unofficial mirror of emacs-devel@gnu.org 
 help / color / mirror / code / Atom feed
blob 03670957a56833ce296c9dc7bca9ba90a1e5e7fa 17903 bytes (raw)
name: lisp/net/nsm.el 	 # note: path name is non-authoritative(*)

  1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
 
;;; nsm.el --- Network Security Manager

;; Copyright (C) 2014-2017 Free Software Foundation, Inc.

;; Author: Lars Magne Ingebrigtsen <larsi@gnus.org>
;; Keywords: encryption, security, network

;; 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 <http://www.gnu.org/licenses/>.

;;; Commentary:

;;; Code:

(require 'cl-lib)
(require 'subr-x)                       ; read-multiple-choice

(defvar nsm-permanent-host-settings nil)
(defvar nsm-temporary-host-settings nil)

(defgroup nsm nil
  "Network Security Manager"
  :version "25.1"
  :group 'comm)

(defcustom network-security-level 'medium
  "How secure the network should be.
If a potential problem with the security of the network
connection is found, the user is asked to give input into how the
connection should be handled.

The following values are possible:

`low': Absolutely no checks are performed.
`medium': This is the default level, should be reasonable for most usage.
`high': This warns about additional things that many people would
not find useful.
`paranoid': On this level, the user is queried for most new connections.

See the Emacs manual for a description of all things that are
checked and warned against."
  :version "25.1"
  :group 'nsm
  :type '(choice (const :tag "Low" low)
		 (const :tag "Medium" medium)
		 (const :tag "High" high)
		 (const :tag "Paranoid" paranoid)))

(defcustom nsm-settings-file (expand-file-name "network-security.data"
						 user-emacs-directory)
  "The file the security manager settings will be stored in."
  :version "25.1"
  :group 'nsm
  :type 'file)

(defcustom nsm-save-host-names nil
  "If non-nil, always save host names in the structures in `nsm-settings-file'.
By default, only hosts that have exceptions have their names
stored in plain text."
  :version "25.1"
  :group 'nsm
  :type 'boolean)

(defvar nsm-noninteractive nil
  "If non-nil, the connection is opened in a non-interactive context.
This means that no queries should be performed.")

(declare-function gnutls-peer-status "gnutls.c" (proc))

(defun nsm-verify-connection (process host port &optional
				      save-fingerprint warn-unencrypted)
  "Verify the security status of PROCESS that's connected to HOST:PORT.
If PROCESS is a gnutls connection, the certificate validity will
be examined.  If it's a non-TLS connection, it may be compared
against previous connections.  If the function determines that
there is something odd about the connection, the user will be
queried about what to do about it.

The process is returned if everything is OK, and otherwise, the
process will be deleted and nil is returned.

If SAVE-FINGERPRINT, always save the fingerprint of the
server (if the connection is a TLS connection).  This is useful
to keep track of the TLS status of STARTTLS servers.

If WARN-UNENCRYPTED, query the user if the connection is
unencrypted."
  (if (eq network-security-level 'low)
      process
    (let* ((status (gnutls-peer-status process))
	   (id (nsm-id host port))
	   (settings (nsm-host-settings id)))
      (cond
       ((not (process-live-p process))
	nil)
       ((not status)
	;; This is a non-TLS connection.
	(nsm-check-plain-connection process host port settings
				    warn-unencrypted))
       (t
	(let ((process
	       (nsm-check-tls-connection process host port status settings)))
	  (when (and process save-fingerprint
		     (null (nsm-host-settings id)))
	    (nsm-save-host host port status 'fingerprint 'always))
	  process))))))

(defun nsm-check-tls-connection (process host port status settings)
  (let ((process (nsm-check-certificate process host port status settings)))
    (if (and process
	     (>= (nsm-level network-security-level) (nsm-level 'medium)))
	;; Do further protocol-level checks if the security is medium.
	(nsm-check-protocol process host port status settings)
      process)))

(declare-function gnutls-peer-status-warning-describe "gnutls.c"
		  (status-symbol))

(defun nsm-check-certificate (process host port status settings)
  (let ((warnings (plist-get status :warnings)))
    (cond

     ;; The certificate validated, but perhaps we want to do
     ;; certificate pinning.
     ((null warnings)
      (cond
       ((< (nsm-level network-security-level) (nsm-level 'high))
	process)
       ;; The certificate is fine, but if we're paranoid, we might
       ;; want to check whether it's changed anyway.
       ((and (>= (nsm-level network-security-level) (nsm-level 'high))
	     (not (nsm-fingerprint-ok-p host port status settings)))
	(delete-process process)
	nil)
       ;; We haven't seen this before, and we're paranoid.
       ((and (eq network-security-level 'paranoid)
	     (null settings)
	     (not (nsm-new-fingerprint-ok-p host port status)))
	(delete-process process)
	nil)
       ((>= (nsm-level network-security-level) (nsm-level 'high))
	;; Save the host fingerprint so that we can check it the
	;; next time we connect.
	(nsm-save-host host port status 'fingerprint 'always)
	process)
       (t
	process)))

     ;; The certificate did not validate.
     ((not (equal network-security-level 'low))
      ;; We always want to pin the certificate of invalid connections
      ;; to track man-in-the-middle or the like.
      (if (not (nsm-fingerprint-ok-p host port status settings))
	  (progn
	    (delete-process process)
	    nil)
	;; We have a warning, so query the user.
	(if (and (not (nsm-warnings-ok-p status settings))
		 (not (nsm-query
		       host port status 'conditions
		       "The TLS connection to %s:%s is insecure for the following reason%s:\n\n%s"
		       host port
		       (if (> (length warnings) 1)
			   "s" "")
		       (mapconcat #'gnutls-peer-status-warning-describe
                                  warnings
                                  "\n"))))
	    (progn
	      (delete-process process)
	      nil)
	  process))))))

(defun nsm-check-protocol (process host port status settings)
  (let ((prime-bits (plist-get status :diffie-hellman-prime-bits))
        (signature-algorithm
         (plist-get (plist-get status :certificate) :signature-algorithm))
        (encryption (format "%s-%s-%s"
			    (plist-get status :key-exchange)
			    (plist-get status :cipher)
			    (plist-get status :mac)))
	(protocol (plist-get status :protocol)))
    (cond
     ((and prime-bits
	   (< prime-bits 1024)
	   (not (memq :diffie-hellman-prime-bits
		      (plist-get settings :conditions)))
	   (not
	    (nsm-query
	     host port status :diffie-hellman-prime-bits
	     "The Diffie-Hellman prime bits (%s) used for this connection to %s:%s is less than what is considered safe (%s). Accept at your own risk."
	     prime-bits host port 1024)))
      (delete-process process)
      nil)
     ((and (string-match "\\bRC4\\b" encryption)
	   (not (memq :rc4 (plist-get settings :conditions)))
	   (not
	    (nsm-query
	     host port status :rc4
	     "The connection to %s:%s uses the RC4 algorithm (%s), which is unsafe. Accept at your own risk."
	     host port encryption)))
      (delete-process process)
      nil)
     ((and (string-match "\\bSHA1\\b" signature-algorithm)
	   (not (memq :signature-sha1 (plist-get settings :conditions)))
	   (not
	    (nsm-query
	     host port status :signature-sha1
	     "The certificate used to verify the connection to %s:%s uses the SHA1 algorithm (%s), which is unsafe. Accept at your own risk."
	     host port signature-algorithm)))
      (delete-process process)
      nil)
     ((let ((what (nsm-check-for-deprecated-protocols protocol settings)))
        (and protocol
             what
	     (not
	      (nsm-query
	       host port status what
	       "The connection to %s:%s uses the %s protocol, which is unsafe. Accept at your own risk."
	       host port protocol))))
      (delete-process process)
      nil)
     (t
      process))))

(defun nsm-check-for-deprecated-protocols (protocol settings)
  (cond
   ((and (string-match "SSL" protocol)
         (not (memq :ssl (plist-get settings :conditions))))
    :ssl)
   ((and (string-equal "TLS1.0" protocol)
         (not (memq :tls1.0 (plist-get settings :conditions))))
    :tls1.0)
   ((and (string-equal "TLS1.1" protocol)
         (not (memq :tls1.1 (plist-get settings :conditions))))
    :tls1.1)
   (t
    nil)))

(defun nsm-fingerprint (status)
  (plist-get (plist-get status :certificate) :public-key-id))

(defun nsm-fingerprint-ok-p (host port status settings)
  (let ((did-query nil))
    (if (and settings
	     (not (eq (plist-get settings :fingerprint) :none))
	     (not (equal (nsm-fingerprint status)
			 (plist-get settings :fingerprint)))
	     (not
	      (setq did-query
		    (nsm-query
		     host port status 'fingerprint
		     "The fingerprint for the connection to %s:%s has changed from %s to %s"
		     host port
		     (plist-get settings :fingerprint)
		     (nsm-fingerprint status)))))
	;; Not OK.
	nil
      (when did-query
	;; Remove any exceptions that have been set on the previous
	;; certificate.
	(plist-put settings :conditions nil))
      t)))

(defun nsm-new-fingerprint-ok-p (host port status)
  (nsm-query
   host port status 'fingerprint
   "The fingerprint for the connection to %s:%s is new: %s"
   host port
   (nsm-fingerprint status)))

(defun nsm-check-plain-connection (process host port settings warn-unencrypted)
  ;; If this connection used to be TLS, but is now plain, then it's
  ;; possible that we're being Man-In-The-Middled by a proxy that's
  ;; stripping out STARTTLS announcements.
  (cond
   ((and (plist-get settings :fingerprint)
	 (not (eq (plist-get settings :fingerprint) :none))
	 (not
	  (nsm-query
	   host port nil 'conditions
	   "The connection to %s:%s used to be an encrypted connection, but is now unencrypted.  This might mean that there's a man-in-the-middle tapping this connection."
	   host port)))
    (delete-process process)
    nil)
   ((and warn-unencrypted
	 (not (memq :unencrypted (plist-get settings :conditions)))
	 (not (nsm-query
	       host port nil 'conditions
	       "The connection to %s:%s is unencrypted."
	       host port)))
    (delete-process process)
    nil)
   (t
    process)))

(defun nsm-query (host port status what message &rest args)
  ;; If there is no user to answer queries, then say `no' to everything.
  (if (or noninteractive
	  nsm-noninteractive)
      nil
    (let ((response
	   (condition-case nil
               (intern
                (car (split-string
                      (nsm-query-user message args
                                      (nsm-format-certificate status))))
                obarray)
	     ;; Make sure we manage to close the process if the user hits
	     ;; `C-g'.
	     (quit 'no)
	     (error 'no))))
      (if (eq response 'no)
          (progn
            (message "Aborting connection to %s:%s" host port)
            nil)
        (message (if (eq response 'session)
                     "Accepting certificate for %s:%s this session only"
                   "Permanently accepting certificate for %s:%s")
                 host port)
	(nsm-save-host host port status what response)
	t))))

(defun nsm-query-user (message args cert)
  (let ((buffer (get-buffer-create "*Network Security Manager*")))
    (save-window-excursion
      ;; First format the certificate and warnings.
      (with-help-window buffer
        (with-current-buffer buffer
          (erase-buffer)
          (when (> (length cert) 0)
            (insert cert "\n"))
          (let ((start (point)))
            (insert (apply #'format-message message args))
            (goto-char start)
            ;; Fill the first line of the message, which usually
            ;; contains lots of explanatory text.
            (fill-region (point) (line-end-position)))))
      ;; Then ask the user what to do about it.
      (unwind-protect
          (cadr
           (read-multiple-choice
            "Continue connecting?"
            '((?a "always" "Accept this certificate this session and for all future sessions.")
              (?s "session only" "Accept this certificate this session only.")
              (?n "no" "Refuse to use this certificate, and close the connection."))))
        (kill-buffer buffer)))))

(defun nsm-save-host (host port status what permanency)
  (let* ((id (nsm-id host port))
	 (saved
	  (list :id id
		:fingerprint (or (nsm-fingerprint status)
				 ;; Plain connection.
				 :none))))
    (when (or (eq what 'conditions)
	      nsm-save-host-names)
      (nconc saved (list :host (format "%s:%s" host port))))
    ;; We either want to save/update the fingerprint or the conditions
    ;; of the certificate/unencrypted connection.
    (cond
     ((eq what 'conditions)
      (cond
       ((not status)
	(nconc saved '(:conditions (:unencrypted))))
       ((plist-get status :warnings)
	(nconc saved
	       (list :conditions (plist-get status :warnings))))))
     ((not (eq what 'fingerprint))
      ;; Store additional protocol settings.
      (let ((settings (nsm-host-settings id)))
	(when settings
	  (setq saved settings))
	(if (plist-get saved :conditions)
	    (nconc (plist-get saved :conditions) (list what))
	  (nconc saved (list :conditions (list what)))))))
    (if (eq permanency 'always)
	(progn
	  (nsm-remove-temporary-setting id)
	  (nsm-remove-permanent-setting id)
	  (push saved nsm-permanent-host-settings)
	  (nsm-write-settings))
      (nsm-remove-temporary-setting id)
      (push saved nsm-temporary-host-settings))))

(defun nsm-write-settings ()
  (with-temp-file nsm-settings-file
    (insert "(\n")
    (dolist (setting nsm-permanent-host-settings)
      (insert " ")
      (prin1 setting (current-buffer))
      (insert "\n"))
    (insert ")\n")))

(defun nsm-read-settings ()
  (setq nsm-permanent-host-settings
	(with-temp-buffer
	  (insert-file-contents nsm-settings-file)
	  (goto-char (point-min))
	  (ignore-errors (read (current-buffer))))))

(defun nsm-id (host port)
  (concat "sha1:" (sha1 (format "%s:%s" host port))))

(defun nsm-host-settings (id)
  (when (and (not nsm-permanent-host-settings)
	     (file-exists-p nsm-settings-file))
    (nsm-read-settings))
  (let ((result nil))
    (dolist (elem (append nsm-temporary-host-settings
			  nsm-permanent-host-settings))
      (when (and (not result)
		 (equal (plist-get elem :id) id))
	(setq result elem)))
    result))

(defun nsm-warnings-ok-p (status settings)
  (let ((ok t)
	(conditions (plist-get settings :conditions)))
    (dolist (warning (plist-get status :warnings))
      (unless (memq warning conditions)
	(setq ok nil)))
    ok))

(defun nsm-remove-permanent-setting (id)
  (setq nsm-permanent-host-settings
	(cl-delete-if
	 (lambda (elem)
	   (equal (plist-get elem :id) id))
	 nsm-permanent-host-settings)))

(defun nsm-remove-temporary-setting (id)
  (setq nsm-temporary-host-settings
	(cl-delete-if
	 (lambda (elem)
	   (equal (plist-get elem :id) id))
	 nsm-temporary-host-settings)))

(defun nsm-format-certificate (status)
  (let ((cert (plist-get status :certificate)))
    (when cert
      (with-temp-buffer
	(insert
	 "Certificate information\n"
	 "Issued by:"
	 (nsm-certificate-part (plist-get cert :issuer) "CN" t) "\n"
	 "Issued to:"
	 (or (nsm-certificate-part (plist-get cert :subject) "O")
	     (nsm-certificate-part (plist-get cert :subject) "OU" t))
	 "\n"
	 "Hostname:"
	 (nsm-certificate-part (plist-get cert :subject) "CN" t) "\n")
	(when (and (plist-get cert :public-key-algorithm)
		   (plist-get cert :signature-algorithm))
	  (insert
	   "Public key:" (plist-get cert :public-key-algorithm)
	   ", signature: " (plist-get cert :signature-algorithm) "\n"))
	(when (and (plist-get status :key-exchange)
		   (plist-get status :cipher)
		   (plist-get status :mac)
		   (plist-get status :protocol))
	  (insert
	   "Protocol:" (plist-get status :protocol)
	   ", key: " (plist-get status :key-exchange)
	   ", cipher: " (plist-get status :cipher)
	   ", mac: " (plist-get status :mac) "\n"))
	(when (plist-get cert :certificate-security-level)
	  (insert
	   "Security level:"
	   (propertize (plist-get cert :certificate-security-level)
		       'face 'bold)
	   "\n"))
	(insert
	 "Valid:From " (plist-get cert :valid-from)
	 " to " (plist-get cert :valid-to) "\n\n")
	(goto-char (point-min))
	(while (re-search-forward "^[^:]+:" nil t)
	  (insert (make-string (- 20 (current-column)) ? )))
	(buffer-string)))))

(defun nsm-certificate-part (string part &optional full)
  (let ((part (cadr (assoc part (nsm-parse-subject string)))))
    (cond
     (part part)
     (full string)
     (t nil))))

(defun nsm-parse-subject (string)
  (with-temp-buffer
    (insert string)
    (goto-char (point-min))
    (let ((start (point))
	  (result nil))
      (while (not (eobp))
	(push (replace-regexp-in-string
	       "[\\]\\(.\\)" "\\1"
	       (buffer-substring start
				 (if (re-search-forward "[^\\]," nil 'move)
				     (1- (point))
				   (point))))
	      result)
	(setq start (point)))
      (mapcar
       (lambda (elem)
	 (let ((pos (cl-position ?= elem)))
	   (if pos
	       (list (substring elem 0 pos)
		     (substring elem (1+ pos)))
	     elem)))
       (nreverse result)))))

(defun nsm-level (symbol)
  "Return a numerical level for SYMBOL for easier comparison."
  (cond
   ((eq symbol 'low) 0)
   ((eq symbol 'medium) 1)
   ((eq symbol 'high) 2)
   (t 3)))

(provide 'nsm)

;;; nsm.el ends here

debug log:

solving 03670957a5 ...
found 03670957a5 in https://yhetil.org/emacs-devel/87shi0tqh3.fsf@gmail.com/
found 8d3463ef0a in https://git.savannah.gnu.org/cgit/emacs.git
preparing index
index prepared:
100644 8d3463ef0a56255b0e60765ee76d84db899414e7	lisp/net/nsm.el

applying [1/1] https://yhetil.org/emacs-devel/87shi0tqh3.fsf@gmail.com/
diff --git a/lisp/net/nsm.el b/lisp/net/nsm.el
index 8d3463ef0a..03670957a5 100644

Checking patch lisp/net/nsm.el...
Applied patch lisp/net/nsm.el cleanly.

index at:
100644 03670957a56833ce296c9dc7bca9ba90a1e5e7fa	lisp/net/nsm.el

(*) Git path names are given by the tree(s) the blob belongs to.
    Blobs themselves have no identifier aside from the hash of its contents.^

Code repositories for project(s) associated with this public inbox

	https://git.savannah.gnu.org/cgit/emacs.git

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).