Re: [PATCH net] mptcp: select CRYPTO_LIB_UTILS instead of CRYPTO

[Mat Martineau <martineau@kernel.org>]

On Wed, 3 Dec 2025, Eric Biggers wrote:

> Since the only crypto functions used by the mptcp code are the SHA-256
> library functions and crypto_memneq(), select only the options needed
> for those: CRYPTO_LIB_SHA256 and CRYPTO_LIB_UTILS.
>
> Previously, CRYPTO was selected instead of CRYPTO_LIB_UTILS.  That does
> pull in CRYPTO_LIB_UTILS as well, but it's unnecessarily broad.
>
> Years ago, the CRYPTO_LIB_* options were visible only when CRYPTO.  That
> may be another reason why CRYPTO is selected here.  However, that was
> fixed years ago, and the libraries can now be selected directly.
>
> Signed-off-by: Eric Biggers <ebiggers@kernel.org>
> ---
> net/mptcp/Kconfig | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)

Thanks Eric!

Yes, this is a case of our Kconfig predating CRYPTO_LIB_UTILS. Appreciate 
the fix.

Netdev maintainers, it's fine to apply this directly to the -net tree.

Reviewed-by: Mat Martineau <martineau@kernel.org>


>
> diff --git a/net/mptcp/Kconfig b/net/mptcp/Kconfig
> index 20328920f6ed..be71fc9b4638 100644
> --- a/net/mptcp/Kconfig
> +++ b/net/mptcp/Kconfig
> @@ -2,11 +2,11 @@
> config MPTCP
> 	bool "MPTCP: Multipath TCP"
> 	depends on INET
> 	select SKB_EXTENSIONS
> 	select CRYPTO_LIB_SHA256
> -	select CRYPTO
> +	select CRYPTO_LIB_UTILS
> 	help
> 	  Multipath TCP (MPTCP) connections send and receive data over multiple
> 	  subflows in order to utilize multiple network paths. Each subflow
> 	  uses the TCP protocol, and TCP options carry header information for
> 	  MPTCP.
>
> base-commit: b2c27842ba853508b0da00187a7508eb3a96c8f7
> -- 
> 2.52.0
>
>