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Commit 36f53993 authored by Tom Cherry's avatar Tom Cherry
Browse files

logd: handle uidToName() directly 

uidToName() originally used a separate worker thread with additional
group permissions.  Threads are not security boundaries however, so
these group permissions are removed in a previous change.

This change handles the lookup for uidToName() directly without using
a separate thread.

Test: boot CF, logd unit tests
Change-Id: If245388bc221bc77102a0bbcee82c8f42b140760
parent acf19e80

logd/main.cpp

+22 −49
Original line number Original line Diff line number Diff line
@@ -150,43 +150,14 @@ void android::prdebug(const char* fmt, ...) { 
    }

    }

}

}





static sem_t uidName;

static uid_t uid;

static char* name;



static sem_t reinit;

static sem_t reinit;

static bool reinit_running = false;

static bool reinit_running = false;

static LogBuffer* logBuf = nullptr;

static LogBuffer* logBuf = nullptr;





static bool package_list_parser_cb(pkg_info* info, void* /* userdata */) {

    bool rc = true;

    if (info->uid == uid) {

        name = strdup(info->name);

        // false to stop processing

        rc = false;

    }



    packagelist_free(info);

    return rc;

}



static void* reinit_thread_start(void* /*obj*/) {

static void* reinit_thread_start(void* /*obj*/) {

    prctl(PR_SET_NAME, "logd.daemon");

    prctl(PR_SET_NAME, "logd.daemon");





    while (reinit_running && !sem_wait(&reinit) && reinit_running) {

    while (reinit_running && !sem_wait(&reinit) && reinit_running) {

        // uidToName Privileged Worker

        if (uid) {

            name = nullptr;



            // if we got the perms wrong above, this would spam if we reported

            // problems with acquisition of an uid name from the packages.

            (void)packagelist_parse(package_list_parser_cb, nullptr);



            uid = 0;

            sem_post(&uidName);

            continue;

        }



        if (fdDmesg >= 0) {

        if (fdDmesg >= 0) {

            static const char reinit_message[] = { KMSG_PRIORITY(LOG_INFO),

            static const char reinit_message[] = { KMSG_PRIORITY(LOG_INFO),

                                                   'l',

                                                   'l',
@@ -223,26 +194,30 @@ static void* reinit_thread_start(void* /*obj*/) { 
    return nullptr;

    return nullptr;

}

}





static sem_t sem_name;



char* android::uidToName(uid_t u) {

char* android::uidToName(uid_t u) {

    if (!u || !reinit_running) {

    struct Userdata {

        return nullptr;

        uid_t uid;

    }

        char* name;



    } userdata = {

    sem_wait(&sem_name);

            .uid = u,



            .name = nullptr,

    // Not multi-thread safe, we use sem_name to protect

    };

    uid = u;



    name = nullptr;

    sem_post(&reinit);

    sem_wait(&uidName);

    char* ret = name;





    sem_post(&sem_name);

    packagelist_parse(

            [](pkg_info* info, void* callback_parameter) {

                auto userdata = reinterpret_cast<Userdata*>(callback_parameter);

                bool result = true;

                if (info->uid == userdata->uid) {

                    userdata->name = strdup(info->name);

                    // false to stop processing

                    result = false;

                }

                packagelist_free(info);

                return result;

            },

            &userdata);





    return ret;

    return userdata.name;

}

}





// Serves as a global method to trigger reinitialization

// Serves as a global method to trigger reinitialization
@@ -363,8 +338,6 @@ int main(int argc, char* argv[]) { 




    // Reinit Thread

    // Reinit Thread

    sem_init(&reinit, 0, 0);

    sem_init(&reinit, 0, 0);

    sem_init(&uidName, 0, 0);

    sem_init(&sem_name, 0, 1);

    pthread_attr_t attr;

    pthread_attr_t attr;

    if (!pthread_attr_init(&attr)) {

    if (!pthread_attr_init(&attr)) {

        struct sched_param param;

        struct sched_param param;