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Don't bind-mount bionic files

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Bind-mounting of the bionic files on /bionic/* paths no longer required
as there are direct symlinks from bionic files in /system partition to
the corresponding bionic files in the runtime APEX. e.g.,

/system/lib/libc.so -> /apex/com.android.runtime/lib/bionic/libc.so

Bug: 125549215
Test: m; devices boots
Change-Id: I4a43101c3e3e2e14a81001d6d65a8a4b727df385
This commit is contained in:
Jiyong Park 2019-02-25 16:41:38 +09:00
parent 9a00f596d3
commit 7b4801a921
5 changed files with 7 additions and 129 deletions
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9
init/builtins.cpp
View file

@ -1118,14 +1118,6 @@ static Result<Success> do_parse_apex_configs(const BuiltinArguments& args) {
}
}
static Result<Success> do_setup_runtime_bionic(const BuiltinArguments& args) {
if (SetupRuntimeBionic()) {
return Success();
} else {
return Error() << "Failed to setup runtime bionic";
}
}
static Result<Success> do_enter_default_mount_ns(const BuiltinArguments& args) {
if (SwitchToDefaultMountNamespace()) {
return Success();
@ -1181,7 +1173,6 @@ const BuiltinFunctionMap::Map& BuiltinFunctionMap::map() const {
{"rmdir", {1, 1, {true, do_rmdir}}},
{"setprop", {2, 2, {true, do_setprop}}},
{"setrlimit", {3, 3, {false, do_setrlimit}}},
{"setup_runtime_bionic", {0, 0, {false, do_setup_runtime_bionic}}},
{"start", {1, 1, {false, do_start}}},
{"stop", {1, 1, {false, do_stop}}},
{"swapon_all", {1, 1, {false, do_swapon_all}}},

120
init/mount_namespace.cpp
View file

@ -33,37 +33,6 @@ namespace android {
namespace init {
namespace {
static constexpr const char* kLinkerMountPoint = "/bionic/bin/linker";
static constexpr const char* kBootstrapLinkerPath = "/system/bin/bootstrap/linker";
static constexpr const char* kRuntimeLinkerPath = "/apex/com.android.runtime/bin/linker";
static constexpr const char* kBionicLibsMountPointDir = "/bionic/lib/";
static constexpr const char* kBootstrapBionicLibsDir = "/system/lib/bootstrap/";
static constexpr const char* kRuntimeBionicLibsDir = "/apex/com.android.runtime/lib/bionic/";
static constexpr const char* kLinkerMountPoint64 = "/bionic/bin/linker64";
static constexpr const char* kBootstrapLinkerPath64 = "/system/bin/bootstrap/linker64";
static constexpr const char* kRuntimeLinkerPath64 = "/apex/com.android.runtime/bin/linker64";
static constexpr const char* kBionicLibsMountPointDir64 = "/bionic/lib64/";
static constexpr const char* kBootstrapBionicLibsDir64 = "/system/lib64/bootstrap/";
static constexpr const char* kRuntimeBionicLibsDir64 = "/apex/com.android.runtime/lib64/bionic/";
static const std::vector<std::string> kBionicLibFileNames = {"libc.so", "libm.so", "libdl.so"};
static bool BindMount(const std::string& source, const std::string& mount_point,
bool recursive = false) {
unsigned long mountflags = MS_BIND;
if (recursive) {
mountflags |= MS_REC;
}
if (mount(source.c_str(), mount_point.c_str(), nullptr, mountflags, nullptr) == -1) {
PLOG(ERROR) << "Could not bind-mount " << source << " to " << mount_point;
return false;
}
return true;
}
static bool MakeShared(const std::string& mount_point, bool recursive = false) {
unsigned long mountflags = MS_SHARED;
if (recursive) {
@ -105,34 +74,6 @@ static std::string GetMountNamespaceId() {
return ret;
}
static bool BindMountBionic(const std::string& linker_source, const std::string& lib_dir_source,
const std::string& linker_mount_point,
const std::string& lib_mount_dir) {
if (access(linker_source.c_str(), F_OK) != 0) {
PLOG(INFO) << linker_source << " does not exist. skipping mounting bionic there.";
// This can happen for 64-bit bionic in 32-bit only device.
// It is okay to skip mounting the 64-bit bionic.
return true;
}
if (!BindMount(linker_source, linker_mount_point)) {
return false;
}
if (!MakePrivate(linker_mount_point)) {
return false;
}
for (const auto& libname : kBionicLibFileNames) {
std::string mount_point = lib_mount_dir + libname;
std::string source = lib_dir_source + libname;
if (!BindMount(source, mount_point)) {
return false;
}
if (!MakePrivate(mount_point)) {
return false;
}
}
return true;
}
static bool IsApexUpdatable() {
static bool updatable = android::sysprop::ApexProperties::updatable().value_or(false);
return updatable;
@ -154,26 +95,7 @@ bool SetupMountNamespaces() {
// point to private.
if (!MakeShared("/", true /*recursive*/)) return false;
// Since different files (bootstrap or runtime APEX) should be mounted to
// the same mount point paths (e.g. /bionic/bin/linker, /bionic/lib/libc.so,
// etc.) across the two mount namespaces, we create a private mount point at
// /bionic so that a mount event for the bootstrap bionic in the mount
// namespace for pre-apexd processes is not propagated to the other mount
// namespace for post-apexd process, and vice versa.
//
// Other mount points other than /bionic, however, are all still shared.
if (!BindMount("/bionic", "/bionic", true /*recursive*/)) return false;
if (!MakePrivate("/bionic")) return false;
// Bind-mount bootstrap bionic.
if (!BindMountBionic(kBootstrapLinkerPath, kBootstrapBionicLibsDir, kLinkerMountPoint,
kBionicLibsMountPointDir))
return false;
if (!BindMountBionic(kBootstrapLinkerPath64, kBootstrapBionicLibsDir64, kLinkerMountPoint64,
kBionicLibsMountPointDir64))
return false;
// /apex is also a private mountpoint to give different sets of APEXes for
// /apex is a private mountpoint to give different sets of APEXes for
// the bootstrap and default mount namespaces. The processes running with
// the bootstrap namespace get APEXes from the read-only partition.
if (!(MakePrivate("/apex"))) return false;
@ -181,12 +103,11 @@ bool SetupMountNamespaces() {
bootstrap_ns_fd.reset(OpenMountNamespace());
bootstrap_ns_id = GetMountNamespaceId();
// When bionic is updatable via the runtime APEX, we create separate mount
// When APEXes are updatable (e.g. not-flattened), we create separate mount
// namespaces for processes that are started before and after the APEX is
// activated by apexd. In the namespace for pre-apexd processes, the bionic
// from the /system partition (that we call bootstrap bionic) is
// bind-mounted. In the namespace for post-apexd processes, the bionic from
// the runtime APEX is bind-mounted.
// activated by apexd. In the namespace for pre-apexd processes, small
// number of essential APEXes (e.g. com.android.runtime) are activated.
// In the namespace for post-apexd processes, all APEXes are activated.
bool success = true;
if (IsApexUpdatable() && !IsRecoveryMode()) {
// Creating a new namespace by cloning, saving, and switching back to
@ -198,15 +119,6 @@ bool SetupMountNamespaces() {
default_ns_fd.reset(OpenMountNamespace());
default_ns_id = GetMountNamespaceId();
// By this unmount, the bootstrap bionic are not mounted in the default
// mount namespace.
if (umount2("/bionic", MNT_DETACH) == -1) {
PLOG(ERROR) << "Cannot unmount /bionic";
// Don't return here. We have to switch back to the bootstrap
// namespace.
success = false;
}
if (setns(bootstrap_ns_fd.get(), CLONE_NEWNS) == -1) {
PLOG(ERROR) << "Cannot switch back to bootstrap mount namespace";
return false;
@ -237,28 +149,6 @@ bool SwitchToDefaultMountNamespace() {
return true;
}
// TODO(jiyong): remove this when /system/lib/libc.so becomes
// a symlink to /apex/com.android.runtime/lib/bionic/libc.so
bool SetupRuntimeBionic() {
if (IsRecoveryMode()) {
// We don't have multiple namespaces in recovery mode
return true;
}
// Bind-mount bionic from the runtime APEX since it is now available. Note
// that in case of IsApexUpdatable() == false, these mounts are over the
// existing existing bind mounts for the bootstrap bionic, which effectively
// becomes hidden.
if (!BindMountBionic(kRuntimeLinkerPath, kRuntimeBionicLibsDir, kLinkerMountPoint,
kBionicLibsMountPointDir))
return false;
if (!BindMountBionic(kRuntimeLinkerPath64, kRuntimeBionicLibsDir64, kLinkerMountPoint64,
kBionicLibsMountPointDir64))
return false;
LOG(INFO) << "Runtime bionic is set up";
return true;
}
bool SwitchToBootstrapMountNamespaceIfNeeded() {
if (IsRecoveryMode()) {
// we don't have multiple namespaces in recovery mode

1
init/mount_namespace.h
View file

@ -20,7 +20,6 @@ namespace android {
namespace init {
bool SetupMountNamespaces();
bool SetupRuntimeBionic();
bool SwitchToDefaultMountNamespace();
bool SwitchToBootstrapMountNamespaceIfNeeded();

4
rootdir/etc/ld.config.txt
View file

@ -83,7 +83,7 @@ namespace.default.permitted.paths += /%PRODUCT_SERVICES%/app
namespace.default.permitted.paths += /%PRODUCT_SERVICES%/priv-app
namespace.default.permitted.paths += /data
namespace.default.permitted.paths += /mnt/expand
namespace.default.permitted.paths += /bionic/${LIB}
namespace.default.permitted.paths += /apex/com.android.runtime/${LIB}/bionic
namespace.default.permitted.paths += /system/${LIB}/bootstrap
namespace.default.asan.search.paths = /data/asan/system/${LIB}
@ -119,7 +119,7 @@ namespace.default.asan.permitted.paths += /%PRODUCT_SERVICES%/framework
namespace.default.asan.permitted.paths += /%PRODUCT_SERVICES%/app
namespace.default.asan.permitted.paths += /%PRODUCT_SERVICES%/priv-app
namespace.default.asan.permitted.paths += /mnt/expand
namespace.default.asan.permitted.paths += /bionic/${LIB}
namespace.default.asan.permitted.paths += /apex/com.android.runtime/${LIB}/bionic
namespace.default.asan.permitted.paths += /system/${LIB}/bootstrap
# Keep in sync with ld.config.txt in the com.android.runtime APEX.

2
rootdir/init.rc
View file

@ -578,8 +578,6 @@ on post-fs-data
# Wait for apexd to finish activating APEXes before starting more processes.
wait_for_prop apexd.status ready
# TODO(jiyong): remove setup_runtime_bionic
setup_runtime_bionic
parse_apex_configs
init_user0