1#!/usr/bin/python
2#
3# Copyright 2015 The Android Open Source Project
4#
5# Licensed under the Apache License, Version 2.0 (the "License");
6# you may not use this file except in compliance with the License.
7# You may obtain a copy of the License at
8#
9# http://www.apache.org/licenses/LICENSE-2.0
10#
11# Unless required by applicable law or agreed to in writing, software
12# distributed under the License is distributed on an "AS IS" BASIS,
13# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14# See the License for the specific language governing permissions and
15# limitations under the License.
16
17"""Partial Python implementation of sock_diag functionality."""
18
19# pylint: disable=g-bad-todo
20
21import errno
22import os
23from socket import *  # pylint: disable=wildcard-import
24import struct
25
26import csocket
27import cstruct
28import net_test
29import netlink
30
31### Base netlink constants. See include/uapi/linux/netlink.h.
32NETLINK_SOCK_DIAG = 4
33
34### sock_diag constants. See include/uapi/linux/sock_diag.h.
35# Message types.
36SOCK_DIAG_BY_FAMILY = 20
37SOCK_DESTROY = 21
38
39### inet_diag_constants. See include/uapi/linux/inet_diag.h
40# Message types.
41TCPDIAG_GETSOCK = 18
42
43# Request attributes.
44INET_DIAG_REQ_BYTECODE = 1
45
46# Extensions.
47INET_DIAG_NONE = 0
48INET_DIAG_MEMINFO = 1
49INET_DIAG_INFO = 2
50INET_DIAG_VEGASINFO = 3
51INET_DIAG_CONG = 4
52INET_DIAG_TOS = 5
53INET_DIAG_TCLASS = 6
54INET_DIAG_SKMEMINFO = 7
55INET_DIAG_SHUTDOWN = 8
56INET_DIAG_DCTCPINFO = 9
57INET_DIAG_DCTCPINFO = 9
58INET_DIAG_PROTOCOL = 10
59INET_DIAG_SKV6ONLY = 11
60INET_DIAG_LOCALS = 12
61INET_DIAG_PEERS = 13
62INET_DIAG_PAD = 14
63INET_DIAG_MARK = 15
64
65# Bytecode operations.
66INET_DIAG_BC_NOP = 0
67INET_DIAG_BC_JMP = 1
68INET_DIAG_BC_S_GE = 2
69INET_DIAG_BC_S_LE = 3
70INET_DIAG_BC_D_GE = 4
71INET_DIAG_BC_D_LE = 5
72INET_DIAG_BC_AUTO = 6
73INET_DIAG_BC_S_COND = 7
74INET_DIAG_BC_D_COND = 8
75INET_DIAG_BC_DEV_COND = 9
76INET_DIAG_BC_MARK_COND = 10
77
78# Data structure formats.
79# These aren't constants, they're classes. So, pylint: disable=invalid-name
80InetDiagSockId = cstruct.Struct(
81    "InetDiagSockId", "!HH16s16sI8s", "sport dport src dst iface cookie")
82InetDiagReqV2 = cstruct.Struct(
83    "InetDiagReqV2", "=BBBxIS", "family protocol ext states id",
84    [InetDiagSockId])
85InetDiagMsg = cstruct.Struct(
86    "InetDiagMsg", "=BBBBSLLLLL",
87    "family state timer retrans id expires rqueue wqueue uid inode",
88    [InetDiagSockId])
89InetDiagMeminfo = cstruct.Struct(
90    "InetDiagMeminfo", "=IIII", "rmem wmem fmem tmem")
91InetDiagBcOp = cstruct.Struct("InetDiagBcOp", "BBH", "code yes no")
92InetDiagHostcond = cstruct.Struct("InetDiagHostcond", "=BBxxi",
93                                  "family prefix_len port")
94InetDiagMarkcond = cstruct.Struct("InetDiagMarkcond", "=II", "mark mask")
95
96SkMeminfo = cstruct.Struct(
97    "SkMeminfo", "=IIIIIIII",
98    "rmem_alloc rcvbuf wmem_alloc sndbuf fwd_alloc wmem_queued optmem backlog")
99TcpInfo = cstruct.Struct(
100    "TcpInfo", "=BBBBBBBxIIIIIIIIIIIIIIIIIIIIIIII",
101    "state ca_state retransmits probes backoff options wscale "
102    "rto ato snd_mss rcv_mss "
103    "unacked sacked lost retrans fackets "
104    "last_data_sent last_ack_sent last_data_recv last_ack_recv "
105    "pmtu rcv_ssthresh rtt rttvar snd_ssthresh snd_cwnd advmss reordering "
106    "rcv_rtt rcv_space "
107    "total_retrans")  # As of linux 3.13, at least.
108
109TCP_TIME_WAIT = 6
110ALL_NON_TIME_WAIT = 0xffffffff & ~(1 << TCP_TIME_WAIT)
111
112
113class SockDiag(netlink.NetlinkSocket):
114
115  FAMILY = NETLINK_SOCK_DIAG
116  NL_DEBUG = []
117
118  def _Decode(self, command, msg, nla_type, nla_data):
119    """Decodes netlink attributes to Python types."""
120    if msg.family == AF_INET or msg.family == AF_INET6:
121      if isinstance(msg, InetDiagReqV2):
122        prefix = "INET_DIAG_REQ"
123      else:
124        prefix = "INET_DIAG"
125      name = self._GetConstantName(__name__, nla_type, prefix)
126    else:
127      # Don't know what this is. Leave it as an integer.
128      name = nla_type
129
130    if name in ["INET_DIAG_SHUTDOWN", "INET_DIAG_TOS", "INET_DIAG_TCLASS",
131                "INET_DIAG_SKV6ONLY"]:
132      data = ord(nla_data)
133    elif name == "INET_DIAG_CONG":
134      data = nla_data.strip("\x00")
135    elif name == "INET_DIAG_MEMINFO":
136      data = InetDiagMeminfo(nla_data)
137    elif name == "INET_DIAG_INFO":
138      # TODO: Catch the exception and try something else if it's not TCP.
139      data = TcpInfo(nla_data)
140    elif name == "INET_DIAG_SKMEMINFO":
141      data = SkMeminfo(nla_data)
142    elif name == "INET_DIAG_MARK":
143      data = struct.unpack("=I", nla_data)[0]
144    elif name == "INET_DIAG_REQ_BYTECODE":
145      data = self.DecodeBytecode(nla_data)
146    elif name in ["INET_DIAG_LOCALS", "INET_DIAG_PEERS"]:
147      data = []
148      while len(nla_data):
149        # The SCTP diag code always appears to copy sizeof(sockaddr_storage)
150        # bytes, but does so from a union sctp_addr which is at most as long
151        # as a sockaddr_in6.
152        addr, nla_data = cstruct.Read(nla_data, csocket.SockaddrStorage)
153        if addr.family == AF_INET:
154          addr = csocket.SockaddrIn(addr.Pack())
155        elif addr.family == AF_INET6:
156          addr = csocket.SockaddrIn6(addr.Pack())
157        data.append(addr)
158    else:
159      data = nla_data
160
161    return name, data
162
163  def MaybeDebugCommand(self, command, unused_flags, data):
164    name = self._GetConstantName(__name__, command, "SOCK_")
165    if "ALL" not in self.NL_DEBUG and "SOCK" not in self.NL_DEBUG:
166      return
167    parsed = self._ParseNLMsg(data, InetDiagReqV2)
168    print "%s %s" % (name, str(parsed))
169
170  @staticmethod
171  def _EmptyInetDiagSockId():
172    return InetDiagSockId(("\x00" * len(InetDiagSockId)))
173
174  @staticmethod
175  def PackBytecode(instructions):
176    """Compiles instructions to inet_diag bytecode.
177
178    The input is a list of (INET_DIAG_BC_xxx, yes, no, arg) tuples, where yes
179    and no are relative jump offsets measured in instructions. The yes branch
180    is taken if the instruction matches.
181
182    To accept, jump 1 past the last instruction. To reject, jump 2 past the
183    last instruction.
184
185    The target of a no jump is only valid if it is reachable by following
186    only yes jumps from the first instruction - see inet_diag_bc_audit and
187    valid_cc. This means that if cond1 and cond2 are two mutually exclusive
188    filter terms, it is not possible to implement cond1 OR cond2 using:
189
190      ...
191      cond1 2 1 arg
192      cond2 1 2 arg
193      accept
194      reject
195
196    but only using:
197
198      ...
199      cond1 1 2 arg
200      jmp   1 2
201      cond2 1 2 arg
202      accept
203      reject
204
205    The jmp instruction ignores yes and always jumps to no, but yes must be 1
206    or the bytecode won't validate. It doesn't have to be jmp - any instruction
207    that is guaranteed not to match on real data will do.
208
209    Args:
210      instructions: list of instruction tuples
211
212    Returns:
213      A string, the raw bytecode.
214    """
215    args = []
216    positions = [0]
217
218    for op, yes, no, arg in instructions:
219
220      if yes <= 0 or no <= 0:
221        raise ValueError("Jumps must be > 0")
222
223      if op in [INET_DIAG_BC_NOP, INET_DIAG_BC_JMP, INET_DIAG_BC_AUTO]:
224        arg = ""
225      elif op in [INET_DIAG_BC_S_GE, INET_DIAG_BC_S_LE,
226                  INET_DIAG_BC_D_GE, INET_DIAG_BC_D_LE]:
227        arg = "\x00\x00" + struct.pack("=H", arg)
228      elif op in [INET_DIAG_BC_S_COND, INET_DIAG_BC_D_COND]:
229        addr, prefixlen, port = arg
230        family = AF_INET6 if ":" in addr else AF_INET
231        addr = inet_pton(family, addr)
232        arg = InetDiagHostcond((family, prefixlen, port)).Pack() + addr
233      elif op == INET_DIAG_BC_MARK_COND:
234        if isinstance(arg, tuple):
235          mark, mask = arg
236        else:
237          mark, mask = arg, 0xffffffff
238        arg = InetDiagMarkcond((mark, mask)).Pack()
239      else:
240        raise ValueError("Unsupported opcode %d" % op)
241
242      args.append(arg)
243      length = len(InetDiagBcOp) + len(arg)
244      positions.append(positions[-1] + length)
245
246    # Reject label.
247    positions.append(positions[-1] + 4)  # Why 4? Because the kernel uses 4.
248    assert len(args) == len(instructions) == len(positions) - 2
249
250    # print positions
251
252    packed = ""
253    for i, (op, yes, no, arg) in enumerate(instructions):
254      yes = positions[i + yes] - positions[i]
255      no = positions[i + no] - positions[i]
256      instruction = InetDiagBcOp((op, yes, no)).Pack() + args[i]
257      #print "%3d: %d %3d %3d %s %s" % (positions[i], op, yes, no,
258      #                                 arg, instruction.encode("hex"))
259      packed += instruction
260    #print
261
262    return packed
263
264  @staticmethod
265  def DecodeBytecode(bytecode):
266    instructions = []
267    try:
268      while bytecode:
269        op, rest = cstruct.Read(bytecode, InetDiagBcOp)
270
271        if op.code in [INET_DIAG_BC_NOP, INET_DIAG_BC_JMP, INET_DIAG_BC_AUTO]:
272          arg = None
273        elif op.code in [INET_DIAG_BC_S_GE, INET_DIAG_BC_S_LE,
274                         INET_DIAG_BC_D_GE, INET_DIAG_BC_D_LE]:
275          op, rest = cstruct.Read(rest, InetDiagBcOp)
276          arg = op.no
277        elif op.code in [INET_DIAG_BC_S_COND, INET_DIAG_BC_D_COND]:
278          cond, rest = cstruct.Read(rest, InetDiagHostcond)
279          if cond.family == 0:
280            arg = (None, cond.prefix_len, cond.port)
281          else:
282            addrlen = 4 if cond.family == AF_INET else 16
283            addr, rest = rest[:addrlen], rest[addrlen:]
284            addr = inet_ntop(cond.family, addr)
285            arg = (addr, cond.prefix_len, cond.port)
286        elif op.code == INET_DIAG_BC_DEV_COND:
287          attrlen = struct.calcsize("=I")
288          attr, rest = rest[:attrlen], rest[attrlen:]
289          arg = struct.unpack("=I", attr)
290        elif op.code == INET_DIAG_BC_MARK_COND:
291          arg, rest = cstruct.Read(rest, InetDiagMarkcond)
292        else:
293          raise ValueError("Unknown opcode %d" % op.code)
294        instructions.append((op, arg))
295        bytecode = rest
296
297      return instructions
298    except (TypeError, ValueError):
299      return "???"
300
301  def Dump(self, diag_req, bytecode):
302    if bytecode:
303      bytecode = self._NlAttr(INET_DIAG_REQ_BYTECODE, bytecode)
304
305    out = self._Dump(SOCK_DIAG_BY_FAMILY, diag_req, InetDiagMsg, bytecode)
306    return out
307
308  def DumpAllInetSockets(self, protocol, bytecode, sock_id=None, ext=0,
309                         states=ALL_NON_TIME_WAIT):
310    """Dumps IPv4 or IPv6 sockets matching the specified parameters."""
311    # DumpSockets(AF_UNSPEC) does not result in dumping all inet sockets, it
312    # results in ENOENT.
313    if sock_id is None:
314      sock_id = self._EmptyInetDiagSockId()
315
316    sockets = []
317    for family in [AF_INET, AF_INET6]:
318      diag_req = InetDiagReqV2((family, protocol, ext, states, sock_id))
319      sockets += self.Dump(diag_req, bytecode)
320
321    return sockets
322
323  @staticmethod
324  def GetRawAddress(family, addr):
325    """Fetches the source address from an InetDiagMsg."""
326    addrlen = {AF_INET:4, AF_INET6: 16}[family]
327    return inet_ntop(family, addr[:addrlen])
328
329  @staticmethod
330  def GetSourceAddress(diag_msg):
331    """Fetches the source address from an InetDiagMsg."""
332    return SockDiag.GetRawAddress(diag_msg.family, diag_msg.id.src)
333
334  @staticmethod
335  def GetDestinationAddress(diag_msg):
336    """Fetches the source address from an InetDiagMsg."""
337    return SockDiag.GetRawAddress(diag_msg.family, diag_msg.id.dst)
338
339  @staticmethod
340  def RawAddress(addr):
341    """Converts an IP address string to binary format."""
342    family = AF_INET6 if ":" in addr else AF_INET
343    return inet_pton(family, addr)
344
345  @staticmethod
346  def PaddedAddress(addr):
347    """Converts an IP address string to binary format for InetDiagSockId."""
348    padded = SockDiag.RawAddress(addr)
349    if len(padded) < 16:
350      padded += "\x00" * (16 - len(padded))
351    return padded
352
353  @staticmethod
354  def DiagReqFromSocket(s):
355    """Creates an InetDiagReqV2 that matches the specified socket."""
356    family = s.getsockopt(net_test.SOL_SOCKET, net_test.SO_DOMAIN)
357    protocol = s.getsockopt(net_test.SOL_SOCKET, net_test.SO_PROTOCOL)
358    if net_test.LINUX_VERSION >= (3, 8):
359      iface = s.getsockopt(SOL_SOCKET, net_test.SO_BINDTODEVICE,
360                           net_test.IFNAMSIZ)
361      iface = GetInterfaceIndex(iface) if iface else 0
362    else:
363      iface = 0
364    src, sport = s.getsockname()[:2]
365    try:
366      dst, dport = s.getpeername()[:2]
367    except error, e:
368      if e.errno == errno.ENOTCONN:
369        dport = 0
370        dst = "::" if family == AF_INET6 else "0.0.0.0"
371      else:
372        raise e
373    src = SockDiag.PaddedAddress(src)
374    dst = SockDiag.PaddedAddress(dst)
375    sock_id = InetDiagSockId((sport, dport, src, dst, iface, "\x00" * 8))
376    return InetDiagReqV2((family, protocol, 0, 0xffffffff, sock_id))
377
378  def FindSockInfoFromFd(self, s):
379    """Gets a diag_msg and attrs from the kernel for the specified socket."""
380    req = self.DiagReqFromSocket(s)
381    # The kernel doesn't use idiag_src and idiag_dst when dumping sockets, it
382    # only uses them when targeting a specific socket with a cookie. Check the
383    # the inode number to ensure we don't mistakenly match another socket on
384    # the same port but with a different IP address.
385    inode = os.fstat(s.fileno()).st_ino
386    results = self.Dump(req, "")
387    if len(results) == 0:
388      raise ValueError("Dump of %s returned no sockets" % req)
389    for diag_msg, attrs in results:
390      if diag_msg.inode == inode:
391        return diag_msg, attrs
392    raise ValueError("Dump of %s did not contain inode %d" % (req, inode))
393
394  def FindSockDiagFromFd(self, s):
395    """Gets an InetDiagMsg from the kernel for the specified socket."""
396    return self.FindSockInfoFromFd(s)[0]
397
398  def GetSockInfo(self, req):
399    """Gets a diag_msg and attrs from the kernel for the specified request."""
400    self._SendNlRequest(SOCK_DIAG_BY_FAMILY, req.Pack(), netlink.NLM_F_REQUEST)
401    return self._GetMsg(InetDiagMsg)
402
403  @staticmethod
404  def DiagReqFromDiagMsg(d, protocol):
405    """Constructs a diag_req from a diag_msg the kernel has given us."""
406    return InetDiagReqV2((d.family, protocol, 0, 1 << d.state, d.id))
407
408  def CloseSocket(self, req):
409    self._SendNlRequest(SOCK_DESTROY, req.Pack(),
410                        netlink.NLM_F_REQUEST | netlink.NLM_F_ACK)
411
412  def CloseSocketFromFd(self, s):
413    diag_msg, attrs = self.FindSockInfoFromFd(s)
414    protocol = s.getsockopt(SOL_SOCKET, net_test.SO_PROTOCOL)
415    req = self.DiagReqFromDiagMsg(diag_msg, protocol)
416    return self.CloseSocket(req)
417
418
419if __name__ == "__main__":
420  n = SockDiag()
421  n.DEBUG = True
422  bytecode = ""
423  sock_id = n._EmptyInetDiagSockId()
424  sock_id.dport = 443
425  ext = 1 << (INET_DIAG_TOS - 1) | 1 << (INET_DIAG_TCLASS - 1)
426  states = 0xffffffff
427  diag_msgs = n.DumpAllInetSockets(IPPROTO_TCP, "",
428                                   sock_id=sock_id, ext=ext, states=states)
429  print diag_msgs
430