[libvirt] [PATCH] lxc: make the pivot_root more robust.
by Serge E. Hallyn
libvirt/lxc is broken on F11. The pivot_root() call returns
-EINVAL. The below is one way we can fix it. I'm also sending
another patch which takes the simpler approach of using chroot.
However, chroot is trivially escapable (see for instance
http://www.linuxsecurity.com/content/view/117632/49/). I don't
know whether the typical libvirt user would care. If so, then
the below patch is probably the way to go.
>From 26cac415771a2d9712af0e1ce60a0bcb41b44665 Mon Sep 17 00:00:00 2001
From: root <root(a)localhost.localdomain>
Date: Sat, 4 Apr 2009 22:49:20 -0400
Subject: [PATCH 1/1] lxc: make the pivot_root more robust.
The libvirt lxc driver uses pivot_root instead of chroot, because
the latter is trivially escapable. However, the pivot_root(2)
system call can fail for several subtle reasons. Depending upon
your distro init sequence you may get lucky and have the old
recipe work, but on a Fedora 11 standard install, for instance,
it will fail.
Do a few more steps to make pivot_root hopefully always
succeed. We mark / as MS_PRIVATE, create an empty tmpfs,
and bind-mount the container root onto /new in that fs.
In this way, we ensure two reasons for pivot_root to fail -
namely old_root->parent being MS_SHARED and old_root and
new_root being on the same fs - won't happen.
Signed-off-by: Serge Hallyn <serue(a)us.ibm.com>
---
src/lxc_container.c | 108 ++++++++++++++++++++++++++++++++++++++++-----------
1 files changed, 85 insertions(+), 23 deletions(-)
diff --git a/src/lxc_container.c b/src/lxc_container.c
index 3f17b8d..d3959f6 100644
--- a/src/lxc_container.c
+++ b/src/lxc_container.c
@@ -264,50 +264,113 @@ static int lxcContainerChildMountSort(const void *a, const void *b)
return strcmp(*sb, *sa);
}
+#ifndef MS_REC
+#define MS_REC 16384
+#endif
+
+#ifndef MNT_DETACH
+#define MNT_DETACH 0x00000002
+#endif
+
+#ifndef MS_PRIVATE
+#define MS_PRIVATE 1<<18
+#endif
+
static int lxcContainerPivotRoot(virDomainFSDefPtr root)
{
int rc;
- char *oldroot;
+ char *oldroot = NULL, *newroot = NULL;
- /* First step is to ensure the new root itself is
- a mount point */
- if (mount(root->src, root->src, NULL, MS_BIND, NULL) < 0) {
- virReportSystemError(NULL, errno,
- _("failed to bind new root %s"),
- root->src);
- return -1;
+ /* root->parent must be private, so make / private. */
+ if (mount("", "/", NULL, MS_PRIVATE|MS_REC, NULL) < 0) {
+ virReportSystemError(NULL, errno, "%s",
+ _("failed to make root private"));
+ goto err;
}
if (virAsprintf(&oldroot, "%s/.oldroot", root->src) < 0) {
virReportOOMError(NULL);
- return -1;
+ goto err;
}
if ((rc = virFileMakePath(oldroot)) < 0) {
virReportSystemError(NULL, rc,
_("failed to create %s"),
oldroot);
- VIR_FREE(oldroot);
- return -1;
+ goto err;
+ }
+
+ /* Create a tmpfs root since old and new roots must be
+ * on separate filesystems */
+ if (mount("", oldroot, "tmpfs", 0, NULL) < 0) {
+ virReportSystemError(NULL, errno,
+ _("failed to mount empty tmpfs at %s"),
+ oldroot);
+ goto err;
+ }
+
+ /* Create a directory called 'new' in tmpfs */
+ if (virAsprintf(&newroot, "%s/new", oldroot) < 0) {
+ virReportOOMError(NULL);
+ goto err;
+ }
+
+ if ((rc = virFileMakePath(newroot)) < 0) {
+ virReportSystemError(NULL, rc,
+ _("failed to create %s"),
+ newroot);
+ goto err;
+ }
+
+ /* ... and mount our root onto it */
+ if (mount(root->src, newroot, NULL, MS_BIND|MS_REC, NULL) < 0) {
+ virReportSystemError(NULL, errno,
+ _("failed to bind new root %s into tmpfs"),
+ root->src);
+ goto err;
+ }
+
+ /* Now we chroot into the tmpfs, then pivot into the
+ * root->src bind-mounted onto '/new' */
+ if (chroot(oldroot) < 0) {
+ virReportSystemError(NULL, errno, "%s",
+ _("failed to chroot into tmpfs"));
+ goto err;
+ }
+
+ if (chdir("/new") < 0) {
+ virReportSystemError(NULL, errno, "%s",
+ _("failed to chdir into /new on tmpfs"));
+ goto err;
}
/* The old root directory will live at /.oldroot after
* this and will soon be unmounted completely */
- if (pivot_root(root->src, oldroot) < 0) {
- virReportSystemError(NULL, errno,
- _("failed to pivot root %s to %s"),
- oldroot, root->src);
- VIR_FREE(oldroot);
- return -1;
+ if (pivot_root(".", ".oldroot") < 0) {
+ virReportSystemError(NULL, errno, "%s",
+ _("failed to pivot root"));
+ goto err;
}
- VIR_FREE(oldroot);
/* CWD is undefined after pivot_root, so go to / */
- if (chdir("/") < 0) {
- return -1;
+ if (chdir("/") < 0)
+ goto err;
+
+ if (umount2(".oldroot", MNT_DETACH) < 0) {
+ virReportSystemError(NULL, errno, "%s",
+ _("failed to lazily unmount old root"));
+ goto err;
}
+ VIR_FREE(oldroot);
+ VIR_FREE(newroot);
+
return 0;
+
+err:
+ if (oldroot) VIR_FREE(oldroot);
+ if (newroot) VIR_FREE(newroot);
+ return -1;
}
static int lxcContainerPopulateDevices(void)
@@ -349,10 +412,9 @@ static int lxcContainerPopulateDevices(void)
_("cannot create /dev/pts"));
return -1;
}
- if (mount("/.oldroot/dev/pts", "/dev/pts", NULL,
- MS_MOVE, NULL) < 0) {
+ if (mount("devpts", "/dev/pts", "devpts", 0, NULL) < 0) {
virReportSystemError(NULL, errno, "%s",
- _("failed to move /dev/pts into container"));
+ _("failed to mount /dev/pts in container"));
return -1;
}
--
1.6.2
16 years
[libvirt] [PATCH] lxc: use chroot instead of pivot_root
by Serge E. Hallyn
This is an alternative to the pivot_root patch which I just
sent. It has the advantage of being much simpler. It also
won't have a problem with the container's / being a read-only
mount. It has the disadvantage, of course, of being escapable.
>From a91bca7f60f27e8fbdb4e3bacf3232a6cbb630d3 Mon Sep 17 00:00:00 2001
From: root <root(a)localhost.localdomain>
Date: Fri, 3 Apr 2009 23:35:24 -0400
Subject: [PATCH 1/1] lxc: use chroot instead of pivot_root
pivot_root is too fragile. For instance, if the container's
/ is read-only, we can't create .oldroot. Maybe we're happy
telling users that if they can't create .oldroot at container
create time, then they must make sure it exists ahead of time.
Or, maybe we're ok with chroot being escapable, and should
just go this simple route.
Signed-off-by: Serge Hallyn <serue(a)us.ibm.com>
---
src/lxc_container.c | 75 +++++++++++++--------------------------------------
1 files changed, 19 insertions(+), 56 deletions(-)
diff --git a/src/lxc_container.c b/src/lxc_container.c
index 3f17b8d..142ed4d 100644
--- a/src/lxc_container.c
+++ b/src/lxc_container.c
@@ -264,52 +264,6 @@ static int lxcContainerChildMountSort(const void *a, const void *b)
return strcmp(*sb, *sa);
}
-static int lxcContainerPivotRoot(virDomainFSDefPtr root)
-{
- int rc;
- char *oldroot;
-
- /* First step is to ensure the new root itself is
- a mount point */
- if (mount(root->src, root->src, NULL, MS_BIND, NULL) < 0) {
- virReportSystemError(NULL, errno,
- _("failed to bind new root %s"),
- root->src);
- return -1;
- }
-
- if (virAsprintf(&oldroot, "%s/.oldroot", root->src) < 0) {
- virReportOOMError(NULL);
- return -1;
- }
-
- if ((rc = virFileMakePath(oldroot)) < 0) {
- virReportSystemError(NULL, rc,
- _("failed to create %s"),
- oldroot);
- VIR_FREE(oldroot);
- return -1;
- }
-
- /* The old root directory will live at /.oldroot after
- * this and will soon be unmounted completely */
- if (pivot_root(root->src, oldroot) < 0) {
- virReportSystemError(NULL, errno,
- _("failed to pivot root %s to %s"),
- oldroot, root->src);
- VIR_FREE(oldroot);
- return -1;
- }
- VIR_FREE(oldroot);
-
- /* CWD is undefined after pivot_root, so go to / */
- if (chdir("/") < 0) {
- return -1;
- }
-
- return 0;
-}
-
static int lxcContainerPopulateDevices(void)
{
int i;
@@ -349,10 +303,9 @@ static int lxcContainerPopulateDevices(void)
_("cannot create /dev/pts"));
return -1;
}
- if (mount("/.oldroot/dev/pts", "/dev/pts", NULL,
- MS_MOVE, NULL) < 0) {
+ if (mount("devpts", "/dev/pts", "devpts", 0, NULL) < 0) {
virReportSystemError(NULL, errno, "%s",
- _("failed to move /dev/pts into container"));
+ _("failed to mount /dev/pts in container"));
return -1;
}
@@ -461,15 +414,25 @@ static int lxcContainerUnmountOldFS(void)
}
-/* Got a FS mapped to /, we're going the pivot_root
- * approach to do a better-chroot-than-chroot
- * this is based on this thread http://lkml.org/lkml/2008/3/5/29
- */
-static int lxcContainerSetupPivotRoot(virDomainDefPtr vmDef,
+/* Got a FS mapped to /, now chroot.
+ * pivot_root would work, but requires too much hand-holding
+ * (especially, old_root->parent must not be shared) */
+static int lxcContainerSetupChroot(virDomainDefPtr vmDef,
virDomainFSDefPtr root)
{
- if (lxcContainerPivotRoot(root) < 0)
+ if (chdir(root->src) < 0) {
+ virReportSystemError(NULL, errno,
+ _("failed to chdir to %s"),
+ root->src);
+ return -1;
+ }
+
+ if (chroot(root->src) < 0) {
+ virReportSystemError(NULL, errno,
+ _("failed to chroot to %s"),
+ root->src);
return -1;
+ }
if (virFileMakePath("/proc") < 0 ||
mount("none", "/proc", "proc", 0, NULL) < 0) {
@@ -537,7 +500,7 @@ static int lxcContainerSetupMounts(virDomainDefPtr vmDef)
}
if (root)
- return lxcContainerSetupPivotRoot(vmDef, root);
+ return lxcContainerSetupChroot(vmDef, root);
else
return lxcContainerSetupExtraMounts(vmDef);
}
--
1.6.2
16 years
[libvirt] VM cpuTime discrepancy
by Zvi Dubitzky
The cpuTime of a VM reported by kvm72 is ok (real seconds ) while
that reported by kvm-84 is not.
Are you aware of this . Did you talk to kvm and was it fixed in latest
kvm releases since 84 ?
I access cpuTime via libvirt . (same version in both cases) .
thanks
Zvi Dubitzky
Virtualization and System Architecture Email:dubi@il.ibm.com
IBM Haifa Research Laboratory Phone: +972-4-8296182
Haifa, 31905, ISRAEL
16 years
[libvirt] win32
by Brecht Sanders
Hi,
Is there any way to compile libvirt with xen some support without
depending on libxenstore?
The reason I ask is that libxen can be built on Windows, but libxenstore
seems to depend on the linux kernel, so I doubt it can be built for Windows.
Regards
Brecht Sanders
16 years
[libvirt] [PATCH] Openvz: how to use a nondefault config
by Anton Protopopov
2009/4/2 Daniel P. Berrange <berrange(a)redhat.com>
> On Thu, Apr 02, 2009 at 06:36:15PM +0400, Evgeniy Sokolov wrote:
> >
> > Config /etc/vz/conf/ve-XXX.conf-sample define there are many parameters
> > like memory, CPU etc. This parameters are not properties of
> <filesystem>.
> >
> > Daniel, usage of pre-defined configs in really usefull. Can we create
> > additional tag inside <domain></domain>?
>
> The trouble with this is that given the XML config of a guest, you can
> no longer determine what its configuration is, because a large amount
> of configuration is hidden in this opaque 'template'.
And in kvm/qemu case there is a lot of hidden information too :)
In OpenVZ case we don't loose any info (see below).
>
> If we're to support templates, I think we need to make them first class
> objects, so you can query what templates exist, and see their associated
> config settings.
>
> eg, expose a simple API
>
> virDomainTemplatePtr;
>
> int virConnectListDomainTemplates(virConnectPtr conn, const char
> **names);
> virDomainTemplatePtr virDomainTemplateLookupbyName(virConnectPtr con,
> const char *name)
> char *virDomainTemplateGetXMLDesc(virDomainTemplatePtr tmpl);
> virDomainTemplatePtr virDomainTemplateDefineXML(virConnectPtr conn, const
> char *xml)
> int virDomainTemplateUndefine(virDomainTemplatePtr tmpl);
> int virDomainTemplateFree(virDomainTemplatePtr tmpl);
>
>
> Then, we could either include a <template>$NAME</template> parameter in
> the XML for a guest. Or have an alternate API for creating guests
>
> virDomainCreateXMLWithTemplate(virConnectPtr conn,
> const char *xmlDesc,
> const char *template)
>
> It depends whether we'd want to track the template <-> guest association
> forever, or just use it once to fill-in the guest XML and then forget
> about the template after that.
It doesn't matter in OpenVZ case: template (or, "config", in openvz
terminology) is used only
once, when container is creating. But then per-container "copy" is created,
and it is already used by libvirt to keep information about container.
Per-container
OpenVZ config keeps the name of the original config (in ORIGIN_SAMPLE
variable).
Is there need for "Template API" in case of other hypervisors?
16 years
[libvirt] Planning and schedule
by Daniel Veillard
Trying to keep up the promises from last week:
- so 0.6.2 is released and out
- I still plan for a new release 0.6.3 around Fri 24 April
- which mean we should have some kind of feature commit freeze
around the 17th April
- and the week 20 - 24 focusing mostly on bug fixes
Plannned so far for 0.6.3 are:
- API for physical host interface
- the VirtualBox driver if in shape and in time
but that's not an exhaustive list and there is a couple of drivers
submitted I need to look at (OpenNebula for example).
And I will provide an update next Friday,
Daniel
--
Daniel Veillard | libxml Gnome XML XSLT toolkit http://xmlsoft.org/
daniel(a)veillard.com | Rpmfind RPM search engine http://rpmfind.net/
http://veillard.com/ | virtualization library http://libvirt.org/
16 years
[libvirt] pypxeboot - libvirt
by Gian Mario
Hi to all,
Can anyone tell me on which version libvirt start to support pypxeboot?
tnks so much.
GMario
16 years
[libvirt] freecell gives out bytes instead of kilobytes
by Gerrit Slomma
The virsh-command freecell hands out bytes but affixes those with kB.
The error ist found in virsh.c on line 1663 and following.
I have corrected this and altered the output to the method i chose for
virt-manager - in the days of 96 GB per socket (Nehalem-EP) no one cares
even about a fraction of a Megabyte.
--- a/src/virsh.c 2009-04-02 17:45:50.000000000 +0200
+++ b/src/virsh.c 2009-04-02 23:35:54.000000000 +0200
@@ -1661,10 +1661,23 @@
}
if (cell == -1)
- vshPrint(ctl, "%s: %llu kB\n", _("Total"), memory);
+ if (memory < 10*1024*1204*1024)
+ {
+ vshPrint(ctl, "%s: %.0f MB\n", _("Total"),
(float)memory/1024/1024);
+ }
+ else
+ {
+ vshPrint(ctl, "%s: %.2f GB\n", _("Total"),
(float)memory/1024/1024/1024);
+ }
else
- vshPrint(ctl, "%d: %llu kB\n", cell, memory);
-
+ if (memory < 10*1024*1204*1024)
+ {
+ vshPrint(ctl, "%d: %.0f MB\n", cell,
(float)memory/1024/1024);
+ }
+ else
+ {
+ vshPrint(ctl, "%d: %.2f GB\n", cell,
(float)memory/1024/1024/1024);
+ }
return TRUE;
}
eg:
rr016# virsh freecell; free -m
0: 24 MB
total used free shared buffers cached
Mem: 3884 3859 24 0 60 1306
-/+ buffers/cache: 2492 1392
Swap: 2047 248 1798
rr017# virsh freecell; free -m
0: 1490 MB
total used free shared buffers cached
Mem: 2991 1501 1489 0 100 1283
-/+ buffers/cache: 117 2873
Swap: 2047 0 2047
rr019# virsh freecell; free -m
0: 1616 MB
total used free shared buffers cached
Mem: 3952 2337 1615 0 5 1209
-/+ buffers/cache: 1121 2831
Swap: 2047 0 2047
Is this okay with you? Or just the fix for the output removing the
kB-suffix.
16 years
[libvirt] [PATCH] Don't squash file format on volume refresh
by Cole Robinson
A while back, code was added to
storage_backend.c:virStorageBackendUpdateVolTargetInfoFD to try to
determine the volume format for iscsi volumes. Unfortunately this
function is also called for refreshing file volumes, which has the
effect of setting the format as 'raw' whenever a volume is refreshed
(ex. after calling virsh vol-info).
The attached patch moves the offending code into a wrapper function in
the scsi driver. I haven't played with the scsi support yet so this is
untested though it's largely code movement.
Thanks,
Cole
16 years
