fix(sri): preserve supported hashes with malformed padding

Keep supported hash metadata through verification so misplaced or excess
base64 padding cannot disable integrity checks or select a weaker algorithm.
Accept matching noncanonical base64 without changing encoded metadata used
by CSP and preload consumption.

Cover script, preload, CSP, and Window/Worker fetch consumers. Validate with
cargo fmt, workspace Clippy, and all 19,886 nextest tests, plus browser
comparisons and SRI/preload WPT regressions.

moli-core/tests/fixtures/preload-consumption.js

@@ -28,7 +28,7 @@ async function () {
  const integrity = await (async () => {return (async () => {
  const rows=[];
  for (const cache of ['max-age=60','no-store']) for (const phase of ['pending','complete'])
- for (const [name,preloadIntegrity,consumerIntegrity,preloadEvent,consumerEvent,requests] of [["good-empty", "sha384-l+rtjjQWlmlLFL2PC8iIPwnXbiW45bZ6LU1ERjlAxYKUFswREZzY3pPyoT0RsvxJ", "", "load", "load", 1], ["bad-empty", "sha384-AAAA", "", "error", "error", 1], ["bad-same", "sha384-AAAA", "sha384-AAAA", "error", "error", 1], ["bad-good", "sha384-AAAA", "sha384-l+rtjjQWlmlLFL2PC8iIPwnXbiW45bZ6LU1ERjlAxYKUFswREZzY3pPyoT0RsvxJ", "error", "load", 2], ["good-bad", "sha384-l+rtjjQWlmlLFL2PC8iIPwnXbiW45bZ6LU1ERjlAxYKUFswREZzY3pPyoT0RsvxJ", "sha384-AAAA", "load", "error", 2], ["good-options", "sha384-l+rtjjQWlmlLFL2PC8iIPwnXbiW45bZ6LU1ERjlAxYKUFswREZzY3pPyoT0RsvxJ?ignored=option", "sha384-l+rtjjQWlmlLFL2PC8iIPwnXbiW45bZ6LU1ERjlAxYKUFswREZzY3pPyoT0RsvxJ", "load", "load", 1], ["good-different-algorithm", "sha384-l+rtjjQWlmlLFL2PC8iIPwnXbiW45bZ6LU1ERjlAxYKUFswREZzY3pPyoT0RsvxJ", "sha256-cRlncoZ/tNV1cbKTR2cXiKEwVFkjvOz4kToIRLKBiSE=", "load", "load", 2], ["empty-good", "", "sha384-l+rtjjQWlmlLFL2PC8iIPwnXbiW45bZ6LU1ERjlAxYKUFswREZzY3pPyoT0RsvxJ", "load", "load", 2]]) {
+ for (const [name,preloadIntegrity,consumerIntegrity,preloadEvent,consumerEvent,requests] of [["good-empty", "sha384-l+rtjjQWlmlLFL2PC8iIPwnXbiW45bZ6LU1ERjlAxYKUFswREZzY3pPyoT0RsvxJ", "", "load", "load", 1], ["bad-empty", "sha384-AAAA", "", "error", "error", 1], ["bad-same", "sha384-AAAA", "sha384-AAAA", "error", "error", 1], ["bad-good", "sha384-AAAA", "sha384-l+rtjjQWlmlLFL2PC8iIPwnXbiW45bZ6LU1ERjlAxYKUFswREZzY3pPyoT0RsvxJ", "error", "load", 2], ["good-bad", "sha384-l+rtjjQWlmlLFL2PC8iIPwnXbiW45bZ6LU1ERjlAxYKUFswREZzY3pPyoT0RsvxJ", "sha384-AAAA", "load", "error", 2], ["good-options", "sha384-l+rtjjQWlmlLFL2PC8iIPwnXbiW45bZ6LU1ERjlAxYKUFswREZzY3pPyoT0RsvxJ?ignored=option", "sha384-l+rtjjQWlmlLFL2PC8iIPwnXbiW45bZ6LU1ERjlAxYKUFswREZzY3pPyoT0RsvxJ", "load", "load", 1], ["good-different-algorithm", "sha384-l+rtjjQWlmlLFL2PC8iIPwnXbiW45bZ6LU1ERjlAxYKUFswREZzY3pPyoT0RsvxJ", "sha256-cRlncoZ/tNV1cbKTR2cXiKEwVFkjvOz4kToIRLKBiSE=", "load", "load", 2], ["empty-good", "", "sha384-l+rtjjQWlmlLFL2PC8iIPwnXbiW45bZ6LU1ERjlAxYKUFswREZzY3pPyoT0RsvxJ", "load", "load", 2], ["malformed-empty", "sha384-AAAA===", "", "error", "error", 1], ["good-malformed", "sha384-l+rtjjQWlmlLFL2PC8iIPwnXbiW45bZ6LU1ERjlAxYKUFswREZzY3pPyoT0RsvxJ", "sha384-A=AAA", "load", "error", 2]]) {
   const token='sri-'+rows.length,url=new URL('/probe-asset',location.href);
   url.searchParams.set('token',token);url.searchParams.set('as','script');url.searchParams.set('cache',cache);
   const link=document.createElement('link');Object.assign(link,{rel:'preload',as:'script',href:url.href,integrity:preloadIntegrity});

moli-core/tests/scripts/preload_consumption.rs

@@ -196,7 +196,7 @@ async fn document_preloads_supply_pending_and_completed_consumers_including_fail
             .context("preload consumption results")?,
     )?;
     assert_eq!(value["basic"]["rows"].as_array().unwrap().len(), 24);
-    assert_eq!(value["integrity"]["rows"].as_array().unwrap().len(), 32);
+    assert_eq!(value["integrity"]["rows"].as_array().unwrap().len(), 40);
     assert_eq!(value["basic"]["failures"], serde_json::json!([]));
     assert_eq!(value["integrity"]["failures"], serde_json::json!([]));
     assert_eq!(value["basic"]["executions"], 12);

moli-renderer-v8/src/script_vm/tests/fetch_integrity.rs

@@ -58,7 +58,7 @@ async fn fetch_integrity_validates_local_bytes_in_window_and_worker() {
 async fn fetch_integrity_validates_network_responses_in_window_and_worker() {
     for worker in [false, true] {
         let server =
-            StaticHttpServer::spawn_with_bodies(vec!["hello integrity".to_owned(); 8]).await;
+            StaticHttpServer::spawn_with_bodies(vec!["hello integrity".to_owned(); 16]).await;
         let expression = format!(
             r#"(async () => {{
               const checks = [];
@@ -74,6 +74,14 @@ async fn fetch_integrity_validates_network_responses_in_window_and_worker() {
                 ['whitespace', ' ', 'GET', true],
                 ['no-integrity', '', 'GET', true],
                 ['null-body', 'sha1-ignored', 'HEAD', false],
+                ['excess-padding-mismatch', 'sha384-AAAA===', 'GET', false],
+                ['interior-padding-mismatch', 'sha384-A=AAA', 'GET', false],
+                ['padding-only-mismatch', 'sha384-====', 'GET', false],
+                ['malformed-stronger-hash', valid + ' sha512-AAAA===', 'GET', false],
+                ['excess-padding-match', valid + '====', 'GET', true],
+                ['noncanonical-padding-bits', valid.replace('6A=', '6B='), 'GET', true],
+                ['non-base64-ignored', 'sha384-***', 'GET', true],
+                ['malformed-and-matching', 'sha256-A=AAA ' + valid, 'GET', true],
               ]) {{
                 try {{
                   const response = await fetch({} + label, {{integrity, method}});
@@ -85,7 +93,7 @@ async fn fetch_integrity_validates_network_responses_in_window_and_worker() {
             }})()"#,
             serde_json::to_string(server.base_url().as_str()).unwrap(),
         );
-        run_integrity_probe(server.base_url().as_str(), worker, &expression, 13).await;
-        assert_eq!(server.finish().await.len(), 8);
+        run_integrity_probe(server.base_url().as_str(), worker, &expression, 25).await;
+        assert_eq!(server.finish().await.len(), 16);
     }
 }

moli-renderer-v8/src/subresource_integrity.rs

@@ -175,6 +175,18 @@ mod tests {
                     );
                 }
             }
+            assert!(!integrity_metadata_allows_preload_consumption(
+                &valid,
+                Some(malformed)
+            ));
+            assert!(integrity_metadata_allows_preload_consumption(
+                malformed,
+                Some(malformed)
+            ));
+            assert!(!integrity_metadata_allows_preload_consumption(
+                "",
+                Some(malformed)
+            ));
         }
     }
 
@@ -183,6 +195,7 @@ mod tests {
         let body = b"noncanonical integrity";
         let digest = base64::engine::general_purpose::STANDARD
             .encode(DigestAlgorithm::Sha256.digest_bytes(body));
+        let metadata = format!("sha256-{digest}");
         for padding in ["", "=", "===", "======="] {
             let padded = format!("sha256-{}{padding}", digest.trim_end_matches('='));
             assert!(response_matches_subresource_integrity_metadata(
@@ -195,6 +208,10 @@ mod tests {
                 Some(&padded),
                 false
             ));
+            assert_eq!(
+                integrity_metadata_allows_preload_consumption(&metadata, Some(&padded)),
+                metadata == padded
+            );
         }
         // Only the top four bits of the final SHA-256 base64 symbol carry data.
         let mut noncanonical = digest.trim_end_matches('=').as_bytes().to_vec();
@@ -207,6 +224,10 @@ mod tests {
             Some(&noncanonical),
             true
         ));
+        assert!(!integrity_metadata_allows_preload_consumption(
+            &metadata,
+            Some(&noncanonical)
+        ));
     }
 
     #[test]