fs/fs_parser.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-or-later
 /* Filesystem parameter parser.
  *
  * Copyright (C) 2018 Red Hat, Inc. All Rights Reserved.
  * Written by David Howells (dhowells@redhat.com)
  */

 #include <linux/export.h>
 #include <linux/fs_context.h>
 #include <linux/fs_parser.h>
 #include <linux/slab.h>
 #include <linux/security.h>
 #include <linux/namei.h>
 #include "internal.h"

 static const struct constant_table bool_names[] = {
 	{ "0",		false },
 	{ "1",		true },
 	{ "false",	false },
 	{ "no",		false },
 	{ "true",	true },
 	{ "yes",	true },
 	{ },
 };

 static const struct constant_table *
 __lookup_constant(const struct constant_table *tbl, const char *name)
 {
 	for ( ; tbl->name; tbl++)
 		if (strcmp(name, tbl->name) == 0)
 			return tbl;
 	return NULL;
 }

 /**
  * lookup_constant - Look up a constant by name in an ordered table
  * @tbl: The table of constants to search.
  * @name: The name to look up.
  * @not_found: The value to return if the name is not found.
  */
 int lookup_constant(const struct constant_table *tbl, const char *name, int not_found)
 {
 	const struct constant_table *p = __lookup_constant(tbl, name);

 	return p ? p->value : not_found;
 }
 EXPORT_SYMBOL(lookup_constant);

 static inline bool is_flag(const struct fs_parameter_spec *p)
 {
 	return p->type == NULL;
 }

 static const struct fs_parameter_spec *fs_lookup_key(
 	const struct fs_parameter_spec *desc,
 	struct fs_parameter *param, bool *negated)
 {
 	const struct fs_parameter_spec *p, *other = NULL;
 	const char *name = param->key;
 	bool want_flag = param->type == fs_value_is_flag;

 	*negated = false;
 	for (p = desc; p->name; p++) {
 		if (strcmp(p->name, name) != 0)
 			continue;
 		if (likely(is_flag(p) == want_flag))
 			return p;
 		other = p;
 	}
 	if (want_flag) {
 		if (name[0] == 'n' && name[1] == 'o' && name[2]) {
 			for (p = desc; p->name; p++) {
 				if (strcmp(p->name, name + 2) != 0)
 					continue;
 				if (!(p->flags & fs_param_neg_with_no))
 					continue;
 				*negated = true;
 				return p;
 			}
 		}
 	}
 	return other;
 }

 /*
  * __fs_parse - Parse a filesystem configuration parameter
  * @log: The filesystem context to log errors through.
  * @desc: The parameter description to use.
  * @param: The parameter.
  * @result: Where to place the result of the parse
  *
  * Parse a filesystem configuration parameter and attempt a conversion for a
  * simple parameter for which this is requested.  If successful, the determined
  * parameter ID is placed into @result->key, the desired type is indicated in
  * @result->t and any converted value is placed into an appropriate member of
  * the union in @result.
  *
  * The function returns the parameter number if the parameter was matched,
  * -ENOPARAM if it wasn't matched and @desc->ignore_unknown indicated that
  * unknown parameters are okay and -EINVAL if there was a conversion issue or
  * the parameter wasn't recognised and unknowns aren't okay.
  */
 int __fs_parse(struct p_log *log,
 	     const struct fs_parameter_spec *desc,
 	     struct fs_parameter *param,
 	     struct fs_parse_result *result)
 {
 	const struct fs_parameter_spec *p;

 	result->uint_64 = 0;

 	p = fs_lookup_key(desc, param, &result->negated);
 	if (!p)
 		return -ENOPARAM;

 	if (p->flags & fs_param_deprecated)
 		warn_plog(log, "Deprecated parameter '%s'", param->key);

 	/* Try to turn the type we were given into the type desired by the
 	 * parameter and give an error if we can't.
 	 */
 	if (is_flag(p)) {
 		if (param->type != fs_value_is_flag)
 			return inval_plog(log, "Unexpected value for '%s'",
 				      param->key);
 		result->boolean = !result->negated;
 	} else  {
 		int ret = p->type(log, p, param, result);
 		if (ret)
 			return ret;
 	}
 	return p->opt;
 }
 EXPORT_SYMBOL(__fs_parse);

 /**
  * fs_lookup_param - Look up a path referred to by a parameter
  * @fc: The filesystem context to log errors through.
  * @param: The parameter.
  * @want_bdev: T if want a blockdev
  * @flags: Pathwalk flags passed to filename_lookup()
  * @_path: The result of the lookup
  */
 int fs_lookup_param(struct fs_context *fc,
 		    struct fs_parameter *param,
 		    bool want_bdev,
 		    unsigned int flags,
 		    struct path *_path)
 {
 	struct filename *f;
 	bool put_f;
 	int ret;

 	switch (param->type) {
 	case fs_value_is_string:
 		f = getname_kernel(param->string);
 		if (IS_ERR(f))
 			return PTR_ERR(f);
 		param->dirfd = AT_FDCWD;
 		put_f = true;
 		break;
 	case fs_value_is_filename:
 		f = param->name;
 		put_f = false;
 		break;
 	default:
 		return invalf(fc, "%s: not usable as path", param->key);
 	}

 	ret = filename_lookup(param->dirfd, f, flags, _path, NULL);
 	if (ret < 0) {
 		errorf(fc, "%s: Lookup failure for '%s'", param->key, f->name);
 		goto out;
 	}

 	if (want_bdev &&
 	    !S_ISBLK(d_backing_inode(_path->dentry)->i_mode)) {
 		path_put(_path);
 		_path->dentry = NULL;
 		_path->mnt = NULL;
 		errorf(fc, "%s: Non-blockdev passed as '%s'",
 		       param->key, f->name);
 		ret = -ENOTBLK;
 	}

 out:
 	if (put_f)
 		putname(f);
 	return ret;
 }
 EXPORT_SYMBOL(fs_lookup_param);

 static int fs_param_bad_value(struct p_log *log, struct fs_parameter *param)
 {
 	return inval_plog(log, "Bad value for '%s'", param->key);
 }

 int fs_param_is_bool(struct p_log *log, const struct fs_parameter_spec *p,
 		     struct fs_parameter *param, struct fs_parse_result *result)
 {
 	int b;
 	if (param->type != fs_value_is_string)
 		return fs_param_bad_value(log, param);
 	if (!*param->string && (p->flags & fs_param_can_be_empty))
 		return 0;
 	b = lookup_constant(bool_names, param->string, -1);
 	if (b == -1)
 		return fs_param_bad_value(log, param);
 	result->boolean = b;
 	return 0;
 }
 EXPORT_SYMBOL(fs_param_is_bool);

 int fs_param_is_u32(struct p_log *log, const struct fs_parameter_spec *p,
 		    struct fs_parameter *param, struct fs_parse_result *result)
 {
 	int base = (unsigned long)p->data;
 	if (param->type != fs_value_is_string)
 		return fs_param_bad_value(log, param);
 	if (!*param->string && (p->flags & fs_param_can_be_empty))
 		return 0;
 	if (kstrtouint(param->string, base, &result->uint_32) < 0)
 		return fs_param_bad_value(log, param);
 	return 0;
 }
 EXPORT_SYMBOL(fs_param_is_u32);

 int fs_param_is_s32(struct p_log *log, const struct fs_parameter_spec *p,
 		    struct fs_parameter *param, struct fs_parse_result *result)
 {
 	if (param->type != fs_value_is_string)
 		return fs_param_bad_value(log, param);
 	if (!*param->string && (p->flags & fs_param_can_be_empty))
 		return 0;
 	if (kstrtoint(param->string, 0, &result->int_32) < 0)
 		return fs_param_bad_value(log, param);
 	return 0;
 }
 EXPORT_SYMBOL(fs_param_is_s32);

 int fs_param_is_u64(struct p_log *log, const struct fs_parameter_spec *p,
 		    struct fs_parameter *param, struct fs_parse_result *result)
 {
 	if (param->type != fs_value_is_string)
 		return fs_param_bad_value(log, param);
 	if (!*param->string && (p->flags & fs_param_can_be_empty))
 		return 0;
 	if (kstrtoull(param->string, 0, &result->uint_64) < 0)
 		return fs_param_bad_value(log, param);
 	return 0;
 }
 EXPORT_SYMBOL(fs_param_is_u64);

 int fs_param_is_enum(struct p_log *log, const struct fs_parameter_spec *p,
 		     struct fs_parameter *param, struct fs_parse_result *result)
 {
 	const struct constant_table *c;
 	if (param->type != fs_value_is_string)
 		return fs_param_bad_value(log, param);
 	if (!*param->string && (p->flags & fs_param_can_be_empty))
 		return 0;
 	c = __lookup_constant(p->data, param->string);
 	if (!c)
 		return fs_param_bad_value(log, param);
 	result->uint_32 = c->value;
 	return 0;
 }
 EXPORT_SYMBOL(fs_param_is_enum);

 int fs_param_is_string(struct p_log *log, const struct fs_parameter_spec *p,
 		       struct fs_parameter *param, struct fs_parse_result *result)
 {
 	if (param->type != fs_value_is_string ||
 	    (!*param->string && !(p->flags & fs_param_can_be_empty)))
 		return fs_param_bad_value(log, param);
 	return 0;
 }
 EXPORT_SYMBOL(fs_param_is_string);

 int fs_param_is_blob(struct p_log *log, const struct fs_parameter_spec *p,
 		     struct fs_parameter *param, struct fs_parse_result *result)
 {
 	if (param->type != fs_value_is_blob)
 		return fs_param_bad_value(log, param);
 	return 0;
 }
 EXPORT_SYMBOL(fs_param_is_blob);

 int fs_param_is_fd(struct p_log *log, const struct fs_parameter_spec *p,
 		  struct fs_parameter *param, struct fs_parse_result *result)
 {
 	switch (param->type) {
 	case fs_value_is_string:
 		if ((!*param->string && !(p->flags & fs_param_can_be_empty)) ||
 		    kstrtouint(param->string, 0, &result->uint_32) < 0)
 			break;
 		if (result->uint_32 <= INT_MAX)
 			return 0;
 		break;
 	case fs_value_is_file:
 		result->uint_32 = param->dirfd;
 		if (result->uint_32 <= INT_MAX)
 			return 0;
 		break;
 	default:
 		break;
 	}
 	return fs_param_bad_value(log, param);
 }
 EXPORT_SYMBOL(fs_param_is_fd);

 int fs_param_is_uid(struct p_log *log, const struct fs_parameter_spec *p,
 		    struct fs_parameter *param, struct fs_parse_result *result)
 {
 	kuid_t uid;

 	if (fs_param_is_u32(log, p, param, result) != 0)
 		return fs_param_bad_value(log, param);

 	uid = make_kuid(current_user_ns(), result->uint_32);
 	if (!uid_valid(uid))
 		return inval_plog(log, "Invalid uid '%s'", param->string);

 	result->uid = uid;
 	return 0;
 }
 EXPORT_SYMBOL(fs_param_is_uid);

 int fs_param_is_gid(struct p_log *log, const struct fs_parameter_spec *p,
 		    struct fs_parameter *param, struct fs_parse_result *result)
 {
 	kgid_t gid;

 	if (fs_param_is_u32(log, p, param, result) != 0)
 		return fs_param_bad_value(log, param);

 	gid = make_kgid(current_user_ns(), result->uint_32);
 	if (!gid_valid(gid))
 		return inval_plog(log, "Invalid gid '%s'", param->string);

 	result->gid = gid;
 	return 0;
 }
 EXPORT_SYMBOL(fs_param_is_gid);

 int fs_param_is_blockdev(struct p_log *log, const struct fs_parameter_spec *p,
 		  struct fs_parameter *param, struct fs_parse_result *result)
 {
 	return 0;
 }
 EXPORT_SYMBOL(fs_param_is_blockdev);

 int fs_param_is_path(struct p_log *log, const struct fs_parameter_spec *p,
 		     struct fs_parameter *param, struct fs_parse_result *result)
 {
 	return 0;
 }
 EXPORT_SYMBOL(fs_param_is_path);

 #ifdef CONFIG_VALIDATE_FS_PARSER
 /**
  * validate_constant_table - Validate a constant table
  * @tbl: The constant table to validate.
  * @tbl_size: The size of the table.
  * @low: The lowest permissible value.
  * @high: The highest permissible value.
  * @special: One special permissible value outside of the range.
  */
 bool validate_constant_table(const struct constant_table *tbl, size_t tbl_size,
 			     int low, int high, int special)
 {
 	size_t i;
 	bool good = true;

 	if (tbl_size == 0) {
 		pr_warn("VALIDATE C-TBL: Empty\n");
 		return true;
 	}

 	for (i = 0; i < tbl_size; i++) {
 		if (!tbl[i].name) {
 			pr_err("VALIDATE C-TBL[%zu]: Null\n", i);
 			good = false;
 		} else if (i > 0 && tbl[i - 1].name) {
 			int c = strcmp(tbl[i-1].name, tbl[i].name);

 			if (c == 0) {
 				pr_err("VALIDATE C-TBL[%zu]: Duplicate %s\n",
 				       i, tbl[i].name);
 				good = false;
 			}
 			if (c > 0) {
 				pr_err("VALIDATE C-TBL[%zu]: Missorted %s>=%s\n",
 				       i, tbl[i-1].name, tbl[i].name);
 				good = false;
 			}
 		}

 		if (tbl[i].value != special &&
 		    (tbl[i].value < low || tbl[i].value > high)) {
 			pr_err("VALIDATE C-TBL[%zu]: %s->%d const out of range (%d-%d)\n",
 			       i, tbl[i].name, tbl[i].value, low, high);
 			good = false;
 		}
 	}

 	return good;
 }

 /**
  * fs_validate_description - Validate a parameter description
  * @name: The parameter name to search for.
  * @desc: The parameter description to validate.
  */
 bool fs_validate_description(const char *name,
 	const struct fs_parameter_spec *desc)
 {
 	const struct fs_parameter_spec *param, *p2;
 	bool good = true;

 	for (param = desc; param->name; param++) {
 		/* Check for duplicate parameter names */
 		for (p2 = desc; p2 < param; p2++) {
 			if (strcmp(param->name, p2->name) == 0) {
 				if (is_flag(param) != is_flag(p2))
 					continue;
 				pr_err("VALIDATE %s: PARAM[%s]: Duplicate\n",
 				       name, param->name);
 				good = false;
 			}
 		}
 	}
 	return good;
 }
 #endif /* CONFIG_VALIDATE_FS_PARSER */
	// SPDX-License-Identifier: GPL-2.0-or-later
	/* Filesystem parameter parser.
	*
	* Copyright (C) 2018 Red Hat, Inc. All Rights Reserved.
	* Written by David Howells (dhowells@redhat.com)
	*/

	#include <linux/export.h>
	#include <linux/fs_context.h>
	#include <linux/fs_parser.h>
	#include <linux/slab.h>
	#include <linux/security.h>
	#include <linux/namei.h>
	#include "internal.h"

	static const struct constant_table bool_names[] = {
	{ "0", false },
	{ "1", true },
	{ "false", false },
	{ "no", false },
	{ "true", true },
	{ "yes", true },
	{ },
	};

	static const struct constant_table *
	__lookup_constant(const struct constant_table tbl, const char name)
	{
	for ( ; tbl->name; tbl++)
	if (strcmp(name, tbl->name) == 0)
	return tbl;
	return NULL;
	}

	/**
	* lookup_constant - Look up a constant by name in an ordered table
	* @tbl: The table of constants to search.
	* @name: The name to look up.
	* @not_found: The value to return if the name is not found.
	*/
	int lookup_constant(const struct constant_table tbl, const char name, int not_found)
	{
	const struct constant_table *p = __lookup_constant(tbl, name);

	return p ? p->value : not_found;
	}
	EXPORT_SYMBOL(lookup_constant);

	static inline bool is_flag(const struct fs_parameter_spec *p)
	{
	return p->type == NULL;
	}

	static const struct fs_parameter_spec *fs_lookup_key(
	const struct fs_parameter_spec *desc,
	struct fs_parameter param, bool negated)
	{
	const struct fs_parameter_spec p, other = NULL;
	const char *name = param->key;
	bool want_flag = param->type == fs_value_is_flag;

	*negated = false;
	for (p = desc; p->name; p++) {
	if (strcmp(p->name, name) != 0)
	continue;
	if (likely(is_flag(p) == want_flag))
	return p;
	other = p;
	}
	if (want_flag) {
	if (name[0] == 'n' && name[1] == 'o' && name[2]) {
	for (p = desc; p->name; p++) {
	if (strcmp(p->name, name + 2) != 0)
	continue;
	if (!(p->flags & fs_param_neg_with_no))
	continue;
	*negated = true;
	return p;
	}
	}
	}
	return other;
	}

	/*
	* __fs_parse - Parse a filesystem configuration parameter
	* @log: The filesystem context to log errors through.
	* @desc: The parameter description to use.
	* @param: The parameter.
	* @result: Where to place the result of the parse
	*
	* Parse a filesystem configuration parameter and attempt a conversion for a
	* simple parameter for which this is requested. If successful, the determined
	* parameter ID is placed into @result->key, the desired type is indicated in
	* @result->t and any converted value is placed into an appropriate member of
	* the union in @result.
	*
	* The function returns the parameter number if the parameter was matched,
	* -ENOPARAM if it wasn't matched and @desc->ignore_unknown indicated that
	* unknown parameters are okay and -EINVAL if there was a conversion issue or
	* the parameter wasn't recognised and unknowns aren't okay.
	*/
	int __fs_parse(struct p_log *log,
	const struct fs_parameter_spec *desc,
	struct fs_parameter *param,
	struct fs_parse_result *result)
	{
	const struct fs_parameter_spec *p;

	result->uint_64 = 0;

	p = fs_lookup_key(desc, param, &result->negated);
	if (!p)
	return -ENOPARAM;

	if (p->flags & fs_param_deprecated)
	warn_plog(log, "Deprecated parameter '%s'", param->key);

	/* Try to turn the type we were given into the type desired by the
	* parameter and give an error if we can't.
	*/
	if (is_flag(p)) {
	if (param->type != fs_value_is_flag)
	return inval_plog(log, "Unexpected value for '%s'",
	param->key);
	result->boolean = !result->negated;
	} else {
	int ret = p->type(log, p, param, result);
	if (ret)
	return ret;
	}
	return p->opt;
	}
	EXPORT_SYMBOL(__fs_parse);

	/**
	* fs_lookup_param - Look up a path referred to by a parameter
	* @fc: The filesystem context to log errors through.
	* @param: The parameter.
	* @want_bdev: T if want a blockdev
	* @flags: Pathwalk flags passed to filename_lookup()
	* @_path: The result of the lookup
	*/
	int fs_lookup_param(struct fs_context *fc,
	struct fs_parameter *param,
	bool want_bdev,
	unsigned int flags,
	struct path *_path)
	{
	struct filename *f;
	bool put_f;
	int ret;

	switch (param->type) {
	case fs_value_is_string:
	f = getname_kernel(param->string);
	if (IS_ERR(f))
	return PTR_ERR(f);
	param->dirfd = AT_FDCWD;
	put_f = true;
	break;
	case fs_value_is_filename:
	f = param->name;
	put_f = false;
	break;
	default:
	return invalf(fc, "%s: not usable as path", param->key);
	}

	ret = filename_lookup(param->dirfd, f, flags, _path, NULL);
	if (ret < 0) {
	errorf(fc, "%s: Lookup failure for '%s'", param->key, f->name);
	goto out;
	}

	if (want_bdev &&
	!S_ISBLK(d_backing_inode(_path->dentry)->i_mode)) {
	path_put(_path);
	_path->dentry = NULL;
	_path->mnt = NULL;
	errorf(fc, "%s: Non-blockdev passed as '%s'",
	param->key, f->name);
	ret = -ENOTBLK;
	}

	out:
	if (put_f)
	putname(f);
	return ret;
	}
	EXPORT_SYMBOL(fs_lookup_param);

	static int fs_param_bad_value(struct p_log log, struct fs_parameter param)
	{
	return inval_plog(log, "Bad value for '%s'", param->key);
	}

	int fs_param_is_bool(struct p_log log, const struct fs_parameter_spec p,
	struct fs_parameter param, struct fs_parse_result result)
	{
	int b;
	if (param->type != fs_value_is_string)
	return fs_param_bad_value(log, param);
	if (!*param->string && (p->flags & fs_param_can_be_empty))
	return 0;
	b = lookup_constant(bool_names, param->string, -1);
	if (b == -1)
	return fs_param_bad_value(log, param);
	result->boolean = b;
	return 0;
	}
	EXPORT_SYMBOL(fs_param_is_bool);

	int fs_param_is_u32(struct p_log log, const struct fs_parameter_spec p,
	struct fs_parameter param, struct fs_parse_result result)
	{
	int base = (unsigned long)p->data;
	if (param->type != fs_value_is_string)
	return fs_param_bad_value(log, param);
	if (!*param->string && (p->flags & fs_param_can_be_empty))
	return 0;
	if (kstrtouint(param->string, base, &result->uint_32) < 0)
	return fs_param_bad_value(log, param);
	return 0;
	}
	EXPORT_SYMBOL(fs_param_is_u32);

	int fs_param_is_s32(struct p_log log, const struct fs_parameter_spec p,
	struct fs_parameter param, struct fs_parse_result result)
	{
	if (param->type != fs_value_is_string)
	return fs_param_bad_value(log, param);
	if (!*param->string && (p->flags & fs_param_can_be_empty))
	return 0;
	if (kstrtoint(param->string, 0, &result->int_32) < 0)
	return fs_param_bad_value(log, param);
	return 0;
	}
	EXPORT_SYMBOL(fs_param_is_s32);

	int fs_param_is_u64(struct p_log log, const struct fs_parameter_spec p,
	struct fs_parameter param, struct fs_parse_result result)
	{
	if (param->type != fs_value_is_string)
	return fs_param_bad_value(log, param);
	if (!*param->string && (p->flags & fs_param_can_be_empty))
	return 0;
	if (kstrtoull(param->string, 0, &result->uint_64) < 0)
	return fs_param_bad_value(log, param);
	return 0;
	}
	EXPORT_SYMBOL(fs_param_is_u64);

	int fs_param_is_enum(struct p_log log, const struct fs_parameter_spec p,
	struct fs_parameter param, struct fs_parse_result result)
	{
	const struct constant_table *c;
	if (param->type != fs_value_is_string)
	return fs_param_bad_value(log, param);
	if (!*param->string && (p->flags & fs_param_can_be_empty))
	return 0;
	c = __lookup_constant(p->data, param->string);
	if (!c)
	return fs_param_bad_value(log, param);
	result->uint_32 = c->value;
	return 0;
	}
	EXPORT_SYMBOL(fs_param_is_enum);

	int fs_param_is_string(struct p_log log, const struct fs_parameter_spec p,
	struct fs_parameter param, struct fs_parse_result result)
	{
	if (param->type != fs_value_is_string \|\|
	(!*param->string && !(p->flags & fs_param_can_be_empty)))
	return fs_param_bad_value(log, param);
	return 0;
	}
	EXPORT_SYMBOL(fs_param_is_string);

	int fs_param_is_blob(struct p_log log, const struct fs_parameter_spec p,
	struct fs_parameter param, struct fs_parse_result result)
	{
	if (param->type != fs_value_is_blob)
	return fs_param_bad_value(log, param);
	return 0;
	}
	EXPORT_SYMBOL(fs_param_is_blob);

	int fs_param_is_fd(struct p_log log, const struct fs_parameter_spec p,
	struct fs_parameter param, struct fs_parse_result result)
	{
	switch (param->type) {
	case fs_value_is_string:
	if ((!*param->string && !(p->flags & fs_param_can_be_empty)) \|\|
	kstrtouint(param->string, 0, &result->uint_32) < 0)
	break;
	if (result->uint_32 <= INT_MAX)
	return 0;
	break;
	case fs_value_is_file:
	result->uint_32 = param->dirfd;
	if (result->uint_32 <= INT_MAX)
	return 0;
	break;
	default:
	break;
	}
	return fs_param_bad_value(log, param);
	}
	EXPORT_SYMBOL(fs_param_is_fd);

	int fs_param_is_uid(struct p_log log, const struct fs_parameter_spec p,
	struct fs_parameter param, struct fs_parse_result result)
	{
	kuid_t uid;

	if (fs_param_is_u32(log, p, param, result) != 0)
	return fs_param_bad_value(log, param);

	uid = make_kuid(current_user_ns(), result->uint_32);
	if (!uid_valid(uid))
	return inval_plog(log, "Invalid uid '%s'", param->string);

	result->uid = uid;
	return 0;
	}
	EXPORT_SYMBOL(fs_param_is_uid);

	int fs_param_is_gid(struct p_log log, const struct fs_parameter_spec p,
	struct fs_parameter param, struct fs_parse_result result)
	{
	kgid_t gid;

	if (fs_param_is_u32(log, p, param, result) != 0)
	return fs_param_bad_value(log, param);

	gid = make_kgid(current_user_ns(), result->uint_32);
	if (!gid_valid(gid))
	return inval_plog(log, "Invalid gid '%s'", param->string);

	result->gid = gid;
	return 0;
	}
	EXPORT_SYMBOL(fs_param_is_gid);

	int fs_param_is_blockdev(struct p_log log, const struct fs_parameter_spec p,
	struct fs_parameter param, struct fs_parse_result result)
	{
	return 0;
	}
	EXPORT_SYMBOL(fs_param_is_blockdev);

	int fs_param_is_path(struct p_log log, const struct fs_parameter_spec p,
	struct fs_parameter param, struct fs_parse_result result)
	{
	return 0;
	}
	EXPORT_SYMBOL(fs_param_is_path);

	#ifdef CONFIG_VALIDATE_FS_PARSER
	/**
	* validate_constant_table - Validate a constant table
	* @tbl: The constant table to validate.
	* @tbl_size: The size of the table.
	* @low: The lowest permissible value.
	* @high: The highest permissible value.
	* @special: One special permissible value outside of the range.
	*/
	bool validate_constant_table(const struct constant_table *tbl, size_t tbl_size,
	int low, int high, int special)
	{
	size_t i;
	bool good = true;

	if (tbl_size == 0) {
	pr_warn("VALIDATE C-TBL: Empty\n");
	return true;
	}

	for (i = 0; i < tbl_size; i++) {
	if (!tbl[i].name) {
	pr_err("VALIDATE C-TBL[%zu]: Null\n", i);
	good = false;
	} else if (i > 0 && tbl[i - 1].name) {
	int c = strcmp(tbl[i-1].name, tbl[i].name);

	if (c == 0) {
	pr_err("VALIDATE C-TBL[%zu]: Duplicate %s\n",
	i, tbl[i].name);
	good = false;
	}
	if (c > 0) {
	pr_err("VALIDATE C-TBL[%zu]: Missorted %s>=%s\n",
	i, tbl[i-1].name, tbl[i].name);
	good = false;
	}
	}

	if (tbl[i].value != special &&
	(tbl[i].value < low \|\| tbl[i].value > high)) {
	pr_err("VALIDATE C-TBL[%zu]: %s->%d const out of range (%d-%d)\n",
	i, tbl[i].name, tbl[i].value, low, high);
	good = false;
	}
	}

	return good;
	}

	/**
	* fs_validate_description - Validate a parameter description
	* @name: The parameter name to search for.
	* @desc: The parameter description to validate.
	*/
	bool fs_validate_description(const char *name,
	const struct fs_parameter_spec *desc)
	{
	const struct fs_parameter_spec param, p2;
	bool good = true;

	for (param = desc; param->name; param++) {
	/* Check for duplicate parameter names */
	for (p2 = desc; p2 < param; p2++) {
	if (strcmp(param->name, p2->name) == 0) {
	if (is_flag(param) != is_flag(p2))
	continue;
	pr_err("VALIDATE %s: PARAM[%s]: Duplicate\n",
	name, param->name);
	good = false;
	}
	}
	}
	return good;
	}
	#endif /* CONFIG_VALIDATE_FS_PARSER */