From patchwork Tue Mar 10 05:16:03 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: James Bottomley X-Patchwork-Id: 11428507 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 5858E14E3 for ; Tue, 10 Mar 2020 05:19:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2F96024655 for ; Tue, 10 Mar 2020 05:19:07 +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="T66AGzkm" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726100AbgCJFTH (ORCPT ); Tue, 10 Mar 2020 01:19:07 -0400 Received: from bedivere.hansenpartnership.com ([66.63.167.143]:35554 "EHLO bedivere.hansenpartnership.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726088AbgCJFTG (ORCPT ); Tue, 10 Mar 2020 01:19:06 -0400 Received: from localhost (localhost [127.0.0.1]) by bedivere.hansenpartnership.com (Postfix) with ESMTP id 859C28EE130; Mon, 9 Mar 2020 22:19:06 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=hansenpartnership.com; s=20151216; t=1583817546; bh=eHKen1U6lSMyEaL+cyLuPnsPKKIy8Gr6+hlWx1fIS4Q=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=T66AGzkmqlY8APb7OYCwk9MY2ilU9J4K8/tGLY+NSvPQUaH2kWaCnl8Ew8nXCph95 XmZXl0rGh/KmpCTDMdJLlDXIMwJajCehovrJ21DzfWergJzgXfKgnaaRfLwEJHee6P SdnQej4iKSpBBt6mZ7SOhfElEKlBdXyFFowdSCyI= 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 wcDEN3hBkTWV; Mon, 9 Mar 2020 22:19:06 -0700 (PDT) Received: from jarvis.lan (jarvis.ext.hansenpartnership.com [153.66.160.226]) by bedivere.hansenpartnership.com (Postfix) with ESMTP id 1ADC38EE121; Mon, 9 Mar 2020 22:19:06 -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 4/8] security: keys: trusted: use ASN.1 TPM2 key format for the blobs Date: Mon, 9 Mar 2020 22:16:03 -0700 Message-Id: <20200310051607.30334-5-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 Modify the TPM2 key format blob output to export and import in the ASN.1 form for TPM2 sealed object keys. For compatibility with prior trusted keys, the importer will also accept two TPM2B quantities representing the public and private parts of the key. However, the export via keyctl pipe will only output the ASN.1 format. The benefit of the ASN.1 format is that it's a standard and thus the exported key can be used by userspace tools (openssl_tpm2_engine, openconnect and tpm2-tss-engine). The format includes policy specifications, thus it gets us out of having to construct policy handles in userspace and the format includes the parent meaning you don't have to keep passing it in each time. This patch only implements basic handling for the ASN.1 format, so keys with passwords but no policy. Signed-off-by: James Bottomley --- v2: Updated encode API, added length checks v5: correct export format after doing interoperability checks v7: use prefix tpm2_key_ instead of tpmkey_ for functions v8: resplit commit --- include/keys/trusted-type.h | 1 + security/keys/trusted-keys/Makefile | 2 +- security/keys/trusted-keys/tpm2key.asn1 | 23 ++++ security/keys/trusted-keys/trusted_tpm1.c | 2 +- security/keys/trusted-keys/trusted_tpm2.c | 207 +++++++++++++++++++++++++++++- 5 files changed, 227 insertions(+), 8 deletions(-) create mode 100644 security/keys/trusted-keys/tpm2key.asn1 diff --git a/include/keys/trusted-type.h b/include/keys/trusted-type.h index b2ed3481c6a0..b2d87ad21714 100644 --- a/include/keys/trusted-type.h +++ b/include/keys/trusted-type.h @@ -22,6 +22,7 @@ struct trusted_key_payload { unsigned int key_len; unsigned int blob_len; unsigned char migratable; + unsigned char old_format; unsigned char key[MAX_KEY_SIZE + 1]; unsigned char blob[MAX_BLOB_SIZE]; }; diff --git a/security/keys/trusted-keys/Makefile b/security/keys/trusted-keys/Makefile index 7b73cebbb378..e0198641eff2 100644 --- a/security/keys/trusted-keys/Makefile +++ b/security/keys/trusted-keys/Makefile @@ -5,4 +5,4 @@ obj-$(CONFIG_TRUSTED_KEYS) += trusted.o trusted-y += trusted_tpm1.o -trusted-y += trusted_tpm2.o +trusted-y += trusted_tpm2.o tpm2key.asn1.o diff --git a/security/keys/trusted-keys/tpm2key.asn1 b/security/keys/trusted-keys/tpm2key.asn1 new file mode 100644 index 000000000000..660b3fa917ae --- /dev/null +++ b/security/keys/trusted-keys/tpm2key.asn1 @@ -0,0 +1,23 @@ +--- +--- Note: This isn't quite the definition in the standard +--- However, the Linux asn.1 parser doesn't understand +--- [2] EXPLICIT SEQUENCE OF OPTIONAL +--- So there's an extra intermediate TPMPolicySequence +--- definition to work around this + +TPMKey ::= SEQUENCE { + type OBJECT IDENTIFIER ({tpm2_key_type}), + emptyAuth [0] EXPLICIT BOOLEAN OPTIONAL, + policy [1] EXPLICIT TPMPolicySequence OPTIONAL, + secret [2] EXPLICIT OCTET STRING OPTIONAL, + parent INTEGER ({tpm2_key_parent}), + pubkey OCTET STRING ({tpm2_key_pub}), + privkey OCTET STRING ({tpm2_key_priv}) + } + +TPMPolicySequence ::= SEQUENCE OF TPMPolicy + +TPMPolicy ::= SEQUENCE { + commandCode [0] EXPLICIT INTEGER, + commandPolicy [1] EXPLICIT OCTET STRING + } diff --git a/security/keys/trusted-keys/trusted_tpm1.c b/security/keys/trusted-keys/trusted_tpm1.c index add9f071d818..77e16caa6a65 100644 --- a/security/keys/trusted-keys/trusted_tpm1.c +++ b/security/keys/trusted-keys/trusted_tpm1.c @@ -1011,7 +1011,7 @@ static int trusted_instantiate(struct key *key, goto out; } - if (!options->keyhandle) { + if (!options->keyhandle && !tpm2) { ret = -EINVAL; goto out; } diff --git a/security/keys/trusted-keys/trusted_tpm2.c b/security/keys/trusted-keys/trusted_tpm2.c index b4a5058107c2..e8dcc47b3388 100644 --- a/security/keys/trusted-keys/trusted_tpm2.c +++ b/security/keys/trusted-keys/trusted_tpm2.c @@ -4,6 +4,8 @@ * Copyright (C) 2014 Intel Corporation */ +#include +#include #include #include #include @@ -12,6 +14,10 @@ #include #include +#include + +#include "tpm2key.asn1.h" + static struct tpm2_hash tpm2_hash_map[] = { {HASH_ALGO_SHA1, TPM_ALG_SHA1}, {HASH_ALGO_SHA256, TPM_ALG_SHA256}, @@ -20,6 +26,165 @@ static struct tpm2_hash tpm2_hash_map[] = { {HASH_ALGO_SM3_256, TPM_ALG_SM3_256}, }; +static u32 tpm2key_oid[] = { 2,23,133,10,1,5 }; + +static int tpm2_key_encode(struct trusted_key_payload *payload, + struct trusted_key_options *options, + u8 *src, u32 len) +{ + const int SCRATCH_SIZE = PAGE_SIZE; + u8 *scratch = kmalloc(SCRATCH_SIZE, GFP_KERNEL); + u8 *work = scratch, *work1; + u8 *end_work = scratch + SCRATCH_SIZE; + u8 *priv, *pub; + u16 priv_len, pub_len; + + priv_len = get_unaligned_be16(src) + 2; + priv = src; + + src += priv_len; + + pub_len = get_unaligned_be16(src) + 2; + pub = src; + + if (!scratch) + return -ENOMEM; + + work = asn1_encode_oid(work, end_work, tpm2key_oid, + asn1_oid_len(tpm2key_oid)); + + if (options->blobauth_len == 0) { + unsigned char bool[3], *w = bool; + /* tag 0 is emptyAuth */ + w = asn1_encode_boolean(w, w + sizeof(bool), true); + if (WARN(IS_ERR(w), "BUG: Boolean failed to encode")) + return PTR_ERR(w); + work = asn1_encode_tag(work, end_work, 0, bool, w - bool); + } + + /* + * Assume both octet strings will encode to a 2 byte definite length + * + * Note: For a well behaved TPM, this warning should never + * trigger, so if it does there's something nefarious going on + */ + if (WARN(work - scratch + pub_len + priv_len + 14 > SCRATCH_SIZE, + "BUG: scratch buffer is too small")) + return -EINVAL; + + work = asn1_encode_integer(work, end_work, options->keyhandle); + work = asn1_encode_octet_string(work, end_work, pub, pub_len); + work = asn1_encode_octet_string(work, end_work, priv, priv_len); + + work1 = payload->blob; + work1 = asn1_encode_sequence(work1, work1 + sizeof(payload->blob), + scratch, work - scratch); + if (WARN(IS_ERR(work1), "BUG: ASN.1 encoder failed")) + return PTR_ERR(work1); + + return work1 - payload->blob; +} + +struct tpm2_key_context { + u32 parent; + const u8 *pub; + u32 pub_len; + const u8 *priv; + u32 priv_len; +}; + +static int tpm2_key_decode(struct trusted_key_payload *payload, + struct trusted_key_options *options, + u8 **buf) +{ + int ret; + struct tpm2_key_context ctx; + u8 *blob; + + memset(&ctx, 0, sizeof(ctx)); + + ret = asn1_ber_decoder(&tpm2key_decoder, &ctx, payload->blob, + payload->blob_len); + if (ret < 0) + return ret; + + if (ctx.priv_len + ctx.pub_len > MAX_BLOB_SIZE) + return -EINVAL; + + blob = kmalloc(ctx.priv_len + ctx.pub_len + 4, GFP_KERNEL); + if (!blob) + return -ENOMEM; + + *buf = blob; + options->keyhandle = ctx.parent; + + memcpy(blob, ctx.priv, ctx.priv_len); + blob += ctx.priv_len; + + memcpy(blob, ctx.pub, ctx.pub_len); + + return 0; +} + +int tpm2_key_parent(void *context, size_t hdrlen, + unsigned char tag, + const void *value, size_t vlen) +{ + struct tpm2_key_context *ctx = context; + const u8 *v = value; + int i; + + ctx->parent = 0; + for (i = 0; i < vlen; i++) { + ctx->parent <<= 8; + ctx->parent |= v[i]; + } + + return 0; +} + +int tpm2_key_type(void *context, size_t hdrlen, + unsigned char tag, + const void *value, size_t vlen) +{ + enum OID oid = look_up_OID(value, vlen); + + if (oid != OID_TPMSealedData) { + char buffer[50]; + + sprint_oid(value, vlen, buffer, sizeof(buffer)); + pr_debug("OID is \"%s\" which is not TPMSealedData\n", + buffer); + return -EINVAL; + } + + return 0; +} + +int tpm2_key_pub(void *context, size_t hdrlen, + unsigned char tag, + const void *value, size_t vlen) +{ + struct tpm2_key_context *ctx = context; + + ctx->pub = value; + ctx->pub_len = vlen; + + return 0; +} + +int tpm2_key_priv(void *context, size_t hdrlen, + unsigned char tag, + const void *value, size_t vlen) +{ + struct tpm2_key_context *ctx = context; + + ctx->priv = value; + ctx->priv_len = vlen; + + return 0; +} + /** * tpm_buf_append_auth() - append TPMS_AUTH_COMMAND to the buffer. * @@ -79,6 +244,9 @@ int tpm2_seal_trusted(struct tpm_chip *chip, if (i == ARRAY_SIZE(tpm2_hash_map)) return -EINVAL; + if (!options->keyhandle) + return -EINVAL; + rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_CREATE); if (rc) return rc; @@ -146,8 +314,10 @@ int tpm2_seal_trusted(struct tpm_chip *chip, goto out; } - memcpy(payload->blob, &buf.data[TPM_HEADER_SIZE + 4], blob_len); - payload->blob_len = blob_len; + payload->blob_len = + tpm2_key_encode(payload, options, + &buf.data[TPM_HEADER_SIZE + 4], + blob_len); out: tpm_buf_destroy(&buf); @@ -158,6 +328,8 @@ int tpm2_seal_trusted(struct tpm_chip *chip, else rc = -EPERM; } + if (payload->blob_len < 0) + return payload->blob_len; return rc; } @@ -184,13 +356,34 @@ static int tpm2_load_cmd(struct tpm_chip *chip, unsigned int private_len; unsigned int public_len; unsigned int blob_len; + u8 *blob; int rc; - private_len = be16_to_cpup((__be16 *) &payload->blob[0]); - if (private_len > (payload->blob_len - 2)) + rc = tpm2_key_decode(payload, options, &blob); + if (rc) { + /* old form */ + blob = payload->blob; + payload->old_format = 1; + } + + /* new format carries keyhandle but old format doesn't */ + if (!options->keyhandle) + return -EINVAL; + + /* must be big enough for at least the two be16 size counts */ + if (payload->blob_len < 4) + return -EINVAL; + + private_len = get_unaligned_be16(blob); + + /* must be big enough for following public_len */ + if (private_len + 2 + 2 > (payload->blob_len)) + return -E2BIG; + + public_len = get_unaligned_be16(blob + 2 + private_len); + if (private_len + 2 + public_len + 2 > payload->blob_len) return -E2BIG; - public_len = be16_to_cpup((__be16 *) &payload->blob[2 + private_len]); blob_len = private_len + public_len + 4; if (blob_len > payload->blob_len) return -E2BIG; @@ -206,7 +399,7 @@ static int tpm2_load_cmd(struct tpm_chip *chip, options->keyauth /* hmac */, TPM_DIGEST_SIZE); - tpm_buf_append(&buf, payload->blob, blob_len); + tpm_buf_append(&buf, blob, blob_len); if (buf.flags & TPM_BUF_OVERFLOW) { rc = -E2BIG; @@ -219,6 +412,8 @@ static int tpm2_load_cmd(struct tpm_chip *chip, (__be32 *) &buf.data[TPM_HEADER_SIZE]); out: + if (blob != payload->blob) + kfree(blob); tpm_buf_destroy(&buf); if (rc > 0)