CODEWITHSUNDEEP
linuxdbussystemdbus
portleJay
portleJay

Reputation: 91

sd-bus API, sd_bus_request_name returns Permission denied

bus APIs in systemd 221. When I request a name for an object in system bus it prints out an error saying "Permission denied". I am running the output file as root. The line "sd_bus_request_name(bus, "net.poettering.Calculator", 0)" throws an error : "Failed to acquire servie name..: Permission denied"

I think root should have a permission to acquire a name for an object. Does any one know how to solve this?

thank you in advance.

Here is the example code from http://0pointer.net/blog/the-new-sd-bus-api-of-systemd.html :

int main(int argc, char *argv[]) {
sd_bus_slot *slot = NULL;
sd_bus *bus = NULL;
int r;

r = sd_bus_default_system(&bus);
if (r < 0) {
    fprintf(stderr, "Failed to connect to system bus: %s\n", strerror(-r));
    goto finish;
}

/* Install the object */
r = sd_bus_add_object_vtable(bus,
                             &slot,
                             "/net/poettering/Calculator",
                             "net.poettering.Calculator",   /* interface name                             */calculator_vtable,
                             NULL);
if (r < 0) {
    fprintf(stderr, "Failed to issue method call: %s\n", strerror(-r));
    goto finish;
}

/* Take a well-known service name so that clients can find us */
r = sd_bus_request_name(bus, "net.poettering.Calculator", 0);
if (r < 0) {
    fprintf(stderr, "Failed to acquire service name: %s\n", strerror(-r));
    goto finish;
}

Upvotes: 9

Views: 5771

Answers (3)

Jose
Jose

Reputation: 43

I don't know if this could be useful, but I found a workaround, not the most recommended because you allow the user to create dbus objects in the system bus without having them listed or having a specific configuration file for them.

  • You need to edit the file in /usr/share/dbus-1/system.conf with sudo.
  • Edit the contents of the lines below the Holes must be punched... phrase.

<!-- Holes must be punched in service configuration files for name ownership and sending method calls --

<deny own="*"/

<deny send_type="method_call"/>

  • Change the deny to allow.

With those changes the sd_bus_request_name returns Permission denied error was solved at least in my case.

Upvotes: 0

Red User
Red User

Reputation: 449

Typical default D-Bus configuration does not allow to register services except explicitly allowed. You need to allow root to register your service. Create /etc/dbus-1/system.d/net.poettering.Calculator.conf:

<!DOCTYPE busconfig PUBLIC
 "-//freedesktop//DTD D-BUS Bus Configuration 1.0//EN"
 "http://www.freedesktop.org/standards/dbus/1.0/busconfig.dtd">
<busconfig>
  <policy user="root">
    <allow own="net.poettering.Calculator"/>
  </policy>
</busconfig>

Read man dbus-daemon for details.

Upvotes: 10

Rational Technologies
Rational Technologies

Reputation: 1

int main(int argc, char *argv[])
{
    sd_bus_slot *slot = NULL;
    sd_bus *bus = NULL;
    int r;
    r = sd_bus_default_system(&bus);
    if (r < 0) 
    {
        fprintf(stderr, "Failed to connect to system bus: %s\n", strerror(-r));
        goto finish;
    }
}

Upvotes: -3

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