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Cleanup for #inclusivefixit.

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Test: treehugger
Change-Id: I651689e2d59c017a9bde44251d95b57e594f0b5b
This commit is contained in:
Elliott Hughes 2020-07-28 11:09:03 -07:00
parent 5ce349927d
commit e79b8c2092
2 changed files with 19 additions and 51 deletions
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59
init/mount_namespace.cpp
View file

@ -44,50 +44,17 @@ namespace android {
namespace init {
namespace {
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) {
static bool BindMount(const std::string& source, const std::string& mount_point) {
if (mount(source.c_str(), mount_point.c_str(), nullptr, MS_BIND | MS_REC, nullptr) == -1) {
PLOG(ERROR) << "Failed to bind mount " << source;
return false;
}
return true;
}
static bool MakeShared(const std::string& mount_point, bool recursive = false) {
unsigned long mountflags = MS_SHARED;
if (recursive) {
mountflags |= MS_REC;
}
static bool ChangeMount(const std::string& mount_point, unsigned long mountflags) {
if (mount(nullptr, mount_point.c_str(), nullptr, mountflags, nullptr) == -1) {
PLOG(ERROR) << "Failed to change propagation type to shared";
return false;
}
return true;
}
static bool MakeSlave(const std::string& mount_point, bool recursive = false) {
unsigned long mountflags = MS_SLAVE;
if (recursive) {
mountflags |= MS_REC;
}
if (mount(nullptr, mount_point.c_str(), nullptr, mountflags, nullptr) == -1) {
PLOG(ERROR) << "Failed to change propagation type to slave";
return false;
}
return true;
}
static bool MakePrivate(const std::string& mount_point, bool recursive = false) {
unsigned long mountflags = MS_PRIVATE;
if (recursive) {
mountflags |= MS_REC;
}
if (mount(nullptr, mount_point.c_str(), nullptr, mountflags, nullptr) == -1) {
PLOG(ERROR) << "Failed to change propagation type to private";
PLOG(ERROR) << "Failed to remount " << mount_point << " as " << std::hex << mountflags;
return false;
}
return true;
@ -225,17 +192,17 @@ bool SetupMountNamespaces() {
// needed for /foo/bar, then we will make /foo/bar as a mount point (by
// bind-mounting by to itself) and set the propagation type of the mount
// point to private.
if (!MakeShared("/", true /*recursive*/)) return false;
if (!ChangeMount("/", MS_SHARED | MS_REC)) return false;
// /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;
if (!(ChangeMount("/apex", MS_PRIVATE))) return false;
// /linkerconfig is a private mountpoint to give a different linker configuration
// based on the mount namespace. Subdirectory will be bind-mounted based on current mount
// namespace
if (!(MakePrivate("/linkerconfig"))) return false;
if (!(ChangeMount("/linkerconfig", MS_PRIVATE))) return false;
// The two mount namespaces present challenges for scoped storage, because
// vold, which is responsible for most of the mounting, lives in the
@ -266,15 +233,15 @@ bool SetupMountNamespaces() {
if (!mkdir_recursive("/mnt/user", 0755)) return false;
if (!mkdir_recursive("/mnt/installer", 0755)) return false;
if (!mkdir_recursive("/mnt/androidwritable", 0755)) return false;
if (!(BindMount("/mnt/user", "/mnt/installer", true))) return false;
if (!(BindMount("/mnt/user", "/mnt/androidwritable", true))) return false;
if (!(BindMount("/mnt/user", "/mnt/installer"))) return false;
if (!(BindMount("/mnt/user", "/mnt/androidwritable"))) return false;
// First, make /mnt/installer and /mnt/androidwritable a slave bind mount
if (!(MakeSlave("/mnt/installer"))) return false;
if (!(MakeSlave("/mnt/androidwritable"))) return false;
if (!(ChangeMount("/mnt/installer", MS_SLAVE))) return false;
if (!(ChangeMount("/mnt/androidwritable", MS_SLAVE))) return false;
// Then, make it shared again - effectively creating a new peer group, that
// will be inherited by new mount namespaces.
if (!(MakeShared("/mnt/installer"))) return false;
if (!(MakeShared("/mnt/androidwritable"))) return false;
if (!(ChangeMount("/mnt/installer", MS_SHARED))) return false;
if (!(ChangeMount("/mnt/androidwritable", MS_SHARED))) return false;
bootstrap_ns_fd.reset(OpenMountNamespace());
bootstrap_ns_id = GetMountNamespaceId();

11
init/service_utils.cpp
View file

@ -60,13 +60,14 @@ Result<void> EnterNamespace(int nstype, const char* path) {
Result<void> SetUpMountNamespace(bool remount_proc, bool remount_sys) {
constexpr unsigned int kSafeFlags = MS_NODEV | MS_NOEXEC | MS_NOSUID;
// Recursively remount / as slave like zygote does so unmounting and mounting /proc
// doesn't interfere with the parent namespace's /proc mount. This will also
// prevent any other mounts/unmounts initiated by the service from interfering
// with the parent namespace but will still allow mount events from the parent
// Recursively remount / as MS_SLAVE like zygote does so that
// unmounting and mounting /proc doesn't interfere with the parent
// namespace's /proc mount. This will also prevent any other
// mounts/unmounts initiated by the service from interfering with the
// parent namespace but will still allow mount events from the parent
// namespace to propagate to the child.
if (mount("rootfs", "/", nullptr, (MS_SLAVE | MS_REC), nullptr) == -1) {
return ErrnoError() << "Could not remount(/) recursively as slave";
return ErrnoError() << "Could not remount(/) recursively as MS_SLAVE";
}
// umount() then mount() /proc and/or /sys