From: David Laight <David.Laight@ACULAB.COM>
To: dccp@vger.kernel.org
Subject: RE: [PATCH 03/26] bpfilter: reject kernel addresses
Date: Thu, 23 Jul 2020 14:42:11 +0000 [thread overview]
Message-ID: <c3dc5b4d84e64230bb6ca8df7bb70705@AcuMS.aculab.com> (raw)
In-Reply-To: <20200723060908.50081-4-hch@lst.de>
From: Christoph Hellwig
> Sent: 23 July 2020 07:09
>
> The bpfilter user mode helper processes the optval address using
> process_vm_readv. Don't send it kernel addresses fed under
> set_fs(KERNEL_DS) as that won't work.
What sort of operations is the bpf filter doing on the sockopt buffers?
Any attempts to reject some requests can be thwarted by a second
application thread modifying the buffer after the bpf filter has
checked that it allowed.
You can't do security by reading a user buffer twice.
David
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Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)
next prev parent reply other threads:[~2020-07-23 14:42 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-23 6:08 [PATCH 03/26] bpfilter: reject kernel addresses Christoph Hellwig
2020-07-23 14:42 ` David Laight [this message]
2020-07-23 14:44 ` 'Christoph Hellwig'
2020-07-23 14:56 ` David Laight
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