From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E3755424671; Thu, 16 Jul 2026 14:13:10 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784211192; cv=none; b=IUsns3hOMHkFn1AoVfmlPm3zmXO9nFuN1ZKC2TsSN9/sbLbLZ33jAEW3FaXpAtQDAYd+rtrgew4ukGmRyMm6BQZU+6BjWIwAjZ4D2mxjROUbKiUSNq2LB748j47c4lSudGCwi72DtTeGz5xEuVuTvIlh9MCFsOLUaNz3Dw+JLbI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784211192; c=relaxed/simple; bh=JbqPPKxnuY+5Ru/skPuycr5SgDuRzXx5dYbnrhmfxKE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=pPlloEuBjPpBSoRkOQQdR1sgVn75yRiZzZ0xpEDJqGraGggaofzjKgsX77h1JiCzNSDQpSuXwWj7swOXUj4grXdan/tfmSqK0pvUt19/1g4Rs9UR6+f3nHRfD1GTxleBptphc9saxIz90Gd8CgmuTGpsrQHR0mSZK23/pWXUAJo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=DBeBG2mk; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="DBeBG2mk" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4702C1F00A3E; Thu, 16 Jul 2026 14:13:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1784211190; bh=1hvToLsJVmJ9TZKLMwbiWqrWIbFc4AUi4MBKMevMEdA=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=DBeBG2mk0D2hPN3F5JfnZW9ngIBwuu3LrA1ErEvUJIYOjnau5pG5HwuvTGpT9w1PI zEQI5F2CAsLRxDevAUF/TaK/Dnu6qAaKXvFMUpMyvsIO/+xNB0fPVrTHkwPffvZ2cr DmISc7M5pFyYx+/d/UNpTnvTSKebnTSXVFi62lZ0= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Thorsten Blum , Ard Biesheuvel , Herbert Xu Subject: [PATCH 6.18 335/480] crypto: atmel-sha204a - drop hwrng quality reduction for ATSHA204A Date: Thu, 16 Jul 2026 15:31:22 +0200 Message-ID: <20260716133052.061493378@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260716133044.672218725@linuxfoundation.org> References: <20260716133044.672218725@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Thorsten Blum commit ea5e57cc97185329dcc5ebdcaae7e1500bf0ad0b upstream. Commit 8006aff15516 ("crypto: atmel-sha204a - Set hwrng quality to lowest possible") reduced the hwrng quality to 1 based on a review by Bill Cox [1]. However, despite its title, the review only tested the ATSHA204, not the ATSHA204A. In the same thread, Atmel engineer Landon Cox wrote "this behavior has been eliminated entirely"[2] in the ATSHA204A and "this problem does not affect the ATECC108 or the ATECC108A (or the ATSHA204A)"[3]. According to the official ATSHA204A datasheet [4], the device contains a high-quality hardware RNG that combines its output with an internal seed value stored in EEPROM or SRAM to generate random numbers. The device also implements all security functions using SHA-256, and the driver uses the chip's Random command in seed-update mode. Keep 'quality = 1' for ATSHA204, but drop the explicit hwrng quality reduction for ATSHA204A and fall back to the hwrng core default. [1] https://www.metzdowd.com/pipermail/cryptography/2014-December/023858.html [2] https://www.metzdowd.com/pipermail/cryptography/2014-December/023852.html [3] https://www.metzdowd.com/pipermail/cryptography/2014-December/023886.html [4] https://ww1.microchip.com/downloads/en/DeviceDoc/ATSHA204A-Data-Sheet-40002025A.pdf Fixes: 8006aff15516 ("crypto: atmel-sha204a - Set hwrng quality to lowest possible") Cc: stable@vger.kernel.org Signed-off-by: Thorsten Blum Reviewed-by: Ard Biesheuvel Signed-off-by: Herbert Xu Signed-off-by: Greg Kroah-Hartman --- drivers/crypto/atmel-sha204a.c | 19 ++++++++++++------- 1 file changed, 12 insertions(+), 7 deletions(-) --- a/drivers/crypto/atmel-sha204a.c +++ b/drivers/crypto/atmel-sha204a.c @@ -19,6 +19,12 @@ #include #include "atmel-i2c.h" +/* + * According to review by Bill Cox [1], the ATSHA204 has very low entropy. + * [1] https://www.metzdowd.com/pipermail/cryptography/2014-December/023858.html + */ +static const unsigned short atsha204_quality = 1; + static void atmel_sha204a_rng_done(struct atmel_i2c_work_data *work_data, void *areq, int status) { @@ -158,6 +164,7 @@ static const struct attribute_group atme static int atmel_sha204a_probe(struct i2c_client *client) { struct atmel_i2c_client_priv *i2c_priv; + const unsigned short *quality; int ret; ret = atmel_i2c_probe(client); @@ -171,11 +178,9 @@ static int atmel_sha204a_probe(struct i2 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; + quality = i2c_get_match_data(client); + if (quality) + i2c_priv->hwrng.quality = *quality; ret = devm_hwrng_register(&client->dev, &i2c_priv->hwrng); if (ret) @@ -207,14 +212,14 @@ static void atmel_sha204a_remove(struct } static const struct of_device_id atmel_sha204a_dt_ids[] __maybe_unused = { - { .compatible = "atmel,atsha204", }, + { .compatible = "atmel,atsha204", .data = &atsha204_quality }, { .compatible = "atmel,atsha204a", }, { /* sentinel */ } }; MODULE_DEVICE_TABLE(of, atmel_sha204a_dt_ids); static const struct i2c_device_id atmel_sha204a_id[] = { - { "atsha204" }, + { "atsha204", (kernel_ulong_t)&atsha204_quality }, { "atsha204a" }, { /* sentinel */ } };