Add the ability to mutate TLS handshake messages before they are written

We add callbacks so that TLS handshake messages can be modified by the test
framework before they are passed to the handshake hash, possibly encrypted
and written to the network. This enables us to simulate badly behaving
endpoints.

Reviewed-by: Hugo Landau <hlandau@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/20030)

include/internal/quic_channel.h

@@ -195,6 +195,8 @@ int ossl_quic_channel_is_terminated(const QUIC_CHANNEL *ch,
 int ossl_quic_channel_is_active(const QUIC_CHANNEL *ch);
 int ossl_quic_channel_is_handshake_complete(const QUIC_CHANNEL *ch);
 
+SSL *ossl_quic_channel_get0_ssl(QUIC_CHANNEL *ch);
+
 # endif
 
 #endif

include/internal/quic_tserver.h

@@ -13,6 +13,7 @@
 # include <openssl/ssl.h>
 # include "internal/quic_stream.h"
 # include "internal/quic_channel.h"
+# include "internal/statem.h"
 
 # ifndef OPENSSL_NO_QUIC
 
@@ -43,10 +44,15 @@ QUIC_TSERVER *ossl_quic_tserver_new(const QUIC_TSERVER_ARGS *args,
 void ossl_quic_tserver_free(QUIC_TSERVER *srv);
 
 /* Set mutator callbacks for test framework support */
-int ossl_quic_tserver_set_mutator(QUIC_TSERVER *srv,
-                                  ossl_mutate_packet_cb mutatecb,
-                                  ossl_finish_mutate_cb finishmutatecb,
-                                  void *mutatearg);
+int ossl_quic_tserver_set_plain_packet_mutator(QUIC_TSERVER *srv,
+                                               ossl_mutate_packet_cb mutatecb,
+                                               ossl_finish_mutate_cb finishmutatecb,
+                                               void *mutatearg);
+
+int ossl_quic_tserver_set_handshake_mutator(QUIC_TSERVER *srv,
+                                            ossl_statem_mutate_handshake_cb mutate_handshake_cb,
+                                            ossl_statem_finish_mutate_handshake_cb finish_mutate_handshake_cb,
+                                            void *mutatearg);
 
 /* Advances the state machine. */
 int ossl_quic_tserver_tick(QUIC_TSERVER *srv);

include/internal/statem.h

@@ -77,6 +77,14 @@ typedef enum {
     CON_FUNC_DONT_SEND
 } CON_FUNC_RETURN;
 
+typedef int (*ossl_statem_mutate_handshake_cb)(unsigned char *msgin,
+                                               size_t inlen,
+                                               unsigned char **msgout,
+                                               size_t *outlen,
+                                               void *arg);
+
+typedef void (*ossl_statem_finish_mutate_handshake_cb)(void *arg);
+
 /*****************************************************************************
  *                                                                           *
  * This structure should be considered "opaque" to anything outside of the   *
@@ -106,6 +114,12 @@ struct ossl_statem_st {
     /* Should we skip the CertificateVerify message? */
     unsigned int no_cert_verify;
     int use_timer;
+
+    /* Test harness message mutator callbacks */
+    ossl_statem_mutate_handshake_cb mutate_handshake_cb;
+    ossl_statem_finish_mutate_handshake_cb finish_mutate_handshake_cb;
+    void *mutatearg;
+    unsigned int write_in_progress : 1;
 };
 typedef struct ossl_statem_st OSSL_STATEM;
 
@@ -116,6 +130,8 @@ typedef struct ossl_statem_st OSSL_STATEM;
  *                                                                           *
  *****************************************************************************/
 
+typedef struct ssl_connection_st SSL_CONNECTION;
+
 __owur int ossl_statem_accept(SSL *s);
 __owur int ossl_statem_connect(SSL *s);
 OSSL_HANDSHAKE_STATE ossl_statem_get_state(SSL_CONNECTION *s);
@@ -144,3 +160,8 @@ __owur int ossl_statem_export_early_allowed(SSL_CONNECTION *s);
 
 /* Flush the write BIO */
 int statem_flush(SSL_CONNECTION *s);
+
+int ossl_statem_set_mutator(SSL *s,
+                            ossl_statem_mutate_handshake_cb mutate_handshake_cb,
+                            ossl_statem_finish_mutate_handshake_cb finish_mutate_handshake_cb,
+                            void *mutatearg);

ssl/quic/quic_channel.c

@@ -2081,3 +2081,8 @@ static int ch_server_on_new_conn(QUIC_CHANNEL *ch, const BIO_ADDR *peer,
     ch->doing_proactive_ver_neg = 0; /* not currently supported */
     return 1;
 }
+
+SSL *ossl_quic_channel_get0_ssl(QUIC_CHANNEL *ch)
+{
+    return ch->tls;
+}

ssl/quic/quic_tserver.c

@@ -123,15 +123,26 @@ void ossl_quic_tserver_free(QUIC_TSERVER *srv)
 }
 
 /* Set mutator callbacks for test framework support */
-int ossl_quic_tserver_set_mutator(QUIC_TSERVER *srv,
-                                  ossl_mutate_packet_cb mutatecb,
-                                  ossl_finish_mutate_cb finishmutatecb,
-                                  void *mutatearg)
+int ossl_quic_tserver_set_plain_packet_mutator(QUIC_TSERVER *srv,
+                                               ossl_mutate_packet_cb mutatecb,
+                                               ossl_finish_mutate_cb finishmutatecb,
+                                               void *mutatearg)
 {
     return ossl_quic_channel_set_mutator(srv->ch, mutatecb, finishmutatecb,
                                          mutatearg);
 }
 
+int ossl_quic_tserver_set_handshake_mutator(QUIC_TSERVER *srv,
+                                            ossl_statem_mutate_handshake_cb mutate_handshake_cb,
+                                            ossl_statem_finish_mutate_handshake_cb finish_mutate_handshake_cb,
+                                            void *mutatearg)
+{
+    return ossl_statem_set_mutator(ossl_quic_channel_get0_ssl(srv->ch),
+                                   mutate_handshake_cb,
+                                   finish_mutate_handshake_cb,
+                                   mutatearg);
+}
+
 int ossl_quic_tserver_tick(QUIC_TSERVER *srv)
 {
     ossl_quic_reactor_tick(ossl_quic_channel_get_reactor(srv->ch));

ssl/ssl_local.h

@@ -29,7 +29,7 @@
 # include <openssl/ct.h>
 # include "record/record.h"
 # include "internal/recordmethod.h"
-# include "statem/statem.h"
+# include "internal/statem.h"
 # include "internal/packet.h"
 # include "internal/dane.h"
 # include "internal/refcount.h"

ssl/statem/statem_lib.c

@@ -36,6 +36,23 @@ const unsigned char hrrrandom[] = {
     0x07, 0x9e, 0x09, 0xe2, 0xc8, 0xa8, 0x33, 0x9c
 };
 
+int ossl_statem_set_mutator(SSL *s,
+                            ossl_statem_mutate_handshake_cb mutate_handshake_cb,
+                            ossl_statem_finish_mutate_handshake_cb finish_mutate_handshake_cb,
+                            void *mutatearg)
+{
+    SSL_CONNECTION *sc = SSL_CONNECTION_FROM_SSL(s);
+
+    if (sc == NULL)
+        return 0;
+
+    sc->statem.mutate_handshake_cb = mutate_handshake_cb;
+    sc->statem.mutatearg = mutatearg;
+    sc->statem.finish_mutate_handshake_cb = finish_mutate_handshake_cb;
+
+    return 1;
+}
+
 /*
  * send s->init_buf in records of type 'type' (SSL3_RT_HANDSHAKE or
  * SSL3_RT_CHANGE_CIPHER_SPEC)
@@ -46,6 +63,32 @@ int ssl3_do_write(SSL_CONNECTION *s, int type)
     size_t written = 0;
     SSL *ssl = SSL_CONNECTION_GET_SSL(s);
 
+    /*
+     * If we're running the test suite then we may need to mutate the message
+     * we've been asked to write. Does not happen in normal operation.
+     */
+    if (s->statem.mutate_handshake_cb != NULL
+            && !s->statem.write_in_progress
+            && type == SSL3_RT_HANDSHAKE
+            && s->init_num >= SSL3_HM_HEADER_LENGTH) {
+        unsigned char *msg;
+        size_t msglen;
+
+        if (!s->statem.mutate_handshake_cb((unsigned char *)s->init_buf->data,
+                                           s->init_num,
+                                           &msg, &msglen,
+                                           s->statem.mutatearg))
+            return -1;
+        if (msglen < SSL3_HM_HEADER_LENGTH
+                || !BUF_MEM_grow(s->init_buf, msglen))
+            return -1;
+        memcpy(s->init_buf->data, msg, msglen);
+        s->init_num = msglen;
+        s->init_msg = s->init_buf->data + SSL3_HM_HEADER_LENGTH;
+        s->statem.finish_mutate_handshake_cb(s->statem.mutatearg);
+        s->statem.write_in_progress = 1;
+    }
+
     ret = ssl3_write_bytes(ssl, type, &s->init_buf->data[s->init_off],
                            s->init_num, &written);
     if (ret < 0)
@@ -65,6 +108,7 @@ int ssl3_do_write(SSL_CONNECTION *s, int type)
                                  written))
                 return -1;
     if (written == s->init_num) {
+        s->statem.write_in_progress = 0;
         if (s->msg_callback)
             s->msg_callback(1, s->version, type, s->init_buf->data,
                             (size_t)(s->init_off + s->init_num), ssl,

test/helpers/quictestlib.c

@@ -240,8 +240,10 @@ int ossl_quic_fault_set_packet_plain_listener(OSSL_QUIC_FAULT *fault,
     fault->pplaincb = pplaincb;
     fault->pplaincbarg = pplaincbarg;
 
-    return ossl_quic_tserver_set_mutator(fault->qtserv, packet_plain_mutate,
-                                         packet_plain_finish, fault);
+    return ossl_quic_tserver_set_plain_packet_mutator(fault->qtserv,
+                                                      packet_plain_mutate,
+                                                      packet_plain_finish,
+                                                      fault);
 }
 
 /* To be called from a packet_plain_listener callback */