Fix CVE-2017-14176:

https://bugs.launchpad.net/bzr/+bug/1710979
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2017-14176

Patch copied from Debian's Bazaar package version bzr_2.7.0+bzr6619-7+deb9u1:

https://alioth.debian.org/scm/loggerhead/pkg-bazaar/bzr/2.7/revision/4204

Description: Prevent SSH command line options from being specified in bzr+ssh:// URLs
Bug: https://bugs.launchpad.net/brz/+bug/1710979
Bug-Debian: https://bugs.debian.org/874429
Bug-Debian-Security: https://security-tracker.debian.org/tracker/CVE-2017-14176
Forwarded: no
Author: Jelmer Vernooĳ <jelmer@jelmer.uk>
Last-Update: 2017-11-26

=== modified file 'bzrlib/tests/test_ssh_transport.py'
--- old/bzrlib/tests/test_ssh_transport.py	2010-10-07 12:45:51 +0000
+++ new/bzrlib/tests/test_ssh_transport.py	2017-08-20 01:59:20 +0000
@@ -22,6 +22,7 @@
     SSHCorpSubprocessVendor,
     LSHSubprocessVendor,
     SSHVendorManager,
+    StrangeHostname,
     )
 
 
@@ -161,6 +162,19 @@
 
 class SubprocessVendorsTests(TestCase):
 
+    def test_openssh_command_tricked(self):
+        vendor = OpenSSHSubprocessVendor()
+        self.assertEqual(
+            vendor._get_vendor_specific_argv(
+                "user", "-oProxyCommand=blah", 100, command=["bzr"]),
+            ["ssh", "-oForwardX11=no", "-oForwardAgent=no",
+                "-oClearAllForwardings=yes",
+                "-oNoHostAuthenticationForLocalhost=yes",
+                "-p", "100",
+                "-l", "user",
+                "--",
+                "-oProxyCommand=blah", "bzr"])
+
     def test_openssh_command_arguments(self):
         vendor = OpenSSHSubprocessVendor()
         self.assertEqual(
@@ -171,6 +185,7 @@
                 "-oNoHostAuthenticationForLocalhost=yes",
                 "-p", "100",
                 "-l", "user",
+                "--",
                 "host", "bzr"]
             )
 
@@ -184,9 +199,16 @@
                 "-oNoHostAuthenticationForLocalhost=yes",
                 "-p", "100",
                 "-l", "user",
-                "-s", "host", "sftp"]
+                "-s", "--", "host", "sftp"]
             )
 
+    def test_openssh_command_tricked(self):
+        vendor = SSHCorpSubprocessVendor()
+        self.assertRaises(
+            StrangeHostname,
+            vendor._get_vendor_specific_argv,
+                "user", "-oProxyCommand=host", 100, command=["bzr"])
+
     def test_sshcorp_command_arguments(self):
         vendor = SSHCorpSubprocessVendor()
         self.assertEqual(
@@ -209,6 +231,13 @@
                 "-s", "sftp", "host"]
             )
 
+    def test_lsh_command_tricked(self):
+        vendor = LSHSubprocessVendor()
+        self.assertRaises(
+            StrangeHostname,
+            vendor._get_vendor_specific_argv,
+                "user", "-oProxyCommand=host", 100, command=["bzr"])
+
     def test_lsh_command_arguments(self):
         vendor = LSHSubprocessVendor()
         self.assertEqual(
@@ -231,6 +260,13 @@
                 "--subsystem", "sftp", "host"]
             )
 
+    def test_plink_command_tricked(self):
+        vendor = PLinkSubprocessVendor()
+        self.assertRaises(
+            StrangeHostname,
+            vendor._get_vendor_specific_argv,
+                "user", "-oProxyCommand=host", 100, command=["bzr"])
+
     def test_plink_command_arguments(self):
         vendor = PLinkSubprocessVendor()
         self.assertEqual(

=== modified file 'bzrlib/transport/ssh.py'
--- old/bzrlib/transport/ssh.py	2015-07-31 01:04:41 +0000
+++ new/bzrlib/transport/ssh.py	2017-08-20 01:59:20 +0000
@@ -46,6 +46,10 @@
     from paramiko.sftp_client import SFTPClient
 
 
+class StrangeHostname(errors.BzrError):
+    _fmt = "Refusing to connect to strange SSH hostname %(hostname)s"
+
+
 SYSTEM_HOSTKEYS = {}
 BZR_HOSTKEYS = {}
 
@@ -360,6 +364,11 @@
     # tests, but beware of using PIPE which may hang due to not being read.
     _stderr_target = None
 
+    @staticmethod
+    def _check_hostname(arg):
+        if arg.startswith('-'):
+            raise StrangeHostname(hostname=arg)
+
     def _connect(self, argv):
         # Attempt to make a socketpair to use as stdin/stdout for the SSH
         # subprocess.  We prefer sockets to pipes because they support
@@ -424,9 +433,9 @@
         if username is not None:
             args.extend(['-l', username])
         if subsystem is not None:
-            args.extend(['-s', host, subsystem])
+            args.extend(['-s', '--', host, subsystem])
         else:
-            args.extend([host] + command)
+            args.extend(['--', host] + command)
         return args
 
 register_ssh_vendor('openssh', OpenSSHSubprocessVendor())
@@ -439,6 +448,7 @@
 
     def _get_vendor_specific_argv(self, username, host, port, subsystem=None,
                                   command=None):
+        self._check_hostname(host)
         args = [self.executable_path, '-x']
         if port is not None:
             args.extend(['-p', str(port)])
@@ -460,6 +470,7 @@
 
     def _get_vendor_specific_argv(self, username, host, port, subsystem=None,
                                   command=None):
+        self._check_hostname(host)
         args = [self.executable_path]
         if port is not None:
             args.extend(['-p', str(port)])
@@ -481,6 +492,7 @@
 
     def _get_vendor_specific_argv(self, username, host, port, subsystem=None,
                                   command=None):
+        self._check_hostname(host)
         args = [self.executable_path, '-x', '-a', '-ssh', '-2', '-batch']
         if port is not None:
             args.extend(['-P', str(port)])

