linker: allow using reserved space for multiple libraries.
Introduce a new flag ANDROID_DLEXT_RESERVED_ADDRESS_RECURSIVE which
instructs the linker to use the reserved address space to load all of
the newly-loaded libraries required by a dlopen() call instead of only
the main library. They will be loaded consecutively into that region if
they fit. The RELRO sections of all the loaded libraries will also be
considered for reading/writing shared RELRO data.
This will allow the WebView implementation to potentially consist of
more than one .so file while still benefiting from the RELRO sharing
optimisation, which would otherwise only apply to the "root" .so file.
Test: bionic-unit-tests (existing and newly added)
Bug: 110790153
Change-Id: I61da775c29fd5017d9a1e2b6b3757c3d20a355b3
diff --git a/tests/dlext_test.cpp b/tests/dlext_test.cpp
index c9ecd2e..edeb4b1 100644
--- a/tests/dlext_test.cpp
+++ b/tests/dlext_test.cpp
@@ -37,6 +37,7 @@
#include <sys/wait.h>
#include <meminfo/procmeminfo.h>
+#include <procinfo/process_map.h>
#include <ziparchive/zip_archive.h>
#include "gtest_globals.h"
@@ -59,6 +60,7 @@
typedef int (*fn)(void);
constexpr const char* kLibName = "libdlext_test.so";
+constexpr const char* kLibNameRecursive = "libdlext_test_recursive.so";
constexpr const char* kLibNameNoRelro = "libdlext_test_norelro.so";
constexpr const char* kLibZipSimpleZip = "libdir/libatest_simple_zip.so";
constexpr auto kLibSize = 1024 * 1024; // how much address space to reserve for it
@@ -332,6 +334,48 @@
EXPECT_EQ(nullptr, handle_);
}
+TEST_F(DlExtTest, ReservedRecursive) {
+ void* start = mmap(nullptr, kLibSize, PROT_NONE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+ ASSERT_TRUE(start != MAP_FAILED);
+ android_dlextinfo extinfo;
+ extinfo.flags = ANDROID_DLEXT_RESERVED_ADDRESS | ANDROID_DLEXT_RESERVED_ADDRESS_RECURSIVE;
+ extinfo.reserved_addr = start;
+ extinfo.reserved_size = kLibSize;
+ handle_ = android_dlopen_ext(kLibNameRecursive, RTLD_NOW, &extinfo);
+ ASSERT_DL_NOTNULL(handle_);
+
+ fn f = reinterpret_cast<fn>(dlsym(handle_, "getRandomNumber"));
+ ASSERT_DL_NOTNULL(f);
+ EXPECT_GE(reinterpret_cast<void*>(f), start);
+ EXPECT_LT(reinterpret_cast<void*>(f),
+ reinterpret_cast<char*>(start) + kLibSize);
+ EXPECT_EQ(4, f());
+
+ f = reinterpret_cast<fn>(dlsym(handle_, "getBiggerRandomNumber"));
+ ASSERT_DL_NOTNULL(f);
+ EXPECT_GE(reinterpret_cast<void*>(f), start);
+ EXPECT_LT(reinterpret_cast<void*>(f),
+ reinterpret_cast<char*>(start) + kLibSize);
+ EXPECT_EQ(8, f());
+
+ uint32_t* taxicab_number = reinterpret_cast<uint32_t*>(dlsym(handle_, "dlopen_testlib_taxicab_number"));
+ ASSERT_DL_NOTNULL(taxicab_number);
+ EXPECT_GE(reinterpret_cast<void*>(taxicab_number), start);
+ EXPECT_LT(reinterpret_cast<void*>(taxicab_number), reinterpret_cast<char*>(start) + kLibSize);
+ EXPECT_EQ(1729U, *taxicab_number);
+}
+
+TEST_F(DlExtTest, ReservedRecursiveTooSmall) {
+ void* start = mmap(nullptr, kLibSize/2, PROT_NONE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+ ASSERT_TRUE(start != MAP_FAILED);
+ android_dlextinfo extinfo;
+ extinfo.flags = ANDROID_DLEXT_RESERVED_ADDRESS | ANDROID_DLEXT_RESERVED_ADDRESS_RECURSIVE;
+ extinfo.reserved_addr = start;
+ extinfo.reserved_size = kLibSize/2;
+ handle_ = android_dlopen_ext(kLibNameRecursive, RTLD_NOW, &extinfo);
+ EXPECT_EQ(nullptr, handle_);
+}
+
TEST_F(DlExtTest, ReservedHint) {
void* start = mmap(nullptr, kLibSize, PROT_NONE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
ASSERT_TRUE(start != MAP_FAILED);
@@ -382,10 +426,14 @@
DlExtTest::TearDown();
}
- void CreateRelroFile(const char* lib, const char* relro_file) {
+ void CreateRelroFile(const char* lib, const char* relro_file, bool recursive) {
int relro_fd = open(relro_file, O_RDWR | O_TRUNC | O_CLOEXEC);
ASSERT_NOERROR(relro_fd);
+ if (recursive) {
+ extinfo_.flags |= ANDROID_DLEXT_RESERVED_ADDRESS_RECURSIVE;
+ }
+
pid_t pid = fork();
if (pid == 0) {
// child process
@@ -411,13 +459,19 @@
extinfo_.relro_fd = relro_fd;
}
- void TryUsingRelro(const char* lib) {
+ void TryUsingRelro(const char* lib, bool recursive) {
handle_ = android_dlopen_ext(lib, RTLD_NOW, &extinfo_);
ASSERT_DL_NOTNULL(handle_);
fn f = reinterpret_cast<fn>(dlsym(handle_, "getRandomNumber"));
ASSERT_DL_NOTNULL(f);
EXPECT_EQ(4, f());
+ if (recursive) {
+ fn f = reinterpret_cast<fn>(dlsym(handle_, "getBiggerRandomNumber"));
+ ASSERT_DL_NOTNULL(f);
+ EXPECT_EQ(8, f());
+ }
+
uint32_t* taxicab_number =
reinterpret_cast<uint32_t*>(dlsym(handle_, "dlopen_testlib_taxicab_number"));
ASSERT_DL_NOTNULL(taxicab_number);
@@ -427,6 +481,8 @@
void SpawnChildrenAndMeasurePss(const char* lib, const char* relro_file, bool share_relro,
size_t* pss_out);
+ std::string FindMappingName(void* ptr);
+
android_dlextinfo extinfo_;
};
@@ -434,8 +490,29 @@
TemporaryFile tf; // Use tf to get an unique filename.
ASSERT_NOERROR(close(tf.fd));
- ASSERT_NO_FATAL_FAILURE(CreateRelroFile(kLibName, tf.path));
- ASSERT_NO_FATAL_FAILURE(TryUsingRelro(kLibName));
+ ASSERT_NO_FATAL_FAILURE(CreateRelroFile(kLibName, tf.path, false));
+ ASSERT_NO_FATAL_FAILURE(TryUsingRelro(kLibName, false));
+ void* relro_data = dlsym(handle_, "lots_of_relro");
+ ASSERT_DL_NOTNULL(relro_data);
+ EXPECT_EQ(tf.path, FindMappingName(relro_data));
+
+ // Use destructor of tf to close and unlink the file.
+ tf.fd = extinfo_.relro_fd;
+}
+
+TEST_F(DlExtRelroSharingTest, ChildWritesGoodDataRecursive) {
+ TemporaryFile tf; // Use tf to get an unique filename.
+ ASSERT_NOERROR(close(tf.fd));
+
+ ASSERT_NO_FATAL_FAILURE(CreateRelroFile(kLibNameRecursive, tf.path, true));
+ ASSERT_NO_FATAL_FAILURE(TryUsingRelro(kLibNameRecursive, true));
+ void* relro_data = dlsym(handle_, "lots_of_relro");
+ ASSERT_DL_NOTNULL(relro_data);
+ EXPECT_EQ(tf.path, FindMappingName(relro_data));
+ void* recursive_relro_data = dlsym(handle_, "lots_more_relro");
+ ASSERT_DL_NOTNULL(recursive_relro_data);
+ EXPECT_EQ(tf.path, FindMappingName(recursive_relro_data));
+
// Use destructor of tf to close and unlink the file.
tf.fd = extinfo_.relro_fd;
@@ -445,15 +522,15 @@
TemporaryFile tf; // // Use tf to get an unique filename.
ASSERT_NOERROR(close(tf.fd));
- ASSERT_NO_FATAL_FAILURE(CreateRelroFile(kLibNameNoRelro, tf.path));
- ASSERT_NO_FATAL_FAILURE(TryUsingRelro(kLibNameNoRelro));
+ ASSERT_NO_FATAL_FAILURE(CreateRelroFile(kLibNameNoRelro, tf.path, false));
+ ASSERT_NO_FATAL_FAILURE(TryUsingRelro(kLibNameNoRelro, false));
// Use destructor of tf to close and unlink the file.
tf.fd = extinfo_.relro_fd;
}
TEST_F(DlExtRelroSharingTest, RelroFileEmpty) {
- ASSERT_NO_FATAL_FAILURE(TryUsingRelro(kLibName));
+ ASSERT_NO_FATAL_FAILURE(TryUsingRelro(kLibName, false));
}
TEST_F(DlExtRelroSharingTest, VerifyMemorySaving) {
@@ -465,7 +542,7 @@
TemporaryFile tf; // Use tf to get an unique filename.
ASSERT_NOERROR(close(tf.fd));
- ASSERT_NO_FATAL_FAILURE(CreateRelroFile(kLibName, tf.path));
+ ASSERT_NO_FATAL_FAILURE(CreateRelroFile(kLibName, tf.path, false));
int pipefd[2];
ASSERT_NOERROR(pipe(pipefd));
@@ -580,6 +657,21 @@
}
}
+std::string DlExtRelroSharingTest::FindMappingName(void* ptr) {
+ uint64_t addr = reinterpret_cast<uint64_t>(ptr);
+ std::string found_name = "<not found>";
+
+ EXPECT_TRUE(android::procinfo::ReadMapFile(
+ "/proc/self/maps",
+ [&](uint64_t start, uint64_t end, uint16_t, uint16_t, ino_t, const char* name) {
+ if (addr >= start && addr < end) {
+ found_name = name;
+ }
+ }));
+
+ return found_name;
+}
+
// Testing namespaces
static const char* g_public_lib = "libnstest_public.so";