hfsplus: implement POSIX ACLs support

/*

 * linux/fs/hfsplus/posix_acl.c

 *

 * Vyacheslav Dubeyko <slava@dubeyko.com>

 *

 * Handler for Posix Access Control Lists (ACLs) support.

 */

#include "hfsplus_fs.h"

#include "xattr.h"

#include "acl.h"

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

{

	struct posix_acl *acl;

	char *xattr_name;

	char *value = NULL;

	ssize_t size;

	acl = get_cached_acl(inode, type);

	if (acl != ACL_NOT_CACHED)

		return acl;

	switch (type) {

	case ACL_TYPE_ACCESS:

		xattr_name = POSIX_ACL_XATTR_ACCESS;

		break;

	case ACL_TYPE_DEFAULT:

		xattr_name = POSIX_ACL_XATTR_DEFAULT;

		break;

	default:

		return ERR_PTR(-EINVAL);

	}

	size = __hfsplus_getxattr(inode, xattr_name, NULL, 0);

	if (size > 0) {

		value = (char *)hfsplus_alloc_attr_entry();

		if (unlikely(!value))

			return ERR_PTR(-ENOMEM);

		size = __hfsplus_getxattr(inode, xattr_name, value, size);

	}

	if (size > 0)

		acl = posix_acl_from_xattr(&init_user_ns, value, size);

	else if (size == -ENODATA)

		acl = NULL;

	else

		acl = ERR_PTR(size);

	hfsplus_destroy_attr_entry((hfsplus_attr_entry *)value);

	if (!IS_ERR(acl))

		set_cached_acl(inode, type, acl);

	return acl;

}

static int hfsplus_set_posix_acl(struct inode *inode,

					int type,

					struct posix_acl *acl)

{

	int err;

	char *xattr_name;

	size_t size = 0;

	char *value = NULL;

	if (S_ISLNK(inode->i_mode))

		return -EOPNOTSUPP;

	switch (type) {

	case ACL_TYPE_ACCESS:

		xattr_name = POSIX_ACL_XATTR_ACCESS;

		if (acl) {

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

			if (err < 0)

				return err;

		}

		err = 0;

		break;

	case ACL_TYPE_DEFAULT:

		xattr_name = POSIX_ACL_XATTR_DEFAULT;

		if (!S_ISDIR(inode->i_mode))

			return acl ? -EACCES : 0;

		break;

	default:

		return -EINVAL;

	}

	if (acl) {

		size = posix_acl_xattr_size(acl->a_count);

		if (unlikely(size > HFSPLUS_MAX_INLINE_DATA_SIZE))

			return -ENOMEM;

		value = (char *)hfsplus_alloc_attr_entry();

		if (unlikely(!value))

			return -ENOMEM;

		err = posix_acl_to_xattr(&init_user_ns, acl, value, size);

		if (unlikely(err < 0))

			goto end_set_acl;

	}

	err = __hfsplus_setxattr(inode, xattr_name, value, size, 0);

end_set_acl:

	hfsplus_destroy_attr_entry((hfsplus_attr_entry *)value);

	if (!err)

		set_cached_acl(inode, type, acl);

	return err;

}

int hfsplus_init_posix_acl(struct inode *inode, struct inode *dir)

{

	int err = 0;

	struct posix_acl *acl = NULL;

	hfs_dbg(ACL_MOD,

		"[%s]: ino %lu, dir->ino %lu\n",

		__func__, inode->i_ino, dir->i_ino);

	if (S_ISLNK(inode->i_mode))

		return 0;

	acl = hfsplus_get_posix_acl(dir, ACL_TYPE_DEFAULT);

	if (IS_ERR(acl))

		return PTR_ERR(acl);

	if (acl) {

		if (S_ISDIR(inode->i_mode)) {

			err = hfsplus_set_posix_acl(inode,

							ACL_TYPE_DEFAULT,

							acl);

			if (unlikely(err))

				goto init_acl_cleanup;

		}

		err = posix_acl_create(&acl, GFP_NOFS, &inode->i_mode);

		if (unlikely(err < 0))

			return err;

		if (err > 0)

			err = hfsplus_set_posix_acl(inode,

							ACL_TYPE_ACCESS,

							acl);

	} else

		inode->i_mode &= ~current_umask();

init_acl_cleanup:

	posix_acl_release(acl);

	return err;

}

int hfsplus_posix_acl_chmod(struct inode *inode)

{

	int err;

	struct posix_acl *acl;

	hfs_dbg(ACL_MOD, "[%s]: ino %lu\n", __func__, inode->i_ino);

	if (S_ISLNK(inode->i_mode))

		return -EOPNOTSUPP;

	acl = hfsplus_get_posix_acl(inode, ACL_TYPE_ACCESS);

	if (IS_ERR(acl) || !acl)

		return PTR_ERR(acl);

	err = posix_acl_chmod(&acl, GFP_KERNEL, inode->i_mode);

	if (unlikely(err))

		return err;

	err = hfsplus_set_posix_acl(inode, ACL_TYPE_ACCESS, acl);

	posix_acl_release(acl);

	return err;

}

static int hfsplus_xattr_get_posix_acl(struct dentry *dentry,

					const char *name,

					void *buffer,

					size_t size,

					int type)

{

	int err = 0;

	struct posix_acl *acl;

	hfs_dbg(ACL_MOD,

		"[%s]: ino %lu, buffer %p, size %zu, type %#x\n",

		__func__, dentry->d_inode->i_ino, buffer, size, type);

	if (strcmp(name, "") != 0)

		return -EINVAL;

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

	if (IS_ERR(acl))

		return PTR_ERR(acl);

	if (acl == NULL)

		return -ENODATA;

	err = posix_acl_to_xattr(&init_user_ns, acl, buffer, size);

	posix_acl_release(acl);

	return err;

}

static int hfsplus_xattr_set_posix_acl(struct dentry *dentry,

					const char *name,

					const void *value,

					size_t size,

					int flags,

					int type)

{

	int err = 0;

	struct inode *inode = dentry->d_inode;

	struct posix_acl *acl = NULL;

	hfs_dbg(ACL_MOD,

		"[%s]: ino %lu, value %p, size %zu, flags %#x, type %#x\n",

		__func__, inode->i_ino, value, size, flags, type);

	if (strcmp(name, "") != 0)

		return -EINVAL;

	if (!inode_owner_or_capable(inode))

		return -EPERM;

	if (value) {

		acl = posix_acl_from_xattr(&init_user_ns, value, size);

		if (IS_ERR(acl))

			return PTR_ERR(acl);

		else if (acl) {

			err = posix_acl_valid(acl);

			if (err)

				goto end_xattr_set_acl;

		}

	}

	err = hfsplus_set_posix_acl(inode, type, acl);

end_xattr_set_acl:

	posix_acl_release(acl);

	return err;

}

static size_t hfsplus_xattr_list_posix_acl(struct dentry *dentry,

						char *list,

						size_t list_size,

						const char *name,

						size_t name_len,

						int type)

{

	/*

	 * This method is not used.

	 * It is used hfsplus_listxattr() instead of generic_listxattr().

	 */

	return -EOPNOTSUPP;

}

const struct xattr_handler hfsplus_xattr_acl_access_handler = {

	.prefix	= POSIX_ACL_XATTR_ACCESS,

	.flags	= ACL_TYPE_ACCESS,

	.list	= hfsplus_xattr_list_posix_acl,

	.get	= hfsplus_xattr_get_posix_acl,

	.set	= hfsplus_xattr_set_posix_acl,

};

const struct xattr_handler hfsplus_xattr_acl_default_handler = {

	.prefix	= POSIX_ACL_XATTR_DEFAULT,

	.flags	= ACL_TYPE_DEFAULT,

	.list	= hfsplus_xattr_list_posix_acl,

	.get	= hfsplus_xattr_get_posix_acl,

	.set	= hfsplus_xattr_set_posix_acl,

};