From c33ceee9a30f19285f6d9bcc290a73a47052b52c Mon Sep 17 00:00:00 2001
From: "Victor M. Alvarez" <vmalvarez@virustotal.com>
Date: Fri, 20 Sep 2024 17:39:48 +0200
Subject: [PATCH] feat: serialize compiled rules in a platform-independent way.

---
 lib/src/compiler/mod.rs   |  3 ++-
 lib/src/compiler/rules.rs | 24 ++++++++++++++++++------
 2 files changed, 20 insertions(+), 7 deletions(-)

diff --git a/lib/src/compiler/mod.rs b/lib/src/compiler/mod.rs
index 613126d96..004a8514d 100644
--- a/lib/src/compiler/mod.rs
+++ b/lib/src/compiler/mod.rs
@@ -714,8 +714,9 @@ impl<'a> Compiler<'a> {
 
         let mut rules = Rules {
             serialized_globals,
+            wasm_mod,
+            compiled_wasm_mod: Some(compiled_wasm_mod),
             relaxed_re_syntax: self.relaxed_re_syntax,
-            wasm_mod: compiled_wasm_mod,
             ac: None,
             num_patterns: self.next_pattern_id.0 as usize,
             ident_pool: self.ident_pool,
diff --git a/lib/src/compiler/rules.rs b/lib/src/compiler/rules.rs
index b78b7ce93..41b61c4ee 100644
--- a/lib/src/compiler/rules.rs
+++ b/lib/src/compiler/rules.rs
@@ -48,12 +48,12 @@ pub struct Rules {
     /// string as `&BStr`.
     pub(in crate::compiler) lit_pool: BStringPool<LiteralId>,
 
+    /// WASM module as in raw form.
+    pub(in crate::compiler) wasm_mod: Vec<u8>,
+
     /// WASM module already compiled into native code for the current platform.
-    #[serde(
-        serialize_with = "serialize_wasm_mod",
-        deserialize_with = "deserialize_wasm_mod"
-    )]
-    pub(in crate::compiler) wasm_mod: wasmtime::Module,
+    #[serde(skip)]
+    pub(in crate::compiler) compiled_wasm_mod: Option<wasmtime::Module>,
 
     /// Vector with the names of all the imported modules. The vector contains
     /// the [`IdentId`] corresponding to the module's identifier.
@@ -163,6 +163,18 @@ impl Rules {
             .with_varint_encoding()
             .deserialize::<Self>(&bytes[magic.len()..])?;
 
+        // Compile the WASM module for the current platform. This panics
+        // if the WASM code is invalid, which should not happen as the code is
+        // emitted by YARA itself. If this ever happens is probably because
+        // wrong WASM code is being emitted.
+        rules.compiled_wasm_mod = Some(
+            wasmtime::Module::from_binary(
+                &crate::wasm::ENGINE,
+                rules.wasm_mod.as_slice(),
+            )
+            .expect("WASM module is not valid"),
+        );
+
         #[cfg(feature = "logging")]
         info!("Deserialization time: {:?}", Instant::elapsed(&start));
 
@@ -421,7 +433,7 @@ impl Rules {
 
     #[inline]
     pub(crate) fn wasm_mod(&self) -> &wasmtime::Module {
-        &self.wasm_mod
+        self.compiled_wasm_mod.as_ref().unwrap()
     }
 }