[Spice-devel] [PATCH vd_agent_linux 02/10] Avoids unchecked file transfer IDs allocation and usage
Frediano Ziglio
fziglio at redhat.com
Tue Nov 3 09:48:26 UTC 2020
From: Frediano Ziglio <freddy77 at gmail.com>
Avoid agents allocating file transfers.
The "active_xfers" entries are now inserted when client start sending
files.
Also different agents cannot mess with other agent transfers as a
transfer is bound to a single agent.
This issue was reported by SUSE security team.
Signed-off-by: Frediano Ziglio <fziglio at redhat.com>
Acked-by: Uri Lublin <uril at redhat.com>
---
src/vdagentd/vdagentd.c | 28 ++++++++++++++++++++++------
1 file changed, 22 insertions(+), 6 deletions(-)
diff --git a/src/vdagentd/vdagentd.c b/src/vdagentd/vdagentd.c
index a2b74bb..f15989d 100644
--- a/src/vdagentd/vdagentd.c
+++ b/src/vdagentd/vdagentd.c
@@ -381,9 +381,11 @@ static void do_client_file_xfer(VirtioPort *vport,
s->id, VD_AGENT_FILE_XFER_STATUS_SESSION_LOCKED, NULL, 0);
return;
}
- udscs_write(active_session_conn, VDAGENTD_FILE_XFER_START, 0, 0,
- data, message_header->size);
- return;
+ msg_type = VDAGENTD_FILE_XFER_START;
+ id = s->id;
+ // associate the id with the active connection
+ g_hash_table_insert(active_xfers, GUINT_TO_POINTER(id), active_session_conn);
+ break;
}
case VD_AGENT_FILE_XFER_STATUS: {
VDAgentFileXferStatusMessage *s = (VDAgentFileXferStatusMessage *)data;
@@ -408,6 +410,12 @@ static void do_client_file_xfer(VirtioPort *vport,
return;
}
udscs_write(conn, msg_type, 0, 0, data, message_header->size);
+
+ // client told that transfer is ended, agents too stop the transfer
+ // and release resources
+ if (message_header->type == VD_AGENT_FILE_XFER_STATUS) {
+ g_hash_table_remove(active_xfers, GUINT_TO_POINTER(id));
+ }
}
static void forward_data_to_session_agent(uint32_t type, uint8_t *data, size_t size)
@@ -1012,6 +1020,15 @@ static void do_agent_file_xfer_status(UdscsConnection *conn,
const gchar *log_msg = NULL;
guint data_size = 0;
+ UdscsConnection *task_conn = g_hash_table_lookup(active_xfers, task_id);
+ if (task_conn == NULL || task_conn != conn) {
+ // Protect against misbehaving agent.
+ // Ignore the message, but do not disconnect the agent, to protect against
+ // a misbehaving client that tries to disconnect a good agent
+ // e.g. by sending a new task and immediately cancelling it.
+ return;
+ }
+
/* header->arg1 = file xfer task id, header->arg2 = file xfer status */
switch (header->arg2) {
case VD_AGENT_FILE_XFER_STATUS_NOT_ENOUGH_SPACE:
@@ -1026,10 +1043,9 @@ static void do_agent_file_xfer_status(UdscsConnection *conn,
send_file_xfer_status(virtio_port, log_msg, header->arg1, header->arg2,
data, data_size);
- if (header->arg2 == VD_AGENT_FILE_XFER_STATUS_CAN_SEND_DATA)
- g_hash_table_insert(active_xfers, task_id, conn);
- else
+ if (header->arg2 != VD_AGENT_FILE_XFER_STATUS_CAN_SEND_DATA) {
g_hash_table_remove(active_xfers, task_id);
+ }
}
static void agent_read_complete(UdscsConnection *conn,
--
2.26.2
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