Improve tls client cert handling

* Improve nginx setup to transfer auth information to the fcgiwrap
 backend.
 * Add instructions for creating client certs for testing.
 * Add debug output to see if and which client cert has been used when
   calling the csaf_provider.go .

cmd/csaf_provider/controller.go

@@ -14,6 +14,7 @@ import (
 	"html/template"
 	"log"
 	"net/http"
+	"os"
 	"strings"
 )
 
@@ -69,15 +70,21 @@ func (c *controller) bind(pim *pathInfoMux) {
 func (c *controller) auth(
 	fn func(http.ResponseWriter, *http.Request),
 ) func(http.ResponseWriter, *http.Request) {
-
-	if c.cfg.Password == nil {
-		return fn
-	}
 	return func(rw http.ResponseWriter, r *http.Request) {
-		hash := r.Header.Get("X-CSAF-PROVIDER-AUTH")
-		if !c.cfg.checkPassword(hash) {
+		log.Printf("SSL_CLIENT_VERIFY: %s\n", os.Getenv("SSL_CLIENT_VERIFY"))
+		if os.Getenv("SSL_CLIENT_VERIFY") == "SUCCESS" {
+			log.Printf("user: %s\n", os.Getenv("SSL_CLIENT_S_DN"))
+			log.Printf("ca: %s\n", os.Getenv("SSL_CLIENT_I_DN"))
+		} else if c.cfg.Password == nil {
+			log.Printf("No password set, declining access.")
 			http.Error(rw, http.StatusText(http.StatusForbidden), http.StatusForbidden)
 			return
+		} else {
+		    hash := r.Header.Get("X-CSAF-PROVIDER-AUTH")
+		    if !c.cfg.checkPassword(hash) {
+			    http.Error(rw, http.StatusText(http.StatusForbidden), http.StatusForbidden)
+				return
+			}
 		}
 		fn(rw, r)
 	}

docs/client-certificate-setup.md

@@ -12,25 +12,36 @@ server {
     # Other Config
     # ...
 
-    ssl_client_certificate /etc/ssl/ca.crt;
+    ssl_client_certificate /etc/ssl/rootca-cert.pem;
     ssl_verify_client optional;
     ssl_verify_depth 2;
 
-    location ~* /.well-known/csaf/(red|green|amber)/{
-        autoindex on;a
+    # This example allows access to all three TLP locations for all certs.
+    location ~ /.well-known/csaf/(red|green|amber)/{
+        autoindex on;
+        # in this location access is only allowed with client certs
         if  ($ssl_client_verify != SUCCESS){
-            return 403;
+            # we use status code 404 == "Not Found", because we do not
+            # want to reveal if this location exists or not.
+            return 404;
         }
     }
-
 }
 ```
-This will restrict the access to the defined paths in the ```location``` directive  to only authenticated client certificates.
+This will restrict the access to the defined paths in the ```location```
+directive to only authenticated client certificates issued by the CAs
+which are configured with `ssl_client_certificate`.
+
+If you want to restrict each path of `green`, `amber` and `red`
+differently, you could use several location blocks
+each which a single `if` that matches the `$ssl_client_i_dn` variable
+to CAs that you would want to allow for that location.
 
 Reload or restart nginx to apply the changes (e.g. `systemctl reload nginx`
 on Debian or Ubuntu.)
 
-To test this:
-* From the browser after importing the ```userA.pfx``` and the navigation to the protected directories.
-* With curl: ```curl https://{serverURL}/.well-known/csaf/red/ --cert /etc/ssl/userA.crt --key /etc/ssl/userA.key```.
+To test this see [development-client-certs.md](development-client-certs.md) and
+* From the browser after importing the `testclient1.p12`:
+nagivate to the protected directories.
+* With curl: `curl https://{serverURL}/.well-known/csaf/red/ --cert-type p12 --cert testclient1.crt`
 

docs/development-client-certs.md

@@ -0,0 +1,58 @@
+# Create TLS client certificates (for testing)
+
+For testing and development purposes we reuse
+the bare bones certificate authority from the
+[development-ca.md](development-ca.md).
+
+(In production setups, it is very likely that two different CAs
+would used for server and for client certificates.)
+
+The following lines directly create the client certificate.
+(As opposed to first creating a certificate signing request and
+then signing it.)
+
+```bash
+# being in devca1/
+certtool --generate-privkey --outfile testclient1-key.pem
+
+echo '
+organization = "CSAF Tools Development (internal)"
+country = DE
+cn = "TLS Test Client 1"
+
+tls_www_client
+signing_key
+encryption_key
+
+serial = 020
+expiration_days = 50
+' > gnutls-certtool.testclient1.template
+
+certtool --generate-certificate --load-privkey testclient1-key.pem --outfile testclient1.crt --load-ca-certificate rootca-cert.pem --load-ca-privkey rootca-key.pem --template gnutls-certtool.testclient1.template
+
+certtool --load-ca-certificate rootca-cert.pem --load-certificate testclient1.crt --load-privkey testclient1-key.pem --to-p12 --p12-name "Test Client 1" --null-password --outder --outfile testclient1.p12
+```
+
+and we do a second one with shorter expiration day:
+
+```bash
+certtool --generate-privkey --outfile testclient2-key.pem
+
+echo '
+organization = "CSAF Tools Development (internal)"
+country = DE
+cn = "TLS Test Client 2"
+
+tls_www_client
+signing_key
+encryption_key
+
+serial = 021
+expiration_days = 1
+' > gnutls-certtool.testclient2.template
+
+certtool --generate-certificate --load-privkey testclient2-key.pem --outfile testclient2.crt --load-ca-certificate rootca-cert.pem --load-ca-privkey rootca-key.pem --template gnutls-certtool.testclient2.template
+
+certtool --load-ca-certificate rootca-cert.pem --load-certificate testclient2.crt --load-privkey testclient2-key.pem --to-p12 --p12-name "Test Client 2" --null-password --outder --outfile testclient2.p12
+```
+

docs/provider-setup.md

@@ -46,6 +46,10 @@ location /cgi-bin/ {
 
   fastcgi_param PATH_INFO $fastcgi_path_info;
   fastcgi_param CSAF_CONFIG /usr/lib/csaf/config.toml;
+
+  fastcgi_param SSL_CLIENT_VERIFY $ssl_client_verify;
+  fastcgi_param SSL_CLIENT_S_DN $ssl_client_s_dn;
+  fastcgi_param SSL_CLIENT_I_DN $ssl_client_i_dn;
 }
 ```
 
@@ -54,6 +58,8 @@ Add to `/etc/nginx/sites-enabled/default`:
 ```
 server {
 
+    root /usr/share/nginx/html;
+
     location / {
         # Other config
         # ... 
@@ -74,7 +80,7 @@ server {
 Place the binary under `/usr/lib/cgi-bin/csaf_provider.go`.
 Make sure `/usr/lib/cgi-bin/` exists.
 
-Create configuarion file under `/usr/lib/csaf/config.toml`:
+Create configuration file under `/usr/lib/csaf/config.toml`:
 
 ```
 # upload_signature = true