diff options
Diffstat (limited to 'DNA/linux/krebs.c')
| -rw-r--r-- | DNA/linux/krebs.c | 192 |
1 files changed, 192 insertions, 0 deletions
diff --git a/DNA/linux/krebs.c b/DNA/linux/krebs.c new file mode 100644 index 00000000..df319c63 --- /dev/null +++ b/DNA/linux/krebs.c @@ -0,0 +1,192 @@ +/* + * kernelroll - linux kernel module for advanced rickrolling + * Copyright (C) 2011 Franz Pletz <fpletz@fnordicwalking.de> + * + * 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 3 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/module.h> +#include <linux/kernel.h> +#include <linux/init.h> +#include <asm/unistd.h> +#include <linux/syscalls.h> +#include <asm/amd_nb.h> +#include <linux/highuid.h> + +#define GPF_DISABLE write_cr0(read_cr0() & (~ 0x10000)) +#define GPF_ENABLE write_cr0(read_cr0() | 0x10000) + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Franz Pletz"); +MODULE_DESCRIPTION("for teh lulz!"); + +char *rollfile = NULL; +unsigned long **sys_call_table = NULL; +module_param(rollfile, charp, 0000); +MODULE_PARM_DESC(rollfile, "music trolling file"); + +module_param(sys_call_table, ulong, 0000); +MODULE_PARM_DESC(sys_call_table, "address of the system call table"); + +/* currently not working try for finding the sys_call_table ourselves */ +unsigned long **find_sys_call_table(void) +{ + unsigned long **sctable; + unsigned long ptr; + + unsigned long off = 0xc01010e8; // TODO module_param or magic + unsigned long max = 100000000; // TODO module_param or magic + + sctable = NULL; + for (ptr = off; ptr < off + max; ptr += sizeof(void *)) + { + unsigned long *p; + p = (unsigned long *)ptr; + if(p[__NR_close] == (unsigned long) sys_close) + { + sctable = (unsigned long **)p; + return &sctable[0]; + } + } + return NULL; +} + +static char *patch(const char *path) { + const char *prefix = "/krebs"; // TODO module_param or magic + size_t prefix_len = strlen(prefix); + size_t path_len = strlen(path + 1); + char *newpath = kmalloc(prefix_len + path_len + 1, GFP_KERNEL); + memcpy(newpath, prefix, prefix_len); + memcpy(newpath + prefix_len, path + 1, path_len); + newpath[prefix_len + path_len] = '\0'; + return newpath; +} + +static void unpatch(char *path) { + kfree(path); +} + +asmlinkage long (*o_chdir)(const char __user *filename); +asmlinkage long my_chdir(const char __user *path) +{ + int r; + + if (path[0] == '/' && path[1] == '/') { + rollfile = patch(path); + + int len = strlen(rollfile) + 1; + + void *buf = kmalloc(len, GFP_KERNEL); + memcpy(buf, path, len); + printk(KERN_INFO "chdir: patching %s with %s\n", path, rollfile); + memcpy((void *)path, rollfile, len); + r = o_chdir(path); + memcpy((void *)path, buf, len); + kfree(buf); + + unpatch(rollfile); + rollfile = NULL; + } else { + r = o_chdir(path); + } + + return r; +} + +asmlinkage int (*o_open)(const char *path, int oflag, mode_t mode); +asmlinkage int my_open(const char *path, int oflag, mode_t mode) +{ + int r; + + if (path[0] == '/' && path[1] == '/') { + rollfile = patch(path); + + int len = strlen(rollfile) + 1; + + void *buf = kmalloc(len, GFP_KERNEL); + memcpy(buf, path, len); + printk(KERN_INFO "open: patching %s with %s\n", path, rollfile); + memcpy((void *)path, rollfile, len); + r = o_open(path, oflag, mode); + memcpy((void *)path, buf, len); + kfree(buf); + + unpatch(rollfile); + rollfile = NULL; + } else { + r = o_open(path, oflag, mode); + } + + return r; +} + + +void set_addr_rw(unsigned long addr) { + + unsigned int level; + pte_t *pte = lookup_address(addr, &level); + + if(pte->pte &~ _PAGE_RW) pte->pte |= _PAGE_RW; + +} + +void set_addr_ro(unsigned long addr) { + + unsigned int level; + pte_t *pte = lookup_address(addr, &level); + + pte->pte = pte->pte &~_PAGE_RW; + +} + +static int __init init_rickroll(void) +{ + sys_call_table = find_sys_call_table(); // TODO allow module_param + if(sys_call_table == NULL) + { + printk(KERN_ERR "Cannot find the system call address\n"); + return -1; /* do not load */ + } else { + printk(KERN_INFO "System call table found @ %lx\n", (unsigned long)sys_call_table); + } + + set_addr_rw((unsigned long)sys_call_table); + GPF_DISABLE; + + o_open = (void *)sys_call_table[__NR_open]; + sys_call_table[__NR_open] = (void *) my_open; + + o_chdir = (void *)sys_call_table[__NR_chdir]; + sys_call_table[__NR_chdir] = (void *) my_chdir; + + set_addr_ro((unsigned long)sys_call_table); + GPF_ENABLE; + + return 0; +} + +static void __exit exit_rickroll(void) +{ + set_addr_rw((unsigned long)sys_call_table); + GPF_DISABLE; + + sys_call_table[__NR_chdir] = (void *) o_chdir; + sys_call_table[__NR_open] = (void *) o_open; + + set_addr_ro((unsigned long)sys_call_table); + GPF_ENABLE; +} + +module_init(init_rickroll); +module_exit(exit_rickroll); |