/*
   * Copyright (c) 2008, Christoph Hellwig
   * All Rights Reserved.
   *
   * 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.
   *
   * This program is distributed in the hope that it would 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 the Free Software Foundation,
   * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
   */
  #include "xfs.h"
  #include "xfs_acl.h"
  #include "xfs_attr.h"
  #include "xfs_bmap_btree.h"
  #include "xfs_inode.h"
  #include "xfs_vnodeops.h"

  #include "xfs_trace.h"

  #include <linux/slab.h>

  #include <linux/xattr.h>
  #include <linux/posix_acl_xattr.h>

  /*
   * Locking scheme:
   *  - all ACL updates are protected by inode->i_mutex, which is taken before
   *    calling into this file.

   */
  
  STATIC struct posix_acl *
  xfs_acl_from_disk(struct xfs_acl *aclp)
  {
  	struct posix_acl_entry *acl_e;
  	struct posix_acl *acl;
  	struct xfs_acl_entry *ace;

  	unsigned int count, i;

  
  	count = be32_to_cpu(aclp->acl_cnt);

  	if (count > XFS_ACL_MAX_ENTRIES)
  		return ERR_PTR(-EFSCORRUPTED);

  
  	acl = posix_acl_alloc(count, GFP_KERNEL);
  	if (!acl)
  		return ERR_PTR(-ENOMEM);
  
  	for (i = 0; i < count; i++) {
  		acl_e = &acl->a_entries[i];
  		ace = &aclp->acl_entry[i];
  
  		/*
  		 * The tag is 32 bits on disk and 16 bits in core.
  		 *
  		 * Because every access to it goes through the core
  		 * format first this is not a problem.
  		 */
  		acl_e->e_tag = be32_to_cpu(ace->ae_tag);
  		acl_e->e_perm = be16_to_cpu(ace->ae_perm);
  
  		switch (acl_e->e_tag) {
  		case ACL_USER:
  		case ACL_GROUP:
  			acl_e->e_id = be32_to_cpu(ace->ae_id);
  			break;
  		case ACL_USER_OBJ:
  		case ACL_GROUP_OBJ:
  		case ACL_MASK:
  		case ACL_OTHER:
  			acl_e->e_id = ACL_UNDEFINED_ID;
  			break;
  		default:
  			goto fail;
  		}
  	}
  	return acl;
  
  fail:
  	posix_acl_release(acl);
  	return ERR_PTR(-EINVAL);
  }
  
  STATIC void
  xfs_acl_to_disk(struct xfs_acl *aclp, const struct posix_acl *acl)
  {
  	const struct posix_acl_entry *acl_e;
  	struct xfs_acl_entry *ace;
  	int i;
  
  	aclp->acl_cnt = cpu_to_be32(acl->a_count);
  	for (i = 0; i < acl->a_count; i++) {
  		ace = &aclp->acl_entry[i];
  		acl_e = &acl->a_entries[i];
  
  		ace->ae_tag = cpu_to_be32(acl_e->e_tag);
  		ace->ae_id = cpu_to_be32(acl_e->e_id);
  		ace->ae_perm = cpu_to_be16(acl_e->e_perm);
  	}
  }

  struct posix_acl *
  xfs_get_acl(struct inode *inode, int type)
  {
  	struct xfs_inode *ip = XFS_I(inode);

  	struct posix_acl *acl;

  	struct xfs_acl *xfs_acl;
  	int len = sizeof(struct xfs_acl);

  	unsigned char *ea_name;

  	int error;

  	acl = get_cached_acl(inode, type);
  	if (acl != ACL_NOT_CACHED)
  		return acl;

  	trace_xfs_get_acl(ip);

  	switch (type) {
  	case ACL_TYPE_ACCESS:
  		ea_name = SGI_ACL_FILE;

  		break;
  	case ACL_TYPE_DEFAULT:
  		ea_name = SGI_ACL_DEFAULT;

  		break;
  	default:

  		BUG();

  	}

  	/*
  	 * If we have a cached ACLs value just return it, not need to
  	 * go out to the disk.
  	 */

  
  	xfs_acl = kzalloc(sizeof(struct xfs_acl), GFP_KERNEL);
  	if (!xfs_acl)
  		return ERR_PTR(-ENOMEM);

  	error = -xfs_attr_get(ip, ea_name, (unsigned char *)xfs_acl,
  							&len, ATTR_ROOT);

  	if (error) {
  		/*
  		 * If the attribute doesn't exist make sure we have a negative
  		 * cache entry, for any other error assume it is transient and

  		 * leave the cache entry as ACL_NOT_CACHED.

  		 */
  		if (error == -ENOATTR) {
  			acl = NULL;
  			goto out_update_cache;
  		}
  		goto out;
  	}
  
  	acl = xfs_acl_from_disk(xfs_acl);
  	if (IS_ERR(acl))
  		goto out;
  
   out_update_cache:

  	set_cached_acl(inode, type, acl);

   out:
  	kfree(xfs_acl);
  	return acl;
  }
  
  STATIC int
  xfs_set_acl(struct inode *inode, int type, struct posix_acl *acl)
  {
  	struct xfs_inode *ip = XFS_I(inode);

  	unsigned char *ea_name;

  	int error;
  
  	if (S_ISLNK(inode->i_mode))
  		return -EOPNOTSUPP;
  
  	switch (type) {
  	case ACL_TYPE_ACCESS:
  		ea_name = SGI_ACL_FILE;

  		break;
  	case ACL_TYPE_DEFAULT:
  		if (!S_ISDIR(inode->i_mode))
  			return acl ? -EACCES : 0;
  		ea_name = SGI_ACL_DEFAULT;

  		break;
  	default:
  		return -EINVAL;
  	}
  
  	if (acl) {
  		struct xfs_acl *xfs_acl;
  		int len;
  
  		xfs_acl = kzalloc(sizeof(struct xfs_acl), GFP_KERNEL);
  		if (!xfs_acl)
  			return -ENOMEM;
  
  		xfs_acl_to_disk(xfs_acl, acl);
  		len = sizeof(struct xfs_acl) -
  			(sizeof(struct xfs_acl_entry) *
  			 (XFS_ACL_MAX_ENTRIES - acl->a_count));

  		error = -xfs_attr_set(ip, ea_name, (unsigned char *)xfs_acl,

  				len, ATTR_ROOT);
  
  		kfree(xfs_acl);
  	} else {
  		/*
  		 * A NULL ACL argument means we want to remove the ACL.
  		 */
  		error = -xfs_attr_remove(ip, ea_name, ATTR_ROOT);
  
  		/*
  		 * If the attribute didn't exist to start with that's fine.
  		 */
  		if (error == -ENOATTR)
  			error = 0;
  	}
  
  	if (!error)

  		set_cached_acl(inode, type, acl);

  	return error;
  }

  static int

  xfs_set_mode(struct inode *inode, umode_t mode)

  {
  	int error = 0;
  
  	if (mode != inode->i_mode) {
  		struct iattr iattr;

  		iattr.ia_valid = ATTR_MODE | ATTR_CTIME;

  		iattr.ia_mode = mode;

  		iattr.ia_ctime = current_fs_time(inode->i_sb);

  		error = -xfs_setattr_nonsize(XFS_I(inode), &iattr, XFS_ATTR_NOACL);

  	}
  
  	return error;
  }
  
  static int

  xfs_acl_exists(struct inode *inode, unsigned char *name)

  {
  	int len = sizeof(struct xfs_acl);
  
  	return (xfs_attr_get(XFS_I(inode), name, NULL, &len,
  			    ATTR_ROOT|ATTR_KERNOVAL) == 0);
  }
  
  int
  posix_acl_access_exists(struct inode *inode)
  {
  	return xfs_acl_exists(inode, SGI_ACL_FILE);
  }
  
  int
  posix_acl_default_exists(struct inode *inode)
  {
  	if (!S_ISDIR(inode->i_mode))
  		return 0;
  	return xfs_acl_exists(inode, SGI_ACL_DEFAULT);
  }
  
  /*
   * No need for i_mutex because the inode is not yet exposed to the VFS.
   */
  int

  xfs_inherit_acl(struct inode *inode, struct posix_acl *acl)

  {

  	umode_t mode = inode->i_mode;

  	int error = 0, inherit = 0;
  
  	if (S_ISDIR(inode->i_mode)) {

  		error = xfs_set_acl(inode, ACL_TYPE_DEFAULT, acl);

  		if (error)

  			goto out;

  	}

  	error = posix_acl_create(&acl, GFP_KERNEL, &mode);

  	if (error < 0)

  		return error;

  
  	/*

  	 * If posix_acl_create returns a positive value we need to

  	 * inherit a permission that can't be represented using the Unix
  	 * mode bits and we actually need to set an ACL.
  	 */
  	if (error > 0)
  		inherit = 1;
  
  	error = xfs_set_mode(inode, mode);
  	if (error)

  		goto out;

  
  	if (inherit)

  		error = xfs_set_acl(inode, ACL_TYPE_ACCESS, acl);

  out:
  	posix_acl_release(acl);

  	return error;
  }
  
  int
  xfs_acl_chmod(struct inode *inode)
  {

  	struct posix_acl *acl;

  	int error;
  
  	if (S_ISLNK(inode->i_mode))
  		return -EOPNOTSUPP;
  
  	acl = xfs_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 = xfs_set_acl(inode, ACL_TYPE_ACCESS, acl);
  	posix_acl_release(acl);

  	return error;
  }

  static int

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

  {
  	struct posix_acl *acl;

  	int error;

  	acl = xfs_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, value, size);
  	posix_acl_release(acl);
  
  	return error;
  }
  
  static int

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

  {

  	struct inode *inode = dentry->d_inode;

  	struct posix_acl *acl = NULL;

  	int error = 0;

  	if (flags & XATTR_CREATE)
  		return -EINVAL;
  	if (type == ACL_TYPE_DEFAULT && !S_ISDIR(inode->i_mode))
  		return value ? -EACCES : 0;
  	if ((current_fsuid() != inode->i_uid) && !capable(CAP_FOWNER))
  		return -EPERM;
  
  	if (!value)
  		goto set_acl;
  
  	acl = posix_acl_from_xattr(value, size);
  	if (!acl) {
  		/*
  		 * acl_set_file(3) may request that we set default ACLs with
  		 * zero length -- defend (gracefully) against that here.
  		 */
  		goto out;
  	}
  	if (IS_ERR(acl)) {
  		error = PTR_ERR(acl);
  		goto out;
  	}
  
  	error = posix_acl_valid(acl);
  	if (error)
  		goto out_release;
  
  	error = -EINVAL;
  	if (acl->a_count > XFS_ACL_MAX_ENTRIES)
  		goto out_release;
  
  	if (type == ACL_TYPE_ACCESS) {

  		umode_t mode = inode->i_mode;

  		error = posix_acl_equiv_mode(acl, &mode);
  
  		if (error <= 0) {
  			posix_acl_release(acl);
  			acl = NULL;
  
  			if (error < 0)
  				return error;
  		}
  
  		error = xfs_set_mode(inode, mode);
  		if (error)
  			goto out_release;
  	}
  
   set_acl:
  	error = xfs_set_acl(inode, type, acl);
   out_release:
  	posix_acl_release(acl);
   out:
  	return error;
  }

  const struct xattr_handler xfs_xattr_acl_access_handler = {

  	.prefix	= POSIX_ACL_XATTR_ACCESS,
  	.flags	= ACL_TYPE_ACCESS,
  	.get	= xfs_xattr_acl_get,
  	.set	= xfs_xattr_acl_set,
  };

  const struct xattr_handler xfs_xattr_acl_default_handler = {

  	.prefix	= POSIX_ACL_XATTR_DEFAULT,
  	.flags	= ACL_TYPE_DEFAULT,
  	.get	= xfs_xattr_acl_get,
  	.set	= xfs_xattr_acl_set,

  };