From 628b3badfbb676bc598e10cffe7beb5f85c59740 Mon Sep 17 00:00:00 2001
From: Andreas Kling <kling@serenityos.org>
Date: Fri, 31 Jul 2020 18:46:55 +0200
Subject: [PATCH] Kernel+AK: Add and use Userspace<T>::unsafe_userspace_ptr()

Since we already have the type information in the Userspace template,
it was a bit silly to cast manually everywhere. Just add a sufficiently
scary-sounding getter for a typed pointer.

Thanks @alimpfard for pointing out that I was being silly with tossing
out the type.

In the future we may want to make this API non-public as well.
---
 AK/Userspace.h           |  1 +
 Kernel/Process.h         | 14 +++++++-------
 Kernel/StdLib.h          |  8 ++++----
 Kernel/Syscalls/read.cpp |  2 +-
 4 files changed, 13 insertions(+), 12 deletions(-)

diff --git a/AK/Userspace.h b/AK/Userspace.h
index 7d61c41625..8f02f6d72f 100644
--- a/AK/Userspace.h
+++ b/AK/Userspace.h
@@ -45,6 +45,7 @@ public:
     }
 
     FlatPtr ptr() const { return m_ptr; }
+    T unsafe_userspace_ptr() const { return (T)m_ptr; }
 #else
     Userspace(T ptr)
         : m_ptr(ptr)
diff --git a/Kernel/Process.h b/Kernel/Process.h
index f5732aaaa1..25a88a9fd6 100644
--- a/Kernel/Process.h
+++ b/Kernel/Process.h
@@ -360,13 +360,13 @@ public:
     template<typename T>
     [[nodiscard]] bool validate_read(Userspace<T*> ptr, size_t size) const
     {
-        return validate_read((const T*)ptr.ptr(), size);
+        return validate_read(ptr.unsafe_userspace_ptr(), size);
     }
 
     template<typename T>
     [[nodiscard]] bool validate_write(Userspace<T*> ptr, size_t size) const
     {
-        return validate_write((T*)ptr.ptr(), size);
+        return validate_write(ptr.unsafe_userspace_ptr(), size);
     }
 
     template<typename T>
@@ -402,9 +402,9 @@ public:
     template<typename T>
     [[nodiscard]] bool validate_read_and_copy_typed(T* dest, Userspace<const T*> src)
     {
-        bool validated = validate_read_typed((const T*)src.ptr());
+        bool validated = validate_read_typed(src);
         if (validated) {
-            copy_from_user(dest, (const T*)src.ptr());
+            copy_from_user(dest, src);
         }
         return validated;
     }
@@ -426,7 +426,7 @@ public:
         size *= count;
         if (size.has_overflow())
             return false;
-        return validate_write((T*)value.ptr(), size.value());
+        return validate_write(value, size.value());
     }
 
     template<typename DataType, typename SizeType>
@@ -445,7 +445,7 @@ public:
 
     [[nodiscard]] String validate_and_copy_string_from_user(Userspace<const char*> user_characters, size_t size) const
     {
-        return validate_and_copy_string_from_user((const char*)user_characters.ptr(), size);
+        return validate_and_copy_string_from_user(user_characters.unsafe_userspace_ptr(), size);
     }
 
     [[nodiscard]] String validate_and_copy_string_from_user(const Syscall::StringArgument&) const;
@@ -597,7 +597,7 @@ private:
     KResultOr<String> get_syscall_path_argument(const char* user_path, size_t path_length) const;
     KResultOr<String> get_syscall_path_argument(Userspace<const char*> user_path, size_t path_length) const
     {
-        return get_syscall_path_argument((const char*)user_path.ptr(), path_length);
+        return get_syscall_path_argument(user_path.unsafe_userspace_ptr(), path_length);
     }
     KResultOr<String> get_syscall_path_argument(const Syscall::StringArgument&) const;
 
diff --git a/Kernel/StdLib.h b/Kernel/StdLib.h
index 983e6ab8a2..994c514123 100644
--- a/Kernel/StdLib.h
+++ b/Kernel/StdLib.h
@@ -75,23 +75,23 @@ inline void copy_to_user(T* dest, const T* src)
 template<typename T>
 inline void copy_from_user(T* dest, Userspace<const T*> src)
 {
-    copy_from_user(dest, (const T*)src.ptr(), sizeof(T));
+    copy_from_user(dest, src.unsafe_userspace_ptr(), sizeof(T));
 }
 
 template<typename T>
 inline void copy_to_user(Userspace<T*> dest, const T* src)
 {
-    copy_to_user((T*)dest.ptr(), src, sizeof(T));
+    copy_to_user(dest.unsafe_userspace_ptr(), src, sizeof(T));
 }
 
 template<typename T>
 inline void copy_to_user(Userspace<T*> dest, const void* src, size_t size)
 {
-    copy_to_user((void*)dest.ptr(), src, size);
+    copy_to_user(dest.unsafe_userspace_ptr(), src, size);
 }
 
 template<typename T>
 inline void copy_from_user(void* dest, Userspace<const T*> src, size_t size)
 {
-    copy_from_user(dest, (const void*)src.ptr(), size);
+    copy_from_user(dest, src.unsafe_userspace_ptr(), size);
 }
diff --git a/Kernel/Syscalls/read.cpp b/Kernel/Syscalls/read.cpp
index f76bbe5106..9832b09b76 100644
--- a/Kernel/Syscalls/read.cpp
+++ b/Kernel/Syscalls/read.cpp
@@ -57,7 +57,7 @@ ssize_t Process::sys$read(int fd, Userspace<u8*> buffer, ssize_t size)
         }
     }
     // FIXME: We should have a read() that takes a Userspace<u8*>
-    return description->read((u8*)buffer.ptr(), size);
+    return description->read(buffer.unsafe_userspace_ptr(), size);
 }
 
 }