Re: [Libguestfs] [PATCH 2/2] Use setfiles from the appliance for the SELinux relabel (RHBZ#1089100).
8:25 a.m.
[Including libguestfs mailing list this time]
On Tue, May 27, 2014 at 06:05:15AM -0700, Colin Walters wrote:
On Tue, May 27, 2014, at 02:04 AM, Richard W.M. Jones wrote:
>
> I'm still anxious for Colin to tell us if this API is suitable for his
> needs.
I'd like an API that allows me to only relabel *unlabeled* files.
The use case here is: I have an existing disk image with an OS,
I want to inject e.g. a systemd service into it. If I do this offline
from libguestfs, the injected /usr/libexec/mydaemon and
/usr/lib/systemd/system/mydaemon.service
won't be labeled, but everything else will be.
> I'm guessing that OStree does not have /etc/selinux/config,
Right, it's in the "deployment root" of
/ostree/deploy/$osname/deploy/$checksum/etc/selinux/config
Got it:
<fs> ll
/ostree/deploy/project-atomic-controller/deploy/afc1794b4b42df77edf1988897b167573b99e299fa39a15b07b235a0e7387d02.0/etc/selinux/targeted/contexts/files/file_contexts
-rw-r--r--. 1 root root 352240 Apr 14 20:14
/sysroot/ostree/deploy/project-atomic-controller/deploy/afc1794b4b42df77edf1988897b167573b99e299fa39a15b07b235a0e7387d02.0/etc/selinux/targeted/contexts/files/file_contexts
To figure that out you'd want to use the OSTree APIs; and then
it
introduces
further questions around *which* deployments you want to relabel. All?
Only
one (the default?).
What I do currently in my scripts is only relabel the default, and that
would
be the best default for an API.
But a totally valid thing to do with OSTree is - say you're running
RHEL7,
and you want to check whether the latest Fedora kernel fixes an issue
you're seeing. You can use ostree to dynamically parallel install
Fedora content in a new deployment root, try it with near-total
safety[1],
and then if it doesn't work, just delete it and free up the space.
So I think an API which looks like this ...
required params:
None
optional params:
path =>
Either a directory to be relabelled recursively, or a single
file (defaults to "/").
root =>
Inspection root of guest. Optional, only makes sense when
'contexts' param is *omitted*.
contexts =>
The `file_contexts' file. Defaults to
/etc/selinux/$selinux_type/contexts/files/file_contexts
OSTree would probably want to pass:
/ostree/deploy/$osname/deploy/$checksum/etc/selinux/targeted/contexts/files/file_contexts
Inspection could be updated to parse /etc/selinux/config in order to
get the default SELinux policy and pass it back through an API such as
`inspect-get-selinux-type'.
If 'contexts' is omitted, 'root' must be supplied, and it causes an
internal call to guestfs_inspect_get_selinux_type (g, root) in order
to get the default policy.
What do you think?
Rich.
--
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9:43 a.m.
New subject: [PATCH 2/2] Use setfiles from the appliance for the SELinux relabel (RHBZ#1089100).
On Tuesday 27 May 2014 14:25:08 Richard W.M. Jones wrote:
So I think an API which looks like this ...
required params:
None
optional params:
path =>
Either a directory to be relabelled recursively, or a single
file (defaults to "/").
root =>
Inspection root of guest. Optional, only makes sense when
'contexts' param is *omitted*.
contexts =>
The `file_contexts' file. Defaults to
/etc/selinux/$selinux_type/contexts/files/file_contexts
OSTree would probably want to pass:
/ostree/deploy/$osname/deploy/$checksum/etc/selinux/targeted/contexts
/files/file_contexts
Inspection could be updated to parse /etc/selinux/config in order to
get the default SELinux policy and pass it back through an API such as
`inspect-get-selinux-type'.
If 'contexts' is omitted, 'root' must be supplied, and it causes an
internal call to guestfs_inspect_get_selinux_type (g, root) in order
to get the default policy.
Note that not specifying a root could lead to issues, as the file
contexts are relative to a root. So if I say to relabel the path
/guestmountpoint/etc/myconfig according to some /path/of/file_contexts
without specifying what is the root, how should setfiles know that path
is /etc/myconfig mounted at /guestmountpoint?
At this point I'm thinking the best option would be making the root a
normal (mandatory) argument, leaving path and contexts as optional (with
the former being "/" as default value, and the latter as "find it from
the root").
In the situation above, path would become a relative path to the
specified root (so if I mount a guest into /guest and I want to relabel
it only under /etc, I would pass root=/guest and path=/etc).
--
Pino Toscano
12:02 p.m.
New subject: [PATCH 2/2] Use setfiles from the appliance for the SELinux relabel (RHBZ#1089100).
On Tue, May 27, 2014 at 04:43:31PM +0200, Pino Toscano wrote:
At this point I'm thinking the best option would be making the
root a
normal (mandatory) argument, leaving path and contexts as optional (with
the former being "/" as default value, and the latter as "find it from
the root").
IIUC, that would force people to use inspection in order to relabel
filesystems. That would prevent Colin's use-case (because libguestfs
cannot currently inspect ostree guests, although that in itself is a
bug, certainly once ostree becomes established and widely used).
Rich.
--
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
Read my programming and virtualization blog: http://rwmj.wordpress.com
virt-top is 'top' for virtual machines. Tiny program with many
powerful monitoring features, net stats, disk stats, logging, etc.
http://people.redhat.com/~rjones/virt-top
8:01 a.m.
New subject: [PATCH 2/2] Use setfiles from the appliance for the SELinux relabel (RHBZ#1089100).
On Tuesday 27 May 2014 18:02:16 Richard W.M. Jones wrote:
On Tue, May 27, 2014 at 04:43:31PM +0200, Pino Toscano wrote:
> At this point I'm thinking the best option would be making the root
> a
> normal (mandatory) argument, leaving path and contexts as optional
> (with the former being "/" as default value, and the latter as
> "find it from the root").
IIUC, that would force people to use inspection in order to relabel
filesystems. That would prevent Colin's use-case (because libguestfs
cannot currently inspect ostree guests, although that in itself is a
bug, certainly once ostree becomes established and widely used).
(Taking this back from the dust...)
The problem with making the root optional is that the SELinux tools need
to know what is the root of the system where files are being relabeled,
since contexts are relative to this root.
After all, in Colin's use case OSTree should know where are all the
roots already, shouldn't it?
--
Pino Toscano
3574
days inactive
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3 comments
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participants (2)
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Pino Toscano -
Richard W.M. Jones