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ssh.py
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ssh.py
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# Copyright 2020 Canonical, Ltd.
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, version 3.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
import logging
import os
import pwd
from pathlib import Path
from subiquitycore.utils import run_command
log = logging.getLogger("subiquitycore.ssh")
def host_key_fingerprints():
"""Query sshd to find the host keys and then fingerprint them.
Returns a sequence of (key-type, fingerprint) pairs.
"""
try:
config = run_command(["sshd", "-T"])
except FileNotFoundError:
log.debug("sshd not found")
return []
if config.returncode != 0:
log.debug("sshd -T failed %r", config.stderr)
return []
keyfiles = []
for line in config.stdout.splitlines():
if line.startswith("hostkey "):
keyfiles.append(line.split(None, 1)[1])
info = []
for keyfile in keyfiles:
info.extend(fingerprints(keyfile))
return info
def fingerprints(keyfile):
info = []
cp = run_command(["ssh-keygen", "-lf", keyfile])
if cp.returncode != 0:
log.debug("ssh-keygen -lf %s failed %r", keyfile, cp.stderr)
return info
for line in cp.stdout.splitlines():
parts = line.strip().replace("\r", "").split()
fingerprint = parts[1]
keytype = parts[-1].strip("()")
info.append((keytype, fingerprint))
return info
host_keys_intro = _(
"""\
The host key fingerprints are:
"""
)
host_key_tmpl = """
{keytype:{width}} {fingerprint}"""
single_host_key_tmpl = _(
"""\
The {keytype} host key fingerprint is:
{fingerprint}
"""
)
def host_key_info(runtime_state_dir=None):
if runtime_state_dir:
# host fingerprints information may have already been prepared by the
# platform glue
host_fingerprints = Path(runtime_state_dir) / "host-fingerprints.txt"
log.debug(
"pre-made host finterprints %s present: %s",
host_fingerprints,
host_fingerprints.is_file(),
)
if host_fingerprints.is_file():
with open(host_fingerprints, "r") as fp:
return fp.read()
return summarize_host_keys(host_key_fingerprints())
def summarize_host_keys(fingerprints):
if len(fingerprints) == 0:
return ""
if len(fingerprints) == 1:
[(keytype, fingerprint)] = fingerprints
return _(single_host_key_tmpl).format(keytype=keytype, fingerprint=fingerprint)
lines = [_(host_keys_intro)]
longest_type = max([len(keytype) for keytype, _ in fingerprints])
for keytype, fingerprint in fingerprints:
lines.append(
host_key_tmpl.format(
keytype=keytype, fingerprint=fingerprint, width=longest_type
)
)
return "".join(lines)
def user_key_fingerprints(username):
try:
user_info = pwd.getpwnam(username)
except KeyError:
log.exception("getpwnam(%s) failed", username)
return []
user_key_file = "{}/.ssh/authorized_keys".format(user_info.pw_dir)
if os.path.exists(user_key_file):
return fingerprints(user_key_file)
else:
return []
def get_ips_standalone():
from probert.prober import Prober
from subiquitycore.models.network import NETDEV_IGNORED_IFACE_TYPES
prober = Prober()
prober.probe_network()
links = prober.get_results()["network"]["links"]
ips = []
for link in sorted(links, key=lambda link: link["netlink_data"]["name"]):
if link["type"] in NETDEV_IGNORED_IFACE_TYPES:
continue
for addr in link["addresses"]:
if addr["scope"] == "global":
ips.append(addr["address"].split("/")[0])
return ips