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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 73B4EC61DA4 for ; Fri, 3 Feb 2023 19:09:33 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id DDB1D6B0074; Fri, 3 Feb 2023 14:09:32 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id D8A7F6B0075; Fri, 3 Feb 2023 14:09:32 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id C79986B0078; Fri, 3 Feb 2023 14:09:32 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id B9FEF6B0074 for ; Fri, 3 Feb 2023 14:09:32 -0500 (EST) Received: from smtpin06.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay10.hostedemail.com (Postfix) with ESMTP id 754B1C120A for ; Fri, 3 Feb 2023 19:09:32 +0000 (UTC) X-FDA: 80426919384.06.BD10752 Received: from mail.skyhub.de (mail.skyhub.de [5.9.137.197]) by imf17.hostedemail.com (Postfix) with ESMTP id 44BB140007 for ; Fri, 3 Feb 2023 19:09:24 +0000 (UTC) Authentication-Results: imf17.hostedemail.com; dkim=pass header.d=alien8.de header.s=dkim header.b=N8WcH7X0; spf=temperror (imf17.hostedemail.com: error in processing during lookup of bp@alien8.de: DNS error) smtp.mailfrom=bp@alien8.de; dmarc=temperror reason="server fail" header.from=alien8.de (policy=temperror) ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1675451370; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=LXY2XoEteH+dNqMW7AfnSnTBOxxYLXAUN7HmaIMxBkM=; b=CrnvLWvwfF3ahIdh/hzFYW+f3K/ukegaJfEE9tYUxZWqqLDyvPVr+HH85H7L6im9BWYKSV 2FQjouICDgUx5rynmupga3WLP2gz+ega3iw1yyD4wpzwdkqCG7UDTWD1GKmX18cRJ6ifVn HcIgdhpmrF+Wx5Bo6vHxyO6Y6yCl+MM= ARC-Authentication-Results: i=1; imf17.hostedemail.com; dkim=pass header.d=alien8.de header.s=dkim header.b=N8WcH7X0; spf=temperror (imf17.hostedemail.com: error in processing during lookup of bp@alien8.de: DNS error) smtp.mailfrom=bp@alien8.de; dmarc=temperror reason="server fail" header.from=alien8.de (policy=temperror) ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1675451370; a=rsa-sha256; cv=none; b=y7OXERGKgKWH/HzpqUAgyFvq97CHuv6hFTW15fkjHncnZr0BCw6H+7EDvASnAUirRrkfZB ddb7XS3RojgGO4IS7e+LkgeOw0viahptYJDaTFR42eybOIry6dqT07zifwV7rifrAp+Qof 1i+xCTi0V88hhSasXJ2YGd2Mx3TvR6U= Received: from zn.tnic (p5de8e9fe.dip0.t-ipconnect.de [93.232.233.254]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.skyhub.de (SuperMail on ZX Spectrum 128k) with ESMTPSA id C593D1EC04E2; Fri, 3 Feb 2023 20:09:20 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alien8.de; s=dkim; t=1675451360; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:in-reply-to:in-reply-to: references:references; bh=LXY2XoEteH+dNqMW7AfnSnTBOxxYLXAUN7HmaIMxBkM=; b=N8WcH7X0tVKglRYLqZtDwZoK8S+1l2pz7CtwpUyF9jIHUhxEgOvmxEiarZF7XyQmhxIttC 4RpkcwEUAfMrKVn+FwZuu3wBPI67biMbhwYr4g060noTNhZ0fBz+HtT1rvxDsfYWg32T7n b/qJbY+RUHNvJw2Y50jVoYs5SSZFBig= Date: Fri, 3 Feb 2023 20:09:15 +0100 From: Borislav Petkov To: Rick Edgecombe Cc: 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 , 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, Yu-cheng Yu , Michael Kerrisk Subject: Re: [PATCH v5 07/39] x86: Add user control-protection fault handler Message-ID: References: <20230119212317.8324-1-rick.p.edgecombe@intel.com> <20230119212317.8324-8-rick.p.edgecombe@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20230119212317.8324-8-rick.p.edgecombe@intel.com> X-Rspam-User: X-Rspamd-Server: rspam03 X-Stat-Signature: 7yt3gna9odheoxddmopiaamw6bsnbzbs X-Rspamd-Queue-Id: 44BB140007 X-HE-Tag: 1675451364-544450 X-HE-Meta: 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 xFwHIghc vxgtDmCsUOeqsSTlkRQhgiw8nVtaP8WFwULHVFHv0bKFhGZatsinAzcBvNkGzjSqu+8bJJOcf0gRtCf8JZ9ZoMP1SXsYC5LcjChvNijkcU+/dsxTn+Sg6ODc7YKMj64ndUqd+O+Biw947BnazbRGVNa5E6Can0hMBXYUxBgMA7r+5Yb2hVQNJIgI71OG2lDqlSwDTz3EdO0ng+j2g1BtXMN/23663whHYkgr6t8iCmpH43BQoysKHxn5yQMDeGK/QHQ0N28EGhCLC1MX/7Il75sneGsbAoOdntVL6RD/mHpmuaZnceJPiemxrjrHOUdSFxcsiR3qRj8+erDl4igIgsmyod50gHzn/t5k/w1IqsaVhOPemqmaBWf2AyJEEaVFMaZ14 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: On Thu, Jan 19, 2023 at 01:22:45PM -0800, Rick Edgecombe wrote: > Subject: Re: [PATCH v5 07/39] x86: Add user control-protection fault handler Subject: x86/shstk: Add... > 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. ... > diff --git a/arch/x86/kernel/cet.c b/arch/x86/kernel/cet.c > new file mode 100644 > index 000000000000..33d7d119be26 > --- /dev/null > +++ b/arch/x86/kernel/cet.c > @@ -0,0 +1,152 @@ > +// SPDX-License-Identifier: GPL-2.0 > + > +#include > +#include > +#include > + > +enum cp_error_code { > + CP_EC = (1 << 15) - 1, That looks like a mask, so CP_EC_MASK I guess. > + > + CP_RET = 1, > + CP_IRET = 2, > + CP_ENDBR = 3, > + CP_RSTRORSSP = 4, > + CP_SETSSBSY = 5, > + > + CP_ENCL = 1 << 15, > +}; ... > +static void do_user_cp_fault(struct pt_regs *regs, unsigned long error_code) > +{ > + struct task_struct *tsk; > + unsigned long ssp; > + > + /* > + * An exception was just taken from userspace. Since interrupts are disabled > + * here, no scheduling should have messed with the registers yet and they > + * will be whatever is live in userspace. So read the SSP before enabling > + * interrupts so locking the fpregs to do it later is not required. > + */ > + rdmsrl(MSR_IA32_PL3_SSP, ssp); > + > + cond_local_irq_enable(regs); > + > + tsk = current; Hmm, should you read current before you enable interrupts? Not that it changes from under us... > + 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)) { > + pr_emerg("%s[%d] control protection ip:%lx sp:%lx ssp:%lx error:%lx(%s)%s", > + tsk->comm, task_pid_nr(tsk), > + regs->ip, regs->sp, ssp, error_code, > + cp_err_string(error_code), > + error_code & CP_ENCL ? " in enclave" : ""); > + 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); > +} -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette