fix(kms): harden key list contract

crates/kms/src/backends/local.rs

@@ -3101,6 +3101,26 @@ mod tests {
         );
     }
 
+    #[tokio::test]
+    async fn list_keys_fails_closed_on_a_corrupt_record() {
+        let (client, _temp_dir) = create_test_client().await;
+        client.create_key("corrupt", "AES_256", None).await.expect("create key");
+
+        let key_path = client.master_key_path("corrupt").expect("valid key id");
+        fs::write(&key_path, b"{\"key_id\":\"corrupt\"")
+            .await
+            .expect("write corrupt record");
+
+        let error = client
+            .list_keys(&ListKeysRequest::default(), None)
+            .await
+            .expect_err("a corrupt record must not disappear from a listing");
+        assert!(
+            matches!(error, KmsError::MaterialCorrupt { key_id, .. } if key_id == "corrupt"),
+            "got {error:?}"
+        );
+    }
+
     #[tokio::test]
     async fn missing_salt_with_pre_marker_key_records_still_initializes() {
         let (dev_client, temp_dir) = create_dev_mode_client().await;

crates/kms/src/backends/mod.rs

@@ -160,7 +160,7 @@ pub(crate) fn ensure_rewrap_context_matches(
 }
 
 /// Page size used when a [`ListKeysRequest`] does not ask for one.
-pub(crate) const DEFAULT_LIST_KEYS_PAGE_SIZE: u32 = 100;
+pub(crate) const DEFAULT_LIST_KEYS_PAGE_SIZE: u32 = DEFAULT_LIST_KEYS_LIMIT;
 
 /// One page of a key set the backend has to slice itself.
 pub(crate) struct KeyPage<'a, T> {
@@ -231,7 +231,7 @@ pub(crate) fn paginate_keys<'a, T>(sorted: &'a [T], request: &ListKeysRequest, k
 pub(crate) fn list_keys_page_size(limit: Option<u32>) -> Option<usize> {
     match limit.unwrap_or(DEFAULT_LIST_KEYS_PAGE_SIZE) {
         0 => None,
-        size => Some(size as usize),
+        size => Some(size.min(MAX_LIST_KEYS_LIMIT) as usize),
     }
 }
 
@@ -860,6 +860,21 @@ mod tests {
         assert_eq!(page_of(&keys, Some(u32::MAX), Some("key-01")), (vec![keys[2].clone()], None, false));
     }
 
+    #[test]
+    fn list_limit_is_bounded_at_the_contract_maximum() {
+        assert_eq!(list_keys_page_size(Some(MAX_LIST_KEYS_LIMIT)), Some(MAX_LIST_KEYS_LIMIT as usize));
+        assert_eq!(
+            list_keys_page_size(Some(MAX_LIST_KEYS_LIMIT + 1)),
+            Some(MAX_LIST_KEYS_LIMIT as usize),
+            "one past the maximum must not expand a backend page"
+        );
+        assert_eq!(
+            list_keys_page_size(Some(u32::MAX)),
+            Some(MAX_LIST_KEYS_LIMIT as usize),
+            "the largest wire value must use the same bounded page"
+        );
+    }
+
     /// The cursor is an identifier, so a marker naming a key that no longer
     /// exists resumes after where it would have been instead of restarting.
     #[test]

crates/kms/src/backends/static_kms.rs

@@ -59,6 +59,12 @@ pub struct StaticKmsBackend {
     key_id: String,
     /// The raw 32-byte AES-256 key material (zeroed on drop).
     key: Zeroizing<[u8; KEY_SIZE]>,
+    /// The time this configured key became visible to the backend.
+    ///
+    /// Static KMS has no persisted key record, so this startup timestamp is
+    /// the only stable creation date it can report across list and describe
+    /// calls. It must not be regenerated for every response.
+    created_at: Zoned,
 }
 
 impl StaticKmsBackend {
@@ -82,6 +88,7 @@ impl StaticKmsBackend {
         Ok(Self {
             key_id: static_config.key_id.clone(),
             key: key.into(),
+            created_at: Zoned::now(),
         })
     }
 
@@ -92,7 +99,7 @@ impl StaticKmsBackend {
             key_state: KeyState::Enabled,
             key_usage: KeyUsage::EncryptDecrypt,
             description: Some("Static single-key KMS backend".to_string()),
-            creation_date: Zoned::now(),
+            creation_date: self.created_at.clone(),
             deletion_date: None,
             origin: "EXTERNAL".to_string(),
             key_manager: "STATIC".to_string(),
@@ -281,7 +288,7 @@ impl StaticKmsBackend {
             version: 1,
             metadata: HashMap::new(),
             tags: HashMap::new(),
-            created_at: Zoned::now(),
+            created_at: self.created_at.clone(),
             rotated_at: None,
             created_by: None,
         };
@@ -677,6 +684,23 @@ mod tests {
         assert!(!response.truncated);
     }
 
+    #[tokio::test]
+    async fn list_key_creation_date_is_stable_for_the_backend_lifetime() {
+        let (backend, key_id, _key) = create_test_backend().await;
+
+        let first = backend
+            .list_configured_key(&ListKeysRequest::default())
+            .expect("first list should succeed");
+        tokio::task::yield_now().await;
+        let second = backend
+            .list_configured_key(&ListKeysRequest::default())
+            .expect("second list should succeed");
+        let described = backend.configured_key_info(&key_id).expect("describe should succeed");
+
+        assert_eq!(first.keys[0].created_at, second.keys[0].created_at);
+        assert_eq!(first.keys[0].created_at, described.created_at);
+    }
+
     /// A zero limit means zero keys, even for a backend whose whole key set is
     /// a single configured key.
     #[tokio::test]

crates/kms/src/backends/vault.rs

@@ -1213,8 +1213,13 @@ impl VaultKmsClient {
             // A key that disappeared between the listing and the read is
             // dropped from the page rather than failing it; the cursor comes
             // from the identifier list, so the listing still advances past it.
-            let Ok(key_info) = self.describe_key(key_id, None).await else {
-                continue;
+            // Any other read error means the record is present but this build
+            // cannot interpret it. Hiding that entry would make the listing
+            // claim a complete key set while silently omitting corrupt data.
+            let key_info = match self.describe_key(key_id, None).await {
+                Ok(key_info) => key_info,
+                Err(KmsError::KeyNotFound { .. }) => continue,
+                Err(error) => return Err(error),
             };
             if request
                 .status_filter
@@ -1955,6 +1960,32 @@ mod tests {
         );
     }
 
+    #[tokio::test]
+    async fn list_keys_fails_closed_on_an_unreadable_kv2_record() {
+        let malformed_record = serde_json::json!({
+            "data": {"algorithm": "AES_256"},
+            "metadata": {
+                "created_time": "2026-01-01T00:00:00Z",
+                "deletion_time": "",
+                "custom_metadata": null,
+                "destroyed": false,
+                "version": 1
+            }
+        });
+        let (vault, client) = scripted_client(vec![
+            ScriptedResponse::ok(serde_json::json!({ "keys": ["poisoned"] })),
+            ScriptedResponse::ok(malformed_record),
+        ])
+        .await;
+
+        let error = client
+            .list_keys(&ListKeysRequest::default(), None)
+            .await
+            .expect_err("a malformed KV2 record must not disappear from a listing");
+        assert!(matches!(error, KmsError::BackendError { .. }), "got {error:?}");
+        assert_eq!(vault.requests().len(), 2, "listing must read the listed record before failing");
+    }
+
     #[tokio::test]
     async fn wired_read_retries_transient_status_then_succeeds() {
         let (vault, client) = scripted_client(vec![

crates/kms/src/types.rs

@@ -415,7 +415,15 @@ impl DecryptRequest {
     }
 }
 
-/// Request to list keys
+/// Default page size used when a request omits `limit`.
+pub const DEFAULT_LIST_KEYS_LIMIT: u32 = 100;
+/// Maximum page size accepted by KMS list implementations.
+pub const MAX_LIST_KEYS_LIMIT: u32 = 1000;
+
+/// Request to list keys.
+///
+/// List pages default to [`DEFAULT_LIST_KEYS_LIMIT`] entries and are capped at
+/// [`MAX_LIST_KEYS_LIMIT`]. A zero limit is a valid request for an empty page.
 #[derive(Debug, Clone, Serialize, Deserialize)]
 pub struct ListKeysRequest {
     /// Maximum number of keys to return
@@ -431,7 +439,7 @@ pub struct ListKeysRequest {
 impl Default for ListKeysRequest {
     fn default() -> Self {
         Self {
-            limit: Some(100),
+            limit: Some(DEFAULT_LIST_KEYS_LIMIT),
             marker: None,
             usage_filter: None,
             status_filter: None,

rustfs/src/admin/handlers/kms_keys.rs

@@ -180,6 +180,21 @@ fn key_list_filters(query_params: &HashMap<String, String>) -> Result<KeyListFil
     })
 }
 
+/// Parse the optional page size without turning malformed input into a
+/// different request. Values above the backend contract maximum are bounded
+/// so a client cannot make one list request describe an unbounded number of
+/// keys.
+fn key_list_limit(query_params: &HashMap<String, String>) -> Result<u32, String> {
+    let Some(value) = query_params.get("limit") else {
+        return Ok(DEFAULT_LIST_KEYS_LIMIT);
+    };
+
+    value
+        .parse::<u32>()
+        .map(|limit| limit.min(MAX_LIST_KEYS_LIMIT))
+        .map_err(|_| format!("invalid value for 'limit': expected an unsigned integer, got '{value}'"))
+}
+
 fn extract_key_id(uri: &hyper::Uri) -> Option<String> {
     let query_params = extract_query_params(uri);
     ["keyId", "key-id", "key"]
@@ -443,12 +458,16 @@ mod tests {
     use super::{
         CancelKmsKeyDeletionRequest, CreateKeyApiRequest, CreateKmsKeyRequest, DeleteKmsKeyRequest, DeleteKmsKeyResponse,
         DescribeKmsKeyResponse, GenerateDataKeyApiRequest, delete_key_error_status, delete_request_from_query, extract_key_id,
-        extract_query_params, key_impact_if_requested, key_list_filters, kms_create_key_actions, kms_delete_key_actions,
-        kms_describe_key_actions, kms_generate_data_key_actions, kms_list_keys_actions, scoped_key_id, wants_key_impact,
+        extract_query_params, key_impact_if_requested, key_list_filters, key_list_limit, kms_create_key_actions,
+        kms_delete_key_actions, kms_describe_key_actions, kms_generate_data_key_actions, kms_list_keys_actions, scoped_key_id,
+        wants_key_impact,
     };
     use http::Uri;
     use hyper::StatusCode;
-    use rustfs_kms::{KeyImpactReport, KeyReference, KeyReferenceKind, KeyStatus, KeyUsage, KmsError, ReferenceScope};
+    use rustfs_kms::{
+        DEFAULT_LIST_KEYS_LIMIT, KeyImpactReport, KeyReference, KeyReferenceKind, KeyStatus, KeyUsage, KmsError,
+        MAX_LIST_KEYS_LIMIT, ReferenceScope,
+    };
     use rustfs_policy::policy::action::{Action, AdminAction, KmsAction};
     use rustfs_policy::policy::{Args, Policy};
     use std::collections::HashMap;
@@ -996,6 +1015,42 @@ mod tests {
         key_list_filters(&extract_query_params(&uri)).map(|filters| (filters.status, filters.usage))
     }
 
+    fn list_limit(query: &str) -> Result<u32, String> {
+        let uri: Uri = format!("/rustfs/admin/v3/kms/keys{query}").parse().expect("uri should parse");
+        key_list_limit(&extract_query_params(&uri))
+    }
+
+    #[test]
+    fn a_key_listing_limit_is_bounded_and_malformed_values_are_refused() {
+        assert_eq!(list_limit(""), Ok(DEFAULT_LIST_KEYS_LIMIT));
+        assert_eq!(list_limit("?limit=0"), Ok(0));
+        assert_eq!(list_limit(&format!("?limit={MAX_LIST_KEYS_LIMIT}")), Ok(MAX_LIST_KEYS_LIMIT));
+        assert_eq!(
+            list_limit(&format!("?limit={}", MAX_LIST_KEYS_LIMIT + 1)),
+            Ok(MAX_LIST_KEYS_LIMIT),
+            "one past the maximum must be clamped"
+        );
+        assert_eq!(list_limit("?limit=4294967295"), Ok(MAX_LIST_KEYS_LIMIT));
+
+        for query in ["?limit=abc", "?limit=-1", "?limit="] {
+            let error = list_limit(query).expect_err("malformed limits must not fall back to the default");
+            assert!(error.contains("invalid value for 'limit'"), "unhelpful error for {query}: {error}");
+        }
+    }
+
+    #[test]
+    fn both_list_handlers_validate_the_requested_limit() {
+        let src = include_str!("kms_keys.rs");
+
+        for handler in ["ListKeysHandler", "ListKmsKeysHandler"] {
+            let block = operation_block(src, handler);
+            assert!(
+                block.contains("key_list_limit(&query_params)"),
+                "{handler} must reject malformed limits before reaching the KMS"
+            );
+        }
+    }
+
     /// A filter is either applied or refused. Answering a narrowed listing with
     /// the unfiltered key set looks, from the response alone, exactly like a key
     /// set in which everything matches — the caller cannot tell that its
@@ -1138,7 +1193,7 @@ impl Operation for ListKeysHandler {
         )?;
 
         let query_params = extract_query_params(&req.uri);
-        let limit = query_params.get("limit").and_then(|s| s.parse::<u32>().ok()).unwrap_or(100);
+        let limit = key_list_limit(&query_params).map_err(|message| s3_error!(InvalidArgument, "{}", message))?;
         let marker = query_params.get("marker").cloned();
         // Validated before the listing runs, so a filter the service cannot
         // apply fails as the input error it is instead of returning the whole
@@ -1878,7 +1933,23 @@ impl Operation for ListKmsKeysHandler {
         )?;
 
         let query_params = extract_query_params(&req.uri);
-        let limit = query_params.get("limit").and_then(|s| s.parse::<u32>().ok()).unwrap_or(100);
+        let limit = match key_list_limit(&query_params) {
+            Ok(limit) => limit,
+            Err(message) => {
+                let response = ListKmsKeysResponse {
+                    success: false,
+                    message,
+                    keys: vec![],
+                    truncated: false,
+                    next_marker: None,
+                };
+                let data =
+                    serde_json::to_vec(&response).map_err(|e| s3_error!(InternalError, "failed to serialize response: {}", e))?;
+                let mut headers = HeaderMap::new();
+                headers.insert(CONTENT_TYPE, "application/json".parse().expect("operation should succeed"));
+                return Ok(S3Response::with_headers((StatusCode::BAD_REQUEST, Body::from(data)), headers));
+            }
+        };
         let marker = query_params.get("marker").cloned();
         // Validated before the listing runs, so a filter the service cannot
         // apply fails as the input error it is instead of returning the whole