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Commit 8b637c88 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.
Merged-In: Ia51f078ad848535ce1ac29edd8a56a2b686a12cc
Change-Id: Ia51f078ad848535ce1ac29edd8a56a2b686a12cc
(cherry picked from commit 54b00a9e)
parent 6a8602a8

logd/main.cpp

+16 −14
Original line number Diff line number Diff line
@@ -62,14 +62,13 @@ 
// 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 int DropPrivs(bool klogd, bool auditd) {

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

        android::prdebug("failed to set background scheduling policy");

        return -1;

    }



    sched_param param = {};

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

        android::prdebug("failed to set batch scheduler");

        return -1;
@@ -84,21 +83,24 @@ static int drop_privs(bool klogd, bool auditd) { 


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

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

        android::prdebug("cap_clear() failed");

        return -1;

    }

    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) {

            android::prdebug("Failed to set CAP_SYSLOG");

            return -1;

        }

    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) {

    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) {

            android::prdebug("Failed to set CAP_AUDIT_CONTROL");

            return -1;

        }

    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) {

        android::prdebug("failed to set CAP_SYSLOG or CAP_AUDIT_CONTROL (%d)", errno);
@@ -332,7 +334,7 @@ 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) {

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

        return EXIT_FAILURE;

    }