vmm: Allow IP configuration on named TAP interfaces

This commit changes existing behavior of named TAP interfaces.
When booting a VM with configuration for a named TAP interface,
cloud-hypervisor will create the interface and apply a given
IP configuration to that interface. If the named interface
already exists on the system, the configuration is NOT overwritten.

Setting the ip and netmask fields in a tap interface configuration
for a named tap interface now works by handing this configuration
to the virtio_devices::Net object when it is created with a name.

This commit also touches net_util to make sure that the ip configuration
of existing TAP interfaces is not modified with ip or netmask handed to
open_tap.

Signed-off-by: Markus Sütter <markus.suetter@secunet.com>
This commit is contained in:
Markus Sütter 2023-12-04 11:21:07 +01:00 committed by Bo Chen
parent 283ae7b33e
commit 0e9513f2b7
2 changed files with 19 additions and 7 deletions

View File

@ -72,6 +72,10 @@ pub fn open_tap(
let mut taps: Vec<Tap> = Vec::new();
let mut ifname: String = String::new();
let vnet_hdr_size = vnet_hdr_len() as i32;
// Check if the given interface exists before we create it.
let tap_existed = if_name.map_or(false, |n| {
Path::new(&format!("/sys/class/net/{n}")).exists()
});
// In case the tap interface already exists, check if the number of
// queues is appropriate. The tap might not support multiqueue while
@ -87,12 +91,20 @@ pub fn open_tap(
Some(name) => Tap::open_named(name, num_rx_q, flags).map_err(Error::TapOpen)?,
None => Tap::new(num_rx_q).map_err(Error::TapOpen)?,
};
// Don't overwrite ip configuration of existing interfaces:
if !tap_existed {
if let Some(ip) = ip_addr {
tap.set_ip_addr(ip).map_err(Error::TapSetIp)?;
}
if let Some(mask) = netmask {
tap.set_netmask(mask).map_err(Error::TapSetNetmask)?;
}
} else {
warn!(
"Tap {} already exists. IP configuration will not be overwritten.",
if_name.unwrap_or_default()
);
}
if let Some(mac) = host_mac {
tap.set_mac_addr(*mac).map_err(Error::TapSetMac)?
} else {

View File

@ -2464,8 +2464,8 @@ impl DeviceManager {
virtio_devices::Net::new(
id.clone(),
Some(tap_if_name),
None,
None,
Some(net_cfg.ip),
Some(net_cfg.mask),
Some(net_cfg.mac),
&mut net_cfg.host_mac,
net_cfg.mtu,