From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 79065C43387 for ; Thu, 20 Dec 2018 18:49:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4DDAC218F0 for ; Thu, 20 Dec 2018 18:49:24 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="HD0cJR8k" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388449AbeLTStX (ORCPT ); Thu, 20 Dec 2018 13:49:23 -0500 Received: from bombadil.infradead.org ([198.137.202.133]:50934 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728324AbeLTStX (ORCPT ); Thu, 20 Dec 2018 13:49:23 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=KKdRf1lwJWtkW/36xyZrlsowCIaciesNrJNkfZ3tciE=; b=HD0cJR8k0HJ+fvRGqpxIpCuBV Fv36z4Vt8ShO8NFzBBtayIPjB9/TjWatGfFJaRKb9lICX04efXa4BN21EloFDDLCNGdIgqNudc6SX RjMVsTOFDBzhTyN7V89mX0EkODnl8JolibRJCLyLbzhQXq6sDbWX1dPZFFPV5qavQkcjzzpKeWB1V 0chzDgEU37j22rDA4kwbbtHMlAO/vj0AY241MDyJMYdsyzhQVzma95xzZwc01OM2NKj0AKWT7iTIR aSMPEYBCDGp1T1EV7jydjusAQi9aN/2Zb7nR5JlEuzl7mGPVop7fspeE5SFbOqFAtUtlzcH+5Mwk6 fJerPEiVw==; Received: from willy by bombadil.infradead.org with local (Exim 4.90_1 #2 (Red Hat Linux)) id 1ga3Nm-0003yK-6A; Thu, 20 Dec 2018 18:49:18 +0000 Date: Thu, 20 Dec 2018 10:49:18 -0800 From: Matthew Wilcox To: Igor Stoppa Cc: Andy Lutomirski , Peter Zijlstra , Dave Hansen , Mimi Zohar , igor.stoppa@huawei.com, Nadav Amit , Kees Cook , linux-integrity@vger.kernel.org, kernel-hardening@lists.openwall.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 04/12] __wr_after_init: x86_64: __wr_op Message-ID: <20181220184917.GY10600@bombadil.infradead.org> References: <20181219213338.26619-1-igor.stoppa@huawei.com> <20181219213338.26619-5-igor.stoppa@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181219213338.26619-5-igor.stoppa@huawei.com> User-Agent: Mutt/1.9.2 (2017-12-15) Sender: linux-integrity-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-integrity@vger.kernel.org On Wed, Dec 19, 2018 at 11:33:30PM +0200, Igor Stoppa wrote: > +void *__wr_op(unsigned long dst, unsigned long src, __kernel_size_t len, > + enum wr_op_type op) > +{ > + temporary_mm_state_t prev; > + unsigned long offset; > + unsigned long wr_poking_addr; > + > + /* Confirm that the writable mapping exists. */ > + if (WARN_ONCE(!wr_ready, "No writable mapping available")) > + return (void *)dst; > + > + if (WARN_ONCE(op >= WR_OPS_NUMBER, "Invalid WR operation.") || > + WARN_ONCE(!is_wr_after_init(dst, len), "Invalid WR range.")) > + return (void *)dst; > + > + offset = dst - (unsigned long)&__start_wr_after_init; > + wr_poking_addr = wr_poking_base + offset; > + local_irq_disable(); > + prev = use_temporary_mm(wr_poking_mm); > + > + if (op == WR_MEMCPY) > + copy_to_user((void __user *)wr_poking_addr, (void *)src, len); > + else if (op == WR_MEMSET) > + memset_user((void __user *)wr_poking_addr, (u8)src, len); > + > + unuse_temporary_mm(prev); > + local_irq_enable(); > + return (void *)dst; > +} I think you're causing yourself more headaches by implementing this "op" function. Here's some generic code: void *wr_memcpy(void *dst, void *src, unsigned int len) { wr_state_t wr_state; void *wr_poking_addr = __wr_addr(dst); local_irq_disable(); wr_enable(&wr_state); __wr_memcpy(wr_poking_addr, src, len); wr_disable(&wr_state); local_irq_enable(); return dst; } Now, x86 can define appropriate macros and functions to use the temporary_mm functionality, and other architectures can do what makes sense to them.