From patchwork Tue Apr 27 20:42:51 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yu-cheng Yu X-Patchwork-Id: 12227235 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id EC33EC43461 for ; Tue, 27 Apr 2021 20:44:24 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 9D1E6613B0 for ; Tue, 27 Apr 2021 20:44:24 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9D1E6613B0 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id EB1C66B0078; Tue, 27 Apr 2021 16:44:13 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id DC1CB6B007B; Tue, 27 Apr 2021 16:44:13 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 951686B0078; Tue, 27 Apr 2021 16:44:13 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0192.hostedemail.com [216.40.44.192]) by kanga.kvack.org (Postfix) with ESMTP id 3BCE06B0073 for ; Tue, 27 Apr 2021 16:44:13 -0400 (EDT) Received: from smtpin40.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 02AF64417 for ; Tue, 27 Apr 2021 20:44:12 +0000 (UTC) X-FDA: 78079324386.40.C8A1328 Received: from mga04.intel.com (mga04.intel.com [192.55.52.120]) by imf11.hostedemail.com (Postfix) with ESMTP id 4EF5F200025C for ; Tue, 27 Apr 2021 20:43:57 +0000 (UTC) IronPort-SDR: WcrR3bGLUmLJLL5Lt115oSt9DM7Rr7sYwCKR9eOvTw5+oKg+dicTwanI6a8o2H83SaIf1mYA1u JnuIiezJZ8IA== X-IronPort-AV: E=McAfee;i="6200,9189,9967"; a="194473649" X-IronPort-AV: E=Sophos;i="5.82,255,1613462400"; d="scan'208";a="194473649" Received: from orsmga001.jf.intel.com ([10.7.209.18]) by fmsmga104.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 27 Apr 2021 13:44:10 -0700 IronPort-SDR: j6jj2Bo1P7nFi54Wldg40UuFycj2vNuL3SpeAQ3d/iWRP+SPOkzJM+4DqaKOt1iCfbEIf3P9Fe xdnaBuY7+rrg== X-IronPort-AV: E=Sophos;i="5.82,255,1613462400"; d="scan'208";a="465623446" Received: from yyu32-desk.sc.intel.com ([143.183.136.146]) by orsmga001-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 27 Apr 2021 13:44:09 -0700 From: Yu-cheng Yu 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" , Vedvyas Shanbhogue , Dave Martin , Weijiang Yang , Pengfei Xu , Haitao Huang Cc: Yu-cheng Yu , Michael Kerrisk Subject: [PATCH v26 06/30] x86/cet: Add control-protection fault handler Date: Tue, 27 Apr 2021 13:42:51 -0700 Message-Id: <20210427204315.24153-7-yu-cheng.yu@intel.com> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20210427204315.24153-1-yu-cheng.yu@intel.com> References: <20210427204315.24153-1-yu-cheng.yu@intel.com> MIME-Version: 1.0 X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 4EF5F200025C X-Stat-Signature: i6deg5iumrgnr1ng6uxzdz1sbedu6d75 Received-SPF: none (intel.com>: No applicable sender policy available) receiver=imf11; identity=mailfrom; envelope-from=""; helo=mga04.intel.com; client-ip=192.55.52.120 X-HE-DKIM-Result: none/none X-HE-Tag: 1619556237-802741 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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 Cc: Kees Cook Cc: Michael Kerrisk --- v25: - Change CONFIG_X86_CET to CONFIG_X86_SHADOW_STACK. - Change X86_FEATURE_CET to X86_FEATURE_SHSTK. 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 | 63 ++++++++++++++++++++++++++++++ include/uapi/asm-generic/siginfo.h | 3 +- 5 files changed, 74 insertions(+), 2 deletions(-) diff --git a/arch/x86/include/asm/idtentry.h b/arch/x86/include/asm/idtentry.h index 5eb3bdf36a41..5791c02864ec 100644 --- a/arch/x86/include/asm/idtentry.h +++ b/arch/x86/include/asm/idtentry.h @@ -571,6 +571,10 @@ 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 ee1a283f8e96..0315fb297dd3 100644 --- a/arch/x86/kernel/idt.c +++ b/arch/x86/kernel/idt.c @@ -105,6 +105,10 @@ 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 a5330ff498f0..dd92490b1e7f 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 != 5); BUILD_BUG_ON(NSIGCHLD != 6); diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index 651e3e508959..a40b34b09400 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -39,6 +39,7 @@ #include #include #include +#include #include #include @@ -606,6 +607,68 @@ 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)) { + pr_emerg("PANIC: unexpected kernel control protection fault\n"); + die("kernel control protection fault", regs, error_code); + panic("Machine halted."); + } + + cond_local_irq_enable(regs); + + if (!boot_cpu_has(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 d2597000407a..1c2ea91284a0 100644 --- a/include/uapi/asm-generic/siginfo.h +++ b/include/uapi/asm-generic/siginfo.h @@ -231,7 +231,8 @@ 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