// 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
   * @fc: 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
   * @_path: The result of the lookup
   */
  int fs_lookup_param(struct fs_context *fc,
  		    struct fs_parameter *param,
  		    bool want_bdev,
  		    struct path *_path)
  {
  	struct filename *f;
  	unsigned int flags = 0;
  	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);
  		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);
  	}

  	f->refcnt++; /* filename_lookup() drops our ref. */

  	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);
  	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 ||
  	    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 ||
  	    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 ||
  	    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);
  	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)
  		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 (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_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
   * @name: Name to use in reporting
   * @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
  ");
  		return true;
  	}
  
  	for (i = 0; i < tbl_size; i++) {
  		if (!tbl[i].name) {
  			pr_err("VALIDATE C-TBL[%zu]: Null
  ", 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
  ",
  				       i, tbl[i].name);
  				good = false;
  			}
  			if (c > 0) {
  				pr_err("VALIDATE C-TBL[%zu]: Missorted %s>=%s
  ",
  				       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)
  ",
  			       i, tbl[i].name, tbl[i].value, low, high);
  			good = false;
  		}
  	}
  
  	return good;
  }
  
  /**
   * fs_validate_description - Validate a parameter description
   * @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
  ",
  				       name, param->name);
  				good = false;

  			}
  		}

  	}

  	return good;
  }
  #endif /* CONFIG_VALIDATE_FS_PARSER */