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