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open5gs/src/pgw/pgw-gtp-path.c

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/*
* Copyright (C) 2019 by Sukchan Lee <acetcom@gmail.com>
*
* This file is part of Open5GS.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
#include "pgw-context.h"
#if HAVE_NETINET_IP_H
#include <netinet/ip.h>
#endif
#if HAVE_NETINET_IP6_H
#include <netinet/ip6.h>
#endif
#if HAVE_NETINET_IP_ICMP_H
#include <netinet/ip_icmp.h>
#endif
#if HAVE_NETINET_ICMP6_H
#include <netinet/icmp6.h>
#endif
#include "pgw-event.h"
#include "pgw-gtp-path.h"
#include "pgw-ipfw.h"
#define PGW_GTP_HANDLED 1
uint16_t in_cksum(uint16_t *addr, int len);
static int pgw_gtp_handle_multicast(ogs_pkbuf_t *recvbuf);
static int pgw_gtp_handle_slaac(pgw_sess_t *sess, ogs_pkbuf_t *recvbuf);
static int pgw_gtp_send_to_bearer(pgw_bearer_t *bearer, ogs_pkbuf_t *sendbuf);
static int pgw_gtp_send_router_advertisement(
pgw_sess_t *sess, uint8_t *ip6_dst);
static void _gtpv1_tun_recv_cb(short when, ogs_socket_t fd, void *data)
{
ogs_pkbuf_t *recvbuf = NULL;
int n;
int rv;
pgw_bearer_t *bearer = NULL;
recvbuf = ogs_pkbuf_alloc(NULL, OGS_MAX_SDU_LEN);
ogs_pkbuf_reserve(recvbuf, OGS_GTPV1U_HEADER_LEN);
ogs_pkbuf_put(recvbuf, OGS_MAX_SDU_LEN-OGS_GTPV1U_HEADER_LEN);
n = ogs_read(fd, recvbuf->data, recvbuf->len);
if (n <= 0) {
ogs_log_message(OGS_LOG_WARN, ogs_socket_errno, "ogs_read() failed");
ogs_pkbuf_free(recvbuf);
return;
}
ogs_pkbuf_trim(recvbuf, n);
/* Find the bearer by packet filter */
bearer = pgw_bearer_find_by_packet(recvbuf);
if (bearer) {
/* Unicast */
rv = pgw_gtp_send_to_bearer(bearer, recvbuf);
ogs_assert(rv == OGS_OK);
} else {
if (ogs_config()->parameter.multicast) {
rv = pgw_gtp_handle_multicast(recvbuf);
ogs_assert(rv != OGS_ERROR);
}
}
ogs_pkbuf_free(recvbuf);
}
static void _gtpv2_c_recv_cb(short when, ogs_socket_t fd, void *data)
{
pgw_event_t *e = NULL;
int rv;
ssize_t size;
ogs_pkbuf_t *pkbuf = NULL;
ogs_sockaddr_t from;
ogs_gtp_node_t *gnode = NULL;
ogs_assert(fd != INVALID_SOCKET);
pkbuf = ogs_pkbuf_alloc(NULL, OGS_MAX_SDU_LEN);
ogs_pkbuf_put(pkbuf, OGS_MAX_SDU_LEN);
size = ogs_recvfrom(fd, pkbuf->data, pkbuf->len, 0, &from);
if (size <= 0) {
ogs_log_message(OGS_LOG_ERROR, ogs_socket_errno,
"ogs_recvfrom() failed");
ogs_pkbuf_free(pkbuf);
return;
}
ogs_pkbuf_trim(pkbuf, size);
e = pgw_event_new(PGW_EVT_S5C_MESSAGE);
gnode = ogs_gtp_node_find_by_addr(&pgw_self()->sgw_s5c_list, &from);
if (!gnode) {
gnode = ogs_gtp_node_add_by_addr(&pgw_self()->sgw_s5c_list, &from);
ogs_assert(gnode);
gnode->sock = data;
}
ogs_assert(e);
e->gnode = gnode;
e->gtpbuf = pkbuf;
rv = ogs_queue_push(pgw_self()->queue, e);
if (rv != OGS_OK) {
ogs_error("ogs_queue_push() failed:%d", (int)rv);
ogs_pkbuf_free(e->gtpbuf);
pgw_event_free(e);
}
}
static void _gtpv1_u_recv_cb(short when, ogs_socket_t fd, void *data)
{
int rv;
ssize_t size;
ogs_pkbuf_t *pkbuf = NULL;
uint32_t len = OGS_GTPV1U_HEADER_LEN;
ogs_gtp_header_t *gtp_h = NULL;
struct ip *ip_h = NULL;
uint32_t teid;
pgw_bearer_t *bearer = NULL;
pgw_sess_t *sess = NULL;
pgw_subnet_t *subnet = NULL;
pgw_dev_t *dev = NULL;
ogs_assert(fd != INVALID_SOCKET);
pkbuf = ogs_pkbuf_alloc(NULL, OGS_MAX_SDU_LEN);
ogs_pkbuf_put(pkbuf, OGS_MAX_SDU_LEN);
size = ogs_recv(fd, pkbuf->data, pkbuf->len, 0);
if (size <= 0) {
ogs_log_message(OGS_LOG_ERROR, ogs_socket_errno,
"ogs_recv() failed");
goto cleanup;
}
ogs_pkbuf_trim(pkbuf, size);
ogs_assert(pkbuf);
ogs_assert(pkbuf->len);
gtp_h = (ogs_gtp_header_t *)pkbuf->data;
if (gtp_h->flags & OGS_GTPU_FLAGS_S) len += 4;
teid = ntohl(gtp_h->teid);
ogs_debug("[PGW] RECV GPU-U from SGW : TEID[0x%x]", teid);
/* Remove GTP header and send packets to TUN interface */
ogs_assert(ogs_pkbuf_pull(pkbuf, len));
ip_h = (struct ip *)pkbuf->data;
ogs_assert(ip_h);
bearer = pgw_bearer_find_by_pgw_s5u_teid(teid);
if (!bearer) {
ogs_warn("[DROP] Cannot find PGW S5U bearer : TEID[0x%x]", teid);
goto cleanup;
}
sess = bearer->sess;
ogs_assert(sess);
if (ip_h->ip_v == 4 && sess->ipv4)
subnet = sess->ipv4->subnet;
else if (ip_h->ip_v == 6 && sess->ipv6)
subnet = sess->ipv6->subnet;
if (!subnet) {
ogs_log_hexdump(OGS_LOG_TRACE, pkbuf->data, pkbuf->len);
ogs_error("[DROP] Cannot find subnet V:%d, IPv4:%p, IPv6:%p",
ip_h->ip_v, sess->ipv4, sess->ipv6);
goto cleanup;
}
/* Check IPv6 */
if (ogs_config()->parameter.no_slaac == 0 && ip_h->ip_v == 6) {
rv = pgw_gtp_handle_slaac(sess, pkbuf);
if (rv == PGW_GTP_HANDLED) {
goto cleanup;
}
ogs_assert(rv == OGS_OK);
}
dev = subnet->dev;
ogs_assert(dev);
if (ogs_write(dev->fd, pkbuf->data, pkbuf->len) <= 0)
ogs_error("ogs_write() failed");
cleanup:
ogs_pkbuf_free(pkbuf);
}
int pgw_gtp_open(void)
{
pgw_dev_t *dev = NULL;
pgw_subnet_t *subnet = NULL;
ogs_socknode_t *node = NULL;
ogs_sock_t *sock = NULL;
int rc;
ogs_list_for_each(&pgw_self()->gtpc_list, node) {
sock = ogs_gtp_server(node);
ogs_assert(sock);
node->poll = ogs_pollset_add(pgw_self()->pollset,
OGS_POLLIN, sock->fd, _gtpv2_c_recv_cb, sock);
}
ogs_list_for_each(&pgw_self()->gtpc_list6, node) {
sock = ogs_gtp_server(node);
ogs_assert(sock);
node->poll = ogs_pollset_add(pgw_self()->pollset,
OGS_POLLIN, sock->fd, _gtpv2_c_recv_cb, sock);
}
pgw_self()->gtpc_sock = ogs_socknode_sock_first(&pgw_self()->gtpc_list);
if (pgw_self()->gtpc_sock)
pgw_self()->gtpc_addr = &pgw_self()->gtpc_sock->local_addr;
pgw_self()->gtpc_sock6 = ogs_socknode_sock_first(&pgw_self()->gtpc_list6);
if (pgw_self()->gtpc_sock6)
pgw_self()->gtpc_addr6 = &pgw_self()->gtpc_sock6->local_addr;
ogs_assert(pgw_self()->gtpc_addr || pgw_self()->gtpc_addr6);
ogs_list_for_each(&pgw_self()->gtpu_list, node) {
sock = ogs_gtp_server(node);
ogs_assert(sock);
node->poll = ogs_pollset_add(pgw_self()->pollset,
OGS_POLLIN, sock->fd, _gtpv1_u_recv_cb, sock);
}
ogs_list_for_each(&pgw_self()->gtpu_list6, node) {
sock = ogs_gtp_server(node);
ogs_assert(sock);
node->poll = ogs_pollset_add(pgw_self()->pollset,
OGS_POLLIN, sock->fd, _gtpv1_u_recv_cb, sock);
}
pgw_self()->gtpu_sock = ogs_socknode_sock_first(&pgw_self()->gtpu_list);
if (pgw_self()->gtpu_sock)
pgw_self()->gtpu_addr = &pgw_self()->gtpu_sock->local_addr;
pgw_self()->gtpu_sock6 = ogs_socknode_sock_first(&pgw_self()->gtpu_list6);
if (pgw_self()->gtpu_sock6)
pgw_self()->gtpu_addr6 = &pgw_self()->gtpu_sock6->local_addr;
ogs_assert(pgw_self()->gtpu_addr || pgw_self()->gtpu_addr6);
/* NOTE : tun device can be created via following command.
*
* $ sudo ip tuntap add name ogstun mode tun
*
* Also, before running pgw, assign the one IP from IP pool of UE
* to ogstun. The IP should not be assigned to UE
*
* $ sudo ifconfig ogstun 10.45.0.1/16 up
*
*/
/* Open Tun interface */
for (dev = pgw_dev_first(); dev; dev = pgw_dev_next(dev)) {
dev->fd = ogs_tun_open(dev->ifname, IFNAMSIZ, 0);
if (dev->fd == INVALID_SOCKET) {
ogs_error("tun_open(dev:%s) failed", dev->ifname);
return OGS_ERROR;
}
dev->poll = ogs_pollset_add(pgw_self()->pollset,
OGS_POLLIN, dev->fd, _gtpv1_tun_recv_cb, NULL);
ogs_assert(dev->poll);
}
/*
* On Linux, it is possible to create a persistent tun/tap
* interface which will continue to exist even if open5gs quit,
* although this is normally not required.
* It can be useful to set up a tun/tap interface owned
* by a non-root user, so open5gs can be started without
* needing any root privileges at all.
*/
/* Set P-to-P IP address with Netmask
* Note that Linux will skip this configuration */
for (subnet = pgw_subnet_first();
subnet; subnet = pgw_subnet_next(subnet)) {
ogs_assert(subnet->dev);
rc = ogs_tun_set_ip(subnet->dev->ifname, &subnet->gw, &subnet->sub);
if (rc != OGS_OK) {
ogs_error("ogs_tun_set_ip(dev:%s) failed", subnet->dev->ifname);
return OGS_ERROR;
}
}
/* Link-Local Address for PGW_TUN */
for (dev = pgw_dev_first(); dev; dev = pgw_dev_next(dev))
dev->link_local_addr = ogs_link_local_addr_by_dev(dev->ifname);
return OGS_OK;
}
void pgw_gtp_close(void)
{
pgw_dev_t *dev = NULL;
ogs_socknode_remove_all(&pgw_self()->gtpc_list);
ogs_socknode_remove_all(&pgw_self()->gtpc_list6);
ogs_socknode_remove_all(&pgw_self()->gtpu_list);
ogs_socknode_remove_all(&pgw_self()->gtpu_list6);
for (dev = pgw_dev_first(); dev; dev = pgw_dev_next(dev)) {
ogs_pollset_remove(dev->poll);
ogs_closesocket(dev->fd);
}
}
static int pgw_gtp_handle_multicast(ogs_pkbuf_t *recvbuf)
{
int rv;
struct ip *ip_h = NULL;
struct ip6_hdr *ip6_h = NULL;
ip_h = (struct ip *)recvbuf->data;
if (ip_h->ip_v == 6) {
#if COMPILE_ERROR_IN_MAC_OS_X /* Compiler error in Mac OS X platform */
ip6_h = (struct ip6_hdr *)recvbuf->data;
if (IN6_IS_ADDR_MULTICAST(&ip6_h->ip6_dst))
#else
struct in6_addr ip6_dst;
ip6_h = (struct ip6_hdr *)recvbuf->data;
memcpy(&ip6_dst, &ip6_h->ip6_dst, sizeof(struct in6_addr));
if (IN6_IS_ADDR_MULTICAST(&ip6_dst))
#endif
{
pgw_sess_t *sess = NULL;
/* IPv6 Multicast */
ogs_list_for_each(&pgw_self()->sess_list, sess) {
if (sess->ipv6) {
/* PDN IPv6 is avaiable */
pgw_bearer_t *bearer = pgw_default_bearer_in_sess(sess);
ogs_assert(bearer);
rv = pgw_gtp_send_to_bearer(bearer, recvbuf);
ogs_assert(rv == OGS_OK);
return PGW_GTP_HANDLED;
}
}
}
}
return OGS_OK;
}
static int pgw_gtp_handle_slaac(pgw_sess_t *sess, ogs_pkbuf_t *recvbuf)
{
int rv;
struct ip *ip_h = NULL;
ogs_assert(sess);
ogs_assert(recvbuf);
ogs_assert(recvbuf->len);
ip_h = (struct ip *)recvbuf->data;
if (ip_h->ip_v == 6) {
struct ip6_hdr *ip6_h = (struct ip6_hdr *)recvbuf->data;
if (ip6_h->ip6_nxt == IPPROTO_ICMPV6) {
struct icmp6_hdr *icmp_h =
(struct icmp6_hdr *)(recvbuf->data + sizeof(struct ip6_hdr));
if (icmp_h->icmp6_type == ND_ROUTER_SOLICIT) {
ogs_debug("[PGW] Router Solict");
if (sess->ipv6) {
rv = pgw_gtp_send_router_advertisement(
sess, ip6_h->ip6_src.s6_addr);
ogs_assert(rv == OGS_OK);
}
return PGW_GTP_HANDLED;
}
}
}
return OGS_OK;
}
static int pgw_gtp_send_to_bearer(pgw_bearer_t *bearer, ogs_pkbuf_t *sendbuf)
{
char buf[OGS_ADDRSTRLEN];
int rv;
ogs_gtp_header_t *gtp_h = NULL;
ogs_assert(bearer);
ogs_assert(bearer->gnode);
ogs_assert(bearer->gnode->sock);
/* Add GTP-U header */
ogs_assert(ogs_pkbuf_push(sendbuf, OGS_GTPV1U_HEADER_LEN));
gtp_h = (ogs_gtp_header_t *)sendbuf->data;
/* Bits 8 7 6 5 4 3 2 1
* +--+--+--+--+--+--+--+--+
* |version |PT| 1| E| S|PN|
* +--+--+--+--+--+--+--+--+
* 0 0 1 1 0 0 0 0
*/
gtp_h->flags = 0x30;
gtp_h->type = OGS_GTPU_MSGTYPE_GPDU;
gtp_h->length = htons(sendbuf->len - OGS_GTPV1U_HEADER_LEN);
gtp_h->teid = htonl(bearer->sgw_s5u_teid);
/* Send to SGW */
ogs_debug("[PGW] SEND GPU-U to SGW[%s] : TEID[0x%x]",
OGS_ADDR(&bearer->gnode->remote_addr, buf),
bearer->sgw_s5u_teid);
rv = ogs_gtp_sendto(bearer->gnode, sendbuf);
return rv;
}
static int pgw_gtp_send_router_advertisement(
pgw_sess_t *sess, uint8_t *ip6_dst)
{
int rv;
ogs_pkbuf_t *pkbuf = NULL;
pgw_bearer_t *bearer = NULL;
pgw_ue_ip_t *ue_ip = NULL;
pgw_subnet_t *subnet = NULL;
pgw_dev_t *dev = NULL;
ogs_ipsubnet_t src_ipsub;
uint16_t plen = 0;
uint8_t nxt = 0;
uint8_t *p = NULL;
struct ip6_hdr *ip6_h = NULL;
struct nd_router_advert *advert_h = NULL;
struct nd_opt_prefix_info *prefix = NULL;
ogs_assert(sess);
bearer = pgw_default_bearer_in_sess(sess);
ogs_assert(bearer);
ue_ip = sess->ipv6;
ogs_assert(ue_ip);
subnet = ue_ip->subnet;
ogs_assert(subnet);
dev = subnet->dev;
ogs_assert(dev);
pkbuf = ogs_pkbuf_alloc(NULL, OGS_GTPV1U_HEADER_LEN+200);
ogs_pkbuf_reserve(pkbuf, OGS_GTPV1U_HEADER_LEN);
ogs_pkbuf_put(pkbuf, 200);
pkbuf->len = sizeof *ip6_h + sizeof *advert_h + sizeof *prefix;
memset(pkbuf->data, 0, pkbuf->len);
p = (uint8_t *)pkbuf->data;
ip6_h = (struct ip6_hdr *)p;
advert_h = (struct nd_router_advert *)((uint8_t *)ip6_h + sizeof *ip6_h);
prefix = (struct nd_opt_prefix_info *)
((uint8_t*)advert_h + sizeof *advert_h);
rv = ogs_ipsubnet(&src_ipsub, "fe80::1", NULL);
ogs_assert(rv == OGS_OK);
if (dev->link_local_addr)
memcpy(src_ipsub.sub, dev->link_local_addr->sin6.sin6_addr.s6_addr,
sizeof src_ipsub.sub);
advert_h->nd_ra_type = ND_ROUTER_ADVERT;
advert_h->nd_ra_code = 0;
advert_h->nd_ra_curhoplimit = 64;
advert_h->nd_ra_flags_reserved = 0;
advert_h->nd_ra_router_lifetime = htons(64800); /* 64800s */
advert_h->nd_ra_reachable = 0;
advert_h->nd_ra_retransmit = 0;
prefix->nd_opt_pi_type = ND_OPT_PREFIX_INFORMATION;
prefix->nd_opt_pi_len = 4; /* 32bytes */
prefix->nd_opt_pi_prefix_len = subnet->prefixlen;
prefix->nd_opt_pi_flags_reserved =
ND_OPT_PI_FLAG_ONLINK|ND_OPT_PI_FLAG_AUTO;
prefix->nd_opt_pi_valid_time = htonl(0xffffffff); /* Infinite */
prefix->nd_opt_pi_preferred_time = htonl(0xffffffff); /* Infinite */
memcpy(prefix->nd_opt_pi_prefix.s6_addr,
subnet->sub.sub, sizeof prefix->nd_opt_pi_prefix.s6_addr);
/* For IPv6 Pseudo-Header */
plen = htons(sizeof *advert_h + sizeof *prefix);
nxt = IPPROTO_ICMPV6;
memcpy(p, src_ipsub.sub, sizeof src_ipsub.sub);
p += sizeof src_ipsub.sub;
memcpy(p, ip6_dst, OGS_IPV6_LEN);
p += OGS_IPV6_LEN;
p += 2; memcpy(p, &plen, 2); p += 2;
p += 3; *p = nxt; p += 1;
advert_h->nd_ra_cksum = in_cksum((uint16_t *)pkbuf->data, pkbuf->len);
ip6_h->ip6_flow = htonl(0x60000001);
ip6_h->ip6_plen = plen;
ip6_h->ip6_nxt = nxt; /* ICMPv6 */
ip6_h->ip6_hlim = 0xff;
memcpy(ip6_h->ip6_src.s6_addr, src_ipsub.sub, sizeof src_ipsub.sub);
memcpy(ip6_h->ip6_dst.s6_addr, ip6_dst, OGS_IPV6_LEN);
rv = pgw_gtp_send_to_bearer(bearer, pkbuf);
ogs_assert(rv == OGS_OK);
ogs_debug("[PGW] Router Advertisement");
ogs_pkbuf_free(pkbuf);
return rv;
}
uint16_t in_cksum(uint16_t *addr, int len)
{
int nleft = len;
uint32_t sum = 0;
uint16_t *w = addr;
uint16_t answer = 0;
// Adding 16 bits sequentially in sum
while (nleft > 1) {
sum += *w;
nleft -= 2;
w++;
}
// If an odd byte is left
if (nleft == 1) {
*(uint8_t *) (&answer) = *(uint8_t *) w;
sum += answer;
}
sum = (sum >> 16) + (sum & 0xffff);
sum += (sum >> 16);
answer = ~sum;
return answer;
}
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