public_git
/
tart-softnet
mirror of https://github.com/cirruslabs/softnet.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

Add dynamic Softnet policy control (#181) 

* Add dynamic Softnet policy control

* Simplify Softnet policy RPC methods

* Use jsonrpsee types for Softnet policy RPC

* Reject superseded Softnet policy revisions

* Apply Softnet policy updates only after enqueue

* Flush final Softnet response after input EOF

* Signal EOF when disabling Softnet control

* Normalize Softnet default-route isolation

* Keep policy rules on Proxy (#182)

* Simplify Softnet policy protocol

* Bound pipelined Softnet policy responses

* Keep Softnet port forwarding active on control wakes

---------

Co-authored-by: edi-oai <edi@openai.com>
This commit is contained in:
Fedor Kororkov 2026-07-21 16:30:06 -04:00 committed by GitHub
parent 5d6b4b9d0c
commit 08200b7a09
No known key found for this signature in database
GPG Key ID: B5690EEEBB952194
7 changed files with 1279 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

28
Cargo.lock generated
View File

@ -1414,6 +1414,18 @@ dependencies = [
"wasm-bindgen",
]
[[package]]
name = "jsonrpsee-types"
version = "0.26.0"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "bc88ff4688e43cc3fa9883a8a95c6fa27aa2e76c96e610b737b6554d650d7fd5"
dependencies = [
"http 1.1.0",
"serde",
"serde_json",
"thiserror 2.0.12",
]
[[package]]
name = "language-tags"
version = "0.3.2"
@ -2417,14 +2429,15 @@ dependencies = [
[[package]]
name = "serde_json"
version = "1.0.128"
version = "1.0.151"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "6ff5456707a1de34e7e37f2a6fd3d3f808c318259cbd01ab6377795054b483d8"
checksum = "c841b55ecdae098c80dcae9cf767f6f8a0c2cdb3416bbef72181df4d0fe73f14"
dependencies = [
"itoa",
"memchr",
"ryu",
"serde",
"serde_core",
"zmij",
]
[[package]]
@ -2568,6 +2581,7 @@ dependencies = [
"dhcproto",
"ip_network",
"ipnet",
"jsonrpsee-types",
"libc",
"log",
"mac_address",
@ -2579,6 +2593,8 @@ dependencies = [
"privdrop",
"sentry",
"sentry-anyhow",
"serde",
"serde_json",
"serial_test",
"smoltcp",
"system-configuration",
@ -3747,3 +3763,9 @@ dependencies = [
"quote",
"syn 2.0.117",
]
[[package]]
name = "zmij"
version = "1.0.23"
source = "registry+https://github.com/rust-lang/crates.io-index"
checksum = "29666d0abbfad1e3dc4dcf6144730dd3a3ab225bbbdac83319345b1b44ccfc1b"

3
Cargo.toml
View File

@ -34,6 +34,9 @@ oslog = "0.2.0"
log = "0.4.29"
serial_test = "3"
coarsetime = "0.1.37"
serde = { version = "1", features = ["derive"] }
serde_json = "1"
jsonrpsee-types = "0.26"
[profile.release]
debug = true

15
README.md
View File

@ -43,3 +43,18 @@ For proper functioning, Softnet binary requires two things:
## Running
Softnet is started and managed automatically by Tart if `--net-softnet` flag is provided when calling `tart run`.
### Dynamic network policy
Softnet can update the running VM's IPv4 egress policy without restarting the VM. Pass a connected Unix stream socket as `--control-fd` to enable a newline-delimited [JSON-RPC 2.0](https://www.jsonrpc.org/specification) control channel. The socket is duplex and must be separate from `--vm-fd`, which carries VM packets.
The supported methods are `softnet.policy.get` and `softnet.policy.set`. A complete policy update looks like this (each request and response occupies one line):
```json
{"jsonrpc":"2.0","id":"42","method":"softnet.policy.set","params":{"allow":["@host","10.0.0.0/8"],"block":["0.0.0.0/0"]}}
{"jsonrpc":"2.0","id":"42","result":{"allow":["10.0.0.0/8","@host"],"block":["0.0.0.0/0"],"ruleCount":3}}
```
Every request must include a non-null string (at most 256 bytes) or non-negative integer `id`; notifications are rejected so policy changes always have an acknowledgment. Policy updates are atomic: all targets are parsed and a new prefix map is built before the active policy changes. Longest-prefix matching and block precedence for identical prefixes are preserved. Targets are normalized and deduplicated. A policy update may contain at most 4096 combined allow/block targets, and a request frame may not exceed 1 MiB.
Use `block=["0.0.0.0/0"]` with specific allow targets for a default-deny policy. Closing the control socket leaves the last accepted policy active.

21
lib/poller.rs
View File

@ -12,6 +12,7 @@ pub struct Poller<'poller> {
timeout: Duration,
vm_fd: BorrowedFd<'poller>,
host_fd: BorrowedFd<'poller>,
control_fd: Option<BorrowedFd<'poller>>,
}
#[derive(IntoPrimitive)]
@ -19,6 +20,7 @@ pub struct Poller<'poller> {
enum EventKey {
VM,
Host,
Control,
Interrupt,
}
@ -26,6 +28,7 @@ impl Poller<'_> {
pub fn new<'poller>(
vm_fd: RawFd,
host_fd: RawFd,
control_fd: Option<RawFd>,
timeout: Duration,
) -> Result<Poller<'poller>> {
let poller = polling::Poller::new()?;
@ -36,6 +39,7 @@ impl Poller<'_> {
timeout,
vm_fd: unsafe { BorrowedFd::borrow_raw(vm_fd) },
host_fd: unsafe { BorrowedFd::borrow_raw(host_fd) },
control_fd: control_fd.map(|fd| unsafe { BorrowedFd::borrow_raw(fd) }),
})
}
@ -46,6 +50,14 @@ impl Poller<'_> {
self.vm_interest(),
PollMode::Edge,
)?;
if let Some(control_fd) = self.control_fd {
self.poller.add_with_mode(
control_fd.as_raw_fd(),
polling::Event::all(EventKey::Control.into()),
PollMode::Edge,
)?;
}
self.poller.add_with_mode(
self.host_fd.as_raw_fd(),
self.host_interest(),
@ -79,10 +91,17 @@ impl Poller<'_> {
.events
.iter()
.any(|ev| ev.key == Into::<usize>::into(EventKey::Interrupt));
Ok((vm_readable, host_readable, interrupt))
}
pub fn remove_control(&mut self) -> Result<()> {
if let Some(control_fd) = self.control_fd.take() {
self.poller.delete(control_fd)?;
}
Ok(())
}
fn vm_interest(&self) -> polling::Event {
polling::Event::readable(EventKey::VM.into())
}

1132
lib/proxy/control.rs Normal file
View File

File diff suppressed because it is too large Load Diff

60
lib/proxy/mod.rs
View File

@ -1,3 +1,4 @@
mod control;
mod exposed_port;
mod host;
mod port_forwarder;
@ -10,6 +11,7 @@ use crate::host::NetType;
use crate::poller::Poller;
use crate::vm::VM;
use anyhow::Result;
use control::Control;
pub use exposed_port::ExposedPort;
use ipnet::Ipv4Net;
use mac_address::MacAddress;
@ -29,6 +31,7 @@ pub struct Proxy<'proxy> {
vm_mac_address: smoltcp::wire::EthernetAddress,
dhcp_snooper: DhcpSnooper,
rules: PrefixMap<Ipv4Net, Action>,
control: Option<Control>,
enobufs_encountered: bool,
port_forwarder: PortForwarder,
}
@ -65,6 +68,7 @@ impl Proxy<'_> {
allow: Vec<Target>,
block: Vec<Target>,
exposed_ports: Vec<ExposedPort>,
control_fd: Option<RawFd>,
) -> Result<Proxy<'proxy>> {
let vm = VM::new(vm_fd)?;
let host = Host::new(
@ -72,7 +76,17 @@ impl Proxy<'_> {
!allow.contains(&Target::Prefix(Ipv4Net::zero())),
)?;
let poller_timeout = Duration::from_millis(100);
let poller = Poller::new(vm.as_raw_fd(), host.as_raw_fd(), poller_timeout)?;
let control = control_fd
.map(|control_fd| {
Control::new(control_fd, host.gateway_ip, allow.clone(), block.clone())
})
.transpose()?;
let poller = Poller::new(
vm.as_raw_fd(),
host.as_raw_fd(),
control.as_ref().map(AsRawFd::as_raw_fd),
poller_timeout,
)?;
// Craft packet filter rules
//
@ -105,6 +119,7 @@ impl Proxy<'_> {
vm_mac_address: smoltcp::wire::EthernetAddress(vm_mac_address.bytes()),
dhcp_snooper: DhcpSnooper::new(poller_timeout),
rules,
control,
enobufs_encountered: false,
port_forwarder: PortForwarder::new(exposed_ports),
})
@ -129,6 +144,10 @@ impl Proxy<'_> {
// Update coarse time for the DHCP snooper
coarsetime::Instant::update();
// Service control on every wake (including timeouts) so a bounded read or a pending
// response continues making progress even when no new edge is generated.
self.service_control();
if vm_readable {
self.read_from_vm(buf.as_mut_slice())?;
}
@ -153,6 +172,8 @@ impl Proxy<'_> {
}
fn read_from_vm(&mut self, buf: &mut [u8]) -> Result<()> {
let mut packets_read = 0;
loop {
match self.vm.read(buf) {
Ok(n) => {
@ -162,6 +183,12 @@ impl Proxy<'_> {
if let Ok(frame) = EthernetFrame::new_checked(&buf[..n]) {
self.process_frame_from_vm(frame)?;
}
packets_read += 1;
if packets_read == 128 {
self.service_control();
packets_read = 0;
}
}
Err(err) => {
if err.kind() == ErrorKind::WouldBlock {
@ -186,6 +213,8 @@ impl Proxy<'_> {
self.process_frame_from_host(&pkt)?;
}
}
self.service_control();
}
Err(err) => {
if let vmnet::Error::VmnetReadNothing = err {
@ -197,6 +226,34 @@ impl Proxy<'_> {
}
}
}
fn service_control(&mut self) {
let Some(control) = self.control.as_mut() else {
return;
};
let keep_open = match control.service(&mut self.rules) {
Ok(keep_open) => keep_open,
Err(err) => {
log::warn!("disabling Softnet control socket: {err:#}");
false
}
};
if keep_open {
return;
}
if let Err(err) = self.poller.remove_control() {
log::warn!("failed to remove Softnet control socket from the poller: {err:#}");
}
if let Some(control) = self.control.take()
&& let Err(err) = control.shutdown()
{
log::warn!("failed to shut down Softnet control socket: {err:#}");
}
}
}
#[cfg(test)]
@ -295,6 +352,7 @@ mod tests {
.map(|cidr| cidr.parse().unwrap())
.collect(),
Vec::default(),
None,
)
.unwrap();

25
src/main.rs
View File

@ -31,6 +31,13 @@ struct Args {
)]
vm_fd: c_int,
#[clap(
long,
value_parser = parse_vm_fd,
help = "connected Unix stream FD for newline-delimited JSON-RPC policy control"
)]
control_fd: Option<c_int>,
#[clap(long, help = "MAC address to enforce for the VM")]
vm_mac_address: mac_address::MacAddress,
@ -203,6 +210,7 @@ fn try_main() -> anyhow::Result<()> {
args.allow,
args.block,
args.expose,
args.control_fd.map(|fd| fd as RawFd),
)
.context("failed to initialize proxy")?;
@ -286,4 +294,21 @@ mod tests {
.contains("file descriptor must be non-negative")
);
}
#[test]
fn test_cli_rejects_negative_control_fd_before_startup() {
let error = Args::try_parse_from([
"softnet",
"--vm-fd=0",
"--control-fd=-1",
"--vm-mac-address=02:00:00:00:00:01",
])
.unwrap_err();
assert!(
error
.to_string()
.contains("file descriptor must be non-negative")
);
}
}