linux-kernel - Re: block: sleeping in atomic warnings

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: <CAHk-=whdCBPH0WYK-D5q60u1hvwTabKETWTsEKYXNRgx4tGOPA@mail.gmail.com>
Date:   Tue, 7 Feb 2023 11:49:15 -0800
From:   Linus Torvalds <torvalds@...ux-foundation.org>
To:     Eric Biggers <ebiggers@...nel.org>
Cc:     Dan Carpenter <error27@...il.com>, linux-block@...r.kernel.org,
        Julia Lawall <julia.lawall@...ia.fr>,
        Luis Chamberlain <mcgrof@...nel.org>,
        Hongchen Zhang <zhanghongchen@...ngson.cn>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Andrew Morton <akpm@...ux-foundation.org>,
        "Christian Brauner (Microsoft)" <brauner@...nel.org>,
        David Howells <dhowells@...hat.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Eric Dumazet <edumazet@...gle.com>,
        "Fabio M. De Francesco" <fmdefrancesco@...il.com>,
        Christophe JAILLET <christophe.jaillet@...adoo.fr>,
        linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
        maobibo <maobibo@...ngson.cn>,
        Matthew Wilcox <willy@...radead.org>,
        Sedat Dilek <sedat.dilek@...il.com>
Subject: Re: block: sleeping in atomic warnings

On Tue, Feb 7, 2023 at 11:35 AM Eric Biggers <ebiggers@...nel.org> wrote:
>
> The point of the "test_dummy_encryption" mount option is that you can just add
> it to the mount options and run existing tests, such as a full run of xfstests,
> and test all the encrypted I/O paths that way.  Which is extremely useful; it
> wouldn't really be possible to properly test the encryption feature without it.

Yes, I see how useful that is, but:

> Now, it's possible that "the kernel automatically adds the key for
> test_dummy_encryption" could be implemented a bit differently.  It maybe could
> be done at the last minute, when the key is being looked for due to a user
> filesystem operation, instead of during the mount itself.

Yeah, that sounds like it would be the right solution, and get rid of
the fscrypt_destroy_keyring() case in __put_super().

Hmm.

I guess the filesystem only ever sees the '->get_tree()' call, and
then never gets any "this mount succeeded" callback.

And we do have at least that

        error = security_sb_set_mnt_opts(sb, fc->security, 0, NULL);
        if (unlikely(error)) {
                fc_drop_locked(fc);
                return error;
        }

error case that does fc_drop_locked() -> deactivate_locked_super() ->
put_super().

Hmm. It does get "kill_sb()", if that happens, so if

 (a) the filesystem registers the keys late only in the success case

and

 (b) ->kill_sb() does the fscrypt_destroy_keyring(s)

then I *think* everything would be fine, and put_super() doesn't need to do it.

Or am I missing some case?

                Linus