Re: [Xen-devel] [PATCH RFC 1/2] libxl: allow /local/domain/0/device-model/$DOMID to be written by $DOMID

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Mon, Jun 01, 2015 at 05:01:34PM +0100, Stefano Stabellini wrote:
> The device model is going to restrict its xenstore connection to $DOMID
> level. Let it access /local/domain/0/device-model/$DOMID, as it is
> required by QEMU to read/write the physmap. It doesn't contain any
> information the guest is not already fully aware of.
> 
> Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
> ---
>  tools/libxl/libxl_dm.c |    7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/tools/libxl/libxl_dm.c b/tools/libxl/libxl_dm.c
> index 97a921f..e74042b 100644
> --- a/tools/libxl/libxl_dm.c
> +++ b/tools/libxl/libxl_dm.c
> @@ -1467,6 +1467,7 @@ void libxl__spawn_local_dm(libxl__egc *egc, 
> libxl__dm_spawn_state *dmss)
>      char **pass_stuff;
>      const char *dm;
>      int dm_state_fd = -1;
> +    struct xs_permissions rwperm[2];
>  
>      if (libxl_defbool_val(b_info->device_model_stubdomain)) {
>          abort();
> @@ -1509,7 +1510,11 @@ void libxl__spawn_local_dm(libxl__egc *egc, 
> libxl__dm_spawn_state *dmss)
>      }
>  
>      path = libxl__device_model_xs_path(gc, LIBXL_TOOLSTACK_DOMID, domid, "");
> -    xs_mkdir(ctx->xsh, XBT_NULL, path);
> +    rwperm[0].id = 0;

Use LIBXL_TOOLSTACK_DOMID?

> +    rwperm[0].perms = XS_PERM_WRITE;

This is probably not what you mean. This means all other domains have
write access.  See tools/xenstore/include/xenstore.h L152.

And, do you also want to consider stubdom?

Wei.

> +    rwperm[1].id = domid;
> +    rwperm[1].perms = XS_PERM_WRITE;
> +    libxl__xs_mkdir(gc, XBT_NULL, path, rwperm, 2); 
>  
>      if (b_info->type == LIBXL_DOMAIN_TYPE_HVM &&
>          b_info->device_model_version
> -- 
> 1.7.10.4

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