linux-ext4 - Re: [PATCH 01/34] namespace: take lock_mount

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: <20201102133331.66v4hxtmlnjrucnn@wittgenstein>
Date:   Mon, 2 Nov 2020 14:33:31 +0100
From:   Christian Brauner <christian.brauner@...ntu.com>
To:     Christoph Hellwig <hch@...radead.org>
Cc:     Alexander Viro <viro@...iv.linux.org.uk>,
        linux-fsdevel@...r.kernel.org,
        John Johansen <john.johansen@...onical.com>,
        James Morris <jmorris@...ei.org>,
        Mimi Zohar <zohar@...ux.ibm.com>,
        Dmitry Kasatkin <dmitry.kasatkin@...il.com>,
        Stephen Smalley <stephen.smalley.work@...il.com>,
        Casey Schaufler <casey@...aufler-ca.com>,
        Arnd Bergmann <arnd@...db.de>,
        Andreas Dilger <adilger.kernel@...ger.ca>,
        OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>,
        Geoffrey Thomas <geofft@...reload.com>,
        Mrunal Patel <mpatel@...hat.com>,
        Josh Triplett <josh@...htriplett.org>,
        Andy Lutomirski <luto@...nel.org>,
        Amir Goldstein <amir73il@...il.com>,
        Miklos Szeredi <miklos@...redi.hu>,
        Theodore Tso <tytso@....edu>, Alban Crequy <alban@...volk.io>,
        Tycho Andersen <tycho@...ho.ws>,
        David Howells <dhowells@...hat.com>,
        James Bottomley <James.Bottomley@...senpartnership.com>,
        Jann Horn <jannh@...gle.com>,
        Seth Forshee <seth.forshee@...onical.com>,
        St??phane Graber <stgraber@...ntu.com>,
        Aleksa Sarai <cyphar@...har.com>,
        Lennart Poettering <lennart@...ttering.net>,
        "Eric W. Biederman" <ebiederm@...ssion.com>, smbarber@...omium.org,
        Phil Estes <estesp@...il.com>, Serge Hallyn <serge@...lyn.com>,
        Kees Cook <keescook@...omium.org>,
        Todd Kjos <tkjos@...gle.com>, Jonathan Corbet <corbet@....net>,
        containers@...ts.linux-foundation.org,
        linux-security-module@...r.kernel.org, linux-api@...r.kernel.org,
        linux-ext4@...r.kernel.org, linux-unionfs@...r.kernel.org,
        linux-audit@...hat.com, linux-integrity@...r.kernel.org,
        selinux@...r.kernel.org
Subject: Re: [PATCH 01/34] namespace: take lock_mount_hash() directly when
 changing flags

On Sun, Nov 01, 2020 at 02:41:08PM +0000, Christoph Hellwig wrote:
> > index cebaa3e81794..20ee291a7af4 100644
> > --- a/fs/namespace.c
> > +++ b/fs/namespace.c
> > @@ -463,7 +463,6 @@ static int mnt_make_readonly(struct mount *mnt)
> >  {
> >  	int ret = 0;
> >  
> > -	lock_mount_hash();
> 
> What about adding a lockdep_assert_lock_held in all the functions
> that used to take the lock to document the assumptions?

Good idea and will do. I wanted to do this but then didn't because I
haven't seen widespread use of lockdep assert in fs/namespace.c.

> 
> >  static int __mnt_unmake_readonly(struct mount *mnt)
> >  {
> > -	lock_mount_hash();
> >  	mnt->mnt.mnt_flags &= ~MNT_READONLY;
> > -	unlock_mount_hash();
> >  	return 0;
> 
> This helper is rather pointless now.

Ok, will remove.

> 
> >  static void set_mount_attributes(struct mount *mnt, unsigned int mnt_flags)
> >  {
> > -	lock_mount_hash();
> >  	mnt_flags |= mnt->mnt.mnt_flags & ~MNT_USER_SETTABLE_MASK;
> >  	mnt->mnt.mnt_flags = mnt_flags;
> >  	touch_mnt_namespace(mnt->mnt_ns);
> > -	unlock_mount_hash();
> 
> In linux-next there is an additional notify_mount after the unlock here.

Thanks! I can try rebasing on -next.

> 
> Also while you touch this lock_mount_hash/unlock_mount_hash could be
> moved to namespace.c and maked static now.

Ok, will try to do that.