/*
   * JFFS2 -- Journalling Flash File System, Version 2.

   *

   * Copyright © 2006  NEC Corporation

   *

   * Created by KaiGai Kohei <kaigai@ak.jp.nec.com>
   *
   * For licensing information, see the file 'LICENCE' in this directory.
   *
   */

  #include <linux/kernel.h>
  #include <linux/slab.h>
  #include <linux/fs.h>

  #include <linux/sched.h>

  #include <linux/time.h>
  #include <linux/crc32.h>
  #include <linux/jffs2.h>
  #include <linux/xattr.h>
  #include <linux/posix_acl_xattr.h>
  #include <linux/mtd/mtd.h>
  #include "nodelist.h"
  
  static size_t jffs2_acl_size(int count)
  {
  	if (count <= 4) {

  		return sizeof(struct jffs2_acl_header)
  		       + count * sizeof(struct jffs2_acl_entry_short);

  	} else {

  		return sizeof(struct jffs2_acl_header)
  		       + 4 * sizeof(struct jffs2_acl_entry_short)
  		       + (count - 4) * sizeof(struct jffs2_acl_entry);

  	}
  }
  
  static int jffs2_acl_count(size_t size)
  {
  	size_t s;

  	size -= sizeof(struct jffs2_acl_header);

  	if (size < 4 * sizeof(struct jffs2_acl_entry_short)) {

  		if (size % sizeof(struct jffs2_acl_entry_short))

  			return -1;

  		return size / sizeof(struct jffs2_acl_entry_short);

  	} else {

  		s = size - 4 * sizeof(struct jffs2_acl_entry_short);

  		if (s % sizeof(struct jffs2_acl_entry))

  			return -1;

  		return s / sizeof(struct jffs2_acl_entry) + 4;

  	}
  }

  static struct posix_acl *jffs2_acl_from_medium(void *value, size_t size)

  {

  	void *end = value + size;
  	struct jffs2_acl_header *header = value;
  	struct jffs2_acl_entry *entry;

  	struct posix_acl *acl;
  	uint32_t ver;
  	int i, count;
  
  	if (!value)
  		return NULL;

  	if (size < sizeof(struct jffs2_acl_header))

  		return ERR_PTR(-EINVAL);

  	ver = je32_to_cpu(header->a_version);

  	if (ver != JFFS2_ACL_VERSION) {
  		JFFS2_WARNING("Invalid ACL version. (=%u)
  ", ver);
  		return ERR_PTR(-EINVAL);
  	}

  	value += sizeof(struct jffs2_acl_header);

  	count = jffs2_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 (i=0; i < count; i++) {

  		entry = value;
  		if (value + sizeof(struct jffs2_acl_entry_short) > end)

  			goto fail;
  		acl->a_entries[i].e_tag = je16_to_cpu(entry->e_tag);
  		acl->a_entries[i].e_perm = je16_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:

  				value += sizeof(struct jffs2_acl_entry_short);

  				acl->a_entries[i].e_id = ACL_UNDEFINED_ID;
  				break;
  
  			case ACL_USER:
  			case ACL_GROUP:

  				value += sizeof(struct jffs2_acl_entry);
  				if (value > end)

  					goto fail;
  				acl->a_entries[i].e_id = je32_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);
  }
  
  static void *jffs2_acl_to_medium(const struct posix_acl *acl, size_t *size)
  {

  	struct jffs2_acl_header *header;
  	struct jffs2_acl_entry *entry;
  	void *e;

  	size_t i;
  
  	*size = jffs2_acl_size(acl->a_count);

  	header = kmalloc(sizeof(*header) + acl->a_count * sizeof(*entry), GFP_KERNEL);
  	if (!header)

  		return ERR_PTR(-ENOMEM);

  	header->a_version = cpu_to_je32(JFFS2_ACL_VERSION);
  	e = header + 1;

  	for (i=0; i < acl->a_count; i++) {

  		entry = e;

  		entry->e_tag = cpu_to_je16(acl->a_entries[i].e_tag);
  		entry->e_perm = cpu_to_je16(acl->a_entries[i].e_perm);
  		switch(acl->a_entries[i].e_tag) {
  			case ACL_USER:
  			case ACL_GROUP:
  				entry->e_id = cpu_to_je32(acl->a_entries[i].e_id);

  				e += sizeof(struct jffs2_acl_entry);

  				break;
  
  			case ACL_USER_OBJ:
  			case ACL_GROUP_OBJ:
  			case ACL_MASK:
  			case ACL_OTHER:

  				e += sizeof(struct jffs2_acl_entry_short);

  				break;
  
  			default:
  				goto fail;
  		}
  	}

  	return header;

   fail:

  	kfree(header);

  	return ERR_PTR(-EINVAL);
  }

  struct posix_acl *jffs2_get_acl(struct inode *inode, int type)

  {

  	struct posix_acl *acl;
  	char *value = NULL;
  	int rc, xprefix;

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

  	switch (type) {
  	case ACL_TYPE_ACCESS:

  		xprefix = JFFS2_XPREFIX_ACL_ACCESS;
  		break;
  	case ACL_TYPE_DEFAULT:

  		xprefix = JFFS2_XPREFIX_ACL_DEFAULT;
  		break;
  	default:

  		BUG();

  	}
  	rc = do_jffs2_getxattr(inode, xprefix, "", NULL, 0);
  	if (rc > 0) {
  		value = kmalloc(rc, GFP_KERNEL);
  		if (!value)
  			return ERR_PTR(-ENOMEM);
  		rc = do_jffs2_getxattr(inode, xprefix, "", value, rc);
  	}
  	if (rc > 0) {
  		acl = jffs2_acl_from_medium(value, rc);
  	} else if (rc == -ENODATA || rc == -ENOSYS) {
  		acl = NULL;
  	} else {
  		acl = ERR_PTR(rc);
  	}
  	if (value)
  		kfree(value);

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

  	return acl;
  }

  static int __jffs2_set_acl(struct inode *inode, int xprefix, struct posix_acl *acl)
  {
  	char *value = NULL;
  	size_t size = 0;
  	int rc;
  
  	if (acl) {
  		value = jffs2_acl_to_medium(acl, &size);
  		if (IS_ERR(value))
  			return PTR_ERR(value);
  	}
  	rc = do_jffs2_setxattr(inode, xprefix, "", value, size, 0);
  	if (!value && rc == -ENODATA)
  		rc = 0;
  	kfree(value);
  
  	return rc;
  }

  static int jffs2_set_acl(struct inode *inode, int type, struct posix_acl *acl)
  {

  	int rc, xprefix;
  
  	if (S_ISLNK(inode->i_mode))
  		return -EOPNOTSUPP;
  
  	switch (type) {
  	case ACL_TYPE_ACCESS:
  		xprefix = JFFS2_XPREFIX_ACL_ACCESS;
  		if (acl) {

  			umode_t mode = inode->i_mode;

  			rc = posix_acl_equiv_mode(acl, &mode);
  			if (rc < 0)
  				return rc;
  			if (inode->i_mode != mode) {

  				struct iattr attr;

  				attr.ia_valid = ATTR_MODE | ATTR_CTIME;

  				attr.ia_mode = mode;

  				attr.ia_ctime = CURRENT_TIME_SEC;

  				rc = jffs2_do_setattr(inode, &attr);
  				if (rc < 0)
  					return rc;

  			}
  			if (rc == 0)
  				acl = NULL;
  		}
  		break;
  	case ACL_TYPE_DEFAULT:
  		xprefix = JFFS2_XPREFIX_ACL_DEFAULT;
  		if (!S_ISDIR(inode->i_mode))
  			return acl ? -EACCES : 0;
  		break;
  	default:
  		return -EINVAL;
  	}

  	rc = __jffs2_set_acl(inode, xprefix, acl);

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

  	return rc;
  }

  int jffs2_init_acl_pre(struct inode *dir_i, struct inode *inode, umode_t *i_mode)

  {

  	struct posix_acl *acl;

  	int rc;

  	cache_no_acl(inode);

  
  	if (S_ISLNK(*i_mode))
  		return 0;	/* Symlink always has no-ACL */
  
  	acl = jffs2_get_acl(dir_i, ACL_TYPE_DEFAULT);
  	if (IS_ERR(acl))
  		return PTR_ERR(acl);
  
  	if (!acl) {

  		*i_mode &= ~current_umask();

  	} else {
  		if (S_ISDIR(*i_mode))

  			set_cached_acl(inode, ACL_TYPE_DEFAULT, acl);

  		rc = posix_acl_create(&acl, GFP_KERNEL, i_mode);
  		if (rc < 0)

  			return rc;
  		if (rc > 0)

  			set_cached_acl(inode, ACL_TYPE_ACCESS, acl);

  		posix_acl_release(acl);

  	}

  	return 0;
  }
  
  int jffs2_init_acl_post(struct inode *inode)
  {

  	int rc;

  	if (inode->i_default_acl) {
  		rc = __jffs2_set_acl(inode, JFFS2_XPREFIX_ACL_DEFAULT, inode->i_default_acl);

  		if (rc)
  			return rc;
  	}

  	if (inode->i_acl) {
  		rc = __jffs2_set_acl(inode, JFFS2_XPREFIX_ACL_ACCESS, inode->i_acl);

  		if (rc)
  			return rc;
  	}

  	return 0;

  }

  int jffs2_acl_chmod(struct inode *inode)
  {

  	struct posix_acl *acl;

  	int rc;
  
  	if (S_ISLNK(inode->i_mode))
  		return -EOPNOTSUPP;
  	acl = jffs2_get_acl(inode, ACL_TYPE_ACCESS);
  	if (IS_ERR(acl) || !acl)
  		return PTR_ERR(acl);

  	rc = posix_acl_chmod(&acl, GFP_KERNEL, inode->i_mode);
  	if (rc)
  		return rc;
  	rc = jffs2_set_acl(inode, ACL_TYPE_ACCESS, acl);

  	posix_acl_release(acl);

  	return rc;
  }

  static size_t jffs2_acl_access_listxattr(struct dentry *dentry, char *list,
  		size_t list_size, const char *name, size_t name_len, int type)

  {
  	const int retlen = sizeof(POSIX_ACL_XATTR_ACCESS);
  
  	if (list && retlen <= list_size)
  		strcpy(list, POSIX_ACL_XATTR_ACCESS);
  	return retlen;
  }

  static size_t jffs2_acl_default_listxattr(struct dentry *dentry, char *list,
  		size_t list_size, const char *name, size_t name_len, int type)

  {
  	const int retlen = sizeof(POSIX_ACL_XATTR_DEFAULT);
  
  	if (list && retlen <= list_size)
  		strcpy(list, POSIX_ACL_XATTR_DEFAULT);
  	return retlen;
  }

  static int jffs2_acl_getxattr(struct dentry *dentry, const char *name,
  		void *buffer, size_t size, int type)

  {
  	struct posix_acl *acl;
  	int rc;

  	if (name[0] != '\0')
  		return -EINVAL;
  
  	acl = jffs2_get_acl(dentry->d_inode, type);

  	if (IS_ERR(acl))
  		return PTR_ERR(acl);
  	if (!acl)
  		return -ENODATA;
  	rc = posix_acl_to_xattr(acl, buffer, size);
  	posix_acl_release(acl);
  
  	return rc;
  }

  static int jffs2_acl_setxattr(struct dentry *dentry, const char *name,
  		const void *value, size_t size, int flags, int type)

  {
  	struct posix_acl *acl;
  	int rc;

  	if (name[0] != '\0')
  		return -EINVAL;

  	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);
  		if (acl) {
  			rc = posix_acl_valid(acl);
  			if (rc)
  				goto out;
  		}
  	} else {
  		acl = NULL;
  	}

  	rc = jffs2_set_acl(dentry->d_inode, type, acl);

   out:
  	posix_acl_release(acl);
  	return rc;
  }

  const struct xattr_handler jffs2_acl_access_xattr_handler = {

  	.prefix	= POSIX_ACL_XATTR_ACCESS,

  	.flags	= ACL_TYPE_DEFAULT,

  	.list	= jffs2_acl_access_listxattr,

  	.get	= jffs2_acl_getxattr,
  	.set	= jffs2_acl_setxattr,

  };

  const struct xattr_handler jffs2_acl_default_xattr_handler = {

  	.prefix	= POSIX_ACL_XATTR_DEFAULT,

  	.flags	= ACL_TYPE_DEFAULT,

  	.list	= jffs2_acl_default_listxattr,

  	.get	= jffs2_acl_getxattr,
  	.set	= jffs2_acl_setxattr,

  };