Build error --with-debug; ECDHE key exchange TLS problem

nginx version: 0.7.62
OpenSSL version: 1.0.0-beta3
Platform: Linux 2.6.18 x64

  • Short description of problem: *

(a) nginx seems not to handle ephemeral DH key exchanges with EC.
(kx=ECDHE, auth=ECDSA) Connection dies on handshake. (b) A build error
in 0.7.62 seems to indicate that the problem is in nginx, and not an
openssl misconfiguration on my part. =)

  • Long description of problem: *

  • Steps to reproduce TLS problem: *

  1. Compile nginx-0.7.62 with openssl-1.0.0-beta3 (minimal tested
    configure line below, without --with-debug).
  2. Use relevant section of nginx.conf as quoted below. See comment
    below about use of EC, which I think is a red herring.
  3. Try to connect with openssl s_client, latest Firefox, IE on Vista,
    etc.

Expected behavior: Successful TLS connection.
Actual behavior: Handshake failure; connection dropped. E.g.:

openssl s_client -connect 127.0.0.1:443
CONNECTED(00000003)
47491508352976:error:14077410:SSL routines:SSL23_GET_SERVER_HELLO:sslv3
alert handshake failure:s23_clnt.c:656:

no peer certificate available

No client certificate CA names sent

SSL handshake has read 7 bytes and written 186 bytes

New, (NONE), Cipher is (NONE)
Compression: NONE
Expansion: NONE

Note: I have tried with various s_client options, e.g., expressly
selecting -tls1 -no_ssl3, selecting the appropriate ciphers, etc. No
substantial difference.

Note: nginx’s error log reports nothing on the above s_client
connection; so I tried to make a debug build…

  • Steps to reproduce build error: *
  1. Add --with-debug to the same configure line. (Tried untgzing into
    fresh build tree, too.)
  2. Run make.

Expected behavior: Successful debug build.
Actual behavior:

cc1: warnings being treated as errors
src/event/ngx_event_openssl.c: In function ngx_ssl_handshake': src/event/ngx_event_openssl.c:505: warning: assignment discards qualifiers from pointer target type make[1]: *** Error 1 make[1]: Leaving directory/my-build-path/nginx-0.7.62’
make: *** Error 2

  • Comments: *

My ECDHE problem is in the SSL handshake. The build error is in
ngx_ssl_handshake. Coincidence?

I am trying to use EC crypto (ECDHE-ECDSA-AES256-SHA). But
ECDH-ECDSA-AES256-SHA (note lack of “E”) works fine, so I suspect it is
not an EC problem. Have not tried non-EC DHE.

  • Minimal configure line confirmed to produce problem: *

Semi-minimal build configuration:

Besides OpenSSL, only including items used by default modules.

./configure --prefix=/test --with-http_ssl_module
–with-openssl=/path/to/openssl-1.0.0-beta3
–with-pcre=/path/to/pcre-7.9
–with-zlib=/path/to/zlib-1.2.3
–with-debug

(Make completes without --with-debug line.)

##################################

Relevant section of nginx.conf

##################################
ssl_certificate /path/to/the.key;
ssl_certificate_key /path/to/the.crt;
ssl_ciphers ECDHE-ECDSA-AES256-SHA;

Above does not work.

ECDH-ECDSA-AES256-SHA works, but is not DHE, and seems not supported

by recent MSIE.

ssl_prefer_server_ciphers on;
ssl_protocols TLSv1;

Have tried with “ssl_protocols TLSv1 SSLv3” also.

  • Key generation: *

openssl ecparam -name secp384r1 -genkey -out /path/to/the.key -outform
PEM

Have tried the above also with -noout to see if EC parameters were

confusing nginx. No such luck. Did I make some stupid openssl error?

openssl req -key /path/to/the.key -keyform PEM -new -out
/path/to/the.crt
-pubkey -nodes -x509 -days 365 -verify

  • Note of Interest *

lighttpd died with segfault on some similar configurations. At least
nginx stays up; it just doesn’t complete the handshake.

kyleb

Posted at Nginx Forum:
http://forum.nginx.org/read.php?2,11737,11737#msg-11737

Hello!

On Wed, Oct 07, 2009 at 01:25:55AM -0400, kyleb wrote:

nginx version: 0.7.62
OpenSSL version: 1.0.0-beta3
Platform: Linux 2.6.18 x64

  • Short description of problem: *

(a) nginx seems not to handle ephemeral DH key exchanges with EC. (kx=ECDHE, auth=ECDSA) Connection dies on handshake. (b) A build error in 0.7.62 seems to indicate that the problem is in nginx, and not an openssl misconfiguration on my part. =)

Yes, nginx does not support ECDHE. As far as I see this requires
elliptic curve to be specified to use for ephemeral ECDH keys,
which isn’t done by nginx now.

No, build error with debug is unrelated. It’s caused by
openssl’s prototype change for SSL_get_current_cipher() which now
returns (const SSL_CIPHER *) instead of (SSL_CIPHER *) as in
previous versions.

[…]

Note: nginx’s error log reports nothing on the above s_client connection; so I tried to make a debug build…

There should be “[info] … SSL_do_handshake() failed” message.
Note that it’s at info level, you probably have to tune your
error_log level to see it.

Maxim D.

This forum is not affiliated to the Ruby language, Ruby on Rails framework, nor any Ruby applications discussed here.

| Privacy Policy | Terms of Service | Remote Ruby Jobs