From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 94BD92D0614; Fri, 17 Apr 2026 17:39:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776447545; cv=none; b=I+OJkF5oeuebd9DXcgcOAHP/lBR0lzE6pAsjXJxfrANkEH70jYfMQZ/laXYDMyuRPVYuoSp96zPaJzlXBaFZFNLjQJxCkplCMQa+Nr4VTUsGwSo3FNO0wBLayLawUoiCEfRwl6VNC2AqeLFURXdAhp13+EEqwhTVUc1swxEzxWw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776447545; c=relaxed/simple; bh=rtaHgFZXQZ78ik4SRZtEsybXv6W9bNkHH0T25TFSeL0=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=gMMzKRf2oij5illdGj7aXNVfHGwKtjFysYhnmhPBYQmectH2EKHq8tVQXumUnz8EpfQYGoSBDs2YVdqcJCByHWhx0Uf9AT91BYDZyDeUOd0e8h9Zr09NnfchM79tTLCplAjoiGt1VzHONbI0BXZZbdxaoGGxqX7mOV+LsizZGqk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=u2/EyyMb; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="u2/EyyMb" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E384FC19425; Fri, 17 Apr 2026 17:38:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1776447545; bh=rtaHgFZXQZ78ik4SRZtEsybXv6W9bNkHH0T25TFSeL0=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=u2/EyyMbkNoksqyFV6DhyMLgjgwjvgYI+oEXVsEeJHbk1ckE8Z09qoH0k6nFGQFm9 cY75hCwPK09VXs+Xm520/ICdasDxYK+68y0wlLNPceDO8WaB2iNuZu5lBnyugyK8mH FtC7u0OpIzmBSwpTZQYHkrrhJLkHKDaQ/uH3RpDJYHzA/vrhG/xwVSk7i4jOMnmtx+ kfIciHnRXI8LXvxbZUpxFSrLKOnTtcOJi+GpcJPKkJzPjyI29rI5qjq57rjoiI3FSj 56GoJa6eh3WUF9kwy5eyLXswYoVwGrq+EKOl7BDlJQuKsL7Catq5Czvt+C9MJ72ICR qXUGtyz6RjjMQ== Message-ID: Date: Fri, 17 Apr 2026 19:38:55 +0200 Precedence: bulk X-Mailing-List: linux-hardening@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v6 01/30] mm: Introduce kpkeys To: Kevin Brodsky , linux-hardening@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Andrew Morton , Andy Lutomirski , Catalin Marinas , Dave Hansen , Ira Weiny , Jann Horn , Jeff Xu , Joey Gouly , Kees Cook , Linus Walleij , Lorenzo Stoakes , Marc Zyngier , Mark Brown , Matthew Wilcox , Maxwell Bland , "Mike Rapoport (IBM)" , Peter Zijlstra , Pierre Langlois , Quentin Perret , Rick Edgecombe , Ryan Roberts , Thomas Gleixner , Vlastimil Babka , Will Deacon , Yang Shi , Yeoreum Yun , linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, x86@kernel.org References: <20260227175518.3728055-1-kevin.brodsky@arm.com> <20260227175518.3728055-2-kevin.brodsky@arm.com> <00b24db8-0063-48d6-8bc4-e8b670d8f0d5@kernel.org> <913002a5-e002-4001-ad19-037102d1f97d@arm.com> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 8bit On 4/17/26 17:59, Kevin Brodsky wrote: > On 17/04/2026 16:37, David Hildenbrand (Arm) wrote: >> On 2/27/26 18:54, Kevin Brodsky wrote: >>> kpkeys is a simple framework to enable the use of protection keys >>> (pkeys) to harden the kernel itself. This patch introduces the basic >>> API in : a couple of functions to set and restore >>> the pkey register and macros to define guard objects. >>> >>> kpkeys introduces a new concept on top of pkeys: the kpkeys level. >>> Each level is associated to a set of permissions for the pkeys >>> managed by the kpkeys framework. kpkeys_set_level(lvl) sets those >>> permissions according to lvl, and returns the original pkey >>> register, to be later restored by kpkeys_restore_pkey_reg(). To >>> start with, only KPKEYS_LVL_DEFAULT is available, which is meant >>> to grant RW access to KPKEYS_PKEY_DEFAULT (i.e. all memory since >>> this is the only available pkey for now). >>> >>> Because each architecture implementing pkeys uses a different >>> representation for the pkey register, and may reserve certain pkeys >>> for specific uses, support for kpkeys must be explicitly indicated >>> by selecting ARCH_HAS_KPKEYS and defining the following functions in >>> , in addition to the macros provided in >>> : >>> >>> - arch_kpkeys_set_level() >>> - arch_kpkeys_restore_pkey_reg() >>> - arch_kpkeys_enabled() >> Another thing: why not simply drop the "arch_" stuff from these helpers? > > The first two are not meant to be directly called, they're the > arch-specific implementation of kpkeys_set_level() and > kpkeys_restore_pkey_reg(), and those generic functions handle some > generic logic. > > arch_kpkeys_enabled() is directly used in generic code, so I suppose it > could be renamed to kpkeys_enabled()? It's actually implemented in an > arch header so I wasn't too sure about it. I was skimming over patch #13 and spotted: +void·__init·kpkeys_hardened_pgtables_init(void) +{ +› if·(!arch_kpkeys_enabled()) +› › return; + +› static_branch_enable(&kpkeys_hardened_pgtables_key); +} The arch_* there can just go IMHO. I'd also do it for the two ones used by the GUARD macros. If we don't expect common code wrappers (arch_kpkeys_enabled() vs. kpkeys_enabled), then the arch_ is unnecessary information -- IMHO -- Cheers, David