Pass caller information in cancelBugreport.

In preparation for a broader set of apps using BugreportManager, we
enforce that only the app which started a bugreport is allowed to cancel
it.

Bug: 161393541
Test: atest BugreportManagerTestCases
Test: manual with two apps triggering/cancelling BRs
Change-Id: I10bdc9ff2a5746e2dc1e7d63876219bb34fad3b9
diff --git a/cmds/dumpstate/DumpstateService.cpp b/cmds/dumpstate/DumpstateService.cpp
index bfcc058..ba25a5a 100644
--- a/cmds/dumpstate/DumpstateService.cpp
+++ b/cmds/dumpstate/DumpstateService.cpp
@@ -39,8 +39,13 @@
     std::string calling_package;
 };
 
-static binder::Status exception(uint32_t code, const std::string& msg) {
-    MYLOGE("%s (%d) ", msg.c_str(), code);
+static binder::Status exception(uint32_t code, const std::string& msg,
+                                const std::string& extra_msg = "") {
+    if (extra_msg.empty()) {
+        MYLOGE("%s (%d) ", msg.c_str(), code);
+    } else {
+        MYLOGE("%s %s (%d) ", msg.c_str(), extra_msg.c_str(), code);
+    }
     return binder::Status::fromExceptionCode(code, String8(msg.c_str()));
 }
 
@@ -60,7 +65,7 @@
 
 }  // namespace
 
-DumpstateService::DumpstateService() : ds_(nullptr) {
+DumpstateService::DumpstateService() : ds_(nullptr), calling_uid_(-1), calling_package_() {
 }
 
 char const* DumpstateService::getServiceName() {
@@ -131,6 +136,10 @@
     ds_->SetOptions(std::move(options));
     ds_->listener_ = listener;
 
+    // Track caller info for cancellation purposes.
+    calling_uid_ = calling_uid;
+    calling_package_ = calling_package;
+
     DumpstateInfo* ds_info = new DumpstateInfo();
     ds_info->ds = ds_;
     ds_info->calling_uid = calling_uid;
@@ -149,8 +158,20 @@
     return binder::Status::ok();
 }
 
-binder::Status DumpstateService::cancelBugreport() {
+binder::Status DumpstateService::cancelBugreport(int32_t calling_uid,
+                                                 const std::string& calling_package) {
     std::lock_guard<std::mutex> lock(lock_);
+    if (calling_uid != calling_uid_ || calling_package != calling_package_) {
+        // Note: we use a SecurityException to prevent BugreportManagerServiceImpl from killing the
+        // report in progress (from another caller).
+        return exception(
+            binder::Status::EX_SECURITY,
+            StringPrintf("Cancellation requested by %d/%s does not match report in "
+                         "progress",
+                         calling_uid, calling_package.c_str()),
+            // Sharing the owner of the BR is a (minor) leak, so leave it out of the app's exception
+            StringPrintf("started by %d/%s", calling_uid_, calling_package_.c_str()));
+    }
     ds_->Cancel();
     return binder::Status::ok();
 }