From patchwork Fri Apr 26 23:22:43 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Nadav Amit X-Patchwork-Id: 10920069 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id B090714D5 for ; Sat, 27 Apr 2019 06:45:10 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id A294D2883A for ; Sat, 27 Apr 2019 06:45:10 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 9697928862; Sat, 27 Apr 2019 06:45:10 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.5 required=2.0 tests=BAYES_00,DATE_IN_PAST_06_12, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FROM,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 3EA902883A for ; Sat, 27 Apr 2019 06:45:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726374AbfD0GnK (ORCPT ); Sat, 27 Apr 2019 02:43:10 -0400 Received: from mail-pl1-f196.google.com ([209.85.214.196]:33820 "EHLO mail-pl1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726001AbfD0GnJ (ORCPT ); Sat, 27 Apr 2019 02:43:09 -0400 Received: by mail-pl1-f196.google.com with SMTP id d5so1988647plr.1; Fri, 26 Apr 2019 23:43:09 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=wqvLZPneRcLgxY6Wjfk6EEQBPauaGcOxn9fq0yjJ9xE=; b=vdYahecrwl2Sp5UawSR3og0bnv/oKfDwV/Dqodp6SG75rtt3oI1BxkHqScjMRc/B0U ndpm0CSM99X5DI5nXyZ0qilWlZ5y+YmffvE0rzTsPOh9Lg0wVC5gzIbXO3T2rI/43jKw dSv/fQEMrgklgF9DfRp0UTkxOOmbTA2q76DVrniyNWh8V594RE3EBRYYfPR9C72DIbVe QvUfF6WjCix52aEKKarcvG6J8JGMJ6kiAHPNxAecwgyTiM6P6ST8UlxjffLYXWC/UN5g Hhv9thRtl94b6Emad3qIhmqwC571N8N4kkx/zbp3oEc24WAmffQk4ZXiiSSJrBGsI7VY gu0w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=wqvLZPneRcLgxY6Wjfk6EEQBPauaGcOxn9fq0yjJ9xE=; b=sBGy4iBLh+YH3Vxoc5sewmFwb6rcbAnc/LfYQ+mQ2MNO8Y4II2Cz6J2gZEyc2s1wEU 4fgP8YiMkq9MdEkZDEAQzeh65SK9/cCPBdwV60HOvlaKkgM5wB4bMl+/TpLLfYve2Fm4 5cdTiHY74Z6eGInaz3bQPwkomNOe5HsIGjUclYn6SfZbb7Zhu4iuu+GDXllRl+ckqhhD D8nTbg7x55e3eUEgy6a4DG2XINGIfLFmrBqumCK51LzsdKv5lsBZgOAlvwHVVzBn+dkG du37msilFuHAZDe4AXrVZkLQALtuE35lbLSbP+hJSOyIwnMAVh6c6lsHgMNjAqU1JN+R t9GQ== X-Gm-Message-State: APjAAAWvfm7NzmDxx0yJ1YgvNqsw4OPVTp3mpWQNySQwrQ/Ev/XVN30K yib+jqHHG3sT4M9DdreZHKA= X-Google-Smtp-Source: APXvYqyiprnnWU4rXtsHhhC4I5UqVMx78ccNfm1X35wazpAaZSJma1EHcKW1CFUxAhCYo5lEBNcLEA== X-Received: by 2002:a17:902:aa83:: with SMTP id d3mr8074837plr.108.1556347388411; Fri, 26 Apr 2019 23:43:08 -0700 (PDT) Received: from sc2-haas01-esx0118.eng.vmware.com ([66.170.99.1]) by smtp.gmail.com with ESMTPSA id j22sm36460145pfn.129.2019.04.26.23.43.07 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 26 Apr 2019 23:43:07 -0700 (PDT) From: nadav.amit@gmail.com To: Peter Zijlstra , Borislav Petkov , Andy Lutomirski , Ingo Molnar Cc: linux-kernel@vger.kernel.org, x86@kernel.org, hpa@zytor.com, Thomas Gleixner , Nadav Amit , Dave Hansen , linux_dti@icloud.com, linux-integrity@vger.kernel.org, linux-security-module@vger.kernel.org, akpm@linux-foundation.org, kernel-hardening@lists.openwall.com, linux-mm@kvack.org, will.deacon@arm.com, ard.biesheuvel@linaro.org, kristen@linux.intel.com, deneen.t.dock@intel.com, Rick Edgecombe , Nadav Amit Subject: [PATCH v6 04/24] x86/mm: Save debug registers when loading a temporary mm Date: Fri, 26 Apr 2019 16:22:43 -0700 Message-Id: <20190426232303.28381-5-nadav.amit@gmail.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20190426232303.28381-1-nadav.amit@gmail.com> References: <20190426232303.28381-1-nadav.amit@gmail.com> Sender: linux-integrity-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-integrity@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Nadav Amit Prevent user watchpoints from mistakenly firing while the temporary mm is being used. As the addresses of the temporary mm might overlap those of the user-process, this is necessary to prevent wrong signals or worse things from happening. Cc: Andy Lutomirski Acked-by: Peter Zijlstra (Intel) Signed-off-by: Nadav Amit Signed-off-by: Rick Edgecombe --- arch/x86/include/asm/mmu_context.h | 23 +++++++++++++++++++++++ 1 file changed, 23 insertions(+) diff --git a/arch/x86/include/asm/mmu_context.h b/arch/x86/include/asm/mmu_context.h index 24dc3b810970..93dff1963337 100644 --- a/arch/x86/include/asm/mmu_context.h +++ b/arch/x86/include/asm/mmu_context.h @@ -13,6 +13,7 @@ #include #include #include +#include extern atomic64_t last_mm_ctx_id; @@ -380,6 +381,21 @@ static inline temp_mm_state_t use_temporary_mm(struct mm_struct *mm) lockdep_assert_irqs_disabled(); temp_state.mm = this_cpu_read(cpu_tlbstate.loaded_mm); switch_mm_irqs_off(NULL, mm, current); + + /* + * If breakpoints are enabled, disable them while the temporary mm is + * used. Userspace might set up watchpoints on addresses that are used + * in the temporary mm, which would lead to wrong signals being sent or + * crashes. + * + * Note that breakpoints are not disabled selectively, which also causes + * kernel breakpoints (e.g., perf's) to be disabled. This might be + * undesirable, but still seems reasonable as the code that runs in the + * temporary mm should be short. + */ + if (hw_breakpoint_active()) + hw_breakpoint_disable(); + return temp_state; } @@ -387,6 +403,13 @@ static inline void unuse_temporary_mm(temp_mm_state_t prev_state) { lockdep_assert_irqs_disabled(); switch_mm_irqs_off(NULL, prev_state.mm, current); + + /* + * Restore the breakpoints if they were disabled before the temporary mm + * was loaded. + */ + if (hw_breakpoint_active()) + hw_breakpoint_restore(); } #endif /* _ASM_X86_MMU_CONTEXT_H */