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03685825c9
Adds a pre-load permission check in exec_internal() to verify the calling task has the required execute (x) bits for the target file. Properly evaluates root (euid == 0), owner, group, and other permissions. This ensures POSIX compliance and cleanly rejects unauthorized files with -EACCES before they reach the ELF loader, preventing unnecessary memory allocation and downstream hardware execution faults. Signed-off-by: Abhishek Mishra <mishra.abhishek2808@gmail.com>
100 lines
2.8 KiB
C
100 lines
2.8 KiB
C
/****************************************************************************
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* binfmt/binfmt_checkexec.c
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*
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* SPDX-License-Identifier: Apache-2.0
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership. The
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* ASF licenses this file to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance with the
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* License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*
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****************************************************************************/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <nuttx/config.h>
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#include <sys/stat.h>
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#include <errno.h>
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#include <nuttx/sched.h>
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#include <nuttx/binfmt/binfmt.h>
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#include "binfmt.h"
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: binfmt_checkexecperm
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*
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* Description:
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* Verify that the calling task has execute permission on the file
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* described by 'bin'. The file owner, group, and mode must already be
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* populated in the binary_s structure before calling this function.
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*
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* Input Parameters:
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* bin - Pointer to the binary descriptor with uid, gid, and mode set.
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*
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* Returned Value:
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* Zero (OK) on success; -EACCES if execute permission is denied.
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*
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****************************************************************************/
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int binfmt_checkexecperm(FAR struct binary_s *bin)
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{
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FAR struct tcb_s *rtcb;
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mode_t xbits;
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rtcb = nxsched_self();
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if (bin == NULL || rtcb == NULL || rtcb->group == NULL)
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{
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return OK;
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}
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if (rtcb->group->tg_euid == 0)
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{
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/* Root can execute any file that has at least one execute bit set */
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if ((bin->mode & (S_IXUSR | S_IXGRP | S_IXOTH)) == 0)
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{
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return -EACCES;
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}
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return OK;
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}
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if (rtcb->group->tg_euid == bin->uid)
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{
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xbits = S_IXUSR;
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}
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else if (rtcb->group->tg_egid == bin->gid)
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{
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xbits = S_IXGRP;
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}
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else
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{
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xbits = S_IXOTH;
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}
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if ((bin->mode & xbits) == 0)
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{
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return -EACCES;
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}
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return OK;
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}
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