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From:   Paul Moore <paul@paul-moore.com>
Date:   Wed, 1 Nov 2023 20:40:49 -0400
Message-ID: <CAHC9VhQHizyP3frH61jQi-8eNeNvg9UcPkvPv6Kk3k7rMsCziQ@mail.gmail.com>
Subject: Re: [PATCH RFC v11 11/19] dm verity: set DM_TARGET_SINGLETON feature flag
To:     Fan Wu <wufan@linux.microsoft.com>, corbet@lwn.net,
        zohar@linux.ibm.com, jmorris@namei.org, serge@hallyn.com,
        tytso@mit.edu, ebiggers@kernel.org, axboe@kernel.dk,
        agk@redhat.com, snitzer@kernel.org, eparis@redhat.com
Cc:     linux-doc@vger.kernel.org, linux-integrity@vger.kernel.org,
        linux-security-module@vger.kernel.org,
        linux-fscrypt@vger.kernel.org, linux-block@vger.kernel.org,
        dm-devel@redhat.com, audit@vger.kernel.org,
        roberto.sassu@huawei.com, linux-kernel@vger.kernel.org
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On Mon, Oct 23, 2023 at 11:52=E2=80=AFPM Paul Moore <paul@paul-moore.com> w=
rote:
> On Oct  4, 2023 Fan Wu <wufan@linux.microsoft.com> wrote:
> >
> > The device-mapper has a flag to mark targets as singleton, which is a
> > required flag for immutable targets. Without this flag, multiple
> > dm-verity targets can be added to a mapped device, which has no
> > practical use cases and will let dm_table_get_immutable_target return
> > NULL. This patch adds the missing flag, restricting only one
> > dm-verity target per mapped device.
> >
> > Signed-off-by: Fan Wu <wufan@linux.microsoft.com>
> > ---
> > v1-v10:
> >   + Not present
> > ---
> >  drivers/md/dm-verity-target.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
>
> This seems reasonable to me and matches with other users of
> DM_TARGET_IMMUTABLE.
>
> Alasdair, Mike, can we get an ACK on this?

A gentle ping with a reminder ...

For reference, the full patchset can be found on lore at the link below:

https://lore.kernel.org/linux-security-module/1696457386-3010-1-git-send-em=
ail-wufan@linux.microsoft.com/

> > diff --git a/drivers/md/dm-verity-target.c b/drivers/md/dm-verity-targe=
t.c
> > index 26adcfea0302..80673b66c194 100644
> > --- a/drivers/md/dm-verity-target.c
> > +++ b/drivers/md/dm-verity-target.c
> > @@ -1503,7 +1503,7 @@ int dm_verity_get_root_digest(struct dm_target *t=
i, u8 **root_digest, unsigned i
> >
> >  static struct target_type verity_target =3D {
> >       .name           =3D "verity",
> > -     .features       =3D DM_TARGET_IMMUTABLE,
> > +     .features       =3D DM_TARGET_SINGLETON | DM_TARGET_IMMUTABLE,
> >       .version        =3D {1, 9, 0},
> >       .module         =3D THIS_MODULE,
> >       .ctr            =3D verity_ctr,
> > --
> > 2.25.1

--=20
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