SERVER-75562 Enforce client metadata limit of 512 on non-internal clients

3 files changed, 36 insertions, 2 deletions

diff --git a/src/mongo/rpc/metadata/client_metadata.cpp b/src/mongo/rpc/metadata/client_metadata.cpp
index 8bd250551cc..24971fbdadc 100644
--- a/src/mongo/rpc/metadata/client_metadata.cpp
+++ b/src/mongo/rpc/metadata/client_metadata.cpp
@@ -488,7 +488,7 @@ void ClientMetadata::setFromMetadataForOperation(OperationContext* opCtx, BSONEl
     state.meta = std::move(inputMetadata);
 }
 
-void ClientMetadata::setFromMetadata(Client* client, BSONElement& elem) {
+void ClientMetadata::setFromMetadata(Client* client, BSONElement& elem, bool isInternalClient) {
     if (elem.eoo()) {
         return;
     }
@@ -502,6 +502,15 @@ void ClientMetadata::setFromMetadata(Client* client, BSONElement& elem) {
     }
 
     auto meta = ClientMetadata::readFromMetadata(elem);
+
+    if (!isInternalClient) {
+        uassert(ErrorCodes::ClientMetadataDocumentTooLarge,
+                str::stream() << "The client metadata document must be less than or equal to "
+                              << kMaxMongoSMetadataDocumentByteLength << " bytes",
+                static_cast<uint32_t>(meta->_document.objsize()) <=
+                    kMaxMongoSMetadataDocumentByteLength);
+    }
+
     if (meta && isMongos()) {
         // If we had a full ClientMetadata and we're on mongos, attach some additional client data.
         meta->setMongoSMetadata(getHostNameCachedAndPort(),
diff --git a/src/mongo/rpc/metadata/client_metadata.h b/src/mongo/rpc/metadata/client_metadata.h
index 309eb5668e0..713fab5f819 100644
--- a/src/mongo/rpc/metadata/client_metadata.h
+++ b/src/mongo/rpc/metadata/client_metadata.h
@@ -230,7 +230,7 @@ public:
      * This function is only valid to invoke if you are on the Client's thread. This function takes
      * the Client lock.
      */
-    static void setFromMetadata(Client* client, BSONElement& elem);
+    static void setFromMetadata(Client* client, BSONElement& elem, bool isInternalClient);
 
     /**
      * Set the ClientMetadata for the OperationContext by reading it from the given BSONElement.
diff --git a/src/mongo/rpc/metadata/client_metadata_test.cpp b/src/mongo/rpc/metadata/client_metadata_test.cpp
index d01507ba66a..b50a9a69185 100644
--- a/src/mongo/rpc/metadata/client_metadata_test.cpp
+++ b/src/mongo/rpc/metadata/client_metadata_test.cpp
@@ -387,4 +387,29 @@ TEST(ClientMetadataTest, TestEooElemAsValueToSetOpCtxMetadata) {
     ASSERT_FALSE(clientMetaDataPtr);
 }
 
+TEST(ClientMetadataTest, InternalClientLimit) {
+    auto svcCtx = ServiceContext::make();
+    svcCtx->registerClientObserver(std::make_unique<LockerNoopClientObserver>());
+    auto client = svcCtx->makeClient("ClientMetadataTest");
+
+    std::string tooLargeValue(600, 'x');
+
+    auto doc = BSON(kMetadataDoc << BSON(kDriver << BSON(kName << "n1" << kVersion << "v1")
+                                                 << kOperatingSystem << BSON(kType << kUnknown)
+                                                 << "extra" << tooLargeValue));
+    auto el = doc.firstElement();
+
+    // Succeeds because default limit is 1024 unless mongos (unit tests are not mongos)
+    ASSERT_OK(ClientMetadata::parse(el).getStatus());
+
+    // Throws since the document is too large
+    ASSERT_THROWS_CODE(ClientMetadata::setFromMetadata(client.get(), el, false),
+                       DBException,
+                       ErrorCodes::ClientMetadataDocumentTooLarge);
+
+
+    // Succeeds because internal client allows 1024
+    ASSERT_DOES_NOT_THROW(ClientMetadata::setFromMetadata(client.get(), el, true));
+}
+
 }  // namespace mongo