4:07 p.m.
This set moves the cgroup creation before that of the container process,
thus ensuring that it is put in the cgroup as well. As a result, I noticed
that we need to allow device access to /dev/pts/*, and thus added a cgroup
mechanism to allow a whole major device type. The LXC driver is made to
allow major type 136 as a result.
Note that this doesn't seem to do much to really restrict the container.
While it does prevent them from opening devices other than what are allowed,
the container can still mount (or access) the cgroup filesystem and move
itself out of its own group and into the unrestricted root. Further,
it can just add whitelist entries for the devices it wants to gain access.
I tested code to restrict the devices in the per-driver cgroup, but that
appears to have no effect, because from within the container, I can still
add "b 8:* rwm" to my group's devices.allow and subsequently access SCSI
disks. Even still, this patch set is crucial for proper cgroup membership of
the container children.
4:07 p.m.
New subject: [libvirt] [PATCH 1 of 2] Add virCgroupAllowMajor()
This interface provides a way to allow an entire major device type
diff -r 388beff59a32 -r 48a9209668ab src/cgroup.c
--- a/src/cgroup.c Wed Oct 15 10:33:01 2008 +0000
+++ b/src/cgroup.c Thu Oct 16 14:01:13 2008 -0700
@@ -761,6 +761,36 @@
return rc;
}
+/**
+ * virCgroupAllowDeviceMajor:
+ *
+ * @group: The cgroup to allow an entire device major type for
+ * @type: The device type (i.e., 'c' or 'b')
+ * @major: The major number of the device type
+ *
+ * Returns: 0 on success
+ */
+int virCgroupAllowDeviceMajor(virCgroupPtr group,
+ char type,
+ int major)
+{
+ int rc;
+ char *devstr = NULL;
+
+ if (asprintf(&devstr, "%c %i:* rwm", type, major) == -1) {
+ rc = -ENOMEM;
+ goto out;
+ }
+
+ rc = virCgroupSetValueStr(group,
+ "devices.allow",
+ devstr);
+ out:
+ VIR_FREE(devstr);
+
+ return rc;
+}
+
int virCgroupSetCpuShares(virCgroupPtr group, unsigned long shares)
{
return virCgroupSetValueU64(group, "cpu.shares", (uint64_t)shares);
diff -r 388beff59a32 -r 48a9209668ab src/cgroup.h
--- a/src/cgroup.h Wed Oct 15 10:33:01 2008 +0000
+++ b/src/cgroup.h Thu Oct 16 14:01:13 2008 -0700
@@ -35,6 +35,9 @@
char type,
int major,
int minor);
+int virCgroupAllowDeviceMajor(virCgroupPtr group,
+ char type,
+ int major);
int virCgroupSetCpuShares(virCgroupPtr group, unsigned long shares);
int virCgroupGetCpuShares(virCgroupPtr group, unsigned long *shares);
10:47 a.m.
New subject: [libvirt] [PATCH 1 of 2] Add virCgroupAllowMajor()
On Thu, Oct 16, 2008 at 02:07:56PM -0700, Dan Smith wrote:
This interface provides a way to allow an entire major device type
ACK.
Daniel
--
|: Red Hat, Engineering, London -o- http://people.redhat.com/berrange/ :|
|: http://libvirt.org -o- http://virt-manager.org -o- http://ovirt.org :|
|: http://autobuild.org -o- http://search.cpan.org/~danberr/ :|
|: GnuPG: 7D3B9505 -o- F3C9 553F A1DA 4AC2 5648 23C1 B3DF F742 7D3B 9505 :|
11:15 a.m.
New subject: [libvirt] [PATCH 1 of 2] Add virCgroupAllowMajor()
On Thu, Oct 16, 2008 at 02:07:56PM -0700, Dan Smith wrote:
This interface provides a way to allow an entire major device type
Looks uncontroversial, +1
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/
4:07 p.m.
New subject: [libvirt] [PATCH 2 of 2] [LXC] Create and enter the cgroup before starting container process
Without this, our container child doesn't actually end up in the cgroup,
and thus runs unrestricted. Note that this does not address the container's
ability to mount cgroup and move itself into the parent namespace.
While making this change, it became clear that we need to allow access to
the entire range of pty devices for the container console to work. This
patch adds that logic as well.
diff -r 48a9209668ab -r 4babf77ec518 src/lxc_container.h
--- a/src/lxc_container.h Thu Oct 16 14:01:13 2008 -0700
+++ b/src/lxc_container.h Thu Oct 16 14:01:13 2008 -0700
@@ -40,6 +40,8 @@
#define LXC_DEV_MAJ_TTY 5
#define LXC_DEV_MIN_CONSOLE 1
+#define LXC_DEV_MAJ_PTY 136
+
int lxcContainerSendContinue(int control);
int lxcContainerStart(virDomainDefPtr def,
diff -r 48a9209668ab -r 4babf77ec518 src/lxc_controller.c
--- a/src/lxc_controller.c Thu Oct 16 14:01:13 2008 -0700
+++ b/src/lxc_controller.c Thu Oct 16 14:01:13 2008 -0700
@@ -102,6 +102,10 @@
if (rc != 0)
goto out;
}
+
+ rc = virCgroupAllowDeviceMajor(cgroup, 'c', LXC_DEV_MAJ_PTY);
+ if (rc != 0)
+ goto out;
rc = virCgroupAddTask(cgroup, getpid());
out:
@@ -449,6 +453,9 @@
goto cleanup;
}
+ if (lxcSetContainerResources(def) < 0)
+ goto cleanup;
+
if ((container = lxcContainerStart(def,
nveths,
veths,
@@ -459,9 +466,6 @@
control[1] = -1;
if (lxcControllerMoveInterfaces(nveths, veths, container) < 0)
- goto cleanup;
-
- if (lxcSetContainerResources(def) < 0)
goto cleanup;
if (lxcContainerSendContinue(control[0]) < 0)
10:48 a.m.
New subject: [libvirt] [PATCH 2 of 2] [LXC] Create and enter the cgroup before starting container process
On Thu, Oct 16, 2008 at 02:07:57PM -0700, Dan Smith wrote:
Without this, our container child doesn't actually end up in the
cgroup,
and thus runs unrestricted. Note that this does not address the container's
ability to mount cgroup and move itself into the parent namespace.
While making this change, it became clear that we need to allow access to
the entire range of pty devices for the container console to work. This
patch adds that logic as well.
Yep, we also need the kernel guys to finish PTS namespace virtualization
so we can actually make /dev/pts private to the container :-)
ACK to this patch.
Daniel
--
|: Red Hat, Engineering, London -o- http://people.redhat.com/berrange/ :|
|: http://libvirt.org -o- http://virt-manager.org -o- http://ovirt.org :|
|: http://autobuild.org -o- http://search.cpan.org/~danberr/ :|
|: GnuPG: 7D3B9505 -o- F3C9 553F A1DA 4AC2 5648 23C1 B3DF F742 7D3B 9505 :|
11:17 a.m.
New subject: [libvirt] [PATCH 2 of 2] [LXC] Create and enter the cgroup before starting container process
On Thu, Oct 16, 2008 at 02:07:57PM -0700, Dan Smith wrote:
Without this, our container child doesn't actually end up in the
cgroup,
and thus runs unrestricted. Note that this does not address the container's
ability to mount cgroup and move itself into the parent namespace.
Okay this moves the initialization earlier, makes sense,
+1
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/
9:58 a.m.
DS> This set moves the cgroup creation before that of the container
DS> process, thus ensuring that it is put in the cgroup as well. As a
DS> result, I noticed that we need to allow device access to
DS> /dev/pts/*, and thus added a cgroup mechanism to allow a whole
DS> major device type. The LXC driver is made to allow major type 136
DS> as a result.
Were there any comments on this set? I think it would be nice to get
it into the tree sooner than later so we at least have resource
controls on containers :)
--
Dan Smith
IBM Linux Technology Center
Open Hypervisor Team
email: danms(a)us.ibm.com
11:17 a.m.
On Tue, Oct 21, 2008 at 07:58:29AM -0700, Dan Smith wrote:
DS> This set moves the cgroup creation before that of the
container
DS> process, thus ensuring that it is put in the cgroup as well. As a
DS> result, I noticed that we need to allow device access to
DS> /dev/pts/*, and thus added a cgroup mechanism to allow a whole
DS> major device type. The LXC driver is made to allow major type 136
DS> as a result.
Were there any comments on this set? I think it would be nice to get
it into the tree sooner than later so we at least have resource
controls on containers :)
sorry for the delay, please push !
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/
12:58 p.m.
DV> sorry for the delay, please push !
Done. Thanks!
--
Dan Smith
IBM Linux Technology Center
Open Hypervisor Team
email: danms(a)us.ibm.com
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9 comments
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participants (3)
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Dan Smith -
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Daniel Veillard