Jing Chen 35d3c6eb73 Update MTU value for ethernet devices. ...

L2 MTU includes both payload and ethernet header. gVisor has supported setting
data link layer MTU, it will be  up to users to set up proper value for a
device's MTU if a larger value is expected.

By doing the change, gVisor will be consistent with runc:

```shell
# runc
root@cec4d7238802:/# ip link set dev lo mtu 1234
root@cec4d7238802:/# ip link list dev lo
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 1234 qdisc noqueue state UNKNOWN mode DEFAULT group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00

# runsc before the change.
root@7cd89278d414:/# ip link set dev lo mtu 1234
root@7cd89278d414:/# ip link list dev lo
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 1220
    link/loopback 00:00:00:00:00:00 brd ff:ff:ff:ff:ff:ff

# runsc after the change.
root@e811c5851226:/# ip link set dev lo mtu 1234
root@e811c5851226:/# ip link list dev lo
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 1234
    link/loopback 00:00:00:00:00:00 brd ff:ff:ff:ff:ff:ff
```
PiperOrigin-RevId: 684746090

2024-10-11 01:36:07 -07:00

..

linux

Update MTU value for ethernet devices.

2024-10-11 01:36:07 -07:00

BUILD

Implement RTM_NEWROUTE in netstack to create/replace a route.

2024-07-09 18:04:19 -07:00