Backporting of fix for listing key aliases.android-13.0.0_r82android-13.0.0_r81android-13.0.0_r80android-13.0.0_r74android-13.0.0_r73android-13.0.0_r72android-13.0.0_r66android-13.0.0_r65android-13.0.0_r64android-13.0.0_r60android-13.0.0_r59android-13.0.0_r58android13-qpr3-c-s8-releaseandroid13-qpr3-c-s7-releaseandroid13-qpr3-c-s6-releaseandroid13-qpr3-c-s5-releaseandroid13-qpr3-c-s4-releaseandroid13-qpr3-c-s3-releaseandroid13-qpr3-c-s2-releaseandroid13-qpr3-c-s12-releaseandroid13-qpr3-c-s11-releaseandroid13-qpr3-c-s10-releaseandroid13-qpr3-c-s1-release

Limit the number of key descriptors sent back.
Backporting - Ported https://r.android.com/2381494

Merged-In: I5e8543a25dd9f1bb504fbc23f35779da0a0153b0
Bug: 267270741
Test: Manual: Generate 2500 keys with a 200 characters name each.
Change-Id: I6d370651441b4186b28cfed243975e64e3e8c85f

1 files changed, 34 insertions, 1 deletions

diff --git a/keystore2/src/utils.rs b/keystore2/src/utils.rs
index 9db2eb9d..08d3a8ef 100644
--- a/keystore2/src/utils.rs
+++ b/keystore2/src/utils.rs
@@ -279,7 +279,40 @@ pub fn list_key_entries(
     );
     result.sort_unstable();
     result.dedup();
-    Ok(result)
+
+    let mut items_to_return = 0;
+    let mut returned_bytes: usize = 0;
+    const RESPONSE_SIZE_LIMIT: usize = 358400;
+    // Estimate the transaction size to avoid returning more items than what
+    // could fit in a binder transaction.
+    for kd in result.iter() {
+        // 4 bytes for the Domain enum
+        // 8 bytes for the Namespace long.
+        returned_bytes += 4 + 8;
+        // Size of the alias string. Includes 4 bytes for length encoding.
+        if let Some(alias) = &kd.alias {
+            returned_bytes += 4 + alias.len();
+        }
+        // Size of the blob. Includes 4 bytes for length encoding.
+        if let Some(blob) = &kd.blob {
+            returned_bytes += 4 + blob.len();
+        }
+        // The binder transaction size limit is 1M. Empirical measurements show
+        // that the binder overhead is 60% (to be confirmed). So break after
+        // 350KB and return a partial list.
+        if returned_bytes > RESPONSE_SIZE_LIMIT {
+            log::warn!(
+                "Key descriptors list ({} items) may exceed binder \
+                       size, returning {} items est {} bytes.",
+                result.len(),
+                items_to_return,
+                returned_bytes
+            );
+            break;
+        }
+        items_to_return += 1;
+    }
+    Ok(result[..items_to_return].to_vec())
 }
 
 /// This module provides helpers for simplified use of the watchdog module.