From mboxrd@z Thu Jan 1 00:00:00 1970 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 70E0FC433EF for ; Sun, 30 Jan 2022 21:22:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1356611AbiA3VWH (ORCPT ); Sun, 30 Jan 2022 16:22:07 -0500 Received: from mga06.intel.com ([134.134.136.31]:52015 "EHLO mga06.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1356315AbiA3VV4 (ORCPT ); Sun, 30 Jan 2022 16:21:56 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1643577716; x=1675113716; h=from:to:cc:subject:date:message-id:in-reply-to: references; bh=Nk1tOIdLVz+bQkgFftn6rPnhzAu43sdXIuQHcD9KXX4=; b=jxUGu5v3y9fzcw1Wafx2EhM5Mp175INZLv2HMckcmunOspbWnPx1nsOI K3JNeBMDqTj+glIY6IPrIjtsZR1Z/bXSMztaSn6Z8UBTqjjnlgSQhgkPq oh9JRFIb7pjuLCE/ni8bBYtK0/7Y9mPV/nR2hOsmXYbOfvZNQrcYdoy4S noFvfWW77QLWUOtippgDAOhYfQ3rVzvVwlE60hJOXiVvwKOilfsveEQDO N/4ysTOoZa8RUWm8ZU1bk+5oaHdtdKuWN0UFj8CZ3L4/+YxnrQujZ054Q xs93poI9gj3OlGyygzjBKq545RnzYe0yykB+yFTNpAR92rj6DwWTZWfGu A==; X-IronPort-AV: E=McAfee;i="6200,9189,10243"; a="308104900" X-IronPort-AV: E=Sophos;i="5.88,329,1635231600"; d="scan'208";a="308104900" Received: from orsmga008.jf.intel.com ([10.7.209.65]) by orsmga104.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 30 Jan 2022 13:21:51 -0800 X-IronPort-AV: E=Sophos;i="5.88,329,1635231600"; d="scan'208";a="536856701" Received: from avmallar-mobl1.amr.corp.intel.com (HELO rpedgeco-desk.amr.corp.intel.com) ([10.209.123.171]) by orsmga008-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 30 Jan 2022 13:21:50 -0800 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 , "Ravi V . Shankar" , Dave Martin , Weijiang Yang , "Kirill A . Shutemov" , joao.moreira@intel.com, John Allen , kcc@google.com, eranian@google.com Cc: rick.p.edgecombe@intel.com, Yu-cheng Yu , Michael Kerrisk Subject: [PATCH 06/35] x86/cet: Add control-protection fault handler Date: Sun, 30 Jan 2022 13:18:09 -0800 Message-Id: <20220130211838.8382-7-rick.p.edgecombe@intel.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20220130211838.8382-1-rick.p.edgecombe@intel.com> References: <20220130211838.8382-1-rick.p.edgecombe@intel.com> Precedence: bulk List-ID: X-Mailing-List: linux-api@vger.kernel.org From: Yu-cheng Yu A control-protection fault is triggered when a control-flow transfer attempt violates Shadow Stack or Indirect Branch Tracking constraints. For example, the return address for a RET instruction differs from the copy on the shadow stack; or an indirect JMP instruction, without the NOTRACK prefix, arrives at a non-ENDBR opcode. The control-protection fault handler works in a similar way as the general protection fault handler. It provides the si_code SEGV_CPERR to the signal handler. Signed-off-by: Yu-cheng Yu Signed-off-by: Rick Edgecombe Cc: Kees Cook Cc: Michael Kerrisk --- v1: - Update static asserts for NSIGSEGV Yu-cheng v29: - Remove pr_emerg() since it is followed by die(). - Change boot_cpu_has() to cpu_feature_enabled(). Yu-cheng v25: - Change CONFIG_X86_CET to CONFIG_X86_SHADOW_STACK. - Change X86_FEATURE_CET to X86_FEATURE_SHSTK. arch/arm/kernel/signal.c | 2 +- arch/arm64/kernel/signal.c | 2 +- arch/arm64/kernel/signal32.c | 2 +- arch/sparc/kernel/signal32.c | 2 +- arch/sparc/kernel/signal_64.c | 2 +- arch/x86/include/asm/idtentry.h | 4 ++ arch/x86/kernel/idt.c | 4 ++ arch/x86/kernel/signal_compat.c | 2 +- arch/x86/kernel/traps.c | 62 ++++++++++++++++++++++++++++++ include/uapi/asm-generic/siginfo.h | 3 +- 10 files changed, 78 insertions(+), 7 deletions(-) diff --git a/arch/arm/kernel/signal.c b/arch/arm/kernel/signal.c index c532a6041066..59aaadce9d52 100644 --- a/arch/arm/kernel/signal.c +++ b/arch/arm/kernel/signal.c @@ -681,7 +681,7 @@ asmlinkage void do_rseq_syscall(struct pt_regs *regs) */ static_assert(NSIGILL == 11); static_assert(NSIGFPE == 15); -static_assert(NSIGSEGV == 9); +static_assert(NSIGSEGV == 10); static_assert(NSIGBUS == 5); static_assert(NSIGTRAP == 6); static_assert(NSIGCHLD == 6); diff --git a/arch/arm64/kernel/signal.c b/arch/arm64/kernel/signal.c index d8aaf4b6f432..d2da57c415b8 100644 --- a/arch/arm64/kernel/signal.c +++ b/arch/arm64/kernel/signal.c @@ -983,7 +983,7 @@ void __init minsigstksz_setup(void) */ static_assert(NSIGILL == 11); static_assert(NSIGFPE == 15); -static_assert(NSIGSEGV == 9); +static_assert(NSIGSEGV == 10); static_assert(NSIGBUS == 5); static_assert(NSIGTRAP == 6); static_assert(NSIGCHLD == 6); diff --git a/arch/arm64/kernel/signal32.c b/arch/arm64/kernel/signal32.c index d984282b979f..8776a34c6444 100644 --- a/arch/arm64/kernel/signal32.c +++ b/arch/arm64/kernel/signal32.c @@ -460,7 +460,7 @@ void compat_setup_restart_syscall(struct pt_regs *regs) */ static_assert(NSIGILL == 11); static_assert(NSIGFPE == 15); -static_assert(NSIGSEGV == 9); +static_assert(NSIGSEGV == 10); static_assert(NSIGBUS == 5); static_assert(NSIGTRAP == 6); static_assert(NSIGCHLD == 6); diff --git a/arch/sparc/kernel/signal32.c b/arch/sparc/kernel/signal32.c index 6cc124a3bb98..dc50b2a78692 100644 --- a/arch/sparc/kernel/signal32.c +++ b/arch/sparc/kernel/signal32.c @@ -752,7 +752,7 @@ asmlinkage int do_sys32_sigstack(u32 u_ssptr, u32 u_ossptr, unsigned long sp) */ static_assert(NSIGILL == 11); static_assert(NSIGFPE == 15); -static_assert(NSIGSEGV == 9); +static_assert(NSIGSEGV == 10); static_assert(NSIGBUS == 5); static_assert(NSIGTRAP == 6); static_assert(NSIGCHLD == 6); diff --git a/arch/sparc/kernel/signal_64.c b/arch/sparc/kernel/signal_64.c index 2a78d2af1265..7fe2bd37bd1a 100644 --- a/arch/sparc/kernel/signal_64.c +++ b/arch/sparc/kernel/signal_64.c @@ -562,7 +562,7 @@ void do_notify_resume(struct pt_regs *regs, unsigned long orig_i0, unsigned long */ static_assert(NSIGILL == 11); static_assert(NSIGFPE == 15); -static_assert(NSIGSEGV == 9); +static_assert(NSIGSEGV == 10); static_assert(NSIGBUS == 5); static_assert(NSIGTRAP == 6); static_assert(NSIGCHLD == 6); diff --git a/arch/x86/include/asm/idtentry.h b/arch/x86/include/asm/idtentry.h index 1345088e9902..a90791433152 100644 --- a/arch/x86/include/asm/idtentry.h +++ b/arch/x86/include/asm/idtentry.h @@ -562,6 +562,10 @@ DECLARE_IDTENTRY_ERRORCODE(X86_TRAP_SS, exc_stack_segment); DECLARE_IDTENTRY_ERRORCODE(X86_TRAP_GP, exc_general_protection); DECLARE_IDTENTRY_ERRORCODE(X86_TRAP_AC, exc_alignment_check); +#ifdef CONFIG_X86_SHADOW_STACK +DECLARE_IDTENTRY_ERRORCODE(X86_TRAP_CP, exc_control_protection); +#endif + /* Raw exception entries which need extra work */ DECLARE_IDTENTRY_RAW(X86_TRAP_UD, exc_invalid_op); DECLARE_IDTENTRY_RAW(X86_TRAP_BP, exc_int3); diff --git a/arch/x86/kernel/idt.c b/arch/x86/kernel/idt.c index df0fa695bb09..9f1bdaabc246 100644 --- a/arch/x86/kernel/idt.c +++ b/arch/x86/kernel/idt.c @@ -113,6 +113,10 @@ static const __initconst struct idt_data def_idts[] = { #elif defined(CONFIG_X86_32) SYSG(IA32_SYSCALL_VECTOR, entry_INT80_32), #endif + +#ifdef CONFIG_X86_SHADOW_STACK + INTG(X86_TRAP_CP, asm_exc_control_protection), +#endif }; /* diff --git a/arch/x86/kernel/signal_compat.c b/arch/x86/kernel/signal_compat.c index b52407c56000..ff50cd978ea5 100644 --- a/arch/x86/kernel/signal_compat.c +++ b/arch/x86/kernel/signal_compat.c @@ -27,7 +27,7 @@ static inline void signal_compat_build_tests(void) */ BUILD_BUG_ON(NSIGILL != 11); BUILD_BUG_ON(NSIGFPE != 15); - BUILD_BUG_ON(NSIGSEGV != 9); + BUILD_BUG_ON(NSIGSEGV != 10); BUILD_BUG_ON(NSIGBUS != 5); BUILD_BUG_ON(NSIGTRAP != 6); BUILD_BUG_ON(NSIGCHLD != 6); diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index c9d566dcf89a..54b7a146fd5e 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -39,6 +39,7 @@ #include #include #include +#include #include #include @@ -641,6 +642,67 @@ DEFINE_IDTENTRY_ERRORCODE(exc_general_protection) cond_local_irq_disable(regs); } +#ifdef CONFIG_X86_SHADOW_STACK +static const char * const control_protection_err[] = { + "unknown", + "near-ret", + "far-ret/iret", + "endbranch", + "rstorssp", + "setssbsy", + "unknown", +}; + +static DEFINE_RATELIMIT_STATE(cpf_rate, DEFAULT_RATELIMIT_INTERVAL, + DEFAULT_RATELIMIT_BURST); + +/* + * When a control protection exception occurs, send a signal to the responsible + * application. Currently, control protection is only enabled for user mode. + * This exception should not come from kernel mode. + */ +DEFINE_IDTENTRY_ERRORCODE(exc_control_protection) +{ + struct task_struct *tsk; + + if (!user_mode(regs)) { + die("kernel control protection fault", regs, error_code); + panic("Unexpected kernel control protection fault. Machine halted."); + } + + cond_local_irq_enable(regs); + + if (!cpu_feature_enabled(X86_FEATURE_SHSTK)) + WARN_ONCE(1, "Control protection fault with CET support disabled\n"); + + tsk = current; + tsk->thread.error_code = error_code; + tsk->thread.trap_nr = X86_TRAP_CP; + + /* + * Ratelimit to prevent log spamming. + */ + if (show_unhandled_signals && unhandled_signal(tsk, SIGSEGV) && + __ratelimit(&cpf_rate)) { + unsigned long ssp; + int cpf_type; + + cpf_type = array_index_nospec(error_code, ARRAY_SIZE(control_protection_err)); + + rdmsrl(MSR_IA32_PL3_SSP, ssp); + pr_emerg("%s[%d] control protection ip:%lx sp:%lx ssp:%lx error:%lx(%s)", + tsk->comm, task_pid_nr(tsk), + regs->ip, regs->sp, ssp, error_code, + control_protection_err[cpf_type]); + print_vma_addr(KERN_CONT " in ", regs->ip); + pr_cont("\n"); + } + + force_sig_fault(SIGSEGV, SEGV_CPERR, (void __user *)0); + cond_local_irq_disable(regs); +} +#endif + static bool do_int3(struct pt_regs *regs) { int res; diff --git a/include/uapi/asm-generic/siginfo.h b/include/uapi/asm-generic/siginfo.h index 3ba180f550d7..081f4b37d22c 100644 --- a/include/uapi/asm-generic/siginfo.h +++ b/include/uapi/asm-generic/siginfo.h @@ -240,7 +240,8 @@ typedef struct siginfo { #define SEGV_ADIPERR 7 /* Precise MCD exception */ #define SEGV_MTEAERR 8 /* Asynchronous ARM MTE error */ #define SEGV_MTESERR 9 /* Synchronous ARM MTE exception */ -#define NSIGSEGV 9 +#define SEGV_CPERR 10 /* Control protection fault */ +#define NSIGSEGV 10 /* * SIGBUS si_codes -- 2.17.1