X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?a=blobdiff_plain;f=site.c;h=9f3ee856b8adb2cb015b477b2ba5e64afc852eef;hb=b67dab18678d3628929999fc77c48a5bc660e5e2;hp=0cd364b8135e963c7b923a684836baec2ccc1294;hpb=20138876b39edc6b9bbcc79789c5aa1a684d3312;p=secnet.git

diff --git a/site.c b/site.c
index 0cd364b..9f3ee85 100644
--- a/site.c
+++ b/site.c
@@ -277,6 +277,7 @@ struct site {
     uint8_t localN[NONCELEN]; /* Nonces for key exchange */
     uint8_t remoteN[NONCELEN];
     struct buffer_if buffer; /* Current outgoing key exchange packet */
+    struct buffer_if scratch;
     int32_t retries; /* Number of retries remaining */
     uint64_t timeout; /* Timeout for current state */
     uint8_t *dhsecret;
@@ -321,6 +322,7 @@ static void enter_state_run(struct site *st);
 static bool_t enter_state_resolve(struct site *st);
 static bool_t enter_new_state(struct site *st,uint32_t next);
 static void enter_state_wait(struct site *st);
+static void activate_new_key(struct site *st);
 
 #define CHECK_AVAIL(b,l) do { if ((b)->size<(l)) return False; } while(0)
 #define CHECK_EMPTY(b) do { if ((b)->size!=0) return False; } while(0)
@@ -628,7 +630,6 @@ static bool_t generate_msg5(struct site *st)
     buffer_init(&st->buffer,st->transform->max_start_pad+(4*4));
     /* Give the netlink code an opportunity to put its own stuff in the
        message (configuration information, etc.) */
-    st->netlink->output_config(st->netlink->st,&st->buffer);
     buf_prepend_uint32(&st->buffer,LABEL_MSG5);
     st->new_transform->forwards(st->new_transform->st,&st->buffer,
 				&transform_err);
@@ -641,15 +642,15 @@ static bool_t generate_msg5(struct site *st)
 }
 
 static bool_t process_msg5(struct site *st, struct buffer_if *msg5,
-			   const struct comm_addr *src)
+			   const struct comm_addr *src,
+			   struct transform_inst_if *transform)
 {
     struct msg0 m;
     cstring_t transform_err;
 
     if (!unpick_msg0(st,msg5,&m)) return False;
 
-    if (st->new_transform->reverse(st->new_transform->st,
-				   msg5,&transform_err)) {
+    if (transform->reverse(transform->st,msg5,&transform_err)) {
 	/* There's a problem */
 	slog(st,LOG_SEC,"process_msg5: transform: %s",transform_err);
 	return False;
@@ -660,15 +661,13 @@ static bool_t process_msg5(struct site *st, struct buffer_if *msg5,
 	slog(st,LOG_SEC,"MSG5/PING packet contained wrong label");
 	return False;
     }
-    if (!st->netlink->check_config(st->netlink->st,msg5)) {
-	slog(st,LOG_SEC,"MSG5/PING packet contained bad netlink config");
-	return False;
-    }
-    CHECK_EMPTY(msg5);
+    /* Older versions of secnet used to write some config data here
+     * which we ignore.  So we don't CHECK_EMPTY */
     return True;
 }
 
-static bool_t generate_msg6(struct site *st)
+static void create_msg6(struct site *st, struct transform_inst_if *transform,
+			uint32_t session_id)
 {
     cstring_t transform_err;
 
@@ -677,14 +676,16 @@ static bool_t generate_msg6(struct site *st)
     buffer_init(&st->buffer,st->transform->max_start_pad+(4*4));
     /* Give the netlink code an opportunity to put its own stuff in the
        message (configuration information, etc.) */
-    st->netlink->output_config(st->netlink->st,&st->buffer);
     buf_prepend_uint32(&st->buffer,LABEL_MSG6);
-    st->new_transform->forwards(st->new_transform->st,&st->buffer,
-				&transform_err);
+    transform->forwards(transform->st,&st->buffer,&transform_err);
     buf_prepend_uint32(&st->buffer,LABEL_MSG6);
     buf_prepend_uint32(&st->buffer,st->index);
-    buf_prepend_uint32(&st->buffer,st->setup_session_id);
+    buf_prepend_uint32(&st->buffer,session_id);
+}
 
+static bool_t generate_msg6(struct site *st)
+{
+    create_msg6(st,st->new_transform,st->setup_session_id);
     st->retries=1; /* Peer will retransmit MSG5 if this packet gets lost */
     return True;
 }
@@ -709,34 +710,58 @@ static bool_t process_msg6(struct site *st, struct buffer_if *msg6,
 	slog(st,LOG_SEC,"MSG6/PONG packet contained invalid data");
 	return False;
     }
-    if (!st->netlink->check_config(st->netlink->st,msg6)) {
-	slog(st,LOG_SEC,"MSG6/PONG packet contained bad netlink config");
+    /* Older versions of secnet used to write some config data here
+     * which we ignore.  So we don't CHECK_EMPTY */
+    return True;
+}
+
+static bool_t decrypt_msg0(struct site *st, struct buffer_if *msg0)
+{
+    cstring_t transform_err, newkey_err="n/a";
+    struct msg0 m;
+    uint32_t problem;
+
+    if (!unpick_msg0(st,msg0,&m)) return False;
+
+    /* Keep a copy so we can try decrypting it with multiple keys */
+    buffer_copy(&st->scratch, msg0);
+
+    problem = st->current_transform->reverse(st->current_transform->st,
+					     msg0,&transform_err);
+    if (!problem) return True;
+
+    if (problem==2) {
+	slog(st,LOG_DROP,"transform: %s (merely skew)",transform_err);
 	return False;
     }
-    CHECK_EMPTY(msg6);
-    return True;
+
+    if (st->state==SITE_SENTMSG5) {
+	buffer_copy(msg0, &st->scratch);
+	if (!st->new_transform->reverse(st->new_transform->st,
+					msg0,&newkey_err)) {
+	    /* It looks like we didn't get the peer's MSG6 */
+	    /* This is like a cut-down enter_new_state(SITE_RUN) */
+	    slog(st,LOG_STATE,"will enter state RUN (MSG0 with new key)");
+	    BUF_FREE(&st->buffer);
+	    st->timeout=0;
+	    activate_new_key(st);
+	    return True; /* do process the data in this packet */
+	}
+    }
+
+    slog(st,LOG_SEC,"transform: %s (new: %s)",transform_err,newkey_err);
+    initiate_key_setup(st,"incoming message would not decrypt");
+    return False;
 }
 
 static bool_t process_msg0(struct site *st, struct buffer_if *msg0,
 			   const struct comm_addr *src)
 {
-    struct msg0 m;
-    cstring_t transform_err;
     uint32_t type;
 
-    if (!st->current_valid) {
-	slog(st,LOG_DROP,"incoming message but no current key -> dropping");
-	return initiate_key_setup(st,"incoming message but no current key");
-    }
-
-    if (!unpick_msg0(st,msg0,&m)) return False;
+    if (!decrypt_msg0(st,msg0))
+	return False;
 
-    if (st->current_transform->reverse(st->current_transform->st,
-				       msg0,&transform_err)) {
-	/* There's a problem */
-	slog(st,LOG_SEC,"transform: %s",transform_err);
-	return initiate_key_setup(st,"incoming message would not decrypt");
-    }
     CHECK_AVAIL(msg0,4);
     type=buf_unprepend_uint32(msg0);
     switch(type) {
@@ -1234,16 +1259,28 @@ static bool_t site_incoming(void *sst, struct buffer_if *buf,
 	    /* Setup packet: expected only in state SENTMSG4 */
 	    /* (may turn up in state RUN if our return MSG6 was lost
 	       and the new key has already been activated. In that
-	       case we should treat it as an ordinary PING packet. We
-	       can't pass it to process_msg5() because the
-	       new_transform will now be unkeyed. XXX) */
-	    if (st->state!=SITE_SENTMSG4) {
-		slog(st,LOG_UNEXPECTED,"unexpected MSG5");
-	    } else if (process_msg5(st,buf,source)) {
-		transport_setup_msgok(st,source);
-		enter_new_state(st,SITE_RUN);
+	       case we discard it. The peer will realise that we
+	       are using the new key when they see our data packets.
+	       Until then the peer's data packets to us get discarded. */
+	    if (st->state==SITE_SENTMSG4) {
+		if (process_msg5(st,buf,source,st->new_transform)) {
+		    transport_setup_msgok(st,source);
+		    enter_new_state(st,SITE_RUN);
+		} else {
+		    slog(st,LOG_SEC,"invalid MSG5");
+		}
+	    } else if (st->state==SITE_RUN) {
+		if (process_msg5(st,buf,source,st->current_transform)) {
+		    slog(st,LOG_DROP,"got MSG5, retransmitting MSG6");
+		    transport_setup_msgok(st,source);
+		    create_msg6(st,st->current_transform,st->remote_session_id);
+		    transport_xmit(st,&st->peers,&st->buffer,True);
+		    BUF_FREE(&st->buffer);
+		} else {
+		    slog(st,LOG_SEC,"invalid MSG5 (in state RUN)");
+		}
 	    } else {
-		slog(st,LOG_SEC,"invalid MSG5");
+		slog(st,LOG_UNEXPECTED,"unexpected MSG5");
 	    }
 	    break;
 	case LABEL_MSG6:
@@ -1342,15 +1379,16 @@ static list_t *site_apply(closure_t *self, struct cloc loc, dict_t *context,
     st->netlink=find_cl_if(dict,"link",CL_NETLINK,True,"site",loc);
 
     list_t *comms_cfg=dict_lookup(dict,"comm");
-    if (!comms_cfg) cfgfatal(loc,"site","closure list \"comm\" not found");
+    if (!comms_cfg) cfgfatal(loc,"site","closure list \"comm\" not found\n");
     st->ncomms=list_length(comms_cfg);
     st->comms=safe_malloc_ary(sizeof(*st->comms),st->ncomms,"comms");
     assert(st->ncomms);
     for (i=0; i<st->ncomms; i++) {
 	item_t *item=list_elem(comms_cfg,i);
-	if (item->type!=t_closure) cfgfatal(loc,"site","comm is not a closure");
+	if (item->type!=t_closure)
+	    cfgfatal(loc,"site","comm is not a closure\n");
 	closure_t *cl=item->data.closure;
-	if (cl->type!=CL_COMM) cfgfatal(loc,"site","comm closure wrong type");
+	if (cl->type!=CL_COMM) cfgfatal(loc,"site","comm closure wrong type\n");
 	st->comms[i]=cl->interface;
     }
 
@@ -1424,6 +1462,9 @@ static list_t *site_apply(closure_t *self, struct cloc loc, dict_t *context,
 
     buffer_new(&st->buffer,SETUP_BUFFER_LEN);
 
+    buffer_new(&st->scratch,0);
+    BUF_ALLOC(&st->scratch,"site:scratch");
+
     /* We are interested in poll(), but only for timeouts. We don't have
        any fds of our own. */
     register_for_poll(st, site_beforepoll, site_afterpoll, 0, "site");
@@ -1602,7 +1643,7 @@ static void transport_peers_copy(struct site *st, transport_peers *dst,
     dst->npeers=src->npeers;
     memcpy(dst->peers, src->peers, sizeof(*dst->peers) * dst->npeers);
     transport_peers_debug(st,dst,"copy",
-			  src->npeers, &src->peers->addr, sizeof(src->peers));
+			  src->npeers, &src->peers->addr, sizeof(*src->peers));
 }
 
 void transport_xmit(struct site *st, transport_peers *peers,