Kernel module to disable the ptrace() system call (http://blog.ghedini.me/post/10240771002/kernel-module-to-disable-ptrace)

Makefile

# Copyright (C) 2011 Alessandro Ghedini <[email protected]>
# Updated 2012 by Mike Perry to extract syscall table addresses
# Updated 2014 by Francis Brosnan Blázquez to check for ia32 support
obj-m += noptrace2.o

KERNEL_VER=$(shell uname -r)

SCT   := $(shell grep " sys_call_table" /boot/System.map-$(KERNEL_VER) | awk '{ print $$1; }')
SCT32 := $(shell grep "ia32_sys_call_table" /boot/System.map-$(KERNEL_VER) | awk '{ print $$1; }')

EXTRA_CFLAGS += -Dsys_call_table_addr="((void**)0x$(SCT))"
ifdef SCT32
EXTRA_CFLAGS += -Dia32_sys_call_table_addr="((void**)0x$(SCT32))" -D__enable_32bits_support
endif

all:
	@echo "Building with " . $(EXTRA_CFLAGS)
	make -C /lib/modules/$(KERNEL_VER)/build M=$(PWD)

clean:
	make -C /lib/modules/$(KERNEL_VER)/build M=$(PWD) clean

noptrace2.c

/*
 * Kernel module to disable the ptrace() system call.
 * Updated to disable ia32 ptrace by Mike Perry <mikeperry torproject org>
 * Updated to check for ia32 support by Francis Brosnan Blázquez <francis aspl es>
 *
 * Compile:
 * $ make
 *
 * Usage:
 * # insmod noptrace2.ko
 * # rmmod noptrace2
 *
 * Copyright (C) 2011 Alessandro Ghedini <[email protected]>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <linux/init.h>

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/syscalls.h>
#include <linux/sched.h>

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Alessandro Ghedini and Mike Perry");
MODULE_DESCRIPTION("disable the ptrace() system call");

/* ia32 entry */
#define __NR_compat_ptrace 26

static asmlinkage long (*o_ptr)(long request, long pid, unsigned long addr, unsigned long data);
#if defined(__enable_32bits_support)
static asmlinkage long (*o_ptr32)(long request, long pid, unsigned long addr, unsigned long data);
#endif

asmlinkage long noptrace(long request, long pid, unsigned long addr, unsigned long data) {
	printk("[noptrace2] ptrace() invoked against process %ld by process %i\n",
               pid, current->pid);

	return EPERM;
}

static void sys_call_table_make_rw(void **addr);
static void sys_call_table_make_ro(void **addr);

static int __init init_noptrace(void) {
	void **sys_call_tbl = sys_call_table_addr;
#if defined(__enable_32bits_support)
	void **ia32_sys_call_tbl = ia32_sys_call_table_addr;
#endif

	sys_call_table_make_rw(sys_call_tbl);
	o_ptr = sys_call_tbl[__NR_ptrace];
	sys_call_tbl[__NR_ptrace] = noptrace;
	sys_call_table_make_ro(sys_call_tbl);

#if defined(__enable_32bits_support)
	sys_call_table_make_rw(ia32_sys_call_tbl);
	o_ptr32 = ia32_sys_call_tbl[__NR_compat_ptrace];
	ia32_sys_call_tbl[__NR_compat_ptrace] = noptrace;
	sys_call_table_make_ro(ia32_sys_call_tbl);
#endif

	printk("[noptrace2] ptrace syscall disabled\n");

	return 0;
}

static void __exit exit_noptrace(void) {
	void **sys_call_tbl = sys_call_table_addr;
#if defined(__enable_32bits_support)
	void **ia32_sys_call_tbl = ia32_sys_call_table_addr;
#endif

	sys_call_table_make_rw(sys_call_tbl);
	sys_call_tbl[__NR_ptrace] = o_ptr;
	sys_call_table_make_ro(sys_call_tbl);

#if defined(__enable_32bits_support)
	sys_call_table_make_rw(ia32_sys_call_tbl);
	ia32_sys_call_tbl[__NR_compat_ptrace] = o_ptr32;
	sys_call_table_make_ro(ia32_sys_call_tbl);
#endif

	printk("[noptrace2] ptrace syscall restored\n");
}

module_init(init_noptrace);
module_exit(exit_noptrace);

static void sys_call_table_make_rw(void **addr) {
	unsigned int lvl;

	pte_t *pte = lookup_address((unsigned long) addr, &lvl);

	if (pte -> pte &~ _PAGE_RW)
		pte -> pte |= _PAGE_RW;

	write_cr0(read_cr0() & (~ 0x10000));
}

static void sys_call_table_make_ro(void **addr) {
	unsigned int lvl;

	pte_t *pte = lookup_address((unsigned long) addr, &lvl);
	pte -> pte = pte -> pte &~_PAGE_RW;

	write_cr0(read_cr0() | 0x10000);
}

Line 59 , wrong function
should be sys_call_table_make_rw