From 838c0dc7641e1c991c0f3027bf94bee4606012f8 Mon Sep 17 00:00:00 2001
From: Bernie Conrad <bernie@allthenticate.net>
Date: Tue, 28 Sep 2021 16:00:15 -0700
Subject: gatt: Fix not cleaning up when disconnected
There is a current use after free possible on a gatt server if a client
disconnects while a WriteValue call is being processed with dbus.
This patch includes the addition of a pending disconnect callback to handle
cleanup better if a disconnect occurs during a write, an acquire write
or read operation using bt_att_register_disconnect with the cb.
---
src/gatt-database.c | 128 ++++++++++++++++++++++++++++++----------------------
1 file changed, 74 insertions(+), 54 deletions(-)
--- a/src/gatt-database.c
+++ b/src/gatt-database.c
@@ -141,8 +141,9 @@ struct external_desc {
};
struct pending_op {
- struct btd_device *device;
+ struct bt_att *att;
unsigned int id;
+ unsigned int disconn_id;
uint16_t offset;
uint8_t link_type;
struct gatt_db_attribute *attrib;
@@ -910,6 +911,26 @@ static struct btd_device *att_get_device
return btd_adapter_find_device(adapter, &dst, dst_type);
}
+
+static void pending_op_free(void *data)
+{
+ struct pending_op *op = data;
+
+ if (op->owner_queue)
+ queue_remove(op->owner_queue, op);
+
+ bt_att_unregister_disconnect(op->att, op->disconn_id);
+ bt_att_unref(op->att);
+ free(op);
+}
+
+static void pending_disconnect_cb(int err, void *user_data)
+{
+ struct pending_op *op = user_data;
+
+ op->owner_queue = NULL;
+}
+
static struct pending_op *pending_ccc_new(struct bt_att *att,
struct gatt_db_attribute *attrib,
uint16_t value,
@@ -929,21 +950,16 @@ static struct pending_op *pending_ccc_ne
op->data.iov_base = UINT_TO_PTR(value);
op->data.iov_len = sizeof(value);
- op->device = device;
+ op->att = bt_att_ref(att);
op->attrib = attrib;
op->link_type = link_type;
- return op;
-}
+ bt_att_register_disconnect(att,
+ pending_disconnect_cb,
+ op,
+ NULL);
-static void pending_op_free(void *data)
-{
- struct pending_op *op = data;
-
- if (op->owner_queue)
- queue_remove(op->owner_queue, op);
-
- free(op);
+ return op;
}
static void gatt_ccc_write_cb(struct gatt_db_attribute *attrib,
@@ -2155,31 +2171,35 @@ done:
gatt_db_attribute_read_result(op->attrib, op->id, ecode, value, len);
}
-static struct pending_op *pending_read_new(struct btd_device *device,
+
+static struct pending_op *pending_read_new(struct bt_att *att,
struct queue *owner_queue,
struct gatt_db_attribute *attrib,
- unsigned int id, uint16_t offset,
- uint8_t link_type)
+ unsigned int id, uint16_t offset)
{
struct pending_op *op;
op = new0(struct pending_op, 1);
op->owner_queue = owner_queue;
- op->device = device;
+ op->att = bt_att_ref(att);
op->attrib = attrib;
op->id = id;
op->offset = offset;
- op->link_type = link_type;
+ op->link_type = bt_att_get_link_type(att);
queue_push_tail(owner_queue, op);
+ op->disconn_id = bt_att_register_disconnect(att, pending_disconnect_cb,
+ op, NULL);
+
return op;
}
static void append_options(DBusMessageIter *iter, void *user_data)
{
struct pending_op *op = user_data;
- const char *path = device_get_path(op->device);
+ struct btd_device *device = att_get_device(op->att);
+ const char *path = device_get_path(device);
struct bt_gatt_server *server;
const char *link;
uint16_t mtu;
@@ -2206,7 +2226,7 @@ static void append_options(DBusMessageIt
dict_append_entry(iter, "prepare-authorize", DBUS_TYPE_BOOLEAN,
&op->prep_authorize);
- server = btd_device_get_gatt_server(op->device);
+ server = btd_device_get_gatt_server(device);
mtu = bt_gatt_server_get_mtu(server);
dict_append_entry(iter, "mtu", DBUS_TYPE_UINT16, &mtu);
@@ -2229,18 +2249,16 @@ static void read_setup_cb(DBusMessageIte
dbus_message_iter_close_container(iter, &dict);
}
-static struct pending_op *send_read(struct btd_device *device,
+static struct pending_op *send_read(struct bt_att *att,
struct gatt_db_attribute *attrib,
GDBusProxy *proxy,
struct queue *owner_queue,
unsigned int id,
- uint16_t offset,
- uint8_t link_type)
+ uint16_t offset)
{
struct pending_op *op;
- op = pending_read_new(device, owner_queue, attrib, id, offset,
- link_type);
+ op = pending_read_new(att, owner_queue, attrib, id, offset);
if (g_dbus_proxy_method_call(proxy, "ReadValue", read_setup_cb,
read_reply_cb, op, pending_op_free) == TRUE)
@@ -2323,15 +2341,17 @@ static void write_reply_cb(DBusMessage *
}
done:
- gatt_db_attribute_write_result(op->attrib, op->id, ecode);
+ /* Make sure that only reply if the device is connected */
+ if (!bt_att_get_fd(op->att))
+ gatt_db_attribute_write_result(op->attrib, op->id, ecode);
}
-static struct pending_op *pending_write_new(struct btd_device *device,
+static struct pending_op *pending_write_new(struct bt_att *att,
struct queue *owner_queue,
struct gatt_db_attribute *attrib,
unsigned int id,
const uint8_t *value, size_t len,
- uint16_t offset, uint8_t link_type,
+ uint16_t offset,
bool is_characteristic,
bool prep_authorize)
{
@@ -2342,33 +2362,37 @@ static struct pending_op *pending_write_
op->data.iov_base = (uint8_t *) value;
op->data.iov_len = len;
- op->device = device;
+ op->att = bt_att_ref(att);
op->owner_queue = owner_queue;
op->attrib = attrib;
op->id = id;
op->offset = offset;
- op->link_type = link_type;
+ op->link_type = bt_att_get_link_type(att);
op->is_characteristic = is_characteristic;
op->prep_authorize = prep_authorize;
queue_push_tail(owner_queue, op);
+ bt_att_register_disconnect(att,
+ pending_disconnect_cb,
+ op, NULL);
+
return op;
}
-static struct pending_op *send_write(struct btd_device *device,
+static struct pending_op *send_write(struct bt_att *att,
struct gatt_db_attribute *attrib,
GDBusProxy *proxy,
struct queue *owner_queue,
unsigned int id,
const uint8_t *value, size_t len,
- uint16_t offset, uint8_t link_type,
+ uint16_t offset,
bool is_characteristic,
bool prep_authorize)
{
struct pending_op *op;
- op = pending_write_new(device, owner_queue, attrib, id, value, len,
- offset, link_type, is_characteristic,
+ op = pending_write_new(att, owner_queue, attrib, id, value, len,
+ offset, is_characteristic,
prep_authorize);
if (g_dbus_proxy_method_call(proxy, "WriteValue", write_setup_cb,
@@ -2544,17 +2568,16 @@ static void acquire_write_setup(DBusMess
}
static struct pending_op *acquire_write(struct external_chrc *chrc,
- struct btd_device *device,
+ struct bt_att *att,
struct gatt_db_attribute *attrib,
unsigned int id,
- const uint8_t *value, size_t len,
- uint8_t link_type)
+ const uint8_t *value, size_t len)
{
struct pending_op *op;
bool acquiring = !queue_isempty(chrc->pending_writes);
- op = pending_write_new(device, chrc->pending_writes, attrib, id, value,
- len, 0, link_type, false, false);
+ op = pending_write_new(att, chrc->pending_writes, attrib, id, value,
+ len, 0, false, false);
if (acquiring)
return op;
@@ -2837,8 +2860,8 @@ static void desc_read_cb(struct gatt_db_
goto fail;
}
- if (send_read(device, attrib, desc->proxy, desc->pending_reads, id,
- offset, bt_att_get_link_type(att)))
+ if (send_read(att, attrib, desc->proxy, desc->pending_reads, id,
+ offset))
return;
fail:
@@ -2869,10 +2892,9 @@ static void desc_write_cb(struct gatt_db
if (opcode == BT_ATT_OP_PREP_WRITE_REQ) {
if (!device_is_trusted(device) && !desc->prep_authorized &&
desc->req_prep_authorization)
- send_write(device, attrib, desc->proxy,
+ send_write(att, attrib, desc->proxy,
desc->pending_writes, id, value, len,
- offset, bt_att_get_link_type(att),
- false, true);
+ offset, false, true);
else
gatt_db_attribute_write_result(attrib, id, 0);
@@ -2882,9 +2904,8 @@ static void desc_write_cb(struct gatt_db
if (opcode == BT_ATT_OP_EXEC_WRITE_REQ)
desc->prep_authorized = false;
- if (send_write(device, attrib, desc->proxy, desc->pending_writes, id,
- value, len, offset, bt_att_get_link_type(att), false,
- false))
+ if (send_write(att, attrib, desc->proxy, desc->pending_writes, id,
+ value, len, offset, false, false))
return;
fail:
@@ -2963,8 +2984,8 @@ static void chrc_read_cb(struct gatt_db_
goto fail;
}
- if (send_read(device, attrib, chrc->proxy, chrc->pending_reads, id,
- offset, bt_att_get_link_type(att)))
+ if (send_read(att, attrib, chrc->proxy, chrc->pending_reads, id,
+ offset))
return;
fail:
@@ -3002,9 +3023,9 @@ static void chrc_write_cb(struct gatt_db
if (opcode == BT_ATT_OP_PREP_WRITE_REQ) {
if (!device_is_trusted(device) && !chrc->prep_authorized &&
chrc->req_prep_authorization)
- send_write(device, attrib, chrc->proxy, queue,
+ send_write(att, attrib, chrc->proxy, queue,
id, value, len, offset,
- bt_att_get_link_type(att), true, true);
+ true, true);
else
gatt_db_attribute_write_result(attrib, id, 0);
@@ -3025,13 +3046,12 @@ static void chrc_write_cb(struct gatt_db
}
if (g_dbus_proxy_get_property(chrc->proxy, "WriteAcquired", &iter)) {
- if (acquire_write(chrc, device, attrib, id, value, len,
- bt_att_get_link_type(att)))
+ if (acquire_write(chrc, att, attrib, id, value, len))
return;
}
- if (send_write(device, attrib, chrc->proxy, queue, id, value, len,
- offset, bt_att_get_link_type(att), false, false))
+ if (send_write(att, attrib, chrc->proxy, queue, id, value, len,
+ offset, false, false))
return;
fail:
