From 3887b98a7d89f2555ed0b25fc74ea2a643e28feb Mon Sep 17 00:00:00 2001
From: apio <blobs.trading@gmail.com>
Date: Sat, 8 Apr 2023 16:32:56 +0200
Subject: [PATCH] kernel: Support setuid binaries

You still have to run "chmod 4755 /bin/su" as root inside Luna for now, as this is not done by the install scripts.
---
 kernel/src/fs/VFS.cpp   | 10 ++++++++++
 kernel/src/fs/VFS.h     |  2 ++
 kernel/src/sys/exec.cpp |  3 +++
 3 files changed, 15 insertions(+)

diff --git a/kernel/src/fs/VFS.cpp b/kernel/src/fs/VFS.cpp
index 1d6f251d..11a75a19 100644
--- a/kernel/src/fs/VFS.cpp
+++ b/kernel/src/fs/VFS.cpp
@@ -86,4 +86,14 @@ namespace VFS
 
         return inode->mode() & S_IROTH;
     }
+
+    bool is_setuid(SharedPtr<Inode> inode)
+    {
+        return inode->mode() & S_ISUID;
+    }
+
+    bool is_setgid(SharedPtr<Inode> inode)
+    {
+        return inode->mode() & S_ISGID;
+    }
 }
diff --git a/kernel/src/fs/VFS.h b/kernel/src/fs/VFS.h
index c6b22a8d..34361c4d 100644
--- a/kernel/src/fs/VFS.h
+++ b/kernel/src/fs/VFS.h
@@ -178,6 +178,8 @@ namespace VFS
     bool can_execute(SharedPtr<Inode> inode, Credentials auth);
     bool can_read(SharedPtr<Inode> inode, Credentials auth);
     bool can_write(SharedPtr<Inode> inode, Credentials auth);
+    bool is_setuid(SharedPtr<Inode> inode);
+    bool is_setgid(SharedPtr<Inode> inode);
 
     Inode& root_inode();
 }
diff --git a/kernel/src/sys/exec.cpp b/kernel/src/sys/exec.cpp
index 725002e5..eb351e34 100644
--- a/kernel/src/sys/exec.cpp
+++ b/kernel/src/sys/exec.cpp
@@ -76,6 +76,9 @@ Result<u64> sys_execve(Registers* regs, SyscallArgs args)
 
     MMU::delete_userspace_page_directory(current->directory);
 
+    if (VFS::is_setuid(inode)) current->auth.euid = current->auth.suid = inode->uid();
+    if (VFS::is_setgid(inode)) current->auth.egid = current->auth.sgid = inode->gid();
+
     current->name = path.chars();
 
     image->apply(current);