From patchwork Tue Sep 27 16:49:15 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Evan Green X-Patchwork-Id: 12990939 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 F353FC6FA8E for ; Tue, 27 Sep 2022 16:50:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233218AbiI0Quu (ORCPT ); Tue, 27 Sep 2022 12:50:50 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52880 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233237AbiI0QuI (ORCPT ); Tue, 27 Sep 2022 12:50:08 -0400 Received: from mail-pf1-x42b.google.com (mail-pf1-x42b.google.com [IPv6:2607:f8b0:4864:20::42b]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7586E56B98 for ; Tue, 27 Sep 2022 09:50:02 -0700 (PDT) Received: by mail-pf1-x42b.google.com with SMTP id d10so9078528pfh.6 for ; Tue, 27 Sep 2022 09:50:02 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date; bh=5nBgpNKzsdj6MGnq+ieEANFB3+OBuHFrCAD/K8T14mQ=; b=FATo9vuZTut0+55sKRQoF7Q0d0XgoVnuny/cBjrOPP8uEExZK4+44eMjWOk9IZNbzY gR2j7K3dtcsdMBKoLxUHrSEUcBzPp2s95Kdja19042qfwcRSzKS0DxrnyEsxc2H/5Ag4 xKCPqjXswjD3BlK475kLKbfTcyG8uUdqIf4aM= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date; bh=5nBgpNKzsdj6MGnq+ieEANFB3+OBuHFrCAD/K8T14mQ=; b=StDMgbikL3lFM16BmquwnG9OtQrsA1UVJwc/+X9VLz0sDM//v+iak8IdcYPEvI52k5 yY5ASoCSEyLXDQVGxwFvzvDX3PmA5o76TmXhr5eN1vE7jCewdx35BVOmapOLWWhtsLnk jkPkR6S7jE+ZF25KT4xjgjKpNyLZJKHGmR2lCL4328UfvZkPXuFNEVMXFnJyvZJW5ThU IPV2wlapHN2PrDHolzyxyGJBWzNZOpc1z3uuJ3YmhhYf7YcyiBXrk/AsY6dUkGxMOuva 4Hr4fbM+X1N4LCgTu99dAi3yJwhYX6MPURmG1wDkOONR49U4Q5saAxm35KpW4QA3/CW0 dTaQ== X-Gm-Message-State: ACrzQf1kG3vyT5elCHmxoi9Smwb7gVjNZ1dsHIsnz/lnTXUETb7G3gpq AeHlFJZgJ20Ze6h8pSVK9GZIVA== X-Google-Smtp-Source: AMsMyM7xllXajWOzanmc0BzTHihO8Omb0iNFfYp8ARnak/8g6+fx2BcYco5pVM/5jk2u6CAog7Wkhw== X-Received: by 2002:a05:6a00:16c4:b0:535:890:d4a with SMTP id l4-20020a056a0016c400b0053508900d4amr30331740pfc.0.1664297401878; Tue, 27 Sep 2022 09:50:01 -0700 (PDT) Received: from evgreen-glaptop.lan ([73.231.74.141]) by smtp.gmail.com with ESMTPSA id p13-20020a63950d000000b00434272fe870sm1753509pgd.88.2022.09.27.09.49.59 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 27 Sep 2022 09:50:01 -0700 (PDT) From: Evan Green To: linux-kernel@vger.kernel.org Cc: linux-integrity@vger.kernel.org, apronin@chromium.org, dlunev@google.com, jarkko@kernel.org, Pavel Machek , Ben Boeckel , rjw@rjwysocki.net, corbet@lwn.net, linux-pm@vger.kernel.org, zohar@linux.ibm.com, Kees Cook , Eric Biggers , jejb@linux.ibm.com, gwendal@chromium.org, Matthew Garrett , Evan Green , David Howells , James Morris , Paul Moore , "Serge E. Hallyn" , keyrings@vger.kernel.org, linux-security-module@vger.kernel.org Subject: [PATCH v3 04/11] security: keys: trusted: Include TPM2 creation data Date: Tue, 27 Sep 2022 09:49:15 -0700 Message-Id: <20220927094559.v3.4.Ieb1215f598bc9df56b0e29e5977eae4fcca25e15@changeid> X-Mailer: git-send-email 2.31.0 In-Reply-To: <20220927164922.3383711-1-evgreen@chromium.org> References: <20220927164922.3383711-1-evgreen@chromium.org> MIME-Version: 1.0 Precedence: bulk List-ID: In addition to the private key and public key, the TPM2_Create command may also return creation data, a creation hash, and a creation ticket. These fields allow the TPM to attest to the contents of a specified set of PCRs at the time the trusted key was created. Encrypted hibernation will use this to ensure that PCRs settable only by the kernel were set properly at the time of creation, indicating this is an authentic hibernate key. Encode these additional parameters into the ASN.1 created to represent the key blob. The new fields are made optional so that they don't bloat key blobs which don't need them, and to ensure interoperability with old blobs. Signed-off-by: Evan Green --- Changes in v3: - Fix SoB and -- note ordering (Kees) - Add comments describing the TPM2 spec type names for the new fields in tpm2key.asn1 (Kees) - Add len buffer checks in tpm2_key_encode() (Kees) This is a replacement for Matthew's original patch here: https://patchwork.kernel.org/patch/12096489/ That patch was written before the exported key format was switched to ASN.1. This patch accomplishes the same thing (saving, loading, and getting pointers to the creation data) while utilizing the new ASN.1 format. --- include/keys/trusted-type.h | 8 + security/keys/trusted-keys/tpm2key.asn1 | 15 +- security/keys/trusted-keys/trusted_tpm2.c | 216 +++++++++++++++++++--- 3 files changed, 213 insertions(+), 26 deletions(-) diff --git a/include/keys/trusted-type.h b/include/keys/trusted-type.h index 4eb64548a74f1a..209086fed240a5 100644 --- a/include/keys/trusted-type.h +++ b/include/keys/trusted-type.h @@ -22,15 +22,23 @@ #define MAX_BLOB_SIZE 512 #define MAX_PCRINFO_SIZE 64 #define MAX_DIGEST_SIZE 64 +#define MAX_CREATION_DATA 412 +#define MAX_TK 76 struct trusted_key_payload { struct rcu_head rcu; unsigned int key_len; unsigned int blob_len; + unsigned int creation_len; + unsigned int creation_hash_len; + unsigned int tk_len; unsigned char migratable; unsigned char old_format; unsigned char key[MAX_KEY_SIZE + 1]; unsigned char blob[MAX_BLOB_SIZE]; + unsigned char *creation; + unsigned char *creation_hash; + unsigned char *tk; }; struct trusted_key_options { diff --git a/security/keys/trusted-keys/tpm2key.asn1 b/security/keys/trusted-keys/tpm2key.asn1 index f57f869ad60068..608f8d9ca95fa8 100644 --- a/security/keys/trusted-keys/tpm2key.asn1 +++ b/security/keys/trusted-keys/tpm2key.asn1 @@ -7,5 +7,18 @@ TPMKey ::= SEQUENCE { emptyAuth [0] EXPLICIT BOOLEAN OPTIONAL, parent INTEGER ({tpm2_key_parent}), pubkey OCTET STRING ({tpm2_key_pub}), - privkey OCTET STRING ({tpm2_key_priv}) + privkey OCTET STRING ({tpm2_key_priv}), + --- + --- A TPM2B_CREATION_DATA struct as returned from the TPM2_Create command. + --- + creationData [1] EXPLICIT OCTET STRING OPTIONAL ({tpm2_key_creation_data}), + --- + --- A TPM2B_DIGEST of the creationHash as returned from the TPM2_Create + --- command. + --- + creationHash [2] EXPLICIT OCTET STRING OPTIONAL ({tpm2_key_creation_hash}), + --- + --- A TPMT_TK_CREATION ticket as returned from the TPM2_Create command. + --- + creationTk [3] EXPLICIT OCTET STRING OPTIONAL ({tpm2_key_creation_tk}) } diff --git a/security/keys/trusted-keys/trusted_tpm2.c b/security/keys/trusted-keys/trusted_tpm2.c index 2b2c8eb258d5bd..e1388d7d799a36 100644 --- a/security/keys/trusted-keys/trusted_tpm2.c +++ b/security/keys/trusted-keys/trusted_tpm2.c @@ -33,19 +33,54 @@ static int tpm2_key_encode(struct trusted_key_payload *payload, u8 *src, u32 len) { const int SCRATCH_SIZE = PAGE_SIZE; + u8 *end = src + len; u8 *scratch = kmalloc(SCRATCH_SIZE, GFP_KERNEL); u8 *work = scratch, *work1; u8 *end_work = scratch + SCRATCH_SIZE; u8 *priv, *pub; + u8 *creation_data = NULL, *creation_hash = NULL, *creation_tk = NULL; + u16 creation_data_len, creation_hash_len = 0, creation_tk_len = 0; u16 priv_len, pub_len; + int rc; + + if (src + 2 > end) + return -EINVAL; priv_len = get_unaligned_be16(src) + 2; priv = src; src += priv_len; - + if (src + 2 > end) + return -EINVAL; pub_len = get_unaligned_be16(src) + 2; pub = src; + src += pub_len; + if (src + 2 > end) + return -EINVAL; + creation_data_len = get_unaligned_be16(src); + if (creation_data_len) { + creation_data_len += 2; + creation_data = src; + src += creation_data_len; + if (src + 2 > end) + return -EINVAL; + + creation_hash_len = get_unaligned_be16(src) + 2; + creation_hash = src; + src += creation_hash_len; + if (src + 2 > end) + return -EINVAL; + + /* + * The creation ticket (TPMT_TK_CREATION) consists of a 2 byte + * tag, 4 byte handle, and then a TPM2B_DIGEST, which is a 2 + * byte length followed by data. + */ + creation_tk_len = get_unaligned_be16(src + 6) + 8; + creation_tk = src; + if (creation_tk + creation_tk_len > end) + return -EINVAL; + } if (!scratch) return -ENOMEM; @@ -63,26 +98,81 @@ static int tpm2_key_encode(struct trusted_key_payload *payload, } /* - * Assume both octet strings will encode to a 2 byte definite length + * Assume each octet string will encode to a 2 byte definite length. + * Each optional octet string consumes one extra byte. * - * Note: For a well behaved TPM, this warning should never - * trigger, so if it does there's something nefarious going on + * 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; + if (WARN(work - scratch + pub_len + priv_len + creation_data_len + + creation_hash_len + creation_tk_len + (7 * 5) + 3 > + SCRATCH_SIZE, + "BUG: scratch buffer is too small")) { + rc = -EINVAL; + goto err; + } 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); + if (creation_data_len) { + u8 *scratch2 = kmalloc(SCRATCH_SIZE, GFP_KERNEL); + u8 *work2; + u8 *end_work2 = scratch2 + SCRATCH_SIZE; + + if (!scratch2) { + rc = -ENOMEM; + goto err; + } + + work2 = asn1_encode_octet_string(scratch2, + end_work2, + creation_data, + creation_data_len); + + work = asn1_encode_tag(work, + end_work, + 1, + scratch2, + work2 - scratch2); + + work2 = asn1_encode_octet_string(scratch2, + end_work2, + creation_hash, + creation_hash_len); + + work = asn1_encode_tag(work, + end_work, + 2, + scratch2, + work2 - scratch2); + + work2 = asn1_encode_octet_string(scratch2, + end_work2, + creation_tk, + creation_tk_len); + + work = asn1_encode_tag(work, + end_work, + 3, + scratch2, + work2 - scratch2); + + kfree(scratch2); + } 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); + if (WARN(IS_ERR(work1), "BUG: ASN.1 encoder failed")) { + rc = PTR_ERR(work1); + goto err; + } return work1 - payload->blob; +err: + kfree(scratch); + return rc; } struct tpm2_key_context { @@ -91,15 +181,21 @@ struct tpm2_key_context { u32 pub_len; const u8 *priv; u32 priv_len; + const u8 *creation_data; + u32 creation_data_len; + const u8 *creation_hash; + u32 creation_hash_len; + const u8 *creation_tk; + u32 creation_tk_len; }; static int tpm2_key_decode(struct trusted_key_payload *payload, - struct trusted_key_options *options, - u8 **buf) + struct trusted_key_options *options) { + u64 data_len; int ret; struct tpm2_key_context ctx; - u8 *blob; + u8 *blob, *buf; memset(&ctx, 0, sizeof(ctx)); @@ -108,21 +204,57 @@ static int tpm2_key_decode(struct trusted_key_payload *payload, if (ret < 0) return ret; - if (ctx.priv_len + ctx.pub_len > MAX_BLOB_SIZE) + data_len = ctx.priv_len + ctx.pub_len + ctx.creation_data_len + + ctx.creation_hash_len + ctx.creation_tk_len; + + if (data_len > MAX_BLOB_SIZE) return -EINVAL; - blob = kmalloc(ctx.priv_len + ctx.pub_len + 4, GFP_KERNEL); - if (!blob) + buf = kmalloc(data_len + 4, GFP_KERNEL); + if (!buf) return -ENOMEM; - *buf = blob; + blob = buf; options->keyhandle = ctx.parent; memcpy(blob, ctx.priv, ctx.priv_len); blob += ctx.priv_len; memcpy(blob, ctx.pub, ctx.pub_len); + blob += ctx.pub_len; + if (ctx.creation_data_len) { + memcpy(blob, ctx.creation_data, ctx.creation_data_len); + blob += ctx.creation_data_len; + } + + if (ctx.creation_hash_len) { + memcpy(blob, ctx.creation_hash, ctx.creation_hash_len); + blob += ctx.creation_hash_len; + } + + if (ctx.creation_tk_len) { + memcpy(blob, ctx.creation_tk, ctx.creation_tk_len); + blob += ctx.creation_tk_len; + } + + /* + * Copy the buffer back into the payload blob since the creation + * info will be used after loading. + */ + payload->blob_len = blob - buf; + memcpy(payload->blob, buf, payload->blob_len); + if (ctx.creation_data_len) { + payload->creation = payload->blob + ctx.priv_len + ctx.pub_len; + payload->creation_len = ctx.creation_data_len; + payload->creation_hash = payload->creation + ctx.creation_data_len; + payload->creation_hash_len = ctx.creation_hash_len; + payload->tk = payload->creation_hash + + payload->creation_hash_len; + + payload->tk_len = ctx.creation_tk_len; + } + kfree(buf); return 0; } @@ -185,6 +317,42 @@ int tpm2_key_priv(void *context, size_t hdrlen, return 0; } +int tpm2_key_creation_data(void *context, size_t hdrlen, + unsigned char tag, + const void *value, size_t vlen) +{ + struct tpm2_key_context *ctx = context; + + ctx->creation_data = value; + ctx->creation_data_len = vlen; + + return 0; +} + +int tpm2_key_creation_hash(void *context, size_t hdrlen, + unsigned char tag, + const void *value, size_t vlen) +{ + struct tpm2_key_context *ctx = context; + + ctx->creation_hash = value; + ctx->creation_hash_len = vlen; + + return 0; +} + +int tpm2_key_creation_tk(void *context, size_t hdrlen, + unsigned char tag, + const void *value, size_t vlen) +{ + struct tpm2_key_context *ctx = context; + + ctx->creation_tk = value; + ctx->creation_tk_len = vlen; + + return 0; +} + /** * tpm_buf_append_auth() - append TPMS_AUTH_COMMAND to the buffer. * @@ -229,6 +397,7 @@ int tpm2_seal_trusted(struct tpm_chip *chip, struct trusted_key_options *options) { int blob_len = 0; + unsigned int offset; struct tpm_buf buf; u32 hash; u32 flags; @@ -317,13 +486,14 @@ int tpm2_seal_trusted(struct tpm_chip *chip, rc = -E2BIG; goto out; } - if (tpm_buf_length(&buf) < TPM_HEADER_SIZE + 4 + blob_len) { + offset = TPM_HEADER_SIZE + 4; + if (tpm_buf_length(&buf) < offset + blob_len) { rc = -EFAULT; goto out; } blob_len = tpm2_key_encode(payload, options, - &buf.data[TPM_HEADER_SIZE + 4], + &buf.data[offset], blob_len); out: @@ -370,13 +540,11 @@ static int tpm2_load_cmd(struct tpm_chip *chip, int rc; u32 attrs; - rc = tpm2_key_decode(payload, options, &blob); - if (rc) { - /* old form */ - blob = payload->blob; + rc = tpm2_key_decode(payload, options); + if (rc) payload->old_format = 1; - } + blob = payload->blob; /* new format carries keyhandle but old format doesn't */ if (!options->keyhandle) return -EINVAL; @@ -433,8 +601,6 @@ 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)