linux-kernel - Re: [PATCH v20 12/20] dm verity: expose root hash digest and signature data to LSMs

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Message-ID: <88695db-efc0-6cc6-13ee-fd7c2abe61c@redhat.com>
Date: Fri, 16 Aug 2024 15:35:01 +0200 (CEST)
From: Mikulas Patocka <mpatocka@...hat.com>
To: Paul Moore <paul@...l-moore.com>
cc: Mike Snitzer <snitzer@...nel.org>, Alasdair Kergon <agk@...hat.com>, 
    linux-doc@...r.kernel.org, linux-integrity@...r.kernel.org, 
    linux-security-module@...r.kernel.org, fsverity@...ts.linux.dev, 
    linux-block@...r.kernel.org, dm-devel@...ts.linux.dev, 
    audit@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v20 12/20] dm verity: expose root hash digest and signature
 data to LSMs



On Thu, 15 Aug 2024, Paul Moore wrote:

> On Thu, Aug 8, 2024 at 6:38 PM Fan Wu <wufan@...ux.microsoft.com> wrote:
> >
> > Hi Mikulas,
> >
> > I hope you’re doing well. I wanted to thank you again for your thorough
> > review for the last version. I’ve since made some minor updates for this
> > version, including adding more comments and refactoring the way the hash
> > algorithm name is obtained due to recent changes in dm-verity.
> >
> > Would you mind if we keep the Review-by tag on the latest version since
> > the changes are minor? Your feedback is greatly valued, and I’d
> > appreciate it if you could take a quick look when you have a moment.
> 
> To add a bit more to this, this patchset now looks like it is in a
> state where we would like to merge it into the LSM tree for the
> upcoming merge window, but I would really like to make sure that the
> device-mapper folks are okay with these changes; an
> Acked-by/Reviewed-by on this patch would be appreciated, assuming you
> are still okay with this patch.
> 
> For those who may be missing the context, the full patchset can be
> found on lore at the link below:
> 
> https://lore.kernel.org/linux-security-module/1722665314-21156-1-git-send-email-wufan@linux.microsoft.com

Hi

I'm not an expert in Linux security subsystems. I skimmed through the 
dm-verity patch, didn't find anything wrong with it, so you can add

Reviewed-by: Mikulas Patocka <mpatocka@...hat.com>

> > >
> > > +#ifdef CONFIG_SECURITY
> > > +     u8 *root_digest_sig;    /* signature of the root digest */
> > > +#endif /* CONFIG_SECURITY */
> > >       unsigned int salt_size;
> > >       sector_t data_start;    /* data offset in 512-byte sectors */
> > >       sector_t hash_start;    /* hash start in blocks */
> > > @@ -58,6 +61,9 @@ struct dm_verity {
> > >       bool hash_failed:1;     /* set if hash of any block failed */
> > >       bool use_bh_wq:1;       /* try to verify in BH wq before normal work-queue */
> > >       unsigned int digest_size;       /* digest size for the current hash algorithm */
> > > +#ifdef CONFIG_SECURITY
> > > +     unsigned int sig_size;  /* root digest signature size */
> > > +#endif /* CONFIG_SECURITY */
> > >       unsigned int hash_reqsize; /* the size of temporary space for crypto */
> > >       enum verity_mode mode;  /* mode for handling verification errors */
> > >       unsigned int corrupted_errs;/* Number of errors for corrupted blocks */

Just nit-picking: I would move "unsigned int sig_size" up, after "u8 
*root_digest_sig" entry.

Mikulas