sctp: enable udp tunneling socks

This patch is to enable udp tunneling socks by calling
sctp_udp_sock_start() in sctp_ctrlsock_init(), and
sctp_udp_sock_stop() in sctp_ctrlsock_exit().

Also add sysctl udp_port to allow changing the listening
sock's port by users.

Wit this patch, the whole sctp over udp feature can be
enabled and used.

v1->v2:
  - Also update ctl_sock udp_port in proc_sctp_do_udp_port()
    where netns udp_port gets changed.
v2->v3:
  - Call htons() when setting sk udp_port from netns udp_port.
v3->v4:
  - Not call sctp_udp_sock_start() when new_value is 0.
  - Add udp_port entry in ip-sysctl.rst.
v4->v5:
  - Not call sctp_udp_sock_start/stop() in sctp_ctrlsock_init/exit().
  - Improve the description of udp_port in ip-sysctl.rst.

Signed-off-by: Xin Long <lucien.xin@gmail.com>
Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/Documentation/networking/ip-sysctl.rst b/Documentation/networking/ip-sysctl.rst
index dad3ba9..2aaf40b 100644 (file)
--- a/Documentation/networking/ip-sysctl.rst
+++ b/Documentation/networking/ip-sysctl.rst
@@ -2642,6 +2642,21 @@ addr_scope_policy - INTEGER
 
        Default: 1
 
+udp_port - INTEGER
+       The listening port for the local UDP tunneling sock. Normally it's
+       using the IANA-assigned UDP port number 9899 (sctp-tunneling).
+
+       This UDP sock is used for processing the incoming UDP-encapsulated
+       SCTP packets (from RFC6951), and shared by all applications in the
+       same net namespace. This UDP sock will be closed when the value is
+       set to 0.
+
+       The value will also be used to set the src port of the UDP header
+       for the outgoing UDP-encapsulated SCTP packets. For the dest port,
+       please refer to 'encap_port' below.
+
+       Default: 0
+
 encap_port - INTEGER
        The default remote UDP encapsulation port.
 

diff --git a/net/sctp/sysctl.c b/net/sctp/sysctl.c
index ecc1b5e..e92df77 100644 (file)
--- a/net/sctp/sysctl.c
+++ b/net/sctp/sysctl.c
@@ -49,6 +49,8 @@ static int proc_sctp_do_rto_min(struct ctl_table *ctl, int write,
                                void *buffer, size_t *lenp, loff_t *ppos);
 static int proc_sctp_do_rto_max(struct ctl_table *ctl, int write, void *buffer,
                                size_t *lenp, loff_t *ppos);
+static int proc_sctp_do_udp_port(struct ctl_table *ctl, int write, void *buffer,
+                                size_t *lenp, loff_t *ppos);
 static int proc_sctp_do_alpha_beta(struct ctl_table *ctl, int write,
                                   void *buffer, size_t *lenp, loff_t *ppos);
 static int proc_sctp_do_auth(struct ctl_table *ctl, int write,
@@ -292,6 +294,15 @@ static struct ctl_table sctp_net_table[] = {
                .proc_handler   = proc_dointvec,
        },
        {
+               .procname       = "udp_port",
+               .data           = &init_net.sctp.udp_port,
+               .maxlen         = sizeof(int),
+               .mode           = 0644,
+               .proc_handler   = proc_sctp_do_udp_port,
+               .extra1         = SYSCTL_ZERO,
+               .extra2         = &udp_port_max,
+       },
+       {
                .procname       = "encap_port",
                .data           = &init_net.sctp.encap_port,
                .maxlen         = sizeof(int),
@@ -487,6 +498,47 @@ static int proc_sctp_do_auth(struct ctl_table *ctl, int write,
        return ret;
 }
 
+static int proc_sctp_do_udp_port(struct ctl_table *ctl, int write,
+                                void *buffer, size_t *lenp, loff_t *ppos)
+{
+       struct net *net = current->nsproxy->net_ns;
+       unsigned int min = *(unsigned int *)ctl->extra1;
+       unsigned int max = *(unsigned int *)ctl->extra2;
+       struct ctl_table tbl;
+       int ret, new_value;
+
+       memset(&tbl, 0, sizeof(struct ctl_table));
+       tbl.maxlen = sizeof(unsigned int);
+
+       if (write)
+               tbl.data = &new_value;
+       else
+               tbl.data = &net->sctp.udp_port;
+
+       ret = proc_dointvec(&tbl, write, buffer, lenp, ppos);
+       if (write && ret == 0) {
+               struct sock *sk = net->sctp.ctl_sock;
+
+               if (new_value > max || new_value < min)
+                       return -EINVAL;
+
+               net->sctp.udp_port = new_value;
+               sctp_udp_sock_stop(net);
+               if (new_value) {
+                       ret = sctp_udp_sock_start(net);
+                       if (ret)
+                               net->sctp.udp_port = 0;
+               }
+
+               /* Update the value in the control socket */
+               lock_sock(sk);
+               sctp_sk(sk)->udp_port = htons(net->sctp.udp_port);
+               release_sock(sk);
+       }
+
+       return ret;
+}
+
 int sctp_sysctl_net_register(struct net *net)
 {
        struct ctl_table *table;