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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 89F99C433FE for ; Mon, 28 Feb 2022 20:47:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229866AbiB1UsI (ORCPT ); Mon, 28 Feb 2022 15:48:08 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55774 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229756AbiB1UsI (ORCPT ); Mon, 28 Feb 2022 15:48:08 -0500 X-Greylist: delayed 949 seconds by postgrey-1.37 at lindbergh.monkeyblade.net; Mon, 28 Feb 2022 12:47:28 PST Received: from matoro.tk (unknown [IPv6:2600:1700:4b10:9d80::2]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7480F5F7B; Mon, 28 Feb 2022 12:47:28 -0800 (PST) DKIM-Signature: a=rsa-sha256; bh=3Z50+tLC8/CEOc9W5FMuZ/YfLz0LpCHJGNIb1bHqn70=; c=relaxed/relaxed; d=matoro.tk; h=Subject:Subject:Sender:To:To:Cc:Cc:From:From:Date:Date:MIME-Version:MIME-Version:Content-Type:Content-Type:Content-Transfer-Encoding:Content-Transfer-Encoding:Reply-To:In-Reply-To:In-Reply-To:Message-Id:Message-Id:References:References:Autocrypt:Openpgp; i=@matoro.tk; s=20220111215046; t=1646080260; v=1; x=1646512260; b=crJzFMOR6tc9squcx92hLTuFtuCfhgO+BgNnioUeH7k69a4pSO7joK45Wfxj0yH7NEIwX6uZ ovLhBNmzxYd5GCzchaGc5QbNkiNzNti5/PIEBt0QyXPX2BToy9B41BFvKbxTGv5xjhVv6kKb/oN OVkZTwV0VQF/Nh/w2UdBttHf7cNJH02zmF8O3u9kFIu3JIdWVoXI6KSpQYEr2yd92EMtlkBySjK VOka02DgQS/aFvpvPOaq3GW48LdBEpQclkOgPyVi61JJq9bq0ylXW5ZtUxY/5ix8dkvcSA0wnHK hZIf4rgSu0P5LiEbYccNCW91mbHc6sUp8HfDA43bsiNAQ9+GWbtWDncUnxcuu2PkY3etBd2b/9G zdLjv5VqebunO676QNsGrJRRkEHk7kWB9gid1XivUpxHo3AY+X+T79AbzN/MnHDtxFJuvGoQILr LZE/kxHolAH+o3gf/wpTQC5IMskejWDD2C2ITZi4ryHpV/NAEiuQRV1F03SdJI9r5ngOfcA4QqP BXYRWYXIYIWbrFE3aw7SFY2xkXoyStoakRiewxY3x02/MgRjFkWvAgznd0fbt0DqESFJ7M35xec OEU6V3m+Q53l8JgSfk6YfDSdMAftMhfkYyPj9J1iZNlN4YHvvi7OXXQBftKtjSF8jHYEKGmPGIb 3Al+HFYYAy8= Received: by matoro.tk (envelope-sender ) with ESMTPS id 51b43b45; Mon, 28 Feb 2022 15:31:00 -0500 MIME-Version: 1.0 Date: Mon, 28 Feb 2022 15:31:00 -0500 From: matoro To: Kees Cook Cc: Alexander Viro , Eric Biederman , linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, John Paul Adrian Glaubitz , stable@vger.kernel.org, Thorsten Leemhuis , Anthony Yznaga , Andrew Morton , regressions@lists.linux.dev, linux-ia64@vger.kernel.org, linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org Subject: Re: [PATCH] binfmt_elf: Avoid total_mapping_size for ET_EXEC In-Reply-To: <20220228194613.1149432-1-keescook@chromium.org> References: <20220228194613.1149432-1-keescook@chromium.org> Message-ID: <5d44f028b2d739395c92e4b3036e2bbf@matoro.tk> X-Sender: matoro_mailinglist_kernel@matoro.tk Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-hardening@vger.kernel.org On 2022-02-28 14:46, Kees Cook wrote: > Partially revert commit 5f501d555653 ("binfmt_elf: reintroduce using > MAP_FIXED_NOREPLACE"). > > At least ia64 has ET_EXEC PT_LOAD segments that are not virtual-address > contiguous (but _are_ file-offset contiguous). This would result in > giant mapping attempts to cover the entire span, including the virtual > address range hole. Disable total_mapping_size for ET_EXEC, which > reduces the MAP_FIXED_NOREPLACE coverage to only the first PT_LOAD: > > $ readelf -lW /usr/bin/gcc > ... > Program Headers: > Type Offset VirtAddr PhysAddr FileSiz MemSiz > ... > ... > LOAD 0x000000 0x4000000000000000 0x4000000000000000 0x00b5a0 0x00b5a0 > ... > LOAD 0x00b5a0 0x600000000000b5a0 0x600000000000b5a0 0x0005ac 0x000710 > ... > ... > ^^^^^^^^ ^^^^^^^^^^^^^^^^^^ ^^^^^^^^ ^^^^^^^^ > > File offset range : 0x000000-0x00bb4c > 0x00bb4c bytes > > Virtual address range : 0x4000000000000000-0x600000000000bcb0 > 0x200000000000bcb0 bytes > > Ironically, this is the reverse of the problem that originally caused > problems with ET_EXEC and MAP_FIXED_NOREPLACE: overlaps. This problem > is > with holes. Future work could restore full coverage if > load_elf_binary() > were to perform mappings in a separate phase from the loading (where > it could resolve both overlaps and holes). > > Cc: Alexander Viro > Cc: Eric Biederman > Cc: linux-fsdevel@vger.kernel.org > Cc: linux-mm@kvack.org > Reported-by: matoro > Reported-by: John Paul Adrian Glaubitz > Fixes: 5f501d555653 ("binfmt_elf: reintroduce using > MAP_FIXED_NOREPLACE") > Link: > https://lore.kernel.org/r/a3edd529-c42d-3b09-135c-7e98a15b150f@leemhuis.info > Cc: stable@vger.kernel.org > Signed-off-by: Kees Cook > --- > matoro (or anyone else) can you please test this? > --- > fs/binfmt_elf.c | 25 ++++++++++++++++++------- > 1 file changed, 18 insertions(+), 7 deletions(-) > > diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c > index 9bea703ed1c2..474b44032c65 100644 > --- a/fs/binfmt_elf.c > +++ b/fs/binfmt_elf.c > @@ -1136,14 +1136,25 @@ static int load_elf_binary(struct linux_binprm > *bprm) > * is then page aligned. > */ > load_bias = ELF_PAGESTART(load_bias - vaddr); > - } > > - /* > - * Calculate the entire size of the ELF mapping (total_size). > - * (Note that first_pt_load is set to false later once the > - * initial mapping is performed.) > - */ > - if (first_pt_load) { > + /* > + * Calculate the entire size of the ELF mapping > + * (total_size), used for the initial mapping, > + * due to first_pt_load which is set to false later > + * once the initial mapping is performed. > + * > + * Note that this is only sensible when the LOAD > + * segments are contiguous (or overlapping). If > + * used for LOADs that are far apart, this would > + * cause the holes between LOADs to be mapped, > + * running the risk of having the mapping fail, > + * as it would be larger than the ELF file itself. > + * > + * As a result, only ET_DYN does this, since > + * some ET_EXEC (e.g. ia64) may have virtual > + * memory holes between LOADs. > + * > + */ > total_size = total_mapping_size(elf_phdata, > elf_ex->e_phnum); > if (!total_size) { This does not apply for me, I'm looking around and can't find any reference to the first_pt_load variable you're removing there? What commit/tag are you applying this on top of?