From patchwork Mon Oct 21 05:39:16 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jarkko Sakkinen X-Patchwork-Id: 13843568 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 4ABD8194AF3; Mon, 21 Oct 2024 05:39:40 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1729489180; cv=none; b=OmkR7Lug7eBX0r4T663QeLfR6ODDpRvQ8Kp4rtKly2RwOjUDuT87Fy/ITZ2re3Zc7q7NN9pBZ51D0ogZSf2bdx2Zob2x6aOXN41ULWYywNDvX1SwtgYp3ZNbPrC1B2vYE0r51oUCFCJcjP9fEH6Vorb8La/mUnHxVtLYs+qBd+Q= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1729489180; c=relaxed/simple; bh=D0m4paxP6P0gzIZy7P2Jr7htyTZRIO+jDExebpPsZQ4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=MI2XRKmuIZ9uQDS5DnNY+jdwcmqTTK7lcPxpCtC3Uc4ftM3vZZs9/8/VMo2NzBXisYwXbIKF1CZouZuXp5C+mAonFqQaiJS7NyXLXYgrMCw5vqZnF4aXRbBAD0TVQtrD7LDRhRICR1DmB6CinuN10Iv2XW63zGPtmeUqZQgKRw0= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=plF3Rzne; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="plF3Rzne" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3AB4DC4CEC3; Mon, 21 Oct 2024 05:39:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1729489179; bh=D0m4paxP6P0gzIZy7P2Jr7htyTZRIO+jDExebpPsZQ4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=plF3RznebuLsmKn3P4aGm240QSdRrTVuIS0UgAMa/HJoG1/bdnZKuhXyXTR7kAAv2 FXMoworq4UGjARs+SBbjUSuhjqYM/DEYRtY6wfBDNV5jiKkqLL4GA753+VMBUwnjR3 Qu36XzfR1terhsaMf6ntNwMbYrrTQc9OTunYFFpb/nojFKbLJCbmYj7dfEt1rPsou1 53BGOeF8qDCqk9nudBwP2FNMBHPXp8nglYlTUDJnAcDPPj9x4Q/n+AO79K+V/bYqlC OL6YL9Bi3pSFTSgNkqySulTBZQlXL5YhpNsbCpdKIiAltNuIAJ3jdE5rmjhKK+B9OV 2U+r9yhmZJTHA== From: Jarkko Sakkinen To: linux-integrity@vger.kernel.org, Peter Huewe , Jarkko Sakkinen , Jason Gunthorpe , James Bottomley Cc: David Howells , Mimi Zohar , Roberto Sassu , Stefan Berger , linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: [PATCH v7 2/5] tpm: Implement tpm2_load_null() rollback Date: Mon, 21 Oct 2024 08:39:16 +0300 Message-ID: <20241021053921.33274-3-jarkko@kernel.org> X-Mailer: git-send-email 2.47.0 In-Reply-To: <20241021053921.33274-1-jarkko@kernel.org> References: <20241021053921.33274-1-jarkko@kernel.org> Precedence: bulk X-Mailing-List: linux-integrity@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 tpm2_load_null() has weak and broken error handling: - The return value of tpm2_create_primary() is ignored. - Leaks TPM return codes from tpm2_load_context() to the caller. - If the key name comparison succeeds returns previous error instead of zero to the caller. Implement a proper error rollback. Cc: stable@vger.kernel.org # v6.10+ Fixes: eb24c9788cd9 ("tpm: disable the TPM if NULL name changes") Signed-off-by: Jarkko Sakkinen Reviewed-by: Stefan Berger --- v6: - Address Stefan's remark: https://lore.kernel.org/linux-integrity/def4ec2d-584b-405f-9d5e-99267013c3c0@linux.ibm.com/ v5: - Fix the TPM error code leak from tpm2_load_context(). v4: - No changes. v3: - Update log messages. Previously the log message incorrectly stated on load failure that integrity check had been failed, even tho the check is done *after* the load operation. v2: - Refined the commit message. - Reverted tpm2_create_primary() changes. They are not required if tmp_null_key is used as the parameter. --- drivers/char/tpm/tpm2-sessions.c | 43 +++++++++++++++++--------------- 1 file changed, 23 insertions(+), 20 deletions(-) diff --git a/drivers/char/tpm/tpm2-sessions.c b/drivers/char/tpm/tpm2-sessions.c index 1e12e0b2492e..bdac11964b55 100644 --- a/drivers/char/tpm/tpm2-sessions.c +++ b/drivers/char/tpm/tpm2-sessions.c @@ -915,33 +915,36 @@ static int tpm2_parse_start_auth_session(struct tpm2_auth *auth, static int tpm2_load_null(struct tpm_chip *chip, u32 *null_key) { - int rc; unsigned int offset = 0; /* dummy offset for null seed context */ u8 name[SHA256_DIGEST_SIZE + 2]; + u32 tmp_null_key; + int rc; rc = tpm2_load_context(chip, chip->null_key_context, &offset, - null_key); - if (rc != -EINVAL) - return rc; + &tmp_null_key); + if (rc != -EINVAL) { + if (!rc) + *null_key = tmp_null_key; + goto err; + } - /* an integrity failure may mean the TPM has been reset */ - dev_err(&chip->dev, "NULL key integrity failure!\n"); - /* check the null name against what we know */ - tpm2_create_primary(chip, TPM2_RH_NULL, NULL, name); - if (memcmp(name, chip->null_key_name, sizeof(name)) == 0) - /* name unchanged, assume transient integrity failure */ - return rc; - /* - * Fatal TPM failure: the NULL seed has actually changed, so - * the TPM must have been illegally reset. All in-kernel TPM - * operations will fail because the NULL primary can't be - * loaded to salt the sessions, but disable the TPM anyway so - * userspace programmes can't be compromised by it. - */ - dev_err(&chip->dev, "NULL name has changed, disabling TPM due to interference\n"); + rc = tpm2_create_primary(chip, TPM2_RH_NULL, &tmp_null_key, name); + if (rc) + goto err; + + /* Return the null key if the name has not been changed: */ + if (memcmp(name, chip->null_key_name, sizeof(name)) == 0) { + *null_key = tmp_null_key; + return 0; + } + + /* Deduce from the name change TPM interference: */ + dev_err(&chip->dev, "the null key integrity check failedh\n"); + tpm2_flush_context(chip, tmp_null_key); chip->flags |= TPM_CHIP_FLAG_DISABLE; - return rc; +err: + return rc ? -ENODEV : 0; } /**