From a099270d452af92c5640d5d6712aa0987adb7c44 Mon Sep 17 00:00:00 2001
From: Jilles Tjoelker <jilles@stack.nl>
Date: Sun, 31 Jan 2010 19:04:20 +0100
Subject: [PATCH] Add certfp support to libratbox and ssld.

This lets a user connect with a client certificate, and
passes the certificate's fingerprint to ircd, which
currently just notices it to the user.

A new ssld->ircd message 'F' is used to pass on the
fingerprint.

This is only for OpenSSL for now, not GNUTLS.
---
 libratbox/include/rb_commio.h |  3 +++
 libratbox/src/gnutls.c        |  7 +++++++
 libratbox/src/nossl.c         |  6 ++++++
 libratbox/src/openssl.c       | 33 +++++++++++++++++++++++++++++++++
 src/sslproc.c                 | 26 ++++++++++++++++++++++++++
 ssld/ssld.c                   |  8 ++++++++
 6 files changed, 83 insertions(+)

diff --git a/libratbox/include/rb_commio.h b/libratbox/include/rb_commio.h
index 64aa889..1eef573 100644
--- a/libratbox/include/rb_commio.h
+++ b/libratbox/include/rb_commio.h
@@ -100,6 +100,8 @@ void rb_note(rb_fde_t *, const char *);
 #define RB_SELECT_ACCEPT		RB_SELECT_READ
 #define RB_SELECT_CONNECT		RB_SELECT_WRITE
 
+#define RB_SSL_CERTFP_LEN 20
+
 int rb_set_nb(rb_fde_t *);
 int rb_set_buffers(rb_fde_t *, int);
 
@@ -141,6 +143,7 @@ int rb_select(unsigned long);
 int rb_fd_ssl(rb_fde_t *F);
 int rb_get_fd(rb_fde_t *F);
 const char *rb_get_ssl_strerror(rb_fde_t *F);
+int rb_get_ssl_certfp(rb_fde_t *F, uint8_t certfp[RB_SSL_CERTFP_LEN]);
 
 rb_fde_t *rb_get_fde(int fd);
 
diff --git a/libratbox/src/gnutls.c b/libratbox/src/gnutls.c
index 0da7748..1b7f4d7 100644
--- a/libratbox/src/gnutls.c
+++ b/libratbox/src/gnutls.c
@@ -496,6 +496,13 @@ rb_get_ssl_strerror(rb_fde_t *F)
 	return gnutls_strerror(F->ssl_errno);
 }
 
+int
+rb_get_ssl_certfp(rb_fde_t *F, uint8_t certfp[RB_SSL_CERTFP_LEN])
+{
+	/* XXX implement this for gnutls */
+	return 0;
+}
+
 int
 rb_supports_ssl(void)
 {
diff --git a/libratbox/src/nossl.c b/libratbox/src/nossl.c
index 1d5c15f..ee85189 100644
--- a/libratbox/src/nossl.c
+++ b/libratbox/src/nossl.c
@@ -100,6 +100,12 @@ rb_get_ssl_strerror(rb_fde_t *F)
 	return nosupport;
 }
 
+int
+rb_get_ssl_certfp(rb_fde_t *F, uint8_t certfp[RB_SSL_CERTFP_LEN])
+{
+	return 0;
+}
+
 void
 rb_ssl_start_accepted(rb_fde_t *new_F, ACCB * cb, void *data, int timeout)
 {
diff --git a/libratbox/src/openssl.c b/libratbox/src/openssl.c
index ffe8330..9ddc356 100644
--- a/libratbox/src/openssl.c
+++ b/libratbox/src/openssl.c
@@ -281,6 +281,12 @@ rb_ssl_write(rb_fde_t *F, const void *buf, size_t count)
 	return rb_ssl_read_or_write(1, F, NULL, buf, count);
 }
 
+static int
+verify_accept_all_cb(int preverify_ok, X509_STORE_CTX *x509_ctx)
+{
+	return 1;
+}
+
 int
 rb_init_ssl(void)
 {
@@ -298,6 +304,7 @@ rb_init_ssl(void)
 	}
 	/* Disable SSLv2, make the client use our settings */
 	SSL_CTX_set_options(ssl_server_ctx, SSL_OP_NO_SSLv2 | SSL_OP_CIPHER_SERVER_PREFERENCE);
+	SSL_CTX_set_verify(ssl_server_ctx, SSL_VERIFY_PEER | SSL_VERIFY_CLIENT_ONCE, verify_accept_all_cb);
 
 	ssl_client_ctx = SSL_CTX_new(TLSv1_client_method());
 
@@ -605,6 +612,32 @@ rb_get_ssl_strerror(rb_fde_t *F)
 	return ERR_error_string(F->ssl_errno, NULL);
 }
 
+int
+rb_get_ssl_certfp(rb_fde_t *F, uint8_t certfp[RB_SSL_CERTFP_LEN])
+{
+	X509 *cert;
+	int res;
+
+	if (F->ssl == NULL)
+		return 0;
+
+	cert = SSL_get_peer_certificate((SSL *) F->ssl);
+	if(cert != NULL)
+	{
+		res = SSL_get_verify_result((SSL *) F->ssl);
+		if(res == X509_V_OK ||
+				res == X509_V_ERR_SELF_SIGNED_CERT_IN_CHAIN ||
+				res == X509_V_ERR_UNABLE_TO_VERIFY_LEAF_SIGNATURE ||
+				res == X509_V_ERR_DEPTH_ZERO_SELF_SIGNED_CERT)
+		{
+			memcpy(certfp, cert->sha1_hash, RB_SSL_CERTFP_LEN);
+			return 1;
+		}
+	}
+
+	return 0;
+}
+
 int
 rb_supports_ssl(void)
 {
diff --git a/src/sslproc.c b/src/sslproc.c
index 573482a..b02a045 100644
--- a/src/sslproc.c
+++ b/src/sslproc.c
@@ -402,6 +402,29 @@ ssl_process_dead_fd(ssl_ctl_t * ctl, ssl_ctl_buf_t * ctl_buf)
 	exit_client(client_p, client_p, &me, reason);
 }
 
+static void
+ssl_process_certfp(ssl_ctl_t * ctl, ssl_ctl_buf_t * ctl_buf)
+{
+	struct Client *client_p;
+	int32_t fd;
+	uint8_t *certfp;
+	char certfp_string[RB_SSL_CERTFP_LEN * 2 + 1];
+	int i;
+
+	if(ctl_buf->buflen != 5 + RB_SSL_CERTFP_LEN)
+		return;		/* bogus message..drop it.. XXX should warn here */
+
+	fd = buf_to_int32(&ctl_buf->buf[1]);
+	certfp = (uint8_t *)&ctl_buf->buf[5];
+	client_p = find_cli_fd_hash(fd);
+	if(client_p == NULL)
+		return;
+	for(i = 0; i < RB_SSL_CERTFP_LEN; i++)
+		rb_snprintf(certfp_string + 2 * i, 3, "%02x",
+				certfp[i]);
+	sendto_one_notice(client_p, ":*** CertFP is %s", certfp_string);
+}
+
 static void
 ssl_process_cmd_recv(ssl_ctl_t * ctl)
 {
@@ -422,6 +445,9 @@ ssl_process_cmd_recv(ssl_ctl_t * ctl)
 		case 'D':
 			ssl_process_dead_fd(ctl, ctl_buf);
 			break;
+		case 'F':
+			ssl_process_certfp(ctl, ctl_buf);
+			break;
 		case 'S':
 			ssl_process_zipstats(ctl, ctl_buf);
 			break;
diff --git a/ssld/ssld.c b/ssld/ssld.c
index b28520d..a6c6b5f 100644
--- a/ssld/ssld.c
+++ b/ssld/ssld.c
@@ -679,8 +679,16 @@ static void
 ssl_process_accept_cb(rb_fde_t *F, int status, struct sockaddr *addr, rb_socklen_t len, void *data)
 {
 	conn_t *conn = data;
+	char buf[5 + RB_SSL_CERTFP_LEN];
+
 	if(status == RB_OK)
 	{
+		if(rb_get_ssl_certfp(F, &buf[5]))
+		{
+			buf[0] = 'F';
+			int32_to_buf(&buf[1], conn->id);
+			mod_cmd_write_queue(conn->ctl, buf, sizeof buf);
+		}
 		conn_mod_read_cb(conn->mod_fd, conn);
 		conn_plain_read_cb(conn->plain_fd, conn);
 		return;