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[2620:137:e000::1:20]) by mx.google.com with ESMTP id e15-20020a1709067e0f00b0097456c647ffsi6314679ejr.447.2023.06.12.17.41.33; Mon, 12 Jun 2023 17:41:57 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@intel.com header.s=Intel header.b=NDEwsYYH; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=intel.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238718AbjFMAQ2 (ORCPT + 99 others); Mon, 12 Jun 2023 20:16:28 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53358 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238733AbjFMAPj (ORCPT ); Mon, 12 Jun 2023 20:15:39 -0400 Received: from mga03.intel.com (mga03.intel.com [134.134.136.65]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 46A6B2686; Mon, 12 Jun 2023 17:13:19 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1686615199; x=1718151199; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=68vHo4+oSqhV8kF+lXavlD4FeK2AToHr3tcBPqqVDm8=; b=NDEwsYYHx40Ep9OMIk9W1/iP7dJnke4QePI7CdyeGzxMV5ajNdl62T88 Y6TCFnKkVf8pkOeKQLhie1xRNENYtsGWviupO47phzUnvwVzSs81yICvs XpDhafxbU9NMXvQMM+LbtiuE7QJlr57p2t0RpcuGaa8TVjkOzFXqIw/Of qcsSWAQC5kJUHCyBJan0ySMjJAY7XPsZlz2iyrQTbMw56qiLGKGKoNnW7 3Ua13iIKiCiBaWVyBK+IxMC4kBBA5hivZkLj5DXgXKBXOSX3EuP/baD5p KIVHX+EBQbi4uzaMbav0H4BXGgnSqnURIkoh2KdGaOFmULaf25C/bclcm Q==; X-IronPort-AV: E=McAfee;i="6600,9927,10739"; a="361557219" X-IronPort-AV: E=Sophos;i="6.00,238,1681196400"; d="scan'208";a="361557219" Received: from orsmga004.jf.intel.com ([10.7.209.38]) by orsmga103.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 12 Jun 2023 17:12:29 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10739"; a="835671067" X-IronPort-AV: E=Sophos;i="6.00,238,1681196400"; d="scan'208";a="835671067" Received: from almeisch-mobl1.amr.corp.intel.com (HELO rpedgeco-desk4.amr.corp.intel.com) ([10.209.42.242]) by orsmga004-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 12 Jun 2023 17:12:28 -0700 From: Rick Edgecombe To: x86@kernel.org, "H . Peter Anvin" , Thomas Gleixner , Ingo Molnar , linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-api@vger.kernel.org, Arnd Bergmann , Andy Lutomirski , Balbir Singh , Borislav Petkov , Cyrill Gorcunov , Dave Hansen , Eugene Syromiatnikov , Florian Weimer , "H . J . Lu" , Jann Horn , Jonathan Corbet , Kees Cook , Mike Kravetz , Nadav Amit , Oleg Nesterov , Pavel Machek , Peter Zijlstra , Randy Dunlap , Weijiang Yang , "Kirill A . Shutemov" , John Allen , kcc@google.com, eranian@google.com, rppt@kernel.org, jamorris@linux.microsoft.com, dethoma@microsoft.com, akpm@linux-foundation.org, Andrew.Cooper3@citrix.com, christina.schimpe@intel.com, david@redhat.com, debug@rivosinc.com, szabolcs.nagy@arm.com, torvalds@linux-foundation.org, broonie@kernel.org Cc: rick.p.edgecombe@intel.com, Yu-cheng Yu , Pengfei Xu Subject: [PATCH v9 24/42] x86/fpu/xstate: Introduce CET MSR and XSAVES supervisor states Date: Mon, 12 Jun 2023 17:10:50 -0700 Message-Id: <20230613001108.3040476-25-rick.p.edgecombe@intel.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20230613001108.3040476-1-rick.p.edgecombe@intel.com> References: <20230613001108.3040476-1-rick.p.edgecombe@intel.com> MIME-Version: 1.0 X-Spam-Status: No, score=-4.4 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_MED, SPF_HELO_NONE,SPF_NONE,T_SCC_BODY_TEXT_LINE,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1768546020526351652?= X-GMAIL-MSGID: =?utf-8?q?1768546020526351652?= Shadow stack register state can be managed with XSAVE. The registers can logically be separated into two groups: * Registers controlling user-mode operation * Registers controlling kernel-mode operation The architecture has two new XSAVE state components: one for each group of those groups of registers. This lets an OS manage them separately if it chooses. Future patches for host userspace and KVM guests will only utilize the user-mode registers, so only configure XSAVE to save user-mode registers. This state will add 16 bytes to the xsave buffer size. Future patches will use the user-mode XSAVE area to save guest user-mode CET state. However, VMCS includes new fields for guest CET supervisor states. KVM can use these to save and restore guest supervisor state, so host supervisor XSAVE support is not required. Adding this exacerbates the already unwieldy if statement in check_xstate_against_struct() that handles warning about unimplemented xfeatures. So refactor these check's by having XCHECK_SZ() set a bool when it actually check's the xfeature. This ends up exceeding 80 chars, but was better on balance than other options explored. Pass the bool as pointer to make it clear that XCHECK_SZ() can change the variable. While configuring user-mode XSAVE, clarify kernel-mode registers are not managed by XSAVE by defining the xfeature in XFEATURE_MASK_SUPERVISOR_UNSUPPORTED, like is done for XFEATURE_MASK_PT. This serves more of a documentation as code purpose, and functionally, only enables a few safety checks. Both XSAVE state components are supervisor states, even the state controlling user-mode operation. This is a departure from earlier features like protection keys where the PKRU state is a normal user (non-supervisor) state. Having the user state be supervisor-managed ensures there is no direct, unprivileged access to it, making it harder for an attacker to subvert CET. To facilitate this privileged access, define the two user-mode CET MSRs, and the bits defined in those MSRs relevant to future shadow stack enablement patches. Co-developed-by: Yu-cheng Yu Signed-off-by: Yu-cheng Yu Signed-off-by: Rick Edgecombe Reviewed-by: Borislav Petkov (AMD) Reviewed-by: Kees Cook Acked-by: Mike Rapoport (IBM) Tested-by: Pengfei Xu Tested-by: John Allen Tested-by: Kees Cook --- arch/x86/include/asm/fpu/types.h | 16 +++++- arch/x86/include/asm/fpu/xstate.h | 6 ++- arch/x86/kernel/fpu/xstate.c | 90 +++++++++++++++---------------- 3 files changed, 61 insertions(+), 51 deletions(-) diff --git a/arch/x86/include/asm/fpu/types.h b/arch/x86/include/asm/fpu/types.h index 7f6d858ff47a..eb810074f1e7 100644 --- a/arch/x86/include/asm/fpu/types.h +++ b/arch/x86/include/asm/fpu/types.h @@ -115,8 +115,8 @@ enum xfeature { XFEATURE_PT_UNIMPLEMENTED_SO_FAR, XFEATURE_PKRU, XFEATURE_PASID, - XFEATURE_RSRVD_COMP_11, - XFEATURE_RSRVD_COMP_12, + XFEATURE_CET_USER, + XFEATURE_CET_KERNEL_UNUSED, XFEATURE_RSRVD_COMP_13, XFEATURE_RSRVD_COMP_14, XFEATURE_LBR, @@ -138,6 +138,8 @@ enum xfeature { #define XFEATURE_MASK_PT (1 << XFEATURE_PT_UNIMPLEMENTED_SO_FAR) #define XFEATURE_MASK_PKRU (1 << XFEATURE_PKRU) #define XFEATURE_MASK_PASID (1 << XFEATURE_PASID) +#define XFEATURE_MASK_CET_USER (1 << XFEATURE_CET_USER) +#define XFEATURE_MASK_CET_KERNEL (1 << XFEATURE_CET_KERNEL_UNUSED) #define XFEATURE_MASK_LBR (1 << XFEATURE_LBR) #define XFEATURE_MASK_XTILE_CFG (1 << XFEATURE_XTILE_CFG) #define XFEATURE_MASK_XTILE_DATA (1 << XFEATURE_XTILE_DATA) @@ -252,6 +254,16 @@ struct pkru_state { u32 pad; } __packed; +/* + * State component 11 is Control-flow Enforcement user states + */ +struct cet_user_state { + /* user control-flow settings */ + u64 user_cet; + /* user shadow stack pointer */ + u64 user_ssp; +}; + /* * State component 15: Architectural LBR configuration state. * The size of Arch LBR state depends on the number of LBRs (lbr_depth). diff --git a/arch/x86/include/asm/fpu/xstate.h b/arch/x86/include/asm/fpu/xstate.h index cd3dd170e23a..d4427b88ee12 100644 --- a/arch/x86/include/asm/fpu/xstate.h +++ b/arch/x86/include/asm/fpu/xstate.h @@ -50,7 +50,8 @@ #define XFEATURE_MASK_USER_DYNAMIC XFEATURE_MASK_XTILE_DATA /* All currently supported supervisor features */ -#define XFEATURE_MASK_SUPERVISOR_SUPPORTED (XFEATURE_MASK_PASID) +#define XFEATURE_MASK_SUPERVISOR_SUPPORTED (XFEATURE_MASK_PASID | \ + XFEATURE_MASK_CET_USER) /* * A supervisor state component may not always contain valuable information, @@ -77,7 +78,8 @@ * Unsupported supervisor features. When a supervisor feature in this mask is * supported in the future, move it to the supported supervisor feature mask. */ -#define XFEATURE_MASK_SUPERVISOR_UNSUPPORTED (XFEATURE_MASK_PT) +#define XFEATURE_MASK_SUPERVISOR_UNSUPPORTED (XFEATURE_MASK_PT | \ + XFEATURE_MASK_CET_KERNEL) /* All supervisor states including supported and unsupported states. */ #define XFEATURE_MASK_SUPERVISOR_ALL (XFEATURE_MASK_SUPERVISOR_SUPPORTED | \ diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c index 0bab497c9436..4fa4751912d9 100644 --- a/arch/x86/kernel/fpu/xstate.c +++ b/arch/x86/kernel/fpu/xstate.c @@ -39,26 +39,26 @@ */ static const char *xfeature_names[] = { - "x87 floating point registers" , - "SSE registers" , - "AVX registers" , - "MPX bounds registers" , - "MPX CSR" , - "AVX-512 opmask" , - "AVX-512 Hi256" , - "AVX-512 ZMM_Hi256" , - "Processor Trace (unused)" , + "x87 floating point registers", + "SSE registers", + "AVX registers", + "MPX bounds registers", + "MPX CSR", + "AVX-512 opmask", + "AVX-512 Hi256", + "AVX-512 ZMM_Hi256", + "Processor Trace (unused)", "Protection Keys User registers", "PASID state", - "unknown xstate feature" , - "unknown xstate feature" , - "unknown xstate feature" , - "unknown xstate feature" , - "unknown xstate feature" , - "unknown xstate feature" , - "AMX Tile config" , - "AMX Tile data" , - "unknown xstate feature" , + "Control-flow User registers", + "Control-flow Kernel registers (unused)", + "unknown xstate feature", + "unknown xstate feature", + "unknown xstate feature", + "unknown xstate feature", + "AMX Tile config", + "AMX Tile data", + "unknown xstate feature", }; static unsigned short xsave_cpuid_features[] __initdata = { @@ -73,6 +73,7 @@ static unsigned short xsave_cpuid_features[] __initdata = { [XFEATURE_PT_UNIMPLEMENTED_SO_FAR] = X86_FEATURE_INTEL_PT, [XFEATURE_PKRU] = X86_FEATURE_PKU, [XFEATURE_PASID] = X86_FEATURE_ENQCMD, + [XFEATURE_CET_USER] = X86_FEATURE_SHSTK, [XFEATURE_XTILE_CFG] = X86_FEATURE_AMX_TILE, [XFEATURE_XTILE_DATA] = X86_FEATURE_AMX_TILE, }; @@ -276,6 +277,7 @@ static void __init print_xstate_features(void) print_xstate_feature(XFEATURE_MASK_Hi16_ZMM); print_xstate_feature(XFEATURE_MASK_PKRU); print_xstate_feature(XFEATURE_MASK_PASID); + print_xstate_feature(XFEATURE_MASK_CET_USER); print_xstate_feature(XFEATURE_MASK_XTILE_CFG); print_xstate_feature(XFEATURE_MASK_XTILE_DATA); } @@ -344,6 +346,7 @@ static __init void os_xrstor_booting(struct xregs_state *xstate) XFEATURE_MASK_BNDREGS | \ XFEATURE_MASK_BNDCSR | \ XFEATURE_MASK_PASID | \ + XFEATURE_MASK_CET_USER | \ XFEATURE_MASK_XTILE) /* @@ -446,14 +449,15 @@ static void __init __xstate_dump_leaves(void) } \ } while (0) -#define XCHECK_SZ(sz, nr, nr_macro, __struct) do { \ - if ((nr == nr_macro) && \ - WARN_ONCE(sz != sizeof(__struct), \ - "%s: struct is %zu bytes, cpu state %d bytes\n", \ - __stringify(nr_macro), sizeof(__struct), sz)) { \ +#define XCHECK_SZ(sz, nr, __struct) ({ \ + if (WARN_ONCE(sz != sizeof(__struct), \ + "[%s]: struct is %zu bytes, cpu state %d bytes\n", \ + xfeature_names[nr], sizeof(__struct), sz)) { \ __xstate_dump_leaves(); \ } \ -} while (0) + true; \ +}) + /** * check_xtile_data_against_struct - Check tile data state size. @@ -527,36 +531,28 @@ static bool __init check_xstate_against_struct(int nr) * Ask the CPU for the size of the state. */ int sz = xfeature_size(nr); + /* * Match each CPU state with the corresponding software * structure. */ - XCHECK_SZ(sz, nr, XFEATURE_YMM, struct ymmh_struct); - XCHECK_SZ(sz, nr, XFEATURE_BNDREGS, struct mpx_bndreg_state); - XCHECK_SZ(sz, nr, XFEATURE_BNDCSR, struct mpx_bndcsr_state); - XCHECK_SZ(sz, nr, XFEATURE_OPMASK, struct avx_512_opmask_state); - XCHECK_SZ(sz, nr, XFEATURE_ZMM_Hi256, struct avx_512_zmm_uppers_state); - XCHECK_SZ(sz, nr, XFEATURE_Hi16_ZMM, struct avx_512_hi16_state); - XCHECK_SZ(sz, nr, XFEATURE_PKRU, struct pkru_state); - XCHECK_SZ(sz, nr, XFEATURE_PASID, struct ia32_pasid_state); - XCHECK_SZ(sz, nr, XFEATURE_XTILE_CFG, struct xtile_cfg); - - /* The tile data size varies between implementations. */ - if (nr == XFEATURE_XTILE_DATA) - check_xtile_data_against_struct(sz); - - /* - * Make *SURE* to add any feature numbers in below if - * there are "holes" in the xsave state component - * numbers. - */ - if ((nr < XFEATURE_YMM) || - (nr >= XFEATURE_MAX) || - (nr == XFEATURE_PT_UNIMPLEMENTED_SO_FAR) || - ((nr >= XFEATURE_RSRVD_COMP_11) && (nr <= XFEATURE_RSRVD_COMP_16))) { + switch (nr) { + case XFEATURE_YMM: return XCHECK_SZ(sz, nr, struct ymmh_struct); + case XFEATURE_BNDREGS: return XCHECK_SZ(sz, nr, struct mpx_bndreg_state); + case XFEATURE_BNDCSR: return XCHECK_SZ(sz, nr, struct mpx_bndcsr_state); + case XFEATURE_OPMASK: return XCHECK_SZ(sz, nr, struct avx_512_opmask_state); + case XFEATURE_ZMM_Hi256: return XCHECK_SZ(sz, nr, struct avx_512_zmm_uppers_state); + case XFEATURE_Hi16_ZMM: return XCHECK_SZ(sz, nr, struct avx_512_hi16_state); + case XFEATURE_PKRU: return XCHECK_SZ(sz, nr, struct pkru_state); + case XFEATURE_PASID: return XCHECK_SZ(sz, nr, struct ia32_pasid_state); + case XFEATURE_XTILE_CFG: return XCHECK_SZ(sz, nr, struct xtile_cfg); + case XFEATURE_CET_USER: return XCHECK_SZ(sz, nr, struct cet_user_state); + case XFEATURE_XTILE_DATA: check_xtile_data_against_struct(sz); return true; + default: XSTATE_WARN_ON(1, "No structure for xstate: %d\n", nr); return false; } + return true; }