From: John Marino <draco@marino.st>
Date: Fri, 13 Jan 2017 22:11:37 +0000 (-0600)
Subject: security/libressl: Fix ECDSA P-256 timing attack vulnerability
X-Git-Tag: v4.8.0rc~225
X-Git-Url: https://gitweb.dragonflybsd.org/dragonfly.git/commitdiff_plain/bd84e83893b298face58762e1fec24667126c8c7

security/libressl: Fix ECDSA P-256 timing attack vulnerability

OpenBSD 6.0 errata 16, Jan 5, 2017:
Avoid possible side-channel leak of ECDSA private keys when signing.

security: CVE-2016-7056
---

diff --git a/crypto/libressl/README.DRAGONFLY b/crypto/libressl/README.DRAGONFLY
index be9696c75f..a74db54680 100644
--- a/crypto/libressl/README.DRAGONFLY
+++ b/crypto/libressl/README.DRAGONFLY
@@ -10,3 +10,6 @@ size = 3014463
 sha1 = 5daaf33f5cc382e1c9dd7375a67e26aad1d0b2ed
 
 The file README.DELETED contains a list of deleted files and directories.
+
+Local modifications applied to following files:
+	crypto/ecdsa/ecs_ossl.c
diff --git a/crypto/libressl/crypto/ecdsa/ecs_ossl.c b/crypto/libressl/crypto/ecdsa/ecs_ossl.c
index b03b1fb0bd..37245d92b8 100644
--- a/crypto/libressl/crypto/ecdsa/ecs_ossl.c
+++ b/crypto/libressl/crypto/ecdsa/ecs_ossl.c
@@ -142,6 +142,8 @@ ecdsa_sign_setup(EC_KEY *eckey, BN_CTX *ctx_in, BIGNUM **kinvp, BIGNUM **rp)
 			if (!BN_add(k, k, order))
 				goto err;
 
+		BN_set_flags(k, BN_FLG_CONSTTIME);
+
 		/* compute r the x-coordinate of generator * k */
 		if (!EC_POINT_mul(group, tmp_point, k, NULL, NULL, ctx)) {
 			ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_EC_LIB);