############################################################################
## Data structures, Algorithms, and Programming tricks used in the kernel ##
##                                                                        ##
## Linux source code for all supported architectures is contained in      ##
## more than 14,000 C and assembly language files stored in about 1000    ##
## subdirectories; it consists of roughly 6 million lines of code,        ##
## which occupy over 230 megabytes of disk space.                         ##
############################################################################

Operating System Concept
+---------------------------------------------------------------------------------
| processes, interprocess communication, semaphores, monitors, message passing, 
| scheduling algorithms, input/output, deadlocks, device drivers, 
| memory management, paging algorithms, file system design, security, 
| and protection mechanisms
+---------------------------------------------------------------------------------

.oO Processor, Memory, Harddisk, Peripheral Oo.

Linux source code directory
/usr/src/linux

slackware config startup
/etc/rc.d/

System Call on Linux
- System Call Number -> asm/unistd.h (sys/syscall.h)
- System Call Table  -> arch/i386/kernel/entry.S

Commands to Manage Kernel Modules
This Command  Does the Following
------------------------------------------------------------------------------------
 insmod     |   Inserts a module into the kernel
------------------------------------------------------------------------------------
 rmmod      |   Removes a module from the kernel
------------------------------------------------------------------------------------
 depmod     |   Determines interdependencies between modules
------------------------------------------------------------------------------------
 ksyms 	|   Displays a list of symbols along with the name of the module that
	      |   defined the symbol
------------------------------------------------------------------------------------
 lsmod      |   Lists all currently loaded modules
------------------------------------------------------------------------------------
 modinfo    |   Displays information about a kernel module
------------------------------------------------------------------------------------
 modprobe   |   Inserts or removes a module or a set of modules intelligently (for
            |   example, if module A requires B, then modprobe automatically
            |   loads B when asked to load A
------------------------------------------------------------------------------------

/etc/rc.d/rc.inet1.conf
# Primary network interface card (eth0)
IPADDR[0]=""
NETMASK[0]=""
USE_DHCP[0]=""       | Yes
DHCP_HOSTNAME[0]=""  | Yes
GATEWAY=""

Kernel source references: 
o arch/i386/kernel/entry.S  (file:///usr/src/linux/arch/i386/kernel/entry.S)
o include/asm-i386/unistd.h (file:///usr/src/linux/include/asm-i386/unistd.h)
o include/linux/sys.h       (file:///usr/src/linux/include/linux/sys.h)

Process at Arch i386
o kernel/fork.c
o kernel/exit.c
o kernel/sched.c
o kernel/timer.c
o kernel/softirq.c
o fs/proc/base.c
o arch/i386/kernel/time.c
o arch/i386/kernel/process.c
o include/linux/sched.h
o include/asm-i386/system.h

Linux Kernel Modul   (LKM)
Linux Kernel Hooker ( LKH)
Linux Kernel Rootkit (LKR)

 | Silvio Cesare, "Runtime Kernel Kmem Patching"
 | http://reactor-core.org/runtime-kernel-patching.html
 --------------------------------------------------------

Kernel Hacking
o Bypassing Integrity Checking Systems
o BACKDOORING BINARY OBJECTS
o Buffer Overflow
  > stack-based buffer overflows
  > adjacent non-terminated string buffers
  > StackGuard 
  > The Frame Pointer Overwrite
  > HEAP OVERFLOW
o ELF(Executable and Linking Format) objects manipulation
o File Descriptor Hijacking
o Format string exploitation
o Bootloader (grub, lilo) exploitation
o Inbound memory management exploitation/malloc techniques
o set_head() technique
o Hiding processes/linux scheduler
o Hiding file
o Hiding Network Connection
o Integer Overflows
o Handling Interrupt Descriptor Table
o NULL/userspace dereference vulnerabilities
o The Slab Allocator
o Forcing a kernel path to sleep
o Race condition exploiting
o Hooking library the linux kernel
o Linux Kernel Keylogger/Function hijacking
o The kernel memory 
o return-into-lib(c) exploits
o Virtual File System exploitation
o Kernel patching without LKM
o Execution Redirection/control of binary execution
o Hijacking Linux Page Fault Handler Exception Table
o Infecting loadable kernel modules 
o ptrace injecting shellcodes
o Redirection of system calls
o Runtime Process Infection
o shift the stack pointer
o Static Kernel Patching
o syscall overflow
o the debugging mechanism/debug registers

~brtv