linux-kernel - Re: debugfs & vfs file permission issue?

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: <8bd0f97a0901052154w213f9a03oafdd07645b1b7dc7@mail.gmail.com>
Date:	Tue, 6 Jan 2009 00:54:58 -0500
From:	"Mike Frysinger" <vapier.adi@...il.com>
To:	"Greg KH" <gregkh@...e.de>
Cc:	"Robin Getz" <rgetz@...ckfin.uclinux.org>, viro@...iv.linux.org.uk,
	linux-kernel@...r.kernel.org
Subject: Re: debugfs & vfs file permission issue?

On Tue, Jan 6, 2009 at 00:48, Greg KH wrote:
> On Mon, Jan 05, 2009 at 09:57:07PM -0500, Robin Getz wrote:
>> On 2.6.28-rc2, If I create a debugfs file with
>>
>>     debugfs_create_x16("SPORT1_TX", 0200 , parent, 0xFFC00910);
>
> Um, are you are passing in a pointer to a known memory location
> properly?  Why would it be ok for the kernel to directly read that
> location?

it's a nommu system and the 0xffc00000+ addresses are always available

>> Although the file shows up as write only (no read):
>>
>> root:/> ls -l /sys/kernel/debug/blackfin/SPORT/SPORT1_TX
>> --w-------    1 root     root            0 Jan  1
>> 2007 /sys/kernel/debug/blackfin/SPORT/SPORT1_TX
>>
>> root:/> cat /sys/kernel/debug/blackfin/SPORT/SPORT1_TX
>>
>> Still works - and causes the read to occur, which crashes :(
>
> You're root, you can do anything :)

any thoughts on how to declare debugfs files that are read or write
only ?  we'll have to add new helper functions or have it be a
parameter or declare our own debugfs file ?
-mike
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/