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 "ecryptfs_kernel.h" 34 35 /** 36 * ecryptfs_read_update_atime 37 * 38 * generic_file_read updates the atime of upper layer inode. But, it 39 * doesn't give us a chance to update the atime of the lower layer 40 * inode. This function is a wrapper to generic_file_read. It 41 * updates the atime of the lower level inode if generic_file_read 42 * returns without any errors. This is to be used only for file reads. 43 * The function to be used for directory reads is ecryptfs_read. 44 */ 45 static ssize_t ecryptfs_read_update_atime(struct kiocb *iocb, 46 const struct iovec *iov, 47 unsigned long nr_segs, loff_t pos) 48 { 49 int rc; 50 struct dentry *lower_dentry; 51 struct vfsmount *lower_vfsmount; 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_vfsmount = ecryptfs_dentry_to_lower_mnt(file->f_path.dentry); 64 touch_atime(lower_vfsmount, lower_dentry); 65 } 66 return rc; 67 } 68 69 struct ecryptfs_getdents_callback { 70 void *dirent; 71 struct dentry *dentry; 72 filldir_t filldir; 73 int err; 74 int filldir_called; 75 int entries_written; 76 }; 77 78 /* Inspired by generic filldir in fs/readir.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 retry: 128 buf.filldir_called = 0; 129 buf.entries_written = 0; 130 buf.err = 0; 131 rc = vfs_readdir(lower_file, ecryptfs_filldir, (void *)&buf); 132 if (buf.err) 133 rc = buf.err; 134 if (buf.filldir_called && !buf.entries_written) 135 goto retry; 136 file->f_pos = lower_file->f_pos; 137 if (rc >= 0) 138 fsstack_copy_attr_atime(inode, lower_file->f_path.dentry->d_inode); 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 ecryptfs_set_file_lower( 195 file, ecryptfs_inode_to_private(inode)->lower_file); 196 if (S_ISDIR(ecryptfs_dentry->d_inode->i_mode)) { 197 ecryptfs_printk(KERN_DEBUG, "This is a directory\n"); 198 crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED); 199 rc = 0; 200 goto out; 201 } 202 mutex_lock(&crypt_stat->cs_mutex); 203 if (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED) 204 || !(crypt_stat->flags & ECRYPTFS_KEY_VALID)) { 205 rc = ecryptfs_read_metadata(ecryptfs_dentry); 206 if (rc) { 207 ecryptfs_printk(KERN_DEBUG, 208 "Valid headers not found\n"); 209 if (!(mount_crypt_stat->flags 210 & ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED)) { 211 rc = -EIO; 212 printk(KERN_WARNING "Attempt to read file that " 213 "is not in a valid eCryptfs format, " 214 "and plaintext passthrough mode is not " 215 "enabled; returning -EIO\n"); 216 mutex_unlock(&crypt_stat->cs_mutex); 217 goto out_free; 218 } 219 rc = 0; 220 crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED); 221 mutex_unlock(&crypt_stat->cs_mutex); 222 goto out; 223 } 224 } 225 mutex_unlock(&crypt_stat->cs_mutex); 226 ecryptfs_printk(KERN_DEBUG, "inode w/ addr = [0x%p], i_ino = [0x%.16x] " 227 "size: [0x%.16x]\n", inode, inode->i_ino, 228 i_size_read(inode)); 229 goto out; 230 out_free: 231 kmem_cache_free(ecryptfs_file_info_cache, 232 ecryptfs_file_to_private(file)); 233 out: 234 return rc; 235 } 236 237 static int ecryptfs_flush(struct file *file, fl_owner_t td) 238 { 239 int rc = 0; 240 struct file *lower_file = NULL; 241 242 lower_file = ecryptfs_file_to_lower(file); 243 if (lower_file->f_op && lower_file->f_op->flush) 244 rc = lower_file->f_op->flush(lower_file, td); 245 return rc; 246 } 247 248 static int ecryptfs_release(struct inode *inode, struct file *file) 249 { 250 kmem_cache_free(ecryptfs_file_info_cache, 251 ecryptfs_file_to_private(file)); 252 return 0; 253 } 254 255 static int 256 ecryptfs_fsync(struct file *file, struct dentry *dentry, int datasync) 257 { 258 struct file *lower_file = ecryptfs_file_to_lower(file); 259 struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry); 260 struct inode *lower_inode = lower_dentry->d_inode; 261 int rc = -EINVAL; 262 263 if (lower_inode->i_fop->fsync) { 264 mutex_lock(&lower_inode->i_mutex); 265 rc = lower_inode->i_fop->fsync(lower_file, lower_dentry, 266 datasync); 267 mutex_unlock(&lower_inode->i_mutex); 268 } 269 return rc; 270 } 271 272 static int ecryptfs_fasync(int fd, struct file *file, int flag) 273 { 274 int rc = 0; 275 struct file *lower_file = NULL; 276 277 lower_file = ecryptfs_file_to_lower(file); 278 if (lower_file->f_op && lower_file->f_op->fasync) 279 rc = lower_file->f_op->fasync(fd, lower_file, flag); 280 return rc; 281 } 282 283 static int ecryptfs_ioctl(struct inode *inode, struct file *file, 284 unsigned int cmd, unsigned long arg); 285 286 const struct file_operations ecryptfs_dir_fops = { 287 .readdir = ecryptfs_readdir, 288 .ioctl = ecryptfs_ioctl, 289 .mmap = generic_file_mmap, 290 .open = ecryptfs_open, 291 .flush = ecryptfs_flush, 292 .release = ecryptfs_release, 293 .fsync = ecryptfs_fsync, 294 .fasync = ecryptfs_fasync, 295 .splice_read = generic_file_splice_read, 296 }; 297 298 const struct file_operations ecryptfs_main_fops = { 299 .llseek = generic_file_llseek, 300 .read = do_sync_read, 301 .aio_read = ecryptfs_read_update_atime, 302 .write = do_sync_write, 303 .aio_write = generic_file_aio_write, 304 .readdir = ecryptfs_readdir, 305 .ioctl = ecryptfs_ioctl, 306 .mmap = generic_file_mmap, 307 .open = ecryptfs_open, 308 .flush = ecryptfs_flush, 309 .release = ecryptfs_release, 310 .fsync = ecryptfs_fsync, 311 .fasync = ecryptfs_fasync, 312 .splice_read = generic_file_splice_read, 313 }; 314 315 static int 316 ecryptfs_ioctl(struct inode *inode, struct file *file, unsigned int cmd, 317 unsigned long arg) 318 { 319 int rc = 0; 320 struct file *lower_file = NULL; 321 322 if (ecryptfs_file_to_private(file)) 323 lower_file = ecryptfs_file_to_lower(file); 324 if (lower_file && lower_file->f_op && lower_file->f_op->ioctl) 325 rc = lower_file->f_op->ioctl(ecryptfs_inode_to_lower(inode), 326 lower_file, cmd, arg); 327 else 328 rc = -ENOTTY; 329 return rc; 330 } 331