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root/net/netfilter/ipvs/ip_vs_proto_udp.c

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DEFINITIONS

This source file includes following definitions.
  1. udp_conn_in_get
  2. udp_conn_out_get
  3. udp_conn_schedule
  4. udp_fast_csum_update
  5. udp_partial_csum_update
  6. udp_snat_handler
  7. udp_dnat_handler
  8. udp_csum_check
  9. udp_app_hashkey
  10. udp_register_app
  11. udp_unregister_app
  12. udp_app_conn_bind
  13. udp_set_state_timeout
  14. udp_state_name
  15. udp_state_transition
  16. udp_init
  17. udp_exit

/*
 * ip_vs_proto_udp.c:   UDP load balancing support for IPVS
 *
 * Authors:     Wensong Zhang <wensong@linuxvirtualserver.org>
 *              Julian Anastasov <ja@ssi.bg>
 *
 *              This program is free software; you can redistribute it and/or
 *              modify it under the terms of the GNU General Public License
 *              as published by the Free Software Foundation; either version
 *              2 of the License, or (at your option) any later version.
 *
 * Changes:
 *
 */

#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 <net/ip_vs.h>
#include <net/ip.h>
#include <net/ip6_checksum.h>

static struct ip_vs_conn *
udp_conn_in_get(int af, const struct sk_buff *skb, struct ip_vs_protocol *pp,
                const struct ip_vs_iphdr *iph, unsigned int proto_off,
                int inverse)
{
        struct ip_vs_conn *cp;
        __be16 _ports[2], *pptr;

        pptr = skb_header_pointer(skb, proto_off, sizeof(_ports), _ports);
        if (pptr == NULL)
                return NULL;

        if (likely(!inverse)) {
                cp = ip_vs_conn_in_get(af, iph->protocol,
                                       &iph->saddr, pptr[0],
                                       &iph->daddr, pptr[1]);
        } else {
                cp = ip_vs_conn_in_get(af, iph->protocol,
                                       &iph->daddr, pptr[1],
                                       &iph->saddr, pptr[0]);
        }

        return cp;
}


static struct ip_vs_conn *
udp_conn_out_get(int af, const struct sk_buff *skb, struct ip_vs_protocol *pp,
                 const struct ip_vs_iphdr *iph, unsigned int proto_off,
                 int inverse)
{
        struct ip_vs_conn *cp;
        __be16 _ports[2], *pptr;

        pptr = skb_header_pointer(skb, proto_off, sizeof(_ports), _ports);
        if (pptr == NULL)
                return NULL;

        if (likely(!inverse)) {
                cp = ip_vs_conn_out_get(af, iph->protocol,
                                        &iph->saddr, pptr[0],
                                        &iph->daddr, pptr[1]);
        } else {
                cp = ip_vs_conn_out_get(af, iph->protocol,
                                        &iph->daddr, pptr[1],
                                        &iph->saddr, pptr[0]);
        }

        return cp;
}


static int
udp_conn_schedule(int af, struct sk_buff *skb, struct ip_vs_protocol *pp,
                  int *verdict, struct ip_vs_conn **cpp)
{
        struct ip_vs_service *svc;
        struct udphdr _udph, *uh;
        struct ip_vs_iphdr iph;

        ip_vs_fill_iphdr(af, skb_network_header(skb), &iph);

        uh = skb_header_pointer(skb, iph.len, sizeof(_udph), &_udph);
        if (uh == NULL) {
                *verdict = NF_DROP;
                return 0;
        }

        svc = ip_vs_service_get(af, skb->mark, iph.protocol,
                                &iph.daddr, uh->dest);
        if (svc) {
                if (ip_vs_todrop()) {
                        /*
                         * It seems that we are very loaded.
                         * We have to drop this packet :(
                         */
                        ip_vs_service_put(svc);
                        *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);
                if (!*cpp) {
                        *verdict = ip_vs_leave(svc, skb, pp);
                        return 0;
                }
                ip_vs_service_put(svc);
        }
        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))));
}


static int
udp_snat_handler(struct sk_buff *skb,
                 struct ip_vs_protocol *pp, struct ip_vs_conn *cp)
{
        struct udphdr *udph;
        unsigned int udphoff;
        int oldlen;

#ifdef CONFIG_IP_VS_IPV6
        if (cp->af == AF_INET6)
                udphoff = sizeof(struct ipv6hdr);
        else
#endif
                udphoff = ip_hdrlen(skb);
        oldlen = skb->len - udphoff;

        /* csum_check requires unshared skb */
        if (!skb_make_writable(skb, udphoff+sizeof(*udph)))
                return 0;

        if (unlikely(cp->app != NULL)) {
                /* Some checks before mangling */
                if (pp->csum_check && !pp->csum_check(cp->af, skb, pp))
                        return 0;

                /*
                 *      Call application helper if needed
                 */
                if (!ip_vs_app_pkt_out(cp, skb))
                        return 0;
        }

        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,
                                        htonl(oldlen),
                                        htonl(skb->len - udphoff));
        } else if (!cp->app && (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 = 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;
                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 udphdr *udph;
        unsigned int udphoff;
        int oldlen;

#ifdef CONFIG_IP_VS_IPV6
        if (cp->af == AF_INET6)
                udphoff = sizeof(struct ipv6hdr);
        else
#endif
                udphoff = ip_hdrlen(skb);
        oldlen = skb->len - udphoff;

        /* csum_check requires unshared skb */
        if (!skb_make_writable(skb, udphoff+sizeof(*udph)))
                return 0;

        if (unlikely(cp->app != NULL)) {
                /* Some checks before mangling */
                if (pp->csum_check && !pp->csum_check(cp->af, skb, pp))
                        return 0;

                /*
                 *      Attempt ip_vs_app call.
                 *      It will fix ip_vs_conn
                 */
                if (!ip_vs_app_pkt_in(cp, skb))
                        return 0;
        }

        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->daddr, &cp->vaddr,
                                        htonl(oldlen),
                                        htonl(skb->len - udphoff));
        } else if (!cp->app && (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 = 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);
                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, 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, pp, skb, 0,
                                                         "Failed checksum for");
                                        return 0;
                                }
                        break;
                default:
                        /* No need to checksum. */
                        break;
                }
        }
        return 1;
}


/*
 *      Note: the caller guarantees that only one of register_app,
 *      unregister_app or app_conn_bind is called each time.
 */

#define UDP_APP_TAB_BITS        4
#define UDP_APP_TAB_SIZE        (1 << UDP_APP_TAB_BITS)
#define UDP_APP_TAB_MASK        (UDP_APP_TAB_SIZE - 1)

static struct list_head udp_apps[UDP_APP_TAB_SIZE];
static DEFINE_SPINLOCK(udp_app_lock);

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 ip_vs_app *inc)
{
        struct ip_vs_app *i;
        __u16 hash;
        __be16 port = inc->port;
        int ret = 0;

        hash = udp_app_hashkey(port);


        spin_lock_bh(&udp_app_lock);
        list_for_each_entry(i, &udp_apps[hash], p_list) {
                if (i->port == port) {
                        ret = -EEXIST;
                        goto out;
                }
        }
        list_add(&inc->p_list, &udp_apps[hash]);
        atomic_inc(&ip_vs_protocol_udp.appcnt);

  out:
        spin_unlock_bh(&udp_app_lock);
        return ret;
}


static void
udp_unregister_app(struct ip_vs_app *inc)
{
        spin_lock_bh(&udp_app_lock);
        atomic_dec(&ip_vs_protocol_udp.appcnt);
        list_del(&inc->p_list);
        spin_unlock_bh(&udp_app_lock);
}


static int udp_app_conn_bind(struct ip_vs_conn *cp)
{
        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);

        spin_lock(&udp_app_lock);
        list_for_each_entry(inc, &udp_apps[hash], p_list) {
                if (inc->port == cp->vport) {
                        if (unlikely(!ip_vs_app_inc_get(inc)))
                                break;
                        spin_unlock(&udp_app_lock);

                        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);
                        goto out;
                }
        }
        spin_unlock(&udp_app_lock);

  out:
        return result;
}


static 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 char * udp_state_name_table[IP_VS_UDP_S_LAST+1] = {
        [IP_VS_UDP_S_NORMAL]            =       "UDP",
        [IP_VS_UDP_S_LAST]              =       "BUG!",
};


static int
udp_set_state_timeout(struct ip_vs_protocol *pp, char *sname, int to)
{
        return ip_vs_set_state_timeout(pp->timeout_table, IP_VS_UDP_S_LAST,
                                       udp_state_name_table, sname, to);
}

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 int
udp_state_transition(struct ip_vs_conn *cp, int direction,
                     const struct sk_buff *skb,
                     struct ip_vs_protocol *pp)
{
        cp->timeout = pp->timeout_table[IP_VS_UDP_S_NORMAL];
        return 1;
}

static void udp_init(struct ip_vs_protocol *pp)
{
        IP_VS_INIT_HASH_TABLE(udp_apps);
        pp->timeout_table = udp_timeouts;
}

static void udp_exit(struct ip_vs_protocol *pp)
{
}


struct ip_vs_protocol ip_vs_protocol_udp = {
        .name =                 "UDP",
        .protocol =             IPPROTO_UDP,
        .num_states =           IP_VS_UDP_S_LAST,
        .dont_defrag =          0,
        .init =                 udp_init,
        .exit =                 udp_exit,
        .conn_schedule =        udp_conn_schedule,
        .conn_in_get =          udp_conn_in_get,
        .conn_out_get =         udp_conn_out_get,
        .snat_handler =         udp_snat_handler,
        .dnat_handler =         udp_dnat_handler,
        .csum_check =           udp_csum_check,
        .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,
        .set_state_timeout =    udp_set_state_timeout,
};

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