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/compat.h> 32 #include <linux/fs_stack.h> 33 #include <linux/smp_lock.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 int 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 *name, int namelen, loff_t offset, 81 u64 ino, unsigned int d_type) 82 { 83 struct ecryptfs_crypt_stat *crypt_stat; 84 struct ecryptfs_getdents_callback *buf = 85 (struct ecryptfs_getdents_callback *)dirent; 86 int rc; 87 int decoded_length; 88 char *decoded_name; 89 90 crypt_stat = ecryptfs_dentry_to_private(buf->dentry)->crypt_stat; 91 buf->filldir_called++; 92 decoded_length = ecryptfs_decode_filename(crypt_stat, name, namelen, 93 &decoded_name); 94 if (decoded_length < 0) { 95 rc = decoded_length; 96 goto out; 97 } 98 rc = buf->filldir(buf->dirent, decoded_name, decoded_length, offset, 99 ino, d_type); 100 kfree(decoded_name); 101 if (rc >= 0) 102 buf->entries_written++; 103 out: 104 return rc; 105 } 106 107 /** 108 * ecryptfs_readdir 109 * @file: The ecryptfs file struct 110 * @dirent: Directory entry 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 = ecryptfs_dentry_to_lower(ecryptfs_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 if ((ecryptfs_inode_to_private(inode)->lower_file->f_flags & O_RDONLY) 195 && !(file->f_flags & O_RDONLY)) { 196 rc = -EPERM; 197 printk(KERN_WARNING "%s: Lower persistent file is RO; eCryptfs " 198 "file must hence be opened RO\n", __func__); 199 goto out; 200 } 201 if (!ecryptfs_inode_to_private(inode)->lower_file) { 202 rc = ecryptfs_init_persistent_file(ecryptfs_dentry); 203 if (rc) { 204 printk(KERN_ERR "%s: Error attempting to initialize " 205 "the persistent file for the dentry with name " 206 "[%s]; rc = [%d]\n", __func__, 207 ecryptfs_dentry->d_name.name, rc); 208 goto out; 209 } 210 } 211 ecryptfs_set_file_lower( 212 file, ecryptfs_inode_to_private(inode)->lower_file); 213 if (S_ISDIR(ecryptfs_dentry->d_inode->i_mode)) { 214 ecryptfs_printk(KERN_DEBUG, "This is a directory\n"); 215 mutex_lock(&crypt_stat->cs_mutex); 216 crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED); 217 mutex_unlock(&crypt_stat->cs_mutex); 218 rc = 0; 219 goto out; 220 } 221 mutex_lock(&crypt_stat->cs_mutex); 222 if (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED) 223 || !(crypt_stat->flags & ECRYPTFS_KEY_VALID)) { 224 rc = ecryptfs_read_metadata(ecryptfs_dentry); 225 if (rc) { 226 ecryptfs_printk(KERN_DEBUG, 227 "Valid headers not found\n"); 228 if (!(mount_crypt_stat->flags 229 & ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED)) { 230 rc = -EIO; 231 printk(KERN_WARNING "Either the lower file " 232 "is not in a valid eCryptfs format, " 233 "or the key could not be retrieved. " 234 "Plaintext passthrough mode is not " 235 "enabled; returning -EIO\n"); 236 mutex_unlock(&crypt_stat->cs_mutex); 237 goto out_free; 238 } 239 rc = 0; 240 crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED); 241 mutex_unlock(&crypt_stat->cs_mutex); 242 goto out; 243 } 244 } 245 mutex_unlock(&crypt_stat->cs_mutex); 246 ecryptfs_printk(KERN_DEBUG, "inode w/ addr = [0x%p], i_ino = [0x%.16x] " 247 "size: [0x%.16x]\n", inode, inode->i_ino, 248 i_size_read(inode)); 249 goto out; 250 out_free: 251 kmem_cache_free(ecryptfs_file_info_cache, 252 ecryptfs_file_to_private(file)); 253 out: 254 return rc; 255 } 256 257 static int ecryptfs_flush(struct file *file, fl_owner_t td) 258 { 259 int rc = 0; 260 struct file *lower_file = NULL; 261 262 lower_file = ecryptfs_file_to_lower(file); 263 if (lower_file->f_op && lower_file->f_op->flush) 264 rc = lower_file->f_op->flush(lower_file, td); 265 return rc; 266 } 267 268 static int ecryptfs_release(struct inode *inode, struct file *file) 269 { 270 kmem_cache_free(ecryptfs_file_info_cache, 271 ecryptfs_file_to_private(file)); 272 return 0; 273 } 274 275 static int 276 ecryptfs_fsync(struct file *file, struct dentry *dentry, int datasync) 277 { 278 struct file *lower_file = ecryptfs_file_to_lower(file); 279 struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry); 280 struct inode *lower_inode = lower_dentry->d_inode; 281 int rc = -EINVAL; 282 283 if (lower_inode->i_fop->fsync) { 284 mutex_lock(&lower_inode->i_mutex); 285 rc = lower_inode->i_fop->fsync(lower_file, lower_dentry, 286 datasync); 287 mutex_unlock(&lower_inode->i_mutex); 288 } 289 return rc; 290 } 291 292 static int ecryptfs_fasync(int fd, struct file *file, int flag) 293 { 294 int rc = 0; 295 struct file *lower_file = NULL; 296 297 lock_kernel(); 298 lower_file = ecryptfs_file_to_lower(file); 299 if (lower_file->f_op && lower_file->f_op->fasync) 300 rc = lower_file->f_op->fasync(fd, lower_file, flag); 301 unlock_kernel(); 302 return rc; 303 } 304 305 static int ecryptfs_ioctl(struct inode *inode, struct file *file, 306 unsigned int cmd, unsigned long arg); 307 308 const struct file_operations ecryptfs_dir_fops = { 309 .readdir = ecryptfs_readdir, 310 .ioctl = ecryptfs_ioctl, 311 .mmap = generic_file_mmap, 312 .open = ecryptfs_open, 313 .flush = ecryptfs_flush, 314 .release = ecryptfs_release, 315 .fsync = ecryptfs_fsync, 316 .fasync = ecryptfs_fasync, 317 .splice_read = generic_file_splice_read, 318 }; 319 320 const struct file_operations ecryptfs_main_fops = { 321 .llseek = generic_file_llseek, 322 .read = do_sync_read, 323 .aio_read = ecryptfs_read_update_atime, 324 .write = do_sync_write, 325 .aio_write = generic_file_aio_write, 326 .readdir = ecryptfs_readdir, 327 .ioctl = ecryptfs_ioctl, 328 .mmap = generic_file_mmap, 329 .open = ecryptfs_open, 330 .flush = ecryptfs_flush, 331 .release = ecryptfs_release, 332 .fsync = ecryptfs_fsync, 333 .fasync = ecryptfs_fasync, 334 .splice_read = generic_file_splice_read, 335 }; 336 337 static int 338 ecryptfs_ioctl(struct inode *inode, struct file *file, unsigned int cmd, 339 unsigned long arg) 340 { 341 int rc = 0; 342 struct file *lower_file = NULL; 343 344 if (ecryptfs_file_to_private(file)) 345 lower_file = ecryptfs_file_to_lower(file); 346 if (lower_file && lower_file->f_op && lower_file->f_op->ioctl) 347 rc = lower_file->f_op->ioctl(ecryptfs_inode_to_lower(inode), 348 lower_file, cmd, arg); 349 else 350 rc = -ENOTTY; 351 return rc; 352 } 353