Fix failed exec after systemctl daemon-reload

libcontainer/cgroups/devices/systemd.go

@@ -128,14 +128,16 @@ func systemdProperties(r *configs.Resources) ([]systemdDbus.Property, error) {
 			case devices.CharDevice:
 				entry.Path = fmt.Sprintf("/dev/char/%d:%d", rule.Major, rule.Minor)
 			}
+			// systemd will issue a warning if the path we give here doesn't exist.
+			// Since all of this logic is best-effort anyway (we manually set these
+			// rules separately to systemd) we can safely skip entries that don't
+			// have a corresponding path.
+			if _, err := os.Stat(entry.Path); err != nil {
+				logrus.Debugf("skipping device %s for systemd: %s", entry.Path, err)
+				continue
+			}
 		}
-		// systemd will issue a warning if the path we give here doesn't exist.
-		// Since all of this logic is best-effort anyway (we manually set these
-		// rules separately to systemd) we can safely skip entries that don't
-		// have a corresponding path.
-		if _, err := os.Stat(entry.Path); err == nil {
-			deviceAllowList = append(deviceAllowList, entry)
-		}
+		deviceAllowList = append(deviceAllowList, entry)
 	}
 
 	properties = append(properties, newProp("DeviceAllow", deviceAllowList))

tests/integration/dev.bats

@@ -128,3 +128,19 @@ function teardown() {
 	runc exec test_allow_block sh -c 'fdisk -l '"$device"''
 	[ "$status" -eq 0 ]
 }
+
+# https://github.com/opencontainers/runc/issues/3551
+@test "runc exec vs systemctl daemon-reload" {
+	requires systemd root
+
+	runc run -d --console-socket "$CONSOLE_SOCKET" test_exec
+	[ "$status" -eq 0 ]
+
+	runc exec -t test_exec sh -c "ls -l /proc/self/fd/0; echo 123"
+	[ "$status" -eq 0 ]
+
+	systemctl daemon-reload
+
+	runc exec -t test_exec sh -c "ls -l /proc/self/fd/0; echo 123"
+	[ "$status" -eq 0 ]
+}