Implement netlink uevent socket

kernel/src/net/socket/netlink/addr/mod.rs

@@ -43,6 +43,11 @@ impl NetlinkSocketAddr {
     pub const fn groups(&self) -> GroupIdSet {
         self.groups
     }
+
+    /// Adds some new groups to the address.
+    pub fn add_groups(&mut self, groups: GroupIdSet) {
+        self.groups.add_groups(groups);
+    }
 }
 
 impl TryFrom<SocketAddr> for NetlinkSocketAddr {

kernel/src/net/socket/netlink/addr/multicast.rs

@@ -24,21 +24,14 @@ impl GroupIdSet {
         GroupIdIter::new(self)
     }
 
-    /// Adds a new group.
-    ///
-    /// If the group already exists, this method will return an error.
-    pub fn add_group(&mut self, group_id: GroupId) -> Result<()> {
-        if group_id >= 32 {
-            return_errno_with_message!(Errno::EINVAL, "the group ID is invalid");
+    /// Adds some new groups.
+    pub fn add_groups(&mut self, groups: GroupIdSet) {
+        self.0 |= groups.0;
     }
 
-        let mask = 1u32 << group_id;
-        if self.0 & mask != 0 {
-            return_errno_with_message!(Errno::EINVAL, "the group ID already exists");
-        }
-        self.0 |= mask;
-
-        Ok(())
+    /// Drops some groups.
+    pub fn drop_groups(&mut self, groups: GroupIdSet) {
+        self.0 &= !groups.0;
     }
 
     /// Sets new groups.

kernel/src/net/socket/netlink/common/bound.rs

@@ -0,0 +1,61 @@
+// SPDX-License-Identifier: MPL-2.0
+
+use crate::{
+    events::IoEvents,
+    net::socket::netlink::{
+        receiver::MessageQueue, table::BoundHandle, GroupIdSet, NetlinkSocketAddr,
+    },
+    prelude::*,
+};
+
+pub struct BoundNetlink<Message: 'static> {
+    pub(in crate::net::socket::netlink) handle: BoundHandle<Message>,
+    pub(in crate::net::socket::netlink) remote_addr: NetlinkSocketAddr,
+    pub(in crate::net::socket::netlink) receive_queue: MessageQueue<Message>,
+}
+
+impl<Message: 'static> BoundNetlink<Message> {
+    pub(super) fn new(handle: BoundHandle<Message>, message_queue: MessageQueue<Message>) -> Self {
+        Self {
+            handle,
+            remote_addr: NetlinkSocketAddr::new_unspecified(),
+            receive_queue: message_queue,
+        }
+    }
+
+    pub(in crate::net::socket::netlink) fn bind_common(
+        &mut self,
+        endpoint: &NetlinkSocketAddr,
+    ) -> Result<()> {
+        if endpoint.port() != self.handle.port() {
+            return_errno_with_message!(
+                Errno::EINVAL,
+                "the socket cannot be bound to a different port"
+            );
+        }
+
+        let groups = endpoint.groups();
+        self.handle.bind_groups(groups);
+
+        Ok(())
+    }
+
+    pub(in crate::net::socket::netlink) fn check_io_events_common(&self) -> IoEvents {
+        let mut events = IoEvents::OUT;
+
+        let receive_queue = self.receive_queue.0.lock();
+        if !receive_queue.is_empty() {
+            events |= IoEvents::IN;
+        }
+
+        events
+    }
+
+    pub(super) fn add_groups(&mut self, groups: GroupIdSet) {
+        self.handle.add_groups(groups);
+    }
+
+    pub(super) fn drop_groups(&mut self, groups: GroupIdSet) {
+        self.handle.drop_groups(groups);
+    }
+}

kernel/src/net/socket/netlink/common/mod.rs

@@ -0,0 +1,230 @@
+// SPDX-License-Identifier: MPL-2.0
+
+use core::sync::atomic::{AtomicBool, Ordering};
+
+pub(super) use bound::BoundNetlink;
+use unbound::UnboundNetlink;
+
+use super::{GroupIdSet, NetlinkSocketAddr};
+use crate::{
+    events::IoEvents,
+    match_sock_option_ref,
+    net::socket::{
+        netlink::{table::SupportedNetlinkProtocol, AddMembership, DropMembership},
+        options::SocketOption,
+        private::SocketPrivate,
+        util::datagram_common::{select_remote_and_bind, Bound, Inner},
+        MessageHeader, SendRecvFlags, Socket, SocketAddr,
+    },
+    prelude::*,
+    process::signal::{PollHandle, Pollable, Pollee},
+    util::{MultiRead, MultiWrite},
+};
+
+mod bound;
+mod unbound;
+
+pub struct NetlinkSocket<P: SupportedNetlinkProtocol> {
+    inner: RwMutex<Inner<UnboundNetlink<P>, BoundNetlink<P::Message>>>,
+
+    is_nonblocking: AtomicBool,
+    pollee: Pollee,
+}
+
+impl<P: SupportedNetlinkProtocol> NetlinkSocket<P>
+where
+    BoundNetlink<P::Message>: Bound<Endpoint = NetlinkSocketAddr>,
+{
+    pub fn new(is_nonblocking: bool) -> Arc<Self> {
+        let unbound = UnboundNetlink::new();
+        Arc::new(Self {
+            inner: RwMutex::new(Inner::Unbound(unbound)),
+            is_nonblocking: AtomicBool::new(is_nonblocking),
+            pollee: Pollee::new(),
+        })
+    }
+
+    fn try_send(
+        &self,
+        reader: &mut dyn MultiRead,
+        remote: Option<&NetlinkSocketAddr>,
+        flags: SendRecvFlags,
+    ) -> Result<usize> {
+        let sent_bytes = select_remote_and_bind(
+            &self.inner,
+            remote,
+            || {
+                self.inner
+                    .write()
+                    .bind_ephemeral(&NetlinkSocketAddr::new_unspecified(), &self.pollee)
+            },
+            |bound, remote_endpoint| bound.try_send(reader, remote_endpoint, flags),
+        )?;
+        self.pollee.invalidate();
+
+        Ok(sent_bytes)
+    }
+
+    // FIXME: This method is marked as `pub(super)` because it's invoked during kernel mode testing.
+    pub(super) fn try_recv(
+        &self,
+        writer: &mut dyn MultiWrite,
+        flags: SendRecvFlags,
+    ) -> Result<(usize, SocketAddr)> {
+        let recv_bytes = self
+            .inner
+            .read()
+            .try_recv(writer, flags)
+            .map(|(recv_bytes, remote_endpoint)| (recv_bytes, remote_endpoint.into()))?;
+        self.pollee.invalidate();
+
+        Ok(recv_bytes)
+    }
+}
+
+impl<P: SupportedNetlinkProtocol> Socket for NetlinkSocket<P>
+where
+    BoundNetlink<P::Message>: Bound<Endpoint = NetlinkSocketAddr>,
+{
+    fn bind(&self, socket_addr: SocketAddr) -> Result<()> {
+        let endpoint = socket_addr.try_into()?;
+
+        self.inner.write().bind(&endpoint, &self.pollee, ())
+    }
+
+    fn connect(&self, socket_addr: SocketAddr) -> Result<()> {
+        let endpoint = socket_addr.try_into()?;
+
+        self.inner.write().connect(&endpoint, &self.pollee)
+    }
+
+    fn addr(&self) -> Result<SocketAddr> {
+        let endpoint = match &*self.inner.read() {
+            Inner::Unbound(unbound) => unbound.addr(),
+            Inner::Bound(bound) => bound.local_endpoint(),
+        };
+
+        Ok(endpoint.into())
+    }
+
+    fn peer_addr(&self) -> Result<SocketAddr> {
+        let endpoint = self
+            .inner
+            .read()
+            .peer_addr()
+            .cloned()
+            .unwrap_or(NetlinkSocketAddr::new_unspecified());
+
+        Ok(endpoint.into())
+    }
+
+    fn sendmsg(
+        &self,
+        reader: &mut dyn MultiRead,
+        message_header: MessageHeader,
+        flags: SendRecvFlags,
+    ) -> Result<usize> {
+        let MessageHeader {
+            addr,
+            control_message,
+        } = message_header;
+
+        let remote = match addr {
+            None => None,
+            Some(addr) => Some(addr.try_into()?),
+        };
+
+        if control_message.is_some() {
+            // TODO: Support sending control message
+            warn!("sending control message is not supported");
+        }
+
+        // TODO: Make sure our blocking behavior matches that of Linux
+        self.try_send(reader, remote.as_ref(), flags)
+    }
+
+    fn recvmsg(
+        &self,
+        writers: &mut dyn MultiWrite,
+        flags: SendRecvFlags,
+    ) -> Result<(usize, MessageHeader)> {
+        let (received_len, addr) = self.block_on(IoEvents::IN, || self.try_recv(writers, flags))?;
+
+        // TODO: Receive control message
+
+        let message_header = MessageHeader::new(Some(addr), None);
+
+        Ok((received_len, message_header))
+    }
+
+    fn set_option(&self, option: &dyn SocketOption) -> Result<()> {
+        match do_set_netlink_option(&self.inner, option) {
+            Ok(()) => Ok(()),
+            Err(e) => {
+                warn!(
+                    "We currently ignore set option errors to pass libnl test: {:?}",
+                    e
+                );
+                Ok(())
+            }
+        }
+    }
+}
+
+impl<P: SupportedNetlinkProtocol> SocketPrivate for NetlinkSocket<P>
+where
+    BoundNetlink<P::Message>: Bound<Endpoint = NetlinkSocketAddr>,
+{
+    fn is_nonblocking(&self) -> bool {
+        self.is_nonblocking.load(Ordering::Relaxed)
+    }
+
+    fn set_nonblocking(&self, nonblocking: bool) {
+        self.is_nonblocking.store(nonblocking, Ordering::Relaxed);
+    }
+}
+
+impl<P: SupportedNetlinkProtocol> Pollable for NetlinkSocket<P>
+where
+    BoundNetlink<P::Message>: Bound<Endpoint = NetlinkSocketAddr>,
+{
+    fn poll(&self, mask: IoEvents, poller: Option<&mut PollHandle>) -> IoEvents {
+        self.pollee
+            .poll_with(mask, poller, || self.inner.read().check_io_events())
+    }
+}
+
+impl<P: SupportedNetlinkProtocol> Inner<UnboundNetlink<P>, BoundNetlink<P::Message>> {
+    fn add_groups(&mut self, groups: GroupIdSet) {
+        match self {
+            Inner::Unbound(unbound_socket) => unbound_socket.add_groups(groups),
+            Inner::Bound(bound_socket) => bound_socket.add_groups(groups),
+        }
+    }
+
+    fn drop_groups(&mut self, groups: GroupIdSet) {
+        match self {
+            Inner::Unbound(unbound_socket) => unbound_socket.drop_groups(groups),
+            Inner::Bound(bound_socket) => bound_socket.drop_groups(groups),
+        }
+    }
+}
+
+fn do_set_netlink_option<P: SupportedNetlinkProtocol>(
+    inner: &RwMutex<Inner<UnboundNetlink<P>, BoundNetlink<P::Message>>>,
+    option: &dyn SocketOption,
+) -> Result<()> {
+    match_sock_option_ref!(option, {
+        add_membership: AddMembership => {
+            let groups = add_membership.get().unwrap();
+            inner.write().add_groups(GroupIdSet::new(*groups));
+        },
+        drop_membership: DropMembership => {
+            let groups = drop_membership.get().unwrap();
+            inner.write().drop_groups(GroupIdSet::new(*groups));
+        },
+        _ => return_errno_with_message!(Errno::ENOPROTOOPT, "the socket option to be set is unknown")
+    });
+
+    Ok(())
+}

kernel/src/net/socket/netlink/common/unbound.rs

@@ -0,0 +1,96 @@
+// SPDX-License-Identifier: MPL-2.0
+
+use core::marker::PhantomData;
+
+use crate::{
+    events::IoEvents,
+    net::socket::{
+        netlink::{
+            common::bound::BoundNetlink,
+            receiver::{MessageQueue, MessageReceiver},
+            table::SupportedNetlinkProtocol,
+            GroupIdSet, NetlinkSocketAddr,
+        },
+        util::datagram_common,
+    },
+    prelude::*,
+    process::signal::Pollee,
+};
+
+pub(super) struct UnboundNetlink<P: SupportedNetlinkProtocol> {
+    groups: GroupIdSet,
+    phantom: PhantomData<BoundNetlink<P::Message>>,
+}
+
+impl<P: SupportedNetlinkProtocol> UnboundNetlink<P> {
+    pub(super) const fn new() -> Self {
+        Self {
+            groups: GroupIdSet::new_empty(),
+            phantom: PhantomData,
+        }
+    }
+
+    pub(super) fn addr(&self) -> NetlinkSocketAddr {
+        NetlinkSocketAddr::new(0, self.groups)
+    }
+
+    pub(super) fn add_groups(&mut self, groups: GroupIdSet) {
+        self.groups.add_groups(groups);
+    }
+
+    pub(super) fn drop_groups(&mut self, groups: GroupIdSet) {
+        self.groups.drop_groups(groups);
+    }
+}
+
+impl<P: SupportedNetlinkProtocol> datagram_common::Unbound for UnboundNetlink<P> {
+    type Endpoint = NetlinkSocketAddr;
+    type BindOptions = ();
+
+    type Bound = BoundNetlink<P::Message>;
+
+    fn bind(
+        &mut self,
+        endpoint: &Self::Endpoint,
+        pollee: &Pollee,
+        _options: Self::BindOptions,
+    ) -> Result<Self::Bound> {
+        let message_queue = MessageQueue::<P::Message>::new();
+
+        let bound_handle = {
+            let endpoint = {
+                let mut endpoint = endpoint.clone();
+                endpoint.add_groups(self.groups);
+                endpoint
+            };
+            let receiver = MessageReceiver::new(message_queue.clone(), pollee.clone());
+            <P as SupportedNetlinkProtocol>::bind(&endpoint, receiver)?
+        };
+
+        Ok(BoundNetlink::new(bound_handle, message_queue))
+    }
+
+    fn bind_ephemeral(
+        &mut self,
+        _remote_endpoint: &Self::Endpoint,
+        pollee: &Pollee,
+    ) -> Result<Self::Bound> {
+        let message_queue = MessageQueue::<P::Message>::new();
+
+        let bound_handle = {
+            let endpoint = {
+                let mut endpoint = NetlinkSocketAddr::new_unspecified();
+                endpoint.add_groups(self.groups);
+                endpoint
+            };
+            let receiver = MessageReceiver::new(message_queue.clone(), pollee.clone());
+            <P as SupportedNetlinkProtocol>::bind(&endpoint, receiver)?
+        };
+
+        Ok(BoundNetlink::new(bound_handle, message_queue))
+    }
+
+    fn check_io_events(&self) -> IoEvents {
+        IoEvents::OUT
+    }
+}

kernel/src/net/socket/netlink/kobject_uevent/bound.rs

@@ -0,0 +1,96 @@
+// SPDX-License-Identifier: MPL-2.0
+
+use core::ops::Sub;
+
+use super::message::UeventMessage;
+use crate::{
+    events::IoEvents,
+    net::socket::{
+        netlink::{common::BoundNetlink, NetlinkSocketAddr},
+        util::datagram_common,
+        SendRecvFlags,
+    },
+    prelude::*,
+    util::{MultiRead, MultiWrite},
+};
+
+pub(super) type BoundNetlinkUevent = BoundNetlink<UeventMessage>;
+
+impl datagram_common::Bound for BoundNetlinkUevent {
+    type Endpoint = NetlinkSocketAddr;
+
+    fn local_endpoint(&self) -> Self::Endpoint {
+        self.handle.addr()
+    }
+
+    fn bind(&mut self, endpoint: &Self::Endpoint) -> Result<()> {
+        self.bind_common(endpoint)
+    }
+
+    fn remote_endpoint(&self) -> Option<&Self::Endpoint> {
+        Some(&self.remote_addr)
+    }
+
+    fn set_remote_endpoint(&mut self, endpoint: &Self::Endpoint) {
+        self.remote_addr = *endpoint;
+    }
+
+    fn try_send(
+        &self,
+        reader: &mut dyn MultiRead,
+        remote: &Self::Endpoint,
+        flags: SendRecvFlags,
+    ) -> Result<usize> {
+        // TODO: Deal with flags
+        if !flags.is_all_supported() {
+            warn!("unsupported flags: {:?}", flags);
+        }
+
+        if *remote != NetlinkSocketAddr::new_unspecified() {
+            return_errno_with_message!(
+                Errno::ECONNREFUSED,
+                "sending uevent messages to user space is not supported"
+            );
+        }
+
+        // FIXME: How to deal with sending message to kernel socket?
+        // Here we simply ignore the message and return the message length.
+        Ok(reader.sum_lens())
+    }
+
+    fn try_recv(
+        &self,
+        writer: &mut dyn MultiWrite,
+        flags: SendRecvFlags,
+    ) -> Result<(usize, Self::Endpoint)> {
+        // TODO: Deal with other flags. Only MSG_PEEK is handled here.
+        if !flags.sub(SendRecvFlags::MSG_PEEK).is_all_supported() {
+            warn!("unsupported flags: {:?}", flags);
+        }
+
+        let mut receive_queue = self.receive_queue.0.lock();
+
+        let Some(response) = receive_queue.front() else {
+            return_errno_with_message!(Errno::EAGAIN, "nothing to receive");
+        };
+
+        let len = {
+            let max_len = writer.sum_lens();
+            response.total_len().min(max_len)
+        };
+
+        response.write_to(writer)?;
+
+        let remote = response.src_addr().clone();
+
+        if !flags.contains(SendRecvFlags::MSG_PEEK) {
+            receive_queue.pop_front().unwrap();
+        }
+
+        Ok((len, remote))
+    }
+
+    fn check_io_events(&self) -> IoEvents {
+        self.check_io_events_common()
+    }
+}

kernel/src/net/socket/netlink/kobject_uevent/message/mod.rs

@@ -0,0 +1,58 @@
+// SPDX-License-Identifier: MPL-2.0
+
+#![cfg_attr(not(ktest), expect(dead_code))]
+
+use uevent::Uevent;
+
+use crate::{
+    net::socket::netlink::{table::MulticastMessage, NetlinkSocketAddr},
+    prelude::*,
+    util::MultiWrite,
+};
+
+mod syn_uevent;
+#[cfg(ktest)]
+mod test;
+mod uevent;
+
+/// A uevent message.
+///
+/// Note that uevent messages are not the same as common netlink messages.
+/// It does not have a netlink header.
+#[derive(Debug, Clone)]
+pub struct UeventMessage {
+    uevent: String,
+    src_addr: NetlinkSocketAddr,
+}
+
+impl UeventMessage {
+    /// Creates a new uevent message.
+    fn new(uevent: Uevent, src_addr: NetlinkSocketAddr) -> Self {
+        Self {
+            uevent: uevent.to_string(),
+            src_addr,
+        }
+    }
+
+    /// Returns the source address of the uevent message.
+    pub(super) fn src_addr(&self) -> &NetlinkSocketAddr {
+        &self.src_addr
+    }
+
+    /// Returns the total length of the uevent.
+    pub(super) fn total_len(&self) -> usize {
+        self.uevent.len()
+    }
+
+    /// Writes the uevent to the given `writer`.
+    pub(super) fn write_to(&self, writer: &mut dyn MultiWrite) -> Result<()> {
+        // FIXME: If the message can be truncated, we should avoid returning an error.
+        if self.uevent.len() > writer.sum_lens() {
+            return_errno_with_message!(Errno::EFAULT, "the writer length is too small");
+        }
+        writer.write(&mut VmReader::from(self.uevent.as_bytes()))?;
+        Ok(())
+    }
+}
+
+impl MulticastMessage for UeventMessage {}

kernel/src/net/socket/netlink/kobject_uevent/message/syn_uevent.rs

@@ -0,0 +1,102 @@
+// SPDX-License-Identifier: MPL-2.0
+
+//! The synthetic uevent.
+//!
+//! The event is triggered when someone writes some content to `/sys/.../uevent` file.
+//! It differs from the event triggers by devices.
+//!
+//! Reference: <https://elixir.bootlin.com/linux/v6.0.9/source/Documentation/ABI/testing/sysfs-uevent>.
+
+use alloc::format;
+use core::str::FromStr;
+
+use super::uevent::SysObjAction;
+use crate::prelude::*;
+
+/// The synthetic uevent.
+pub(super) struct SyntheticUevent {
+    pub(super) action: SysObjAction,
+    pub(super) uuid: Option<Uuid>,
+    pub(super) envs: Vec<(String, String)>,
+}
+
+impl FromStr for SyntheticUevent {
+    type Err = Error;
+
+    fn from_str(s: &str) -> Result<Self> {
+        let mut split = s.split(" ");
+
+        let action = {
+            let Some(action_str) = split.next() else {
+                return_errno_with_message!(Errno::EINVAL, "the string is empty");
+            };
+            SysObjAction::from_str(action_str)?
+        };
+
+        let uuid = if let Some(uuid_str) = split.next() {
+            Some(Uuid::from_str(uuid_str)?)
+        } else {
+            None
+        };
+
+        let mut envs = Vec::new();
+        for env_str in split.into_iter() {
+            let (key, value) = {
+                // Each string should be in the `KEY=VALUE` format.
+                match env_str.split_once('=') {
+                    Some(key_value) => key_value,
+                    None => return_errno_with_message!(Errno::EINVAL, "invalid key value pairs"),
+                }
+            };
+
+            // Both `KEY` and `VALUE` can contain alphanumeric characters only.
+            for byte in key.as_bytes().iter().chain(value.as_bytes()) {
+                if !byte.is_ascii_alphanumeric() {
+                    return_errno_with_message!(
+                        Errno::EINVAL,
+                        "invalid character in key value pairs"
+                    );
+                }
+            }
+
+            // The `KEY` name gains `SYNTH_ARG_` prefix to avoid possible collisions
+            // with existing variables.
+            let key = format!("SYNTH_ARG_{}", key);
+            let value = value.to_string();
+            envs.push((key, value));
+        }
+
+        Ok(Self { action, uuid, envs })
+    }
+}
+
+pub(super) struct Uuid(pub(super) String);
+
+impl FromStr for Uuid {
+    type Err = Error;
+
+    fn from_str(s: &str) -> Result<Self> {
+        /// The allowed UUID pattern, where each `x` is a hex digit.
+        ///
+        /// Reference: <https://elixir.bootlin.com/linux/v6.0.9/source/Documentation/ABI/testing/sysfs-uevent#L19>.
+        const UUID_PATTERN: &str = "xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx";
+
+        let bytes = s.as_bytes();
+
+        if bytes.len() != UUID_PATTERN.len() {
+            return_errno_with_message!(Errno::EINVAL, "the UUID length is invalid");
+        }
+
+        for (byte, pattern) in bytes.into_iter().zip(UUID_PATTERN.as_bytes()) {
+            if *pattern == b'x' && byte.is_ascii_hexdigit() {
+                continue;
+            } else if *pattern == b'-' && *byte == b'-' {
+                continue;
+            } else {
+                return_errno_with_message!(Errno::EINVAL, "the UUID content is invalid");
+            }
+        }
+
+        Ok(Self(s.to_string()))
+    }
+}

kernel/src/net/socket/netlink/kobject_uevent/message/test.rs

@@ -0,0 +1,89 @@
+// SPDX-License-Identifier: MPL-2.0
+
+use alloc::vec;
+use core::str::FromStr;
+
+use ostd::{mm::VmWriter, prelude::*};
+
+use crate::{
+    net::socket::{
+        netlink::{
+            kobject_uevent::{
+                message::{
+                    syn_uevent::{SyntheticUevent, Uuid},
+                    uevent::Uevent,
+                },
+                UeventMessage,
+            },
+            table::{NetlinkUeventProtocol, SupportedNetlinkProtocol},
+            GroupIdSet, NetlinkSocketAddr, NetlinkUeventSocket,
+        },
+        SendRecvFlags, Socket, SocketAddr,
+    },
+    prelude::*,
+};
+
+#[ktest]
+fn uuid() {
+    let uuid = Uuid::from_str("12345678-1234-1234-1234-123456789012");
+    assert!(uuid.is_ok());
+
+    let uuid = Uuid::from_str("12345678-1234-1234-1234-12345678901");
+    assert!(uuid.is_err());
+
+    let uuid = Uuid::from_str("12345678-1234-1234-1234-1234567890g");
+    assert!(uuid.is_err());
+}
+
+#[ktest]
+fn synthetic_uevent() {
+    let uevent = SyntheticUevent::from_str("add");
+    assert!(uevent.is_ok());
+
+    let uevent = SyntheticUevent::from_str("add 12345678-1234-1234-1234-123456789012");
+    assert!(uevent.is_ok());
+
+    let uevent = SyntheticUevent::from_str("add 12345678-1234-1234-1234-123456789012 NAME=lo");
+    assert!(uevent.is_ok());
+}
+
+#[ktest]
+fn multicast_synthetic_uevent() {
+    crate::net::socket::netlink::init();
+
+    // Creates a new netlink uevent socket and joins the group for kobject uevents.
+    let socket = NetlinkUeventSocket::new(true);
+    let socket_addr = SocketAddr::Netlink(NetlinkSocketAddr::new(100, GroupIdSet::new(0x1)));
+    socket.bind(socket_addr).unwrap();
+
+    // Tries to receive and returns EAGAIN if no message is available.
+    let mut buffer = vec![0u8; 1024];
+    let mut writer = VmWriter::from(buffer.as_mut_slice()).to_fallible();
+    let res = socket.try_recv(&mut writer, SendRecvFlags::empty());
+    assert!(res.is_err_and(|err| err.error() == Errno::EAGAIN));
+
+    // Broadcasts a uevent message.
+    let uevent = {
+        let lo_infos = vec![
+            ("INTERFACE".to_string(), "lo".to_string()),
+            ("IFINDEX".to_string(), "1".to_string()),
+        ];
+        let synth_uevent = SyntheticUevent::from_str("add").unwrap();
+        Uevent::new_from_syn(
+            synth_uevent,
+            "/devices/virtual/net/lo".to_string(),
+            "net".to_string(),
+            lo_infos,
+        )
+    };
+    let uevent_message =
+        UeventMessage::new(uevent, NetlinkSocketAddr::new(0, GroupIdSet::new(0x1)));
+    NetlinkUeventProtocol::multicast(GroupIdSet::new(0x1), uevent_message).unwrap();
+
+    let (len, _) = socket
+        .try_recv(&mut writer, SendRecvFlags::empty())
+        .unwrap();
+    let s = core::str::from_utf8(&buffer[..len]).unwrap();
+
+    assert_eq!(s, "add@/devices/virtual/net/lo\0ACTION=add\0DEVPATH=/devices/virtual/net/lo\0SUBSYSTEM=net\0SYNTH_UUID=0\0INTERFACE=lo\0IFINDEX=1\0SEQNUM=1\0");
+}

kernel/src/net/socket/netlink/kobject_uevent/message/uevent.rs

@@ -0,0 +1,176 @@
+// SPDX-License-Identifier: MPL-2.0
+
+use alloc::format;
+use core::{
+    str::FromStr,
+    sync::atomic::{AtomicU64, Ordering},
+};
+
+use super::syn_uevent::{SyntheticUevent, Uuid};
+use crate::prelude::*;
+
+/// `SysObj` action type.
+///
+/// Reference: <https://elixir.bootlin.com/linux/v6.14/source/include/linux/kobject.h#L53>.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, TryFromInt)]
+#[repr(u8)]
+pub(super) enum SysObjAction {
+    /// Indicates the addition of a new `SysObj` to the system.
+    ///
+    /// Triggered when a device is discovered or registered.
+    Add = 0,
+
+    /// Signals the removal of a `SysObj` from the system.
+    ///
+    /// Typically occurs during device disconnection or deregistration.
+    Remove = 1,
+
+    /// Denotes a modification to the `SysObj`'s properties or state.
+    ///
+    /// Used for attribute changes that don't involve structural modifications.
+    Change = 2,
+
+    /// Represents hierarchical relocation of a `SysObj`.
+    ///
+    /// Occurs when a device moves within the device tree topology.
+    Move = 3,
+
+    /// Marks a device returning to operational status after being offlined.
+    ///
+    /// Common in hot-pluggable device scenarios.
+    Online = 4,
+
+    /// Indicates a device entering non-operational status.
+    ///
+    /// Typically precedes safe removal of hot-pluggable hardware.
+    Offline = 5,
+
+    /// Signifies successful driver-device binding.
+    ///
+    /// Occurs after successful driver probe sequence.
+    Bind = 6,
+
+    /// Indicates driver-device binding termination.
+    ///
+    /// Precedes driver unload or device removal.
+    Unbind = 7,
+}
+
+const SYSOBJ_ACTION_STRS: [&str; SysObjAction::Unbind as usize + 1] = [
+    "add", "remove", "change", "move", "online", "offline", "bind", "unbind",
+];
+
+impl FromStr for SysObjAction {
+    type Err = Error;
+
+    fn from_str(s: &str) -> Result<Self> {
+        let Some(index) = SYSOBJ_ACTION_STRS
+            .iter()
+            .position(|action_str| s == *action_str)
+        else {
+            return_errno_with_message!(Errno::EINVAL, "the string is not a valid `SysObj` action");
+        };
+
+        Ok(SysObjAction::try_from(index as u8).unwrap())
+    }
+}
+
+impl SysObjAction {
+    fn as_str(&self) -> &'static str {
+        SYSOBJ_ACTION_STRS[*self as usize]
+    }
+}
+
+/// Userspace event.
+pub(super) struct Uevent {
+    /// The `SysObj` action.
+    action: SysObjAction,
+    /// The absolute `SysObj` path under sysfs.
+    devpath: String,
+    /// The subsystem the event originates from
+    subsystem: String,
+    /// Other key-value arguments
+    envs: Vec<(String, String)>,
+    /// Sequence number.
+    seq_num: u64,
+}
+
+impl Uevent {
+    /// Creates a new uevent.
+    fn new(
+        action: SysObjAction,
+        devpath: String,
+        subsystem: String,
+        envs: Vec<(String, String)>,
+    ) -> Self {
+        debug_assert!(devpath.starts_with('/'));
+
+        let seq_num = SEQ_NUM_ALLOCATOR.fetch_add(1, Ordering::Relaxed);
+
+        Self {
+            action,
+            devpath,
+            subsystem,
+            envs,
+            seq_num,
+        }
+    }
+
+    /// Creates a new uevent from synthetic uevent.
+    pub(super) fn new_from_syn(
+        synth_uevent: SyntheticUevent,
+        devpath: String,
+        subsystem: String,
+        mut other_envs: Vec<(String, String)>,
+    ) -> Self {
+        let SyntheticUevent {
+            action,
+            uuid,
+            mut envs,
+        } = synth_uevent;
+
+        let uuid_key = "SYNTH_UUID".to_string();
+        if let Some(Uuid(uuid)) = uuid {
+            envs.push((uuid_key, uuid));
+        } else {
+            envs.push((uuid_key, "0".to_string()));
+        };
+
+        envs.append(&mut other_envs);
+
+        Self::new(action, devpath, subsystem, envs)
+    }
+}
+
+impl ToString for Uevent {
+    fn to_string(&self) -> String {
+        let mut env_string = {
+            let len = self
+                .envs
+                .iter()
+                .map(|(key, value)| key.len() + value.len() + 2)
+                .sum();
+            String::with_capacity(len)
+        };
+
+        for (key, value) in self.envs.iter() {
+            env_string.push_str(key);
+            env_string.push('=');
+            env_string.push_str(value);
+            env_string.push('\0');
+        }
+
+        format!(
+            "{}@{}\0ACTION={}\0DEVPATH={}\0SUBSYSTEM={}\0{}SEQNUM={}\0",
+            self.action.as_str(),
+            self.devpath,
+            self.action.as_str(),
+            self.devpath,
+            self.subsystem,
+            env_string,
+            self.seq_num
+        )
+    }
+}
+
+static SEQ_NUM_ALLOCATOR: AtomicU64 = AtomicU64::new(1);

kernel/src/net/socket/netlink/kobject_uevent/mod.rs

@@ -0,0 +1,10 @@
+// SPDX-License-Identifier: MPL-2.0
+
+pub(super) use message::UeventMessage;
+
+use crate::net::socket::netlink::{common::NetlinkSocket, table::NetlinkUeventProtocol};
+
+mod bound;
+mod message;
+
+pub type NetlinkUeventSocket = NetlinkSocket<NetlinkUeventProtocol>;

kernel/src/net/socket/netlink/message/mod.rs

@@ -26,7 +26,7 @@ use crate::{
 /// A netlink message can be transmitted to and from user space using a single send/receive syscall.
 /// It consists of one or more [`ProtocolSegment`]s.
 #[derive(Debug)]
-pub(super) struct Message<T: ProtocolSegment> {
+pub struct Message<T: ProtocolSegment> {
     segments: Vec<T>,
 }
 
@@ -69,7 +69,7 @@ impl<T: ProtocolSegment> Message<T> {
     }
 }
 
-pub(super) trait ProtocolSegment: Sized {
+pub trait ProtocolSegment: Sized {
     fn header(&self) -> &CMsgSegHdr;
     fn header_mut(&mut self) -> &mut CMsgSegHdr;
     fn read_from(reader: &mut dyn MultiRead) -> Result<Self>;

kernel/src/net/socket/netlink/message/segment/header.rs

@@ -23,7 +23,7 @@ pub struct CMsgSegHdr {
 }
 
 bitflags! {
-    /// Common flags used in [`CMsgSegmentHdr`].
+    /// Common flags used in [`CMsgSegHdr`].
     ///
     /// Reference: <https://elixir.bootlin.com/linux/v6.13/source/include/uapi/linux/netlink.h#L62>.
     pub struct SegHdrCommonFlags: u16 {

kernel/src/net/socket/netlink/mod.rs

@@ -38,11 +38,17 @@
 //!
 
 mod addr;
+mod common;
+mod kobject_uevent;
 mod message;
+mod options;
+mod receiver;
 mod route;
 mod table;
 
 pub use addr::{GroupIdSet, NetlinkSocketAddr};
+pub use kobject_uevent::NetlinkUeventSocket;
+pub use options::{AddMembership, DropMembership};
 pub use route::NetlinkRouteSocket;
 pub use table::{is_valid_protocol, StandardNetlinkProtocol};
 

kernel/src/net/socket/netlink/options.rs

@@ -0,0 +1,8 @@
+// SPDX-License-Identifier: MPL-2.0
+
+use crate::impl_socket_options;
+
+impl_socket_options!(
+    pub struct AddMembership(u32);
+    pub struct DropMembership(u32);
+);

kernel/src/net/socket/netlink/receiver.rs

@@ -0,0 +1,45 @@
+// SPDX-License-Identifier: MPL-2.0
+
+use crate::{events::IoEvents, prelude::*, process::signal::Pollee};
+
+pub struct MessageReceiver<Message> {
+    message_queue: MessageQueue<Message>,
+    pollee: Pollee,
+}
+
+pub(super) struct MessageQueue<Message>(pub(super) Arc<Mutex<VecDeque<Message>>>);
+
+impl<Message> Clone for MessageQueue<Message> {
+    fn clone(&self) -> Self {
+        Self(self.0.clone())
+    }
+}
+
+impl<Message> MessageQueue<Message> {
+    pub(super) fn new() -> Self {
+        Self(Arc::new(Mutex::new(VecDeque::new())))
+    }
+
+    fn enqueue(&self, message: Message) -> Result<()> {
+        // FIXME: We should verify the socket buffer length to ensure
+        // that adding the message doesn't exceed the buffer capacity.
+        self.0.lock().push_back(message);
+        Ok(())
+    }
+}
+
+impl<Message> MessageReceiver<Message> {
+    pub(super) const fn new(message_queue: MessageQueue<Message>, pollee: Pollee) -> Self {
+        Self {
+            message_queue,
+            pollee,
+        }
+    }
+
+    pub(super) fn enqueue_message(&self, message: Message) -> Result<()> {
+        self.message_queue.enqueue(message)?;
+        self.pollee.notify(IoEvents::IN);
+
+        Ok(())
+    }
+}

kernel/src/net/socket/netlink/route/bound.rs

@@ -7,8 +7,8 @@ use crate::{
     events::IoEvents,
     net::socket::{
         netlink::{
-            message::ProtocolSegment, route::kernel::get_netlink_route_kernel, table::BoundHandle,
-            NetlinkSocketAddr,
+            common::BoundNetlink, message::ProtocolSegment,
+            route::kernel::get_netlink_route_kernel, NetlinkSocketAddr,
         },
         util::datagram_common,
         SendRecvFlags,
@@ -17,21 +17,7 @@ use crate::{
     util::{MultiRead, MultiWrite},
 };
 
-pub(super) struct BoundNetlinkRoute {
-    handle: BoundHandle,
-    remote_addr: NetlinkSocketAddr,
-    receive_queue: Mutex<VecDeque<RtnlMessage>>,
-}
-
-impl BoundNetlinkRoute {
-    pub(super) const fn new(handle: BoundHandle) -> Self {
-        Self {
-            handle,
-            remote_addr: NetlinkSocketAddr::new_unspecified(),
-            receive_queue: Mutex::new(VecDeque::new()),
-        }
-    }
-}
+pub(super) type BoundNetlinkRoute = BoundNetlink<RtnlMessage>;
 
 impl datagram_common::Bound for BoundNetlinkRoute {
     type Endpoint = NetlinkSocketAddr;
@@ -40,6 +26,10 @@ impl datagram_common::Bound for BoundNetlinkRoute {
         self.handle.addr()
     }
 
+    fn bind(&mut self, endpoint: &Self::Endpoint) -> Result<()> {
+        self.bind_common(endpoint)
+    }
+
     fn remote_endpoint(&self) -> Option<&Self::Endpoint> {
         Some(&self.remote_addr)
     }
@@ -97,9 +87,7 @@ impl datagram_common::Bound for BoundNetlinkRoute {
             }
         }
 
-        get_netlink_route_kernel().request(&nlmsg, |response| {
-            self.receive_queue.lock().push_back(response);
-        });
+        get_netlink_route_kernel().request(&nlmsg, local_port);
 
         Ok(nlmsg.total_len())
     }
@@ -114,7 +102,7 @@ impl datagram_common::Bound for BoundNetlinkRoute {
             warn!("unsupported flags: {:?}", flags);
         }
 
-        let mut receive_queue = self.receive_queue.lock();
+        let mut receive_queue = self.receive_queue.0.lock();
 
         let Some(response) = receive_queue.front() else {
             return_errno_with_message!(Errno::EAGAIN, "nothing to receive");
@@ -138,13 +126,6 @@ impl datagram_common::Bound for BoundNetlinkRoute {
     }
 
     fn check_io_events(&self) -> IoEvents {
-        let mut events = IoEvents::OUT;
-
-        let receive_queue = self.receive_queue.lock();
-        if !receive_queue.is_empty() {
-            events |= IoEvents::IN;
-        }
-
-        events
+        self.check_io_events_common()
     }
 }

kernel/src/net/socket/netlink/route/kernel/mod.rs

@@ -7,7 +7,11 @@ use core::marker::PhantomData;
 
 use super::message::{RtnlMessage, RtnlSegment};
 use crate::{
-    net::socket::netlink::message::{CSegmentType, ErrorSegment, ProtocolSegment},
+    net::socket::netlink::{
+        addr::PortNum,
+        message::{CSegmentType, ErrorSegment, ProtocolSegment},
+        table::{NetlinkRouteProtocol, SupportedNetlinkProtocol},
+    },
     prelude::*,
 };
 
@@ -26,11 +30,7 @@ impl NetlinkRouteKernelSocket {
         }
     }
 
-    pub(super) fn request<F: FnMut(RtnlMessage)>(
-        &self,
-        request: &RtnlMessage,
-        mut consume_response: F,
-    ) {
+    pub(super) fn request(&self, request: &RtnlMessage, dst_port: PortNum) {
         debug!("netlink route request: {:?}", request);
 
         for segment in request.segments() {
@@ -61,7 +61,7 @@ impl NetlinkRouteKernelSocket {
 
             debug!("netlink route response: {:?}", response);
 
-            consume_response(response);
+            NetlinkRouteProtocol::unicast(dst_port, response).unwrap();
         }
     }
 }

kernel/src/net/socket/netlink/route/message/mod.rs

@@ -18,4 +18,4 @@ pub(super) use segment::{
 use crate::net::socket::netlink::message::Message;
 
 /// A netlink route message.
-pub(super) type RtnlMessage = Message<RtnlSegment>;
+pub(in crate::net::socket::netlink) type RtnlMessage = Message<RtnlSegment>;

kernel/src/net/socket/netlink/route/mod.rs

@@ -2,179 +2,12 @@
 
 //! Netlink Route Socket.
 
-use core::sync::atomic::{AtomicBool, Ordering};
+pub(super) use message::RtnlMessage;
 
-use bound::BoundNetlinkRoute;
-use unbound::UnboundNetlinkRoute;
-
-use super::NetlinkSocketAddr;
-use crate::{
-    events::IoEvents,
-    net::socket::{
-        options::SocketOption,
-        private::SocketPrivate,
-        util::datagram_common::{select_remote_and_bind, Bound, Inner},
-        MessageHeader, SendRecvFlags, Socket, SocketAddr,
-    },
-    prelude::*,
-    process::signal::{PollHandle, Pollable, Pollee},
-    util::{MultiRead, MultiWrite},
-};
+use crate::net::socket::netlink::{common::NetlinkSocket, table::NetlinkRouteProtocol};
 
 mod bound;
 mod kernel;
 mod message;
-mod unbound;
 
-pub struct NetlinkRouteSocket {
-    inner: RwMutex<Inner<UnboundNetlinkRoute, BoundNetlinkRoute>>,
-
-    is_nonblocking: AtomicBool,
-    pollee: Pollee,
-}
-
-impl NetlinkRouteSocket {
-    pub fn new(is_nonblocking: bool) -> Self {
-        let unbound = UnboundNetlinkRoute::new();
-        Self {
-            inner: RwMutex::new(Inner::Unbound(unbound)),
-            is_nonblocking: AtomicBool::new(is_nonblocking),
-            pollee: Pollee::new(),
-        }
-    }
-
-    fn try_send(
-        &self,
-        reader: &mut dyn MultiRead,
-        remote: Option<&NetlinkSocketAddr>,
-        flags: SendRecvFlags,
-    ) -> Result<usize> {
-        let sent_bytes = select_remote_and_bind(
-            &self.inner,
-            remote,
-            || {
-                self.inner
-                    .write()
-                    .bind_ephemeral(&NetlinkSocketAddr::new_unspecified(), &self.pollee)
-            },
-            |bound, remote_endpoint| bound.try_send(reader, remote_endpoint, flags),
-        )?;
-        self.pollee.notify(IoEvents::OUT | IoEvents::IN);
-
-        Ok(sent_bytes)
-    }
-
-    fn try_recv(
-        &self,
-        writer: &mut dyn MultiWrite,
-        flags: SendRecvFlags,
-    ) -> Result<(usize, SocketAddr)> {
-        let recv_bytes = self
-            .inner
-            .read()
-            .try_recv(writer, flags)
-            .map(|(recv_bytes, remote_endpoint)| (recv_bytes, remote_endpoint.into()))?;
-        self.pollee.invalidate();
-
-        Ok(recv_bytes)
-    }
-}
-
-impl Socket for NetlinkRouteSocket {
-    fn bind(&self, socket_addr: SocketAddr) -> Result<()> {
-        let endpoint = socket_addr.try_into()?;
-
-        // FIXME: We need to further check the Linux behavior
-        // whether we should return error if the socket is bound.
-        // The socket may call `bind` syscall to join new multicast groups.
-        self.inner.write().bind(&endpoint, &self.pollee, ())
-    }
-
-    fn connect(&self, socket_addr: SocketAddr) -> Result<()> {
-        let endpoint = socket_addr.try_into()?;
-
-        self.inner.write().connect(&endpoint, &self.pollee)
-    }
-
-    fn addr(&self) -> Result<SocketAddr> {
-        let endpoint = self
-            .inner
-            .read()
-            .addr()
-            .unwrap_or(NetlinkSocketAddr::new_unspecified());
-
-        Ok(endpoint.into())
-    }
-
-    fn peer_addr(&self) -> Result<SocketAddr> {
-        let endpoint = self
-            .inner
-            .read()
-            .peer_addr()
-            .cloned()
-            .unwrap_or(NetlinkSocketAddr::new_unspecified());
-
-        Ok(endpoint.into())
-    }
-
-    fn sendmsg(
-        &self,
-        reader: &mut dyn MultiRead,
-        message_header: MessageHeader,
-        flags: SendRecvFlags,
-    ) -> Result<usize> {
-        let MessageHeader {
-            addr,
-            control_message,
-        } = message_header;
-
-        let remote = match addr {
-            None => None,
-            Some(addr) => Some(addr.try_into()?),
-        };
-
-        if control_message.is_some() {
-            // TODO: Support sending control message
-            warn!("sending control message is not supported");
-        }
-
-        // TODO: Make sure our blocking behavior matches that of Linux
-        self.try_send(reader, remote.as_ref(), flags)
-    }
-
-    fn recvmsg(
-        &self,
-        writers: &mut dyn MultiWrite,
-        flags: SendRecvFlags,
-    ) -> Result<(usize, MessageHeader)> {
-        let (received_len, addr) = self.block_on(IoEvents::IN, || self.try_recv(writers, flags))?;
-
-        // TODO: Receive control message
-
-        let message_header = MessageHeader::new(Some(addr), None);
-
-        Ok((received_len, message_header))
-    }
-
-    fn set_option(&self, _option: &dyn SocketOption) -> Result<()> {
-        // TODO: This dummy option is added to pass the libnl test
-        Ok(())
-    }
-}
-
-impl SocketPrivate for NetlinkRouteSocket {
-    fn is_nonblocking(&self) -> bool {
-        self.is_nonblocking.load(Ordering::Relaxed)
-    }
-
-    fn set_nonblocking(&self, nonblocking: bool) {
-        self.is_nonblocking.store(nonblocking, Ordering::Relaxed);
-    }
-}
-
-impl Pollable for NetlinkRouteSocket {
-    fn poll(&self, mask: IoEvents, poller: Option<&mut PollHandle>) -> IoEvents {
-        self.pollee
-            .poll_with(mask, poller, || self.inner.read().check_io_events())
-    }
-}
+pub type NetlinkRouteSocket = NetlinkSocket<NetlinkRouteProtocol>;

kernel/src/net/socket/netlink/route/unbound.rs

@@ -1,58 +0,0 @@
-// SPDX-License-Identifier: MPL-2.0
-
-use super::bound::BoundNetlinkRoute;
-use crate::{
-    events::IoEvents,
-    net::socket::{
-        netlink::{table::NETLINK_SOCKET_TABLE, NetlinkSocketAddr, StandardNetlinkProtocol},
-        util::datagram_common,
-    },
-    prelude::*,
-    process::signal::Pollee,
-};
-
-pub(super) struct UnboundNetlinkRoute {
-    _private: (),
-}
-
-impl UnboundNetlinkRoute {
-    pub(super) const fn new() -> Self {
-        Self { _private: () }
-    }
-}
-
-impl datagram_common::Unbound for UnboundNetlinkRoute {
-    type Endpoint = NetlinkSocketAddr;
-    type BindOptions = ();
-
-    type Bound = BoundNetlinkRoute;
-
-    fn bind(
-        &mut self,
-        endpoint: &Self::Endpoint,
-        _pollee: &Pollee,
-        _options: Self::BindOptions,
-    ) -> Result<BoundNetlinkRoute> {
-        let bound_handle =
-            NETLINK_SOCKET_TABLE.bind(StandardNetlinkProtocol::ROUTE as _, endpoint)?;
-
-        Ok(BoundNetlinkRoute::new(bound_handle))
-    }
-
-    fn bind_ephemeral(
-        &mut self,
-        _remote_endpoint: &Self::Endpoint,
-        _pollee: &Pollee,
-    ) -> Result<Self::Bound> {
-        let bound_handle = NETLINK_SOCKET_TABLE.bind(
-            StandardNetlinkProtocol::ROUTE as _,
-            &NetlinkSocketAddr::new_unspecified(),
-        )?;
-
-        Ok(BoundNetlinkRoute::new(bound_handle))
-    }
-
-    fn check_io_events(&self) -> IoEvents {
-        IoEvents::OUT
-    }
-}

kernel/src/net/socket/netlink/table/mod.rs

@@ -1,57 +1,82 @@
 // SPDX-License-Identifier: MPL-2.0
 
 use multicast::MulticastGroup;
+pub(super) use multicast::MulticastMessage;
+use spin::Once;
 
 use super::addr::{GroupIdSet, NetlinkProtocolId, NetlinkSocketAddr, PortNum, MAX_GROUPS};
-use crate::{net::socket::netlink::addr::UNSPECIFIED_PORT, prelude::*, util::random::getrandom};
+use crate::{
+    net::socket::netlink::{
+        addr::UNSPECIFIED_PORT, kobject_uevent::UeventMessage, receiver::MessageReceiver,
+        route::RtnlMessage,
+    },
+    prelude::*,
+    util::random::getrandom,
+};
 
 mod multicast;
 
-pub(super) static NETLINK_SOCKET_TABLE: NetlinkSocketTable = NetlinkSocketTable::new();
+static NETLINK_SOCKET_TABLE: Once<NetlinkSocketTable> = Once::new();
 
 /// All bound netlink sockets.
-pub(super) struct NetlinkSocketTable {
-    protocols: [Mutex<Option<ProtocolSocketTable>>; MAX_ALLOWED_PROTOCOL_ID as usize],
+struct NetlinkSocketTable {
+    route: RwMutex<ProtocolSocketTable<RtnlMessage>>,
+    uevent: RwMutex<ProtocolSocketTable<UeventMessage>>,
 }
 
 impl NetlinkSocketTable {
-    pub(super) const fn new() -> Self {
+    fn new() -> Self {
         Self {
-            protocols: [const { Mutex::new(None) }; MAX_ALLOWED_PROTOCOL_ID as usize],
+            route: RwMutex::new(ProtocolSocketTable::new()),
+            uevent: RwMutex::new(ProtocolSocketTable::new()),
+        }
     }
 }
 
-    /// Adds a new netlink protocol.
-    fn add_new_protocol(&self, protocol_id: NetlinkProtocolId) {
-        if protocol_id >= MAX_ALLOWED_PROTOCOL_ID {
-            return;
-        }
+pub trait SupportedNetlinkProtocol {
+    type Message: 'static + Send;
 
-        let mut protocol = self.protocols[protocol_id as usize].lock();
-        if protocol.is_some() {
-            return;
-        }
+    fn socket_table() -> &'static RwMutex<ProtocolSocketTable<Self::Message>>;
 
-        let new_protocol = ProtocolSocketTable::new(protocol_id);
-        *protocol = Some(new_protocol);
-    }
-
-    pub(super) fn bind(
-        &self,
-        protocol: NetlinkProtocolId,
+    fn bind(
         addr: &NetlinkSocketAddr,
-    ) -> Result<BoundHandle> {
-        if protocol >= MAX_ALLOWED_PROTOCOL_ID {
-            return_errno_with_message!(Errno::EINVAL, "the netlink protocol does not exist");
+        receiver: MessageReceiver<Self::Message>,
+    ) -> Result<BoundHandle<Self::Message>> {
+        let mut socket_table = Self::socket_table().write();
+        socket_table.bind(Self::socket_table(), addr, receiver)
     }
 
-        let mut protocol = self.protocols[protocol as usize].lock();
+    fn unicast(dst_port: PortNum, message: Self::Message) -> Result<()> {
+        let socket_table = Self::socket_table().read();
+        socket_table.unicast(dst_port, message)
+    }
 
-        let Some(protocol_sockets) = protocol.as_mut() else {
-            return_errno_with_message!(Errno::EINVAL, "the netlink protocol does not exist")
-        };
+    fn multicast(dst_groups: GroupIdSet, message: Self::Message) -> Result<()>
+    where
+        Self::Message: MulticastMessage,
+    {
+        let socket_table = Self::socket_table().read();
+        socket_table.multicast(dst_groups, message)
+    }
+}
 
-        protocol_sockets.bind(addr)
+pub enum NetlinkRouteProtocol {}
+
+impl SupportedNetlinkProtocol for NetlinkRouteProtocol {
+    type Message = RtnlMessage;
+
+    fn socket_table() -> &'static RwMutex<ProtocolSocketTable<Self::Message>> {
+        &NETLINK_SOCKET_TABLE.get().unwrap().route
+    }
+}
+
+pub enum NetlinkUeventProtocol {}
+
+impl SupportedNetlinkProtocol for NetlinkUeventProtocol {
+    type Message = UeventMessage;
+
+    fn socket_table() -> &'static RwMutex<ProtocolSocketTable<Self::Message>> {
+        &NETLINK_SOCKET_TABLE.get().unwrap().uevent
     }
 }
 
@@ -59,21 +84,17 @@ impl NetlinkSocketTable {
 ///
 /// Each table can have bound sockets for unicast
 /// and at most 32 groups for multicast.
-struct ProtocolSocketTable {
-    id: NetlinkProtocolId,
-    // TODO: This table should maintain the port number-to-socket relationship
-    // to support both unicast and multicast effectively.
-    unicast_sockets: BTreeSet<PortNum>,
+pub struct ProtocolSocketTable<Message> {
+    unicast_sockets: BTreeMap<PortNum, MessageReceiver<Message>>,
     multicast_groups: Box<[MulticastGroup]>,
 }
 
-impl ProtocolSocketTable {
+impl<Message: 'static> ProtocolSocketTable<Message> {
     /// Creates a new table.
-    fn new(id: NetlinkProtocolId) -> Self {
+    fn new() -> Self {
         let multicast_groups = (0u32..MAX_GROUPS).map(|_| MulticastGroup::new()).collect();
         Self {
-            id,
-            unicast_sockets: BTreeSet::new(),
+            unicast_sockets: BTreeMap::new(),
             multicast_groups,
         }
     }
@@ -89,29 +110,66 @@ impl ProtocolSocketTable {
     ///
     /// Additionally, this socket can join one or more multicast groups,
     /// as specified in `addr.groups()`.
-    fn bind(&mut self, addr: &NetlinkSocketAddr) -> Result<BoundHandle> {
+    fn bind(
+        &mut self,
+        socket_table: &'static RwMutex<ProtocolSocketTable<Message>>,
+        addr: &NetlinkSocketAddr,
+        receiver: MessageReceiver<Message>,
+    ) -> Result<BoundHandle<Message>> {
         let port = if addr.port() != UNSPECIFIED_PORT {
             addr.port()
         } else {
             let mut random_port = current!().pid();
-            while random_port == UNSPECIFIED_PORT || self.unicast_sockets.contains(&random_port) {
+            while random_port == UNSPECIFIED_PORT || self.unicast_sockets.contains_key(&random_port)
+            {
                 getrandom(random_port.as_bytes_mut()).unwrap();
             }
             random_port
         };
 
-        if self.unicast_sockets.contains(&port) {
+        if self.unicast_sockets.contains_key(&port) {
             return_errno_with_message!(Errno::EADDRINUSE, "the netlink port is already in use");
         }
 
-        self.unicast_sockets.insert(port);
+        self.unicast_sockets.insert(port, receiver);
 
         for group_id in addr.groups().ids_iter() {
             let group = &mut self.multicast_groups[group_id as usize];
             group.add_member(port);
         }
 
-        Ok(BoundHandle::new(self.id, port, addr.groups()))
+        Ok(BoundHandle::new(socket_table, port, addr.groups()))
+    }
+
+    fn unicast(&self, dst_port: PortNum, message: Message) -> Result<()> {
+        let Some(receiver) = self.unicast_sockets.get(&dst_port) else {
+            // FIXME: Should we return error here?
+            return Ok(());
+        };
+
+        receiver.enqueue_message(message)
+    }
+
+    fn multicast(&self, dst_groups: GroupIdSet, message: Message) -> Result<()>
+    where
+        Message: MulticastMessage,
+    {
+        for group in dst_groups.ids_iter() {
+            let Some(group) = self.multicast_groups.get(group as usize) else {
+                continue;
+            };
+
+            for port_num in group.members() {
+                let Some(receiver) = self.unicast_sockets.get(port_num) else {
+                    continue;
+                };
+
+                // FIXME: Should we slightly ignore the error if the socket's buffer has no enough space?
+                receiver.enqueue_message(message.clone())?;
+            }
+        }
+
+        Ok(())
     }
 }
 
@@ -119,19 +177,22 @@ impl ProtocolSocketTable {
 ///
 /// When dropping a `BoundHandle`,
 /// the port will be automatically released.
-#[derive(Debug)]
-pub(super) struct BoundHandle {
-    protocol: NetlinkProtocolId,
+pub struct BoundHandle<Message: 'static> {
+    socket_table: &'static RwMutex<ProtocolSocketTable<Message>>,
     port: PortNum,
     groups: GroupIdSet,
 }
 
-impl BoundHandle {
-    fn new(protocol: NetlinkProtocolId, port: PortNum, groups: GroupIdSet) -> Self {
+impl<Message: 'static> BoundHandle<Message> {
+    fn new(
+        socket_table: &'static RwMutex<ProtocolSocketTable<Message>>,
+        port: PortNum,
+        groups: GroupIdSet,
+    ) -> Self {
         debug_assert_ne!(port, UNSPECIFIED_PORT);
 
         Self {
-            protocol,
+            socket_table,
             port,
             groups,
         }
@@ -144,15 +205,49 @@ impl BoundHandle {
     pub(super) const fn addr(&self) -> NetlinkSocketAddr {
         NetlinkSocketAddr::new(self.port, self.groups)
     }
+
+    pub(super) fn add_groups(&mut self, groups: GroupIdSet) {
+        let mut protocol_sockets = self.socket_table.write();
+
+        for group_id in groups.ids_iter() {
+            let group = &mut protocol_sockets.multicast_groups[group_id as usize];
+            group.add_member(self.port);
         }
 
-impl Drop for BoundHandle {
-    fn drop(&mut self) {
-        let mut protocol_sockets = NETLINK_SOCKET_TABLE.protocols[self.protocol as usize].lock();
+        self.groups.add_groups(groups);
+    }
 
-        let Some(protocol_sockets) = protocol_sockets.as_mut() else {
-            return;
-        };
+    pub(super) fn drop_groups(&mut self, groups: GroupIdSet) {
+        let mut protocol_sockets = self.socket_table.write();
+
+        for group_id in groups.ids_iter() {
+            let group = &mut protocol_sockets.multicast_groups[group_id as usize];
+            group.remove_member(self.port);
+        }
+
+        self.groups.drop_groups(groups);
+    }
+
+    pub(super) fn bind_groups(&mut self, groups: GroupIdSet) {
+        let mut protocol_sockets = self.socket_table.write();
+
+        for group_id in self.groups.ids_iter() {
+            let group = &mut protocol_sockets.multicast_groups[group_id as usize];
+            group.remove_member(self.port);
+        }
+
+        for group_id in groups.ids_iter() {
+            let group = &mut protocol_sockets.multicast_groups[group_id as usize];
+            group.add_member(self.port);
+        }
+
+        self.groups = groups;
+    }
+}
+
+impl<Message: 'static> Drop for BoundHandle<Message> {
+    fn drop(&mut self) {
+        let mut protocol_sockets = self.socket_table.write();
 
         protocol_sockets.unicast_sockets.remove(&self.port);
 
@@ -164,11 +259,7 @@ impl Drop for BoundHandle {
 }
 
 pub(super) fn init() {
-    for protocol in 0..MAX_ALLOWED_PROTOCOL_ID {
-        if is_standard_protocol(protocol) {
-            NETLINK_SOCKET_TABLE.add_new_protocol(protocol);
-        }
-    }
+    NETLINK_SOCKET_TABLE.call_once(|| NetlinkSocketTable::new());
 }
 
 /// Returns whether the `protocol` is valid.
@@ -176,11 +267,6 @@ pub fn is_valid_protocol(protocol: NetlinkProtocolId) -> bool {
     protocol < MAX_ALLOWED_PROTOCOL_ID
 }
 
-/// Returns whether the `protocol` is reserved for system use.
-fn is_standard_protocol(protocol: NetlinkProtocolId) -> bool {
-    StandardNetlinkProtocol::try_from(protocol).is_ok()
-}
-
 /// Netlink protocols that are assigned for specific usage.
 ///
 /// Reference: <https://elixir.bootlin.com/linux/v6.0.9/source/include/uapi/linux/netlink.h#L9>.

kernel/src/net/socket/netlink/table/multicast.rs

@@ -18,21 +18,20 @@ impl MulticastGroup {
         }
     }
 
-    /// Returns whether the group contains a member.
-    #[expect(unused)]
-    pub fn contains_member(&self, port_num: PortNum) -> bool {
-        self.members.contains(&port_num)
-    }
-
     /// Adds a new member to the multicast group.
     pub fn add_member(&mut self, port_num: PortNum) {
-        debug_assert!(!self.members.contains(&port_num));
         self.members.insert(port_num);
     }
 
     /// Removes a member from the multicast group.
     pub fn remove_member(&mut self, port_num: PortNum) {
-        debug_assert!(self.members.contains(&port_num));
         self.members.remove(&port_num);
     }
+
+    /// Returns all members in this group.
+    pub fn members(&self) -> &BTreeSet<PortNum> {
+        &self.members
     }
+}
+
+pub trait MulticastMessage: Clone {}

kernel/src/net/socket/util/datagram_common.rs

@@ -36,6 +36,9 @@ pub trait Bound {
     type Endpoint;
 
     fn local_endpoint(&self) -> Self::Endpoint;
+    fn bind(&mut self, _endpoint: &Self::Endpoint) -> Result<()> {
+        return_errno_with_message!(Errno::EINVAL, "the socket is already bound to an address")
+    }
     fn remote_endpoint(&self) -> Option<&Self::Endpoint>;
     fn set_remote_endpoint(&mut self, endpoint: &Self::Endpoint);
 
@@ -72,11 +75,8 @@ where
     ) -> Result<()> {
         let unbound_datagram = match self {
             Inner::Unbound(unbound_datagram) => unbound_datagram,
-            Inner::Bound(_) => {
-                return_errno_with_message!(
-                    Errno::EINVAL,
-                    "the socket is already bound to an address"
-                )
+            Inner::Bound(bound_datagram) => {
+                return bound_datagram.bind(endpoint);
             }
         };
 

kernel/src/syscall/socket.rs

@@ -5,7 +5,9 @@ use crate::{
     fs::{file_handle::FileLike, file_table::FdFlags},
     net::socket::{
         ip::{datagram::DatagramSocket, stream::StreamSocket},
-        netlink::{is_valid_protocol, NetlinkRouteSocket, StandardNetlinkProtocol},
+        netlink::{
+            is_valid_protocol, NetlinkRouteSocket, NetlinkUeventSocket, StandardNetlinkProtocol,
+        },
         unix::UnixStreamSocket,
         vsock::VsockStreamSocket,
     },
@@ -52,7 +54,10 @@ pub fn sys_socket(domain: i32, type_: i32, protocol: i32, ctx: &Context) -> Resu
             debug!("netlink family = {:?}", netlink_family);
             match netlink_family {
                 Ok(StandardNetlinkProtocol::ROUTE) => {
-                    Arc::new(NetlinkRouteSocket::new(is_nonblocking))
+                    NetlinkRouteSocket::new(is_nonblocking) as Arc<dyn FileLike>
+                }
+                Ok(StandardNetlinkProtocol::KOBJECT_UEVENT) => {
+                    NetlinkUeventSocket::new(is_nonblocking) as Arc<dyn FileLike>
                 }
                 Ok(_) => {
                     return_errno_with_message!(

kernel/src/util/net/options/mod.rs

@@ -52,10 +52,12 @@
 //!
 
 use ip::new_ip_option;
+use netlink::new_netlink_option;
 
 use crate::{net::socket::options::SocketOption, prelude::*};
 
 mod ip;
+mod netlink;
 mod socket;
 mod tcp;
 mod utils;
@@ -130,6 +132,34 @@ macro_rules! impl_raw_sock_option_get_only {
     };
 }
 
+/// Impl `RawSocketOption` for a struct which is for only `setsockopt` and implements `SocketOption`.
+#[macro_export]
+macro_rules! impl_raw_sock_option_set_only {
+    ($option:ty) => {
+        impl RawSocketOption for $option {
+            fn read_from_user(&mut self, addr: Vaddr, max_len: u32) -> Result<()> {
+                use $crate::util::net::options::utils::ReadFromUser;
+
+                let input = ReadFromUser::read_from_user(addr, max_len)?;
+                self.set(input);
+                Ok(())
+            }
+
+            fn write_to_user(&self, _addr: Vaddr, _max_len: u32) -> Result<usize> {
+                return_errno_with_message!(Errno::ENOPROTOOPT, "the option is setter-only");
+            }
+
+            fn as_sock_option_mut(&mut self) -> &mut dyn SocketOption {
+                self
+            }
+
+            fn as_sock_option(&self) -> &dyn SocketOption {
+                self
+            }
+        }
+    };
+}
+
 pub fn new_raw_socket_option(
     level: CSocketOptionLevel,
     name: i32,
@@ -138,6 +168,7 @@ pub fn new_raw_socket_option(
         CSocketOptionLevel::SOL_SOCKET => new_socket_option(name),
         CSocketOptionLevel::SOL_IP => new_ip_option(name),
         CSocketOptionLevel::SOL_TCP => new_tcp_option(name),
+        CSocketOptionLevel::SOL_NETLINK => new_netlink_option(name),
         _ => return_errno_with_message!(Errno::EOPNOTSUPP, "unsupported option level"),
     }
 }
@@ -153,4 +184,5 @@ pub enum CSocketOptionLevel {
     SOL_UDP = 17,
     SOL_IPV6 = 41,
     SOL_RAW = 255,
+    SOL_NETLINK = 270,
 }

kernel/src/util/net/options/netlink.rs

@@ -0,0 +1,34 @@
+// SPDX-License-Identifier: MPL-2.0
+
+use super::RawSocketOption;
+use crate::{
+    impl_raw_sock_option_set_only,
+    net::socket::netlink::{AddMembership, DropMembership},
+    prelude::*,
+    util::net::options::SocketOption,
+};
+
+/// Socket options for netlink socket.
+///
+/// Reference: <https://elixir.bootlin.com/linux/v6.0.9/source/include/uapi/linux/netlink.h#L149>.
+#[repr(i32)]
+#[derive(Debug, Clone, Copy, TryFromInt)]
+#[expect(non_camel_case_types)]
+#[expect(clippy::upper_case_acronyms)]
+pub enum CNetlinkOptionName {
+    ADD_MEMBERSHIP = 1,
+    DROP_MEMBERSHIP = 2,
+    PKTINFO = 3,
+}
+
+pub fn new_netlink_option(name: i32) -> Result<Box<dyn RawSocketOption>> {
+    let name = CNetlinkOptionName::try_from(name).map_err(|_| Errno::ENOPROTOOPT)?;
+    match name {
+        CNetlinkOptionName::ADD_MEMBERSHIP => Ok(Box::new(AddMembership::new())),
+        CNetlinkOptionName::DROP_MEMBERSHIP => Ok(Box::new(DropMembership::new())),
+        _ => return_errno_with_message!(Errno::ENOPROTOOPT, "unsupported netlink option"),
+    }
+}
+
+impl_raw_sock_option_set_only!(AddMembership);
+impl_raw_sock_option_set_only!(DropMembership);