Ignore symbols of imported libs' dependencies
When a library is present in a namespace via the secondary_namespaces
list (i.e. the executable, LD_PRELOAD, DF_1_GLOBAL, or
android_create_namespace inheritance), then we want to search that
library's symbols, but not the symbols of its dependencies. Otherwise,
we want to search the dependencies to handle cross-NS dependency.
Bug: http://b/148569846
Test: bionic unit tests
Change-Id: If798d69de28ed5c0f1a155e4ff85c7e08934e531
diff --git a/linker/linker_namespaces.cpp b/linker/linker_namespaces.cpp
index edbd592..b993689 100644
--- a/linker/linker_namespaces.cpp
+++ b/linker/linker_namespaces.cpp
@@ -71,7 +71,7 @@
// Are symbols from this shared object accessible for symbol lookups in a library from this
// namespace?
bool android_namespace_t::is_accessible(soinfo* s) {
- auto is_accessible_ftor = [this] (soinfo* si) {
+ auto is_accessible_ftor = [this] (soinfo* si, bool allow_secondary) {
// This is workaround for apps hacking into soinfo list.
// and inserting their own entries into it. (http://b/37191433)
if (!si->has_min_version(3)) {
@@ -84,20 +84,37 @@
return true;
}
- const android_namespace_list_t& secondary_namespaces = si->get_secondary_namespaces();
- if (secondary_namespaces.find(this) != secondary_namespaces.end()) {
- return true;
+ // When we're looking up symbols, we want to search libraries from the same namespace (whether
+ // the namespace membership is primary or secondary), but we also want to search the immediate
+ // dependencies of libraries in our namespace. (e.g. Supposing that libapp.so -> libandroid.so
+ // crosses a namespace boundary, we want to search libandroid.so but not any of libandroid.so's
+ // dependencies).
+ //
+ // Some libraries may be present in this namespace via the secondary namespace list:
+ // - the executable
+ // - LD_PRELOAD and DF_1_GLOBAL libraries
+ // - libraries inherited during dynamic namespace creation (e.g. because of
+ // RTLD_GLOBAL / DF_1_GLOBAL / ANDROID_NAMESPACE_TYPE_SHARED)
+ //
+ // When a library's membership is secondary, we want to search its symbols, but not the symbols
+ // of its dependencies. The executable may depend on internal system libraries which should not
+ // be searched.
+ if (allow_secondary) {
+ const android_namespace_list_t& secondary_namespaces = si->get_secondary_namespaces();
+ if (secondary_namespaces.find(this) != secondary_namespaces.end()) {
+ return true;
+ }
}
return false;
};
- if (is_accessible_ftor(s)) {
+ if (is_accessible_ftor(s, true)) {
return true;
}
return !s->get_parents().visit([&](soinfo* si) {
- return !is_accessible_ftor(si);
+ return !is_accessible_ftor(si, false);
});
}