From patchwork Mon Mar 4 22:49:23 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Subject: rng: restrict passthrough names to known-good files Date: Mon, 04 Mar 2013 12:49:23 -0000 From: Eric Blake X-Patchwork-Id: 224853 Message-Id: <1362437363-27570-1-git-send-email-eblake@redhat.com> To: libvir-list@redhat.com Cc: pbonzini@redhat.com, qemu-devel@nongnu.org, anthony@codemonkey.ws There is some controversy[1] on the qemu list on whether qemu should have ever allowed arbitrary file name passthrough, or whether it should be restricted to JUST /dev/random and /dev/hwrng. It is always easier to add support for additional filenames than it is to remove support for something once released, so this patch restricts libvirt 1.0.3 (where the virtio-random backend was first supported) to just the two uncontroversial names, letting us defer to a later date any decision on whether supporting arbitrary files makes sense. Additionally, since qemu 1.4 does NOT support /dev/fdset/nnn fd passthrough for the backend, limiting to just two known names means that we don't get tempted to try fd passthrough where it won't work. [1]https://lists.gnu.org/archive/html/qemu-devel/2013-03/threads.html#00023 * src/conf/domain_conf.c (virDomainRNGDefParseXML): Only allow /dev/random and /dev/hwrng. * docs/schemas/domaincommon.rng: Flag invalid files. * docs/formatdomain.html.in (elementsRng): Document this. * tests/qemuxml2argvdata/qemuxml2argv-virtio-rng-random.args: Update test to match. * tests/qemuxml2argvdata/qemuxml2argv-virtio-rng-random.xml: Likewise. Acked-by: Anthony Liguori --- This needs to be acked before libvirt 1.0.3; otherwise we are stuck supporting arbitrary name passthrough. docs/formatdomain.html.in | 3 ++- docs/schemas/domaincommon.rng | 5 ++++- src/conf/domain_conf.c | 7 +++++++ tests/qemuxml2argvdata/qemuxml2argv-virtio-rng-random.args | 2 +- tests/qemuxml2argvdata/qemuxml2argv-virtio-rng-random.xml | 2 +- 5 files changed, 15 insertions(+), 4 deletions(-) diff --git a/docs/formatdomain.html.in b/docs/formatdomain.html.in index 1835b39..4cafc92 100644 --- a/docs/formatdomain.html.in +++ b/docs/formatdomain.html.in @@ -4310,7 +4310,8 @@ qemu-kvm -net nic,model=? /dev/null model attribute. Supported source models are:

diff --git a/docs/schemas/domaincommon.rng b/docs/schemas/domaincommon.rng index e7231cc..4b60885 100644 --- a/docs/schemas/domaincommon.rng +++ b/docs/schemas/domaincommon.rng @@ -3511,7 +3511,10 @@ random - + + /dev/random + /dev/hwrng + diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c index 995cf0c..9c96cf1 100644 --- a/src/conf/domain_conf.c +++ b/src/conf/domain_conf.c @@ -7423,6 +7423,13 @@ virDomainRNGDefParseXML(const xmlNodePtr node, switch ((enum virDomainRNGBackend) def->backend) { case VIR_DOMAIN_RNG_BACKEND_RANDOM: def->source.file = virXPathString("string(./backend)", ctxt); + if (STRNEQ(def->source.file, "/dev/random") && + STRNEQ(def->source.file, "/dev/hwrng")) { + virReportError(VIR_ERR_XML_ERROR, + _("file '%s' is not a supported random source"), + def->source.file); + goto error; + } break; case VIR_DOMAIN_RNG_BACKEND_EGD: diff --git a/tests/qemuxml2argvdata/qemuxml2argv-virtio-rng-random.args b/tests/qemuxml2argvdata/qemuxml2argv-virtio-rng-random.args index ad27132..7ab9dbc 100644 --- a/tests/qemuxml2argvdata/qemuxml2argv-virtio-rng-random.args +++ b/tests/qemuxml2argvdata/qemuxml2argv-virtio-rng-random.args @@ -2,5 +2,5 @@ LC_ALL=C PATH=/bin HOME=/home/test USER=test LOGNAME=test /usr/bin/qemu \ -S -M pc -m 214 -smp 1 -nographic -nodefaults \ -monitor unix:/tmp/test-monitor,server,nowait -no-acpi -boot c -usb \ -device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x3 \ --object 'rng-random,id=rng0,filename=/test/ph - /test/ph<ile + /dev/hwrng