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 dentry *lower_dentry; 52 struct vfsmount *lower_vfsmount; 53 struct file *file = iocb->ki_filp; 54 55 rc = generic_file_aio_read(iocb, iov, nr_segs, pos); 56 /* 57 * Even though this is a async interface, we need to wait 58 * for IO to finish to update atime 59 */ 60 if (-EIOCBQUEUED == rc) 61 rc = wait_on_sync_kiocb(iocb); 62 if (rc >= 0) { 63 lower_dentry = ecryptfs_dentry_to_lower(file->f_path.dentry); 64 lower_vfsmount = ecryptfs_dentry_to_lower_mnt(file->f_path.dentry); 65 touch_atime(lower_vfsmount, lower_dentry); 66 } 67 return rc; 68 } 69 70 struct ecryptfs_getdents_callback { 71 void *dirent; 72 struct dentry *dentry; 73 filldir_t filldir; 74 int filldir_called; 75 int entries_written; 76 }; 77 78 /* Inspired by generic filldir in fs/readdir.c */ 79 static int 80 ecryptfs_filldir(void *dirent, const char *lower_name, int lower_namelen, 81 loff_t offset, u64 ino, unsigned int d_type) 82 { 83 struct ecryptfs_getdents_callback *buf = 84 (struct ecryptfs_getdents_callback *)dirent; 85 size_t name_size; 86 char *name; 87 int rc; 88 89 buf->filldir_called++; 90 rc = ecryptfs_decode_and_decrypt_filename(&name, &name_size, 91 buf->dentry, lower_name, 92 lower_namelen); 93 if (rc) { 94 printk(KERN_ERR "%s: Error attempting to decode and decrypt " 95 "filename [%s]; rc = [%d]\n", __func__, lower_name, 96 rc); 97 goto out; 98 } 99 rc = buf->filldir(buf->dirent, name, name_size, offset, ino, d_type); 100 kfree(name); 101 if (rc >= 0) 102 buf->entries_written++; 103 out: 104 return rc; 105 } 106 107 /** 108 * ecryptfs_readdir 109 * @file: The eCryptfs directory file 110 * @dirent: Directory entry handle 111 * @filldir: The filldir callback function 112 */ 113 static int ecryptfs_readdir(struct file *file, void *dirent, filldir_t filldir) 114 { 115 int rc; 116 struct file *lower_file; 117 struct inode *inode; 118 struct ecryptfs_getdents_callback buf; 119 120 lower_file = ecryptfs_file_to_lower(file); 121 lower_file->f_pos = file->f_pos; 122 inode = file->f_path.dentry->d_inode; 123 memset(&buf, 0, sizeof(buf)); 124 buf.dirent = dirent; 125 buf.dentry = file->f_path.dentry; 126 buf.filldir = filldir; 127 buf.filldir_called = 0; 128 buf.entries_written = 0; 129 rc = vfs_readdir(lower_file, ecryptfs_filldir, (void *)&buf); 130 file->f_pos = lower_file->f_pos; 131 if (rc < 0) 132 goto out; 133 if (buf.filldir_called && !buf.entries_written) 134 goto out; 135 if (rc >= 0) 136 fsstack_copy_attr_atime(inode, 137 lower_file->f_path.dentry->d_inode); 138 out: 139 return rc; 140 } 141 142 struct kmem_cache *ecryptfs_file_info_cache; 143 144 /** 145 * ecryptfs_open 146 * @inode: inode speciying file to open 147 * @file: Structure to return filled in 148 * 149 * Opens the file specified by inode. 150 * 151 * Returns zero on success; non-zero otherwise 152 */ 153 static int ecryptfs_open(struct inode *inode, struct file *file) 154 { 155 int rc = 0; 156 struct ecryptfs_crypt_stat *crypt_stat = NULL; 157 struct ecryptfs_mount_crypt_stat *mount_crypt_stat; 158 struct dentry *ecryptfs_dentry = file->f_path.dentry; 159 /* Private value of ecryptfs_dentry allocated in 160 * ecryptfs_lookup() */ 161 struct dentry *lower_dentry; 162 struct ecryptfs_file_info *file_info; 163 164 mount_crypt_stat = &ecryptfs_superblock_to_private( 165 ecryptfs_dentry->d_sb)->mount_crypt_stat; 166 if ((mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED) 167 && ((file->f_flags & O_WRONLY) || (file->f_flags & O_RDWR) 168 || (file->f_flags & O_CREAT) || (file->f_flags & O_TRUNC) 169 || (file->f_flags & O_APPEND))) { 170 printk(KERN_WARNING "Mount has encrypted view enabled; " 171 "files may only be read\n"); 172 rc = -EPERM; 173 goto out; 174 } 175 /* Released in ecryptfs_release or end of function if failure */ 176 file_info = kmem_cache_zalloc(ecryptfs_file_info_cache, GFP_KERNEL); 177 ecryptfs_set_file_private(file, file_info); 178 if (!file_info) { 179 ecryptfs_printk(KERN_ERR, 180 "Error attempting to allocate memory\n"); 181 rc = -ENOMEM; 182 goto out; 183 } 184 lower_dentry = ecryptfs_dentry_to_lower(ecryptfs_dentry); 185 crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat; 186 mutex_lock(&crypt_stat->cs_mutex); 187 if (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED)) { 188 ecryptfs_printk(KERN_DEBUG, "Setting flags for stat...\n"); 189 /* Policy code enabled in future release */ 190 crypt_stat->flags |= (ECRYPTFS_POLICY_APPLIED 191 | ECRYPTFS_ENCRYPTED); 192 } 193 mutex_unlock(&crypt_stat->cs_mutex); 194 rc = ecryptfs_init_persistent_file(ecryptfs_dentry); 195 if (rc) { 196 printk(KERN_ERR "%s: Error attempting to initialize " 197 "the persistent file for the dentry with name " 198 "[%s]; rc = [%d]\n", __func__, 199 ecryptfs_dentry->d_name.name, rc); 200 goto out_free; 201 } 202 if ((ecryptfs_inode_to_private(inode)->lower_file->f_flags & O_ACCMODE) 203 == O_RDONLY && (file->f_flags & O_ACCMODE) != O_RDONLY) { 204 rc = -EPERM; 205 printk(KERN_WARNING "%s: Lower persistent file is RO; eCryptfs " 206 "file must hence be opened RO\n", __func__); 207 goto out_free; 208 } 209 ecryptfs_set_file_lower( 210 file, ecryptfs_inode_to_private(inode)->lower_file); 211 if (S_ISDIR(ecryptfs_dentry->d_inode->i_mode)) { 212 ecryptfs_printk(KERN_DEBUG, "This is a directory\n"); 213 mutex_lock(&crypt_stat->cs_mutex); 214 crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED); 215 mutex_unlock(&crypt_stat->cs_mutex); 216 rc = 0; 217 goto out; 218 } 219 mutex_lock(&crypt_stat->cs_mutex); 220 if (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED) 221 || !(crypt_stat->flags & ECRYPTFS_KEY_VALID)) { 222 rc = ecryptfs_read_metadata(ecryptfs_dentry); 223 if (rc) { 224 ecryptfs_printk(KERN_DEBUG, 225 "Valid headers not found\n"); 226 if (!(mount_crypt_stat->flags 227 & ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED)) { 228 rc = -EIO; 229 printk(KERN_WARNING "Either the lower file " 230 "is not in a valid eCryptfs format, " 231 "or the key could not be retrieved. " 232 "Plaintext passthrough mode is not " 233 "enabled; returning -EIO\n"); 234 mutex_unlock(&crypt_stat->cs_mutex); 235 goto out_free; 236 } 237 rc = 0; 238 crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED); 239 mutex_unlock(&crypt_stat->cs_mutex); 240 goto out; 241 } 242 } 243 mutex_unlock(&crypt_stat->cs_mutex); 244 ecryptfs_printk(KERN_DEBUG, "inode w/ addr = [0x%p], i_ino = " 245 "[0x%.16lx] size: [0x%.16llx]\n", inode, inode->i_ino, 246 (unsigned long long)i_size_read(inode)); 247 goto out; 248 out_free: 249 kmem_cache_free(ecryptfs_file_info_cache, 250 ecryptfs_file_to_private(file)); 251 out: 252 return rc; 253 } 254 255 static int ecryptfs_flush(struct file *file, fl_owner_t td) 256 { 257 int rc = 0; 258 struct file *lower_file = NULL; 259 260 lower_file = ecryptfs_file_to_lower(file); 261 if (lower_file->f_op && lower_file->f_op->flush) 262 rc = lower_file->f_op->flush(lower_file, td); 263 return rc; 264 } 265 266 static int ecryptfs_release(struct inode *inode, struct file *file) 267 { 268 kmem_cache_free(ecryptfs_file_info_cache, 269 ecryptfs_file_to_private(file)); 270 return 0; 271 } 272 273 static int 274 ecryptfs_fsync(struct file *file, int datasync) 275 { 276 return vfs_fsync(ecryptfs_file_to_lower(file), datasync); 277 } 278 279 static int ecryptfs_fasync(int fd, struct file *file, int flag) 280 { 281 int rc = 0; 282 struct file *lower_file = NULL; 283 284 lower_file = ecryptfs_file_to_lower(file); 285 if (lower_file->f_op && lower_file->f_op->fasync) 286 rc = lower_file->f_op->fasync(fd, lower_file, flag); 287 return rc; 288 } 289 290 static long 291 ecryptfs_unlocked_ioctl(struct file *file, unsigned int cmd, unsigned long arg) 292 { 293 struct file *lower_file = NULL; 294 long rc = -ENOTTY; 295 296 if (ecryptfs_file_to_private(file)) 297 lower_file = ecryptfs_file_to_lower(file); 298 if (lower_file && lower_file->f_op && lower_file->f_op->unlocked_ioctl) 299 rc = lower_file->f_op->unlocked_ioctl(lower_file, cmd, arg); 300 return rc; 301 } 302 303 #ifdef CONFIG_COMPAT 304 static long 305 ecryptfs_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg) 306 { 307 struct file *lower_file = NULL; 308 long rc = -ENOIOCTLCMD; 309 310 if (ecryptfs_file_to_private(file)) 311 lower_file = ecryptfs_file_to_lower(file); 312 if (lower_file && lower_file->f_op && lower_file->f_op->compat_ioctl) 313 rc = lower_file->f_op->compat_ioctl(lower_file, cmd, arg); 314 return rc; 315 } 316 #endif 317 318 const struct file_operations ecryptfs_dir_fops = { 319 .readdir = ecryptfs_readdir, 320 .read = generic_read_dir, 321 .unlocked_ioctl = ecryptfs_unlocked_ioctl, 322 #ifdef CONFIG_COMPAT 323 .compat_ioctl = ecryptfs_compat_ioctl, 324 #endif 325 .open = ecryptfs_open, 326 .flush = ecryptfs_flush, 327 .release = ecryptfs_release, 328 .fsync = ecryptfs_fsync, 329 .fasync = ecryptfs_fasync, 330 .splice_read = generic_file_splice_read, 331 .llseek = default_llseek, 332 }; 333 334 const struct file_operations ecryptfs_main_fops = { 335 .llseek = generic_file_llseek, 336 .read = do_sync_read, 337 .aio_read = ecryptfs_read_update_atime, 338 .write = do_sync_write, 339 .aio_write = generic_file_aio_write, 340 .readdir = ecryptfs_readdir, 341 .unlocked_ioctl = ecryptfs_unlocked_ioctl, 342 #ifdef CONFIG_COMPAT 343 .compat_ioctl = ecryptfs_compat_ioctl, 344 #endif 345 .mmap = generic_file_mmap, 346 .open = ecryptfs_open, 347 .flush = ecryptfs_flush, 348 .release = ecryptfs_release, 349 .fsync = ecryptfs_fsync, 350 .fasync = ecryptfs_fasync, 351 .splice_read = generic_file_splice_read, 352 }; 353