From patchwork Wed Jan 22 17:19:23 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mel Gorman X-Patchwork-Id: 13947554 Received: from mail13.out.titan.email (mail13.out.titan.email [18.198.78.245]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D40DF21505F; Wed, 22 Jan 2025 17:20:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=18.198.78.245 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1737566408; cv=none; b=e66ls4YZ1fttG6UR/6iCZ0wX9OVaSB4Fe0E22ywogTGZ2A9WwN5KgUNEmRRKmh4ylj42ncHfRodTyYaeHkqCotBDlRAoSD8gVXZtAu9WHNj/xPseWledzUXORyV3N5lPiJ6A7M5LuhvuyczNjMcmH9Rqu7sXMvhjAPISBK21/gs= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1737566408; c=relaxed/simple; bh=SuG5hvAQgjxhXm9LGjN9dYWNlAAqBwyJpF59KcRtkR4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=PLHhrSYdzweam+Kgqe4Ix0NhfIC4ykOfbTPU9aKHICkIE6eicDhvhTLu7IrW88e28uIdqtWMK6RA0jEuT2LKG9m5FRG/JaEoheVP+ddZn8vENT+V+suxolAaHxfGlDVwo7fMThB4gLgUkSvg5Rlp8JHjGfU9cWw6pjfBKKKoNLc= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=techsingularity.net; spf=pass smtp.mailfrom=techsingularity.net; dkim=pass (1024-bit key) header.d=techsingularity.net header.i=@techsingularity.net header.b=Bpnsrt+X; arc=none smtp.client-ip=18.198.78.245 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=techsingularity.net Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=techsingularity.net Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=techsingularity.net header.i=@techsingularity.net header.b="Bpnsrt+X" Received: from smtp-out0101.titan.email (localhost [127.0.0.1]) by smtp-out0101.titan.email (Postfix) with ESMTP id A0C49A015A; Wed, 22 Jan 2025 17:19:58 +0000 (UTC) DKIM-Signature: a=rsa-sha256; bh=Z2jYOWM8hUV6J3bzYS5e2M9sLIUUWbq7B6uKhS/GsCs=; c=relaxed/relaxed; d=techsingularity.net; h=mime-version:from:to:cc:message-id:in-reply-to:subject:date:references:from:to:cc:subject:date:message-id:in-reply-to:references:reply-to; q=dns/txt; s=titan1; t=1737566398; v=1; b=Bpnsrt+XYCpXjb4LOgVfgwsOpx/9Q7ZydDgH4UuJRheEiW3AHJAIB4mclRxQbwCFWzYu9/E9 LDApje3CjvtfkI2u0OXsR03GQyfT1EVJNCYQ1GFK0DiRF2s/Hz3JEDWgvcr5C6+2ZVFSxfFc4VE NgWkQ5xP5Bw789VU4DxEV+40= Received: from mail.blacknight.com (ip-84-203-196-66.broadband.digiweb.ie [84.203.196.66]) by smtp-out0101.titan.email (Postfix) with ESMTPA id 33020A0008; Wed, 22 Jan 2025 17:19:58 +0000 (UTC) Feedback-ID: :mgorman@techsingularity.net:techsingularity.net:flockmailId From: Mel Gorman To: Kees Cook Cc: Daniel Micay , Paul Moore , linux-hardening@vger.kernel.org, linux-kernel@vger.kernel.org, Mel Gorman Subject: [PATCH 2/4] mm: security: Allow default HARDENED_USERCOPY to be set at compile time Date: Wed, 22 Jan 2025 17:19:23 +0000 Message-ID: <20250122171925.25472-3-mgorman@techsingularity.net> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20250122171925.25472-1-mgorman@techsingularity.net> References: <20250122171925.25472-1-mgorman@techsingularity.net> Precedence: bulk X-Mailing-List: linux-hardening@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-F-Verdict: SPFVALID X-Titan-Src-Out: 1737566398543734204.9138.2594461423631213783@prod-euc1-smtp-out1002. X-CMAE-Score: 0 X-CMAE-Analysis: v=2.4 cv=UdNXSrSN c=1 sm=1 tr=0 ts=679128be a=jU4EnjUUC1PH4wSjvv7Pww==:117 a=jU4EnjUUC1PH4wSjvv7Pww==:17 a=CEWIc4RMnpUA:10 a=R_Myd5XaAAAA:8 a=0z80O7jHjOjBg2F2ajAA:9 a=L2g4Dz8VuBQ37YGmWQah:22 X-Virus-Scanned: ClamAV using ClamSMTP HARDENED_USERCOPY defaults to on if enabled at compile time. Allow hardened_usercopy= default to be set at compile time similar to init_on_alloc= and init_on_free=. The intent is that hardening options that can be disabled at runtime can set their default at build time. Signed-off-by: Mel Gorman --- Documentation/admin-guide/kernel-parameters.txt | 4 +++- mm/usercopy.c | 3 ++- security/Kconfig.hardening | 8 ++++++++ 3 files changed, 13 insertions(+), 2 deletions(-) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 3872bc6ec49d..5d759b20540a 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -1773,7 +1773,9 @@ allocation boundaries as a proactive defense against bounds-checking flaws in the kernel's copy_to_user()/copy_from_user() interface. - on Perform hardened usercopy checks (default). + The default is determined by + CONFIG_HARDENED_USERCOPY_DEFAULT_ON. + on Perform hardened usercopy checks. off Disable hardened usercopy checks. hardlockup_all_cpu_backtrace= diff --git a/mm/usercopy.c b/mm/usercopy.c index 83c164aba6e0..4cf33305347a 100644 --- a/mm/usercopy.c +++ b/mm/usercopy.c @@ -255,7 +255,8 @@ void __check_object_size(const void *ptr, unsigned long n, bool to_user) } EXPORT_SYMBOL(__check_object_size); -static bool enable_checks __initdata = true; +static bool enable_checks __initdata = + IS_ENABLED(CONFIG_HARDENED_USERCOPY_DEFAULT_ON); static int __init parse_hardened_usercopy(char *str) { diff --git a/security/Kconfig.hardening b/security/Kconfig.hardening index 9088d613d519..adcc260839c7 100644 --- a/security/Kconfig.hardening +++ b/security/Kconfig.hardening @@ -293,6 +293,14 @@ config HARDENED_USERCOPY or are part of the kernel text. This prevents entire classes of heap overflow exploits and similar kernel memory exposures. +config HARDENED_USERCOPY_DEFAULT_ON + bool "Harden memory copies by default" + depends on HARDENED_USERCOPY + default n + help + This has the effect of setting "hardened_usercopy=on" on the kernel + command line. This can be disabled with "hardened_usercopy=off". + endmenu menu "Hardening of kernel data structures"