path: root/bin/update-vuln

#!/usr/bin/env python3
# -*- coding: utf-8 -*-
"""
  update-vuln - #1001453

  - mark a given released suite (stable/oldstable/LTS) as <not-affected>
    for a specific CVE ID
  - add a bug number to an existing CVE entry
  - add a NOTE: entry to an existing CVE

Only make one change to one CVE at a time. Review and merge that
change and delete the merged file before updating the same CVE.

The workflow would be:
./bin/update-vuln --cve CVE-YYYY-NNNNN ...
# on exit zero:
./bin/merge-cve-files ./CVE-YYYY-NNNNN.list
# review change to data/CVE/list
git diff data/CVE/list
rm ./CVE-YYYY-NNNNN.list
# .. repeat
git add data/CVE/list
git commit

"""
#  Copyright 2021-2022 Neil Williams <codehelp@debian.org>
#
#  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; either version 2 of the License, or
#  (at your option) any later version.
#
#  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, write to the Free Software
#  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
#  MA 02110-1301, USA.

import os
import argparse
import bisect
import logging
import sys

import setup_paths  # noqa # pylint: disable=unused-import
from sectracker.parsers import (
    PackageAnnotation,
    PackageBugAnnotation,
    StringAnnotation,
    Bug,
    cvelist,
    writecvelist,
)

# pylint: disable=line-too-long


class ParseUpdates:
    """
    Update a CVE with requested changes and produce a file for
    manual review and use with merge-cve-files.
    """

    def __init__(self):
        self.cves = []
        self.bugs = {}
        self.marker = "aaaaaaaaaaaaa"  # replacement for NoneType to always sort first
        self.logger = logging.getLogger("update-vuln")
        self.logger.setLevel(logging.DEBUG)
        # console logging
        ch_log = logging.StreamHandler()
        ch_log.setLevel(logging.DEBUG)
        formatter = logging.Formatter("%(name)s - %(levelname)s - %(message)s")
        ch_log.setFormatter(formatter)
        self.logger.addHandler(ch_log)

    def _read_cvelist(self):
        """Build a list of Bug items for the CVE from data/CVE/list"""
        os.chdir(os.path.dirname(os.path.dirname(os.path.realpath(__file__))))
        data, _ = cvelist("data/CVE/list")  # pylint: disable=no-value-for-parameter
        for cve in self.cves:
            for bug in data:
                if bug.header.name == cve:
                    self.bugs[cve] = bug

    def _add_annotation_to_cve(self, cve, annotation):
        """
        Adds an annotation to a CVE entry.

        StringAnnotation - appended to the end
        PackageAnnotation - inserted in alphabetical order by release

        Accounts for PackageAnnotation.release == None for unstable.
        """
        if isinstance(annotation, PackageAnnotation):
            store = {ann.release: ann for ann in self.bugs[cve].annotations if isinstance(ann, PackageAnnotation)}
            store[annotation.release] = annotation
            # this is needed despite python3 >= 3.7 having ordered dicts
            # because using the dict.keys() would need a copy of that list anyway.
            existing = [ann.release for ann in self.bugs[cve].annotations if isinstance(ann, PackageAnnotation)]
            if None in existing:
                # release == None for unstable
                index = existing.index(None)
                existing[index] = self.marker
            insertion = annotation.release if annotation.release else self.marker

            # bisect cannot work with NoneType
            bisect.insort(existing, insertion)

            if self.marker in existing:
                index = existing.index(self.marker)
                existing[index] = None

            bug_list = []
            for item in existing:
                bug_list.append(store[item])

        elif isinstance(annotation, StringAnnotation):
            bug_list = list(self.bugs[cve].annotations)
            bug_list.append(annotation)
        else:
            raise ValueError(f"Unsupported annotation type: {type(annotation)}")

        return Bug(self.bugs[cve].file, self.bugs[cve].header, tuple(bug_list))

    def _replace_annotation_on_line(self, cve, line, mod_line):
        index = self.bugs[cve].annotations.index(line)
        bug_list = list(self.bugs[cve].annotations)
        bug_list[index] = mod_line
        return Bug(self.bugs[cve].file, self.bugs[cve].header, tuple(bug_list))

    def write_modified(self, modified, cve_file):
        """
        Write out a CVE snippet for review and merge

        Fails if the file already exists.
        """
        if not modified:
            return 0
        if not isinstance(modified, list):
            return 0
        if os.path.exists(cve_file):
            self.logger.critical(
                "%s already exists - merge the update and remove the file first.",
                cve_file,
            )
            return -1
        for cve in modified:
            self.logger.info("Writing to ./%s with update for %s", cve_file, cve.header.name)
        with open(cve_file, "a") as snippet:
            writecvelist(modified, snippet)
        return 0

    def mark_not_affected(self, suite, src, description):
        """
        Writes out a CVE file snippet with the filename:
        ./<cve>.list
        Fails if the file already exists.
        """
        release = suite
        if suite in ("unstable", "sid"):
            # special handling for unstable
            suite = None
            release = "unstable"
        modified = []
        cve = self.cves[0]
        cve_file = f"{cve}.list"
        existing = [line.release for line in self.bugs[cve].annotations if isinstance(line, PackageAnnotation)]
        if suite not in existing:
            # line type release package kind version description flags
            line = PackageAnnotation(0, "package", suite, src, "not-affected", None, description, [])
            mod_bug = self._add_annotation_to_cve(cve, line)
            modified.append(mod_bug)
        for line in self.bugs[cve].annotations:
            if not isinstance(line, PackageAnnotation):
                continue  # skip notes etc.
            if line.release != suite:
                continue
            if line.package != src:
                continue
            # need to define the allowed changes
            # if fixed, version would need to be undone too.
            if line.kind == "not-affected":
                self.logger.info("Nothing to do for %s in %s.", cve, suite)
                return
            mod_line = line._replace(kind="not-affected")
            self.logger.info("Modified %s for %s in %s to <not-affected>", cve, src, release)
            if mod_line.version:
                self.logger.info("Removing version %s", line.version)
                ver_line = mod_line
                mod_line = ver_line._replace(version=None)
            if description:
                self.logger.info("Replacing description %s", line.description)
                desc_line = mod_line
                mod_line = desc_line._replace(description=description)
            elif mod_line.description:
                self.logger.info("Removing description %s", line.description)
                desc_line = mod_line
                mod_line = desc_line._replace(description=None)
            # removing a bug annotation is not covered, yet.
            mod_bug = self._replace_annotation_on_line(cve, line, mod_line)
            modified.append(mod_bug)
        self.write_modified(modified, cve_file)

    def add_note(self, note):
        """
        Writes out a CVE file snippet with the filename:
        ./<cve>.list
        Fails if the file already exists.
        """
        # use _add_annotation_to_cve to add the note
        modified = []
        cve = self.cves[0]
        cve_file = f"{cve}.list"
        existing = [note.description for note in self.bugs[cve].annotations if isinstance(note, StringAnnotation)]
        if note in existing:
            self.logger.info("Note already exists, ignoring")
            return
        new_note = StringAnnotation(line=0, type="NOTE", description=note)
        mod_bug = self._add_annotation_to_cve(cve, new_note)
        modified.append(mod_bug)
        self.write_modified(modified, cve_file)

    def add_bug_number(self, bug, itp=False):  # pylint: disable=too-many-locals
        """
        Writes out a CVE file snippet with the filename:
        ./<cve>.list
        Fails if the file already exists.
        """
        # bugs only apply to unstable (or itp)
        modified = []
        cve = self.cves[0]
        cve_file = f"{cve}.list"
        existing = [
            pkg.flags
            for pkg in self.bugs[cve].annotations
            if isinstance(pkg, PackageAnnotation)
            if not pkg.release and pkg.kind != "removed"
        ]
        bugs = [bug for sublist in existing for bug in sublist]
        if bugs:
            self.logger.warning("%s already has a bug annotation for unstable: %s", cve, bugs[0].bug)
            return -1
        pkgs = [
            pkg
            for pkg in self.bugs[cve].annotations
            if isinstance(pkg, PackageAnnotation)
            if not pkg.release and pkg.kind != "removed"
        ]
        if itp:
            # no useful entry will exist in pkgs
            new_flags = [PackageBugAnnotation(bug)]
            new_pkg = PackageAnnotation(
                0,
                "package",
                None,
                itp,
                "itp",
                None,
                None,
                new_flags,
            )
            others = []
        else:
            if not pkgs:
                self.logger.error("%s does not have a package annotation.", cve)
                return -1
            old_pkg = pkgs[0]
            if itp and old_pkg.kind == "fixed":
                self.logger.error("%s is already marked as <fixed> but --itp flag was set.", cve)
                return -3
            new_flags = [PackageBugAnnotation(bug)]
            new_pkg = PackageAnnotation(
                old_pkg.line,
                old_pkg.type,
                old_pkg.release,
                old_pkg.package,
                old_pkg.kind,
                old_pkg.version,
                old_pkg.description,
                new_flags,
            )
            bug_list = list(self.bugs[cve].annotations)
            others = [pkg for pkg in bug_list if pkg.line != old_pkg.line]
        bug_list = list(self.bugs[cve].annotations)
        # may need to retain the original order.
        new_list = [new_pkg] + others
        mod_bug = Bug(self.bugs[cve].file, self.bugs[cve].header, tuple(new_list))
        modified.append(mod_bug)
        self.write_modified(modified, cve_file)
        return 0

    def load_cve(self, cve):
        """Load all data for the specified CVE"""
        self.logger.info("Loading data for %s...", cve)
        self.cves.append(cve)
        self._read_cvelist()


def main():
    """
    This script does NOT reparse the output file - create, review and
    merge ONE update at a time.
    (For some operations, check-new-issues may be more suitable).

    For example, --bug 100 --itp intended_pkg_name
    then, merge-cve-list, then:
    --note "URL:"
    """
    parser = argparse.ArgumentParser(
        description="Make a single update to specified CVE data as not-affected, add bug number or add a note",
        usage="%(prog)s [-h] --cve CVE [--src SRC --suite SUITE "
        "[--description DESCRIPTION]] | [[--number NUMBER] [--itp SRC]] | [--note NOTE]",
        epilog="Data is written to a new <cve_number>.list "
        "file which can be used with './bin/merge-cve-files'. "
        "Make sure the output file is merged and removed before "
        "updating the same CVE again.",
    )

    required = parser.add_argument_group("Required arguments")
    required.add_argument("--cve", required=True, help="The CVE ID to update")

    affected = parser.add_argument_group(
        "Marking a CVE as not-affected - must use --src and --suite "
        "Optionally add a description or omit to remove the current description"
    )
    # needs to specify the src_package as well as suite to cope with removed etc.
    affected.add_argument("--src", help="Source package name in SUITE")
    affected.add_argument("--suite", default="unstable", help="Mark the CVE as <not-affected> in SUITE")
    affected.add_argument(
        "--description",
        help="Optional description of why the SRC is unaffected in SUITE",
    )

    buggy = parser.add_argument_group("Add a bug number to the CVE")
    buggy.add_argument("--number", help="Debian BTS bug number")
    buggy.add_argument(
        "--itp",
        metavar="SRC",
        help="Mark as an ITP bug for the specified source package name",
    )

    notes = parser.add_argument_group("Add a NOTE: entry to the CVE")
    notes.add_argument("--note", help="Content of the NOTE: entry to add to the CVE")

    args = parser.parse_args()
    parser = ParseUpdates()
    parser.load_cve(args.cve)

    logger = logging.getLogger("update-vuln")
    if not parser.bugs:
        logger.critical("Unable to parse CVE ID %s", args.cve)
        return -1
    if args.src and args.suite:
        parser.mark_not_affected(args.suite, args.src, args.description)
    if args.note:
        parser.add_note(args.note)
    if args.number:
        # to set itp properly, the source package name also needs to be set.
        parser.add_bug_number(args.number, args.itp)
    return 0


if __name__ == "__main__":
    sys.exit(main())