ksmbd: limit repeated connections from clients with the same IP

Repeated connections from clients with the same IP address may exhaust
the max connections and prevent other normal client connections.
This patch limit repeated connections from clients with the same IP.

Reported-by: tianshuo han <hantianshuo233@gmail.com>
Cc: stable@vger.kernel.org
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>

diff --git a/fs/smb/server/connection.h b/fs/smb/server/connection.h
index dd3e0e3..31dd1ca 100644 (file)
--- a/fs/smb/server/connection.h
+++ b/fs/smb/server/connection.h
@@ -46,6 +46,7 @@ struct ksmbd_conn {
        struct mutex                    srv_mutex;
        int                             status;
        unsigned int                    cli_cap;
+       __be32                          inet_addr;
        char                            *request_buf;
        struct ksmbd_transport          *transport;
        struct nls_table                *local_nls;

diff --git a/fs/smb/server/transport_tcp.c b/fs/smb/server/transport_tcp.c
index 4e9f98d..d72588f 100644 (file)
--- a/fs/smb/server/transport_tcp.c
+++ b/fs/smb/server/transport_tcp.c
@@ -87,6 +87,7 @@ static struct tcp_transport *alloc_transport(struct socket *client_sk)
                return NULL;
        }
 
+       conn->inet_addr = inet_sk(client_sk->sk)->inet_daddr;
        conn->transport = KSMBD_TRANS(t);
        KSMBD_TRANS(t)->conn = conn;
        KSMBD_TRANS(t)->ops = &ksmbd_tcp_transport_ops;
@@ -230,6 +231,8 @@ static int ksmbd_kthread_fn(void *p)
 {
        struct socket *client_sk = NULL;
        struct interface *iface = (struct interface *)p;
+       struct inet_sock *csk_inet;
+       struct ksmbd_conn *conn;
        int ret;
 
        while (!kthread_should_stop()) {
@@ -248,6 +251,20 @@ static int ksmbd_kthread_fn(void *p)
                        continue;
                }
 
+               /*
+                * Limits repeated connections from clients with the same IP.
+                */
+               csk_inet = inet_sk(client_sk->sk);
+               down_read(&conn_list_lock);
+               list_for_each_entry(conn, &conn_list, conns_list)
+                       if (csk_inet->inet_daddr == conn->inet_addr) {
+                               ret = -EAGAIN;
+                               break;
+                       }
+               up_read(&conn_list_lock);
+               if (ret == -EAGAIN)
+                       continue;
+
                if (server_conf.max_connections &&
                    atomic_inc_return(&active_num_conn) >= server_conf.max_connections) {
                        pr_info_ratelimited("Limit the maximum number of connections(%u)\n",