Problem with proxy_set_header $ssl_client_cert

Server NGINX
1

Hello,

I am having an issue while verifying client SSL certificates. Everything
works fine until I attempt to forward the cert onto the upstream.

Once I add a line similar to the following in my location block, all
requests become an error 400 Bad Request.

proxy_set_header X-SSL-Client_Cert $ssl_client_cert;
(I’ve also tried $ssl_client_raw_cert, but the docs say
“[$ssl_client_cert]
is intended for the use in the proxy_set_header directive;”

Here is my entire location block:
location @unicorn {
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header X-SSL-Client-Cert $ssl_client_cert;
proxy_set_header X-Forwarded-Proto $scheme;
proxy_set_header Host $http_host;
proxy_redirect off;
proxy_pass http://unicorn;
}

Originally I was using add_header X-SSL-Client-Cert in the server block,
which did not throw a 400, but my upstream app was not seeing the
header.

Once I remove the proxy_set_header line, the server works as expected:
requests with a valid cert get passed through while unauthenticated
requests
get a 403. (This is done by checking $ssl_client_verify).

Am I missing something obvious? Any help would be very appreciated.
Thank
you.

Posted at Nginx Forum:

2

Hello!

On Sun, Feb 24, 2013 at 09:41:38AM -0500, jstrybis wrote:

Originally I was using add_header X-SSL-Client-Cert in the server block,
which did not throw a 400, but my upstream app was not seeing the header.

Once I remove the proxy_set_header line, the server works as expected:
requests with a valid cert get passed through while unauthenticated requests
get a 403. (This is done by checking $ssl_client_verify).

Am I missing something obvious? Any help would be very appreciated. Thank
you.

The $ssl_client_cert variable abuses header continuation, and this
doesn’t work with many http servers (including nginx itself).
There should be more portable way to pass client certificate to an
upstream server.

–
Maxim D.

3

The $ssl_client_cert variable abuses header continuation, and this
doesn’t work with many http servers (including nginx itself).

Noticed that with spray-can.

There should be more portable way to pass client certificate to an
upstream server.

Is there already, or is there one in plans? Any known workarounds?
Encoding
and decoding the $ssl_client_cert somehow? (I’m really new to nginx.)

–
Lynoure Braakman

Posted at Nginx Forum:

4

On 25 Feb2013, at 18:37 , Lynoure [email protected] wrote:

The $ssl_client_cert variable abuses header continuation, and this
doesn’t work with many http servers (including nginx itself).

Noticed that with spray-can.

There should be more portable way to pass client certificate to an
upstream server.

Is there already, or is there one in plans? Any known workarounds? Encoding
and decoding the $ssl_client_cert somehow? (I’m really new to nginx.)

You could hack ngx_ssl_get_certificate() function to get certificate in
one line,
or there is an ugly, but possible way to remove limited number of
newline
characters from variable with map directive:

map $ssl_client_raw_cert $a {
“~^(-.-\n)(?<1st>[^\n]+)\n((?[^\n]+)\n)?((?[^\n]+)\n)?((?[^\n]+)\n)?((?[^\n]+)\n)?((?[^\n]+)\n)?((?[^\n]+)\n)?((?[^\n]+)\n)?((?[^\n]+)\n)?((?[^\n]+)\n)?((?[^\n]+)\n)?((?[^\n]+)\n)?((?[^\n]+)\n)?((?[^\n]+)\n)?((?[^\n]+)\n)?((?

[^\n]+)\n)?((?[^\n]+)\n)?((?[^\n]+)\n)?((?[^\n]+)\n)?((?[^\n]+)\n)?((?[^\n]+)\n)?((?[^\n]+)\n)?((?[^\n]+)\n)?((?[^\n]+)\n)?((?[^\n]+)\n)?((?[^\n]+)\n)?(-.-)$”
$1st;
}

server {
location / {
proxy_set_header X-cert
$a$b$c$d$e$f$g$h$i$j$k$l$m$n$o$p$q$r$s$t$v$u$w$x$y$z;
proxy_pass http://localhost:8000;
}
}

Example works for up to 26 line certificate, you could extend it to
reasonable number of lines.

5

Thank you Sergey, this workaround suffices for us for now.

Posted at Nginx Forum:

6

Thanks for your reply. My application does not require the entire
certificate, so I am just forwarding $ssl_client_s_dn in a custom header
without any problems.

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