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From: "Stephan Müller" <smueller@chronox.de>
To: herbert@gondor.apana.org.au
Cc: linux-crypto@vger.kernel.org,
	Marcelo Cerri <marcelo.cerri@canonical.com>,
	Tianjia Zhang <tianjia.zhang@linux.alibaba.com>,
	ard.biesheuvel@linaro.org, nhorman@redhat.com, simo@redhat.com
Subject: [PATCH v2 3/5] crypto: DH - check validity of Z before export
Date: Sun, 12 Jul 2020 18:40:20 +0200
Message-ID: <2134009.irdbgypaU6@positron.chronox.de> (raw)
In-Reply-To: <5722559.lOV4Wx5bFT@positron.chronox.de>

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 <smueller@chronox.de>
---
 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 <crypto/internal/kpp.h>
 #include <crypto/kpp.h>
 #include <crypto/dh.h>
+#include <linux/fips.h>
 #include <linux/mpi.h>
 
 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





  parent reply index

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-10 10:09 [PATCH 0/3] DH: SP800-56A rev 3 compliant shared secret Stephan Müller
2020-07-10 10:10 ` [PATCH 1/3] crypto: ECDH - check validity of Z before export Stephan Müller
2020-07-10 10:10 ` [PATCH 2/3] lib/mpi: Add mpi_sub_ui() Stephan Müller
2020-07-10 14:42   ` Ard Biesheuvel
2020-07-10 15:10     ` Stephan Mueller
2020-07-10 10:15 ` [PATCH 3/3] crypto: DH - check validity of Z before export Stephan Müller
2020-07-12 16:38 ` [PATCH v2 0/5] DH: SP800-56A rev 3 compliant validation checks Stephan Müller
2020-07-12 16:39   ` [PATCH v2 1/5] crypto: ECDH - check validity of Z before export Stephan Müller
2020-07-12 18:02     ` Vitaly Chikunov
2020-07-15 13:17     ` Marcelo Henrique Cerri
2020-07-12 16:39   ` [PATCH v2 2/5] lib/mpi: Add mpi_sub_ui() Stephan Müller
2020-07-16  7:30     ` Herbert Xu
2020-07-16  8:41       ` Ard Biesheuvel
2020-07-16 12:50         ` Marcelo Henrique Cerri
2020-07-16 13:09           ` Ard Biesheuvel
2020-07-16 13:41             ` Marcelo Henrique Cerri
2020-07-16 13:53               ` Ard Biesheuvel
2020-07-16 14:23                 ` Marcelo Henrique Cerri
2020-07-16 14:37                   ` Ard Biesheuvel
2020-07-16 14:56                     ` Marcelo Henrique Cerri
2020-07-16 15:20                       ` Ard Biesheuvel
2020-07-12 16:40   ` Stephan Müller [this message]
2020-07-15 13:17     ` [PATCH v2 3/5] crypto: DH - check validity of Z before export Marcelo Henrique Cerri
2020-07-12 16:40   ` [PATCH v2 4/5] crypto: DH SP800-56A rev 3 local public key validation Stephan Müller
2020-07-15 13:18     ` Marcelo Henrique Cerri
2020-07-12 16:42   ` [PATCH v2 5/5] crypto: ECDH " Stephan Müller
2020-07-12 18:06     ` Vitaly Chikunov
2020-07-13  5:04       ` Stephan Mueller
2020-07-13  5:59         ` Vitaly Chikunov
2020-07-13  6:02           ` Stephan Müller
2020-07-15 13:19     ` Marcelo Henrique Cerri
2020-07-20 17:05   ` [PATCH v3 0/5] DH: SP800-56A rev 3 compliant validation checks Stephan Müller
2020-07-20 17:07     ` [PATCH v3 1/5] crypto: ECDH - check validity of Z before export Stephan Müller
2020-07-22 13:11       ` Vitaly Chikunov
2020-07-24 17:47       ` Neil Horman
2020-07-20 17:08     ` [PATCH v3 2/5] lib/mpi: Add mpi_sub_ui() Stephan Müller
2020-07-20 17:08     ` [PATCH v3 3/5] crypto: DH - check validity of Z before export Stephan Müller
2020-07-24 18:02       ` Neil Horman
2020-07-20 17:08     ` [PATCH v3 4/5] crypto: DH SP800-56A rev 3 local public key validation Stephan Müller
2020-07-20 17:09     ` [PATCH v3 5/5] crypto: ECDH " Stephan Müller
2020-07-21 11:35     ` [PATCH v3 0/5] DH: SP800-56A rev 3 compliant validation checks Marcelo Henrique Cerri
2020-07-31 13:29     ` Herbert Xu

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