[Xen-devel] [PATCH v2 1/5] libxl: allow /local/domain/0/device-model/$DOMID to be written by $DOMID

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

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>

---
Changes in v2:
- fix permissions to actually do what intended
- use LIBXL_TOOLSTACK_DOMID instead of 0
---
 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 79a9a22..f4f104f 100644
--- a/tools/libxl/libxl_dm.c
+++ b/tools/libxl/libxl_dm.c
@@ -1461,6 +1461,7 @@ 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();
@@ -1503,7 +1504,11 @@ 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 = LIBXL_TOOLSTACK_DOMID;
+    rwperm[0].perms = XS_PERM_NONE;
+    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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