Introduce privsep for private keys:

- Move RSA private keys to a new separate process instead of copying
them to the relays.  A custom RSA engine is used by the SSL/TLS code
of the relay processes to send RSA private key encryption/decryption
(also used for sign/verify) requests to the new "ca" processes instead
of operating on the private key directly.

- Each relay process gets its own related ca process.  Setting
"prefork 5" in the config file will spawn 10 processes (5 relay, 5
ca).  This diff also reduces the default number of relay processes
from 5 to 3 which should be suitable in most installations without a
very heavy load.

- Don't keep text versions of the keys in memory, parse them once and
keep the binary representation.  This might still be the case in
OpenSSL's internals but will be fixed in the library.

This diff doesn't prevent something like "heartbleed" but adds an
additional mitigation to prevent leakage of the private keys from the
processes doing SSL/TLS.

With feedback from many
ok benno@

1 files changed, 19 insertions, 5 deletions

diff --git a/usr.sbin/relayd/relay.c b/usr.sbin/relayd/relay.c
index 8c73ded7bcd..ad7b7f86b65 100644
--- a/usr.sbin/relayd/relay.c
+++ b/usr.sbin/relayd/relay.c
@@ -1,7 +1,7 @@
-/*	$OpenBSD: relay.c,v 1.167 2013/09/09 17:57:44 reyk Exp $	*/
+/*	$OpenBSD: relay.c,v 1.168 2014/04/18 13:55:26 reyk Exp $	*/
 
 /*
- * Copyright (c) 2006 - 2013 Reyk Floeter <reyk@openbsd.org>
+ * Copyright (c) 2006 - 2014 Reyk Floeter <reyk@openbsd.org>
  *
  * Permission to use, copy, modify, and distribute this software for any
  * purpose with or without fee is hereby granted, provided that the above
@@ -52,6 +52,8 @@ int		 relay_dispatch_parent(int, struct privsep_proc *,
 		    struct imsg *);
 int		 relay_dispatch_pfe(int, struct privsep_proc *,
 		    struct imsg *);
+int		 relay_dispatch_ca(int, struct privsep_proc *,
+		    struct imsg *);
 void		 relay_shutdown(void);
 
 void		 relay_nodedebug(const char *, struct protonode *);
@@ -96,6 +98,7 @@ int				 proc_id;
 static struct privsep_proc procs[] = {
 	{ "parent",	PROC_PARENT,	relay_dispatch_parent },
 	{ "pfe",	PROC_PFE,	relay_dispatch_pfe },
+	{ "ca",		PROC_CA,	relay_dispatch_ca }
 };
 
 pid_t
@@ -1782,6 +1785,12 @@ relay_dispatch_pfe(int fd, struct privsep_proc *p, struct imsg *imsg)
 }
 
 int
+relay_dispatch_ca(int fd, struct privsep_proc *p, struct imsg *imsg)
+{
+	return (-1);
+}
+
+int
 relay_dispatch_parent(int fd, struct privsep_proc *p, struct imsg *imsg)
 {
 	struct rsession		*con;
@@ -1904,9 +1913,11 @@ relay_ssl_ctx_create(struct relay *rlay)
 		goto err;
 
 	log_debug("%s: loading private key", __func__);
-	if (!ssl_ctx_use_private_key(ctx, rlay->rl_ssl_key,
-	    rlay->rl_conf.ssl_key_len))
+	if (!ssl_ctx_fake_private_key(ctx,
+	    &rlay->rl_conf.id, rlay->rl_ssl_cert, rlay->rl_conf.ssl_cert_len,
+	    &rlay->rl_ssl_x509, &rlay->rl_ssl_pkey))
 		goto err;
+
 	if (!SSL_CTX_check_private_key(ctx))
 		goto err;
 
@@ -1915,6 +1926,9 @@ relay_ssl_ctx_create(struct relay *rlay)
 	    strlen(rlay->rl_conf.name)))
 		goto err;
 
+	/* The text versions of the keys/certs are not needed anymore */
+	purge_key(&rlay->rl_ssl_cert, rlay->rl_conf.ssl_cert_len);
+
 	return (ctx);
 
  err:
@@ -2087,7 +2101,7 @@ relay_ssl_connect(int fd, short event, void *arg)
 		    SSL_get_peer_certificate(con->se_out.ssl)) != NULL) {
 			con->se_in.sslcert =
 			    ssl_update_certificate(servercert,
-			    rlay->rl_ssl_key, rlay->rl_conf.ssl_key_len,
+			    rlay->rl_ssl_pkey,
 			    rlay->rl_ssl_cakey, rlay->rl_conf.ssl_cakey_len,
 			    rlay->rl_ssl_cacert, rlay->rl_conf.ssl_cacert_len);
 		} else