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#!/usr/bin/env python3
# -*- coding: utf-8 -*-
# SPDX-License-Identifier: GPL-2.0-or-later
# Copyright (C) 2020 by the Linux Foundation
#
import sys
import email
import email.utils
import email.message
import email.header
import smtplib
import b4
import argparse
import base64
import logging
logger = b4.logger
def in_header_attest(lmsg: b4.LoreMessage, mode: str = 'pgp', replace: bool = False) -> None:
if lmsg.msg.get(b4.HDR_PATCH_HASHES):
if not replace:
logger.info(' attest: message already attested')
return
del lmsg.msg[b4.HDR_PATCH_HASHES]
del lmsg.msg[b4.HDR_PATCH_SIG]
logger.info(' attest: generating attestation hashes')
if not lmsg.attestation:
raise RuntimeError('Could not calculate patch attestation')
headers = list()
hparts = [
'v=1',
'h=sha256',
f'g={lmsg.git_patch_id}',
f'i={lmsg.attestation.ib}',
f'm={lmsg.attestation.mb}',
f'p={lmsg.attestation.pb}',
]
hhname, hhval = b4.dkim_canonicalize_header(b4.HDR_PATCH_HASHES, '; '.join(hparts))
headers.append(f'{hhname}:{hhval}')
logger.debug('Signing with mode=%s', mode)
if mode == 'pgp':
usercfg = b4.get_user_config()
keyid = usercfg.get('signingkey')
if not keyid:
raise RuntimeError('Please set user.signingKey to use this feature')
logger.debug('Using i=%s, s=0x%s', lmsg.fromemail, keyid.rstrip('!'))
gpgargs = ['-b', '-u', f'{keyid}']
hparts = [
'm=pgp',
f'i={lmsg.fromemail}',
's=0x%s' % keyid.rstrip('!'),
'b=',
]
shname, shval = b4.dkim_canonicalize_header(b4.HDR_PATCH_SIG, '; '.join(hparts))
headers.append(f'{shname}:{shval}')
payload = '\r\n'.join(headers).encode()
ecode, out, err = b4.gpg_run_command(gpgargs, payload)
if ecode > 0:
logger.critical('Running gpg failed')
logger.critical(err.decode())
raise RuntimeError('Running gpg failed')
bdata = base64.b64encode(out).decode()
shval += header_splitter(bdata)
else:
raise NotImplementedError('Mode %s not implemented' % mode)
hhdr = email.header.make_header([(hhval.encode(), 'us-ascii')], maxlinelen=78)
shdr = email.header.make_header([(shval.encode(), 'us-ascii')], maxlinelen=78)
lmsg.msg[b4.HDR_PATCH_HASHES] = hhdr
lmsg.msg[b4.HDR_PATCH_SIG] = shdr
def header_splitter(longstr: str, limit: int = 77) -> str:
splitstr = list()
first = True
while len(longstr) > limit:
at = limit
if first:
first = False
at -= 2
splitstr.append(longstr[:at])
longstr = longstr[at:]
splitstr.append(longstr)
return ' '.join(splitstr)
def attest_and_send(cmdargs: argparse.Namespace):
# Grab the message from stdin as bytes
if sys.stdin.isatty():
logger.critical('Pass the message to attest as stdin')
sys.exit(1)
inbytes = sys.stdin.buffer.read()
msg = email.message_from_bytes(inbytes)
lmsg = b4.LoreMessage(msg)
lmsg.load_hashes()
if not lmsg.attestation:
logger.debug('Nothing to attest in %s, sending as-is')
outbytes = inbytes
else:
in_header_attest(lmsg)
outbytes = lmsg.msg.as_bytes()
if cmdargs.nosend:
logger.info('--- MESSAGE FOLLOWS ---')
sys.stdout.buffer.write(outbytes)
return
if cmdargs.identity:
cfgname = f'sendemail\\.{cmdargs.identity}\\..*'
else:
cfgname = 'sendemail\\..*'
scfg = b4.get_config_from_git(cfgname)
sserver = scfg.get('smtpserver')
if not sserver:
logger.critical('MISSING: smtpserver option in %s', cfgname)
sys.exit(1)
if sserver[0] == '/':
args = [sserver, '-i'] + cmdargs.recipients
extraopts = scfg.get('smtpserveroption')
if extraopts:
args += extraopts.split()
ecode, out, err = b4._run_command(args, outbytes) # noqa
sys.stdout.buffer.write(out)
sys.stderr.buffer.write(err)
sys.exit(ecode)
sport = int(scfg.get('smtpserverport', '0'))
sdomain = scfg.get('smtpdomain')
suser = scfg.get('smtpuser')
spass = scfg.get('smtppass')
senc = scfg.get('smtpencryption', 'tls')
sfrom = scfg.get('from')
if not sfrom:
sfrom = lmsg.fromemail
logger.info('Connecting to %s', sserver)
if senc == 'ssl':
sconn = smtplib.SMTP_SSL(host=sserver, port=sport, local_hostname=sdomain)
else:
sconn = smtplib.SMTP(host=sserver, port=sport, local_hostname=sdomain)
if senc == 'tls':
sconn.starttls()
if suser:
logger.info('Logging in as user %s', suser)
sconn.login(suser, spass)
logger.info('Sending %s', lmsg.full_subject)
sconn.sendmail(sfrom, cmdargs.recipients, outbytes)
def attest_patches(cmdargs: argparse.Namespace) -> None:
for pf in cmdargs.patchfile:
with open(pf, 'rb') as fh:
msg = email.message_from_bytes(fh.read())
lmsg = b4.LoreMessage(msg)
lmsg.load_hashes()
if not lmsg.attestation:
logger.debug('Nothing to attest in %s, skipped')
continue
logger.info('Attesting: %s', pf)
in_header_attest(lmsg, replace=True)
with open(pf, 'wb') as fh:
fh.write(lmsg.msg.as_bytes())
if __name__ == '__main__':
# Special mode for running b4-send-email
# noinspection PyTypeChecker
parser = argparse.ArgumentParser(
prog='b4-send-email',
description='A drop-in wrapper for git-send-email to attest patches before sending',
formatter_class=argparse.ArgumentDefaultsHelpFormatter,
)
parser.add_argument('-d', '--debug', action='store_true', default=False,
help='Add more debugging info to the output')
parser.add_argument('-q', '--quiet', action='store_true', default=False,
help='Output critical information only')
parser.add_argument('-i', dest='_compat', action='store_true', default=True,
help='Sendmail compatibility thingamabob')
parser.add_argument('--identity', default='b4',
help='The sendemail identity to use for real smtp/sendmail settings')
parser.add_argument('-n', '--no-send', dest='nosend', action='store_true', default=False,
help='Do not send, just output what would be sent')
parser.add_argument('recipients', nargs='+', help='Message recipients')
_cmdargs = parser.parse_args()
logger.setLevel(logging.DEBUG)
ch = logging.StreamHandler()
formatter = logging.Formatter('b4: %(message)s')
ch.setFormatter(formatter)
if _cmdargs.quiet:
ch.setLevel(logging.CRITICAL)
elif _cmdargs.debug:
ch.setLevel(logging.DEBUG)
else:
ch.setLevel(logging.INFO)
logger.addHandler(ch)
attest_and_send(_cmdargs)
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