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guest/net: find out eth0 index #226

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2 changes: 1 addition & 1 deletion crates/muvm/Cargo.toml
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Original file line number Diff line number Diff line change
Expand Up @@ -18,7 +18,7 @@ input-linux = { version = "0.7.0", default-features = false, features = [] }
input-linux-sys = { version = "0.9.0", default-features = false, features = [] }
krun-sys = { path = "../krun-sys", version = "1.9.1", default-features = false, features = [] }
log = { version = "0.4.21", default-features = false, features = ["kv"] }
nix = { version = "0.30.0", default-features = false, features = ["event", "fs", "ioctl", "mman", "ptrace", "signal", "socket", "uio", "user"] }
nix = { version = "0.30.0", default-features = false, features = ["event", "fs", "ioctl", "mman", "net", "ptrace", "signal", "socket", "uio", "user"] }
neli = { version = "0.7.0-rc3", default-features = false, features = ["sync"] }
procfs = { version = "0.18.0", default-features = false, features = [] }
rustix = { version = "0.38.34", default-features = false, features = ["fs", "mount", "process", "pty", "std", "stdio", "system", "termios", "use-libc-auxv"] }
Expand Down
89 changes: 58 additions & 31 deletions crates/muvm/src/guest/net.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -16,14 +16,15 @@ use neli::rtnl::{
};
use neli::types::RtBuffer;
use neli::utils::Groups;
use nix::net::if_::if_nametoindex;
use rustix::system::sethostname;

/// Set interface flags for eth0 (interface index 2) with a given mask
fn flags_eth0(rtnl: &NlRouter, mask: Iff, set: Iff) -> Result<()> {
/// Set interface flags with a given mask
fn set_flags(rtnl: &NlRouter, if_index: i32, mask: Iff, set: Iff) -> Result<()> {
let ifinfomsg = IfinfomsgBuilder::default()
.ifi_family(RtAddrFamily::Unspecified)
.ifi_type(Arphrd::Ether)
.ifi_index(2)
.ifi_index(if_index)
.ifi_change(mask)
.ifi_flags(set)
.build()?;
Expand All @@ -34,12 +35,12 @@ fn flags_eth0(rtnl: &NlRouter, mask: Iff, set: Iff) -> Result<()> {
Ok(())
}

/// Set MTU for eth0 (interface index 2)
fn mtu_eth0(rtnl: &NlRouter, mtu: u32) -> Result<()> {
/// Set interface MTU
fn set_mtu(rtnl: &NlRouter, if_index: i32, mtu: u32) -> Result<()> {
let ifinfomsg = IfinfomsgBuilder::default()
.ifi_family(RtAddrFamily::Unspecified)
.ifi_type(Arphrd::Ether)
.ifi_index(2)
.ifi_index(if_index)
.rtattrs(RtBuffer::from_iter([RtattrBuilder::default()
.rta_type(Ifla::Mtu)
.rta_payload(mtu)
Expand All @@ -52,8 +53,8 @@ fn mtu_eth0(rtnl: &NlRouter, mtu: u32) -> Result<()> {
Ok(())
}

/// Add or delete IPv4 routes for eth0 (interface index 2)
fn route4_eth0(rtnl: &NlRouter, what: Rtm, gw: Ipv4Addr) -> Result<()> {
/// Add or delete IPv4 routes
fn update_route4(rtnl: &NlRouter, if_index: i32, what: Rtm, gw: Ipv4Addr) -> Result<()> {
let rtmsg = RtmsgBuilder::default()
.rtm_family(RtAddrFamily::Inet)
.rtm_dst_len(0)
Expand All @@ -67,7 +68,7 @@ fn route4_eth0(rtnl: &NlRouter, what: Rtm, gw: Ipv4Addr) -> Result<()> {
.rtattrs(RtBuffer::from_iter([
RtattrBuilder::default()
.rta_type(Rta::Oif)
.rta_payload(2)
.rta_payload(if_index)
.build()?,
RtattrBuilder::default()
.rta_type(Rta::Dst)
Expand All @@ -89,13 +90,19 @@ fn route4_eth0(rtnl: &NlRouter, what: Rtm, gw: Ipv4Addr) -> Result<()> {
Ok(())
}

/// Add or delete IPv4 addresses for eth0 (interface index 2)
fn addr4_eth0(rtnl: &NlRouter, what: Rtm, addr: Ipv4Addr, prefix_len: u8) -> Result<()> {
/// Add or delete IPv4 addresses
fn update_addr4(
rtnl: &NlRouter,
if_index: i32,
what: Rtm,
addr: Ipv4Addr,
prefix_len: u8,
) -> Result<()> {
let ifaddrmsg = IfaddrmsgBuilder::default()
.ifa_family(RtAddrFamily::Inet)
.ifa_prefixlen(prefix_len)
.ifa_scope(RtScope::Universe)
.ifa_index(2)
.ifa_index(if_index)
.rtattrs(RtBuffer::from_iter([
RtattrBuilder::default()
.rta_type(Ifa::Local)
Expand All @@ -118,10 +125,16 @@ fn addr4_eth0(rtnl: &NlRouter, what: Rtm, addr: Ipv4Addr, prefix_len: u8) -> Res
}

/// Send DISCOVER with Rapid Commit, process ACK, configure address and route
fn do_dhcp(rtnl: &NlRouter) -> Result<()> {
fn do_dhcp(rtnl: &NlRouter, if_index: i32) -> Result<()> {
// Temporary link-local address and route avoid the need for raw sockets
route4_eth0(rtnl, Rtm::Newroute, Ipv4Addr::UNSPECIFIED)?;
addr4_eth0(rtnl, Rtm::Newaddr, Ipv4Addr::new(169, 254, 1, 1), 16)?;
update_route4(rtnl, if_index, Rtm::Newroute, Ipv4Addr::UNSPECIFIED)?;
update_addr4(
rtnl,
if_index,
Rtm::Newaddr,
Ipv4Addr::new(169, 254, 1, 1),
16,
)?;

// Send request (DHCPDISCOVER)
let socket = UdpSocket::bind("0.0.0.0:68").expect("Failed to bind");
Expand Down Expand Up @@ -209,24 +222,36 @@ fn do_dhcp(rtnl: &NlRouter) -> Result<()> {
let prefix_len: u8 = netmask.to_bits().leading_ones() as u8;

// Drop temporary address and route, configure what we got instead
route4_eth0(rtnl, Rtm::Delroute, Ipv4Addr::UNSPECIFIED)?;
addr4_eth0(rtnl, Rtm::Deladdr, Ipv4Addr::new(169, 254, 1, 1), 16)?;

addr4_eth0(rtnl, Rtm::Newaddr, addr, prefix_len)?;
route4_eth0(rtnl, Rtm::Newroute, router)?;

mtu_eth0(rtnl, mtu.into())?;
update_route4(rtnl, if_index, Rtm::Delroute, Ipv4Addr::UNSPECIFIED)?;
update_addr4(
rtnl,
if_index,
Rtm::Deladdr,
Ipv4Addr::new(169, 254, 1, 1),
16,
)?;

update_addr4(rtnl, if_index, Rtm::Newaddr, addr, prefix_len)?;
update_route4(rtnl, if_index, Rtm::Newroute, router)?;

set_mtu(rtnl, if_index, mtu.into())?;
} else {
// Clean up: we're clearly too cool for IPv4
route4_eth0(rtnl, Rtm::Delroute, Ipv4Addr::UNSPECIFIED)?;
addr4_eth0(rtnl, Rtm::Deladdr, Ipv4Addr::new(169, 254, 1, 1), 16)?;
update_route4(rtnl, if_index, Rtm::Delroute, Ipv4Addr::UNSPECIFIED)?;
update_addr4(
rtnl,
if_index,
Rtm::Deladdr,
Ipv4Addr::new(169, 254, 1, 1),
16,
)?;
}

Ok(())
}

/// Wait for SLAAC to complete or fail
fn wait_for_slaac(rtnl: &NlRouter) -> Result<()> {
fn wait_for_slaac(rtnl: &NlRouter, if_index: i32) -> Result<()> {
let mut global_seen = false;
let mut global_wait = true;
let mut ll_seen = false;
Expand All @@ -238,7 +263,7 @@ fn wait_for_slaac(rtnl: &NlRouter) -> Result<()> {
.ifa_family(RtAddrFamily::Inet6)
.ifa_prefixlen(0)
.ifa_scope(RtScope::Universe)
.ifa_index(2)
.ifa_index(if_index)
.build()?;

let recv = rtnl.send(Rtm::Getaddr, NlmF::ROOT, NlPayload::Payload(ifaddrmsg))?;
Expand Down Expand Up @@ -291,26 +316,28 @@ pub fn configure_network() -> Result<()> {
let (rtnl, _) = NlRouter::connect(NlFamily::Route, None, Groups::empty())?;
rtnl.enable_strict_checking(true)?;

let if_index = if_nametoindex("eth0").context("Failed to get interface index for eth0")? as i32;

// Disable neighbour solicitations (dodge DAD), bring up link to start SLAAC
{
// IFF_NOARP | IFF_UP in one shot delays router solicitations, avoid it
flags_eth0(&rtnl, Iff::NOARP, Iff::NOARP)?;
flags_eth0(&rtnl, Iff::UP, Iff::UP)?;
set_flags(&rtnl, if_index, Iff::NOARP, Iff::NOARP)?;
set_flags(&rtnl, if_index, Iff::UP, Iff::UP)?;
}

// Configure IPv4
{
do_dhcp(&rtnl)?;
do_dhcp(&rtnl, if_index)?;
}

// Ensure IPv6 setup is done, if available
{
wait_for_slaac(&rtnl)?;
wait_for_slaac(&rtnl, if_index)?;
}

// Re-enable neighbour solicitations and ARP requests
{
flags_eth0(&rtnl, Iff::NOARP, Iff::empty())?;
set_flags(&rtnl, if_index, Iff::NOARP, Iff::empty())?;
}

Ok(())
Expand Down
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