From patchwork Tue Mar 31 04:48:21 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Russell Currey X-Patchwork-Id: 11466715 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 279DF912 for ; Tue, 31 Mar 2020 04:49:25 +0000 (UTC) Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.kernel.org (Postfix) with SMTP id 826B6206EB for ; Tue, 31 Mar 2020 04:49:24 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=russell.cc header.i=@russell.cc header.b="RNYWsI3p"; dkim=pass (2048-bit key) header.d=messagingengine.com header.i=@messagingengine.com header.b="nJUvIi5/" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 826B6206EB Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=russell.cc Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kernel-hardening-return-18317-patchwork-kernel-hardening=patchwork.kernel.org@lists.openwall.com Received: (qmail 18105 invoked by uid 550); 31 Mar 2020 04:49:03 -0000 Mailing-List: contact kernel-hardening-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Delivered-To: mailing list kernel-hardening@lists.openwall.com Received: (qmail 18006 invoked from network); 31 Mar 2020 04:49:03 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=russell.cc; h= from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; s=fm1; bh=7lxSiSzlC+CRa BOucvvMEahHc5ocTEmTHhLzUywxUHs=; b=RNYWsI3poX7iSqx2QX4AkSlMzpR/l 2QsHyDn9fXKk8uIAak4ktw4HLoiN/QComTMxM/Nrb3Zzy9k5gy4D9cenM+LnWAKl wZf+CkdPqAfoql+MgSfMNB1dGSW2eRPJCTQNG+WwTmRbzIuIvs4ggHtrU63SgFz7 rEdzxJhdggA7K/T1MJAfNjCWtiTdQ0b6HEDXYWm78+pCG8kzO3OoUTNcQA9Gd/vG +o2a2xydvtRMxz7KEQkVNDwZQPjwiUmQp5+I1RpWTSOfGJx3wK8N2fwkARgvqlU+ Bvb9trV+TkrL+NfDioHQwX4z78Da15EOLyFmZkE3++GFZ3BeSmkpx2WfQ== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:content-transfer-encoding:date:from :in-reply-to:message-id:mime-version:references:subject:to :x-me-proxy:x-me-proxy:x-me-sender:x-me-sender:x-sasl-enc; s= fm2; bh=7lxSiSzlC+CRaBOucvvMEahHc5ocTEmTHhLzUywxUHs=; b=nJUvIi5/ MUz3fp9JkeoyprNQLeiRzQmBiTjLnUEnmEY4/svivO6/WIXL/beGNRb0Y2IXDeTb IExUs6p+RMuwTFJ19Pmr+97XkTQd3BgBZZdk9XR8r7b8lYNueeILaHCosgLgFebu LxTMiDC4xL/kErnVyNDBAy/My1qZU2VgZ2CKJHZtf+fxJ1x++vOdPX0TcdZ83wRU xuK1RpjnBsLEt1KX+92eDUY9uKexliiYOEPBkbgVtMBU3yQY9ZFcrWrkAMVxdelF NcnszopBpgAx1XegiLgT3v7lxrGsj7r26MGCBr0ZLBCcp2OTX9wkH6wfc2y7kT+H sm4+x/WZnimwgw== X-ME-Sender: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgedugedrudeiiedgkeeiucetufdoteggodetrfdotf fvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdfqfgfvpdfurfetoffkrfgpnffqhgen uceurghilhhouhhtmecufedttdenucesvcftvggtihhpihgvnhhtshculddquddttddmne gfrhhlucfvnfffucdludehmdenucfjughrpefhvffufffkofgjfhgggfestdekredtredt tdenucfhrhhomheptfhushhsvghllhcuvehurhhrvgihuceorhhushgtuhhrsehruhhssh gvlhhlrdgttgeqnecukfhppeduvddurdeghedrvdduvddrvdefleenucevlhhushhtvghr ufhiiigvpedvnecurfgrrhgrmhepmhgrihhlfhhrohhmpehruhhstghurhesrhhushhsvg hllhdrtggt X-ME-Proxy: From: Russell Currey To: linuxppc-dev@lists.ozlabs.org Cc: Russell Currey , christophe.leroy@c-s.fr, mpe@ellerman.id.au, ajd@linux.ibm.com, dja@axtens.net, npiggin@gmail.com, kernel-hardening@lists.openwall.com, Kees Cook Subject: [PATCH v7 3/7] powerpc/mm/ptdump: debugfs handler for W+X checks at runtime Date: Tue, 31 Mar 2020 15:48:21 +1100 Message-Id: <20200331044825.591653-4-ruscur@russell.cc> X-Mailer: git-send-email 2.26.0 In-Reply-To: <20200331044825.591653-1-ruscur@russell.cc> References: <20200331044825.591653-1-ruscur@russell.cc> MIME-Version: 1.0 Very rudimentary, just echo 1 > [debugfs]/check_wx_pages and check the kernel log. Useful for testing strict module RWX. Updated the Kconfig entry to reflect this. Also fixed a typo. Reviewed-by: Kees Cook Signed-off-by: Russell Currey --- arch/powerpc/Kconfig.debug | 6 ++++-- arch/powerpc/mm/ptdump/ptdump.c | 21 ++++++++++++++++++++- 2 files changed, 24 insertions(+), 3 deletions(-) diff --git a/arch/powerpc/Kconfig.debug b/arch/powerpc/Kconfig.debug index 0b063830eea8..e37960ef68c6 100644 --- a/arch/powerpc/Kconfig.debug +++ b/arch/powerpc/Kconfig.debug @@ -370,7 +370,7 @@ config PPC_PTDUMP If you are unsure, say N. config PPC_DEBUG_WX - bool "Warn on W+X mappings at boot" + bool "Warn on W+X mappings at boot & enable manual checks at runtime" depends on PPC_PTDUMP && STRICT_KERNEL_RWX help Generate a warning if any W+X mappings are found at boot. @@ -384,7 +384,9 @@ config PPC_DEBUG_WX of other unfixed kernel bugs easier. There is no runtime or memory usage effect of this option - once the kernel has booted up - it's a one time check. + once the kernel has booted up, it only automatically checks once. + + Enables the "check_wx_pages" debugfs entry for checking at runtime. If in doubt, say "Y". diff --git a/arch/powerpc/mm/ptdump/ptdump.c b/arch/powerpc/mm/ptdump/ptdump.c index 206156255247..a15e19a3b14e 100644 --- a/arch/powerpc/mm/ptdump/ptdump.c +++ b/arch/powerpc/mm/ptdump/ptdump.c @@ -4,7 +4,7 @@ * * This traverses the kernel pagetables and dumps the * information about the used sections of memory to - * /sys/kernel/debug/kernel_pagetables. + * /sys/kernel/debug/kernel_page_tables. * * Derived from the arm64 implementation: * Copyright (c) 2014, The Linux Foundation, Laura Abbott. @@ -413,6 +413,25 @@ void ptdump_check_wx(void) else pr_info("Checked W+X mappings: passed, no W+X pages found\n"); } + +static int check_wx_debugfs_set(void *data, u64 val) +{ + if (val != 1ULL) + return -EINVAL; + + ptdump_check_wx(); + + return 0; +} + +DEFINE_SIMPLE_ATTRIBUTE(check_wx_fops, NULL, check_wx_debugfs_set, "%llu\n"); + +static int ptdump_check_wx_init(void) +{ + return debugfs_create_file("check_wx_pages", 0200, NULL, + NULL, &check_wx_fops) ? 0 : -ENOMEM; +} +device_initcall(ptdump_check_wx_init); #endif static int ptdump_init(void)