[NTLUG:Discuss] C Program Woes on Ubuntu

[George Lass]

I'm not exactly sure why, but apparently Ubuntu will not allow execution of *anything* in sub directories below /run.  I was logged into my server via ssh as root (not sudo'ed).  I created a directory called bin (/run/bin) and tried to build and execute my C program there.  Copying the executable *anywhere* else allows it to be executed.
Thanks all,
George

      From: Lee Heath <madhat at gmail.com>
 To: George Lass <george.lass at sbcglobal.net>; NTLUG Discussion List <discuss at ntlug.org> 
 Sent: Thursday, May 31, 2018 12:47 PM
 Subject: Re: [NTLUG:Discuss] C Program Woes on Ubuntu
   
Do you have selinux enabled?
https://en.wikipedia.org/wiki/Security-Enhanced_Linux

$ sudo getenforce
[sudo] password for me: 
Disabled

Have you check the logs?

$ sudo grep -r x-bash /var/log/* 


> On May 31, 2018, at 12:26 PM, George Lass <george.lass at sbcglobal.net> wrote:
> 
> I have just installed Ubuntu 18.04 LTS on a 4 or 5 year old Dell PowerEdge R210 II.  I have updated and upgraded to the latest versions of everything.  I am having problems trying to execute even the simplest C Language program:
> #include <stdio.h>
> int main(int argc, char *argv[]){        printf("this is a test");        return 0;}
> 
> No problem building the executable from the source file x.c:
> # make xcc      x.c      -o x
> But I am unable to actually run the executable:
> # ./x-bash: ./x: Permission denied
> 
> It isn't a problem with file permission:
> # ls -l x-rwxr-xr-x 1 root root 8288 May 31 12:19 x
> 
> And I don't *think* it's a compatibility issue with shared objects since it seems to use the same library as bash:
> # file xx: ELF 64-bit LSB shared object, x86-64, version 1 (SYSV), dynamically linked, interpreter /lib64/ld-linux-x86-64.so.2, for GNU/Linux 3.2.0, BuildID[sha1]=4167fc090a21cefc7aa84aae77c4203bb35ac56b, not stripped
> 
> # file /bin/bash/bin/bash: ELF 64-bit LSB shared object, x86-64, version 1 (SYSV), dynamically linked, interpreter /lib64/ld-linux-x86-64.so.2, for GNU/Linux 3.2.0, BuildID[sha1]=b636f50d85c3cca7cf2518030446660c1d90d660, stripped
> Does anyone have any ideas as to what is going on?
> Thanks,
> George Lass
> 
> _______________________________________________
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Lee Heath
InfoSec Mercenary
@unspecific