1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * eCryptfs: Linux filesystem encryption layer 4 * 5 * Copyright (C) 1997-2004 Erez Zadok 6 * Copyright (C) 2001-2004 Stony Brook University 7 * Copyright (C) 2004-2007 International Business Machines Corp. 8 * Author(s): Michael A. Halcrow <mhalcrow@us.ibm.com> 9 * Michael C. Thompson <mcthomps@us.ibm.com> 10 */ 11 12 #include <linux/file.h> 13 #include <linux/poll.h> 14 #include <linux/slab.h> 15 #include <linux/mount.h> 16 #include <linux/pagemap.h> 17 #include <linux/security.h> 18 #include <linux/compat.h> 19 #include <linux/fs_stack.h> 20 #include "ecryptfs_kernel.h" 21 22 /* 23 * ecryptfs_read_update_atime 24 * 25 * generic_file_read updates the atime of upper layer inode. But, it 26 * doesn't give us a chance to update the atime of the lower layer 27 * inode. This function is a wrapper to generic_file_read. It 28 * updates the atime of the lower level inode if generic_file_read 29 * returns without any errors. This is to be used only for file reads. 30 * The function to be used for directory reads is ecryptfs_read. 31 */ 32 static ssize_t ecryptfs_read_update_atime(struct kiocb *iocb, 33 struct iov_iter *to) 34 { 35 ssize_t rc; 36 const struct path *path; 37 struct file *file = iocb->ki_filp; 38 39 rc = generic_file_read_iter(iocb, to); 40 if (rc >= 0) { 41 path = ecryptfs_dentry_to_lower_path(file->f_path.dentry); 42 touch_atime(path); 43 } 44 return rc; 45 } 46 47 struct ecryptfs_getdents_callback { 48 struct dir_context ctx; 49 struct dir_context *caller; 50 struct super_block *sb; 51 int filldir_called; 52 int entries_written; 53 }; 54 55 /* Inspired by generic filldir in fs/readdir.c */ 56 static bool 57 ecryptfs_filldir(struct dir_context *ctx, const char *lower_name, 58 int lower_namelen, loff_t offset, u64 ino, unsigned int d_type) 59 { 60 struct ecryptfs_getdents_callback *buf = 61 container_of(ctx, struct ecryptfs_getdents_callback, ctx); 62 size_t name_size; 63 char *name; 64 int err; 65 bool res; 66 67 buf->filldir_called++; 68 err = ecryptfs_decode_and_decrypt_filename(&name, &name_size, 69 buf->sb, lower_name, 70 lower_namelen); 71 if (err) { 72 if (err != -EINVAL) { 73 ecryptfs_printk(KERN_DEBUG, 74 "%s: Error attempting to decode and decrypt filename [%s]; rc = [%d]\n", 75 __func__, lower_name, err); 76 return false; 77 } 78 79 /* Mask -EINVAL errors as these are most likely due a plaintext 80 * filename present in the lower filesystem despite filename 81 * encryption being enabled. One unavoidable example would be 82 * the "lost+found" dentry in the root directory of an Ext4 83 * filesystem. 84 */ 85 return true; 86 } 87 88 buf->caller->pos = buf->ctx.pos; 89 res = dir_emit(buf->caller, name, name_size, ino, d_type); 90 kfree(name); 91 if (res) 92 buf->entries_written++; 93 return res; 94 } 95 96 /** 97 * ecryptfs_readdir 98 * @file: The eCryptfs directory file 99 * @ctx: The actor to feed the entries to 100 */ 101 static int ecryptfs_readdir(struct file *file, struct dir_context *ctx) 102 { 103 int rc; 104 struct file *lower_file; 105 struct inode *inode = file_inode(file); 106 struct ecryptfs_getdents_callback buf = { 107 .ctx.actor = ecryptfs_filldir, 108 .caller = ctx, 109 .sb = inode->i_sb, 110 }; 111 lower_file = ecryptfs_file_to_lower(file); 112 rc = iterate_dir(lower_file, &buf.ctx); 113 ctx->pos = buf.ctx.pos; 114 if (rc >= 0 && (buf.entries_written || !buf.filldir_called)) 115 fsstack_copy_attr_atime(inode, file_inode(lower_file)); 116 return rc; 117 } 118 119 struct kmem_cache *ecryptfs_file_info_cache; 120 121 static int read_or_initialize_metadata(struct dentry *dentry) 122 { 123 struct inode *inode = d_inode(dentry); 124 struct ecryptfs_mount_crypt_stat *mount_crypt_stat; 125 struct ecryptfs_crypt_stat *crypt_stat; 126 int rc; 127 128 crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat; 129 mount_crypt_stat = &ecryptfs_superblock_to_private( 130 inode->i_sb)->mount_crypt_stat; 131 mutex_lock(&crypt_stat->cs_mutex); 132 133 if (crypt_stat->flags & ECRYPTFS_POLICY_APPLIED && 134 crypt_stat->flags & ECRYPTFS_KEY_VALID) { 135 rc = 0; 136 goto out; 137 } 138 139 rc = ecryptfs_read_metadata(dentry); 140 if (!rc) 141 goto out; 142 143 if (mount_crypt_stat->flags & ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED) { 144 crypt_stat->flags &= ~(ECRYPTFS_I_SIZE_INITIALIZED 145 | ECRYPTFS_ENCRYPTED); 146 rc = 0; 147 goto out; 148 } 149 150 if (!(mount_crypt_stat->flags & ECRYPTFS_XATTR_METADATA_ENABLED) && 151 !i_size_read(ecryptfs_inode_to_lower(inode))) { 152 rc = ecryptfs_initialize_file(dentry, inode); 153 if (!rc) 154 goto out; 155 } 156 157 rc = -EIO; 158 out: 159 mutex_unlock(&crypt_stat->cs_mutex); 160 return rc; 161 } 162 163 static int ecryptfs_mmap(struct file *file, struct vm_area_struct *vma) 164 { 165 struct file *lower_file = ecryptfs_file_to_lower(file); 166 /* 167 * Don't allow mmap on top of file systems that don't support it 168 * natively. If FILESYSTEM_MAX_STACK_DEPTH > 2 or ecryptfs 169 * allows recursive mounting, this will need to be extended. 170 */ 171 if (!lower_file->f_op->mmap) 172 return -ENODEV; 173 return generic_file_mmap(file, vma); 174 } 175 176 /** 177 * ecryptfs_open 178 * @inode: inode specifying file to open 179 * @file: Structure to return filled in 180 * 181 * Opens the file specified by inode. 182 * 183 * Returns zero on success; non-zero otherwise 184 */ 185 static int ecryptfs_open(struct inode *inode, struct file *file) 186 { 187 int rc = 0; 188 struct ecryptfs_crypt_stat *crypt_stat = NULL; 189 struct dentry *ecryptfs_dentry = file->f_path.dentry; 190 /* Private value of ecryptfs_dentry allocated in 191 * ecryptfs_lookup() */ 192 struct ecryptfs_file_info *file_info; 193 194 /* Released in ecryptfs_release or end of function if failure */ 195 file_info = kmem_cache_zalloc(ecryptfs_file_info_cache, GFP_KERNEL); 196 ecryptfs_set_file_private(file, file_info); 197 if (!file_info) { 198 ecryptfs_printk(KERN_ERR, 199 "Error attempting to allocate memory\n"); 200 rc = -ENOMEM; 201 goto out; 202 } 203 crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat; 204 mutex_lock(&crypt_stat->cs_mutex); 205 if (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED)) { 206 ecryptfs_printk(KERN_DEBUG, "Setting flags for stat...\n"); 207 /* Policy code enabled in future release */ 208 crypt_stat->flags |= (ECRYPTFS_POLICY_APPLIED 209 | ECRYPTFS_ENCRYPTED); 210 } 211 mutex_unlock(&crypt_stat->cs_mutex); 212 rc = ecryptfs_get_lower_file(ecryptfs_dentry, inode); 213 if (rc) { 214 printk(KERN_ERR "%s: Error attempting to initialize " 215 "the lower file for the dentry with name " 216 "[%pd]; rc = [%d]\n", __func__, 217 ecryptfs_dentry, rc); 218 goto out_free; 219 } 220 if ((ecryptfs_inode_to_private(inode)->lower_file->f_flags & O_ACCMODE) 221 == O_RDONLY && (file->f_flags & O_ACCMODE) != O_RDONLY) { 222 rc = -EPERM; 223 printk(KERN_WARNING "%s: Lower file is RO; eCryptfs " 224 "file must hence be opened RO\n", __func__); 225 goto out_put; 226 } 227 ecryptfs_set_file_lower( 228 file, ecryptfs_inode_to_private(inode)->lower_file); 229 rc = read_or_initialize_metadata(ecryptfs_dentry); 230 if (rc) 231 goto out_put; 232 ecryptfs_printk(KERN_DEBUG, "inode w/ addr = [0x%p], i_ino = " 233 "[0x%.16lx] size: [0x%.16llx]\n", inode, inode->i_ino, 234 (unsigned long long)i_size_read(inode)); 235 goto out; 236 out_put: 237 ecryptfs_put_lower_file(inode); 238 out_free: 239 kmem_cache_free(ecryptfs_file_info_cache, 240 ecryptfs_file_to_private(file)); 241 out: 242 return rc; 243 } 244 245 /** 246 * ecryptfs_dir_open 247 * @inode: inode specifying file to open 248 * @file: Structure to return filled in 249 * 250 * Opens the file specified by inode. 251 * 252 * Returns zero on success; non-zero otherwise 253 */ 254 static int ecryptfs_dir_open(struct inode *inode, struct file *file) 255 { 256 struct dentry *ecryptfs_dentry = file->f_path.dentry; 257 /* Private value of ecryptfs_dentry allocated in 258 * ecryptfs_lookup() */ 259 struct ecryptfs_file_info *file_info; 260 struct file *lower_file; 261 262 /* Released in ecryptfs_release or end of function if failure */ 263 file_info = kmem_cache_zalloc(ecryptfs_file_info_cache, GFP_KERNEL); 264 ecryptfs_set_file_private(file, file_info); 265 if (unlikely(!file_info)) { 266 ecryptfs_printk(KERN_ERR, 267 "Error attempting to allocate memory\n"); 268 return -ENOMEM; 269 } 270 lower_file = dentry_open(ecryptfs_dentry_to_lower_path(ecryptfs_dentry), 271 file->f_flags, current_cred()); 272 if (IS_ERR(lower_file)) { 273 printk(KERN_ERR "%s: Error attempting to initialize " 274 "the lower file for the dentry with name " 275 "[%pd]; rc = [%ld]\n", __func__, 276 ecryptfs_dentry, PTR_ERR(lower_file)); 277 kmem_cache_free(ecryptfs_file_info_cache, file_info); 278 return PTR_ERR(lower_file); 279 } 280 ecryptfs_set_file_lower(file, lower_file); 281 return 0; 282 } 283 284 static int ecryptfs_flush(struct file *file, fl_owner_t td) 285 { 286 struct file *lower_file = ecryptfs_file_to_lower(file); 287 288 if (lower_file->f_op->flush) { 289 filemap_write_and_wait(file->f_mapping); 290 return lower_file->f_op->flush(lower_file, td); 291 } 292 293 return 0; 294 } 295 296 static int ecryptfs_release(struct inode *inode, struct file *file) 297 { 298 ecryptfs_put_lower_file(inode); 299 kmem_cache_free(ecryptfs_file_info_cache, 300 ecryptfs_file_to_private(file)); 301 return 0; 302 } 303 304 static int ecryptfs_dir_release(struct inode *inode, struct file *file) 305 { 306 fput(ecryptfs_file_to_lower(file)); 307 kmem_cache_free(ecryptfs_file_info_cache, 308 ecryptfs_file_to_private(file)); 309 return 0; 310 } 311 312 static loff_t ecryptfs_dir_llseek(struct file *file, loff_t offset, int whence) 313 { 314 return vfs_llseek(ecryptfs_file_to_lower(file), offset, whence); 315 } 316 317 static int 318 ecryptfs_fsync(struct file *file, loff_t start, loff_t end, int datasync) 319 { 320 int rc; 321 322 rc = file_write_and_wait(file); 323 if (rc) 324 return rc; 325 326 return vfs_fsync(ecryptfs_file_to_lower(file), datasync); 327 } 328 329 static int ecryptfs_fasync(int fd, struct file *file, int flag) 330 { 331 int rc = 0; 332 struct file *lower_file = NULL; 333 334 lower_file = ecryptfs_file_to_lower(file); 335 if (lower_file->f_op->fasync) 336 rc = lower_file->f_op->fasync(fd, lower_file, flag); 337 return rc; 338 } 339 340 static long 341 ecryptfs_unlocked_ioctl(struct file *file, unsigned int cmd, unsigned long arg) 342 { 343 struct file *lower_file = ecryptfs_file_to_lower(file); 344 long rc = -ENOTTY; 345 346 if (!lower_file->f_op->unlocked_ioctl) 347 return rc; 348 349 switch (cmd) { 350 case FITRIM: 351 case FS_IOC_GETFLAGS: 352 case FS_IOC_SETFLAGS: 353 case FS_IOC_GETVERSION: 354 case FS_IOC_SETVERSION: 355 rc = lower_file->f_op->unlocked_ioctl(lower_file, cmd, arg); 356 fsstack_copy_attr_all(file_inode(file), file_inode(lower_file)); 357 358 return rc; 359 default: 360 return rc; 361 } 362 } 363 364 #ifdef CONFIG_COMPAT 365 static long 366 ecryptfs_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg) 367 { 368 struct file *lower_file = ecryptfs_file_to_lower(file); 369 long rc = -ENOIOCTLCMD; 370 371 if (!lower_file->f_op->compat_ioctl) 372 return rc; 373 374 switch (cmd) { 375 case FITRIM: 376 case FS_IOC32_GETFLAGS: 377 case FS_IOC32_SETFLAGS: 378 case FS_IOC32_GETVERSION: 379 case FS_IOC32_SETVERSION: 380 rc = lower_file->f_op->compat_ioctl(lower_file, cmd, arg); 381 fsstack_copy_attr_all(file_inode(file), file_inode(lower_file)); 382 383 return rc; 384 default: 385 return rc; 386 } 387 } 388 #endif 389 390 const struct file_operations ecryptfs_dir_fops = { 391 .iterate_shared = ecryptfs_readdir, 392 .read = generic_read_dir, 393 .unlocked_ioctl = ecryptfs_unlocked_ioctl, 394 #ifdef CONFIG_COMPAT 395 .compat_ioctl = ecryptfs_compat_ioctl, 396 #endif 397 .open = ecryptfs_dir_open, 398 .release = ecryptfs_dir_release, 399 .fsync = ecryptfs_fsync, 400 .llseek = ecryptfs_dir_llseek, 401 }; 402 403 const struct file_operations ecryptfs_main_fops = { 404 .llseek = generic_file_llseek, 405 .read_iter = ecryptfs_read_update_atime, 406 .write_iter = generic_file_write_iter, 407 .unlocked_ioctl = ecryptfs_unlocked_ioctl, 408 #ifdef CONFIG_COMPAT 409 .compat_ioctl = ecryptfs_compat_ioctl, 410 #endif 411 .mmap = ecryptfs_mmap, 412 .open = ecryptfs_open, 413 .flush = ecryptfs_flush, 414 .release = ecryptfs_release, 415 .fsync = ecryptfs_fsync, 416 .fasync = ecryptfs_fasync, 417 .splice_read = generic_file_splice_read, 418 }; 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