From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 50247 invoked by alias); 4 Jul 2018 13:34:36 -0000 Mailing-List: contact gnu-gabi-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Post: List-Help: List-Subscribe: Sender: gnu-gabi-owner@sourceware.org Received: (qmail 50230 invoked by uid 89); 4 Jul 2018 13:34:35 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Checked: by ClamAV 0.99.4 on sourceware.org X-Virus-Found: No X-Spam-SWARE-Status: No, score=-1.4 required=5.0 tests=AWL,BAYES_00,KAM_LAZY_DOMAIN_SECURITY,SPF_HELO_PASS autolearn=no version=3.3.2 spammy= X-Spam-Status: No, score=-1.4 required=5.0 tests=AWL,BAYES_00,KAM_LAZY_DOMAIN_SECURITY,SPF_HELO_PASS autolearn=no version=3.3.2 X-Spam-Checker-Version: SpamAssassin 3.3.2 (2011-06-06) on sourceware.org X-Spam-Level: X-HELO: mx1.redhat.com Received: from mx3-rdu2.redhat.com (HELO mx1.redhat.com) (66.187.233.73) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Wed, 04 Jul 2018 13:34:34 +0000 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.rdu2.redhat.com [10.11.54.5]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id D9892406F8B2; Wed, 4 Jul 2018 13:34:32 +0000 (UTC) Received: from oldenburg.str.redhat.com (dhcp-192-212.str.redhat.com [10.33.192.212]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 3A8BC7C53; Wed, 4 Jul 2018 13:34:32 +0000 (UTC) Subject: Re: RFA: Add a new gynamic tag: DT_GNU_GOT_PLT_END To: Cary Coutant Cc: Nick Clifton , gnu-gabi@sourceware.org, "H.J. Lu" References: <87sh5hadd6.fsf@redhat.com> <83d583d0-884e-4208-436e-5b25cbb6ce5a@redhat.com> From: Florian Weimer Message-ID: Date: Mon, 01 Jan 2018 00:00:00 -0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.8.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.11.54.5 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.7]); Wed, 04 Jul 2018 13:34:32 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.7]); Wed, 04 Jul 2018 13:34:32 +0000 (UTC) for IP:'10.11.54.5' DOMAIN:'int-mx05.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'fweimer@redhat.com' RCPT:'' X-IsSubscribed: yes X-SW-Source: 2018-q3/txt/msg00003.txt.bz2 On 06/26/2018 02:42 AM, Cary Coutant wrote: >>> OK, so it's a variant of RELRO. I'd prefer using a new program header >>> type, PT_GNU_PLTGOT, then. >> >> Wouldn't this cause the binaries not to run with an older loader? > > Maybe, but new dynamic table entries could do that, too. I think ld.so ignores unknown DT_* entries. > Does anyone remember what the experience was when PT_GNU_RELRO was added? There were binutils crashes. But I was mistaken: ld.so ignores unknown PT_* entries, too. I still think a DT_* entry is conceptually the right choice here. It's really specific to the PLT. It's not something that I expect can be used to change other mappings successfully. Thanks, Florian