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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7E909C433EF for ; Mon, 27 Sep 2021 21:19:56 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 01EBE6103B for ; Mon, 27 Sep 2021 21:19:55 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 01EBE6103B Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=nongnu.org Received: from localhost ([::1]:43078 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1mUy2V-0000TO-2s for qemu-devel@archiver.kernel.org; Mon, 27 Sep 2021 17:19:55 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:49292) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mUy1P-0007ar-1z for qemu-devel@nongnu.org; Mon, 27 Sep 2021 17:18:47 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:58784) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mUy1L-0007CQ-1C for qemu-devel@nongnu.org; Mon, 27 Sep 2021 17:18:44 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1632777521; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=sL+lHTvuswMgF3m1GXUFQKIm0jm/utfJCCuKC8MeJ3k=; b=fSO5vqbRBx1vVQRz1Z2Ho2lknsEA4mn77dBO16IoiEoFwLUT6d1wMhC8QpE57XcA29rtUj r8mBvRC6pBZsARJ+Ey4l+dE3yfMFZggyANry5lLNcIBgIE8zWF7AMEA0krviFAY2aFeR9k mEsAn/RjJHp0+egQJP3xuEG2otfbpb4= 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-370--jReo5YRNimkIw3HyL95ZQ-1; Mon, 27 Sep 2021 17:18:37 -0400 X-MC-Unique: -jReo5YRNimkIw3HyL95ZQ-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 107D3802935; Mon, 27 Sep 2021 21:18:37 +0000 (UTC) Received: from redhat.com (ovpn-113-87.phx2.redhat.com [10.3.113.87]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 6A6A510013D7; Mon, 27 Sep 2021 21:18:36 +0000 (UTC) Date: Mon, 27 Sep 2021 16:18:34 -0500 From: Eric Blake To: "Richard W.M. Jones" Subject: Re: [PATCH v2] nbd/server: Add --selinux-label option Message-ID: <20210927211834.tzqpx4egzwbvjmrs@redhat.com> References: <20210723103303.1731437-1-rjones@redhat.com> <20210723103303.1731437-2-rjones@redhat.com> MIME-Version: 1.0 In-Reply-To: <20210723103303.1731437-2-rjones@redhat.com> User-Agent: NeoMutt/20210205-773-8890a5 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=eblake@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Received-SPF: pass client-ip=170.10.133.124; envelope-from=eblake@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -27 X-Spam_score: -2.8 X-Spam_bar: -- X-Spam_report: (-2.8 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: vsementsov@virtuozzo.com, berrange@redhat.com, qemu-devel@nongnu.org, qemu-block@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Fri, Jul 23, 2021 at 11:33:03AM +0100, Richard W.M. Jones wrote: > Under SELinux, Unix domain sockets have two labels. One is on the > disk and can be set with commands such as chcon(1). There is a > different label stored in memory (called the process label). This can > only be set by the process creating the socket. When using SELinux + > SVirt and wanting qemu to be able to connect to a qemu-nbd instance, > you must set both labels correctly first. > > For qemu-nbd the options to set the second label are awkward. You can > create the socket in a wrapper program and then exec into qemu-nbd. > Or you could try something with LD_PRELOAD. > > This commit adds the ability to set the label straightforwardly on the > command line, via the new --selinux-label flag. (The name of the flag > is the same as the equivalent nbdkit option.) > > A worked example showing how to use the new option can be found in > this bug: https://bugzilla.redhat.com/show_bug.cgi?id=1984938 > > Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1984938 > Signed-off-by: Richard W.M. Jones > --- I'm making one tweak to your patch before sending the pull request: > +++ b/qemu-nbd.c > @@ -64,6 +68,7 @@ > #define QEMU_NBD_OPT_FORK 263 > #define QEMU_NBD_OPT_TLSAUTHZ 264 > #define QEMU_NBD_OPT_PID_FILE 265 > +#define QEMU_NBD_OPT_SELINUX_LABEL 266 > > #define MBR_SIZE 512 > > @@ -116,6 +121,9 @@ static void usage(const char *name) > " --fork fork off the server process and exit the parent\n" > " once the server is running\n" > " --pid-file=PATH store the server's process ID in the given file\n" > +#ifdef CONFIG_SELINUX > +" --selinux-label=LABEL set SELinux process label on listening socket\n" > +#endif The new option is only conditionally advertised under --help (qemu-nbd lacks a stable machine-parseable output, so scraping --help output will have to do for now)... > #if HAVE_NBD_DEVICE > "\n" > "Kernel NBD client support:\n" > @@ -532,6 +540,8 @@ int main(int argc, char **argv) > { "trace", required_argument, NULL, 'T' }, > { "fork", no_argument, NULL, QEMU_NBD_OPT_FORK }, > { "pid-file", required_argument, NULL, QEMU_NBD_OPT_PID_FILE }, > + { "selinux-label", required_argument, NULL, > + QEMU_NBD_OPT_SELINUX_LABEL }, ...but is unconditionally supported as a long option even when support was not compiled in... > { NULL, 0, NULL, 0 } > }; > int ch; > @@ -558,6 +568,7 @@ int main(int argc, char **argv) > int old_stderr = -1; > unsigned socket_activation; > const char *pid_file_name = NULL; > + const char *selinux_label = NULL; > BlockExportOptions *export_opts; > > #ifdef CONFIG_POSIX > @@ -747,6 +758,9 @@ int main(int argc, char **argv) > case QEMU_NBD_OPT_PID_FILE: > pid_file_name = optarg; > break; > + case QEMU_NBD_OPT_SELINUX_LABEL: > + selinux_label = optarg; > + break; > } > } > > @@ -938,6 +952,16 @@ int main(int argc, char **argv) > } else { > backlog = MIN(shared, SOMAXCONN); > } > + if (sockpath && selinux_label) { > +#ifdef CONFIG_SELINUX > + if (setsockcreatecon_raw(selinux_label) == -1) { > + error_report("Cannot set SELinux socket create context " > + "to %s: %s", > + selinux_label, strerror(errno)); > + exit(EXIT_FAILURE); > + } > +#endif ...but here we silently ignore it if support is not compiled in. Better is to issue an error message about using an unsupported option, so I'll squash this in: diff --git i/qemu-nbd.c w/qemu-nbd.c index 5dc82c419255..94f8ec07c064 100644 --- i/qemu-nbd.c +++ w/qemu-nbd.c @@ -962,6 +962,9 @@ int main(int argc, char **argv) selinux_label, strerror(errno)); exit(EXIT_FAILURE); } +#else + error_report("SELinux support not enabled in this binary"); + exit(EXIT_FAILURE); #endif } saddr = nbd_build_socket_address(sockpath, bindto, port); @@ -978,6 +981,9 @@ int main(int argc, char **argv) strerror(errno)); exit(EXIT_FAILURE); } +#else + error_report("SELinux support not enabled in this binary"); + exit(EXIT_FAILURE); #endif } } else { -- Eric Blake, Principal Software Engineer Red Hat, Inc. +1-919-301-3266 Virtualization: qemu.org | libvirt.org