From patchwork Thu Nov 3 18:01:10 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Evan Green X-Patchwork-Id: 621308 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 A6FE1C433FE for ; Thu, 3 Nov 2022 18:04:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230165AbiKCSEQ (ORCPT ); Thu, 3 Nov 2022 14:04:16 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36946 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230182AbiKCSEA (ORCPT ); Thu, 3 Nov 2022 14:04:00 -0400 Received: from mail-pj1-x102b.google.com (mail-pj1-x102b.google.com [IPv6:2607:f8b0:4864:20::102b]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6B13A23396 for ; Thu, 3 Nov 2022 11:01:40 -0700 (PDT) Received: by mail-pj1-x102b.google.com with SMTP id gw22so2394917pjb.3 for ; Thu, 03 Nov 2022 11:01:40 -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 :message-id:reply-to; bh=WfQ8/CAL4S026DtWAnZscysHYhGEE1wVieDh82Tdr08=; b=I18iC2yKrg6+LAoc5oeMqbZb2+EuFmwElNbhB+mUlPs0W89QCjCZPKV2w4PrgavOFa kFnCeYud6UfFP8OvHBqunAtTVF/rbF13qqrG9H3qMTi1Ygmz7MlR/y2vna8amHhP4LOY rbOH9iNj9wvWvP8Uegka7N+SJm0ekA0q8PY+M= 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:message-id:reply-to; bh=WfQ8/CAL4S026DtWAnZscysHYhGEE1wVieDh82Tdr08=; b=U51xbjWGFXJxQtcQqQ++SM28vKlunZoWfpcdRF1QYMxgie7ksxv4kwoViiUO9vkb2b 6UsP1Xp8onIznAcERXqfFNvVvlc97RK4FK3Huj9vVK67P9n4WB+7mnASagW49RbOwjkS AE5LNXTFJrHTm0AKe/dV+RfDXOaE9cWWR2w5CRcRcvaNzt7Vm0JMj8RSk7Ib+E+yjRyz Y2eZNT7ljPlFd5Yh+KbdA6rrCO7q+nnrOfFynDp+Ch4LaoRKhJ+jjAUy8MyurLgE+u2g b7tZTab0m9hh6TsCsV/Sau9ajXmGFi5//56Ozx7eEpZsqTB1W+E25evT2Q/hql2YRU9p A5Ig== X-Gm-Message-State: ACrzQf3ZFj+O6/LawqZjLTwPnJkZKcehMxSaBOF7+k+8uCtWIYr9qB9L 5CfjcV17qDC1kru80hFSNXoUfQ== X-Google-Smtp-Source: AMsMyM4xq4UAu0O7V+ZZtlC479QmsjfT8xWTYxEDk8MFu2zZxJDctc12i9fXITGj7vI9jGerYFNLzQ== X-Received: by 2002:a17:90a:f484:b0:213:d200:e956 with SMTP id bx4-20020a17090af48400b00213d200e956mr25810351pjb.40.1667498500047; Thu, 03 Nov 2022 11:01:40 -0700 (PDT) Received: from evgreen-glaptop.lan ([98.45.28.95]) by smtp.gmail.com with ESMTPSA id t12-20020a1709027fcc00b00177fb862a87sm1000277plb.20.2022.11.03.11.01.38 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 03 Nov 2022 11:01:39 -0700 (PDT) From: Evan Green To: linux-kernel@vger.kernel.org Cc: corbet@lwn.net, linux-pm@vger.kernel.org, rjw@rjwysocki.net, gwendal@chromium.org, apronin@chromium.org, Pavel Machek , Kees Cook , Matthew Garrett , linux-integrity@vger.kernel.org, jejb@linux.ibm.com, zohar@linux.ibm.com, dlunev@google.com, Eric Biggers , Ben Boeckel , jarkko@kernel.org, Evan Green , Jason Gunthorpe , Peter Huewe Subject: [PATCH v4 02/11] tpm: Export and rename tpm2_find_and_validate_cc() Date: Thu, 3 Nov 2022 11:01:10 -0700 Message-Id: <20221103105558.v4.2.I7bbedcf5efd3f1c72c32d6002faed086c5ed31c7@changeid> X-Mailer: git-send-email 2.38.1.431.g37b22c650d-goog In-Reply-To: <20221103180120.752659-1-evgreen@chromium.org> References: <20221103180120.752659-1-evgreen@chromium.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org Export tpm_find_and_validate_cc() since it will be needed by an upcoming change allowing access to certain PCRs to be restricted to the kernel. In order to export it consistently, and because it's a tpm2-only function, rename it to tpm2_find_and_validate_cc(). Signed-off-by: Evan Green --- (no changes since v3) Changes in v3: - Split find_and_validate_cc() export to its own patch (Jarkko) - Rename tpm_find_and_validate_cc() to tpm2_find_and_validate_cc(). drivers/char/tpm/tpm.h | 3 +++ drivers/char/tpm/tpm2-space.c | 8 ++++---- 2 files changed, 7 insertions(+), 4 deletions(-) diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h index 24ee4e1cc452a0..f1e0f490176f01 100644 --- a/drivers/char/tpm/tpm.h +++ b/drivers/char/tpm/tpm.h @@ -231,6 +231,9 @@ int tpm2_find_cc(struct tpm_chip *chip, u32 cc); int tpm2_init_space(struct tpm_space *space, unsigned int buf_size); void tpm2_del_space(struct tpm_chip *chip, struct tpm_space *space); void tpm2_flush_space(struct tpm_chip *chip); +int tpm2_find_and_validate_cc(struct tpm_chip *chip, + struct tpm_space *space, + const void *cmd, size_t len); int tpm2_prepare_space(struct tpm_chip *chip, struct tpm_space *space, u8 *cmd, size_t cmdsiz); int tpm2_commit_space(struct tpm_chip *chip, struct tpm_space *space, void *buf, diff --git a/drivers/char/tpm/tpm2-space.c b/drivers/char/tpm/tpm2-space.c index ffb35f0154c16c..ca34cc006e7f8d 100644 --- a/drivers/char/tpm/tpm2-space.c +++ b/drivers/char/tpm/tpm2-space.c @@ -262,9 +262,9 @@ static int tpm2_map_command(struct tpm_chip *chip, u32 cc, u8 *cmd) return 0; } -static int tpm_find_and_validate_cc(struct tpm_chip *chip, - struct tpm_space *space, - const void *cmd, size_t len) +int tpm2_find_and_validate_cc(struct tpm_chip *chip, + struct tpm_space *space, + const void *cmd, size_t len) { const struct tpm_header *header = (const void *)cmd; int i; @@ -306,7 +306,7 @@ int tpm2_prepare_space(struct tpm_chip *chip, struct tpm_space *space, u8 *cmd, if (!space) return 0; - cc = tpm_find_and_validate_cc(chip, space, cmd, cmdsiz); + cc = tpm2_find_and_validate_cc(chip, space, cmd, cmdsiz); if (cc < 0) return cc; From patchwork Thu Nov 3 18:01:11 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Evan Green X-Patchwork-Id: 621307 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 CFCF1C43217 for ; Thu, 3 Nov 2022 18:04:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230489AbiKCSEs (ORCPT ); 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Thu, 03 Nov 2022 11:01:41 -0700 (PDT) From: Evan Green To: linux-kernel@vger.kernel.org Cc: corbet@lwn.net, linux-pm@vger.kernel.org, rjw@rjwysocki.net, gwendal@chromium.org, apronin@chromium.org, Pavel Machek , Kees Cook , Matthew Garrett , linux-integrity@vger.kernel.org, jejb@linux.ibm.com, zohar@linux.ibm.com, dlunev@google.com, Eric Biggers , Ben Boeckel , jarkko@kernel.org, Matthew Garrett , Matthew Garrett , Evan Green , Jason Gunthorpe , Peter Huewe Subject: [PATCH v4 03/11] tpm: Allow PCR 23 to be restricted to kernel-only use Date: Thu, 3 Nov 2022 11:01:11 -0700 Message-Id: <20221103105558.v4.3.I9ded8c8caad27403e9284dfc78ad6cbd845bc98d@changeid> X-Mailer: git-send-email 2.38.1.431.g37b22c650d-goog In-Reply-To: <20221103180120.752659-1-evgreen@chromium.org> References: <20221103180120.752659-1-evgreen@chromium.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org From: Matthew Garrett Introduce a new Kconfig, TCG_TPM_RESTRICT_PCR, which if enabled restricts usermode's ability to extend or reset PCR 23. Under certain circumstances it might be desirable to enable the creation of TPM-backed secrets that are only accessible to the kernel. In an ideal world this could be achieved by using TPM localities, but these don't appear to be available on consumer systems. An alternative is to simply block userland from modifying one of the resettable PCRs, leaving it available to the kernel. If the kernel ensures that no userland can access the TPM while it is carrying out work, it can reset PCR 23, extend it to an arbitrary value, create or load a secret, and then reset the PCR again. Even if userland somehow obtains the sealed material, it will be unable to unseal it since PCR 23 will never be in the appropriate state. This Kconfig is only properly supported for systems with TPM2 devices. For systems with TPM1 devices, having this Kconfig enabled completely restricts usermode's access to the TPM. TPM1 contains support for tunnelled transports, which usermode could use to smuggle commands through that this Kconfig is attempting to restrict. Link: https://lore.kernel.org/lkml/20210220013255.1083202-3-matthewgarrett@google.com/ Signed-off-by: Matthew Garrett Signed-off-by: Evan Green --- Changes in v4: - Augment the commit message (Jarkko) Changes in v3: - Fix up commit message (Jarkko) - tpm2_find_and_validate_cc() was split (Jarkko) - Simply fully restrict TPM1 since v2 failed to account for tunnelled transport sessions (Stefan and Jarkko). Changes in v2: - Fixed sparse warnings drivers/char/tpm/Kconfig | 12 ++++++++++++ drivers/char/tpm/tpm-dev-common.c | 8 ++++++++ drivers/char/tpm/tpm.h | 19 +++++++++++++++++++ drivers/char/tpm/tpm1-cmd.c | 13 +++++++++++++ drivers/char/tpm/tpm2-cmd.c | 22 ++++++++++++++++++++++ 5 files changed, 74 insertions(+) diff --git a/drivers/char/tpm/Kconfig b/drivers/char/tpm/Kconfig index 927088b2c3d3f2..c8ed54c66e399a 100644 --- a/drivers/char/tpm/Kconfig +++ b/drivers/char/tpm/Kconfig @@ -211,4 +211,16 @@ config TCG_FTPM_TEE This driver proxies for firmware TPM running in TEE. source "drivers/char/tpm/st33zp24/Kconfig" + +config TCG_TPM_RESTRICT_PCR + bool "Restrict userland access to PCR 23" + depends on TCG_TPM + help + If set, block userland from extending or resetting PCR 23. This allows it + to be restricted to in-kernel use, preventing userland from being able to + make use of data sealed to the TPM by the kernel. This is required for + secure hibernation support, but should be left disabled if any userland + may require access to PCR23. This is a TPM2-only feature, and if enabled + on a TPM1 machine will cause all usermode TPM commands to return EPERM due + to the complications introduced by tunnelled sessions in TPM1.2. endif # TCG_TPM diff --git a/drivers/char/tpm/tpm-dev-common.c b/drivers/char/tpm/tpm-dev-common.c index dc4c0a0a512903..7a4e618c7d1942 100644 --- a/drivers/char/tpm/tpm-dev-common.c +++ b/drivers/char/tpm/tpm-dev-common.c @@ -198,6 +198,14 @@ ssize_t tpm_common_write(struct file *file, const char __user *buf, priv->response_read = false; *off = 0; + if (priv->chip->flags & TPM_CHIP_FLAG_TPM2) + ret = tpm2_cmd_restricted(priv->chip, priv->data_buffer, size); + else + ret = tpm1_cmd_restricted(priv->chip, priv->data_buffer, size); + + if (ret) + goto out; + /* * If in nonblocking mode schedule an async job to send * the command return the size. diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h index f1e0f490176f01..c0845e3f9eda17 100644 --- a/drivers/char/tpm/tpm.h +++ b/drivers/char/tpm/tpm.h @@ -245,4 +245,23 @@ void tpm_bios_log_setup(struct tpm_chip *chip); void tpm_bios_log_teardown(struct tpm_chip *chip); int tpm_dev_common_init(void); void tpm_dev_common_exit(void); + +#ifdef CONFIG_TCG_TPM_RESTRICT_PCR +#define TPM_RESTRICTED_PCR 23 + +int tpm1_cmd_restricted(struct tpm_chip *chip, u8 *buffer, size_t size); +int tpm2_cmd_restricted(struct tpm_chip *chip, u8 *buffer, size_t size); +#else +static inline int tpm1_cmd_restricted(struct tpm_chip *chip, u8 *buffer, + size_t size) +{ + return 0; +} + +static inline int tpm2_cmd_restricted(struct tpm_chip *chip, u8 *buffer, + size_t size) +{ + return 0; +} +#endif #endif diff --git a/drivers/char/tpm/tpm1-cmd.c b/drivers/char/tpm/tpm1-cmd.c index cf64c738510529..1869e89215fcb9 100644 --- a/drivers/char/tpm/tpm1-cmd.c +++ b/drivers/char/tpm/tpm1-cmd.c @@ -811,3 +811,16 @@ int tpm1_get_pcr_allocation(struct tpm_chip *chip) return 0; } + +#ifdef CONFIG_TCG_TPM_RESTRICT_PCR +int tpm1_cmd_restricted(struct tpm_chip *chip, u8 *buffer, size_t size) +{ + /* + * Restrict all usermode commands on TPM1.2. Ideally we'd just restrict + * TPM_ORD_PCR_EXTEND and TPM_ORD_PCR_RESET, but TPM1.2 also supports + * tunnelled transport sessions where the kernel would be unable to filter + * commands. + */ + return -EPERM; +} +#endif diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c index 303ce2ea02a4b0..e0503cfd7bcfee 100644 --- a/drivers/char/tpm/tpm2-cmd.c +++ b/drivers/char/tpm/tpm2-cmd.c @@ -778,3 +778,25 @@ int tpm2_find_cc(struct tpm_chip *chip, u32 cc) return -1; } + +#ifdef CONFIG_TCG_TPM_RESTRICT_PCR +int tpm2_cmd_restricted(struct tpm_chip *chip, u8 *buffer, size_t size) +{ + int cc = tpm2_find_and_validate_cc(chip, NULL, buffer, size); + __be32 *handle; + + switch (cc) { + case TPM2_CC_PCR_EXTEND: + case TPM2_CC_PCR_RESET: + if (size < (TPM_HEADER_SIZE + sizeof(u32))) + return -EINVAL; + + handle = (__be32 *)&buffer[TPM_HEADER_SIZE]; + if (be32_to_cpu(*handle) == TPM_RESTRICTED_PCR) + return -EPERM; + break; + } + + return 0; +} +#endif From patchwork Thu Nov 3 18:01:14 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Evan Green X-Patchwork-Id: 621306 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 81E03C433FE for ; Thu, 3 Nov 2022 18:04:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231566AbiKCSEz (ORCPT ); Thu, 3 Nov 2022 14:04:55 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42966 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230147AbiKCSEJ (ORCPT ); Thu, 3 Nov 2022 14:04:09 -0400 Received: from mail-pl1-x62e.google.com (mail-pl1-x62e.google.com [IPv6:2607:f8b0:4864:20::62e]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3A77923BD9 for ; Thu, 3 Nov 2022 11:01:49 -0700 (PDT) Received: by mail-pl1-x62e.google.com with SMTP id j12so2663548plj.5 for ; Thu, 03 Nov 2022 11:01:49 -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 :message-id:reply-to; bh=gmRSuvtVdtePdWlhI+qYfa3jkKLy3lL4+DZtMxIoK0I=; b=oCaws+kyFllbssoMBrcVaWuoHdvEerAiSWJdhgX2/4syWfjhj1QKDY3vH01nEt1vCn 6+epL9ht0qOEZlWyuffULkcOVrYNaQtUOQrp36inBYo1C6HudOiAwjNrVKMTzQk3Tt92 d2ijSkQ/5cW7KlfiSiDR6E4oiBjCKBzhXuCcE= 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:message-id:reply-to; bh=gmRSuvtVdtePdWlhI+qYfa3jkKLy3lL4+DZtMxIoK0I=; b=PDplTLVxDRG9OOoTJ4nyRmuKXVub6GW3vPSBGVbEdznFNQutgElAqeg/xQqkwzaWBP C80p7ChJuCY2vXXXTAK93cCnwHY6P/RTfr8PkCOq5cPprZ2HO7fiYAOk5xHRbV9Ot9+D ugMBGRyrcWxX5Ntd5Pa/AGm4H0zXzi/DCM3YjTjpB4Cab5iCIHjcOcbnBpkzw9g5rRH1 GKspv9SIZmrFE5LHJcfVynmvI0djoM5WRznzsOjCTf/V1K8nLtCuFUKmWoNjT/RtI7da LLRbkXWMWyvGoXXtTDAHK75EQFEVADLMfo3LIWO3EXfM46/+svJhi3+7R30zAQa+0bE2 f5Ow== X-Gm-Message-State: ACrzQf0UfUyEY7of/s6DGKOyTHCH/z0GgtZflpQXH6YfSfQAwNcOfIXn OR258T9+00eK6Y10djhEiM4FtmfYk4p1lvQF X-Google-Smtp-Source: AMsMyM5Pk1O0MR+psJrfWUlI0d5V4npjm5wYkPwm+68nIz1aVymvhFA0VHcpQUBKzObFd3rMSFoLEw== X-Received: by 2002:a17:90b:278b:b0:213:c2f2:6ca1 with SMTP id pw11-20020a17090b278b00b00213c2f26ca1mr27478944pjb.103.1667498509274; Thu, 03 Nov 2022 11:01:49 -0700 (PDT) Received: from evgreen-glaptop.lan ([98.45.28.95]) by smtp.gmail.com with ESMTPSA id t12-20020a1709027fcc00b00177fb862a87sm1000277plb.20.2022.11.03.11.01.47 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 03 Nov 2022 11:01:48 -0700 (PDT) From: Evan Green To: linux-kernel@vger.kernel.org Cc: corbet@lwn.net, linux-pm@vger.kernel.org, rjw@rjwysocki.net, gwendal@chromium.org, apronin@chromium.org, Pavel Machek , Kees Cook , Matthew Garrett , linux-integrity@vger.kernel.org, jejb@linux.ibm.com, zohar@linux.ibm.com, dlunev@google.com, Eric Biggers , Ben Boeckel , jarkko@kernel.org, Evan Green , Matthew Garrett , David Howells , James Morris , Matthew Garrett , Paul Moore , "Serge E. Hallyn" , axelj , keyrings@vger.kernel.org, linux-security-module@vger.kernel.org Subject: [PATCH v4 06/11] security: keys: trusted: Verify creation data Date: Thu, 3 Nov 2022 11:01:14 -0700 Message-Id: <20221103105558.v4.6.I6cdb522cb5ea28fcd1e35b4cd92cbd067f99269a@changeid> X-Mailer: git-send-email 2.38.1.431.g37b22c650d-goog In-Reply-To: <20221103180120.752659-1-evgreen@chromium.org> References: <20221103180120.752659-1-evgreen@chromium.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org If a loaded key contains creation data, ask the TPM to verify that creation data. This allows users like encrypted hibernate to know that the loaded and parsed creation data has not been tampered with. Suggested-by: Matthew Garrett Signed-off-by: Evan Green --- Source material for this change is at: https://patchwork.kernel.org/project/linux-pm/patch/20210220013255.1083202-9-matthewgarrett@google.com/ (no changes since v3) Changes in v3: - Changed funky tag to suggested-by (Kees). Matthew, holler if you want something different. Changes in v2: - Adjust hash len by 2 due to new ASN.1 storage, and add underflow check. include/linux/tpm.h | 1 + security/keys/trusted-keys/trusted_tpm2.c | 77 ++++++++++++++++++++++- 2 files changed, 77 insertions(+), 1 deletion(-) diff --git a/include/linux/tpm.h b/include/linux/tpm.h index 70134e6551745f..9c2ee3e30ffa5d 100644 --- a/include/linux/tpm.h +++ b/include/linux/tpm.h @@ -224,6 +224,7 @@ enum tpm2_command_codes { TPM2_CC_SELF_TEST = 0x0143, TPM2_CC_STARTUP = 0x0144, TPM2_CC_SHUTDOWN = 0x0145, + TPM2_CC_CERTIFYCREATION = 0x014A, TPM2_CC_NV_READ = 0x014E, TPM2_CC_CREATE = 0x0153, TPM2_CC_LOAD = 0x0157, diff --git a/security/keys/trusted-keys/trusted_tpm2.c b/security/keys/trusted-keys/trusted_tpm2.c index a7ad83bc0e5396..c76a1b5a2e8471 100644 --- a/security/keys/trusted-keys/trusted_tpm2.c +++ b/security/keys/trusted-keys/trusted_tpm2.c @@ -703,6 +703,74 @@ static int tpm2_unseal_cmd(struct tpm_chip *chip, return rc; } +/** + * tpm2_certify_creation() - execute a TPM2_CertifyCreation command + * + * @chip: TPM chip to use + * @payload: the key data in clear and encrypted form + * @blob_handle: the loaded TPM handle of the key + * + * Return: 0 on success + * -EINVAL on tpm error status + * < 0 error from tpm_send or tpm_buf_init + */ +static int tpm2_certify_creation(struct tpm_chip *chip, + struct trusted_key_payload *payload, + u32 blob_handle) +{ + struct tpm_header *head; + struct tpm_buf buf; + int rc; + + rc = tpm_buf_init(&buf, TPM2_ST_SESSIONS, TPM2_CC_CERTIFYCREATION); + if (rc) + return rc; + + /* Use TPM_RH_NULL for signHandle */ + tpm_buf_append_u32(&buf, 0x40000007); + + /* Object handle */ + tpm_buf_append_u32(&buf, blob_handle); + + /* Auth */ + tpm_buf_append_u32(&buf, 9); + tpm_buf_append_u32(&buf, TPM2_RS_PW); + tpm_buf_append_u16(&buf, 0); + tpm_buf_append_u8(&buf, 0); + tpm_buf_append_u16(&buf, 0); + + /* Qualifying data */ + tpm_buf_append_u16(&buf, 0); + + /* Creation data hash */ + if (payload->creation_hash_len < 2) { + rc = -EINVAL; + goto out; + } + + tpm_buf_append_u16(&buf, payload->creation_hash_len - 2); + tpm_buf_append(&buf, payload->creation_hash + 2, + payload->creation_hash_len - 2); + + /* signature scheme */ + tpm_buf_append_u16(&buf, TPM_ALG_NULL); + + /* creation ticket */ + tpm_buf_append(&buf, payload->tk, payload->tk_len); + + rc = tpm_transmit_cmd(chip, &buf, 6, "certifying creation data"); + if (rc) + goto out; + + head = (struct tpm_header *)buf.data; + + if (be32_to_cpu(head->return_code) != TPM2_RC_SUCCESS) + rc = -EINVAL; +out: + tpm_buf_destroy(&buf); + return rc; +} + /** * tpm2_unseal_trusted() - unseal the payload of a trusted key * @@ -728,8 +796,15 @@ int tpm2_unseal_trusted(struct tpm_chip *chip, goto out; rc = tpm2_unseal_cmd(chip, payload, options, blob_handle); - tpm2_flush_context(chip, blob_handle); + if (rc) + goto flush; + + if (payload->creation_len) + rc = tpm2_certify_creation(chip, payload, blob_handle); + +flush: + tpm2_flush_context(chip, blob_handle); out: tpm_put_ops(chip); From patchwork Thu Nov 3 18:01:15 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Evan Green X-Patchwork-Id: 621305 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 831ABC4332F for ; Thu, 3 Nov 2022 18:05:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230056AbiKCSFD (ORCPT ); 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Thu, 03 Nov 2022 11:01:51 -0700 (PDT) From: Evan Green To: linux-kernel@vger.kernel.org Cc: corbet@lwn.net, linux-pm@vger.kernel.org, rjw@rjwysocki.net, gwendal@chromium.org, apronin@chromium.org, Pavel Machek , Kees Cook , Matthew Garrett , linux-integrity@vger.kernel.org, jejb@linux.ibm.com, zohar@linux.ibm.com, dlunev@google.com, Eric Biggers , Ben Boeckel , jarkko@kernel.org, Evan Green , Len Brown , "Rafael J. Wysocki" Subject: [PATCH v4 07/11] PM: hibernate: Add kernel-based encryption Date: Thu, 3 Nov 2022 11:01:15 -0700 Message-Id: <20221103105558.v4.7.Ifff11e11797a1bde0297577ecb2f7ebb3f9e2b04@changeid> X-Mailer: git-send-email 2.38.1.431.g37b22c650d-goog In-Reply-To: <20221103180120.752659-1-evgreen@chromium.org> References: <20221103180120.752659-1-evgreen@chromium.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org Enabling the kernel to be able to do encryption and integrity checks on the hibernate image prevents a malicious userspace from escalating to kernel execution via hibernation resume. As a first step toward this, add the scaffolding needed for the kernel to do AEAD encryption on the hibernate image, giving us both secrecy and integrity. We currently hardwire the encryption to be gcm(aes) in 16-page chunks. This strikes a balance between minimizing the authentication tag overhead on storage, and keeping a modest sized staging buffer. With this chunk size, we'd generate 2MB of authentication tag data on an 8GB hiberation image. The encryption currently sits on top of the core snapshot functionality, wired up only if requested in the uswsusp path. This could potentially be lowered into the common snapshot code given a mechanism to stitch the key contents into the image itself. To avoid forcing usermode to deal with sequencing the auth tags in with the data, we stitch the auth tags in to the snapshot after each chunk of pages. This complicates the read and write functions, as we roll through the flow of (for read) 1) fill the staging buffer with encrypted data, 2) feed the data pages out to user mode, 3) feed the tag out to user mode. To avoid having each syscall return a small and variable amount of data, the encrypted versions of read and write operate in a loop, allowing an arbitrary amount of data through per syscall. One alternative that would simplify things here would be a streaming interface to AEAD. Then we could just stream the entire hibernate image through directly, and handle a single tag at the end. However there is a school of thought that suggests a streaming interface to AEAD represents a loaded footgun, as it tempts the caller to act on the decrypted but not yet verified data, defeating the purpose of AEAD. With this change alone, we don't actually protect ourselves from malicious userspace at all, since we kindly hand the key in plaintext to usermode. In later changes, we'll seal the key with the TPM before handing it back to usermode, so they can't decrypt or tamper with the key themselves. Signed-off-by: Evan Green --- Changes in v4: - Local ordering and whitespace changes (Jarkko) Documentation/power/userland-swsusp.rst | 8 + include/uapi/linux/suspend_ioctls.h | 15 +- kernel/power/Kconfig | 13 + kernel/power/Makefile | 1 + kernel/power/snapenc.c | 493 ++++++++++++++++++++++++ kernel/power/user.c | 40 +- kernel/power/user.h | 103 +++++ 7 files changed, 661 insertions(+), 12 deletions(-) create mode 100644 kernel/power/snapenc.c create mode 100644 kernel/power/user.h diff --git a/Documentation/power/userland-swsusp.rst b/Documentation/power/userland-swsusp.rst index 1cf62d80a9ca10..f759915a78ce98 100644 --- a/Documentation/power/userland-swsusp.rst +++ b/Documentation/power/userland-swsusp.rst @@ -115,6 +115,14 @@ SNAPSHOT_S2RAM to resume the system from RAM if there's enough battery power or restore its state on the basis of the saved suspend image otherwise) +SNAPSHOT_ENABLE_ENCRYPTION + Enables encryption of the hibernate image within the kernel. Upon suspend + (ie when the snapshot device was opened for reading), returns a blob + representing the random encryption key the kernel created to encrypt the + hibernate image with. Upon resume (ie when the snapshot device was opened + for writing), receives a blob from usermode containing the key material + previously returned during hibernate. + The device's read() operation can be used to transfer the snapshot image from the kernel. It has the following limitations: diff --git a/include/uapi/linux/suspend_ioctls.h b/include/uapi/linux/suspend_ioctls.h index bcce04e21c0dce..b73026ef824bb9 100644 --- a/include/uapi/linux/suspend_ioctls.h +++ b/include/uapi/linux/suspend_ioctls.h @@ -13,6 +13,18 @@ struct resume_swap_area { __u32 dev; } __attribute__((packed)); +#define USWSUSP_KEY_NONCE_SIZE 16 + +/* + * This structure is used to pass the kernel's hibernate encryption key in + * either direction. + */ +struct uswsusp_key_blob { + __u32 blob_len; + __u8 blob[512]; + __u8 nonce[USWSUSP_KEY_NONCE_SIZE]; +} __attribute__((packed)); + #define SNAPSHOT_IOC_MAGIC '3' #define SNAPSHOT_FREEZE _IO(SNAPSHOT_IOC_MAGIC, 1) #define SNAPSHOT_UNFREEZE _IO(SNAPSHOT_IOC_MAGIC, 2) @@ -29,6 +41,7 @@ struct resume_swap_area { #define SNAPSHOT_PREF_IMAGE_SIZE _IO(SNAPSHOT_IOC_MAGIC, 18) #define SNAPSHOT_AVAIL_SWAP_SIZE _IOR(SNAPSHOT_IOC_MAGIC, 19, __kernel_loff_t) #define SNAPSHOT_ALLOC_SWAP_PAGE _IOR(SNAPSHOT_IOC_MAGIC, 20, __kernel_loff_t) -#define SNAPSHOT_IOC_MAXNR 20 +#define SNAPSHOT_ENABLE_ENCRYPTION _IOWR(SNAPSHOT_IOC_MAGIC, 21, struct uswsusp_key_blob) +#define SNAPSHOT_IOC_MAXNR 21 #endif /* _LINUX_SUSPEND_IOCTLS_H */ diff --git a/kernel/power/Kconfig b/kernel/power/Kconfig index 60a1d3051cc79a..cd574af0b43379 100644 --- a/kernel/power/Kconfig +++ b/kernel/power/Kconfig @@ -92,6 +92,19 @@ config HIBERNATION_SNAPSHOT_DEV If in doubt, say Y. +config ENCRYPTED_HIBERNATION + bool "Encryption support for userspace snapshots" + depends on HIBERNATION_SNAPSHOT_DEV + depends on CRYPTO_AEAD2=y + default n + help + Enable support for kernel-based encryption of hibernation snapshots + created by uswsusp tools. + + Say N if userspace handles the image encryption. + + If in doubt, say N. + config PM_STD_PARTITION string "Default resume partition" depends on HIBERNATION diff --git a/kernel/power/Makefile b/kernel/power/Makefile index 874ad834dc8daf..7be08f2e0e3b68 100644 --- a/kernel/power/Makefile +++ b/kernel/power/Makefile @@ -16,6 +16,7 @@ obj-$(CONFIG_SUSPEND) += suspend.o obj-$(CONFIG_PM_TEST_SUSPEND) += suspend_test.o obj-$(CONFIG_HIBERNATION) += hibernate.o snapshot.o swap.o obj-$(CONFIG_HIBERNATION_SNAPSHOT_DEV) += user.o +obj-$(CONFIG_ENCRYPTED_HIBERNATION) += snapenc.o obj-$(CONFIG_PM_AUTOSLEEP) += autosleep.o obj-$(CONFIG_PM_WAKELOCKS) += wakelock.o diff --git a/kernel/power/snapenc.c b/kernel/power/snapenc.c new file mode 100644 index 00000000000000..f215df16dad4d3 --- /dev/null +++ b/kernel/power/snapenc.c @@ -0,0 +1,493 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* This file provides encryption support for system snapshots. */ + +#include +#include +#include +#include +#include +#include + +#include "power.h" +#include "user.h" + +/* Encrypt more data from the snapshot into the staging area. */ +static int snapshot_encrypt_refill(struct snapshot_data *data) +{ + + struct aead_request *req = data->aead_req; + u8 nonce[GCM_AES_IV_SIZE]; + DECLARE_CRYPTO_WAIT(wait); + size_t total = 0; + int pg_idx; + int res; + + /* + * The first buffer is the associated data, set to the offset to prevent + * attacks that rearrange chunks. + */ + sg_set_buf(&data->sg[0], &data->crypt_total, sizeof(data->crypt_total)); + + /* Load the crypt buffer with snapshot pages. */ + for (pg_idx = 0; pg_idx < CHUNK_SIZE; pg_idx++) { + void *buf = data->crypt_pages[pg_idx]; + + res = snapshot_read_next(&data->handle); + if (res < 0) + return res; + if (res == 0) + break; + + WARN_ON(res != PAGE_SIZE); + + /* + * Copy the page into the staging area. A future optimization + * could potentially skip this copy for lowmem pages. + */ + memcpy(buf, data_of(data->handle), PAGE_SIZE); + sg_set_buf(&data->sg[1 + pg_idx], buf, PAGE_SIZE); + total += PAGE_SIZE; + } + + sg_set_buf(&data->sg[1 + pg_idx], &data->auth_tag, SNAPSHOT_AUTH_TAG_SIZE); + aead_request_set_callback(req, 0, crypto_req_done, &wait); + /* + * Use incrementing nonces for each chunk, since a 64 bit value won't + * roll into re-use for any given hibernate image. + */ + memcpy(&nonce[0], &data->nonce_low, sizeof(data->nonce_low)); + memcpy(&nonce[sizeof(data->nonce_low)], + &data->nonce_high, + sizeof(nonce) - sizeof(data->nonce_low)); + + data->nonce_low += 1; + /* Total does not include AAD or the auth tag. */ + aead_request_set_crypt(req, data->sg, data->sg, total, nonce); + res = crypto_wait_req(crypto_aead_encrypt(req), &wait); + if (res) + return res; + + data->crypt_size = total; + data->crypt_total += total; + return 0; +} + +/* Decrypt data from the staging area and push it to the snapshot. */ +static int snapshot_decrypt_drain(struct snapshot_data *data) +{ + struct aead_request *req = data->aead_req; + u8 nonce[GCM_AES_IV_SIZE]; + DECLARE_CRYPTO_WAIT(wait); + int page_count; + size_t total; + int pg_idx; + int res; + + /* Set up the associated data. */ + sg_set_buf(&data->sg[0], &data->crypt_total, sizeof(data->crypt_total)); + + /* + * Get the number of full pages, which could be short at the end. There + * should also be a tag at the end, so the offset won't be an even page. + */ + page_count = data->crypt_offset >> PAGE_SHIFT; + total = page_count << PAGE_SHIFT; + if ((total == 0) || (total == data->crypt_offset)) + return -EINVAL; + + /* + * Load the sg list with the crypt buffer. Inline decrypt back into the + * staging buffer. A future optimization could decrypt directly into + * lowmem pages. + */ + for (pg_idx = 0; pg_idx < page_count; pg_idx++) + sg_set_buf(&data->sg[1 + pg_idx], data->crypt_pages[pg_idx], PAGE_SIZE); + + /* + * It's possible this is the final decrypt, and there are fewer than + * CHUNK_SIZE pages. If this is the case we would have just written the + * auth tag into the first few bytes of a new page. Copy to the tag if + * so. + */ + if ((page_count < CHUNK_SIZE) && + (data->crypt_offset - total) == sizeof(data->auth_tag)) { + + memcpy(data->auth_tag, + data->crypt_pages[pg_idx], + sizeof(data->auth_tag)); + + } else if (data->crypt_offset != + ((CHUNK_SIZE << PAGE_SHIFT) + SNAPSHOT_AUTH_TAG_SIZE)) { + + return -EINVAL; + } + + sg_set_buf(&data->sg[1 + pg_idx], &data->auth_tag, SNAPSHOT_AUTH_TAG_SIZE); + aead_request_set_callback(req, 0, crypto_req_done, &wait); + memcpy(&nonce[0], &data->nonce_low, sizeof(data->nonce_low)); + memcpy(&nonce[sizeof(data->nonce_low)], + &data->nonce_high, + sizeof(nonce) - sizeof(data->nonce_low)); + + data->nonce_low += 1; + aead_request_set_crypt(req, data->sg, data->sg, total + SNAPSHOT_AUTH_TAG_SIZE, nonce); + res = crypto_wait_req(crypto_aead_decrypt(req), &wait); + if (res) + return res; + + data->crypt_size = 0; + data->crypt_offset = 0; + + /* Push the decrypted pages further down the stack. */ + total = 0; + for (pg_idx = 0; pg_idx < page_count; pg_idx++) { + void *buf = data->crypt_pages[pg_idx]; + + res = snapshot_write_next(&data->handle); + if (res < 0) + return res; + if (res == 0) + break; + + if (!data_of(data->handle)) + return -EINVAL; + + WARN_ON(res != PAGE_SIZE); + + /* + * Copy the page into the staging area. A future optimization + * could potentially skip this copy for lowmem pages. + */ + memcpy(data_of(data->handle), buf, PAGE_SIZE); + total += PAGE_SIZE; + } + + data->crypt_total += total; + return 0; +} + +static ssize_t snapshot_read_next_encrypted(struct snapshot_data *data, + void **buf) +{ + size_t tag_off; + + /* Refill the encrypted buffer if it's empty. */ + if ((data->crypt_size == 0) || + (data->crypt_offset >= + (data->crypt_size + SNAPSHOT_AUTH_TAG_SIZE))) { + + int rc; + + data->crypt_size = 0; + data->crypt_offset = 0; + rc = snapshot_encrypt_refill(data); + if (rc < 0) + return rc; + } + + /* Return data pages if the offset is in that region. */ + if (data->crypt_offset < data->crypt_size) { + size_t pg_idx = data->crypt_offset >> PAGE_SHIFT; + size_t pg_off = data->crypt_offset & (PAGE_SIZE - 1); + *buf = data->crypt_pages[pg_idx] + pg_off; + return PAGE_SIZE - pg_off; + } + + /* Use offsets just beyond the size to return the tag. */ + tag_off = data->crypt_offset - data->crypt_size; + if (tag_off > SNAPSHOT_AUTH_TAG_SIZE) + tag_off = SNAPSHOT_AUTH_TAG_SIZE; + + *buf = data->auth_tag + tag_off; + return SNAPSHOT_AUTH_TAG_SIZE - tag_off; +} + +static ssize_t snapshot_write_next_encrypted(struct snapshot_data *data, + void **buf) +{ + size_t tag_off; + + /* Return data pages if the offset is in that region. */ + if (data->crypt_offset < (PAGE_SIZE * CHUNK_SIZE)) { + size_t pg_idx = data->crypt_offset >> PAGE_SHIFT; + size_t pg_off = data->crypt_offset & (PAGE_SIZE - 1); + *buf = data->crypt_pages[pg_idx] + pg_off; + return PAGE_SIZE - pg_off; + } + + /* Use offsets just beyond the size to return the tag. */ + tag_off = data->crypt_offset - (PAGE_SIZE * CHUNK_SIZE); + if (tag_off > SNAPSHOT_AUTH_TAG_SIZE) + tag_off = SNAPSHOT_AUTH_TAG_SIZE; + + *buf = data->auth_tag + tag_off; + return SNAPSHOT_AUTH_TAG_SIZE - tag_off; +} + +ssize_t snapshot_read_encrypted(struct snapshot_data *data, + char __user *buf, size_t count, loff_t *offp) +{ + ssize_t total = 0; + + /* Loop getting buffers of varying sizes and copying to userspace. */ + while (count) { + size_t copy_size; + size_t not_done; + void *src; + ssize_t src_size = snapshot_read_next_encrypted(data, &src); + + if (src_size <= 0) { + if (total == 0) + return src_size; + + break; + } + + copy_size = min(count, (size_t)src_size); + not_done = copy_to_user(buf + total, src, copy_size); + copy_size -= not_done; + total += copy_size; + count -= copy_size; + data->crypt_offset += copy_size; + if (copy_size == 0) { + if (total == 0) + return -EFAULT; + + break; + } + } + + *offp += total; + return total; +} + +ssize_t snapshot_write_encrypted(struct snapshot_data *data, + const char __user *buf, size_t count, + loff_t *offp) +{ + ssize_t total = 0; + + /* Loop getting buffers of varying sizes and copying from. */ + while (count) { + size_t copy_size; + size_t not_done; + void *dst; + ssize_t dst_size = snapshot_write_next_encrypted(data, &dst); + + if (dst_size <= 0) { + if (total == 0) + return dst_size; + + break; + } + + copy_size = min(count, (size_t)dst_size); + not_done = copy_from_user(dst, buf + total, copy_size); + copy_size -= not_done; + total += copy_size; + count -= copy_size; + data->crypt_offset += copy_size; + if (copy_size == 0) { + if (total == 0) + return -EFAULT; + + break; + } + + /* Drain the encrypted buffer if it's full. */ + if ((data->crypt_offset >= + ((PAGE_SIZE * CHUNK_SIZE) + SNAPSHOT_AUTH_TAG_SIZE))) { + + int rc; + + rc = snapshot_decrypt_drain(data); + if (rc < 0) + return rc; + } + } + + *offp += total; + return total; +} + +void snapshot_teardown_encryption(struct snapshot_data *data) +{ + int i; + + if (data->aead_req) { + aead_request_free(data->aead_req); + data->aead_req = NULL; + } + + if (data->aead_tfm) { + crypto_free_aead(data->aead_tfm); + data->aead_tfm = NULL; + } + + for (i = 0; i < CHUNK_SIZE; i++) { + if (data->crypt_pages[i]) { + free_page((unsigned long)data->crypt_pages[i]); + data->crypt_pages[i] = NULL; + } + } +} + +static int snapshot_setup_encryption_common(struct snapshot_data *data) +{ + int i, rc; + + data->crypt_total = 0; + data->crypt_offset = 0; + data->crypt_size = 0; + memset(data->crypt_pages, 0, sizeof(data->crypt_pages)); + /* This only works once per hibernate. */ + if (data->aead_tfm) + return -EINVAL; + + /* Set up the encryption transform */ + data->aead_tfm = crypto_alloc_aead("gcm(aes)", 0, 0); + if (IS_ERR(data->aead_tfm)) { + rc = PTR_ERR(data->aead_tfm); + data->aead_tfm = NULL; + return rc; + } + + rc = -ENOMEM; + data->aead_req = aead_request_alloc(data->aead_tfm, GFP_KERNEL); + if (data->aead_req == NULL) + goto setup_fail; + + /* Allocate the staging area */ + for (i = 0; i < CHUNK_SIZE; i++) { + data->crypt_pages[i] = (void *)__get_free_page(GFP_ATOMIC); + if (data->crypt_pages[i] == NULL) + goto setup_fail; + } + + sg_init_table(data->sg, CHUNK_SIZE + 2); + + /* + * The associated data will be the offset so that blocks can't be + * rearranged. + */ + aead_request_set_ad(data->aead_req, sizeof(data->crypt_total)); + rc = crypto_aead_setauthsize(data->aead_tfm, SNAPSHOT_AUTH_TAG_SIZE); + if (rc) + goto setup_fail; + + return 0; + +setup_fail: + snapshot_teardown_encryption(data); + return rc; +} + +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]; + int rc; + + /* Don't pull a random key from a world that can be reset. */ + if (data->ready) + return -EPIPE; + + rc = snapshot_setup_encryption_common(data); + if (rc) + return rc; + + /* Build a random starting nonce. */ + 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)); + 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); + if (rc) + goto fail; + + rc = copy_to_user(&key->blob, &aead_key, sizeof(aead_key)); + if (rc) + goto fail; + + rc = copy_to_user(&key->nonce, &nonce, sizeof(nonce)); + if (rc) + goto fail; + + return 0; + +fail: + snapshot_teardown_encryption(data); + return rc; +} + +int snapshot_set_encryption_key(struct snapshot_data *data, + struct uswsusp_key_blob __user *key) +{ + struct uswsusp_key_blob blob; + int rc; + + /* It's too late if data's been pushed in. */ + if (data->handle.cur) + return -EPIPE; + + rc = snapshot_setup_encryption_common(data); + if (rc) + return rc; + + /* Load the key from user mode. */ + rc = copy_from_user(&blob, key, sizeof(struct uswsusp_key_blob)); + if (rc) + goto crypto_setup_fail; + + if (blob.blob_len != sizeof(struct uswsusp_key_blob)) { + rc = -EINVAL; + goto crypto_setup_fail; + } + + rc = crypto_aead_setkey(data->aead_tfm, + blob.blob, + SNAPSHOT_ENCRYPTION_KEY_SIZE); + + if (rc) + goto crypto_setup_fail; + + /* Load the starting nonce. */ + memcpy(&data->nonce_low, &blob.nonce[0], sizeof(data->nonce_low)); + memcpy(&data->nonce_high, &blob.nonce[8], sizeof(data->nonce_high)); + return 0; + +crypto_setup_fail: + snapshot_teardown_encryption(data); + return rc; +} + +loff_t snapshot_get_encrypted_image_size(loff_t raw_size) +{ + loff_t pages = raw_size >> PAGE_SHIFT; + loff_t chunks = (pages + (CHUNK_SIZE - 1)) / CHUNK_SIZE; + /* + * The encrypted size is the normal size, plus a stitched in + * authentication tag for every chunk of pages. + */ + return raw_size + (chunks * SNAPSHOT_AUTH_TAG_SIZE); +} + +int snapshot_finalize_decrypted_image(struct snapshot_data *data) +{ + int rc; + + if (data->crypt_offset != 0) { + rc = snapshot_decrypt_drain(data); + if (rc) + return rc; + } + + return 0; +} diff --git a/kernel/power/user.c b/kernel/power/user.c index 3a4e70366f354c..bba5cdbd2c0239 100644 --- a/kernel/power/user.c +++ b/kernel/power/user.c @@ -25,19 +25,10 @@ #include #include "power.h" +#include "user.h" static bool need_wait; - -static struct snapshot_data { - struct snapshot_handle handle; - int swap; - int mode; - bool frozen; - bool ready; - bool platform_support; - bool free_bitmaps; - dev_t dev; -} snapshot_state; +struct snapshot_data snapshot_state; int is_hibernate_resume_dev(dev_t dev) { @@ -122,6 +113,7 @@ static int snapshot_release(struct inode *inode, struct file *filp) } else if (data->free_bitmaps) { free_basic_memory_bitmaps(); } + snapshot_teardown_encryption(data); pm_notifier_call_chain(data->mode == O_RDONLY ? PM_POST_HIBERNATION : PM_POST_RESTORE); hibernate_release(); @@ -146,6 +138,12 @@ static ssize_t snapshot_read(struct file *filp, char __user *buf, res = -ENODATA; goto Unlock; } + + if (snapshot_encryption_enabled(data)) { + res = snapshot_read_encrypted(data, buf, count, offp); + goto Unlock; + } + if (!pg_offp) { /* on page boundary? */ res = snapshot_read_next(&data->handle); if (res <= 0) @@ -182,6 +180,11 @@ static ssize_t snapshot_write(struct file *filp, const char __user *buf, data = filp->private_data; + if (snapshot_encryption_enabled(data)) { + res = snapshot_write_encrypted(data, buf, count, offp); + goto unlock; + } + if (!pg_offp) { res = snapshot_write_next(&data->handle); if (res <= 0) @@ -317,6 +320,12 @@ static long snapshot_ioctl(struct file *filp, unsigned int cmd, break; case SNAPSHOT_ATOMIC_RESTORE: + if (snapshot_encryption_enabled(data)) { + error = snapshot_finalize_decrypted_image(data); + if (error) + break; + } + snapshot_write_finalize(&data->handle); if (data->mode != O_WRONLY || !data->frozen || !snapshot_image_loaded(&data->handle)) { @@ -352,6 +361,8 @@ static long snapshot_ioctl(struct file *filp, unsigned int cmd, } size = snapshot_get_image_size(); size <<= PAGE_SHIFT; + if (snapshot_encryption_enabled(data)) + size = snapshot_get_encrypted_image_size(size); error = put_user(size, (loff_t __user *)arg); break; @@ -409,6 +420,13 @@ static long snapshot_ioctl(struct file *filp, unsigned int cmd, error = snapshot_set_swap_area(data, (void __user *)arg); break; + case SNAPSHOT_ENABLE_ENCRYPTION: + if (data->mode == O_RDONLY) + error = snapshot_get_encryption_key(data, (void __user *)arg); + else + error = snapshot_set_encryption_key(data, (void __user *)arg); + break; + default: error = -ENOTTY; diff --git a/kernel/power/user.h b/kernel/power/user.h new file mode 100644 index 00000000000000..ac429782abff85 --- /dev/null +++ b/kernel/power/user.h @@ -0,0 +1,103 @@ +/* SPDX-License-Identifier: GPL-2.0 */ + +#include +#include +#include + +#define SNAPSHOT_ENCRYPTION_KEY_SIZE AES_KEYSIZE_128 +#define SNAPSHOT_AUTH_TAG_SIZE 16 + +/* Define the number of pages in a single AEAD encryption chunk. */ +#define CHUNK_SIZE 16 + +struct snapshot_data { + struct snapshot_handle handle; + int swap; + int mode; + bool frozen; + bool ready; + bool platform_support; + bool free_bitmaps; + dev_t dev; + +#if defined(CONFIG_ENCRYPTED_HIBERNATION) + struct crypto_aead *aead_tfm; + struct aead_request *aead_req; + void *crypt_pages[CHUNK_SIZE]; + u8 auth_tag[SNAPSHOT_AUTH_TAG_SIZE]; + struct scatterlist sg[CHUNK_SIZE + 2]; /* Add room for AD and auth tag. */ + size_t crypt_offset; + size_t crypt_size; + uint64_t crypt_total; + uint64_t nonce_low; + uint64_t nonce_high; +#endif + +}; + +extern struct snapshot_data snapshot_state; + +/* kernel/power/swapenc.c routines */ +#if defined(CONFIG_ENCRYPTED_HIBERNATION) + +ssize_t snapshot_read_encrypted(struct snapshot_data *data, + char __user *buf, size_t count, loff_t *offp); + +ssize_t snapshot_write_encrypted(struct snapshot_data *data, + const char __user *buf, size_t count, + loff_t *offp); + +void snapshot_teardown_encryption(struct snapshot_data *data); +int snapshot_get_encryption_key(struct snapshot_data *data, + struct uswsusp_key_blob __user *key); + +int snapshot_set_encryption_key(struct snapshot_data *data, + struct uswsusp_key_blob __user *key); + +loff_t snapshot_get_encrypted_image_size(loff_t raw_size); + +int snapshot_finalize_decrypted_image(struct snapshot_data *data); + +#define snapshot_encryption_enabled(data) (!!(data)->aead_tfm) + +#else + +ssize_t snapshot_read_encrypted(struct snapshot_data *data, + char __user *buf, size_t count, loff_t *offp) +{ + return -ENOTTY; +} + +ssize_t snapshot_write_encrypted(struct snapshot_data *data, + const char __user *buf, size_t count, + loff_t *offp) +{ + return -ENOTTY; +} + +static void snapshot_teardown_encryption(struct snapshot_data *data) {} +static int snapshot_get_encryption_key(struct snapshot_data *data, + struct uswsusp_key_blob __user *key) +{ + return -ENOTTY; +} + +static int snapshot_set_encryption_key(struct snapshot_data *data, + struct uswsusp_key_blob __user *key) +{ + return -ENOTTY; +} + +static loff_t snapshot_get_encrypted_image_size(loff_t raw_size) +{ + return raw_size; +} + +static int snapshot_finalize_decrypted_image(struct snapshot_data *data) +{ + return -ENOTTY; +} + +#define snapshot_encryption_enabled(data) (0) + +#endif From patchwork Thu Nov 3 18:01:17 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Evan Green X-Patchwork-Id: 621304 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 DBC75C43219 for ; Thu, 3 Nov 2022 18:05:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229611AbiKCSFE (ORCPT ); Thu, 3 Nov 2022 14:05:04 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42978 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229567AbiKCSEN (ORCPT ); Thu, 3 Nov 2022 14:04:13 -0400 Received: from mail-pf1-x429.google.com (mail-pf1-x429.google.com [IPv6:2607:f8b0:4864:20::429]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B240723E87 for ; 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Thu, 03 Nov 2022 11:01:54 -0700 (PDT) Received: from evgreen-glaptop.lan ([98.45.28.95]) by smtp.gmail.com with ESMTPSA id t12-20020a1709027fcc00b00177fb862a87sm1000277plb.20.2022.11.03.11.01.53 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 03 Nov 2022 11:01:54 -0700 (PDT) From: Evan Green To: linux-kernel@vger.kernel.org Cc: corbet@lwn.net, linux-pm@vger.kernel.org, rjw@rjwysocki.net, gwendal@chromium.org, apronin@chromium.org, Pavel Machek , Kees Cook , Matthew Garrett , linux-integrity@vger.kernel.org, jejb@linux.ibm.com, zohar@linux.ibm.com, dlunev@google.com, Eric Biggers , Ben Boeckel , jarkko@kernel.org, Evan Green , Len Brown , "Rafael J. Wysocki" Subject: [PATCH v4 09/11] PM: hibernate: Mix user key in encrypted hibernate Date: Thu, 3 Nov 2022 11:01:17 -0700 Message-Id: <20221103105558.v4.9.I87952411cf83f2199ff7a4cc8c828d357b8c8ce3@changeid> X-Mailer: git-send-email 2.38.1.431.g37b22c650d-goog In-Reply-To: <20221103180120.752659-1-evgreen@chromium.org> References: <20221103180120.752659-1-evgreen@chromium.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org Usermode may have their own data protection requirements when it comes to encrypting the hibernate image. For example, users may want a policy where the hibernate image is protected by a key derived both from platform-level security as well as authentication data (such as a password or PIN). This way, even if the platform is compromised (ie a stolen laptop), sensitive data cannot be exfiltrated via the hibernate image without additional data (like the user's password). The kernel is already doing the encryption, but will be protecting its key with the TPM alone. Allow usermode to mix in key content of their own for the data portion of the hibernate image, so that the image encryption key is determined both by a TPM-backed secret and user-defined data. To mix the user key in, we hash the kernel key followed by the user key, and use the resulting hash as the new key. This allows usermode to mix in its key material without giving it too much control over what key is actually driving the encryption (which might be used to attack the secret kernel key). Limiting this to the data portion allows the kernel to receive the page map and prepare its giant allocation even if this user key is not yet available (ie the user has not yet finished typing in their password). Once the user key becomes available, the data portion can be pushed through to the kernel as well. This enables "preloading" scenarios, where the hibernate image is loaded off of disk while the additional key material (eg password) is being collected. One annoyance of the "preloading" scheme is that hibernate image memory is effectively double-allocated: first by the usermode process pulling encrypted contents off of disk and holding it, and second by the kernel in its giant allocation in prepare_image(). An interesting future optimization would be to allow the kernel to accept and store encrypted page data before the user key is available. This would remove the double allocation problem, as usermode could push the encrypted pages loaded from disk immediately without storing them. The kernel could defer decryption of the data until the user key is available, while still knowing the correct page locations to store the encrypted data in. Signed-off-by: Evan Green --- (no changes since v2) Changes in v2: - Add missing static on snapshot_encrypted_byte_count() - Fold in only the used kernel key bytes to the user key. - Make the user key length 32 (Eric) - Use CRYPTO_LIB_SHA256 for less boilerplate (Eric) include/uapi/linux/suspend_ioctls.h | 15 ++- kernel/power/Kconfig | 1 + kernel/power/power.h | 1 + kernel/power/snapenc.c | 158 ++++++++++++++++++++++++++-- kernel/power/snapshot.c | 5 + kernel/power/user.c | 4 + kernel/power/user.h | 12 +++ 7 files changed, 185 insertions(+), 11 deletions(-) diff --git a/include/uapi/linux/suspend_ioctls.h b/include/uapi/linux/suspend_ioctls.h index b73026ef824bb9..f93a22eac52dc2 100644 --- a/include/uapi/linux/suspend_ioctls.h +++ b/include/uapi/linux/suspend_ioctls.h @@ -25,6 +25,18 @@ struct uswsusp_key_blob { __u8 nonce[USWSUSP_KEY_NONCE_SIZE]; } __attribute__((packed)); +/* + * Allow user mode to fold in key material for the data portion of the hibernate + * image. + */ +struct uswsusp_user_key { + /* Kernel returns the metadata size. */ + __kernel_loff_t meta_size; + __u32 key_len; + __u8 key[32]; + __u32 pad; +}; + #define SNAPSHOT_IOC_MAGIC '3' #define SNAPSHOT_FREEZE _IO(SNAPSHOT_IOC_MAGIC, 1) #define SNAPSHOT_UNFREEZE _IO(SNAPSHOT_IOC_MAGIC, 2) @@ -42,6 +54,7 @@ struct uswsusp_key_blob { #define SNAPSHOT_AVAIL_SWAP_SIZE _IOR(SNAPSHOT_IOC_MAGIC, 19, __kernel_loff_t) #define SNAPSHOT_ALLOC_SWAP_PAGE _IOR(SNAPSHOT_IOC_MAGIC, 20, __kernel_loff_t) #define SNAPSHOT_ENABLE_ENCRYPTION _IOWR(SNAPSHOT_IOC_MAGIC, 21, struct uswsusp_key_blob) -#define SNAPSHOT_IOC_MAXNR 21 +#define SNAPSHOT_SET_USER_KEY _IOWR(SNAPSHOT_IOC_MAGIC, 22, struct uswsusp_user_key) +#define SNAPSHOT_IOC_MAXNR 22 #endif /* _LINUX_SUSPEND_IOCTLS_H */ diff --git a/kernel/power/Kconfig b/kernel/power/Kconfig index 2f8acbd87b34dc..35bf48b925ebf6 100644 --- a/kernel/power/Kconfig +++ b/kernel/power/Kconfig @@ -97,6 +97,7 @@ config ENCRYPTED_HIBERNATION depends on HIBERNATION_SNAPSHOT_DEV depends on CRYPTO_AEAD2=y depends on TRUSTED_KEYS=y + select CRYPTO_LIB_SHA256 default n help Enable support for kernel-based encryption of hibernation snapshots diff --git a/kernel/power/power.h b/kernel/power/power.h index b4f43394320961..5955e5cf692302 100644 --- a/kernel/power/power.h +++ b/kernel/power/power.h @@ -151,6 +151,7 @@ struct snapshot_handle { extern unsigned int snapshot_additional_pages(struct zone *zone); extern unsigned long snapshot_get_image_size(void); +extern unsigned long snapshot_get_meta_page_count(void); extern int snapshot_read_next(struct snapshot_handle *handle); extern int snapshot_write_next(struct snapshot_handle *handle); extern void snapshot_write_finalize(struct snapshot_handle *handle); diff --git a/kernel/power/snapenc.c b/kernel/power/snapenc.c index 7ff4fc66f7500c..50167a37c5bf23 100644 --- a/kernel/power/snapenc.c +++ b/kernel/power/snapenc.c @@ -6,6 +6,7 @@ #include #include #include +#include #include #include #include @@ -21,6 +22,38 @@ static struct tpm_digest known_digest = { .alg_id = TPM_ALG_SHA256, 0xf1, 0x22, 0x38, 0x6c, 0x33, 0xb1, 0x14, 0xb7, 0xec, 0x05, 0x5f, 0x49}}; +/* Derive a key from the kernel and user keys for data encryption. */ +static int snapshot_use_user_key(struct snapshot_data *data) +{ + u8 digest[SHA256_DIGEST_SIZE]; + struct trusted_key_payload *payload = data->key->payload.data[0]; + struct sha256_state sha256_state; + + /* + * Hash the kernel key and the user key together. This folds in the user + * key, but not in a way that gives the user mode predictable control + * over the key bits. + */ + sha256_init(&sha256_state); + sha256_update(&sha256_state, payload->key, SNAPSHOT_ENCRYPTION_KEY_SIZE); + sha256_update(&sha256_state, data->user_key, sizeof(data->user_key)); + sha256_final(&sha256_state, digest); + return crypto_aead_setkey(data->aead_tfm, + digest, + SNAPSHOT_ENCRYPTION_KEY_SIZE); +} + +/* Check to see if it's time to switch to the user key, and do it if so. */ +static int snapshot_check_user_key_switch(struct snapshot_data *data) +{ + if (data->user_key_valid && data->meta_size && + data->crypt_total == data->meta_size) { + return snapshot_use_user_key(data); + } + + return 0; +} + /* Encrypt more data from the snapshot into the staging area. */ static int snapshot_encrypt_refill(struct snapshot_data *data) { @@ -32,6 +65,15 @@ static int snapshot_encrypt_refill(struct snapshot_data *data) int pg_idx; int res; + if (data->crypt_total == 0) { + data->meta_size = snapshot_get_meta_page_count() << PAGE_SHIFT; + + } else { + res = snapshot_check_user_key_switch(data); + if (res) + return res; + } + /* * The first buffer is the associated data, set to the offset to prevent * attacks that rearrange chunks. @@ -42,6 +84,11 @@ static int snapshot_encrypt_refill(struct snapshot_data *data) for (pg_idx = 0; pg_idx < CHUNK_SIZE; pg_idx++) { void *buf = data->crypt_pages[pg_idx]; + /* Stop at the meta page boundary to potentially switch keys. */ + if (total && + ((data->crypt_total + total) == data->meta_size)) + break; + res = snapshot_read_next(&data->handle); if (res < 0) return res; @@ -114,10 +161,10 @@ static int snapshot_decrypt_drain(struct snapshot_data *data) sg_set_buf(&data->sg[1 + pg_idx], data->crypt_pages[pg_idx], PAGE_SIZE); /* - * It's possible this is the final decrypt, and there are fewer than - * CHUNK_SIZE pages. If this is the case we would have just written the - * auth tag into the first few bytes of a new page. Copy to the tag if - * so. + * It's possible this is the final decrypt, or the final decrypt of the + * meta region, and there are fewer than CHUNK_SIZE pages. If this is + * the case we would have just written the auth tag into the first few + * bytes of a new page. Copy to the tag if so. */ if ((page_count < CHUNK_SIZE) && (data->crypt_offset - total) == sizeof(data->auth_tag)) { @@ -172,7 +219,14 @@ static int snapshot_decrypt_drain(struct snapshot_data *data) total += PAGE_SIZE; } + if (data->crypt_total == 0) + data->meta_size = snapshot_get_meta_page_count() << PAGE_SHIFT; + data->crypt_total += total; + res = snapshot_check_user_key_switch(data); + if (res) + return res; + return 0; } @@ -221,8 +275,26 @@ static ssize_t snapshot_write_next_encrypted(struct snapshot_data *data, if (data->crypt_offset < (PAGE_SIZE * CHUNK_SIZE)) { size_t pg_idx = data->crypt_offset >> PAGE_SHIFT; size_t pg_off = data->crypt_offset & (PAGE_SIZE - 1); + size_t size_avail = PAGE_SIZE; *buf = data->crypt_pages[pg_idx] + pg_off; - return PAGE_SIZE - pg_off; + + /* + * If this is the boundary where the meta pages end, then just + * return enough for the auth tag. + */ + if (data->meta_size && (data->crypt_total < data->meta_size)) { + uint64_t total_done = + data->crypt_total + data->crypt_offset; + + if ((total_done >= data->meta_size) && + (total_done < + (data->meta_size + SNAPSHOT_AUTH_TAG_SIZE))) { + + size_avail = SNAPSHOT_AUTH_TAG_SIZE; + } + } + + return size_avail - pg_off; } /* Use offsets just beyond the size to return the tag. */ @@ -304,9 +376,15 @@ ssize_t snapshot_write_encrypted(struct snapshot_data *data, break; } - /* Drain the encrypted buffer if it's full. */ + /* + * Drain the encrypted buffer if it's full, or if we hit the end + * of the meta pages and need a key change. + */ if ((data->crypt_offset >= - ((PAGE_SIZE * CHUNK_SIZE) + SNAPSHOT_AUTH_TAG_SIZE))) { + ((PAGE_SIZE * CHUNK_SIZE) + SNAPSHOT_AUTH_TAG_SIZE)) || + (data->meta_size && (data->crypt_total < data->meta_size) && + ((data->crypt_total + data->crypt_offset) == + (data->meta_size + SNAPSHOT_AUTH_TAG_SIZE)))) { int rc; @@ -350,6 +428,8 @@ void snapshot_teardown_encryption(struct snapshot_data *data) data->crypt_pages[i] = NULL; } } + + memset(data->user_key, 0, sizeof(data->user_key)); } static int snapshot_setup_encryption_common(struct snapshot_data *data) @@ -359,6 +439,7 @@ static int snapshot_setup_encryption_common(struct snapshot_data *data) data->crypt_total = 0; data->crypt_offset = 0; data->crypt_size = 0; + data->user_key_valid = false; memset(data->crypt_pages, 0, sizeof(data->crypt_pages)); /* This only works once per hibernate. */ if (data->aead_tfm) @@ -661,15 +742,72 @@ int snapshot_set_encryption_key(struct snapshot_data *data, return rc; } -loff_t snapshot_get_encrypted_image_size(loff_t raw_size) +static loff_t snapshot_encrypted_byte_count(loff_t plain_size) { - loff_t pages = raw_size >> PAGE_SHIFT; + loff_t pages = plain_size >> PAGE_SHIFT; loff_t chunks = (pages + (CHUNK_SIZE - 1)) / CHUNK_SIZE; /* * The encrypted size is the normal size, plus a stitched in * authentication tag for every chunk of pages. */ - return raw_size + (chunks * SNAPSHOT_AUTH_TAG_SIZE); + return plain_size + (chunks * SNAPSHOT_AUTH_TAG_SIZE); +} + +static loff_t snapshot_get_meta_data_size(void) +{ + loff_t pages = snapshot_get_meta_page_count(); + + return snapshot_encrypted_byte_count(pages << PAGE_SHIFT); +} + +int snapshot_set_user_key(struct snapshot_data *data, + struct uswsusp_user_key __user *key) +{ + struct uswsusp_user_key user_key; + unsigned int key_len; + int rc; + loff_t size; + + /* + * Return the metadata size, the number of bytes that can be fed in before + * the user data key is needed at resume time. + */ + size = snapshot_get_meta_data_size(); + rc = put_user(size, &key->meta_size); + if (rc) + return rc; + + rc = copy_from_user(&user_key, key, sizeof(struct uswsusp_user_key)); + if (rc) + return rc; + + key_len = min_t(__u32, user_key.key_len, sizeof(data->user_key)); + if (key_len < 8) + return -EINVAL; + + /* Don't allow it if it's too late. */ + if (data->crypt_total > data->meta_size) + return -EBUSY; + + memset(data->user_key, 0, sizeof(data->user_key)); + memcpy(data->user_key, user_key.key, key_len); + data->user_key_valid = true; + /* Install the key if the user is just under the wire. */ + rc = snapshot_check_user_key_switch(data); + if (rc) + return rc; + + return 0; +} + +loff_t snapshot_get_encrypted_image_size(loff_t raw_size) +{ + loff_t pages = raw_size >> PAGE_SHIFT; + loff_t meta_size; + + pages -= snapshot_get_meta_page_count(); + meta_size = snapshot_get_meta_data_size(); + return snapshot_encrypted_byte_count(pages << PAGE_SHIFT) + meta_size; } int snapshot_finalize_decrypted_image(struct snapshot_data *data) diff --git a/kernel/power/snapshot.c b/kernel/power/snapshot.c index 2a406753af9049..026ee511633bc9 100644 --- a/kernel/power/snapshot.c +++ b/kernel/power/snapshot.c @@ -2083,6 +2083,11 @@ unsigned long snapshot_get_image_size(void) return nr_copy_pages + nr_meta_pages + 1; } +unsigned long snapshot_get_meta_page_count(void) +{ + return nr_meta_pages + 1; +} + static int init_header(struct swsusp_info *info) { memset(info, 0, sizeof(struct swsusp_info)); diff --git a/kernel/power/user.c b/kernel/power/user.c index bba5cdbd2c0239..a66e32c9596da8 100644 --- a/kernel/power/user.c +++ b/kernel/power/user.c @@ -427,6 +427,10 @@ static long snapshot_ioctl(struct file *filp, unsigned int cmd, error = snapshot_set_encryption_key(data, (void __user *)arg); break; + case SNAPSHOT_SET_USER_KEY: + error = snapshot_set_user_key(data, (void __user *)arg); + break; + default: error = -ENOTTY; diff --git a/kernel/power/user.h b/kernel/power/user.h index 6c86fb64ebe13e..c1e80a835d0a38 100644 --- a/kernel/power/user.h +++ b/kernel/power/user.h @@ -32,6 +32,9 @@ struct snapshot_data { uint64_t nonce_low; uint64_t nonce_high; struct key *key; + u8 user_key[SNAPSHOT_ENCRYPTION_KEY_SIZE]; + bool user_key_valid; + uint64_t meta_size; #endif }; @@ -55,6 +58,9 @@ int snapshot_get_encryption_key(struct snapshot_data *data, int snapshot_set_encryption_key(struct snapshot_data *data, struct uswsusp_key_blob __user *key); +int snapshot_set_user_key(struct snapshot_data *data, + struct uswsusp_user_key __user *key); + loff_t snapshot_get_encrypted_image_size(loff_t raw_size); int snapshot_finalize_decrypted_image(struct snapshot_data *data); @@ -89,6 +95,12 @@ static int snapshot_set_encryption_key(struct snapshot_data *data, return -ENOTTY; } +static int snapshot_set_user_key(struct snapshot_data *data, + struct uswsusp_user_key __user *key) +{ + return -ENOTTY; +} + static loff_t snapshot_get_encrypted_image_size(loff_t raw_size) { return raw_size; From patchwork Thu Nov 3 18:01:19 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Evan Green X-Patchwork-Id: 621303 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 D6D2FC433FE for ; Thu, 3 Nov 2022 18:05:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231672AbiKCSFb (ORCPT ); Thu, 3 Nov 2022 14:05:31 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42950 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231355AbiKCSEn (ORCPT ); Thu, 3 Nov 2022 14:04:43 -0400 Received: from mail-pf1-x436.google.com (mail-pf1-x436.google.com [IPv6:2607:f8b0:4864:20::436]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 741DC2339D for ; 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Thu, 03 Nov 2022 11:01:58 -0700 (PDT) Received: from evgreen-glaptop.lan ([98.45.28.95]) by smtp.gmail.com with ESMTPSA id t12-20020a1709027fcc00b00177fb862a87sm1000277plb.20.2022.11.03.11.01.56 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 03 Nov 2022 11:01:58 -0700 (PDT) From: Evan Green To: linux-kernel@vger.kernel.org Cc: corbet@lwn.net, linux-pm@vger.kernel.org, rjw@rjwysocki.net, gwendal@chromium.org, apronin@chromium.org, Pavel Machek , Kees Cook , Matthew Garrett , linux-integrity@vger.kernel.org, jejb@linux.ibm.com, zohar@linux.ibm.com, dlunev@google.com, Eric Biggers , Ben Boeckel , jarkko@kernel.org, Evan Green , Matthew Garrett , Len Brown , Matthew Garrett , "Rafael J. Wysocki" , axelj Subject: [PATCH v4 11/11] PM: hibernate: seal the encryption key with a PCR policy Date: Thu, 3 Nov 2022 11:01:19 -0700 Message-Id: <20221103105558.v4.11.Ifce072ae1ef1ce39bd681fff55af13a054045d9f@changeid> X-Mailer: git-send-email 2.38.1.431.g37b22c650d-goog In-Reply-To: <20221103180120.752659-1-evgreen@chromium.org> References: <20221103180120.752659-1-evgreen@chromium.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org The key blob is not secret, and by default the TPM will happily unseal it regardless of system state. We can protect against that by sealing the secret with a PCR policy - if the current PCR state doesn't match, the TPM will refuse to release the secret. For now let's just seal it to PCR 23. In the long term we may want a more flexible policy around this, such as including PCR 7 for PCs or 0 for Chrome OS. Link: https://lore.kernel.org/all/20210220013255.1083202-10-matthewgarrett@google.com/ Co-developed-by: Matthew Garrett Signed-off-by: Matthew Garrett Signed-off-by: Evan Green --- Changes in v4: - Local variable ordering (Jarkko) Changes in v3: - Changed funky tag to Co-developed-by (Kees) Changes in v2: - Fix sparse warnings - Fix session type comment (Andrey) - Eliminate extra label in get/create_kernel_key() (Andrey) - Call tpm_try_get_ops() before calling tpm2_flush_context(). include/linux/tpm.h | 4 + kernel/power/snapenc.c | 166 +++++++++++++++++++++++++++++++++++++++-- 2 files changed, 165 insertions(+), 5 deletions(-) diff --git a/include/linux/tpm.h b/include/linux/tpm.h index 9c2ee3e30ffa5d..252a8a92a7ff5b 100644 --- a/include/linux/tpm.h +++ b/include/linux/tpm.h @@ -233,18 +233,22 @@ enum tpm2_command_codes { TPM2_CC_CONTEXT_LOAD = 0x0161, TPM2_CC_CONTEXT_SAVE = 0x0162, TPM2_CC_FLUSH_CONTEXT = 0x0165, + TPM2_CC_START_AUTH_SESSION = 0x0176, TPM2_CC_VERIFY_SIGNATURE = 0x0177, TPM2_CC_GET_CAPABILITY = 0x017A, TPM2_CC_GET_RANDOM = 0x017B, TPM2_CC_PCR_READ = 0x017E, + TPM2_CC_POLICY_PCR = 0x017F, TPM2_CC_PCR_EXTEND = 0x0182, TPM2_CC_EVENT_SEQUENCE_COMPLETE = 0x0185, TPM2_CC_HASH_SEQUENCE_START = 0x0186, + TPM2_CC_POLICY_GET_DIGEST = 0x0189, TPM2_CC_CREATE_LOADED = 0x0191, TPM2_CC_LAST = 0x0193, /* Spec 1.36 */ }; enum tpm2_permanent_handles { + TPM2_RH_NULL = 0x40000007, TPM2_RS_PW = 0x40000009, }; diff --git a/kernel/power/snapenc.c b/kernel/power/snapenc.c index 2f421061498246..23f4d09ced578b 100644 --- a/kernel/power/snapenc.c +++ b/kernel/power/snapenc.c @@ -438,6 +438,111 @@ void snapshot_teardown_encryption(struct snapshot_data *data) memset(data->user_key, 0, sizeof(data->user_key)); } +static int tpm_setup_policy(struct tpm_chip *chip, int *session_handle) +{ + struct tpm_header *head; + struct tpm_buf buf; + char nonce[32] = {0x00}; + int rc; + + rc = tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS, + TPM2_CC_START_AUTH_SESSION); + if (rc) + return rc; + + /* Decrypt key */ + tpm_buf_append_u32(&buf, TPM2_RH_NULL); + + /* Auth entity */ + tpm_buf_append_u32(&buf, TPM2_RH_NULL); + + /* Nonce - blank is fine here */ + tpm_buf_append_u16(&buf, sizeof(nonce)); + tpm_buf_append(&buf, nonce, sizeof(nonce)); + + /* Encrypted secret - empty */ + tpm_buf_append_u16(&buf, 0); + + /* Session type - policy */ + tpm_buf_append_u8(&buf, 0x01); + + /* Encryption type - NULL */ + tpm_buf_append_u16(&buf, TPM_ALG_NULL); + + /* Hash type - SHA256 */ + tpm_buf_append_u16(&buf, TPM_ALG_SHA256); + + rc = tpm_send(chip, buf.data, tpm_buf_length(&buf)); + if (rc) + goto out; + + head = (struct tpm_header *)buf.data; + if (be32_to_cpu(head->length) != sizeof(struct tpm_header) + + sizeof(u32) + sizeof(u16) + sizeof(nonce)) { + rc = -EINVAL; + goto out; + } + + *session_handle = be32_to_cpu(*(__be32 *)&buf.data[10]); + memcpy(nonce, &buf.data[16], sizeof(nonce)); + tpm_buf_destroy(&buf); + rc = tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_POLICY_PCR); + if (rc) + return rc; + + tpm_buf_append_u32(&buf, *session_handle); + + /* PCR digest - read from the PCR, we'll verify creation data later */ + tpm_buf_append_u16(&buf, 0); + + /* One PCR */ + tpm_buf_append_u32(&buf, 1); + + /* SHA256 banks */ + tpm_buf_append_u16(&buf, TPM_ALG_SHA256); + + /* Select PCR 23 */ + tpm_buf_append_u32(&buf, 0x03000080); + rc = tpm_send(chip, buf.data, tpm_buf_length(&buf)); + if (rc) + goto out; + +out: + tpm_buf_destroy(&buf); + return rc; +} + +static int tpm_policy_get_digest(struct tpm_chip *chip, int handle, + char *digest) +{ + struct tpm_header *head; + struct tpm_buf buf; + int rc; + + rc = tpm_buf_init(&buf, TPM2_ST_NO_SESSIONS, TPM2_CC_POLICY_GET_DIGEST); + if (rc) + return rc; + + tpm_buf_append_u32(&buf, handle); + rc = tpm_send(chip, buf.data, tpm_buf_length(&buf)); + + if (rc) + goto out; + + head = (struct tpm_header *)buf.data; + if (be32_to_cpu(head->length) != sizeof(struct tpm_header) + + sizeof(u16) + SHA256_DIGEST_SIZE) { + rc = -EINVAL; + goto out; + } + + memcpy(digest, &buf.data[12], SHA256_DIGEST_SIZE); + +out: + tpm_buf_destroy(&buf); + return rc; +} + static int snapshot_setup_encryption_common(struct snapshot_data *data) { int i, rc; @@ -492,11 +597,16 @@ static int snapshot_setup_encryption_common(struct snapshot_data *data) static int snapshot_create_kernel_key(struct snapshot_data *data) { /* Create a key sealed by the SRK. */ - char *keyinfo = "new\t32\tkeyhandle=0x81000000\tcreationpcrs=0x00800000"; + const char *keytemplate = + "new\t32\tkeyhandle=0x81000000\tcreationpcrs=0x00800000\tpolicydigest=%s"; const struct cred *cred = current_cred(); struct tpm_digest *digests = NULL; + char policy[SHA256_DIGEST_SIZE]; + char *policydigest = NULL; + int session_handle = -1; struct key *key = NULL; struct tpm_chip *chip; + char *keyinfo = NULL; int ret, i; chip = tpm_default_chip(); @@ -529,6 +639,28 @@ static int snapshot_create_kernel_key(struct snapshot_data *data) if (ret != 0) goto out; + policydigest = kmalloc(SHA256_DIGEST_SIZE * 2 + 1, GFP_KERNEL); + if (!policydigest) { + ret = -ENOMEM; + goto out; + } + + ret = tpm_setup_policy(chip, &session_handle); + if (ret != 0) + goto out; + + ret = tpm_policy_get_digest(chip, session_handle, policy); + if (ret != 0) + goto out; + + bin2hex(policydigest, policy, SHA256_DIGEST_SIZE); + policydigest[SHA256_DIGEST_SIZE * 2] = '\0'; + keyinfo = kasprintf(GFP_KERNEL, keytemplate, policydigest); + 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); @@ -539,7 +671,7 @@ static int snapshot_create_kernel_key(struct snapshot_data *data) goto out; } - ret = key_instantiate_and_link(key, keyinfo, sizeof(keyinfo), NULL, + ret = key_instantiate_and_link(key, keyinfo, strlen(keyinfo) + 1, NULL, NULL); if (ret != 0) goto out; @@ -553,7 +685,16 @@ static int snapshot_create_kernel_key(struct snapshot_data *data) key_put(key); } + if (session_handle != -1) { + if (tpm_try_get_ops(chip) == 0) { + tpm2_flush_context(chip, session_handle); + tpm_put_ops(chip); + } + } + kfree(digests); + kfree(keyinfo); + kfree(policydigest); tpm2_pcr_reset(chip, 23); out_dev: @@ -617,12 +758,13 @@ static int snapshot_load_kernel_key(struct snapshot_data *data, struct uswsusp_key_blob *blob) { - char *keytemplate = "load\t%s\tkeyhandle=0x81000000"; + char *keytemplate = "load\t%s\tkeyhandle=0x81000000\tpolicyhandle=0x%x"; const struct cred *cred = current_cred(); struct trusted_key_payload *payload; char certhash[SHA256_DIGEST_SIZE]; struct tpm_digest *digests = NULL; char *blobstring = NULL; + int session_handle = -1; struct key *key = NULL; struct tpm_chip *chip; char *keyinfo = NULL; @@ -658,14 +800,21 @@ static int snapshot_load_kernel_key(struct snapshot_data *data, if (ret != 0) goto out; - blobstring = kmalloc(blob->blob_len * 2, GFP_KERNEL); + ret = tpm_setup_policy(chip, &session_handle); + if (ret != 0) + goto out; + + blobstring = kmalloc(blob->blob_len * 2 + 1, GFP_KERNEL); if (!blobstring) { ret = -ENOMEM; goto out; } bin2hex(blobstring, blob->blob, blob->blob_len); - keyinfo = kasprintf(GFP_KERNEL, keytemplate, blobstring); + blobstring[blob->blob_len * 2] = '\0'; + keyinfo = kasprintf(GFP_KERNEL, keytemplate, blobstring, + session_handle); + if (!keyinfo) { ret = -ENOMEM; goto out; @@ -748,6 +897,13 @@ static int snapshot_load_kernel_key(struct snapshot_data *data, key_put(key); } + if (session_handle != -1) { + if (tpm_try_get_ops(chip) == 0) { + tpm2_flush_context(chip, session_handle); + tpm_put_ops(chip); + } + } + kfree(keyinfo); kfree(blobstring); kfree(digests);