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Fri, 7 Aug 2020 16:33:03 +0000 (UTC) Date: Fri, 7 Aug 2020 17:33:00 +0100 From: "Dr. David Alan Gilbert" To: Vivek Goyal Subject: Re: [PATCH v2 1/5] virtiofsd: Add notion of unprivileged mode Message-ID: <20200807163300.GH2780@work-vm> References: <20200730194736.173994-1-vgoyal@redhat.com> <20200730194736.173994-2-vgoyal@redhat.com> MIME-Version: 1.0 In-Reply-To: <20200730194736.173994-2-vgoyal@redhat.com> User-Agent: Mutt/1.14.6 (2020-07-11) X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=dgilbert@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=207.211.31.120; envelope-from=dgilbert@redhat.com; helo=us-smtp-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/08/07 02:21:37 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_H3=-0.01, RCVD_IN_MSPIKE_WL=-0.01, 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: berrange@redhat.com, vromanso@redhat.com, dwalsh@redhat.com, qemu-devel@nongnu.org, virtio-fs@redhat.com, stefanha@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" * Vivek Goyal (vgoyal@redhat.com) wrote: > At startup if we are running as non-root user, then internally set > unpriviliged mode set. Also add a notion of sandbox NONE and set > that internally in unprivileged mode. setting up namespaces and > chroot() fails in unpriviliged mode. > > Signed-off-by: Vivek Goyal > --- > tools/virtiofsd/passthrough_ll.c | 8 ++++++++ > 1 file changed, 8 insertions(+) > > diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c > index e2fbc614fd..cd91c4a831 100644 > --- a/tools/virtiofsd/passthrough_ll.c > +++ b/tools/virtiofsd/passthrough_ll.c > @@ -147,11 +147,13 @@ enum { > enum { > SANDBOX_NAMESPACE, > SANDBOX_CHROOT, > + SANDBOX_NONE, > }; > > struct lo_data { > pthread_mutex_t mutex; > int sandbox; > + bool unprivileged; > int debug; > int writeback; > int flock; > @@ -3288,6 +3290,12 @@ int main(int argc, char *argv[]) > lo_map_init(&lo.dirp_map); > lo_map_init(&lo.fd_map); > > + if (geteuid() != 0) { > + lo.unprivileged = true; > + lo.sandbox = SANDBOX_NONE; > + fuse_log(FUSE_LOG_DEBUG, "Running in unprivileged passthrough mode.\n"); > + } I don't like this being automatic; to switch to a less secure mode, the user should have to explicitly ask for it; we don't want people accidentally ending up with less security. Also, I'm not sure that checking for geteuid() != 0 is the right test - wouldn't the current virtiofsd run with a non-root user as long as it had the correct capabilities? I was doing to suggest we match cloud-hypervisor where we added --disable-sandbox; but with this we now have a trinary switch; so sandbox=none is probably the right way. Dave > if (fuse_parse_cmdline(&args, &opts) != 0) { > goto err_out1; > } > -- > 2.25.4 > -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK