ksmbd: add max connections parameter

commit 0d0d4680db22eda1eea785c47bbf66a9b33a8b16 upstream.

Add max connections parameter to limit number of maximum simultaneous
connections.

Fixes: 0626e6641f6b ("cifsd: add server handler for central processing and tranport layers")
Cc: stable@vger.kernel.org
Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.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/ksmbd/ksmbd_netlink.h b/fs/ksmbd/ksmbd_netlink.h
index ff07c67..ce866ff 100644 (file)
--- a/fs/ksmbd/ksmbd_netlink.h
+++ b/fs/ksmbd/ksmbd_netlink.h
@@ -105,7 +105,8 @@ struct ksmbd_startup_request {
        __u32   sub_auth[3];            /* Subauth value for Security ID */
        __u32   smb2_max_credits;       /* MAX credits */
        __u32   smbd_max_io_size;       /* smbd read write size */
-       __u32   reserved[127];          /* Reserved room */
+       __u32   max_connections;        /* Number of maximum simultaneous connections */
+       __u32   reserved[126];          /* Reserved room */
        __u32   ifc_list_sz;            /* interfaces list size */
        __s8    ____payload[];
 };

diff --git a/fs/ksmbd/server.h b/fs/ksmbd/server.h
index ac9d932..db72781 100644 (file)
--- a/fs/ksmbd/server.h
+++ b/fs/ksmbd/server.h
@@ -41,6 +41,7 @@ struct ksmbd_server_config {
        unsigned int            share_fake_fscaps;
        struct smb_sid          domain_sid;
        unsigned int            auth_mechs;
+       unsigned int            max_connections;
 
        char                    *conf[SERVER_CONF_WORK_GROUP + 1];
 };

diff --git a/fs/ksmbd/transport_ipc.c b/fs/ksmbd/transport_ipc.c
index c9aca21..40c721f 100644 (file)
--- a/fs/ksmbd/transport_ipc.c
+++ b/fs/ksmbd/transport_ipc.c
@@ -308,6 +308,9 @@ static int ipc_server_config_on_startup(struct ksmbd_startup_request *req)
        if (req->smbd_max_io_size)
                init_smbd_max_io_size(req->smbd_max_io_size);
 
+       if (req->max_connections)
+               server_conf.max_connections = req->max_connections;
+
        ret = ksmbd_set_netbios_name(req->netbios_name);
        ret |= ksmbd_set_server_string(req->server_string);
        ret |= ksmbd_set_work_group(req->work_group);

diff --git a/fs/ksmbd/transport_tcp.c b/fs/ksmbd/transport_tcp.c
index 4c6bd0b..603893f 100644 (file)
--- a/fs/ksmbd/transport_tcp.c
+++ b/fs/ksmbd/transport_tcp.c
@@ -15,6 +15,8 @@
 #define IFACE_STATE_DOWN               BIT(0)
 #define IFACE_STATE_CONFIGURED         BIT(1)
 
+static atomic_t active_num_conn;
+
 struct interface {
        struct task_struct      *ksmbd_kthread;
        struct socket           *ksmbd_socket;
@@ -185,8 +187,10 @@ static int ksmbd_tcp_new_connection(struct socket *client_sk)
        struct tcp_transport *t;
 
        t = alloc_transport(client_sk);
-       if (!t)
+       if (!t) {
+               sock_release(client_sk);
                return -ENOMEM;
+       }
 
        csin = KSMBD_TCP_PEER_SOCKADDR(KSMBD_TRANS(t)->conn);
        if (kernel_getpeername(client_sk, csin) < 0) {
@@ -239,6 +243,15 @@ static int ksmbd_kthread_fn(void *p)
                        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",
+                                           atomic_read(&active_num_conn));
+                       atomic_dec(&active_num_conn);
+                       sock_release(client_sk);
+                       continue;
+               }
+
                ksmbd_debug(CONN, "connect success: accepted new connection\n");
                client_sk->sk->sk_rcvtimeo = KSMBD_TCP_RECV_TIMEOUT;
                client_sk->sk->sk_sndtimeo = KSMBD_TCP_SEND_TIMEOUT;
@@ -368,6 +381,8 @@ static int ksmbd_tcp_writev(struct ksmbd_transport *t, struct kvec *iov,
 static void ksmbd_tcp_disconnect(struct ksmbd_transport *t)
 {
        free_transport(TCP_TRANS(t));
+       if (server_conf.max_connections)
+               atomic_dec(&active_num_conn);
 }
 
 static void tcp_destroy_socket(struct socket *ksmbd_socket)