[PATCH 6.1.y] ksmbd: add max ip connections parameter

[Sasha Levin <sashal@kernel.org>]

From: Namjae Jeon <linkinjeon@kernel.org>

[ Upstream commit d8b6dc9256762293048bf122fc11c4e612d0ef5d ]

This parameter set the maximum number of connections per ip address.
The default is 8.

Cc: stable@vger.kernel.org
Fixes: c0d41112f1a5 ("ksmbd: extend the connection limiting mechanism to support IPv6")
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
[ adjust reserved room ]
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/smb/server/ksmbd_netlink.h |  5 +++--
 fs/smb/server/server.h        |  1 +
 fs/smb/server/transport_ipc.c |  3 +++
 fs/smb/server/transport_tcp.c | 27 ++++++++++++++++-----------
 4 files changed, 23 insertions(+), 13 deletions(-)

diff --git a/fs/smb/server/ksmbd_netlink.h b/fs/smb/server/ksmbd_netlink.h
index 4464a62228cf3..d3c0b985eb8c1 100644
--- a/fs/smb/server/ksmbd_netlink.h
+++ b/fs/smb/server/ksmbd_netlink.h
@@ -107,10 +107,11 @@ struct ksmbd_startup_request {
 	__u32	smb2_max_credits;	/* MAX credits */
 	__u32	smbd_max_io_size;	/* smbd read write size */
 	__u32	max_connections;	/* Number of maximum simultaneous connections */
-	__u32	reserved[126];		/* Reserved room */
+	__u32	max_ip_connections;	/* Number of maximum connection per ip address */
+	__u32	reserved[125];		/* Reserved room */
 	__u32	ifc_list_sz;		/* interfaces list size */
 	__s8	____payload[];
-};
+} __packed;
 
 #define KSMBD_STARTUP_CONFIG_INTERFACES(s)	((s)->____payload)
 
diff --git a/fs/smb/server/server.h b/fs/smb/server/server.h
index db72781817603..2cb1b855a39e2 100644
--- a/fs/smb/server/server.h
+++ b/fs/smb/server/server.h
@@ -42,6 +42,7 @@ struct ksmbd_server_config {
 	struct smb_sid		domain_sid;
 	unsigned int		auth_mechs;
 	unsigned int		max_connections;
+	unsigned int		max_ip_connections;
 
 	char			*conf[SERVER_CONF_WORK_GROUP + 1];
 };
diff --git a/fs/smb/server/transport_ipc.c b/fs/smb/server/transport_ipc.c
index 7fc4b33b89e36..3ca820d0b8d62 100644
--- a/fs/smb/server/transport_ipc.c
+++ b/fs/smb/server/transport_ipc.c
@@ -318,6 +318,9 @@ static int ipc_server_config_on_startup(struct ksmbd_startup_request *req)
 	if (req->max_connections)
 		server_conf.max_connections = req->max_connections;
 
+	if (req->max_ip_connections)
+		server_conf.max_ip_connections = req->max_ip_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/smb/server/transport_tcp.c b/fs/smb/server/transport_tcp.c
index a4e7d1a5d64d7..4ef032e737f37 100644
--- a/fs/smb/server/transport_tcp.c
+++ b/fs/smb/server/transport_tcp.c
@@ -236,6 +236,7 @@ static int ksmbd_kthread_fn(void *p)
 	struct interface *iface = (struct interface *)p;
 	struct ksmbd_conn *conn;
 	int ret;
+	unsigned int max_ip_conns;
 
 	while (!kthread_should_stop()) {
 		mutex_lock(&iface->sock_release_lock);
@@ -253,34 +254,38 @@ static int ksmbd_kthread_fn(void *p)
 			continue;
 		}
 
+		if (!server_conf.max_ip_connections)
+			goto skip_max_ip_conns_limit;
+
 		/*
 		 * Limits repeated connections from clients with the same IP.
 		 */
+		max_ip_conns = 0;
 		down_read(&conn_list_lock);
-		list_for_each_entry(conn, &conn_list, conns_list)
+		list_for_each_entry(conn, &conn_list, conns_list) {
 #if IS_ENABLED(CONFIG_IPV6)
 			if (client_sk->sk->sk_family == AF_INET6) {
 				if (memcmp(&client_sk->sk->sk_v6_daddr,
-					   &conn->inet6_addr, 16) == 0) {
-					ret = -EAGAIN;
-					break;
-				}
+					   &conn->inet6_addr, 16) == 0)
+					max_ip_conns++;
 			} else if (inet_sk(client_sk->sk)->inet_daddr ==
-				 conn->inet_addr) {
-				ret = -EAGAIN;
-				break;
-			}
+				 conn->inet_addr)
+				max_ip_conns++;
 #else
 			if (inet_sk(client_sk->sk)->inet_daddr ==
-			    conn->inet_addr) {
+			    conn->inet_addr)
+				max_ip_conns++;
+#endif
+			if (server_conf.max_ip_connections <= max_ip_conns) {
 				ret = -EAGAIN;
 				break;
 			}
-#endif
+		}
 		up_read(&conn_list_lock);
 		if (ret == -EAGAIN)
 			continue;
 
+skip_max_ip_conns_limit:
 		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",
-- 
2.51.0