[pitboss/grind] deferred session-0014 (20260522T163126Z-7d60)

src/dynamic/framework/adapters/crypto_python.rs

@@ -0,0 +1,202 @@
+//! Python [`super::super::FrameworkAdapter`] matching weak-crypto
+//! sink constructions (`random.randint` / `random.random` for key
+//! material, `hashlib.md5` / `hashlib.sha1` used without
+//! `usedforsecurity=False`).
+//!
+//! Phase 11 (Track L.9).  Fires when the function body invokes one
+//! of the canonical Python weak-crypto entry points and the
+//! surrounding source imports the matching stdlib module.
+
+use crate::dynamic::framework::{FrameworkAdapter, FrameworkBinding};
+use crate::evidence::EntryKind;
+use crate::summary::FuncSummary;
+use crate::symbol::Lang;
+
+pub struct CryptoPythonAdapter;
+
+const ADAPTER_NAME: &str = "crypto-python";
+
+fn callee_is_weak_crypto(name: &str) -> bool {
+    let last = name.rsplit_once('.').map(|(_, s)| s).unwrap_or(name);
+    matches!(
+        last,
+        "randint" | "random" | "uniform" | "choice" | "seed" | "md5" | "sha1" | "new"
+    ) || matches!(
+        name,
+        "random.randint"
+            | "random.random"
+            | "random.uniform"
+            | "random.choice"
+            | "random.seed"
+            | "hashlib.md5"
+            | "hashlib.sha1"
+            | "Crypto.Hash.MD5.new"
+            | "Crypto.Hash.SHA1.new"
+    )
+}
+
+fn source_imports_python_crypto(file_bytes: &[u8]) -> bool {
+    const NEEDLES: &[&[u8]] = &[
+        b"import random",
+        b"from random ",
+        b"import hashlib",
+        b"from hashlib ",
+        b"from Crypto.Hash",
+        b"from Cryptodome.Hash",
+    ];
+    NEEDLES
+        .iter()
+        .any(|n| file_bytes.windows(n.len()).any(|w| w == *n))
+}
+
+/// Returns `true` when the surrounding source visibly routes the
+/// crypto call through a CSPRNG / hardened path (`secrets.*`,
+/// `os.urandom`, or hashlib called with `usedforsecurity=False`).
+fn source_routed_through_csprng(file_bytes: &[u8]) -> bool {
+    const NEEDLES: &[&[u8]] = &[
+        b"secrets.token_bytes",
+        b"secrets.token_hex",
+        b"secrets.token_urlsafe",
+        b"secrets.randbits",
+        b"secrets.choice",
+        b"secrets.SystemRandom",
+        b"os.urandom(",
+        b"usedforsecurity=False",
+    ];
+    NEEDLES
+        .iter()
+        .any(|n| file_bytes.windows(n.len()).any(|w| w == *n))
+}
+
+impl FrameworkAdapter for CryptoPythonAdapter {
+    fn name(&self) -> &'static str {
+        ADAPTER_NAME
+    }
+
+    fn lang(&self) -> Lang {
+        Lang::Python
+    }
+
+    fn detect(
+        &self,
+        summary: &FuncSummary,
+        _ast: tree_sitter::Node<'_>,
+        file_bytes: &[u8],
+    ) -> Option<FrameworkBinding> {
+        if source_routed_through_csprng(file_bytes) {
+            return None;
+        }
+        let matches_call = super::any_callee_matches(summary, callee_is_weak_crypto);
+        let matches_source = source_imports_python_crypto(file_bytes);
+        if matches_call && matches_source {
+            Some(FrameworkBinding {
+                adapter: ADAPTER_NAME.to_owned(),
+                kind: EntryKind::Function,
+                route: None,
+                request_params: Vec::new(),
+                response_writer: None,
+                middleware: Vec::new(),
+            })
+        } else {
+            None
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn parse_python(src: &[u8]) -> tree_sitter::Tree {
+        let mut parser = tree_sitter::Parser::new();
+        let lang = tree_sitter::Language::from(tree_sitter_python::LANGUAGE);
+        parser.set_language(&lang).unwrap();
+        parser.parse(src, None).unwrap()
+    }
+
+    #[test]
+    fn fires_on_random_randint() {
+        let src: &[u8] = b"import random\n\
+            def run(value):\n    return random.randint(0, 0xFFFF)\n";
+        let tree = parse_python(src);
+        let summary = FuncSummary {
+            name: "run".into(),
+            callees: vec![crate::summary::CalleeSite::bare("random.randint")],
+            ..Default::default()
+        };
+        assert!(
+            CryptoPythonAdapter
+                .detect(&summary, tree.root_node(), src)
+                .is_some()
+        );
+    }
+
+    #[test]
+    fn fires_on_hashlib_md5() {
+        let src: &[u8] = b"import hashlib\n\
+            def sign(value):\n    return hashlib.md5(value).hexdigest()\n";
+        let tree = parse_python(src);
+        let summary = FuncSummary {
+            name: "sign".into(),
+            callees: vec![crate::summary::CalleeSite::bare("hashlib.md5")],
+            ..Default::default()
+        };
+        assert!(
+            CryptoPythonAdapter
+                .detect(&summary, tree.root_node(), src)
+                .is_some()
+        );
+    }
+
+    #[test]
+    fn skips_when_source_routes_through_secrets() {
+        let src: &[u8] = b"import random\nimport secrets\n\
+            def run(value):\n    if 'STRONG' in value:\n        return secrets.token_bytes(32)\n    return random.randint(0, 0xFFFF)\n";
+        let tree = parse_python(src);
+        let summary = FuncSummary {
+            name: "run".into(),
+            callees: vec![
+                crate::summary::CalleeSite::bare("random.randint"),
+                crate::summary::CalleeSite::bare("secrets.token_bytes"),
+            ],
+            ..Default::default()
+        };
+        assert!(
+            CryptoPythonAdapter
+                .detect(&summary, tree.root_node(), src)
+                .is_none()
+        );
+    }
+
+    #[test]
+    fn skips_when_md5_used_for_non_security() {
+        let src: &[u8] = b"import hashlib\n\
+            def cache_key(value):\n    return hashlib.md5(value, usedforsecurity=False).hexdigest()\n";
+        let tree = parse_python(src);
+        let summary = FuncSummary {
+            name: "cache_key".into(),
+            callees: vec![crate::summary::CalleeSite::bare("hashlib.md5")],
+            ..Default::default()
+        };
+        assert!(
+            CryptoPythonAdapter
+                .detect(&summary, tree.root_node(), src)
+                .is_none()
+        );
+    }
+
+    #[test]
+    fn skips_plain_function() {
+        let src: &[u8] = b"def add(a, b):\n    return a + b\n";
+        let tree = parse_python(src);
+        let summary = FuncSummary {
+            name: "add".into(),
+            ..Default::default()
+        };
+        assert!(
+            CryptoPythonAdapter
+                .detect(&summary, tree.root_node(), src)
+                .is_none()
+        );
+    }
+}