From patchwork Tue May 2 01:15:58 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jarkko Sakkinen X-Patchwork-Id: 13228418 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9A776C7EE21 for ; Tue, 2 May 2023 01:16:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233401AbjEBBQR (ORCPT ); Mon, 1 May 2023 21:16:17 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58342 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233390AbjEBBQQ (ORCPT ); Mon, 1 May 2023 21:16:16 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D1AB840F0; Mon, 1 May 2023 18:16:14 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 52A8561BCB; Tue, 2 May 2023 01:16:14 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5F6FCC433EF; Tue, 2 May 2023 01:16:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1682990173; bh=jw3tryjtZVR59Kgi2CPEHZnInV3fijXsH621FDHqksc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Yz+c4M9joX6zWN1bbjXLkOeBSzz8DYu6sRahMvg1Fn4IK7HBLCXzp7r1TD2BJoPWP NaKp45phmW9T1Q8qI4e/rp4pIeZibRVuKf9j/ZUinwU/HbCio4r3MsveQ2KhOvKGvZ qnyjXe10jUq/7r+rg7skmGyPLZngt/hK3bRCvPaswHe6ERIDJ1NLC6NUx+0ck6QE0F azfedMeoi58IKzbHv64oLR0HRgm08moVUV+IHhPpy3OFsQZtxbP1oFFzvkIWxmMfkP 4Mc7+1WxTkidJ/mEX8aeGVhIA4+wxkFdphHXLrhinajORTpG2zjshygfx1BvG4UH24 wGjNPCYO+r5Dg== From: Jarkko Sakkinen To: linux-integrity@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Jarkko Sakkinen , Vlastimil Babka , "Jason A . Donenfeld" , Jason Gunthorpe , Jerry Snitselaar , stable@vger.kernel.org Subject: [PATCH v2 2/2] tpm: Prevent hwrng from activating during resume Date: Tue, 2 May 2023 04:15:58 +0300 Message-Id: <20230502011558.10743-3-jarkko@kernel.org> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230502011558.10743-1-jarkko@kernel.org> References: <20230502011558.10743-1-jarkko@kernel.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-integrity@vger.kernel.org Set TPM_CHIP_FLAG_SUSPENDED in tpm_pm_suspend() and reset in tpm_pm_resume(). While the flag is set, tpm_hwrng() gives back zero bytes. This prevents hwrng from racing during resume. Cc: stable@vger.kernel.org Fixes: 6e592a065d51 ("tpm: Move Linux RNG connection to hwrng") Reviewed-by: Jerry Snitselaar Signed-off-by: Jarkko Sakkinen --- drivers/char/tpm/tpm-chip.c | 4 ++++ drivers/char/tpm/tpm-interface.c | 10 ++++++++++ include/linux/tpm.h | 1 + 3 files changed, 15 insertions(+) diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c index c10a4aa97373..cd48033b804a 100644 --- a/drivers/char/tpm/tpm-chip.c +++ b/drivers/char/tpm/tpm-chip.c @@ -571,6 +571,10 @@ static int tpm_hwrng_read(struct hwrng *rng, void *data, size_t max, bool wait) { struct tpm_chip *chip = container_of(rng, struct tpm_chip, hwrng); + /* Give back zero bytes, as TPM chip has not yet fully resumed: */ + if (chip->flags & TPM_CHIP_FLAG_SUSPENDED) + return 0; + return tpm_get_random(chip, data, max); } diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c index 4463d0018290..586ca10b0d72 100644 --- a/drivers/char/tpm/tpm-interface.c +++ b/drivers/char/tpm/tpm-interface.c @@ -412,6 +412,8 @@ int tpm_pm_suspend(struct device *dev) } suspended: + chip->flags |= TPM_CHIP_FLAG_SUSPENDED; + if (rc) dev_err(dev, "Ignoring error %d while suspending\n", rc); return 0; @@ -429,6 +431,14 @@ int tpm_pm_resume(struct device *dev) if (chip == NULL) return -ENODEV; + chip->flags &= ~TPM_CHIP_FLAG_SUSPENDED; + + /* + * Guarantee that SUSPENDED is written last, so that hwrng does not + * activate before the chip has been fully resumed. + */ + wmb(); + return 0; } EXPORT_SYMBOL_GPL(tpm_pm_resume); diff --git a/include/linux/tpm.h b/include/linux/tpm.h index 77693389c3f9..6a1e8f157255 100644 --- a/include/linux/tpm.h +++ b/include/linux/tpm.h @@ -282,6 +282,7 @@ enum tpm_chip_flags { TPM_CHIP_FLAG_ALWAYS_POWERED = BIT(5), TPM_CHIP_FLAG_FIRMWARE_POWER_MANAGED = BIT(6), TPM_CHIP_FLAG_FIRMWARE_UPGRADE = BIT(7), + TPM_CHIP_FLAG_SUSPENDED = BIT(8), }; #define to_tpm_chip(d) container_of(d, struct tpm_chip, dev)