CVE-2015-6240 (Python, published 2017-06-07T20:29Z)
Description: value: The chroot, jail, and zone connection plugins in ansible before 1.9.2 allow local users to escape a restricted environment via a symlink attack.
Severity: HIGH (CVSS v3 base score: 7.8)
Weakness: CWE-59 \u2014 Improper Link Resolution Before File Access ('Link Following')
The product attempts to access a file based on the filename, but it does not properly prevent that filename from identifying a link or shortcut that resolves to an unintended resource.
Repository: https://github.com/ansible/ansible
Files changed:
lib/ansible/plugins/connections/chroot.py
Commit message: Fix problem with chroot connection plugins and symlinks from within the chroot.


Vulnerable code:
import shutil
    def exec_command(self, cmd, tmp_path, become_user=None, sudoable=False, executable='/bin/sh', in_data=None):
        ''' run a command on the chroot '''

        if executable:
            local_cmd = [self.chroot_cmd, self.chroot, executable, '-c', cmd]
        else:
            local_cmd = '%s "%s" %s' % (self.chroot_cmd, self.chroot, cmd)
                             stdin=subprocess.PIPE,
        if not out_path.startswith(os.path.sep):
            out_path = os.path.join(os.path.sep, out_path)
        normpath = os.path.normpath(out_path)
        out_path = os.path.join(self.chroot, normpath[1:])

        if not os.path.exists(in_path):
            raise errors.AnsibleFileNotFound("file or module does not exist: %s" % in_path)
            shutil.copyfile(in_path, out_path)
        except shutil.Error:
            traceback.print_exc()
            raise errors.AnsibleError("failed to copy: %s and %s are the same" % (in_path, out_path))
            traceback.print_exc()
            raise errors.AnsibleError("failed to transfer file to %s" % out_path)
        if not in_path.startswith(os.path.sep):
            in_path = os.path.join(os.path.sep, in_path)
        normpath = os.path.normpath(in_path)
        in_path = os.path.join(self.chroot, normpath[1:])

        if not os.path.exists(in_path):
            raise errors.AnsibleFileNotFound("file or module does not exist: %s" % in_path)
            shutil.copyfile(in_path, out_path)
        except shutil.Error:
            traceback.print_exc()
            raise errors.AnsibleError("failed to copy: %s and %s are the same" % (in_path, out_path))
        except IOError:
            traceback.print_exc()
            raise errors.AnsibleError("failed to transfer file to %s" % out_path)

Fixed code:
# (c) 2015, Toshio Kuratomi <tkuratomi@ansible.com>
BUFSIZE = 65536

    def _generate_cmd(self, executable, cmd):
        if executable:
            local_cmd = [self.chroot_cmd, self.chroot, executable, '-c', cmd]
        else:
            local_cmd = '%s "%s" %s' % (self.chroot_cmd, self.chroot, cmd)
        return local_cmd

    def _buffered_exec_command(self, cmd, tmp_path, become_user=None, sudoable=False, executable='/bin/sh', in_data=None, stdin=subprocess.PIPE):
        ''' run a command on the chroot.  This is only needed for implementing
        put_file() get_file() so that we don't have to read the whole file
        into memory.

        compared to exec_command() it looses some niceties like being able to
        return the process's exit code immediately.
        '''
        local_cmd = self._generate_cmd(executable, cmd)
                             stdin=stdin,
        return p

    def exec_command(self, cmd, tmp_path, become_user=None, sudoable=False, executable='/bin/sh', in_data=None):
        ''' run a command on the chroot '''

        p = self._buffered_exec_command(cmd, tmp_path, become_user, sudoable, executable, in_data)


            with open(in_path, 'rb') as in_file:
                try:
                    p = self._buffered_exec_command('dd of=%s' % out_path, None, stdin=in_file)
                except OSError:
                    raise errors.AnsibleError("chroot connection requires dd command in the chroot")
                try:
                    stdout, stderr = p.communicate()
                except:
                    traceback.print_exc()
                    raise errors.AnsibleError("failed to transfer file %s to %s" % (in_path, out_path))
                if p.returncode != 0:
                    raise errors.AnsibleError("failed to transfer file %s to %s:\n%s\n%s" % (in_path, out_path, stdout, stderr))
            raise errors.AnsibleError("file or module does not exist at: %s" % in_path)

            p = self._buffered_exec_command('dd if=%s bs=%s' % (in_path, BUFSIZE), None)
        except OSError:
            raise errors.AnsibleError("chroot connection requires dd command in the jail")

        with open(out_path, 'wb+') as out_file:
            try:
                for chunk in p.stdout.read(BUFSIZE):
                    out_file.write(chunk)
            except:
                traceback.print_exc()
                raise errors.AnsibleError("failed to transfer file %s to %s" % (in_path, out_path))
            stdout, stderr = p.communicate()
            if p.returncode != 0:
                raise errors.AnsibleError("failed to transfer file %s to %s:\n%s\n%s" % (in_path, out_path, stdout, stderr))