Re: [patch] remove MNT_NOEXEC check for PROT_EXEC mmaps

On 03/10/06, Stas Sergeev <stsp@xxxxxxxx> wrote:
Hello.

Arjan van de Ven wrote:
> no what bothers me that on the one hand you want no execute from the
> partition, and AT THE SAME TIME want stuff to execute from there (being
> libraries or binaries, same thing to me).
The original problem came from "noexec" on /dev/shm
mount. There is no library and no binary there, but
the programs do shm_open(), ftruncate() and
mmap(MAP_SHARED, PROT_EXEC) to get some shared memory
with an exec perm. That fails.


So first you mount /dev/shm with 'noexec', thereby telling the system
"please make shared memory non executable".
Then an application goes and asks for executable shared memory, gets
denied and thus fails. And that's a problem? It's exactely what you
asked for.

Either you want non-executable shared memory, so you mount /dev/shm
'noexec' or you want shared memory to be executable, in which case you
don't mount it 'noexec'.

As I see it, that's really all there is to it.

--
Jesper Juhl <jesper.juhl@xxxxxxxxx>
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