Add function for checking if file is owned by admin or system account

3 files changed, 51 insertions, 0 deletions

diff --git a/talpid-windows/Cargo.toml b/talpid-windows/Cargo.toml
index 0b9e1d2672..594e17f9ef 100644
--- a/talpid-windows/Cargo.toml
+++ b/talpid-windows/Cargo.toml
@@ -23,6 +23,7 @@ features = [
     "Win32_Foundation",
     "Win32_Globalization",
     "Win32_Security",
+    "Win32_Security_Authorization",
     "Win32_System_Diagnostics_ToolHelp",
     "Win32_System_IO",
     "Win32_Networking_WinSock",
diff --git a/talpid-windows/src/fs.rs b/talpid-windows/src/fs.rs
new file mode 100644
index 0000000000..eb78efa963
--- /dev/null
+++ b/talpid-windows/src/fs.rs
@@ -0,0 +1,47 @@
+use core::ffi::c_void;
+use std::io;
+use std::os::windows::io::AsRawHandle;
+use std::ptr;
+
+use windows_sys::Win32::{
+    Foundation::{LocalFree, ERROR_SUCCESS},
+    Security::{
+        Authorization::{GetSecurityInfo, SE_FILE_OBJECT},
+        IsWellKnownSid, WinBuiltinAdministratorsSid, WinLocalSystemSid, OWNER_SECURITY_INFORMATION,
+        SECURITY_DESCRIPTOR, SID,
+    },
+};
+
+/// Return whether a file handle is owned by either SYSTEM or the built-in administrators account
+pub fn is_admin_owned<T: AsRawHandle>(handle: T) -> io::Result<bool> {
+    let mut security_descriptor: *mut SECURITY_DESCRIPTOR = ptr::null_mut();
+    let mut owner: *mut SID = ptr::null_mut();
+
+    // SAFETY: `handle` is a valid handle
+    let result = unsafe {
+        GetSecurityInfo(
+            handle.as_raw_handle() as isize,
+            SE_FILE_OBJECT,
+            OWNER_SECURITY_INFORMATION,
+            (&mut owner) as *mut *mut SID as *mut *mut c_void,
+            ptr::null_mut(),
+            ptr::null_mut(),
+            ptr::null_mut(),
+            (&mut security_descriptor) as *mut *mut SECURITY_DESCRIPTOR as *mut *mut c_void,
+        )
+    };
+
+    if result != ERROR_SUCCESS {
+        return Err(io::Error::from_raw_os_error(result as i32));
+    }
+
+    // SAFETY: `owner` is valid since `security_descriptor` still is, and the well-known type is a valid argument
+    let is_system_owned = unsafe { IsWellKnownSid(owner as _, WinLocalSystemSid) != 0 };
+    // SAFETY: `owner` is valid since `security_descriptor` still is, and the well-known type is a valid argument
+    let is_admin_owned = unsafe { IsWellKnownSid(owner as _, WinBuiltinAdministratorsSid) != 0 };
+
+    // SAFETY: Since we no longer need the descriptor (or owner), it may be freed
+    unsafe { LocalFree(security_descriptor.cast()) };
+
+    Ok(is_system_owned || is_admin_owned)
+}
diff --git a/talpid-windows/src/lib.rs b/talpid-windows/src/lib.rs
index 53fa172ee0..92db769623 100644
--- a/talpid-windows/src/lib.rs
+++ b/talpid-windows/src/lib.rs
@@ -3,6 +3,9 @@
 #![deny(missing_docs)]
 #![cfg(windows)]
 
+/// File system
+pub mod fs;
+
 /// I/O
 pub mod io;