pmbootstrap/pmb/chroot/apk_static.py

185 lines
6.6 KiB
Python

"""
Copyright 2018 Oliver Smith
This file is part of pmbootstrap.
pmbootstrap 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, either version 3 of the License, or
(at your option) any later version.
pmbootstrap 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 pmbootstrap. If not, see <http://www.gnu.org/licenses/>.
"""
import os
import logging
import shutil
import tarfile
import tempfile
import stat
import pmb.helpers.run
import pmb.config
import pmb.config.load
import pmb.parse.apkindex
import pmb.helpers.http
import pmb.parse.version
def read_signature_info(tar):
"""
Find various information about the signature, that was used to sign
/sbin/apk.static inside the archive (not to be confused with the normal apk
archive signature!)
:returns: (sigfilename, sigkey_path)
"""
# Get signature filename and key
prefix = "sbin/apk.static.SIGN.RSA."
sigfilename = None
for filename in tar.getnames():
if filename.startswith(prefix):
sigfilename = filename
break
if not sigfilename:
raise RuntimeError("Could not find signature filename in apk." +
" This means, that your apk file is damaged. Delete it" +
" and try again. If the problem persists, fill out a bug" +
" report.")
sigkey = sigfilename[len(prefix):]
logging.debug("sigfilename: " + sigfilename)
logging.debug("sigkey: " + sigkey)
# Get path to keyfile on disk
sigkey_path = pmb.config.apk_keys_path + "/" + sigkey
if "/" in sigkey or not os.path.exists(sigkey_path):
logging.debug("sigkey_path: " + sigkey_path)
raise RuntimeError("Invalid signature key: " + sigkey)
return (sigfilename, sigkey_path)
def extract_temp(tar, sigfilename):
"""
Extract apk.static and signature as temporary files.
"""
ret = {
"apk": {
"filename": "sbin/apk.static",
"temp_path": None
},
"sig": {
"filename": sigfilename,
"temp_path": None
}
}
for ftype in ret.keys():
member = tar.getmember(ret[ftype]["filename"])
handle, path = tempfile.mkstemp(ftype, "pmbootstrap")
handle = open(handle, "wb")
ret[ftype]["temp_path"] = path
shutil.copyfileobj(tar.extractfile(member), handle)
logging.debug("extracted: " + path)
handle.close()
return ret
def verify_signature(args, files, sigkey_path):
"""
Verify the signature with openssl.
:param files: return value from extract_temp()
:raises RuntimeError: when verification failed and removes temp files
"""
logging.debug("Verify apk.static signature with " + sigkey_path)
try:
pmb.helpers.run.user(args, ["openssl", "dgst", "-sha1", "-verify",
sigkey_path, "-signature", files[
"sig"]["temp_path"],
files["apk"]["temp_path"]])
except BaseException:
os.unlink(files["sig"]["temp_path"])
os.unlink(files["apk"]["temp_path"])
raise RuntimeError("Failed to validate signature of apk.static."
" Either openssl is not installed, or the"
" download failed. Run 'pmbootstrap zap -hc' to"
" delete the download and try again.")
def extract(args, version, apk_path):
"""
Extract everything to temporary locations, verify signatures and reported
versions. When everything is right, move the extracted apk.static to the
final location.
"""
# Extract to a temporary path
with tarfile.open(apk_path, "r:gz") as tar:
sigfilename, sigkey_path = read_signature_info(tar)
files = extract_temp(tar, sigfilename)
# Verify signature
verify_signature(args, files, sigkey_path)
os.unlink(files["sig"]["temp_path"])
temp_path = files["apk"]["temp_path"]
# Verify the version, that the extracted binary reports
logging.debug("Verify the version reported by the apk.static binary" +
" (must match the package version " + version + ")")
os.chmod(temp_path, os.stat(temp_path).st_mode | stat.S_IEXEC)
version_bin = pmb.helpers.run.user(args, [temp_path, "--version"],
output_return=True)
version_bin = version_bin.split(" ")[1].split(",")[0]
if not version.startswith(version_bin + "-r"):
os.unlink(temp_path)
raise RuntimeError("Downloaded apk-tools-static-" + version + ".apk,"
" but the apk binary inside that package reports to be"
" version: " + version_bin + "! Looks like a downgrade attack"
" from a malicious server! Switch the server (-m) and try again.")
# Move it to the right path
target_path = args.work + "/apk.static"
shutil.move(temp_path, target_path)
def download(args, file):
"""
Download a single file from an Alpine mirror.
"""
base_url = args.mirror_alpine + "edge/main/" + args.arch_native
return pmb.helpers.http.download(args, base_url + "/" + file, file)
def init(args):
"""
Download, verify, extract $WORK/apk.static.
"""
# Get and parse the APKINDEX
apkindex = pmb.helpers.repo.alpine_apkindex_path(args, "main")
index_data = pmb.parse.apkindex.package(args, "apk-tools-static",
indexes=[apkindex])
version = index_data["version"]
# Extract and verify the apk-tools-static version
version_min = pmb.config.apk_tools_static_min_version
apk_name = "apk-tools-static-" + version + ".apk"
if pmb.parse.version.compare(version, version_min) == -1:
raise RuntimeError("Your APKINDEX has an outdated version of"
" apk-tools-static (your version: " + version +
", expected at least:" + version_min + "). Please" +
" run 'pmbootstrap update'.")
# Download, extract, verify apk-tools-static
apk_static = download(args, apk_name)
extract(args, version, apk_static)
def run(args, parameters):
pmb.helpers.run.root(args, [args.work + "/apk.static"] + parameters)