sd-device/networkd: unify code to get a socket for issuing netdev ioctls on

As suggested here:

https://github.com/systemd/systemd/pull/4296#issuecomment-251911349

Let's try AF_INET first as socket, but let's fall back to AF_NETLINK, so that
we can use a protocol-independent socket here if possible. This has the benefit
that our code will still work even if AF_INET/AF_INET6 is made unavailable (for
exmple via seccomp), at least on current kernels.

1 files changed, 3 insertions, 2 deletions

diff --git a/src/libsystemd/sd-device/sd-device.c b/src/libsystemd/sd-device/sd-device.c
index 0c4ad966bd..411453e08d 100644
--- a/src/libsystemd/sd-device/sd-device.c
+++ b/src/libsystemd/sd-device/sd-device.c
@@ -36,6 +36,7 @@
 #include "parse-util.h"
 #include "path-util.h"
 #include "set.h"
+#include "socket-util.h"
 #include "stat-util.h"
 #include "string-util.h"
 #include "strv.h"
@@ -629,9 +630,9 @@ _public_ int sd_device_new_from_device_id(sd_device **ret, const char *id) {
                 if (r < 0)
                         return r;
 
-                sk = socket(PF_INET, SOCK_DGRAM, 0);
+                sk = socket_ioctl_fd();
                 if (sk < 0)
-                        return -errno;
+                        return sk;
 
                 r = ioctl(sk, SIOCGIFNAME, &ifr);
                 if (r < 0)