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Commit 0d462c23 authored by David Anderson's avatar David Anderson Committed by Automerger Merge Worker
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Merge "init: only mlock() system pages when performing snapuserd transitions." am: c90fce43 

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

MUST ONLY BE SUBMITTED BY AUTOMERGER

Change-Id: Ida527e2b3690299ace5267068b743e8a77d28fd0
parents 9273df5b c90fce43

init/Android.bp

+2 −0
Original line number Diff line number Diff line
@@ -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,

init/Android.mk

+1 −0
Original line number Diff line number Diff line
@@ -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.

init/snapuserd_transition.cpp

+30 −3
Original line number Diff line number Diff line
@@ -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");