From: Matthew Wilcox <willy@infradead.org>
To: Ross Zwisler <zwisler@chromium.org>
Cc: Raul Rangel <rrangel@google.com>,
David Howells <dhowells@redhat.com>,
linux-kernel <linux-kernel@vger.kernel.org>,
Mattias Nissler <mnissler@chromium.org>,
Alexander Viro <viro@zeniv.linux.org.uk>,
linux-fsdevel@vger.kernel.org,
Benjamin Gordon <bmgordon@google.com>,
Micah Morton <mortonm@google.com>,
Dmitry Torokhov <dtor@google.com>, Jan Kara <jack@suse.cz>,
Aleksa Sarai <cyphar@cyphar.com>
Subject: Re: [PATCH v5] Add a "nosymfollow" mount option.
Date: Tue, 4 Feb 2020 19:21:10 -0800 [thread overview]
Message-ID: <20200205032110.GR8731@bombadil.infradead.org> (raw)
In-Reply-To: <CAGRrVHyzX4zOpO2nniv42BHOCbyCdPV9U7GE3FVhjzeFonb0bQ@mail.gmail.com>
On Tue, Feb 04, 2020 at 04:49:48PM -0700, Ross Zwisler wrote:
> On Tue, Feb 4, 2020 at 3:11 PM Ross Zwisler <zwisler@chromium.org> wrote:
> > On Tue, Feb 4, 2020 at 2:53 PM Raul Rangel <rrangel@google.com> wrote:
> > > > --- a/include/uapi/linux/mount.h
> > > > +++ b/include/uapi/linux/mount.h
> > > > @@ -34,6 +34,7 @@
> > > > #define MS_I_VERSION (1<<23) /* Update inode I_version field */
> > > > #define MS_STRICTATIME (1<<24) /* Always perform atime updates */
> > > > #define MS_LAZYTIME (1<<25) /* Update the on-disk [acm]times lazily */
> > > > +#define MS_NOSYMFOLLOW (1<<26) /* Do not follow symlinks */
> > > Doesn't this conflict with MS_SUBMOUNT below?
> > > >
> > > > /* These sb flags are internal to the kernel */
> > > > #define MS_SUBMOUNT (1<<26)
> >
> > Yep. Thanks for the catch, v6 on it's way.
>
> It actually looks like most of the flags which are internal to the
> kernel are actually unused (MS_SUBMOUNT, MS_NOREMOTELOCK, MS_NOSEC,
> MS_BORN and MS_ACTIVE). Several are unused completely, and the rest
> are just part of the AA_MS_IGNORE_MASK which masks them off in the
> apparmor LSM, but I'm pretty sure they couldn't have been set anyway.
>
> I'll just take over (1<<26) for MS_NOSYMFOLLOW, and remove the rest in
> a second patch.
>
> If someone thinks these flags are actually used by something and I'm
> just missing it, please let me know.
Afraid you did miss it ...
/*
* sb->s_flags. Note that these mirror the equivalent MS_* flags where
* represented in both.
*/
...
#define SB_SUBMOUNT (1<<26)
It's not entirely clear to me why they need to be the same, but I haven't
been paying close attention to the separation of superblock and mount
flags, so someone else can probably explain the why of it.
next prev parent reply other threads:[~2020-02-05 3:21 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-04 21:50 [PATCH v5] Add a "nosymfollow" mount option Ross Zwisler
2020-02-04 21:52 ` Raul Rangel
2020-02-04 22:11 ` Ross Zwisler
2020-02-04 23:49 ` Ross Zwisler
2020-02-05 3:21 ` Matthew Wilcox [this message]
2020-02-05 3:45 ` Aleksa Sarai
2020-02-06 19:10 ` Ross Zwisler
2020-02-13 15:46 ` Ross Zwisler
2020-02-21 1:21 ` Aleksa Sarai
2020-02-21 18:21 ` Ross Zwisler
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