OS: Pengertian Kernel Modul - Revision history

Onnowpurbo: /* FreeBSD */

2014-04-13T09:25:45Z

FreeBSD

Onnowpurbo: /* Linux */

2014-04-13T09:18:05Z

Linux

Onnowpurbo: /* Linux */

2014-04-13T09:03:31Z

Linux

Onnowpurbo: /* Implementations in different operating systems */

2014-04-13T08:52:10Z

Implementations in different operating systems

Onnowpurbo: /* Kerugian */

2014-04-13T07:53:46Z

Kerugian

Onnowpurbo: /* Keuntungan */

2014-04-13T04:51:34Z

Keuntungan

Onnowpurbo at 04:21, 13 April 2014

2014-04-13T04:21:24Z

Onnowpurbo at 04:12, 13 April 2014

2014-04-13T04:12:53Z

Onnowpurbo: New page: Sumber: http://en.wikipedia.org/wiki/Kernel_module In computing, a '''loadable kernel module''' (or '''LKM''') is an object file that contains code to extend the running [[kern...

2014-04-13T04:05:46Z

New page: Sumber: http://en.wikipedia.org/wiki/Kernel_module In computing, a '''loadable kernel module''' (or '''LKM''') is an object file that contains code to extend the running [[kern...

New page

Sumber: http://en.wikipedia.org/wiki/Kernel_module

In [[computing]], a '''loadable kernel module''' (or '''LKM''') is an [[object file]] that contains code to extend the running [[kernel (computer science)|kernel]], or so-called ''base kernel'', of an [[operating system]]. LKMs are typically used to add support for new [[computer hardware|hardware]] and/or [[filesystem]]s, or for adding [[system call]]s. When the functionality provided by a LKM is no longer required, it can be unloaded in order to free [[computer storage|memory]] and other resources.

Most current [[Unix-like]] systems and [[Microsoft Windows]] support loadable kernel modules, although they might use a different name for them, such as '''kernel loadable module''' ('''kld''') in [[FreeBSD]], '''kernel extension''' ('''kext''') in [[OS X]] and '''kernel-mode driver''' in Windows NT. They are also known as '''Kernel Loadable Modules''' (or '''KLM'''), and simply as '''Kernel Modules''' ('''KMOD''').

== Advantages ==
Without loadable kernel modules, an operating system would have to include all possible anticipated functionality already compiled directly into the base kernel. Much of that functionality would reside in memory without being used, wasting memory, and would require that users rebuild and [[booting|reboot]] the base kernel every time they require new functionality. Most operating systems supporting loadable kernel modules will include modules to support most desired functionality.

== Disadvantages ==
One minor criticism of preferring a modular kernel over a static kernel is the so-called ''[[Fragmentation (computer)|Fragmentation]] Penalty''.
The ''base kernel'' is always unpacked into ''real'' contiguous [[Random-access memory|memory]] by its setup routines; so, the base kernel code is never fragmented. Once the system is in a state where modules may be inserted—for example, once the [[filesystem]]s have been [[Mount (computing)|mount]]ed that contain the modules—it is probable that any new kernel code insertion will cause the kernel to become fragmented, thereby introducing a minor performance penalty.

== Implementations in different operating systems ==

=== Linux ===
Loadable kernel modules in Linux are loaded (and unloaded) by the <tt>[[modprobe]]</tt> command. They are located in <tt>/lib/modules</tt> and have had the extension <tt>.ko</tt> ("kernel object") since version 2.6 (previous versions used the <tt>.o</tt> extension). The <tt>[[lsmod]]</tt> command lists the loaded kernel modules. In emergency cases, when the system fails to boot due to e.g. broken modules, specific modules can be enabled or disabled by modifying the kernel boot parameters list (for example, if using [[GRUB]], by pressing 'e' in the GRUB start menu, then editing the kernel parameter line).

==== License issues ====
In the opinion of Linux maintainers, LKM are [[derived work]]s of the kernel. The Linux maintainers tolerate the distribution of [[Proprietary software|proprietary]] modules,{{Citation needed|date=April 2012}} but allow symbols to be marked as only available to [[GNU General Public License]] (GPL) modules.

Loading a proprietary or non-GPL-compatible LKM will set a 'taint' flag in the running kernel—meaning that any problems or [[Software bug|bugs]] experienced will be less likely to be investigated by the maintainers. LKMs effectively become part of the running kernel, so can corrupt kernel data structures and produce bugs that may not be able to be investigated if the module is indeed proprietary.

===== Linuxant controversy =====

In 2004, Linuxant—a consulting company that releases proprietary [[device driver]]s as loadable kernel modules—attempted to bypass GPLONLY symbol restrictions by abusing a [[Null character|NULL terminator]] in their <code>MODULE_LICENSE</code>:

<source lang="text">
MODULE_LICENSE("GPL\0for files in the \"GPL\" directory; for others, only LICENSE file applies");
</source>

The string comparison code used by the kernel at the time tried to determine whether the module was GPLed stopped when it reached a null character (<tt>\0</tt>), so it would be fooled into thinking that the module was declaring its license to be just "GPL".

=== FreeBSD ===
Kernel modules for [[FreeBSD]] are stored within <tt>/boot/kernel/</tt> for modules distributed with the [[Operating system|OS]], or usually <tt>/boot/modules/</tt> for modules installed from [[FreeBSD ports]] or [[FreeBSD ports#Packages|FreeBSD packages]], or for proprietary or otherwise binary-only modules. FreeBSD kernel modules usually have the extension <tt>.ko</tt>. Once the machine has booted, they may be loaded with the <tt>kldload</tt> command, unloaded with <tt>kldunload</tt>, and listed with <tt>kldstat</tt>. Modules can also be loaded from the loader before the kernel starts, either automatically (through <tt>/boot/loader.conf</tt>) or by hand.

=== OS X ===
Some loadable kernel modules in OS X can be loaded automatically. Loadable kernel modules can also be loaded by the <tt>kextload</tt> command. They can be listed by the <tt>kextstat</tt> command. Loadable kernel modules are located in [[application bundle]]s with the extension <tt>.kext</tt>. Modules supplied with the operating system are stored in the <tt>/System/Library/Extensions</tt> directory; modules supplied by third parties are in various other directories.

== Binary compatibility ==
Linux does not provide a stable [[API]] or [[Application binary interface|ABI]] for kernel modules. This means that there are differences in internal structure and function between different kernel versions, which can cause compatibility problems. In an attempt to combat those problems, symbol versioning data is placed within the <tt>.modinfo</tt> section of loadable [[Executable and Linkable Format|ELF]] modules. This versioning information can be compared with that of the running kernel before loading a module; if the versions are incompatible, the module will not be loaded.

Other operating systems, such as [[Solaris (operating system)|Solaris]], [[FreeBSD]], [[OS X]], and [[Microsoft Windows|Windows]] keep the kernel [[API]] and [[Application binary interface|ABI]] relatively stable, thus avoiding this problem. For example, [[FreeBSD]] kernel modules compiled against kernel version 6.0 will work without recompilation on any other FreeBSD 6.x version, e.g. 6.4. However, they are not compatible with other major versions and must be recompiled for use with FreeBSD 7.x, as API and ABI compatibility is maintained only within a branch.

== Security ==
While loadable kernel modules are a convenient method of modifying the running kernel, this can be abused by attackers on a compromised system to prevent detection of their [[Process (computing)|processes]] or [[Computer file|file]]s, allowing them to maintain control over the system. Many [[rootkits]] make use of LKMs in this way. Note that on most operating systems modules do not help [[privilege elevation]] in any way, as elevated privilege is required to load a LKM; they merely make it easier for the attacker to hide the break-in.

=== Linux ===
Linux allows disabling module loading via [[sysctl]] option <code>/proc/sys/kernel/modules_disabled</code>. An initramfs system may load specific modules needed for a machine at boot and then disable module loading. This makes the security very similar to a monolithic kernel. If an attacker can change the initramfs, they can change the kernel binary.

=== OS X ===
On OS X, a loadable kernel module in a kernel extension bundle can be loaded by non-root users if the OSBundleAllowUserLoad property is set to True in the bundle's property list. However, if any of the files in the bundle, including the executable code file, are not owned by root and group wheel, or are writable by the group or "other", the attempt to load the kernel loadable module will fail.

== External links ==
* [http://www.ibm.com/developerworks/linux/library/l-lkm/index.html?ca=dgr-lnxw07LinuxLKM&S_TACT=105AGX59&S_CMP=GR IBM DeveloperWorks in-depth article on LKM]
* [http://www.osx86.net/ Online kext database for OSX / Hackintosh]
* [http://en.tldp.org/LDP/lkmpg/index.html Ori Pomerantz, Linux Kernel Module Programming Guide]
* [http://www.linux.org/docs/ldp/howto/Module-HOWTO/copyright.html Copyright Considerations With LKMs]{{dead link|date=October 2011}}
* [http://developer.apple.com/mac/library/documentation/Darwin/Conceptual/KEXTConcept/KEXTConceptIntro/introduction.html "Kernel Extension Programming Topics" document for OS X]
* [http://www.web-manual.net/linux-3/what-is-a-loadable-kernel-module-lkm/ What Is A Loadable Kernel Module (LKM)?]

==Referensi==

* http://en.wikipedia.org/wiki/Kernel_module

@@ Line 22: / Line 22: @@
 Loadable kernel module di Linux  di load (dan di unload) menggunakan perintah <tt>[[modprobe]]</tt>.  Sejak versi 2.6, kernel modul berlokasi di <tt>/lib/modules</tt> dan mempunyai extension <tt>.ko</tt> ("kernel object"), versi sebelumnya menggunakan extension <tt>.o</tt>).
-Perintah <tt>[[lsmod]]</tt> memperlihatkan kernel modul yang di lad.
+Perintah <tt>[[lsmod]]</tt> memperlihatkan kernel modul yang di load ke memory.
 Pada saat emergency, saat sistem gagal di booting karena, misalnya, modul rusak, modul tertentu dapat di enable atau disable
 dengan cara memodifikasi daftar parameter boot kernel

@@ Line 11: / Line 11: @@
 == Kerugian ==
-One minor criticism of preferring a modular kernel over a static kernel is the so-called ''[[Fragmentation (computer)|Fragmentation]] Penalty''.
+Sedikit kritik bagi mereka yang lebih suka pada kernel yang modular daripada kernel statik adalah ''Fragmentation Penalty''.
-The ''base kernel'' is always unpacked into ''real'' contiguous [[Random-access memory|memory]] by its setup routines; so, the base kernel code is never fragmented. Once the system is in a state where modules may be inserted—for example, once the [[filesystem]]s have been [[Mount (computing)|mount]]ed that contain the modules—it is probable that any new kernel code insertion will cause the kernel to become fragmented, thereby introducing a minor performance penalty.
+''base kernel'' selalu masuk ke dalam memory (RAM) tanpa putus / contiguous oleh routine setup-nya;
 == Implementations in different operating systems ==

@@ Line 7: / Line 7: @@
 == Keuntungan ==
-Without loadable kernel modules, an operating system would have to include all possible anticipated functionality already compiled directly into the base kernel. Much of that functionality would reside in memory without being used, wasting memory, and would require that users rebuild and [[booting|reboot]] the base kernel every time they require new functionality. Most operating systems supporting loadable kernel modules will include modules to support most desired functionality.
+Tanpa loadable kernel module, sebuah sistem operasi harus memasukan semua fungsi yang mungkin nantinya akan digunakan ke dalam base kernel. Sebagian besar fungsi tersebut akan mengambil memory tanpa kita gunakan untuk apa-apa. Dengan kata lain, memboroskan memory, dan membutuhkan user membuat ulang dan [[reboot]] base kernel setiap kali user membutuhkan fungsi baru. Kebanyakan sistem operasi mendukung loadable kernel module akan memasukan modul untuk mendukung fungsi yang paling di butuhkannya.
 == Kerugian ==

@@ Line 3: / Line 3: @@
 Dalam dunia komputasi, '''Loadable Kernel Module''' (atau'''LKM''') adalah sebuah [[object file]] yang berisi code yang memperluas fungsi [[kernel]] yang berjalan, atau biasa disebut ''base kernel'', dari sebuah [[sistem operasi]]. LKM biasanya digunakan untuk dukungan bagi [[hardware]] baru atau [[filesystem]] baru, atau menambahkan [[system call]]. Saat fungsi yang diberikan oleh LKM tidak lagi dibutuhkan, kita dapat meng-unload LKM tersebut untuk membebaskan [[memory]] maupun sumber daya lainnya.
-Sebagia besar sistem [[Unix-like]] yang baru dan [[Microsoft Windows]] mendukung loadable kernel modules, meskipun mereka akan menggunakan nama lain, seperti '''kernel loadable module''' ('''kld''') di [[FreeBSD]], '''kernel extension''' ('''kext''') di [[OS X]] dan '''kernel-mode driver''' di Windows NT. Dia juga sering dikenali sebagai '''Kernel Loadable Module''' (atau '''KLM'''), atau hanya '''Kernel Module''' ('''KMOD''').
+Sebagian besar sistem [[Unix-like]] yang baru dan [[Microsoft Windows]] mendukung loadable kernel modules, meskipun mereka akan menggunakan nama lain, seperti '''kernel loadable module''' ('''kld''') di [[FreeBSD]], '''kernel extension''' ('''kext''') di [[OS X]] dan '''kernel-mode driver''' di Windows NT. Dia juga sering dikenali sebagai '''Kernel Loadable Module''' (atau '''KLM'''), atau hanya '''Kernel Module''' ('''KMOD''').
 == Keuntungan ==

@@ Line 45: / Line 45: @@
 === FreeBSD ===
-Kernel modules for [[FreeBSD]] are stored within <tt>/boot/kernel/</tt> for modules distributed with the [[Operating system|OS]], or usually <tt>/boot/modules/</tt> for modules installed from [[FreeBSD ports]] or [[FreeBSD ports#Packages|FreeBSD packages]], or for proprietary or otherwise binary-only modules.  FreeBSD kernel modules usually have the extension <tt>.ko</tt>.  Once the machine has booted, they may be loaded with the <tt>kldload</tt> command, unloaded with <tt>kldunload</tt>, and listed with <tt>kldstat</tt>.  Modules can also be loaded from the loader before the kernel starts, either automatically (through <tt>/boot/loader.conf</tt>) or by hand.
 === OS X ===

@@ Line 21: / Line 21: @@
 === Linux ===
-Loadable kernel module di Linux  di load (dan di unload) menggunakan perintah <tt>[[modprobe]]</tt>.  They are located in <tt>/lib/modules</tt> and have had the extension <tt>.ko</tt> ("kernel object") since version 2.6 (previous versions used the <tt>.o</tt> extension). The <tt>[[lsmod]]</tt> command lists the loaded kernel modules. In emergency cases, when the system fails to boot due to e.g. broken modules, specific modules can be enabled or disabled by modifying the kernel boot parameters list (for example, if using [[GRUB]], by pressing 'e' in the GRUB start menu, then editing the kernel parameter line).
+Loadable kernel module di Linux  di load (dan di unload) menggunakan perintah <tt>[[modprobe]]</tt>.  Sejak versi 2.6, kernel modul berlokasi di <tt>/lib/modules</tt> dan mempunyai extension <tt>.ko</tt> ("kernel object"), versi sebelumnya menggunakan extension <tt>.o</tt>).
 ==== License issues ====
 In the opinion of Linux maintainers, LKM are [[derived work]]s of the kernel. The Linux maintainers tolerate the distribution of [[Proprietary software|proprietary]] modules,{{Citation needed|date=April 2012}} but allow symbols to be marked as only available to [[GNU General Public License]] (GPL) modules.

@@ Line 17: / Line 17: @@
 akan menyebabkan kernel menjadi fragmented / terputus, ini kemungkinan akan menyebabkan pengorbanan / penalty performance.
-== Implementations in different operating systems ==
+== Implementasi di berbagai sistem operasi ==
 === Linux ===
-Loadable kernel modules in Linux are loaded (and unloaded) by the <tt>[[modprobe]]</tt> command.  They are located in <tt>/lib/modules</tt> and have had the extension <tt>.ko</tt> ("kernel object") since version 2.6 (previous versions used the <tt>.o</tt> extension). The <tt>[[lsmod]]</tt> command lists the loaded kernel modules. In emergency cases, when the system fails to boot due to e.g. broken modules, specific modules can be enabled or disabled by modifying the kernel boot parameters list (for example, if using [[GRUB]], by pressing 'e' in the GRUB start menu, then editing the kernel parameter line).
 ==== License issues ====

@@ Line 1: / Line 1: @@
 Sumber: http://en.wikipedia.org/wiki/Kernel_module
-In [[computing]], a '''loadable kernel module''' (or '''LKM''') is an [[object file]] that contains code to extend the running [[kernel (computer science)|kernel]], or so-called ''base kernel'', of an [[operating system]]. LKMs are typically used to add support for new [[computer hardware|hardware]] and/or [[filesystem]]s, or for adding [[system call]]s. When the functionality provided by a LKM is no longer required, it can be unloaded in order to free [[computer storage|memory]] and other resources.
+Without loadable kernel modules, an operating system would have to include all possible anticipated functionality already compiled directly into the base kernel. Much of that functionality would reside in memory without being used, wasting memory, and would require that users rebuild and [[booting|reboot]] the base kernel every time they require new functionality. Most operating systems supporting loadable kernel modules will include modules to support most desired functionality.
-Most current [[Unix-like]] systems and [[Microsoft Windows]] support loadable kernel modules, although they might use a different name for them, such as '''kernel loadable module''' ('''kld''') in [[FreeBSD]], '''kernel extension''' ('''kext''') in [[OS X]] and '''kernel-mode driver''' in Windows NT. They are also known as '''Kernel Loadable Modules''' (or '''KLM'''), and simply as '''Kernel Modules''' ('''KMOD''').
+== Kerugian ==
 One minor criticism of preferring a modular kernel over a static kernel is the so-called ''[[Fragmentation (computer)|Fragmentation]] Penalty''.
 The ''base kernel'' is always unpacked into ''real'' contiguous [[Random-access memory|memory]] by its setup routines; so, the base kernel code is never fragmented. Once the system is in a state where modules may be inserted—for example, once the [[filesystem]]s have been [[Mount (computing)|mount]]ed that contain the modules—it is probable that any new kernel code insertion will cause the kernel to become fragmented, thereby introducing a minor performance penalty.
@@ Line 33: / Line 32: @@
 </source>
-The string comparison code used by the kernel at the time tried to determine whether the module was GPLed stopped when it reached a null character (<tt>\0</tt>), so it would be fooled into thinking that the module was declaring its license to be just "GPL".
+The string comparison code used by the kernel at the time tried to determine whether the module was GPLed stopped when it reached a null character (<tt>\0</tt>), so it would be fooled into thinking that the module was declar
 === FreeBSD ===