mirror of
https://git.savannah.gnu.org/git/emacs.git
synced 2024-12-15 09:47:20 +00:00
390 lines
16 KiB
EmacsLisp
390 lines
16 KiB
EmacsLisp
;;; gnutls.el --- Support SSL/TLS connections through GnuTLS -*- lexical-binding: t; -*-
|
|
|
|
;; Copyright (C) 2010-2022 Free Software Foundation, Inc.
|
|
|
|
;; Author: Ted Zlatanov <tzz@lifelogs.com>
|
|
;; Keywords: comm, tls, ssl, encryption
|
|
;; Originally-By: Simon Josefsson (See https://josefsson.org/emacs-security/)
|
|
;; Thanks-To: Lars Magne Ingebrigtsen <larsi@gnus.org>
|
|
|
|
;; This file is part of GNU Emacs.
|
|
|
|
;; GNU Emacs 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.
|
|
|
|
;; GNU Emacs 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 GNU Emacs. If not, see <https://www.gnu.org/licenses/>.
|
|
|
|
;;; Commentary:
|
|
|
|
;; This package provides language bindings for the GnuTLS library
|
|
;; using the corresponding core functions in gnutls.c. It should NOT
|
|
;; be used directly, only through open-network-stream.
|
|
|
|
;; Simple test:
|
|
;;
|
|
;; (open-gnutls-stream "tls" "tls-buffer" "yourserver.com" "https")
|
|
;; (open-gnutls-stream "tls" "tls-buffer" "imap.gmail.com" "imaps")
|
|
|
|
;;; Code:
|
|
|
|
(require 'cl-lib)
|
|
(require 'puny)
|
|
|
|
(declare-function network-stream-certificate "network-stream"
|
|
(host service parameters))
|
|
|
|
(defgroup gnutls nil
|
|
"Emacs interface to the GnuTLS library."
|
|
:version "24.1"
|
|
:prefix "gnutls-"
|
|
:group 'comm)
|
|
|
|
(defcustom gnutls-algorithm-priority nil
|
|
"If non-nil, this should be a TLS priority string.
|
|
For instance, if you want to skip the \"dhe-rsa\" algorithm,
|
|
set this variable to \"normal:-dhe-rsa\".
|
|
|
|
This variable can be useful for modifying low-level TLS
|
|
connection parameters (for instance if you need to connect to a
|
|
host that only accepts a specific algorithm). However, in
|
|
general, Emacs network security is handled by the Network
|
|
Security Manager (NSM), and the default value of nil delegates
|
|
the job of checking the connection security to the NSM.
|
|
See Info node `(emacs) Network Security'."
|
|
:type '(choice (const nil)
|
|
string))
|
|
|
|
(defcustom gnutls-verify-error nil
|
|
"If non-nil, this should be t or a list of checks per hostname regex.
|
|
If nil, the default, failures in certificate verification will be
|
|
logged (subject to `gnutls-log-level'), but the connection will be
|
|
allowed to proceed.
|
|
If the value is a list, it should have the form
|
|
|
|
((HOST-REGEX FLAGS...) (HOST-REGEX FLAGS...) ...)
|
|
|
|
where each HOST-REGEX is a regular expression to be matched
|
|
against the hostname, on a first-match basis, and FLAGS is either
|
|
t or a list of one or more verification flags. The supported
|
|
flags and the corresponding conditions to be tested are:
|
|
|
|
:trustfiles -- certificate must be issued by a trusted authority.
|
|
:hostname -- hostname must match presented certificate's host name.
|
|
t -- all of the above conditions are tested.
|
|
|
|
If the condition test fails, an error will be signaled.
|
|
|
|
If the value of this variable is t, every connection will be subjected
|
|
to all of the tests described above.
|
|
|
|
The default value of this variable is nil, which means that no
|
|
checks are performed at the gnutls level. Instead the checks are
|
|
performed via `open-network-stream' at a higher level by the
|
|
Network Security Manager. See Info node `(emacs) Network
|
|
Security'."
|
|
:version "24.4"
|
|
:type '(choice
|
|
(const t)
|
|
(repeat :tag "List of hostname regexps with flags for each"
|
|
(list
|
|
(choice :tag "Hostname"
|
|
(const ".*" :tag "Any hostname")
|
|
regexp)
|
|
(set (const :trustfiles)
|
|
(const :hostname))))))
|
|
|
|
(defcustom gnutls-trustfiles
|
|
'(
|
|
"/etc/ssl/certs/ca-certificates.crt" ; Debian, Ubuntu, Gentoo,
|
|
; Arch, Guix, Parabola
|
|
"/etc/pki/tls/certs/ca-bundle.crt" ; Fedora and RHEL
|
|
"/etc/ssl/ca-bundle.pem" ; Suse
|
|
"/usr/ssl/certs/ca-bundle.crt" ; Cygwin
|
|
"/usr/local/share/certs/ca-root-nss.crt" ; FreeBSD
|
|
"/etc/ssl/cert.pem" ; macOS, Dragora, Parabola
|
|
"/etc/certs/ca-certificates.crt" ; OpenIndiana
|
|
)
|
|
"List of CA bundle location filenames or a function returning said list.
|
|
If a file path contains glob wildcards, they will be expanded.
|
|
The files may be in PEM or DER format, as per the GnuTLS documentation.
|
|
The files may not exist, in which case they will be ignored."
|
|
:type '(choice (function :tag "Function to produce list of bundle filenames")
|
|
(repeat (file :tag "Bundle filename"))))
|
|
|
|
(defcustom gnutls-min-prime-bits nil
|
|
"Minimum number of prime bits accepted by GnuTLS for key exchange.
|
|
During a Diffie-Hellman handshake, if the server sends a prime
|
|
number with fewer than this number of bits, the handshake is
|
|
rejected. \(The smaller the prime number, the less secure the
|
|
key exchange is against man-in-the-middle attacks.)
|
|
|
|
A value of nil says to use the default GnuTLS value.
|
|
|
|
The default value of this variable is such that virtually any
|
|
connection can be established, whether this connection can be
|
|
considered cryptographically \"safe\" or not. However, Emacs
|
|
network security is handled at a higher level via
|
|
`open-network-stream' and the Network Security Manager. See Info
|
|
node `(emacs) Network Security'."
|
|
:type '(choice (const :tag "Use default value" nil)
|
|
(integer :tag "Number of bits" 2048))
|
|
:version "27.1")
|
|
|
|
(defcustom gnutls-crlfiles
|
|
'(
|
|
"/etc/grid-security/certificates/*.crl.pem"
|
|
)
|
|
"List of CRL file paths or a function returning said list.
|
|
If a file path contains glob wildcards, they will be expanded.
|
|
The files may be in PEM or DER format, as per the GnuTLS documentation.
|
|
The files may not exist, in which case they will be ignored."
|
|
:type '(choice (function :tag "Function to produce list of CRL filenames")
|
|
(repeat (file :tag "CRL filename")))
|
|
:version "27.1")
|
|
|
|
(defun open-gnutls-stream (name buffer host service &optional parameters)
|
|
"Open a SSL/TLS connection for a service to a host.
|
|
Returns a subprocess-object to represent the connection.
|
|
Input and output work as for subprocesses; `delete-process' closes it.
|
|
Args are NAME BUFFER HOST SERVICE.
|
|
NAME is name for process. It is modified if necessary to make it unique.
|
|
BUFFER is the buffer (or `buffer-name') to associate with the process.
|
|
Process output goes at end of that buffer, unless you specify
|
|
a filter function to handle the output.
|
|
BUFFER may be also nil, meaning that this process is not associated
|
|
with any buffer
|
|
Third arg HOST is the name of the host to connect to, or its IP address.
|
|
Fourth arg SERVICE is the name of the service desired, or an integer
|
|
specifying a port number to connect to.
|
|
Fifth arg PARAMETERS is an optional list of keyword/value pairs.
|
|
Only :client-certificate, :nowait, and :coding keywords are
|
|
recognized, and have the same meaning as for
|
|
`open-network-stream'.
|
|
For historical reasons PARAMETERS can also be a symbol, which is
|
|
interpreted the same as passing a list containing :nowait and the
|
|
value of that symbol.
|
|
|
|
Usage example:
|
|
|
|
(with-temp-buffer
|
|
(open-gnutls-stream \"tls\"
|
|
(current-buffer)
|
|
\"your server goes here\"
|
|
\"imaps\"))
|
|
|
|
This is a very simple wrapper around `gnutls-negotiate'. See its
|
|
documentation for the specific parameters you can use to open a
|
|
GnuTLS connection, including specifying the credential type,
|
|
trust and key files, and priority string."
|
|
(let* ((parameters
|
|
(cond ((symbolp parameters)
|
|
(list :nowait parameters))
|
|
((not (cl-evenp (length parameters)))
|
|
(error "Malformed keyword list"))
|
|
((consp parameters)
|
|
parameters)
|
|
(t
|
|
(error "Unknown parameter type"))))
|
|
(cert (network-stream-certificate host service parameters))
|
|
(keylist (and cert (list cert)))
|
|
(nowait (plist-get parameters :nowait))
|
|
(process (open-network-stream
|
|
name buffer host service
|
|
:nowait nowait
|
|
:tls-parameters
|
|
(and nowait
|
|
(cons 'gnutls-x509pki
|
|
(gnutls-boot-parameters
|
|
:type 'gnutls-x509pki
|
|
:keylist keylist
|
|
:hostname (puny-encode-domain host))))
|
|
:coding (plist-get parameters :coding))))
|
|
(if nowait
|
|
process
|
|
(gnutls-negotiate :process process
|
|
:type 'gnutls-x509pki
|
|
:keylist keylist
|
|
:hostname (puny-encode-domain host)))))
|
|
|
|
(define-error 'gnutls-error "GnuTLS error")
|
|
|
|
(declare-function gnutls-boot "gnutls.c" (proc type proplist))
|
|
(declare-function gnutls-errorp "gnutls.c" (error))
|
|
(defvar gnutls-log-level) ; gnutls.c
|
|
|
|
(cl-defun gnutls-negotiate
|
|
(&rest spec
|
|
&key process type hostname priority-string
|
|
trustfiles crlfiles keylist min-prime-bits
|
|
verify-flags verify-error verify-hostname-error
|
|
&allow-other-keys)
|
|
"Negotiate a SSL/TLS connection. Return proc. Signal gnutls-error.
|
|
|
|
Note that arguments are passed CL style, :type TYPE instead of just TYPE.
|
|
|
|
PROCESS is a process returned by `open-network-stream'.
|
|
For the meaning of the rest of the parameters, see `gnutls-boot-parameters'."
|
|
(let* ((type (or type 'gnutls-x509pki))
|
|
;; The gnutls library doesn't understand files delivered via
|
|
;; the special handlers, so ignore all files found via those.
|
|
(file-name-handler-alist nil)
|
|
(params (gnutls-boot-parameters
|
|
:type type
|
|
:hostname hostname
|
|
:priority-string priority-string
|
|
:trustfiles trustfiles
|
|
:crlfiles crlfiles
|
|
:keylist keylist
|
|
:min-prime-bits min-prime-bits
|
|
:verify-flags verify-flags
|
|
:verify-error verify-error
|
|
:verify-hostname-error verify-hostname-error))
|
|
ret)
|
|
(gnutls-message-maybe
|
|
(setq ret (gnutls-boot process type
|
|
(append (list :complete-negotiation t)
|
|
params)))
|
|
"boot: %s" params)
|
|
|
|
(when (gnutls-errorp ret)
|
|
;; This is an error from the underlying C code.
|
|
(signal 'gnutls-error (list process ret)))
|
|
|
|
process))
|
|
|
|
(cl-defun gnutls-boot-parameters
|
|
(&rest spec
|
|
&key type hostname priority-string
|
|
trustfiles crlfiles keylist min-prime-bits
|
|
verify-flags verify-error verify-hostname-error
|
|
&allow-other-keys)
|
|
"Return a keyword list of parameters suitable for passing to `gnutls-boot'.
|
|
|
|
TYPE is `gnutls-x509pki' (default) or `gnutls-anon'. Use nil for the default.
|
|
HOSTNAME is the remote hostname. It must be a valid string.
|
|
PRIORITY-STRING is as per the GnuTLS docs, default is based on \"NORMAL\".
|
|
TRUSTFILES is a list of CA bundles. It defaults to `gnutls-trustfiles'.
|
|
CRLFILES is a list of CRL files.
|
|
KEYLIST is an alist of (client key file, client cert file) pairs.
|
|
MIN-PRIME-BITS is the minimum acceptable size of Diffie-Hellman keys
|
|
\(see `gnutls-min-prime-bits' for more information). Use nil for the
|
|
default.
|
|
|
|
VERIFY-HOSTNAME-ERROR is a backwards compatibility option for
|
|
putting `:hostname' in VERIFY-ERROR.
|
|
|
|
When VERIFY-ERROR is t or a list containing `:trustfiles', an
|
|
error will be raised when the peer certificate verification fails
|
|
as per GnuTLS' gnutls_certificate_verify_peers2. Otherwise, only
|
|
warnings will be shown about the verification failure.
|
|
|
|
When VERIFY-ERROR is t or a list containing `:hostname', an error
|
|
will be raised when the hostname does not match the presented
|
|
certificate's host name. The exact verification algorithm is a
|
|
basic implementation of the matching described in
|
|
RFC2818 (HTTPS), which takes into account wildcards, and the
|
|
DNSName/IPAddress subject alternative name PKIX extension. See
|
|
GnuTLS' gnutls_x509_crt_check_hostname for details. Otherwise,
|
|
only a warning will be issued.
|
|
|
|
Note that the list in `gnutls-verify-error', matched against the
|
|
HOSTNAME, is the default VERIFY-ERROR.
|
|
|
|
VERIFY-FLAGS is a numeric OR of verification flags only for
|
|
`gnutls-x509pki' connections. See GnuTLS' x509.h for details;
|
|
here's a recent version of the list.
|
|
|
|
GNUTLS_VERIFY_DISABLE_CA_SIGN = 1,
|
|
GNUTLS_VERIFY_ALLOW_X509_V1_CA_CRT = 2,
|
|
GNUTLS_VERIFY_DO_NOT_ALLOW_SAME = 4,
|
|
GNUTLS_VERIFY_ALLOW_ANY_X509_V1_CA_CRT = 8,
|
|
GNUTLS_VERIFY_ALLOW_SIGN_RSA_MD2 = 16,
|
|
GNUTLS_VERIFY_ALLOW_SIGN_RSA_MD5 = 32,
|
|
GNUTLS_VERIFY_DISABLE_TIME_CHECKS = 64,
|
|
GNUTLS_VERIFY_DISABLE_TRUSTED_TIME_CHECKS = 128,
|
|
GNUTLS_VERIFY_DO_NOT_ALLOW_X509_V1_CA_CRT = 256
|
|
|
|
It must be omitted, a number, or nil; if omitted or nil it
|
|
defaults to GNUTLS_VERIFY_ALLOW_X509_V1_CA_CRT."
|
|
(let* ((trustfiles (or trustfiles (gnutls-trustfiles)))
|
|
(crlfiles (or crlfiles (gnutls-crlfiles)))
|
|
(maybe-dumbfw (if (memq 'ClientHello\ Padding (gnutls-available-p))
|
|
":%DUMBFW"
|
|
""))
|
|
(priority-string (or priority-string
|
|
(cond
|
|
((eq type 'gnutls-anon)
|
|
(concat "NORMAL:+ANON-DH:!ARCFOUR-128"
|
|
maybe-dumbfw))
|
|
((eq type 'gnutls-x509pki)
|
|
(if gnutls-algorithm-priority
|
|
(upcase gnutls-algorithm-priority)
|
|
(concat "NORMAL" maybe-dumbfw))))))
|
|
(verify-error (or verify-error
|
|
;; this uses the value of `gnutls-verify-error'
|
|
(cond
|
|
;; if t, pass it on
|
|
((eq gnutls-verify-error t)
|
|
t)
|
|
;; if a list, look for hostname matches
|
|
((listp gnutls-verify-error)
|
|
(cadr (cl-find-if (lambda (x)
|
|
(string-match (car x) hostname))
|
|
gnutls-verify-error)))
|
|
;; else it's nil
|
|
(t nil))))
|
|
(min-prime-bits (or min-prime-bits gnutls-min-prime-bits)))
|
|
|
|
;; Only add :hostname if `verify-error' is not t, since t
|
|
;; means "include :hostname" Bug#38602.
|
|
(and verify-hostname-error
|
|
(not (eq verify-error t))
|
|
(push :hostname verify-error))
|
|
|
|
`(:priority ,priority-string
|
|
:hostname ,hostname
|
|
:loglevel ,gnutls-log-level
|
|
:min-prime-bits ,min-prime-bits
|
|
:trustfiles ,trustfiles
|
|
:crlfiles ,crlfiles
|
|
:keylist ,keylist
|
|
:verify-flags ,verify-flags
|
|
:verify-error ,verify-error
|
|
:callbacks nil)))
|
|
|
|
(defun gnutls--get-files (files)
|
|
(cl-loop for f in files
|
|
if f do (setq f (if (functionp f) (funcall f) f))
|
|
append (cl-delete-if-not #'file-exists-p (file-expand-wildcards f t))))
|
|
|
|
(defun gnutls-trustfiles ()
|
|
"Return a list of usable trustfiles."
|
|
(gnutls--get-files gnutls-trustfiles))
|
|
|
|
(defun gnutls-crlfiles ()
|
|
"Return a list of usable CRL files."
|
|
(gnutls--get-files gnutls-crlfiles))
|
|
|
|
(declare-function gnutls-error-string "gnutls.c" (error))
|
|
|
|
(defun gnutls-message-maybe (doit format &rest params)
|
|
"When DOIT, message with the caller name followed by FORMAT on PARAMS."
|
|
;; (apply 'debug format (or params '(nil)))
|
|
(when (gnutls-errorp doit)
|
|
(message "%s: (err=[%s] %s) %s"
|
|
"gnutls.el"
|
|
doit (gnutls-error-string doit)
|
|
(apply #'format-message format (or params '(nil))))))
|
|
|
|
(provide 'gnutls)
|
|
|
|
;;; gnutls.el ends here
|