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Commit 54b00a9e authored by Tom Cherry's avatar Tom Cherry
Browse files

logd: make drop_privs work if neither klogd or auditd are used 

Fix a bug that was causing cap_set_flag() fail and logd to exit.

Bug: 159588327
Test: caps are set correctly and logd functions with both, one of, or
      none of klogd and auditd enabled.
Change-Id: Ia51f078ad848535ce1ac29edd8a56a2b686a12cc
parent a2f97dbb

logd/main.cpp

+18 −27
Original line number Diff line number Diff line
@@ -69,49 +69,42 @@ 
// has a 'sigstop' feature that sends SIGSTOP to a service immediately before calling exec().  This

// allows debuggers, etc to be attached to logd at the very beginning, while still having init

// handle the user, groups, capabilities, files, etc setup.

static int drop_privs(bool klogd, bool auditd) {

    sched_param param = {};



static void DropPrivs(bool klogd, bool auditd) {

    if (set_sched_policy(0, SP_BACKGROUND) < 0) {

        PLOG(ERROR) << "failed to set background scheduling policy";

        return -1;

        PLOG(FATAL) << "failed to set background scheduling policy";

    }



    sched_param param = {};

    if (sched_setscheduler((pid_t)0, SCHED_BATCH, &param) < 0) {

        PLOG(ERROR) << "failed to set batch scheduler";

        return -1;

        PLOG(FATAL) << "failed to set batch scheduler";

    }



    if (!__android_logger_property_get_bool("ro.debuggable", BOOL_DEFAULT_FALSE) &&

        prctl(PR_SET_DUMPABLE, 0) == -1) {

        PLOG(ERROR) << "failed to clear PR_SET_DUMPABLE";

        return -1;

        PLOG(FATAL) << "failed to clear PR_SET_DUMPABLE";

    }



    std::unique_ptr<struct _cap_struct, int (*)(void*)> caps(cap_init(), cap_free);

    if (cap_clear(caps.get()) < 0) {

        return -1;

        PLOG(FATAL) << "cap_clear() failed";

    }

    std::vector<cap_value_t> cap_value;

    if (klogd) {

        cap_value.emplace_back(CAP_SYSLOG);

        cap_value_t cap_syslog = CAP_SYSLOG;

        if (cap_set_flag(caps.get(), CAP_PERMITTED, 1, &cap_syslog, CAP_SET) < 0 ||

            cap_set_flag(caps.get(), CAP_EFFECTIVE, 1, &cap_syslog, CAP_SET) < 0) {

            PLOG(FATAL) << "Failed to set CAP_SYSLOG";

        }

    if (auditd) {

        cap_value.emplace_back(CAP_AUDIT_CONTROL);

    }



    if (cap_set_flag(caps.get(), CAP_PERMITTED, cap_value.size(), cap_value.data(), CAP_SET) < 0) {

        return -1;

    if (auditd) {

        cap_value_t cap_audit_control = CAP_AUDIT_CONTROL;

        if (cap_set_flag(caps.get(), CAP_PERMITTED, 1, &cap_audit_control, CAP_SET) < 0 ||

            cap_set_flag(caps.get(), CAP_EFFECTIVE, 1, &cap_audit_control, CAP_SET) < 0) {

            PLOG(FATAL) << "Failed to set CAP_AUDIT_CONTROL";

        }

    if (cap_set_flag(caps.get(), CAP_EFFECTIVE, cap_value.size(), cap_value.data(), CAP_SET) < 0) {

        return -1;

    }

    if (cap_set_proc(caps.get()) < 0) {

        PLOG(ERROR) << "failed to set CAP_SYSLOG or CAP_AUDIT_CONTROL";

        return -1;

        PLOG(FATAL) << "cap_set_proc() failed";

    }



    return 0;

}



char* android::uidToName(uid_t u) {
@@ -254,9 +247,7 @@ int main(int argc, char* argv[]) { 
    }



    bool auditd = __android_logger_property_get_bool("ro.logd.auditd", BOOL_DEFAULT_TRUE);

    if (drop_privs(klogd, auditd) != 0) {

        return EXIT_FAILURE;

    }

    DropPrivs(klogd, auditd);



    // A cache of event log tags

    LogTags log_tags;