Use open(2) uid for transforms

With node transforms, we delay calling the transform until read(2), if
the opened fd is first read from a different process, we might use the
wrong uid while computing the transform.

To fix, we add the uid of process opening in the handle, and use it at
read

Test: Manual
Bug: 170487388
Change-Id: I98d5e093bffc78c26c8fa1040bbe4504b7f92760

1 files changed, 3 insertions, 1 deletions

diff --git a/jni/node-inl.h b/jni/node-inl.h
index e5344cc37..b635a1c48 100644
--- a/jni/node-inl.h
+++ b/jni/node-inl.h
@@ -41,13 +41,15 @@ namespace mediaprovider {
 namespace fuse {
 
 struct handle {
-    explicit handle(int fd, const RedactionInfo* ri, bool cached) : fd(fd), ri(ri), cached(cached) {
+    explicit handle(int fd, const RedactionInfo* ri, bool cached, uid_t uid)
+        : fd(fd), ri(ri), cached(cached), uid(uid) {
         CHECK(ri != nullptr);
     }
 
     const int fd;
     const std::unique_ptr<const RedactionInfo> ri;
     const bool cached;
+    const uid_t uid;
 
     ~handle() { close(fd); }
 };