From bb8b22a087db32773f1a9cd3473061f3ad714afc Mon Sep 17 00:00:00 2001 From: Dimitry Ivanov Date: Fri, 21 Apr 2017 13:12:05 -0700 Subject: [PATCH] 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 --- linker/linker.cpp | 11 +++++- tests/dlext_test.cpp | 96 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 106 insertions(+), 1 deletion(-) diff --git a/linker/linker.cpp b/linker/linker.cpp index 66bec58af..53f0608b5 100644 --- a/linker/linker.cpp +++ b/linker/linker.cpp @@ -36,6 +36,7 @@ #include #include #include +#include #include #include @@ -1191,7 +1192,15 @@ static bool load_library(android_namespace_t* ns, 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 a0226a6f6..35dff2a31 100644 --- a/tests/dlext_test.cpp +++ b/tests/dlext_test.cpp @@ -24,9 +24,13 @@ #include #include #include + #include + +#include #include #include +#include #include #include @@ -802,6 +806,98 @@ TEST(dlext, ns_smoke) { 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(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(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(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)); -- 2.11.0