From 73eed89ab3db30c756534ea16b8e68ad49327bb4 Mon Sep 17 00:00:00 2001
From: Erin <erin@erindesu.cz>
Date: Thu, 17 Aug 2023 03:45:57 +0200
Subject: [PATCH] Out of program execution parameter

---
 hbvm/fuzz/fuzz_targets/vm.rs       |  2 +-
 hbvm/src/main.rs                   |  2 +-
 hbvm/src/mem/softpaging/mapping.rs |  2 +-
 hbvm/src/mem/softpaging/mod.rs     | 16 +++++++++++-----
 4 files changed, 14 insertions(+), 8 deletions(-)

diff --git a/hbvm/fuzz/fuzz_targets/vm.rs b/hbvm/fuzz/fuzz_targets/vm.rs
index 03b3455c..2c368db9 100644
--- a/hbvm/fuzz/fuzz_targets/vm.rs
+++ b/hbvm/fuzz/fuzz_targets/vm.rs
@@ -16,7 +16,7 @@ fuzz_target!(|data: &[u8]| {
     if validate(data).is_ok() {
         let mut vm = unsafe {
             Vm::<_, 16384>::new(
-                SoftPagedMem {
+                SoftPagedMem::<_, true> {
                     pf_handler: TestTrapHandler,
                     program:    data,
                     root_pt:    Box::into_raw(Default::default()),
diff --git a/hbvm/src/main.rs b/hbvm/src/main.rs
index 80814c69..7bb45022 100644
--- a/hbvm/src/main.rs
+++ b/hbvm/src/main.rs
@@ -17,7 +17,7 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
     } else {
         unsafe {
             let mut vm = Vm::<_, 0>::new(
-                SoftPagedMem {
+                SoftPagedMem::<_, true> {
                     pf_handler: TestTrapHandler,
                     program:    &prog,
                     root_pt:    Box::into_raw(Default::default()),
diff --git a/hbvm/src/mem/softpaging/mapping.rs b/hbvm/src/mem/softpaging/mapping.rs
index 0d6858ee..8f406a4a 100644
--- a/hbvm/src/mem/softpaging/mapping.rs
+++ b/hbvm/src/mem/softpaging/mapping.rs
@@ -10,7 +10,7 @@ use {
     derive_more::Display,
 };
 
-impl<'p, A> SoftPagedMem<'p, A> {
+impl<'p, A,  const OUT_PROG_EXEC: bool> SoftPagedMem<'p, A, OUT_PROG_EXEC> {
     /// Maps host's memory into VM's memory
     ///
     /// # Safety
diff --git a/hbvm/src/mem/softpaging/mod.rs b/hbvm/src/mem/softpaging/mod.rs
index 1acf984b..11fa4658 100644
--- a/hbvm/src/mem/softpaging/mod.rs
+++ b/hbvm/src/mem/softpaging/mod.rs
@@ -18,8 +18,12 @@ use {
 };
 
 /// HoleyBytes software paged memory
+/// 
+/// - `OUT_PROG_EXEC`: set to `false` to disable executing program
+///   not contained in initially provided program, even the pages
+///   are executable
 #[derive(Clone, Debug)]
-pub struct SoftPagedMem<'p, PfH> {
+pub struct SoftPagedMem<'p, PfH, const OUT_PROG_EXEC: bool = true> {
     /// Root page table
     pub root_pt:    *mut PageTable,
     /// Page fault handler
@@ -30,7 +34,9 @@ pub struct SoftPagedMem<'p, PfH> {
     pub icache:     ICache,
 }
 
-impl<'p, PfH: HandlePageFault> Memory for SoftPagedMem<'p, PfH> {
+impl<'p, PfH: HandlePageFault, const OUT_PROG_EXEC: bool> Memory
+    for SoftPagedMem<'p, PfH, OUT_PROG_EXEC>
+{
     /// Load value from an address
     ///
     /// # Safety
@@ -70,7 +76,7 @@ impl<'p, PfH: HandlePageFault> Memory for SoftPagedMem<'p, PfH> {
 
     #[inline(always)]
     unsafe fn prog_read<T>(&mut self, addr: u64) -> Option<T> {
-        if addr as usize > self.program.len() {
+        if OUT_PROG_EXEC && addr as usize > self.program.len() {
             return self.icache.fetch::<T>(addr, self.root_pt);
         }
 
@@ -82,7 +88,7 @@ impl<'p, PfH: HandlePageFault> Memory for SoftPagedMem<'p, PfH> {
 
     #[inline(always)]
     unsafe fn prog_read_unchecked<T>(&mut self, addr: u64) -> T {
-        if addr as usize > self.program.len() {
+        if OUT_PROG_EXEC && addr as usize > self.program.len() {
             return self
                 .icache
                 .fetch::<T>(addr as _, self.root_pt)
@@ -93,7 +99,7 @@ impl<'p, PfH: HandlePageFault> Memory for SoftPagedMem<'p, PfH> {
     }
 }
 
-impl<'p, PfH: HandlePageFault> SoftPagedMem<'p, PfH> {
+impl<'p, PfH: HandlePageFault, const OUT_PROG_EXEC: bool> SoftPagedMem<'p, PfH, OUT_PROG_EXEC> {
     // Everyone behold, the holy function, the god of HBVM memory accesses!
 
     /// Split address to pages, check their permissions and feed pointers with offset