From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [63.128.21.124]) by sourceware.org (Postfix) with ESMTP id 7C98A3939C15 for ; Tue, 19 Jan 2021 14:40:29 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org 7C98A3939C15 Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-98-NQWBCnVpPL2a8K34pvTSFw-1; Tue, 19 Jan 2021 09:40:27 -0500 X-MC-Unique: NQWBCnVpPL2a8K34pvTSFw-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 110611005D44 for ; Tue, 19 Jan 2021 14:40:26 +0000 (UTC) Received: from oldenburg.str.redhat.com (ovpn-112-110.ams2.redhat.com [10.36.112.110]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 704141042A52; Tue, 19 Jan 2021 14:40:21 +0000 (UTC) From: Florian Weimer To: Carlos O'Donell Cc: Carlos O'Donell via Libc-alpha , DJ Delorie Subject: Re: nsswitch: do not reload if "/" changes References: <25a79acd-f739-83ec-5dcf-ab2bd771f561@redhat.com> <87eeiinq4o.fsf@oldenburg.str.redhat.com> <7109c06d-5f0b-99a2-2aad-9c50bb89c0cb@redhat.com> Date: Tue, 19 Jan 2021 15:40:16 +0100 In-Reply-To: <7109c06d-5f0b-99a2-2aad-9c50bb89c0cb@redhat.com> (Carlos O'Donell's message of "Tue, 19 Jan 2021 09:30:09 -0500") Message-ID: <8735yxhtwv.fsf@oldenburg.str.redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.1 (gnu/linux) MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain X-Spam-Status: No, score=-6.6 required=5.0 tests=BAYES_00, DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, RCVD_IN_DNSWL_LOW, RCVD_IN_MSPIKE_H4, RCVD_IN_MSPIKE_WL, SPF_HELO_NONE, SPF_PASS, TXREP autolearn=ham autolearn_force=no version=3.4.2 X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on server2.sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 19 Jan 2021 14:40:30 -0000 * Carlos O'Donell: > On 1/18/21 11:53 AM, Florian Weimer wrote: >> * Carlos O'Donell via Libc-alpha: >> >>> Can we create a non-test-container test for this? >>> >>> I think you can use support_become_root to unshare and then try >>> to use support_chroot_create/support_chroot_free and xhcroot to >>> change root, and then try to do an NSS call that will fail? >> >> You need to chroot twice, first to get a defined /etc/nsswitch.conf, and >> another one to make sure things don't ger reloaded after chroot. > > That would be a perfect solution. > > However, I think you could get away with recording some known uid/gid > from the system that was doing the build and then ensure that value > is not present in the container. The issue is with loading NSS modules from the system. This can lead to crashes/unpredictable behavior. We've been through this already, if I recall correctly. Thanks, Florian -- Red Hat GmbH, https://de.redhat.com/ , Registered seat: Grasbrunn, Commercial register: Amtsgericht Muenchen, HRB 153243, Managing Directors: Charles Cachera, Brian Klemm, Laurie Krebs, Michael O'Neill