/*
   * linux/fs/ext2/acl.c
   *
   * Copyright (C) 2001-2003 Andreas Gruenbacher, <agruen@suse.de>
   */

  #include <linux/capability.h>

  #include <linux/init.h>
  #include <linux/sched.h>
  #include <linux/slab.h>
  #include <linux/fs.h>
  #include "ext2.h"
  #include "xattr.h"
  #include "acl.h"
  
  /*
   * Convert from filesystem to in-memory representation.
   */
  static struct posix_acl *
  ext2_acl_from_disk(const void *value, size_t size)
  {
  	const char *end = (char *)value + size;
  	int n, count;
  	struct posix_acl *acl;
  
  	if (!value)
  		return NULL;
  	if (size < sizeof(ext2_acl_header))
  		 return ERR_PTR(-EINVAL);
  	if (((ext2_acl_header *)value)->a_version !=
  	    cpu_to_le32(EXT2_ACL_VERSION))
  		return ERR_PTR(-EINVAL);
  	value = (char *)value + sizeof(ext2_acl_header);
  	count = ext2_acl_count(size);
  	if (count < 0)
  		return ERR_PTR(-EINVAL);
  	if (count == 0)
  		return NULL;
  	acl = posix_acl_alloc(count, GFP_KERNEL);
  	if (!acl)
  		return ERR_PTR(-ENOMEM);
  	for (n=0; n < count; n++) {
  		ext2_acl_entry *entry =
  			(ext2_acl_entry *)value;
  		if ((char *)value + sizeof(ext2_acl_entry_short) > end)
  			goto fail;
  		acl->a_entries[n].e_tag  = le16_to_cpu(entry->e_tag);
  		acl->a_entries[n].e_perm = le16_to_cpu(entry->e_perm);
  		switch(acl->a_entries[n].e_tag) {
  			case ACL_USER_OBJ:
  			case ACL_GROUP_OBJ:
  			case ACL_MASK:
  			case ACL_OTHER:
  				value = (char *)value +
  					sizeof(ext2_acl_entry_short);
  				acl->a_entries[n].e_id = ACL_UNDEFINED_ID;
  				break;
  
  			case ACL_USER:
  			case ACL_GROUP:
  				value = (char *)value + sizeof(ext2_acl_entry);
  				if ((char *)value > end)
  					goto fail;
  				acl->a_entries[n].e_id =
  					le32_to_cpu(entry->e_id);
  				break;
  
  			default:
  				goto fail;
  		}
  	}
  	if (value != end)
  		goto fail;
  	return acl;
  
  fail:
  	posix_acl_release(acl);
  	return ERR_PTR(-EINVAL);
  }
  
  /*
   * Convert from in-memory to filesystem representation.
   */
  static void *
  ext2_acl_to_disk(const struct posix_acl *acl, size_t *size)
  {
  	ext2_acl_header *ext_acl;
  	char *e;
  	size_t n;
  
  	*size = ext2_acl_size(acl->a_count);

  	ext_acl = kmalloc(sizeof(ext2_acl_header) + acl->a_count *
  			sizeof(ext2_acl_entry), GFP_KERNEL);

  	if (!ext_acl)
  		return ERR_PTR(-ENOMEM);
  	ext_acl->a_version = cpu_to_le32(EXT2_ACL_VERSION);
  	e = (char *)ext_acl + sizeof(ext2_acl_header);
  	for (n=0; n < acl->a_count; n++) {
  		ext2_acl_entry *entry = (ext2_acl_entry *)e;
  		entry->e_tag  = cpu_to_le16(acl->a_entries[n].e_tag);
  		entry->e_perm = cpu_to_le16(acl->a_entries[n].e_perm);
  		switch(acl->a_entries[n].e_tag) {
  			case ACL_USER:
  			case ACL_GROUP:
  				entry->e_id =
  					cpu_to_le32(acl->a_entries[n].e_id);
  				e += sizeof(ext2_acl_entry);
  				break;
  
  			case ACL_USER_OBJ:
  			case ACL_GROUP_OBJ:
  			case ACL_MASK:
  			case ACL_OTHER:
  				e += sizeof(ext2_acl_entry_short);
  				break;
  
  			default:
  				goto fail;
  		}
  	}
  	return (char *)ext_acl;
  
  fail:
  	kfree(ext_acl);
  	return ERR_PTR(-EINVAL);
  }

  /*

   * inode->i_mutex: don't care

   */

  struct posix_acl *

  ext2_get_acl(struct inode *inode, int type)
  {

  	int name_index;
  	char *value = NULL;
  	struct posix_acl *acl;
  	int retval;
  
  	if (!test_opt(inode->i_sb, POSIX_ACL))
  		return NULL;

  	acl = get_cached_acl(inode, type);
  	if (acl != ACL_NOT_CACHED)
  		return acl;
  
  	switch (type) {
  	case ACL_TYPE_ACCESS:
  		name_index = EXT2_XATTR_INDEX_POSIX_ACL_ACCESS;
  		break;
  	case ACL_TYPE_DEFAULT:
  		name_index = EXT2_XATTR_INDEX_POSIX_ACL_DEFAULT;
  		break;
  	default:
  		BUG();

  	}
  	retval = ext2_xattr_get(inode, name_index, "", NULL, 0);
  	if (retval > 0) {
  		value = kmalloc(retval, GFP_KERNEL);
  		if (!value)
  			return ERR_PTR(-ENOMEM);
  		retval = ext2_xattr_get(inode, name_index, "", value, retval);
  	}
  	if (retval > 0)
  		acl = ext2_acl_from_disk(value, retval);
  	else if (retval == -ENODATA || retval == -ENOSYS)
  		acl = NULL;
  	else
  		acl = ERR_PTR(retval);

  	kfree(value);

  	if (!IS_ERR(acl))
  		set_cached_acl(inode, type, acl);

  	return acl;
  }
  
  /*

   * inode->i_mutex: down

   */
  static int
  ext2_set_acl(struct inode *inode, int type, struct posix_acl *acl)
  {

  	int name_index;
  	void *value = NULL;

  	size_t size = 0;

  	int error;
  
  	if (S_ISLNK(inode->i_mode))
  		return -EOPNOTSUPP;
  	if (!test_opt(inode->i_sb, POSIX_ACL))
  		return 0;
  
  	switch(type) {
  		case ACL_TYPE_ACCESS:
  			name_index = EXT2_XATTR_INDEX_POSIX_ACL_ACCESS;
  			if (acl) {

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

  				if (error < 0)
  					return error;
  				else {

  					inode->i_ctime = CURRENT_TIME_SEC;

  					mark_inode_dirty(inode);
  					if (error == 0)
  						acl = NULL;
  				}
  			}
  			break;
  
  		case ACL_TYPE_DEFAULT:
  			name_index = EXT2_XATTR_INDEX_POSIX_ACL_DEFAULT;
  			if (!S_ISDIR(inode->i_mode))
  				return acl ? -EACCES : 0;
  			break;
  
  		default:
  			return -EINVAL;
  	}
   	if (acl) {
  		value = ext2_acl_to_disk(acl, &size);
  		if (IS_ERR(value))
  			return (int)PTR_ERR(value);
  	}
  
  	error = ext2_xattr_set(inode, name_index, "", value, size, 0);

  	kfree(value);

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

  	return error;
  }

  /*
   * Initialize the ACLs of a new inode. Called from ext2_new_inode.
   *

   * dir->i_mutex: down
   * inode->i_mutex: up (access to inode is still exclusive)

   */
  int
  ext2_init_acl(struct inode *inode, struct inode *dir)
  {
  	struct posix_acl *acl = NULL;
  	int error = 0;
  
  	if (!S_ISLNK(inode->i_mode)) {
  		if (test_opt(dir->i_sb, POSIX_ACL)) {
  			acl = ext2_get_acl(dir, ACL_TYPE_DEFAULT);
  			if (IS_ERR(acl))
  				return PTR_ERR(acl);
  		}
  		if (!acl)

  			inode->i_mode &= ~current_umask();

  	}
  	if (test_opt(inode->i_sb, POSIX_ACL) && acl) {

  		if (S_ISDIR(inode->i_mode)) {
  			error = ext2_set_acl(inode, ACL_TYPE_DEFAULT, acl);
  			if (error)
  				goto cleanup;
  		}

  		error = posix_acl_create(&acl, GFP_KERNEL, &inode->i_mode);

  		if (error < 0)
  			return error;

  		if (error > 0) {
  			/* This is an extended ACL */
  			error = ext2_set_acl(inode, ACL_TYPE_ACCESS, acl);

  		}

  	}
  cleanup:
         posix_acl_release(acl);
         return error;
  }
  
  /*
   * Does chmod for an inode that may have an Access Control List. The
   * inode->i_mode field must be updated to the desired value by the caller
   * before calling this function.
   * Returns 0 on success, or a negative error number.
   *
   * We change the ACL rather than storing some ACL entries in the file
   * mode permission bits (which would be more efficient), because that
   * would break once additional permissions (like  ACL_APPEND, ACL_DELETE
   * for directories) are added. There are no more bits available in the
   * file mode.
   *

   * inode->i_mutex: down

   */
  int
  ext2_acl_chmod(struct inode *inode)
  {

  	struct posix_acl *acl;

          int error;
  
  	if (!test_opt(inode->i_sb, POSIX_ACL))
  		return 0;
  	if (S_ISLNK(inode->i_mode))
  		return -EOPNOTSUPP;
  	acl = ext2_get_acl(inode, ACL_TYPE_ACCESS);
  	if (IS_ERR(acl) || !acl)
  		return PTR_ERR(acl);

  	error = posix_acl_chmod(&acl, GFP_KERNEL, inode->i_mode);
  	if (error)
  		return error;
  	error = ext2_set_acl(inode, ACL_TYPE_ACCESS, acl);

  	posix_acl_release(acl);

  	return error;
  }
  
  /*
   * Extended attribut handlers
   */
  static size_t

  ext2_xattr_list_acl_access(struct dentry *dentry, char *list, size_t list_size,
  			   const char *name, size_t name_len, int type)

  {

  	const size_t size = sizeof(POSIX_ACL_XATTR_ACCESS);

  	if (!test_opt(dentry->d_sb, POSIX_ACL))

  		return 0;
  	if (list && size <= list_size)

  		memcpy(list, POSIX_ACL_XATTR_ACCESS, size);

  	return size;
  }
  
  static size_t

  ext2_xattr_list_acl_default(struct dentry *dentry, char *list, size_t list_size,
  			    const char *name, size_t name_len, int type)

  {

  	const size_t size = sizeof(POSIX_ACL_XATTR_DEFAULT);

  	if (!test_opt(dentry->d_sb, POSIX_ACL))

  		return 0;
  	if (list && size <= list_size)

  		memcpy(list, POSIX_ACL_XATTR_DEFAULT, size);

  	return size;
  }
  
  static int

  ext2_xattr_get_acl(struct dentry *dentry, const char *name, void *buffer,
  		   size_t size, int type)

  {
  	struct posix_acl *acl;
  	int error;

  	if (strcmp(name, "") != 0)
  		return -EINVAL;
  	if (!test_opt(dentry->d_sb, POSIX_ACL))

  		return -EOPNOTSUPP;

  	acl = ext2_get_acl(dentry->d_inode, type);

  	if (IS_ERR(acl))
  		return PTR_ERR(acl);
  	if (acl == NULL)
  		return -ENODATA;
  	error = posix_acl_to_xattr(acl, buffer, size);
  	posix_acl_release(acl);
  
  	return error;
  }
  
  static int

  ext2_xattr_set_acl(struct dentry *dentry, const char *name, const void *value,
  		   size_t size, int flags, int type)

  {
  	struct posix_acl *acl;
  	int error;

  	if (strcmp(name, "") != 0)
  		return -EINVAL;
  	if (!test_opt(dentry->d_sb, POSIX_ACL))

  		return -EOPNOTSUPP;

  	if (!inode_owner_or_capable(dentry->d_inode))

  		return -EPERM;
  
  	if (value) {
  		acl = posix_acl_from_xattr(value, size);
  		if (IS_ERR(acl))
  			return PTR_ERR(acl);
  		else if (acl) {
  			error = posix_acl_valid(acl);
  			if (error)
  				goto release_and_out;
  		}
  	} else
  		acl = NULL;

  	error = ext2_set_acl(dentry->d_inode, type, acl);

  
  release_and_out:
  	posix_acl_release(acl);
  	return error;
  }

  const struct xattr_handler ext2_xattr_acl_access_handler = {

  	.prefix	= POSIX_ACL_XATTR_ACCESS,

  	.flags	= ACL_TYPE_ACCESS,

  	.list	= ext2_xattr_list_acl_access,

  	.get	= ext2_xattr_get_acl,
  	.set	= ext2_xattr_set_acl,

  };

  const struct xattr_handler ext2_xattr_acl_default_handler = {

  	.prefix	= POSIX_ACL_XATTR_DEFAULT,

  	.flags	= ACL_TYPE_DEFAULT,

  	.list	= ext2_xattr_list_acl_default,

  	.get	= ext2_xattr_get_acl,
  	.set	= ext2_xattr_set_acl,

  };