445 lines
11 KiB
C
445 lines
11 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/* Filesystem parameter parser.
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*
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* Copyright (C) 2018 Red Hat, Inc. All Rights Reserved.
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* Written by David Howells (dhowells@redhat.com)
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*/
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#include <linux/export.h>
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#include <linux/fs_context.h>
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#include <linux/fs_parser.h>
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#include <linux/slab.h>
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#include <linux/security.h>
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#include <linux/namei.h>
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#include "internal.h"
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static const struct constant_table bool_names[] = {
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{ "0", false },
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{ "1", true },
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{ "false", false },
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{ "no", false },
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{ "true", true },
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{ "yes", true },
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};
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/**
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* lookup_constant - Look up a constant by name in an ordered table
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* @tbl: The table of constants to search.
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* @tbl_size: The size of the table.
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* @name: The name to look up.
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* @not_found: The value to return if the name is not found.
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*/
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int __lookup_constant(const struct constant_table *tbl, size_t tbl_size,
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const char *name, int not_found)
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{
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unsigned int i;
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for (i = 0; i < tbl_size; i++)
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if (strcmp(name, tbl[i].name) == 0)
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return tbl[i].value;
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return not_found;
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}
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EXPORT_SYMBOL(__lookup_constant);
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static const struct fs_parameter_spec *fs_lookup_key(
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const struct fs_parameter_description *desc,
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const char *name)
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{
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const struct fs_parameter_spec *p;
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if (!desc->specs)
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return NULL;
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for (p = desc->specs; p->name; p++)
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if (strcmp(p->name, name) == 0)
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return p;
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return NULL;
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}
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/*
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* fs_parse - Parse a filesystem configuration parameter
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* @fc: The filesystem context to log errors through.
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* @desc: The parameter description to use.
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* @param: The parameter.
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* @result: Where to place the result of the parse
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*
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* Parse a filesystem configuration parameter and attempt a conversion for a
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* simple parameter for which this is requested. If successful, the determined
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* parameter ID is placed into @result->key, the desired type is indicated in
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* @result->t and any converted value is placed into an appropriate member of
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* the union in @result.
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*
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* The function returns the parameter number if the parameter was matched,
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* -ENOPARAM if it wasn't matched and @desc->ignore_unknown indicated that
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* unknown parameters are okay and -EINVAL if there was a conversion issue or
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* the parameter wasn't recognised and unknowns aren't okay.
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*/
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int fs_parse(struct fs_context *fc,
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const struct fs_parameter_description *desc,
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struct fs_parameter *param,
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struct fs_parse_result *result)
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{
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const struct fs_parameter_spec *p;
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const struct fs_parameter_enum *e;
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int ret = -ENOPARAM, b;
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result->has_value = !!param->string;
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result->negated = false;
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result->uint_64 = 0;
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p = fs_lookup_key(desc, param->key);
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if (!p) {
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/* If we didn't find something that looks like "noxxx", see if
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* "xxx" takes the "no"-form negative - but only if there
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* wasn't an value.
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*/
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if (result->has_value)
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goto unknown_parameter;
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if (param->key[0] != 'n' || param->key[1] != 'o' || !param->key[2])
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goto unknown_parameter;
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p = fs_lookup_key(desc, param->key + 2);
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if (!p)
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goto unknown_parameter;
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if (!(p->flags & fs_param_neg_with_no))
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goto unknown_parameter;
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result->boolean = false;
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result->negated = true;
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}
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if (p->flags & fs_param_deprecated)
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warnf(fc, "%s: Deprecated parameter '%s'",
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desc->name, param->key);
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if (result->negated)
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goto okay;
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/* Certain parameter types only take a string and convert it. */
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switch (p->type) {
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case __fs_param_wasnt_defined:
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return -EINVAL;
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case fs_param_is_u32:
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case fs_param_is_u32_octal:
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case fs_param_is_u32_hex:
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case fs_param_is_s32:
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case fs_param_is_u64:
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case fs_param_is_enum:
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case fs_param_is_string:
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if (param->type != fs_value_is_string)
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goto bad_value;
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if (!result->has_value) {
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if (p->flags & fs_param_v_optional)
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goto okay;
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goto bad_value;
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}
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/* Fall through */
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default:
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break;
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}
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/* Try to turn the type we were given into the type desired by the
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* parameter and give an error if we can't.
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*/
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switch (p->type) {
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case fs_param_is_flag:
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if (param->type != fs_value_is_flag &&
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(param->type != fs_value_is_string || result->has_value))
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return invalf(fc, "%s: Unexpected value for '%s'",
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desc->name, param->key);
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result->boolean = true;
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goto okay;
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case fs_param_is_bool:
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switch (param->type) {
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case fs_value_is_flag:
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result->boolean = true;
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goto okay;
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case fs_value_is_string:
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if (param->size == 0) {
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result->boolean = true;
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goto okay;
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}
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b = lookup_constant(bool_names, param->string, -1);
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if (b == -1)
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goto bad_value;
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result->boolean = b;
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goto okay;
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default:
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goto bad_value;
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}
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case fs_param_is_u32:
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ret = kstrtouint(param->string, 0, &result->uint_32);
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goto maybe_okay;
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case fs_param_is_u32_octal:
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ret = kstrtouint(param->string, 8, &result->uint_32);
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goto maybe_okay;
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case fs_param_is_u32_hex:
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ret = kstrtouint(param->string, 16, &result->uint_32);
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goto maybe_okay;
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case fs_param_is_s32:
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ret = kstrtoint(param->string, 0, &result->int_32);
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goto maybe_okay;
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case fs_param_is_u64:
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ret = kstrtoull(param->string, 0, &result->uint_64);
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goto maybe_okay;
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case fs_param_is_enum:
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for (e = desc->enums; e->name[0]; e++) {
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if (e->opt == p->opt &&
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strcmp(e->name, param->string) == 0) {
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result->uint_32 = e->value;
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goto okay;
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}
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}
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goto bad_value;
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case fs_param_is_string:
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goto okay;
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case fs_param_is_blob:
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if (param->type != fs_value_is_blob)
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goto bad_value;
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goto okay;
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case fs_param_is_fd: {
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if (param->type != fs_value_is_file)
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goto bad_value;
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goto okay;
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}
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case fs_param_is_blockdev:
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case fs_param_is_path:
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goto okay;
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default:
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BUG();
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}
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maybe_okay:
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if (ret < 0)
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goto bad_value;
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okay:
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return p->opt;
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bad_value:
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return invalf(fc, "%s: Bad value for '%s'", desc->name, param->key);
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unknown_parameter:
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return -ENOPARAM;
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}
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EXPORT_SYMBOL(fs_parse);
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/**
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* fs_lookup_param - Look up a path referred to by a parameter
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* @fc: The filesystem context to log errors through.
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* @param: The parameter.
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* @want_bdev: T if want a blockdev
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* @_path: The result of the lookup
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*/
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int fs_lookup_param(struct fs_context *fc,
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struct fs_parameter *param,
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bool want_bdev,
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struct path *_path)
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{
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struct filename *f;
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unsigned int flags = 0;
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bool put_f;
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int ret;
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switch (param->type) {
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case fs_value_is_string:
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f = getname_kernel(param->string);
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if (IS_ERR(f))
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return PTR_ERR(f);
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put_f = true;
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break;
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case fs_value_is_filename_empty:
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flags = LOOKUP_EMPTY;
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/* Fall through */
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case fs_value_is_filename:
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f = param->name;
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put_f = false;
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break;
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default:
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return invalf(fc, "%s: not usable as path", param->key);
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}
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f->refcnt++; /* filename_lookup() drops our ref. */
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ret = filename_lookup(param->dirfd, f, flags, _path, NULL);
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if (ret < 0) {
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errorf(fc, "%s: Lookup failure for '%s'", param->key, f->name);
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goto out;
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}
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if (want_bdev &&
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!S_ISBLK(d_backing_inode(_path->dentry)->i_mode)) {
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path_put(_path);
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_path->dentry = NULL;
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_path->mnt = NULL;
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errorf(fc, "%s: Non-blockdev passed as '%s'",
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param->key, f->name);
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ret = -ENOTBLK;
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}
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out:
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if (put_f)
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putname(f);
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return ret;
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}
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EXPORT_SYMBOL(fs_lookup_param);
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#ifdef CONFIG_VALIDATE_FS_PARSER
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/**
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* validate_constant_table - Validate a constant table
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* @name: Name to use in reporting
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* @tbl: The constant table to validate.
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* @tbl_size: The size of the table.
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* @low: The lowest permissible value.
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* @high: The highest permissible value.
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* @special: One special permissible value outside of the range.
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*/
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bool validate_constant_table(const struct constant_table *tbl, size_t tbl_size,
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int low, int high, int special)
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{
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size_t i;
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bool good = true;
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if (tbl_size == 0) {
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pr_warn("VALIDATE C-TBL: Empty\n");
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return true;
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}
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for (i = 0; i < tbl_size; i++) {
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if (!tbl[i].name) {
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pr_err("VALIDATE C-TBL[%zu]: Null\n", i);
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good = false;
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} else if (i > 0 && tbl[i - 1].name) {
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int c = strcmp(tbl[i-1].name, tbl[i].name);
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if (c == 0) {
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pr_err("VALIDATE C-TBL[%zu]: Duplicate %s\n",
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i, tbl[i].name);
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good = false;
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}
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if (c > 0) {
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pr_err("VALIDATE C-TBL[%zu]: Missorted %s>=%s\n",
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i, tbl[i-1].name, tbl[i].name);
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good = false;
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}
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}
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if (tbl[i].value != special &&
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(tbl[i].value < low || tbl[i].value > high)) {
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pr_err("VALIDATE C-TBL[%zu]: %s->%d const out of range (%d-%d)\n",
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i, tbl[i].name, tbl[i].value, low, high);
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good = false;
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}
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}
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return good;
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}
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/**
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* fs_validate_description - Validate a parameter description
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* @desc: The parameter description to validate.
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*/
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bool fs_validate_description(const struct fs_parameter_description *desc)
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{
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const struct fs_parameter_spec *param, *p2;
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const struct fs_parameter_enum *e;
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const char *name = desc->name;
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unsigned int nr_params = 0;
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bool good = true, enums = false;
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pr_notice("*** VALIDATE %s ***\n", name);
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if (!name[0]) {
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pr_err("VALIDATE Parser: No name\n");
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name = "Unknown";
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good = false;
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}
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if (desc->specs) {
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for (param = desc->specs; param->name; param++) {
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enum fs_parameter_type t = param->type;
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/* Check that the type is in range */
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if (t == __fs_param_wasnt_defined ||
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t >= nr__fs_parameter_type) {
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pr_err("VALIDATE %s: PARAM[%s] Bad type %u\n",
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name, param->name, t);
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good = false;
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} else if (t == fs_param_is_enum) {
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enums = true;
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}
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/* Check for duplicate parameter names */
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for (p2 = desc->specs; p2 < param; p2++) {
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if (strcmp(param->name, p2->name) == 0) {
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pr_err("VALIDATE %s: PARAM[%s]: Duplicate\n",
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name, param->name);
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good = false;
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}
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}
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}
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nr_params = param - desc->specs;
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}
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if (desc->enums) {
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if (!nr_params) {
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pr_err("VALIDATE %s: Enum table but no parameters\n",
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name);
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good = false;
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goto no_enums;
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}
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if (!enums) {
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pr_err("VALIDATE %s: Enum table but no enum-type values\n",
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name);
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good = false;
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goto no_enums;
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}
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for (e = desc->enums; e->name[0]; e++) {
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/* Check that all entries in the enum table have at
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* least one parameter that uses them.
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*/
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for (param = desc->specs; param->name; param++) {
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if (param->opt == e->opt &&
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param->type != fs_param_is_enum) {
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pr_err("VALIDATE %s: e[%tu] enum val for %s\n",
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name, e - desc->enums, param->name);
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good = false;
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}
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}
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}
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/* Check that all enum-type parameters have at least one enum
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* value in the enum table.
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*/
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for (param = desc->specs; param->name; param++) {
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if (param->type != fs_param_is_enum)
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continue;
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for (e = desc->enums; e->name[0]; e++)
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if (e->opt == param->opt)
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break;
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if (!e->name[0]) {
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pr_err("VALIDATE %s: PARAM[%s] enum with no values\n",
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name, param->name);
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good = false;
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}
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}
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} else {
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if (enums) {
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pr_err("VALIDATE %s: enum-type values, but no enum table\n",
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name);
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good = false;
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goto no_enums;
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}
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}
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no_enums:
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return good;
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}
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#endif /* CONFIG_VALIDATE_FS_PARSER */
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