add support for setting up routing inside the netns

Cargo.lock

@@ -82,6 +82,15 @@ version = "0.2.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "613afe47fcd5fac7ccf1db93babcb082c5994d996f20b8b159f2ad1658eb5724"
 
+[[package]]
+name = "cidr"
+version = "0.3.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "579504560394e388085d0c080ea587dfa5c15f7e251b4d5247d1e1a61d1d6928"
+dependencies = [
+ "serde",
+]
+
 [[package]]
 name = "clap"
 version = "4.5.58"
@@ -509,6 +518,7 @@ dependencies = [
 name = "netnsd"
 version = "0.2.0"
 dependencies = [
+ "cidr",
  "clap",
  "either",
  "futures",

Cargo.toml

@@ -23,6 +23,7 @@ either = "1.15.0"
 uzers = "0.12.2"
 sysinfo = "0.38.1"
 landlock = "0.4.4"
+cidr = { version = "0.3.2", features = ["serde"] }
 
 [dev-dependencies]
 serde_test = "1.0.177"

README.md

@@ -8,6 +8,7 @@ A declarative manager for Linux network namespaces.
 - Hot reloading of configuration
 - Port forwarding into or out of the namespace
 - Moving network devices to the namespace
+- Setting up routing inside the namespace
 
 ## Usage
 
@@ -57,6 +58,11 @@ name = "test"
 # move existing devices into the namespace
 devices = ["somelink"]
 
+# create a route inside the namespace
+[[namespace.route]]
+destination = "default" # either "default" or an ip range in CIDR notation
+device = "somelink"
+
 # You can define any number of port forwards to setup into the namespace
 [[namespace.forward]]
 # port, address or socket outside the namespace to listen on

config.sample.toml

@@ -5,6 +5,11 @@ name = "test"
 # move existing devices into the namespace
 devices = ["somelink"]
 
+# create a route inside the namespace
+[[namespace.route]]
+destination = "default" # either "default" or an ip range in CIDR notation
+device = "somelink"
+
 # You can define any number of port forwards to setup into the namespace
 [[namespace.forward]]
 # port, address or socket outside the namespace to listen on

nix/module.nix

@@ -60,6 +60,22 @@ in {
             default = [];
             description = "devices to move into the namespace";
           };
+          route = mkOption {
+            type = types.listOf (types.submodule ({config, ...}: {
+              options = {
+                device = mkOption {
+                  type = types.str;
+                  description = "device to route the traffic trough";
+                };
+                destination = mkOption {
+                  type = types.str;
+                  description = "What traffic to route. Either \"default\" or an ip range in CIDR notation";
+                };
+              };
+            }));
+            description = "routes to setup inside the namespace";
+            default = [];
+          };
         };
       }));
       description = "namespaces to setup";

src/config/mod.rs

@@ -5,10 +5,15 @@ mod target;
 pub use crate::config::name::{DeviceName, NamespaceName};
 pub use crate::config::source::ForwardSource;
 pub use crate::config::target::ForwardTarget;
-use serde::Deserialize;
+use cidr::AnyIpCidr;
+use serde::de::Error;
+use serde::{Deserialize, Deserializer};
+use std::borrow::Cow;
 use std::collections::HashSet;
+use std::fmt::{Display, Formatter};
 use std::fs::read_to_string;
 use std::path::{Path, PathBuf};
+use std::str::FromStr;
 use thiserror::Error;
 use toml::from_str;
 
@@ -84,6 +89,8 @@ pub struct NamespaceConfig {
     pub forward: Vec<ForwardConfig>,
     #[serde(default)]
     pub devices: Vec<DeviceName>,
+    #[serde(default, rename = "route")]
+    pub routes: Vec<RouteConfig>,
 }
 
 #[derive(Deserialize, Debug)]
@@ -94,6 +101,27 @@ pub struct ForwardConfig {
     pub reverse: bool,
 }
 
+#[derive(Deserialize, Debug, PartialEq, Clone)]
+pub struct RouteConfig {
+    #[serde(deserialize_with = "parse_cidr")]
+    pub destination: AnyIpCidr,
+    pub device: DeviceName,
+}
+
+impl Display for RouteConfig {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        write!(f, "{} dev {}", self.destination, self.device)
+    }
+}
+
+fn parse_cidr<'de, D: Deserializer<'de>>(deserializer: D) -> Result<AnyIpCidr, D::Error> {
+    let str = Cow::<'de, str>::deserialize(deserializer)?;
+    match str.as_ref() {
+        "default" => Ok(AnyIpCidr::Any),
+        str => AnyIpCidr::from_str(str).map_err(D::Error::custom),
+    }
+}
+
 #[derive(Debug, Error)]
 pub enum ConfigError {
     #[error("Error while reading config from {}: {error:#}", path.display())]

src/config/name.rs

@@ -186,7 +186,7 @@ fn validate_name(name: &str) -> bool {
 
 #[test]
 fn test_de() {
-    use serde_test::{assert_de_tokens, assert_de_tokens_error, Token};
+    use serde_test::{Token, assert_de_tokens, assert_de_tokens_error};
 
     assert_de_tokens(&NamespaceName("foo".into()), &[Token::String("foo")]);
 

src/config/source.rs

@@ -114,7 +114,7 @@ pub struct InvalidForwardSource {
 
 #[test]
 fn test_de() {
-    use serde_test::{assert_de_tokens, assert_de_tokens_error, Token};
+    use serde_test::{Token, assert_de_tokens, assert_de_tokens_error};
 
     let addr_str = "127.0.0.1:80";
     let addr = SocketAddr::from_str("127.0.0.1:80").unwrap();

src/config/target.rs

@@ -111,7 +111,7 @@ pub struct InvalidForwardTarget {
 
 #[test]
 fn test_de() {
-    use serde_test::{assert_de_tokens, assert_de_tokens_error, Token};
+    use serde_test::{Token, assert_de_tokens, assert_de_tokens_error};
 
     let addr_str = "127.0.0.1:80";
     let addr = SocketAddr::from_str("127.0.0.1:80").unwrap();

src/daemon.rs

@@ -1,4 +1,6 @@
-use crate::config::{Config, DeviceName, ForwardConfig, NamespaceConfig, NamespaceName};
+use crate::config::{
+    Config, DeviceName, ForwardConfig, NamespaceConfig, NamespaceName, RouteConfig,
+};
 use crate::link::{LinkError, LinkManager};
 use crate::namespace::{
     NamespaceEnterError, NamespaceError, NamespaceHandle, NamespaceHandleError, NetNs,
@@ -128,6 +130,7 @@ impl State {
             let config = config.get_namespace(namespace.name()).unwrap();
             namespace.update_proxies(config)?;
             namespace.update_devices(config)?;
+            namespace.update_links(config)?;
         }
 
         Ok(())
@@ -144,6 +147,7 @@ struct ActiveNamespace {
     ns: NetNs,
     proxies: Vec<ActiveProxy>,
     devices: Vec<DeviceName>,
+    routes: Vec<RouteConfig>,
 }
 
 impl ActiveNamespace {
@@ -154,6 +158,7 @@ impl ActiveNamespace {
             ns,
             proxies: Vec::default(),
             devices: Vec::default(),
+            routes: Vec::default(),
         })
     }
 
@@ -212,6 +217,52 @@ impl ActiveNamespace {
         Ok(())
     }
 
+    pub fn update_links(&mut self, config: &NamespaceConfig) -> Result<(), DaemonError> {
+        let removed: Vec<_> = self
+            .routes
+            .extract_if(.., |existing| {
+                !config.routes.iter().any(|new| existing == new)
+            })
+            .collect();
+
+        let mut added = Vec::new();
+        for new in &config.routes {
+            if !self.has_route(new) {
+                added.push(new.clone());
+            }
+        }
+
+        self.ns.handle().run_in(|| {
+            let link_manager = LinkManager::new()?;
+            for link in link_manager.get_links()?.flatten() {
+                if let Some(route) = removed
+                    .iter()
+                    .find(|route| route.device == link.name.as_str())
+                {
+                    info!(namespace = %config.name, %route, "deleting route");
+                    link_manager.delete_route(&link, route.destination)?;
+                }
+            }
+
+            for link in link_manager.get_links()?.flatten() {
+                if let Some(route) = added
+                    .iter()
+                    .find(|route| route.device == link.name.as_str())
+                {
+                    info!(namespace = %config.name, %route, "adding route");
+                    link_manager.add_route(&link, route.destination)?;
+                }
+            }
+            Ok::<_, DaemonError>(())
+        })??;
+
+        for new in added {
+            self.routes.push(new);
+        }
+
+        Ok(())
+    }
+
     fn has_forward(&self, config: &ForwardConfig) -> bool {
         self.proxies.iter().any(|existing| existing == config)
     }
@@ -220,6 +271,10 @@ impl ActiveNamespace {
         self.devices.iter().any(|existing| existing == name)
     }
 
+    fn has_route(&self, route: &RouteConfig) -> bool {
+        self.routes.iter().any(|existing| existing == route)
+    }
+
     pub fn name(&self) -> &NamespaceName {
         self.ns.name()
     }

src/link.rs

@@ -1,26 +1,27 @@
+use cidr::{AnyIpCidr, Family};
 use neli::consts::nl::NlmF;
-use neli::consts::rtnl::Ifla;
-use neli::consts::rtnl::RtAddrFamily;
 use neli::consts::rtnl::Rtm;
+use neli::consts::rtnl::{Ifla, RtScope, RtTable, Rta};
+use neli::consts::rtnl::{RtAddrFamily, Rtn, Rtprot};
 use neli::consts::socket::NlFamily;
 use neli::err::RouterError;
 use neli::nl::NlPayload;
 use neli::router::synchronous::NlRouter;
-use neli::rtnl::IfinfomsgBuilder;
-use neli::rtnl::{Ifinfomsg, RtattrBuilder};
+use neli::rtnl::{Ifinfomsg, RtattrBuilder, Rtmsg};
+use neli::rtnl::{IfinfomsgBuilder, RtmsgBuilder};
 use neli::types::{Buffer, RtBuffer};
 use neli::utils::Groups;
 use nix::libc::c_int;
-use std::fmt::Debug;
+use std::fmt::{Debug, Display, Formatter};
 use std::os::fd::AsRawFd;
 use thiserror::Error;
-use tracing::info;
+use tracing::{info, instrument};
 
 #[derive(Debug, Error)]
 pub enum LinkError {
-    #[error("Failed to communicate with netlink:")]
+    #[error("Failed to communicate with netlink: {0}")]
     Netlink(String),
-    #[error("Failed to parse netlink response")]
+    #[error("Failed to parse netlink response: {0}")]
     Parse(String),
     #[error("Link not found: {0}")]
     NotFound(String),
@@ -46,6 +47,12 @@ pub struct Link {
     pub name: String,
 }
 
+impl Display for Link {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        f.write_str(&self.name)
+    }
+}
+
 impl Link {
     fn msg_builder(&self) -> IfinfomsgBuilder {
         IfinfomsgBuilder::default()
@@ -112,7 +119,7 @@ impl LinkManager {
         info_attrs.push(
             RtattrBuilder::default()
                 .rta_type(Ifla::NetNsFd)
-                .rta_payload(Buffer::from(ns_handle.to_ne_bytes().as_slice()))
+                .rta_payload(ns_handle)
                 .build()
                 .expect("invalid rtattr"),
         );
@@ -135,6 +142,47 @@ impl LinkManager {
         )?;
         Ok(())
     }
+
+    #[instrument(skip_all, fields(link = %link, destination = %destination))]
+    pub fn add_route(&self, link: &Link, destination: AnyIpCidr) -> Result<(), LinkError> {
+        let rt_msg = route_message_for(link, destination);
+
+        let res = self.router.send::<_, _, Rtm, Rtmsg>(
+            Rtm::Newroute,
+            NlmF::CREATE | NlmF::EXCL | NlmF::REQUEST | NlmF::ACK,
+            NlPayload::Payload(rt_msg),
+        )?;
+
+        for msg in res {
+            match msg {
+                Err(RouterError::Nlmsgerr(err)) if *err.error() == -17 => {
+                    info!("route already exists");
+                    // already exists
+                }
+                Err(err) => {
+                    return Err(err.into());
+                }
+                _ => {}
+            }
+        }
+        Ok(())
+    }
+
+    #[instrument(skip_all, fields(link = %link, destination = %destination))]
+    pub fn delete_route(&self, link: &Link, destination: AnyIpCidr) -> Result<(), LinkError> {
+        let rt_msg = route_message_for(link, destination);
+
+        let res = self.router.send::<_, _, Rtm, Rtmsg>(
+            Rtm::Delroute,
+            NlmF::REQUEST | NlmF::ACK,
+            NlPayload::Payload(rt_msg),
+        )?;
+
+        for msg in res {
+            msg?;
+        }
+        Ok(())
+    }
 }
 
 /// Set a link to UP
@@ -147,6 +195,7 @@ pub fn link_up(link_name: &str) -> Result<(), LinkError> {
 /// Move a link into a namespace
 pub fn move_link_into<Fd: AsRawFd>(link_name: &str, namespace: &Fd) -> Result<(), LinkError> {
     let manager = LinkManager::new()?;
+    // todo, might already be in target ns
     let link = manager.get_link(link_name)?;
     info!(name = &link.name, "moving link into namespace");
     manager.move_link(&link, namespace)
@@ -163,3 +212,54 @@ pub fn move_all_links<Fd: AsRawFd>(namespace: &Fd) -> Result<(), LinkError> {
     }
     Ok::<_, LinkError>(())
 }
+
+fn route_message_for(link: &Link, destination: AnyIpCidr) -> Rtmsg {
+    let mut info_attrs = RtBuffer::<Rta, Buffer>::new();
+    match &destination {
+        AnyIpCidr::V4(addr) => {
+            info_attrs.push(
+                RtattrBuilder::default()
+                    .rta_type(Rta::Dst)
+                    .rta_payload(addr.first_address().octets())
+                    .build()
+                    .expect("invalid rtattr"),
+            );
+        }
+        AnyIpCidr::V6(addr) => {
+            info_attrs.push(
+                RtattrBuilder::default()
+                    .rta_type(Rta::Dst)
+                    .rta_payload(addr.first_address().octets())
+                    .build()
+                    .expect("invalid rtattr"),
+            );
+        }
+        _ => {}
+    }
+    info_attrs.push(
+        RtattrBuilder::default()
+            .rta_type(Rta::Oif)
+            .rta_payload(link.index)
+            .build()
+            .expect("invalid rtattr"),
+    );
+
+    let family = match &destination.family() {
+        None => RtAddrFamily::Inet,
+        Some(Family::Ipv4) => RtAddrFamily::Inet,
+        Some(Family::Ipv6) => RtAddrFamily::Inet6,
+    };
+
+    RtmsgBuilder::default()
+        .rtm_table(RtTable::Main)
+        .rtm_scope(RtScope::Universe)
+        .rtm_family(family)
+        .rtattrs(info_attrs)
+        .rtm_src_len(0)
+        .rtm_tos(0)
+        .rtm_protocol(Rtprot::Boot)
+        .rtm_type(Rtn::Unicast)
+        .rtm_dst_len(destination.network_length().unwrap_or_default())
+        .build()
+        .expect("rt msg")
+}

src/main.rs

@@ -5,10 +5,10 @@ use crate::proxy::proxy;
 use crate::up::up;
 use clap::{Parser, Subcommand};
 use main_error::MainResult;
-use std::path::PathBuf;
 use nix::errno::Errno;
-use nix::sys::signal::{kill, Signal};
+use nix::sys::signal::{Signal, kill};
 use nix::unistd::Pid;
+use std::path::PathBuf;
 use sysinfo::{ProcessRefreshKind, RefreshKind, System, UpdateKind};
 use tracing::{error, info, warn};
 
@@ -94,10 +94,12 @@ fn reload() -> MainResult {
             match kill(Pid::from_raw(proc.pid().as_u32() as i32), Signal::SIGHUP) {
                 Ok(_) => {
                     info!("Sent reload command to daemon")
-                },
+                }
                 Err(Errno::EPERM) => {
-                    error!("Sending signal not permitted, try are you running the command as root?");
-                },
+                    error!(
+                        "Sending signal not permitted, try are you running the command as root?"
+                    );
+                }
                 Err(error) => {
                     error!(%error, "Unexpected error");
                 }

src/namespace/handle.rs

@@ -1,6 +1,6 @@
 use crate::namespace::NamespaceEnterError;
 use nix::errno::Errno;
-use nix::sched::{setns, CloneFlags};
+use nix::sched::{CloneFlags, setns};
 use std::fs::File;
 use std::io::Error as IoError;
 use std::os::fd::{AsFd, AsRawFd, BorrowedFd, OwnedFd, RawFd};

src/namespace/mod.rs

@@ -2,13 +2,13 @@ mod handle;
 mod raw;
 
 use crate::config::{DeviceName, NamespaceName};
-use crate::link::{link_up, move_all_links, move_link_into, LinkError};
+use crate::link::{LinkError, link_up, move_all_links, move_link_into};
 pub use crate::namespace::handle::{NamespaceHandle, NamespaceHandleError};
-use crate::namespace::raw::{create_network_namespace, NamespaceSetupError};
+use crate::namespace::raw::{NamespaceSetupError, create_network_namespace};
 use either::Either;
 use nix::errno::Errno;
-use nix::mount::{mount, umount2, MntFlags, MsFlags};
-use std::fs::{create_dir, read_dir, remove_file, File};
+use nix::mount::{MntFlags, MsFlags, mount, umount2};
+use std::fs::{File, create_dir, read_dir, remove_file};
 use std::io::{Error as IoError, ErrorKind};
 use std::iter::empty;
 use std::os::unix::fs::symlink;
@@ -162,9 +162,7 @@ impl NetNs {
     pub fn delete(self) -> Result<(), NamespaceError> {
         let parent_namespace = NamespaceHandle::parent()?;
 
-        self.handle.run_in(|| {
-            move_all_links(&parent_namespace)
-        })??;
+        self.handle.run_in(|| move_all_links(&parent_namespace))??;
         let name = self.path.file_name().unwrap().to_str().unwrap();
         info!(name, "deleting network namespace");
         match umount2(&self.path, MntFlags::MNT_DETACH) {

src/namespace/raw.rs

@@ -1,7 +1,7 @@
 use nix::errno::Errno;
-use nix::sched::{clone, CloneFlags};
+use nix::sched::{CloneFlags, clone};
 use nix::sys::signal::Signal;
-use nix::sys::wait::{waitpid, WaitStatus};
+use nix::sys::wait::{WaitStatus, waitpid};
 use std::path::PathBuf;
 use thiserror::Error;
 

src/proxy/mod.rs

@@ -3,7 +3,12 @@ mod tcp;
 use crate::config::{ForwardConfig, ForwardSource, ForwardTarget, NamespaceName};
 use crate::proxy::tcp::Proxy;
 use futures::future::AbortHandle;
+use landlock::{
+    ABI, Access, AccessFs, AccessNet, NetPort, Ruleset, RulesetAttr, RulesetCreatedAttr,
+    RulesetError, RulesetStatus,
+};
 use main_error::MainResult;
+use nix::errno::Errno;
 use nix::sched::{CloneFlags, setns};
 use nix::sys::signal::{SIGINT, kill};
 use nix::unistd::{Gid, Pid, Uid, setgid, setuid};
@@ -13,8 +18,6 @@ use std::net::SocketAddr;
 use std::path::{Path, PathBuf};
 use std::process::{Child, Command};
 use std::thread::spawn;
-use landlock::{Access, AccessFs, AccessNet, NetPort, Ruleset, RulesetAttr, RulesetCreatedAttr, RulesetError, RulesetStatus, ABI};
-use nix::errno::Errno;
 use thiserror::Error;
 use tokio::runtime::Builder;
 use tokio::signal::ctrl_c;

src/proxy/tcp.rs

@@ -1,6 +1,6 @@
 /// Loosely based on https://github.com/fooker/netns-proxy/blob/main/src/tcp.rs
-use crate::config::{ForwardTarget, ForwardSource};
-use crate::proxy::{ProxyError};
+use crate::config::{ForwardSource, ForwardTarget};
+use crate::proxy::ProxyError;
 use futures::TryStreamExt;
 use futures::stream::{AbortRegistration, Abortable};
 use std::fs::{remove_file, set_permissions};
@@ -56,28 +56,18 @@ impl Proxy {
         })?;
         debug!("Created TCP socket");
 
-        Ok(Self {
-            socket,
-        })
+        Ok(Self { socket })
     }
 
     pub async fn run(self, target: ForwardTarget, abort: AbortRegistration) {
         match self.socket {
-            ProxyListener::Tcp(socket) => {
-                run_tcp(socket, target.addr, abort).await
-            }
-            ProxyListener::Unix(socket) => {
-                run_unix(socket, target.addr, abort).await
-            }
+            ProxyListener::Tcp(socket) => run_tcp(socket, target.addr, abort).await,
+            ProxyListener::Unix(socket) => run_unix(socket, target.addr, abort).await,
         }
     }
 }
 
-async fn run_tcp(
-    socket: TcpListener,
-    target: SocketAddr,
-    abort: AbortRegistration,
-) {
+async fn run_tcp(socket: TcpListener, target: SocketAddr, abort: AbortRegistration) {
     let accepts = TcpListenerStream::new(socket).map_err(|error| ProxyError::Accept { error });
     let mut accepts = pin!(Abortable::new(accepts, abort));
     while let Some(client) = accepts.next().await {
@@ -94,11 +84,7 @@ async fn run_tcp(
     }
 }
 
-async fn run_unix(
-    socket: UnixListener,
-    target: SocketAddr,
-    abort: AbortRegistration,
-) {
+async fn run_unix(socket: UnixListener, target: SocketAddr, abort: AbortRegistration) {
     let accepts = UnixListenerStream::new(socket).map_err(|error| ProxyError::Accept { error });
     let mut accepts = pin!(Abortable::new(accepts, abort));
     while let Some(client) = accepts.next().await {

src/up.rs

@@ -1,4 +1,5 @@
 use crate::config::{Config, NamespaceName};
+use crate::link::{LinkError, LinkManager};
 use crate::namespace::NetNs;
 use main_error::MainResult;
 use tracing::error;
@@ -24,6 +25,14 @@ pub fn up(config: Config) -> MainResult {
                 error!(%error, "failed to move device into namespace");
             }
         }
+        for route in new.routes {
+            namespace.handle().run_in(|| {
+                let manager = LinkManager::new()?;
+                let link = manager.get_link(&route.device)?;
+                manager.add_route(&link, route.destination)?;
+                Ok::<_, LinkError>(())
+            })??;
+        }
     }
 
     Ok(())