Merge pull request torvalds#744 from wedsonaf/socket

rust: add basic tcp socket support

rust/kernel/net.rs

@@ -6,7 +6,7 @@
 //! [`include/linux/netdevice.h`](../../../../include/linux/netdevice.h),
 //! [`include/linux/skbuff.h`](../../../../include/linux/skbuff.h).
 
-use crate::{bindings, str::CStr, ARef, AlwaysRefCounted};
+use crate::{bindings, str::CStr, to_result, ARef, AlwaysRefCounted, Error, Result};
 use core::{cell::UnsafeCell, ptr::NonNull};
 
 #[cfg(CONFIG_NETFILTER)]
@@ -115,3 +115,278 @@ unsafe impl AlwaysRefCounted for SkBuff {
         };
     }
 }
+
+/// An IPv4 address.
+///
+/// This is equivalent to C's `in_addr`.
+#[repr(transparent)]
+pub struct Ipv4Addr(bindings::in_addr);
+
+impl Ipv4Addr {
+    /// A wildcard IPv4 address.
+    ///
+    /// Binding to this address means binding to all IPv4 addresses.
+    pub const ANY: Self = Self::new(0, 0, 0, 0);
+
+    /// The IPv4 loopback address.
+    pub const LOOPBACK: Self = Self::new(127, 0, 0, 1);
+
+    /// The IPv4 broadcast address.
+    pub const BROADCAST: Self = Self::new(255, 255, 255, 255);
+
+    /// Creates a new IPv4 address with the given components.
+    pub const fn new(a: u8, b: u8, c: u8, d: u8) -> Self {
+        Self(bindings::in_addr {
+            s_addr: u32::from_be_bytes([a, b, c, d]).to_be(),
+        })
+    }
+}
+
+/// An IPv6 address.
+///
+/// This is equivalent to C's `in6_addr`.
+#[repr(transparent)]
+pub struct Ipv6Addr(bindings::in6_addr);
+
+impl Ipv6Addr {
+    /// A wildcard IPv6 address.
+    ///
+    /// Binding to this address means binding to all IPv6 addresses.
+    pub const ANY: Self = Self::new(0, 0, 0, 0, 0, 0, 0, 0);
+
+    /// The IPv6 loopback address.
+    pub const LOOPBACK: Self = Self::new(0, 0, 0, 0, 0, 0, 0, 1);
+
+    /// Creates a new IPv6 address with the given components.
+    #[allow(clippy::too_many_arguments)]
+    pub const fn new(a: u16, b: u16, c: u16, d: u16, e: u16, f: u16, g: u16, h: u16) -> Self {
+        Self(bindings::in6_addr {
+            in6_u: bindings::in6_addr__bindgen_ty_1 {
+                u6_addr16: [
+                    a.to_be(),
+                    b.to_be(),
+                    c.to_be(),
+                    d.to_be(),
+                    e.to_be(),
+                    f.to_be(),
+                    g.to_be(),
+                    h.to_be(),
+                ],
+            },
+        })
+    }
+}
+
+/// A socket address.
+///
+/// It's an enum with either an IPv4 or IPv6 socket address.
+pub enum SocketAddr {
+    /// An IPv4 socket address.
+    V4(SocketAddrV4),
+
+    /// An IPv6 socket address.
+    V6(SocketAddrV6),
+}
+
+/// An IPv4 socket address.
+///
+/// This is equivalent to C's `sockaddr_in`.
+#[repr(transparent)]
+pub struct SocketAddrV4(bindings::sockaddr_in);
+
+impl SocketAddrV4 {
+    /// Creates a new IPv4 socket address.
+    pub const fn new(addr: Ipv4Addr, port: u16) -> Self {
+        Self(bindings::sockaddr_in {
+            sin_family: bindings::AF_INET as _,
+            sin_port: port.to_be(),
+            sin_addr: addr.0,
+            __pad: [0; 8],
+        })
+    }
+}
+
+/// An IPv6 socket address.
+///
+/// This is equivalent to C's `sockaddr_in6`.
+#[repr(transparent)]
+pub struct SocketAddrV6(bindings::sockaddr_in6);
+
+impl SocketAddrV6 {
+    /// Creates a new IPv6 socket address.
+    pub const fn new(addr: Ipv6Addr, port: u16, flowinfo: u32, scopeid: u32) -> Self {
+        Self(bindings::sockaddr_in6 {
+            sin6_family: bindings::AF_INET6 as _,
+            sin6_port: port.to_be(),
+            sin6_addr: addr.0,
+            sin6_flowinfo: flowinfo,
+            sin6_scope_id: scopeid,
+        })
+    }
+}
+
+/// A socket listening on a TCP port.
+///
+/// # Invariants
+///
+/// The socket pointer is always non-null and valid.
+pub struct TcpListener {
+    sock: *mut bindings::socket,
+}
+
+// SAFETY: `TcpListener` is just a wrapper for a kernel socket, which can be used from any thread.
+unsafe impl Send for TcpListener {}
+
+// SAFETY: `TcpListener` is just a wrapper for a kernel socket, which can be used from any thread.
+unsafe impl Sync for TcpListener {}
+
+impl TcpListener {
+    /// Creates a new TCP listener.
+    ///
+    /// It is configured to listen on the given socket address for the given namespace.
+    pub fn try_new(ns: &Namespace, addr: &SocketAddr) -> Result<Self> {
+        let mut socket = core::ptr::null_mut();
+        let (pf, addr, addrlen) = match addr {
+            SocketAddr::V4(addr) => (
+                bindings::PF_INET,
+                addr as *const _ as _,
+                core::mem::size_of::<bindings::sockaddr_in>(),
+            ),
+            SocketAddr::V6(addr) => (
+                bindings::PF_INET6,
+                addr as *const _ as _,
+                core::mem::size_of::<bindings::sockaddr_in6>(),
+            ),
+        };
+
+        // SAFETY: The namespace is valid and the output socket pointer is valid for write.
+        to_result(|| unsafe {
+            bindings::sock_create_kern(
+                ns.0.get(),
+                pf as _,
+                bindings::sock_type_SOCK_STREAM as _,
+                bindings::IPPROTO_TCP as _,
+                &mut socket,
+            )
+        })?;
+
+        // INVARIANT: The socket was just created, so it is valid.
+        let listener = Self { sock: socket };
+
+        // SAFETY: The type invariant guarantees that the socket is valid, and `addr` and `addrlen`
+        // were initialised based on valid values provided in the address enum.
+        to_result(|| unsafe { bindings::kernel_bind(socket, addr, addrlen as _) })?;
+
+        // SAFETY: The socket is valid per the type invariant.
+        to_result(|| unsafe { bindings::kernel_listen(socket, bindings::SOMAXCONN as _) })?;
+
+        Ok(listener)
+    }
+
+    /// Accepts a new connection.
+    ///
+    /// On success, returns the newly-accepted socket stream.
+    ///
+    /// If no connection is available to be accepted, one of two behaviours will occur:
+    /// - If `block` is `false`, returns [`crate::error::code::EAGAIN`];
+    /// - If `block` is `true`, blocks until an error occurs or some connection can be accepted.
+    pub fn accept(&self, block: bool) -> Result<TcpStream> {
+        let mut new = core::ptr::null_mut();
+        let flags = if block { 0 } else { bindings::O_NONBLOCK };
+        // SAFETY: The type invariant guarantees that the socket is valid, and the output argument
+        // is also valid for write.
+        to_result(|| unsafe { bindings::kernel_accept(self.sock, &mut new, flags as _) })?;
+        Ok(TcpStream { sock: new })
+    }
+}
+
+impl Drop for TcpListener {
+    fn drop(&mut self) {
+        // SAFETY: The type invariant guarantees that the socket is valid.
+        unsafe { bindings::sock_release(self.sock) };
+    }
+}
+
+/// A connected TCP socket.
+///
+/// # Invariants
+///
+/// The socket pointer is always non-null and valid.
+pub struct TcpStream {
+    sock: *mut bindings::socket,
+}
+
+// SAFETY: `TcpStream` is just a wrapper for a kernel socket, which can be used from any thread.
+unsafe impl Send for TcpStream {}
+
+// SAFETY: `TcpStream` is just a wrapper for a kernel socket, which can be used from any thread.
+unsafe impl Sync for TcpStream {}
+
+impl TcpStream {
+    /// Reads data from a connected socket.
+    ///
+    /// On success, returns the number of bytes read, which will be zero if the connection is
+    /// closed.
+    ///
+    /// If no data is immediately available for reading, one of two behaviours will occur:
+    /// - If `block` is `false`, returns [`crate::error::code::EAGAIN`];
+    /// - If `block` is `true`, blocks until an error occurs, the connection is closed, or some
+    ///   becomes readable.
+    pub fn read(&mut self, buf: &mut [u8], block: bool) -> Result<usize> {
+        let mut msg = bindings::msghdr::default();
+        let mut vec = bindings::kvec {
+            iov_base: buf.as_mut_ptr().cast(),
+            iov_len: buf.len(),
+        };
+        // SAFETY: The type invariant guarantees that the socket is valid, and `vec` was
+        // initialised with the output buffer.
+        let r = unsafe {
+            bindings::kernel_recvmsg(
+                self.sock,
+                &mut msg,
+                &mut vec,
+                1,
+                vec.iov_len,
+                if block { 0 } else { bindings::MSG_DONTWAIT } as _,
+            )
+        };
+        if r < 0 {
+            Err(Error::from_kernel_errno(r))
+        } else {
+            Ok(r as _)
+        }
+    }
+
+    /// Writes data to the connected socket.
+    ///
+    /// On success, returns the number of bytes written.
+    ///
+    /// If the send buffer of the socket is full, one of two behaviours will occur:
+    /// - If `block` is `false`, returns [`crate::error::code::EAGAIN`];
+    /// - If `block` is `true`, blocks until an error occurs or some data is written.
+    pub fn write(&mut self, buf: &[u8], block: bool) -> Result<usize> {
+        let mut msg = bindings::msghdr {
+            msg_flags: if block { 0 } else { bindings::MSG_DONTWAIT },
+            ..bindings::msghdr::default()
+        };
+        let mut vec = bindings::kvec {
+            iov_base: buf.as_ptr() as *mut u8 as _,
+            iov_len: buf.len(),
+        };
+        // SAFETY: The type invariant guarantees that the socket is valid, and `vec` was
+        // initialised with the input  buffer.
+        let r = unsafe { bindings::kernel_sendmsg(self.sock, &mut msg, &mut vec, 1, vec.iov_len) };
+        if r < 0 {
+            Err(Error::from_kernel_errno(r))
+        } else {
+            Ok(r as _)
+        }
+    }
+}
+
+impl Drop for TcpStream {
+    fn drop(&mut self) {
+        // SAFETY: The type invariant guarantees that the socket is valid.
+        unsafe { bindings::sock_release(self.sock) };
+    }
+}