From: Eric Brower <ebrower@gmail.com>
To: sparclinux@vger.kernel.org
Subject: Re: TUNSETIFF: data not copied back to userspace
Date: Mon, 14 Feb 2005 20:45:27 +0000 [thread overview]
Message-ID: <ec7cefb0502141245151c1cec@mail.gmail.com> (raw)
In-Reply-To: <Pine.LNX.4.61.0502141928510.11663@l01.thnet>
Take a look at the dev_ifsioc() function in ioctl32.c-- it does not
copy the data back to userspace except for SIOCSIFMAP, and judging
from the strict definition of TUNSETIFF it should not be required to
do so.
I think if this is functionality that is required (I see no TUNGETIFF,
but I don't play with this stuff enough to know) the directionality of
the ioctl definition should be _IOWR rather than _IOR; in any case,
the "argument" field should not be "int" but rather "struct ifreq*"
in if_tun.h. Likely, neither will change for historical reasons....
E
On Mon, 14 Feb 2005 20:41:33 +0100 (CET), Michael Tautschnig
<michael.tautschnig@zt-consulting.com> wrote:
> Hello!
>
> Thanks for the information regarding userland/kernelspace - I think I
> understood ...
>
> The reason of my question were problems using the tun/tap interface - I've
> got an application (namely l2tpns) demanding the ifreq-structure being
> copied back to userspace - which AFAIK doesn't happen in case of the
> TUNSETIFF-ioctl. Is this a bug or are there any reasons why this shouldn't
> happen in dev_ifsioc ?
>
> Thanks,
> Michael
>
> -
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--
E
next prev parent reply other threads:[~2005-02-14 20:45 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-02-14 19:41 TUNSETIFF: data not copied back to userspace Michael Tautschnig
2005-02-14 20:45 ` Eric Brower [this message]
2005-02-14 22:59 ` Michael Tautschnig
2005-02-14 23:02 ` David S. Miller
2005-02-14 23:18 ` Michael Tautschnig
2005-02-14 23:30 ` David S. Miller
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