From 8c6791798de4b68923e422f565581af1ee74124c Mon Sep 17 00:00:00 2001
From: Roger Pau Monne <roger.pau@citrix.com>
Date: Thu, 30 Jun 2022 14:35:35 +0200
Subject: [PATCH] tools/libxl: env variable to signal whether disk/nic backend
 is trusted
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Introduce support in libxl for fetching the default backend trusted
option for disk and nic devices.

Users can set libxl_{disk,nic}_backend_untrusted environment variable
to notify libxl of whether the backends for disk and nic devices
should be trusted.  Such information is passed into the frontend so it
can take the appropriate measures.

This is part of XSA-403.

Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
---
 tools/libs/light/libxl_disk.c | 3 +++
 tools/libs/light/libxl_nic.c  | 3 +++
 2 files changed, 6 insertions(+)

diff --git a/tools/libs/light/libxl_disk.c b/tools/libs/light/libxl_disk.c
index 93936d0dd0..0aaf6afce8 100644
--- a/tools/libs/light/libxl_disk.c
+++ b/tools/libs/light/libxl_disk.c
@@ -395,6 +395,9 @@ static void device_disk_add(libxl__egc *egc, uint32_t domid,
         flexarray_append(front, GCSPRINTF("%d", device->devid));
         flexarray_append(front, "device-type");
         flexarray_append(front, disk->is_cdrom ? "cdrom" : "disk");
+        flexarray_append(front, "trusted");
+        flexarray_append(front, getenv("libxl_disk_backend_untrusted") ? "0"
+                                                                       : "1");
 
         /*
          * Old PV kernel disk frontends before 2.6.26 rely on tool stack to
diff --git a/tools/libs/light/libxl_nic.c b/tools/libs/light/libxl_nic.c
index 0b9e70c9d1..34c3fe6df0 100644
--- a/tools/libs/light/libxl_nic.c
+++ b/tools/libs/light/libxl_nic.c
@@ -255,6 +255,9 @@ static int libxl__set_xenstore_nic(libxl__gc *gc, uint32_t domid,
     flexarray_append(back, "hotplug-status");
     flexarray_append(back, "");
 
+    flexarray_append(front, "trusted");
+    flexarray_append(front, getenv("libxl_nic_backend_untrusted") ? "0" : "1");
+
     return 0;
 }
 
-- 
2.37.0