444 lines · c
1// SPDX-License-Identifier: GPL-2.0-or-later2/*3 * eCryptfs: Linux filesystem encryption layer4 *5 * Copyright (C) 1997-2004 Erez Zadok6 * Copyright (C) 2001-2004 Stony Brook University7 * 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_atime24 *25 * generic_file_read updates the atime of upper layer inode. But, it26 * doesn't give us a chance to update the atime of the lower layer27 * inode. This function is a wrapper to generic_file_read. It28 * updates the atime of the lower level inode if generic_file_read29 * 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 */32static 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/*48 * ecryptfs_splice_read_update_atime49 *50 * filemap_splice_read updates the atime of upper layer inode. But, it51 * doesn't give us a chance to update the atime of the lower layer inode. This52 * function is a wrapper to generic_file_read. It updates the atime of the53 * lower level inode if generic_file_read returns without any errors. This is54 * to be used only for file reads. The function to be used for directory reads55 * is ecryptfs_read.56 */57static ssize_t ecryptfs_splice_read_update_atime(struct file *in, loff_t *ppos,58 struct pipe_inode_info *pipe,59 size_t len, unsigned int flags)60{61 ssize_t rc;62 const struct path *path;63 64 rc = filemap_splice_read(in, ppos, pipe, len, flags);65 if (rc >= 0) {66 path = ecryptfs_dentry_to_lower_path(in->f_path.dentry);67 touch_atime(path);68 }69 return rc;70}71 72struct ecryptfs_getdents_callback {73 struct dir_context ctx;74 struct dir_context *caller;75 struct super_block *sb;76 int filldir_called;77 int entries_written;78};79 80/* Inspired by generic filldir in fs/readdir.c */81static bool82ecryptfs_filldir(struct dir_context *ctx, const char *lower_name,83 int lower_namelen, loff_t offset, u64 ino, unsigned int d_type)84{85 struct ecryptfs_getdents_callback *buf =86 container_of(ctx, struct ecryptfs_getdents_callback, ctx);87 size_t name_size;88 char *name;89 int err;90 bool res;91 92 buf->filldir_called++;93 err = ecryptfs_decode_and_decrypt_filename(&name, &name_size,94 buf->sb, lower_name,95 lower_namelen);96 if (err) {97 if (err != -EINVAL) {98 ecryptfs_printk(KERN_DEBUG,99 "%s: Error attempting to decode and decrypt filename [%s]; rc = [%d]\n",100 __func__, lower_name, err);101 return false;102 }103 104 /* Mask -EINVAL errors as these are most likely due a plaintext105 * filename present in the lower filesystem despite filename106 * encryption being enabled. One unavoidable example would be107 * the "lost+found" dentry in the root directory of an Ext4108 * filesystem.109 */110 return true;111 }112 113 buf->caller->pos = buf->ctx.pos;114 res = dir_emit(buf->caller, name, name_size, ino, d_type);115 kfree(name);116 if (res)117 buf->entries_written++;118 return res;119}120 121/**122 * ecryptfs_readdir123 * @file: The eCryptfs directory file124 * @ctx: The actor to feed the entries to125 */126static int ecryptfs_readdir(struct file *file, struct dir_context *ctx)127{128 int rc;129 struct file *lower_file;130 struct inode *inode = file_inode(file);131 struct ecryptfs_getdents_callback buf = {132 .ctx.actor = ecryptfs_filldir,133 .caller = ctx,134 .sb = inode->i_sb,135 };136 lower_file = ecryptfs_file_to_lower(file);137 rc = iterate_dir(lower_file, &buf.ctx);138 ctx->pos = buf.ctx.pos;139 if (rc >= 0 && (buf.entries_written || !buf.filldir_called))140 fsstack_copy_attr_atime(inode, file_inode(lower_file));141 return rc;142}143 144struct kmem_cache *ecryptfs_file_info_cache;145 146static int read_or_initialize_metadata(struct dentry *dentry)147{148 struct inode *inode = d_inode(dentry);149 struct ecryptfs_mount_crypt_stat *mount_crypt_stat;150 struct ecryptfs_crypt_stat *crypt_stat;151 int rc;152 153 crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;154 mount_crypt_stat = &ecryptfs_superblock_to_private(155 inode->i_sb)->mount_crypt_stat;156 mutex_lock(&crypt_stat->cs_mutex);157 158 if (crypt_stat->flags & ECRYPTFS_POLICY_APPLIED &&159 crypt_stat->flags & ECRYPTFS_KEY_VALID) {160 rc = 0;161 goto out;162 }163 164 rc = ecryptfs_read_metadata(dentry);165 if (!rc)166 goto out;167 168 if (mount_crypt_stat->flags & ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED) {169 crypt_stat->flags &= ~(ECRYPTFS_I_SIZE_INITIALIZED170 | ECRYPTFS_ENCRYPTED);171 rc = 0;172 goto out;173 }174 175 if (!(mount_crypt_stat->flags & ECRYPTFS_XATTR_METADATA_ENABLED) &&176 !i_size_read(ecryptfs_inode_to_lower(inode))) {177 rc = ecryptfs_initialize_file(dentry, inode);178 if (!rc)179 goto out;180 }181 182 rc = -EIO;183out:184 mutex_unlock(&crypt_stat->cs_mutex);185 return rc;186}187 188static int ecryptfs_mmap(struct file *file, struct vm_area_struct *vma)189{190 struct file *lower_file = ecryptfs_file_to_lower(file);191 /*192 * Don't allow mmap on top of file systems that don't support it193 * natively. If FILESYSTEM_MAX_STACK_DEPTH > 2 or ecryptfs194 * allows recursive mounting, this will need to be extended.195 */196 if (!lower_file->f_op->mmap)197 return -ENODEV;198 return generic_file_mmap(file, vma);199}200 201/**202 * ecryptfs_open203 * @inode: inode specifying file to open204 * @file: Structure to return filled in205 *206 * Opens the file specified by inode.207 *208 * Returns zero on success; non-zero otherwise209 */210static int ecryptfs_open(struct inode *inode, struct file *file)211{212 int rc = 0;213 struct ecryptfs_crypt_stat *crypt_stat = NULL;214 struct dentry *ecryptfs_dentry = file->f_path.dentry;215 /* Private value of ecryptfs_dentry allocated in216 * ecryptfs_lookup() */217 struct ecryptfs_file_info *file_info;218 219 /* Released in ecryptfs_release or end of function if failure */220 file_info = kmem_cache_zalloc(ecryptfs_file_info_cache, GFP_KERNEL);221 ecryptfs_set_file_private(file, file_info);222 if (!file_info) {223 ecryptfs_printk(KERN_ERR,224 "Error attempting to allocate memory\n");225 rc = -ENOMEM;226 goto out;227 }228 crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;229 mutex_lock(&crypt_stat->cs_mutex);230 if (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED)) {231 ecryptfs_printk(KERN_DEBUG, "Setting flags for stat...\n");232 /* Policy code enabled in future release */233 crypt_stat->flags |= (ECRYPTFS_POLICY_APPLIED234 | ECRYPTFS_ENCRYPTED);235 }236 mutex_unlock(&crypt_stat->cs_mutex);237 rc = ecryptfs_get_lower_file(ecryptfs_dentry, inode);238 if (rc) {239 printk(KERN_ERR "%s: Error attempting to initialize "240 "the lower file for the dentry with name "241 "[%pd]; rc = [%d]\n", __func__,242 ecryptfs_dentry, rc);243 goto out_free;244 }245 if ((ecryptfs_inode_to_private(inode)->lower_file->f_flags & O_ACCMODE)246 == O_RDONLY && (file->f_flags & O_ACCMODE) != O_RDONLY) {247 rc = -EPERM;248 printk(KERN_WARNING "%s: Lower file is RO; eCryptfs "249 "file must hence be opened RO\n", __func__);250 goto out_put;251 }252 ecryptfs_set_file_lower(253 file, ecryptfs_inode_to_private(inode)->lower_file);254 rc = read_or_initialize_metadata(ecryptfs_dentry);255 if (rc)256 goto out_put;257 ecryptfs_printk(KERN_DEBUG, "inode w/ addr = [0x%p], i_ino = "258 "[0x%.16lx] size: [0x%.16llx]\n", inode, inode->i_ino,259 (unsigned long long)i_size_read(inode));260 goto out;261out_put:262 ecryptfs_put_lower_file(inode);263out_free:264 kmem_cache_free(ecryptfs_file_info_cache,265 ecryptfs_file_to_private(file));266out:267 return rc;268}269 270/**271 * ecryptfs_dir_open272 * @inode: inode specifying file to open273 * @file: Structure to return filled in274 *275 * Opens the file specified by inode.276 *277 * Returns zero on success; non-zero otherwise278 */279static int ecryptfs_dir_open(struct inode *inode, struct file *file)280{281 struct dentry *ecryptfs_dentry = file->f_path.dentry;282 /* Private value of ecryptfs_dentry allocated in283 * ecryptfs_lookup() */284 struct ecryptfs_file_info *file_info;285 struct file *lower_file;286 287 /* Released in ecryptfs_release or end of function if failure */288 file_info = kmem_cache_zalloc(ecryptfs_file_info_cache, GFP_KERNEL);289 ecryptfs_set_file_private(file, file_info);290 if (unlikely(!file_info)) {291 ecryptfs_printk(KERN_ERR,292 "Error attempting to allocate memory\n");293 return -ENOMEM;294 }295 lower_file = dentry_open(ecryptfs_dentry_to_lower_path(ecryptfs_dentry),296 file->f_flags, current_cred());297 if (IS_ERR(lower_file)) {298 printk(KERN_ERR "%s: Error attempting to initialize "299 "the lower file for the dentry with name "300 "[%pd]; rc = [%ld]\n", __func__,301 ecryptfs_dentry, PTR_ERR(lower_file));302 kmem_cache_free(ecryptfs_file_info_cache, file_info);303 return PTR_ERR(lower_file);304 }305 ecryptfs_set_file_lower(file, lower_file);306 return 0;307}308 309static int ecryptfs_flush(struct file *file, fl_owner_t td)310{311 struct file *lower_file = ecryptfs_file_to_lower(file);312 313 if (lower_file->f_op->flush) {314 filemap_write_and_wait(file->f_mapping);315 return lower_file->f_op->flush(lower_file, td);316 }317 318 return 0;319}320 321static int ecryptfs_release(struct inode *inode, struct file *file)322{323 ecryptfs_put_lower_file(inode);324 kmem_cache_free(ecryptfs_file_info_cache,325 ecryptfs_file_to_private(file));326 return 0;327}328 329static int ecryptfs_dir_release(struct inode *inode, struct file *file)330{331 fput(ecryptfs_file_to_lower(file));332 kmem_cache_free(ecryptfs_file_info_cache,333 ecryptfs_file_to_private(file));334 return 0;335}336 337static loff_t ecryptfs_dir_llseek(struct file *file, loff_t offset, int whence)338{339 return vfs_llseek(ecryptfs_file_to_lower(file), offset, whence);340}341 342static int343ecryptfs_fsync(struct file *file, loff_t start, loff_t end, int datasync)344{345 int rc;346 347 rc = file_write_and_wait(file);348 if (rc)349 return rc;350 351 return vfs_fsync(ecryptfs_file_to_lower(file), datasync);352}353 354static int ecryptfs_fasync(int fd, struct file *file, int flag)355{356 int rc = 0;357 struct file *lower_file = NULL;358 359 lower_file = ecryptfs_file_to_lower(file);360 if (lower_file->f_op->fasync)361 rc = lower_file->f_op->fasync(fd, lower_file, flag);362 return rc;363}364 365static long366ecryptfs_unlocked_ioctl(struct file *file, unsigned int cmd, unsigned long arg)367{368 struct file *lower_file = ecryptfs_file_to_lower(file);369 long rc = -ENOTTY;370 371 if (!lower_file->f_op->unlocked_ioctl)372 return rc;373 374 switch (cmd) {375 case FITRIM:376 case FS_IOC_GETFLAGS:377 case FS_IOC_SETFLAGS:378 case FS_IOC_GETVERSION:379 case FS_IOC_SETVERSION:380 rc = lower_file->f_op->unlocked_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}388 389#ifdef CONFIG_COMPAT390static long391ecryptfs_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)392{393 struct file *lower_file = ecryptfs_file_to_lower(file);394 long rc = -ENOIOCTLCMD;395 396 if (!lower_file->f_op->compat_ioctl)397 return rc;398 399 switch (cmd) {400 case FITRIM:401 case FS_IOC32_GETFLAGS:402 case FS_IOC32_SETFLAGS:403 case FS_IOC32_GETVERSION:404 case FS_IOC32_SETVERSION:405 rc = lower_file->f_op->compat_ioctl(lower_file, cmd, arg);406 fsstack_copy_attr_all(file_inode(file), file_inode(lower_file));407 408 return rc;409 default:410 return rc;411 }412}413#endif414 415const struct file_operations ecryptfs_dir_fops = {416 .iterate_shared = ecryptfs_readdir,417 .read = generic_read_dir,418 .unlocked_ioctl = ecryptfs_unlocked_ioctl,419#ifdef CONFIG_COMPAT420 .compat_ioctl = ecryptfs_compat_ioctl,421#endif422 .open = ecryptfs_dir_open,423 .release = ecryptfs_dir_release,424 .fsync = ecryptfs_fsync,425 .llseek = ecryptfs_dir_llseek,426};427 428const struct file_operations ecryptfs_main_fops = {429 .llseek = generic_file_llseek,430 .read_iter = ecryptfs_read_update_atime,431 .write_iter = generic_file_write_iter,432 .unlocked_ioctl = ecryptfs_unlocked_ioctl,433#ifdef CONFIG_COMPAT434 .compat_ioctl = ecryptfs_compat_ioctl,435#endif436 .mmap = ecryptfs_mmap,437 .open = ecryptfs_open,438 .flush = ecryptfs_flush,439 .release = ecryptfs_release,440 .fsync = ecryptfs_fsync,441 .fasync = ecryptfs_fasync,442 .splice_read = ecryptfs_splice_read_update_atime,443};444