From 1c4f1ab86725af0619f1dc248bc38901be71b114 Mon Sep 17 00:00:00 2001
From: apio <blobs.trading@gmail.com>
Date: Fri, 28 Oct 2022 17:19:26 +0200
Subject: [PATCH] Kernel, libc: Add setuid() and setgid() system calls

---
 kernel/include/sys/Syscall.h    |  6 ++++-
 kernel/src/sys/Syscall.cpp      |  2 ++
 kernel/src/sys/id.cpp           | 48 +++++++++++++++++++++++++++++++++
 libs/libc/include/sys/syscall.h |  2 ++
 libs/libc/src/syscall.cpp       |  2 ++
 5 files changed, 59 insertions(+), 1 deletion(-)

diff --git a/kernel/include/sys/Syscall.h b/kernel/include/sys/Syscall.h
index cc40242c..036eba79 100644
--- a/kernel/include/sys/Syscall.h
+++ b/kernel/include/sys/Syscall.h
@@ -28,6 +28,8 @@
 #define SYS_getdents 22
 #define SYS_stat 23
 #define SYS_dup2 24
+#define SYS_setuid 25
+#define SYS_setgid 26
 
 struct stat;
 struct pstat;
@@ -62,4 +64,6 @@ void sys_fstat(Context* context, int fd, struct stat* buf);
 void sys_pstat(Context* context, long pid, struct pstat* buf);
 void sys_getdents(Context* context, int fd, struct luna_dirent* buf, size_t count);
 void sys_stat(Context* context, const char* path, struct stat* buf);
-void sys_dup2(Context* context, int fd, int fd2);
\ No newline at end of file
+void sys_dup2(Context* context, int fd, int fd2);
+void sys_setuid(Context* context, int new_uid, int new_euid);
+void sys_setgid(Context* context, int new_gid, int new_egid);
\ No newline at end of file
diff --git a/kernel/src/sys/Syscall.cpp b/kernel/src/sys/Syscall.cpp
index eb6b6d12..0378acb9 100644
--- a/kernel/src/sys/Syscall.cpp
+++ b/kernel/src/sys/Syscall.cpp
@@ -38,6 +38,8 @@ void Syscall::entry(Context* context)
         sys_getdents(context, (int)context->rdi, (struct luna_dirent*)context->rsi, (size_t)context->rdx);
         break;
     case SYS_dup2: sys_dup2(context, (int)context->rdi, (int)context->rsi); break;
+    case SYS_setuid: sys_setuid(context, (int)context->rdi, (int)context->rsi); break;
+    case SYS_setgid: sys_setgid(context, (int)context->rdi, (int)context->rsi); break;
     default: context->rax = -ENOSYS; break;
     }
     VMM::exit_syscall_context();
diff --git a/kernel/src/sys/id.cpp b/kernel/src/sys/id.cpp
index 018a7027..3385428d 100644
--- a/kernel/src/sys/id.cpp
+++ b/kernel/src/sys/id.cpp
@@ -45,4 +45,52 @@ void sys_getprocid(Context* context, int field)
         context->rax = -EINVAL;
         return;
     }
+}
+
+void sys_setuid(Context* context, int new_uid, int new_euid)
+{
+    Task* current_task = Scheduler::current_task();
+
+    if (!current_task->is_superuser())
+    {
+        if (new_uid != current_task->uid && new_uid != current_task->euid)
+        {
+            context->rax = -EPERM;
+            return;
+        }
+        if (new_euid != current_task->euid && new_euid != current_task->uid)
+        {
+            context->rax = -EPERM;
+            return;
+        }
+    }
+
+    current_task->uid = new_uid;
+    current_task->euid = new_euid;
+
+    context->rax = 0;
+}
+
+void sys_setgid(Context* context, int new_gid, int new_egid)
+{
+    Task* current_task = Scheduler::current_task();
+
+    if (!current_task->is_superuser())
+    {
+        if (new_gid != current_task->gid && new_gid != current_task->egid)
+        {
+            context->rax = -EPERM;
+            return;
+        }
+        if (new_egid != current_task->egid && new_egid != current_task->gid)
+        {
+            context->rax = -EPERM;
+            return;
+        }
+    }
+
+    current_task->gid = new_gid;
+    current_task->egid = new_egid;
+
+    context->rax = 0;
 }
\ No newline at end of file
diff --git a/libs/libc/include/sys/syscall.h b/libs/libc/include/sys/syscall.h
index 5b02e983..1a70c1e6 100644
--- a/libs/libc/include/sys/syscall.h
+++ b/libs/libc/include/sys/syscall.h
@@ -26,5 +26,7 @@
 #define SYS_getdents 22
 #define SYS_stat 23
 #define SYS_dup2 24
+#define SYS_setuid 25
+#define SYS_setgid 26
 
 #endif
\ No newline at end of file
diff --git a/libs/libc/src/syscall.cpp b/libs/libc/src/syscall.cpp
index b5ae5667..c527bba2 100644
--- a/libs/libc/src/syscall.cpp
+++ b/libs/libc/src/syscall.cpp
@@ -26,6 +26,8 @@ extern "C" long syscall(long number, ...)
     case SYS_fstat:
     case SYS_stat:
     case SYS_dup2:
+    case SYS_setuid:
+    case SYS_setgid:
     case SYS_pstat: {
         arg arg0 = va_arg(ap, arg);
         arg arg1 = va_arg(ap, arg);