Add permissions to the filesystem, preliminary permissions to the syscalls

kernel/syscall/mod.rs

@@ -48,6 +48,10 @@ pub extern fn syscall(a: usize, b: usize, c: usize, d: usize, e: usize, f: usize
             SYS_CLONE => clone(b, stack),
             SYS_YIELD => sched_yield(),
             SYS_GETCWD => getcwd(validate_slice_mut(b as *mut u8, c)?),
+            SYS_GETUID => getuid(),
+            SYS_GETGID => getgid(),
+            SYS_SETUID => setuid(b as u32),
+            SYS_SETGID => setgid(b as u32),
             SYS_FEVENT => fevent(b, c),
             SYS_FPATH => fpath(b, validate_slice_mut(c as *mut u8, d)?),
             SYS_PHYSALLOC => physalloc(b),

kernel/syscall/process.rs

@@ -58,6 +58,8 @@ pub fn clone(flags: usize, stack_base: usize) -> Result<usize> {
     let ppid;
     let pid;
     {
+        let uid;
+        let gid;
         let arch;
         let vfork;
         let mut kfx_option = None;
@@ -78,6 +80,8 @@ pub fn clone(flags: usize, stack_base: usize) -> Result<usize> {
             let context = context_lock.read();
 
             ppid = context.id;
+            uid = context.uid;
+            gid = context.gid;
 
             arch = context.arch.clone();
 
@@ -249,6 +253,8 @@ pub fn clone(flags: usize, stack_base: usize) -> Result<usize> {
             pid = context.id;
 
             context.ppid = ppid;
+            context.uid = uid;
+            context.gid = gid;
 
             context.status = context::Status::Runnable;
 
@@ -452,6 +458,7 @@ pub fn exec(path: &[u8], arg_ptrs: &[[usize; 2]]) -> Result<usize> {
                     drop(context.stack.take());
                     context.grants = Arc::new(Mutex::new(Vec::new()));
 
+                    // Map and copy new segments
                     for segment in elf.segments() {
                         if segment.p_type == program_header::PT_LOAD {
                             let mut memory = context::memory::Memory::new(
@@ -488,6 +495,7 @@ pub fn exec(path: &[u8], arg_ptrs: &[[usize; 2]]) -> Result<usize> {
                         }
                     }
 
+                    // Map heap
                     context.heap = Some(context::memory::Memory::new(
                         VirtualAddress::new(arch::USER_HEAP_OFFSET),
                         0,
@@ -572,6 +580,13 @@ pub fn exec(path: &[u8], arg_ptrs: &[[usize; 2]]) -> Result<usize> {
     unsafe { usermode(entry, sp); }
 }
 
+pub fn getgid() -> Result<usize> {
+    let contexts = context::contexts();
+    let context_lock = contexts.current().ok_or(Error::new(ESRCH))?;
+    let context = context_lock.read();
+    Ok(context.gid as usize)
+}
+
 pub fn getpid() -> Result<usize> {
     let contexts = context::contexts();
     let context_lock = contexts.current().ok_or(Error::new(ESRCH))?;
@@ -579,6 +594,13 @@ pub fn getpid() -> Result<usize> {
     Ok(context.id)
 }
 
+pub fn getuid() -> Result<usize> {
+    let contexts = context::contexts();
+    let context_lock = contexts.current().ok_or(Error::new(ESRCH))?;
+    let context = context_lock.read();
+    Ok(context.uid as usize)
+}
+
 pub fn iopl(_level: usize) -> Result<usize> {
     //TODO
     Ok(0)
@@ -676,6 +698,34 @@ pub fn sched_yield() -> Result<usize> {
     Ok(0)
 }
 
+pub fn setgid(gid: 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.gid == 0 {
+        context.gid = gid;
+        Ok(0)
+    } else if context.gid == gid {
+        Ok(0)
+    } else {
+        Err(Error::new(EPERM))
+    }
+}
+
+pub fn setuid(uid: 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.uid == 0 {
+        context.uid = uid;
+        Ok(0)
+    } else if context.uid == uid {
+        Ok(0)
+    } else {
+        Err(Error::new(EPERM))
+    }
+}
+
 pub fn virttophys(virtual_address: usize) -> Result<usize> {
     let active_table = unsafe { ActivePageTable::new() };
     match active_table.translate(VirtualAddress::new(virtual_address)) {