On Thu, Feb 27, 2025 at 01:33:38PM +0100, Ard Biesheuvel wrote: > From: Ard Biesheuvel <ardb@xxxxxxxxxx> > > The ChaCha20-Poly1305 library code uses the sg_miter API to process > input presented via scatterlists, except for the special case where the > digest buffer is not covered entirely by the same scatterlist entry as > the last byte of input. In that case, it uses scatterwalk_map_and_copy() > to access the memory in the input scatterlist where the digest is stored. > > This results in a dependency on crypto/scatterwalk.c and therefore on > CONFIG_CRYPTO_ALGAPI, which is unnecessary, as the sg_miter API already > provides this functionality via sg_copy_to_buffer(). So use that > instead, and drop the CRYPTO_ALGAPI dependency. > > Reported-by: Arnd Bergmann <arnd@xxxxxxxx> > Signed-off-by: Ard Biesheuvel <ardb@xxxxxxxxxx> Acked-by: Eric Biggers <ebiggers@xxxxxxxxxx> There's indeed redundancy between crypto/scatterwalk.c and lib/scatterlist.c, and switching to lib/scatterlist.c makes sense here. I do think that the implementation in crypto/scatterwalk.c is slightly better (including being slightly more efficient), especially if my patchset https://lore.kernel.org/linux-crypto/20250219182341.43961-1-ebiggers@xxxxxxxxxx/ gets applied. It would be a good future project to unify them into a single version, which of course would not depend on CRYPTO. But for now, just using the one that already does not depend on CRYPTO here is the right choice. > diff --git a/lib/crypto/Kconfig b/lib/crypto/Kconfig > index b01253cac70a..a759e6f6a939 100644 > --- a/lib/crypto/Kconfig > +++ b/lib/crypto/Kconfig > @@ -135,7 +135,6 @@ config CRYPTO_LIB_CHACHA20POLY1305 > depends on CRYPTO > select CRYPTO_LIB_CHACHA > select CRYPTO_LIB_POLY1305 > - select CRYPTO_ALGAPI As Arnd mentioned, 'depends on CRYPTO' should be dropped. > diff --git a/lib/crypto/chacha20poly1305.c b/lib/crypto/chacha20poly1305.c > index a839c0ac60b2..280a4925dd17 100644 > --- a/lib/crypto/chacha20poly1305.c > +++ b/lib/crypto/chacha20poly1305.c > @@ -11,7 +11,6 @@ > #include <crypto/algapi.h> > #include <crypto/chacha20poly1305.h> > #include <crypto/chacha.h> > #include <crypto/poly1305.h> > -#include <crypto/scatterwalk.h> Also replace the include of <crypto/algapi.h> with <crypto/utils.h>, for consistency with the removal of the selection of CRYPTO_ALGAPI. - Eric
