243 lines
8.5 KiB
Python
243 lines
8.5 KiB
Python
#!/usr/bin/python
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# vi: ts=4 expandtab
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#
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# Copyright (C) 2012 Canonical Ltd.
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# Copyright (C) 2012 Hewlett-Packard Development Company, L.P.
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#
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# Author: Scott Moser <scott.moser@canonical.com>
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# Author: Juerg Hafliger <juerg.haefliger@hp.com>
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#
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# This program is free software: you can redistribute it and/or modify
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# it under the terms of the GNU General Public License version 3, as
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# published by the Free Software Foundation.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program. If not, see <http://www.gnu.org/licenses/>.
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from StringIO import StringIO
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import csv
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import os
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import pwd
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from cloudinit import log as logging
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from cloudinit import util
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LOG = logging.getLogger(__name__)
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DEF_SSHD_CFG = "/etc/ssh/sshd_config"
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class AuthKeyEntry(object):
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"""
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AUTHORIZED_KEYS FILE FORMAT
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AuthorizedKeysFile specifies the file containing public keys for public
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key authentication; if none is specified, the default is
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~/.ssh/authorized_keys. Each line of the file contains one key (empty
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(because of the size of the public key encoding) up to a limit of 8 kilo-
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bytes, which permits DSA keys up to 8 kilobits and RSA keys up to 16
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kilobits. You don't want to type them in; instead, copy the
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identity.pub, id_dsa.pub, or the id_rsa.pub file and edit it.
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sshd enforces a minimum RSA key modulus size for protocol 1 and protocol
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2 keys of 768 bits.
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The options (if present) consist of comma-separated option specifica-
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tions. No spaces are permitted, except within double quotes. The fol-
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lowing option specifications are supported (note that option keywords are
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case-insensitive):
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"""
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def __init__(self, line, def_opt=None):
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self.line = str(line)
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(self.value, self.components) = self._parse(self.line, def_opt)
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def _extract_options(self, ent):
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"""
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The options (if present) consist of comma-separated option specifica-
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tions. No spaces are permitted, except within double quotes.
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Note that option keywords are case-insensitive.
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"""
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quoted = False
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i = 0
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while (i < len(ent) and
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((quoted) or (ent[i] not in (" ", "\t")))):
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curc = ent[i]
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if i + 1 >= len(ent):
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i = i + 1
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break
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nextc = ent[i + 1]
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if curc == "\\" and nextc == '"':
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i = i + 1
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elif curc == '"':
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quoted = not quoted
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i = i + 1
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options = ent[0:i]
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options_lst = []
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reader = csv.reader(StringIO(options), quoting=csv.QUOTE_NONE)
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for row in reader:
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for e in row:
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e = e.strip()
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if e:
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options_lst.append(e)
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toks = []
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if i + 1 < len(ent):
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toks = ent[i + 1:].split(None, 3)
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return (options_lst, toks)
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def _form_components(self, toks):
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components = {}
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if len(toks) == 1:
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components['base64'] = toks[0]
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elif len(toks) == 2:
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components['base64'] = toks[0]
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components['comment'] = toks[1]
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elif len(toks) == 3:
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components['keytype'] = toks[0]
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components['base64'] = toks[1]
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components['comment'] = toks[2]
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return components
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def get(self, piece):
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return self.components.get(piece)
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def _parse(self, in_line, def_opt):
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line = in_line.rstrip("\r\n")
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if line.startswith("#") or line.strip() == '':
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return (False, {})
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else:
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ent = line.strip()
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toks = ent.split(None, 3)
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tmp_components = {}
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if def_opt:
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tmp_components['options'] = def_opt
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if len(toks) < 4:
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tmp_components.update(self._form_components(toks))
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else:
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(options, toks) = self._extract_options(ent)
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if options:
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tmp_components['options'] = ",".join(options)
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tmp_components.update(self._form_components(toks))
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# We got some useful value!
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return (True, tmp_components)
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def __str__(self):
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if not self.value:
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return self.line
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else:
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toks = []
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if 'options' in self.components:
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toks.append(self.components['options'])
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if 'keytype' in self.components:
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toks.append(self.components['keytype'])
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if 'base64' in self.components:
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toks.append(self.components['base64'])
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if 'comment' in self.components:
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toks.append(self.components['comment'])
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if not toks:
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return ''
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return ' '.join(toks)
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def update_authorized_keys(fname, keys):
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lines = []
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try:
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if os.path.isfile(fname):
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lines = util.load_file(fname).splitlines()
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except (IOError, OSError):
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util.logexc(LOG, "Error reading lines from %s", fname)
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lines = []
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to_add = list(keys)
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for i in range(0, len(lines)):
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ent = AuthKeyEntry(lines[i])
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if not ent.value:
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continue
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# Replace those with the same base64
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for k in keys:
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if not k.value:
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continue
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if k.get('base64') == ent.get('base64'):
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# Replace it with our better one
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ent = k
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# Don't add it later
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to_add.remove(k)
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lines[i] = str(ent)
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# Now append any entries we did not match above
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for key in to_add:
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lines.append(str(key))
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# Ensure it ends with a newline
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lines.append('')
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return '\n'.join(lines)
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def setup_user_keys(keys, user, key_prefix, sshd_config_fn=None):
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if not sshd_config_fn:
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sshd_config_fn = DEF_SSHD_CFG
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pwent = pwd.getpwnam(user)
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ssh_dir = os.path.join(pwent.pw_dir, '.ssh')
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if not os.path.exists(ssh_dir):
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util.ensure_dir(ssh_dir, mode=0700)
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util.chownbyid(ssh_dir, pwent.pw_uid, pwent.pw_gid)
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key_entries = []
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for k in keys:
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key_entries.append(AuthKeyEntry(k, def_opt=key_prefix))
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with util.SeLinuxGuard(ssh_dir, recursive=True):
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try:
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# AuthorizedKeysFile may contain tokens
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# of the form %T which are substituted during connection set-up.
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# The following tokens are defined: %% is replaced by a literal
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# '%', %h is replaced by the home directory of the user being
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# authenticated and %u is replaced by the username of that user.
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ssh_cfg = parse_ssh_config(sshd_config_fn)
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akeys = ssh_cfg.get("authorizedkeysfile", '')
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akeys = akeys.strip()
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if not akeys:
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akeys = "%h/.ssh/authorized_keys"
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akeys = akeys.replace("%h", pwent.pw_dir)
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akeys = akeys.replace("%u", user)
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akeys = akeys.replace("%%", '%')
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if not akeys.startswith('/'):
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akeys = os.path.join(pwent.pw_dir, akeys)
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authorized_keys = akeys
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except (IOError, OSError):
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authorized_keys = os.path.join(ssh_dir, 'authorized_keys')
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util.logexc(LOG, ("Failed extracting 'AuthorizedKeysFile'"
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" in ssh config"
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" from %s, using 'AuthorizedKeysFile' file"
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" %s instead"),
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sshd_config_fn, authorized_keys)
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content = update_authorized_keys(authorized_keys, key_entries)
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util.ensure_dir(os.path.dirname(authorized_keys), mode=0700)
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util.write_file(authorized_keys, content, mode=0600)
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util.chownbyid(authorized_keys, pwent.pw_uid, pwent.pw_gid)
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def parse_ssh_config(fname):
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# The file contains keyword-argument pairs, one per line.
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# Lines starting with '#' and empty lines are interpreted as comments.
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# Note: key-words are case-insensitive and arguments are case-sensitive
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ret = {}
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if not os.path.isfile(fname):
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return ret
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for line in util.load_file(fname).splitlines():
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line = line.strip()
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if not line or line.startswith("#"):
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continue
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(key, val) = line.split(None, 1)
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key = key.strip().lower()
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if key:
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ret[key] = val
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return ret
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