Package: emacs;
Reported by: flitterio <at> gmail.com (Francis Litterio)
Date: Sun, 12 Jun 2016 21:35:02 UTC
Severity: normal
Tags: security, wontfix
Found in version 25.1.50
Done: Lars Ingebrigtsen <larsi <at> gnus.org>
Bug is archived. No further changes may be made.
View this message in rfc822 format
From: flitterio <at> gmail.com (Francis Litterio) To: 23759 <at> debbugs.gnu.org Subject: bug#23759: 25.1.50; open-tls-stream creates malformed gnutls-cli command if trusted cert files don't exist Date: Sun, 12 Jun 2016 17:32:56 -0400
Using Emacs built from the latest mainline source on Windows 7 (with all updates applied),
I see this problem:
1. Launch Emacs using: emacs.exe -Q
2. Evaluate this form in buffer *scratch*:
(progn
(require 'tls)
(open-tls-stream "foo" nil "irc.oftc.net" 6697))
After the connection is established, buffer *Messages* shows two failed connection
attempts using gnutls-cli, followed by a successful connection using openssl:
Opening TLS connection to ‘irc.oftc.net’...
Opening TLS connection with ‘gnutls-cli --x509cafile nil -p 6697 irc.oftc.net’...failed
Opening TLS connection with ‘gnutls-cli --x509cafile nil -p 6697 irc.oftc.net --protocols ssl3’...failed
Opening TLS connection with ‘openssl s_client -connect irc.oftc.net:6697 -no_ssl2 -ign_eof’...done
Opening TLS connection to ‘irc.oftc.net’...done
Notice switch "--x509cafile nil" passed to gnutls-cli, which cause it to fail both times.
The root cause has to do with variable tls-program, which has this value:
("gnutls-cli --x509cafile %t -p %p %h"
"gnutls-cli --x509cafile %t -p %p %h --protocols ssl3"
"openssl s_client -connect %h:%p -no_ssl2 -ign_eof")
The docstring for tls-program says that %t is replaced "with a file name containing
trusted certificates". The names of trusted certificate files come from variable
gnutls-trustfiles, which has this value:
("/etc/ssl/certs/ca-certificates.crt"
"/etc/pki/tls/certs/ca-bundle.crt"
"/etc/ssl/ca-bundle.pem"
"/usr/ssl/certs/ca-bundle.crt"
"/usr/local/share/certs/ca-root-nss.crt")
The docstring for gnutlsw-trustfiles says:
The files may not exist, in which case they will be ignored.
These files do not exist on my Windows system, but the %t in the strings listed in
variable tls-program is replaced by "nil", which creates a malformed gnutls-cli command.
I can work around the problem by setting variable tls-program to this list, which is the
above list without the "--x509cafile %t" in the gnutls-cli commands:
("gnutls-cli -p %p %h"
"gnutls-cli -p %p %h --protocols ssl3"
"openssl s_client -connect %h:%p -no_ssl2 -ign_eof")
If the no trusted cert file is available, the gnutls-cli command needs to be constructed
more intelligently, so as not to create a malformed command. This problem seems to be
localized in this code in function open-tls-stream in lisp/net/tls.el:
(with-current-buffer buffer
(message "Opening TLS connection to `%s'..." host)
(while (and (not done) (setq cmd (pop cmds)))
(let ((process-connection-type tls-process-connection-type)
(formatted-cmd
(format-spec
cmd
(format-spec-make
?t (car (gnutls-trustfiles))
?h host
?p (if (integerp port)
(int-to-string port)
port)))))
(message "Opening TLS connection with `%s'..." formatted-cmd)
(setq process (start-process
name buffer shell-file-name shell-command-switch
formatted-cmd))
--
Fran Litterio
In GNU Emacs 25.1.50.1 (i686-pc-mingw32)
of 2016-05-28 built on PUPPY
Repository revision: 549470fdf234acb4da7941e3bb9b28ed63a51876
Windowing system distributor 'Microsoft Corp.', version 6.1.7601
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Wrote c:/franl/zzz-emacs-bug-open-tls-stream.el
Saving file c:/franl/zzz-emacs-bug-open-tls-stream.el...
Wrote c:/franl/zzz-emacs-bug-open-tls-stream.el
Saving file c:/franl/zzz-emacs-bug-open-tls-stream.el...
Wrote c:/franl/zzz-emacs-bug-open-tls-stream.el
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