From: ebiederm@xmission.com (Eric W. Biederman)
To: Alexey Gladkov <gladkov.alexey@gmail.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
Kernel Hardening <kernel-hardening@lists.openwall.com>,
Linux API <linux-api@vger.kernel.org>,
Linux FS Devel <linux-fsdevel@vger.kernel.org>,
Linux Security Module <linux-security-module@vger.kernel.org>,
Akinobu Mita <akinobu.mita@gmail.com>,
Alexander Viro <viro@zeniv.linux.org.uk>,
Alexey Dobriyan <adobriyan@gmail.com>,
Andrew Morton <akpm@linux-foundation.org>,
Andy Lutomirski <luto@kernel.org>,
Daniel Micay <danielmicay@gmail.com>,
Djalal Harouni <tixxdz@gmail.com>,
"Dmitry V . Levin" <ldv@altlinux.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Ingo Molnar <mingo@kernel.org>,
"J . Bruce Fields" <bfields@fieldses.org>,
Jeff Layton <jlayton@poochiereds.net>,
Jonathan Corbet <corbet@lwn.net>,
Kees Cook <keescook@chromium.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Oleg Nesterov <oleg@redhat.com>,
David Howells <dhowells@redhat.com>
Subject: Re: [PATCH v10 8/9] proc: use human-readable values for hidehid
Date: Thu, 02 Apr 2020 12:04:44 -0500 [thread overview]
Message-ID: <87r1x5iztf.fsf@x220.int.ebiederm.org> (raw)
In-Reply-To: <20200402165156.4mzenof4upvtd3lv@comp-core-i7-2640m-0182e6> (Alexey Gladkov's message of "Thu, 2 Apr 2020 18:51:56 +0200")
Alexey Gladkov <gladkov.alexey@gmail.com> writes:
> On Thu, Apr 02, 2020 at 11:05:21AM -0500, Eric W. Biederman wrote:
>> Alexey Gladkov <gladkov.alexey@gmail.com> writes:
>>
>> > The hidepid parameter values are becoming more and more and it becomes
>> > difficult to remember what each new magic number means.
>>
>> In principle I like this change. In practice I think you have just
>> broken ABI compatiblity with the new mount ABI.
>>
>> In particular the following line seems broken.
>>
>> > diff --git a/fs/proc/root.c b/fs/proc/root.c
>> > index dbcd96f07c7a..ba782d6e6197 100644
>> > --- a/fs/proc/root.c
>> > +++ b/fs/proc/root.c
>> > @@ -45,7 +45,7 @@ enum proc_param {
>> >
>> > static const struct fs_parameter_spec proc_fs_parameters[] = {
>> > fsparam_u32("gid", Opt_gid),
>> > - fsparam_u32("hidepid", Opt_hidepid),
>> > + fsparam_string("hidepid", Opt_hidepid),
>> > fsparam_string("subset", Opt_subset),
>> > {}
>> > };
>>
>> As I read fs_parser.c fs_param_is_u32 handles string inputs and turns them
>> into numbers, and it handles binary numbers. However fs_param_is_string
>> appears to only handle strings. It appears to have not capacity to turn
>> raw binary numbers into strings.
>
> I use result only with hidepid_u32_spec and nobody modifies param->string.
> I do not use internal functions here.
>
> I don’t follow how a raw number can get here ?
I may be wrong but last I looked you can input raw numbers using the new
mount api. I have most of the details paged out at the moment,
but I believe that is why when you set a parameter in the new mount api
it takes a type.
>> So I think we probably need to fix fs_param_is_string to raw binary
>> numbers before we can safely make this change to fs/proc/root.c
>>
>> David am I reading the fs_parser.c code correctly? If I am are you ok
>> with a change like the above?
Eric
next prev parent reply other threads:[~2020-04-02 17:07 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-27 17:23 [PATCH v10 0/9] proc: modernize proc to support multiple private instances Alexey Gladkov
2020-03-27 17:23 ` [PATCH v10 1/9] proc: rename struct proc_fs_info to proc_fs_opts Alexey Gladkov
2020-03-27 17:23 ` [PATCH v10 2/9] proc: allow to mount many instances of proc in one pid namespace Alexey Gladkov
2020-04-02 15:31 ` Eric W. Biederman
2020-04-02 16:32 ` Alexey Gladkov
2020-03-27 17:23 ` [PATCH v10 3/9] proc: move hide_pid, pid_gid from pid_namespace to proc_fs_info Alexey Gladkov
2020-03-27 17:23 ` [PATCH v10 4/9] proc: instantiate only pids that we can ptrace on 'hidepid=4' mount option Alexey Gladkov
2020-03-28 20:40 ` Kees Cook
2020-03-28 21:23 ` Alexey Gladkov
2020-03-27 17:23 ` [PATCH v10 5/9] proc: add option to mount only a pids subset Alexey Gladkov
2020-03-27 17:23 ` [PATCH v10 6/9] docs: proc: add documentation for "hidepid=4" and "subset=pid" options and new mount behavior Alexey Gladkov
2020-03-27 17:23 ` [PATCH v10 7/9] proc: move hidepid values to uapi as they are user interface to mount Alexey Gladkov
2020-03-28 20:41 ` Kees Cook
2020-03-28 21:25 ` Alexey Gladkov
2020-03-28 21:53 ` Kees Cook
2020-03-28 23:00 ` Alexey Gladkov
2020-03-29 3:17 ` Kees Cook
2020-04-02 16:58 ` Eric W. Biederman
2020-04-03 23:59 ` Kees Cook
2020-03-27 17:23 ` [PATCH v10 8/9] proc: use human-readable values for hidehid Alexey Gladkov
2020-03-28 20:28 ` Kees Cook
2020-03-28 21:14 ` Alexey Gladkov
2020-03-28 21:52 ` Kees Cook
2020-03-28 22:54 ` Alexey Gladkov
2020-03-30 11:12 ` [PATCH v11 " Alexey Gladkov
2020-03-30 18:33 ` Kees Cook
2020-04-02 16:11 ` Jann Horn
2020-04-02 16:05 ` [PATCH v10 " Eric W. Biederman
2020-04-02 16:51 ` Alexey Gladkov
2020-04-02 17:04 ` Eric W. Biederman [this message]
2020-04-09 14:32 ` Alexey Gladkov
2020-03-27 17:23 ` [PATCH v10 9/9] proc: use named enums for better readability Alexey Gladkov
2020-04-02 17:00 ` [PATCH v10 0/9] proc: modernize proc to support multiple private instances Eric W. Biederman
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