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=-13.5 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 5A79FC433F5 for ; Sun, 5 Sep 2021 15:32:35 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id BBF0460F56 for ; Sun, 5 Sep 2021 15:32:34 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org BBF0460F56 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=roeck-us.net Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvack.org Received: by kanga.kvack.org (Postfix) id BC8196B0071; Sun, 5 Sep 2021 11:32:33 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id B5088900002; Sun, 5 Sep 2021 11:32:33 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A18CE6B0073; Sun, 5 Sep 2021 11:32:33 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0212.hostedemail.com [216.40.44.212]) by kanga.kvack.org (Postfix) with ESMTP id 934FC6B0071 for ; Sun, 5 Sep 2021 11:32:33 -0400 (EDT) Received: from smtpin06.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 368AB2BA7E for ; Sun, 5 Sep 2021 15:32:33 +0000 (UTC) X-FDA: 78553911786.06.7C85C94 Received: from mail-ot1-f47.google.com (mail-ot1-f47.google.com [209.85.210.47]) by imf27.hostedemail.com (Postfix) with ESMTP id CADDD700009D for ; Sun, 5 Sep 2021 15:32:32 +0000 (UTC) Received: by mail-ot1-f47.google.com with SMTP id i3-20020a056830210300b0051af5666070so5489195otc.4 for ; Sun, 05 Sep 2021 08:32:32 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=XoAlzqJi3De8B+VzmGNnnTIvew9rejsmVUIc2D4Tpw0=; b=LurNh+xXN3Seno1v6vKCeczmHg5jkp75T7+rEOTZc9poUVG66GYg/QUXCpVw/gZFaz UrOiFKVGus5FSJFr25SxzrUPwkqmdBOL2RrQ9cqQnQV+zeT6US5zUeogQAglGZ9aQRpu g+f4EQwqe1RumBAG3axpcqPQtpkxvocGhMlE2O7dmqkW0U/qx0C36GKaVq1rhDbNs7Aq d0kmTanGwQiiXk849oEBv1wsz2C3u5LbNaV8lb9H9tcU+UWwtp/6tZUNqAZ+LW9AQmmY /cbJ4ru1mUxJ8CmChZjh79C9VmP5PfoaUWgv6dfo692Lw8w0YblbPX71SpcZgzh3TgZj pi8Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:from:to:cc:subject:message-id :references:mime-version:content-disposition:in-reply-to; bh=XoAlzqJi3De8B+VzmGNnnTIvew9rejsmVUIc2D4Tpw0=; b=d77yDQRhmOX0IDsnyo7MJXGbT+kIKlCbjAAcZg36VMIeCKtI4YuuhokYsbYZSd5MHV dZaTF06KeFo+NP6x+I6UQThh13BKnafbTJ4VG3eDCEOfCjcK74fthqwPlLRlASIl8Xj2 zdCUVtm+5Yq9QEFNtenRhjl1uVaP3548uXxTcTkYDspYD/nlR8m4x/5Es75jyV8Ii+k4 h744PbfwHb6ltzUFBZqsUZzQB6qg3D6J6MAEWFvc2yYUbRsxZGaR466DUj6eHF6KbTwz i9x50fw47FSDTRcq39kwBknNQDRAkmUpfhMvvE+ngT2ZbxvuZWCbCKTpUJN/8Ahwnkiq XSxQ== X-Gm-Message-State: AOAM530vp7Uw4ue4U1h54yjdAX2Far6aNB1+RB6LyDjZtmUsG2pqjxGk G7DOf4tHTrcWWFL/DQ/ihr0= X-Google-Smtp-Source: ABdhPJzbxr3wcNwbKxd3onpfBStc77h8RDWiIefjN+/Q69lK78BTudJW3loI0eDagfkU7WkIR01wsQ== X-Received: by 2002:a9d:6359:: with SMTP id y25mr7629665otk.274.1630855952160; Sun, 05 Sep 2021 08:32:32 -0700 (PDT) Received: from server.roeck-us.net ([2600:1700:e321:62f0:329c:23ff:fee3:9d7c]) by smtp.gmail.com with ESMTPSA id x12sm999383oie.56.2021.09.05.08.32.30 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 05 Sep 2021 08:32:31 -0700 (PDT) Date: Sun, 5 Sep 2021 08:32:29 -0700 From: Guenter Roeck To: David Hildenbrand Cc: linux-kernel@vger.kernel.org, Linus Torvalds , Andrew Morton , Thomas Gleixner , Ingo Molnar , Borislav Petkov , "H. Peter Anvin" , Alexander Viro , Alexey Dobriyan , Steven Rostedt , Peter Zijlstra , Arnaldo Carvalho de Melo , Mark Rutland , Alexander Shishkin , Jiri Olsa , Namhyung Kim , Petr Mladek , Sergey Senozhatsky , Andy Shevchenko , Rasmus Villemoes , Kees Cook , "Eric W. Biederman" , Greg Ungerer , Geert Uytterhoeven , Mike Rapoport , Vlastimil Babka , Vincenzo Frascino , Chinwen Chang , Catalin Marinas , "Matthew Wilcox (Oracle)" , Huang Ying , Jann Horn , Feng Tang , Kevin Brodsky , Michael Ellerman , Shawn Anastasio , Steven Price , Nicholas Piggin , Christian Brauner , Jens Axboe , Gabriel Krisman Bertazi , Peter Xu , Suren Baghdasaryan , Shakeel Butt , Marco Elver , Daniel Jordan , Nicolas Viennot , Thomas Cedeno , Michal Hocko , Miklos Szeredi , Chengguang Xu , Christian =?iso-8859-1?Q?K=F6nig?= , Florian Weimer , David Laight , linux-unionfs@vger.kernel.org, linux-api@vger.kernel.org, x86@kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH v2 1/7] binfmt: don't use MAP_DENYWRITE when loading shared libraries via uselib() Message-ID: <20210905153229.GA3019909@roeck-us.net> References: <20210816194840.42769-1-david@redhat.com> <20210816194840.42769-2-david@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210816194840.42769-2-david@redhat.com> X-Rspamd-Queue-Id: CADDD700009D Authentication-Results: imf27.hostedemail.com; dkim=pass header.d=gmail.com header.s=20210112 header.b=LurNh+xX; dmarc=none; spf=pass (imf27.hostedemail.com: domain of groeck7@gmail.com designates 209.85.210.47 as permitted sender) smtp.mailfrom=groeck7@gmail.com X-Rspamd-Server: rspam01 X-Stat-Signature: 3ceuw3tj8rata166frium53d8zp4yshw X-HE-Tag: 1630855952-665830 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Mon, Aug 16, 2021 at 09:48:34PM +0200, David Hildenbrand wrote: > uselib() is the legacy systemcall for loading shared libraries. > Nowadays, applications use dlopen() to load shared libraries, completely > implemented in user space via mmap(). > > For example, glibc uses MAP_COPY to mmap shared libraries. While this > maps to MAP_PRIVATE | MAP_DENYWRITE on Linux, Linux ignores any > MAP_DENYWRITE specification from user space in mmap. > > With this change, all remaining in-tree users of MAP_DENYWRITE use it > to map an executable. We will be able to open shared libraries loaded > via uselib() writable, just as we already can via dlopen() from user > space. > > This is one step into the direction of removing MAP_DENYWRITE from the > kernel. This can be considered a minor user space visible change. > > Acked-by: "Eric W. Biederman" > Signed-off-by: David Hildenbrand > --- > arch/x86/ia32/ia32_aout.c | 2 +- > fs/binfmt_aout.c | 2 +- > fs/binfmt_elf.c | 2 +- > 3 files changed, 3 insertions(+), 3 deletions(-) > > diff --git a/arch/x86/ia32/ia32_aout.c b/arch/x86/ia32/ia32_aout.c > index 5e5b9fc2747f..321d7b22ad2d 100644 > --- a/arch/x86/ia32/ia32_aout.c > +++ b/arch/x86/ia32/ia32_aout.c > @@ -293,7 +293,7 @@ static int load_aout_library(struct file *file) > /* Now use mmap to map the library into memory. */ > error = vm_mmap(file, start_addr, ex.a_text + ex.a_data, > PROT_READ | PROT_WRITE | PROT_EXEC, > - MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE | MAP_32BIT, > + MAP_FIXED | MAP_PRIVATE | MAP_32BIT, > N_TXTOFF(ex)); > retval = error; > if (error != start_addr) > diff --git a/fs/binfmt_aout.c b/fs/binfmt_aout.c > index 145917f734fe..d29de971d3f3 100644 > --- a/fs/binfmt_aout.c > +++ b/fs/binfmt_aout.c > @@ -309,7 +309,7 @@ static int load_aout_library(struct file *file) > /* Now use mmap to map the library into memory. */ > error = vm_mmap(file, start_addr, ex.a_text + ex.a_data, > PROT_READ | PROT_WRITE | PROT_EXEC, > - MAP_FIXED | MAP_PRIVATE | MAP_DENYWRITE, > + MAP_FIXED | MAP_PRIVATE; > N_TXTOFF(ex)); Guess someone didn't care compile testing their code. This is now in mainline. Guenter