[Pkg-xen-devel] Bug#695221: Bug#695221: confirmed bug, serious

[Thomas Goirand]

I don't think it's useful to bikeshed about the severity of an issue but...

On 02/10/2013 11:45 PM, Daniel Pocock wrote:
> It is serious because
> 
> a) it makes the package and the whole system unusable for all but one
> very specific network configuration (users with a /24)

Using a /24 is all but a "very specific network configuration", it's in
fact the most common one.

> b) using good old `xm' style Xen I never experienced any issue like
> this, just using a /26 subnet with xm on squeeze is fine.

This is totally unrelated.

> c) it will lead to a complete loss of connectivity for people accessing
> a host remotely to set up XCP

Sure, but it doesn't match the "serious" definition:

makes the package in question unusable by most or all users, or causes
data loss, or introduces a security hole allowing access to the accounts
of users who use the package.

Besides this, I don't think it's reasonable to delay the release of
Wheezy just for this bug.

> I did a `find' in /etc and /var and I located the following file:
> 
> /var/lib/xcp/networkd.db
> 
> which contains the value {"interface_config":  ......"MY ADDRESS", 32]]]
> 
> The 32 is the bad subnet mask.  Using vi, I replaced it with 29  (for a
> /29), rebooted, and it came up OK.

That's interesting!

I've added Mike and Jon as Cc:, hoping that they will be able to tell
wtf is going on, and why the db is being wrong.

> As I don't know XCP very well, I
> don't want to suggest this is a valid workaround.  Could anyone with
> more experience confirm if that file can be modified by hand in this
> case?  Is there something else that could come along and clobber that
> file?  Does xcp-networkd need to be stopped before modifying the file
> safely?

Mike must know.

> If there is a workaround (what I describe above, or something else) for
> this such that a /29 or some other valid netmask can be enabled, then
> the bug could probably be downgraded to important but certainly not
> normal, it is just too disruptive.

Ultimately, this is the job of the maintainer of a given package to
decide the seriousness of a bug. To me, setting it to either normal or
important is exactly the same (eg: it is on my radar, and I really want
to have it fix), and discussing the seriousness doesn't help. Discussing
ways to fix it does.

> To extend the scope of what may qualify as a valid workaround:
> 
> a) is there some valid use case that avoids using pif-reconfigure-ip and
> just let /etc/network/interfaces manage the IP?

I don't think so. XAPI needs to know how you configure your PIF.

> b) should the user put a /24 subnet on a dummy interface and configure
> eth0 or xenbr0 separately from XCP?

I don't think so.

> I also came across this:
> 
> http://lists.xen.org/archives/html/xen-api/2012-05/msg00104.html
> 
> which contradicts this:
> 
> http://wiki.xen.org/wiki/XCP_toolstack_on_a_Debian-based_distribution#Setup_the_network.2Finterfaces_file
> 
> Specifically, the mailing list posts suggests nothing should be in
> /etc/network/interfaces, but the wiki suggests that the interface should
> be described in /etc/network/interfaces (even though it will eventually
> be reconfigured by xcp-networkd later in the boot process)

As much as I know, you do have to configure stuff in
/etc/network/interfaces. This is described in the README.Debian for
xcp-xapi, under section 4.2 of the file. Though the networking might be
different when using openvswitch, I'm not sure about this.

Thomas