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__init__.py
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__init__.py
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# Copyright 2015 PLUMgrid
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# https://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
from __future__ import print_function
import atexit
from collections import MutableMapping
import ctypes as ct
import fcntl
import json
import os
from subprocess import Popen, PIPE
import sys
basestring = (unicode if sys.version_info[0] < 3 else str)
lib = ct.CDLL("libbcc.so")
# keep in sync with bpf_common.h
lib.bpf_module_create_b.restype = ct.c_void_p
lib.bpf_module_create_b.argtypes = [ct.c_char_p, ct.c_char_p, ct.c_uint]
lib.bpf_module_create_c.restype = ct.c_void_p
lib.bpf_module_create_c.argtypes = [ct.c_char_p, ct.c_uint]
lib.bpf_module_create_c_from_string.restype = ct.c_void_p
lib.bpf_module_create_c_from_string.argtypes = [ct.c_char_p, ct.c_uint]
lib.bpf_module_destroy.restype = None
lib.bpf_module_destroy.argtypes = [ct.c_void_p]
lib.bpf_module_license.restype = ct.c_char_p
lib.bpf_module_license.argtypes = [ct.c_void_p]
lib.bpf_module_kern_version.restype = ct.c_uint
lib.bpf_module_kern_version.argtypes = [ct.c_void_p]
lib.bpf_function_start.restype = ct.c_void_p
lib.bpf_function_start.argtypes = [ct.c_void_p, ct.c_char_p]
lib.bpf_function_size.restype = ct.c_size_t
lib.bpf_function_size.argtypes = [ct.c_void_p, ct.c_char_p]
lib.bpf_table_id.restype = ct.c_ulonglong
lib.bpf_table_id.argtypes = [ct.c_void_p, ct.c_char_p]
lib.bpf_table_fd.restype = ct.c_int
lib.bpf_table_fd.argtypes = [ct.c_void_p, ct.c_char_p]
lib.bpf_table_type_id.restype = ct.c_int
lib.bpf_table_type_id.argtypes = [ct.c_void_p, ct.c_ulonglong]
lib.bpf_table_key_desc.restype = ct.c_char_p
lib.bpf_table_key_desc.argtypes = [ct.c_void_p, ct.c_char_p]
lib.bpf_table_leaf_desc.restype = ct.c_char_p
lib.bpf_table_leaf_desc.argtypes = [ct.c_void_p, ct.c_char_p]
lib.bpf_table_key_snprintf.restype = ct.c_int
lib.bpf_table_key_snprintf.argtypes = [ct.c_void_p, ct.c_ulonglong,
ct.c_char_p, ct.c_ulonglong, ct.c_void_p]
lib.bpf_table_leaf_snprintf.restype = ct.c_int
lib.bpf_table_leaf_snprintf.argtypes = [ct.c_void_p, ct.c_ulonglong,
ct.c_char_p, ct.c_ulonglong, ct.c_void_p]
lib.bpf_table_key_sscanf.restype = ct.c_int
lib.bpf_table_key_sscanf.argtypes = [ct.c_void_p, ct.c_ulonglong,
ct.c_char_p, ct.c_void_p]
lib.bpf_table_leaf_sscanf.restype = ct.c_int
lib.bpf_table_leaf_sscanf.argtypes = [ct.c_void_p, ct.c_ulonglong,
ct.c_char_p, ct.c_void_p]
# keep in sync with libbpf.h
lib.bpf_get_next_key.restype = ct.c_int
lib.bpf_get_next_key.argtypes = [ct.c_int, ct.c_void_p, ct.c_void_p]
lib.bpf_lookup_elem.restype = ct.c_int
lib.bpf_lookup_elem.argtypes = [ct.c_int, ct.c_void_p, ct.c_void_p]
lib.bpf_update_elem.restype = ct.c_int
lib.bpf_update_elem.argtypes = [ct.c_int, ct.c_void_p, ct.c_void_p,
ct.c_ulonglong]
lib.bpf_delete_elem.restype = ct.c_int
lib.bpf_delete_elem.argtypes = [ct.c_int, ct.c_void_p]
lib.bpf_open_raw_sock.restype = ct.c_int
lib.bpf_open_raw_sock.argtypes = [ct.c_char_p]
lib.bpf_attach_socket.restype = ct.c_int
lib.bpf_attach_socket.argtypes = [ct.c_int, ct.c_int]
lib.bpf_prog_load.restype = ct.c_int
lib.bpf_prog_load.argtypes = [ct.c_int, ct.c_void_p, ct.c_size_t,
ct.c_char_p, ct.c_uint, ct.c_char_p, ct.c_uint]
lib.bpf_attach_kprobe.restype = ct.c_int
lib.bpf_attach_kprobe.argtypes = [ct.c_int, ct.c_char_p,
ct.c_char_p, ct.c_int, ct.c_int, ct.c_int]
lib.bpf_detach_kprobe.restype = ct.c_int
lib.bpf_detach_kprobe.argtypes = [ct.c_char_p]
open_kprobes = {}
tracefile = None
TRACEFS = "/sys/kernel/debug/tracing"
@atexit.register
def cleanup_kprobes():
for k, v in open_kprobes.items():
os.close(v)
desc = "-:kprobes/%s" % k
lib.bpf_detach_kprobe(desc.encode("ascii"))
if tracefile:
tracefile.close()
class BPF(object):
SOCKET_FILTER = 1
KPROBE = 2
SCHED_CLS = 3
SCHED_ACT = 4
HASH = 1
ARRAY = 2
PROG_ARRAY = 3
class Function(object):
def __init__(self, bpf, name, fd):
self.bpf = bpf
self.name = name
self.fd = fd
class Table(MutableMapping):
def __init__(self, bpf, map_id, map_fd, keytype, leaftype):
self.bpf = bpf
self.map_id = map_id
self.map_fd = map_fd
self.Key = keytype
self.Leaf = leaftype
self.ttype = lib.bpf_table_type_id(self.bpf.module, self.map_id)
def key_sprintf(self, key):
key_p = ct.pointer(key)
buf = ct.create_string_buffer(ct.sizeof(self.Key) * 8)
res = lib.bpf_table_key_snprintf(self.bpf.module, self.map_id,
buf, len(buf), key_p)
if res < 0:
raise Exception("Could not printf key")
return buf.value
def leaf_sprintf(self, leaf):
leaf_p = ct.pointer(leaf)
buf = ct.create_string_buffer(ct.sizeof(self.Leaf) * 8)
res = lib.bpf_table_leaf_snprintf(self.bpf.module, self.map_id,
buf, len(buf), leaf_p)
if res < 0:
raise Exception("Could not printf leaf")
return buf.value
def key_scanf(self, key_str):
key = self.Key()
key_p = ct.pointer(key)
res = lib.bpf_table_key_sscanf(self.bpf.module, self.map_id,
key_str, key_p)
if res < 0:
raise Exception("Could not scanf key")
return key
def leaf_scanf(self, leaf_str):
leaf = self.Leaf()
leaf_p = ct.pointer(leaf)
res = lib.bpf_table_leaf_sscanf(self.bpf.module, self.map_id,
leaf_str, leaf_p)
if res < 0:
raise Exception("Could not scanf leaf")
return leaf
def __getitem__(self, key):
key_p = ct.pointer(key)
leaf = self.Leaf()
leaf_p = ct.pointer(leaf)
res = lib.bpf_lookup_elem(self.map_fd,
ct.cast(key_p, ct.c_void_p),
ct.cast(leaf_p, ct.c_void_p))
if res < 0:
raise KeyError
return leaf
def __setitem__(self, key, leaf):
key_p = ct.pointer(key)
leaf_p = ct.pointer(leaf)
res = lib.bpf_update_elem(self.map_fd,
ct.cast(key_p, ct.c_void_p),
ct.cast(leaf_p, ct.c_void_p), 0)
if res < 0:
raise Exception("Could not update table")
def __len__(self):
i = 0
for k in self: i += 1
return i
def __delitem__(self, key):
key_p = ct.pointer(key)
ttype = lib.bpf_table_type_id(self.bpf.module, self.map_id)
# Deleting from array type maps does not have an effect, so
# zero out the entry instead.
if ttype in (BPF.ARRAY, BPF.PROG_ARRAY):
leaf = self.Leaf()
leaf_p = ct.pointer(leaf)
res = lib.bpf_update_elem(self.map_fd,
ct.cast(key_p, ct.c_void_p),
ct.cast(leaf_p, ct.c_void_p), 0)
if res < 0:
raise Exception("Could not clear item")
else:
res = lib.bpf_delete_elem(self.map_fd,
ct.cast(key_p, ct.c_void_p))
if res < 0:
raise KeyError
def clear(self):
if self.ttype in (BPF.ARRAY, BPF.PROG_ARRAY):
# Special case clear, since this class is currently behaving
# like a dict but popitem on an array causes an infinite loop.
# TODO: derive Table from array.array instead
for k in self.keys():
self.__delitem__(k)
else:
super(BPF.Table, self).clear()
def __iter__(self):
return BPF.Table.Iter(self, self.Key)
def iter(self): return self.__iter__()
def keys(self): return self.__iter__()
class Iter(object):
def __init__(self, table, keytype):
self.Key = keytype
self.table = table
self.key = self.Key()
def __iter__(self):
return self
def __next__(self):
return self.next()
def next(self):
self.key = self.table.next(self.key)
return self.key
def next(self, key):
next_key = self.Key()
next_key_p = ct.pointer(next_key)
key_p = ct.pointer(key)
res = lib.bpf_get_next_key(self.map_fd,
ct.cast(key_p, ct.c_void_p),
ct.cast(next_key_p, ct.c_void_p))
if res < 0:
raise StopIteration()
return next_key
@staticmethod
def _find_file(filename):
""" If filename is invalid, search in ./ of argv[0] """
if filename:
if not os.path.isfile(filename):
t = "/".join([os.path.abspath(os.path.dirname(sys.argv[0])), filename])
if os.path.isfile(t):
filename = t
else:
raise Exception("Could not find file %s" % filename)
return filename
def __init__(self, src_file="", hdr_file="", text=None, debug=0):
"""Create a a new BPF module with the given source code.
Note:
All fields are marked as optional, but either `src_file` or `text`
must be supplied, and not both.
Args:
src_file (Optional[str]): Path to a source file for the module
hdr_file (Optional[str]): Path to a helper header file for the `src_file`
text (Optional[str]): Contents of a source file for the module
debug (Optional[int]): Flags used for debug prints, can be |'d together
0x1: print LLVM IR to stderr
0x2: print BPF bytecode to stderr
"""
self.debug = debug
self.funcs = {}
self.tables = {}
if text:
self.module = lib.bpf_module_create_c_from_string(text.encode("ascii"), self.debug)
else:
src_file = BPF._find_file(src_file)
hdr_file = BPF._find_file(hdr_file)
if src_file.endswith(".b"):
self.module = lib.bpf_module_create_b(src_file.encode("ascii"),
hdr_file.encode("ascii"), self.debug)
else:
self.module = lib.bpf_module_create_c(src_file.encode("ascii"),
self.debug)
if self.module == None:
raise Exception("Failed to compile BPF module %s" % src_file)
def load_func(self, func_name, prog_type):
if func_name in self.funcs:
return self.funcs[func_name]
if lib.bpf_function_start(self.module, func_name.encode("ascii")) == None:
raise Exception("Unknown program %s" % func_name)
log_buf = ct.create_string_buffer(65536) if self.debug else None
fd = lib.bpf_prog_load(prog_type,
lib.bpf_function_start(self.module, func_name.encode("ascii")),
lib.bpf_function_size(self.module, func_name.encode("ascii")),
lib.bpf_module_license(self.module),
lib.bpf_module_kern_version(self.module),
log_buf, ct.sizeof(log_buf) if log_buf else 0)
if self.debug & 0x2:
print(log_buf.value.decode(), file=sys.stderr)
if fd < 0:
raise Exception("Failed to load BPF program %s" % func_name)
fn = BPF.Function(self, func_name, fd)
self.funcs[func_name] = fn
return fn
str2ctype = {
u"_Bool": ct.c_bool,
u"char": ct.c_char,
u"wchar_t": ct.c_wchar,
u"char": ct.c_byte,
u"unsigned char": ct.c_ubyte,
u"short": ct.c_short,
u"unsigned short": ct.c_ushort,
u"int": ct.c_int,
u"unsigned int": ct.c_uint,
u"long": ct.c_long,
u"unsigned long": ct.c_ulong,
u"long long": ct.c_longlong,
u"unsigned long long": ct.c_ulonglong,
u"float": ct.c_float,
u"double": ct.c_double,
u"long double": ct.c_longdouble
}
@staticmethod
def _decode_table_type(desc):
if isinstance(desc, basestring):
return BPF.str2ctype[desc]
fields = []
for t in desc[1]:
if len(t) == 2:
fields.append((t[0], BPF._decode_table_type(t[1])))
elif len(t) == 3:
fields.append((t[0], BPF._decode_table_type(t[1]), t[2]))
cls = type(str(desc[0]), (ct.Structure,), dict(_fields_=fields))
return cls
def get_table(self, name, keytype=None, leaftype=None):
map_id = lib.bpf_table_id(self.module, name.encode("ascii"))
map_fd = lib.bpf_table_fd(self.module, name.encode("ascii"))
if map_fd < 0:
raise KeyError
if not keytype:
key_desc = lib.bpf_table_key_desc(self.module, name.encode("ascii"))
if not key_desc:
raise Exception("Failed to load BPF Table %s key desc" % name)
keytype = BPF._decode_table_type(json.loads(key_desc.decode()))
if not leaftype:
leaf_desc = lib.bpf_table_leaf_desc(self.module, name.encode("ascii"))
if not leaf_desc:
raise Exception("Failed to load BPF Table %s leaf desc" % name)
leaftype = BPF._decode_table_type(json.loads(leaf_desc.decode()))
return BPF.Table(self, map_id, map_fd, keytype, leaftype)
def __getitem__(self, key):
if key not in self.tables:
self.tables[key] = self.get_table(key)
return self.tables[key]
def __setitem__(self, key, leaf):
self.tables[key] = leaf
def __len__(self):
return len(self.tables)
def __delitem__(self, key):
del self.tables[key]
def __iter__(self):
return self.tables.__iter__()
@staticmethod
def attach_raw_socket(fn, dev):
if not isinstance(fn, BPF.Function):
raise Exception("arg 1 must be of type BPF.Function")
sock = lib.bpf_open_raw_sock(dev.encode("ascii"))
if sock < 0:
errstr = os.strerror(ct.get_errno())
raise Exception("Failed to open raw device %s: %s" % (dev, errstr))
res = lib.bpf_attach_socket(sock, fn.fd)
if res < 0:
errstr = os.strerror(ct.get_errno())
raise Exception("Failed to attach BPF to device %s: %s"
% (dev, errstr))
fn.sock = sock
@staticmethod
def _get_kprobe_functions(event_re):
p = Popen(["awk", "$1 ~ /%s/ { print $1 }" % event_re,
"%s/available_filter_functions" % TRACEFS], stdout=PIPE)
lines = p.communicate()[0].decode().split()
return [line.rstrip() for line in lines if line != "\n"]
def attach_kprobe(self, event="", fn_name="", event_re="",
pid=0, cpu=-1, group_fd=-1):
# allow the caller to glob multiple functions together
if event_re:
for line in BPF._get_kprobe_functions(event_re):
self.attach_kprobe(event=line, fn_name=fn_name, pid=pid,
cpu=cpu, group_fd=group_fd)
return
fn = self.load_func(fn_name, BPF.KPROBE)
ev_name = "p_" + event.replace("+", "_")
desc = "p:kprobes/%s %s" % (ev_name, event)
res = lib.bpf_attach_kprobe(fn.fd, ev_name.encode("ascii"),
desc.encode("ascii"), pid, cpu, group_fd)
if res < 0:
raise Exception("Failed to attach BPF to kprobe")
open_kprobes[ev_name] = res
return self
@staticmethod
def detach_kprobe(event):
ev_name = "p_" + event.replace("+", "_")
if ev_name not in open_kprobes:
raise Exception("Kprobe %s is not attached" % event)
os.close(open_kprobes[ev_name])
desc = "-:kprobes/%s" % ev_name
res = lib.bpf_detach_kprobe(desc.encode("ascii"))
if res < 0:
raise Exception("Failed to detach BPF from kprobe")
del open_kprobes[ev_name]
def attach_kretprobe(self, event="", fn_name="", event_re="",
pid=-1, cpu=0, group_fd=-1):
# allow the caller to glob multiple functions together
if event_re:
for line in BPF._get_kprobe_functions(event_re):
self.attach_kretprobe(event=line, fn_name=fn_name, pid=pid,
cpu=cpu, group_fd=group_fd)
return
fn = self.load_func(fn_name, BPF.KPROBE)
ev_name = "r_" + event.replace("+", "_")
desc = "r:kprobes/%s %s" % (ev_name, event)
res = lib.bpf_attach_kprobe(fn.fd, ev_name.encode("ascii"),
desc.encode("ascii"), pid, cpu, group_fd)
if res < 0:
raise Exception("Failed to attach BPF to kprobe")
open_kprobes[ev_name] = res
return self
@staticmethod
def detach_kretprobe(event):
ev_name = "r_" + event.replace("+", "_")
if ev_name not in open_kprobes:
raise Exception("Kretprobe %s is not attached" % event)
os.close(open_kprobes[ev_name])
desc = "-:kprobes/%s" % ev_name
res = lib.bpf_detach_kprobe(desc.encode("ascii"))
if res < 0:
raise Exception("Failed to detach BPF from kprobe")
del open_kprobes[ev_name]
@staticmethod
def trace_open(nonblocking=False):
"""trace_open(nonblocking=False)
Open the trace_pipe if not already open
"""
global tracefile
if not tracefile:
tracefile = open("%s/trace_pipe" % TRACEFS)
if nonblocking:
fd = tracefile.fileno()
fl = fcntl.fcntl(fd, fcntl.F_GETFL)
fcntl.fcntl(fd, fcntl.F_SETFL, fl | os.O_NONBLOCK)
return tracefile
@staticmethod
def trace_readline_fields(nonblocking=False):
"""trace_readline_fields(nonblocking=False)
Read from the kernel debug trace pipe and return a tuple of the
fields (task, pid, cpu, flags, timestamp, msg) or None if no
line was read (nonblocking=True)
"""
line = BPF.trace_readline(nonblocking)
if line:
# don't print messages related to lost events
if line.startswith("CPU:"): return
task = line[:16].lstrip()
line = line[17:]
ts_end = line.find(":")
pid, cpu, flags, ts = line[:ts_end].split()
cpu = cpu[1:-1]
msg = line[ts_end + 4:]
return (task, int(pid), int(cpu), flags, float(ts), msg)
return
@staticmethod
def trace_readline(nonblocking=False):
"""trace_readline(nonblocking=False)
Read from the kernel debug trace pipe and return one line
If nonblocking is False, this will block until ctrl-C is pressed.
"""
trace = BPF.trace_open(nonblocking)
line = None
try:
line = trace.readline(1024).rstrip()
except IOError:
pass
except KeyboardInterrupt:
exit()
return line
@staticmethod
def trace_print(fmt=None):
"""trace_print(fmt=None)
Read from the kernel debug trace pipe and print on stdout.
If fmt is specified, apply as a format string to the output. See
trace_readline_fields for the members of the tuple
example: trace_print(fmt="pid {1}, msg = {5}")
"""
while True:
if fmt:
fields = BPF.trace_readline_fields(nonblocking=False)
if not fields: continue
line = fmt.format(*fields)
else:
line = BPF.trace_readline(nonblocking=False)
print(line)
sys.stdout.flush()