linux-ext4 - Re: [PATCH] fsverity: don't check builtin signatures when require

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Message-ID: <Y5zd6ucBc20CV7Le@sol.localdomain>
Date:   Fri, 16 Dec 2022 13:06:50 -0800
From:   Eric Biggers <ebiggers@...nel.org>
To:     Luca Boccassi <bluca@...ian.org>
Cc:     linux-fscrypt@...r.kernel.org, linux-ext4@...r.kernel.org,
        linux-f2fs-devel@...ts.sourceforge.net,
        linux-btrfs@...r.kernel.org, linux-integrity@...r.kernel.org,
        stable@...r.kernel.org
Subject: Re: [PATCH] fsverity: don't check builtin signatures when
 require_signatures=0

On Thu, Dec 08, 2022 at 08:42:56PM +0000, Luca Boccassi wrote:
> On Thu, 8 Dec 2022 at 03:35, Eric Biggers <ebiggers@...nel.org> wrote:
> >
> > From: Eric Biggers <ebiggers@...gle.com>
> >
> > An issue that arises when migrating from builtin signatures to userspace
> > signatures is that existing files that have builtin signatures cannot be
> > opened unless either CONFIG_FS_VERITY_BUILTIN_SIGNATURES is disabled or
> > the signing certificate is left in the .fs-verity keyring.
> >
> > Since builtin signatures provide no security benefit when
> > fs.verity.require_signatures=0 anyway, let's just skip the signature
> > verification in this case.
> >
> > Fixes: 432434c9f8e1 ("fs-verity: support builtin file signatures")
> > Cc: <stable@...r.kernel.org> # v5.4+
> > Signed-off-by: Eric Biggers <ebiggers@...gle.com>
> > ---
> >  fs/verity/signature.c | 18 ++++++++++++++++--
> >  1 file changed, 16 insertions(+), 2 deletions(-)
> 
> Acked-by: Luca Boccassi <bluca@...ian.org>

So if I can't apply
https://lore.kernel.org/linux-fscrypt/20221208033548.122704-1-ebiggers@kernel.org
("fsverity: mark builtin signatures as deprecated") due to IPE, wouldn't I not
be able to apply this patch either?  Surely IPE isn't depending on
fs.verity.require_signatures=1, given that it enforces the policy itself?

- Eric