From: Luis Chamberlain <mcgrof@kernel.org>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Michal Hocko <mhocko@kernel.org>,
Vlastimil Babka <vbabka@suse.cz>,
Kees Cook <keescook@chromium.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>,
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: Mon, 30 Mar 2020 22:09:39 +0000 [thread overview]
Message-ID: <20200330220939.GW11244@42.do-not-panic.com> (raw)
In-Reply-To: <87bloj2skm.fsf@x220.int.ebiederm.org>
On Thu, Mar 26, 2020 at 07:45:13AM -0500, Eric W. Biederman wrote:
> > On Wed 25-03-20 17:20:40, Eric W. Biederman wrote:
> plus I want to get very far away from the incorrect idea that you
> can have sysctls without compiling in proc support. That is not how
> the code works, that is not how the code is tested.
Agreed.
> It is also worth pointing out that:
>
> proc_mnt = kern_mount(proc_fs_type);
> for_each_sysctl_cmdline() {
> ...
> file = file_open_root(proc_mnt->mnt_root, proc_mnt, sysctl_path, O_WRONLY, 0);
> kernel_write(file, value, value_len);
> }
> kern_umount(proc_mnt);
>
> Is not an unreasonable implementation.
This:
> There are problems with a persistent mount of proc in that it forces
> userspace not to use any proc mount options. But a temporary mount of
> proc to deal with command line options is not at all unreasonable.
> Plus it looks like we can have kern_write do all of the kernel/user
> buffer silliness.
Is a bit of tribal knowledge worth documenting for the approach taken
forward. Vlastimil can you add a little comment mentioning some of this
logic?
Luis
next prev parent reply other threads:[~2020-03-30 22:09 UTC|newest]
Thread overview: 18+ 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 22:54 ` Kees Cook
2020-03-26 6:58 ` Michal Hocko
2020-03-26 7:21 ` Kees Cook
2020-03-26 12:45 ` Eric W. Biederman
2020-03-30 22:09 ` Luis Chamberlain [this message]
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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