[Toybox] setuid (TOYFLAG_STAYROOT) requirement - in nested case

[Rob Landley]

On 05/10/2013 03:29:46 AM, Ashwini Sharma wrote:
> Hey Rob,
> 
>    I have a case, where setuid is required in nested case.
> 
> nested case:
>   lets say there are two commands in toybox called __acmd__ and  
> __bcmd__.
> __acmd__ doesn't require setuid bit, whereas __bcmd__ does require  
> setuid
> bit.
> 
> Take a case where __acmd__ will run/launch __bcmd__. Now since  
> __acmd__
> doesn't need TOYFLAG_STAYROOT, this sets the euid to be of uid in
> toy_init() function.
> When __bcmd__ is run from __acmd__, this would have lost the setuid  
> bit and
> hence fails to run due to this.

Use execvp(bcmd) instead of toy_exec(bcmd). Toybox can't re-escalate to  
suid, so you have to ask the operating system to do so.

I should add a check for this in toysh...

Rob