path: root/fs/overlayfs/params.c

// SPDX-License-Identifier: GPL-2.0-only

#include <linux/fs.h>
#include <linux/module.h>
#include <linux/namei.h>
#include <linux/fs_context.h>
#include <linux/fs_parser.h>
#include <linux/posix_acl_xattr.h>
#include <linux/seq_file.h>
#include <linux/xattr.h>
#include "overlayfs.h"
#include "params.h"

static bool ovl_redirect_dir_def = IS_ENABLED(CONFIG_OVERLAY_FS_REDIRECT_DIR);
module_param_named(redirect_dir, ovl_redirect_dir_def, bool, 0644);
MODULE_PARM_DESC(redirect_dir,
		 "Default to on or off for the redirect_dir feature");

static bool ovl_redirect_always_follow =
	IS_ENABLED(CONFIG_OVERLAY_FS_REDIRECT_ALWAYS_FOLLOW);
module_param_named(redirect_always_follow, ovl_redirect_always_follow,
		   bool, 0644);
MODULE_PARM_DESC(redirect_always_follow,
		 "Follow redirects even if redirect_dir feature is turned off");

static bool ovl_xino_auto_def = IS_ENABLED(CONFIG_OVERLAY_FS_XINO_AUTO);
module_param_named(xino_auto, ovl_xino_auto_def, bool, 0644);
MODULE_PARM_DESC(xino_auto,
		 "Auto enable xino feature");

static bool ovl_index_def = IS_ENABLED(CONFIG_OVERLAY_FS_INDEX);
module_param_named(index, ovl_index_def, bool, 0644);
MODULE_PARM_DESC(index,
		 "Default to on or off for the inodes index feature");

static bool ovl_nfs_export_def = IS_ENABLED(CONFIG_OVERLAY_FS_NFS_EXPORT);
module_param_named(nfs_export, ovl_nfs_export_def, bool, 0644);
MODULE_PARM_DESC(nfs_export,
		 "Default to on or off for the NFS export feature");

static bool ovl_metacopy_def = IS_ENABLED(CONFIG_OVERLAY_FS_METACOPY);
module_param_named(metacopy, ovl_metacopy_def, bool, 0644);
MODULE_PARM_DESC(metacopy,
		 "Default to on or off for the metadata only copy up feature");

enum ovl_opt {
	Opt_lowerdir,
	Opt_lowerdir_add,
	Opt_datadir_add,
	Opt_upperdir,
	Opt_workdir,
	Opt_default_permissions,
	Opt_redirect_dir,
	Opt_index,
	Opt_uuid,
	Opt_nfs_export,
	Opt_userxattr,
	Opt_xino,
	Opt_metacopy,
	Opt_verity,
	Opt_volatile,
};

static const struct constant_table ovl_parameter_bool[] = {
	{ "on",		true  },
	{ "off",	false },
	{}
};

static const struct constant_table ovl_parameter_uuid[] = {
	{ "off",	OVL_UUID_OFF  },
	{ "null",	OVL_UUID_NULL },
	{ "auto",	OVL_UUID_AUTO },
	{ "on",		OVL_UUID_ON   },
	{}
};

static const char *ovl_uuid_mode(struct ovl_config *config)
{
	return ovl_parameter_uuid[config->uuid].name;
}

static int ovl_uuid_def(void)
{
	return OVL_UUID_AUTO;
}

static const struct constant_table ovl_parameter_xino[] = {
	{ "off",	OVL_XINO_OFF  },
	{ "auto",	OVL_XINO_AUTO },
	{ "on",		OVL_XINO_ON   },
	{}
};

const char *ovl_xino_mode(struct ovl_config *config)
{
	return ovl_parameter_xino[config->xino].name;
}

static int ovl_xino_def(void)
{
	return ovl_xino_auto_def ? OVL_XINO_AUTO : OVL_XINO_OFF;
}

const struct constant_table ovl_parameter_redirect_dir[] = {
	{ "off",	OVL_REDIRECT_OFF      },
	{ "follow",	OVL_REDIRECT_FOLLOW   },
	{ "nofollow",	OVL_REDIRECT_NOFOLLOW },
	{ "on",		OVL_REDIRECT_ON       },
	{}
};

static const char *ovl_redirect_mode(struct ovl_config *config)
{
	return ovl_parameter_redirect_dir[config->redirect_mode].name;
}

static int ovl_redirect_mode_def(void)
{
	return ovl_redirect_dir_def	  ? OVL_REDIRECT_ON :
	       ovl_redirect_always_follow ? OVL_REDIRECT_FOLLOW :
					    OVL_REDIRECT_NOFOLLOW;
}

static const struct constant_table ovl_parameter_verity[] = {
	{ "off",	OVL_VERITY_OFF     },
	{ "on",		OVL_VERITY_ON      },
	{ "require",	OVL_VERITY_REQUIRE },
	{}
};

static const char *ovl_verity_mode(struct ovl_config *config)
{
	return ovl_parameter_verity[config->verity_mode].name;
}

static int ovl_verity_mode_def(void)
{
	return OVL_VERITY_OFF;
}

const struct fs_parameter_spec ovl_parameter_spec[] = {
	fsparam_string_empty("lowerdir",    Opt_lowerdir),
	fsparam_string("lowerdir+",         Opt_lowerdir_add),
	fsparam_string("datadir+",          Opt_datadir_add),
	fsparam_string("upperdir",          Opt_upperdir),
	fsparam_string("workdir",           Opt_workdir),
	fsparam_flag("default_permissions", Opt_default_permissions),
	fsparam_enum("redirect_dir",        Opt_redirect_dir, ovl_parameter_redirect_dir),
	fsparam_enum("index",               Opt_index, ovl_parameter_bool),
	fsparam_enum("uuid",                Opt_uuid, ovl_parameter_uuid),
	fsparam_enum("nfs_export",          Opt_nfs_export, ovl_parameter_bool),
	fsparam_flag("userxattr",           Opt_userxattr),
	fsparam_enum("xino",                Opt_xino, ovl_parameter_xino),
	fsparam_enum("metacopy",            Opt_metacopy, ovl_parameter_bool),
	fsparam_enum("verity",              Opt_verity, ovl_parameter_verity),
	fsparam_flag("volatile",            Opt_volatile),
	{}
};

static char *ovl_next_opt(char **s)
{
	char *sbegin = *s;
	char *p;

	if (sbegin == NULL)
		return NULL;

	for (p = sbegin; *p; p++) {
		if (*p == '\\') {
			p++;
			if (!*p)
				break;
		} else if (*p == ',') {
			*p = '\0';
			*s = p + 1;
			return sbegin;
		}
	}
	*s = NULL;
	return sbegin;
}

static int ovl_parse_monolithic(struct fs_context *fc, void *data)
{
	return vfs_parse_monolithic_sep(fc, data, ovl_next_opt);
}

static ssize_t ovl_parse_param_split_lowerdirs(char *str)
{
	ssize_t nr_layers = 1, nr_colons = 0;
	char *s, *d;

	for (s =