Replace setuid, setgid with setreuid, setregid

kernel/syscall/mod.rs

@@ -86,8 +86,8 @@ pub extern fn syscall(a: usize, b: usize, c: usize, d: usize, e: usize, f: usize
                 SYS_GETGID => getgid(),
                 SYS_GETEUID => geteuid(),
                 SYS_GETEGID => getegid(),
-                SYS_SETUID => setuid(b as u32),
-                SYS_SETGID => setgid(b as u32),
+                SYS_SETREUID => setreuid(b as u32, c as u32),
+                SYS_SETREGID => setregid(b as u32, c as u32),
                 SYS_SETNS => setns(validate_slice(b as *const [usize; 2], c)?),
                 SYS_PIPE2 => pipe2(validate_slice_mut(b as *mut usize, 2)?, c),
                 SYS_PHYSALLOC => physalloc(b),

kernel/syscall/privilege.rs

@@ -33,26 +33,52 @@ pub fn getuid() -> Result<usize> {
     Ok(context.ruid as usize)
 }
 
-pub fn setgid(gid: u32) -> Result<usize> {
+pub fn setregid(rgid: u32, egid: u32) -> Result<usize> {
     let contexts = context::contexts();
     let context_lock = contexts.current().ok_or(Error::new(ESRCH))?;
     let mut context = context_lock.write();
-    if context.egid == 0 {
-        context.rgid = gid;
-        context.egid = gid;
+
+    if (context.euid == 0
+    || rgid as i32 == -1
+    || rgid == context.egid
+    || rgid == context.rgid)
+    && (context.euid == 0
+    || egid as i32 == -1
+    || egid == context.egid
+    || egid == context.rgid)
+    {
+        if rgid as i32 != -1 {
+            context.rgid = rgid;
+        }
+        if egid as i32 != -1 {
+            context.egid = egid;
+        }
         Ok(0)
     } else {
         Err(Error::new(EPERM))
     }
 }
 
-pub fn setuid(uid: u32) -> Result<usize> {
+pub fn setreuid(ruid: u32, euid: u32) -> Result<usize> {
     let contexts = context::contexts();
     let context_lock = contexts.current().ok_or(Error::new(ESRCH))?;
     let mut context = context_lock.write();
-    if context.euid == 0 {
-        context.ruid = uid;
-        context.euid = uid;
+
+    if (context.euid == 0
+    || ruid as i32 == -1
+    || ruid == context.euid
+    || ruid == context.ruid)
+    && (context.euid == 0
+    || euid as i32 == -1
+    || euid == context.euid
+    || euid == context.ruid)
+    {
+        if ruid as i32 != -1 {
+            context.ruid = ruid;
+        }
+        if euid as i32 != -1 {
+            context.euid = euid;
+        }
         Ok(0)
     } else {
         Err(Error::new(EPERM))