2:33 p.m.
On 12/13/2012 12:05 PM, Osier Yang wrote:
Since "rawio" and "cdbfilter" are only valid for
"lun", this
groups them together; And since both of them intend to allow
the unprivledged user to use the SG_IO commands, they must be
s/unprivledged/unprivileged/
exclusive.
---
docs/formatdomain.html.in | 13 +++++++++-
docs/schemas/domaincommon.rng | 52 ++++++++++++++++++++++++++++------------
2 files changed, 48 insertions(+), 17 deletions(-)
diff --git a/docs/formatdomain.html.in b/docs/formatdomain.html.in
index 8e234fd..8c7c682 100644
--- a/docs/formatdomain.html.in
+++ b/docs/formatdomain.html.in
@@ -1395,7 +1395,18 @@
rawio='yes', rawio capability will be enabled for all disks in
the domain (because, in the case of QEMU, this capability can
only be set on a per-process basis). This attribute is only
- valid when device is "lun".
+ valid when device is "lun". NB, <code>rawio</code> intends
to
+ confine the capability per-device, however, current QEMU
+ implementation gives the domain process broader capability
+ than that (per-process basis, affects all the domain disks).
+ To confine the capability as much as possible for QEMU driver
+ as this stage, <code>cdbfilter</code> is recommended.
+ The optional <code>cdbfilter</code> attribute
+ (<span class="since">since 1.0.1</span>) indicates whether
the
+ kernel will filter unprivileged SG_IO for the disk, valid settings
+ are "yes" or "no" (defaults to "yes"). Note that
it's exclusive
+ with attribute <code>rawio</code>; Same with
<code>rawio</code>,
+ <code>cdbfilter</code> is only valid for device 'lun'.
Hmm, this doesn't seem like the smartest of designs. If I'm
understanding you right, we have:
rawio cdbfilter result
missing missing kernel prevents SG_IO
missing no kernel prevents SG_IO
missing yes SG_IO allowed for disk
no missing kernel prevents SG_IO
no no kernel prevents SG_IO
no yes SG_IO allowed for disk
yes missing SG_IO allowed for process
yes no SG_IO allowed for process
yes yes error
Why not simplify things, and have a single attribute rawio, with
multiple values?
rawio result
missing kernel prevents SG_IO
no kernel prevents SG_IO
yes SG_IO allowed for process
cdb SG_IO allowed for disk
where we document that 'yes' works on more kernel versions than 'cdb',
but that 'cdb' (new to 1.0.1) is more secure.
The optional <code>snapshot</code> attribute
indicates the default
behavior of the disk during disk snapshots: "internal"
requires a file format such as qcow2 that can store both the
diff --git a/docs/schemas/domaincommon.rng b/docs/schemas/domaincommon.rng
index 14344e2..c8cdfd7 100644
--- a/docs/schemas/domaincommon.rng
+++ b/docs/schemas/domaincommon.rng
@@ -971,24 +971,44 @@
-->
<define name="disk">
<element name="disk">
- <optional>
- <attribute name="device">
- <choice>
- <value>floppy</value>
- <value>disk</value>
- <value>cdrom</value>
- <value>lun</value>
- </choice>
- </attribute>
- </optional>
- <optional>
- <attribute name="rawio">
+ <choice>
+ <group>
+ <optional>
+ <attribute name="device">
+ <choice>
+ <value>floppy</value>
+ <value>disk</value>
+ <value>cdrom</value>
+ </choice>
+ </attribute>
+ </optional>
+ </group>
I like that you split this up, to enforce that rawio only appears with
device='lun'. However...
+ <group>
+ <optional>
+ <attribute name="device">
+ <value>lun</value>
+ </attribute>
+ </optional>
This device='lun' should not be <optional>, since the default when
device= is omitted is 'disk' (that is, unless you want the absence of
device= and the presence of rawio='...' to imply a lun, but I think we
should require an explicit use of lun before allowing rawio=).
<choice>
- <value>yes</value>
- <value>no</value>
+ <optional>
+ <attribute name="rawio">
+ <choice>
+ <value>yes</value>
+ <value>no</value>
+ </choice>
+ </attribute>
+ </optional>
+ <optional>
+ <attribute name="cdbfilter">
+ <choice>
+ <value>yes</value>
+ <value>no</value>
+ </choice>
And this part would need a major rework if you go with my idea of a
tri-state attribute value for rawio instead of introducing yet another
attribute.
+ </attribute>
+ </optional>
</choice>
- </attribute>
- </optional>
+ </group>
+ </choice>
<optional>
<ref name="snapshot"/>
</optional>
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org