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use crate::{Batch, Rule, nft_expr, sys::libc};
use crate::expr::{LogGroup, LogPrefix};
use ipnetwork::IpNetwork;
use std::ffi::{CString, NulError};
use std::net::IpAddr;
use std::num::ParseIntError;
#[derive(thiserror::Error, Debug)]
pub enum Error {
#[error("Unable to open netlink socket to netfilter")]
NetlinkOpenError(#[source] std::io::Error),
#[error("Firewall is already started")]
AlreadyDone,
#[error("Error converting from a C string to a string")]
CStringError(#[from] NulError),
#[error("no interface found under that name")]
NoSuchIface,
#[error("Error converting from a string to an integer")]
ParseError(#[from] ParseIntError),
#[error("the interface name is too long")]
NameTooLong,
}
/// Simple protocol description. Note that it does not implement other layer 4 protocols as
/// IGMP et al. See [`Rule::igmp`] for a workaround.
#[derive(Debug, Clone)]
pub enum Protocol {
TCP,
UDP
}
/// A RuleMethods trait over [`crate::Rule`], to make it match some criteria, and give it a
/// verdict. Mostly adapted from [talpid-core's firewall].
/// All methods return the rule itself, allowing them to be chained. Usage example :
/// ```rust
/// use rustables::{Batch, Chain, ChainMethods, Protocol, ProtoFamily, Rule, RuleMethods, Table, MsgType, Hook};
/// use std::ffi::CString;
/// use std::rc::Rc;
/// let table = Rc::new(Table::new(&CString::new("main_table").unwrap(), ProtoFamily::Inet));
/// let mut batch = Batch::new();
/// batch.add(&table, MsgType::Add);
/// let inbound = Rc::new(Chain::from_hook(Hook::In, Rc::clone(&table))
/// .add_to_batch(&mut batch));
/// let rule = Rule::new(inbound)
/// .dport("80", &Protocol::TCP).unwrap()
/// .accept()
/// .add_to_batch(&mut batch);
/// ```
/// [talpid-core's firewall]:
/// https://github.com/mullvad/mullvadvpn-app/blob/d92376b4d1df9b547930c68aa9bae9640ff2a022/talpid-core/src/firewall/linux.rs
pub trait RuleMethods {
/// Matches ICMP packets.
fn icmp(self) -> Self;
/// Matches IGMP packets.
fn igmp(self) -> Self;
/// Matches packets to destination `port` and `protocol`.
fn dport(self, port: &str, protocol: &Protocol) -> Result<Self, Error>
where Self: std::marker::Sized;
/// Matches packets on `protocol`.
fn protocol(self, protocol: Protocol) -> Result<Self, Error>
where Self: std::marker::Sized;
/// Matches packets in an already established connection.
fn established(self) -> Self where Self: std::marker::Sized;
/// Matches packets going through `iface_index`. Interface indexes can be queried with
/// `iface_index()`.
fn iface_id(self, iface_index: libc::c_uint) -> Result<Self, Error>
where Self: std::marker::Sized;
/// Matches packets going through `iface_name`, an interface name, as in "wlan0" or "lo".
fn iface(self, iface_name: &str) -> Result<Self, Error>
where Self: std::marker::Sized;
/// Adds a log instruction to the rule. `group` is the NFLog group, `prefix` is a prefix
/// appended to each log line.
fn log(self, group: Option<LogGroup>, prefix: Option<LogPrefix>) -> Self;
/// Matches packets whose source IP address is `saddr`.
fn saddr(self, ip: IpAddr) -> Self;
/// Matches packets whose source network is `snet`.
fn snetwork(self, ip: IpNetwork) -> Self;
/// Adds the `Accept` verdict to the rule. The packet will be sent to destination.
fn accept(self) -> Self;
/// Adds the `Drop` verdict to the rule. The packet will be dropped.
fn drop(self) -> Self;
/// Appends this rule to `batch`.
fn add_to_batch(self, batch: &mut Batch) -> Self;
}
/// A trait to add helper functions to match some criterium over `crate::Rule`.
impl RuleMethods for Rule {
fn icmp(mut self) -> Self {
self.add_expr(&nft_expr!(meta l4proto));
//self.add_expr(&nft_expr!(cmp == libc::IPPROTO_ICMPV6 as u8));
self.add_expr(&nft_expr!(cmp == libc::IPPROTO_ICMP as u8));
self
}
fn igmp(mut self) -> Self {
self.add_expr(&nft_expr!(meta l4proto));
self.add_expr(&nft_expr!(cmp == libc::IPPROTO_IGMP as u8));
self
}
fn dport(mut self, port: &str, protocol: &Protocol) -> Result<Self, Error> {
self.add_expr(&nft_expr!(meta l4proto));
match protocol {
&Protocol::TCP => {
self.add_expr(&nft_expr!(cmp == libc::IPPROTO_TCP as u8));
self.add_expr(&nft_expr!(payload tcp dport));
},
&Protocol::UDP => {
self.add_expr(&nft_expr!(cmp == libc::IPPROTO_UDP as u8));
self.add_expr(&nft_expr!(payload udp dport));
}
}
// Convert the port to Big-Endian number spelling.
// See https://github.com/mullvad/mullvadvpn-app/blob/d92376b4d1df9b547930c68aa9bae9640ff2a022/talpid-core/src/firewall/linux.rs#L969
self.add_expr(&nft_expr!(cmp == port.parse::<u16>()?.to_be()));
Ok(self)
}
fn protocol(mut self, protocol: Protocol) -> Result<Self, Error> {
self.add_expr(&nft_expr!(meta l4proto));
match protocol {
Protocol::TCP => {
self.add_expr(&nft_expr!(cmp == libc::IPPROTO_TCP as u8));
},
Protocol::UDP => {
self.add_expr(&nft_expr!(cmp == libc::IPPROTO_UDP as u8));
}
}
Ok(self)
}
fn established(mut self) -> Self {
let allowed_states = crate::expr::ct::States::ESTABLISHED.bits();
self.add_expr(&nft_expr!(ct state));
self.add_expr(&nft_expr!(bitwise mask allowed_states, xor 0u32));
self.add_expr(&nft_expr!(cmp != 0u32));
self
}
fn iface_id(mut self, iface_index: libc::c_uint) -> Result<Self, Error> {
self.add_expr(&nft_expr!(meta iif));
self.add_expr(&nft_expr!(cmp == iface_index));
Ok(self)
}
fn iface(mut self, iface_name: &str) -> Result<Self, Error> {
if iface_name.len() >= libc::IFNAMSIZ {
return Err(Error::NameTooLong);
}
let mut name_arr = [0u8; libc::IFNAMSIZ];
for (pos, i) in iface_name.bytes().enumerate() {
name_arr[pos] = i;
}
self.add_expr(&nft_expr!(meta iifname));
self.add_expr(&nft_expr!(cmp == name_arr.as_ref()));
Ok(self)
}
fn saddr(mut self, ip: IpAddr) -> Self {
self.add_expr(&nft_expr!(meta nfproto));
match ip {
IpAddr::V4(addr) => {
self.add_expr(&nft_expr!(cmp == libc::NFPROTO_IPV4 as u8));
self.add_expr(&nft_expr!(payload ipv4 saddr));
self.add_expr(&nft_expr!(cmp == addr))
},
IpAddr::V6(addr) => {
self.add_expr(&nft_expr!(cmp == libc::NFPROTO_IPV6 as u8));
self.add_expr(&nft_expr!(payload ipv6 saddr));
self.add_expr(&nft_expr!(cmp == addr))
}
}
self
}
fn snetwork(mut self, net: IpNetwork) -> Self {
self.add_expr(&nft_expr!(meta nfproto));
match net {
IpNetwork::V4(_) => {
self.add_expr(&nft_expr!(cmp == libc::NFPROTO_IPV4 as u8));
self.add_expr(&nft_expr!(payload ipv4 saddr));
self.add_expr(&nft_expr!(bitwise mask net.mask(), xor 0u32));
self.add_expr(&nft_expr!(cmp == net.network()));
},
IpNetwork::V6(_) => {
self.add_expr(&nft_expr!(cmp == libc::NFPROTO_IPV6 as u8));
self.add_expr(&nft_expr!(payload ipv6 saddr));
self.add_expr(&nft_expr!(bitwise mask net.mask(), xor &[0u16; 8][..]));
self.add_expr(&nft_expr!(cmp == net.network()));
}
}
self
}
fn log(mut self, group: Option<LogGroup>, prefix: Option<LogPrefix>) -> Self {
match (group.is_some(), prefix.is_some()) {
(true, true) => {
self.add_expr(&nft_expr!(log group group prefix prefix));
},
(false, true) => {
self.add_expr(&nft_expr!(log prefix prefix));
},
(true, false) => {
self.add_expr(&nft_expr!(log group group));
},
(false, false) => {
self.add_expr(&nft_expr!(log));
}
}
self
}
fn accept(mut self) -> Self {
self.add_expr(&nft_expr!(verdict accept));
self
}
fn drop(mut self) -> Self {
self.add_expr(&nft_expr!(verdict drop));
self
}
fn add_to_batch(self, batch: &mut Batch) -> Self {
batch.add(&self, crate::MsgType::Add);
self
}
}
/// Looks up the interface index for a given interface name.
pub fn iface_index(name: &str) -> Result<libc::c_uint, Error> {
let c_name = CString::new(name)?;
let index = unsafe { libc::if_nametoindex(c_name.as_ptr()) };
match index {
0 => Err(Error::NoSuchIface),
_ => Ok(index)
}
}
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