Probe for SELinux execheap permission during bootup

EverestAPI · Dec 14, 2023 · 0cb187f · 0cb187f
1 parent 1772c18
commit 0cb187f
Showing 1 changed file with 23 additions and 0 deletions.
diff --git a/Celeste.Mod.mm/Mod/Everest/BOOT.cs b/Celeste.Mod.mm/Mod/Everest/BOOT.cs
@@ -6,6 +6,7 @@
 using System;
 using System.Collections;
 using System.Collections.Generic;
+using System.ComponentModel;
 using System.Diagnostics;
 using System.Globalization;
 using System.IO;
@@ -48,6 +49,28 @@ private static void Main(string[] args) {
                 } catch {
                 }
 
+                // SELinux can cause weird game corruption-like symptoms when we lack the execheap permission
+                // So probe for it before continuing to boot on Linux
+                if (RuntimeInformation.IsOSPlatform(OSPlatform.Linux)) {
+                    [DllImport("libc", SetLastError = true)]
+                    static extern int mprotect(IntPtr ptr, nuint len, int prot);
+                    const int PROT_READ = 1, PROT_WRITE = 2, PROT_EXEC = 4;
+
+                    //Allocate a bit of memory on the heap
+                    IntPtr heapAlloc = Marshal.AllocHGlobal(123);
+                    IntPtr heapPage = heapAlloc & ~0xfff;
+
+                    //Try to make it executable
+                    if (mprotect(heapPage, 0x1000, PROT_READ | PROT_WRITE | PROT_EXEC) < 0)
+                        throw new Win32Exception(Marshal.GetLastPInvokeError(), "SELinux execheap probe failed! Please ensure Everest has this permission, then try again");
+
+                    //Cleanup
+                    if (mprotect(heapPage, 0x1000, PROT_READ | PROT_WRITE) < 0)
+                        throw new Win32Exception(Marshal.GetLastPInvokeError(), "Failed to revert memory permissions after SELinux execheap probe");
+
+                    Marshal.FreeHGlobal(heapAlloc);
+                }
+
                 // Load the compatibility mode setting
                 Everest.CompatibilityMode = Everest.CompatMode.None;
                 bool useExclusiveFullscreen = false;