linux-kernel - Re: [GIT PULL] NFSD changes for v6.18

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Message-ID: <b97cea29-4ab7-4fb6-85ba-83f9830e524f@kernel.org>
Date: Thu, 16 Oct 2025 11:04:24 -0400
From: Chuck Lever <cel@...nel.org>
To: Geert Uytterhoeven <geert@...ux-m68k.org>,
 Jeff Layton <jlayton@...nel.org>
Cc: Eric Biggers <ebiggers@...nel.org>, Trond Myklebust <trondmy@...nel.org>,
 Linus Torvalds <torvalds@...ux-foundation.org>,
 linux-kernel@...r.kernel.org, linux-nfs@...r.kernel.org
Subject: Re: [GIT PULL] NFSD changes for v6.18

On 10/16/25 10:36 AM, Geert Uytterhoeven wrote:
> Hi Jeff,
> 
> On Thu, 16 Oct 2025 at 16:31, Jeff Layton <jlayton@...nel.org> wrote:
>> On Mon, 2025-10-13 at 15:37 -0400, Chuck Lever wrote:
>>> On 10/13/25 3:21 PM, Eric Biggers wrote:
>>>> On Mon, Oct 13, 2025 at 12:15:52PM +0200, Geert Uytterhoeven wrote:
>>>>> Hi Chuck, Eric,
>>>>>
>>>>> On Wed, 8 Oct 2025 at 00:05, Chuck Lever <cel@...nel.org> wrote:
>>>>>> Eric Biggers (4):
>>>>>>       SUNRPC: Make RPCSEC_GSS_KRB5 select CRYPTO instead of depending on it
>>>>>
>>>>> This is now commit d8e97cc476e33037 ("SUNRPC: Make RPCSEC_GSS_KRB5
>>>>> select CRYPTO instead of depending on it") in v6.18-rc1.
>>>>> As RPCSEC_GSS_KRB5 defaults to "y", CRYPTO is now auto-enabled in
>>>>> defconfigs that didn't enable it before.
>>>>
>>>> Now the config is:
>>>>
>>>>     config RPCSEC_GSS_KRB5
>>>>         tristate "Secure RPC: Kerberos V mechanism"
>>>>         depends on SUNRPC
>>>>         default y
>>>>         select SUNRPC_GSS
>>>>         select CRYPTO
>>>>         select CRYPTO_SKCIPHER
>>>>         select CRYPTO_HASH
>>>>
>>>> Perhaps the 'default y' should be removed?
>>>>
>>>> Chuck, do you know why it's there?
>>> The "default y" was added by 2010 commit df486a25900f ("NFS: Fix the
>>> selection of security flavours in Kconfig"), then modified again by
>>> commit e3b2854faabd ("SUNRPC: Fix the SUNRPC Kerberos V RPCSEC_GSS
>>> module dependencies") in 2011.
>>>
>>> Copying Trond, the author of both of those patches.
>>
>> Looking at this a bit closer, maybe a patch like this is what we want?
>> This should make it so that we only enable RPCSEC_GSS_KRB5 if CRYPTO is
>> already enabled:
>>
>> diff --git a/net/sunrpc/Kconfig b/net/sunrpc/Kconfig
>> index 984e0cf9bf8a..d433626c7917 100644
>> --- a/net/sunrpc/Kconfig
>> +++ b/net/sunrpc/Kconfig
>> @@ -19,9 +19,8 @@ config SUNRPC_SWAP
>>  config RPCSEC_GSS_KRB5
>>         tristate "Secure RPC: Kerberos V mechanism"
>>         depends on SUNRPC
>> -       default y
>> +       default y if CRYPTO
> 
> This merely controls the default, the user can still override it.
> Implementing your suggestion above would mean re-adding "depends on
> CRYPTO", i.e. reverting commit d8e97cc476e33037.
> 
>>         select SUNRPC_GSS
>> -       select CRYPTO
>>         select CRYPTO_SKCIPHER
>>         select CRYPTO_HASH
>>         help
> 
> Gr{oetje,eeting}s,
> 
>                         Geert
> 

The graph of dependencies and selects between NFS, NFSD, and SUNRPC is
brittle, unfortunately. I suggest reverting d8e97cc476e33037 for now
while a proper solution is worked out and then tested.


-- 
Chuck Lever