From patchwork Tue Oct 15 20:58:37 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jarkko Sakkinen X-Patchwork-Id: 13837071 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 3C5BA1F80DD; Tue, 15 Oct 2024 20:58:58 +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=1729025939; cv=none; b=L5N0iW0waY+LR3rlpdN5QfxOpxNq+RGyffdOhXJp1G3CwLrRh/ms62yIxnDodr84OPSp30I7hZruUsIpjmDCM1E0ApNQFcSDDAy8GdQQ5Wthn/4obKg3r7bvc0s9nWUthV07xX1dZV7/zZRyLcd4eZG3kGYDtReEc5/xl7ag3+4= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1729025939; c=relaxed/simple; bh=eldE9A77XPppw7dIFi4hvn84XWAs9Hpi5aCEiES7OhI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=IEMMhqAqEht+guIKAnhpdnNqkHIxVq/Uq32EHDLV17msL8UZ3CD3hVmmtg4T8gTkhkOuSwH+BpZeZiLf3uQTMS9qtO29CTDNunR6zFwX7r7f7iZPxEEUhxLy8dVMdHsv2t8o8Z/qUd8ao/rQ/RIcH0CrG40U6zRBoFdJ5TF3bBk= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=EN3RLaGF; 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="EN3RLaGF" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 556D6C4CEC7; Tue, 15 Oct 2024 20:58:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1729025938; bh=eldE9A77XPppw7dIFi4hvn84XWAs9Hpi5aCEiES7OhI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=EN3RLaGFxAnYU1k4ESJFMyO2pvuRBGG4Qr0VJafZRQJKS8ueEvBfjwFPv4C8KR3M5 JQzI3JrfsMNKXCoAtujbpKHp25HQaNV+zHzuhd0Bnf+Ofq5E+lv/4owPC1EtDwVU7l W8sEiB9pt/HCXPNMDqK14mx0iRVHkYW4hoixBFUHePH0fHzmfzy+9eyNLJFBwmIeV9 2QYHC7zrLWKaqKAgW3iuXbvkfHEoAXtX1r+QEjhyF4remjPrcbJN03wEQrM2SzWxde chW1sguAH9eqcxaoniqcnBnFVUK4goFTfYH32IIf7D+siKpVjmlDVXAHoMyfch/dmD 1gf5F7ksU/Q/Q== From: Jarkko Sakkinen To: Peter Huewe , Jarkko Sakkinen , Jason Gunthorpe , James Bottomley Cc: Stefan Berger , stable@vger.kernel.org, linux-integrity@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v6 2/5] tpm: Implement tpm2_load_null() rollback Date: Tue, 15 Oct 2024 23:58:37 +0300 Message-ID: <20241015205842.117300-3-jarkko@kernel.org> X-Mailer: git-send-email 2.47.0 In-Reply-To: <20241015205842.117300-1-jarkko@kernel.org> References: <20241015205842.117300-1-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 --- 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 253639767c1e..1215c53f0ae7 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; } /**