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

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Message-ID: <ac6e33b8-ec1f-494a-874f-9a16d3316fce@linux.microsoft.com>
Date: Fri, 16 Aug 2024 12:11:12 -0700
From: Fan Wu <wufan@...ux.microsoft.com>
To: Mikulas Patocka <mpatocka@...hat.com>, 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 8/16/2024 6:35 AM, Mikulas Patocka wrote:
> 
> 
> 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>
>

Thank you for reviewing the patch and for your suggestion.

>>>>
>>>> +#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

Sure, I can make these two fields together.

-Fan