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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 <[email protected]>
*
* Author: Harald Welte <[email protected]>
* Pablo Neira Ayuso <[email protected]>
* Andreas Schultz <[email protected]>
*/
#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/ipv6.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;
union {
struct in_addr addr;
struct in6_addr addr6;
} ms;
union {
struct in_addr addr;
struct in6_addr addr6;
} peer;
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 {
u16 af;
u8 gtp_version;
union {
struct in_addr addr;
} ms;
union {
struct in_addr addr;
} peer;
};
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);
}
static u32 ipv6_hashfn(const struct in6_addr *ip6)
{
return jhash_2words((__force u32)ip6->s6_addr32[0],
(__force u32)ip6->s6_addr32[1], 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, u16 family)
{
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->af == family &&
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, u16 family)
{
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->af == family &&
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.s_addr == ms_addr)
return pdp;
}
return NULL;
}
/* 3GPP TS 29.060: PDN Connection: the association between a MS represented by
* [...] one IPv6 *prefix* and a PDN represented by an APN.
*
* Then, 3GPP TS 29.061, Section 11.2.1.3 says: The size of the prefix shall be
* according to the maximum prefix length for a global IPv6 address as
* specified in the IPv6 Addressing Architecture, see RFC 4291.
*
* Finally, RFC 4291 section 2.5.4 states: All Global Unicast addresses other
* than those that start with binary 000 have a 64-bit interface ID field
* (i.e., n + m = 64).
*/
static bool ipv6_pdp_addr_equal(const struct in6_addr *a,
const struct in6_addr *b)
{
return a->s6_addr32[0] == b->s6_addr32[0] &&
a->s6_addr32[1] == b->s6_addr32[1];
}
static struct pdp_ctx *ipv6_pdp_find(struct gtp_dev *gtp,
const struct in6_addr *ms_addr)
{
struct hlist_head *head;
struct pdp_ctx *pdp;
head = >p->addr_hash[ipv6_hashfn(ms_addr) % gtp->hash_size];
hlist_for_each_entry_rcu(pdp, head, hlist_addr) {
if (pdp->af == AF_INET6 &&
ipv6_pdp_addr_equal(&pdp->ms.addr6, 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.s_addr;
else
return iph->saddr == pctx->ms.addr.s_addr;
}
static bool gtp_check_ms_ipv6(struct sk_buff *skb, struct pdp_ctx *pctx,
unsigned int hdrlen, unsigned int role)
{
struct ipv6hdr *ip6h;
int ret;
if (!pskb_may_pull(skb, hdrlen + sizeof(struct ipv6hdr)))
return false;
ip6h = (struct ipv6hdr *)(skb->data + hdrlen);
if ((ipv6_addr_type(&ip6h->saddr) & IPV6_ADDR_LINKLOCAL) ||
(ipv6_addr_type(&ip6h->daddr) & IPV6_ADDR_LINKLOCAL))
return false;
if (role == GTP_ROLE_SGSN) {
ret = ipv6_pdp_addr_equal(&ip6h->daddr, &pctx->ms.addr6);
} else {
ret = ipv6_pdp_addr_equal(&ip6h->saddr, &pctx->ms.addr6);
}
return ret;
}
/* 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,
__u16 inner_proto)
{
switch (inner_proto) {
case ETH_P_IP:
return gtp_check_ms_ipv4(skb, pctx, hdrlen, role);
case ETH_P_IPV6:
return gtp_check_ms_ipv6(skb, pctx, hdrlen, role);
}
return false;
}
static int gtp_inner_proto(struct sk_buff *skb, unsigned int hdrlen,
__u16 *inner_proto)
{
__u8 *ip_version, _ip_version;
ip_version = skb_header_pointer(skb, hdrlen, sizeof(*ip_version),
&_ip_version);
if (!ip_version)
return -1;
switch (*ip_version & 0xf0) {
case 0x40:
*inner_proto = ETH_P_IP;
break;
case 0x60:
*inner_proto = ETH_P_IPV6;
break;
default:
return -1;
}
return 0;
}
static int gtp_rx(struct pdp_ctx *pctx, struct sk_buff *skb,
unsigned int hdrlen, unsigned int role, __u16 inner_proto)
{
if (!gtp_check_ms(skb, pctx, hdrlen, role, inner_proto)) {
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, htons(inner_proto),
!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 = ip_sock_rt_tos(sk);
fl4->flowi4_scope = ip_sock_rt_scope(sk);
fl4->flowi4_proto = sk->sk_protocol;
return ip_route_output_key(sock_net(sk), fl4);
}
static struct rt6_info *ip6_route_output_gtp(struct net *net,
struct flowi6 *fl6,
const struct sock *sk,
const struct in6_addr *daddr,
struct in6_addr *saddr)
{
struct dst_entry *dst;
memset(fl6, 0, sizeof(*fl6));
fl6->flowi6_oif = sk->sk_bound_dev_if;
fl6->daddr = *daddr;
fl6->saddr = *saddr;
fl6->flowi6_proto = sk->sk_protocol;
dst = ipv6_stub->ipv6_dst_lookup_flow(net, sk, fl6, NULL);
if (IS_ERR(dst))
return ERR_PTR(-ENETUNREACH);
return (struct rt6_info *)dst;
}
/* 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_ip(struct gtp_dev *gtp, struct sk_buff *skb)
{
struct iphdr *iph = ip_hdr(skb);
struct flowi4 fl4;
struct rtable *rt;
/* 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 gtp0_send_echo_resp(struct gtp_dev *gtp, struct sk_buff *skb)
{
struct gtp0_packet *gtp_pkt;
struct gtp0_header *gtp0;
__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;
switch (gtp->sk0->sk_family) {
case AF_INET:
if (gtp0_send_echo_resp_ip(gtp, skb) < 0)
return -1;
break;
case AF_INET6:
return -1;
}
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.s_addr) ||
nla_put_be32(skb, GTPA_MS_ADDRESS, echo.ms.addr.s_addr))
goto failure;
genlmsg_end(skb, genlh);
return 0;
failure:
genlmsg_cancel(skb, genlh);
return -EMSGSIZE;
}
static void gtp0_handle_echo_resp_ip(struct sk_buff *skb, struct echo_info *echo)
{
struct iphdr *iph = ip_hdr(skb);
echo->ms.addr.s_addr = iph->daddr;
echo->peer.addr.s_addr = iph->saddr;
echo->gtp_version = GTP_V0;
}
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;
int ret;
gtp0 = (struct gtp0_header *)(skb->data + sizeof(struct udphdr));
if (!gtp0_validate_echo_hdr(gtp0))
return -1;
switch (gtp->sk0->sk_family) {
case AF_INET:
gtp0_handle_echo_resp_ip(skb, &echo);
break;
case AF_INET6:
return -1;
}
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 gtp_proto_to_family(__u16 proto)
{
switch (proto) {
case ETH_P_IP:
return AF_INET;
case ETH_P_IPV6:
return AF_INET6;
default:
WARN_ON_ONCE(1);
break;
}
return AF_UNSPEC;
}
/* 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;
__u16 inner_proto;
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;
if (gtp_inner_proto(skb, hdrlen, &inner_proto) < 0) {
netdev_dbg(gtp->dev, "GTP packet does not encapsulate an IP packet\n");
return -1;
}
pctx = gtp0_pdp_find(gtp, be64_to_cpu(gtp0->tid),
gtp_proto_to_family(inner_proto));
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, inner_proto);
}
/* 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.s_addr = iph->daddr;
echo.peer.addr.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 gtp_parse_exthdrs(struct sk_buff *skb, unsigned int *hdrlen)
{
struct gtp_ext_hdr *gtp_exthdr, _gtp_exthdr;
unsigned int offset = *hdrlen;
__u8 *next_type, _next_type;
/* From 29.060: "The Extension Header Length field specifies the length
* of the particular Extension header in 4 octets units."
*
* This length field includes length field size itself (1 byte),
* payload (variable length) and next type (1 byte). The extension
* header is aligned to to 4 bytes.
*/
do {
gtp_exthdr = skb_header_pointer(skb, offset, sizeof(*gtp_exthdr),
&_gtp_exthdr);
if (!gtp_exthdr || !gtp_exthdr->len)
return -1;
offset += gtp_exthdr->len * 4;
/* From 29.060: "If no such Header follows, then the value of
* the Next Extension Header Type shall be 0."
*/
next_type = skb_header_pointer(skb, offset - 1,
sizeof(_next_type), &_next_type);
if (!next_type)
return -1;
} while (*next_type != 0);
*hdrlen = offset;
return 0;
}
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;
__u16 inner_proto;
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;
if (gtp_inner_proto(skb, hdrlen, &inner_proto) < 0) {
netdev_dbg(gtp->dev, "GTP packet does not encapsulate an IP packet\n");
return -1;
}
gtp1 = (struct gtp1_header *)(skb->data + sizeof(struct udphdr));
pctx = gtp1_pdp_find(gtp, ntohl(gtp1->tid),
gtp_proto_to_family(inner_proto));
if (!pctx) {
netdev_dbg(gtp->dev, "No PDP ctx to decap skb=%p\n", skb);
return 1;
}
if (gtp1->flags & GTP1_F_EXTHDR &&
gtp_parse_exthdrs(skb, &hdrlen) < 0)
return -1;
return gtp_rx(pctx, skb, hdrlen, gtp->role, inner_proto);
}
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;
WRITE_ONCE(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 (READ_ONCE(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 void gtp_dev_uninit(struct net_device *dev)
{
struct gtp_dev *gtp = netdev_priv(dev);
gtp_encap_disable(gtp);
}
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;
union {
struct flowi4 fl4;
struct flowi6 fl6;
};
union {
struct rtable *rt;
struct rt6_info *rt6;
};
struct pdp_ctx *pctx;
struct net_device *dev;
__u8 tos;
__be16 gtph_port;
};
static void gtp_push_header(struct sk_buff *skb, struct gtp_pktinfo *pktinfo)