On Fri, Nov 06, 2009 at 12:00:06AM +0000, Joe Orton wrote:
> On Thu, Nov 05, 2009 at 09:31:00PM +0000, Joe Orton wrote:
> > * we can detect in mod_ssl when the client is renegotiating by using the
> > callback installed using SSL_CTX_set_info_callback(), in conjunction
> > with suitable flags in the SSLConnRec to detect the cases where this is
> > either a server-initiated renegotiation or the initial handshake on the
> > connection.
>
> Here is a very rough first hack (for discussion/testing purposes only!):
A second hack, slightly less rough hack:
Index: ssl_private.h
===================================================================
--- ssl_private.h (revision 832979)
+++ ssl_private.h (working copy)
@@ -335,6 +335,20 @@
int is_proxy;
int disabled;
int non_ssl_request;
+
+ /* Track the handshake/renegotiation state for the connection so
+ * that all client-initiated renegotiations can be rejected, as a
+ * partial fix for CVE-2009-3555. */
+ enum {
+ RENEG_INIT = 0, /* Before initial handshake */
+ RENEG_REJECT, /* After initial handshake; any client-initiated
+ * renegotiation should be rejected */
+ RENEG_ALLOW, /* A server-initated renegotiation is taking
+ * place (as dictated by configuration) */
+ RENEG_ABORT /* Renegotiation initiated by client, abort the
+ * connection */
+ } reneg_state;
+
server_rec *server;
} SSLConnRec;
@@ -618,7 +632,7 @@
int ssl_callback_NewSessionCacheEntry(SSL *, SSL_SESSION *);
SSL_SESSION *ssl_callback_GetSessionCacheEntry(SSL *, unsigned char *, int,
int *);
void ssl_callback_DelSessionCacheEntry(SSL_CTX *, SSL_SESSION *);
-void ssl_callback_LogTracingState(MODSSL_INFO_CB_ARG_TYPE, int, int);
+void ssl_callback_Info(MODSSL_INFO_CB_ARG_TYPE, int, int);
#ifndef OPENSSL_NO_TLSEXT
int ssl_callback_ServerNameIndication(SSL *, int *, modssl_ctx_t *);
#endif
Index: ssl_engine_init.c
===================================================================
--- ssl_engine_init.c (revision 832979)
+++ ssl_engine_init.c (working copy)
@@ -520,10 +520,7 @@
SSL_CTX_set_tmp_rsa_callback(ctx, ssl_callback_TmpRSA);
SSL_CTX_set_tmp_dh_callback(ctx, ssl_callback_TmpDH);
- if (s->loglevel >= APLOG_DEBUG) {
- /* this callback only logs if LogLevel >= info */
- SSL_CTX_set_info_callback(ctx, ssl_callback_LogTracingState);
- }
+ SSL_CTX_set_info_callback(ctx, ssl_callback_Info);
}
static void ssl_init_ctx_verify(server_rec *s,
Index: ssl_engine_io.c
===================================================================
--- ssl_engine_io.c (revision 832979)
+++ ssl_engine_io.c (working copy)
@@ -103,6 +103,7 @@
ap_filter_t *pInputFilter;
ap_filter_t *pOutputFilter;
int nobuffer; /* non-zero to prevent buffering */
+ SSLConnRec *config;
} ssl_filter_ctx_t;
typedef struct {
@@ -193,7 +194,13 @@
static int bio_filter_out_write(BIO *bio, const char *in, int inl)
{
bio_filter_out_ctx_t *outctx = (bio_filter_out_ctx_t *)(bio->ptr);
-
+
+ /* Abort early if the client has initiated a renegotiation. */
+ if (outctx->filter_ctx->config->reneg_state == RENEG_ABORT) {
+ outctx->rc = APR_ECONNABORTED;
+ return -1;
+ }
+
/* when handshaking we'll have a small number of bytes.
* max size SSL will pass us here is about 16k.
* (16413 bytes to be exact)
@@ -476,6 +483,12 @@
if (!in)
return 0;
+ /* Abort early if the client has initiated a renegotiation. */
+ if (inctx->filter_ctx->config->reneg_state == RENEG_ABORT) {
+ inctx->rc = APR_ECONNABORTED;
+ return -1;
+ }
+
/* In theory, OpenSSL should flush as necessary, but it is known
* not to do so correctly in some cases; see PR 46952.
*
@@ -1699,6 +1712,8 @@
filter_ctx = apr_palloc(c->pool, sizeof(ssl_filter_ctx_t));
+ filter_ctx->config = myConnConfig(c);
+
filter_ctx->nobuffer = 0;
filter_ctx->pOutputFilter = ap_add_output_filter(ssl_io_filter,
filter_ctx, r, c);
Index: ssl_engine_kernel.c
===================================================================
--- ssl_engine_kernel.c (revision 832979)
+++ ssl_engine_kernel.c (working copy)
@@ -733,6 +733,10 @@
(unsigned char *)&id,
sizeof(id));
+ /* Toggle the renegotiation state to allow the new
+ * handshake to proceed. */
+ sslconn->reneg_state = RENEG_ALLOW;
+
SSL_renegotiate(ssl);
SSL_do_handshake(ssl);
@@ -754,6 +758,8 @@
SSL_set_state(ssl, SSL_ST_ACCEPT);
SSL_do_handshake(ssl);
+ sslconn->reneg_state = RENEG_REJECT;
+
if (SSL_get_state(ssl) != SSL_ST_OK) {
ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
"Re-negotiation handshake failed: "
@@ -1814,76 +1820,55 @@
return;
}
-/*
- * This callback function is executed while OpenSSL processes the
- * SSL handshake and does SSL record layer stuff. We use it to
- * trace OpenSSL's processing in out SSL logfile.
- */
-void ssl_callback_LogTracingState(MODSSL_INFO_CB_ARG_TYPE ssl, int where, int
rc)
+/* Dump debugginfo trace to the log file. */
+static void log_tracing_state(MODSSL_INFO_CB_ARG_TYPE ssl, server_rec *s,
+ conn_rec *c, int where, int rc)
{
- conn_rec *c;
- server_rec *s;
- SSLSrvConfigRec *sc;
-
/*
- * find corresponding server
+ * create the various trace messages
*/
- if (!(c = (conn_rec *)SSL_get_app_data((SSL *)ssl))) {
- return;
+ if (where & SSL_CB_HANDSHAKE_START) {
+ ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s,
+ "%s: Handshake: start", SSL_LIBRARY_NAME);
}
-
- s = mySrvFromConn(c);
- if (!(sc = mySrvConfig(s))) {
- return;
+ else if (where & SSL_CB_HANDSHAKE_DONE) {
+ ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s,
+ "%s: Handshake: done", SSL_LIBRARY_NAME);
}
-
- /*
- * create the various trace messages
- */
- if (s->loglevel >= APLOG_DEBUG) {
- if (where & SSL_CB_HANDSHAKE_START) {
+ else if (where & SSL_CB_LOOP) {
+ ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s,
+ "%s: Loop: %s",
+ SSL_LIBRARY_NAME, SSL_state_string_long(ssl));
+ }
+ else if (where & SSL_CB_READ) {
+ ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s,
+ "%s: Read: %s",
+ SSL_LIBRARY_NAME, SSL_state_string_long(ssl));
+ }
+ else if (where & SSL_CB_WRITE) {
+ ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s,
+ "%s: Write: %s",
+ SSL_LIBRARY_NAME, SSL_state_string_long(ssl));
+ }
+ else if (where & SSL_CB_ALERT) {
+ char *str = (where & SSL_CB_READ) ? "read" : "write";
+ ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s,
+ "%s: Alert: %s:%s:%s",
+ SSL_LIBRARY_NAME, str,
+ SSL_alert_type_string_long(rc),
+ SSL_alert_desc_string_long(rc));
+ }
+ else if (where & SSL_CB_EXIT) {
+ if (rc == 0) {
ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s,
- "%s: Handshake: start", SSL_LIBRARY_NAME);
- }
- else if (where & SSL_CB_HANDSHAKE_DONE) {
- ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s,
- "%s: Handshake: done", SSL_LIBRARY_NAME);
- }
- else if (where & SSL_CB_LOOP) {
- ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s,
- "%s: Loop: %s",
+ "%s: Exit: failed in %s",
SSL_LIBRARY_NAME, SSL_state_string_long(ssl));
}
- else if (where & SSL_CB_READ) {
+ else if (rc < 0) {
ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s,
- "%s: Read: %s",
+ "%s: Exit: error in %s",
SSL_LIBRARY_NAME, SSL_state_string_long(ssl));
}
- else if (where & SSL_CB_WRITE) {
- ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s,
- "%s: Write: %s",
- SSL_LIBRARY_NAME, SSL_state_string_long(ssl));
- }
- else if (where & SSL_CB_ALERT) {
- char *str = (where & SSL_CB_READ) ? "read" : "write";
- ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s,
- "%s: Alert: %s:%s:%s",
- SSL_LIBRARY_NAME, str,
- SSL_alert_type_string_long(rc),
- SSL_alert_desc_string_long(rc));
- }
- else if (where & SSL_CB_EXIT) {
- if (rc == 0) {
- ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s,
- "%s: Exit: failed in %s",
- SSL_LIBRARY_NAME, SSL_state_string_long(ssl));
- }
- else if (rc < 0) {
- ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, s,
- "%s: Exit: error in %s",
- SSL_LIBRARY_NAME, SSL_state_string_long(ssl));
- }
- }
}
/*
@@ -1903,6 +1888,60 @@
}
}
+/*
+ * This callback function is executed while OpenSSL processes the SSL
+ * handshake and does SSL record layer stuff. It's used to trap
+ * client-initiated renegotiations, and for dumping everything to the
+ * log.
+ */
+void ssl_callback_Info(MODSSL_INFO_CB_ARG_TYPE ssl, int where, int rc)
+{
+ conn_rec *c;
+ server_rec *s;
+ SSLSrvConfigRec *sc;
+ SSLConnRec *scr;
+
+ /*
+ * find corresponding server
+ */
+ if (!(c = (conn_rec *)SSL_get_app_data((SSL *)ssl))) {
+ return;
+ }
+
+ scr = myConnConfig(c);
+ if (!scr) {
+ return;
+ }
+
+ /* If the reneg state is to reject renegotiations, check the SSL
+ * state machine and move to ABORT if a Client Hello is being
+ * read. */
+ if ((where & SSL_CB_ACCEPT_LOOP) && scr->reneg_state == RENEG_REJECT) {
+ int state = SSL_get_state(ssl);
+
+ if (state == SSL3_ST_SR_CLNT_HELLO_A
+ || state == SSL23_ST_SR_CLNT_HELLO_A) {
+ scr->reneg_state = RENEG_ABORT;
+ ap_log_cerror(APLOG_MARK, APLOG_ERR, 0, c,
+ "rejecting client initiated renegotiation");
+ }
+ }
+ /* If the first handshake is complete, change state to reject any
+ * subsequent client-initated renegotiation. */
+ else if (where & SSL_CB_HANDSHAKE_DONE && scr->reneg_state == RENEG_INIT) {
+ scr->reneg_state = RENEG_REJECT;
+ }
+
+ s = mySrvFromConn(c);
+ if (!(sc = mySrvConfig(s))) {
+ return;
+ }
+
+ if (s->loglevel >= APLOG_DEBUG) {
+ log_tracing_state(ssl, s, c, where, rc);
+ }
+}
+
#ifndef OPENSSL_NO_TLSEXT
/*
* This callback function is executed when OpenSSL encounters an extended
