Re: [PATCH] Configure MTU via kernel DHCP
From: Denis Vlasenko (vda_at_port.imtp.ilyichevsk.odessa.ua)
Date: 02/04/05
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To: Shane Hathaway <shane@hathawaymix.org>, Kernel Mailing List <linux-kernel@vger.kernel.org> Date: Fri, 4 Feb 2005 10:06:49 +0200
On Thursday 03 February 2005 06:47, Shane Hathaway wrote:
> The attached patch enhances the kernel's DHCP client support (in
> net/ipv4/ipconfig.c) to set the interface MTU if provided by the DHCP server.
> Without this patch, it's difficult to netboot on a network that uses jumbo
> frames. The patch is based on 2.6.10, but I'll update it to the latest
> testing kernel if that would expedite its inclusion in the kernel.
>
> More background: it's currently difficult to netboot on a jumbo frame network
> because when clients try to mount the root partition, they are still
> configured with a small MTU and therefore reject packets sent by the
> jumbo-frame-enabled NFS server. Linux needs to set the client MTU before
> mounting any NFS shares. Fortunately, the DHCP protocol already supports
> setting the MTU; this patch just integrates that feature into the kernel.
>
> Incidentally, ipconfig.c doesn't appear to do enough bounds checking on byte 1
> of DHCP/BOOTP extension fields (the length field). It looks like a malicious
> DHCP server could mess with kernel memory that way. I could try to fix the
> hole, but maybe someone more experienced with this code would like to verify
> there's a problem first.
Long term solution is to use approptiately configured initramfs or initrd image
and do above mentioned stuff in userspace.
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- Previous message: Tejun Heo: "Re: [PATCH 2.6.11-rc2 04/14] ide_pci: Merges cy82c693.h into cy82c693.c"
- In reply to: Shane Hathaway: "[PATCH] Configure MTU via kernel DHCP"
- Next in thread: Hans-Peter Jansen: "Re: [PATCH] Configure MTU via kernel DHCP"
- Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]
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