ksmbd: limit repeated connections from clients with the same IP

commit e6bb9193974059ddbb0ce7763fa3882bd60d4dc3 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/smb/server/connection.h b/fs/smb/server/connection.h
index 47e6a8694c0fc1fea45aa9a18fbdb8f40875cb76..c769fe3859b37e1b322f6f17998853b84192458e 100644 (file)
--- a/fs/smb/server/connection.h
+++ b/fs/smb/server/connection.h
@@ -45,6 +45,7 @@ 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 64941a49438f370ead555e977dbff1d6ab4ee809..e86bc4a460687ad87d783da6eb1c1d6b306be464 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",