Reviewed-by: Marcelo Henrique Cerri Tested-by: Marcelo Henrique Cerri On Sun, Jul 12, 2020 at 06:40:20PM +0200, Stephan Müller wrote: > SP800-56A rev3 section 5.7.1.1 step 2 mandates that the validity of the > calculated shared secret is verified before the data is returned to the > caller. This patch adds the validation check. > > Signed-off-by: Stephan Mueller > --- > crypto/dh.c | 29 +++++++++++++++++++++++++++++ > 1 file changed, 29 insertions(+) > > diff --git a/crypto/dh.c b/crypto/dh.c > index 566f624a2de2..f84fd50ec79b 100644 > --- a/crypto/dh.c > +++ b/crypto/dh.c > @@ -9,6 +9,7 @@ > #include > #include > #include > +#include > #include > > struct dh_ctx { > @@ -179,6 +180,34 @@ static int dh_compute_value(struct kpp_request *req) > if (ret) > goto err_free_base; > > + /* SP800-56A rev3 5.7.1.1 check: Validation of shared secret */ > + if (fips_enabled && req->src) { > + MPI pone; > + > + /* z <= 1 */ > + if (mpi_cmp_ui(val, 1) < 1) { > + ret = -EBADMSG; > + goto err_free_base; > + } > + > + /* z == p - 1 */ > + pone = mpi_alloc(0); > + > + if (!pone) { > + ret = -ENOMEM; > + goto err_free_base; > + } > + > + ret = mpi_sub_ui(pone, ctx->p, 1); > + if (!ret && !mpi_cmp(pone, val)) > + ret = -EBADMSG; > + > + mpi_free(pone); > + > + if (ret) > + goto err_free_base; > + } > + > ret = mpi_write_to_sgl(val, req->dst, req->dst_len, &sign); > if (ret) > goto err_free_base; > -- > 2.26.2 > > > > -- Regards, Marcelo