Introducing linker namespaces

Bug: http://b/22548808
Change-Id: Ia3af3c0a167f1d16447a3d83bb045d143319b1e1

libc/include/android/dlext.h

@@ -98,6 +98,11 @@ enum {
    */
   ANDROID_DLEXT_LOAD_AT_FIXED_ADDRESS = 0x100,
 
+  /* This flag used to load library in a different namespace. The namespace is
+   * specified in library_namespace.
+   */
+  ANDROID_DLEXT_USE_NAMESPACE = 0x200,
+
   /* Mask of valid bits */
   ANDROID_DLEXT_VALID_FLAG_BITS       = ANDROID_DLEXT_RESERVED_ADDRESS |
                                         ANDROID_DLEXT_RESERVED_ADDRESS_HINT |
@@ -107,9 +112,12 @@ enum {
                                         ANDROID_DLEXT_USE_LIBRARY_FD_OFFSET |
                                         ANDROID_DLEXT_FORCE_LOAD |
                                         ANDROID_DLEXT_FORCE_FIXED_VADDR |
-                                        ANDROID_DLEXT_LOAD_AT_FIXED_ADDRESS,
+                                        ANDROID_DLEXT_LOAD_AT_FIXED_ADDRESS |
+                                        ANDROID_DLEXT_USE_NAMESPACE,
 };
 
+struct android_namespace_t;
+
 typedef struct {
   uint64_t flags;
   void*   reserved_addr;
@@ -117,10 +125,40 @@ typedef struct {
   int     relro_fd;
   int     library_fd;
   off64_t library_fd_offset;
+  struct android_namespace_t* library_namespace;
 } android_dlextinfo;
 
 extern void* android_dlopen_ext(const char* filename, int flag, const android_dlextinfo* extinfo);
 
+/*
+ * Initializes public namespace. The path is the list of sonames
+ * separated by colon. Example: "libc.so:libm.so:libdl.so".
+ *
+ * The libraries in this list should be loaded prior to this call.
+ */
+extern bool android_init_public_namespace(const char* path);
+
+/*
+ * Creates new linker namespace.
+ * ld_library_path and default_library_path represent the search path
+ * for the libraries in the namespace.
+ *
+ * The libraries in the namespace are searched by folowing order:
+ * 1. ld_library_path (Think of this as namespace-local LD_LIBRARY_PATH)
+ * 2. In directories specified by DT_RUNPATH of the "needed by" binary.
+ * 3. deault_library_path (This of this as namespace-local default library path)
+ *
+ * When is_isolated is true the resulted namespace requires all of the libraries
+ * to be on the search path; the search_path is ld_library_path:default_library_path.
+ *
+ * If a library or any of its dependencies are outside of the search path and not
+ * part of the public namespace dlopen will fail.
+ */
+extern struct android_namespace_t* android_create_namespace(const char* name,
+                                                            const char* ld_library_path,
+                                                            const char* default_library_path,
+                                                            bool is_isolated);
+
 __END_DECLS
 
 #endif /* __ANDROID_DLEXT_H__ */

libdl/libdl.arm.map

@@ -14,10 +14,16 @@ LIBC {
     *;
 };
 
+LIBC_N {
+  global:
+    android_init_public_namespace;
+    android_create_namespace;
+} LIBC;
+
 LIBC_PRIVATE {
   global:
     android_get_application_target_sdk_version;
     android_set_application_target_sdk_version;
     android_get_LD_LIBRARY_PATH;
     android_update_LD_LIBRARY_PATH;
-} LIBC;
+} LIBC_N;

libdl/libdl.arm64.map

@@ -13,10 +13,16 @@ LIBC {
     *;
 };
 
+LIBC_N {
+  global:
+    android_init_public_namespace;
+    android_create_namespace;
+} LIBC;
+
 LIBC_PRIVATE {
   global:
     android_get_application_target_sdk_version;
     android_set_application_target_sdk_version;
     android_get_LD_LIBRARY_PATH;
     android_update_LD_LIBRARY_PATH;
-} LIBC;
+} LIBC_N;

libdl/libdl.c

@@ -33,12 +33,26 @@ int dlclose(void* handle __unused) { return 0; }
 _Unwind_Ptr dl_unwind_find_exidx(_Unwind_Ptr pc __unused, int* pcount __unused) { return 0; }
 #endif
 
-int dl_iterate_phdr(int (*cb)(struct dl_phdr_info* info, size_t size, void* data) __unused, void* data __unused) { return 0; }
+int dl_iterate_phdr(int (*cb)(struct dl_phdr_info* info, size_t size, void* data) __unused,
+                    void* data __unused) {
+  return 0;
+}
 
 void android_get_LD_LIBRARY_PATH(char* buffer __unused, size_t buffer_size __unused) { }
 void android_update_LD_LIBRARY_PATH(const char* ld_library_path __unused) { }
 
-void* android_dlopen_ext(const char* filename __unused, int flag __unused, const android_dlextinfo* extinfo __unused) { return 0; }
+void* android_dlopen_ext(const char* filename __unused, int flag __unused,
+                         const android_dlextinfo* extinfo __unused) {
+  return 0;
+}
 
 void android_set_application_target_sdk_version(uint32_t target __unused) { }
 uint32_t android_get_application_target_sdk_version() { return 0; }
+
+bool android_init_public_namespace(const char* paths __unused) { return false; }
+struct android_namespace_t* android_create_namespace(const char* name __unused,
+                                                     const char* ld_library_path __unused,
+                                                     const char* default_library_path __unused,
+                                                     bool isolated __unused) {
+  return 0;
+}

libdl/libdl.map.txt

@@ -28,10 +28,16 @@ LIBC {
     *;
 };
 
+LIBC_N {
+  global:
+    android_init_public_namespace;
+    android_create_namespace;
+} LIBC;
+
 LIBC_PRIVATE {
   global:
     android_get_application_target_sdk_version;
     android_set_application_target_sdk_version;
     android_get_LD_LIBRARY_PATH;
     android_update_LD_LIBRARY_PATH;
-} LIBC;
+} LIBC_N;

libdl/libdl.mips.map

@@ -13,10 +13,16 @@ LIBC {
     *;
 };
 
+LIBC_N {
+  global:
+    android_init_public_namespace;
+    android_create_namespace;
+} LIBC;
+
 LIBC_PRIVATE {
   global:
     android_get_application_target_sdk_version;
     android_set_application_target_sdk_version;
     android_get_LD_LIBRARY_PATH;
     android_update_LD_LIBRARY_PATH;
-} LIBC;
+} LIBC_N;

libdl/libdl.mips64.map

@@ -13,10 +13,16 @@ LIBC {
     *;
 };
 
+LIBC_N {
+  global:
+    android_init_public_namespace;
+    android_create_namespace;
+} LIBC;
+
 LIBC_PRIVATE {
   global:
     android_get_application_target_sdk_version;
     android_set_application_target_sdk_version;
     android_get_LD_LIBRARY_PATH;
     android_update_LD_LIBRARY_PATH;
-} LIBC;
+} LIBC_N;

libdl/libdl.x86.map

@@ -13,10 +13,16 @@ LIBC {
     *;
 };
 
+LIBC_N {
+  global:
+    android_init_public_namespace;
+    android_create_namespace;
+} LIBC;
+
 LIBC_PRIVATE {
   global:
     android_get_application_target_sdk_version;
     android_set_application_target_sdk_version;
     android_get_LD_LIBRARY_PATH;
     android_update_LD_LIBRARY_PATH;
-} LIBC;
+} LIBC_N;

libdl/libdl.x86_64.map

@@ -13,10 +13,16 @@ LIBC {
     *;
 };
 
+LIBC_N {
+  global:
+    android_init_public_namespace;
+    android_create_namespace;
+} LIBC;
+
 LIBC_PRIVATE {
   global:
     android_get_application_target_sdk_version;
     android_set_application_target_sdk_version;
     android_get_LD_LIBRARY_PATH;
     android_update_LD_LIBRARY_PATH;
-} LIBC;
+} LIBC_N;

linker/Android.mk

@@ -9,12 +9,12 @@ LOCAL_SRC_FILES := \
     dlfcn.cpp \
     linker.cpp \
     linker_allocator.cpp \
-    linker_sdk_versions.cpp \
     linker_block_allocator.cpp \
     linker_libc_support.c \
     linker_mapped_file_fragment.cpp \
     linker_memory.cpp \
     linker_phdr.cpp \
+    linker_sdk_versions.cpp \
     linker_utils.cpp \
     rt.cpp \
 

linker/dlfcn.cpp

@@ -108,9 +108,16 @@ void* dlsym(void* handle, const char* symbol) {
   const ElfW(Sym)* sym = nullptr;
   void* caller_addr = __builtin_return_address(0);
   soinfo* caller = find_containing_library(caller_addr);
+  if (caller == nullptr) {
+    char buf[256];
+    __libc_format_buffer(buf, sizeof(buf), "dlsym couldn't locate its caller address=%p; "
+                         "the caller was code not loaded by the dynamic linker", caller_addr);
+    __bionic_format_dlerror(buf, nullptr);
+    return nullptr;
+  }
 
   if (handle == RTLD_DEFAULT || handle == RTLD_NEXT) {
-    sym = dlsym_linear_lookup(symbol, &found, caller, handle);
+    sym = dlsym_linear_lookup(caller->get_namespace(), symbol, &found, caller, handle);
   } else {
     sym = dlsym_handle_lookup(reinterpret_cast<soinfo*>(handle), &found, symbol);
   }
@@ -177,6 +184,30 @@ uint32_t android_get_application_target_sdk_version() {
   return get_application_target_sdk_version();
 }
 
+bool android_init_public_namespace(const char* path) {
+  ScopedPthreadMutexLocker locker(&g_dl_mutex);
+  bool success = init_public_namespace(path);
+  if (!success) {
+    __bionic_format_dlerror("android_init_public_namespace failed", linker_get_error_buffer());
+  }
+
+  return success;
+}
+
+android_namespace_t* android_create_namespace(const char* name, const char* ld_library_path,
+                                              const char* default_library_path, bool is_isolated) {
+  ScopedPthreadMutexLocker locker(&g_dl_mutex);
+
+  android_namespace_t* result = create_namespace(name, ld_library_path,
+                                                 default_library_path, is_isolated);
+
+  if (result == nullptr) {
+    __bionic_format_dlerror("android_create_namespace failed", linker_get_error_buffer());
+  }
+
+  return result;
+}
+
 // name_offset: starting index of the name in libdl_info.strtab
 #define ELF32_SYM_INITIALIZER(name_offset, value, shndx) \
     { name_offset, \
@@ -203,11 +234,11 @@ static const char ANDROID_LIBDL_STRTAB[] =
   // 00000000001 1111111112222222222 3333333333444444444455555555556666666666777 777777788888888889999999999
   // 01234567890 1234567890123456789 0123456789012345678901234567890123456789012 345678901234567890123456789
     "erate_phdr\0android_dlopen_ext\0android_set_application_target_sdk_version\0android_get_application_tar"
-  // 0000000000111111
+  // 0000000000111111 111122222222223333333333444444 4444555555555566666666667
-  // 0123456789012345
+  // 0123456789012345 678901234567890123456789012345 6789012345678901234567890
-    "get_sdk_version\0"
+    "get_sdk_version\0android_init_public_namespace\0android_create_namespace\0"
 #if defined(__arm__)
-  // 216
+  // 271
     "dl_unwind_find_exidx\0"
 #endif
     ;
@@ -229,8 +260,10 @@ static ElfW(Sym) g_libdl_symtab[] = {
   ELFW(SYM_INITIALIZER)(111, &android_dlopen_ext, 1),
   ELFW(SYM_INITIALIZER)(130, &android_set_application_target_sdk_version, 1),
   ELFW(SYM_INITIALIZER)(173, &android_get_application_target_sdk_version, 1),
+  ELFW(SYM_INITIALIZER)(216, &android_init_public_namespace, 1),
+  ELFW(SYM_INITIALIZER)(246, &android_create_namespace, 1),
 #if defined(__arm__)
-  ELFW(SYM_INITIALIZER)(216, &dl_unwind_find_exidx, 1),
+  ELFW(SYM_INITIALIZER)(271, &dl_unwind_find_exidx, 1),
 #endif
 };
 
@@ -247,18 +280,20 @@ static ElfW(Sym) g_libdl_symtab[] = {
 // Note that adding any new symbols here requires stubbing them out in libdl.
 static unsigned g_libdl_buckets[1] = { 1 };
 #if defined(__arm__)
-static unsigned g_libdl_chains[] = { 0, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 0 };
+static unsigned g_libdl_chains[] = { 0, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 0 };
 #else
-static unsigned g_libdl_chains[] = { 0, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 0 };
+static unsigned g_libdl_chains[] = { 0, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 0 };
 #endif
 
 static uint8_t __libdl_info_buf[sizeof(soinfo)] __attribute__((aligned(8)));
 static soinfo* __libdl_info = nullptr;
 
+extern android_namespace_t g_default_namespace;
+
 // This is used by the dynamic linker. Every process gets these symbols for free.
 soinfo* get_libdl_info() {
   if (__libdl_info == nullptr) {
-    __libdl_info = new (__libdl_info_buf) soinfo("libdl.so", nullptr, 0, RTLD_GLOBAL);
+    __libdl_info = new (__libdl_info_buf) soinfo(&g_default_namespace, "libdl.so", nullptr, 0, RTLD_GLOBAL);
     __libdl_info->flags_ |= FLAG_LINKED;
     __libdl_info->strtab_ = ANDROID_LIBDL_STRTAB;
     __libdl_info->symtab_ = g_libdl_symtab;

linker/linked_list.h

@@ -25,12 +25,49 @@ struct LinkedListEntry {
   T* element;
 };
 
+// ForwardInputIterator
+template<typename T>
+class LinkedListIterator {
+ public:
+  LinkedListIterator() : entry_(nullptr) {}
+  LinkedListIterator(const LinkedListIterator<T>& that) : entry_(that.entry_) {}
+  explicit LinkedListIterator(LinkedListEntry<T>* entry) : entry_(entry) {}
+
+  LinkedListIterator<T>& operator=(const LinkedListIterator<T>& that) {
+    entry_ = that.entry_;
+    return *this;
+  }
+
+  LinkedListIterator<T>& operator++() {
+    entry_ = entry_->next;
+    return *this;
+  }
+
+  T* operator*() {
+    return entry_->element;
+  }
+
+  bool operator==(const LinkedListIterator<T>& that) const {
+    return entry_ == that.entry_;
+  }
+
+  bool operator!=(const LinkedListIterator<T>& that) const {
+    return entry_ != that.entry_;
+  }
+
+ private:
+  LinkedListEntry<T> *entry_;
+};
+
 /*
  * Represents linked list of objects of type T
  */
 template<typename T, typename Allocator>
 class LinkedList {
  public:
+  typedef LinkedListIterator<T> iterator;
+  typedef T* value_type;
+
   LinkedList() : head_(nullptr), tail_(nullptr) {}
   ~LinkedList() {
     clear();
@@ -133,6 +170,7 @@ class LinkedList {
         }
 
         Allocator::free(e);
+
         e = next;
       } else {
         p = e;
@@ -152,6 +190,24 @@ class LinkedList {
     return nullptr;
   }
 
+  iterator begin() {
+    return iterator(head_);
+  }
+
+  iterator end() {
+    return iterator(nullptr);
+  }
+
+  iterator find(T* value) {
+    for (LinkedListEntry<T>* e = head_; e != nullptr; e = e->next) {
+      if (e->element == value) {
+        return iterator(e);
+      }
+    }
+
+    return end();
+  }
+
   size_t copy_to_array(T* array[], size_t array_length) const {
     size_t sz = 0;
     for (LinkedListEntry<T>* e = head_; sz < array_length && e != nullptr; e = e->next) {

linker/linker.cpp

@@ -70,11 +70,55 @@ extern void __libc_init_AT_SECURE(KernelArgumentBlock&);
 #undef ELF_ST_TYPE
 #define ELF_ST_TYPE(x) (static_cast<uint32_t>(x) & 0xf)
 
+struct android_namespace_t {
+ public:
+  android_namespace_t() : name_(nullptr), is_isolated_(false) {}
+
+  const char* get_name() const { return name_; }
+  void set_name(const char* name) { name_ = name; }
+
+  bool is_isolated() const { return is_isolated_; }
+  void set_isolated(bool isolated) { is_isolated_ = isolated; }
+
+  const std::vector<std::string>& get_ld_library_paths() const {
+    return ld_library_paths_;
+  }
+  void set_ld_library_paths(std::vector<std::string>&& library_paths) {
+    ld_library_paths_ = library_paths;
+  }
+
+  const std::vector<std::string>& get_default_library_paths() const {
+    return default_library_paths_;
+  }
+  void set_default_library_paths(std::vector<std::string>&& library_paths) {
+    default_library_paths_ = library_paths;
+  }
+
+  soinfo::soinfo_list_t& soinfo_list() { return soinfo_list_; }
+
+  // For isolated namespaces - checks if the file is on the search path;
+  // always returns true for not isolated namespace.
+  bool is_accessible(const std::string& path);
+
+ private:
+  const char* name_;
+  bool is_isolated_;
+  std::vector<std::string> ld_library_paths_;
+  std::vector<std::string> default_library_paths_;
+  soinfo::soinfo_list_t soinfo_list_;
+
+  DISALLOW_COPY_AND_ASSIGN(android_namespace_t);
+};
+
+android_namespace_t g_default_namespace;
+
 static ElfW(Addr) get_elf_exec_load_bias(const ElfW(Ehdr)* elf);
 
 static LinkerTypeAllocator<soinfo> g_soinfo_allocator;
 static LinkerTypeAllocator<LinkedListEntry<soinfo>> g_soinfo_links_allocator;
 
+static LinkerTypeAllocator<android_namespace_t> g_namespace_allocator;
+
 static soinfo* solist;
 static soinfo* sonext;
 static soinfo* somain; // main process, always the one after libdl_info
@@ -107,14 +151,15 @@ static const char* const kAsanDefaultLdPaths[] = {
 
 static const ElfW(Versym) kVersymNotNeeded = 0;
 static const ElfW(Versym) kVersymGlobal = 1;
-static const char* const kZipFileSeparator = "!/";
 
 static const char* const* g_default_ld_paths;
-static std::vector<std::string> g_ld_library_paths;
 static std::vector<std::string> g_ld_preload_names;
 
 static std::vector<soinfo*> g_ld_preloads;
 
+static bool g_public_namespace_initialized;
+static soinfo::soinfo_list_t g_public_namespace;
+
 __LIBC_HIDDEN__ int g_ld_debug_verbosity;
 
 __LIBC_HIDDEN__ abort_msg_t* g_abort_message = nullptr; // For debuggerd.
@@ -247,6 +292,26 @@ void notify_gdb_of_libraries() {
   rtld_db_dlactivity();
 }
 
+bool android_namespace_t::is_accessible(const std::string& file) {
+  if (!is_isolated_) {
+    return true;
+  }
+
+  for (const auto& dir : ld_library_paths_) {
+    if (file_is_in_dir(file, dir)) {
+      return true;
+    }
+  }
+
+  for (const auto& dir : default_library_paths_) {
+    if (file_is_in_dir(file, dir)) {
+      return true;
+    }
+  }
+
+  return false;
+}
+
 LinkedListEntry<soinfo>* SoinfoListAllocator::alloc() {
   return g_soinfo_links_allocator.alloc();
 }
@@ -255,18 +320,22 @@ void SoinfoListAllocator::free(LinkedListEntry<soinfo>* entry) {
   g_soinfo_links_allocator.free(entry);
 }
 
-static soinfo* soinfo_alloc(const char* name, struct stat* file_stat,
+static soinfo* soinfo_alloc(android_namespace_t* ns, const char* name,
-                            off64_t file_offset, uint32_t rtld_flags) {
+                            struct stat* file_stat, off64_t file_offset,
+                            uint32_t rtld_flags) {
   if (strlen(name) >= PATH_MAX) {
     DL_ERR("library name \"%s\" too long", name);
     return nullptr;
   }
 
-  soinfo* si = new (g_soinfo_allocator.alloc()) soinfo(name, file_stat, file_offset, rtld_flags);
+  soinfo* si = new (g_soinfo_allocator.alloc()) soinfo(ns, name, file_stat,
+                                                       file_offset, rtld_flags);
 
   sonext->next = si;
   sonext = si;
 
+  ns->soinfo_list().push_back(si);
+
   TRACE("name %s: allocated soinfo @ %p", name, si);
   return si;
 }
@@ -307,33 +376,130 @@ static void soinfo_free(soinfo* si) {
     sonext = prev;
   }
 
+  // remove from the namespace
+  si->get_namespace()->soinfo_list().remove_if([&](soinfo* candidate) {
+    return si == candidate;
+  });
+
   si->~soinfo();
   g_soinfo_allocator.free(si);
 }
 
-static void parse_path(const char* path, const char* delimiters,
+// For every path element this function checks of it exists, and is a directory,
+// and normalizes it:
+// 1. For regular path it converts it to realpath()
+// 2. For path in a zip file it uses realpath on the zipfile
+//    normalizes entry name by calling normalize_path function.
+static void resolve_paths(std::vector<std::string>& paths,
+                          std::vector<std::string>* resolved_paths) {
+  resolved_paths->clear();
+  for (const auto& path : paths) {
+    char resolved_path[PATH_MAX];
+    const char* original_path = path.c_str();
+    if (realpath(original_path, resolved_path) != nullptr) {
+      struct stat s;
+      if (stat(resolved_path, &s) == 0) {
+        if (S_ISDIR(s.st_mode)) {
+          resolved_paths->push_back(resolved_path);
+        } else {
+          DL_WARN("Warning: \"%s\" is not a directory (excluding from path)", resolved_path);
+          continue;
+        }
+      } else {
+        DL_WARN("Warning: cannot stat file \"%s\": %s", resolved_path, strerror(errno));
+        continue;
+      }
+    } else {
+      std::string zip_path;
+      std::string entry_path;
+
+      std::string normalized_path;
+
+      if (!normalize_path(original_path, &normalized_path)) {
+        DL_WARN("Warning: unable to normalize \"%s\"", original_path);
+        continue;
+      }
+
+      if (parse_zip_path(normalized_path.c_str(), &zip_path, &entry_path)) {
+        if (realpath(zip_path.c_str(), resolved_path) == nullptr) {
+          DL_WARN("Warning: unable to resolve \"%s\": %s", zip_path.c_str(), strerror(errno));
+          continue;
+        }
+
+        ZipArchiveHandle handle = nullptr;
+        if (OpenArchive(resolved_path, &handle) != 0) {
+          DL_WARN("Warning: unable to open zip archive: %s", resolved_path);
+          continue;
+        }
+
+        // Check if zip-file has a dir with entry_path name
+        void* cookie = nullptr;
+        std::string prefix_str = entry_path + "/";
+        ZipString prefix(prefix_str.c_str());
+
+        ZipEntry out_data;
+        ZipString out_name;
+
+        int32_t error_code;
+
+        if ((error_code = StartIteration(handle, &cookie, &prefix, nullptr)) != 0) {
+          DL_WARN("Unable to iterate over zip-archive entries \"%s\";"
+                  " error code: %d", zip_path.c_str(), error_code);
+          continue;
+        }
+
+        if (Next(cookie, &out_data, &out_name) != 0) {
+          DL_WARN("Unable to find entries starting with \"%s\" in \"%s\"",
+                  prefix_str.c_str(), zip_path.c_str());
+          continue;
+        }
+
+        auto zip_guard = make_scope_guard([&]() {
+          if (cookie != nullptr) {
+            EndIteration(cookie);
+          }
+          CloseArchive(handle);
+        });
+
+        resolved_paths->push_back(std::string(resolved_path) + kZipFileSeparator + entry_path);
+      }
+    }
+  }
+}
+
+static void split_path(const char* path, const char* delimiters,
                        std::vector<std::string>* paths) {
-  paths->clear();
   if (path != nullptr) {
     *paths = android::base::Split(path, delimiters);
   }
 }
 
+static void parse_path(const char* path, const char* delimiters,
+                       std::vector<std::string>* resolved_paths) {
+  std::vector<std::string> paths;
+  split_path(path, delimiters, &paths);
+  resolve_paths(paths, resolved_paths);
+}
+
 static void parse_LD_LIBRARY_PATH(const char* path) {
-  parse_path(path, ":", &g_ld_library_paths);
+  std::vector<std::string> ld_libary_paths;
+  parse_path(path, ":", &ld_libary_paths);
+  g_default_namespace.set_ld_library_paths(std::move(ld_libary_paths));
 }
 
 void soinfo::set_dt_runpath(const char* path) {
-  if (!has_min_version(2)) {
+  if (!has_min_version(3)) {
     return;
   }
 
-  parse_path(path, ":", &dt_runpath_);
+  std::vector<std::string> runpaths;
+
+  split_path(path, ":", &runpaths);
 
   std::string origin = dirname(get_realpath());
   // FIXME: add $LIB and $PLATFORM.
   std::pair<std::string, std::string> substs[] = {{"ORIGIN", origin}};
-  for (auto&& s : dt_runpath_) {
+  for (auto&& s : runpaths) {
     size_t pos = 0;
     while (pos < s.size()) {
       pos = s.find("$", pos);
@@ -356,11 +522,16 @@ void soinfo::set_dt_runpath(const char* path) {
       ++pos;
     }
   }
+
+  resolve_paths(runpaths, &dt_runpath_);
 }
 
 static void parse_LD_PRELOAD(const char* path) {
-  // We have historically supported ':' as well as ' ' in LD_PRELOAD.
+  g_ld_preload_names.clear();
-  parse_path(path, " :", &g_ld_preload_names);
+  if (path != nullptr) {
+    // We have historically supported ':' as well as ' ' in LD_PRELOAD.
+    g_ld_preload_names = android::base::Split(path, " :");
+  }
 }
 
 static bool realpath_fd(int fd, std::string* realpath) {
@@ -688,8 +859,9 @@ bool soinfo::elf_lookup(SymbolName& symbol_name,
   return true;
 }
 
-soinfo::soinfo(const char* realpath, const struct stat* file_stat,
+soinfo::soinfo(android_namespace_t* ns, const char* realpath,
-               off64_t file_offset, int rtld_flags) {
+               const struct stat* file_stat, off64_t file_offset,
+               int rtld_flags) {
   memset(this, 0, sizeof(*this));
 
   if (realpath != nullptr) {
@@ -706,6 +878,7 @@ soinfo::soinfo(const char* realpath, const struct stat* file_stat,
   }
 
   this->rtld_flags_ = rtld_flags;
+  this->namespace_ = ns;
 }
 
 
@@ -857,6 +1030,7 @@ class ProtectedDataGuard {
   void protect_data(int protection) {
     g_soinfo_allocator.protect_all(protection);
     g_soinfo_links_allocator.protect_all(protection);
+    g_namespace_allocator.protect_all(protection);
   }
 
   static size_t ref_count_;
@@ -1096,7 +1270,7 @@ const ElfW(Sym)* dlsym_handle_lookup(soinfo* si, soinfo** found, const char* nam
   // libraries and they are loaded in breath-first (correct) order we can just execute
   // dlsym(RTLD_DEFAULT, ...); instead of doing two stage lookup.
   if (si == somain) {
-    return dlsym_linear_lookup(name, found, nullptr, RTLD_DEFAULT);
+    return dlsym_linear_lookup(&g_default_namespace, name, found, nullptr, RTLD_DEFAULT);
   }
 
   SymbolName symbol_name(name);
@@ -1108,24 +1282,29 @@ const ElfW(Sym)* dlsym_handle_lookup(soinfo* si, soinfo** found, const char* nam
    beginning of the global solist. Otherwise the search starts at the
    specified soinfo (for RTLD_NEXT).
  */
-const ElfW(Sym)* dlsym_linear_lookup(const char* name,
+const ElfW(Sym)* dlsym_linear_lookup(android_namespace_t* ns,
+                                     const char* name,
                                      soinfo** found,
                                      soinfo* caller,
                                      void* handle) {
   SymbolName symbol_name(name);
 
-  soinfo* start = solist;
+  soinfo::soinfo_list_t& soinfo_list = ns->soinfo_list();
+  soinfo::soinfo_list_t::iterator start = soinfo_list.begin();
 
   if (handle == RTLD_NEXT) {
     if (caller == nullptr) {
       return nullptr;
     } else {
-      start = caller->next;
+      soinfo::soinfo_list_t::iterator it = soinfo_list.find(caller);
+      CHECK (it != soinfo_list.end());
+      start = ++it;
     }
   }
 
   const ElfW(Sym)* s = nullptr;
-  for (soinfo* si = start; si != nullptr; si = si->next) {
+  for (soinfo::soinfo_list_t::iterator it = start, end = soinfo_list.end(); it != end; ++it) {
+    soinfo* si = *it;
     // Do not skip RTLD_LOCAL libraries in dlsym(RTLD_DEFAULT, ...)
     // if the library is opened by application with target api level <= 22
     // See http://b/21565766
@@ -1337,35 +1516,13 @@ static bool format_path(char* buf, size_t buf_size, const char* path, const char
   return true;
 }
 
-static int open_library_on_default_path(const char* name, off64_t* file_offset, std::string* realpath) {
-  for (size_t i = 0; g_default_ld_paths[i] != nullptr; ++i) {
-    char buf[512];
-    if (!format_path(buf, sizeof(buf), g_default_ld_paths[i], name)) {
-      continue;
-    }
-
-    int fd = TEMP_FAILURE_RETRY(open(buf, O_RDONLY | O_CLOEXEC));
-    if (fd != -1) {
-      *file_offset = 0;
-      if (!realpath_fd(fd, realpath)) {
-        PRINT("warning: unable to get realpath for the library \"%s\". Will use given path.", buf);
-        *realpath = buf;
-      }
-      return fd;
-    }
-  }
-
-  return -1;
-}
-
 static int open_library_on_paths(ZipArchiveCache* zip_archive_cache,
                                  const char* name, off64_t* file_offset,
                                  const std::vector<std::string>& paths,
                                  std::string* realpath) {
-  for (const auto& path_str : paths) {
+  for (const auto& path : paths) {
     char buf[512];
-    const char* const path = path_str.c_str();
+    if (!format_path(buf, sizeof(buf), path.c_str(), name)) {
-    if (!format_path(buf, sizeof(buf), path, name)) {
       continue;
     }
 
@@ -1393,39 +1550,49 @@ static int open_library_on_paths(ZipArchiveCache* zip_archive_cache,
   return -1;
 }
 
-static int open_library(ZipArchiveCache* zip_archive_cache,
+static int open_library(android_namespace_t* ns,
+                        ZipArchiveCache* zip_archive_cache,
                         const char* name, soinfo *needed_by,
                         off64_t* file_offset, std::string* realpath) {
   TRACE("[ opening %s ]", name);
 
   // If the name contains a slash, we should attempt to open it directly and not search the paths.
   if (strchr(name, '/') != nullptr) {
+    int fd = -1;
+
     if (strstr(name, kZipFileSeparator) != nullptr) {
-      int fd = open_library_in_zipfile(zip_archive_cache, name, file_offset, realpath);
+      fd = open_library_in_zipfile(zip_archive_cache, name, file_offset, realpath);
+    }
+
+    if (fd == -1) {
+      fd = TEMP_FAILURE_RETRY(open(name, O_RDONLY | O_CLOEXEC));
       if (fd != -1) {
-        return fd;
+        *file_offset = 0;
+        if (!realpath_fd(fd, realpath)) {
+          PRINT("warning: unable to get realpath for the library \"%s\". Will use given path.", name);
+          *realpath = name;
+        }
       }
     }
 
-    int fd = TEMP_FAILURE_RETRY(open(name, O_RDONLY | O_CLOEXEC));
+    if (fd != -1 && !ns->is_accessible(*realpath)) {
-    if (fd != -1) {
+      fd = -1;
-      *file_offset = 0;
-      if (!realpath_fd(fd, realpath)) {
-        PRINT("warning: unable to get realpath for the library \"%s\". Will use given path.", name);
-        *realpath = name;
-      }
     }
     return fd;
   }
 
-  // Otherwise we try LD_LIBRARY_PATH first, and fall back to the built-in well known paths.
+  // Otherwise we try LD_LIBRARY_PATH first, and fall back to the default library path
-  int fd = open_library_on_paths(zip_archive_cache, name, file_offset, g_ld_library_paths, realpath);
+  int fd = open_library_on_paths(zip_archive_cache, name, file_offset, ns->get_ld_library_paths(), realpath);
   if (fd == -1 && needed_by != nullptr) {
     fd = open_library_on_paths(zip_archive_cache, name, file_offset, needed_by->get_dt_runpath(), realpath);
+    // Check if the library is accessible
+    if (fd != -1 && !ns->is_accessible(*realpath)) {
+      fd = -1;
+    }
   }
 
   if (fd == -1) {
-    fd = open_library_on_default_path(name, file_offset, realpath);
+    fd = open_library_on_paths(zip_archive_cache, name, file_offset, ns->get_default_library_paths(), realpath);
   }
 
   return fd;
@@ -1464,7 +1631,8 @@ static void for_each_dt_needed(const ElfReader& elf_reader, F action) {
   }
 }
 
-static bool load_library(LoadTask* task,
+static bool load_library(android_namespace_t* ns,
+                         LoadTask* task,
                          LoadTaskList* load_tasks,
                          int rtld_flags,
                          const std::string& realpath) {
@@ -1495,18 +1663,30 @@ static bool load_library(LoadTask* task,
   // Check for symlink and other situations where
   // file can have different names, unless ANDROID_DLEXT_FORCE_LOAD is set
   if (extinfo == nullptr || (extinfo->flags & ANDROID_DLEXT_FORCE_LOAD) == 0) {
-    for (soinfo* si = solist; si != nullptr; si = si->next) {
+    auto predicate = [&](soinfo* si) {
-      if (si->get_st_dev() != 0 &&
+      return si->get_st_dev() != 0 &&
-          si->get_st_ino() != 0 &&
+             si->get_st_ino() != 0 &&
-          si->get_st_dev() == file_stat.st_dev &&
+             si->get_st_dev() == file_stat.st_dev &&
-          si->get_st_ino() == file_stat.st_ino &&
+             si->get_st_ino() == file_stat.st_ino &&
-          si->get_file_offset() == file_offset) {
+             si->get_file_offset() == file_offset;
-        TRACE("library \"%s\" is already loaded under different name/path \"%s\" - "
+    };
-            "will return existing soinfo", name, si->get_realpath());
+
-        task->set_soinfo(si);
+    soinfo* si = ns->soinfo_list().find_if(predicate);
-        return true;
+
+    // check public namespace
+    if (si == nullptr) {
+      si = g_public_namespace.find_if(predicate);
+      if (si != nullptr) {
+        ns->soinfo_list().push_back(si);
       }
     }
+
+    if (si != nullptr) {
+      TRACE("library \"%s\" is already loaded under different name/path \"%s\" - "
+            "will return existing soinfo", name, si->get_realpath());
+      task->set_soinfo(si);
+      return true;
+    }
   }
 
   if ((rtld_flags & RTLD_NOLOAD) != 0) {
@@ -1514,7 +1694,7 @@ static bool load_library(LoadTask* task,
     return false;
   }
 
-  soinfo* si = soinfo_alloc(realpath.c_str(), &file_stat, file_offset, rtld_flags);
+  soinfo* si = soinfo_alloc(ns, realpath.c_str(), &file_stat, file_offset, rtld_flags);
   if (si == nullptr) {
     return false;
   }
@@ -1550,7 +1730,8 @@ static bool load_library(LoadTask* task,
 
 }
 
-static bool load_library(LoadTask* task,
+static bool load_library(android_namespace_t* ns,
+                         LoadTask* task,
                          ZipArchiveCache* zip_archive_cache,
                          LoadTaskList* load_tasks,
                          int rtld_flags) {
@@ -1574,11 +1755,11 @@ static bool load_library(LoadTask* task,
 
     task->set_fd(extinfo->library_fd, false);
     task->set_file_offset(file_offset);
-    return load_library(task, load_tasks, rtld_flags, realpath);
+    return load_library(ns, task, load_tasks, rtld_flags, realpath);
   }
 
   // Open the file.
-  int fd = open_library(zip_archive_cache, name, needed_by, &file_offset, &realpath);
+  int fd = open_library(ns, zip_archive_cache, name, needed_by, &file_offset, &realpath);
   if (fd == -1) {
     DL_ERR("library \"%s\" not found", name);
     return false;
@@ -1587,14 +1768,15 @@ static bool load_library(LoadTask* task,
   task->set_fd(fd, true);
   task->set_file_offset(file_offset);
 
-  return load_library(task, load_tasks, rtld_flags, realpath);
+  return load_library(ns, task, load_tasks, rtld_flags, realpath);
 }
 
 // Returns true if library was found and false in 2 cases
-// 1. The library was found but loaded under different target_sdk_version
+// 1. (for default namespace only) The library was found but loaded under different
-//    (*candidate != nullptr)
+//    target_sdk_version (*candidate != nullptr)
 // 2. The library was not found by soname (*candidate is nullptr)
-static bool find_loaded_library_by_soname(const char* name, soinfo** candidate) {
+static bool find_loaded_library_by_soname(android_namespace_t* ns,
+                                          const char* name, soinfo** candidate) {
   *candidate = nullptr;
 
   // Ignore filename with path.
@@ -1604,7 +1786,7 @@ static bool find_loaded_library_by_soname(const char* name, soinfo** candidate)
 
   uint32_t target_sdk_version = get_application_target_sdk_version();
 
-  for (soinfo* si = solist; si != nullptr; si = si->next) {
+  return !ns->soinfo_list().visit([&](soinfo* si) {
     const char* soname = si->get_soname();
     if (soname != nullptr && (strcmp(name, soname) == 0)) {
       // If the library was opened under different target sdk version
@@ -1614,36 +1796,52 @@ static bool find_loaded_library_by_soname(const char* name, soinfo** candidate)
       // in any case.
       bool is_libdl = si == solist;
       if (is_libdl || (si->get_dt_flags_1() & DF_1_GLOBAL) != 0 ||
-          !si->is_linked() || si->get_target_sdk_version() == target_sdk_version) {
+          !si->is_linked() || si->get_target_sdk_version() == target_sdk_version ||
+          ns != &g_default_namespace) {
         *candidate = si;
-        return true;
+        return false;
       } else if (*candidate == nullptr) {
-        // for the different sdk version - remember the first library.
+        // for the different sdk version in the default namespace
+        // remember the first library.
         *candidate = si;
       }
     }
-  }
 
-  return false;
+    return true;
+  });
 }
 
-static bool find_library_internal(LoadTask* task,
+static bool find_library_internal(android_namespace_t* ns,
+                                  LoadTask* task,
                                   ZipArchiveCache* zip_archive_cache,
                                   LoadTaskList* load_tasks,
                                   int rtld_flags) {
   soinfo* candidate;
 
-  if (find_loaded_library_by_soname(task->get_name(), &candidate)) {
+  if (find_loaded_library_by_soname(ns, task->get_name(), &candidate)) {
     task->set_soinfo(candidate);
     return true;
   }
 
+  if (ns != &g_default_namespace) {
+    // check public namespace
+    candidate = g_public_namespace.find_if([&](soinfo* si) {
+      return strcmp(task->get_name(), si->get_soname()) == 0;
+    });
+
+    if (candidate != nullptr) {
+      ns->soinfo_list().push_back(candidate);
+      task->set_soinfo(candidate);
+      return true;
+    }
+  }
+
   // Library might still be loaded, the accurate detection
   // of this fact is done by load_library.
   TRACE("[ '%s' find_loaded_library_by_soname returned false (*candidate=%s@%p). Trying harder...]",
       task->get_name(), candidate == nullptr ? "n/a" : candidate->get_realpath(), candidate);
 
-  if (load_library(task, zip_archive_cache, load_tasks, rtld_flags)) {
+  if (load_library(ns, task, zip_archive_cache, load_tasks, rtld_flags)) {
     return true;
   } else {
     // In case we were unable to load the library but there
@@ -1667,13 +1865,13 @@ static void soinfo_unload(soinfo* si);
 //
 // This group consists of the main executable, LD_PRELOADs
 // and libraries with the DF_1_GLOBAL flag set.
-static soinfo::soinfo_list_t make_global_group() {
+static soinfo::soinfo_list_t make_global_group(android_namespace_t* ns) {
   soinfo::soinfo_list_t global_group;
-  for (soinfo* si = somain; si != nullptr; si = si->next) {
+  ns->soinfo_list().for_each([&](soinfo* si) {
     if ((si->get_dt_flags_1() & DF_1_GLOBAL) != 0) {
       global_group.push_back(si);
     }
-  }
+  });
 
   return global_group;
 }
@@ -1690,7 +1888,8 @@ static void shuffle(std::vector<LoadTask*>* v) {
 // not their transitive dependencies) as children of the start_with library.
 // This is false when find_libraries is called for dlopen(), when newly loaded
 // libraries must form a disjoint tree.
-static bool find_libraries(soinfo* start_with,
+static bool find_libraries(android_namespace_t* ns,
+                           soinfo* start_with,
                            const char* const library_names[],
                            size_t library_names_count, soinfo* soinfos[],
                            std::vector<soinfo*>* ld_preloads,
@@ -1707,7 +1906,7 @@ static bool find_libraries(soinfo* start_with,
   }
 
   // Construct global_group.
-  soinfo::soinfo_list_t global_group = make_global_group();
+  soinfo::soinfo_list_t global_group = make_global_group(ns);
 
   // If soinfos array is null allocate one on stack.
   // The array is needed in case of failure; for example
@@ -1749,7 +1948,7 @@ static bool find_libraries(soinfo* start_with,
     bool is_dt_needed = needed_by != nullptr && (needed_by != start_with || add_as_children);
     task->set_extinfo(is_dt_needed ? nullptr : extinfo);
 
-    if(!find_library_internal(task, &zip_archive_cache, &load_tasks, rtld_flags)) {
+    if(!find_library_internal(ns, task, &zip_archive_cache, &load_tasks, rtld_flags)) {
       return false;
     }
 
@@ -1850,14 +2049,15 @@ static bool find_libraries(soinfo* start_with,
   return linked;
 }
 
-static soinfo* find_library(const char* name, int rtld_flags,
+static soinfo* find_library(android_namespace_t* ns,
+                            const char* name, int rtld_flags,
                             const android_dlextinfo* extinfo,
                             soinfo* needed_by) {
   soinfo* si;
 
   if (name == nullptr) {
     si = somain;
-  } else if (!find_libraries(needed_by, &name, 1, &si, nullptr, 0, rtld_flags,
+  } else if (!find_libraries(ns, needed_by, &name, 1, &si, nullptr, 0, rtld_flags,
                              extinfo, /* add_as_children */ false)) {
     return nullptr;
   }
@@ -1920,7 +2120,9 @@ static void soinfo_unload(soinfo* root) {
           TRACE("deprecated (old format of soinfo): %s needs to unload %s",
               si->get_realpath(), library_name);
 
-          soinfo* needed = find_library(library_name, RTLD_NOLOAD, nullptr, nullptr);
+          soinfo* needed = find_library(si->get_namespace(),
+                                        library_name, RTLD_NOLOAD, nullptr, nullptr);
+
           if (needed != nullptr) {
             // Not found: for example if symlink was deleted between dlopen and dlclose
             // Since we cannot really handle errors at this point - print and continue.
@@ -1992,6 +2194,9 @@ soinfo* do_dlopen(const char* name, int flags, const android_dlextinfo* extinfo,
     DL_ERR("invalid flags to dlopen: %x", flags);
     return nullptr;
   }
+
+  android_namespace_t* ns = caller->get_namespace();
+
   if (extinfo != nullptr) {
     if ((extinfo->flags & ~(ANDROID_DLEXT_VALID_FLAG_BITS)) != 0) {
       DL_ERR("invalid extended flags to android_dlopen_ext: 0x%" PRIx64, extinfo->flags);
@@ -2011,13 +2216,22 @@ soinfo* do_dlopen(const char* name, int flags, const android_dlextinfo* extinfo,
              "compatible with ANDROID_DLEXT_RESERVED_ADDRESS/ANDROID_DLEXT_RESERVED_ADDRESS_HINT");
       return nullptr;
     }
+
+    if ((extinfo->flags & ANDROID_DLEXT_USE_NAMESPACE) != 0) {
+      if (extinfo->library_namespace == nullptr) {
+        DL_ERR("ANDROID_DLEXT_USE_NAMESPACE is set but extinfo->library_namespace is null");
+        return nullptr;
+      }
+      ns = extinfo->library_namespace;
+    }
   }
 
   ProtectedDataGuard guard;
-  soinfo* si = find_library(name, flags, extinfo, caller);
+  soinfo* si = find_library(ns, name, flags, extinfo, caller);
   if (si != nullptr) {
     si->call_constructors();
   }
+
   return si;
 }
 
@@ -2026,6 +2240,67 @@ void do_dlclose(soinfo* si) {
   soinfo_unload(si);
 }
 
+bool init_public_namespace(const char* libs) {
+  CHECK(libs != nullptr);
+  if (g_public_namespace_initialized) {
+    DL_ERR("Public namespace has already been initialized.");
+    return false;
+  }
+
+  std::vector<std::string> sonames = android::base::Split(libs, ":");
+
+  ProtectedDataGuard guard;
+
+  auto failure_guard = make_scope_guard([&]() {
+    g_public_namespace.clear();
+  });
+
+  soinfo* candidate;
+  for (const auto& soname : sonames) {
+    if (!find_loaded_library_by_soname(&g_default_namespace, soname.c_str(), &candidate)) {
+      DL_ERR("Error initializing public namespace: \"%s\" was not found"
+             " in the default namespace", soname.c_str());
+      return false;
+    }
+
+    candidate->set_nodelete();
+    g_public_namespace.push_back(candidate);
+  }
+
+  failure_guard.disable();
+  g_public_namespace_initialized = true;
+  return true;
+}
+
+android_namespace_t* create_namespace(const char* name,
+                                      const char* ld_library_path,
+                                      const char* default_library_path,
+                                      bool is_isolated) {
+  if (!g_public_namespace_initialized) {
+    DL_ERR("Cannot create namespace: public namespace is not initialized.");
+    return nullptr;
+  }
+
+  ProtectedDataGuard guard;
+  std::vector<std::string> ld_library_paths;
+  std::vector<std::string> default_library_paths;
+
+  parse_path(ld_library_path, ":", &ld_library_paths);
+  parse_path(default_library_path, ":", &default_library_paths);
+
+  android_namespace_t* ns = new (g_namespace_allocator.alloc()) android_namespace_t();
+  ns->set_name(name);
+  ns->set_isolated(is_isolated);
+  ns->set_ld_library_paths(std::move(ld_library_paths));
+  ns->set_default_library_paths(std::move(default_library_paths));
+
+  // TODO(dimtiry): Should this be global group of caller's namespace?
+  auto global_group = make_global_group(&g_default_namespace);
+  std::copy(global_group.begin(), global_group.end(), std::back_inserter(ns->soinfo_list()));
+
+  return ns;
+}
+
 static ElfW(Addr) call_ifunc_resolver(ElfW(Addr) resolver_addr) {
   typedef ElfW(Addr) (*ifunc_resolver_t)(void);
   ifunc_resolver_t ifunc_resolver = reinterpret_cast<ifunc_resolver_t>(resolver_addr);
@@ -2694,6 +2969,10 @@ void soinfo::set_dt_flags_1(uint32_t dt_flags_1) {
   }
 }
 
+void soinfo::set_nodelete() {
+  rtld_flags_ |= RTLD_NODELETE;
+}
+
 const char* soinfo::get_realpath() const {
 #if defined(__work_around_b_24465209__)
   if (has_min_version(2)) {
@@ -2760,13 +3039,21 @@ soinfo::soinfo_list_t& soinfo::get_parents() {
 static std::vector<std::string> g_empty_runpath;
 
 const std::vector<std::string>& soinfo::get_dt_runpath() const {
-  if (has_min_version(2)) {
+  if (has_min_version(3)) {
     return dt_runpath_;
   }
 
   return g_empty_runpath;
 }
 
+android_namespace_t* soinfo::get_namespace() {
+  if (has_min_version(3)) {
+    return namespace_;
+  }
+
+  return &g_default_namespace;
+}
+
 ElfW(Addr) soinfo::resolve_symbol_address(const ElfW(Sym)* s) const {
   if (ELF_ST_TYPE(s->st_info) == STT_GNU_IFUNC) {
     return call_ifunc_resolver(s->st_value + load_bias);
@@ -3464,7 +3751,8 @@ static soinfo* linker_soinfo_for_gdb = nullptr;
  * be on the soinfo list.
  */
 static void init_linker_info_for_gdb(ElfW(Addr) linker_base) {
-  linker_soinfo_for_gdb = new (linker_soinfo_for_gdb_buf) soinfo(LINKER_PATH, nullptr, 0, 0);
+  linker_soinfo_for_gdb = new (linker_soinfo_for_gdb_buf) soinfo(nullptr, LINKER_PATH,
+                                                                 nullptr, 0, 0);
 
   linker_soinfo_for_gdb->load_bias = linker_base;
 
@@ -3481,14 +3769,25 @@ static void init_linker_info_for_gdb(ElfW(Addr) linker_base) {
   insert_soinfo_into_debug_map(linker_soinfo_for_gdb);
 }
 
-static void init_default_ld_library_path() {
+static void init_default_namespace() {
+  g_default_namespace.set_name("(default)");
+  g_default_namespace.set_isolated(false);
+
   const char *interp = phdr_table_get_interpreter_name(somain->phdr, somain->phnum,
                                                        somain->load_bias);
   const char* bname = basename(interp);
-  if (bname && (strcmp(bname, "linker_asan") == 0 || strcmp(bname, "linker_asan64") == 0))
+  if (bname && (strcmp(bname, "linker_asan") == 0 || strcmp(bname, "linker_asan64") == 0)) {
     g_default_ld_paths = kAsanDefaultLdPaths;
-  else
+  } else {
     g_default_ld_paths = kDefaultLdPaths;
+  }
+
+  std::vector<std::string> ld_default_paths;
+  for (size_t i = 0; g_default_ld_paths[i] != nullptr; ++i) {
+    ld_default_paths.push_back(g_default_ld_paths[i]);
+  }
+
+  g_default_namespace.set_default_library_paths(std::move(ld_default_paths));
 };
 
 extern "C" int __system_properties_init(void);
@@ -3529,7 +3828,7 @@ static ElfW(Addr) __linker_init_post_relocation(KernelArgumentBlock& args, ElfW(
 
   INFO("[ android linker & debugger ]");
 
-  soinfo* si = soinfo_alloc(args.argv[0], nullptr, 0, RTLD_GLOBAL);
+  soinfo* si = soinfo_alloc(&g_default_namespace, args.argv[0], nullptr, 0, RTLD_GLOBAL);
   if (si == nullptr) {
     exit(EXIT_FAILURE);
   }
@@ -3581,11 +3880,10 @@ static ElfW(Addr) __linker_init_post_relocation(KernelArgumentBlock& args, ElfW(
 
   somain = si;
 
-  init_default_ld_library_path();
+  init_default_namespace();
 
   if (!si->prelink_image()) {
-    __libc_format_fd(2, "CANNOT LINK EXECUTABLE: %s\n", linker_get_error_buffer());
+    __libc_fatal("CANNOT LINK EXECUTABLE: %s", linker_get_error_buffer());
-    exit(EXIT_FAILURE);
   }
 
   // add somain to global group
@@ -3613,15 +3911,13 @@ static ElfW(Addr) __linker_init_post_relocation(KernelArgumentBlock& args, ElfW(
   needed_library_name_list.copy_to_array(needed_library_names, needed_libraries_count);
 
   if (needed_libraries_count > 0 &&
-      !find_libraries(si, needed_library_names, needed_libraries_count, nullptr,
+      !find_libraries(&g_default_namespace, si, needed_library_names, needed_libraries_count,
-                      &g_ld_preloads, ld_preloads_count, RTLD_GLOBAL, nullptr,
+                      nullptr, &g_ld_preloads, ld_preloads_count, RTLD_GLOBAL, nullptr,
                       /* add_as_children */ true)) {
-    __libc_format_fd(2, "CANNOT LINK EXECUTABLE: %s\n", linker_get_error_buffer());
+    __libc_fatal("CANNOT LINK EXECUTABLE: %s", linker_get_error_buffer());
-    exit(EXIT_FAILURE);
   } else if (needed_libraries_count == 0) {
     if (!si->link_image(g_empty_list, soinfo::soinfo_list_t::make_list(si), nullptr)) {
-      __libc_format_fd(2, "CANNOT LINK EXECUTABLE: %s\n", linker_get_error_buffer());
+      __libc_fatal("CANNOT LINK EXECUTABLE: %s", linker_get_error_buffer());
-      exit(EXIT_FAILURE);
     }
     si->increment_ref_count();
   }
@@ -3730,7 +4026,7 @@ extern "C" ElfW(Addr) __linker_init(void* raw_args) {
   ElfW(Ehdr)* elf_hdr = reinterpret_cast<ElfW(Ehdr)*>(linker_addr);
   ElfW(Phdr)* phdr = reinterpret_cast<ElfW(Phdr)*>(linker_addr + elf_hdr->e_phoff);
 
-  soinfo linker_so(nullptr, nullptr, 0, 0);
+  soinfo linker_so(nullptr, nullptr, nullptr, 0, 0);
 
   // If the linker is not acting as PT_INTERP entry_point is equal to
   // _start. Which means that the linker is running as an executable and
@@ -3739,7 +4035,7 @@ extern "C" ElfW(Addr) __linker_init(void* raw_args) {
   // This happens when user tries to run 'adb shell /system/bin/linker'
   // see also https://code.google.com/p/android/issues/detail?id=63174
   if (reinterpret_cast<ElfW(Addr)>(&_start) == entry_point) {
-    __libc_fatal("This is %s, the helper program for shared library executables.\n", args.argv[0]);
+    __libc_fatal("This is %s, the helper program for shared library executables.", args.argv[0]);
   }
 
   linker_so.base = linker_addr;
@@ -3757,15 +4053,7 @@ extern "C" ElfW(Addr) __linker_init(void* raw_args) {
   // are not yet initialized, and therefore we cannot use linked_list.push_*
   // functions at this point.
   if (!(linker_so.prelink_image() && linker_so.link_image(g_empty_list, g_empty_list, nullptr))) {
-    // It would be nice to print an error message, but if the linker
+    __libc_fatal("CANNOT LINK EXECUTABLE: %s", linker_get_error_buffer());
-    // can't link itself, there's no guarantee that we'll be able to
-    // call write() (because it involves a GOT reference). We may as
-    // well try though...
-    const char* msg = "CANNOT LINK EXECUTABLE: ";
-    write(2, msg, strlen(msg));
-    write(2, __linker_dl_err_buf, strlen(__linker_dl_err_buf));
-    write(2, "\n", 1);
-    _exit(EXIT_FAILURE);
   }
 
   __libc_init_main_thread(args);
@@ -3781,6 +4069,7 @@ extern "C" ElfW(Addr) __linker_init(void* raw_args) {
   // before get_libdl_info().
   solist = get_libdl_info();
   sonext = get_libdl_info();
+  g_default_namespace.soinfo_list().push_back(get_libdl_info());
 
   // We have successfully fixed our own relocations. It's safe to run
   // the main part of the linker now.

linker/linker.h

@@ -86,7 +86,7 @@
 
 #define SUPPORTED_DT_FLAGS_1 (DF_1_NOW | DF_1_GLOBAL | DF_1_NODELETE)
 
-#define SOINFO_VERSION 2
+#define SOINFO_VERSION 3
 
 #if defined(__work_around_b_24465209__)
 #define SOINFO_NAME_LEN 128
@@ -261,7 +261,8 @@ struct soinfo {
   bool has_DT_SYMBOLIC;
 
  public:
-  soinfo(const char* name, const struct stat* file_stat, off64_t file_offset, int rtld_flags);
+  soinfo(android_namespace_t* ns, const char* name, const struct stat* file_stat,
+         off64_t file_offset, int rtld_flags);
 
   void call_constructors();
   void call_destructors();
@@ -311,6 +312,7 @@ struct soinfo {
   void set_linked();
   void set_linker_flag();
   void set_main_executable();
+  void set_nodelete();
 
   void increment_ref_count();
   size_t decrement_ref_count();
@@ -332,6 +334,7 @@ struct soinfo {
 
   void set_dt_runpath(const char *);
   const std::vector<std::string>& get_dt_runpath() const;
+  android_namespace_t* get_namespace();
 
  private:
   bool elf_lookup(SymbolName& symbol_name, const version_info* vi, uint32_t* symbol_index) const;
@@ -394,7 +397,9 @@ struct soinfo {
 
   uint32_t target_sdk_version_;
 
+  // version >= 3
   std::vector<std::string> dt_runpath_;
+  android_namespace_t* namespace_;
 
   friend soinfo* get_libdl_info();
 };
@@ -422,7 +427,9 @@ void do_dlclose(soinfo* si);
 
 int do_dl_iterate_phdr(int (*cb)(dl_phdr_info* info, size_t size, void* data), void* data);
 
-const ElfW(Sym)* dlsym_linear_lookup(const char* name, soinfo** found, soinfo* caller, void* handle);
+const ElfW(Sym)* dlsym_linear_lookup(android_namespace_t* ns, const char* name, soinfo** found,
+                                     soinfo* caller, void* handle);
+
 soinfo* find_containing_library(const void* addr);
 
 const ElfW(Sym)* dlsym_handle_lookup(soinfo* si, soinfo** found, const char* name);
@@ -437,4 +444,8 @@ size_t linker_get_error_buffer_size();
 void set_application_target_sdk_version(uint32_t target);
 uint32_t get_application_target_sdk_version();
 
+bool init_public_namespace(const char* path);
+android_namespace_t* create_namespace(const char* name, const char* ld_library_path,
+                                      const char* default_library_path, bool is_isolated);
+
 #endif

linker/linker_utils.cpp

@@ -20,7 +20,7 @@
 bool normalize_path(const char* path, std::string* normalized_path) {
   // Input should be an absolute path
   if (path[0] != '/') {
-    PRINT("canonize_path - invalid input: '%s', the input path should be absolute", path);
+    PRINT("normalize_path - invalid input: '%s', the input path should be absolute", path);
     return false;
   }
 
@@ -61,3 +61,47 @@ bool normalize_path(const char* path, std::string* normalized_path) {
   return true;
 }
 
+bool file_is_in_dir(const std::string& file, const std::string& dir) {
+  const char* needle = dir.c_str();
+  const char* haystack = file.c_str();
+  size_t needle_len = strlen(needle);
+
+  return (strncmp(haystack, needle, needle_len) == 0 &&
+          haystack[needle_len] == '/' &&
+          strchr(haystack + needle_len + 1, '/') == nullptr);
+}
+
+const char* const kZipFileSeparator = "!/";
+
+bool parse_zip_path(const char* input_path, std::string* zip_path, std::string* entry_path) {
+  std::string normalized_path;
+  if (!normalize_path(input_path, &normalized_path)) {
+    return false;
+  }
+
+  const char* const path = normalized_path.c_str();
+  TRACE("Trying zip file open from path '%s' -> normalized '%s'", input_path, path);
+
+  // Treat an '!/' separator inside a path as the separator between the name
+  // of the zip file on disk and the subdirectory to search within it.
+  // For example, if path is "foo.zip!/bar/bas/x.so", then we search for
+  // "bar/bas/x.so" within "foo.zip".
+  const char* const separator = strstr(path, kZipFileSeparator);
+  if (separator == nullptr) {
+    return false;
+  }
+
+  char buf[512];
+  if (strlcpy(buf, path, sizeof(buf)) >= sizeof(buf)) {
+    PRINT("Warning: ignoring very long library path: %s", path);
+    return false;
+  }
+
+  buf[separator - path] = '\0';
+
+  *zip_path = buf;
+  *entry_path = &buf[separator - path + 2];
+
+  return true;
+}
+

linker/linker_utils.h

@@ -18,6 +18,10 @@
 
 #include <string>
 
+extern const char* const kZipFileSeparator;
+
 bool normalize_path(const char* path, std::string* normalized_path);
+bool file_is_in_dir(const std::string& file, const std::string& dir);
+bool parse_zip_path(const char* input_path, std::string* zip_path, std::string* entry_path);
 
 #endif

linker/tests/linker_utils_test.cpp

@@ -43,3 +43,29 @@ TEST(linker_utils, normalize_path_smoke) {
   ASSERT_FALSE(normalize_path("root///dir/.///dir2/somedir/../zipfile!/dir/dir9//..///afile", &output));
   ASSERT_EQ("unchanged", output);
 }
+
+TEST(linker_utils, file_is_in_dir_smoke) {
+  ASSERT_TRUE(file_is_in_dir("/foo/bar/file", "/foo/bar"));
+  ASSERT_FALSE(file_is_in_dir("/foo/bar/file", "/foo"));
+
+  ASSERT_FALSE(file_is_in_dir("/foo/bar/file", "/bar/foo"));
+
+  ASSERT_TRUE(file_is_in_dir("/file", ""));
+  ASSERT_FALSE(file_is_in_dir("/file", "/"));
+}
+
+TEST(linker_utils, parse_zip_path_smoke) {
+  std::string zip_path;
+  std::string entry_path;
+
+  ASSERT_FALSE(parse_zip_path("/not/a/zip/path/file.zip", &zip_path, &entry_path));
+  ASSERT_FALSE(parse_zip_path("/not/a/zip/path/file.zip!path/in/zip", &zip_path, &entry_path));
+  ASSERT_TRUE(parse_zip_path("/zip/path/file.zip!/path/in/zip", &zip_path, &entry_path));
+  ASSERT_EQ("/zip/path/file.zip", zip_path);
+  ASSERT_EQ("path/in/zip", entry_path);
+
+  ASSERT_TRUE(parse_zip_path("/zip/path/file2.zip!/", &zip_path, &entry_path));
+  ASSERT_EQ("/zip/path/file2.zip", zip_path);
+  ASSERT_EQ("", entry_path);
+}
+

tests/Android.build.mk

@@ -28,9 +28,17 @@ ifneq ($(findstring LIBRARY, $(build_target)),LIBRARY)
     LOCAL_MODULE_STEM_32 := $(module)32
     LOCAL_MODULE_STEM_64 := $(module)64
 else
+
+ifneq ($($(module)_install_to_out_data_dir),)
+  $(module)_install_to_out_data := true
+endif
+
 ifeq ($($(module)_install_to_out_data),true)
-    LOCAL_MODULE_PATH_32 := $($(TARGET_2ND_ARCH_VAR_PREFIX)TARGET_OUT_DATA_NATIVE_TESTS)/$(module)
+    ifeq ($($(module)_install_to_out_data_dir),)
-    LOCAL_MODULE_PATH_64 := $(TARGET_OUT_DATA_NATIVE_TESTS)/$(module)
+      $(module)_install_to_out_data_dir := $(module)
+    endif
+    LOCAL_MODULE_PATH_32 := $($(TARGET_2ND_ARCH_VAR_PREFIX)TARGET_OUT_DATA_NATIVE_TESTS)/$($(module)_install_to_out_data_dir)
+    LOCAL_MODULE_PATH_64 := $(TARGET_OUT_DATA_NATIVE_TESTS)/$($(module)_install_to_out_data_dir)
 endif
 endif
 

tests/dlext_test.cpp

@@ -52,14 +52,14 @@ typedef int (*fn)(void);
 #define LIBSIZE 1024*1024 // how much address space to reserve for it
 
 #if defined(__LP64__)
-#define LIBPATH_PREFIX "/nativetest64/"
+#define NATIVE_TESTS_PATH "/nativetest64"
 #else
-#define LIBPATH_PREFIX "/nativetest/"
+#define NATIVE_TESTS_PATH "/nativetest"
 #endif
 
-#define LIBPATH LIBPATH_PREFIX "libdlext_test_fd/libdlext_test_fd.so"
+#define LIBPATH NATIVE_TESTS_PATH "/libdlext_test_fd/libdlext_test_fd.so"
-#define LIBZIPPATH LIBPATH_PREFIX "libdlext_test_zip/libdlext_test_zip_zipaligned.zip"
+#define LIBZIPPATH NATIVE_TESTS_PATH "/libdlext_test_zip/libdlext_test_zip_zipaligned.zip"
-#define LIBZIPPATH_WITH_RUNPATH LIBPATH_PREFIX "libdlext_test_runpath_zip/libdlext_test_runpath_zip_zipaligned.zip"
+#define LIBZIPPATH_WITH_RUNPATH NATIVE_TESTS_PATH "/libdlext_test_runpath_zip/libdlext_test_runpath_zip_zipaligned.zip"
 
 #define LIBZIP_OFFSET PAGE_SIZE
 
@@ -602,3 +602,192 @@ void DlExtRelroSharingTest::SpawnChildrenAndMeasurePss(const char* lib, bool sha
     ASSERT_EQ(0, WEXITSTATUS(status));
   }
 }
+
+// Testing namespaces
+static const char* g_public_lib = "libnstest_public.so";
+
+TEST(dlext, ns_smoke) {
+  static const char* root_lib = "libnstest_root.so";
+  std::string path = std::string("libc.so:libc++.so:libdl.so:libm.so:") + g_public_lib;
+
+  ASSERT_FALSE(android_init_public_namespace(path.c_str()));
+  ASSERT_STREQ("android_init_public_namespace failed: Error initializing public namespace: "
+               "\"libnstest_public.so\" was not found in the default namespace", dlerror());
+
+  const std::string lib_path = std::string(getenv("ANDROID_DATA")) + NATIVE_TESTS_PATH;
+
+  void* handle_public = dlopen((lib_path + "/public_namespace_libs/" + g_public_lib).c_str(), RTLD_NOW);
+  ASSERT_TRUE(handle_public != nullptr) << dlerror();
+
+  ASSERT_TRUE(android_init_public_namespace(path.c_str())) << dlerror();
+
+  // Check that libraries added to public namespace are NODELETE
+  dlclose(handle_public);
+  handle_public = dlopen((lib_path + "/public_namespace_libs/" + g_public_lib).c_str(), RTLD_NOW | RTLD_NOLOAD);
+  ASSERT_TRUE(handle_public != nullptr) << dlerror();
+
+  android_namespace_t* ns1 = android_create_namespace("private", nullptr, (lib_path + "/private_namespace_libs").c_str(), false);
+  ASSERT_TRUE(ns1 != nullptr) << dlerror();
+
+  android_namespace_t* ns2 = android_create_namespace("private_isolated", nullptr, (lib_path + "/private_namespace_libs").c_str(), true);
+  ASSERT_TRUE(ns2 != nullptr) << dlerror();
+
+  // This should not have affect search path for default namespace:
+  ASSERT_TRUE(dlopen(root_lib, RTLD_NOW) == nullptr);
+  void* handle = dlopen(g_public_lib, RTLD_NOW);
+  ASSERT_TRUE(handle != nullptr) << dlerror();
+  dlclose(handle);
+
+  android_dlextinfo extinfo;
+  extinfo.flags = ANDROID_DLEXT_USE_NAMESPACE;
+  extinfo.library_namespace = ns1;
+
+  void* handle1 = android_dlopen_ext(root_lib, RTLD_NOW, &extinfo);
+  ASSERT_TRUE(handle1 != nullptr) << dlerror();
+
+  extinfo.library_namespace = ns2;
+  void* handle2 = android_dlopen_ext(root_lib, RTLD_NOW, &extinfo);
+  ASSERT_TRUE(handle2 != nullptr) << dlerror();
+
+  ASSERT_TRUE(handle1 != handle2);
+
+  typedef const char* (*fn_t)();
+
+  fn_t ns_get_local_string1 = reinterpret_cast<fn_t>(dlsym(handle1, "ns_get_local_string"));
+  ASSERT_TRUE(ns_get_local_string1 != nullptr) << dlerror();
+  fn_t ns_get_local_string2 = reinterpret_cast<fn_t>(dlsym(handle2, "ns_get_local_string"));
+  ASSERT_TRUE(ns_get_local_string2 != nullptr) << dlerror();
+
+  EXPECT_STREQ("This string is local to root library", ns_get_local_string1());
+  EXPECT_STREQ("This string is local to root library", ns_get_local_string2());
+
+  ASSERT_TRUE(ns_get_local_string1() != ns_get_local_string2());
+
+  fn_t ns_get_private_extern_string1 =
+          reinterpret_cast<fn_t>(dlsym(handle1, "ns_get_private_extern_string"));
+  ASSERT_TRUE(ns_get_private_extern_string1 != nullptr) << dlerror();
+  fn_t ns_get_private_extern_string2 =
+          reinterpret_cast<fn_t>(dlsym(handle2, "ns_get_private_extern_string"));
+  ASSERT_TRUE(ns_get_private_extern_string2 != nullptr) << dlerror();
+
+  EXPECT_STREQ("This string is from private namespace", ns_get_private_extern_string1());
+  EXPECT_STREQ("This string is from private namespace", ns_get_private_extern_string2());
+
+  ASSERT_TRUE(ns_get_private_extern_string1() != ns_get_private_extern_string2());
+
+  fn_t ns_get_public_extern_string1 =
+          reinterpret_cast<fn_t>(dlsym(handle1, "ns_get_public_extern_string"));
+  ASSERT_TRUE(ns_get_public_extern_string1 != nullptr) << dlerror();
+  fn_t ns_get_public_extern_string2 =
+          reinterpret_cast<fn_t>(dlsym(handle2, "ns_get_public_extern_string"));
+  ASSERT_TRUE(ns_get_public_extern_string2 != nullptr) << dlerror();
+
+  EXPECT_STREQ("This string is from public namespace", ns_get_public_extern_string1());
+  ASSERT_TRUE(ns_get_public_extern_string1() == ns_get_public_extern_string2());
+
+  // and now check that dlopen() does the right thing in terms of preserving namespace
+  fn_t ns_get_dlopened_string1 = reinterpret_cast<fn_t>(dlsym(handle1, "ns_get_dlopened_string"));
+  ASSERT_TRUE(ns_get_dlopened_string1 != nullptr) << dlerror();
+  fn_t ns_get_dlopened_string2 = reinterpret_cast<fn_t>(dlsym(handle2, "ns_get_dlopened_string"));
+  ASSERT_TRUE(ns_get_dlopened_string2 != nullptr) << dlerror();
+
+  EXPECT_STREQ("This string is from private namespace (dlopened library)", ns_get_dlopened_string1());
+  EXPECT_STREQ("This string is from private namespace (dlopened library)", ns_get_dlopened_string2());
+
+  ASSERT_TRUE(ns_get_dlopened_string1() != ns_get_dlopened_string2());
+
+  dlclose(handle1);
+
+  // Check if handle2 is still alive (and well)
+  ASSERT_STREQ("This string is local to root library", ns_get_local_string2());
+  ASSERT_STREQ("This string is from private namespace", ns_get_private_extern_string2());
+  ASSERT_STREQ("This string is from public namespace", ns_get_public_extern_string2());
+  ASSERT_STREQ("This string is from private namespace (dlopened library)", ns_get_dlopened_string2());
+
+  dlclose(handle2);
+}
+
+TEST(dlext, ns_isolated) {
+  static const char* root_lib = "libnstest_root_not_isolated.so";
+  std::string path = std::string("libc.so:libc++.so:libdl.so:libm.so:") + g_public_lib;
+
+  const std::string lib_path = std::string(getenv("ANDROID_DATA")) + NATIVE_TESTS_PATH;
+  void* handle_public = dlopen((lib_path + "/public_namespace_libs/" + g_public_lib).c_str(), RTLD_NOW);
+  ASSERT_TRUE(handle_public != nullptr) << dlerror();
+
+  ASSERT_TRUE(android_init_public_namespace(path.c_str())) << dlerror();
+
+  android_namespace_t* ns_not_isolated = android_create_namespace("private", nullptr, (lib_path + "/private_namespace_libs").c_str(), false);
+  ASSERT_TRUE(ns_not_isolated != nullptr) << dlerror();
+
+  android_namespace_t* ns_isolated = android_create_namespace("private_isolated1", nullptr, (lib_path + "/private_namespace_libs").c_str(), true);
+  ASSERT_TRUE(ns_isolated != nullptr) << dlerror();
+
+  android_namespace_t* ns_isolated2 = android_create_namespace("private_isolated2", (lib_path + "/private_namespace_libs").c_str(), nullptr, true);
+  ASSERT_TRUE(ns_isolated2 != nullptr) << dlerror();
+
+  ASSERT_TRUE(dlopen(root_lib, RTLD_NOW) == nullptr);
+  ASSERT_STREQ("dlopen failed: library \"libnstest_root_not_isolated.so\" not found", dlerror());
+
+  std::string lib_private_external_path =
+      lib_path + "/private_namespace_libs_external/libnstest_private_external.so";
+
+  // Load lib_private_external_path to default namespace
+  // (it should remain invisible for the isolated namespaces after this)
+  void* handle = dlopen(lib_private_external_path.c_str(), RTLD_NOW);
+  ASSERT_TRUE(handle != nullptr) << dlerror();
+
+  android_dlextinfo extinfo;
+  extinfo.flags = ANDROID_DLEXT_USE_NAMESPACE;
+  extinfo.library_namespace = ns_not_isolated;
+
+  void* handle1 = android_dlopen_ext(root_lib, RTLD_NOW, &extinfo);
+  ASSERT_TRUE(handle1 != nullptr) << dlerror();
+
+  extinfo.library_namespace = ns_isolated;
+
+  void* handle2 = android_dlopen_ext(root_lib, RTLD_NOW, &extinfo);
+  ASSERT_TRUE(handle2 == nullptr);
+  ASSERT_STREQ("dlopen failed: library \"libnstest_private_external.so\" not found", dlerror());
+
+  // Check dlopen by absolute path
+  handle2 = android_dlopen_ext(lib_private_external_path.c_str(), RTLD_NOW, &extinfo);
+  ASSERT_TRUE(handle2 == nullptr);
+  ASSERT_EQ("dlopen failed: library \"" + lib_private_external_path + "\" not found", dlerror());
+
+  extinfo.library_namespace = ns_isolated2;
+
+  handle2 = android_dlopen_ext(root_lib, RTLD_NOW, &extinfo);
+  ASSERT_TRUE(handle2 == nullptr);
+  ASSERT_STREQ("dlopen failed: library \"libnstest_private_external.so\" not found", dlerror());
+
+  // Check dlopen by absolute path
+  handle2 = android_dlopen_ext(lib_private_external_path.c_str(), RTLD_NOW, &extinfo);
+  ASSERT_TRUE(handle2 == nullptr);
+  ASSERT_EQ("dlopen failed: library \"" + lib_private_external_path + "\" not found", dlerror());
+
+  typedef const char* (*fn_t)();
+  fn_t ns_get_local_string = reinterpret_cast<fn_t>(dlsym(handle1, "ns_get_local_string"));
+  ASSERT_TRUE(ns_get_local_string != nullptr) << dlerror();
+
+  ASSERT_STREQ("This string is local to root library", ns_get_local_string());
+
+  fn_t ns_get_private_extern_string =
+          reinterpret_cast<fn_t>(dlsym(handle1, "ns_get_private_extern_string"));
+  ASSERT_TRUE(ns_get_private_extern_string != nullptr) << dlerror();
+
+  ASSERT_STREQ("This string is from private namespace", ns_get_private_extern_string());
+
+  fn_t ns_get_public_extern_string =
+          reinterpret_cast<fn_t>(dlsym(handle1, "ns_get_public_extern_string"));
+  ASSERT_TRUE(ns_get_public_extern_string != nullptr) << dlerror();
+
+  ASSERT_STREQ("This string is from public namespace", ns_get_public_extern_string());
+
+  fn_t ns_get_dlopened_string = reinterpret_cast<fn_t>(dlsym(handle1, "ns_get_dlopened_string"));
+  ASSERT_TRUE(ns_get_dlopened_string != nullptr) << dlerror();
+
+  ASSERT_STREQ("This string is from private namespace (dlopened library)", ns_get_dlopened_string());
+
+  dlclose(handle1);
+}

tests/libs/Android.build.linker_namespaces.mk

@@ -0,0 +1,84 @@
+#
+# Copyright (C) 2015 The Android Open Source Project
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+# -----------------------------------------------------------------------------
+# This set of libraries are used to verify linker namespaces.
+# -----------------------------------------------------------------------------
+
+# -----------------------------------------------------------------------------
+# Test cases
+# 1. Check that private libraries loaded in different namespaces are
+#    different. Check that dlsym does not confuse them.
+# 2. Check that public libraries loaded in different namespaces are shared
+#    between them.
+# 3. Check that namespace sticks on dlopen
+#
+# Dependency tree (visibility)
+# libnstest_root.so (this should be local to the namespace)
+# +-> libnstest_public.so
+# +-> libnstest_private.so
+#
+# libnstest_dlopened.so (library in private namespace dlopened from libnstest_root.so)
+# -----------------------------------------------------------------------------
+libnstest_root_src_files := namespaces_root.cpp
+libnstest_root_shared_libraries := libnstest_public libnstest_private
+libnstest_root_install_to_out_data_dir := private_namespace_libs
+module := libnstest_root
+include $(LOCAL_PATH)/Android.build.target.testlib.mk
+
+libnstest_public_src_files := namespaces_public.cpp
+module := libnstest_public
+libnstest_public_install_to_out_data_dir := public_namespace_libs
+include $(LOCAL_PATH)/Android.build.target.testlib.mk
+
+libnstest_private_src_files := namespaces_private.cpp
+libnstest_private_install_to_out_data_dir := private_namespace_libs
+module := libnstest_private
+include $(LOCAL_PATH)/Android.build.target.testlib.mk
+
+libnstest_dlopened_src_files := namespaces_dlopened.cpp
+libnstest_dlopened_install_to_out_data_dir := private_namespace_libs
+module := libnstest_dlopened
+include $(LOCAL_PATH)/Android.build.target.testlib.mk
+
+# -----------------------------------------------------------------------------
+# This set of libraries is to test isolated namespaces
+#
+# Isolated namespaces do not allow loading of the library outside of
+# the search paths.
+#
+# This library cannot be loaded in isolated namespace because one of DT_NEEDED
+# libraries is outside of the search paths.
+#
+# libnstest_root_not_isolated.so (DT_RUNPATH = $ORIGIN/../private_namespace_libs_external/)
+# +-> libnstest_public.so
+# +-> libnstest_private_external.so (located in $ORIGIN/../private_namespace_libs_external/)
+#
+# Search path: $NATIVE_TESTS/private_namespace_libs/
+# -----------------------------------------------------------------------------
+libnstest_root_not_isolated_src_files := namespaces_root.cpp
+libnstest_root_not_isolated_shared_libraries := libnstest_public libnstest_private_external
+libnstest_root_not_isolated_install_to_out_data_dir := private_namespace_libs
+libnstest_root_not_isolated_ldflags := -Wl,--rpath,\$$ORIGIN/../private_namespace_libs_external \
+                                       -Wl,--enable-new-dtags
+
+module := libnstest_root_not_isolated
+include $(LOCAL_PATH)/Android.build.target.testlib.mk
+
+libnstest_private_external_src_files := namespaces_private.cpp
+libnstest_private_external_install_to_out_data_dir := private_namespace_libs_external
+module := libnstest_private_external
+include $(LOCAL_PATH)/Android.build.target.testlib.mk

tests/libs/Android.build.target.testlib.mk

@@ -0,0 +1,20 @@
+#
+# Copyright (C) 2015 The Android Open Source Project
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+build_target := SHARED_LIBRARY
+build_type := target
+include $(TEST_PATH)/Android.build.mk
+

tests/libs/Android.mk

@@ -26,6 +26,7 @@ common_additional_dependencies := \
     $(LOCAL_PATH)/Android.build.dlopen_check_order_dlsym.mk \
     $(LOCAL_PATH)/Android.build.dlopen_check_order_reloc_siblings.mk \
     $(LOCAL_PATH)/Android.build.dlopen_check_order_reloc_main_executable.mk \
+    $(LOCAL_PATH)/Android.build.linker_namespaces.mk \
     $(LOCAL_PATH)/Android.build.pthread_atfork.mk \
     $(LOCAL_PATH)/Android.build.testlib.mk \
     $(LOCAL_PATH)/Android.build.versioned_lib.mk \
@@ -212,6 +213,11 @@ libtest_nodelete_dt_flags_1_ldflags := -Wl,-z,nodelete
 module := libtest_nodelete_dt_flags_1
 include $(LOCAL_PATH)/Android.build.testlib.mk
 
+# -----------------------------------------------------------------------------
+# Build test helper libraries for linker namespaces
+# -----------------------------------------------------------------------------
+include $(LOCAL_PATH)/Android.build.linker_namespaces.mk
+
 # -----------------------------------------------------------------------------
 # Build DT_RUNPATH test helper libraries
 # -----------------------------------------------------------------------------

tests/libs/namespaces_dlopened.cpp

@@ -0,0 +1,19 @@
+/*
+ * Copyright (C) 2015 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+const char* g_private_dlopened_string = "This string is from private namespace "
+                                        "(dlopened library)";
+

tests/libs/namespaces_private.cpp

@@ -0,0 +1,18 @@
+/*
+ * Copyright (C) 2015 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+const char* g_private_extern_string = "This string is from private namespace";
+

tests/libs/namespaces_public.cpp

@@ -0,0 +1,18 @@
+/*
+ * Copyright (C) 2015 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+const char* g_public_extern_string = "This string is from public namespace";
+

tests/libs/namespaces_root.cpp

@@ -0,0 +1,49 @@
+/*
+ * Copyright (C) 2015 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <dlfcn.h>
+
+static const char* g_local_string = "This string is local to root library";
+extern "C" const char* g_private_extern_string;
+extern "C" const char* g_public_extern_string;
+
+bool g_dlopened = false;
+
+extern "C" const char* ns_get_local_string() {
+  return g_local_string;
+}
+
+extern "C" const char* ns_get_private_extern_string() {
+  return g_private_extern_string;
+}
+
+extern "C" const char* ns_get_public_extern_string() {
+  return g_public_extern_string;
+}
+
+extern "C" const char* ns_get_dlopened_string() {
+  void* handle = dlopen("libnstest_dlopened.so", RTLD_NOW | RTLD_GLOBAL);
+  if (handle == nullptr) {
+    return nullptr;
+  }
+
+  const char* result = *static_cast<const char**>(dlsym(handle, "g_private_dlopened_string"));
+  if (result != nullptr) {
+    g_dlopened = true;
+  }
+
+  return result;
+}