a055604e6f
* guix/cve.scm (<cve>)[references]: Rename accessor to 'cve-references' and fix adjust exported name accordingly.
429 lines
15 KiB
Scheme
429 lines
15 KiB
Scheme
;;; GNU Guix --- Functional package management for GNU
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;;; Copyright © 2015, 2016, 2017, 2018, 2019 Ludovic Courtès <ludo@gnu.org>
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;;;
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;;; This file is part of GNU Guix.
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;;;
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;;; GNU Guix is free software; you can redistribute it and/or modify it
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;;; under the terms of the GNU General Public License as published by
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;;; the Free Software Foundation; either version 3 of the License, or (at
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;;; your option) any later version.
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;;;
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;;; GNU Guix is distributed in the hope that it will be useful, but
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;;; 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 GNU Guix. If not, see <http://www.gnu.org/licenses/>.
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(define-module (guix cve)
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#:use-module (guix utils)
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#:use-module (guix http-client)
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#:use-module (guix json)
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#:use-module (guix i18n)
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#:use-module (json)
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#:use-module (web uri)
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#:use-module (srfi srfi-1)
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#:use-module (srfi srfi-9)
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#:use-module (srfi srfi-11)
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#:use-module (srfi srfi-19)
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#:use-module (srfi srfi-26)
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#:use-module (srfi srfi-34)
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#:use-module (srfi srfi-35)
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#:use-module (ice-9 match)
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#:use-module (ice-9 regex)
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#:use-module (ice-9 vlist)
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#:export (json->cve-items
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cve-item?
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cve-item-cve
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cve-item-configurations
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cve-item-published-date
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cve-item-last-modified-date
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cve?
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cve-id
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cve-data-type
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cve-data-format
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cve-references
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cve-reference?
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cve-reference-url
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cve-reference-tags
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vulnerability?
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vulnerability-id
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vulnerability-packages
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json->vulnerabilities
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current-vulnerabilities
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vulnerabilities->lookup-proc))
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;;; Commentary:
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;;;
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;;; This modules provides the tools to fetch, parse, and digest part of the
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;;; Common Vulnerabilities and Exposures (CVE) feeds provided by the US NIST
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;;; at <https://nvd.nist.gov/vuln/data-feeds>.
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;;;
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;;; Code:
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(define (string->date* str)
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(string->date str "~Y-~m-~dT~H:~M~z"))
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(define-json-mapping <cve-item> cve-item cve-item?
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json->cve-item
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(cve cve-item-cve "cve" json->cve) ;<cve>
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(configurations cve-item-configurations ;list of sexps
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"configurations" configuration-data->cve-configurations)
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(published-date cve-item-published-date
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"publishedDate" string->date*)
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(last-modified-date cve-item-last-modified-date
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"lastModifiedDate" string->date*))
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(define-json-mapping <cve> cve cve?
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json->cve
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(id cve-id "CVE_data_meta" ;string
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(cut assoc-ref <> "ID"))
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(data-type cve-data-type ;'CVE
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"data_type" string->symbol)
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(data-format cve-data-format ;'MITRE
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"data_format" string->symbol)
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(references cve-references ;list of <cve-reference>
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"references" reference-data->cve-references))
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(define-json-mapping <cve-reference> cve-reference cve-reference?
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json->cve-reference
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(url cve-reference-url) ;string
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(tags cve-reference-tags ;list of strings
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"tags" vector->list))
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(define (reference-data->cve-references alist)
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(map json->cve-reference
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(vector->list (assoc-ref alist "reference_data"))))
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(define %cpe-package-rx
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;; For applications: "cpe:2.3:a:VENDOR:PACKAGE:VERSION", or sometimes
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;; "cpe:2.3:a:VENDOR:PACKAGE:VERSION:PATCH-LEVEL".
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(make-regexp "^cpe:2\\.3:a:([^:]+):([^:]+):([^:]+):([^:]+):"))
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(define (cpe->package-name cpe)
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"Converts the Common Platform Enumeration (CPE) string CPE to a package
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name, in a very naive way. Return two values: the package name, and its
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version string. Return #f and #f if CPE does not look like an application CPE
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string."
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(cond ((regexp-exec %cpe-package-rx cpe)
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=>
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(lambda (matches)
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(values (match:substring matches 2)
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(match (match:substring matches 3)
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("*" '_)
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(version
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(string-append version
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(match (match:substring matches 4)
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("" "")
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(patch-level
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;; Drop the colon from things like
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;; "cpe:2.3:a:openbsd:openssh:6.8:p1".
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(string-drop patch-level 1)))))))))
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(else
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(values #f #f))))
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(define (cpe-match->cve-configuration alist)
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"Convert ALIST, a \"cpe_match\" alist, into an sexp representing the package
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and versions matched. Return #f if ALIST doesn't correspond to an application
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package."
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(let ((cpe (assoc-ref alist "cpe23Uri"))
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(starti (assoc-ref alist "versionStartIncluding"))
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(starte (assoc-ref alist "versionStartExcluding"))
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(endi (assoc-ref alist "versionEndIncluding"))
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(ende (assoc-ref alist "versionEndExcluding")))
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(let-values (((package version) (cpe->package-name cpe)))
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(and package
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`(,package
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,(cond ((and (or starti starte) (or endi ende))
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`(and ,(if starti `(>= ,starti) `(> ,starte))
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,(if endi `(<= ,endi) `(< ,ende))))
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(starti `(>= ,starti))
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(starte `(> ,starte))
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(endi `(<= ,endi))
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(ende `(< ,ende))
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(else version)))))))
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(define (configuration-data->cve-configurations alist)
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"Given ALIST, a JSON dictionary for the baroque \"configurations\"
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element found in CVEs, return an sexp such as (\"binutils\" (<
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\"2.31\")) that represents matching configurations."
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(define string->operator
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(match-lambda
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("OR" 'or)
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("AND" 'and)))
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(define (node->configuration node)
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(let ((operator (string->operator (assoc-ref node "operator"))))
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(cond
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((assoc-ref node "cpe_match")
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=>
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(lambda (matches)
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(let ((matches (vector->list matches)))
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(match (filter-map cpe-match->cve-configuration
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matches)
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(() #f)
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((one) one)
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(lst (cons operator lst))))))
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((assoc-ref node "children") ;typically for 'and'
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=>
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(lambda (children)
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(match (filter-map node->configuration (vector->list children))
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(() #f)
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((one) one)
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(lst (cons operator lst)))))
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(else
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#f))))
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(let ((nodes (vector->list (assoc-ref alist "nodes"))))
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(filter-map node->configuration nodes)))
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(define (json->cve-items json)
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"Parse JSON, an input port or a string, and return a list of <cve-item>
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records."
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(let* ((alist (json->scm json))
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(type (assoc-ref alist "CVE_data_type"))
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(format (assoc-ref alist "CVE_data_format"))
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(version (assoc-ref alist "CVE_data_version")))
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(unless (equal? type "CVE")
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(raise (condition (&message
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(message "invalid CVE feed")))))
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(unless (equal? format "MITRE")
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(raise (condition
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(&message
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(message (format #f (G_ "unsupported CVE format: '~a'")
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format))))))
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(unless (equal? version "4.0")
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(raise (condition
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(&message
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(message (format #f (G_ "unsupported CVE data version: '~a'")
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version))))))
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(map json->cve-item
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(vector->list (assoc-ref alist "CVE_Items")))))
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(define (version-matches? version sexp)
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"Return true if VERSION, a string, matches SEXP."
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(match sexp
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('_
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#t)
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((? string? expected)
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(version-prefix? expected version))
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(('or sexps ...)
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(any (cut version-matches? version <>) sexps))
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(('and sexps ...)
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(every (cut version-matches? version <>) sexps))
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(('< max)
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(version>? max version))
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(('<= max)
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(version>=? max version))
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(('> min)
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(version>? version min))
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(('>= min)
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(version>=? version min))))
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;;;
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;;; High-level interface.
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;;;
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(define %now
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(current-date))
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(define %current-year
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(date-year %now))
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(define %past-year
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(- %current-year 1))
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(define (yearly-feed-uri year)
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"Return the URI for the CVE feed for YEAR."
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(string->uri
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(string-append "https://nvd.nist.gov/feeds/json/cve/1.1/nvdcve-1.1-"
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(number->string year) ".json.gz")))
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(define %current-year-ttl
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;; According to <https://nvd.nist.gov/download.cfm#CVE_FEED>, feeds are
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;; updated "approximately every two hours."
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(* 60 30))
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(define %past-year-ttl
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;; Update the previous year's database more and more infrequently.
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(* 3600 24 (date-month %now)))
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(define-record-type <vulnerability>
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(vulnerability id packages)
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vulnerability?
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(id vulnerability-id) ;string
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(packages vulnerability-packages)) ;((p1 sexp1) (p2 sexp2) ...)
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(define vulnerability->sexp
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(match-lambda
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(($ <vulnerability> id packages)
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`(v ,id ,packages))))
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(define sexp->vulnerability
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(match-lambda
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(('v id (packages ...))
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(vulnerability id packages))))
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(define (cve-configuration->package-list config)
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"Parse CONFIG, a config sexp, and return a list of the form (P SEXP)
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where P is a package name and SEXP expresses constraints on the matching
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versions."
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(let loop ((config config)
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(packages '()))
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(match config
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(('or configs ...)
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(fold loop packages configs))
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(('and config _ ...) ;XXX
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(loop config packages))
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(((? string? package) '_) ;any version
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(cons `(,package _)
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(alist-delete package packages)))
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(((? string? package) sexp)
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(let ((previous (assoc-ref packages package)))
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(if previous
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(cons `(,package (or ,sexp ,@previous))
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(alist-delete package packages))
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(cons `(,package ,sexp) packages)))))))
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(define (merge-package-lists lst)
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"Merge the list in LST, each of which has the form (p sexp), where P
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is the name of a package and SEXP is an sexp that constrains matching
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versions."
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(fold (lambda (plist result) ;XXX: quadratic
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(fold (match-lambda*
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(((package version) result)
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(match (assoc-ref result package)
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(#f
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(cons `(,package ,version) result))
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((previous)
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(cons `(,package (or ,version ,previous))
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(alist-delete package result))))))
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result
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plist))
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'()
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lst))
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(define (cve-item->vulnerability item)
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"Return a <vulnerability> corresponding to ITEM, a <cve-item> record;
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return #f if ITEM does not list any configuration or if it does not list
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any \"a\" (application) configuration."
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(let ((id (cve-id (cve-item-cve item))))
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(match (cve-item-configurations item)
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(() ;no configurations
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#f)
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((configs ...)
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(vulnerability id
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(merge-package-lists
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(map cve-configuration->package-list configs)))))))
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(define (json->vulnerabilities json)
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"Parse JSON, an input port or a string, and return the list of
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vulnerabilities found therein."
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(filter-map cve-item->vulnerability (json->cve-items json)))
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(define (write-cache input cache)
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"Read vulnerabilities as gzipped JSON from INPUT, and write it as a compact
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sexp to CACHE."
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(call-with-decompressed-port 'gzip input
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(lambda (input)
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(define vulns
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(json->vulnerabilities input))
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(write `(vulnerabilities
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1 ;format version
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,(map vulnerability->sexp vulns))
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cache))))
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(define (fetch-vulnerabilities year ttl)
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"Return the list of <vulnerability> for YEAR, assuming the on-disk cache has
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the given TTL (fetch from the NIST web site when TTL has expired)."
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(define (cache-miss uri)
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(format (current-error-port) "fetching CVE database for ~a...~%" year))
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(define (read* port)
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;; Disable read options to avoid populating the source property weak
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;; table, which speeds things up, saves memory, and works around
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;; <https://lists.gnu.org/archive/html/guile-devel/2017-09/msg00031.html>.
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(let ((options (read-options)))
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(dynamic-wind
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(lambda ()
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(read-disable 'positions))
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(lambda ()
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(read port))
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(lambda ()
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(read-options options)))))
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;; Note: We used to keep the original JSON files in cache but parsing it
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;; would take typically ~15s for a year of data. Thus, we instead store a
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;; summarized version thereof as an sexp, which can be parsed in 1s or so.
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(let* ((port (http-fetch/cached (yearly-feed-uri year)
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#:ttl ttl
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#:write-cache write-cache
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#:cache-miss cache-miss))
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(sexp (read* port)))
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(close-port port)
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(match sexp
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(('vulnerabilities 1 vulns)
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(map sexp->vulnerability vulns)))))
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(define (current-vulnerabilities)
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"Return the current list of Common Vulnerabilities and Exposures (CVE) as
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published by the US NIST."
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(let ((past-years (unfold (cut > <> 3)
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(lambda (n)
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(- %current-year n))
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1+
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1))
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(past-ttls (unfold (cut > <> 3)
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(lambda (n)
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(* n %past-year-ttl))
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1+
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1)))
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(append-map fetch-vulnerabilities
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(cons %current-year past-years)
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(cons %current-year-ttl past-ttls))))
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(define (vulnerabilities->lookup-proc vulnerabilities)
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"Return a lookup procedure built from VULNERABILITIES that takes a package
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name and optionally a version number. When the version is omitted, the lookup
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procedure returns a list of vulnerabilities; otherwise, it returns a list of
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vulnerabilities affecting the given package version."
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(define table
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;; Map package names to lists of version/vulnerability pairs.
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(fold (lambda (vuln table)
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(match vuln
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(($ <vulnerability> id packages)
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(fold (lambda (package table)
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(match package
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((name . versions)
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(vhash-cons name (cons vuln versions)
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table))))
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table
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packages))))
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vlist-null
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vulnerabilities))
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(lambda* (package #:optional version)
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(vhash-fold* (if version
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(lambda (pair result)
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(match pair
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((vuln sexp)
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(if (version-matches? version sexp)
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(cons vuln result)
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result))))
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(lambda (pair result)
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(match pair
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((vuln . _)
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(cons vuln result)))))
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'()
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package table)))
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;;; cve.scm ends here
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