From: Petr Štetiar <ynezz@true.cz>
Date: Thu, 19 Dec 2019 10:25:56 +0000 (+0100)
Subject: fix blob parsing vulnerability by using blob_parse_untrusted
X-Git-Url: http://git.cdn.openwrt.org/?a=commitdiff_plain;h=a1523d76b016ed46501f61e38ad38999d6c66f52;p=project%2Fubus.git

fix blob parsing vulnerability by using blob_parse_untrusted

blob_parse expects blobs from trusted inputs, but it can be supplied
with possibly malicious blobs from untrusted inputs as well, which might
lead to undefined behaviour and/or crash of ubus daemon. In order to
prevent such conditions, switch to blob_parse_untrusted which should
hopefully handle such untrusted inputs appropriately.

Signed-off-by: Petr Štetiar <ynezz@true.cz>
---

diff --git a/cli.c b/cli.c
index 421f244..f566279 100644
--- a/cli.c
+++ b/cli.c
@@ -472,7 +472,7 @@ ubus_cli_monitor_cb(struct ubus_context *ctx, uint32_t seq, struct blob_attr *ms
 	bool send;
 	char *data;
 
-	blob_parse(msg, tb, policy, UBUS_MONITOR_MAX);
+	blob_parse_untrusted(msg, blob_raw_len(msg), tb, policy, UBUS_MONITOR_MAX);
 
 	if (!tb[UBUS_MONITOR_CLIENT] ||
 	    !tb[UBUS_MONITOR_PEER] ||
diff --git a/libubus-internal.h b/libubus-internal.h
index 8cf99b3..24477a0 100644
--- a/libubus-internal.h
+++ b/libubus-internal.h
@@ -17,7 +17,7 @@
 extern struct blob_buf b;
 extern const struct ubus_method watch_method;
 
-struct blob_attr **ubus_parse_msg(struct blob_attr *msg);
+struct blob_attr **ubus_parse_msg(struct blob_attr *msg, size_t len);
 bool ubus_validate_hdr(struct ubus_msghdr *hdr);
 void ubus_handle_data(struct uloop_fd *u, unsigned int events);
 int ubus_send_msg(struct ubus_context *ctx, uint32_t seq,
diff --git a/libubus-io.c b/libubus-io.c
index 81c1cd1..ba1016d 100644
--- a/libubus-io.c
+++ b/libubus-io.c
@@ -43,9 +43,9 @@ static const struct blob_attr_info ubus_policy[UBUS_ATTR_MAX] = {
 
 static struct blob_attr *attrbuf[UBUS_ATTR_MAX];
 
-__hidden struct blob_attr **ubus_parse_msg(struct blob_attr *msg)
+__hidden struct blob_attr **ubus_parse_msg(struct blob_attr *msg, size_t len)
 {
-	blob_parse(msg, attrbuf, ubus_policy, UBUS_ATTR_MAX);
+	blob_parse_untrusted(msg, len, attrbuf, ubus_policy, UBUS_ATTR_MAX);
 	return attrbuf;
 }
 
diff --git a/libubus-obj.c b/libubus-obj.c
index 2580b24..29cbb2b 100644
--- a/libubus-obj.c
+++ b/libubus-obj.c
@@ -121,7 +121,7 @@ void __hidden ubus_process_obj_msg(struct ubus_context *ctx, struct ubus_msghdr_
 	struct ubus_object *obj;
 	uint32_t objid;
 	void *prev_data = NULL;
-	attrbuf = ubus_parse_msg(buf->data);
+	attrbuf = ubus_parse_msg(buf->data, blob_raw_len(buf->data));
 	if (!attrbuf[UBUS_ATTR_OBJID])
 		return;
 
@@ -160,7 +160,7 @@ void __hidden ubus_process_obj_msg(struct ubus_context *ctx, struct ubus_msghdr_
 static void ubus_add_object_cb(struct ubus_request *req, int type, struct blob_attr *msg)
 {
 	struct ubus_object *obj = req->priv;
-	struct blob_attr **attrbuf = ubus_parse_msg(msg);
+	struct blob_attr **attrbuf = ubus_parse_msg(msg, blob_raw_len(msg));
 
 	if (!attrbuf[UBUS_ATTR_OBJID])
 		return;
@@ -240,7 +240,7 @@ int ubus_add_object(struct ubus_context *ctx, struct ubus_object *obj)
 static void ubus_remove_object_cb(struct ubus_request *req, int type, struct blob_attr *msg)
 {
 	struct ubus_object *obj = req->priv;
-	struct blob_attr **attrbuf = ubus_parse_msg(msg);
+	struct blob_attr **attrbuf = ubus_parse_msg(msg, blob_raw_len(msg));
 
 	if (!attrbuf[UBUS_ATTR_OBJID])
 		return;
diff --git a/libubus-req.c b/libubus-req.c
index fd9a548..ae9d192 100644
--- a/libubus-req.c
+++ b/libubus-req.c
@@ -31,7 +31,7 @@ static void req_data_cb(struct ubus_request *req, int type, struct blob_attr *da
 	if (!req->data_cb)
 		return;
 
-	attr = ubus_parse_msg(data);
+	attr = ubus_parse_msg(data, blob_raw_len(data));
 	if (!attr[UBUS_ATTR_DATA])
 		return;
 
@@ -328,7 +328,7 @@ int ubus_notify(struct ubus_context *ctx, struct ubus_object *obj,
 
 static bool ubus_get_status(struct ubus_msghdr_buf *buf, int *ret)
 {
-	struct blob_attr **attrbuf = ubus_parse_msg(buf->data);
+	struct blob_attr **attrbuf = ubus_parse_msg(buf->data, blob_raw_len(buf->data));
 
 	if (!attrbuf[UBUS_ATTR_STATUS])
 		return false;
@@ -435,7 +435,7 @@ static void ubus_process_notify_status(struct ubus_request *req, int id, struct
 
 	if (!id) {
 		/* first id: ubusd's status message with a list of ids */
-		tb = ubus_parse_msg(buf->data);
+		tb = ubus_parse_msg(buf->data, blob_raw_len(buf->data));
 		if (tb[UBUS_ATTR_SUBSCRIBERS]) {
 			blob_for_each_attr(cur, tb[UBUS_ATTR_SUBSCRIBERS], rem) {
 				if (!blob_check_type(blob_data(cur), blob_len(cur), BLOB_ATTR_INT32))
diff --git a/libubus.c b/libubus.c
index b405891..91f317c 100644
--- a/libubus.c
+++ b/libubus.c
@@ -139,7 +139,7 @@ static void ubus_lookup_cb(struct ubus_request *ureq, int type, struct blob_attr
 	struct blob_attr **attr;
 
 	req = container_of(ureq, struct ubus_lookup_request, req);
-	attr = ubus_parse_msg(msg);
+	attr = ubus_parse_msg(msg, blob_raw_len(msg));
 
 	if (!attr[UBUS_ATTR_OBJID] || !attr[UBUS_ATTR_OBJPATH] ||
 	    !attr[UBUS_ATTR_OBJTYPE])
@@ -175,7 +175,7 @@ static void ubus_lookup_id_cb(struct ubus_request *req, int type, struct blob_at
 	struct blob_attr **attr;
 	uint32_t *id = req->priv;
 
-	attr = ubus_parse_msg(msg);
+	attr = ubus_parse_msg(msg, blob_raw_len(msg));
 
 	if (!attr[UBUS_ATTR_OBJID])
 		return;
diff --git a/tests/fuzz/test-fuzz.c b/tests/fuzz/test-fuzz.c
index 9922ff9..7a7a1eb 100644
--- a/tests/fuzz/test-fuzz.c
+++ b/tests/fuzz/test-fuzz.c
@@ -28,7 +28,7 @@ static void _ubus_parse_msg(const uint8_t *data, size_t size)
 	if (blob_pad_len(attr) > UBUS_MAX_MSGLEN)
 		return;
 
-	ubus_parse_msg(attr);
+	ubus_parse_msg(attr, size);
 }
 
 int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size)
diff --git a/ubusd.h b/ubusd.h
index 867cde9..923e43d 100644
--- a/ubusd.h
+++ b/ubusd.h
@@ -72,7 +72,7 @@ struct ubus_msg_buf *ubus_msg_new(void *data, int len, bool shared);
 void ubus_msg_send(struct ubus_client *cl, struct ubus_msg_buf *ub);
 ssize_t ubus_msg_writev(int fd, struct ubus_msg_buf *ub, size_t offset);
 void ubus_msg_free(struct ubus_msg_buf *ub);
-struct blob_attr **ubus_parse_msg(struct blob_attr *msg);
+struct blob_attr **ubus_parse_msg(struct blob_attr *msg, size_t len);
 
 struct ubus_client *ubusd_proto_new_client(int fd, uloop_fd_handler cb);
 void ubusd_proto_receive_message(struct ubus_client *cl, struct ubus_msg_buf *ub);
diff --git a/ubusd_acl.c b/ubusd_acl.c
index f19df9a..e426a4a 100644
--- a/ubusd_acl.c
+++ b/ubusd_acl.c
@@ -549,7 +549,7 @@ static int ubusd_reply_query(struct ubus_client *cl, struct ubus_msg_buf *ub, st
 static int ubusd_acl_recv(struct ubus_client *cl, struct ubus_msg_buf *ub, const char *method, struct blob_attr *msg)
 {
 	if (!strcmp(method, "query"))
-		return ubusd_reply_query(cl, ub, ubus_parse_msg(ub->data), msg);
+		return ubusd_reply_query(cl, ub, ubus_parse_msg(ub->data, blob_raw_len(ub->data)), msg);
 
 	return UBUS_STATUS_INVALID_COMMAND;
 }
diff --git a/ubusd_proto.c b/ubusd_proto.c
index 4dd89dd..4746605 100644
--- a/ubusd_proto.c
+++ b/ubusd_proto.c
@@ -34,9 +34,9 @@ static const struct blob_attr_info ubus_policy[UBUS_ATTR_MAX] = {
 	[UBUS_ATTR_GROUP] = { .type = BLOB_ATTR_STRING },
 };
 
-struct blob_attr **ubus_parse_msg(struct blob_attr *msg)
+struct blob_attr **ubus_parse_msg(struct blob_attr *msg, size_t len)
 {
-	blob_parse(msg, attrbuf, ubus_policy, UBUS_ATTR_MAX);
+	blob_parse_untrusted(msg, len, attrbuf, ubus_policy, UBUS_ATTR_MAX);
 	return attrbuf;
 }
 
@@ -454,7 +454,7 @@ void ubusd_proto_receive_message(struct ubus_client *cl, struct ubus_msg_buf *ub
 	/* Note: no callback should free the `ub` buffer
 	         that's always done right after the callback finishes */
 	if (cb)
-		ret = cb(cl, ub, ubus_parse_msg(ub->data));
+		ret = cb(cl, ub, ubus_parse_msg(ub->data, blob_raw_len(ub->data)));
 	else
 		ret = UBUS_STATUS_INVALID_COMMAND;