docs: Document SELinux caveats when migrating over UNIX sockets

The information about sockets having different label than the one on the file
and the way it needs to be set is very difficult to find for those who did not
come across it before.  Let's describe what needs to happen in order for the
migration to go through rather than rely on general knowledge of others.

Signed-off-by: Martin Kletzander <mkletzan@redhat.com>
Reviewed-by: Jiri Denemark <jdenemar@redhat.com>

diff --git a/docs/manpages/virsh.rst b/docs/manpages/virsh.rst
index 36c868a3e69e0819e16837b9e25d0dbff40e097d..86deaa486de3cf7e2081b5430c56b0ae8360c0f1 100644 (file)
--- a/docs/manpages/virsh.rst
+++ b/docs/manpages/virsh.rst
@@ -3340,7 +3340,12 @@ migrating disks.  This can be *tcp://address:port* to specify a listen address
 UNIX socket with that specified path.  In this case you need to make sure the
 same socket path is accessible to both source and destination hypervisors and
 connecting to the socket on the source (after hypervisor creates it on the
-destination) will actually connect to the destination.
+destination) will actually connect to the destination. If you are using SELinux
+(at least on the source host) you need to make sure the socket on the source is
+accessible to libvirtd/QEMU for connection.  Libvirt cannot change the context
+of the existing socket because it is different from the file representation of
+the socket and the context is chosen by its creator (usually by using
+*setsockcreatecon{,_raw}()* functions).
 
 
 migrate-compcache

diff --git a/docs/migration.html.in b/docs/migration.html.in
index b080e3a7f591c36d551c73e4e7f3e05ecb9ba925..ac38c6e13d4ad4cb213670b14f7e3f995edc8228 100644 (file)
--- a/docs/migration.html.in
+++ b/docs/migration.html.in
@@ -677,6 +677,15 @@ virsh migrate --domain web1 [--p2p] --copy-storage-all
   --disks-uri unix:///tmp/migdir/test-sock-nbd
     </pre>
 
+    <p>
+      One caveat is that on SELinux-enabled systems all the sockets that the
+      hypervisor is going to connect to needs to have the proper context and
+      that is chosen before its creation by the process that creates it.  That
+      is usually done by using <code>setsockcreatecon{,raw}()</code> functions.
+      Generally *system_r:system_u:svirt_socket_t:s0* should do the trick, but
+      check the SELinux rules and settings of your system.
+    </p>
+
     <p>
       Supported by QEMU driver
     </p>