[libvirt] [PATCH] lxc / docker containers gives option to inherit the namespaces. Example lxc-start has option [ --share-[net|ipc|uts] name|pid ] where --share-net name|pid means Inherit a network namespace from a name container or a pid.

Imran Khan ik.nitk at gmail.com
Wed Jul 1 18:00:47 UTC 2015


Dear Michal,

Thanks a lot for reviewing the changes.  I really appreciate your ability
to spot very minute errors which have not been spotted by me or my local
reviews.

I have reworked almost all of the review comments you made. and Have sent a
separate email with subject "Inherit namespace feature".  But for
convenience i would like to paste the changes here too. Please forgive for
big mail.   To answer some of your questions below:
   1.  Why this feature :
         (imran):  As the latest container technology (lxc-tools  and
docker) already provides sharing of network namespace. We think that this
feature is important to be added in libvirt lxc too.
          please check this link for lxc-start option :[ *--share-[net|ipc|uts]
**name|pid* ]
           http://man7.org/linux/man-pages/man1/lxc-start.1.html
          please check this link for docker --net option :
              https://docs.docker.com/articles/networking/:
--net=container:NAME_or_ID
   2.  Moving open namespace in driver.
         (imran) I have moved the code to driver now.  But regarding the
function i used the readymade functions instead of using internal data
structure because i would end up writing almost same functions again which
i felt was redundant.
   3. Regarding the security:
         (imran) This can always be taken care by adding checks in
pre-install or post-install scripts for libvirt lxc:
          https://libvirt.org/drvlxc.html#security


code snippet


---
 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>
+<domain type='lxc' xmlns:lxc='
http://libvirt.org/schemas/domain/lxc/1.0'>
+...
+<lxc:namespace>
+  <lxc:sharenet type='netns' value='red'/>
+  <lxc:shareuts type='name' value='container1'/>
+  <lxc:shareipc type='pid' value='12345'/>
+</lxc:namespace>
+</domain>
+</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);

-----------------------
-imran



On Thu, Jun 11, 2015 at 5:47 PM, Michal Privoznik <mprivozn at redhat.com>
wrote:

> On 21.05.2015 19:43, ik.nitk wrote:
> >  This patch tries to add the similar option to libvirt lxc. So to
> inherit namespace from name
> >  container c2.
> >  add this into xml.
> >      <lxc:namespace>
> >          <sharenet type='name' value='c2'/>
> >      </lxc:namespace>
> >
> >  And to inherit namespace from a pid.
> >  add this into xml.
> >      <lxc:namespace>
> >          <sharenet type='pid' value='10245'/>
> >      </lxc:namespace>
> >
> >  And to inherit namespace from a netns.
> >  add this into xml.
> >      <lxc:namespace>
> >          <sharenet type='netns' value='red'/>
> >      </lxc:namespace>
> >
> >  Similar options for ipc/uts.
> >      <shareipc    /> , <shareuts />
> >
> >  The reasong lxc xml namespace is added because this feature is very
> specific to lxc. Therfore wanted to
> >  keep it seperated from actual libvirt xml domain.
> >
> >  -imran
> > ---
>
> The subject line is just too long. Look at git log to see the style we
> use to write commit messages.
>
> >  src/Makefile.am         |   5 +-
> >  src/lxc/lxc_conf.c      |   2 +-
> >  src/lxc/lxc_conf.h      |  23 +++++
> >  src/lxc/lxc_container.c | 191 ++++++++++++++++++++++++++++++++++--
> >  src/lxc/lxc_domain.c    | 254
> +++++++++++++++++++++++++++++++++++++++++++++++-
> >  src/lxc/lxc_domain.h    |   1 +
> >  6 files changed, 463 insertions(+), 13 deletions(-)
>
>
> You are introducing new elements and namespace to the XML. This must
> always go hand in hand with RNG schema adjustment and a test case or two
> under tests/. I NACK every patch that does not comply with this rule.
> But let me review the rest.
>
> >
> > diff --git a/src/Makefile.am b/src/Makefile.am
> > index 579421d..1a78fde 100644
> > --- a/src/Makefile.am
> > +++ b/src/Makefile.am
> > @@ -1293,7 +1293,8 @@ 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) $(FUSE_LIBS)
> > +libvirt_driver_lxc_impl_la_LDFLAGS = libvirt-lxc.la
>
> This won't fly. If you need libvirt-lxc.la to be added, you must put it
> into LIBADD. Otherwise automake will fail to see the dependency tree. It
> happened to me when I was building this with -j5. Although, this won't
> be needed at all IMO, but more on that later.
>
> >  if WITH_BLKID
> >  libvirt_driver_lxc_impl_la_CFLAGS += $(BLKID_CFLAGS)
> >  libvirt_driver_lxc_impl_la_LIBADD += $(BLKID_LIBS)
> > @@ -2652,6 +2653,8 @@ 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..59002e5 100644
> > --- a/src/lxc/lxc_conf.h
> > +++ b/src/lxc/lxc_conf.h
> > @@ -67,6 +67,29 @@ struct _virLXCDriverConfig {
> >      bool securityRequireConfined;
> >  };
> >
> > +
> > +typedef enum {
> > +    VIR_DOMAIN_NAMESPACE_SHARENET = 0,
> > +    VIR_DOMAIN_NAMESPACE_SHAREIPC,
> > +    VIR_DOMAIN_NAMESPACE_SHAREUTS,
> > +    VIR_DOMAIN_NAMESPACE_LAST,
> > +} virDomainNamespace;
> > +
> > +struct ns_info {
> > +    const char *proc_name;
> > +    int clone_flag;
> > +};
> > +
> > +extern const struct ns_info ns_info[VIR_DOMAIN_NAMESPACE_LAST];
> > +
> > +typedef struct _lxcDomainDef lxcDomainDef;
> > +typedef lxcDomainDef *lxcDomainDefPtr;
> > +struct _lxcDomainDef {
> > +    int ns_inherit_fd[VIR_DOMAIN_NAMESPACE_LAST];
> > +    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 9a9ae5c..a9a7ba0 100644
> > --- a/src/lxc/lxc_container.c
> > +++ b/src/lxc/lxc_container.c
> > @@ -25,8 +25,8 @@
> >   */
> >
> >  #include <config.h>
> > -
>
> No, we like the extra space here. config.h has a special status.
>
> >  #include <fcntl.h>
> > +#include <sched.h>
> >  #include <limits.h>
> >  #include <stdlib.h>
> >  #include <stdio.h>
> > @@ -38,7 +38,6 @@
> >  #include <mntent.h>
> >  #include <sys/reboot.h>
> >  #include <linux/reboot.h>
> > -
> >  /* Yes, we want linux private one, for _syscall2() macro */
> >  #include <linux/unistd.h>
> >
> > @@ -99,6 +98,50 @@ VIR_LOG_INIT("lxc.lxc_container");
> >  typedef char lxc_message_t;
> >  #define LXC_CONTINUE_MSG 'c'
> >
>
>
> > +#ifdef __linux__
> > +/*
> > + * Workaround older glibc. While kernel may support the setns
> > + * syscall, the glibc wrapper might not exist. If that's the
> > + * case, use our own.
> > + */
> > +# ifndef __NR_setns
> > +#  if defined(__x86_64__)
> > +#   define __NR_setns 308
> > +#  elif defined(__i386__)
> > +#   define __NR_setns 346
> > +#  elif defined(__arm__)
> > +#   define __NR_setns 375
> > +#  elif defined(__aarch64__)
> > +#   define __NR_setns 375
> > +#  elif defined(__powerpc__)
> > +#   define __NR_setns 350
> > +#  elif defined(__s390__)
> > +#   define __NR_setns 339
> > +#  endif
> > +# endif
> > +
> > +# ifndef HAVE_SETNS
> > +#  if defined(__NR_setns)
> > +#   include <sys/syscall.h>
> > +
> > +static inline int setns(int fd, int nstype)
> > +{
> > +    return syscall(__NR_setns, fd, nstype);
> > +}
> > +#  else /* !__NR_setns */
> > +#   error Please determine the syscall number for setns on your
> architecture
> > +#  endif
> > +# endif
> > +#else /* !__linux__ */
> > +static inline int setns(int fd ATTRIBUTE_UNUSED, int nstype
> ATTRIBUTE_UNUSED)
> > +{
> > +    virReportSystemError(ENOSYS, "%s",
> > +                         _("Namespaces are not supported on this
> platform."));
> > +    return -1;
> > +}
> > +#endif
> > +
> > +
>
> This seems like copied over from util/virprocess.c. I think you can use
> setns() function defined there instead of redefining your own.
>
> >  typedef struct __lxc_child_argv lxc_child_argv_t;
> >  struct __lxc_child_argv {
> >      virDomainDefPtr config;
> > @@ -2233,7 +2276,6 @@ static int lxcContainerChild(void *data)
> >                      vmDef->os.init);
> >          goto cleanup;
> >      }
> > -
>
> I think this empty line is intentional here.
>
> >      /* rename and enable interfaces */
> >      if (lxcContainerRenameAndEnableInterfaces(vmDef,
> >                                                argv->nveths,
> > @@ -2321,6 +2363,99 @@ virArch lxcContainerGetAlt32bitArch(virArch arch)
> >      return VIR_ARCH_NONE;
> >  }
> >
> > +/* Used only for containers,same as the one defined in
> > + * domain_conf.c. But used locally
> > + */
> > +static const struct ns_info 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 void close_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 (access("/proc/self/ns", X_OK)) {
>
> virFileIsExecutable. Although I guess you want tot check if the file
> exists, in which case virFileExists is just enough.
>
> > +        virReportSystemError(errno, "%s",
> > +                             _("Kernel does not support attach;
> preserve_ns ignored"));
> > +        return 0;
>
> So an error is reported, but success is claimed?
>
> > +    }
> > +
> > +    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;
>
> If virAsprintf fails, an error is already reported. But due to 'goto
> error' you overwrite it with (wrong) error message.
>
> > +        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;
> > +    close_ns(ns_fd);
> > +    errno = saved_errno;
> > +    VIR_FREE(path);
> > +    virReportSystemError(errno, _("failed to open '%s'"), path);
>
> Ouch. @path is NULL at this point.
>
> > +    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)
> > +            goto error;
>
> Any reason why the block under 'error' label is not here directly?
>
> > +    }
> > +    return 0;
> > +
> > + error:
> > +    virReportSystemError(errno, _("failed to set namespace '%s'")
> > +                         , ns_info_local[i].proc_name);
> > +    return -1;
> > +}
> > +
> >
> >  /**
> >   * lxcContainerStart:
> > @@ -2346,9 +2481,12 @@ 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 preserve_mask = 0;
> > +    lxcDomainDefPtr lxcDef;
> >      lxc_child_argv_t args = {
> >          .config = def,
> >          .securityDriver = securityDriver,
> > @@ -2368,7 +2506,14 @@ 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_inherit_fd[i] != -1)
> > +           preserve_mask |= ns_info_local[i].clone_flag;
> > +
> > +
> > +
> > +    cflags = CLONE_NEWPID|CLONE_NEWNS|SIGCHLD;
> >
> >      if (userns_required(def)) {
> >          if (userns_supported()) {
> > @@ -2381,10 +2526,36 @@ int lxcContainerStart(virDomainDefPtr def,
> >              return -1;
> >          }
> >      }
> > +    if (!lxcDef || (lxcDef &&
> lxcDef->ns_inherit_fd[VIR_DOMAIN_NAMESPACE_SHARENET] == -1)) {
>
> C language short-cuircuit conditions evaluation. Therefore, if lxcDef is
> NULL, the first part of the condition will direct control into the if()
> body. Therefore there's no need to check:
>
> if (!a || (a && a->something));
>
> It's equivallent to:
>
> if (!a || a->something);
>
> > +        if (lxcNeedNetworkNamespace(def)) {
> > +            VIR_DEBUG("Enable network namespaces");
> > +            cflags |= CLONE_NEWNET;
> > +        }
> > +    } else {
> > +        VIR_DEBUG("Inheriting a net namespace");
> > +    }
> >
> > -    if (lxcNeedNetworkNamespace(def)) {
> > -        VIR_DEBUG("Enable network namespaces");
> > -        cflags |= CLONE_NEWNET;
> > +    if (!lxcDef || (lxcDef &&
> lxcDef->ns_inherit_fd[VIR_DOMAIN_NAMESPACE_SHAREIPC] == -1)) {
> > +        cflags |= CLONE_NEWIPC;
> > +    } else {
> > +        VIR_DEBUG("Inheriting an IPC namespace");
> > +    }
> > +
> > +    if (!lxcDef || (lxcDef &&
> lxcDef->ns_inherit_fd[VIR_DOMAIN_NAMESPACE_SHAREUTS] == -1)) {
> > +        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 (lxcDef && lxcAttach_ns(lxcDef->ns_inherit_fd) < 0) {
> > +        virReportError(VIR_ERR_SYSTEM_ERROR, "%s",
> > +                       _("failed to attach the namespace"));
> > +        return -1;
> >      }
> >
> >      VIR_DEBUG("Cloning container init process");
> > @@ -2397,6 +2568,10 @@ 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"));
> > +    }
> >
> >      return pid;
> >  }
> > diff --git a/src/lxc/lxc_domain.c b/src/lxc/lxc_domain.c
> > index c2180cb..6e4a19a 100644
> > --- a/src/lxc/lxc_domain.c
> > +++ b/src/lxc/lxc_domain.c
> > @@ -20,14 +20,18 @@
> >   */
> >
> >  #include <config.h>
> > -
> >  #include "lxc_domain.h"
> > -
>
> I've raised this already.
>
> >  #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 +45,251 @@ static void *virLXCDomainObjPrivateAlloc(void)
> >      return priv;
> >  }
> >
> > +
> > +static int open_ns(const char *nnsname_pid, const char *ns_proc_name)
> > +{
> > +    int fd = -1;
> > +    virDomainPtr dom = NULL;
> > +    virConnectPtr conn = NULL;
> > +    pid_t pid;
> > +    int nfdlist;
> > +    int *fdlist;
> > +    char *path = NULL;
> > +    char *eptr;
> > +    pid = strtol(nnsname_pid, &eptr, 10);
> > +    if (*eptr != '\0' || pid < 1) {
> > +        /* check if the domain is running, then set the namespaces
> > +        * to that container
> > +        */
> > +        size_t i = 0;
> > +        const char *ns[] = { "user", "ipc", "uts", "net", "pid", "mnt"
> };
> > +        conn = virConnectOpen("lxc:///");
> > +        if (!conn)
> > +          goto cleanup;
> > +        dom = virDomainLookupByName(conn, nnsname_pid);
> > +        if (!dom)
> > +           goto cleanup;
> > +        if ((nfdlist = virDomainLxcOpenNamespace(dom, &fdlist, 0)) < 0)
> > +           goto cleanup;
> > +         /* Internally above function calls  virProcessGetNamespaces
> > +          *  function which opens ns
> > +          * in the order { "user", "ipc", "uts", "net", "pid", "mnt" }
> > +          */
> > +        for (i = 0; i < ARRAY_CARDINALITY(ns); i++) {
> > +            if (STREQ(ns[i], ns_proc_name)) {
> > +              fd = fdlist[i];
> > +              break;
> > +           }
> > +        }
> > +        if (nfdlist > 0)
>
> No, please no. If you read the virDomainLxcOpenNamespace() description,
> you'll notice that not only we must free the array, but also close all
> the file descriptors. You'll leak all of them but one. That's not
> acceptable.
>
> > +            VIR_FREE(fdlist);
> > +     } else {
> > +        if (virAsprintf(&path, "/proc/%d/ns/%s", pid, ns_proc_name) < 0)
> > +           goto cleanup;
> > +        fd = open(path, O_RDONLY);
> > +     }
> > +cleanup:
> > +     if (dom)
> > +       virDomainFree(dom);
> > +     VIR_FREE(path);
> > +     (fd < 0)? VIR_ERROR(
> > +         _("failed to open ns %s"), nnsname_pid):
> > +     VIR_DEBUG("OPENED NAMESPACE : fd %d\n", fd);
> > +     return fd;
> > +}
>
>
> This is the part I'm having trouble with. IIUC, this code is run at the
> time of domain XML parsing. The other domain I'm referring to may still
> not be running. How am I going to set the same namespace then?
>
> I think this should be done at domain startup (and fail, if the
> referenced PID or domain does not exist). Having said that, when doing
> this in driver, that's starting a namespace, you have access to all
> internal variables and functions. Then you don't need to open a dummy
> connection just to look up the referenced domain. You can use an
> internal function which does not require virConnection object. Moreover,
> you will not need the Makefile change.
>
> > +
> > +
> > +/* Used only for containers */
> > +const struct ns_info ns_info[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}
> > +};
> > +
> > +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++) {
> > +       if (lxcDef->ns_inherit_fd[j] > 0) {
> > +          VIR_FREE(lxcDef->ns_type);
> > +          VIR_FREE(lxcDef->ns_val);
> > +#if 0
> > +          if (VIR_CLOSE(lxcDef->ns_inherit_fd[j]) < 0)
> > +              virReportSystemError(errno, "%s", _("failed to close
> file"));
> > +#endif
> > +       }
> > +    }
> > +    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;
> > +    pid_t fd = -1;
> > +
> > +    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_inherit_fd[i] = -1;
> > +        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;
> > +                /*netns option is only for
> VIR_DOMAIN_NAMESPACE_SHARENET*/
> > +                if (STREQ("netns",
> lxcDef->ns_type[VIR_DOMAIN_NAMESPACE_SHARENET])) {
>
> I don't think this is safe. ns_type[SHARENET] can be NULL at this point.
> STREQ_NULLABLE is more apropriate.
>
> > +                    char *path = NULL;
> > +                    if (virAsprintf(&path, "/var/run/netns/%s", tmp) <
> 0)
> > +                        goto error;
> > +                    fd = open(path, O_RDONLY);
> > +                    VIR_FREE(path);
>
> What if open() fails?
>
> > +                } else {
> > +                    fd = open_ns(tmp, ns_info[feature].proc_name);
> > +                    if (fd < 0) {
> > +                        virReportError(VIR_ERR_XML_ERROR,
> > +                                       _("unable to open %s namespace
> for "
> > +                                         "namespace feature '%s'"), tmp,
> > +                                       nodes[i]->name);
> > +                        goto error;
> > +                    }
> > +                }
> > +                lxcDef->ns_inherit_fd[feature] = fd;
> > +            }
> > +            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_inherit_fd[j] > 0) {
> > +                    virBufferAsprintf(buf, "<%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;
> > @@ -73,7 +322,6 @@ static int
> virLXCDomainObjPrivateXMLParse(xmlXPathContextPtr ctxt, void *data)
> >      } else {
> >          priv->initpid = thepid;
> >      }
> > -
> >      return 0;
> >  }
>
> Yet again, why is this change needed?
>
> >
> > 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;
> >
> >
>
> Frankly, I don't have good feeling about this. But maybe I'm missing
> some rationale behind. What's the usecase? You want two containers to
> share the same network namespace, or?
> I view two or more containers in the same namespace as a security flaw,
> not feature. With this mind set maybe I'm not the right person to review
> the patches. But hey, I'm open for persuasion :)
>
> Michal
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://listman.redhat.com/archives/libvir-list/attachments/20150701/016b3b32/attachment-0001.htm>


More information about the libvir-list mailing list