From patchwork Wed May 24 16:57:12 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Chang S. Bae" X-Patchwork-Id: 13254319 X-Patchwork-Delegate: herbert@gondor.apana.org.au 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 5DEE6C77B73 for ; Wed, 24 May 2023 17:10:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232784AbjEXRKr (ORCPT ); Wed, 24 May 2023 13:10:47 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36824 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235164AbjEXRKm (ORCPT ); Wed, 24 May 2023 13:10:42 -0400 Received: from mga18.intel.com (mga18.intel.com [134.134.136.126]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 16F9F180; Wed, 24 May 2023 10:10:24 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1684948224; x=1716484224; h=from:to:cc:subject:date:message-id:in-reply-to: references; bh=hNwP92Fv0O2IjL5reMXC0VMmleDiOlnYLtu6Ii1PZt4=; b=OOfnugxpGyccFuvrftoCdTAD7G9FXxOc/WMnMGBRFEbWk072N8V3FmhW DfhyqDf6yf4hmI+Wxo+nxkISsTb9U47OhOTk9L5Ood5s6vYCht7KLeF5R 7PNJE1xK5O1Eq7dOjAlDbv2HAoEp7Ia+n4yR6bT4mK4RLo/sDK+V1AlPJ PAy6IYY1wHuwtTEkVvA21IhnaXckOc1JHUdjwhmgrwKOVMooWoy78AQPl OMxKzTM9Op8kbQRYqUpHSTowXNCksJv6tCifdBlxRks1nqIp/icxZxflO L/8oV5n7nshGTz03WW+gGq4sKXkk345SMJ4mkISq6hXYvOW5nKtFtMAVU Q==; X-IronPort-AV: E=McAfee;i="6600,9927,10720"; a="338206739" X-IronPort-AV: E=Sophos;i="6.00,189,1681196400"; d="scan'208";a="338206739" Received: from orsmga002.jf.intel.com ([10.7.209.21]) by orsmga106.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 24 May 2023 10:09:54 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10720"; a="704427356" X-IronPort-AV: E=Sophos;i="6.00,189,1681196400"; d="scan'208";a="704427356" Received: from chang-linux-3.sc.intel.com ([172.25.66.173]) by orsmga002.jf.intel.com with ESMTP; 24 May 2023 10:09:54 -0700 From: "Chang S. Bae" To: linux-kernel@vger.kernel.org, linux-crypto@vger.kernel.org, dm-devel@redhat.com Cc: ebiggers@kernel.org, elliott@hpe.com, gmazyland@gmail.com, luto@kernel.org, dave.hansen@linux.intel.com, tglx@linutronix.de, bp@alien8.de, mingo@kernel.org, x86@kernel.org, herbert@gondor.apana.org.au, ardb@kernel.org, dan.j.williams@intel.com, bernie.keany@intel.com, charishma1.gairuboyina@intel.com, lalithambika.krishnakumar@intel.com, nhuck@google.com, chang.seok.bae@intel.com, Ingo Molnar , "H. Peter Anvin" , Peter Zijlstra Subject: [PATCH v7 07/12] x86/cpu/keylocker: Load a wrapping key at boot-time Date: Wed, 24 May 2023 09:57:12 -0700 Message-Id: <20230524165717.14062-8-chang.seok.bae@intel.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20230524165717.14062-1-chang.seok.bae@intel.com> References: <20230410225936.8940-1-chang.seok.bae@intel.com> <20230524165717.14062-1-chang.seok.bae@intel.com> Precedence: bulk List-ID: X-Mailing-List: linux-crypto@vger.kernel.org The wrapping key is an entity to encode a clear text key into a key handle. This key is a pivot in protecting user keys. So the value has to be randomized before being loaded in the software-invisible CPU state. The wrapping key needs to be established before the first user. Given that the only proposed Linux use case for Key Locker is dm-crypt, the feature could be lazily enabled when the first dm-crypt user arrives. But there is no precedent for late enabling of CPU features and it adds maintenance burden without demonstrative benefit outside of minimizing the visibility of Key Locker to userspace. Therefore, generate random bytes and load them at boot time. Ensure the dynamic CPU bit (CPUID.AESKLE) is set before the load and flush out these bytes after that. Given that the Linux Key Locker support is only intended for bare metal dm-crypt consumption, and that switching wrapping key per VM is untenable, explicitly skip this setup in the X86_FEATURE_HYPERVISOR case. Signed-off-by: Chang S. Bae Reviewed-by: Dan Williams Cc: Thomas Gleixner Cc: Ingo Molnar Cc: Borislav Petkov Cc: Dave Hansen Cc: "H. Peter Anvin" Cc: Peter Zijlstra Cc: x86@kernel.org Cc: linux-kernel@vger.kernel.org --- Changes from v6: * Switch to use 'static inline' for the empty functions, instead of macro that disallows type checks. (Eric Biggers and Dave Hansen) * Use memzero_explicit() to wipe out the key data instead of writing the poison value over there. (Robert Elliott) * Massage the changelog for the better readability. Changes from v5: * Call out the disabling when the feature is available on a virtual machine. Then, it will turn off the feature flag Changes from RFC v2: * Make bare metal only. * Clean up the code (e.g. dynamically allocate the key cache). (Dan Williams) * Massage the changelog. * Move out the LOADIWKEY wrapper and the Key Locker CPUID defines. Note, Dan wonders that given that the only proposed Linux use case for Key Locker is dm-crypt, the feature could be lazily enabled when the first dm-crypt user arrives, but as Dave notes there is no precedent for late enabling of CPU features and it adds maintenance burden without demonstrative benefit outside of minimizing the visibility of Key Locker to userspace. --- arch/x86/include/asm/keylocker.h | 9 ++++ arch/x86/kernel/Makefile | 1 + arch/x86/kernel/cpu/common.c | 5 +- arch/x86/kernel/keylocker.c | 82 ++++++++++++++++++++++++++++++++ arch/x86/kernel/smpboot.c | 2 + 5 files changed, 98 insertions(+), 1 deletion(-) create mode 100644 arch/x86/kernel/keylocker.c diff --git a/arch/x86/include/asm/keylocker.h b/arch/x86/include/asm/keylocker.h index 1717e0866254..9040e10ab648 100644 --- a/arch/x86/include/asm/keylocker.h +++ b/arch/x86/include/asm/keylocker.h @@ -5,6 +5,7 @@ #ifndef __ASSEMBLY__ +#include #include #include @@ -28,5 +29,13 @@ struct iwkey { #define KEYLOCKER_CPUID_EBX_WIDE BIT(2) #define KEYLOCKER_CPUID_EBX_BACKUP BIT(4) +#ifdef CONFIG_X86_KEYLOCKER +void setup_keylocker(struct cpuinfo_x86 *c); +void destroy_keylocker_data(void); +#else +static inline void setup_keylocker(struct cpuinfo_x86 *c) { } +static inline void destroy_keylocker_data(void) { } +#endif + #endif /*__ASSEMBLY__ */ #endif /* _ASM_KEYLOCKER_H */ diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile index 4070a01c11b7..9e2647320dc6 100644 --- a/arch/x86/kernel/Makefile +++ b/arch/x86/kernel/Makefile @@ -134,6 +134,7 @@ obj-$(CONFIG_PERF_EVENTS) += perf_regs.o obj-$(CONFIG_TRACING) += tracepoint.o obj-$(CONFIG_SCHED_MC_PRIO) += itmt.o obj-$(CONFIG_X86_UMIP) += umip.o +obj-$(CONFIG_X86_KEYLOCKER) += keylocker.o obj-$(CONFIG_UNWINDER_ORC) += unwind_orc.o obj-$(CONFIG_UNWINDER_FRAME_POINTER) += unwind_frame.o diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index 8f284e185aea..5882ff6e3c6b 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -58,6 +58,8 @@ #include #include #include +#include + #include #include #include @@ -1834,10 +1836,11 @@ static void identify_cpu(struct cpuinfo_x86 *c) /* Disable the PN if appropriate */ squash_the_stupid_serial_number(c); - /* Set up SMEP/SMAP/UMIP */ + /* Setup various Intel-specific CPU security features */ setup_smep(c); setup_smap(c); setup_umip(c); + setup_keylocker(c); /* Enable FSGSBASE instructions if available. */ if (cpu_has(c, X86_FEATURE_FSGSBASE)) { diff --git a/arch/x86/kernel/keylocker.c b/arch/x86/kernel/keylocker.c new file mode 100644 index 000000000000..038e5268e6b8 --- /dev/null +++ b/arch/x86/kernel/keylocker.c @@ -0,0 +1,82 @@ +// SPDX-License-Identifier: GPL-2.0-only + +/* + * Setup Key Locker feature and support the wrapping key management. + */ + +#include +#include +#include + +#include +#include +#include + +static __initdata struct keylocker_setup_data { + struct iwkey key; +} kl_setup; + +static void __init generate_keylocker_data(void) +{ + get_random_bytes(&kl_setup.key.integrity_key, sizeof(kl_setup.key.integrity_key)); + get_random_bytes(&kl_setup.key.encryption_key, sizeof(kl_setup.key.encryption_key)); +} + +void __init destroy_keylocker_data(void) +{ + memzero_explicit(&kl_setup.key, sizeof(kl_setup.key)); +} + +static void __init load_keylocker(void) +{ + kernel_fpu_begin(); + load_xmm_iwkey(&kl_setup.key); + kernel_fpu_end(); +} + +/** + * setup_keylocker - Enable the feature. + * @c: A pointer to struct cpuinfo_x86 + */ +void __ref setup_keylocker(struct cpuinfo_x86 *c) +{ + if (!cpu_feature_enabled(X86_FEATURE_KEYLOCKER)) + goto out; + + if (cpu_feature_enabled(X86_FEATURE_HYPERVISOR)) { + pr_debug("x86/keylocker: Not compatible with a hypervisor.\n"); + goto disable; + } + + cr4_set_bits(X86_CR4_KEYLOCKER); + + if (c == &boot_cpu_data) { + u32 eax, ebx, ecx, edx; + + cpuid_count(KEYLOCKER_CPUID, 0, &eax, &ebx, &ecx, &edx); + /* + * Check the feature readiness via CPUID. Note that the + * CPUID AESKLE bit is conditionally set only when CR4.KL + * is set. + */ + if (!(ebx & KEYLOCKER_CPUID_EBX_AESKLE) || + !(eax & KEYLOCKER_CPUID_EAX_SUPERVISOR)) { + pr_debug("x86/keylocker: Not fully supported.\n"); + goto disable; + } + + generate_keylocker_data(); + } + + load_keylocker(); + + pr_info_once("x86/keylocker: Enabled.\n"); + return; + +disable: + setup_clear_cpu_cap(X86_FEATURE_KEYLOCKER); + pr_info_once("x86/keylocker: Disabled.\n"); +out: + /* Make sure the feature disabled for kexec-reboot. */ + cr4_clear_bits(X86_CR4_KEYLOCKER); +} diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c index e82be82cda55..41f24ab74fb9 100644 --- a/arch/x86/kernel/smpboot.c +++ b/arch/x86/kernel/smpboot.c @@ -86,6 +86,7 @@ #include #include #include +#include /* representing HT siblings of each logical CPU */ DEFINE_PER_CPU_READ_MOSTLY(cpumask_var_t, cpu_sibling_map); @@ -1386,6 +1387,7 @@ void __init native_smp_cpus_done(unsigned int max_cpus) nmi_selftest(); impress_friends(); cache_aps_init(); + destroy_keylocker_data(); } static int __initdata setup_possible_cpus = -1;