tools/net/ynl/lib/ynl.py

   1 # SPDX-License-Identifier: BSD-3-Clause
   2
   3 import functools
   4 import os
   5 import random
   6 import socket
   7 import struct
   8 import yaml
   9
  10 from .nlspec import SpecFamily
  11
  12 #
  13 # Generic Netlink code which should really be in some library, but I can't quickly find one.
  14 #
  15
  16
  17 class Netlink:
  18     # Netlink socket
  19     SOL_NETLINK = 270
  20
  21     NETLINK_ADD_MEMBERSHIP = 1
  22     NETLINK_CAP_ACK = 10
  23     NETLINK_EXT_ACK = 11
  24
  25     # Netlink message
  26     NLMSG_ERROR = 2
  27     NLMSG_DONE = 3
  28
  29     NLM_F_REQUEST = 1
  30     NLM_F_ACK = 4
  31     NLM_F_ROOT = 0x100
  32     NLM_F_MATCH = 0x200
  33     NLM_F_APPEND = 0x800
  34
  35     NLM_F_CAPPED = 0x100
  36     NLM_F_ACK_TLVS = 0x200
  37
  38     NLM_F_DUMP = NLM_F_ROOT | NLM_F_MATCH
  39
  40     NLA_F_NESTED = 0x8000
  41     NLA_F_NET_BYTEORDER = 0x4000
  42
  43     NLA_TYPE_MASK = NLA_F_NESTED | NLA_F_NET_BYTEORDER
  44
  45     # Genetlink defines
  46     NETLINK_GENERIC = 16
  47
  48     GENL_ID_CTRL = 0x10
  49
  50     # nlctrl
  51     CTRL_CMD_GETFAMILY = 3
  52
  53     CTRL_ATTR_FAMILY_ID = 1
  54     CTRL_ATTR_FAMILY_NAME = 2
  55     CTRL_ATTR_MAXATTR = 5
  56     CTRL_ATTR_MCAST_GROUPS = 7
  57
  58     CTRL_ATTR_MCAST_GRP_NAME = 1
  59     CTRL_ATTR_MCAST_GRP_ID = 2
  60
  61     # Extack types
  62     NLMSGERR_ATTR_MSG = 1
  63     NLMSGERR_ATTR_OFFS = 2
  64     NLMSGERR_ATTR_COOKIE = 3
  65     NLMSGERR_ATTR_POLICY = 4
  66     NLMSGERR_ATTR_MISS_TYPE = 5
  67     NLMSGERR_ATTR_MISS_NEST = 6
  68
  69
  70 class NlAttr:
  71     def __init__(self, raw, offset):
  72         self._len, self._type = struct.unpack("HH", raw[offset:offset + 4])
  73         self.type = self._type & ~Netlink.NLA_TYPE_MASK
  74         self.payload_len = self._len
  75         self.full_len = (self.payload_len + 3) & ~3
  76         self.raw = raw[offset + 4:offset + self.payload_len]
  77
  78     def as_u8(self):
  79         return struct.unpack("B", self.raw)[0]
  80
  81     def as_u16(self):
  82         return struct.unpack("H", self.raw)[0]
  83
  84     def as_u32(self):
  85         return struct.unpack("I", self.raw)[0]
  86
  87     def as_u64(self):
  88         return struct.unpack("Q", self.raw)[0]
  89
  90     def as_strz(self):
  91         return self.raw.decode('ascii')[:-1]
  92
  93     def as_bin(self):
  94         return self.raw
  95
  96     def __repr__(self):
  97         return f"[type:{self.type} len:{self._len}] {self.raw}"
  98
  99
 100 class NlAttrs:
 101     def __init__(self, msg):
 102         self.attrs = []
 103
 104         offset = 0
 105         while offset < len(msg):
 106             attr = NlAttr(msg, offset)
 107             offset += attr.full_len
 108             self.attrs.append(attr)
 109
 110     def __iter__(self):
 111         yield from self.attrs
 112
 113     def __repr__(self):
 114         msg = ''
 115         for a in self.attrs:
 116             if msg:
 117                 msg += '\n'
 118             msg += repr(a)
 119         return msg
 120
 121
 122 class NlMsg:
 123     def __init__(self, msg, offset, attr_space=None):
 124         self.hdr = msg[offset:offset + 16]
 125
 126         self.nl_len, self.nl_type, self.nl_flags, self.nl_seq, self.nl_portid = \
 127             struct.unpack("IHHII", self.hdr)
 128
 129         self.raw = msg[offset + 16:offset + self.nl_len]
 130
 131         self.error = 0
 132         self.done = 0
 133
 134         extack_off = None
 135         if self.nl_type == Netlink.NLMSG_ERROR:
 136             self.error = struct.unpack("i", self.raw[0:4])[0]
 137             self.done = 1
 138             extack_off = 20
 139         elif self.nl_type == Netlink.NLMSG_DONE:
 140             self.done = 1
 141             extack_off = 4
 142
 143         self.extack = None
 144         if self.nl_flags & Netlink.NLM_F_ACK_TLVS and extack_off:
 145             self.extack = dict()
 146             extack_attrs = NlAttrs(self.raw[extack_off:])
 147             for extack in extack_attrs:
 148                 if extack.type == Netlink.NLMSGERR_ATTR_MSG:
 149                     self.extack['msg'] = extack.as_strz()
 150                 elif extack.type == Netlink.NLMSGERR_ATTR_MISS_TYPE:
 151                     self.extack['miss-type'] = extack.as_u32()
 152                 elif extack.type == Netlink.NLMSGERR_ATTR_MISS_NEST:
 153                     self.extack['miss-nest'] = extack.as_u32()
 154                 elif extack.type == Netlink.NLMSGERR_ATTR_OFFS:
 155                     self.extack['bad-attr-offs'] = extack.as_u32()
 156                 else:
 157                     if 'unknown' not in self.extack:
 158                         self.extack['unknown'] = []
 159                     self.extack['unknown'].append(extack)
 160
 161             if attr_space:
 162                 # We don't have the ability to parse nests yet, so only do global
 163                 if 'miss-type' in self.extack and 'miss-nest' not in self.extack:
 164                     miss_type = self.extack['miss-type']
 165                     if miss_type in attr_space.attrs_by_val:
 166                         spec = attr_space.attrs_by_val[miss_type]
 167                         desc = spec['name']
 168                         if 'doc' in spec:
 169                             desc += f" ({spec['doc']})"
 170                         self.extack['miss-type'] = desc
 171
 172     def __repr__(self):
 173         msg = f"nl_len = {self.nl_len} ({len(self.raw)}) nl_flags = 0x{self.nl_flags:x} nl_type = {self.nl_type}\n"
 174         if self.error:
 175             msg += '\terror: ' + str(self.error)
 176         if self.extack:
 177             msg += '\textack: ' + repr(self.extack)
 178         return msg
 179
 180
 181 class NlMsgs:
 182     def __init__(self, data, attr_space=None):
 183         self.msgs = []
 184
 185         offset = 0
 186         while offset < len(data):
 187             msg = NlMsg(data, offset, attr_space=attr_space)
 188             offset += msg.nl_len
 189             self.msgs.append(msg)
 190
 191     def __iter__(self):
 192         yield from self.msgs
 193
 194
 195 genl_family_name_to_id = None
 196
 197
 198 def _genl_msg(nl_type, nl_flags, genl_cmd, genl_version, seq=None):
 199     # we prepend length in _genl_msg_finalize()
 200     if seq is None:
 201         seq = random.randint(1, 1024)
 202     nlmsg = struct.pack("HHII", nl_type, nl_flags, seq, 0)
 203     genlmsg = struct.pack("bbH", genl_cmd, genl_version, 0)
 204     return nlmsg + genlmsg
 205
 206
 207 def _genl_msg_finalize(msg):
 208     return struct.pack("I", len(msg) + 4) + msg
 209
 210
 211 def _genl_load_families():
 212     with socket.socket(socket.AF_NETLINK, socket.SOCK_RAW, Netlink.NETLINK_GENERIC) as sock:
 213         sock.setsockopt(Netlink.SOL_NETLINK, Netlink.NETLINK_CAP_ACK, 1)
 214
 215         msg = _genl_msg(Netlink.GENL_ID_CTRL,
 216                         Netlink.NLM_F_REQUEST | Netlink.NLM_F_ACK | Netlink.NLM_F_DUMP,
 217                         Netlink.CTRL_CMD_GETFAMILY, 1)
 218         msg = _genl_msg_finalize(msg)
 219
 220         sock.send(msg, 0)
 221
 222         global genl_family_name_to_id
 223         genl_family_name_to_id = dict()
 224
 225         while True:
 226             reply = sock.recv(128 * 1024)
 227             nms = NlMsgs(reply)
 228             for nl_msg in nms:
 229                 if nl_msg.error:
 230                     print("Netlink error:", nl_msg.error)
 231                     return
 232                 if nl_msg.done:
 233                     return
 234
 235                 gm = GenlMsg(nl_msg)
 236                 fam = dict()
 237                 for attr in gm.raw_attrs:
 238                     if attr.type == Netlink.CTRL_ATTR_FAMILY_ID:
 239                         fam['id'] = attr.as_u16()
 240                     elif attr.type == Netlink.CTRL_ATTR_FAMILY_NAME:
 241                         fam['name'] = attr.as_strz()
 242                     elif attr.type == Netlink.CTRL_ATTR_MAXATTR:
 243                         fam['maxattr'] = attr.as_u32()
 244                     elif attr.type == Netlink.CTRL_ATTR_MCAST_GROUPS:
 245                         fam['mcast'] = dict()
 246                         for entry in NlAttrs(attr.raw):
 247                             mcast_name = None
 248                             mcast_id = None
 249                             for entry_attr in NlAttrs(entry.raw):
 250                                 if entry_attr.type == Netlink.CTRL_ATTR_MCAST_GRP_NAME:
 251                                     mcast_name = entry_attr.as_strz()
 252                                 elif entry_attr.type == Netlink.CTRL_ATTR_MCAST_GRP_ID:
 253                                     mcast_id = entry_attr.as_u32()
 254                             if mcast_name and mcast_id is not None:
 255                                 fam['mcast'][mcast_name] = mcast_id
 256                 if 'name' in fam and 'id' in fam:
 257                     genl_family_name_to_id[fam['name']] = fam
 258
 259
 260 class GenlMsg:
 261     def __init__(self, nl_msg):
 262         self.nl = nl_msg
 263
 264         self.hdr = nl_msg.raw[0:4]
 265         self.raw = nl_msg.raw[4:]
 266
 267         self.genl_cmd, self.genl_version, _ = struct.unpack("bbH", self.hdr)
 268
 269         self.raw_attrs = NlAttrs(self.raw)
 270
 271     def __repr__(self):
 272         msg = repr(self.nl)
 273         msg += f"\tgenl_cmd = {self.genl_cmd} genl_ver = {self.genl_version}\n"
 274         for a in self.raw_attrs:
 275             msg += '\t\t' + repr(a) + '\n'
 276         return msg
 277
 278
 279 class GenlFamily:
 280     def __init__(self, family_name):
 281         self.family_name = family_name
 282
 283         global genl_family_name_to_id
 284         if genl_family_name_to_id is None:
 285             _genl_load_families()
 286
 287         self.genl_family = genl_family_name_to_id[family_name]
 288         self.family_id = genl_family_name_to_id[family_name]['id']
 289
 290
 291 #
 292 # YNL implementation details.
 293 #
 294
 295
 296 class YnlFamily(SpecFamily):
 297     def __init__(self, def_path, schema=None):
 298         super().__init__(def_path, schema)
 299
 300         self.include_raw = False
 301
 302         self.sock = socket.socket(socket.AF_NETLINK, socket.SOCK_RAW, Netlink.NETLINK_GENERIC)
 303         self.sock.setsockopt(Netlink.SOL_NETLINK, Netlink.NETLINK_CAP_ACK, 1)
 304         self.sock.setsockopt(Netlink.SOL_NETLINK, Netlink.NETLINK_EXT_ACK, 1)
 305
 306         self._types = dict()
 307
 308         for elem in self.yaml.get('definitions', []):
 309             self._types[elem['name']] = elem
 310
 311         self.async_msg_ids = set()
 312         self.async_msg_queue = []
 313
 314         for msg in self.msgs.values():
 315             if msg.is_async:
 316                 self.async_msg_ids.add(msg.rsp_value)
 317
 318         for op_name, op in self.ops.items():
 319             bound_f = functools.partial(self._op, op_name)
 320             setattr(self, op.ident_name, bound_f)
 321
 322         self.family = GenlFamily(self.yaml['name'])
 323
 324     def ntf_subscribe(self, mcast_name):
 325         if mcast_name not in self.family.genl_family['mcast']:
 326             raise Exception(f'Multicast group "{mcast_name}" not present in the family')
 327
 328         self.sock.bind((0, 0))
 329         self.sock.setsockopt(Netlink.SOL_NETLINK, Netlink.NETLINK_ADD_MEMBERSHIP,
 330                              self.family.genl_family['mcast'][mcast_name])
 331
 332     def _add_attr(self, space, name, value):
 333         attr = self.attr_sets[space][name]
 334         nl_type = attr.value
 335         if attr["type"] == 'nest':
 336             nl_type |= Netlink.NLA_F_NESTED
 337             attr_payload = b''
 338             for subname, subvalue in value.items():
 339                 attr_payload += self._add_attr(attr['nested-attributes'], subname, subvalue)
 340         elif attr["type"] == 'flag':
 341             attr_payload = b''
 342         elif attr["type"] == 'u32':
 343             attr_payload = struct.pack("I", int(value))
 344         elif attr["type"] == 'string':
 345             attr_payload = str(value).encode('ascii') + b'\x00'
 346         elif attr["type"] == 'binary':
 347             attr_payload = value
 348         else:
 349             raise Exception(f'Unknown type at {space} {name} {value} {attr["type"]}')
 350
 351         pad = b'\x00' * ((4 - len(attr_payload) % 4) % 4)
 352         return struct.pack('HH', len(attr_payload) + 4, nl_type) + attr_payload + pad
 353
 354     def _decode_enum(self, rsp, attr_spec):
 355         raw = rsp[attr_spec['name']]
 356         enum = self._types[attr_spec['enum']]
 357         i = attr_spec.get('value-start', 0)
 358         if 'enum-as-flags' in attr_spec and attr_spec['enum-as-flags']:
 359             value = set()
 360             while raw:
 361                 if raw & 1:
 362                     value.add(enum['entries'][i])
 363                 raw >>= 1
 364                 i += 1
 365         else:
 366             value = enum['entries'][raw - i]
 367         rsp[attr_spec['name']] = value
 368
 369     def _decode(self, attrs, space):
 370         attr_space = self.attr_sets[space]
 371         rsp = dict()
 372         for attr in attrs:
 373             attr_spec = attr_space.attrs_by_val[attr.type]
 374             if attr_spec["type"] == 'nest':
 375                 subdict = self._decode(NlAttrs(attr.raw), attr_spec['nested-attributes'])
 376                 rsp[attr_spec['name']] = subdict
 377             elif attr_spec['type'] == 'u8':
 378                 rsp[attr_spec['name']] = attr.as_u8()
 379             elif attr_spec['type'] == 'u32':
 380                 rsp[attr_spec['name']] = attr.as_u32()
 381             elif attr_spec['type'] == 'u64':
 382                 rsp[attr_spec['name']] = attr.as_u64()
 383             elif attr_spec["type"] == 'string':
 384                 rsp[attr_spec['name']] = attr.as_strz()
 385             elif attr_spec["type"] == 'binary':
 386                 rsp[attr_spec['name']] = attr.as_bin()
 387             elif attr_spec["type"] == 'flag':
 388                 rsp[attr_spec['name']] = True
 389             else:
 390                 raise Exception(f'Unknown {attr.type} {attr_spec["name"]} {attr_spec["type"]}')
 391
 392             if 'enum' in attr_spec:
 393                 self._decode_enum(rsp, attr_spec)
 394         return rsp
 395
 396     def handle_ntf(self, nl_msg, genl_msg):
 397         msg = dict()
 398         if self.include_raw:
 399             msg['nlmsg'] = nl_msg
 400             msg['genlmsg'] = genl_msg
 401         op = self.rsp_by_value[genl_msg.genl_cmd]
 402         msg['name'] = op['name']
 403         msg['msg'] = self._decode(genl_msg.raw_attrs, op.attr_set.name)
 404         self.async_msg_queue.append(msg)
 405
 406     def check_ntf(self):
 407         while True:
 408             try:
 409                 reply = self.sock.recv(128 * 1024, socket.MSG_DONTWAIT)
 410             except BlockingIOError:
 411                 return
 412
 413             nms = NlMsgs(reply)
 414             for nl_msg in nms:
 415                 if nl_msg.error:
 416                     print("Netlink error in ntf!?", os.strerror(-nl_msg.error))
 417                     print(nl_msg)
 418                     continue
 419                 if nl_msg.done:
 420                     print("Netlink done while checking for ntf!?")
 421                     continue
 422
 423                 gm = GenlMsg(nl_msg)
 424                 if gm.genl_cmd not in self.async_msg_ids:
 425                     print("Unexpected msg id done while checking for ntf", gm)
 426                     continue
 427
 428                 self.handle_ntf(nl_msg, gm)
 429
 430     def _op(self, method, vals, dump=False):
 431         op = self.ops[method]
 432
 433         nl_flags = Netlink.NLM_F_REQUEST | Netlink.NLM_F_ACK
 434         if dump:
 435             nl_flags |= Netlink.NLM_F_DUMP
 436
 437         req_seq = random.randint(1024, 65535)
 438         msg = _genl_msg(self.family.family_id, nl_flags, op.req_value, 1, req_seq)
 439         for name, value in vals.items():
 440             msg += self._add_attr(op.attr_set.name, name, value)
 441         msg = _genl_msg_finalize(msg)
 442
 443         self.sock.send(msg, 0)
 444
 445         done = False
 446         rsp = []
 447         while not done:
 448             reply = self.sock.recv(128 * 1024)
 449             nms = NlMsgs(reply, attr_space=op.attr_set)
 450             for nl_msg in nms:
 451                 if nl_msg.error:
 452                     print("Netlink error:", os.strerror(-nl_msg.error))
 453                     print(nl_msg)
 454                     return
 455                 if nl_msg.done:
 456                     done = True
 457                     break
 458
 459                 gm = GenlMsg(nl_msg)
 460                 # Check if this is a reply to our request
 461                 if nl_msg.nl_seq != req_seq or gm.genl_cmd != op.rsp_value:
 462                     if gm.genl_cmd in self.async_msg_ids:
 463                         self.handle_ntf(nl_msg, gm)
 464                         continue
 465                     else:
 466                         print('Unexpected message: ' + repr(gm))
 467                         continue
 468
 469                 rsp.append(self._decode(gm.raw_attrs, op.attr_set.name))
 470
 471         if not rsp:
 472             return None
 473         if not dump and len(rsp) == 1:
 474             return rsp[0]
 475         return rsp