sd-device: don't use BPF filtering for kernel monitors

BPF filtering accesses fields in the netlink header that are
only filled in by libudev, never by the kernel. Therefore adding
BPF filters for kernel monitors is pointless. Even false filtering
of kernel events might be possible; at least it's hard to prove that
it can't occur.

(cherry picked from commit d8ce385fe3e5be91b6f414415e10f8897e41d942)

diff --git a/src/libsystemd/sd-device/device-monitor.c b/src/libsystemd/sd-device/device-monitor.c
index fd5900704dfce37e3cd9690d618c3e5926275b4b..4f555a0126a95a6c3627f55229a91168dcf647f0 100644 (file)
--- a/src/libsystemd/sd-device/device-monitor.c
+++ b/src/libsystemd/sd-device/device-monitor.c
@@ -627,8 +627,9 @@ _public_ int sd_device_monitor_filter_update(sd_device_monitor *m) {
         if (m->filter_uptodate)
                 return 0;
 
-        if (hashmap_isempty(m->subsystem_filter) &&
-            set_isempty(m->tag_filter)) {
+        if (m->snl.nl.nl_groups == MONITOR_GROUP_KERNEL ||
+            (hashmap_isempty(m->subsystem_filter) &&
+             set_isempty(m->tag_filter))) {
                 m->filter_uptodate = true;
                 return 0;
         }