[RFC PATCH net-next v2 1/5] gtp: Allow to create GTP device without FDs
From: Wojciech Drewek <wojciech.drewek@intel.com> Currently, when the user wants to create GTP device, he has to provide file handles to the sockets created in userspace (IFLA_GTP_FD0, IFLA_GTP_FD1). This behaviour is not ideal, considering the option of adding support for GTP device creation through ip link. Ip link application is not a good place to create such sockets. This patch allows to create GTP device without providing IFLA_GTP_FD0 and IFLA_GTP_FD1 arguments. If the user does not provide file handles to the sockets, then GTP module takes care of creating UDP sockets by itself. Sockets are created with the commonly known UDP ports used for GTP protocol (GTP0_PORT and GTP1U_PORT). In this case we don't have to provide encap_destroy because no extra deinitialization is needed, everything is covered by udp_tunnel_sock_release. Signed-off-by: Wojciech Drewek <wojciech.drewek@intel.com> --- drivers/net/gtp.c | 74 ++++++++++++++++++++++++++++++++++++++++++----- 1 file changed, 67 insertions(+), 7 deletions(-) diff --git a/drivers/net/gtp.c b/drivers/net/gtp.c index 24e5c54d06c1..a2ad0af913cb 100644 --- a/drivers/net/gtp.c +++ b/drivers/net/gtp.c @@ -66,8 +66,10 @@ struct gtp_dev { struct sock *sk0; struct sock *sk1u; + u8 sk_created; struct net_device *dev; + struct net *net; unsigned int role; unsigned int hash_size; @@ -320,8 +322,16 @@ static void gtp_encap_disable_sock(struct sock *sk) static void gtp_encap_disable(struct gtp_dev *gtp) { - gtp_encap_disable_sock(gtp->sk0); - gtp_encap_disable_sock(gtp->sk1u); + if (gtp->sk_created) { + udp_tunnel_sock_release(gtp->sk0->sk_socket); + udp_tunnel_sock_release(gtp->sk1u->sk_socket); + gtp->sk_created = false; + gtp->sk0 = NULL; + gtp->sk1u = NULL; + } else { + gtp_encap_disable_sock(gtp->sk0); + gtp_encap_disable_sock(gtp->sk1u); + } } /* UDP encapsulation receive handler. See net/ipv4/udp.c. @@ -664,9 +674,6 @@ static int gtp_newlink(struct net *src_net, struct net_device *dev, struct gtp_net *gn; int hashsize, err; - if (!data[IFLA_GTP_FD0] && !data[IFLA_GTP_FD1]) - return -EINVAL; - gtp = netdev_priv(dev); if (!data[IFLA_GTP_PDP_HASHSIZE]) { @@ -677,6 +684,8 @@ static int gtp_newlink(struct net *src_net, struct net_device *dev, hashsize = 1024; } + gtp->net = src_net; + err = gtp_hashtable_new(gtp, hashsize); if (err < 0) return err; @@ -844,6 +853,38 @@ static struct sock *gtp_encap_enable_socket(int fd, int type, return sk; } +static struct sock *gtp_encap_create_sock(int type, struct gtp_dev *gtp) +{ + struct udp_tunnel_sock_cfg tuncfg = {}; + struct udp_port_cfg udp_conf = { + .local_ip.s_addr = htonl(INADDR_ANY), + .family = AF_INET, + }; + struct net *net = gtp->net; + struct socket *sock; + int err; + + if (type == UDP_ENCAP_GTP0) + udp_conf.local_udp_port = GTP0_PORT; + else if (type == UDP_ENCAP_GTP1U) + udp_conf.local_udp_port = GTP1U_PORT; + else + return ERR_PTR(-EINVAL); + + err = udp_sock_create(net, &udp_conf, &sock); + if (err) + return ERR_PTR(err); + + tuncfg.sk_user_data = gtp; + tuncfg.encap_type = type; + tuncfg.encap_rcv = gtp_encap_recv; + tuncfg.encap_destroy = NULL; + + setup_udp_tunnel_sock(net, sock, &tuncfg); + + return sock->sk; +} + static int gtp_encap_enable(struct gtp_dev *gtp, struct nlattr *data[]) { struct sock *sk1u = NULL; @@ -868,11 +909,30 @@ static int gtp_encap_enable(struct gtp_dev *gtp, struct nlattr *data[]) } } + if (!data[IFLA_GTP_FD0] && !data[IFLA_GTP_FD1]) { + sk0 = gtp_encap_create_sock(UDP_ENCAP_GTP0, gtp); + if (IS_ERR(sk0)) + return PTR_ERR(sk0); + + sk1u = gtp_encap_create_sock(UDP_ENCAP_GTP1U, gtp); + if (IS_ERR(sk1u)) { + udp_tunnel_sock_release(sk0->sk_socket); + return PTR_ERR(sk1u); + } + gtp->sk_created = true; + } + if (data[IFLA_GTP_ROLE]) { role = nla_get_u32(data[IFLA_GTP_ROLE]); if (role > GTP_ROLE_SGSN) { - gtp_encap_disable_sock(sk0); - gtp_encap_disable_sock(sk1u); + if (gtp->sk_created) { + udp_tunnel_sock_release(sk0->sk_socket); + udp_tunnel_sock_release(sk1u->sk_socket); + gtp->sk_created = false; + } else { + gtp_encap_disable_sock(sk0); + gtp_encap_disable_sock(sk1u); + } return -EINVAL; } } -- 2.31.1
Hi Wojciech, thanks for your contribution, I think in general it is a good idea. However, I do not think this can be merged, as the resulting system would not be possible to use in a spec-compliant way.
Currently, when the user wants to create GTP device, he has to provide file handles to the sockets created in userspace (IFLA_GTP_FD0, IFLA_GTP_FD1). This behaviour is not ideal, considering the option of adding support for GTP device creation through ip link. Ip link application is not a good place to create such sockets.
The GTP kernel module in its past and current form only handles G-PDU packets and not any other packets. So it relies on always having a user space process [the one with the socket you want to make optional to handle other frames, such as GTP ECHO. So if you apply your patch, you will end up creating a GTP-U instance which does not respond to echo requests, which is in violation of 3GPP specs and which will create problems in production. So if you want to make this optional, you'd also have to implement GTP-U ECHO handling in the kernel, and require that in-kernel handling to be enabled when creating a GTP device without the socket file descriptors. Regards, Harald -- - Harald Welte <laforge@gnumonks.org> http://laforge.gnumonks.org/ ============================================================================ "Privacy in residential applications is a desirable marketing option." (ETSI EN 300 175-7 Ch. A6)
Hi Harald, Thanks for the response, I'll take a look on how GTP-U ECHO works and I'll try to implement it. Regards, Wojtek
-----Original Message----- From: Harald Welte <laforge@gnumonks.org> Sent: czwartek, 27 stycznia 2022 15:41 To: Marcin Szycik <marcin.szycik@linux.intel.com> Cc: netdev@vger.kernel.org; michal.swiatkowski@linux.intel.com; Drewek, Wojciech <wojciech.drewek@intel.com>; davem@davemloft.net; kuba@kernel.org; pablo@netfilter.org; osmocom-net-gprs@lists.osmocom.org Subject: Re: [RFC PATCH net-next v2 1/5] gtp: Allow to create GTP device without FDs
Hi Wojciech,
thanks for your contribution, I think in general it is a good idea.
However, I do not think this can be merged, as the resulting system would not be possible to use in a spec-compliant way.
Currently, when the user wants to create GTP device, he has to provide file handles to the sockets created in userspace (IFLA_GTP_FD0, IFLA_GTP_FD1). This behaviour is not ideal, considering the option of adding support for GTP device creation through ip link. Ip link application is not a good place to create such sockets.
The GTP kernel module in its past and current form only handles G-PDU packets and not any other packets. So it relies on always having a user space process [the one with the socket you want to make optional to handle other frames, such as GTP ECHO.
So if you apply your patch, you will end up creating a GTP-U instance which does not respond to echo requests, which is in violation of 3GPP specs and which will create problems in production.
So if you want to make this optional, you'd also have to implement GTP-U ECHO handling in the kernel, and require that in-kernel handling to be enabled when creating a GTP device without the socket file descriptors.
Regards, Harald
-- - Harald Welte <laforge@gnumonks.org> http://laforge.gnumonks.org/ ============================================================================ "Privacy in residential applications is a desirable marketing option." (ETSI EN 300 175-7 Ch. A6)
participants (3)
-
Drewek, Wojciech -
Harald Welte -
Marcin Szycik