ethtool: use GPERMADDR instead the ethtool command line tool

This patch implements the ETHTOOL_GPERMADDR command in order to retrieve
the permanent address from ethtool instead using command line tool.

Signed-off-by: Fernando Fernandez Mancera <ffmancera@riseup.net>

defaults/main.yml

@@ -34,7 +34,7 @@ _network_packages_default_gobject_packages: ["python{{
       ansible_python['version']['major'] | replace('2', '')}}-gobject-base"]
 
 network_service_name_default_nm: NetworkManager
-network_packages_default_nm: "{{ ['ethtool', 'NetworkManager']
+network_packages_default_nm: "{{['NetworkManager']
       + _network_packages_default_gobject_packages|select()|list()
       + _network_packages_default_802_1x|select()|list()}}"
 
@@ -56,8 +56,8 @@ if ansible_distribution in ['RedHat', 'CentOS', 'OracleLinux'] and
 # |select() filters the list to include only values that evaluate to true
 #     (the empty string is false)
 # |list() converts the generator that |select() creates to a list
-network_packages_default_initscripts: "{{ ['ethtool']
-+ _network_packages_default_initscripts_bridge|select()|list()
+network_packages_default_initscripts: "{{
+_network_packages_default_initscripts_bridge|select()|list()
 + _network_packages_default_initscripts_network_scripts|select()|list()
 }}"
 

library/network_connections.py

@@ -13,19 +13,21 @@ import traceback
 
 # pylint: disable=import-error, no-name-in-module
 from ansible.module_utils.basic import AnsibleModule
+from ansible.module_utils.network_lsr import ethtool
 from ansible.module_utils.network_lsr import MyError
 
-# pylint: disable=import-error
 from ansible.module_utils.network_lsr.argument_validator import (
     ArgUtil,
     ArgValidator_ListConnections,
     ValidationError,
 )
 
-# pylint: disable=import-error
 from ansible.module_utils.network_lsr.utils import Util
 from ansible.module_utils.network_lsr import nm_provider
 
+# pylint: enable=import-error, no-name-in-module
+
+
 DOCUMENTATION = """
 ---
 module: network_connections
@@ -107,15 +109,7 @@ class SysUtil:
 
     @staticmethod
     def _link_read_permaddress(ifname):
-        try:
-            out = Util.check_output(["ethtool", "-P", ifname])
-        except MyError:
-            return None
-
-        m = re.match("^Permanent address: ([0-9A-Fa-f:]*)\n$", out)
-        if not m:
-            return None
-        return Util.mac_norm(m.group(1))
+        return ethtool.get_perm_addr(ifname)
 
     @staticmethod
     def _link_infos_fetch():

module_utils/network_lsr/ethtool.py

@@ -0,0 +1,56 @@
+# SPDX-License-Identifier: BSD-3-Clause
+
+import array
+import struct
+import fcntl
+import socket
+
+from .utils import Util
+
+ETHTOOL_GPERMADDR = 0x00000020
+SIOCETHTOOL = 0x8946
+MAX_ADDR_LEN = 32
+IFNAMESIZ = 16
+
+
+def get_perm_addr(ifname):
+    """
+    Return the Permanent address value for the specified interface using the
+    ETHTOOL_GPERMADDR ioctl command.
+
+    Please for further documentation, see:
+    https://github.com/torvalds/linux/blob/master/include/uapi/linux/ethtool.h#L734
+    https://github.com/torvalds/linux/blob/master/include/uapi/linux/ethtool.h#L1388
+    https://git.kernel.org/pub/scm/network/ethtool/ethtool.git/tree/ethtool.c#n4172
+    """
+    try:
+        sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+        sockfd = sock.fileno()
+        ifname = ifname.encode("utf-8")
+        if len(ifname) > IFNAMESIZ:
+            return None
+
+        ecmd = array.array(
+            "B",
+            struct.pack(
+                "II%is" % MAX_ADDR_LEN,
+                ETHTOOL_GPERMADDR,
+                MAX_ADDR_LEN,
+                b"\x00" * MAX_ADDR_LEN,
+            ),
+        )
+        ifreq = struct.pack("%isP" % IFNAMESIZ, ifname, ecmd.buffer_info()[0])
+
+        fcntl.ioctl(sockfd, SIOCETHTOOL, ifreq)
+        try:
+            res = ecmd.tobytes()
+        except AttributeError:  # tobytes() is not available in python2
+            res = ecmd.tostring()
+        _, size, perm_addr = struct.unpack("II%is" % MAX_ADDR_LEN, res)
+        perm_addr = Util.mac_ntoa(perm_addr[:size])
+    except IOError:
+        perm_addr = None
+    finally:
+        sock.close()
+
+    return perm_addr

module_utils/network_lsr/utils.py

@@ -2,9 +2,7 @@
 # SPDX-License-Identifier: BSD-3-Clause
 # vim: fileencoding=utf8
 
-import os
 import socket
-import subprocess
 import sys
 import uuid
 
@@ -25,19 +23,6 @@ class Util:
                 return v
         return default
 
-    @staticmethod
-    def check_output(argv):
-        # subprocess.check_output is python 2.7.
-        with open("/dev/null", "wb") as DEVNULL:
-            env = os.environ.copy()
-            env["LANG"] = "C"
-            p = subprocess.Popen(argv, stdout=subprocess.PIPE, stderr=DEVNULL, env=env)
-            # FIXME: Can we assume this to always be UTF-8?
-            out = p.communicate()[0].decode("UTF-8")
-            if p.returncode != 0:
-                raise MyError("failure calling %s: exit with %s" % (argv, p.returncode))
-        return out
-
     @staticmethod
     def path_to_glib_bytes(path):
         """
@@ -275,7 +260,8 @@ class Util:
     def mac_ntoa(mac):
         if mac is None:
             return None
-        return ":".join(["%02x" % c for c in mac])
+        # bytearray() is needed for python2 compatibility
+        return ":".join(["%02x" % c for c in bytearray(mac)])
 
     @staticmethod
     def mac_norm(mac_str, force_len=None):

tests/unit/helpers/ethtool

@@ -1,6 +0,0 @@
-#! /bin/bash
-
-if [ "${1}" == "-P" ] && [ "${2}" != "" ]
-then
-    echo "Permanent address: 23:00:00:00:00:00"
-fi

tests/unit/test_network_connections.py

@@ -2503,10 +2503,9 @@ class TestNM(unittest.TestCase):
 
 
 class TestUtils(unittest.TestCase):
-    def test_check_output(self):
-        res = Util.check_output(["echo", "test"])
-        self.assertEqual(res, "test\n")
-        self.assertRaises(n.MyError, Util.check_output, ["false"])
+    def test_mac_ntoa(self):
+        mac_bytes = b"\xaa\xbb\xcc\xdd\xee\xff"
+        self.assertEqual(Util.mac_ntoa(mac_bytes), "aa:bb:cc:dd:ee:ff")
 
     def test_convert_passwd_flags_nm(self):
         test_cases = [
@@ -2528,10 +2527,9 @@ class TestUtils(unittest.TestCase):
 
 class TestSysUtils(unittest.TestCase):
     def test_link_read_permaddress(self):
-        # Manipulate PATH to use ethtool mock script to avoid hard dependency on
-        # ethtool
-        os.environ["PATH"] = TESTS_BASEDIR + "/helpers:" + os.environ["PATH"]
-        self.assertEqual(SysUtil._link_read_permaddress("lo"), "23:00:00:00:00:00")
+        self.assertEqual(SysUtil._link_read_permaddress("lo"), "00:00:00:00:00:00")
+        self.assertEqual(SysUtil._link_read_permaddress("fakeiface"), None)
+        self.assertEqual(SysUtil._link_read_permaddress("morethansixteenchars"), None)
 
 
 if __name__ == "__main__":