Add AF_VSOCK based SocketAddr

This is necessary in order to connect to AF_VSOCK sockets, or listen
on the AF_VSOCK socket type.

Signed-off-by: John Nunley <dev@notgull.net>

Author: notgull

Cargo.toml

@@ -33,7 +33,7 @@ rustc-std-workspace-alloc = { version = "1.0.0", optional = true } # not aliased
 # libc backend can be selected via adding `--cfg=rustix_use_libc` to
 # `RUSTFLAGS` or enabling the `use-libc` cargo feature.
 [target.'cfg(all(not(rustix_use_libc), not(miri), target_os = "linux", any(target_endian = "little", any(target_arch = "s390x", target_arch = "powerpc")), any(target_arch = "arm", all(target_arch = "aarch64", target_pointer_width = "64"), target_arch = "riscv64", all(rustix_use_experimental_asm, target_arch = "powerpc"), all(rustix_use_experimental_asm, target_arch = "powerpc64"), all(rustix_use_experimental_asm, target_arch = "s390x"), all(rustix_use_experimental_asm, target_arch = "mips"), all(rustix_use_experimental_asm, target_arch = "mips32r6"), all(rustix_use_experimental_asm, target_arch = "mips64"), all(rustix_use_experimental_asm, target_arch = "mips64r6"), target_arch = "x86", all(target_arch = "x86_64", target_pointer_width = "64"))))'.dependencies]
-linux-raw-sys = { version = "0.11.0", default-features = false, features = ["auxvec", "general", "errno", "ioctl", "no_std", "elf"] }
+linux-raw-sys = { git = "https://github.com/forkgull/linux-raw-sys", branch = "notgull/vsock", default-features = false, features = ["auxvec", "general", "errno", "ioctl", "no_std", "elf"] }
 libc_errno = { package = "errno", version = "0.3.10", default-features = false, optional = true }
 libc = { version = "0.2.177", default-features = false, optional = true }
 
@@ -50,7 +50,7 @@ libc = { version = "0.2.177", default-features = false }
 # Some syscalls do not have libc wrappers, such as in `io_uring`. For these,
 # the libc backend uses the linux-raw-sys ABI and `libc::syscall`.
 [target.'cfg(all(any(target_os = "linux"), any(rustix_use_libc, miri, not(all(target_os = "linux", any(target_endian = "little", any(target_arch = "s390x", target_arch = "powerpc")), any(target_arch = "arm", all(target_arch = "aarch64", target_pointer_width = "64"), target_arch = "riscv64", all(rustix_use_experimental_asm, target_arch = "powerpc"), all(rustix_use_experimental_asm, target_arch = "powerpc64"), all(rustix_use_experimental_asm, target_arch = "s390x"), all(rustix_use_experimental_asm, target_arch = "mips"), all(rustix_use_experimental_asm, target_arch = "mips32r6"), all(rustix_use_experimental_asm, target_arch = "mips64"), all(rustix_use_experimental_asm, target_arch = "mips64r6"), target_arch = "x86", all(target_arch = "x86_64", target_pointer_width = "64")))))))'.dependencies]
-linux-raw-sys = { version = "0.11.0", default-features = false, features = ["general", "ioctl", "no_std"] }
+linux-raw-sys = { git = "https://github.com/forkgull/linux-raw-sys", branch = "notgull/vsock", default-features = false, features = ["general", "ioctl", "no_std"] }
 
 # For the libc backend on Windows, use the Winsock API in windows-sys.
 [target.'cfg(windows)'.dependencies.windows-sys]
@@ -132,7 +132,7 @@ io_uring = ["event", "fs", "net", "thread", "linux-raw-sys/io_uring"]
 mount = []
 
 # Enable `rustix::net::*`.
-net = ["linux-raw-sys/net", "linux-raw-sys/netlink", "linux-raw-sys/if_ether", "linux-raw-sys/xdp"]
+net = ["linux-raw-sys/net", "linux-raw-sys/netlink", "linux-raw-sys/if_ether", "linux-raw-sys/vm_sockets", "linux-raw-sys/xdp"]
 
 # Enable `rustix::thread::*`.
 thread = ["linux-raw-sys/prctl"]

src/backend/libc/net/read_sockaddr.rs

@@ -11,6 +11,8 @@ use crate::io::Errno;
 use crate::net::addr::SocketAddrLen;
 #[cfg(linux_kernel)]
 use crate::net::netlink::SocketAddrNetlink;
+#[cfg(any(linux_kernel, apple))]
+use crate::net::vsock::SocketAddrVSock;
 #[cfg(target_os = "linux")]
 use crate::net::xdp::{SocketAddrXdp, SocketAddrXdpFlags};
 use crate::net::{AddressFamily, Ipv4Addr, Ipv6Addr, SocketAddrAny, SocketAddrV4, SocketAddrV6};
@@ -262,3 +264,15 @@ pub(crate) fn read_sockaddr_netlink(addr: &SocketAddrAny) -> Result<SocketAddrNe
     let decode = unsafe { &*addr.as_ptr().cast::<c::sockaddr_nl>() };
     Ok(SocketAddrNetlink::new(decode.nl_pid, decode.nl_groups))
 }
+
+#[cfg(any(linux_kernel, apple))]
+#[inline]
+pub(crate) fn read_sockaddr_vsock(addr: &SocketAddrAny) -> Result<SocketAddrVSock, Errno> {
+    if addr.address_family() != AddressFamily::VSOCK {
+        return Err(Errno::AFNOSUPPORT);
+    }
+
+    assert!(addr.addr_len() as usize >= size_of::<c::sockaddr_vm>());
+    let decode = unsafe { &*addr.as_ptr().cast::<c::sockaddr_vm>() };
+    Ok(SocketAddrVSock::new(decode.svm_cid, decode.svm_port))
+}

src/backend/linux_raw/c.rs

@@ -105,6 +105,7 @@ pub(crate) use linux_raw_sys::{
         TCP_QUICKACK, TCP_THIN_LINEAR_TIMEOUTS, TCP_USER_TIMEOUT,
     },
     netlink::*,
+    vm_sockets::sockaddr_vm,
     xdp::{
         sockaddr_xdp, xdp_desc, xdp_mmap_offsets, xdp_mmap_offsets_v1, xdp_options,
         xdp_ring_offset, xdp_ring_offset_v1, xdp_statistics, xdp_statistics_v1, xdp_umem_reg,

src/backend/linux_raw/net/read_sockaddr.rs

@@ -6,6 +6,7 @@ use crate::backend::c;
 use crate::io::Errno;
 use crate::net::addr::SocketAddrLen;
 use crate::net::netlink::SocketAddrNetlink;
+use crate::net::vsock::SocketAddrVSock;
 #[cfg(target_os = "linux")]
 use crate::net::xdp::{SocketAddrXdp, SocketAddrXdpFlags};
 use crate::net::{
@@ -153,3 +154,14 @@ pub(crate) fn read_sockaddr_netlink(addr: &SocketAddrAny) -> Result<SocketAddrNe
     let decode = unsafe { &*addr.as_ptr().cast::<c::sockaddr_nl>() };
     Ok(SocketAddrNetlink::new(decode.nl_pid, decode.nl_groups))
 }
+
+#[inline]
+pub(crate) fn read_sockaddr_vsock(addr: &SocketAddrAny) -> Result<SocketAddrVSock, Errno> {
+    if addr.address_family() != AddressFamily::VSOCK {
+        return Err(Errno::AFNOSUPPORT);
+    }
+
+    assert!(addr.addr_len() as usize >= size_of::<c::sockaddr_vm>());
+    let decode = unsafe { &*addr.as_ptr().cast::<c::sockaddr_vm>() };
+    Ok(SocketAddrVSock::new(decode.svm_cid, decode.svm_port))
+}

src/net/socket_addr_any.rs

@@ -225,6 +225,12 @@ impl fmt::Debug for SocketAddrAny {
                     return addr.fmt(f);
                 }
             }
+            #[cfg(any(linux_kernel, apple))]
+            AddressFamily::VSOCK => {
+                if let Ok(addr) = crate::net::vsock::SocketAddrVSock::try_from(self.clone()) {
+                    return addr.fmt(f);
+                }
+            }
             _ => {}
         }
 

src/net/types.rs

@@ -2081,6 +2081,105 @@ pub mod xdp {
     pub const XSK_UNALIGNED_BUF_ADDR_MASK: u64 = c::XSK_UNALIGNED_BUF_ADDR_MASK;
 }
 
+/// `AF_VSOCK` and related types.
+#[cfg(any(linux_kernel, apple))]
+pub mod vsock {
+    use crate::backend::net::read_sockaddr::read_sockaddr_vsock;
+    use crate::net::addr::{call_with_sockaddr, SocketAddrArg, SocketAddrLen, SocketAddrOpaque};
+    use crate::net::SocketAddrAny;
+
+    use super::c;
+    use core::mem;
+
+    /// A VSock socket address.
+    ///
+    /// Used to bind to a VSock socket. Not ABI compatible with `sockadr_vm`.
+    #[derive(Clone, PartialEq, PartialOrd, Eq, Ord, Hash, Debug)]
+    pub struct SocketAddrVSock {
+        /// The Context IDentifier (CID) to connect to.
+        cid: u32,
+        /// The port to connect to.
+        port: u32,
+    }
+
+    impl SocketAddrVSock {
+        /// Construct a new VSock address.
+        #[inline]
+        pub const fn new(cid: u32, port: u32) -> Self {
+            Self { cid, port }
+        }
+
+        /// Context IDentifier (CID), referring to the VM to connect to.
+        #[inline]
+        pub fn cid(&self) -> u32 {
+            self.cid
+        }
+
+        /// Set the context identifier.
+        #[inline]
+        pub fn set_cid(&mut self, cid: u32) {
+            self.cid = cid;
+        }
+
+        /// Port to connect to.
+        #[inline]
+        pub fn port(&self) -> u32 {
+            self.port
+        }
+
+        /// Set the port to connect to.
+        #[inline]
+        pub fn set_port(&mut self, port: u32) {
+            self.port = port;
+        }
+    }
+
+    #[allow(unsafe_code)]
+    // SAFETY: `with_sockaddr` calls `f` using `call_with_sockaddr`, which
+    // handles calling `f` with the needed preconditions.
+    unsafe impl SocketAddrArg for SocketAddrVSock {
+        unsafe fn with_sockaddr<R>(
+            &self,
+            f: impl FnOnce(*const SocketAddrOpaque, SocketAddrLen) -> R,
+        ) -> R {
+            let addr = c::sockaddr_vm {
+                svm_family: c::AF_VSOCK as _,
+                svm_cid: self.cid,
+                svm_port: self.port,
+                ..mem::zeroed()
+            };
+
+            call_with_sockaddr(&addr, f)
+        }
+    }
+
+    impl From<SocketAddrVSock> for SocketAddrAny {
+        #[inline]
+        fn from(from: SocketAddrVSock) -> Self {
+            from.as_any()
+        }
+    }
+
+    impl TryFrom<SocketAddrAny> for SocketAddrVSock {
+        type Error = crate::io::Errno;
+
+        fn try_from(addr: SocketAddrAny) -> Result<Self, Self::Error> {
+            read_sockaddr_vsock(&addr)
+        }
+    }
+
+    /// CID to connect to any host.
+    pub const VMADDR_CID_ANY: u32 = 0xFFFFFFFF;
+    /// CID to connect to the hypervisor.
+    pub const VMADDR_CID_HYPERVISOR: u32 = 0;
+    /// CID to connect to the local host.
+    pub const VMADDR_CID_LOCAL: u32 = 1;
+    /// CID to connect to the host.
+    pub const VMADDR_CID_HOST: u32 = 2;
+    /// Connect to any port.
+    pub const VMADDR_PORT_ANY: u32 = 0xFFFFFFFF;
+}
+
 /// UNIX credentials of socket peer, for use with [`get_socket_peercred`]
 /// [`SendAncillaryMessage::ScmCredentials`] and
 /// [`RecvAncillaryMessage::ScmCredentials`].

tests/net/main.rs

@@ -23,6 +23,7 @@ mod unix;
 mod unix_alloc;
 mod v4;
 mod v6;
+mod vsock;
 
 #[cfg(windows)]
 mod windows {