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gtp.c
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// SPDX-License-Identifier: GPL-2.0-or-later
/* GTP according to GSM TS 09.60 / 3GPP TS 29.060
*
* (C) 2012-2014 by sysmocom - s.f.m.c. GmbH
* (C) 2016 by Pablo Neira Ayuso <pablo@netfilter.org>
*
* Author: Harald Welte <hwelte@sysmocom.de>
* Pablo Neira Ayuso <pablo@netfilter.org>
* Andreas Schultz <aschultz@travelping.com>
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/udp.h>
#include <linux/rculist.h>
#include <linux/jhash.h>
#include <linux/if_tunnel.h>
#include <linux/net.h>
#include <linux/file.h>
#include <linux/gtp.h>
#include <net/net_namespace.h>
#include <net/protocol.h>
#include <net/ip.h>
#include <net/udp.h>
#include <net/udp_tunnel.h>
#include <net/icmp.h>
#include <net/xfrm.h>
#include <net/genetlink.h>
#include <net/netns/generic.h>
#include <net/gtp.h>
/* An active session for the subscriber. */
struct pdp_ctx {
struct hlist_node hlist_tid;
struct hlist_node hlist_addr;
union {
struct {
u64 tid;
u16 flow;
} v0;
struct {
u32 i_tei;
u32 o_tei;
} v1;
} u;
u8 gtp_version;
u16 af;
struct in_addr ms_addr_ip4;
struct in_addr peer_addr_ip4;
struct sock *sk;
struct net_device *dev;
atomic_t tx_seq;
struct rcu_head rcu_head;
};
/* One instance of the GTP device. */
struct gtp_dev {
struct list_head list;
struct sock *sk0;
struct sock *sk1u;
u8 sk_created;
struct net_device *dev;
struct net *net;
unsigned int role;
unsigned int hash_size;
struct hlist_head *tid_hash;
struct hlist_head *addr_hash;
u8 restart_count;
};
struct echo_info {
struct in_addr ms_addr_ip4;
struct in_addr peer_addr_ip4;
u8 gtp_version;
};
static unsigned int gtp_net_id __read_mostly;
struct gtp_net {
struct list_head gtp_dev_list;
};
static u32 gtp_h_initval;
static struct genl_family gtp_genl_family;
enum gtp_multicast_groups {
GTP_GENL_MCGRP,
};
static const struct genl_multicast_group gtp_genl_mcgrps[] = {
[GTP_GENL_MCGRP] = { .name = GTP_GENL_MCGRP_NAME },
};
static void pdp_context_delete(struct pdp_ctx *pctx);
static inline u32 gtp0_hashfn(u64 tid)
{
u32 *tid32 = (u32 *) &tid;
return jhash_2words(tid32[0], tid32[1], gtp_h_initval);
}
static inline u32 gtp1u_hashfn(u32 tid)
{
return jhash_1word(tid, gtp_h_initval);
}
static inline u32 ipv4_hashfn(__be32 ip)
{
return jhash_1word((__force u32)ip, gtp_h_initval);
}
/* Resolve a PDP context structure based on the 64bit TID. */
static struct pdp_ctx *gtp0_pdp_find(struct gtp_dev *gtp, u64 tid)
{
struct hlist_head *head;
struct pdp_ctx *pdp;
head = >p->tid_hash[gtp0_hashfn(tid) % gtp->hash_size];
hlist_for_each_entry_rcu(pdp, head, hlist_tid) {
if (pdp->gtp_version == GTP_V0 &&
pdp->u.v0.tid == tid)
return pdp;
}
return NULL;
}
/* Resolve a PDP context structure based on the 32bit TEI. */
static struct pdp_ctx *gtp1_pdp_find(struct gtp_dev *gtp, u32 tid)
{
struct hlist_head *head;
struct pdp_ctx *pdp;
head = >p->tid_hash[gtp1u_hashfn(tid) % gtp->hash_size];
hlist_for_each_entry_rcu(pdp, head, hlist_tid) {
if (pdp->gtp_version == GTP_V1 &&
pdp->u.v1.i_tei == tid)
return pdp;
}
return NULL;
}
/* Resolve a PDP context based on IPv4 address of MS. */
static struct pdp_ctx *ipv4_pdp_find(struct gtp_dev *gtp, __be32 ms_addr)
{
struct hlist_head *head;
struct pdp_ctx *pdp;
head = >p->addr_hash[ipv4_hashfn(ms_addr) % gtp->hash_size];
hlist_for_each_entry_rcu(pdp, head, hlist_addr) {
if (pdp->af == AF_INET &&
pdp->ms_addr_ip4.s_addr == ms_addr)
return pdp;
}
return NULL;
}
static bool gtp_check_ms_ipv4(struct sk_buff *skb, struct pdp_ctx *pctx,
unsigned int hdrlen, unsigned int role)
{
struct iphdr *iph;
if (!pskb_may_pull(skb, hdrlen + sizeof(struct iphdr)))
return false;
iph = (struct iphdr *)(skb->data + hdrlen);
if (role == GTP_ROLE_SGSN)
return iph->daddr == pctx->ms_addr_ip4.s_addr;
else
return iph->saddr == pctx->ms_addr_ip4.s_addr;
}
/* Check if the inner IP address in this packet is assigned to any
* existing mobile subscriber.
*/
static bool gtp_check_ms(struct sk_buff *skb, struct pdp_ctx *pctx,
unsigned int hdrlen, unsigned int role)
{
switch (ntohs(skb->protocol)) {
case ETH_P_IP:
return gtp_check_ms_ipv4(skb, pctx, hdrlen, role);
}
return false;
}
static int gtp_rx(struct pdp_ctx *pctx, struct sk_buff *skb,
unsigned int hdrlen, unsigned int role)
{
if (!gtp_check_ms(skb, pctx, hdrlen, role)) {
netdev_dbg(pctx->dev, "No PDP ctx for this MS\n");
return 1;
}
/* Get rid of the GTP + UDP headers. */
if (iptunnel_pull_header(skb, hdrlen, skb->protocol,
!net_eq(sock_net(pctx->sk), dev_net(pctx->dev)))) {
pctx->dev->stats.rx_length_errors++;
goto err;
}
netdev_dbg(pctx->dev, "forwarding packet from GGSN to uplink\n");
/* Now that the UDP and the GTP header have been removed, set up the
* new network header. This is required by the upper layer to
* calculate the transport header.
*/
skb_reset_network_header(skb);
skb_reset_mac_header(skb);
skb->dev = pctx->dev;
dev_sw_netstats_rx_add(pctx->dev, skb->len);
__netif_rx(skb);
return 0;
err:
pctx->dev->stats.rx_dropped++;
return -1;
}
static struct rtable *ip4_route_output_gtp(struct flowi4 *fl4,
const struct sock *sk,
__be32 daddr, __be32 saddr)
{
memset(fl4, 0, sizeof(*fl4));
fl4->flowi4_oif = sk->sk_bound_dev_if;
fl4->daddr = daddr;
fl4->saddr = saddr;
fl4->flowi4_tos = RT_CONN_FLAGS(sk);
fl4->flowi4_proto = sk->sk_protocol;
return ip_route_output_key(sock_net(sk), fl4);
}
/* GSM TS 09.60. 7.3
* In all Path Management messages:
* - TID: is not used and shall be set to 0.
* - Flow Label is not used and shall be set to 0
* In signalling messages:
* - number: this field is not yet used in signalling messages.
* It shall be set to 255 by the sender and shall be ignored
* by the receiver
* Returns true if the echo req was correct, false otherwise.
*/
static bool gtp0_validate_echo_hdr(struct gtp0_header *gtp0)
{
return !(gtp0->tid || (gtp0->flags ^ 0x1e) ||
gtp0->number != 0xff || gtp0->flow);
}
/* msg_type has to be GTP_ECHO_REQ or GTP_ECHO_RSP */
static void gtp0_build_echo_msg(struct gtp0_header *hdr, __u8 msg_type)
{
int len_pkt, len_hdr;
hdr->flags = 0x1e; /* v0, GTP-non-prime. */
hdr->type = msg_type;
/* GSM TS 09.60. 7.3 In all Path Management Flow Label and TID
* are not used and shall be set to 0.
*/
hdr->flow = 0;
hdr->tid = 0;
hdr->number = 0xff;
hdr->spare[0] = 0xff;
hdr->spare[1] = 0xff;
hdr->spare[2] = 0xff;
len_pkt = sizeof(struct gtp0_packet);
len_hdr = sizeof(struct gtp0_header);
if (msg_type == GTP_ECHO_RSP)
hdr->length = htons(len_pkt - len_hdr);
else
hdr->length = 0;
}
static int gtp0_send_echo_resp(struct gtp_dev *gtp, struct sk_buff *skb)
{
struct gtp0_packet *gtp_pkt;
struct gtp0_header *gtp0;
struct rtable *rt;
struct flowi4 fl4;
struct iphdr *iph;
__be16 seq;
gtp0 = (struct gtp0_header *)(skb->data + sizeof(struct udphdr));
if (!gtp0_validate_echo_hdr(gtp0))
return -1;
seq = gtp0->seq;
/* pull GTP and UDP headers */
skb_pull_data(skb, sizeof(struct gtp0_header) + sizeof(struct udphdr));
gtp_pkt = skb_push(skb, sizeof(struct gtp0_packet));
memset(gtp_pkt, 0, sizeof(struct gtp0_packet));
gtp0_build_echo_msg(>p_pkt->gtp0_h, GTP_ECHO_RSP);
/* GSM TS 09.60. 7.3 The Sequence Number in a signalling response
* message shall be copied from the signalling request message
* that the GSN is replying to.
*/
gtp_pkt->gtp0_h.seq = seq;
gtp_pkt->ie.tag = GTPIE_RECOVERY;
gtp_pkt->ie.val = gtp->restart_count;
iph = ip_hdr(skb);
/* find route to the sender,
* src address becomes dst address and vice versa.
*/
rt = ip4_route_output_gtp(&fl4, gtp->sk0, iph->saddr, iph->daddr);
if (IS_ERR(rt)) {
netdev_dbg(gtp->dev, "no route for echo response from %pI4\n",
&iph->saddr);
return -1;
}
udp_tunnel_xmit_skb(rt, gtp->sk0, skb,
fl4.saddr, fl4.daddr,
iph->tos,
ip4_dst_hoplimit(&rt->dst),
0,
htons(GTP0_PORT), htons(GTP0_PORT),
!net_eq(sock_net(gtp->sk1u),
dev_net(gtp->dev)),
false);
return 0;
}
static int gtp_genl_fill_echo(struct sk_buff *skb, u32 snd_portid, u32 snd_seq,
int flags, u32 type, struct echo_info echo)
{
void *genlh;
genlh = genlmsg_put(skb, snd_portid, snd_seq, >p_genl_family, flags,
type);
if (!genlh)
goto failure;
if (nla_put_u32(skb, GTPA_VERSION, echo.gtp_version) ||
nla_put_be32(skb, GTPA_PEER_ADDRESS, echo.peer_addr_ip4.s_addr) ||
nla_put_be32(skb, GTPA_MS_ADDRESS, echo.ms_addr_ip4.s_addr))
goto failure;
genlmsg_end(skb, genlh);
return 0;
failure:
genlmsg_cancel(skb, genlh);
return -EMSGSIZE;
}
static int gtp0_handle_echo_resp(struct gtp_dev *gtp, struct sk_buff *skb)
{
struct gtp0_header *gtp0;
struct echo_info echo;
struct sk_buff *msg;
struct iphdr *iph;
int ret;
gtp0 = (struct gtp0_header *)(skb->data + sizeof(struct udphdr));
if (!gtp0_validate_echo_hdr(gtp0))
return -1;
iph = ip_hdr(skb);
echo.ms_addr_ip4.s_addr = iph->daddr;
echo.peer_addr_ip4.s_addr = iph->saddr;
echo.gtp_version = GTP_V0;
msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_ATOMIC);
if (!msg)
return -ENOMEM;
ret = gtp_genl_fill_echo(msg, 0, 0, 0, GTP_CMD_ECHOREQ, echo);
if (ret < 0) {
nlmsg_free(msg);
return ret;
}
return genlmsg_multicast_netns(>p_genl_family, dev_net(gtp->dev),
msg, 0, GTP_GENL_MCGRP, GFP_ATOMIC);
}
/* 1 means pass up to the stack, -1 means drop and 0 means decapsulated. */
static int gtp0_udp_encap_recv(struct gtp_dev *gtp, struct sk_buff *skb)
{
unsigned int hdrlen = sizeof(struct udphdr) +
sizeof(struct gtp0_header);
struct gtp0_header *gtp0;
struct pdp_ctx *pctx;
if (!pskb_may_pull(skb, hdrlen))
return -1;
gtp0 = (struct gtp0_header *)(skb->data + sizeof(struct udphdr));
if ((gtp0->flags >> 5) != GTP_V0)
return 1;
/* If the sockets were created in kernel, it means that
* there is no daemon running in userspace which would
* handle echo request.
*/
if (gtp0->type == GTP_ECHO_REQ && gtp->sk_created)
return gtp0_send_echo_resp(gtp, skb);
if (gtp0->type == GTP_ECHO_RSP && gtp->sk_created)
return gtp0_handle_echo_resp(gtp, skb);
if (gtp0->type != GTP_TPDU)
return 1;
pctx = gtp0_pdp_find(gtp, be64_to_cpu(gtp0->tid));
if (!pctx) {
netdev_dbg(gtp->dev, "No PDP ctx to decap skb=%p\n", skb);
return 1;
}
return gtp_rx(pctx, skb, hdrlen, gtp->role);
}
/* msg_type has to be GTP_ECHO_REQ or GTP_ECHO_RSP */
static void gtp1u_build_echo_msg(struct gtp1_header_long *hdr, __u8 msg_type)
{
int len_pkt, len_hdr;
/* S flag must be set to 1 */
hdr->flags = 0x32; /* v1, GTP-non-prime. */
hdr->type = msg_type;
/* 3GPP TS 29.281 5.1 - TEID has to be set to 0 */
hdr->tid = 0;
/* seq, npdu and next should be counted to the length of the GTP packet
* that's why szie of gtp1_header should be subtracted,
* not size of gtp1_header_long.
*/
len_hdr = sizeof(struct gtp1_header);
if (msg_type == GTP_ECHO_RSP) {
len_pkt = sizeof(struct gtp1u_packet);
hdr->length = htons(len_pkt - len_hdr);
} else {
/* GTP_ECHO_REQ does not carry GTP Information Element,
* the why gtp1_header_long is used here.
*/
len_pkt = sizeof(struct gtp1_header_long);
hdr->length = htons(len_pkt - len_hdr);
}
}
static int gtp1u_send_echo_resp(struct gtp_dev *gtp, struct sk_buff *skb)
{
struct gtp1_header_long *gtp1u;
struct gtp1u_packet *gtp_pkt;
struct rtable *rt;
struct flowi4 fl4;
struct iphdr *iph;
gtp1u = (struct gtp1_header_long *)(skb->data + sizeof(struct udphdr));
/* 3GPP TS 29.281 5.1 - For the Echo Request, Echo Response,
* Error Indication and Supported Extension Headers Notification
* messages, the S flag shall be set to 1 and TEID shall be set to 0.
*/
if (!(gtp1u->flags & GTP1_F_SEQ) || gtp1u->tid)
return -1;
/* pull GTP and UDP headers */
skb_pull_data(skb,
sizeof(struct gtp1_header_long) + sizeof(struct udphdr));
gtp_pkt = skb_push(skb, sizeof(struct gtp1u_packet));
memset(gtp_pkt, 0, sizeof(struct gtp1u_packet));
gtp1u_build_echo_msg(>p_pkt->gtp1u_h, GTP_ECHO_RSP);
/* 3GPP TS 29.281 7.7.2 - The Restart Counter value in the
* Recovery information element shall not be used, i.e. it shall
* be set to zero by the sender and shall be ignored by the receiver.
* The Recovery information element is mandatory due to backwards
* compatibility reasons.
*/
gtp_pkt->ie.tag = GTPIE_RECOVERY;
gtp_pkt->ie.val = 0;
iph = ip_hdr(skb);
/* find route to the sender,
* src address becomes dst address and vice versa.
*/
rt = ip4_route_output_gtp(&fl4, gtp->sk1u, iph->saddr, iph->daddr);
if (IS_ERR(rt)) {
netdev_dbg(gtp->dev, "no route for echo response from %pI4\n",
&iph->saddr);
return -1;
}
udp_tunnel_xmit_skb(rt, gtp->sk1u, skb,
fl4.saddr, fl4.daddr,
iph->tos,
ip4_dst_hoplimit(&rt->dst),
0,
htons(GTP1U_PORT), htons(GTP1U_PORT),
!net_eq(sock_net(gtp->sk1u),
dev_net(gtp->dev)),
false);
return 0;
}
static int gtp1u_handle_echo_resp(struct gtp_dev *gtp, struct sk_buff *skb)
{
struct gtp1_header_long *gtp1u;
struct echo_info echo;
struct sk_buff *msg;
struct iphdr *iph;
int ret;
gtp1u = (struct gtp1_header_long *)(skb->data + sizeof(struct udphdr));
/* 3GPP TS 29.281 5.1 - For the Echo Request, Echo Response,
* Error Indication and Supported Extension Headers Notification
* messages, the S flag shall be set to 1 and TEID shall be set to 0.
*/
if (!(gtp1u->flags & GTP1_F_SEQ) || gtp1u->tid)
return -1;
iph = ip_hdr(skb);
echo.ms_addr_ip4.s_addr = iph->daddr;
echo.peer_addr_ip4.s_addr = iph->saddr;
echo.gtp_version = GTP_V1;
msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_ATOMIC);
if (!msg)
return -ENOMEM;
ret = gtp_genl_fill_echo(msg, 0, 0, 0, GTP_CMD_ECHOREQ, echo);
if (ret < 0) {
nlmsg_free(msg);
return ret;
}
return genlmsg_multicast_netns(>p_genl_family, dev_net(gtp->dev),
msg, 0, GTP_GENL_MCGRP, GFP_ATOMIC);
}
static int gtp1u_udp_encap_recv(struct gtp_dev *gtp, struct sk_buff *skb)
{
unsigned int hdrlen = sizeof(struct udphdr) +
sizeof(struct gtp1_header);
struct gtp1_header *gtp1;
struct pdp_ctx *pctx;
if (!pskb_may_pull(skb, hdrlen))
return -1;
gtp1 = (struct gtp1_header *)(skb->data + sizeof(struct udphdr));
if ((gtp1->flags >> 5) != GTP_V1)
return 1;
/* If the sockets were created in kernel, it means that
* there is no daemon running in userspace which would
* handle echo request.
*/
if (gtp1->type == GTP_ECHO_REQ && gtp->sk_created)
return gtp1u_send_echo_resp(gtp, skb);
if (gtp1->type == GTP_ECHO_RSP && gtp->sk_created)
return gtp1u_handle_echo_resp(gtp, skb);
if (gtp1->type != GTP_TPDU)
return 1;
/* From 29.060: "This field shall be present if and only if any one or
* more of the S, PN and E flags are set.".
*
* If any of the bit is set, then the remaining ones also have to be
* set.
*/
if (gtp1->flags & GTP1_F_MASK)
hdrlen += 4;
/* Make sure the header is larger enough, including extensions. */
if (!pskb_may_pull(skb, hdrlen))
return -1;
gtp1 = (struct gtp1_header *)(skb->data + sizeof(struct udphdr));
pctx = gtp1_pdp_find(gtp, ntohl(gtp1->tid));
if (!pctx) {
netdev_dbg(gtp->dev, "No PDP ctx to decap skb=%p\n", skb);
return 1;
}
return gtp_rx(pctx, skb, hdrlen, gtp->role);
}
static void __gtp_encap_destroy(struct sock *sk)
{
struct gtp_dev *gtp;
lock_sock(sk);
gtp = sk->sk_user_data;
if (gtp) {
if (gtp->sk0 == sk)
gtp->sk0 = NULL;
else
gtp->sk1u = NULL;
udp_sk(sk)->encap_type = 0;
rcu_assign_sk_user_data(sk, NULL);
release_sock(sk);
sock_put(sk);
return;
}
release_sock(sk);
}
static void gtp_encap_destroy(struct sock *sk)
{
rtnl_lock();
__gtp_encap_destroy(sk);
rtnl_unlock();
}
static void gtp_encap_disable_sock(struct sock *sk)
{
if (!sk)
return;
__gtp_encap_destroy(sk);
}
static void gtp_encap_disable(struct gtp_dev *gtp)
{
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.
* Return codes: 0: success, <0: error, >0: pass up to userspace UDP socket.
*/
static int gtp_encap_recv(struct sock *sk, struct sk_buff *skb)
{
struct gtp_dev *gtp;
int ret = 0;
gtp = rcu_dereference_sk_user_data(sk);
if (!gtp)
return 1;
netdev_dbg(gtp->dev, "encap_recv sk=%p\n", sk);
switch (udp_sk(sk)->encap_type) {
case UDP_ENCAP_GTP0:
netdev_dbg(gtp->dev, "received GTP0 packet\n");
ret = gtp0_udp_encap_recv(gtp, skb);
break;
case UDP_ENCAP_GTP1U:
netdev_dbg(gtp->dev, "received GTP1U packet\n");
ret = gtp1u_udp_encap_recv(gtp, skb);
break;
default:
ret = -1; /* Shouldn't happen. */
}
switch (ret) {
case 1:
netdev_dbg(gtp->dev, "pass up to the process\n");
break;
case 0:
break;
case -1:
netdev_dbg(gtp->dev, "GTP packet has been dropped\n");
kfree_skb(skb);
ret = 0;
break;
}
return ret;
}
static int gtp_dev_init(struct net_device *dev)
{
struct gtp_dev *gtp = netdev_priv(dev);
gtp->dev = dev;
dev->tstats = netdev_alloc_pcpu_stats(struct pcpu_sw_netstats);
if (!dev->tstats)
return -ENOMEM;
return 0;
}
static void gtp_dev_uninit(struct net_device *dev)
{
struct gtp_dev *gtp = netdev_priv(dev);
gtp_encap_disable(gtp);
free_percpu(dev->tstats);
}
static inline void gtp0_push_header(struct sk_buff *skb, struct pdp_ctx *pctx)
{
int payload_len = skb->len;
struct gtp0_header *gtp0;
gtp0 = skb_push(skb, sizeof(*gtp0));
gtp0->flags = 0x1e; /* v0, GTP-non-prime. */
gtp0->type = GTP_TPDU;
gtp0->length = htons(payload_len);
gtp0->seq = htons((atomic_inc_return(&pctx->tx_seq) - 1) % 0xffff);
gtp0->flow = htons(pctx->u.v0.flow);
gtp0->number = 0xff;
gtp0->spare[0] = gtp0->spare[1] = gtp0->spare[2] = 0xff;
gtp0->tid = cpu_to_be64(pctx->u.v0.tid);
}
static inline void gtp1_push_header(struct sk_buff *skb, struct pdp_ctx *pctx)
{
int payload_len = skb->len;
struct gtp1_header *gtp1;
gtp1 = skb_push(skb, sizeof(*gtp1));
/* Bits 8 7 6 5 4 3 2 1
* +--+--+--+--+--+--+--+--+
* |version |PT| 0| E| S|PN|
* +--+--+--+--+--+--+--+--+
* 0 0 1 1 1 0 0 0
*/
gtp1->flags = 0x30; /* v1, GTP-non-prime. */
gtp1->type = GTP_TPDU;
gtp1->length = htons(payload_len);
gtp1->tid = htonl(pctx->u.v1.o_tei);
/* TODO: Support for extension header, sequence number and N-PDU.
* Update the length field if any of them is available.
*/
}
struct gtp_pktinfo {
struct sock *sk;
struct iphdr *iph;
struct flowi4 fl4;
struct rtable *rt;
struct pdp_ctx *pctx;
struct net_device *dev;
__be16 gtph_port;
};
static void gtp_push_header(struct sk_buff *skb, struct gtp_pktinfo *pktinfo)
{
switch (pktinfo->pctx->gtp_version) {
case GTP_V0:
pktinfo->gtph_port = htons(GTP0_PORT);
gtp0_push_header(skb, pktinfo->pctx);
break;
case GTP_V1:
pktinfo->gtph_port = htons(GTP1U_PORT);
gtp1_push_header(skb, pktinfo->pctx);
break;
}
}
static inline void gtp_set_pktinfo_ipv4(struct gtp_pktinfo *pktinfo,
struct sock *sk, struct iphdr *iph,
struct pdp_ctx *pctx, struct rtable *rt,
struct flowi4 *fl4,
struct net_device *dev)
{
pktinfo->sk = sk;
pktinfo->iph = iph;
pktinfo->pctx = pctx;
pktinfo->rt = rt;
pktinfo->fl4 = *fl4;
pktinfo->dev = dev;
}
static int gtp_build_skb_ip4(struct sk_buff *skb, struct net_device *dev,
struct gtp_pktinfo *pktinfo)
{
struct gtp_dev *gtp = netdev_priv(dev);
struct pdp_ctx *pctx;
struct rtable *rt;
struct flowi4 fl4;
struct iphdr *iph;
__be16 df;
int mtu;
/* Read the IP destination address and resolve the PDP context.
* Prepend PDP header with TEI/TID from PDP ctx.
*/
iph = ip_hdr(skb);
if (gtp->role == GTP_ROLE_SGSN)
pctx = ipv4_pdp_find(gtp, iph->saddr);
else
pctx = ipv4_pdp_find(gtp, iph->daddr);
if (!pctx) {
netdev_dbg(dev, "no PDP ctx found for %pI4, skip\n",
&iph->daddr);
return -ENOENT;
}
netdev_dbg(dev, "found PDP context %p\n", pctx);
rt = ip4_route_output_gtp(&fl4, pctx->sk, pctx->peer_addr_ip4.s_addr,
inet_sk(pctx->sk)->inet_saddr);
if (IS_ERR(rt)) {
netdev_dbg(dev, "no route to SSGN %pI4\n",
&pctx->peer_addr_ip4.s_addr);
dev->stats.tx_carrier_errors++;
goto err;
}
if (rt->dst.dev == dev) {
netdev_dbg(dev, "circular route to SSGN %pI4\n",
&pctx->peer_addr_ip4.s_addr);
dev->stats.collisions++;
goto err_rt;
}
/* This is similar to tnl_update_pmtu(). */
df = iph->frag_off;
if (df) {
mtu = dst_mtu(&rt->dst) - dev->hard_header_len -
sizeof(struct iphdr) - sizeof(struct udphdr);
switch (pctx->gtp_version) {
case GTP_V0:
mtu -= sizeof(struct gtp0_header);
break;
case GTP_V1:
mtu -= sizeof(struct gtp1_header);
break;
}
} else {
mtu = dst_mtu(&rt->dst);
}
skb_dst_update_pmtu_no_confirm(skb, mtu);
if (!skb_is_gso(skb) && (iph->frag_off & htons(IP_DF)) &&
mtu < ntohs(iph->tot_len)) {
netdev_dbg(dev, "packet too big, fragmentation needed\n");
icmp_ndo_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED,
htonl(mtu));
goto err_rt;
}
gtp_set_pktinfo_ipv4(pktinfo, pctx->sk, iph, pctx, rt, &fl4, dev);
gtp_push_header(skb, pktinfo);
return 0;
err_rt:
ip_rt_put(rt);
err:
return -EBADMSG;
}
static netdev_tx_t gtp_dev_xmit(struct sk_buff *skb, struct net_device *dev)
{
unsigned int proto = ntohs(skb->protocol);
struct gtp_pktinfo pktinfo;
int err;
/* Ensure there is sufficient headroom. */
if (skb_cow_head(skb, dev->needed_headroom))
goto tx_err;
skb_reset_inner_headers(skb);
/* PDP context lookups in gtp_build_skb_*() need rcu read-side lock. */
rcu_read_lock();
switch (proto) {
case ETH_P_IP:
err = gtp_build_skb_ip4(skb, dev, &pktinfo);
break;
default:
err = -EOPNOTSUPP;
break;
}
rcu_read_unlock();
if (err < 0)
goto tx_err;
switch (proto) {
case ETH_P_IP:
netdev_dbg(pktinfo.dev, "gtp -> IP src: %pI4 dst: %pI4\n",
&pktinfo.iph->saddr, &pktinfo.iph->daddr);
udp_tunnel_xmit_skb(pktinfo.rt, pktinfo.sk, skb,
pktinfo.fl4.saddr, pktinfo.fl4.daddr,
pktinfo.iph->tos,
ip4_dst_hoplimit(&pktinfo.rt->dst),
0,
pktinfo.gtph_port, pktinfo.gtph_port,
!net_eq(sock_net(pktinfo.pctx->sk),
dev_net(dev)),
false);
break;
}
return NETDEV_TX_OK;
tx_err:
dev->stats.tx_errors++;
dev_kfree_skb(skb);
return NETDEV_TX_OK;
}
static const struct net_device_ops gtp_netdev_ops = {
.ndo_init = gtp_dev_init,
.ndo_uninit = gtp_dev_uninit,
.ndo_start_xmit = gtp_dev_xmit,
.ndo_get_stats64 = dev_get_tstats64,
};
static const struct device_type gtp_type = {
.name = "gtp",
};
static void gtp_link_setup(struct net_device *dev)
{
unsigned int max_gtp_header_len = sizeof(struct iphdr) +
sizeof(struct udphdr) +
sizeof(struct gtp0_header);
dev->netdev_ops = >p_netdev_ops;
dev->needs_free_netdev = true;
SET_NETDEV_DEVTYPE(dev, >p_type);
dev->hard_header_len = 0;
dev->addr_len = 0;
dev->mtu = ETH_DATA_LEN - max_gtp_header_len;
/* Zero header length. */
dev->type = ARPHRD_NONE;
dev->flags = IFF_POINTOPOINT | IFF_NOARP | IFF_MULTICAST;
dev->priv_flags |= IFF_NO_QUEUE;
dev->features |= NETIF_F_LLTX;
netif_keep_dst(dev);
dev->needed_headroom = LL_MAX_HEADER + max_gtp_header_len;
}
static int gtp_hashtable_new(struct gtp_dev *gtp, int hsize);
static int gtp_encap_enable(struct gtp_dev *gtp, struct nlattr *data[]);
static void gtp_destructor(struct net_device *dev)
{
struct gtp_dev *gtp = netdev_priv(dev);
kfree(gtp->addr_hash);
kfree(gtp->tid_hash);
}
static struct sock *gtp_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)