nuttx/sched/environ/env_secureexec.c
Abhishek Mishra e29db6724c sched,fs,docs: support setuid sudo helper
Supports the UNIX setuid-on-exec sudo helper. Documents the model,
generates an extra ROMFS user and /etc/sudoers for a non-root test,
reports BINFS modes from the builtin table so ls -l matches execute
bits, and skips NULL environment entries when sanitizing a setuid exec.

Signed-off-by: Abhishek Mishra <mishra.abhishek2808@gmail.com>
2026-08-18 15:57:52 +08:00

133 lines
3.7 KiB
C

/****************************************************************************
* sched/environ/env_secureexec.c
*
* SPDX-License-Identifier: Apache-2.0
*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership. The
* ASF licenses this file to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance with the
* License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations
* under the License.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <stdbool.h>
#include <string.h>
#include <stdlib.h>
#include <assert.h>
#include "sched/sched.h"
#include "environ/environ.h"
/****************************************************************************
* Private Functions
****************************************************************************/
#ifdef CONFIG_SCHED_USER_IDENTITY
/****************************************************************************
* Name: env_is_unsafe
*
* Description:
* Return true if the "NAME=value" pair must not be inherited by a secure
* (set-user-ID or set-group-ID) executable.
*
****************************************************************************/
static bool env_is_unsafe(FAR const char *pair)
{
static FAR const char * const names[] =
{
"IFS=",
"CDPATH=",
"ENV=",
"BASH_ENV=",
"PATH=",
"HOSTALIASES=",
"LOCPATH=",
"GCONV_PATH=",
"TZDIR=",
"LOCALDOMAIN=",
"NLSPATH=",
NULL
};
FAR const char * const *name;
for (name = names; *name != NULL; name++)
{
if (pair != NULL && strncmp(pair, *name, strlen(*name)) == 0)
{
return true;
}
}
if (pair == NULL)
{
return false;
}
return strncmp(pair, "LD_", 3) == 0 ||
strncmp(pair, "MALLOC_", 7) == 0;
}
#endif /* CONFIG_SCHED_USER_IDENTITY */
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: env_sanitize_secure
****************************************************************************/
#ifdef CONFIG_SCHED_USER_IDENTITY
void env_sanitize_secure(FAR struct task_group_s *group)
{
ssize_t index;
DEBUGASSERT(group != NULL);
nxrmutex_lock(&group->tg_mutex);
for (index = group->tg_envc - 1; index >= 0; )
{
FAR char *pair = group->tg_envp[index];
if (pair != NULL && env_is_unsafe(pair))
{
env_removevar(group, index);
}
else
{
index--;
}
}
nxrmutex_unlock(&group->tg_mutex);
}
#endif
/****************************************************************************
* Name: secure_getenv
****************************************************************************/
FAR char *secure_getenv(FAR const char *name)
{
return issetugid() ? NULL : getenv(name);
}