m/n/c/network: static networking fixes
This fixes three issues with static networking:
It joins interfaces to a master in down state as otherwise Linux
can return an error.
It takes up the automatically-created loopback interface as otherwise we
have no working loopback interface which causes some weird breakage.
It also patches netlink to use RTM_SETLINK instead of RTM_NEWLINK for
reconfiguring interfaces as otherwise Linux sometimes returns an error.
Change-Id: I512e38c6edc1a6d964feb552b1a3995165d74730
Reviewed-on: https://review.monogon.dev/c/monogon/+/1523
Tested-by: Jenkins CI
Reviewed-by: Serge Bazanski <serge@monogon.tech>
diff --git a/third_party/go/patches/netlink-use-rtm_setlink.patch b/third_party/go/patches/netlink-use-rtm_setlink.patch
new file mode 100644
index 0000000..7d05d0e
--- /dev/null
+++ b/third_party/go/patches/netlink-use-rtm_setlink.patch
@@ -0,0 +1,65 @@
+From f367f115a327ca07a294022bc296b4a2fd4e8f8c Mon Sep 17 00:00:00 2001
+From: Lorenz Brun <lorenz@monogon.tech>
+Date: Thu, 6 Apr 2023 23:06:03 +0200
+Subject: [PATCH] Use RTM_SETLINK where appropriate
+
+---
+ link_linux.go | 12 ++++++------
+ 1 file changed, 6 insertions(+), 6 deletions(-)
+
+diff --git a/link_linux.go b/link_linux.go
+index cc80fb6..db89880 100644
+--- a/link_linux.go
++++ b/link_linux.go
+@@ -332,7 +332,7 @@ func BridgeSetMcastSnoop(link Link, on bool) error {
+ func (h *Handle) BridgeSetMcastSnoop(link Link, on bool) error {
+ bridge := link.(*Bridge)
+ bridge.MulticastSnooping = &on
+- return h.linkModify(bridge, unix.NLM_F_ACK)
++ return h.linkModify(bridge, unix.RTM_SETLINK, unix.NLM_F_ACK)
+ }
+
+ func BridgeSetVlanFiltering(link Link, on bool) error {
+@@ -342,7 +342,7 @@ func BridgeSetVlanFiltering(link Link, on bool) error {
+ func (h *Handle) BridgeSetVlanFiltering(link Link, on bool) error {
+ bridge := link.(*Bridge)
+ bridge.VlanFiltering = &on
+- return h.linkModify(bridge, unix.NLM_F_ACK)
++ return h.linkModify(bridge, unix.RTM_SETLINK, unix.NLM_F_ACK)
+ }
+
+ func SetPromiscOn(link Link) error {
+@@ -1197,7 +1197,7 @@ func LinkAdd(link Link) error {
+ // are taken from the parameters in the link object.
+ // Equivalent to: `ip link add $link`
+ func (h *Handle) LinkAdd(link Link) error {
+- return h.linkModify(link, unix.NLM_F_CREATE|unix.NLM_F_EXCL|unix.NLM_F_ACK)
++ return h.linkModify(link, unix.RTM_NEWLINK, unix.NLM_F_CREATE|unix.NLM_F_EXCL|unix.NLM_F_ACK)
+ }
+
+ func LinkModify(link Link) error {
+@@ -1205,10 +1205,10 @@ func LinkModify(link Link) error {
+ }
+
+ func (h *Handle) LinkModify(link Link) error {
+- return h.linkModify(link, unix.NLM_F_REQUEST|unix.NLM_F_ACK)
++ return h.linkModify(link, unix.RTM_SETLINK, unix.NLM_F_REQUEST|unix.NLM_F_ACK)
+ }
+
+-func (h *Handle) linkModify(link Link, flags int) error {
++func (h *Handle) linkModify(link Link, proto, flags int) error {
+ // TODO: support extra data for macvlan
+ base := link.Attrs()
+
+@@ -1373,7 +1373,7 @@ func (h *Handle) linkModify(link Link, flags int) error {
+ return nil
+ }
+
+- req := h.newNetlinkRequest(unix.RTM_NEWLINK, flags)
++ req := h.newNetlinkRequest(proto, flags)
+
+ msg := nl.NewIfInfomsg(unix.AF_UNSPEC)
+ // TODO: make it shorter
+--
+2.39.2
+