Add enforcement of overlayable targetName

Adds android:targetName to the overlay manifest attributes and
PackageParser reads the name into PackageInfo. Specifying
android:targetName on an overlay allows the overlay to be associated
with a particular set of overlayable resources. The overlay can only
override the values of the resources defined within the target
overlayable element.

Test: idmap2_tests
Bug: 119390855
Bug: 110869880

Change-Id: I1128274af4cae983f61ae15cdfcbface63233ff2
diff --git a/cmds/idmap2/libidmap2/Idmap.cpp b/cmds/idmap2/libidmap2/Idmap.cpp
index 2890ae1..5d449e9 100644
--- a/cmds/idmap2/libidmap2/Idmap.cpp
+++ b/cmds/idmap2/libidmap2/Idmap.cpp
@@ -274,17 +274,24 @@
   return std::move(idmap);
 }
 
-bool CheckOverlayable(const LoadedPackage& target_package, PolicyBitmask fulfilled_polices,
-                      ResourceId resid) {
-  const OverlayableInfo* info = target_package.GetOverlayableInfo(resid);
-  if (info == nullptr) {
+bool CheckOverlayable(const LoadedPackage& target_package,
+                      const utils::OverlayManifestInfo& overlay_info,
+                      const PolicyBitmask& fulfilled_polices, const ResourceId& resid) {
+  const OverlayableInfo* overlayable_info = target_package.GetOverlayableInfo(resid);
+  if (overlayable_info == nullptr) {
     // If the resource does not have an overlayable definition, allow the resource to be overlaid.
     // Once overlayable enforcement is turned on, this check will return false.
     return true;
   }
 
+  if (!overlay_info.target_name.empty() && overlay_info.target_name != overlayable_info->name) {
+    // If the overlay supplies a target overlayable name, the resource must belong to the
+    // overlayable defined with the specified name to be overlaid.
+    return false;
+  }
+
   // Enforce policy restrictions if the resource is declared as overlayable.
-  return (info->policy_flags & fulfilled_polices) != 0;
+  return (overlayable_info->policy_flags & fulfilled_polices) != 0;
 }
 
 std::unique_ptr<const Idmap> Idmap::FromApkAssets(
@@ -339,6 +346,12 @@
     return nullptr;
   }
 
+  Result<utils::OverlayManifestInfo> overlay_info =
+      utils::ExtractOverlayManifestInfo(overlay_apk_path, out_error);
+  if (!overlay_info) {
+    return nullptr;
+  }
+
   std::unique_ptr<IdmapHeader> header(new IdmapHeader());
   header->magic_ = kIdmapMagic;
   header->version_ = kIdmapCurrentVersion;
@@ -393,9 +406,8 @@
       continue;
     }
 
-    if (enforce_overlayable && !CheckOverlayable(*target_pkg, fulfilled_policies, target_resid)) {
-      // The resources must be defined as overlayable and the overlay must fulfill at least one
-      // policy enforced on the overlayable resource
+    if (enforce_overlayable &&
+        !CheckOverlayable(*target_pkg, *overlay_info, fulfilled_policies, target_resid)) {
       LOG(WARNING) << "overlay \"" << overlay_apk_path << "\" is not allowed to overlay resource \""
                    << full_name << "\"" << std::endl;
       continue;
diff --git a/cmds/idmap2/libidmap2/ResourceUtils.cpp b/cmds/idmap2/libidmap2/ResourceUtils.cpp
index 04e0ec7..7a984f3 100644
--- a/cmds/idmap2/libidmap2/ResourceUtils.cpp
+++ b/cmds/idmap2/libidmap2/ResourceUtils.cpp
@@ -14,6 +14,7 @@
  * limitations under the License.
  */
 
+#include <memory>
 #include <string>
 
 #include "androidfw/StringPiece.h"
@@ -21,8 +22,13 @@
 
 #include "idmap2/ResourceUtils.h"
 #include "idmap2/Result.h"
+#include "idmap2/Xml.h"
+#include "idmap2/ZipFile.h"
 
 using android::StringPiece16;
+using android::idmap2::Result;
+using android::idmap2::Xml;
+using android::idmap2::ZipFile;
 using android::util::Utf16ToUtf8;
 
 namespace android::idmap2::utils {
@@ -47,4 +53,63 @@
   return {out};
 }
 
+Result<OverlayManifestInfo> ExtractOverlayManifestInfo(const std::string& path,
+                                                       std::ostream& out_error,
+                                                       bool assert_overlay) {
+  std::unique_ptr<const ZipFile> zip = ZipFile::Open(path);
+  if (!zip) {
+    out_error << "error: failed to open " << path << " as a zip file" << std::endl;
+    return kResultError;
+  }
+
+  std::unique_ptr<const MemoryChunk> entry = zip->Uncompress("AndroidManifest.xml");
+  if (!entry) {
+    out_error << "error: failed to uncompress AndroidManifest.xml from " << path << std::endl;
+    return kResultError;
+  }
+
+  std::unique_ptr<const Xml> xml = Xml::Create(entry->buf, entry->size);
+  if (!xml) {
+    out_error << "error: failed to parse AndroidManifest.xml from " << path << std::endl;
+    return kResultError;
+  }
+
+  OverlayManifestInfo info{};
+  const auto tag = xml->FindTag("overlay");
+  if (!tag) {
+    if (assert_overlay) {
+      out_error << "error: <overlay> missing from AndroidManifest.xml of " << path << std::endl;
+      return kResultError;
+    }
+    return info;
+  }
+
+  auto iter = tag->find("targetPackage");
+  if (iter == tag->end()) {
+    if (assert_overlay) {
+      out_error << "error: android:targetPackage missing from <overlay> of " << path << std::endl;
+      return kResultError;
+    }
+  } else {
+    info.target_package = iter->second;
+  }
+
+  iter = tag->find("targetName");
+  if (iter != tag->end()) {
+    info.target_name = iter->second;
+  }
+
+  iter = tag->find("isStatic");
+  if (iter != tag->end()) {
+    info.is_static = std::stoul(iter->second) != 0U;
+  }
+
+  iter = tag->find("priority");
+  if (iter != tag->end()) {
+    info.priority = std::stoi(iter->second);
+  }
+
+  return info;
+}
+
 }  // namespace android::idmap2::utils