From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 4A655C369C2 for ; Tue, 22 Apr 2025 10:31:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: Content-Type:MIME-Version:Message-ID:Date:Subject:Cc:To:From:Reply-To: Content-ID:Content-Description:Resent-Date:Resent-From:Resent-Sender: Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To:References:List-Owner; bh=HHEz/+ubk2A0Vj5bhm9eyEa2NH6WNZdZF0TFxwHEsMY=; b=UzXP+PtJPmxBKn5gzDgm8Ihukb lVo/XnV5twMLz/nuypQ9sGF3ghyjDPZ4iPiPIA6kus4r7kJ8gGC0jNZbs7NKRctw88Baq4x7X1Sy3 nxAZK3cgODvbMXrrzPqLl4PNvQtYMCg3zzSXbPIATs7wbkxY2TBilfLea04jcwftacdofQwNAwIyL ZFmJsVK6Bv6G9QX8a2wtJ3nGNahh5VmQ+E84eiNEVmdfuONwvUKl7Q/KulFZOb7JsNaKyB2d9+tYu WYawGEXY1sgbJyO6s4YaOryAWbjjZ4WOn551Ly40PxGBpBbNheuSTOTd5DBbK0rDYZBZha8G3X9vl JJmfX9Ng==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1u7Au8-00000006mmF-0Z0W; Tue, 22 Apr 2025 10:31:04 +0000 Received: from tor.source.kernel.org ([172.105.4.254]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1u7ANZ-00000006etG-1les for linux-arm-kernel@lists.infradead.org; Tue, 22 Apr 2025 09:57:25 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by tor.source.kernel.org (Postfix) with ESMTP id E6E1F614AB; Tue, 22 Apr 2025 09:57:04 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 31B2DC4CEE9; Tue, 22 Apr 2025 09:57:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1745315844; bh=t1U5iu98UOVrBT4ZBbp17ocR2D+pzk83ZqkZJHQyekw=; h=From:To:Cc:Subject:Date:From; b=oRY1KBfXD6XpEip2QJIKF9vcSvOYFSGYWB0yBS2TWWN5XoySex5XlxZQCPTgqSV/F ygHLWy89V2pRzcET2vZhQSkH4AzcEz+Wgyv25q9Hu5x254EpYG3RdSnq01Qhfqu5Fu Hg5ywdrncFxOLNJ5Nxk+11e9H0mRkJrVr6zOebhcrfGLxOoFT6vt0MkDGX+UehGJU9 URsZlrh0Si+X4AQdnCX0qGjPvHkZXPozCyQcJJ1rFLVD4cL2o9j6ZvOrrPfcF9JmS2 ih6c+DOzJleOp6+LRk7lkUmlJok5QtjmwdLw99V3ycWVCrZyooXKY2ydUFB92V/BDt yjEmO4PBxHDGQ== From: =?UTF-8?q?Marek=20Beh=C3=BAn?= To: linux-crypto@vger.kernel.org Cc: =?UTF-8?q?Marek=20Beh=C3=BAn?= , Herbert Xu , "David S. Miller" , Nicolas Ferre , Alexandre Belloni , Claudiu Beznea , Ard Biesheuvel , Linus Walleij , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: [PATCH] crypto: atmel-sha204a - Set hwrng quality to lowest possible Date: Tue, 22 Apr 2025 11:57:18 +0200 Message-ID: <20250422095718.17360-1-kabel@kernel.org> X-Mailer: git-send-email 2.49.0 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org According to the review by Bill Cox [1], the Atmel SHA204A random number generator produces random numbers with very low entropy. Set the lowest possible entropy for this chip just to be safe. [1] https://www.metzdowd.com/pipermail/cryptography/2014-December/023858.html Fixes: da001fb651b00e1d ("crypto: atmel-i2c - add support for SHA204A random number generator") Signed-off-by: Marek Behún --- drivers/crypto/atmel-sha204a.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/drivers/crypto/atmel-sha204a.c b/drivers/crypto/atmel-sha204a.c index 75bebec2c757..0fcf4a39de27 100644 --- a/drivers/crypto/atmel-sha204a.c +++ b/drivers/crypto/atmel-sha204a.c @@ -163,6 +163,12 @@ static int atmel_sha204a_probe(struct i2c_client *client) i2c_priv->hwrng.name = dev_name(&client->dev); i2c_priv->hwrng.read = atmel_sha204a_rng_read; + /* + * According to review by Bill Cox [1], this HWRNG has very low entropy. + * [1] https://www.metzdowd.com/pipermail/cryptography/2014-December/023858.html + */ + i2c_priv->hwrng.quality = 1; + ret = devm_hwrng_register(&client->dev, &i2c_priv->hwrng); if (ret) dev_warn(&client->dev, "failed to register RNG (%d)\n", ret); -- 2.49.0