| 1 | |
| 2 | |
| 3 | |
| 4 | |
| 5 | |
| 6 |
|
| 7 | |
| 8 | from __future__ import print_function
|
| 9 |
|
| 10 | import argparse
|
| 11 | import json
|
| 12 | import re
|
| 13 | import sys, os
|
| 14 | import subprocess
|
| 15 |
|
| 16 | helpersDocStart = 'Start of BPF helper function descriptions:'
|
| 17 |
|
| 18 | class NoHelperFound(BaseException):
|
| 19 | pass
|
| 20 |
|
| 21 | class NoSyscallCommandFound(BaseException):
|
| 22 | pass
|
| 23 |
|
| 24 | class ParsingError(BaseException):
|
| 25 | def __init__(self, line='<line not provided>', reader=None):
|
| 26 | if reader:
|
| 27 | BaseException.__init__(self,
|
| 28 | 'Error at file offset %d, parsing line: %s' %
|
| 29 | (reader.tell(), line))
|
| 30 | else:
|
| 31 | BaseException.__init__(self, 'Error parsing line: %s' % line)
|
| 32 |
|
| 33 |
|
| 34 | class APIElement(object):
|
| 35 | |
| 36 | An object representing the description of an aspect of the eBPF API.
|
| 37 | @proto: prototype of the API symbol
|
| 38 | @desc: textual description of the symbol
|
| 39 | @ret: (optional) description of any associated return value
|
| 40 |
|
| 41 | def __init__(self, proto='', desc='', ret=''):
|
| 42 | self.proto = proto
|
| 43 | self.desc = desc
|
| 44 | self.ret = ret
|
| 45 |
|
| 46 | def to_dict(self):
|
| 47 | return {
|
| 48 | 'proto': self.proto,
|
| 49 | 'desc': self.desc,
|
| 50 | 'ret': self.ret
|
| 51 | }
|
| 52 |
|
| 53 |
|
| 54 | class Helper(APIElement):
|
| 55 | |
| 56 | An object representing the description of an eBPF helper function.
|
| 57 | @proto: function prototype of the helper function
|
| 58 | @desc: textual description of the helper function
|
| 59 | @ret: description of the return value of the helper function
|
| 60 |
|
| 61 | def __init__(self, proto='', desc='', ret='', attrs=[]):
|
| 62 | super().__init__(proto, desc, ret)
|
| 63 | self.attrs = attrs
|
| 64 | self.enum_val = None
|
| 65 |
|
| 66 | def proto_break_down(self):
|
| 67 | |
| 68 | Break down helper function protocol into smaller chunks: return type,
|
| 69 | name, distincts arguments.
|
| 70 |
|
| 71 | arg_re = re.compile(r'((\w+ )*?(\w+|...))( (\**)(\w+))?$')
|
| 72 | res = {}
|
| 73 | proto_re = re.compile(r'(.+) (\**)(\w+)\(((([^,]+)(, )?){1,5})\)$')
|
| 74 |
|
| 75 | capture = proto_re.match(self.proto)
|
| 76 | res['ret_type'] = capture.group(1)
|
| 77 | res['ret_star'] = capture.group(2)
|
| 78 | res['name'] = capture.group(3)
|
| 79 | res['args'] = []
|
| 80 |
|
| 81 | args = capture.group(4).split(', ')
|
| 82 | for a in args:
|
| 83 | capture = arg_re.match(a)
|
| 84 | res['args'].append({
|
| 85 | 'type' : capture.group(1),
|
| 86 | 'star' : capture.group(5),
|
| 87 | 'name' : capture.group(6)
|
| 88 | })
|
| 89 |
|
| 90 | return res
|
| 91 |
|
| 92 | def to_dict(self):
|
| 93 | d = super().to_dict()
|
| 94 | d["attrs"] = self.attrs
|
| 95 | d.update(self.proto_break_down())
|
| 96 | return d
|
| 97 |
|
| 98 |
|
| 99 | ATTRS = {
|
| 100 | '__bpf_fastcall': 'bpf_fastcall'
|
| 101 | }
|
| 102 |
|
| 103 |
|
| 104 | class HeaderParser(object):
|
| 105 | |
| 106 | An object used to parse a file in order to extract the documentation of a
|
| 107 | list of eBPF helper functions. All the helpers that can be retrieved are
|
| 108 | stored as Helper object, in the self.helpers() array.
|
| 109 | @filename: name of file to parse, usually include/uapi/linux/bpf.h in the
|
| 110 | kernel tree
|
| 111 |
|
| 112 | def __init__(self, filename):
|
| 113 | self.reader = open(filename, 'r')
|
| 114 | self.line = ''
|
| 115 | self.helpers = []
|
| 116 | self.commands = []
|
| 117 | self.desc_unique_helpers = set()
|
| 118 | self.define_unique_helpers = []
|
| 119 | self.helper_enum_vals = {}
|
| 120 | self.helper_enum_pos = {}
|
| 121 | self.desc_syscalls = []
|
| 122 | self.enum_syscalls = []
|
| 123 |
|
| 124 | def parse_element(self):
|
| 125 | proto = self.parse_symbol()
|
| 126 | desc = self.parse_desc(proto)
|
| 127 | ret = self.parse_ret(proto)
|
| 128 | return APIElement(proto=proto, desc=desc, ret=ret)
|
| 129 |
|
| 130 | def parse_helper(self):
|
| 131 | proto = self.parse_proto()
|
| 132 | desc = self.parse_desc(proto)
|
| 133 | ret = self.parse_ret(proto)
|
| 134 | attrs = self.parse_attrs(proto)
|
| 135 | return Helper(proto=proto, desc=desc, ret=ret, attrs=attrs)
|
| 136 |
|
| 137 | def parse_symbol(self):
|
| 138 | p = re.compile(r' \* ?(BPF\w+)$')
|
| 139 | capture = p.match(self.line)
|
| 140 | if not capture:
|
| 141 | raise NoSyscallCommandFound
|
| 142 | end_re = re.compile(r' \* ?NOTES$')
|
| 143 | end = end_re.match(self.line)
|
| 144 | if end:
|
| 145 | raise NoSyscallCommandFound
|
| 146 | self.line = self.reader.readline()
|
| 147 | return capture.group(1)
|
| 148 |
|
| 149 | def parse_proto(self):
|
| 150 | |
| 151 | |
| 152 | |
| 153 | |
| 154 | |
| 155 | |
| 156 | |
| 157 | p = re.compile(r' \* ?((.+) \**\w+\((((const )?(struct )?(\w+|\.\.\.)( \**\w+)?)(, )?){1,5}\))$')
|
| 158 | capture = p.match(self.line)
|
| 159 | if not capture:
|
| 160 | raise NoHelperFound
|
| 161 | self.line = self.reader.readline()
|
| 162 | return capture.group(1)
|
| 163 |
|
| 164 | def parse_desc(self, proto):
|
| 165 | p = re.compile(r' \* ?(?:\t| {5,8})Description$')
|
| 166 | capture = p.match(self.line)
|
| 167 | if not capture:
|
| 168 | raise Exception("No description section found for " + proto)
|
| 169 | |
| 170 | |
| 171 | desc = ''
|
| 172 | desc_present = False
|
| 173 | while True:
|
| 174 | self.line = self.reader.readline()
|
| 175 | if self.line == ' *\n':
|
| 176 | desc += '\n'
|
| 177 | else:
|
| 178 | p = re.compile(r' \* ?(?:\t| {5,8})(?:\t| {8})(.*)')
|
| 179 | capture = p.match(self.line)
|
| 180 | if capture:
|
| 181 | desc_present = True
|
| 182 | desc += capture.group(1) + '\n'
|
| 183 | else:
|
| 184 | break
|
| 185 |
|
| 186 | if not desc_present:
|
| 187 | raise Exception("No description found for " + proto)
|
| 188 | return desc
|
| 189 |
|
| 190 | def parse_ret(self, proto):
|
| 191 | p = re.compile(r' \* ?(?:\t| {5,8})Return$')
|
| 192 | capture = p.match(self.line)
|
| 193 | if not capture:
|
| 194 | raise Exception("No return section found for " + proto)
|
| 195 | |
| 196 | |
| 197 | ret = ''
|
| 198 | ret_present = False
|
| 199 | while True:
|
| 200 | self.line = self.reader.readline()
|
| 201 | if self.line == ' *\n':
|
| 202 | ret += '\n'
|
| 203 | else:
|
| 204 | p = re.compile(r' \* ?(?:\t| {5,8})(?:\t| {8})(.*)')
|
| 205 | capture = p.match(self.line)
|
| 206 | if capture:
|
| 207 | ret_present = True
|
| 208 | ret += capture.group(1) + '\n'
|
| 209 | else:
|
| 210 | break
|
| 211 |
|
| 212 | if not ret_present:
|
| 213 | raise Exception("No return found for " + proto)
|
| 214 | return ret
|
| 215 |
|
| 216 | def parse_attrs(self, proto):
|
| 217 | p = re.compile(r' \* ?(?:\t| {5,8})Attributes$')
|
| 218 | capture = p.match(self.line)
|
| 219 | if not capture:
|
| 220 | return []
|
| 221 | |
| 222 | self.line = self.reader.readline()
|
| 223 | p = re.compile(r' \* ?(?:\t| {5,8})(?:\t| {8})(.*)')
|
| 224 | capture = p.match(self.line)
|
| 225 | if not capture:
|
| 226 | raise Exception("Incomplete 'Attributes' section for " + proto)
|
| 227 | attrs = capture.group(1).split(' ')
|
| 228 | for attr in attrs:
|
| 229 | if attr not in ATTRS:
|
| 230 | raise Exception("Unexpected attribute '" + attr + "' specified for " + proto)
|
| 231 | self.line = self.reader.readline()
|
| 232 | if self.line != ' *\n':
|
| 233 | raise Exception("Expecting empty line after 'Attributes' section for " + proto)
|
| 234 | |
| 235 | self.line = self.reader.readline()
|
| 236 | return attrs
|
| 237 |
|
| 238 | def seek_to(self, target, help_message, discard_lines = 1):
|
| 239 | self.reader.seek(0)
|
| 240 | offset = self.reader.read().find(target)
|
| 241 | if offset == -1:
|
| 242 | raise Exception(help_message)
|
| 243 | self.reader.seek(offset)
|
| 244 | self.reader.readline()
|
| 245 | for _ in range(discard_lines):
|
| 246 | self.reader.readline()
|
| 247 | self.line = self.reader.readline()
|
| 248 |
|
| 249 | def parse_desc_syscall(self):
|
| 250 | self.seek_to('* DOC: eBPF Syscall Commands',
|
| 251 | 'Could not find start of eBPF syscall descriptions list')
|
| 252 | while True:
|
| 253 | try:
|
| 254 | command = self.parse_element()
|
| 255 | self.commands.append(command)
|
| 256 | self.desc_syscalls.append(command.proto)
|
| 257 |
|
| 258 | except NoSyscallCommandFound:
|
| 259 | break
|
| 260 |
|
| 261 | def parse_enum_syscall(self):
|
| 262 | self.seek_to('enum bpf_cmd {',
|
| 263 | 'Could not find start of bpf_cmd enum', 0)
|
| 264 | |
| 265 | bpf_p = re.compile(r'\s*(BPF\w+)+')
|
| 266 | |
| 267 | |
| 268 | |
| 269 | |
| 270 | assign_p = re.compile(r'\s*(BPF\w+)\s*=\s*(BPF\w+)')
|
| 271 | bpf_cmd_str = ''
|
| 272 | while True:
|
| 273 | capture = assign_p.match(self.line)
|
| 274 | if capture:
|
| 275 | |
| 276 | self.line = self.reader.readline()
|
| 277 | continue
|
| 278 | capture = bpf_p.match(self.line)
|
| 279 | if capture:
|
| 280 | bpf_cmd_str += self.line
|
| 281 | else:
|
| 282 | break
|
| 283 | self.line = self.reader.readline()
|
| 284 | |
| 285 | self.enum_syscalls = re.findall(r'(BPF\w+)+', bpf_cmd_str)
|
| 286 |
|
| 287 | def parse_desc_helpers(self):
|
| 288 | self.seek_to(helpersDocStart,
|
| 289 | 'Could not find start of eBPF helper descriptions list')
|
| 290 | while True:
|
| 291 | try:
|
| 292 | helper = self.parse_helper()
|
| 293 | self.helpers.append(helper)
|
| 294 | proto = helper.proto_break_down()
|
| 295 | self.desc_unique_helpers.add(proto['name'])
|
| 296 | except NoHelperFound:
|
| 297 | break
|
| 298 |
|
| 299 | def parse_define_helpers(self):
|
| 300 | |
| 301 | |
| 302 | |
| 303 | |
| 304 | |
| 305 | |
| 306 | self.seek_to('#define ___BPF_FUNC_MAPPER(FN, ctx...)',
|
| 307 | 'Could not find start of eBPF helper definition list')
|
| 308 | |
| 309 | p = re.compile(r'\s*FN\((\w+), (\d+), ##ctx\)|\\\\')
|
| 310 | fn_defines_str = ''
|
| 311 | i = 0
|
| 312 | while True:
|
| 313 | capture = p.match(self.line)
|
| 314 | if capture:
|
| 315 | fn_defines_str += self.line
|
| 316 | helper_name = capture.expand(r'bpf_\1')
|
| 317 | self.helper_enum_vals[helper_name] = int(capture.group(2))
|
| 318 | self.helper_enum_pos[helper_name] = i
|
| 319 | i += 1
|
| 320 | else:
|
| 321 | break
|
| 322 | self.line = self.reader.readline()
|
| 323 | |
| 324 | self.define_unique_helpers = re.findall(r'FN\(\w+, \d+, ##ctx\)', fn_defines_str)
|
| 325 |
|
| 326 | def validate_helpers(self):
|
| 327 | last_helper = ''
|
| 328 | seen_helpers = set()
|
| 329 | seen_enum_vals = set()
|
| 330 | i = 0
|
| 331 | for helper in self.helpers:
|
| 332 | proto = helper.proto_break_down()
|
| 333 | name = proto['name']
|
| 334 | try:
|
| 335 | enum_val = self.helper_enum_vals[name]
|
| 336 | enum_pos = self.helper_enum_pos[name]
|
| 337 | except KeyError:
|
| 338 | raise Exception("Helper %s is missing from enum bpf_func_id" % name)
|
| 339 |
|
| 340 | if name in seen_helpers:
|
| 341 | if last_helper != name:
|
| 342 | raise Exception("Helper %s has multiple descriptions which are not grouped together" % name)
|
| 343 | continue
|
| 344 |
|
| 345 | |
| 346 | |
| 347 | if enum_pos != i:
|
| 348 | raise Exception("Helper %s (ID %d) comment order (#%d) must be aligned with its position (#%d) in enum bpf_func_id" % (name, enum_val, i + 1, enum_pos + 1))
|
| 349 | if enum_val in seen_enum_vals:
|
| 350 | raise Exception("Helper %s has duplicated value %d" % (name, enum_val))
|
| 351 |
|
| 352 | seen_helpers.add(name)
|
| 353 | last_helper = name
|
| 354 | seen_enum_vals.add(enum_val)
|
| 355 |
|
| 356 | helper.enum_val = enum_val
|
| 357 | i += 1
|
| 358 |
|
| 359 | def run(self):
|
| 360 | self.parse_desc_syscall()
|
| 361 | self.parse_enum_syscall()
|
| 362 | self.parse_desc_helpers()
|
| 363 | self.parse_define_helpers()
|
| 364 | self.validate_helpers()
|
| 365 | self.reader.close()
|
| 366 |
|
| 367 | |
| 368 |
|
| 369 | class Printer(object):
|
| 370 | |
| 371 | A generic class for printers. Printers should be created with an array of
|
| 372 | Helper objects, and implement a way to print them in the desired fashion.
|
| 373 | @parser: A HeaderParser with objects to print to standard output
|
| 374 |
|
| 375 | def __init__(self, parser):
|
| 376 | self.parser = parser
|
| 377 | self.elements = []
|
| 378 |
|
| 379 | def print_header(self):
|
| 380 | pass
|
| 381 |
|
| 382 | def print_footer(self):
|
| 383 | pass
|
| 384 |
|
| 385 | def print_one(self, helper):
|
| 386 | pass
|
| 387 |
|
| 388 | def print_all(self):
|
| 389 | self.print_header()
|
| 390 | for elem in self.elements:
|
| 391 | self.print_one(elem)
|
| 392 | self.print_footer()
|
| 393 |
|
| 394 | def elem_number_check(self, desc_unique_elem, define_unique_elem, type, instance):
|
| 395 | |
| 396 | Checks the number of helpers/syscalls documented within the header file
|
| 397 | description with those defined as part of enum/macro and raise an
|
| 398 | Exception if they don't match.
|
| 399 |
|
| 400 | nr_desc_unique_elem = len(desc_unique_elem)
|
| 401 | nr_define_unique_elem = len(define_unique_elem)
|
| 402 | if nr_desc_unique_elem != nr_define_unique_elem:
|
| 403 | exception_msg = '''
|
| 404 | The number of unique %s in description (%d) doesn\'t match the number of unique %s defined in %s (%d)
|
| 405 | ''' % (type, nr_desc_unique_elem, type, instance, nr_define_unique_elem)
|
| 406 | if nr_desc_unique_elem < nr_define_unique_elem:
|
| 407 | |
| 408 | |
| 409 | exception_msg += '''
|
| 410 | The description for %s is not present or formatted correctly.
|
| 411 | ''' % (define_unique_elem[nr_desc_unique_elem])
|
| 412 | raise Exception(exception_msg)
|
| 413 |
|
| 414 | class PrinterRST(Printer):
|
| 415 | |
| 416 | A generic class for printers that print ReStructured Text. Printers should
|
| 417 | be created with a HeaderParser object, and implement a way to print API
|
| 418 | elements in the desired fashion.
|
| 419 | @parser: A HeaderParser with objects to print to standard output
|
| 420 |
|
| 421 | def __init__(self, parser):
|
| 422 | self.parser = parser
|
| 423 |
|
| 424 | def print_license(self):
|
| 425 | license = '''\
|
| 426 | .. Copyright (C) All BPF authors and contributors from 2014 to present.
|
| 427 | .. See git log include/uapi/linux/bpf.h in kernel tree for details.
|
| 428 | ..
|
| 429 | .. SPDX-License-Identifier: Linux-man-pages-copyleft
|
| 430 | ..
|
| 431 | .. Please do not edit this file. It was generated from the documentation
|
| 432 | .. located in file include/uapi/linux/bpf.h of the Linux kernel sources
|
| 433 | .. (helpers description), and from scripts/bpf_doc.py in the same
|
| 434 | .. repository (header and footer).
|
| 435 | '''
|
| 436 | print(license)
|
| 437 |
|
| 438 | def print_elem(self, elem):
|
| 439 | if (elem.desc):
|
| 440 | print('\tDescription')
|
| 441 | |
| 442 | |
| 443 | for line in re.sub('\n$', '', elem.desc, count=1).split('\n'):
|
| 444 | print('{}{}'.format('\t\t' if line else '', line))
|
| 445 |
|
| 446 | if (elem.ret):
|
| 447 | print('\tReturn')
|
| 448 | for line in elem.ret.rstrip().split('\n'):
|
| 449 | print('{}{}'.format('\t\t' if line else '', line))
|
| 450 |
|
| 451 | print('')
|
| 452 |
|
| 453 | def get_kernel_version(self):
|
| 454 | try:
|
| 455 | version = subprocess.run(['git', 'describe'], cwd=linuxRoot,
|
| 456 | capture_output=True, check=True)
|
| 457 | version = version.stdout.decode().rstrip()
|
| 458 | except:
|
| 459 | try:
|
| 460 | version = subprocess.run(['make', '-s', '--no-print-directory', 'kernelversion'],
|
| 461 | cwd=linuxRoot, capture_output=True, check=True)
|
| 462 | version = version.stdout.decode().rstrip()
|
| 463 | except:
|
| 464 | return 'Linux'
|
| 465 | return 'Linux {version}'.format(version=version)
|
| 466 |
|
| 467 | def get_last_doc_update(self, delimiter):
|
| 468 | try:
|
| 469 | cmd = ['git', 'log', '-1', '--pretty=format:%cs', '--no-patch',
|
| 470 | '-L',
|
| 471 | '/{}/,/\\*\\//:include/uapi/linux/bpf.h'.format(delimiter)]
|
| 472 | date = subprocess.run(cmd, cwd=linuxRoot,
|
| 473 | capture_output=True, check=True)
|
| 474 | return date.stdout.decode().rstrip()
|
| 475 | except:
|
| 476 | return ''
|
| 477 |
|
| 478 | class PrinterHelpersRST(PrinterRST):
|
| 479 | |
| 480 | A printer for dumping collected information about helpers as a ReStructured
|
| 481 | Text page compatible with the rst2man program, which can be used to
|
| 482 | generate a manual page for the helpers.
|
| 483 | @parser: A HeaderParser with Helper objects to print to standard output
|
| 484 |
|
| 485 | def __init__(self, parser):
|
| 486 | self.elements = parser.helpers
|
| 487 | self.elem_number_check(parser.desc_unique_helpers, parser.define_unique_helpers, 'helper', '___BPF_FUNC_MAPPER')
|
| 488 |
|
| 489 | def print_header(self):
|
| 490 | header = '''\
|
| 491 | ===========
|
| 492 | BPF-HELPERS
|
| 493 | ===========
|
| 494 | -------------------------------------------------------------------------------
|
| 495 | list of eBPF helper functions
|
| 496 | -------------------------------------------------------------------------------
|
| 497 |
|
| 498 | :Manual section: 7
|
| 499 | :Version: {version}
|
| 500 | {date_field}{date}
|
| 501 |
|
| 502 | DESCRIPTION
|
| 503 | ===========
|
| 504 |
|
| 505 | The extended Berkeley Packet Filter (eBPF) subsystem consists in programs
|
| 506 | written in a pseudo-assembly language, then attached to one of the several
|
| 507 | kernel hooks and run in reaction of specific events. This framework differs
|
| 508 | from the older, "classic" BPF (or "cBPF") in several aspects, one of them being
|
| 509 | the ability to call special functions (or "helpers") from within a program.
|
| 510 | These functions are restricted to a white-list of helpers defined in the
|
| 511 | kernel.
|
| 512 |
|
| 513 | These helpers are used by eBPF programs to interact with the system, or with
|
| 514 | the context in which they work. For instance, they can be used to print
|
| 515 | debugging messages, to get the time since the system was booted, to interact
|
| 516 | with eBPF maps, or to manipulate network packets. Since there are several eBPF
|
| 517 | program types, and that they do not run in the same context, each program type
|
| 518 | can only call a subset of those helpers.
|
| 519 |
|
| 520 | Due to eBPF conventions, a helper can not have more than five arguments.
|
| 521 |
|
| 522 | Internally, eBPF programs call directly into the compiled helper functions
|
| 523 | without requiring any foreign-function interface. As a result, calling helpers
|
| 524 | introduces no overhead, thus offering excellent performance.
|
| 525 |
|
| 526 | This document is an attempt to list and document the helpers available to eBPF
|
| 527 | developers. They are sorted by chronological order (the oldest helpers in the
|
| 528 | kernel at the top).
|
| 529 |
|
| 530 | HELPERS
|
| 531 | =======
|
| 532 | '''
|
| 533 | kernelVersion = self.get_kernel_version()
|
| 534 | lastUpdate = self.get_last_doc_update(helpersDocStart)
|
| 535 |
|
| 536 | PrinterRST.print_license(self)
|
| 537 | print(header.format(version=kernelVersion,
|
| 538 | date_field = ':Date: ' if lastUpdate else '',
|
| 539 | date=lastUpdate))
|
| 540 |
|
| 541 | def print_footer(self):
|
| 542 | footer = '''
|
| 543 | EXAMPLES
|
| 544 | ========
|
| 545 |
|
| 546 | Example usage for most of the eBPF helpers listed in this manual page are
|
| 547 | available within the Linux kernel sources, at the following locations:
|
| 548 |
|
| 549 | * *samples/bpf/*
|
| 550 | * *tools/testing/selftests/bpf/*
|
| 551 |
|
| 552 | LICENSE
|
| 553 | =======
|
| 554 |
|
| 555 | eBPF programs can have an associated license, passed along with the bytecode
|
| 556 | instructions to the kernel when the programs are loaded. The format for that
|
| 557 | string is identical to the one in use for kernel modules (Dual licenses, such
|
| 558 | as "Dual BSD/GPL", may be used). Some helper functions are only accessible to
|
| 559 | programs that are compatible with the GNU General Public License (GNU GPL).
|
| 560 |
|
| 561 | In order to use such helpers, the eBPF program must be loaded with the correct
|
| 562 | license string passed (via **attr**) to the **bpf**\\ () system call, and this
|
| 563 | generally translates into the C source code of the program containing a line
|
| 564 | similar to the following:
|
| 565 |
|
| 566 | ::
|
| 567 |
|
| 568 | char ____license[] __attribute__((section("license"), used)) = "GPL";
|
| 569 |
|
| 570 | IMPLEMENTATION
|
| 571 | ==============
|
| 572 |
|
| 573 | This manual page is an effort to document the existing eBPF helper functions.
|
| 574 | But as of this writing, the BPF sub-system is under heavy development. New eBPF
|
| 575 | program or map types are added, along with new helper functions. Some helpers
|
| 576 | are occasionally made available for additional program types. So in spite of
|
| 577 | the efforts of the community, this page might not be up-to-date. If you want to
|
| 578 | check by yourself what helper functions exist in your kernel, or what types of
|
| 579 | programs they can support, here are some files among the kernel tree that you
|
| 580 | may be interested in:
|
| 581 |
|
| 582 | * *include/uapi/linux/bpf.h* is the main BPF header. It contains the full list
|
| 583 | of all helper functions, as well as many other BPF definitions including most
|
| 584 | of the flags, structs or constants used by the helpers.
|
| 585 | * *net/core/filter.c* contains the definition of most network-related helper
|
| 586 | functions, and the list of program types from which they can be used.
|
| 587 | * *kernel/trace/bpf_trace.c* is the equivalent for most tracing program-related
|
| 588 | helpers.
|
| 589 | * *kernel/bpf/verifier.c* contains the functions used to check that valid types
|
| 590 | of eBPF maps are used with a given helper function.
|
| 591 | * *kernel/bpf/* directory contains other files in which additional helpers are
|
| 592 | defined (for cgroups, sockmaps, etc.).
|
| 593 | * The bpftool utility can be used to probe the availability of helper functions
|
| 594 | on the system (as well as supported program and map types, and a number of
|
| 595 | other parameters). To do so, run **bpftool feature probe** (see
|
| 596 | **bpftool-feature**\\ (8) for details). Add the **unprivileged** keyword to
|
| 597 | list features available to unprivileged users.
|
| 598 |
|
| 599 | Compatibility between helper functions and program types can generally be found
|
| 600 | in the files where helper functions are defined. Look for the **struct
|
| 601 | bpf_func_proto** objects and for functions returning them: these functions
|
| 602 | contain a list of helpers that a given program type can call. Note that the
|
| 603 | **default:** label of the **switch ... case** used to filter helpers can call
|
| 604 | other functions, themselves allowing access to additional helpers. The
|
| 605 | requirement for GPL license is also in those **struct bpf_func_proto**.
|
| 606 |
|
| 607 | Compatibility between helper functions and map types can be found in the
|
| 608 | **check_map_func_compatibility**\\ () function in file *kernel/bpf/verifier.c*.
|
| 609 |
|
| 610 | Helper functions that invalidate the checks on **data** and **data_end**
|
| 611 | pointers for network processing are listed in function
|
| 612 | **bpf_helper_changes_pkt_data**\\ () in file *net/core/filter.c*.
|
| 613 |
|
| 614 | SEE ALSO
|
| 615 | ========
|
| 616 |
|
| 617 | **bpf**\\ (2),
|
| 618 | **bpftool**\\ (8),
|
| 619 | **cgroups**\\ (7),
|
| 620 | **ip**\\ (8),
|
| 621 | **perf_event_open**\\ (2),
|
| 622 | **sendmsg**\\ (2),
|
| 623 | **socket**\\ (7),
|
| 624 | **tc-bpf**\\ (8)'''
|
| 625 | print(footer)
|
| 626 |
|
| 627 | def print_proto(self, helper):
|
| 628 | |
| 629 | Format function protocol with bold and italics markers. This makes RST
|
| 630 | file less readable, but gives nice results in the manual page.
|
| 631 |
|
| 632 | proto = helper.proto_break_down()
|
| 633 |
|
| 634 | print('**%s %s%s(' % (proto['ret_type'],
|
| 635 | proto['ret_star'].replace('*', '\\*'),
|
| 636 | proto['name']),
|
| 637 | end='')
|
| 638 |
|
| 639 | comma = ''
|
| 640 | for a in proto['args']:
|
| 641 | one_arg = '{}{}'.format(comma, a['type'])
|
| 642 | if a['name']:
|
| 643 | if a['star']:
|
| 644 | one_arg += ' {}**\\ '.format(a['star'].replace('*', '\\*'))
|
| 645 | else:
|
| 646 | one_arg += '** '
|
| 647 | one_arg += '*{}*\\ **'.format(a['name'])
|
| 648 | comma = ', '
|
| 649 | print(one_arg, end='')
|
| 650 |
|
| 651 | print(')**')
|
| 652 |
|
| 653 | def print_one(self, helper):
|
| 654 | self.print_proto(helper)
|
| 655 | self.print_elem(helper)
|
| 656 |
|
| 657 |
|
| 658 | class PrinterSyscallRST(PrinterRST):
|
| 659 | |
| 660 | A printer for dumping collected information about the syscall API as a
|
| 661 | ReStructured Text page compatible with the rst2man program, which can be
|
| 662 | used to generate a manual page for the syscall.
|
| 663 | @parser: A HeaderParser with APIElement objects to print to standard
|
| 664 | output
|
| 665 |
|
| 666 | def __init__(self, parser):
|
| 667 | self.elements = parser.commands
|
| 668 | self.elem_number_check(parser.desc_syscalls, parser.enum_syscalls, 'syscall', 'bpf_cmd')
|
| 669 |
|
| 670 | def print_header(self):
|
| 671 | header = '''\
|
| 672 | ===
|
| 673 | bpf
|
| 674 | ===
|
| 675 | -------------------------------------------------------------------------------
|
| 676 | Perform a command on an extended BPF object
|
| 677 | -------------------------------------------------------------------------------
|
| 678 |
|
| 679 | :Manual section: 2
|
| 680 |
|
| 681 | COMMANDS
|
| 682 | ========
|
| 683 | '''
|
| 684 | PrinterRST.print_license(self)
|
| 685 | print(header)
|
| 686 |
|
| 687 | def print_one(self, command):
|
| 688 | print('**%s**' % (command.proto))
|
| 689 | self.print_elem(command)
|
| 690 |
|
| 691 |
|
| 692 | class PrinterHelpersHeader(Printer):
|
| 693 | |
| 694 | A printer for dumping collected information about helpers as C header to
|
| 695 | be included from BPF program.
|
| 696 | @parser: A HeaderParser with Helper objects to print to standard output
|
| 697 |
|
| 698 | def __init__(self, parser):
|
| 699 | self.elements = parser.helpers
|
| 700 | self.elem_number_check(parser.desc_unique_helpers, parser.define_unique_helpers, 'helper', '___BPF_FUNC_MAPPER')
|
| 701 |
|
| 702 | type_fwds = [
|
| 703 | 'struct bpf_fib_lookup',
|
| 704 | 'struct bpf_sk_lookup',
|
| 705 | 'struct bpf_perf_event_data',
|
| 706 | 'struct bpf_perf_event_value',
|
| 707 | 'struct bpf_pidns_info',
|
| 708 | 'struct bpf_redir_neigh',
|
| 709 | 'struct bpf_sock',
|
| 710 | 'struct bpf_sock_addr',
|
| 711 | 'struct bpf_sock_ops',
|
| 712 | 'struct bpf_sock_tuple',
|
| 713 | 'struct bpf_spin_lock',
|
| 714 | 'struct bpf_sysctl',
|
| 715 | 'struct bpf_tcp_sock',
|
| 716 | 'struct bpf_tunnel_key',
|
| 717 | 'struct bpf_xfrm_state',
|
| 718 | 'struct linux_binprm',
|
| 719 | 'struct pt_regs',
|
| 720 | 'struct sk_reuseport_md',
|
| 721 | 'struct sockaddr',
|
| 722 | 'struct tcphdr',
|
| 723 | 'struct seq_file',
|
| 724 | 'struct tcp6_sock',
|
| 725 | 'struct tcp_sock',
|
| 726 | 'struct tcp_timewait_sock',
|
| 727 | 'struct tcp_request_sock',
|
| 728 | 'struct udp6_sock',
|
| 729 | 'struct unix_sock',
|
| 730 | 'struct task_struct',
|
| 731 | 'struct cgroup',
|
| 732 |
|
| 733 | 'struct __sk_buff',
|
| 734 | 'struct sk_msg_md',
|
| 735 | 'struct xdp_md',
|
| 736 | 'struct path',
|
| 737 | 'struct btf_ptr',
|
| 738 | 'struct inode',
|
| 739 | 'struct socket',
|
| 740 | 'struct file',
|
| 741 | 'struct bpf_timer',
|
| 742 | 'struct mptcp_sock',
|
| 743 | 'struct bpf_dynptr',
|
| 744 | 'struct iphdr',
|
| 745 | 'struct ipv6hdr',
|
| 746 | ]
|
| 747 | known_types = {
|
| 748 | '...',
|
| 749 | 'void',
|
| 750 | 'const void',
|
| 751 | 'char',
|
| 752 | 'const char',
|
| 753 | 'int',
|
| 754 | 'long',
|
| 755 | 'unsigned long',
|
| 756 |
|
| 757 | '__be16',
|
| 758 | '__be32',
|
| 759 | '__wsum',
|
| 760 |
|
| 761 | 'struct bpf_fib_lookup',
|
| 762 | 'struct bpf_perf_event_data',
|
| 763 | 'struct bpf_perf_event_value',
|
| 764 | 'struct bpf_pidns_info',
|
| 765 | 'struct bpf_redir_neigh',
|
| 766 | 'struct bpf_sk_lookup',
|
| 767 | 'struct bpf_sock',
|
| 768 | 'struct bpf_sock_addr',
|
| 769 | 'struct bpf_sock_ops',
|
| 770 | 'struct bpf_sock_tuple',
|
| 771 | 'struct bpf_spin_lock',
|
| 772 | 'struct bpf_sysctl',
|
| 773 | 'struct bpf_tcp_sock',
|
| 774 | 'struct bpf_tunnel_key',
|
| 775 | 'struct bpf_xfrm_state',
|
| 776 | 'struct linux_binprm',
|
| 777 | 'struct pt_regs',
|
| 778 | 'struct sk_reuseport_md',
|
| 779 | 'struct sockaddr',
|
| 780 | 'struct tcphdr',
|
| 781 | 'struct seq_file',
|
| 782 | 'struct tcp6_sock',
|
| 783 | 'struct tcp_sock',
|
| 784 | 'struct tcp_timewait_sock',
|
| 785 | 'struct tcp_request_sock',
|
| 786 | 'struct udp6_sock',
|
| 787 | 'struct unix_sock',
|
| 788 | 'struct task_struct',
|
| 789 | 'struct cgroup',
|
| 790 | 'struct path',
|
| 791 | 'const struct path',
|
| 792 | 'struct btf_ptr',
|
| 793 | 'struct inode',
|
| 794 | 'struct socket',
|
| 795 | 'struct file',
|
| 796 | 'struct bpf_timer',
|
| 797 | 'struct mptcp_sock',
|
| 798 | 'struct bpf_dynptr',
|
| 799 | 'const struct bpf_dynptr',
|
| 800 | 'struct iphdr',
|
| 801 | 'struct ipv6hdr',
|
| 802 | }
|
| 803 | mapped_types = {
|
| 804 | 'u8': '__u8',
|
| 805 | 'u16': '__u16',
|
| 806 | 'u32': '__u32',
|
| 807 | 'u64': '__u64',
|
| 808 | 's8': '__s8',
|
| 809 | 's16': '__s16',
|
| 810 | 's32': '__s32',
|
| 811 | 's64': '__s64',
|
| 812 | 'size_t': 'unsigned long',
|
| 813 | 'struct bpf_map': 'void',
|
| 814 | 'struct sk_buff': 'struct __sk_buff',
|
| 815 | 'const struct sk_buff': 'const struct __sk_buff',
|
| 816 | 'struct sk_msg_buff': 'struct sk_msg_md',
|
| 817 | 'struct xdp_buff': 'struct xdp_md',
|
| 818 | }
|
| 819 | |
| 820 | overloaded_helpers = [
|
| 821 | 'bpf_get_socket_cookie',
|
| 822 | 'bpf_sk_assign',
|
| 823 | ]
|
| 824 |
|
| 825 | def print_header(self):
|
| 826 | header = '''\
|
| 827 | /* This is auto-generated file. See bpf_doc.py for details. */
|
| 828 |
|
| 829 | /* Forward declarations of BPF structs */'''
|
| 830 |
|
| 831 | print(header)
|
| 832 | for fwd in self.type_fwds:
|
| 833 | print('%s;' % fwd)
|
| 834 | print('')
|
| 835 |
|
| 836 | used_attrs = set()
|
| 837 | for helper in self.elements:
|
| 838 | for attr in helper.attrs:
|
| 839 | used_attrs.add(attr)
|
| 840 | for attr in sorted(used_attrs):
|
| 841 | print('#ifndef %s' % attr)
|
| 842 | print('#if __has_attribute(%s)' % ATTRS[attr])
|
| 843 | print('#define %s __attribute__((%s))' % (attr, ATTRS[attr]))
|
| 844 | print('#else')
|
| 845 | print('#define %s' % attr)
|
| 846 | print('#endif')
|
| 847 | print('#endif')
|
| 848 | if used_attrs:
|
| 849 | print('')
|
| 850 |
|
| 851 | def print_footer(self):
|
| 852 | footer = ''
|
| 853 | print(footer)
|
| 854 |
|
| 855 | def map_type(self, t):
|
| 856 | if t in self.known_types:
|
| 857 | return t
|
| 858 | if t in self.mapped_types:
|
| 859 | return self.mapped_types[t]
|
| 860 | print("Unrecognized type '%s', please add it to known types!" % t,
|
| 861 | file=sys.stderr)
|
| 862 | sys.exit(1)
|
| 863 |
|
| 864 | seen_helpers = set()
|
| 865 |
|
| 866 | def print_one(self, helper):
|
| 867 | proto = helper.proto_break_down()
|
| 868 |
|
| 869 | if proto['name'] in self.seen_helpers:
|
| 870 | return
|
| 871 | self.seen_helpers.add(proto['name'])
|
| 872 |
|
| 873 | print('/*')
|
| 874 | print(" * %s" % proto['name'])
|
| 875 | print(" *")
|
| 876 | if (helper.desc):
|
| 877 | |
| 878 | |
| 879 | for line in re.sub('\n$', '', helper.desc, count=1).split('\n'):
|
| 880 | print(' *{}{}'.format(' \t' if line else '', line))
|
| 881 |
|
| 882 | if (helper.ret):
|
| 883 | print(' *')
|
| 884 | print(' * Returns')
|
| 885 | for line in helper.ret.rstrip().split('\n'):
|
| 886 | print(' *{}{}'.format(' \t' if line else '', line))
|
| 887 |
|
| 888 | print(' */')
|
| 889 | print('static ', end='')
|
| 890 | if helper.attrs:
|
| 891 | print('%s ' % (" ".join(helper.attrs)), end='')
|
| 892 | print('%s %s(* const %s)(' % (self.map_type(proto['ret_type']),
|
| 893 | proto['ret_star'], proto['name']), end='')
|
| 894 | comma = ''
|
| 895 | for i, a in enumerate(proto['args']):
|
| 896 | t = a['type']
|
| 897 | n = a['name']
|
| 898 | if proto['name'] in self.overloaded_helpers and i == 0:
|
| 899 | t = 'void'
|
| 900 | n = 'ctx'
|
| 901 | one_arg = '{}{}'.format(comma, self.map_type(t))
|
| 902 | if n:
|
| 903 | if a['star']:
|
| 904 | one_arg += ' {}'.format(a['star'])
|
| 905 | else:
|
| 906 | one_arg += ' '
|
| 907 | one_arg += '{}'.format(n)
|
| 908 | comma = ', '
|
| 909 | print(one_arg, end='')
|
| 910 |
|
| 911 | print(') = (void *) %d;' % helper.enum_val)
|
| 912 | print('')
|
| 913 |
|
| 914 |
|
| 915 | class PrinterHelpersJSON(Printer):
|
| 916 | |
| 917 | A printer for dumping collected information about helpers as a JSON file.
|
| 918 | @parser: A HeaderParser with Helper objects
|
| 919 |
|
| 920 |
|
| 921 | def __init__(self, parser):
|
| 922 | self.elements = parser.helpers
|
| 923 | self.elem_number_check(
|
| 924 | parser.desc_unique_helpers,
|
| 925 | parser.define_unique_helpers,
|
| 926 | "helper",
|
| 927 | "___BPF_FUNC_MAPPER",
|
| 928 | )
|
| 929 |
|
| 930 | def print_all(self):
|
| 931 | helper_dicts = [helper.to_dict() for helper in self.elements]
|
| 932 | out_dict = {'helpers': helper_dicts}
|
| 933 | print(json.dumps(out_dict, indent=4))
|
| 934 |
|
| 935 |
|
| 936 | class PrinterSyscallJSON(Printer):
|
| 937 | |
| 938 | A printer for dumping collected syscall information as a JSON file.
|
| 939 | @parser: A HeaderParser with APIElement objects
|
| 940 |
|
| 941 |
|
| 942 | def __init__(self, parser):
|
| 943 | self.elements = parser.commands
|
| 944 | self.elem_number_check(parser.desc_syscalls, parser.enum_syscalls, 'syscall', 'bpf_cmd')
|
| 945 |
|
| 946 | def print_all(self):
|
| 947 | syscall_dicts = [syscall.to_dict() for syscall in self.elements]
|
| 948 | out_dict = {'syscall': syscall_dicts}
|
| 949 | print(json.dumps(out_dict, indent=4))
|
| 950 |
|
| 951 | |
| 952 |
|
| 953 | |
| 954 | |
| 955 | |
| 956 | script = os.path.abspath(sys.argv[0])
|
| 957 | linuxRoot = os.path.dirname(os.path.dirname(script))
|
| 958 | bpfh = os.path.join(linuxRoot, 'include/uapi/linux/bpf.h')
|
| 959 |
|
| 960 | |
| 961 | printers = {
|
| 962 | 'helpers': {
|
| 963 | 'rst': PrinterHelpersRST,
|
| 964 | 'json': PrinterHelpersJSON,
|
| 965 | 'header': PrinterHelpersHeader,
|
| 966 | },
|
| 967 | 'syscall': {
|
| 968 | 'rst': PrinterSyscallRST,
|
| 969 | 'json': PrinterSyscallJSON
|
| 970 | },
|
| 971 | }
|
| 972 |
|
| 973 | argParser = argparse.ArgumentParser(description="""
|
| 974 | Parse eBPF header file and generate documentation for the eBPF API.
|
| 975 | The RST-formatted output produced can be turned into a manual page with the
|
| 976 | rst2man utility.
|
| 977 | """)
|
| 978 | argParser.add_argument('--header', action='store_true',
|
| 979 | help='generate C header file')
|
| 980 | argParser.add_argument('--json', action='store_true',
|
| 981 | help='generate a JSON')
|
| 982 | if (os.path.isfile(bpfh)):
|
| 983 | argParser.add_argument('--filename', help='path to include/uapi/linux/bpf.h',
|
| 984 | default=bpfh)
|
| 985 | else:
|
| 986 | argParser.add_argument('--filename', help='path to include/uapi/linux/bpf.h')
|
| 987 | argParser.add_argument('target', nargs='?', default='helpers',
|
| 988 | choices=printers.keys(), help='eBPF API target')
|
| 989 |
|
| 990 | def error_die(message: str):
|
| 991 | argParser.print_usage(file=sys.stderr)
|
| 992 | print('Error: {}'.format(message), file=sys.stderr)
|
| 993 | exit(1)
|
| 994 |
|
| 995 | def parse_and_dump():
|
| 996 | args = argParser.parse_args()
|
| 997 |
|
| 998 | |
| 999 | headerParser = HeaderParser(args.filename)
|
| 1000 | headerParser.run()
|
| 1001 |
|
| 1002 | if args.header and args.json:
|
| 1003 | error_die('Use either --header or --json, not both')
|
| 1004 |
|
| 1005 | output_format = 'rst'
|
| 1006 | if args.header:
|
| 1007 | output_format = 'header'
|
| 1008 | elif args.json:
|
| 1009 | output_format = 'json'
|
| 1010 |
|
| 1011 | try:
|
| 1012 | printer = printers[args.target][output_format](headerParser)
|
| 1013 | |
| 1014 | printer.print_all()
|
| 1015 | except KeyError:
|
| 1016 | error_die('Unsupported target/format combination: "{}", "{}"'
|
| 1017 | .format(args.target, output_format))
|
| 1018 |
|
| 1019 | if __name__ == "__main__":
|
| 1020 | parse_and_dump()
|