From patchwork Fri Jun 19 17:18:09 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Dr. David Alan Gilbert" X-Patchwork-Id: 11614737 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 53D1113A0 for ; Fri, 19 Jun 2020 17:22:30 +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 2B591208DB for ; Fri, 19 Jun 2020 17:22:30 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="eiYrxtPX" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2B591208DB Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Received: from localhost ([::1]:37300 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jmKij-0001Ck-A7 for patchwork-qemu-devel@patchwork.kernel.org; Fri, 19 Jun 2020 13:22:29 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:32966) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jmKel-00011e-1I for qemu-devel@nongnu.org; Fri, 19 Jun 2020 13:18:23 -0400 Received: from us-smtp-2.mimecast.com ([207.211.31.81]:51507 helo=us-smtp-delivery-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1jmKej-0006H7-0o for qemu-devel@nongnu.org; Fri, 19 Jun 2020 13:18:22 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1592587100; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=39LY6zwHpBop9k1GBKeTNcptDY6I2N59MV1dShpsMwA=; b=eiYrxtPX51b3SWVWdFjIuecYKSxsFqvKM8GTJkZFxpRzTh4W1bRpvPTtgNOGHA4F4HOJ5N BcUWcLgYUnLBmtMhpqxlF9zNIDIzPLSdf5GhCGiDjIM5QgxgwYCBfSCydOYdG9XwTrlZ/3 KLiF6/YBOM8ioG2KzU+AeLeny5ZcsYs= 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-199-izLRoqZ9NcSO5RlkEZwoww-1; Fri, 19 Jun 2020 13:18:18 -0400 X-MC-Unique: izLRoqZ9NcSO5RlkEZwoww-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 72C0D107ACCA for ; Fri, 19 Jun 2020 17:18:17 +0000 (UTC) Received: from dgilbert-t580.localhost (ovpn-114-215.ams2.redhat.com [10.36.114.215]) by smtp.corp.redhat.com (Postfix) with ESMTP id EB91119D7B; Fri, 19 Jun 2020 17:18:10 +0000 (UTC) From: "Dr. David Alan Gilbert (git)" To: qemu-devel@nongnu.org, virtio-fs@redhat.com, stefanha@redhat.com, vgoyal@redhat.com Subject: [PATCH] virtiofsd: Allow capability restriction to be turned off Date: Fri, 19 Jun 2020 18:18:09 +0100 Message-Id: <20200619171809.30984-1-dgilbert@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Received-SPF: pass client-ip=207.211.31.81; envelope-from=dgilbert@redhat.com; helo=us-smtp-delivery-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/06/19 01:50:04 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -30 X-Spam_score: -3.1 X-Spam_bar: --- X-Spam_report: (-3.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=-0.01, RCVD_IN_MSPIKE_WL=-0.01, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=_AUTOLEARN 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: , Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" From: "Dr. David Alan Gilbert" Commit a59feb483b8fae24d043 dropped most capabilities at startup, since in most cases virtiofsd doesn't need them. Unfortunately we found a case that needs CAP_SYS_ADMIN - setting trusted extended attributes. It's rare to need it, and the clean fix for it is going to be more complicated, but as a way for existing users to continue, allow the capability restriction to be turned off by adding -o no_restrictcaps We still drop the capabilities by default since this seems much safer; even if we don't have an explicit problem to fix. Signed-off-by: Dr. David Alan Gilbert --- docs/tools/virtiofsd.rst | 3 +++ tools/virtiofsd/helper.c | 3 +++ tools/virtiofsd/passthrough_ll.c | 8 +++++++- 3 files changed, 13 insertions(+), 1 deletion(-) diff --git a/docs/tools/virtiofsd.rst b/docs/tools/virtiofsd.rst index 378594c422..8819d7d19e 100644 --- a/docs/tools/virtiofsd.rst +++ b/docs/tools/virtiofsd.rst @@ -81,6 +81,9 @@ Options Enable/disable extended attributes (xattr) on files and directories. The default is ``no_xattr``. + * restrictcaps|no_restrictcaps\n" + Restrict capabilities at startup. The default is ``restrictcaps``. + .. option:: --socket-path=PATH Listen on vhost-user UNIX domain socket at PATH. diff --git a/tools/virtiofsd/helper.c b/tools/virtiofsd/helper.c index 00a1ef666a..51ed9fbed0 100644 --- a/tools/virtiofsd/helper.c +++ b/tools/virtiofsd/helper.c @@ -174,6 +174,9 @@ void fuse_cmdline_help(void) " default: no_writeback\n" " -o xattr|no_xattr enable/disable xattr\n" " default: no_xattr\n" + " -o restrictcaps|no_restrictcaps\n" + " restrict capabilities at startup\n" + " default: restrictcaps\n" " --rlimit-nofile= set maximum number of file descriptors\n" " (0 leaves rlimit unchanged)\n" " default: min(1000000, fs.file-max - 16384)\n" diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c index 2ce7c96085..8dee657b19 100644 --- a/tools/virtiofsd/passthrough_ll.c +++ b/tools/virtiofsd/passthrough_ll.c @@ -144,6 +144,7 @@ struct lo_data { int flock; int posix_lock; int xattr; + int restrictcaps; char *source; double timeout; int cache; @@ -170,6 +171,8 @@ static const struct fuse_opt lo_opts[] = { { "no_posix_lock", offsetof(struct lo_data, posix_lock), 0 }, { "xattr", offsetof(struct lo_data, xattr), 1 }, { "no_xattr", offsetof(struct lo_data, xattr), 0 }, + { "restrictcaps", offsetof(struct lo_data, restrictcaps), 1 }, + { "no_restrictcaps", offsetof(struct lo_data, restrictcaps), 0 }, { "timeout=%lf", offsetof(struct lo_data, timeout), 0 }, { "timeout=", offsetof(struct lo_data, timeout_set), 1 }, { "cache=none", offsetof(struct lo_data, cache), CACHE_NONE }, @@ -2615,7 +2618,9 @@ static void setup_sandbox(struct lo_data *lo, struct fuse_session *se, setup_namespaces(lo, se); setup_mounts(lo->source); setup_seccomp(enable_syslog); - setup_capabilities(); + if (lo->restrictcaps) { + setup_capabilities(); + } } /* Set the maximum number of open file descriptors */ @@ -2764,6 +2769,7 @@ int main(int argc, char *argv[]) .writeback = 0, .posix_lock = 1, .proc_self_fd = -1, + .restrictcaps = 1, }; struct lo_map_elem *root_elem; int ret = -1;