Gentle reminder for the experts out there. Need some of your valuable inputs.

-imran

On Wed, Jul 1, 2015 at 11:07 PM, ik.nitk <ik.nitk@gmail.com> wrote:
This patch adds feature for lxc containers to inherit namespaces. This is very similar to what
lxc-tools or docker provides.  Look for "man lxc-start" and you will find that you can pass command args as
[ --share-[net|ipc|uts] name|pid ]. Or check out docker networking option in which you can give --net=container:NAME_or_ID as an option for sharing namespace.

>From this patch you can add extra libvirt option to share namespace in following way.
 <lxc:namespace>
   <lxc:sharenet type='netns' value='red'/>
   <lxc:shareipc type='pid' value='12345'/>
   <lxc:shareuts type='name' value='container1'/>
 </lxc:namespace>


---
 docs/drvlxc.html.in                   |  18 +++
 docs/schemas/domaincommon.rng         |  42 ++++++
 src/Makefile.am                       |   4 +-
 src/lxc/lxc_conf.c                    |   2 +-
 src/lxc/lxc_conf.h                    |  15 +++
 src/lxc/lxc_container.c               | 236 +++++++++++++++++++++++++++++++++-
 src/lxc/lxc_domain.c                  | 164 ++++++++++++++++++++++-
 src/lxc/lxc_domain.h                  |   1 +
 tests/lxcxml2xmldata/lxc-sharenet.xml |  33 +++++
 tests/lxcxml2xmltest.c                |   1 +
 10 files changed, 507 insertions(+), 9 deletions(-)
 create mode 100644 tests/lxcxml2xmldata/lxc-sharenet.xml

diff --git a/docs/drvlxc.html.in b/docs/drvlxc.html.in
index a094bd9..d14d4c7 100644
--- a/docs/drvlxc.html.in
+++ b/docs/drvlxc.html.in
@@ -590,6 +590,24 @@ Note that allowing capabilities that are normally dropped by default can serious
 affect the security of the container and the host.
 </p>

+<h2><a name="share">Inherit namespaces</a></h2>
+
+<p>
+Libvirt allows you to inherit the namespace from container/process just like lxc tools
+or docker provides to share the network namespace. The following can be used to share
+required namespaces. If we want to share only one then the other namespaces can be ignored.
+</p>
+<pre>
+&lt;domain type='lxc' xmlns:lxc='http://libvirt.org/schemas/domain/lxc/1.0'&gt;
+...
+&lt;lxc:namespace&gt;
+  &lt;lxc:sharenet type='netns' value='red'/&gt;
+  &lt;lxc:shareuts type='name' value='container1'/&gt;
+  &lt;lxc:shareipc type='pid' value='12345'/&gt;
+&lt;/lxc:namespace&gt;
+&lt;/domain&gt;
+</pre>
+
 <h2><a name="usage">Container usage / management</a></h2>

 <p>
diff --git a/docs/schemas/domaincommon.rng b/docs/schemas/domaincommon.rng
index 1120003..803b327 100644
--- a/docs/schemas/domaincommon.rng
+++ b/docs/schemas/domaincommon.rng
@@ -68,6 +68,9 @@
           <ref name='qemucmdline'/>
         </optional>
         <optional>
+          <ref name='lxcsharens'/>
+        </optional>
+        <optional>
           <ref name='keywrap'/>
         </optional>
       </interleave>
@@ -5012,6 +5015,45 @@
     </element>
   </define>

+  <!--
+       Optional hypervisor extensions in their own namespace:
+       LXC
+    -->
+  <define name="lxcsharens">
+    <element name="namespace" ns="http://libvirt.org/schemas/domain/lxc/1.0">
+      <zeroOrMore>
+        <element name="sharenet">
+          <attribute name="type">
+            <choice>
+              <value>netns</value>
+              <value>name</value>
+              <value>pid</value>
+            </choice>
+          </attribute>
+          <attribute name='value'/>
+        </element>
+        <element name="shareipc">
+          <attribute name="type">
+            <choice>
+              <value>name</value>
+              <value>pid</value>
+            </choice>
+          </attribute>
+          <attribute name='value'/>
+        </element>
+        <element name="shareuts">
+          <attribute name="type">
+            <choice>
+              <value>name</value>
+              <value>pid</value>
+            </choice>
+          </attribute>
+          <attribute name='value'/>
+        </element>
+      </zeroOrMore>
+    </element>
+  </define>
+
   <define name="metadata">
     <element name="metadata">
       <zeroOrMore>
diff --git a/src/Makefile.am b/src/Makefile.am
index be63e26..ef96a5a 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -1319,7 +1319,7 @@ libvirt_driver_lxc_impl_la_CFLAGS = \
                -I$(srcdir)/access \
                -I$(srcdir)/conf \
                $(AM_CFLAGS)
-libvirt_driver_lxc_impl_la_LIBADD = $(CAPNG_LIBS) $(LIBNL_LIBS) $(FUSE_LIBS)
+libvirt_driver_lxc_impl_la_LIBADD = $(CAPNG_LIBS) $(LIBNL_LIBS) $(LIBXML_LIBS) libvirt-lxc.la $(FUSE_LIBS)
 if WITH_BLKID
 libvirt_driver_lxc_impl_la_CFLAGS += $(BLKID_CFLAGS)
 libvirt_driver_lxc_impl_la_LIBADD += $(BLKID_LIBS)
@@ -2709,6 +2709,8 @@ libvirt_lxc_LDADD =                       \
                libvirt-net-rpc.la \
                libvirt_security_manager.la \
                libvirt_conf.la \
+               libvirt.la \
+               libvirt-lxc.la \
                libvirt_util.la \
                ../gnulib/lib/libgnu.la
 if WITH_DTRACE_PROBES
diff --git a/src/lxc/lxc_conf.c b/src/lxc/lxc_conf.c
index c393cb5..96a0f47 100644
--- a/src/lxc/lxc_conf.c
+++ b/src/lxc/lxc_conf.c
@@ -213,7 +213,7 @@ lxcDomainXMLConfInit(void)
 {
     return virDomainXMLOptionNew(&virLXCDriverDomainDefParserConfig,
                                  &virLXCDriverPrivateDataCallbacks,
-                                 NULL);
+                                 &virLXCDriverDomainXMLNamespace);
 }


diff --git a/src/lxc/lxc_conf.h b/src/lxc/lxc_conf.h
index 8340b1f..72b1d44 100644
--- a/src/lxc/lxc_conf.h
+++ b/src/lxc/lxc_conf.h
@@ -67,6 +67,21 @@ struct _virLXCDriverConfig {
     bool securityRequireConfined;
 };

+
+typedef enum {
+    VIR_DOMAIN_NAMESPACE_SHARENET = 0,
+    VIR_DOMAIN_NAMESPACE_SHAREIPC,
+    VIR_DOMAIN_NAMESPACE_SHAREUTS,
+    VIR_DOMAIN_NAMESPACE_LAST,
+} virDomainNamespace;
+
+typedef struct _lxcDomainDef lxcDomainDef;
+typedef lxcDomainDef *lxcDomainDefPtr;
+struct _lxcDomainDef {
+    char *ns_type[VIR_DOMAIN_NAMESPACE_LAST];
+    char *ns_val[VIR_DOMAIN_NAMESPACE_LAST];
+};
+
 struct _virLXCDriver {
     virMutex lock;

diff --git a/src/lxc/lxc_container.c b/src/lxc/lxc_container.c
index 11e9514..d8362ab 100644
--- a/src/lxc/lxc_container.c
+++ b/src/lxc/lxc_container.c
@@ -27,6 +27,7 @@
 #include <config.h>

 #include <fcntl.h>
+#include <sched.h>
 #include <limits.h>
 #include <stdlib.h>
 #include <stdio.h>
@@ -38,7 +39,6 @@
 #include <mntent.h>
 #include <sys/reboot.h>
 #include <linux/reboot.h>
-
 /* Yes, we want linux private one, for _syscall2() macro */
 #include <linux/unistd.h>

@@ -2321,6 +2321,181 @@ virArch lxcContainerGetAlt32bitArch(virArch arch)
     return VIR_ARCH_NONE;
 }

+struct ns_info {
+        const char *proc_name;
+        int clone_flag;
+}ns_info_local[VIR_DOMAIN_NAMESPACE_LAST] = {
+    [VIR_DOMAIN_NAMESPACE_SHARENET] = {"net", CLONE_NEWNET},
+    [VIR_DOMAIN_NAMESPACE_SHAREIPC] = {"ipc", CLONE_NEWIPC},
+    [VIR_DOMAIN_NAMESPACE_SHAREUTS] = {"uts", CLONE_NEWUTS}
+};
+
+static int lxcOpen_ns(lxcDomainDefPtr lxcDef, int ns_fd[VIR_DOMAIN_NAMESPACE_LAST])
+{
+    int i, n, rc = 0;
+    virDomainPtr dom = NULL;
+    virConnectPtr conn = NULL;
+    pid_t pid;
+    int nfdlist;
+    int *fdlist;
+    char *path = NULL;
+    char *eptr;
+    for (i = 0; i < VIR_DOMAIN_NAMESPACE_LAST; i++)
+        ns_fd[i] = -1;
+
+    if (STREQ_NULLABLE("netns", lxcDef->ns_type[VIR_DOMAIN_NAMESPACE_SHARENET])) {
+        if (virAsprintf(&path, "/var/run/netns/%s", lxcDef->ns_val[VIR_DOMAIN_NAMESPACE_SHARENET]) < 0)
+            return  -1;
+        ns_fd[VIR_DOMAIN_NAMESPACE_SHARENET] = open(path, O_RDONLY);
+        VIR_FREE(path);
+        if (ns_fd[VIR_DOMAIN_NAMESPACE_SHARENET] < 0) {
+            virReportSystemError(errno,
+                      _("failed to open netns %s"), lxcDef->ns_val[VIR_DOMAIN_NAMESPACE_SHARENET]);
+            return -1;
+        }
+    }
+    for (i = 0; i < VIR_DOMAIN_NAMESPACE_LAST; i++) {
+        /* If not yet intialized by above: netns*/
+        if (lxcDef->ns_type[i] && ns_fd[i] == -1) {
+            pid = strtol(lxcDef->ns_val[i], &eptr, 10);
+            if (*eptr != '\0' || pid < 1) {
+                /* check if the domain is running, then set the namespaces
+                 * to that container
+                 */
+                const char *ns[] = { "user", "ipc", "uts", "net", "pid", "mnt" };
+                conn = virConnectOpen("lxc:///");
+                if (!conn) {
+                    virReportError(virGetLastError()->code,
+                      _("unable to get connect to lxc %s"), lxcDef->ns_val[i]);
+                    rc = -1;
+                    goto cleanup;
+                }
+                dom = virDomainLookupByName(conn, lxcDef->ns_val[i]);
+                if (!dom) {
+                    virReportError(virGetLastError()->code,
+                                   _("Unable to lookup peer containeri %s"),
+                                   lxcDef->ns_val[i]);
+                    rc = -1;
+                    goto cleanup;
+                }
+                if ((nfdlist = virDomainLxcOpenNamespace(dom, &fdlist, 0)) < 0) {
+                    virReportError(virGetLastError()->code,
+                                   _("Unable to open %s"), lxcDef->ns_val[i]);
+                    rc = -1;
+                    goto cleanup;
+                }
+                for (n = 0; n < ARRAY_CARDINALITY(ns); n++) {
+                    if (STREQ(ns[n], ns_info_local[i].proc_name)) {
+                        ns_fd[i] = fdlist[n];
+                    } else {
+                        if (VIR_CLOSE(fdlist[n]) < 0)
+                           VIR_ERROR(_("failed to close fd. ignoring.."));
+                    }
+                }
+                if (nfdlist > 0)
+                    VIR_FREE(fdlist);
+            } else {
+                if (virAsprintf(&path, "/proc/%d/ns/%s", pid, ns_info_local[i].proc_name) < 0)
+                    return -1;
+                ns_fd[i] = open(path, O_RDONLY);
+                VIR_FREE(path);
+                if (ns_fd[i] < 0) {
+                    virReportSystemError(errno,
+                      _("failed to open ns %s"), lxcDef->ns_val[i]);
+                    return -1;
+                }
+            }
+        }
+    }
+ cleanup:
+    if (dom)
+        virDomainFree(dom);
+    if (conn)
+        virConnectClose(conn);
+    return rc;
+}
+
+
+static void lxcClose_ns(int ns_fd[VIR_DOMAIN_NAMESPACE_LAST])
+{
+    int i;
+    for (i = 0; i < VIR_DOMAIN_NAMESPACE_LAST; i++) {
+        if (ns_fd[i] > -1) {
+            if (VIR_CLOSE(ns_fd[i]) < 0)
+                virReportSystemError(errno, "%s", _("failed to close file"));
+            ns_fd[i] = -1;
+        }
+    }
+}
+
+
+/**
+ * lxcPreserve_ns:
+ * @ns_fd: array to store current namespace
+ * @clone_flags: namespaces that need to be preserved
+ */
+static int lxcPreserve_ns(int ns_fd[VIR_DOMAIN_NAMESPACE_LAST], int clone_flags)
+{
+    int i, saved_errno;
+    char *path = NULL;
+
+    for (i = 0; i < VIR_DOMAIN_NAMESPACE_LAST; i++)
+        ns_fd[i] = -1;
+
+    if (!virFileExists("/proc/self/ns")) {
+        virReportSystemError(errno, "%s",
+                             _("Kernel does not support attach; preserve_ns ignored"));
+        return -1;
+    }
+
+    for (i = 0; i < VIR_DOMAIN_NAMESPACE_LAST; i++) {
+        if ((clone_flags & ns_info_local[i].clone_flag) == 0)
+            continue;
+        if (virAsprintf(&path, "/proc/self/ns/%s",
+                         ns_info_local[i].proc_name) < 0)
+              goto error;
+        ns_fd[i] = open(path, O_RDONLY | O_CLOEXEC);
+        if (ns_fd[i] < 0)
+            goto error;
+        VIR_FREE(path);
+    }
+    return 0;
+ error:
+    saved_errno = errno;
+    lxcClose_ns(ns_fd);
+    errno = saved_errno;
+    virReportSystemError(errno, _("lxcPreserve_ns failed for '%s'"), path);
+    VIR_FREE(path);
+    return -1;
+}
+
+/**
+ * lxcAttach_ns:
+ * @ns_fd: array of namespaces to attach
+ */
+static int lxcAttach_ns(const int ns_fd[VIR_DOMAIN_NAMESPACE_LAST])
+{
+    int i;
+
+    for (i = 0; i < VIR_DOMAIN_NAMESPACE_LAST; i++) {
+        if (ns_fd[i] < 0)
+            continue;
+         VIR_DEBUG("Setting into namespace\n");
+        /* We get EINVAL if new NS is same as the current
+         * NS, or if the fd namespace doesn't match the
+         * type passed to setns()'s second param. Since we
+         * pass 0, we know the EINVAL is harmless
+         */
+        if (setns(ns_fd[i], 0) < 0 &&
+            errno != EINVAL) {
+            virReportSystemError(errno, _("failed to set namespace '%s'")
+                                 , ns_info_local[i].proc_name);
+            return -1;
+        }
+    }
+    return 0;
+}
+

 /**
  * lxcContainerStart:
@@ -2346,9 +2521,13 @@ int lxcContainerStart(virDomainDefPtr def,
                       char **ttyPaths)
 {
     pid_t pid;
-    int cflags;
+    int cflags, i;
     int stacksize = getpagesize() * 4;
     char *stack, *stacktop;
+    int saved_ns_fd[VIR_DOMAIN_NAMESPACE_LAST];
+    int ns_inherit_fd[VIR_DOMAIN_NAMESPACE_LAST];
+    int preserve_mask = 0;
+    lxcDomainDefPtr lxcDef;
     lxc_child_argv_t args = {
         .config = def,
         .securityDriver = securityDriver,
@@ -2368,7 +2547,12 @@ int lxcContainerStart(virDomainDefPtr def,

     stacktop = stack + stacksize;

-    cflags = CLONE_NEWPID|CLONE_NEWNS|CLONE_NEWUTS|CLONE_NEWIPC|SIGCHLD;
+    lxcDef = def->namespaceData;
+    for (i = 0; i < VIR_DOMAIN_NAMESPACE_LAST; i++)
+       if (lxcDef && lxcDef->ns_type[i])
+           preserve_mask |= ns_info_local[i].clone_flag;
+
+    cflags = CLONE_NEWPID|CLONE_NEWNS|SIGCHLD;

     if (userns_required(def)) {
         if (userns_supported()) {
@@ -2381,10 +2565,43 @@ int lxcContainerStart(virDomainDefPtr def,
             return -1;
         }
     }
+    if (!lxcDef || !lxcDef->ns_type[VIR_DOMAIN_NAMESPACE_SHARENET]) {
+        if (lxcNeedNetworkNamespace(def)) {
+            VIR_DEBUG("Enable network namespaces");
+            cflags |= CLONE_NEWNET;
+        }
+    } else {
+        VIR_DEBUG("Inheriting a net namespace");
+    }
+
+    if (!lxcDef || !lxcDef->ns_type[VIR_DOMAIN_NAMESPACE_SHAREIPC]) {
+        cflags |= CLONE_NEWIPC;
+    } else {
+        VIR_DEBUG("Inheriting an IPC namespace");
+    }
+
+    if (!lxcDef || !lxcDef->ns_type[VIR_DOMAIN_NAMESPACE_SHAREUTS]) {
+        cflags |= CLONE_NEWUTS;
+    } else {
+        VIR_DEBUG("Inheriting a UTS namespace");
+    }
+
+    if (lxcDef && lxcPreserve_ns(saved_ns_fd, preserve_mask) < 0) {
+        virReportError(VIR_ERR_SYSTEM_ERROR, "%s",
+                       _("failed to preserve the namespace"));
+        return -1;
+    }

-    if (lxcNeedNetworkNamespace(def)) {
-        VIR_DEBUG("Enable network namespaces");
-        cflags |= CLONE_NEWNET;
+    if (lxcDef && lxcOpen_ns(lxcDef, ns_inherit_fd)) {
+        virReportError(VIR_ERR_SYSTEM_ERROR, "%s",
+                       _("failed to open the namespace"));
+        return -1;
+    }
+
+    if (lxcDef && lxcAttach_ns(ns_inherit_fd) < 0) {
+        virReportError(VIR_ERR_SYSTEM_ERROR, "%s",
+                       _("failed to attach the namespace"));
+        return -1;
     }

     VIR_DEBUG("Cloning container init process");
@@ -2397,7 +2614,14 @@ int lxcContainerStart(virDomainDefPtr def,
                              _("Failed to run clone container"));
         return -1;
     }
+    if (lxcDef && lxcAttach_ns(saved_ns_fd)) {
+        virReportError(VIR_ERR_SYSTEM_ERROR, "%s",
+                             _("failed to restore saved namespaces"));
+    }

+    /* clean up */
+    if (lxcDef)
+        lxcClose_ns(ns_inherit_fd);
     return pid;
 }

diff --git a/src/lxc/lxc_domain.c b/src/lxc/lxc_domain.c
index 70606f3..5e63969 100644
--- a/src/lxc/lxc_domain.c
+++ b/src/lxc/lxc_domain.c
@@ -26,8 +26,14 @@
 #include "viralloc.h"
 #include "virlog.h"
 #include "virerror.h"
+#include <fcntl.h>
+#include <libxml/xpathInternals.h>
+#include "virstring.h"
+#include "virutil.h"
+#include "virfile.h"

 #define VIR_FROM_THIS VIR_FROM_LXC
+#define LXC_NAMESPACE_HREF "http://libvirt.org/schemas/domain/lxc/1.0"

 VIR_LOG_INIT("lxc.lxc_domain");

@@ -41,6 +47,163 @@ static void *virLXCDomainObjPrivateAlloc(void)
     return priv;
 }

+VIR_ENUM_DECL(virDomainNamespace)
+VIR_ENUM_IMPL(virDomainNamespace, VIR_DOMAIN_NAMESPACE_LAST,
+    N_("sharenet"),
+    N_("shareipc"),
+    N_("shareuts"))
+
+static void
+lxcDomainDefNamespaceFree(void *nsdata)
+{
+    int j;
+    lxcDomainDefPtr lxcDef = nsdata;
+    for (j = 0; j < VIR_DOMAIN_NAMESPACE_LAST; j++) {
+       VIR_FREE(lxcDef->ns_type[j]);
+       VIR_FREE(lxcDef->ns_val[j]);
+    }
+    VIR_FREE(nsdata);
+}
+
+static int
+lxcDomainDefNamespaceParse(xmlDocPtr xml ATTRIBUTE_UNUSED,
+                           xmlNodePtr root ATTRIBUTE_UNUSED,
+                           xmlXPathContextPtr ctxt,
+                           void **data)
+{
+    lxcDomainDefPtr lxcDef = NULL;
+    xmlNodePtr *nodes = NULL;
+    bool uses_lxc_ns = false;
+    xmlNodePtr node;
+    int feature;
+    int n;
+    char *tmp = NULL;
+    size_t i;
+
+    if (xmlXPathRegisterNs(ctxt, BAD_CAST "lxc", BAD_CAST LXC_NAMESPACE_HREF) < 0) {
+        virReportError(VIR_ERR_INTERNAL_ERROR,
+                       _("Failed to register xml namespace '%s'"),
+                       LXC_NAMESPACE_HREF);
+        return -1;
+    }
+
+    if (VIR_ALLOC(lxcDef) < 0)
+        return -1;
+    /* Init ns_herit_fd for namespaces */
+    for (i = 0; i < VIR_DOMAIN_NAMESPACE_LAST; i++) {
+        lxcDef->ns_type[i] = NULL;
+        lxcDef->ns_val[i] = NULL;
+    }
+
+    node = ctxt->node;
+    if ((n = virXPathNodeSet("./lxc:namespace/*", ctxt, &nodes)) < 0)
+        goto error;
+    uses_lxc_ns |= n > 0;
+
+    for (i = 0; i < n; i++) {
+        feature =
+            virDomainNamespaceTypeFromString((const char *) nodes[i]->name);
+        if (feature < 0) {
+            virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
+                            _("unsupported Namespace feature: %s"),
+                            nodes[i]->name);
+            goto error;
+        }
+
+        ctxt->node = nodes[i];
+
+        switch ((virDomainNamespace) feature) {
+        case VIR_DOMAIN_NAMESPACE_SHARENET:
+        case VIR_DOMAIN_NAMESPACE_SHAREIPC:
+        case VIR_DOMAIN_NAMESPACE_SHAREUTS:
+            {
+                tmp = virXMLPropString(nodes[i], "type");
+                if (tmp == NULL) {
+                    virReportError(VIR_ERR_INTERNAL_ERROR,
+                                   "%s", _("No lxc environment type specified"));
+                    goto error;
+                }
+                /* save the tmp so that its needed while writing to xml */
+                lxcDef->ns_type[feature] = tmp;
+                tmp = virXMLPropString(nodes[i], "value");
+                if (tmp == NULL) {
+                    virReportError(VIR_ERR_INTERNAL_ERROR,
+                                   "%s", _("No lxc environment type specified"));
+                    goto error;
+                }
+                lxcDef->ns_val[feature] = tmp;
+            }
+            break;
+        case VIR_DOMAIN_NAMESPACE_LAST:
+            break;
+        }
+    }
+    VIR_FREE(nodes);
+    ctxt->node = node;
+    if (uses_lxc_ns)
+        *data = lxcDef;
+    else
+        VIR_FREE(lxcDef);
+    return 0;
+ error:
+    VIR_FREE(nodes);
+    lxcDomainDefNamespaceFree(lxcDef);
+    return -1;
+}
+
+
+static int
+lxcDomainDefNamespaceFormatXML(virBufferPtr buf,
+                               void *nsdata)
+{
+    lxcDomainDefPtr lxcDef = nsdata;
+    size_t j;
+
+    if (!lxcDef)
+       return 0;
+
+    virBufferAddLit(buf, "<lxc:namespace>\n");
+    virBufferAdjustIndent(buf, 2);
+
+    for (j = 0; j < VIR_DOMAIN_NAMESPACE_LAST; j++) {
+        switch ((virDomainNamespace) j) {
+        case VIR_DOMAIN_NAMESPACE_SHAREIPC:
+        case VIR_DOMAIN_NAMESPACE_SHAREUTS:
+        case VIR_DOMAIN_NAMESPACE_SHARENET:
+            {
+                if (lxcDef->ns_type[j]) {
+                    virBufferAsprintf(buf, "<lxc:%s type='%s' value='%s'/>\n",
+                                      virDomainNamespaceTypeToString(j),
+                                      lxcDef->ns_type[j],
+                                      lxcDef->ns_val[j]);
+                }
+            }
+            break;
+        case VIR_DOMAIN_NAMESPACE_LAST:
+            break;
+        }
+    }
+
+    virBufferAdjustIndent(buf, -2);
+    virBufferAddLit(buf, "</lxc:namespace>\n");
+    return 0;
+}
+
+static const char *
+lxcDomainDefNamespaceHref(void)
+{
+    return "xmlns:lxc='" LXC_NAMESPACE_HREF "'";
+}
+
+
+virDomainXMLNamespace virLXCDriverDomainXMLNamespace = {
+    .parse = lxcDomainDefNamespaceParse,
+    .free = lxcDomainDefNamespaceFree,
+    .format = lxcDomainDefNamespaceFormatXML,
+    .href = lxcDomainDefNamespaceHref,
+};
+
+
 static void virLXCDomainObjPrivateFree(void *data)
 {
     virLXCDomainObjPrivatePtr priv = data;
@@ -77,7 +240,6 @@ virLXCDomainObjPrivateXMLParse(xmlXPathContextPtr ctxt,
     } else {
         priv->initpid = thepid;
     }
-
     return 0;
 }

diff --git a/src/lxc/lxc_domain.h b/src/lxc/lxc_domain.h
index 751aece..25df999 100644
--- a/src/lxc/lxc_domain.h
+++ b/src/lxc/lxc_domain.h
@@ -41,6 +41,7 @@ struct _virLXCDomainObjPrivate {
     virCgroupPtr cgroup;
 };

+extern virDomainXMLNamespace virLXCDriverDomainXMLNamespace;
 extern virDomainXMLPrivateDataCallbacks virLXCDriverPrivateDataCallbacks;
 extern virDomainDefParserConfig virLXCDriverDomainDefParserConfig;

diff --git a/tests/lxcxml2xmldata/lxc-sharenet.xml b/tests/lxcxml2xmldata/lxc-sharenet.xml
new file mode 100644
index 0000000..a2b8d1b
--- /dev/null
+++ b/tests/lxcxml2xmldata/lxc-sharenet.xml
@@ -0,0 +1,33 @@
+<domain type='lxc' xmlns:lxc='http://libvirt.org/schemas/domain/lxc/1.0'>
+  <name>jessie</name>
+  <uuid>e21987a5-e98e-9c99-0e35-803e4d9ad1fe</uuid>
+  <memory unit='KiB'>1048576</memory>
+  <currentMemory unit='KiB'>1048576</currentMemory>
+  <vcpu placement='static'>1</vcpu>
+  <resource>
+    <partition>/machine</partition>
+  </resource>
+  <os>
+    <type arch='x86_64'>exe</type>
+    <init>/sbin/init</init>
+  </os>
+  <clock offset='utc'/>
+  <on_poweroff>destroy</on_poweroff>
+  <on_reboot>restart</on_reboot>
+  <on_crash>restart</on_crash>
+  <devices>
+    <emulator>/usr/libexec/libvirt_lxc</emulator>
+    <filesystem type='mount' accessmode='passthrough'>
+      <source dir='/mach/jessie'/>
+      <target dir='/'/>
+    </filesystem>
+    <console type='pty'>
+      <target type='lxc' port='0'/>
+    </console>
+  </devices>
+  <lxc:namespace>
+    <lxc:sharenet type='netns' value='red'/>
+    <lxc:shareipc type='pid' value='12345'/>
+    <lxc:shareuts type='name' value='container1'/>
+  </lxc:namespace>
+</domain>
diff --git a/tests/lxcxml2xmltest.c b/tests/lxcxml2xmltest.c
index 3e00347..8d824b9 100644
--- a/tests/lxcxml2xmltest.c
+++ b/tests/lxcxml2xmltest.c
@@ -133,6 +133,7 @@ mymain(void)
     DO_TEST("filesystem-root");
     DO_TEST("idmap");
     DO_TEST("capabilities");
+    DO_TEST("sharenet");

     virObjectUnref(caps);
     virObjectUnref(xmlopt);
--
1.9.1