Dazuko - FAQ (Troubleshooting - inserting the module)

FAQ: 5 Troubleshooting - inserting the module

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5.1 What does "insmod: error inserting './dazuko.ko': -1 Invalid parameters" mean?

This is a general error. Please look in /var/log/messages to see what the real problem is. Usually kernel messages are logged to this file.

5.2 In /var/log/messages it says "kernel: There is already a security framework initialized, register_security failed. kernel: dazuko: failed to register". What is wrong?

This occurs because another security module is already loaded and is not allowing Dazuko to be loaded. In order to allow multiple security modules, Linux 2.6 supports stacking. Unfortunately some modules do not implement this, which makes it impossible to load additional security modules. Dazuko does support stacking correctly. If you make sure that Dazuko is the first loaded security module, than other modules can also be loaded.

Typically the problem is the "capability" module. You can verify that this is the problem by unloading the "capability" module, loading Dazuko, and then reloading the "capability" module:

# rmmod capability
# insmod ./dazuko.ko
# modprobe capability

If this was indeed the problem, you can usually configure your system to load modules in a specific order. This varies between Linux distributions.

5.3 When I run the GNU/Linux command "insmod" I get an error about a kernel version mismatch. What is wrong?

This means that the kernel you are running is not the same as the kernel source code you are using to compile Dazuko. Either configure the kernel source code to match the kernel you are running or, even better, compile and install a new kernel from the source code.

See FAQ for information about how to configure your Linux kernel source code.

5.4 When I run the GNU/Linux command "insmod" I get an error that is not mentioned here. What is wrong?

Make sure you are inserting the module as root. If this is the case, the problem may be that you are using a different compiler (or compiler version) to build the Dazuko module than you used to build your kernel. Building your own kernel will guarentee that this is not a problem.

Note: There may be multiple versions of a compiler installed at the same time. Be sure to use the correct one.

Linux 2.6: You may be trying to use multiple security modules. This is not well supported under Linux 2.6. As long as Dazuko is loaded before any other security modules, other security modules may also be loaded. Dazuko version 2.0.4 or higher is required for this to work correctly. Here are some tips for Linux 2.6 users:

Tip 1. Configure and build your kernel with:

"Enable different security modules" ENABLED
"Default Linux Capabilities" as MODULE <M>
"NSA SELinux Support" DISABLED

Note: If SELinux has been built into your kernel, you can usually disable it at boot with the boot parameter "selinux=0"

Tip 2. Dazuko for Linux 2.6 requires the "commoncap" module. This module must be loaded before Dazuko can be loaded:

# modprobe commoncap

Tip 3. Once Dazuko has been loaded, you are free to load other security modules such as "capability" or "root_plug" if needed.

Note: If Dazuko was not loaded as the primary (first) security module, it may not work correctly or it may not be possible to add additional modules after Dazuko. This is a limitation of the first module loaded, not Dazuko. If Dazuko is loaded as the first security module, stacking will be correctly supported.

See FAQ for information about how to install Dazuko for SuSE 9.1.

5.5 The command "insmod" produces a segmentation fault when I load a module with syscall hooking enabled.

Most likely you are using a kernel that has a read-only syscall table. The configure script should have provided an IMPORTANT NOTICE about this. You will need to try to re-configure Dazuko with an additional option --sct-readonly. Unfortunately, you will need to reboot your system before continuing because the Dazuko module caused a crash during its initialization. Since the true read-write status of the syscall table can be determined at neither compile time nor run time, you are forced to try one method (first as read-write) and then the other (as read-only).

5.6 The Linux 2.6 kernel crashes in the change_page_attr() routine when I load a module with syscall hooking enabled.

You have most likely configured Dazuko using the --sct-readonly option for a kernel that does not have a read-only system call table. This option should only be used if problems (such as those mentioned in 5.5) are present. Since the true read-write status of the syscall table can be determined at neither compile time nor run time, you are forced to try one method (first as read-write) and then the other (as read-only).

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6 Troubleshooting - running the example program