/*

   * fs/f2fs/acl.c
   *
   * Copyright (c) 2012 Samsung Electronics Co., Ltd.
   *             http://www.samsung.com/
   *
   * Portions of this code from linux/fs/ext2/acl.c
   *
   * Copyright (C) 2001-2003 Andreas Gruenbacher, <agruen@suse.de>
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License version 2 as
   * published by the Free Software Foundation.
   */
  #include <linux/f2fs_fs.h>
  #include "f2fs.h"
  #include "xattr.h"
  #include "acl.h"

  static inline size_t f2fs_acl_size(int count)
  {
  	if (count <= 4) {
  		return sizeof(struct f2fs_acl_header) +
  			count * sizeof(struct f2fs_acl_entry_short);
  	} else {
  		return sizeof(struct f2fs_acl_header) +
  			4 * sizeof(struct f2fs_acl_entry_short) +
  			(count - 4) * sizeof(struct f2fs_acl_entry);
  	}
  }
  
  static inline int f2fs_acl_count(size_t size)
  {
  	ssize_t s;
  	size -= sizeof(struct f2fs_acl_header);
  	s = size - 4 * sizeof(struct f2fs_acl_entry_short);
  	if (s < 0) {
  		if (size % sizeof(struct f2fs_acl_entry_short))
  			return -1;
  		return size / sizeof(struct f2fs_acl_entry_short);
  	} else {
  		if (s % sizeof(struct f2fs_acl_entry))
  			return -1;
  		return s / sizeof(struct f2fs_acl_entry) + 4;
  	}
  }
  
  static struct posix_acl *f2fs_acl_from_disk(const char *value, size_t size)
  {
  	int i, count;
  	struct posix_acl *acl;
  	struct f2fs_acl_header *hdr = (struct f2fs_acl_header *)value;
  	struct f2fs_acl_entry *entry = (struct f2fs_acl_entry *)(hdr + 1);
  	const char *end = value + size;
  
  	if (hdr->a_version != cpu_to_le32(F2FS_ACL_VERSION))
  		return ERR_PTR(-EINVAL);
  
  	count = f2fs_acl_count(size);
  	if (count < 0)
  		return ERR_PTR(-EINVAL);
  	if (count == 0)
  		return NULL;

  	acl = posix_acl_alloc(count, GFP_NOFS);

  	if (!acl)
  		return ERR_PTR(-ENOMEM);
  
  	for (i = 0; i < count; i++) {
  
  		if ((char *)entry > end)
  			goto fail;
  
  		acl->a_entries[i].e_tag  = le16_to_cpu(entry->e_tag);
  		acl->a_entries[i].e_perm = le16_to_cpu(entry->e_perm);
  
  		switch (acl->a_entries[i].e_tag) {
  		case ACL_USER_OBJ:
  		case ACL_GROUP_OBJ:
  		case ACL_MASK:
  		case ACL_OTHER:

  			entry = (struct f2fs_acl_entry *)((char *)entry +
  					sizeof(struct f2fs_acl_entry_short));
  			break;
  
  		case ACL_USER:
  			acl->a_entries[i].e_uid =
  				make_kuid(&init_user_ns,
  						le32_to_cpu(entry->e_id));
  			entry = (struct f2fs_acl_entry *)((char *)entry +
  					sizeof(struct f2fs_acl_entry));
  			break;
  		case ACL_GROUP:
  			acl->a_entries[i].e_gid =
  				make_kgid(&init_user_ns,
  						le32_to_cpu(entry->e_id));
  			entry = (struct f2fs_acl_entry *)((char *)entry +
  					sizeof(struct f2fs_acl_entry));
  			break;
  		default:
  			goto fail;
  		}
  	}
  	if ((char *)entry != end)
  		goto fail;
  	return acl;
  fail:
  	posix_acl_release(acl);
  	return ERR_PTR(-EINVAL);
  }

  static void *f2fs_acl_to_disk(struct f2fs_sb_info *sbi,
  				const struct posix_acl *acl, size_t *size)

  {
  	struct f2fs_acl_header *f2fs_acl;
  	struct f2fs_acl_entry *entry;
  	int i;

  	f2fs_acl = f2fs_kmalloc(sbi, sizeof(struct f2fs_acl_header) +
  			acl->a_count * sizeof(struct f2fs_acl_entry),
  			GFP_NOFS);

  	if (!f2fs_acl)
  		return ERR_PTR(-ENOMEM);
  
  	f2fs_acl->a_version = cpu_to_le32(F2FS_ACL_VERSION);
  	entry = (struct f2fs_acl_entry *)(f2fs_acl + 1);
  
  	for (i = 0; i < acl->a_count; i++) {
  
  		entry->e_tag  = cpu_to_le16(acl->a_entries[i].e_tag);
  		entry->e_perm = cpu_to_le16(acl->a_entries[i].e_perm);
  
  		switch (acl->a_entries[i].e_tag) {
  		case ACL_USER:
  			entry->e_id = cpu_to_le32(
  					from_kuid(&init_user_ns,
  						acl->a_entries[i].e_uid));
  			entry = (struct f2fs_acl_entry *)((char *)entry +
  					sizeof(struct f2fs_acl_entry));
  			break;
  		case ACL_GROUP:
  			entry->e_id = cpu_to_le32(
  					from_kgid(&init_user_ns,
  						acl->a_entries[i].e_gid));
  			entry = (struct f2fs_acl_entry *)((char *)entry +
  					sizeof(struct f2fs_acl_entry));
  			break;
  		case ACL_USER_OBJ:
  		case ACL_GROUP_OBJ:
  		case ACL_MASK:
  		case ACL_OTHER:
  			entry = (struct f2fs_acl_entry *)((char *)entry +
  					sizeof(struct f2fs_acl_entry_short));
  			break;
  		default:
  			goto fail;
  		}
  	}
  	*size = f2fs_acl_size(acl->a_count);
  	return (void *)f2fs_acl;
  
  fail:
  	kfree(f2fs_acl);
  	return ERR_PTR(-EINVAL);
  }

  static struct posix_acl *__f2fs_get_acl(struct inode *inode, int type,
  						struct page *dpage)

  {

  	int name_index = F2FS_XATTR_INDEX_POSIX_ACL_DEFAULT;
  	void *value = NULL;
  	struct posix_acl *acl;
  	int retval;

  	if (type == ACL_TYPE_ACCESS)
  		name_index = F2FS_XATTR_INDEX_POSIX_ACL_ACCESS;

  	retval = f2fs_getxattr(inode, name_index, "", NULL, 0, dpage);

  	if (retval > 0) {

  		value = f2fs_kmalloc(F2FS_I_SB(inode), retval, GFP_F2FS_ZERO);

  		if (!value)
  			return ERR_PTR(-ENOMEM);

  		retval = f2fs_getxattr(inode, name_index, "", value,
  							retval, dpage);

  	}

  	if (retval > 0)

  		acl = f2fs_acl_from_disk(value, retval);

  	else if (retval == -ENODATA)
  		acl = NULL;
  	else
  		acl = ERR_PTR(retval);

  	kfree(value);

  	return acl;
  }

  struct posix_acl *f2fs_get_acl(struct inode *inode, int type)
  {
  	return __f2fs_get_acl(inode, type, NULL);
  }

  static int __f2fs_set_acl(struct inode *inode, int type,

  			struct posix_acl *acl, struct page *ipage)

  {

  	int name_index;
  	void *value = NULL;
  	size_t size = 0;
  	int error;

  	switch (type) {
  	case ACL_TYPE_ACCESS:
  		name_index = F2FS_XATTR_INDEX_POSIX_ACL_ACCESS;
  		if (acl) {

  			error = posix_acl_update_mode(inode, &inode->i_mode, &acl);
  			if (error)

  				return error;

  			set_acl_inode(inode, inode->i_mode);

  		}
  		break;
  
  	case ACL_TYPE_DEFAULT:
  		name_index = F2FS_XATTR_INDEX_POSIX_ACL_DEFAULT;
  		if (!S_ISDIR(inode->i_mode))
  			return acl ? -EACCES : 0;
  		break;
  
  	default:
  		return -EINVAL;
  	}
  
  	if (acl) {

  		value = f2fs_acl_to_disk(F2FS_I_SB(inode), acl, &size);

  		if (IS_ERR(value)) {

  			clear_inode_flag(inode, FI_ACL_MODE);

  			return (int)PTR_ERR(value);
  		}
  	}

  	error = f2fs_setxattr(inode, name_index, "", value, size, ipage, 0);

  
  	kfree(value);
  	if (!error)
  		set_cached_acl(inode, type, acl);

  	clear_inode_flag(inode, FI_ACL_MODE);

  	return error;
  }

  int f2fs_set_acl(struct inode *inode, struct posix_acl *acl, int type)

  {

  	return __f2fs_set_acl(inode, type, acl, NULL);

  }

  /*
   * Most part of f2fs_acl_clone, f2fs_acl_create_masq, f2fs_acl_create
   * are copied from posix_acl.c
   */
  static struct posix_acl *f2fs_acl_clone(const struct posix_acl *acl,
  							gfp_t flags)
  {
  	struct posix_acl *clone = NULL;
  
  	if (acl) {
  		int size = sizeof(struct posix_acl) + acl->a_count *
  				sizeof(struct posix_acl_entry);
  		clone = kmemdup(acl, size, flags);
  		if (clone)
  			atomic_set(&clone->a_refcount, 1);
  	}
  	return clone;
  }
  
  static int f2fs_acl_create_masq(struct posix_acl *acl, umode_t *mode_p)
  {
  	struct posix_acl_entry *pa, *pe;
  	struct posix_acl_entry *group_obj = NULL, *mask_obj = NULL;
  	umode_t mode = *mode_p;
  	int not_equiv = 0;
  
  	/* assert(atomic_read(acl->a_refcount) == 1); */
  
  	FOREACH_ACL_ENTRY(pa, acl, pe) {
  		switch(pa->e_tag) {
  		case ACL_USER_OBJ:
  			pa->e_perm &= (mode >> 6) | ~S_IRWXO;
  			mode &= (pa->e_perm << 6) | ~S_IRWXU;
  			break;
  
  		case ACL_USER:
  		case ACL_GROUP:
  			not_equiv = 1;
  			break;
  
  		case ACL_GROUP_OBJ:
  			group_obj = pa;
  			break;
  
  		case ACL_OTHER:
  			pa->e_perm &= mode | ~S_IRWXO;
  			mode &= pa->e_perm | ~S_IRWXO;
  			break;
  
  		case ACL_MASK:
  			mask_obj = pa;
  			not_equiv = 1;
  			break;
  
  		default:
  			return -EIO;
  		}
  	}
  
  	if (mask_obj) {
  		mask_obj->e_perm &= (mode >> 3) | ~S_IRWXO;
  		mode &= (mask_obj->e_perm << 3) | ~S_IRWXG;
  	} else {
  		if (!group_obj)
  			return -EIO;
  		group_obj->e_perm &= (mode >> 3) | ~S_IRWXO;
  		mode &= (group_obj->e_perm << 3) | ~S_IRWXG;
  	}
  
  	*mode_p = (*mode_p & ~S_IRWXUGO) | mode;
          return not_equiv;
  }
  
  static int f2fs_acl_create(struct inode *dir, umode_t *mode,
  		struct posix_acl **default_acl, struct posix_acl **acl,
  		struct page *dpage)
  {
  	struct posix_acl *p;

  	struct posix_acl *clone;

  	int ret;

  	*acl = NULL;
  	*default_acl = NULL;

  	if (S_ISLNK(*mode) || !IS_POSIXACL(dir))

  		return 0;

  
  	p = __f2fs_get_acl(dir, ACL_TYPE_DEFAULT, dpage);

  	if (!p || p == ERR_PTR(-EOPNOTSUPP)) {
  		*mode &= ~current_umask();
  		return 0;

  	}

  	if (IS_ERR(p))
  		return PTR_ERR(p);

  	clone = f2fs_acl_clone(p, GFP_NOFS);
  	if (!clone)

  		goto no_mem;

  	ret = f2fs_acl_create_masq(clone, mode);

  	if (ret < 0)
  		goto no_mem_clone;

  	if (ret == 0)
  		posix_acl_release(clone);
  	else
  		*acl = clone;

  	if (!S_ISDIR(*mode))

  		posix_acl_release(p);

  	else

  		*default_acl = p;

  	return 0;

  
  no_mem_clone:

  	posix_acl_release(clone);

  no_mem:
  	posix_acl_release(p);
  	return -ENOMEM;

  }
  
  int f2fs_init_acl(struct inode *inode, struct inode *dir, struct page *ipage,
  							struct page *dpage)

  {

  	struct posix_acl *default_acl = NULL, *acl = NULL;

  	int error = 0;

  	error = f2fs_acl_create(dir, &inode->i_mode, &default_acl, &acl, dpage);

  	if (error)
  		return error;

  	f2fs_mark_inode_dirty_sync(inode);

  	if (default_acl) {
  		error = __f2fs_set_acl(inode, ACL_TYPE_DEFAULT, default_acl,
  				       ipage);
  		posix_acl_release(default_acl);
  	}
  	if (acl) {

  		if (!error)

  			error = __f2fs_set_acl(inode, ACL_TYPE_ACCESS, acl,
  					       ipage);
  		posix_acl_release(acl);

  	}

  	return error;
  }