Re: [PATCH] docs: clarify xenstore permission documentation

[Juergen Gross <jgross@xxxxxxxx>]

On 09.02.23 16:29, Edwin Torok wrote:
> > On 9 Feb 2023, at 15:15, Andrew Cooper <andrew.cooper3@xxxxxxxxxx> wrote:
> >
> > On 09/02/2023 2:41 pm, Juergen Gross wrote:
> > > In docs/misc/xenstore.txt the description of the Xenstore node access
> > > permissions is missing one important aspect, which can be found only
> > > in the code or in the wiki [1]:
> > >
> > > The first permission entry is defining the owner of the node via the
> > > domid, and the access rights for all domains NOT having a dedicated
> > > permission entry.
> > >
> > > Make that aspect clear in the official documentation.
> > >
> > > [1]: https://wiki.xenproject.org/wiki/XenBus#Permissions
> > >
> > > Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
> > I feel as if Edvin deserves some kind of credit here, seeing as it was
> > his observation...
> >
> > Also, CC to double check the wording.
> >
> > ~Andrew
> >
> > > ---
> > > docs/misc/xenstore.txt | 17 ++++++++++-------
> > > 1 file changed, 10 insertions(+), 7 deletions(-)
> > >
> > > diff --git a/docs/misc/xenstore.txt b/docs/misc/xenstore.txt
> > > index 8887e7df88..d807ef0709 100644
> > > --- a/docs/misc/xenstore.txt
> > > +++ b/docs/misc/xenstore.txt
> > > @@ -45,13 +45,16 @@ them to within 2048 bytes.  (See XENSTORE_*_PATH_MAX in 
> > > xs_wire.h.)
> > >
> > > Each node has one or multiple permission entries.  Permissions are
> > > granted by domain-id, the first permission entry of each node specifies
> > > -the owner of the node.  Permissions of a node can be changed by the
> > > -owner of the node, the owner can only be modified by the control
> > > -domain (usually domain id 0).  The owner always has the right to read
> > > -and write the node, while other permissions can be setup to allow
> > > -read and/or write access.  When a domain is being removed from Xenstore
> > > -nodes owned by that domain will be removed together with all of those
> > > -nodes' children.
> > > +the owner of the node, who always has full access to the node (read and
> > > +write permission).
> > >   The access rights of the first entry specify the
> > > +allowed access for all domains not having a dedicated permission entry
> > > +(the default is "n", removing access for all domains not explicitly
> > > +added via additional permission entries).  Permissions of a node can be
> > > +changed by the owner of the node, the owner can only be modified by the
> > > +control domain (usually domain id 0).
> This looks good in general, one small nitpick, maybe we need something like 
> this too:
> ", or domains equivalent to the owner or control domain (domain equivalence can be 
> established with the privileged SET_TARGET operation)"
This is already part of the SET_TARGET description. So I don't think we
need to add it here, too.


Juergen

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