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[209.132.180.67]) by mx.google.com with ESMTP id c15si1054886pfr.73.2019.06.20.18.23.26; Thu, 20 Jun 2019 18:23:46 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; dkim=pass header.i=@google.com header.s=20161025 header.b=Pg7CAs8Y; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726827AbfFUBUv (ORCPT + 99 others); Thu, 20 Jun 2019 21:20:51 -0400 Received: from mail-pg1-f201.google.com ([209.85.215.201]:51257 "EHLO mail-pg1-f201.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726761AbfFUBUl (ORCPT ); Thu, 20 Jun 2019 21:20:41 -0400 Received: by mail-pg1-f201.google.com with SMTP id i35so1795118pgi.18 for ; Thu, 20 Jun 2019 18:20:41 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=C2HEat8ChWdY0hmQrNdX6y9AIaltC2qHKe9IgXVBgg0=; b=Pg7CAs8Y51TZZLF1Lrf1EzgZZxAIfmpAgkg435aK19YQWb2C1HEcQS/IA5NONe5F1y Ob+ZzvlKygwjW5U9HoeoPUvj+ZQTVz4KTWE9brl/hTU7bpg2WRFHbtsL3RFZHXcCCD44 Umo5dJEwJPaaGUejehg1qSwqxZx6iu83RfpN/QMRxgiIpStb3VimfRc3/SsvvajRR8lK dWBlC/n58vr22GR9zDV7ockIGy/PDlXgyh+QAD4lrJlM6xPfisbmyM/PzywgA6/w2EGW mQCqo4qAZHk6V9TOc/zjjk76CPbO5M0+OPZ046QVHhSKHw8iNbWNlA3MGsO8M+7TgyDU Xmog== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=C2HEat8ChWdY0hmQrNdX6y9AIaltC2qHKe9IgXVBgg0=; b=OwIAt9liho/lw7uf9l8Zogo8m5p50/Jlc1FemiDSAX3TNCVqiZbkwJ/RsCwACD2yx3 rrD9sHJCuLQzvCk1rwEET1eyJLWPy6o4zOU0Zk/OBbhR+t5ZyiDNXgQAoh8C0jGjP53J 7VZSQrXgs7BuyRjfVtPPzzJOCMNdiMKWgHgjklJG9s/Iv8vYa/Ux/tkMIVhM6yoLhcBp zhHetmrU12d3EvSzM038AczBgcT94UGwIb8oIXfh4HiYIp4x9NZUGCnBl2+ExAiYUIsG MwAtUZrg+g7W5OcvJiGgrs8D6yzCQZZ1J60Rl5rfPLXXQgLpfrs/AIGDKwXyg49iqWYm NbbQ== X-Gm-Message-State: APjAAAXY1t36ZH0J8duzRLNAFwoh95OGuij+RQSu+OTfLclPkWjBQZ2g pSXFhykmOq6F6yoxgVrTEu8eIe7PJS8gYvuAplMiNQ== X-Received: by 2002:a63:5a02:: with SMTP id o2mr14951958pgb.93.1561080040579; Thu, 20 Jun 2019 18:20:40 -0700 (PDT) Date: Thu, 20 Jun 2019 18:19:32 -0700 In-Reply-To: <20190621011941.186255-1-matthewgarrett@google.com> Message-Id: <20190621011941.186255-22-matthewgarrett@google.com> Mime-Version: 1.0 References: <20190621011941.186255-1-matthewgarrett@google.com> X-Mailer: git-send-email 2.22.0.410.gd8fdbe21b5-goog Subject: [PATCH V33 21/30] x86/mmiotrace: Lock down the testmmiotrace module From: Matthew Garrett To: jmorris@namei.org Cc: linux-security@vger.kernel.org, linux-kernel@vger.kernel.org, linux-api@vger.kernel.org, David Howells , Thomas Gleixner , Matthew Garrett , Steven Rostedt , Ingo Molnar , "H. Peter Anvin" , x86@kernel.org Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: David Howells The testmmiotrace module shouldn't be permitted when the kernel is locked down as it can be used to arbitrarily read and write MMIO space. This is a runtime check rather than buildtime in order to allow configurations where the same kernel may be run in both locked down or permissive modes depending on local policy. Suggested-by: Thomas Gleixner Signed-off-by: David Howells cc: Thomas Gleixner cc: Steven Rostedt cc: Ingo Molnar cc: "H. Peter Anvin" cc: x86@kernel.org --- arch/x86/mm/testmmiotrace.c | 3 +++ include/linux/security.h | 1 + security/lockdown/lockdown.c | 1 + 3 files changed, 5 insertions(+) diff --git a/arch/x86/mm/testmmiotrace.c b/arch/x86/mm/testmmiotrace.c index f6ae6830b341..a6b204f9f505 100644 --- a/arch/x86/mm/testmmiotrace.c +++ b/arch/x86/mm/testmmiotrace.c @@ -115,6 +115,9 @@ static int __init init(void) { unsigned long size = (read_far) ? (8 << 20) : (16 << 10); + if (security_is_locked_down(LOCKDOWN_MMIOTRACE)) + return -EPERM; + if (mmio_address == 0) { pr_err("you have to use the module argument mmio_address.\n"); pr_err("DO NOT LOAD THIS MODULE UNLESS YOU REALLY KNOW WHAT YOU ARE DOING!\n"); diff --git a/include/linux/security.h b/include/linux/security.h index 47ca04ac00f6..89b7adfae525 100644 --- a/include/linux/security.h +++ b/include/linux/security.h @@ -93,6 +93,7 @@ enum lockdown_reason { LOCKDOWN_PCMCIA_CIS, LOCKDOWN_TIOCSSERIAL, LOCKDOWN_MODULE_PARAMETERS, + LOCKDOWN_MMIOTRACE, LOCKDOWN_INTEGRITY_MAX, LOCKDOWN_CONFIDENTIALITY_MAX, }; diff --git a/security/lockdown/lockdown.c b/security/lockdown/lockdown.c index 0788d4805449..215615e67237 100644 --- a/security/lockdown/lockdown.c +++ b/security/lockdown/lockdown.c @@ -29,6 +29,7 @@ static char *lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1] = { [LOCKDOWN_PCMCIA_CIS] = "direct PCMCIA CIS storage", [LOCKDOWN_TIOCSSERIAL] = "reconfiguration of serial port IO", [LOCKDOWN_MODULE_PARAMETERS] = "unsafe module parameters", + [LOCKDOWN_MMIOTRACE] = "unsafe mmio", [LOCKDOWN_INTEGRITY_MAX] = "integrity", [LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality", }; -- 2.22.0.410.gd8fdbe21b5-goog