netd: ignore non-directories/symlinks when getting interfaces from /sys/class/net

This prevents /sys/class/net/bonding_masters file (which is present
if kernel is bonding device capable) from being detected as a network
interface and triggering attempts to load netdev-bonding_masters module.

This should eliminate selinux policy violations:
  type=1400 audit(:3): avc: denied { module_request } for comm="netd" kmod="netdev-bonding_masters" scontext=u:r:netd:s0 tcontext=u:r:kernel:s0 tclass=system
  type=1400 audit(:3): avc: denied { module_request } for comm="netd" kmod="netdev-bonding_masters" scontext=u:r:netd:s0 tcontext=u:r:kernel:s0 tclass=system
  type=1400 audit(:4): avc: denied { sys_module } for comm="netd" capability=16 scontext=u:r:netd:s0 tcontext=u:r:netd:s0 tclass=capability
  type=1400 audit(:4): avc: denied { sys_module } for comm="netd" capability=16 scontext=u:r:netd:s0 tcontext=u:r:netd:s0 tclass=capability
  type=1400 audit(:3): avc: denied { module_request } for kmod="netdev-bonding_masters" scontext=u:r:netd:s0 tcontext=u:r:kernel:s0 tclass=system
  type=1400 audit(:4): avc: denied { sys_module } for capability=16 scontext=u:r:netd:s0 tcontext=u:r:netd:s0 tclass=capability
ie.
  netd kernel:system module_request;
  netd self:capability sys_module;

Test: build and a_test libbpf_android_test libnetdbpf_test netd_integration_test netd_unit_test netdutils_test resolv_integration_test resolv_unit_test

Bug: 129670638
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: Ibe10c33b2c6ebe5661d5665f3fde89e540248f72

1 files changed, 1 insertions, 0 deletions

diff --git a/server/InterfaceController.cpp b/server/InterfaceController.cpp
index 78e08d02..bad4ba23 100644
--- a/server/InterfaceController.cpp
+++ b/server/InterfaceController.cpp
@@ -431,6 +431,7 @@ StatusOr<std::vector<std::string>> InterfaceController::getIfaceNames() {
         return statusFromErrno(errno, "Cannot open iface directory");
     }
     while ((de = readdir(d))) {
+        if ((de->d_type != DT_DIR) && (de->d_type != DT_LNK)) continue;
         if (de->d_name[0] == '.') continue;
         ifaceNames.push_back(std::string(de->d_name));
     }