/* * IPVS An implementation of the IP virtual server support for the * LINUX operating system. IPVS is now implemented as a module * over the Netfilter framework. IPVS can be used to build a * high-performance and highly available server based on a * cluster of servers. * * Version: $Id: ip_vs_core.c,v 1.34 2003/05/10 03:05:23 wensong Exp $ * * Authors: Wensong Zhang * Peter Kese * Julian Anastasov * * 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. * * The IPVS code for kernel 2.2 was done by Wensong Zhang and Peter Kese, * with changes/fixes from Julian Anastasov, Lars Marowsky-Bree, Horms * and others. * * Changes: * Paul `Rusty' Russell properly handle non-linear skbs * */ #include #include #include #include #include #include #include #include #include /* for icmp_send */ #include #include #include #include EXPORT_SYMBOL(register_ip_vs_scheduler); EXPORT_SYMBOL(unregister_ip_vs_scheduler); EXPORT_SYMBOL(ip_vs_skb_replace); EXPORT_SYMBOL(ip_vs_proto_name); EXPORT_SYMBOL(ip_vs_conn_new); EXPORT_SYMBOL(ip_vs_conn_in_get); EXPORT_SYMBOL(ip_vs_conn_out_get); #ifdef CONFIG_IP_VS_PROTO_TCP EXPORT_SYMBOL(ip_vs_tcp_conn_listen); #endif EXPORT_SYMBOL(ip_vs_conn_put); #ifdef CONFIG_IP_VS_DEBUG EXPORT_SYMBOL(ip_vs_get_debug_level); #endif EXPORT_SYMBOL(ip_vs_make_skb_writable); /* ID used in ICMP lookups */ #define icmp_id(icmph) (((icmph)->un).echo.id) const char *ip_vs_proto_name(unsigned proto) { static char buf[20]; switch (proto) { case IPPROTO_IP: return "IP"; case IPPROTO_UDP: return "UDP"; case IPPROTO_TCP: return "TCP"; case IPPROTO_ICMP: return "ICMP"; default: sprintf(buf, "IP_%d", proto); return buf; } } void ip_vs_init_hash_table(struct list_head *table, int rows) { while (--rows >= 0) INIT_LIST_HEAD(&table[rows]); } static inline void ip_vs_in_stats(struct ip_vs_conn *cp, struct sk_buff *skb) { struct ip_vs_dest *dest = cp->dest; if (dest && (dest->flags & IP_VS_DEST_F_AVAILABLE)) { spin_lock(&dest->stats.lock); dest->stats.inpkts++; dest->stats.inbytes += skb->len; spin_unlock(&dest->stats.lock); spin_lock(&dest->svc->stats.lock); dest->svc->stats.inpkts++; dest->svc->stats.inbytes += skb->len; spin_unlock(&dest->svc->stats.lock); spin_lock(&ip_vs_stats.lock); ip_vs_stats.inpkts++; ip_vs_stats.inbytes += skb->len; spin_unlock(&ip_vs_stats.lock); } } static inline void ip_vs_out_stats(struct ip_vs_conn *cp, struct sk_buff *skb) { struct ip_vs_dest *dest = cp->dest; if (dest && (dest->flags & IP_VS_DEST_F_AVAILABLE)) { spin_lock(&dest->stats.lock); dest->stats.outpkts++; dest->stats.outbytes += skb->len; spin_unlock(&dest->stats.lock); spin_lock(&dest->svc->stats.lock); dest->svc->stats.outpkts++; dest->svc->stats.outbytes += skb->len; spin_unlock(&dest->svc->stats.lock); spin_lock(&ip_vs_stats.lock); ip_vs_stats.outpkts++; ip_vs_stats.outbytes += skb->len; spin_unlock(&ip_vs_stats.lock); } } static inline void ip_vs_conn_stats(struct ip_vs_conn *cp, struct ip_vs_service *svc) { spin_lock(&cp->dest->stats.lock); cp->dest->stats.conns++; spin_unlock(&cp->dest->stats.lock); spin_lock(&svc->stats.lock); svc->stats.conns++; spin_unlock(&svc->stats.lock); spin_lock(&ip_vs_stats.lock); ip_vs_stats.conns++; spin_unlock(&ip_vs_stats.lock); } static inline int ip_vs_set_state(struct ip_vs_conn *cp, int direction, const struct sk_buff *skb, struct ip_vs_protocol *pp) { if (unlikely(!pp->state_transition)) return 0; return pp->state_transition(cp, direction, skb, pp); } int ip_vs_make_skb_writable(struct sk_buff **pskb, int writable_len) { struct sk_buff *skb = *pskb; /* skb is already used, better copy skb and its payload */ if (unlikely(skb_shared(skb) || skb->sk)) goto copy_skb; /* skb data is already used, copy it */ if (unlikely(skb_cloned(skb))) goto copy_data; return pskb_may_pull(skb, writable_len); copy_data: if (unlikely(writable_len > skb->len)) return 0; return !pskb_expand_head(skb, 0, 0, GFP_ATOMIC); copy_skb: if (unlikely(writable_len > skb->len)) return 0; skb = skb_copy(skb, GFP_ATOMIC); if (!skb) return 0; BUG_ON(skb_is_nonlinear(skb)); /* Rest of kernel will get very unhappy if we pass it a suddenly-orphaned skbuff */ if ((*pskb)->sk) skb_set_owner_w(skb, (*pskb)->sk); kfree_skb(*pskb); *pskb = skb; return 1; } /* * IPVS persistent scheduling function * It creates a connection entry according to its template if exists, * or selects a server and creates a connection entry plus a template. * Locking: we are svc user (svc->refcnt), so we hold all dests too * Protocols supported: TCP, UDP */ static struct ip_vs_conn * ip_vs_sched_persist(struct ip_vs_service *svc, const struct sk_buff *skb, __u16 ports[2]) { struct ip_vs_conn *cp = NULL; struct iphdr *iph = skb->nh.iph; struct ip_vs_dest *dest; struct ip_vs_conn *ct; __u16 dport; /* destination port to forward */ __u32 snet; /* source network of the client, after masking */ /* Mask saddr with the netmask to adjust template granularity */ snet = iph->saddr & svc->netmask; IP_VS_DBG(6, "p-schedule: src %u.%u.%u.%u:%u dest %u.%u.%u.%u:%u " "mnet %u.%u.%u.%u\n", NIPQUAD(iph->saddr), ntohs(ports[0]), NIPQUAD(iph->daddr), ntohs(ports[1]), NIPQUAD(snet)); /* * As far as we know, FTP is a very complicated network protocol, and * it uses control connection and data connections. For active FTP, * FTP server initialize data connection to the client, its source port * is often 20. For passive FTP, FTP server tells the clients the port * that it passively listens to, and the client issues the data * connection. In the tunneling or direct routing mode, the load * balancer is on the client-to-server half of connection, the port * number is unknown to the load balancer. So, a conn template like * is created for persistent FTP * service, and a template like * is created for other persistent services. */ if (ports[1] == svc->port) { /* Check if a template already exists */ if (svc->port != FTPPORT) ct = ip_vs_conn_in_get(iph->protocol, snet, 0, iph->daddr, ports[1]); else ct = ip_vs_conn_in_get(iph->protocol, snet, 0, iph->daddr, 0); if (!ct || !ip_vs_check_template(ct)) { /* * No template found or the dest of the connection * template is not available. */ dest = svc->scheduler->schedule(svc, skb); if (dest == NULL) { IP_VS_DBG(1, "p-schedule: no dest found.\n"); return NULL; } /* * Create a template like for non-ftp service, * and * for ftp service. */ if (svc->port != FTPPORT) ct = ip_vs_conn_new(iph->protocol, snet, 0, iph->daddr, ports[1], dest->addr, dest->port, 0, dest); else ct = ip_vs_conn_new(iph->protocol, snet, 0, iph->daddr, 0, dest->addr, 0, 0, dest); if (ct == NULL) return NULL; ct->timeout = svc->timeout; } else { /* set destination with the found template */ dest = ct->dest; } dport = dest->port; } else { /* * Note: persistent fwmark-based services and persistent * port zero service are handled here. * fwmark template: * port zero template: */ if (svc->fwmark) ct = ip_vs_conn_in_get(IPPROTO_IP, snet, 0, htonl(svc->fwmark), 0); else ct = ip_vs_conn_in_get(iph->protocol, snet, 0, iph->daddr, 0); if (!ct || !ip_vs_check_template(ct)) { /* * If it is not persistent port zero, return NULL, * otherwise create a connection template. */ if (svc->port) return NULL; dest = svc->scheduler->schedule(svc, skb); if (dest == NULL) { IP_VS_DBG(1, "p-schedule: no dest found.\n"); return NULL; } /* * Create a template according to the service */ if (svc->fwmark) ct = ip_vs_conn_new(IPPROTO_IP, snet, 0, htonl(svc->fwmark), 0, dest->addr, 0, 0, dest); else ct = ip_vs_conn_new(iph->protocol, snet, 0, iph->daddr, 0, dest->addr, 0, 0, dest); if (ct == NULL) return NULL; ct->timeout = svc->timeout; } else { /* set destination with the found template */ dest = ct->dest; } dport = ports[1]; } /* * Create a new connection according to the template */ cp = ip_vs_conn_new(iph->protocol, iph->saddr, ports[0], iph->daddr, ports[1], dest->addr, dport, 0, dest); if (cp == NULL) { ip_vs_conn_put(ct); return NULL; } /* * Add its control */ ip_vs_control_add(cp, ct); ip_vs_conn_put(ct); ip_vs_conn_stats(cp, svc); return cp; } /* * IPVS main scheduling function * It selects a server according to the virtual service, and * creates a connection entry. * Protocols supported: TCP, UDP */ struct ip_vs_conn * ip_vs_schedule(struct ip_vs_service *svc, const struct sk_buff *skb) { struct ip_vs_conn *cp = NULL; struct iphdr *iph = skb->nh.iph; struct ip_vs_dest *dest; __u16 _ports[2], *pptr; pptr = skb_header_pointer(skb, iph->ihl*4, sizeof(_ports), _ports); if (pptr == NULL) return NULL; /* * Persistent service */ if (svc->flags & IP_VS_SVC_F_PERSISTENT) return ip_vs_sched_persist(svc, skb, pptr); /* * Non-persistent service */ if (!svc->fwmark && pptr[1] != svc->port) { if (!svc->port) IP_VS_ERR("Schedule: port zero only supported " "in persistent services, " "check your ipvs configuration\n"); return NULL; } dest = svc->scheduler->schedule(svc, skb); if (dest == NULL) { IP_VS_DBG(1, "Schedule: no dest found.\n"); return NULL; } /* * Create a connection entry. */ cp = ip_vs_conn_new(iph->protocol, iph->saddr, pptr[0], iph->daddr, pptr[1], dest->addr, dest->port?dest->port:pptr[1], 0, dest); if (cp == NULL) return NULL; IP_VS_DBG(6, "Schedule fwd:%c c:%u.%u.%u.%u:%u v:%u.%u.%u.%u:%u " "d:%u.%u.%u.%u:%u flg:%X cnt:%d\n", ip_vs_fwd_tag(cp), NIPQUAD(cp->caddr), ntohs(cp->cport), NIPQUAD(cp->vaddr), ntohs(cp->vport), NIPQUAD(cp->daddr), ntohs(cp->dport), cp->flags, atomic_read(&cp->refcnt)); ip_vs_conn_stats(cp, svc); return cp; } /* * Pass or drop the packet. * Called by ip_vs_in, when the virtual service is available but * no destination is available for a new connection. */ int ip_vs_leave(struct ip_vs_service *svc, struct sk_buff *skb, struct ip_vs_protocol *pp) { __u16 _ports[2], *pptr; struct iphdr *iph = skb->nh.iph; pptr = skb_header_pointer(skb, iph->ihl*4, sizeof(_ports), _ports); if (pptr == NULL) { ip_vs_service_put(svc); return NF_DROP; } /* if it is fwmark-based service, the cache_bypass sysctl is up and the destination is RTN_UNICAST (and not local), then create a cache_bypass connection entry */ if (sysctl_ip_vs_cache_bypass && svc->fwmark && (inet_addr_type(iph->daddr) == RTN_UNICAST)) { int ret, cs; struct ip_vs_conn *cp; ip_vs_service_put(svc); /* create a new connection entry */ IP_VS_DBG(6, "ip_vs_leave: create a cache_bypass entry\n"); cp = ip_vs_conn_new(iph->protocol, iph->saddr, pptr[0], iph->daddr, pptr[1], 0, 0, IP_VS_CONN_F_BYPASS, NULL); if (cp == NULL) return NF_DROP; /* statistics */ ip_vs_in_stats(cp, skb); /* set state */ cs = ip_vs_set_state(cp, IP_VS_DIR_INPUT, skb, pp); /* transmit the first SYN packet */ ret = cp->packet_xmit(skb, cp, pp); /* do not touch skb anymore */ atomic_inc(&cp->in_pkts); ip_vs_conn_put(cp); return ret; } /* * When the virtual ftp service is presented, packets destined * for other services on the VIP may get here (except services * listed in the ipvs table), pass the packets, because it is * not ipvs job to decide to drop the packets. */ if ((svc->port == FTPPORT) && (pptr[1] != FTPPORT)) { ip_vs_service_put(svc); return NF_ACCEPT; } ip_vs_service_put(svc); /* * Notify the client that the destination is unreachable, and * release the socket buffer. * Since it is in IP layer, the TCP socket is not actually * created, the TCP RST packet cannot be sent, instead that * ICMP_PORT_UNREACH is sent here no matter it is TCP/UDP. --WZ */ icmp_send(skb, ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0); return NF_DROP; } /* * It is hooked before NF_IP_PRI_NAT_SRC at the NF_IP_POST_ROUTING * chain, and is used for VS/NAT. * It detects packets for VS/NAT connections and sends the packets * immediately. This can avoid that iptable_nat mangles the packets * for VS/NAT. */ static unsigned int ip_vs_post_routing(unsigned int hooknum, struct sk_buff **pskb, const struct net_device *in, const struct net_device *out, int (*okfn)(struct sk_buff *)) { if (!((*pskb)->nfcache & NFC_IPVS_PROPERTY)) return NF_ACCEPT; /* The packet was sent from IPVS, exit this chain */ (*okfn)(*pskb); return NF_STOLEN; } u16 ip_vs_checksum_complete(struct sk_buff *skb, int offset) { return (u16) csum_fold(skb_checksum(skb, offset, skb->len - offset, 0)); } static inline struct sk_buff * ip_vs_gather_frags(struct sk_buff *skb, u_int32_t user) { skb = ip_defrag(skb, user); if (skb) ip_send_check(skb->nh.iph); return skb; } /* * Packet has been made sufficiently writable in caller * - inout: 1=in->out, 0=out->in */ void ip_vs_nat_icmp(struct sk_buff *skb, struct ip_vs_protocol *pp, struct ip_vs_conn *cp, int inout) { struct iphdr *iph = skb->nh.iph; unsigned int icmp_offset = iph->ihl*4; struct icmphdr *icmph = (struct icmphdr *)(skb->nh.raw + icmp_offset); struct iphdr *ciph = (struct iphdr *)(icmph + 1); if (inout) { iph->saddr = cp->vaddr; ip_send_check(iph); ciph->daddr = cp->vaddr; ip_send_check(ciph); } else { iph->daddr = cp->daddr; ip_send_check(iph); ciph->saddr = cp->daddr; ip_send_check(ciph); } /* the TCP/UDP port */ if (IPPROTO_TCP == ciph->protocol || IPPROTO_UDP == ciph->protocol) { __u16 *ports = (void *)ciph + ciph->ihl*4; if (inout) ports[1] = cp->vport; else ports[0] = cp->dport; } /* And finally the ICMP checksum */ icmph->checksum = 0; icmph->checksum = ip_vs_checksum_complete(skb, icmp_offset); skb->ip_summed = CHECKSUM_UNNECESSARY; if (inout) IP_VS_DBG_PKT(11, pp, skb, (void *)ciph - (void *)iph, "Forwarding altered outgoing ICMP"); else IP_VS_DBG_PKT(11, pp, skb, (void *)ciph - (void *)iph, "Forwarding altered incoming ICMP"); } /* * Handle ICMP messages in the inside-to-outside direction (outgoing). * Find any that might be relevant, check against existing connections, * forward to the right destination host if relevant. * Currently handles error types - unreachable, quench, ttl exceeded. * (Only used in VS/NAT) */ static int ip_vs_out_icmp(struct sk_buff **pskb, int *related) { struct sk_buff *skb = *pskb; struct iphdr *iph; struct icmphdr _icmph, *ic; struct iphdr _ciph, *cih; /* The ip header contained within the ICMP */ struct ip_vs_conn *cp; struct ip_vs_protocol *pp; unsigned int offset, ihl, verdict; *related = 1; /* reassemble IP fragments */ if (skb->nh.iph->frag_off & __constant_htons(IP_MF|IP_OFFSET)) { skb = ip_vs_gather_frags(skb, IP_DEFRAG_VS_OUT); if (!skb) return NF_STOLEN; *pskb = skb; } iph = skb->nh.iph; offset = ihl = iph->ihl * 4; ic = skb_header_pointer(skb, offset, sizeof(_icmph), &_icmph); if (ic == NULL) return NF_DROP; IP_VS_DBG(12, "Outgoing ICMP (%d,%d) %u.%u.%u.%u->%u.%u.%u.%u\n", ic->type, ntohs(icmp_id(ic)), NIPQUAD(iph->saddr), NIPQUAD(iph->daddr)); /* * Work through seeing if this is for us. * These checks are supposed to be in an order that means easy * things are checked first to speed up processing.... however * this means that some packets will manage to get a long way * down this stack and then be rejected, but that's life. */ if ((ic->type != ICMP_DEST_UNREACH) && (ic->type != ICMP_SOURCE_QUENCH) && (ic->type != ICMP_TIME_EXCEEDED)) { *related = 0; return NF_ACCEPT; } /* Now find the contained IP header */ offset += sizeof(_icmph); cih = skb_header_pointer(skb, offset, sizeof(_ciph), &_ciph); if (cih == NULL) return NF_ACCEPT; /* The packet looks wrong, ignore */ pp = ip_vs_proto_get(cih->protocol); if (!pp) return NF_ACCEPT; /* Is the embedded protocol header present? */ if (unlikely(cih->frag_off & __constant_htons(IP_OFFSET) && pp->dont_defrag)) return NF_ACCEPT; IP_VS_DBG_PKT(11, pp, skb, offset, "Checking outgoing ICMP for"); offset += cih->ihl * 4; /* The embedded headers contain source and dest in reverse order */ cp = pp->conn_out_get(skb, pp, cih, offset, 1); if (!cp) return NF_ACCEPT; verdict = NF_DROP; if (IP_VS_FWD_METHOD(cp) != 0) { IP_VS_ERR("shouldn't reach here, because the box is on the" "half connection in the tun/dr module.\n"); } /* Ensure the checksum is correct */ if (skb->ip_summed != CHECKSUM_UNNECESSARY && ip_vs_checksum_complete(skb, ihl)) { /* Failed checksum! */ IP_VS_DBG(1, "Forward ICMP: failed checksum from %d.%d.%d.%d!\n", NIPQUAD(iph->saddr)); goto out; } if (IPPROTO_TCP == cih->protocol || IPPROTO_UDP == cih->protocol) offset += 2 * sizeof(__u16); if (!ip_vs_make_skb_writable(pskb, offset)) goto out; skb = *pskb; ip_vs_nat_icmp(skb, pp, cp, 1); /* do the statistics and put it back */ ip_vs_out_stats(cp, skb); skb->nfcache |= NFC_IPVS_PROPERTY; verdict = NF_ACCEPT; out: __ip_vs_conn_put(cp); return verdict; } static inline int is_tcp_reset(const struct sk_buff *skb) { struct tcphdr _tcph, *th; th = skb_header_pointer(skb, skb->nh.iph->ihl * 4, sizeof(_tcph), &_tcph); if (th == NULL) return 0; return th->rst; } /* * It is hooked at the NF_IP_FORWARD chain, used only for VS/NAT. * Check if outgoing packet belongs to the established ip_vs_conn, * rewrite addresses of the packet and send it on its way... */ static unsigned int ip_vs_out(unsigned int hooknum, struct sk_buff **pskb, const struct net_device *in, const struct net_device *out, int (*okfn)(struct sk_buff *)) { struct sk_buff *skb = *pskb; struct iphdr *iph; struct ip_vs_protocol *pp; struct ip_vs_conn *cp; int ihl; EnterFunction(11); if (skb->nfcache & NFC_IPVS_PROPERTY) return NF_ACCEPT; iph = skb->nh.iph; if (unlikely(iph->protocol == IPPROTO_ICMP)) { int related, verdict = ip_vs_out_icmp(pskb, &related); if (related) return verdict; skb = *pskb; iph = skb->nh.iph; } pp = ip_vs_proto_get(iph->protocol); if (unlikely(!pp)) return NF_ACCEPT; /* reassemble IP fragments */ if (unlikely(iph->frag_off & __constant_htons(IP_MF|IP_OFFSET) && !pp->dont_defrag)) { skb = ip_vs_gather_frags(skb, IP_DEFRAG_VS_OUT); if (!skb) return NF_STOLEN; iph = skb->nh.iph; *pskb = skb; } ihl = iph->ihl << 2; /* * Check if the packet belongs to an existing entry */ cp = pp->conn_out_get(skb, pp, iph, ihl, 0); if (unlikely(!cp)) { if (sysctl_ip_vs_nat_icmp_send && (pp->protocol == IPPROTO_TCP || pp->protocol == IPPROTO_UDP)) { __u16 _ports[2], *pptr; pptr = skb_header_pointer(skb, ihl, sizeof(_ports), _ports); if (pptr == NULL) return NF_ACCEPT; /* Not for me */ if (ip_vs_lookup_real_service(iph->protocol, iph->saddr, pptr[0])) { /* * Notify the real server: there is no * existing entry if it is not RST * packet or not TCP packet. */ if (iph->protocol != IPPROTO_TCP || !is_tcp_reset(skb)) { icmp_send(skb,ICMP_DEST_UNREACH, ICMP_PORT_UNREACH, 0); return NF_DROP; } } } IP_VS_DBG_PKT(12, pp, skb, 0, "packet continues traversal as normal"); return NF_ACCEPT; } IP_VS_DBG_PKT(11, pp, skb, 0, "Outgoing packet"); if (!ip_vs_make_skb_writable(pskb, ihl)) goto drop; /* mangle the packet */ if (pp->snat_handler && !pp->snat_handler(pskb, pp, cp)) goto drop; skb = *pskb; skb->nh.iph->saddr = cp->vaddr; ip_send_check(skb->nh.iph); IP_VS_DBG_PKT(10, pp, skb, 0, "After SNAT"); ip_vs_out_stats(cp, skb); ip_vs_set_state(cp, IP_VS_DIR_OUTPUT, skb, pp); ip_vs_conn_put(cp); skb->nfcache |= NFC_IPVS_PROPERTY; LeaveFunction(11); return NF_ACCEPT; drop: ip_vs_conn_put(cp); kfree_skb(*pskb); return NF_STOLEN; } /* * Handle ICMP messages in the outside-to-inside direction (incoming). * Find any that might be relevant, check against existing connections, * forward to the right destination host if relevant. * Currently handles error types - unreachable, quench, ttl exceeded. */ static int ip_vs_in_icmp(struct sk_buff **pskb, int *related, unsigned int hooknum) { struct sk_buff *skb = *pskb; struct iphdr *iph; struct icmphdr _icmph, *ic; struct iphdr _ciph, *cih; /* The ip header contained within the ICMP */ struct ip_vs_conn *cp; struct ip_vs_protocol *pp; unsigned int offset, ihl, verdict; *related = 1; /* reassemble IP fragments */ if (skb->nh.iph->frag_off & __constant_htons(IP_MF|IP_OFFSET)) { skb = ip_vs_gather_frags(skb, hooknum == NF_IP_LOCAL_IN ? IP_DEFRAG_VS_IN : IP_DEFRAG_VS_FWD); if (!skb) return NF_STOLEN; *pskb = skb; } iph = skb->nh.iph; offset = ihl = iph->ihl * 4; ic = skb_header_pointer(skb, offset, sizeof(_icmph), &_icmph); if (ic == NULL) return NF_DROP; IP_VS_DBG(12, "Incoming ICMP (%d,%d) %u.%u.%u.%u->%u.%u.%u.%u\n", ic->type, ntohs(icmp_id(ic)), NIPQUAD(iph->saddr), NIPQUAD(iph->daddr)); /* * Work through seeing if this is for us. * These checks are supposed to be in an order that means easy * things are checked first to speed up processing.... however * this means that some packets will manage to get a long way * down this stack and then be rejected, but that's life. */ if ((ic->type != ICMP_DEST_UNREACH) && (ic->type != ICMP_SOURCE_QUENCH) && (ic->type != ICMP_TIME_EXCEEDED)) { *related = 0; return NF_ACCEPT; } /* Now find the contained IP header */ offset += sizeof(_icmph); cih = skb_header_pointer(skb, offset, sizeof(_ciph), &_ciph); if (cih == NULL) return NF_ACCEPT; /* The packet looks wrong, ignore */ pp = ip_vs_proto_get(cih->protocol); if (!pp) return NF_ACCEPT; /* Is the embedded protocol header present? */ if (unlikely(cih->frag_off & __constant_htons(IP_OFFSET) && pp->dont_defrag)) return NF_ACCEPT; IP_VS_DBG_PKT(11, pp, skb, offset, "Checking incoming ICMP for"); offset += cih->ihl * 4; /* The embedded headers contain source and dest in reverse order */ cp = pp->conn_in_get(skb, pp, cih, offset, 1); if (!cp) return NF_ACCEPT; verdict = NF_DROP; /* Ensure the checksum is correct */ if (skb->ip_summed != CHECKSUM_UNNECESSARY && ip_vs_checksum_complete(skb, ihl)) { /* Failed checksum! */ IP_VS_DBG(1, "Incoming ICMP: failed checksum from %d.%d.%d.%d!\n", NIPQUAD(iph->saddr)); goto out; } /* do the statistics and put it back */ ip_vs_in_stats(cp, skb); if (IPPROTO_TCP == cih->protocol || IPPROTO_UDP == cih->protocol) offset += 2 * sizeof(__u16); verdict = ip_vs_icmp_xmit(skb, cp, pp, offset); /* do not touch skb anymore */ out: __ip_vs_conn_put(cp); return verdict; } /* * Check if it's for virtual services, look it up, * and send it on its way... */ static unsigned int ip_vs_in(unsigned int hooknum, struct sk_buff **pskb, const struct net_device *in, const struct net_device *out, int (*okfn)(struct sk_buff *)) { struct sk_buff *skb = *pskb; struct iphdr *iph; struct ip_vs_protocol *pp; struct ip_vs_conn *cp; int ret, restart; int ihl; /* * Big tappo: only PACKET_HOST (neither loopback nor mcasts) * ... don't know why 1st test DOES NOT include 2nd (?) */ if (unlikely(skb->pkt_type != PACKET_HOST || skb->dev == &loopback_dev || skb->sk)) { IP_VS_DBG(12, "packet type=%d proto=%d daddr=%d.%d.%d.%d ignored\n", skb->pkt_type, skb->nh.iph->protocol, NIPQUAD(skb->nh.iph->daddr)); return NF_ACCEPT; } iph = skb->nh.iph; if (unlikely(iph->protocol == IPPROTO_ICMP)) { int related, verdict = ip_vs_in_icmp(pskb, &related, hooknum); if (related) return verdict; skb = *pskb; iph = skb->nh.iph; } /* Protocol supported? */ pp = ip_vs_proto_get(iph->protocol); if (unlikely(!pp)) return NF_ACCEPT; ihl = iph->ihl << 2; /* * Check if the packet belongs to an existing connection entry */ cp = pp->conn_in_get(skb, pp, iph, ihl, 0); if (unlikely(!cp)) { int v; if (!pp->conn_schedule(skb, pp, &v, &cp)) return v; } if (unlikely(!cp)) { /* sorry, all this trouble for a no-hit :) */ IP_VS_DBG_PKT(12, pp, skb, 0, "packet continues traversal as normal"); return NF_ACCEPT; } IP_VS_DBG_PKT(11, pp, skb, 0, "Incoming packet"); /* Check the server status */ if (cp->dest && !(cp->dest->flags & IP_VS_DEST_F_AVAILABLE)) { /* the destination server is not available */ if (sysctl_ip_vs_expire_nodest_conn) { /* try to expire the connection immediately */ ip_vs_conn_expire_now(cp); } else { /* don't restart its timer, and silently drop the packet. */ __ip_vs_conn_put(cp); } return NF_DROP; } ip_vs_in_stats(cp, skb); restart = ip_vs_set_state(cp, IP_VS_DIR_INPUT, skb, pp); if (cp->packet_xmit) ret = cp->packet_xmit(skb, cp, pp); /* do not touch skb anymore */ else { IP_VS_DBG_RL("warning: packet_xmit is null"); ret = NF_ACCEPT; } /* increase its packet counter and check if it is needed to be synchronized */ atomic_inc(&cp->in_pkts); if ((ip_vs_sync_state & IP_VS_STATE_MASTER) && (cp->protocol != IPPROTO_TCP || cp->state == IP_VS_TCP_S_ESTABLISHED) && (atomic_read(&cp->in_pkts) % sysctl_ip_vs_sync_threshold[1] == sysctl_ip_vs_sync_threshold[0])) ip_vs_sync_conn(cp); ip_vs_conn_put(cp); return ret; } /* * It is hooked at the NF_IP_FORWARD chain, in order to catch ICMP * related packets destined for 0.0.0.0/0. * When fwmark-based virtual service is used, such as transparent * cache cluster, TCP packets can be marked and routed to ip_vs_in, * but ICMP destined for 0.0.0.0/0 cannot not be easily marked and * sent to ip_vs_in_icmp. So, catch them at the NF_IP_FORWARD chain * and send them to ip_vs_in_icmp. */ static unsigned int ip_vs_forward_icmp(unsigned int hooknum, struct sk_buff **pskb, const struct net_device *in, const struct net_device *out, int (*okfn)(struct sk_buff *)) { int r; if ((*pskb)->nh.iph->protocol != IPPROTO_ICMP) return NF_ACCEPT; return ip_vs_in_icmp(pskb, &r, hooknum); } /* After packet filtering, forward packet through VS/DR, VS/TUN, or VS/NAT(change destination), so that filtering rules can be applied to IPVS. */ static struct nf_hook_ops ip_vs_in_ops = { .hook = ip_vs_in, .owner = THIS_MODULE, .pf = PF_INET, .hooknum = NF_IP_LOCAL_IN, .priority = 100, }; /* After packet filtering, change source only for VS/NAT */ static struct nf_hook_ops ip_vs_out_ops = { .hook = ip_vs_out, .owner = THIS_MODULE, .pf = PF_INET, .hooknum = NF_IP_FORWARD, .priority = 100, }; /* After packet filtering (but before ip_vs_out_icmp), catch icmp destined for 0.0.0.0/0, which is for incoming IPVS connections */ static struct nf_hook_ops ip_vs_forward_icmp_ops = { .hook = ip_vs_forward_icmp, .owner = THIS_MODULE, .pf = PF_INET, .hooknum = NF_IP_FORWARD, .priority = 99, }; /* Before the netfilter connection tracking, exit from POST_ROUTING */ static struct nf_hook_ops ip_vs_post_routing_ops = { .hook = ip_vs_post_routing, .owner = THIS_MODULE, .pf = PF_INET, .hooknum = NF_IP_POST_ROUTING, .priority = NF_IP_PRI_NAT_SRC-1, }; /* * Initialize IP Virtual Server */ static int __init ip_vs_init(void) { int ret; ret = ip_vs_control_init(); if (ret < 0) { IP_VS_ERR("can't setup control.\n"); goto cleanup_nothing; } ip_vs_protocol_init(); ret = ip_vs_app_init(); if (ret < 0) { IP_VS_ERR("can't setup application helper.\n"); goto cleanup_protocol; } ret = ip_vs_conn_init(); if (ret < 0) { IP_VS_ERR("can't setup connection table.\n"); goto cleanup_app; } ret = nf_register_hook(&ip_vs_in_ops); if (ret < 0) { IP_VS_ERR("can't register in hook.\n"); goto cleanup_conn; } ret = nf_register_hook(&ip_vs_out_ops); if (ret < 0) { IP_VS_ERR("can't register out hook.\n"); goto cleanup_inops; } ret = nf_register_hook(&ip_vs_post_routing_ops); if (ret < 0) { IP_VS_ERR("can't register post_routing hook.\n"); goto cleanup_outops; } ret = nf_register_hook(&ip_vs_forward_icmp_ops); if (ret < 0) { IP_VS_ERR("can't register forward_icmp hook.\n"); goto cleanup_postroutingops; } IP_VS_INFO("ipvs loaded.\n"); return ret; cleanup_postroutingops: nf_unregister_hook(&ip_vs_post_routing_ops); cleanup_outops: nf_unregister_hook(&ip_vs_out_ops); cleanup_inops: nf_unregister_hook(&ip_vs_in_ops); cleanup_conn: ip_vs_conn_cleanup(); cleanup_app: ip_vs_app_cleanup(); cleanup_protocol: ip_vs_protocol_cleanup(); ip_vs_control_cleanup(); cleanup_nothing: return ret; } static void __exit ip_vs_cleanup(void) { nf_unregister_hook(&ip_vs_forward_icmp_ops); nf_unregister_hook(&ip_vs_post_routing_ops); nf_unregister_hook(&ip_vs_out_ops); nf_unregister_hook(&ip_vs_in_ops); ip_vs_conn_cleanup(); ip_vs_app_cleanup(); ip_vs_protocol_cleanup(); ip_vs_control_cleanup(); IP_VS_INFO("ipvs unloaded.\n"); } module_init(ip_vs_init); module_exit(ip_vs_cleanup); MODULE_LICENSE("GPL");