From patchwork Tue Mar 10 05:16:02 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: James Bottomley X-Patchwork-Id: 11428503 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id C12DE1731 for ; Tue, 10 Mar 2020 05:18:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A01B024655 for ; Tue, 10 Mar 2020 05:18:24 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=hansenpartnership.com header.i=@hansenpartnership.com header.b="LA3OAGtv" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726045AbgCJFSY (ORCPT ); Tue, 10 Mar 2020 01:18:24 -0400 Received: from bedivere.hansenpartnership.com ([66.63.167.143]:35516 "EHLO bedivere.hansenpartnership.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726018AbgCJFSY (ORCPT ); Tue, 10 Mar 2020 01:18:24 -0400 Received: from localhost (localhost [127.0.0.1]) by bedivere.hansenpartnership.com (Postfix) with ESMTP id 102E28EE130; Mon, 9 Mar 2020 22:18:24 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=hansenpartnership.com; s=20151216; t=1583817504; bh=VFKpNu65QRAP7EiwQ890RMJI7DpANgZim1KpewF6NIM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=LA3OAGtvaXlZdBvbGdQYFlgmDyDmxGwiaXY6NjHchlZgIOBmOg6JTqm1Y6T69+GWM ihEADdFqiqbxBr0HxiaYwA6STEErFfIqWJhirdwIymcVE/dgRHO4VDCVtSR76hqLgR swmWjN2zOT6QtIYn1vArWKWDWZUvC+0RDg7F9vOQ= Received: from bedivere.hansenpartnership.com ([127.0.0.1]) by localhost (bedivere.hansenpartnership.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id AEq9TFuB_0No; Mon, 9 Mar 2020 22:18:23 -0700 (PDT) Received: from jarvis.lan (jarvis.ext.hansenpartnership.com [153.66.160.226]) by bedivere.hansenpartnership.com (Postfix) with ESMTP id 9FBFE8EE121; Mon, 9 Mar 2020 22:18:23 -0700 (PDT) From: James Bottomley To: linux-integrity@vger.kernel.org Cc: Mimi Zohar , Jarkko Sakkinen , David Woodhouse , keyrings@vger.kernel.org Subject: [PATCH v8 3/8] security: keys: trusted: fix TPM2 authorizations Date: Mon, 9 Mar 2020 22:16:02 -0700 Message-Id: <20200310051607.30334-4-James.Bottomley@HansenPartnership.com> X-Mailer: git-send-email 2.16.4 In-Reply-To: <20200310051607.30334-1-James.Bottomley@HansenPartnership.com> References: <20200310051607.30334-1-James.Bottomley@HansenPartnership.com> Sender: keyrings-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: keyrings@vger.kernel.org In TPM 1.2 an authorization was a 20 byte number. The spec actually recommended you to hash variable length passwords and use the sha1 hash as the authorization. Because the spec doesn't require this hashing, the current authorization for trusted keys is a 40 digit hex number. For TPM 2.0 the spec allows the passing in of variable length passwords and passphrases directly, so we should allow that in trusted keys for ease of use. Update the 'blobauth' parameter to take this into account, so we can now use plain text passwords for the keys. so before keyctl add trusted kmk "new 32 blobauth=f572d396fae9206628714fb2ce00f72e94f2258f" after we will accept both the old hex sha1 form as well as a new directly supplied password: keyctl add trusted kmk "new 32 blobauth=hello keyhandle=81000001" Since a sha1 hex code must be exactly 40 bytes long and a direct password must be 20 or less, we use the length as the discriminator for which form is input. Note this is both and enhancement and a potential bug fix. The TPM 2.0 spec requires us to strip leading zeros, meaning empyty authorization is a zero length HMAC whereas we're currently passing in 20 bytes of zeros. A lot of TPMs simply accept this as OK, but the Microsoft TPM emulator rejects it with TPM_RC_BAD_AUTH, so this patch makes the Microsoft TPM emulator work with trusted keys. Fixes: 0fe5480303a1 ("keys, trusted: seal/unseal with TPM 2.0 chips") Signed-off-by: James Bottomley Reviewed-by: Jarkko Sakkinen --- v6: change comment, eliminate else clauses and add fixes tag v7: fixes before signoff --- include/keys/trusted-type.h | 1 + security/keys/trusted-keys/trusted_tpm1.c | 32 +++++++++++++++++++++++++------ security/keys/trusted-keys/trusted_tpm2.c | 10 ++++++---- 3 files changed, 33 insertions(+), 10 deletions(-) diff --git a/include/keys/trusted-type.h b/include/keys/trusted-type.h index a94c03a61d8f..b2ed3481c6a0 100644 --- a/include/keys/trusted-type.h +++ b/include/keys/trusted-type.h @@ -30,6 +30,7 @@ struct trusted_key_options { uint16_t keytype; uint32_t keyhandle; unsigned char keyauth[TPM_DIGEST_SIZE]; + uint32_t blobauth_len; unsigned char blobauth[TPM_DIGEST_SIZE]; uint32_t pcrinfo_len; unsigned char pcrinfo[MAX_PCRINFO_SIZE]; diff --git a/security/keys/trusted-keys/trusted_tpm1.c b/security/keys/trusted-keys/trusted_tpm1.c index d2c5ec1e040b..add9f071d818 100644 --- a/security/keys/trusted-keys/trusted_tpm1.c +++ b/security/keys/trusted-keys/trusted_tpm1.c @@ -781,13 +781,33 @@ static int getoptions(char *c, struct trusted_key_payload *pay, return -EINVAL; break; case Opt_blobauth: - if (strlen(args[0].from) != 2 * SHA1_DIGEST_SIZE) - return -EINVAL; - res = hex2bin(opt->blobauth, args[0].from, - SHA1_DIGEST_SIZE); - if (res < 0) - return -EINVAL; + /* + * TPM 1.2 authorizations are sha1 hashes passed in as + * hex strings. TPM 2.0 authorizations are simple + * passwords (although it can take a hash as well) + */ + opt->blobauth_len = strlen(args[0].from); + + if (opt->blobauth_len == 2 * TPM_DIGEST_SIZE) { + res = hex2bin(opt->blobauth, args[0].from, + TPM_DIGEST_SIZE); + if (res < 0) + return -EINVAL; + + opt->blobauth_len = TPM_DIGEST_SIZE; + return 0; + } + + if (tpm2 && opt->blobauth_len <= sizeof(opt->blobauth)) { + memcpy(opt->blobauth, args[0].from, + opt->blobauth_len); + return 0; + } + + return -EINVAL; + break; + case Opt_migratable: if (*args[0].from == '0') pay->migratable = 0; diff --git a/security/keys/trusted-keys/trusted_tpm2.c b/security/keys/trusted-keys/trusted_tpm2.c index 08ec7f48f01d..b4a5058107c2 100644 --- a/security/keys/trusted-keys/trusted_tpm2.c +++ b/security/keys/trusted-keys/trusted_tpm2.c @@ -91,10 +91,12 @@ int tpm2_seal_trusted(struct tpm_chip *chip, TPM_DIGEST_SIZE); /* sensitive */ - tpm_buf_append_u16(&buf, 4 + TPM_DIGEST_SIZE + payload->key_len + 1); + tpm_buf_append_u16(&buf, 4 + options->blobauth_len + payload->key_len + 1); + + tpm_buf_append_u16(&buf, options->blobauth_len); + if (options->blobauth_len) + tpm_buf_append(&buf, options->blobauth, options->blobauth_len); - tpm_buf_append_u16(&buf, TPM_DIGEST_SIZE); - tpm_buf_append(&buf, options->blobauth, TPM_DIGEST_SIZE); tpm_buf_append_u16(&buf, payload->key_len + 1); tpm_buf_append(&buf, payload->key, payload->key_len); tpm_buf_append_u8(&buf, payload->migratable); @@ -258,7 +260,7 @@ static int tpm2_unseal_cmd(struct tpm_chip *chip, NULL /* nonce */, 0, TPM2_SA_CONTINUE_SESSION, options->blobauth /* hmac */, - TPM_DIGEST_SIZE); + options->blobauth_len); rc = tpm_send(chip, buf.data, tpm_buf_length(&buf)); if (rc > 0)