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bug#40397: 28.0.50; epg decrypt does not verify signed content in smime
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From: |
Sebastian Fieber |
|
Subject: |
bug#40397: 28.0.50; epg decrypt does not verify signed content in smime encrypted and signed message |
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Date: |
Thu, 23 Dec 2021 19:14:34 +0100 |
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User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/28.0.50 (gnu/linux) |
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On Mi, Dez 22 2021, Lars Ingebrigtsen <larsi@gnus.org> wrote:
> Still seems relevant to me, but the patch no longer applies due to other
> changes in Gnus. Can you re-spin the patch for Emacs 29, and then I'll
> get it committed.
This one should apply :)
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From=203f85a1a72953f0877d2edcf56e872e7fe760b9f9 Mon Sep 17 00:00:00 2001
From: Sebastian Fieber <sebastian.fieber@web.de>
Date: Mon, 6 Apr 2020 20:45:05 +0200
Subject: [PATCH] fix bug #40397
This fixes S/MIME encrypted AND signed mails where in the encrypted
pkcs7 envelope is a signed pkcs7 structure.
Also this patch enables proper security-buttons for pkcs7-mime
encrypted and/or signed mails.
Changes:
=2D don't force Content-type header to text/plain in front of decrypted
content for smime decryption using mm-view-pkcs7. This fixes the
initial bug where the signed part was not verified due to the wrong
content type header.
=2D structure the result of mm-dissect-buffer of application/pkcs7-mime
like a multipart mail so there is no loosing of information of
verification and decryption results which can now be displayed by
gnus-mime-display-security
=2D adjust gnus-mime-display-part to handle application/pkcs7-mime like
multipart/encrypted or multipart/signed
=2D add dummy entries to mm-verify-function-alist and
mm-decrypt-function-alist so gnus-mime-display-security correctly
displays "S/MIME" and not "unknown protocol"
=2D don't just check for multipart/signed in
gnus-insert-mime-security-button but also for the pkcs7-mime mimetypes
to print "Encrypted" or "Signed" accordingly in the security button
=2D adjust mm-possibly-verify-or-decrypt to check for smime-type to ask
wether to verify or decrypt the part and not to always ask to decrypt
=2D adjust mm-view-pkcs7-decrypt and verify to call mm-sec-status so
success information can be displayed by gnus-mime-display-security
=2D in mm-view-pkcs7-verify also remove carriage returns like in
mm-view-pkcs7-decrypt
=2D adjust gnus-mime-security-verify-or-decrypt to handle pkcs7-mime
right with the done changes
TODO: mm-view-pkcs7-decrypt and verify error handling and
reporting. ATM there is only the good case implemented - at least for
reporting with gnus-mime-display-security.
=2D--
lisp/gnus/gnus-art.el | 60 ++++++++++++++++++++++++++++---
lisp/gnus/mm-decode.el | 81 +++++++++++++++++++++++++++++++-----------
lisp/gnus/mm-view.el | 25 +++++++++++--
3 files changed, 138 insertions(+), 28 deletions(-)
diff --git a/lisp/gnus/gnus-art.el b/lisp/gnus/gnus-art.el
index 6b9610d312..b130650df6 100644
=2D-- a/lisp/gnus/gnus-art.el
+++ b/lisp/gnus/gnus-art.el
@@ -5986,6 +5986,34 @@ gnus-mime-display-part
((equal (car handle) "multipart/encrypted")
(gnus-add-wash-type 'encrypted)
(gnus-mime-display-security handle))
+ ;; pkcs7-mime handling:
+ ;;
+ ;; although not really multipart these are structured internally by
+ ;; mm-dissect-buffer like multipart to not discard the decryption
+ ;; and verification results
+ ;;
+ ;; application/pkcs7-mime
+ ((and (equal (car handle) "application/pkcs7-mime")
+ (equal (mm-handle-multipart-ctl-parameter handle 'protocol)
+ "application/pkcs7-mime_signed-data"))
+ (gnus-add-wash-type 'signed)
+ (gnus-mime-display-security handle))
+ ((and (equal (car handle) "application/pkcs7-mime")
+ (equal (mm-handle-multipart-ctl-parameter handle 'protocol)
+ "application/pkcs7-mime_enveloped-data"))
+ (gnus-add-wash-type 'encrypted)
+ (gnus-mime-display-security handle))
+ ;; application/x-pkcs7-mime
+ ((and (equal (car handle) "application/x-pkcs7-mime")
+ (equal (mm-handle-multipart-ctl-parameter handle 'protocol)
+ "application/x-pkcs7-mime_signed-data"))
+ (gnus-add-wash-type 'signed)
+ (gnus-mime-display-security handle))
+ ((and (equal (car handle) "application/x-pkcs7-mime")
+ (equal (mm-handle-multipart-ctl-parameter handle 'protocol)
+ "application/x-pkcs7-mime_enveloped-data"))
+ (gnus-add-wash-type 'encrypted)
+ (gnus-mime-display-security handle))
;; Other multiparts are handled like multipart/mixed.
(t
(gnus-mime-display-mixed (cdr handle)))))
@@ -8733,9 +8761,16 @@ gnus-mime-security-verify-or-decrypt
(with-current-buffer (mm-handle-multipart-original-buffer handle)
(let* ((mm-verify-option 'known)
(mm-decrypt-option 'known)
=2D (nparts (mm-possibly-verify-or-decrypt (cdr handle) handle)))
+ (pkcs7-mime-p (or (equal (car handle) "application/pkcs7-mime=
")
+ (equal (car handle) "application/x-pkcs7-mi=
me")))
+ (nparts (if pkcs7-mime-p
+ (list (mm-possibly-verify-or-decrypt (cadr handle=
) (cadadr handle)))
+ (mm-possibly-verify-or-decrypt (cdr handle) handle)=
)))
(unless (eq nparts (cdr handle))
=2D (mm-destroy-parts (cdr handle))
+ ;; if pkcs7-mime don't destroy the parts as the buffer in
+ ;; the cdr still needs to be accessible
+ (when (not pkcs7-mime-p)
+ (mm-destroy-parts (cdr handle)))
(setcdr handle nparts))))
(gnus-mime-display-security handle)
(when region
@@ -8793,8 +8828,25 @@ gnus-insert-mime-security-button
(or (nth 2 (assoc protocol mm-verify-function-alist))
(nth 2 (assoc protocol mm-decrypt-function-alist))
"Unknown")
=2D (if (equal (car handle) "multipart/signed")
=2D " Signed" " Encrypted")
+ (cond ((equal (car handle) "multipart/signed") " Signed")
+ ((equal (car handle) "multipart/encrypted") " Encrypted")
+ ((and (equal (car handle) "application/pkcs7-mime")
+ (equal (mm-handle-multipart-ctl-parameter handle 'p=
rotocol)
+ "application/pkcs7-mime_signed-data"))
+ " Signed")
+ ((and (equal (car handle) "application/pkcs7-mime")
+ (equal (mm-handle-multipart-ctl-parameter handle 'p=
rotocol)
+ "application/pkcs7-mime_enveloped-data"))
+ " Encrypted")
+ ;; application/x-pkcs7-mime
+ ((and (equal (car handle) "application/x-pkcs7-mime")
+ (equal (mm-handle-multipart-ctl-parameter handle 'p=
rotocol)
+ "application/x-pkcs7-mime_signed-data"))
+ " Signed")
+ ((and (equal (car handle) "application/x-pkcs7-mime")
+ (equal (mm-handle-multipart-ctl-parameter handle 'p=
rotocol)
+ "application/x-pkcs7-mime_enveloped-data"))
+ " Encrypted"))
" Part"))
(gnus-tmp-info
(or (mm-handle-multipart-ctl-parameter handle 'gnus-info)
diff --git a/lisp/gnus/mm-decode.el b/lisp/gnus/mm-decode.el
index 96695aabfd..da1a7c36a5 100644
=2D-- a/lisp/gnus/mm-decode.el
+++ b/lisp/gnus/mm-decode.el
@@ -473,6 +473,7 @@ mm-dissect-default-type
(autoload 'mml2015-verify-test "mml2015")
(autoload 'mml-smime-verify "mml-smime")
(autoload 'mml-smime-verify-test "mml-smime")
+(autoload 'mm-view-pkcs7-verify "mm-view")
(defvar mm-verify-function-alist
'(("application/pgp-signature" mml2015-verify "PGP" mml2015-verify-test)
@@ -481,7 +482,15 @@ mm-verify-function-alist
("application/pkcs7-signature" mml-smime-verify "S/MIME"
mml-smime-verify-test)
("application/x-pkcs7-signature" mml-smime-verify "S/MIME"
=2D mml-smime-verify-test)))
+ mml-smime-verify-test)
+ ("application/x-pkcs7-signature" mml-smime-verify "S/MIME"
+ mml-smime-verify-test)
+ ;; these are only used for security-buttons and contain the
+ ;; smime-type after the underscore
+ ("application/pkcs7-mime_signed-data" mm-view-pkcs7-verify "S/MIME"
+ nil)
+ ("application/x-pkcs7-mime_signed-data" mml-view-pkcs7-verify "S/MIME"
+ nil)))
(defcustom mm-verify-option 'never
"Option of verifying signed parts.
@@ -500,11 +509,16 @@ mm-verify-option
(autoload 'mml2015-decrypt "mml2015")
(autoload 'mml2015-decrypt-test "mml2015")
+(autoload 'mm-view-pkcs7-decrypt "mm-view")
(defvar mm-decrypt-function-alist
'(("application/pgp-encrypted" mml2015-decrypt "PGP" mml2015-decrypt-tes=
t)
("application/x-gnus-pgp-encrypted" mm-uu-pgp-encrypted-extract-1 "PGP"
=2D mm-uu-pgp-encrypted-test)))
+ mm-uu-pgp-encrypted-test)
+ ;; these are only used for security-buttons and contain the
+ ;; smime-type after the underscore
+ ("application/pkcs7-mime_enveloped-data" mm-view-pkcs7-decrypt "S/MIME=
" nil)
+ ("application/x-pkcs7-mime_enveloped-data" mm-view-pkcs7-decrypt "S/MI=
ME" nil)))
(defcustom mm-decrypt-option nil
"Option of decrypting encrypted parts.
@@ -682,14 +696,29 @@ mm-dissect-buffer
(car ctl))
(cons (car ctl) (mm-dissect-multipart ctl from))))
(t
=2D (mm-possibly-verify-or-decrypt
=2D (mm-dissect-singlepart
=2D ctl
=2D (and cte (intern (downcase (mail-header-strip-cte cte))))
=2D no-strict-mime
=2D (and cd (mail-header-parse-content-disposition cd))
=2D description id)
=2D ctl from))))
+ (let* ((handle
+ (mm-dissect-singlepart
+ ctl
+ (and cte (intern (downcase (mail-header-strip-cte cte))=
))
+ no-strict-mime
+ (and cd (mail-header-parse-content-disposition cd))
+ description id))
+ (intermediate-result (mm-possibly-verify-or-decrypt hand=
le ctl from)))
+ (when (and (equal type "application")
+ (or (equal subtype "pkcs7-mime")
+ (equal subtype "x-pkcs7-mime")))
+ (add-text-properties 0
+ (length (car ctl))
+ (list 'protocol
+ (concat (substring-no-properties=
(car ctl))
+ "_"
+ (cdr (assoc 'smime-type =
ctl))))
+ (car ctl))
+ ;; if this is a pkcs7-mime lets treat this special and
+ ;; more like multipart so the pkcs7-mime part does not
+ ;; get ignored
+ (setq intermediate-result (cons (car ctl) (list intermediat=
e-result))))
+ intermediate-result))))
(when id
(when (string-match " *<\\(.*\\)> *" id)
(setq id (match-string 1 id)))
@@ -1672,17 +1701,27 @@ mm-possibly-verify-or-decrypt
(cond
((or (equal type "application/x-pkcs7-mime")
(equal type "application/pkcs7-mime"))
=2D (with-temp-buffer
=2D (when (and (cond
=2D ((eq mm-decrypt-option 'never) nil)
=2D ((eq mm-decrypt-option 'always) t)
=2D ((eq mm-decrypt-option 'known) t)
=2D (t (y-or-n-p
=2D (format "Decrypt (S/MIME) part? "))))
=2D (mm-view-pkcs7 parts from))
=2D (goto-char (point-min))
=2D (insert "Content-type: text/plain\n\n")
=2D (setq parts (mm-dissect-buffer t)))))
+ (add-text-properties 0 (length (car ctl))
+ (list 'buffer (car parts))
+ (car ctl))
+ (let* ((smime-type (cdr (assoc 'smime-type ctl)))
+ (envelope-p (string=3D smime-type "enveloped-data"))
+ (decrypt-or-sign-option (if envelope-p
+ mm-decrypt-option
+ mm-verify-option))
+ (question (if envelope-p
+ "Decrypt (S/MIME) part? "
+ "Verify signed (S/MIME) part? ")))
+ (with-temp-buffer
+ (when (and (cond
+ ((eq decrypt-or-sign-option 'never) nil)
+ ((eq decrypt-or-sign-option 'always) t)
+ ((eq decrypt-or-sign-option 'known) t)
+ (t (y-or-n-p
+ (format question)))))
+ (mm-view-pkcs7 parts from)
+ (goto-char (point-min))
+ (setq parts (mm-dissect-buffer t))))))
((equal subtype "signed")
(unless (and (setq protocol
(mm-handle-multipart-ctl-parameter ctl 'protocol))
diff --git a/lisp/gnus/mm-view.el b/lisp/gnus/mm-view.el
index 828ac633dc..34da9464ce 100644
=2D-- a/lisp/gnus/mm-view.el
+++ b/lisp/gnus/mm-view.el
@@ -591,8 +591,15 @@ mm-view-pkcs7-verify
(with-temp-buffer
(insert-buffer-substring (mm-handle-buffer handle))
(goto-char (point-min))
=2D (let ((part (base64-decode-string (buffer-string))))
=2D (epg-verify-string (epg-make-context 'CMS) part))))
+ (let* ((part (base64-decode-string (buffer-string)))
+ (context (epg-make-context 'CMS))
+ (plain (epg-verify-string context part)))
+ (mm-sec-status
+ 'gnus-info
+ (epg-verify-result-to-string (epg-context-result-for context=
'verify))
+ 'gnus-details
+ nil)
+ plain)))
(with-temp-buffer
(insert "MIME-Version: 1.0\n")
(mm-insert-headers "application/pkcs7-mime" "base64" "smime.p7m")
@@ -601,6 +608,10 @@ mm-view-pkcs7-verify
(if verified
(insert verified)
(insert-buffer-substring smime-details-buffer)))
+ (goto-char (point-min))
+ (while (search-forward "\r\n" nil t)
+ (replace-match "\n"))
+ (goto-char (point-min))
t))
(autoload 'epg-decrypt-string "epg")
@@ -612,7 +623,15 @@ mm-view-pkcs7-decrypt
;; Use EPG/gpgsm
(let ((part (base64-decode-string (buffer-string))))
(erase-buffer)
=2D (insert (epg-decrypt-string (epg-make-context 'CMS) part)))
+ (insert
+ (let* ((context (epg-make-context 'CMS))
+ (plain (epg-decrypt-string context part)))
+ (mm-sec-status
+ 'gnus-info
+ "OK"
+ 'gnus-details
+ nil)
+ plain)))
;; Use openssl
(insert "MIME-Version: 1.0\n")
(mm-insert-headers "application/pkcs7-mime" "base64" "smime.p7m")
=2D-
2.25.2
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