Re: W^X toggle button in RWX allocation

Kamil Rytarowski <[email protected]> Sun, 4 Jun 2017 16:14:13 +0200
Newsgroups gmane.os.netbsd.devel.security
Message-ID <[email protected]>
On 04.06.2017 15:21, Joerg Sonnenberger wrote:
> On Sun, Jun 04, 2017 at 02:41:16PM +0200, Kamil Rytarowski wrote:
>> There is a new code for RWX memory mapping with MAP_REMAPDUP.
>>
>> Is there a functionality to switch which mapping is in force? To
>> manually switch between RW or RX? This would be useful for the W^X
>> mechanism in firefox.
>>
>> https://jandemooij.nl/blog/2015/12/29/wx-jit-code-enabled-in-firefox/
> 
> Look at the libffi and t_mprotect changes. That basically cover the
> normal ways to do this.
> 
> Joerg
> 

Does it mean that we need to perform duplication of a mapping for each
switch RW - RX, and munmap(2) the old one?
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