loader: enable loading libraries from tmpfs
This change adds two tests for dlopen from temporary files.
1. One Uses memfd_create() can be used to load libraries directly
from memory. This requires relaxing namespace accessibility check
in order to make this work in isolated namespaces.
2. Another checks that open with O_TMPFILE works.
Bug: http://b/37245203
Test: bionic-unit-tests --gtest_filter=dl*:Dl*
Change-Id: I3be1d7198ca17e7f1ba022a0d86c64d59a493506
diff --git a/linker/linker.cpp b/linker/linker.cpp
index 66bec58..53f0608 100644
--- a/linker/linker.cpp
+++ b/linker/linker.cpp
@@ -36,6 +36,7 @@
#include <string.h>
#include <sys/mman.h>
#include <sys/param.h>
+#include <sys/vfs.h>
#include <unistd.h>
#include <new>
@@ -1191,7 +1192,15 @@
return false;
}
- if (!ns->is_accessible(realpath)) {
+ struct statfs fs_stat;
+ if (TEMP_FAILURE_RETRY(fstatfs(task->get_fd(), &fs_stat)) != 0) {
+ DL_ERR("unable to fstatfs file for the library \"%s\": %s", name, strerror(errno));
+ return false;
+ }
+
+ // do not check accessibility using realpath if fd is located on tmpfs
+ // this enables use of memfd_create() for apps
+ if ((fs_stat.f_type != TMPFS_MAGIC) && (!ns->is_accessible(realpath))) {
// TODO(dimitry): workaround for http://b/26394120 - the grey-list
// TODO(dimitry) before O release: add a namespace attribute to have this enabled
diff --git a/tests/dlext_test.cpp b/tests/dlext_test.cpp
index a0226a6..35dff2a 100644
--- a/tests/dlext_test.cpp
+++ b/tests/dlext_test.cpp
@@ -24,9 +24,13 @@
#include <stdio.h>
#include <string.h>
#include <unistd.h>
+
#include <android/dlext.h>
+
+#include <linux/memfd.h>
#include <sys/mman.h>
#include <sys/types.h>
+#include <sys/vfs.h>
#include <sys/wait.h>
#include <pagemap/pagemap.h>
@@ -802,6 +806,98 @@
dlclose(handle2);
}
+TEST(dlext, dlopen_ext_use_o_tmpfile_fd) {
+ const std::string lib_path = get_testlib_root() + "/libtest_simple.so";
+
+ int tmpfd = TEMP_FAILURE_RETRY(
+ open(get_testlib_root().c_str(), O_TMPFILE | O_CLOEXEC | O_RDWR | O_EXCL));
+
+ // Ignore kernels without O_TMPFILE flag support
+ if (tmpfd == -1 && (errno == EISDIR || errno == EINVAL || errno == EOPNOTSUPP)) {
+ return;
+ }
+
+ ASSERT_TRUE(tmpfd != -1) << strerror(errno);
+
+ android_namespace_t* ns =
+ android_create_namespace("testing-o_tmpfile",
+ nullptr,
+ get_testlib_root().c_str(),
+ ANDROID_NAMESPACE_TYPE_ISOLATED,
+ nullptr,
+ nullptr);
+
+ ASSERT_DL_NOTNULL(ns);
+
+ ASSERT_TRUE(android_link_namespaces(ns, nullptr, g_core_shared_libs.c_str())) << dlerror();
+
+ std::string content;
+ ASSERT_TRUE(android::base::ReadFileToString(lib_path, &content)) << strerror(errno);
+ ASSERT_TRUE(android::base::WriteStringToFd(content, tmpfd)) << strerror(errno);
+
+ android_dlextinfo extinfo;
+ extinfo.flags = ANDROID_DLEXT_USE_LIBRARY_FD | ANDROID_DLEXT_USE_NAMESPACE;
+ extinfo.library_fd = tmpfd;
+ extinfo.library_namespace = ns;
+
+ void* handle = android_dlopen_ext("foobar", RTLD_NOW, &extinfo);
+
+ ASSERT_DL_NOTNULL(handle);
+
+ uint32_t* taxicab_number = reinterpret_cast<uint32_t*>(dlsym(handle, "dlopen_testlib_taxicab_number"));
+ ASSERT_DL_NOTNULL(taxicab_number);
+ EXPECT_EQ(1729U, *taxicab_number);
+ dlclose(handle);
+}
+
+TEST(dlext, dlopen_ext_use_memfd) {
+ const std::string lib_path = get_testlib_root() + "/libtest_simple.so";
+
+ // create memfd
+ int memfd = syscall(__NR_memfd_create, "foobar", MFD_CLOEXEC);
+ if (memfd == -1 && errno == ENOSYS) {
+ return;
+ }
+
+ ASSERT_TRUE(memfd != -1) << strerror(errno);
+
+ // Check st.f_type is TMPFS_MAGIC for memfd
+ struct statfs st;
+ ASSERT_TRUE(TEMP_FAILURE_RETRY(fstatfs(memfd, &st)) == 0) << strerror(errno);
+ ASSERT_EQ(static_cast<decltype(st.f_type)>(TMPFS_MAGIC), st.f_type);
+
+ android_namespace_t* ns =
+ android_create_namespace("testing-memfd",
+ nullptr,
+ get_testlib_root().c_str(),
+ ANDROID_NAMESPACE_TYPE_ISOLATED,
+ nullptr,
+ nullptr);
+
+ ASSERT_DL_NOTNULL(ns);
+
+ ASSERT_TRUE(android_link_namespaces(ns, nullptr, g_core_shared_libs.c_str())) << dlerror();
+
+ // read file into memfd backed one.
+ std::string content;
+ ASSERT_TRUE(android::base::ReadFileToString(lib_path, &content)) << strerror(errno);
+ ASSERT_TRUE(android::base::WriteStringToFd(content, memfd)) << strerror(errno);
+
+ android_dlextinfo extinfo;
+ extinfo.flags = ANDROID_DLEXT_USE_LIBRARY_FD | ANDROID_DLEXT_USE_NAMESPACE;
+ extinfo.library_fd = memfd;
+ extinfo.library_namespace = ns;
+
+ void* handle = android_dlopen_ext("foobar", RTLD_NOW, &extinfo);
+
+ ASSERT_DL_NOTNULL(handle);
+
+ uint32_t* taxicab_number = reinterpret_cast<uint32_t*>(dlsym(handle, "dlopen_testlib_taxicab_number"));
+ ASSERT_DL_NOTNULL(taxicab_number);
+ EXPECT_EQ(1729U, *taxicab_number);
+ dlclose(handle);
+}
+
TEST(dlext, ns_symbol_visibilty_one_namespace) {
static const char* root_lib = "libnstest_root.so";
ASSERT_TRUE(android_init_anonymous_namespace(g_core_shared_libs.c_str(), nullptr));
