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