE) != O_RDONLY) { 245 rc = -EPERM; 246 printk(KERN_WARNING "%s: Lower file is RO; eCryptfs " 247 "file must hence be opened RO\n", __func__); 248 goto out_put; 249 } 250 ecryptfs_set_file_lower( 251 file, ecryptfs_inode_to_private(inode)->lower_file); 252 if (S_ISDIR(ecryptfs_dentry->d_inode->i_mode)) { 253 ecryptfs_printk(KERN_DEBUG, "This is a directory\n"); 254 mutex_lock(&crypt_stat->cs_mutex); 255 crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED); 256 mutex_unlock(&crypt_stat->cs_mutex); 257 rc = 0; 258 goto out; 259 } 260 rc = read_or_initialize_metadata(ecryptfs_dentry); 261 if (rc) 262 goto out_put; 263 ecryptfs_printk(KERN_DEBUG, "inode w/ addr = [0x%p], i_ino = " 264 "[0x%.16lx] size: [0x%.16llx]\n", inode, inode->i_ino, 265 (unsigned long long)i_size_read(inode)); 266 goto out; 267 out_put: 268 ecryptfs_put_lower_file(inode); 269 out_free: 270 kmem_cache_free(ecryptfs_file_info_cache, 271 ecryptfs_file_to_private(file)); 272 out: 273 return rc; 274 } 275 276 static int ecryptfs_flush(struct file *file, fl_owner_t td) 277 { 278 struct file *lower_file = ecryptfs_file_to_lower(file); 279 280 if (lower_file->f_op && lower_file->f_op->flush) { 281 filemap_write_and_wait(file->f_mapping); 282 return lower_file->f_op->flush(lower_file, td); 283 } 284 285 return 0; 286 } 287 288 static int ecryptfs_release(struct inode *inode, struct file *file) 289 { 290 ecryptfs_put_lower_file(inode); 291 kmem_cache_free(ecryptfs_file_info_cache, 292 ecryptfs_file_to_private(file)); 293 return 0; 294 } 295 296 static int 297 ecryptfs_fsync(struct file *file, loff_t start, loff_t end, int datasync) 298 { 299 return vfs_fsync(ecryptfs_file_to_lower(file), datasync); 300 } 301 302 static int ecryptfs_fasync(int fd, struct file *file, int flag) 303 { 304 int rc = 0; 305 struct file *lower_file = NULL; 306 307 lower_file = ecryptfs_file_to_lower(file); 308 if (lower_file->f_op && lower_file->f_op->fasync) 309 rc = lower_file->f_op->fasync(fd, lower_file, flag); 310 return rc; 311 } 312 313 static long 314 ecryptfs_unlocked_ioctl(struct file *file, unsigned int cmd, unsigned long arg) 315 { 316 struct file *lower_file = NULL; 317 long rc = -ENOTTY; 318 319 if (ecryptfs_file_to_private(file)) 320 lower_file = ecryptfs_file_to_lower(file); 321 if (lower_file && lower_file->f_op && lower_file->f_op->unlocked_ioctl) 322 rc = lower_file->f_op->unlocked_ioctl(lower_file, cmd, arg); 323 return rc; 324 } 325 326 #ifdef CONFIG_COMPAT 327 static long 328 ecryptfs_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg) 329 { 330 struct file *lower_file = NULL; 331 long rc = -ENOIOCTLCMD; 332 333 if (ecryptfs_file_to_private(file)) 334 lower_file = ecryptfs_file_to_lower(file); 335 if (lower_file && lower_file->f_op && lower_file->f_op->compat_ioctl) 336 rc = lower_file->f_op->compat_ioctl(lower_file, cmd, arg); 337 return rc; 338 } 339 #endif 340 341 const struct file_operations ecryptfs_dir_fops = { 342 .readdir = ecryptfs_readdir, 343 .read = generic_read_dir, 344 .unlocked_ioctl = ecryptfs_unlocked_ioctl, 345 #ifdef CONFIG_COMPAT 346 .compat_ioctl = ecryptfs_compat_ioctl, 347 #endif 348 .open = ecryptfs_open, 349 .flush = ecryptfs_flush, 350 .release = ecryptfs_release, 351 .fsync = ecryptfs_fsync, 352 .fasync = ecryptfs_fasync, 353 .splice_read = generic_file_splice_read, 354 .llseek = default_llseek, 355 }; 356 357 const struct file_operations ecryptfs_main_fops = { 358 .llseek = generic_file_llseek, 359 .read = do_sync_read, 360 .aio_read = ecryptfs_read_update_atime, 361 .write = do_sync_write, 362 .aio_write = generic_file_aio_write, 363 .readdir = ecryptfs_readdir, 364 .unlocked_ioctl = ecryptfs_unlocked_ioctl, 365 #ifdef CONFIG_COMPAT 366 .compat_ioctl = ecryptfs_compat_ioctl, 367 #endif 368 .mmap = generic_file_mmap, 369 .open = ecryptfs_open, 370 .flush = ecryptfs_flush, 371 .release = ecryptfs_release, 372 .fsync = ecryptfs_fsync, 373 .fasync = ecryptfs_fasync, 374 .splice_read = generic_file_splice_read, 375 }; 376