// SPDX-License-Identifier: GPL-2.0

  #include "ubifs.h"
  
  static int ubifs_crypt_get_context(struct inode *inode, void *ctx, size_t len)
  {
  	return ubifs_xattr_get(inode, UBIFS_XATTR_NAME_ENCRYPTION_CONTEXT,
  			       ctx, len);
  }
  
  static int ubifs_crypt_set_context(struct inode *inode, const void *ctx,
  				   size_t len, void *fs_data)
  {

  	/*
  	 * Creating an encryption context is done unlocked since we
  	 * operate on a new inode which is not visible to other users
  	 * at this point. So, no need to check whether inode is locked.
  	 */

  	return ubifs_xattr_set(inode, UBIFS_XATTR_NAME_ENCRYPTION_CONTEXT,

  			       ctx, len, 0, false);

  }
  
  static bool ubifs_crypt_empty_dir(struct inode *inode)
  {
  	return ubifs_check_dir_empty(inode) == 0;
  }
  
  static unsigned int ubifs_crypt_max_namelen(struct inode *inode)
  {
  	if (S_ISLNK(inode->i_mode))
  		return UBIFS_MAX_INO_DATA;
  	else
  		return UBIFS_MAX_NLEN;
  }

  int ubifs_encrypt(const struct inode *inode, struct ubifs_data_node *dn,
  		  unsigned int in_len, unsigned int *out_len, int block)
  {
  	struct ubifs_info *c = inode->i_sb->s_fs_info;
  	void *p = &dn->data;
  	struct page *ret;
  	unsigned int pad_len = round_up(in_len, UBIFS_CIPHER_BLOCK_SIZE);
  
  	ubifs_assert(pad_len <= *out_len);
  	dn->compr_size = cpu_to_le16(in_len);
  
  	/* pad to full block cipher length */
  	if (pad_len != in_len)
  		memset(p + in_len, 0, pad_len - in_len);
  
  	ret = fscrypt_encrypt_page(inode, virt_to_page(&dn->data), pad_len,
  			offset_in_page(&dn->data), block, GFP_NOFS);
  	if (IS_ERR(ret)) {
  		ubifs_err(c, "fscrypt_encrypt_page failed: %ld", PTR_ERR(ret));
  		return PTR_ERR(ret);
  	}
  	*out_len = pad_len;
  
  	return 0;
  }
  
  int ubifs_decrypt(const struct inode *inode, struct ubifs_data_node *dn,
  		  unsigned int *out_len, int block)
  {
  	struct ubifs_info *c = inode->i_sb->s_fs_info;
  	int err;
  	unsigned int clen = le16_to_cpu(dn->compr_size);
  	unsigned int dlen = *out_len;
  
  	if (clen <= 0 || clen > UBIFS_BLOCK_SIZE || clen > dlen) {
  		ubifs_err(c, "bad compr_size: %i", clen);
  		return -EINVAL;
  	}
  
  	ubifs_assert(dlen <= UBIFS_BLOCK_SIZE);
  	err = fscrypt_decrypt_page(inode, virt_to_page(&dn->data), dlen,
  			offset_in_page(&dn->data), block);
  	if (err) {
  		ubifs_err(c, "fscrypt_decrypt_page failed: %i", err);
  		return err;
  	}
  	*out_len = clen;
  
  	return 0;
  }

  const struct fscrypt_operations ubifs_crypt_operations = {

  	.flags			= FS_CFLG_OWN_PAGES,

  	.key_prefix		= "ubifs:",

  	.get_context		= ubifs_crypt_get_context,
  	.set_context		= ubifs_crypt_set_context,

  	.is_encrypted		= __ubifs_crypt_is_encrypted,

  	.empty_dir		= ubifs_crypt_empty_dir,
  	.max_namelen		= ubifs_crypt_max_namelen,

  };