/* Filesystem parameter parser.
*
* Copyright (C) 2018 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public Licence
* as published by the Free Software Foundation; either version
* 2 of the Licence, or (at your option) any later version.
*/
#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 },
};
/**
* lookup_constant - Look up a constant by name in an ordered table
* @tbl: The table of constants to search.
* @tbl_size: The size of the table.
* @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, size_t tbl_size,
const char *name, int not_found)
{
unsigned int i;
for (i = 0; i < tbl_size; i++)
if (strcmp(name, tbl[i].name) == 0)
return tbl[i].value;
return not_found;
}
EXPORT_SYMBOL(__lookup_constant);
static const struct fs_parameter_spec *fs_lookup_key(
const struct fs_parameter_description *desc,
const char *name)
{
const struct fs_parameter_spec *p;
if (!desc->specs)
return NULL;
for (p = desc->specs; p->name; p++)
if (strcmp(p->name, name) == 0)
return p;
return NULL;
}
/*
* 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 fs_context *fc,
const struct fs_parameter_description *desc,
struct fs_parameter *param,
struct fs_parse_result *result)
{
const struct fs_parameter_spec *p;
const struct fs_parameter_enum *e;
int ret = -ENOPARAM, b;
result->has_value = !!param->string;
result->negated = false;
result->uint_64 = 0;
p = fs_lookup_key(desc, param->key);
if (!p) {
/* If we didn't find something that looks like "noxxx", see if
* "xxx" takes the "no"-form negative - but only if there
* wasn't an value.
*/
if (result->has_value)
goto unknown_parameter;
if (param->key[0] != 'n' || param->key[1] != 'o' || !param->key[2])
goto unknown_parameter;
p = fs_lookup_key(desc, param->key + 2);
if (!p)
goto unknown_parameter;
if (!(p->flags & fs_param_neg_with_no))
goto unknown_parameter;
result->boolean = false;
result->negated = true;
}
if (p->flags & fs_param_deprecated)
warnf(fc, "%s: Deprecated parameter '%s'",
desc->name, param->key);
if (result->negated)
goto okay;
/* Certain parameter types only take a string and convert it. */
switch (p->type) {
case __fs_param_wasnt_defined:
return -EINVAL;
case fs_param_is_u32:
case fs_param_is_u32_octal:
case fs_param_is_u32_hex:
case fs_param_is_s32:
case fs_param_is_u64:
case fs_param_is_enum:
case fs_param_is_string:
if (param->type != fs_value_is_string)
goto bad_value;
if (!result->has_value) {
if (p->flags & fs_param_v_optional)
goto okay;
goto bad_value;
}
/* Fall through */
default:
break;
}
/* Try to turn the type we were given into the type desired by the
* parameter and give an error if we can't.
*/
switch (p->type) {
case fs_param_is_flag:
if (param->type != fs_value_is_flag &&
(param->type != fs_value_is_string || result->has_value))
return invalf(fc, "%s: Unexpected value for '%s'",
desc->name, param->key);
result->boolean = true;
goto okay;
case fs_param_is_bool:
switch (param->type) {
case fs_value_is_flag:
result->boolean = true;
goto okay;
case fs_value_is_string:
if (param->size == 0) {
result->boolean = true;
goto okay;
}
b = lookup_constant(bool_names, param->string, -1);
if (b == -1)
goto bad_value;
result->boolean = b;
goto okay;
default:
goto bad_value;
}
case fs_param_is_u32:
ret = kstrtouint(param->string, 0, &result->uint_32);
goto maybe_okay;
case fs_param_is_u32_octal:
ret = kstrtouint(param->string, 8, &result->uint_32);
goto maybe_okay;
case fs_param_is_u32_hex:
ret = kstrtouint(param->string, 16, &result->uint_32);
goto maybe_okay;
case fs_param_is_s32:
ret = kstrtoint(param->string, 0, &result->int_32);
goto maybe_okay;
case fs_param_is_u64:
ret = kstrtoull(param->string, 0, &result->uint_64);
goto maybe_okay;
case fs_param_is_enum:
for (e = desc->enums; e->name[0]; e++) {
if (e->opt == p->opt &&
strcmp(e->name, param->string) == 0) {
result->uint_32 = e->value;
goto okay;
}
}
goto bad_value;
case fs_param_is_string:
goto okay;
case fs_param_is_blob:
if (param->type != fs_value_is_blob)
goto bad_value;
goto okay;
case fs_param_is_fd: {
if (param->type != fs_value_is_file)
goto bad_value;
goto okay;
}
case fs_param_is_blockdev:
case fs_param_is_path:
goto okay;
default:
BUG();
}
maybe_okay:
if (ret < 0)
goto bad_value;
okay:
return p->opt;
bad_value:
return invalf(fc, "%s: Bad value for '%s'", desc->name, param->key);
unknown_parameter:
return -ENOPARAM;
}
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_empty:
flags = LOOKUP_EMPTY;
/* Fall through */
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);
#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\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
* @desc: The parameter description to validate.
*/
bool fs_validate_description(const struct fs_parameter_description *desc)
{
const struct fs_parameter_spec *param, *p2;
const struct fs_parameter_enum *e;
const char *name = desc->name;
unsigned int nr_params = 0;
bool good = true, enums = false;
pr_notice("*** VALIDATE %s ***\n", name);
if (!name[0]) {
pr_err("VALIDATE Parser: No name\n");
name = "Unknown";
good = false;
}
if (desc->specs) {
for (param = desc->specs; param->name; param++) {
enum fs_parameter_type t = param->type;
/* Check that the type is in range */
if (t == __fs_param_wasnt_defined ||
t >= nr__fs_parameter_type) {
pr_err("VALIDATE %s: PARAM[%s] Bad type %u\n",
name, param->name, t);
good = false;
} else if (t == fs_param_is_enum) {
enums = true;
}
/* Check for duplicate parameter names */
for (p2 = desc->specs; p2 < param; p2++) {
if (strcmp(param->name, p2->name) == 0) {
pr_err("VALIDATE %s: PARAM[%s]: Duplicate\n",
name, param->name);
good = false;
}
}
}
nr_params = param - desc->specs;
}
if (desc->enums) {
if (!nr_params) {
pr_err("VALIDATE %s: Enum table but no parameters\n",
name);
good = false;
goto no_enums;
}
if (!enums) {
pr_err("VALIDATE %s: Enum table but no enum-type values\n",
name);
good = false;
goto no_enums;
}
for (e = desc->enums; e->name[0]; e++) {
/* Check that all entries in the enum table have at
* least one parameter that uses them.
*/
for (param = desc->specs; param->name; param++) {
if (param->opt == e->opt &&
param->type != fs_param_is_enum) {
pr_err("VALIDATE %s: e[%tu] enum val for %s\n",
name, e - desc->enums, param->name);
good = false;
}
}
}
/* Check that all enum-type parameters have at least one enum
* value in the enum table.
*/
for (param = desc->specs; param->name; param++) {
if (param->type != fs_param_is_enum)
continue;
for (e = desc->enums; e->name[0]; e++)
if (e->opt == param->opt)
break;
if (!e->name[0]) {
pr_err("VALIDATE %s: PARAM[%s] enum with no values\n",
name, param->name);
good = false;
}
}
} else {
if (enums) {
pr_err("VALIDATE %s: enum-type values, but no enum table\n",
name);
good = false;
goto no_enums;
}
}
no_enums:
return good;
}
#endif /* CONFIG_VALIDATE_FS_PARSER */
