[Pound Mailing List] Re: X-SSL-cipher header reports TLS connections as SSLv3

Patch attached. Patch applied against Pound-2.6.tgz

-- 
Tom Fitzhenry

On Mon, Dec 1, 2014, at 02:23 PM, Tom Fitzhenry wrote:
> # Steps to reproduce
> 1. Copy the attached `pound.cfg` to `/etc/pound/`
> 2. Copy the attached `pound-test-cert.pem` to `/etc/ssl/private/`
> 3. Open a TCP port on port 8080: `netcat -t -l -p 8080`
> 4. `service pound start`
> 5. Make a TLS (not SSL!) request: `curl --tlsv1 --ciphers 'AES128-SHA'
> -k https://127.0.0.1:8443/`
> 6. Look at the stdout of netcat, and see the value of HTTP request
> header X-SSL-cipher that pound has injected into the request
> 
> ## Expected
> The connection is reported to be TLS
> 
> ## Actual
> The connection is reported to be SSLv3: "AES128-SHA SSLv3 Kx=RSA Au=RSA
> Enc=AES(128) Mac=SHA1"
> 
> Wireshark debugging confirms that the curl connection is indeed a TLS
> connection, rather than a SSLv3 connection.
> 
> # Impact
> When trying to determine the impact of disabling SSLv3 (re POODLE), we
> searched
> our logs for how many clients used SSLv3, and this bug caused us to
> believe we
> had more SSLv3 traffic than we actually did.
> 
> # Why this is reported to be SSLv3
> Looking into the pound code[0], X-SSL-cipher is populated with the
> result of SSL_CIPHER_description().
> In SSL_CIPHER_description() "The TLSv1.0 ciphers are flagged with
> SSLv3."[1].
> The AES ciphers are TLSv1 ciphers, and hence are reported as SSLv3 by
> pound/openssl.
> 
> # Proposed fix
> Add a X-SSL-version header, using SSL_get_version()[2]. I can produce a
> patch for this, if it is considered an acceptable change.
> 
> I originally raised this against Ubuntu's bug tracker[3], but have since
> found this mailing list, so am posting it here.
> 
> 0.
> https://github.com/mandiant/pound/blob/a3705bc06e44ec4a229fd38760d6c04c43ced6b6/http.c#L943
> 1. https://www.openssl.org/docs/ssl/SSL_CIPHER_get_name.html
> 2. https://www.openssl.org/docs/ssl/SSL_get_version.html
> 3. https://bugs.launchpad.net/ubuntu/+source/pound/+bug/1398007
> 
> -- 
> Tom Fitzhenry
> Email had 2 attachments:
> + pound.cfg
>   1k (application/octet-stream)
> + pound-test-cert.pem
>   2k (application/x-x509-ca-cert)

From d8caa2629ad0c9adeb16c45fd6cc5d11da3bbad2 Mon Sep 17 00:00:00 2001
From: Tom Fitzhenry <[email protected]>
Date: Mon, 1 Dec 2014 22:32:43 +0000
Subject: [PATCH] Add X-SSL-version header

Uses https://www.openssl.org/docs/ssl/SSL_get_version.html , so the
value of X-SSL-version is one of
{SSLv2,SSLv3,TLSv1,TLSv1.1,TLSv1.2,unknown}
---
 http.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/http.c b/http.c
index bb2ce8b..caa89e3 100755
--- a/http.c
+++ b/http.c
@@ -953,6 +953,7 @@ do_http(thr_arg *arg)
         /* if SSL put additional headers for client certificate */
         if(cur_backend->be_type == 0 && ssl != NULL) {
             SSL_CIPHER  *cipher;
+            const char *protocolVersion;
 
             if((cipher = SSL_get_current_cipher(ssl)) != NULL) {
                 SSL_CIPHER_description(cipher, buf, MAXBUF - 1);
@@ -968,6 +969,18 @@ do_http(thr_arg *arg)
                 }
             }
 
+            if((protocolVersion = SSL_get_version(ssl)) != NULL) {
+                if(BIO_printf(be, "X-SSL-version: %s\r\n", protocolVersion) <= 0) {
+                    str_be(buf, MAXBUF - 1, cur_backend);
+                    end_req = cur_time();
+                    logmsg(LOG_WARNING, "(%lx) e500 error write X-SSL-version to %s: %s (%.3f sec)",
+                        pthread_self(), buf, strerror(errno), (end_req - start_req) / 1000000.0);
+                    err_reply(cl, h500, lstn->err500);
+                    clean_all();
+                    return;
+                }
+            }
+
             if(lstn->clnt_check > 0 && x509 != NULL && (bb = BIO_new(BIO_s_mem())) != NULL) {
                 X509_NAME_print_ex(bb, X509_get_subject_name(x509), 8, XN_FLAG_ONELINE & ~ASN1_STRFLGS_ESC_MSB);
                 get_line(bb, buf, MAXBUF);
-- 
2.2.0