* [PATCH] tools: Restrict configuration of qemu processes
@ 2016-03-15 1:08 Jim Fehlig
2016-03-15 1:14 ` Jim Fehlig
2016-03-24 13:53 ` Ian Jackson
0 siblings, 2 replies; 7+ messages in thread
From: Jim Fehlig @ 2016-03-15 1:08 UTC (permalink / raw)
To: xen-devel; +Cc: Jim Fehlig
Commit 6ef823fd added '-nodefaults' to the qemu args created by
libxl, which is a good step in restricting qemu's default
configuration. This change takes another step by adding
-no-user-config, which ignores any user-provided config files in
sysconfdir. Together, -nodefaults and -no-user-config allow Xen
to avoid unkown and uncontrolled qemu configuration.
Both options are also added to the qemu invocation in the
xen-qemu-dom0-disk-backend systemd service file.
Signed-off-by: Jim Fehlig <jfehlig@suse.com>
---
tools/hotplug/Linux/systemd/xen-qemu-dom0-disk-backend.service.in | 1 +
tools/libxl/libxl_dm.c | 6 ++++++
2 files changed, 7 insertions(+)
diff --git a/tools/hotplug/Linux/systemd/xen-qemu-dom0-disk-backend.service.in b/tools/hotplug/Linux/systemd/xen-qemu-dom0-disk-backend.service.in
index acf61a8..f56775b 100644
--- a/tools/hotplug/Linux/systemd/xen-qemu-dom0-disk-backend.service.in
+++ b/tools/hotplug/Linux/systemd/xen-qemu-dom0-disk-backend.service.in
@@ -14,6 +14,7 @@ ExecStartPre=/bin/mkdir -p @XEN_RUN_DIR@
ExecStart=@qemu_xen_systemd@ -xen-domid 0 \
-xen-attach -name dom0 -nographic -M xenpv -daemonize \
-monitor /dev/null -serial /dev/null -parallel /dev/null \
+ -nodefaults -no-user-config \
-pidfile @XEN_RUN_DIR@/qemu-dom0.pid
[Install]
diff --git a/tools/libxl/libxl_dm.c b/tools/libxl/libxl_dm.c
index 4aca38e..cfda24c 100644
--- a/tools/libxl/libxl_dm.c
+++ b/tools/libxl/libxl_dm.c
@@ -828,6 +828,12 @@ static int libxl__build_device_model_args_new(libxl__gc *gc,
*/
flexarray_append(dm_args, "-nodefaults");
+ /*
+ * Do not use any of the user-provided config files in sysconfdir,
+ * avoiding unkown and uncontrolled configuration.
+ */
+ flexarray_append(dm_args, "-no-user-config");
+
if (b_info->type == LIBXL_DOMAIN_TYPE_PV) {
flexarray_append(dm_args, "-xen-attach");
}
--
2.1.4
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^ permalink raw reply related [flat|nested] 7+ messages in thread
* Re: [PATCH] tools: Restrict configuration of qemu processes
2016-03-15 1:08 [PATCH] tools: Restrict configuration of qemu processes Jim Fehlig
@ 2016-03-15 1:14 ` Jim Fehlig
2016-03-15 12:28 ` Wei Liu
2016-03-24 13:53 ` Ian Jackson
1 sibling, 1 reply; 7+ messages in thread
From: Jim Fehlig @ 2016-03-15 1:14 UTC (permalink / raw)
To: xen-devel; +Cc: Ian Jackson, Wei Liu, Stefano Stabellini
Opps, forgot to cc the tools maintainers, sorry. I can resend if needed.
Regards,
Jim
On 03/14/2016 07:08 PM, Jim Fehlig wrote:
> Commit 6ef823fd added '-nodefaults' to the qemu args created by
> libxl, which is a good step in restricting qemu's default
> configuration. This change takes another step by adding
> -no-user-config, which ignores any user-provided config files in
> sysconfdir. Together, -nodefaults and -no-user-config allow Xen
> to avoid unkown and uncontrolled qemu configuration.
>
> Both options are also added to the qemu invocation in the
> xen-qemu-dom0-disk-backend systemd service file.
>
> Signed-off-by: Jim Fehlig <jfehlig@suse.com>
> ---
> tools/hotplug/Linux/systemd/xen-qemu-dom0-disk-backend.service.in | 1 +
> tools/libxl/libxl_dm.c | 6 ++++++
> 2 files changed, 7 insertions(+)
>
> diff --git a/tools/hotplug/Linux/systemd/xen-qemu-dom0-disk-backend.service.in b/tools/hotplug/Linux/systemd/xen-qemu-dom0-disk-backend.service.in
> index acf61a8..f56775b 100644
> --- a/tools/hotplug/Linux/systemd/xen-qemu-dom0-disk-backend.service.in
> +++ b/tools/hotplug/Linux/systemd/xen-qemu-dom0-disk-backend.service.in
> @@ -14,6 +14,7 @@ ExecStartPre=/bin/mkdir -p @XEN_RUN_DIR@
> ExecStart=@qemu_xen_systemd@ -xen-domid 0 \
> -xen-attach -name dom0 -nographic -M xenpv -daemonize \
> -monitor /dev/null -serial /dev/null -parallel /dev/null \
> + -nodefaults -no-user-config \
> -pidfile @XEN_RUN_DIR@/qemu-dom0.pid
>
> [Install]
> diff --git a/tools/libxl/libxl_dm.c b/tools/libxl/libxl_dm.c
> index 4aca38e..cfda24c 100644
> --- a/tools/libxl/libxl_dm.c
> +++ b/tools/libxl/libxl_dm.c
> @@ -828,6 +828,12 @@ static int libxl__build_device_model_args_new(libxl__gc *gc,
> */
> flexarray_append(dm_args, "-nodefaults");
>
> + /*
> + * Do not use any of the user-provided config files in sysconfdir,
> + * avoiding unkown and uncontrolled configuration.
> + */
> + flexarray_append(dm_args, "-no-user-config");
> +
> if (b_info->type == LIBXL_DOMAIN_TYPE_PV) {
> flexarray_append(dm_args, "-xen-attach");
> }
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http://lists.xen.org/xen-devel
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] tools: Restrict configuration of qemu processes
2016-03-15 1:14 ` Jim Fehlig
@ 2016-03-15 12:28 ` Wei Liu
2016-03-22 20:12 ` Jim Fehlig
0 siblings, 1 reply; 7+ messages in thread
From: Wei Liu @ 2016-03-15 12:28 UTC (permalink / raw)
To: Jim Fehlig; +Cc: Ian Jackson, Stefano Stabellini, Wei Liu, xen-devel
On Mon, Mar 14, 2016 at 07:14:12PM -0600, Jim Fehlig wrote:
> Opps, forgot to cc the tools maintainers, sorry. I can resend if needed.
>
> Regards,
> Jim
>
> On 03/14/2016 07:08 PM, Jim Fehlig wrote:
> > Commit 6ef823fd added '-nodefaults' to the qemu args created by
> > libxl, which is a good step in restricting qemu's default
> > configuration. This change takes another step by adding
> > -no-user-config, which ignores any user-provided config files in
> > sysconfdir. Together, -nodefaults and -no-user-config allow Xen
> > to avoid unkown and uncontrolled qemu configuration.
> >
> > Both options are also added to the qemu invocation in the
> > xen-qemu-dom0-disk-backend systemd service file.
> >
> > Signed-off-by: Jim Fehlig <jfehlig@suse.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
> > ---
> > tools/hotplug/Linux/systemd/xen-qemu-dom0-disk-backend.service.in | 1 +
> > tools/libxl/libxl_dm.c | 6 ++++++
> > 2 files changed, 7 insertions(+)
> >
> > diff --git a/tools/hotplug/Linux/systemd/xen-qemu-dom0-disk-backend.service.in b/tools/hotplug/Linux/systemd/xen-qemu-dom0-disk-backend.service.in
> > index acf61a8..f56775b 100644
> > --- a/tools/hotplug/Linux/systemd/xen-qemu-dom0-disk-backend.service.in
> > +++ b/tools/hotplug/Linux/systemd/xen-qemu-dom0-disk-backend.service.in
> > @@ -14,6 +14,7 @@ ExecStartPre=/bin/mkdir -p @XEN_RUN_DIR@
> > ExecStart=@qemu_xen_systemd@ -xen-domid 0 \
> > -xen-attach -name dom0 -nographic -M xenpv -daemonize \
> > -monitor /dev/null -serial /dev/null -parallel /dev/null \
> > + -nodefaults -no-user-config \
> > -pidfile @XEN_RUN_DIR@/qemu-dom0.pid
> >
> > [Install]
> > diff --git a/tools/libxl/libxl_dm.c b/tools/libxl/libxl_dm.c
> > index 4aca38e..cfda24c 100644
> > --- a/tools/libxl/libxl_dm.c
> > +++ b/tools/libxl/libxl_dm.c
> > @@ -828,6 +828,12 @@ static int libxl__build_device_model_args_new(libxl__gc *gc,
> > */
> > flexarray_append(dm_args, "-nodefaults");
> >
> > + /*
> > + * Do not use any of the user-provided config files in sysconfdir,
> > + * avoiding unkown and uncontrolled configuration.
> > + */
> > + flexarray_append(dm_args, "-no-user-config");
> > +
> > if (b_info->type == LIBXL_DOMAIN_TYPE_PV) {
> > flexarray_append(dm_args, "-xen-attach");
> > }
>
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http://lists.xen.org/xen-devel
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] tools: Restrict configuration of qemu processes
2016-03-15 12:28 ` Wei Liu
@ 2016-03-22 20:12 ` Jim Fehlig
0 siblings, 0 replies; 7+ messages in thread
From: Jim Fehlig @ 2016-03-22 20:12 UTC (permalink / raw)
To: Wei Liu; +Cc: xen-devel, Ian Jackson, Stefano Stabellini
On 03/15/2016 06:28 AM, Wei Liu wrote:
> On Mon, Mar 14, 2016 at 07:14:12PM -0600, Jim Fehlig wrote:
>> Opps, forgot to cc the tools maintainers, sorry. I can resend if needed.
>>
>> Regards,
>> Jim
>>
>> On 03/14/2016 07:08 PM, Jim Fehlig wrote:
>>> Commit 6ef823fd added '-nodefaults' to the qemu args created by
>>> libxl, which is a good step in restricting qemu's default
>>> configuration. This change takes another step by adding
>>> -no-user-config, which ignores any user-provided config files in
>>> sysconfdir. Together, -nodefaults and -no-user-config allow Xen
>>> to avoid unkown and uncontrolled qemu configuration.
>>>
>>> Both options are also added to the qemu invocation in the
>>> xen-qemu-dom0-disk-backend systemd service file.
>>>
>>> Signed-off-by: Jim Fehlig <jfehlig@suse.com>
> Acked-by: Wei Liu <wei.liu2@citrix.com>
If there are no remaining issues, can this patch be applied? Thanks!
Regards,
Jim
>
>>> ---
>>> tools/hotplug/Linux/systemd/xen-qemu-dom0-disk-backend.service.in | 1 +
>>> tools/libxl/libxl_dm.c | 6 ++++++
>>> 2 files changed, 7 insertions(+)
>>>
>>> diff --git a/tools/hotplug/Linux/systemd/xen-qemu-dom0-disk-backend.service.in b/tools/hotplug/Linux/systemd/xen-qemu-dom0-disk-backend.service.in
>>> index acf61a8..f56775b 100644
>>> --- a/tools/hotplug/Linux/systemd/xen-qemu-dom0-disk-backend.service.in
>>> +++ b/tools/hotplug/Linux/systemd/xen-qemu-dom0-disk-backend.service.in
>>> @@ -14,6 +14,7 @@ ExecStartPre=/bin/mkdir -p @XEN_RUN_DIR@
>>> ExecStart=@qemu_xen_systemd@ -xen-domid 0 \
>>> -xen-attach -name dom0 -nographic -M xenpv -daemonize \
>>> -monitor /dev/null -serial /dev/null -parallel /dev/null \
>>> + -nodefaults -no-user-config \
>>> -pidfile @XEN_RUN_DIR@/qemu-dom0.pid
>>>
>>> [Install]
>>> diff --git a/tools/libxl/libxl_dm.c b/tools/libxl/libxl_dm.c
>>> index 4aca38e..cfda24c 100644
>>> --- a/tools/libxl/libxl_dm.c
>>> +++ b/tools/libxl/libxl_dm.c
>>> @@ -828,6 +828,12 @@ static int libxl__build_device_model_args_new(libxl__gc *gc,
>>> */
>>> flexarray_append(dm_args, "-nodefaults");
>>>
>>> + /*
>>> + * Do not use any of the user-provided config files in sysconfdir,
>>> + * avoiding unkown and uncontrolled configuration.
>>> + */
>>> + flexarray_append(dm_args, "-no-user-config");
>>> +
>>> if (b_info->type == LIBXL_DOMAIN_TYPE_PV) {
>>> flexarray_append(dm_args, "-xen-attach");
>>> }
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xen.org
> http://lists.xen.org/xen-devel
_______________________________________________
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^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] tools: Restrict configuration of qemu processes
2016-03-15 1:08 [PATCH] tools: Restrict configuration of qemu processes Jim Fehlig
2016-03-15 1:14 ` Jim Fehlig
@ 2016-03-24 13:53 ` Ian Jackson
2016-05-09 16:35 ` Ian Jackson
1 sibling, 1 reply; 7+ messages in thread
From: Ian Jackson @ 2016-03-24 13:53 UTC (permalink / raw)
To: Jim Fehlig; +Cc: xen-devel
Jim Fehlig writes ("[Xen-devel] [PATCH] tools: Restrict configuration of qemu processes"):
> Commit 6ef823fd added '-nodefaults' to the qemu args created by
> libxl, which is a good step in restricting qemu's default
> configuration. This change takes another step by adding
> -no-user-config, which ignores any user-provided config files in
> sysconfdir. Together, -nodefaults and -no-user-config allow Xen
> to avoid unkown and uncontrolled qemu configuration.
>
> Both options are also added to the qemu invocation in the
> xen-qemu-dom0-disk-backend systemd service file.
Queued, thanks. Also listed for backport.
Ian.
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^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] tools: Restrict configuration of qemu processes
2016-03-24 13:53 ` Ian Jackson
@ 2016-05-09 16:35 ` Ian Jackson
2016-05-09 22:37 ` Jim Fehlig
0 siblings, 1 reply; 7+ messages in thread
From: Ian Jackson @ 2016-05-09 16:35 UTC (permalink / raw)
To: Jim Fehlig, xen-devel
Ian Jackson writes ("Re: [Xen-devel] [PATCH] tools: Restrict configuration of qemu processes"):
> Jim Fehlig writes ("[Xen-devel] [PATCH] tools: Restrict configuration of qemu processes"):
> > Commit 6ef823fd added '-nodefaults' to the qemu args created by
> > libxl, which is a good step in restricting qemu's default
> > configuration. This change takes another step by adding
> > -no-user-config, which ignores any user-provided config files in
> > sysconfdir. Together, -nodefaults and -no-user-config allow Xen
> > to avoid unkown and uncontrolled qemu configuration.
> >
> > Both options are also added to the qemu invocation in the
> > xen-qemu-dom0-disk-backend systemd service file.
>
> Queued, thanks. Also listed for backport.
I found this on my backport todo list. Thinking about it, I have had
second thoughts.
I worry that existing users of stable branches might be relying on the
user config feature (for example by dropping qemu configuration in
~root). If they are, then applying this would break things for them.
It's not a security problem because in xen the configuration in
question would have to come from ~root.
So I think, probably, that we should leave this be (ie, not backport
the patch). Does anyone want to try to change my mind ?
Ian.
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^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] tools: Restrict configuration of qemu processes
2016-05-09 16:35 ` Ian Jackson
@ 2016-05-09 22:37 ` Jim Fehlig
0 siblings, 0 replies; 7+ messages in thread
From: Jim Fehlig @ 2016-05-09 22:37 UTC (permalink / raw)
To: Ian Jackson, xen-devel
On 05/09/2016 10:35 AM, Ian Jackson wrote:
> Ian Jackson writes ("Re: [Xen-devel] [PATCH] tools: Restrict configuration of qemu processes"):
>> Jim Fehlig writes ("[Xen-devel] [PATCH] tools: Restrict configuration of qemu processes"):
>>> Commit 6ef823fd added '-nodefaults' to the qemu args created by
>>> libxl, which is a good step in restricting qemu's default
>>> configuration. This change takes another step by adding
>>> -no-user-config, which ignores any user-provided config files in
>>> sysconfdir. Together, -nodefaults and -no-user-config allow Xen
>>> to avoid unkown and uncontrolled qemu configuration.
>>>
>>> Both options are also added to the qemu invocation in the
>>> xen-qemu-dom0-disk-backend systemd service file.
>> Queued, thanks. Also listed for backport.
> I found this on my backport todo list. Thinking about it, I have had
> second thoughts.
>
> I worry that existing users of stable branches might be relying on the
> user config feature (for example by dropping qemu configuration in
> ~root). If they are, then applying this would break things for them.
>
> It's not a security problem because in xen the configuration in
> question would have to come from ~root.
Good point.
> So I think, probably, that we should leave this be (ie, not backport
> the patch). Does anyone want to try to change my mind ?
I never asked for a backport, so have no incentive to change your mind. Plus, I
agree with your comment.
Regards,
Jim
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^ permalink raw reply [flat|nested] 7+ messages in thread
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2016-03-15 1:08 [PATCH] tools: Restrict configuration of qemu processes Jim Fehlig
2016-03-15 1:14 ` Jim Fehlig
2016-03-15 12:28 ` Wei Liu
2016-03-22 20:12 ` Jim Fehlig
2016-03-24 13:53 ` Ian Jackson
2016-05-09 16:35 ` Ian Jackson
2016-05-09 22:37 ` Jim Fehlig
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