tools/net/ynl/lib/ynl.py

   1 # SPDX-License-Identifier: GPL-2.0 OR 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 NlError(Exception):
  71   def __init__(self, nl_msg):
  72     self.nl_msg = nl_msg
  73
  74   def __str__(self):
  75     return f"Netlink error: {os.strerror(-self.nl_msg.error)}\n{self.nl_msg}"
  76
  77
  78 class NlAttr:
  79     type_formats = { 'u8' : ('B', 1), 's8' : ('b', 1),
  80                      'u16': ('H', 2), 's16': ('h', 2),
  81                      'u32': ('I', 4), 's32': ('i', 4),
  82                      'u64': ('Q', 8), 's64': ('q', 8) }
  83
  84     def __init__(self, raw, offset):
  85         self._len, self._type = struct.unpack("HH", raw[offset:offset + 4])
  86         self.type = self._type & ~Netlink.NLA_TYPE_MASK
  87         self.payload_len = self._len
  88         self.full_len = (self.payload_len + 3) & ~3
  89         self.raw = raw[offset + 4:offset + self.payload_len]
  90
  91     def format_byte_order(byte_order):
  92         if byte_order:
  93             return ">" if byte_order == "big-endian" else "<"
  94         return ""
  95
  96     def as_u8(self):
  97         return struct.unpack("B", self.raw)[0]
  98
  99     def as_u16(self, byte_order=None):
 100         endian = NlAttr.format_byte_order(byte_order)
 101         return struct.unpack(f"{endian}H", self.raw)[0]
 102
 103     def as_u32(self, byte_order=None):
 104         endian = NlAttr.format_byte_order(byte_order)
 105         return struct.unpack(f"{endian}I", self.raw)[0]
 106
 107     def as_u64(self, byte_order=None):
 108         endian = NlAttr.format_byte_order(byte_order)
 109         return struct.unpack(f"{endian}Q", self.raw)[0]
 110
 111     def as_strz(self):
 112         return self.raw.decode('ascii')[:-1]
 113
 114     def as_bin(self):
 115         return self.raw
 116
 117     def as_c_array(self, type):
 118         format, _ = self.type_formats[type]
 119         return list({ x[0] for x in struct.iter_unpack(format, self.raw) })
 120
 121     def as_struct(self, members):
 122         value = dict()
 123         offset = 0
 124         for m in members:
 125             # TODO: handle non-scalar members
 126             format, size = self.type_formats[m.type]
 127             decoded = struct.unpack_from(format, self.raw, offset)
 128             offset += size
 129             value[m.name] = decoded[0]
 130         return value
 131
 132     def __repr__(self):
 133         return f"[type:{self.type} len:{self._len}] {self.raw}"
 134
 135
 136 class NlAttrs:
 137     def __init__(self, msg):
 138         self.attrs = []
 139
 140         offset = 0
 141         while offset < len(msg):
 142             attr = NlAttr(msg, offset)
 143             offset += attr.full_len
 144             self.attrs.append(attr)
 145
 146     def __iter__(self):
 147         yield from self.attrs
 148
 149     def __repr__(self):
 150         msg = ''
 151         for a in self.attrs:
 152             if msg:
 153                 msg += '\n'
 154             msg += repr(a)
 155         return msg
 156
 157
 158 class NlMsg:
 159     def __init__(self, msg, offset, attr_space=None):
 160         self.hdr = msg[offset:offset + 16]
 161
 162         self.nl_len, self.nl_type, self.nl_flags, self.nl_seq, self.nl_portid = \
 163             struct.unpack("IHHII", self.hdr)
 164
 165         self.raw = msg[offset + 16:offset + self.nl_len]
 166
 167         self.error = 0
 168         self.done = 0
 169
 170         extack_off = None
 171         if self.nl_type == Netlink.NLMSG_ERROR:
 172             self.error = struct.unpack("i", self.raw[0:4])[0]
 173             self.done = 1
 174             extack_off = 20
 175         elif self.nl_type == Netlink.NLMSG_DONE:
 176             self.done = 1
 177             extack_off = 4
 178
 179         self.extack = None
 180         if self.nl_flags & Netlink.NLM_F_ACK_TLVS and extack_off:
 181             self.extack = dict()
 182             extack_attrs = NlAttrs(self.raw[extack_off:])
 183             for extack in extack_attrs:
 184                 if extack.type == Netlink.NLMSGERR_ATTR_MSG:
 185                     self.extack['msg'] = extack.as_strz()
 186                 elif extack.type == Netlink.NLMSGERR_ATTR_MISS_TYPE:
 187                     self.extack['miss-type'] = extack.as_u32()
 188                 elif extack.type == Netlink.NLMSGERR_ATTR_MISS_NEST:
 189                     self.extack['miss-nest'] = extack.as_u32()
 190                 elif extack.type == Netlink.NLMSGERR_ATTR_OFFS:
 191                     self.extack['bad-attr-offs'] = extack.as_u32()
 192                 else:
 193                     if 'unknown' not in self.extack:
 194                         self.extack['unknown'] = []
 195                     self.extack['unknown'].append(extack)
 196
 197             if attr_space:
 198                 # We don't have the ability to parse nests yet, so only do global
 199                 if 'miss-type' in self.extack and 'miss-nest' not in self.extack:
 200                     miss_type = self.extack['miss-type']
 201                     if miss_type in attr_space.attrs_by_val:
 202                         spec = attr_space.attrs_by_val[miss_type]
 203                         desc = spec['name']
 204                         if 'doc' in spec:
 205                             desc += f" ({spec['doc']})"
 206                         self.extack['miss-type'] = desc
 207
 208     def __repr__(self):
 209         msg = f"nl_len = {self.nl_len} ({len(self.raw)}) nl_flags = 0x{self.nl_flags:x} nl_type = {self.nl_type}\n"
 210         if self.error:
 211             msg += '\terror: ' + str(self.error)
 212         if self.extack:
 213             msg += '\textack: ' + repr(self.extack)
 214         return msg
 215
 216
 217 class NlMsgs:
 218     def __init__(self, data, attr_space=None):
 219         self.msgs = []
 220
 221         offset = 0
 222         while offset < len(data):
 223             msg = NlMsg(data, offset, attr_space=attr_space)
 224             offset += msg.nl_len
 225             self.msgs.append(msg)
 226
 227     def __iter__(self):
 228         yield from self.msgs
 229
 230
 231 genl_family_name_to_id = None
 232
 233
 234 def _genl_msg(nl_type, nl_flags, genl_cmd, genl_version, seq=None):
 235     # we prepend length in _genl_msg_finalize()
 236     if seq is None:
 237         seq = random.randint(1, 1024)
 238     nlmsg = struct.pack("HHII", nl_type, nl_flags, seq, 0)
 239     genlmsg = struct.pack("BBH", genl_cmd, genl_version, 0)
 240     return nlmsg + genlmsg
 241
 242
 243 def _genl_msg_finalize(msg):
 244     return struct.pack("I", len(msg) + 4) + msg
 245
 246
 247 def _genl_load_families():
 248     with socket.socket(socket.AF_NETLINK, socket.SOCK_RAW, Netlink.NETLINK_GENERIC) as sock:
 249         sock.setsockopt(Netlink.SOL_NETLINK, Netlink.NETLINK_CAP_ACK, 1)
 250
 251         msg = _genl_msg(Netlink.GENL_ID_CTRL,
 252                         Netlink.NLM_F_REQUEST | Netlink.NLM_F_ACK | Netlink.NLM_F_DUMP,
 253                         Netlink.CTRL_CMD_GETFAMILY, 1)
 254         msg = _genl_msg_finalize(msg)
 255
 256         sock.send(msg, 0)
 257
 258         global genl_family_name_to_id
 259         genl_family_name_to_id = dict()
 260
 261         while True:
 262             reply = sock.recv(128 * 1024)
 263             nms = NlMsgs(reply)
 264             for nl_msg in nms:
 265                 if nl_msg.error:
 266                     print("Netlink error:", nl_msg.error)
 267                     return
 268                 if nl_msg.done:
 269                     return
 270
 271                 gm = GenlMsg(nl_msg)
 272                 fam = dict()
 273                 for attr in gm.raw_attrs:
 274                     if attr.type == Netlink.CTRL_ATTR_FAMILY_ID:
 275                         fam['id'] = attr.as_u16()
 276                     elif attr.type == Netlink.CTRL_ATTR_FAMILY_NAME:
 277                         fam['name'] = attr.as_strz()
 278                     elif attr.type == Netlink.CTRL_ATTR_MAXATTR:
 279                         fam['maxattr'] = attr.as_u32()
 280                     elif attr.type == Netlink.CTRL_ATTR_MCAST_GROUPS:
 281                         fam['mcast'] = dict()
 282                         for entry in NlAttrs(attr.raw):
 283                             mcast_name = None
 284                             mcast_id = None
 285                             for entry_attr in NlAttrs(entry.raw):
 286                                 if entry_attr.type == Netlink.CTRL_ATTR_MCAST_GRP_NAME:
 287                                     mcast_name = entry_attr.as_strz()
 288                                 elif entry_attr.type == Netlink.CTRL_ATTR_MCAST_GRP_ID:
 289                                     mcast_id = entry_attr.as_u32()
 290                             if mcast_name and mcast_id is not None:
 291                                 fam['mcast'][mcast_name] = mcast_id
 292                 if 'name' in fam and 'id' in fam:
 293                     genl_family_name_to_id[fam['name']] = fam
 294
 295
 296 class GenlMsg:
 297     def __init__(self, nl_msg, fixed_header_members=[]):
 298         self.nl = nl_msg
 299
 300         self.hdr = nl_msg.raw[0:4]
 301         offset = 4
 302
 303         self.genl_cmd, self.genl_version, _ = struct.unpack("BBH", self.hdr)
 304
 305         self.fixed_header_attrs = dict()
 306         for m in fixed_header_members:
 307             format, size = NlAttr.type_formats[m.type]
 308             decoded = struct.unpack_from(format, nl_msg.raw, offset)
 309             offset += size
 310             self.fixed_header_attrs[m.name] = decoded[0]
 311
 312         self.raw = nl_msg.raw[offset:]
 313         self.raw_attrs = NlAttrs(self.raw)
 314
 315     def __repr__(self):
 316         msg = repr(self.nl)
 317         msg += f"\tgenl_cmd = {self.genl_cmd} genl_ver = {self.genl_version}\n"
 318         for a in self.raw_attrs:
 319             msg += '\t\t' + repr(a) + '\n'
 320         return msg
 321
 322
 323 class GenlFamily:
 324     def __init__(self, family_name):
 325         self.family_name = family_name
 326
 327         global genl_family_name_to_id
 328         if genl_family_name_to_id is None:
 329             _genl_load_families()
 330
 331         self.genl_family = genl_family_name_to_id[family_name]
 332         self.family_id = genl_family_name_to_id[family_name]['id']
 333
 334
 335 #
 336 # YNL implementation details.
 337 #
 338
 339
 340 class YnlFamily(SpecFamily):
 341     def __init__(self, def_path, schema=None):
 342         super().__init__(def_path, schema)
 343
 344         self.include_raw = False
 345
 346         self.sock = socket.socket(socket.AF_NETLINK, socket.SOCK_RAW, Netlink.NETLINK_GENERIC)
 347         self.sock.setsockopt(Netlink.SOL_NETLINK, Netlink.NETLINK_CAP_ACK, 1)
 348         self.sock.setsockopt(Netlink.SOL_NETLINK, Netlink.NETLINK_EXT_ACK, 1)
 349
 350         self.async_msg_ids = set()
 351         self.async_msg_queue = []
 352
 353         for msg in self.msgs.values():
 354             if msg.is_async:
 355                 self.async_msg_ids.add(msg.rsp_value)
 356
 357         for op_name, op in self.ops.items():
 358             bound_f = functools.partial(self._op, op_name)
 359             setattr(self, op.ident_name, bound_f)
 360
 361         try:
 362             self.family = GenlFamily(self.yaml['name'])
 363         except KeyError:
 364             raise Exception(f"Family '{self.yaml['name']}' not supported by the kernel")
 365
 366     def ntf_subscribe(self, mcast_name):
 367         if mcast_name not in self.family.genl_family['mcast']:
 368             raise Exception(f'Multicast group "{mcast_name}" not present in the family')
 369
 370         self.sock.bind((0, 0))
 371         self.sock.setsockopt(Netlink.SOL_NETLINK, Netlink.NETLINK_ADD_MEMBERSHIP,
 372                              self.family.genl_family['mcast'][mcast_name])
 373
 374     def _add_attr(self, space, name, value):
 375         attr = self.attr_sets[space][name]
 376         nl_type = attr.value
 377         if attr["type"] == 'nest':
 378             nl_type |= Netlink.NLA_F_NESTED
 379             attr_payload = b''
 380             for subname, subvalue in value.items():
 381                 attr_payload += self._add_attr(attr['nested-attributes'], subname, subvalue)
 382         elif attr["type"] == 'flag':
 383             attr_payload = b''
 384         elif attr["type"] == 'u8':
 385             attr_payload = struct.pack("B", int(value))
 386         elif attr["type"] == 'u16':
 387             endian = NlAttr.format_byte_order(attr.byte_order)
 388             attr_payload = struct.pack(f"{endian}H", int(value))
 389         elif attr["type"] == 'u32':
 390             endian = NlAttr.format_byte_order(attr.byte_order)
 391             attr_payload = struct.pack(f"{endian}I", int(value))
 392         elif attr["type"] == 'u64':
 393             endian = NlAttr.format_byte_order(attr.byte_order)
 394             attr_payload = struct.pack(f"{endian}Q", int(value))
 395         elif attr["type"] == 'string':
 396             attr_payload = str(value).encode('ascii') + b'\x00'
 397         elif attr["type"] == 'binary':
 398             attr_payload = value
 399         else:
 400             raise Exception(f'Unknown type at {space} {name} {value} {attr["type"]}')
 401
 402         pad = b'\x00' * ((4 - len(attr_payload) % 4) % 4)
 403         return struct.pack('HH', len(attr_payload) + 4, nl_type) + attr_payload + pad
 404
 405     def _decode_enum(self, rsp, attr_spec):
 406         raw = rsp[attr_spec['name']]
 407         enum = self.consts[attr_spec['enum']]
 408         i = attr_spec.get('value-start', 0)
 409         if 'enum-as-flags' in attr_spec and attr_spec['enum-as-flags']:
 410             value = set()
 411             while raw:
 412                 if raw & 1:
 413                     value.add(enum.entries_by_val[i].name)
 414                 raw >>= 1
 415                 i += 1
 416         else:
 417             value = enum.entries_by_val[raw - i].name
 418         rsp[attr_spec['name']] = value
 419
 420     def _decode_binary(self, attr, attr_spec):
 421         if attr_spec.struct_name:
 422             decoded = attr.as_struct(self.consts[attr_spec.struct_name])
 423         elif attr_spec.sub_type:
 424             decoded = attr.as_c_array(attr_spec.sub_type)
 425         else:
 426             decoded = attr.as_bin()
 427         return decoded
 428
 429     def _decode(self, attrs, space):
 430         attr_space = self.attr_sets[space]
 431         rsp = dict()
 432         for attr in attrs:
 433             attr_spec = attr_space.attrs_by_val[attr.type]
 434             if attr_spec["type"] == 'nest':
 435                 subdict = self._decode(NlAttrs(attr.raw), attr_spec['nested-attributes'])
 436                 decoded = subdict
 437             elif attr_spec['type'] == 'u8':
 438                 decoded = attr.as_u8()
 439             elif attr_spec['type'] == 'u16':
 440                 decoded = attr.as_u16(attr_spec.byte_order)
 441             elif attr_spec['type'] == 'u32':
 442                 decoded = attr.as_u32(attr_spec.byte_order)
 443             elif attr_spec['type'] == 'u64':
 444                 decoded = attr.as_u64(attr_spec.byte_order)
 445             elif attr_spec["type"] == 'string':
 446                 decoded = attr.as_strz()
 447             elif attr_spec["type"] == 'binary':
 448                 decoded = self._decode_binary(attr, attr_spec)
 449             elif attr_spec["type"] == 'flag':
 450                 decoded = True
 451             else:
 452                 raise Exception(f'Unknown {attr.type} {attr_spec["name"]} {attr_spec["type"]}')
 453
 454             if not attr_spec.is_multi:
 455                 rsp[attr_spec['name']] = decoded
 456             elif attr_spec.name in rsp:
 457                 rsp[attr_spec.name].append(decoded)
 458             else:
 459                 rsp[attr_spec.name] = [decoded]
 460
 461             if 'enum' in attr_spec:
 462                 self._decode_enum(rsp, attr_spec)
 463         return rsp
 464
 465     def _decode_extack_path(self, attrs, attr_set, offset, target):
 466         for attr in attrs:
 467             attr_spec = attr_set.attrs_by_val[attr.type]
 468             if offset > target:
 469                 break
 470             if offset == target:
 471                 return '.' + attr_spec.name
 472
 473             if offset + attr.full_len <= target:
 474                 offset += attr.full_len
 475                 continue
 476             if attr_spec['type'] != 'nest':
 477                 raise Exception(f"Can't dive into {attr.type} ({attr_spec['name']}) for extack")
 478             offset += 4
 479             subpath = self._decode_extack_path(NlAttrs(attr.raw),
 480                                                self.attr_sets[attr_spec['nested-attributes']],
 481                                                offset, target)
 482             if subpath is None:
 483                 return None
 484             return '.' + attr_spec.name + subpath
 485
 486         return None
 487
 488     def _decode_extack(self, request, attr_space, extack):
 489         if 'bad-attr-offs' not in extack:
 490             return
 491
 492         genl_req = GenlMsg(NlMsg(request, 0, attr_space=attr_space))
 493         path = self._decode_extack_path(genl_req.raw_attrs, attr_space,
 494                                         20, extack['bad-attr-offs'])
 495         if path:
 496             del extack['bad-attr-offs']
 497             extack['bad-attr'] = path
 498
 499     def handle_ntf(self, nl_msg, genl_msg):
 500         msg = dict()
 501         if self.include_raw:
 502             msg['nlmsg'] = nl_msg
 503             msg['genlmsg'] = genl_msg
 504         op = self.rsp_by_value[genl_msg.genl_cmd]
 505         msg['name'] = op['name']
 506         msg['msg'] = self._decode(genl_msg.raw_attrs, op.attr_set.name)
 507         self.async_msg_queue.append(msg)
 508
 509     def check_ntf(self):
 510         while True:
 511             try:
 512                 reply = self.sock.recv(128 * 1024, socket.MSG_DONTWAIT)
 513             except BlockingIOError:
 514                 return
 515
 516             nms = NlMsgs(reply)
 517             for nl_msg in nms:
 518                 if nl_msg.error:
 519                     print("Netlink error in ntf!?", os.strerror(-nl_msg.error))
 520                     print(nl_msg)
 521                     continue
 522                 if nl_msg.done:
 523                     print("Netlink done while checking for ntf!?")
 524                     continue
 525
 526                 gm = GenlMsg(nl_msg)
 527                 if gm.genl_cmd not in self.async_msg_ids:
 528                     print("Unexpected msg id done while checking for ntf", gm)
 529                     continue
 530
 531                 self.handle_ntf(nl_msg, gm)
 532
 533     def operation_do_attributes(self, name):
 534       """
 535       For a given operation name, find and return a supported
 536       set of attributes (as a dict).
 537       """
 538       op = self.find_operation(name)
 539       if not op:
 540         return None
 541
 542       return op['do']['request']['attributes'].copy()
 543
 544     def _op(self, method, vals, dump=False):
 545         op = self.ops[method]
 546
 547         nl_flags = Netlink.NLM_F_REQUEST | Netlink.NLM_F_ACK
 548         if dump:
 549             nl_flags |= Netlink.NLM_F_DUMP
 550
 551         req_seq = random.randint(1024, 65535)
 552         msg = _genl_msg(self.family.family_id, nl_flags, op.req_value, 1, req_seq)
 553         fixed_header_members = []
 554         if op.fixed_header:
 555             fixed_header_members = self.consts[op.fixed_header].members
 556             for m in fixed_header_members:
 557                 value = vals.pop(m.name)
 558                 format, _ = NlAttr.type_formats[m.type]
 559                 msg += struct.pack(format, value)
 560         for name, value in vals.items():
 561             msg += self._add_attr(op.attr_set.name, name, value)
 562         msg = _genl_msg_finalize(msg)
 563
 564         self.sock.send(msg, 0)
 565
 566         done = False
 567         rsp = []
 568         while not done:
 569             reply = self.sock.recv(128 * 1024)
 570             nms = NlMsgs(reply, attr_space=op.attr_set)
 571             for nl_msg in nms:
 572                 if nl_msg.extack:
 573                     self._decode_extack(msg, op.attr_set, nl_msg.extack)
 574
 575                 if nl_msg.error:
 576                     raise NlError(nl_msg)
 577                 if nl_msg.done:
 578                     if nl_msg.extack:
 579                         print("Netlink warning:")
 580                         print(nl_msg)
 581                     done = True
 582                     break
 583
 584                 gm = GenlMsg(nl_msg, fixed_header_members)
 585                 # Check if this is a reply to our request
 586                 if nl_msg.nl_seq != req_seq or gm.genl_cmd != op.rsp_value:
 587                     if gm.genl_cmd in self.async_msg_ids:
 588                         self.handle_ntf(nl_msg, gm)
 589                         continue
 590                     else:
 591                         print('Unexpected message: ' + repr(gm))
 592                         continue
 593
 594                 rsp_msg = self._decode(gm.raw_attrs, op.attr_set.name)
 595                 rsp_msg.update(gm.fixed_header_attrs)
 596                 rsp.append(rsp_msg)
 597
 598         if not rsp:
 599             return None
 600         if not dump and len(rsp) == 1:
 601             return rsp[0]
 602         return rsp
 603
 604     def do(self, method, vals):
 605         return self._op(method, vals)
 606
 607     def dump(self, method, vals):
 608         return self._op(method, vals, dump=True)