/**
   * eCryptfs: Linux filesystem encryption layer
   *
   * Copyright (C) 1997-2004 Erez Zadok
   * Copyright (C) 2001-2004 Stony Brook University
   * Copyright (C) 2004-2007 International Business Machines Corp.
   *   Author(s): Michael A. Halcrow <mhalcrow@us.ibm.com>
   *   		Michael C. Thompson <mcthomps@us.ibm.com>
   *
   * This program is free software; you can redistribute it and/or
   * modify it under the terms of the GNU General Public License as
   * published by the Free Software Foundation; either version 2 of the
   * License, or (at your option) any later version.
   *
   * This program is distributed in the hope that it will be useful, but
   * WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   * General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with this program; if not, write to the Free Software
   * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
   * 02111-1307, USA.
   */
  
  #include <linux/file.h>
  #include <linux/poll.h>
  #include <linux/slab.h>
  #include <linux/mount.h>
  #include <linux/pagemap.h>
  #include <linux/security.h>
  #include <linux/compat.h>
  #include <linux/fs_stack.h>
  #include "ecryptfs_kernel.h"
  
  /**
   * ecryptfs_read_update_atime
   *
   * generic_file_read updates the atime of upper layer inode.  But, it
   * doesn't give us a chance to update the atime of the lower layer
   * inode.  This function is a wrapper to generic_file_read.  It
   * updates the atime of the lower level inode if generic_file_read
   * returns without any errors. This is to be used only for file reads.
   * The function to be used for directory reads is ecryptfs_read.
   */
  static ssize_t ecryptfs_read_update_atime(struct kiocb *iocb,
  				struct iov_iter *to)
  {
  	ssize_t rc;
  	struct path *path;
  	struct file *file = iocb->ki_filp;
  
  	rc = generic_file_read_iter(iocb, to);
  	if (rc >= 0) {
  		path = ecryptfs_dentry_to_lower_path(file->f_path.dentry);
  		touch_atime(path);
  	}
  	return rc;
  }
  
  struct ecryptfs_getdents_callback {
  	struct dir_context ctx;
  	struct dir_context *caller;
  	struct super_block *sb;
  	int filldir_called;
  	int entries_written;
  };
  
  /* Inspired by generic filldir in fs/readdir.c */
  static int
  ecryptfs_filldir(struct dir_context *ctx, const char *lower_name,
  		 int lower_namelen, loff_t offset, u64 ino, unsigned int d_type)
  {
  	struct ecryptfs_getdents_callback *buf =
  		container_of(ctx, struct ecryptfs_getdents_callback, ctx);
  	size_t name_size;
  	char *name;
  	int rc;
  
  	buf->filldir_called++;
  	rc = ecryptfs_decode_and_decrypt_filename(&name, &name_size,
  						  buf->sb, lower_name,
  						  lower_namelen);
  	if (rc) {
  		printk(KERN_ERR "%s: Error attempting to decode and decrypt "
  		       "filename [%s]; rc = [%d]
  ", __func__, lower_name,
  		       rc);
  		goto out;
  	}
  	buf->caller->pos = buf->ctx.pos;
  	rc = !dir_emit(buf->caller, name, name_size, ino, d_type);
  	kfree(name);
  	if (!rc)
  		buf->entries_written++;
  out:
  	return rc;
  }
  
  /**
   * ecryptfs_readdir
   * @file: The eCryptfs directory file
   * @ctx: The actor to feed the entries to
   */
  static int ecryptfs_readdir(struct file *file, struct dir_context *ctx)
  {
  	int rc;
  	struct file *lower_file;
  	struct inode *inode = file_inode(file);
  	struct ecryptfs_getdents_callback buf = {
  		.ctx.actor = ecryptfs_filldir,
  		.caller = ctx,
  		.sb = inode->i_sb,
  	};
  	lower_file = ecryptfs_file_to_lower(file);
  	rc = iterate_dir(lower_file, &buf.ctx);
  	ctx->pos = buf.ctx.pos;
  	if (rc < 0)
  		goto out;
  	if (buf.filldir_called && !buf.entries_written)
  		goto out;
  	if (rc >= 0)
  		fsstack_copy_attr_atime(inode,
  					file_inode(lower_file));
  out:
  	return rc;
  }
  
  struct kmem_cache *ecryptfs_file_info_cache;
  
  static int read_or_initialize_metadata(struct dentry *dentry)
  {
  	struct inode *inode = d_inode(dentry);
  	struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
  	struct ecryptfs_crypt_stat *crypt_stat;
  	int rc;
  
  	crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
  	mount_crypt_stat = &ecryptfs_superblock_to_private(
  						inode->i_sb)->mount_crypt_stat;
  	mutex_lock(&crypt_stat->cs_mutex);
  
  	if (crypt_stat->flags & ECRYPTFS_POLICY_APPLIED &&
  	    crypt_stat->flags & ECRYPTFS_KEY_VALID) {
  		rc = 0;
  		goto out;
  	}
  
  	rc = ecryptfs_read_metadata(dentry);
  	if (!rc)
  		goto out;
  
  	if (mount_crypt_stat->flags & ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED) {
  		crypt_stat->flags &= ~(ECRYPTFS_I_SIZE_INITIALIZED
  				       | ECRYPTFS_ENCRYPTED);
  		rc = 0;
  		goto out;
  	}
  
  	if (!(mount_crypt_stat->flags & ECRYPTFS_XATTR_METADATA_ENABLED) &&
  	    !i_size_read(ecryptfs_inode_to_lower(inode))) {
  		rc = ecryptfs_initialize_file(dentry, inode);
  		if (!rc)
  			goto out;
  	}
  
  	rc = -EIO;
  out:
  	mutex_unlock(&crypt_stat->cs_mutex);
  	return rc;
  }
  
  static int ecryptfs_mmap(struct file *file, struct vm_area_struct *vma)
  {
  	struct file *lower_file = ecryptfs_file_to_lower(file);
  	/*
  	 * Don't allow mmap on top of file systems that don't support it
  	 * natively.  If FILESYSTEM_MAX_STACK_DEPTH > 2 or ecryptfs
  	 * allows recursive mounting, this will need to be extended.
  	 */
  	if (!lower_file->f_op->mmap)
  		return -ENODEV;
  	return generic_file_mmap(file, vma);
  }
  
  /**
   * ecryptfs_open
   * @inode: inode speciying file to open
   * @file: Structure to return filled in
   *
   * Opens the file specified by inode.
   *
   * Returns zero on success; non-zero otherwise
   */
  static int ecryptfs_open(struct inode *inode, struct file *file)
  {
  	int rc = 0;
  	struct ecryptfs_crypt_stat *crypt_stat = NULL;
  	struct dentry *ecryptfs_dentry = file->f_path.dentry;
  	/* Private value of ecryptfs_dentry allocated in
  	 * ecryptfs_lookup() */
  	struct ecryptfs_file_info *file_info;
  
  	/* Released in ecryptfs_release or end of function if failure */
  	file_info = kmem_cache_zalloc(ecryptfs_file_info_cache, GFP_KERNEL);
  	ecryptfs_set_file_private(file, file_info);
  	if (!file_info) {
  		ecryptfs_printk(KERN_ERR,
  				"Error attempting to allocate memory
  ");
  		rc = -ENOMEM;
  		goto out;
  	}
  	crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
  	mutex_lock(&crypt_stat->cs_mutex);
  	if (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED)) {
  		ecryptfs_printk(KERN_DEBUG, "Setting flags for stat...
  ");
  		/* Policy code enabled in future release */
  		crypt_stat->flags |= (ECRYPTFS_POLICY_APPLIED
  				      | ECRYPTFS_ENCRYPTED);
  	}
  	mutex_unlock(&crypt_stat->cs_mutex);
  	rc = ecryptfs_get_lower_file(ecryptfs_dentry, inode);
  	if (rc) {
  		printk(KERN_ERR "%s: Error attempting to initialize "
  			"the lower file for the dentry with name "
  			"[%pd]; rc = [%d]
  ", __func__,
  			ecryptfs_dentry, rc);
  		goto out_free;
  	}
  	if ((ecryptfs_inode_to_private(inode)->lower_file->f_flags & O_ACCMODE)
  	    == O_RDONLY && (file->f_flags & O_ACCMODE) != O_RDONLY) {
  		rc = -EPERM;
  		printk(KERN_WARNING "%s: Lower file is RO; eCryptfs "
  		       "file must hence be opened RO
  ", __func__);
  		goto out_put;
  	}
  	ecryptfs_set_file_lower(
  		file, ecryptfs_inode_to_private(inode)->lower_file);
  	rc = read_or_initialize_metadata(ecryptfs_dentry);
  	if (rc)
  		goto out_put;
  	ecryptfs_printk(KERN_DEBUG, "inode w/ addr = [0x%p], i_ino = "
  			"[0x%.16lx] size: [0x%.16llx]
  ", inode, inode->i_ino,
  			(unsigned long long)i_size_read(inode));
  	goto out;
  out_put:
  	ecryptfs_put_lower_file(inode);
  out_free:
  	kmem_cache_free(ecryptfs_file_info_cache,
  			ecryptfs_file_to_private(file));
  out:
  	return rc;
  }
  
  /**
   * ecryptfs_dir_open
   * @inode: inode speciying file to open
   * @file: Structure to return filled in
   *
   * Opens the file specified by inode.
   *
   * Returns zero on success; non-zero otherwise
   */
  static int ecryptfs_dir_open(struct inode *inode, struct file *file)
  {
  	struct dentry *ecryptfs_dentry = file->f_path.dentry;
  	/* Private value of ecryptfs_dentry allocated in
  	 * ecryptfs_lookup() */
  	struct ecryptfs_file_info *file_info;
  	struct file *lower_file;
  
  	/* Released in ecryptfs_release or end of function if failure */
  	file_info = kmem_cache_zalloc(ecryptfs_file_info_cache, GFP_KERNEL);
  	ecryptfs_set_file_private(file, file_info);
  	if (unlikely(!file_info)) {
  		ecryptfs_printk(KERN_ERR,
  				"Error attempting to allocate memory
  ");
  		return -ENOMEM;
  	}
  	lower_file = dentry_open(ecryptfs_dentry_to_lower_path(ecryptfs_dentry),
  				 file->f_flags, current_cred());
  	if (IS_ERR(lower_file)) {
  		printk(KERN_ERR "%s: Error attempting to initialize "
  			"the lower file for the dentry with name "
  			"[%pd]; rc = [%ld]
  ", __func__,
  			ecryptfs_dentry, PTR_ERR(lower_file));
  		kmem_cache_free(ecryptfs_file_info_cache, file_info);
  		return PTR_ERR(lower_file);
  	}
  	ecryptfs_set_file_lower(file, lower_file);
  	return 0;
  }
  
  static int ecryptfs_flush(struct file *file, fl_owner_t td)
  {
  	struct file *lower_file = ecryptfs_file_to_lower(file);
  
  	if (lower_file->f_op->flush) {
  		filemap_write_and_wait(file->f_mapping);
  		return lower_file->f_op->flush(lower_file, td);
  	}
  
  	return 0;
  }
  
  static int ecryptfs_release(struct inode *inode, struct file *file)
  {
  	ecryptfs_put_lower_file(inode);
  	kmem_cache_free(ecryptfs_file_info_cache,
  			ecryptfs_file_to_private(file));
  	return 0;
  }
  
  static int ecryptfs_dir_release(struct inode *inode, struct file *file)
  {
  	fput(ecryptfs_file_to_lower(file));
  	kmem_cache_free(ecryptfs_file_info_cache,
  			ecryptfs_file_to_private(file));
  	return 0;
  }
  
  static loff_t ecryptfs_dir_llseek(struct file *file, loff_t offset, int whence)
  {
  	return vfs_llseek(ecryptfs_file_to_lower(file), offset, whence);
  }
  
  static int
  ecryptfs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
  {
  	int rc;
  
  	rc = filemap_write_and_wait(file->f_mapping);
  	if (rc)
  		return rc;
  
  	return vfs_fsync(ecryptfs_file_to_lower(file), datasync);
  }
  
  static int ecryptfs_fasync(int fd, struct file *file, int flag)
  {
  	int rc = 0;
  	struct file *lower_file = NULL;
  
  	lower_file = ecryptfs_file_to_lower(file);
  	if (lower_file->f_op->fasync)
  		rc = lower_file->f_op->fasync(fd, lower_file, flag);
  	return rc;
  }
  
  static long
  ecryptfs_unlocked_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
  {
  	struct file *lower_file = ecryptfs_file_to_lower(file);
  	long rc = -ENOTTY;
  
  	if (!lower_file->f_op->unlocked_ioctl)
  		return rc;
  
  	switch (cmd) {
  	case FITRIM:
  	case FS_IOC_GETFLAGS:
  	case FS_IOC_SETFLAGS:
  	case FS_IOC_GETVERSION:
  	case FS_IOC_SETVERSION:
  		rc = lower_file->f_op->unlocked_ioctl(lower_file, cmd, arg);
  		fsstack_copy_attr_all(file_inode(file), file_inode(lower_file));
  
  		return rc;
  	default:
  		return rc;
  	}
  }
  
  #ifdef CONFIG_COMPAT
  static long
  ecryptfs_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
  {
  	struct file *lower_file = ecryptfs_file_to_lower(file);
  	long rc = -ENOIOCTLCMD;
  
  	if (!lower_file->f_op->compat_ioctl)
  		return rc;
  
  	switch (cmd) {
  	case FS_IOC32_GETFLAGS:
  	case FS_IOC32_SETFLAGS:
  	case FS_IOC32_GETVERSION:
  	case FS_IOC32_SETVERSION:
  		rc = lower_file->f_op->compat_ioctl(lower_file, cmd, arg);
  		fsstack_copy_attr_all(file_inode(file), file_inode(lower_file));
  
  		return rc;
  	default:
  		return rc;
  	}
  }
  #endif
  
  const struct file_operations ecryptfs_dir_fops = {
  	.iterate = ecryptfs_readdir,
  	.read = generic_read_dir,
  	.unlocked_ioctl = ecryptfs_unlocked_ioctl,
  #ifdef CONFIG_COMPAT
  	.compat_ioctl = ecryptfs_compat_ioctl,
  #endif
  	.open = ecryptfs_dir_open,
  	.release = ecryptfs_dir_release,
  	.fsync = ecryptfs_fsync,
  	.llseek = ecryptfs_dir_llseek,
  };
  
  const struct file_operations ecryptfs_main_fops = {
  	.llseek = generic_file_llseek,
  	.read_iter = ecryptfs_read_update_atime,
  	.write_iter = generic_file_write_iter,
  	.unlocked_ioctl = ecryptfs_unlocked_ioctl,
  #ifdef CONFIG_COMPAT
  	.compat_ioctl = ecryptfs_compat_ioctl,
  #endif
  	.mmap = ecryptfs_mmap,
  	.open = ecryptfs_open,
  	.flush = ecryptfs_flush,
  	.release = ecryptfs_release,
  	.fsync = ecryptfs_fsync,
  	.fasync = ecryptfs_fasync,
  	.splice_read = generic_file_splice_read,
  };