Add UnixCredentials support on FreeBSD/DragonFly (cmsgcred/SCM_CREDS)

src/sys/socket/mod.rs

@@ -189,7 +189,8 @@ cfg_if! {
     if #[cfg(any(target_os = "android", target_os = "linux"))] {
         /// Unix credentials of the sending process.
         ///
-        /// This struct is used with the `SO_PEERCRED` ancillary message for UNIX sockets.
+        /// This struct is used with the `SO_PEERCRED` ancillary message
+        /// and the `SCM_CREDENTIALS` control message for UNIX sockets.
         #[repr(transparent)]
         #[derive(Clone, Copy, Debug, Eq, PartialEq)]
         pub struct UnixCredentials(libc::ucred);
@@ -222,8 +223,43 @@ cfg_if! {
                 self.0
             }
         }
-    }
-}
+    } else if #[cfg(any(target_os = "freebsd", target_os = "dragonfly"))] {
+        /// Unix credentials of the sending process.
+        ///
+        /// This struct is used with the `SCM_CREDS` ancillary message for UNIX sockets.
+        #[repr(transparent)]
+        #[derive(Clone, Copy, Debug, Eq, PartialEq)]
+        pub struct UnixCredentials(libc::cmsgcred);
+
+        impl UnixCredentials {
+            /// Returns the process identifier
+            pub fn pid(&self) -> libc::pid_t {
+                self.0.cmcred_pid
+            }
+
+            /// Returns the user identifier
+            pub fn uid(&self) -> libc::uid_t {
+                self.0.cmcred_uid
+            }
+
+            /// Returns the group identifier
+            pub fn gid(&self) -> libc::gid_t {
+                self.0.cmcred_gid
+            }
+        }
+
+        impl From<libc::cmsgcred> for UnixCredentials {
+            fn from(cred: libc::cmsgcred) -> Self {
+                UnixCredentials(cred)
+            }
+        }
+
+        impl Into<libc::cmsgcred> for UnixCredentials {
+            fn into(self) -> libc::cmsgcred {
+                self.0
+            }
+        }
+    }}
 
 /// Request for multicast socket operations
 ///
@@ -367,7 +403,12 @@ pub enum ControlMessageOwned {
     ScmRights(Vec<RawFd>),
     /// Received version of
     /// [`ControlMessage::ScmCredentials`][#enum.ControlMessage.html#variant.ScmCredentials]
-    #[cfg(any(target_os = "android", target_os = "linux"))]
+    #[cfg(any(
+        target_os = "android",
+        target_os = "linux",
+        target_os = "freebsd",
+        target_os = "dragonfly",
+    ))]
     ScmCredentials(UnixCredentials),
     /// A message of type `SCM_TIMESTAMP`, containing the time the
     /// packet was received by the kernel.
@@ -498,6 +539,11 @@ impl ControlMessageOwned {
                 let cred: libc::ucred = ptr::read_unaligned(p as *const _);
                 ControlMessageOwned::ScmCredentials(cred.into())
             }
+            #[cfg(any(target_os = "freebsd", target_os = "dragonfly"))]
+            (libc::SOL_SOCKET, /* libc::SCM_CREDS */ 0x03) => {
+                let cred: libc::cmsgcred = ptr::read_unaligned(p as *const _);
+                ControlMessageOwned::ScmCredentials(cred.into())
+            }
             (libc::SOL_SOCKET, libc::SCM_TIMESTAMP) => {
                 let tv: libc::timeval = ptr::read_unaligned(p as *const _);
                 ControlMessageOwned::ScmTimestamp(TimeVal::from(tv))
@@ -574,17 +620,25 @@ pub enum ControlMessage<'a> {
     /// Instead, you can put all fds to be passed into a single `ScmRights`
     /// message.
     ScmRights(&'a [RawFd]),
-    /// A message of type `SCM_CREDENTIALS`, containing the pid, uid and gid of
+    /// A message of type `SCM_CREDENTIALS`/`SCM_CREDS`, containing the pid, uid and gid of
     /// a process connected to the socket.
     ///
     /// This is similar to the socket option `SO_PEERCRED`, but requires a
-    /// process to explicitly send its credentials. A process running as root is
-    /// allowed to specify any credentials, while credentials sent by other
-    /// processes are verified by the kernel.
+    /// process to explicitly send its credentials.
+    ///
+    /// On Linux, a process running as root is allowed to specify any credentials,
+    /// while credentials sent by other processes are verified by the kernel.
+    ///
+    /// On FreeBSD/DragonFly, credentials are always overwritten by the kernel.
     ///
     /// For further information, please refer to the
     /// [`unix(7)`](http://man7.org/linux/man-pages/man7/unix.7.html) man page.
-    #[cfg(any(target_os = "android", target_os = "linux"))]
+    #[cfg(any(
+        target_os = "android",
+        target_os = "linux",
+        target_os = "freebsd",
+        target_os = "dragonfly",
+    ))]
     ScmCredentials(&'a UnixCredentials),
 
     /// Set IV for `AF_ALG` crypto API.
@@ -655,6 +709,10 @@ impl<'a> ControlMessage<'a> {
             ControlMessage::ScmCredentials(creds) => {
                 &creds.0 as *const libc::ucred as *const u8
             }
+            #[cfg(any(target_os = "freebsd", target_os = "dragonfly"))]
+            ControlMessage::ScmCredentials(creds) => {
+                &creds.0 as *const libc::cmsgcred as *const u8
+            }
             #[cfg(any(target_os = "android", target_os = "linux"))]
             ControlMessage::AlgSetIv(iv) => {
                 unsafe {
@@ -692,7 +750,12 @@ impl<'a> ControlMessage<'a> {
             ControlMessage::ScmRights(fds) => {
                 mem::size_of_val(fds)
             },
-            #[cfg(any(target_os = "android", target_os = "linux"))]
+            #[cfg(any(
+                target_os = "android",
+                target_os = "linux",
+                target_os = "freebsd",
+                target_os = "dragonfly",
+            ))]
             ControlMessage::ScmCredentials(creds) => {
                 mem::size_of_val(creds)
             }
@@ -715,7 +778,12 @@ impl<'a> ControlMessage<'a> {
     fn cmsg_level(&self) -> libc::c_int {
         match *self {
             ControlMessage::ScmRights(_) => libc::SOL_SOCKET,
-            #[cfg(any(target_os = "android", target_os = "linux"))]
+            #[cfg(any(
+                target_os = "android",
+                target_os = "linux",
+                target_os = "freebsd",
+                target_os = "dragonfly",
+            ))]
             ControlMessage::ScmCredentials(_) => libc::SOL_SOCKET,
             #[cfg(any(target_os = "android", target_os = "linux"))]
             ControlMessage::AlgSetIv(_) | ControlMessage::AlgSetOp(_) |
@@ -729,6 +797,8 @@ impl<'a> ControlMessage<'a> {
             ControlMessage::ScmRights(_) => libc::SCM_RIGHTS,
             #[cfg(any(target_os = "android", target_os = "linux"))]
             ControlMessage::ScmCredentials(_) => libc::SCM_CREDENTIALS,
+            #[cfg(any(target_os = "freebsd", target_os = "dragonfly"))]
+            ControlMessage::ScmCredentials(_) => /* libc::SCM_CREDS */ 0x03, // https://github.com/rust-lang/libc/pull/1740
             #[cfg(any(target_os = "android", target_os = "linux"))]
             ControlMessage::AlgSetIv(_) => {
                 libc::ALG_SET_IV