Allow an option to set CA file and CA Path to AWS SDK
diff --git a/tensorflow/core/platform/s3/s3_file_system.cc b/tensorflow/core/platform/s3/s3_file_system.cc
index 9363390..ca6adfe 100644
--- a/tensorflow/core/platform/s3/s3_file_system.cc
+++ b/tensorflow/core/platform/s3/s3_file_system.cc
@@ -124,6 +124,14 @@
         cfg.requestTimeoutMs = timeout;
       }
     }
+    const char* ca_file = getenv("S3_CA_FILE");
+    if (ca_file) {
+      cfg.caFile = Aws::String(ca_file);
+    }
+    const char* ca_path = getenv("S3_CA_PATH");
+    if (ca_path) {
+      cfg.caPath = Aws::String(ca_path);
+    }
 
     init = true;
   }