From: Kees Cook <keescook@chromium.org>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Vlastimil Babka <vbabka@suse.cz>,
Luis Chamberlain <mcgrof@kernel.org>,
Iurii Zaikin <yzaikin@google.com>,
linux-kernel@vger.kernel.org, linux-api@vger.kernel.org,
linux-mm@kvack.org, Ivan Teterevkov <ivan.teterevkov@nutanix.com>,
Michal Hocko <mhocko@kernel.org>,
David Rientjes <rientjes@google.com>,
Matthew Wilcox <willy@infradead.org>,
"Guilherme G . Piccoli" <gpiccoli@canonical.com>
Subject: Re: [RFC v2 1/2] kernel/sysctl: support setting sysctl parameters from kernel command line
Date: Wed, 25 Mar 2020 15:54:09 -0700 [thread overview]
Message-ID: <202003251544.7ECB392A7@keescook> (raw)
In-Reply-To: <874kuc5b5z.fsf@x220.int.ebiederm.org>
On Wed, Mar 25, 2020 at 05:20:40PM -0500, Eric W. Biederman wrote:
> Hmm. There is a big gotcha in here and I think it should be mentioned.
> This code only works because no one has done set_fs(KERNEL_DS). Which
> means this only works with strings that are kernel addresses essentially
> by mistake. A big fat comment documenting why it is safe to pass in
> kernel addresses to a function that takes a "char __user*" pointer
> would be very good.
Yeah, I was going to mention this too just now as I went looking through
one of the handlers and was reminded that the args are marked __user. :P
I suspect we might need to add some __force __user markings or something
(with a comment as you say above), to keep sparse from going crazy. :)
--
Kees Cook
next prev parent reply other threads:[~2020-03-25 22:54 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-25 12:03 [RFC v2 1/2] kernel/sysctl: support setting sysctl parameters from kernel command line Vlastimil Babka
2020-03-25 12:03 ` [RFC v2 2/2] kernel/sysctl: support handling command line aliases Vlastimil Babka
2020-03-25 14:29 ` Michal Hocko
2020-03-25 14:36 ` Vlastimil Babka
2020-03-25 14:44 ` Michal Hocko
2020-03-25 22:42 ` Kees Cook
2020-03-29 15:00 ` Arvind Sankar
2020-03-25 21:21 ` [RFC v2 1/2] kernel/sysctl: support setting sysctl parameters from kernel command line Kees Cook
2020-03-26 9:30 ` Vlastimil Babka
2020-03-25 22:20 ` Eric W. Biederman
2020-03-25 22:20 ` Eric W. Biederman
2020-03-25 22:54 ` Kees Cook [this message]
2020-03-26 6:58 ` Michal Hocko
2020-03-26 7:21 ` Kees Cook
2020-03-26 12:45 ` Eric W. Biederman
2020-03-26 12:45 ` Eric W. Biederman
2020-03-30 22:09 ` Luis Chamberlain
2020-03-26 13:30 ` Christian Brauner
2020-03-26 13:39 ` Michal Hocko
2020-03-26 13:29 ` Vlastimil Babka
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