linux-stable/fs/fs_parser.c
Lukas Czerner 6abfaaf124 fs_parse: allow parameter value to be empty
Allow parameter value to be empty by specifying fs_param_can_be_empty
flag.

Signed-off-by: Lukas Czerner <lczerner@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>
Link: https://lore.kernel.org/r/20211027141857.33657-2-lczerner@redhat.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2021-12-09 14:09:36 -05:00

399 lines
11 KiB
C

// 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);
}
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_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 */