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Merge "init: only mlock() system pages when performing snapuserd transitions." am: c90fce4387 am: 0d462c23e0 am: a1e59f9d10

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Original change: https://android-review.googlesource.com/c/platform/system/core/+/1621424

MUST ONLY BE SUBMITTED BY AUTOMERGER

Change-Id: I3af8018a6e83c9016eb0c7acbca9b4b40a837258
This commit is contained in:
David Anderson 2021-03-08 21:26:42 +00:00 committed by Automerger Merge Worker
commit b8112a37c3
3 changed files with 33 additions and 3 deletions
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2
init/Android.bp
View file

@ -143,6 +143,7 @@ cc_defaults {
"libcgrouprc_format",
"liblmkd_utils",
"libmodprobe",
"libprocinfo",
"libprotobuf-cpp-lite",
"libpropertyinfoserializer",
"libpropertyinfoparser",
@ -308,6 +309,7 @@ cc_binary {
"libsnapshot_cow",
"libsnapshot_init",
"update_metadata-protos",
"libprocinfo",
],
static_executable: true,

1
init/Android.mk
View file

@ -130,6 +130,7 @@ LOCAL_STATIC_LIBRARIES := \
libsnapshot_cow \
libsnapshot_init \
update_metadata-protos \
libprocinfo \
LOCAL_SANITIZE := signed-integer-overflow
# First stage init is weird: it may start without stdout/stderr, and no /proc.

33
init/snapuserd_transition.cpp
View file

@ -24,6 +24,7 @@
#include <filesystem>
#include <string>
#include <string_view>
#include <android-base/file.h>
#include <android-base/logging.h>
@ -34,6 +35,7 @@
#include <libsnapshot/snapshot.h>
#include <libsnapshot/snapuserd_client.h>
#include <private/android_filesystem_config.h>
#include <procinfo/process_map.h>
#include <selinux/android.h>
#include "block_dev_initializer.h"
@ -157,6 +159,33 @@ SnapuserdSelinuxHelper::SnapuserdSelinuxHelper(std::unique_ptr<SnapshotManager>&
});
}
static void LockAllSystemPages() {
bool ok = true;
auto callback = [&](const android::procinfo::MapInfo& map) -> void {
if (!ok || android::base::StartsWith(map.name, "/dev/") ||
!android::base::StartsWith(map.name, "/")) {
return;
}
auto start = reinterpret_cast<const void*>(map.start);
auto len = map.end - map.start;
if (!len) {
return;
}
if (mlock(start, len) < 0) {
LOG(ERROR) << "mlock failed, " << start << " for " << len << " bytes.";
ok = false;
}
};
if (!android::procinfo::ReadProcessMaps(getpid(), callback) || !ok) {
LOG(FATAL) << "Could not process /proc/" << getpid() << "/maps file for init, "
<< "falling back to mlockall().";
if (mlockall(MCL_CURRENT) < 0) {
LOG(FATAL) << "mlockall failed";
}
}
}
void SnapuserdSelinuxHelper::StartTransition() {
LOG(INFO) << "Starting SELinux transition of snapuserd";
@ -170,9 +199,7 @@ void SnapuserdSelinuxHelper::StartTransition() {
// We cannot access /system after the transition, so make sure init is
// pinned in memory.
if (mlockall(MCL_CURRENT) < 0) {
LOG(FATAL) << "mlockall failed";
}
LockAllSystemPages();
argv_.emplace_back("snapuserd");
argv_.emplace_back("-no_socket");