init: Add support for native service registration with lmkd

init should be able to register native services with lmkd so that they
can be killed when needed. Only processes with oom_score_adjust not
equal to the default -1000 will be registered with lmkd because with the
score that low the process is unkillable anyway.
Inform lmkd when a registered process is killed so that the record can be
removed.
Change init.rc to start lmkd during init phase so that it is there to
register other services.
Replace hardcoded oom_score_adj values with appropriate definitions.

Bug: 129011369
Test: boot and verify native service registration
Change-Id: Ie5ed62203395120d86dc1c8250fae01aa0b3c511
Signed-off-by: Suren Baghdasaryan <[email protected]>

Author: surenbaghdasaryan

init/Android.bp

@@ -65,6 +65,7 @@ cc_defaults {
         "libavb",
         "libc++fs",
         "libcgrouprc_format",
+        "liblmkd_utils",
         "libmodprobe",
         "libprotobuf-cpp-lite",
         "libpropertyinfoserializer",
@@ -118,6 +119,7 @@ cc_library_static {
         "init.cpp",
         "interface_utils.cpp",
         "keychords.cpp",
+        "lmkd_service.cpp",
         "modalias_handler.cpp",
         "mount_handler.cpp",
         "mount_namespace.cpp",

init/init.cpp

@@ -59,6 +59,7 @@
 #include "first_stage_mount.h"
 #include "import_parser.h"
 #include "keychords.h"
+#include "lmkd_service.h"
 #include "mount_handler.h"
 #include "mount_namespace.h"
 #include "property_service.h"
@@ -684,9 +685,15 @@ int SecondStageMain(int argc, char** argv) {
     InitKernelLogging(argv);
     LOG(INFO) << "init second stage started!";
 
+    // Will handle EPIPE at the time of write by checking the errno
+    signal(SIGPIPE, SIG_IGN);
+
     // Set init and its forked children's oom_adj.
-    if (auto result = WriteFile("/proc/1/oom_score_adj", "-1000"); !result) {
-        LOG(ERROR) << "Unable to write -1000 to /proc/1/oom_score_adj: " << result.error();
+    if (auto result =
+                WriteFile("/proc/1/oom_score_adj", StringPrintf("%d", DEFAULT_OOM_SCORE_ADJUST));
+        !result) {
+        LOG(ERROR) << "Unable to write " << DEFAULT_OOM_SCORE_ADJUST
+                   << " to /proc/1/oom_score_adj: " << result.error();
     }
 
     // Set up a session keyring that all processes will have access to. It

init/lmkd_service.cpp

@@ -0,0 +1,131 @@
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "lmkd_service.h"
+
+#include <errno.h>
+
+#include <android-base/logging.h>
+#include <liblmkd_utils.h>
+
+#include "service_list.h"
+
+namespace android {
+namespace init {
+
+enum LmkdRegistrationResult {
+    LMKD_REG_SUCCESS,
+    LMKD_CONN_FAILED,
+    LMKD_REG_FAILED,
+};
+
+static int lmkd_socket = -1;
+
+static LmkdRegistrationResult RegisterProcess(uid_t uid, pid_t pid, int oom_score_adjust) {
+    // connect to lmkd if not already connected
+    if (lmkd_socket < 0) {
+        lmkd_socket = lmkd_connect();
+        if (lmkd_socket < 0) {
+            return LMKD_CONN_FAILED;
+        }
+    }
+
+    // register service with lmkd
+    struct lmk_procprio params;
+    params.pid = pid;
+    params.uid = uid;
+    params.oomadj = oom_score_adjust;
+    params.ptype = PROC_TYPE_SERVICE;
+    if (lmkd_register_proc(lmkd_socket, &params) != 0) {
+        // data transfer failed, reset the connection
+        close(lmkd_socket);
+        lmkd_socket = -1;
+        return LMKD_REG_FAILED;
+    }
+
+    return LMKD_REG_SUCCESS;
+}
+
+static bool UnregisterProcess(pid_t pid) {
+    if (lmkd_socket < 0) {
+        // no connection or it was lost, no need to unregister
+        return false;
+    }
+
+    // unregister service
+    struct lmk_procremove params;
+    params.pid = pid;
+    if (lmkd_unregister_proc(lmkd_socket, &params) != 0) {
+        // data transfer failed, reset the connection
+        close(lmkd_socket);
+        lmkd_socket = -1;
+        return false;
+    }
+
+    return true;
+}
+
+static void RegisterServices(pid_t exclude_pid) {
+    for (const auto& service : ServiceList::GetInstance().services()) {
+        auto svc = service.get();
+        if (svc->oom_score_adjust() != DEFAULT_OOM_SCORE_ADJUST) {
+            // skip if process is excluded or not yet forked (pid==0)
+            if (svc->pid() == exclude_pid || svc->pid() == 0) {
+                continue;
+            }
+            if (RegisterProcess(svc->uid(), svc->pid(), svc->oom_score_adjust()) !=
+                LMKD_REG_SUCCESS) {
+                // a failure here resets the connection, will retry during next registration
+                break;
+            }
+        }
+    }
+}
+
+void LmkdRegister(const std::string& name, uid_t uid, pid_t pid, int oom_score_adjust) {
+    bool new_connection = lmkd_socket == -1;
+    LmkdRegistrationResult result;
+
+    result = RegisterProcess(uid, pid, oom_score_adjust);
+    if (result == LMKD_REG_FAILED) {
+        // retry one time if connection to lmkd was lost
+        result = RegisterProcess(uid, pid, oom_score_adjust);
+        new_connection = result == LMKD_REG_SUCCESS;
+    }
+    switch (result) {
+        case LMKD_REG_SUCCESS:
+            // register existing services once new connection is established
+            if (new_connection) {
+                RegisterServices(pid);
+            }
+            break;
+        case LMKD_CONN_FAILED:
+            PLOG(ERROR) << "lmkd connection failed when " << name << " process got started";
+            break;
+        case LMKD_REG_FAILED:
+            PLOG(ERROR) << "lmkd failed to register " << name << " process";
+            break;
+    }
+}
+
+void LmkdUnregister(const std::string& name, pid_t pid) {
+    if (!UnregisterProcess(pid)) {
+        PLOG(ERROR) << "lmkd failed to unregister " << name << " process";
+    }
+}
+
+}  // namespace init
+}  // namespace android

init/lmkd_service.h

@@ -0,0 +1,44 @@
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <sys/types.h>
+
+#include <string>
+
+namespace android {
+namespace init {
+
+static const int MIN_OOM_SCORE_ADJUST = -1000;
+static const int MAX_OOM_SCORE_ADJUST = 1000;
+// service with default score is unkillable
+static const int DEFAULT_OOM_SCORE_ADJUST = MIN_OOM_SCORE_ADJUST;
+
+#if defined(__ANDROID__)
+
+void LmkdRegister(const std::string& name, uid_t uid, pid_t pid, int oom_score_adjust);
+void LmkdUnregister(const std::string& name, pid_t pid);
+
+#else  // defined(__ANDROID__)
+
+static inline void LmkdRegister(const std::string&, uid_t, pid_t, int) {}
+static inline void LmkdUnregister(const std::string&, pid_t) {}
+
+#endif  // defined(__ANDROID__)
+
+}  // namespace init
+}  // namespace android

init/service.cpp

@@ -36,6 +36,7 @@
 #include <processgroup/processgroup.h>
 #include <selinux/selinux.h>
 
+#include "lmkd_service.h"
 #include "service_list.h"
 #include "util.h"
 
@@ -151,7 +152,7 @@ Service::Service(const std::string& name, unsigned flags, uid_t uid, gid_t gid,
       seclabel_(seclabel),
       onrestart_(false, subcontext_for_restart_commands, "<Service '" + name + "' onrestart>", 0,
                  "onrestart", {}),
-      oom_score_adjust_(-1000),
+      oom_score_adjust_(DEFAULT_OOM_SCORE_ADJUST),
       start_order_(0),
       args_(args) {}
 
@@ -199,6 +200,10 @@ void Service::KillProcessGroup(int signal) {
 
         if (r == 0) process_cgroup_empty_ = true;
     }
+
+    if (oom_score_adjust_ != DEFAULT_OOM_SCORE_ADJUST) {
+        LmkdUnregister(name_, pid_);
+    }
 }
 
 void Service::SetProcessAttributesAndCaps() {
@@ -502,7 +507,7 @@ Result<void> Service::Start() {
         return ErrnoError() << "Failed to fork";
     }
 
-    if (oom_score_adjust_ != -1000) {
+    if (oom_score_adjust_ != DEFAULT_OOM_SCORE_ADJUST) {
         std::string oom_str = std::to_string(oom_score_adjust_);
         std::string oom_file = StringPrintf("/proc/%d/oom_score_adj", pid);
         if (!WriteStringToFile(oom_str, oom_file)) {
@@ -563,6 +568,10 @@ Result<void> Service::Start() {
         }
     }
 
+    if (oom_score_adjust_ != DEFAULT_OOM_SCORE_ADJUST) {
+        LmkdRegister(name_, proc_attr_.uid, pid_, oom_score_adjust_);
+    }
+
     NotifyStateChange("running");
     reboot_on_failure.Disable();
     return {};

init/service_parser.cpp

@@ -29,6 +29,7 @@
 #include <hidl-util/FQName.h>
 #include <system/thread_defs.h>
 
+#include "lmkd_service.h"
 #include "rlimit_parser.h"
 #include "service_utils.h"
 #include "util.h"
@@ -261,8 +262,10 @@ Result<void> ServiceParser::ParseNamespace(std::vector<std::string>&& args) {
 }
 
 Result<void> ServiceParser::ParseOomScoreAdjust(std::vector<std::string>&& args) {
-    if (!ParseInt(args[1], &service_->oom_score_adjust_, -1000, 1000)) {
-        return Error() << "oom_score_adjust value must be in range -1000 - +1000";
+    if (!ParseInt(args[1], &service_->oom_score_adjust_, MIN_OOM_SCORE_ADJUST,
+                  MAX_OOM_SCORE_ADJUST)) {
+        return Error() << "oom_score_adjust value must be in range " << MIN_OOM_SCORE_ADJUST
+                       << " - +" << MAX_OOM_SCORE_ADJUST;
     }
     return {};
 }

init/service_test.cpp

@@ -23,6 +23,7 @@
 
 #include <gtest/gtest.h>
 
+#include "lmkd_service.h"
 #include "util.h"
 
 namespace android {
@@ -49,7 +50,7 @@ TEST(service, pod_initialized) {
     EXPECT_EQ(IoSchedClass_NONE, service_in_old_memory->ioprio_class());
     EXPECT_EQ(0, service_in_old_memory->ioprio_pri());
     EXPECT_EQ(0, service_in_old_memory->priority());
-    EXPECT_EQ(-1000, service_in_old_memory->oom_score_adjust());
+    EXPECT_EQ(DEFAULT_OOM_SCORE_ADJUST, service_in_old_memory->oom_score_adjust());
     EXPECT_FALSE(service_in_old_memory->process_cgroup_empty());
 
     for (std::size_t i = 0; i < memory_size; ++i) {
@@ -68,7 +69,7 @@ TEST(service, pod_initialized) {
     EXPECT_EQ(IoSchedClass_NONE, service_in_old_memory2->ioprio_class());
     EXPECT_EQ(0, service_in_old_memory2->ioprio_pri());
     EXPECT_EQ(0, service_in_old_memory2->priority());
-    EXPECT_EQ(-1000, service_in_old_memory2->oom_score_adjust());
+    EXPECT_EQ(DEFAULT_OOM_SCORE_ADJUST, service_in_old_memory2->oom_score_adjust());
     EXPECT_FALSE(service_in_old_memory->process_cgroup_empty());
 }
 

rootdir/init.rc

@@ -347,6 +347,8 @@ on init
 
     # Start logd before any other services run to ensure we capture all of their logs.
     start logd
+    # Start lmkd before any other services run so that it can register them
+    start lmkd
 
     # Start essential services.
     start servicemanager