// SPDX-License-Identifier: GPL-2.0-or-later
/*
* ip_vs_proto_udp.c: UDP load balancing support for IPVS
*
* Authors: Wensong Zhang <[email protected]>
* Julian Anastasov <[email protected]>
*
* Changes: Hans Schillstrom <[email protected]>
* Network name space (netns) aware.
*/
#define KMSG_COMPONENT "IPVS"
#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
#include <linux/in.h>
#include <linux/ip.h>
#include <linux/kernel.h>
#include <linux/netfilter.h>
#include <linux/netfilter_ipv4.h>
#include <linux/udp.h>
#include <linux/indirect_call_wrapper.h>
#include <net/ip_vs.h>
#include <net/ip.h>
#include <net/ip6_checksum.h>
static int
udp_csum_check(int af, struct sk_buff *skb, struct ip_vs_protocol *pp);
static int
udp_conn_schedule(struct netns_ipvs *ipvs, int af, struct sk_buff *skb,
struct ip_vs_proto_data *pd,
int *verdict, struct ip_vs_conn **cpp,
struct ip_vs_iphdr *iph)
{
struct ip_vs_service *svc;
struct udphdr _udph, *uh;
__be16 _ports[2], *ports = NULL;
if (likely(!ip_vs_iph_icmp(iph))) {
/* IPv6 fragments, only first fragment will hit this */
uh = skb_header_pointer(skb, iph->len, sizeof(_udph), &_udph);
if (uh)
ports = &uh->source;
} else {
ports = skb_header_pointer(
skb, iph->len, sizeof(_ports), &_ports);
}
if (!ports) {
*verdict = NF_DROP;
return 0;
}
if (likely(!ip_vs_iph_inverse(iph)))
svc = ip_vs_service_find(ipvs, af, skb->mark, iph->protocol,
&iph->daddr, ports[1]);
else
svc = ip_vs_service_find(ipvs, af, skb->mark, iph->protocol,
&iph->saddr, ports[0]);
if (svc) {
int ignored;
if (ip_vs_todrop(ipvs)) {
/*
* It seems that we are very loaded.
* We have to drop this packet :(
*/
*verdict = NF_DROP;
return 0;
}
/*
* Let the virtual server select a real server for the
* incoming connection, and create a connection entry.
*/
*cpp = ip_vs_schedule(svc, skb, pd, &ignored, iph);
if (!*cpp && ignored <= 0) {
if (!ignored)
*verdict = ip_vs_leave(svc, skb, pd, iph);
else
*verdict = NF_DROP;
return 0;
}
}
/* NF_ACCEPT */
return 1;
}
static inline void
udp_fast_csum_update(int af, struct udphdr *uhdr,
const union nf_inet_addr *oldip,
const union nf_inet_addr *newip,
__be16 oldport, __be16 newport)
{
#ifdef CONFIG_IP_VS_IPV6
if (af == AF_INET6)
uhdr->check =
csum_fold(ip_vs_check_diff16(oldip->ip6, newip->ip6,
ip_vs_check_diff2(oldport, newport,
~csum_unfold(uhdr->check))));
else
#endif
uhdr->check =
csum_fold(ip_vs_check_diff4(oldip->ip, newip->ip,
ip_vs_check_diff2(oldport, newport,
~csum_unfold(uhdr->check))));
if (!uhdr->check)
uhdr->check = CSUM_MANGLED_0;
}
static inline void
udp_partial_csum_update(int af, struct udphdr *uhdr,
const union nf_inet_addr *oldip,
const union nf_inet_addr *newip,
__be16 oldlen, __be16 newlen)
{
#ifdef CONFIG_IP_VS_IPV6
if (af == AF_INET6)
uhdr->check =
~csum_fold(ip_vs_check_diff16(oldip->ip6, newip->ip6,
ip_vs_check_diff2(oldlen, newlen,
csum_unfold(uhdr->check))));
else
#endif
uhdr->check =
~csum_fold(ip_vs_check_diff4(oldip->ip, newip->ip,
ip_vs_check_diff2(oldlen, newlen,
csum_unfold(uhdr->check))));
}
INDIRECT_CALLABLE_SCOPE int
udp_snat_handler(struct sk_buff *skb, struct ip_vs_protocol *pp,
struct ip_vs_conn *cp, struct ip_vs_iphdr *iph)
{
struct udphdr *udph;
unsigned int udphoff = iph->len;
bool payload_csum = false;
int oldlen;
#ifdef CONFIG_IP_VS_IPV6
if (cp->af == AF_INET6 && iph->fragoffs)
return 1;
#endif
oldlen = skb->len - udphoff;
/* csum_check requires unshared skb */
if (skb_ensure_writable(skb, udphoff + sizeof(*udph)))
return 0;
if (unlikely(cp->app != NULL)) {
int ret;
/* Some checks before mangling */
if (!udp_csum_check(cp->af, skb, pp))
return 0;
/*
* Call application helper if needed
*/
if (!(ret = ip_vs_app_pkt_out(cp, skb, iph)))
return 0;
/* ret=2: csum update is needed after payload mangling */
if (ret == 1)
oldlen = skb->len - udphoff;
else
payload_csum = true;
}
udph = (void *)skb_network_header(skb) + udphoff;
udph->source = cp->vport;
/*
* Adjust UDP checksums
*/
if (skb->ip_summed == CHECKSUM_PARTIAL) {
udp_partial_csum_update(cp->af, udph, &cp->daddr, &cp->vaddr,
htons(oldlen),
htons(skb->len - udphoff));
} else if (!payload_csum && (udph->check != 0)) {
/* Only port and addr are changed, do fast csum update */
udp_fast_csum_update(cp->af, udph, &cp->daddr, &cp->vaddr,
cp->dport, cp->vport);
if (skb->ip_summed == CHECKSUM_COMPLETE)
skb->ip_summed = cp->app ?
CHECKSUM_UNNECESSARY : CHECKSUM_NONE;
} else {
/* full checksum calculation */
udph->check = 0;
skb->csum = skb_checksum(skb, udphoff, skb->len - udphoff, 0);
#ifdef CONFIG_IP_VS_IPV6
if (cp->af == AF_INET6)
udph->check = csum_ipv6_magic(&cp->vaddr.in6,
&cp->caddr.in6,
skb->len - udphoff,
cp->protocol, skb->csum);
else
#endif
udph->check = csum_tcpudp_magic(cp->vaddr.ip,
cp->caddr.ip,
skb->len - udphoff,
cp->protocol,
skb->csum);
if (udph->check == 0)
udph->check = CSUM_MANGLED_0;
skb->ip_summed = CHECKSUM_UNNECESSARY;
IP_VS_DBG(11, "O-pkt: %s O-csum=%d (+%zd)\n",
pp->name, udph->check,
(char*)&(udph->check) - (char*)udph);
}
return 1;
}
static int
udp_dnat_handler(struct sk_buff *skb, struct ip_vs_protocol *pp,
struct ip_vs_conn *cp, struct ip_vs_iphdr *iph)
{
struct udphdr *udph;
unsigned int udphoff = iph->len;
bool payload_csum = false;
int oldlen;
#ifdef CONFIG_IP_VS_IPV6
if (cp->af == AF_INET6 && iph->fragoffs)
return 1;
#endif
oldlen = skb->len - udphoff;
/* csum_check requires unshared skb */
if (skb_ensure_writable(skb, udphoff + sizeof(*udph)))
return 0;
if (unlikely(cp->app != NULL)) {
int ret;
/* Some checks before mangling */
if (!udp_csum_check(cp->af, skb, pp))
return 0;
/*
* Attempt ip_vs_app call.
* It will fix ip_vs_conn
*/
if (!(ret = ip_vs_app_pkt_in(cp, skb, iph)))
return 0;
/* ret=2: csum update is needed after payload mangling */
if (ret == 1)
oldlen = skb->len - udphoff;
else
payload_csum = true;
}
udph = (void *)skb_network_header(skb) + udphoff;
udph->dest = cp->dport;
/*
* Adjust UDP checksums
*/
if (skb->ip_summed == CHECKSUM_PARTIAL) {
udp_partial_csum_update(cp->af, udph, &cp->vaddr, &cp->daddr,
htons(oldlen),
htons(skb->len - udphoff));
} else if (!payload_csum && (udph->check != 0)) {
/* Only port and addr are changed, do fast csum update */
udp_fast_csum_update(cp->af, udph, &cp->vaddr, &cp->daddr,
cp->vport, cp->dport);
if (skb->ip_summed == CHECKSUM_COMPLETE)
skb->ip_summed = cp->app ?
CHECKSUM_UNNECESSARY : CHECKSUM_NONE;
} else {
/* full checksum calculation */
udph->check = 0;
skb->csum = skb_checksum(skb, udphoff, skb->len - udphoff, 0);
#ifdef CONFIG_IP_VS_IPV6
if (cp->af == AF_INET6)
udph->check = csum_ipv6_magic(&cp->caddr.in6,
&cp->daddr.in6,
skb->len - udphoff,
cp->protocol, skb->csum);
else
#endif
udph->check = csum_tcpudp_magic(cp->caddr.ip,
cp->daddr.ip,
skb->len - udphoff,
cp->protocol,
skb->csum);
if (udph->check == 0)
udph->check = CSUM_MANGLED_0;
skb->ip_summed = CHECKSUM_UNNECESSARY;
}
return 1;
}
static int
udp_csum_check(int af, struct sk_buff *skb, struct ip_vs_protocol *pp)
{
struct udphdr _udph, *uh;
unsigned int udphoff;
#ifdef CONFIG_IP_VS_IPV6
if (af == AF_INET6)
udphoff = sizeof(struct ipv6hdr);
else
#endif
udphoff = ip_hdrlen(skb);
uh = skb_header_pointer(skb, udphoff, sizeof(_udph), &_udph);
if (uh == NULL)
return 0;
if (uh->check != 0) {
switch (skb->ip_summed) {
case CHECKSUM_NONE:
skb->csum = skb_checksum(skb, udphoff,
skb->len - udphoff, 0);
fallthrough;
case CHECKSUM_COMPLETE:
#ifdef CONFIG_IP_VS_IPV6
if (af == AF_INET6) {
if (csum_ipv6_magic(&ipv6_hdr(skb)->saddr,
&ipv6_hdr(skb)->daddr,
skb->len - udphoff,
ipv6_hdr(skb)->nexthdr,
skb->csum)) {
IP_VS_DBG_RL_PKT(0, af, pp, skb, 0,
"Failed checksum for");
return 0;
}
} else
#endif
if (csum_tcpudp_magic(ip_hdr(skb)->saddr,
ip_hdr(skb)->daddr,
skb->len - udphoff,
ip_hdr(skb)->protocol,
skb->csum)) {
IP_VS_DBG_RL_PKT(0, af, pp, skb, 0,
"Failed checksum for");
return 0;
}
break;
default:
/* No need to checksum. */
break;
}
}
return 1;
}
static inline __u16 udp_app_hashkey(__be16 port)
{
return (((__force u16)port >> UDP_APP_TAB_BITS) ^ (__force u16)port)
& UDP_APP_TAB_MASK;
}
static int udp_register_app(struct netns_ipvs *ipvs, struct ip_vs_app *inc)
{
struct ip_vs_app *i;
__u16 hash;
__be16 port = inc->port;
int ret = 0;
struct ip_vs_proto_data *pd = ip_vs_proto_data_get(ipvs, IPPROTO_UDP);
hash = udp_app_hashkey(port);
list_for_each_entry(i, &ipvs->udp_apps[hash], p_list) {
if (i->port == port) {
ret = -EEXIST;
goto out;
}
}
list_add_rcu(&inc->p_list, &ipvs->udp_apps[hash]);
atomic_inc(&pd->appcnt);
out:
return ret;
}
static void
udp_unregister_app(struct netns_ipvs *ipvs, struct ip_vs_app *inc)
{
struct ip_vs_proto_data *pd = ip_vs_proto_data_get(ipvs, IPPROTO_UDP);
atomic_dec(&pd->appcnt);
list_del_rcu(&inc->p_list);
}
static int udp_app_conn_bind(struct ip_vs_conn *cp)
{
struct netns_ipvs *ipvs = cp->ipvs;
int hash;
struct ip_vs_app *inc;
int result = 0;
/* Default binding: bind app only for NAT */
if (IP_VS_FWD_METHOD(cp) != IP_VS_CONN_F_MASQ)
return 0;
/* Lookup application incarnations and bind the right one */
hash = udp_app_hashkey(cp->vport);
list_for_each_entry_rcu(inc, &ipvs->udp_apps[hash], p_list) {
if (inc->port == cp->vport) {
if (unlikely(!ip_vs_app_inc_get(inc)))
break;
IP_VS_DBG_BUF(9, "%s(): Binding conn %s:%u->"
"%s:%u to app %s on port %u\n",
__func__,
IP_VS_DBG_ADDR(cp->af, &cp->caddr),
ntohs(cp->cport),
IP_VS_DBG_ADDR(cp->af, &cp->vaddr),
ntohs(cp->vport),
inc->name, ntohs(inc->port));
cp->app = inc;
if (inc->init_conn)
result = inc->init_conn(inc, cp);
break;
}
}
return result;
}
static const int udp_timeouts[IP_VS_UDP_S_LAST+1] = {
[IP_VS_UDP_S_NORMAL] = 5*60*HZ,
[IP_VS_UDP_S_LAST] = 2*HZ,
};
static const char *const udp_state_name_table[IP_VS_UDP_S_LAST+1] = {
[IP_VS_UDP_S_NORMAL] = "UDP",
[IP_VS_UDP_S_LAST] = "BUG!",
};
static const char * udp_state_name(int state)
{
if (state >= IP_VS_UDP_S_LAST)
return "ERR!";
return udp_state_name_table[state] ? udp_state_name_table[state] : "?";
}
static void
udp_state_transition(struct ip_vs_conn *cp, int direction,
const struct sk_buff *skb,
struct ip_vs_proto_data *pd)
{
if (unlikely(!pd)) {
pr_err("UDP no ns data\n");
return;
}
cp->timeout = pd->timeout_table[IP_VS_UDP_S_NORMAL];
if (direction == IP_VS_DIR_OUTPUT)
ip_vs_control_assure_ct(cp);
}
static int __udp_init(struct netns_ipvs *ipvs, struct ip_vs_proto_data *pd)
{
ip_vs_init_hash_table(ipvs->udp_apps, UDP_APP_TAB_SIZE);
pd->timeout_table = ip_vs_create_timeout_table((int *)udp_timeouts,
sizeof(udp_timeouts));
if (!pd->timeout_table)
return -ENOMEM;
return 0;
}
static void __udp_exit(struct netns_ipvs *ipvs, struct ip_vs_proto_data *pd)
{
kfree(pd->timeout_table);
}
struct ip_vs_protocol ip_vs_protocol_udp = {
.name = "UDP",
.protocol = IPPROTO_UDP,
.num_states = IP_VS_UDP_S_LAST,
.dont_defrag = 0,
.init = NULL,
.exit = NULL,
.init_netns = __udp_init,
.exit_netns = __udp_exit,
.conn_schedule = udp_conn_schedule,
.conn_in_get = ip_vs_conn_in_get_proto,
.conn_out_get = ip_vs_conn_out_get_proto,
.snat_handler = udp_snat_handler,
.dnat_handler = udp_dnat_handler,
.state_transition = udp_state_transition,
.state_name = udp_state_name,
.register_app = udp_register_app,
.unregister_app = udp_unregister_app,
.app_conn_bind = udp_app_conn_bind,
.debug_packet = ip_vs_tcpudp_debug_packet,
.timeout_change = NULL,
};
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