lists.openwall.net   lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  linux-cve-announce  PHC 
Open Source and information security mailing list archives
 
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <9561.1176209728@redhat.com>
Date:	Tue, 10 Apr 2007 13:55:28 +0100
From:	David Howells <dhowells@...hat.com>
To:	Robin Getz <rgetz@...ckfin.uclinux.org>
Cc:	bryan.wu@...log.com, "Alan Cox" <alan@...rguk.ukuu.org.uk>,
	waltje@...lt.nl.mugnet.org, "Aubrey Li" <aubreylee@...il.com>,
	netdev@...r.kernel.org, "Andrew Morton" <akpm@...l.org>,
	"Linux Kernel" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] CONFIG_PACKET_MMAP should depend on MMU 

Robin Getz <rgetz@...ckfin.uclinux.org> wrote:

> David - I know you have been reworking the noMMU vma handling - is there a 
> solution to vm_insert_page?

The reason vm_insert_page() is being called, I imagine, is because
packet_mmap() has to insert mappings to an already existing buffer.  All it
does is munge the PTEs in that virtual region to point to the buffer.

As long as the buffer is completely contiguous (which I don't know for
certain), then this function can be trivially reduced in NOMMU-mode to
something that just returns the address of the requested part of the buffer.
No remapping would be required.

However...  If the buffer is *not* completely contiguous, then you can still
perform mmaps of it - but only where the desired part _is_ contiguous.
Alternatively, you can arrange for the buffer to be completely contiguous
upfront.

Looking at alloc_pg_vec() in af_packet.c, I will place my bets on the latter
case.  I don't know that this is a problem; it depends on how things work, and
that I don't know offhand.  If someone can give me a simple test program, I
would be able to evaluate it better.

David
-
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Powered by blists - more mailing lists