From patchwork Tue Mar 10 01:03:34 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Russell Currey X-Patchwork-Id: 11428257 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 284E614B7 for ; Tue, 10 Mar 2020 01:04:44 +0000 (UTC) Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.kernel.org (Postfix) with SMTP id 8342D20637 for ; Tue, 10 Mar 2020 01:04:43 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=russell.cc header.i=@russell.cc header.b="nuHFjJ3b"; dkim=pass (2048-bit key) header.d=messagingengine.com header.i=@messagingengine.com header.b="igN1LVoO" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8342D20637 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-18116-patchwork-kernel-hardening=patchwork.kernel.org@lists.openwall.com Received: (qmail 26035 invoked by uid 550); 10 Mar 2020 01:04:24 -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 25946 invoked from network); 10 Mar 2020 01:04:24 -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=8lzF+bki5ljY1 +3LRVnTxy2EovRyYNho4bqwRNKSXkI=; b=nuHFjJ3bYut+r7z12RZ+iPn9kAOFm BqZ7jkWFLpiJwEJg8b32a/owfy59xHaNRZ925cgDdAsId4j2Lr9PG22Ve0TFzPjF iyMn3mO9jX4uYRM8Y/ZZhM2y5E0k+uAczRX77d0nnOgo776kL8TUkwwyNrObmTKJ lFUssyFdRSYwq1lRx3dEGHaa4VL4forHy+8/zPKi0SdCv9rpKbIVmnGiTQCdMdJH BijBbpWdNhRvKMc6/2RUzSuSbTnwdlD6TdwfbadahinKRm861ygaZp9isWD77zdH D/qQOK6L8xmvC2xcAmV5q4MzLnXaDescHpHWc1b0nfOxqm0Gdg2yAvGgw== 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=8lzF+bki5ljY1+3LRVnTxy2EovRyYNho4bqwRNKSXkI=; b=igN1LVoO NEY7Rpz1yZkAlgZMCRCjlBSQ59rxJCm6adTX17R6kZWnUBXWHd1NpL6La6HoVIQ7 7oI58mSWfexvcK393VtWdjLzuRRizj1p8/AYeAaEOIUjON7bP+wT4cZJk+xwzLeB 8caEN98n+X62itKsVt+/Uupmt+fzSHDyVRJCkkwAcm/Bo3wyjlvyxJMlKNF/EK/Q Q8SZHlGMtdvlMuH24MXWrwEKnh8sgUdlyUN7I8JyyEnopBhyCqSBsexHZuT0Shf8 GHVuzmgsrYYqeq/dy9R1adtydAXMhiVixxqP3jaidCsI9MKNSv+ixjvs3+r20ot5 y9KjwTOX2ENSKA== X-ME-Sender: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgedugedrudduledgvdelucetufdoteggodetrfdotf fvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdfqfgfvpdfurfetoffkrfgpnffqhgen uceurghilhhouhhtmecufedttdenucesvcftvggtihhpihgvnhhtshculddquddttddmne gfrhhlucfvnfffucdludehmdenucfjughrpefhvffufffkofgjfhgggfestdekredtredt tdenucfhrhhomheptfhushhsvghllhcuvehurhhrvgihuceorhhushgtuhhrsehruhhssh gvlhhlrdgttgeqnecukfhppeduvddvrdelledrkedvrddutdenucevlhhushhtvghrufhi iigvpedunecurfgrrhgrmhepmhgrihhlfhhrohhmpehruhhstghurhesrhhushhsvghllh drtggt X-ME-Proxy: From: Russell Currey To: linuxppc-dev@lists.ozlabs.org Cc: Russell Currey , christophe.leroy@c-s.fr, joel@jms.id.au, mpe@ellerman.id.au, ajd@linux.ibm.com, dja@axtens.net, npiggin@gmail.com, kernel-hardening@lists.openwall.com, Kees Cook Subject: [PATCH v6 3/7] powerpc/mm/ptdump: debugfs handler for W+X checks at runtime Date: Tue, 10 Mar 2020 12:03:34 +1100 Message-Id: <20200310010338.21205-4-ruscur@russell.cc> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200310010338.21205-1-ruscur@russell.cc> References: <20200310010338.21205-1-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)