From patchwork Tue Sep 27 16:49:19 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Evan Green X-Patchwork-Id: 12990962 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 A3F16C07E9D for ; Tue, 27 Sep 2022 16:51:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231653AbiI0Qvj (ORCPT ); Tue, 27 Sep 2022 12:51:39 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52272 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230098AbiI0Qu3 (ORCPT ); Tue, 27 Sep 2022 12:50:29 -0400 Received: from mail-pf1-x430.google.com (mail-pf1-x430.google.com [IPv6:2607:f8b0:4864:20::430]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8B8AD3F1CB for ; Tue, 27 Sep 2022 09:50:21 -0700 (PDT) Received: by mail-pf1-x430.google.com with SMTP id l65so10184122pfl.8 for ; Tue, 27 Sep 2022 09:50:21 -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=oGDeJBld5Cal1lMQoNXrh5yLdLu+9wtYQCQscKtr4hQ=; b=CK2cJTCY9t1dWJQSyb1cj9KrSbH1QCDXX8Z8uqkJLYRe4P6nxNHBB2loaHp7SalTyT hPLe7DA21MNvwvrE5EHjiUQN1FrZmXHk6tkhlLvjmBCHWsbht/S2AFt5QU3I0/ixCQD3 Wl7pc21fL/1xr+v2xoI66oP3xDAUp6EuOqiPQ= 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=oGDeJBld5Cal1lMQoNXrh5yLdLu+9wtYQCQscKtr4hQ=; b=o/1hfMu9Fj0BTs9varzgGgg2Uk6VX+ieqQvcWVgtVGwLQ0nIPMkbydWMciT1OfpVI7 IlvQqq5XZ/WXYeEaTn+PQD6Ac24VLfq/j1cUUlCmKRVqhXIaZ792zmYgn84exK/jAb7L x3e9YgKbup4YodIbObnS30IZ4nPfRhGknZDK0ZL5Y20EBcq5eBssQhL4CQsFrFlYg+tC aIckgMZyhYaHl6p+EuormXWRigOFhSDlwG7qXovd+tLPaKqLQN5iXwQEiLgetSnsWK+4 D9vj5do75mC/EckfPsRGJpXRzu7F1bwPSmno697+BV4BEtKAICuHkdl2lPvd7LXm73x3 dUKg== X-Gm-Message-State: ACrzQf0t+UK0vvrtUPo+REoKUxjd3uLxak1MhzTrGEiUFv6UK3LCaCdf h1ybEOz2Sh8LU0WlzoJyXhIVKg== X-Google-Smtp-Source: AMsMyM7QKe9Pt5aFZiUDzDF2Kq+4A+xDVObbA17L36ZItvYP+CVmr08jdSKU86xrpDtZrLz7irQn4w== X-Received: by 2002:a63:c1:0:b0:439:befa:2ee8 with SMTP id 184-20020a6300c1000000b00439befa2ee8mr24860725pga.108.1664297420455; Tue, 27 Sep 2022 09:50:20 -0700 (PDT) Received: from evgreen-glaptop.lan ([73.231.74.141]) by smtp.gmail.com with ESMTPSA id p13-20020a63950d000000b00434272fe870sm1753509pgd.88.2022.09.27.09.50.18 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 27 Sep 2022 09:50:20 -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 , Len Brown , "Rafael J. Wysocki" Subject: [PATCH v3 08/11] PM: hibernate: Use TPM-backed keys to encrypt image Date: Tue, 27 Sep 2022 09:49:19 -0700 Message-Id: <20220927094559.v3.8.Ibd067e73916b9fae268a5824c2dd037416426af8@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: X-Mailing-List: linux-pm@vger.kernel.org When using encrypted hibernate images, have the TPM create a key for us and seal it. By handing back a sealed blob instead of the raw key, we prevent usermode from being able to decrypt and tamper with the hibernate image on a different machine. We'll also go through the motions of having PCR23 set to a known value at the time of key creation and unsealing. Currently there's nothing that enforces the contents of PCR23 as a condition to unseal the key blob, that will come in a later change. Sourced-from: Matthew Garrett Signed-off-by: Evan Green --- Matthew's incarnation of this patch is at: https://patchwork.kernel.org/project/linux-pm/patch/20210220013255.1083202-9-matthewgarrett@google.com/ Changes in v3: - ENCRYPTED_HIBERNATION needs TRUSTED_KEYS builtin for key_type_trusted. - Remove KEYS dependency since it's covered by TRUSTED_KEYS (Kees) Changes in v2: - Rework load/create_kernel_key() to eliminate a label (Andrey) - Call put_device() needed from calling tpm_default_chip(). kernel/power/Kconfig | 1 + kernel/power/snapenc.c | 207 +++++++++++++++++++++++++++++++++++++++-- kernel/power/user.h | 1 + 3 files changed, 200 insertions(+), 9 deletions(-) diff --git a/kernel/power/Kconfig b/kernel/power/Kconfig index cd574af0b43379..2f8acbd87b34dc 100644 --- a/kernel/power/Kconfig +++ b/kernel/power/Kconfig @@ -96,6 +96,7 @@ config ENCRYPTED_HIBERNATION bool "Encryption support for userspace snapshots" depends on HIBERNATION_SNAPSHOT_DEV depends on CRYPTO_AEAD2=y + depends on TRUSTED_KEYS=y default n help Enable support for kernel-based encryption of hibernation snapshots diff --git a/kernel/power/snapenc.c b/kernel/power/snapenc.c index cb90692d6ab83a..90079f6d4f184b 100644 --- a/kernel/power/snapenc.c +++ b/kernel/power/snapenc.c @@ -4,13 +4,23 @@ #include #include #include +#include +#include #include #include +#include #include #include "power.h" #include "user.h" +/* sha256("To sleep, perchance to dream") */ +static struct tpm_digest known_digest = { .alg_id = TPM_ALG_SHA256, + .digest = {0x92, 0x78, 0x3d, 0x79, 0x2d, 0x00, 0x31, 0xb0, 0x55, 0xf9, + 0x1e, 0x0d, 0xce, 0x83, 0xde, 0x1d, 0xc4, 0xc5, 0x8e, 0x8c, + 0xf1, 0x22, 0x38, 0x6c, 0x33, 0xb1, 0x14, 0xb7, 0xec, 0x05, + 0x5f, 0x49}}; + /* Encrypt more data from the snapshot into the staging area. */ static int snapshot_encrypt_refill(struct snapshot_data *data) { @@ -313,6 +323,12 @@ void snapshot_teardown_encryption(struct snapshot_data *data) { int i; + if (data->key) { + key_revoke(data->key); + key_put(data->key); + data->key = NULL; + } + if (data->aead_req) { aead_request_free(data->aead_req); data->aead_req = NULL; @@ -381,11 +397,83 @@ static int snapshot_setup_encryption_common(struct snapshot_data *data) return rc; } +static int snapshot_create_kernel_key(struct snapshot_data *data) +{ + const struct cred *cred = current_cred(); + struct tpm_digest *digests = NULL; + struct tpm_chip *chip; + struct key *key = NULL; + int ret, i; + /* Create a key sealed by the SRK. */ + char *keyinfo = "new\t32\tkeyhandle=0x81000000"; + + chip = tpm_default_chip(); + if (!chip) + return -ENODEV; + + if (!(tpm_is_tpm2(chip))) { + ret = -ENODEV; + goto out_dev; + } + + ret = tpm_pcr_reset(chip, 23); + if (ret) + goto out; + + digests = kcalloc(chip->nr_allocated_banks, sizeof(struct tpm_digest), + GFP_KERNEL); + if (!digests) { + ret = -ENOMEM; + goto out; + } + + for (i = 0; i <= chip->nr_allocated_banks; i++) { + digests[i].alg_id = chip->allocated_banks[i].alg_id; + if (digests[i].alg_id == known_digest.alg_id) + memcpy(&digests[i], &known_digest, sizeof(known_digest)); + } + + ret = tpm_pcr_extend(chip, 23, digests); + if (ret != 0) + goto out; + + key = key_alloc(&key_type_trusted, "swsusp", GLOBAL_ROOT_UID, + GLOBAL_ROOT_GID, cred, 0, KEY_ALLOC_NOT_IN_QUOTA, + NULL); + + if (IS_ERR(key)) { + ret = PTR_ERR(key); + key = NULL; + goto out; + } + + ret = key_instantiate_and_link(key, keyinfo, strlen(keyinfo) + 1, NULL, + NULL); + if (ret != 0) + goto out; + + data->key = key; + key = NULL; + +out: + if (key) { + key_revoke(key); + key_put(key); + } + + kfree(digests); + tpm_pcr_reset(chip, 23); + +out_dev: + put_device(&chip->dev); + return ret; +} + int snapshot_get_encryption_key(struct snapshot_data *data, struct uswsusp_key_blob __user *key) { - u8 aead_key[SNAPSHOT_ENCRYPTION_KEY_SIZE]; u8 nonce[USWSUSP_KEY_NONCE_SIZE]; + struct trusted_key_payload *payload; int rc; /* Don't pull a random key from a world that can be reset. */ if (data->ready) @@ -399,21 +487,28 @@ int snapshot_get_encryption_key(struct snapshot_data *data, get_random_bytes(nonce, sizeof(nonce)); memcpy(&data->nonce_low, &nonce[0], sizeof(data->nonce_low)); memcpy(&data->nonce_high, &nonce[8], sizeof(data->nonce_high)); - /* Build a random key */ - get_random_bytes(aead_key, sizeof(aead_key)); - rc = crypto_aead_setkey(data->aead_tfm, aead_key, sizeof(aead_key)); + + /* Create a kernel key, and set it. */ + rc = snapshot_create_kernel_key(data); + if (rc) + goto fail; + + payload = data->key->payload.data[0]; + /* Install the key */ + rc = crypto_aead_setkey(data->aead_tfm, payload->key, SNAPSHOT_ENCRYPTION_KEY_SIZE); if (rc) goto fail; - /* Hand the key back to user mode (to be changed!) */ - rc = put_user(sizeof(struct uswsusp_key_blob), &key->blob_len); + /* Hand the key back to user mode in sealed form. */ + rc = put_user(payload->blob_len, &key->blob_len); if (rc) goto fail; - rc = copy_to_user(&key->blob, &aead_key, sizeof(aead_key)); + rc = copy_to_user(&key->blob, &payload->blob, payload->blob_len); if (rc) goto fail; + /* The nonce just gets handed back in the clear. */ rc = copy_to_user(&key->nonce, &nonce, sizeof(nonce)); if (rc) goto fail; @@ -425,10 +520,99 @@ int snapshot_get_encryption_key(struct snapshot_data *data, return rc; } +static int snapshot_load_kernel_key(struct snapshot_data *data, + struct uswsusp_key_blob *blob) +{ + + const struct cred *cred = current_cred(); + char *keytemplate = "load\t%s\tkeyhandle=0x81000000"; + struct tpm_digest *digests = NULL; + char *blobstring = NULL; + char *keyinfo = NULL; + struct tpm_chip *chip; + struct key *key = NULL; + int i, ret; + + chip = tpm_default_chip(); + if (!chip) + return -ENODEV; + + if (!(tpm_is_tpm2(chip))) { + ret = -ENODEV; + goto out_dev; + } + + ret = tpm_pcr_reset(chip, 23); + if (ret) + goto out; + + digests = kcalloc(chip->nr_allocated_banks, sizeof(struct tpm_digest), + GFP_KERNEL); + if (!digests) + goto out; + + for (i = 0; i <= chip->nr_allocated_banks; i++) { + digests[i].alg_id = chip->allocated_banks[i].alg_id; + if (digests[i].alg_id == known_digest.alg_id) + memcpy(&digests[i], &known_digest, sizeof(known_digest)); + } + + ret = tpm_pcr_extend(chip, 23, digests); + if (ret != 0) + goto out; + + blobstring = kmalloc(blob->blob_len * 2, GFP_KERNEL); + if (!blobstring) { + ret = -ENOMEM; + goto out; + } + + bin2hex(blobstring, blob->blob, blob->blob_len); + keyinfo = kasprintf(GFP_KERNEL, keytemplate, blobstring); + if (!keyinfo) { + ret = -ENOMEM; + goto out; + } + + key = key_alloc(&key_type_trusted, "swsusp", GLOBAL_ROOT_UID, + GLOBAL_ROOT_GID, cred, 0, KEY_ALLOC_NOT_IN_QUOTA, + NULL); + + if (IS_ERR(key)) { + ret = PTR_ERR(key); + key = NULL; + goto out; + } + + ret = key_instantiate_and_link(key, keyinfo, strlen(keyinfo) + 1, NULL, + NULL); + if (ret != 0) + goto out; + + data->key = key; + key = NULL; + +out: + if (key) { + key_revoke(key); + key_put(key); + } + + kfree(keyinfo); + kfree(blobstring); + kfree(digests); + tpm_pcr_reset(chip, 23); + +out_dev: + put_device(&chip->dev); + return ret; +} + int snapshot_set_encryption_key(struct snapshot_data *data, struct uswsusp_key_blob __user *key) { struct uswsusp_key_blob blob; + struct trusted_key_payload *payload; int rc; /* It's too late if data's been pushed in. */ @@ -444,13 +628,18 @@ int snapshot_set_encryption_key(struct snapshot_data *data, if (rc) goto crypto_setup_fail; - if (blob.blob_len != sizeof(struct uswsusp_key_blob)) { + if (blob.blob_len > sizeof(key->blob)) { rc = -EINVAL; goto crypto_setup_fail; } + rc = snapshot_load_kernel_key(data, &blob); + if (rc) + goto crypto_setup_fail; + + payload = data->key->payload.data[0]; rc = crypto_aead_setkey(data->aead_tfm, - blob.blob, + payload->key, SNAPSHOT_ENCRYPTION_KEY_SIZE); if (rc) diff --git a/kernel/power/user.h b/kernel/power/user.h index 6823e2eba7ec53..591b30bb213349 100644 --- a/kernel/power/user.h +++ b/kernel/power/user.h @@ -31,6 +31,7 @@ struct snapshot_data { uint64_t crypt_total; uint64_t nonce_low; uint64_t nonce_high; + struct key *key; #endif };