/* * ip_vs_xmit.c: various packet transmitters for IPVS * * Authors: Wensong Zhang * 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. * * Changes: * * Description of forwarding methods: * - all transmitters are called from LOCAL_IN (remote clients) and * LOCAL_OUT (local clients) but for ICMP can be called from FORWARD * - not all connections have destination server, for example, * connections in backup server when fwmark is used * - bypass connections use daddr from packet * - we can use dst without ref while sending in RCU section, we use * ref when returning NF_ACCEPT for NAT-ed packet via loopback * LOCAL_OUT rules: * - skb->dev is NULL, skb->protocol is not set (both are set in POST_ROUTING) * - skb->pkt_type is not set yet * - the only place where we can see skb->sk != NULL */ #define KMSG_COMPONENT "IPVS" #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt #include #include #include /* for tcphdr */ #include #include /* for csum_tcpudp_magic */ #include #include /* for icmp_send */ #include /* for ip_route_output */ #include #include #include #include #include #include #include #include enum { IP_VS_RT_MODE_LOCAL = 1, /* Allow local dest */ IP_VS_RT_MODE_NON_LOCAL = 2, /* Allow non-local dest */ IP_VS_RT_MODE_RDR = 4, /* Allow redirect from remote daddr to * local */ IP_VS_RT_MODE_CONNECT = 8, /* Always bind route to saddr */ IP_VS_RT_MODE_KNOWN_NH = 16,/* Route via remote addr */ IP_VS_RT_MODE_TUNNEL = 32,/* Tunnel mode */ }; static inline struct ip_vs_dest_dst *ip_vs_dest_dst_alloc(void) { return kmalloc(sizeof(struct ip_vs_dest_dst), GFP_ATOMIC); } static inline void ip_vs_dest_dst_free(struct ip_vs_dest_dst *dest_dst) { kfree(dest_dst); } /* * Destination cache to speed up outgoing route lookup */ static inline void __ip_vs_dst_set(struct ip_vs_dest *dest, struct ip_vs_dest_dst *dest_dst, struct dst_entry *dst, u32 dst_cookie) { struct ip_vs_dest_dst *old; old = rcu_dereference_protected(dest->dest_dst, lockdep_is_held(&dest->dst_lock)); if (dest_dst) { dest_dst->dst_cache = dst; dest_dst->dst_cookie = dst_cookie; } rcu_assign_pointer(dest->dest_dst, dest_dst); if (old) call_rcu(&old->rcu_head, ip_vs_dest_dst_rcu_free); } static inline struct ip_vs_dest_dst * __ip_vs_dst_check(struct ip_vs_dest *dest) { struct ip_vs_dest_dst *dest_dst = rcu_dereference(dest->dest_dst); struct dst_entry *dst; if (!dest_dst) return NULL; dst = dest_dst->dst_cache; if (dst->obsolete && dst->ops->check(dst, dest_dst->dst_cookie) == NULL) return NULL; return dest_dst; } static inline bool __mtu_check_toobig_v6(const struct sk_buff *skb, u32 mtu) { if (IP6CB(skb)->frag_max_size) { /* frag_max_size tell us that, this packet have been * defragmented by netfilter IPv6 conntrack module. */ if (IP6CB(skb)->frag_max_size > mtu) return true; /* largest fragment violate MTU */ } else if (skb->len > mtu && !skb_is_gso(skb)) { return true; /* Packet size violate MTU size */ } return false; } /* Get route to daddr, update *saddr, optionally bind route to saddr */ static struct rtable *do_output_route4(struct net *net, __be32 daddr, int rt_mode, __be32 *saddr) { struct flowi4 fl4; struct rtable *rt; int loop = 0; memset(&fl4, 0, sizeof(fl4)); fl4.daddr = daddr; fl4.flowi4_flags = (rt_mode & IP_VS_RT_MODE_KNOWN_NH) ? FLOWI_FLAG_KNOWN_NH : 0; retry: rt = ip_route_output_key(net, &fl4); if (IS_ERR(rt)) { /* Invalid saddr ? */ if (PTR_ERR(rt) == -EINVAL && *saddr && rt_mode & IP_VS_RT_MODE_CONNECT && !loop) { *saddr = 0; flowi4_update_output(&fl4, 0, 0, daddr, 0); goto retry; } IP_VS_DBG_RL("ip_route_output error, dest: %pI4\n", &daddr); return NULL; } else if (!*saddr && rt_mode & IP_VS_RT_MODE_CONNECT && fl4.saddr) { ip_rt_put(rt); *saddr = fl4.saddr; flowi4_update_output(&fl4, 0, 0, daddr, fl4.saddr); loop++; goto retry; } *saddr = fl4.saddr; return rt; } #ifdef CONFIG_IP_VS_IPV6 static inline int __ip_vs_is_local_route6(struct rt6_info *rt) { return rt->dst.dev && rt->dst.dev->flags & IFF_LOOPBACK; } #endif static inline bool crosses_local_route_boundary(int skb_af, struct sk_buff *skb, int rt_mode, bool new_rt_is_local) { bool rt_mode_allow_local = !!(rt_mode & IP_VS_RT_MODE_LOCAL); bool rt_mode_allow_non_local = !!(rt_mode & IP_VS_RT_MODE_LOCAL); bool rt_mode_allow_redirect = !!(rt_mode & IP_VS_RT_MODE_RDR); bool source_is_loopback; bool old_rt_is_local; #ifdef CONFIG_IP_VS_IPV6 if (skb_af == AF_INET6) { int addr_type = ipv6_addr_type(&ipv6_hdr(skb)->saddr); source_is_loopback = (!skb->dev || skb->dev->flags & IFF_LOOPBACK) && (addr_type & IPV6_ADDR_LOOPBACK); old_rt_is_local = __ip_vs_is_local_route6( (struct rt6_info *)skb_dst(skb)); } else #endif { source_is_loopback = ipv4_is_loopback(ip_hdr(skb)->saddr); old_rt_is_local = skb_rtable(skb)->rt_flags & RTCF_LOCAL; } if (unlikely(new_rt_is_local)) { if (!rt_mode_allow_local) return true; if (!rt_mode_allow_redirect && !old_rt_is_local) return true; } else { if (!rt_mode_allow_non_local) return true; if (source_is_loopback) return true; } return false; } static inline void maybe_update_pmtu(int skb_af, struct sk_buff *skb, int mtu) { struct sock *sk = skb->sk; struct rtable *ort = skb_rtable(skb); if (!skb->dev && sk && sk_fullsock(sk)) ort->dst.ops->update_pmtu(&ort->dst, sk, NULL, mtu); } static inline bool ensure_mtu_is_adequate(int skb_af, int rt_mode, struct ip_vs_iphdr *ipvsh, struct sk_buff *skb, int mtu) { #ifdef CONFIG_IP_VS_IPV6 if (skb_af == AF_INET6) { struct net *net = dev_net(skb_dst(skb)->dev); if (unlikely(__mtu_check_toobig_v6(skb, mtu))) { if (!skb->dev) skb->dev = net->loopback_dev; /* only send ICMP too big on first fragment */ if (!ipvsh->fragoffs) icmpv6_send(skb, ICMPV6_PKT_TOOBIG, 0, mtu); IP_VS_DBG(1, "frag needed for %pI6c\n", &ipv6_hdr(skb)->saddr); return false; } } else #endif { struct netns_ipvs *ipvs = net_ipvs(skb_net(skb)); /* If we're going to tunnel the packet and pmtu discovery * is disabled, we'll just fragment it anyway */ if ((rt_mode & IP_VS_RT_MODE_TUNNEL) && !sysctl_pmtu_disc(ipvs)) return true; if (unlikely(ip_hdr(skb)->frag_off & htons(IP_DF) && skb->len > mtu && !skb_is_gso(skb))) { icmp_send(skb, ICMP_DEST_UNREACH, ICMP_FRAG_NEEDED, htonl(mtu)); IP_VS_DBG(1, "frag needed for %pI4\n", &ip_hdr(skb)->saddr); return false; } } return true; } /* Get route to destination or remote server */ static int __ip_vs_get_out_rt(int skb_af, struct sk_buff *skb, struct ip_vs_dest *dest, __be32 daddr, int rt_mode, __be32 *ret_saddr, struct ip_vs_iphdr *ipvsh) { struct net *net = dev_net(skb_dst(skb)->dev); struct ip_vs_dest_dst *dest_dst; struct rtable *rt; /* Route to the other host */ int mtu; int local, noref = 1; if (dest) { dest_dst = __ip_vs_dst_check(dest); if (likely(dest_dst)) rt = (struct rtable *) dest_dst->dst_cache; else { dest_dst = ip_vs_dest_dst_alloc(); spin_lock_bh(&dest->dst_lock); if (!dest_dst) { __ip_vs_dst_set(dest, NULL, NULL, 0); spin_unlock_bh(&dest->dst_lock); goto err_unreach; } rt = do_output_route4(net, dest->addr.ip, rt_mode, &dest_dst->dst_saddr.ip); if (!rt) { __ip_vs_dst_set(dest, NULL, NULL, 0); spin_unlock_bh(&dest->dst_lock); ip_vs_dest_dst_free(dest_dst); goto err_unreach; } __ip_vs_dst_set(dest, dest_dst, &rt->dst, 0); spin_unlock_bh(&dest->dst_lock); IP_VS_DBG(10, "new dst %pI4, src %pI4, refcnt=%d\n", &dest->addr.ip, &dest_dst->dst_saddr.ip, atomic_read(&rt->dst.__refcnt)); } if (ret_saddr) *ret_saddr = dest_dst->dst_saddr.ip; } else { __be32 saddr = htonl(INADDR_ANY); noref = 0; /* For such unconfigured boxes avoid many route lookups * for performance reasons because we do not remember saddr */ rt_mode &= ~IP_VS_RT_MODE_CONNECT; rt = do_output_route4(net, daddr, rt_mode, &saddr); if (!rt) goto err_unreach; if (ret_saddr) *ret_saddr = saddr; } local = (rt->rt_flags & RTCF_LOCAL) ? 1 : 0; if (unlikely(crosses_local_route_boundary(skb_af, skb, rt_mode, local))) { IP_VS_DBG_RL("We are crossing local and non-local addresses" " daddr=%pI4\n", &daddr); goto err_put; } if (unlikely(local)) { /* skb to local stack, preserve old route */ if (!noref) ip_rt_put(rt); return local; } if (likely(!(rt_mode & IP_VS_RT_MODE_TUNNEL))) { mtu = dst_mtu(&rt->dst); } else { mtu = dst_mtu(&rt->dst) - sizeof(struct iphdr); if (mtu < 68) { IP_VS_DBG_RL("%s(): mtu less than 68\n", __func__); goto err_put; } maybe_update_pmtu(skb_af, skb, mtu); } if (!ensure_mtu_is_adequate(skb_af, rt_mode, ipvsh, skb, mtu)) goto err_put; skb_dst_drop(skb); if (noref) { if (!local) skb_dst_set_noref(skb, &rt->dst); else skb_dst_set(skb, dst_clone(&rt->dst)); } else skb_dst_set(skb, &rt->dst); return local; err_put: if (!noref) ip_rt_put(rt); return -1; err_unreach: dst_link_failure(skb); return -1; } #ifdef CONFIG_IP_VS_IPV6 static struct dst_entry * __ip_vs_route_output_v6(struct net *net, struct in6_addr *daddr, struct in6_addr *ret_saddr, int do_xfrm) { struct dst_entry *dst; struct flowi6 fl6 = { .daddr = *daddr, }; dst = ip6_route_output(net, NULL, &fl6); if (dst->error) goto out_err; if (!ret_saddr) return dst; if (ipv6_addr_any(&fl6.saddr) && ipv6_dev_get_saddr(net, ip6_dst_idev(dst)->dev, &fl6.daddr, 0, &fl6.saddr) < 0) goto out_err; if (do_xfrm) { dst = xfrm_lookup(net, dst, flowi6_to_flowi(&fl6), NULL, 0); if (IS_ERR(dst)) { dst = NULL; goto out_err; } } *ret_saddr = fl6.saddr; return dst; out_err: dst_release(dst); IP_VS_DBG_RL("ip6_route_output error, dest: %pI6\n", daddr); return NULL; } /* * Get route to destination or remote server */ static int __ip_vs_get_out_rt_v6(int skb_af, struct sk_buff *skb, struct ip_vs_dest *dest, struct in6_addr *daddr, struct in6_addr *ret_saddr, struct ip_vs_iphdr *ipvsh, int do_xfrm, int rt_mode) { struct net *net = dev_net(skb_dst(skb)->dev); struct ip_vs_dest_dst *dest_dst; struct rt6_info *rt; /* Route to the other host */ struct dst_entry *dst; int mtu; int local, noref = 1; if (dest) { dest_dst = __ip_vs_dst_check(dest); if (likely(dest_dst)) rt = (struct rt6_info *) dest_dst->dst_cache; else { u32 cookie; dest_dst = ip_vs_dest_dst_alloc(); spin_lock_bh(&dest->dst_lock); if (!dest_dst) { __ip_vs_dst_set(dest, NULL, NULL, 0); spin_unlock_bh(&dest->dst_lock); goto err_unreach; } dst = __ip_vs_route_output_v6(net, &dest->addr.in6, &dest_dst->dst_saddr.in6, do_xfrm); if (!dst) { __ip_vs_dst_set(dest, NULL, NULL, 0); spin_unlock_bh(&dest->dst_lock); ip_vs_dest_dst_free(dest_dst); goto err_unreach; } rt = (struct rt6_info *) dst; cookie = rt->rt6i_node ? rt->rt6i_node->fn_sernum : 0; __ip_vs_dst_set(dest, dest_dst, &rt->dst, cookie); spin_unlock_bh(&dest->dst_lock); IP_VS_DBG(10, "new dst %pI6, src %pI6, refcnt=%d\n", &dest->addr.in6, &dest_dst->dst_saddr.in6, atomic_read(&rt->dst.__refcnt)); } if (ret_saddr) *ret_saddr = dest_dst->dst_saddr.in6; } else { noref = 0; dst = __ip_vs_route_output_v6(net, daddr, ret_saddr, do_xfrm); if (!dst) goto err_unreach; rt = (struct rt6_info *) dst; } local = __ip_vs_is_local_route6(rt); if (unlikely(crosses_local_route_boundary(skb_af, skb, rt_mode, local))) { IP_VS_DBG_RL("We are crossing local and non-local addresses" " daddr=%pI6\n", daddr); goto err_put; } if (unlikely(local)) { /* skb to local stack, preserve old route */ if (!noref) dst_release(&rt->dst); return local; } /* MTU checking */ if (likely(!(rt_mode & IP_VS_RT_MODE_TUNNEL))) mtu = dst_mtu(&rt->dst); else { mtu = dst_mtu(&rt->dst) - sizeof(struct ipv6hdr); if (mtu < IPV6_MIN_MTU) { IP_VS_DBG_RL("%s(): mtu less than %d\n", __func__, IPV6_MIN_MTU); goto err_put; } maybe_update_pmtu(skb_af, skb, mtu); } if (!ensure_mtu_is_adequate(skb_af, rt_mode, ipvsh, skb, mtu)) goto err_put; skb_dst_drop(skb); if (noref) { if (!local) skb_dst_set_noref(skb, &rt->dst); else skb_dst_set(skb, dst_clone(&rt->dst)); } else skb_dst_set(skb, &rt->dst); return local; err_put: if (!noref) dst_release(&rt->dst); return -1; err_unreach: dst_link_failure(skb); return -1; } #endif /* return NF_ACCEPT to allow forwarding or other NF_xxx on error */ static inline int ip_vs_tunnel_xmit_prepare(struct sk_buff *skb, struct ip_vs_conn *cp) { int ret = NF_ACCEPT; skb->ipvs_property = 1; if (unlikely(cp->flags & IP_VS_CONN_F_NFCT)) ret = ip_vs_confirm_conntrack(skb); if (ret == NF_ACCEPT) { nf_reset(skb); skb_forward_csum(skb); if (!skb->sk) skb_sender_cpu_clear(skb); } return ret; } /* In the event of a remote destination, it's possible that we would have * matches against an old socket (particularly a TIME-WAIT socket). This * causes havoc down the line (ip_local_out et. al. expect regular sockets * and invalid memory accesses will happen) so simply drop the association * in this case. */ static inline void ip_vs_drop_early_demux_sk(struct sk_buff *skb) { /* If dev is set, the packet came from the LOCAL_IN callback and * not from a local TCP socket. */ if (skb->dev) skb_orphan(skb); } /* return NF_STOLEN (sent) or NF_ACCEPT if local=1 (not sent) */ static inline int ip_vs_nat_send_or_cont(int pf, struct sk_buff *skb, struct ip_vs_conn *cp, int local) { int ret = NF_STOLEN; skb->ipvs_property = 1; if (likely(!(cp->flags & IP_VS_CONN_F_NFCT))) ip_vs_notrack(skb); else ip_vs_update_conntrack(skb, cp, 1); /* Remove the early_demux association unless it's bound for the * exact same port and address on this host after translation. */ if (!local || cp->vport != cp->dport || !ip_vs_addr_equal(cp->af, &cp->vaddr, &cp->daddr)) ip_vs_drop_early_demux_sk(skb); if (!local) { skb_forward_csum(skb); if (!skb->sk) skb_sender_cpu_clear(skb); NF_HOOK(pf, NF_INET_LOCAL_OUT, NULL, skb, NULL, skb_dst(skb)->dev, dst_output_sk); } else ret = NF_ACCEPT; return ret; } /* return NF_STOLEN (sent) or NF_ACCEPT if local=1 (not sent) */ static inline int ip_vs_send_or_cont(int pf, struct sk_buff *skb, struct ip_vs_conn *cp, int local) { int ret = NF_STOLEN; skb->ipvs_property = 1; if (likely(!(cp->flags & IP_VS_CONN_F_NFCT))) ip_vs_notrack(skb); if (!local) { ip_vs_drop_early_demux_sk(skb); skb_forward_csum(skb); if (!skb->sk) skb_sender_cpu_clear(skb); NF_HOOK(pf, NF_INET_LOCAL_OUT, NULL, skb, NULL, skb_dst(skb)->dev, dst_output_sk); } else ret = NF_ACCEPT; return ret; } /* * NULL transmitter (do nothing except return NF_ACCEPT) */ int ip_vs_null_xmit(struct sk_buff *skb, struct ip_vs_conn *cp, struct ip_vs_protocol *pp, struct ip_vs_iphdr *ipvsh) { /* we do not touch skb and do not need pskb ptr */ return ip_vs_send_or_cont(NFPROTO_IPV4, skb, cp, 1); } /* * Bypass transmitter * Let packets bypass the destination when the destination is not * available, it may be only used in transparent cache cluster. */ int ip_vs_bypass_xmit(struct sk_buff *skb, struct ip_vs_conn *cp, struct ip_vs_protocol *pp, struct ip_vs_iphdr *ipvsh) { struct iphdr *iph = ip_hdr(skb); EnterFunction(10); rcu_read_lock(); if (__ip_vs_get_out_rt(cp->af, skb, NULL, iph->daddr, IP_VS_RT_MODE_NON_LOCAL, NULL, ipvsh) < 0) goto tx_error; ip_send_check(iph); /* Another hack: avoid icmp_send in ip_fragment */ skb->ignore_df = 1; ip_vs_send_or_cont(NFPROTO_IPV4, skb, cp, 0); rcu_read_unlock(); LeaveFunction(10); return NF_STOLEN; tx_error: kfree_skb(skb); rcu_read_unlock(); LeaveFunction(10); return NF_STOLEN; } #ifdef CONFIG_IP_VS_IPV6 int ip_vs_bypass_xmit_v6(struct sk_buff *skb, struct ip_vs_conn *cp, struct ip_vs_protocol *pp, struct ip_vs_iphdr *ipvsh) { EnterFunction(10); rcu_read_lock(); if (__ip_vs_get_out_rt_v6(cp->af, skb, NULL, &ipvsh->daddr.in6, NULL, ipvsh, 0, IP_VS_RT_MODE_NON_LOCAL) < 0) goto tx_error; /* Another hack: avoid icmp_send in ip_fragment */ skb->ignore_df = 1; ip_vs_send_or_cont(NFPROTO_IPV6, skb, cp, 0); rcu_read_unlock(); LeaveFunction(10); return NF_STOLEN; tx_error: kfree_skb(skb); rcu_read_unlock(); LeaveFunction(10); return NF_STOLEN; } #endif /* * NAT transmitter (only for outside-to-inside nat forwarding) * Not used for related ICMP */ int ip_vs_nat_xmit(struct sk_buff *skb, struct ip_vs_conn *cp, struct ip_vs_protocol *pp, struct ip_vs_iphdr *ipvsh) { struct rtable *rt; /* Route to the other host */ int local, rc, was_input; EnterFunction(10); rcu_read_lock(); /* check if it is a connection of no-client-port */ if (unlikely(cp->flags & IP_VS_CONN_F_NO_CPORT)) { __be16 _pt, *p; p = skb_header_pointer(skb, ipvsh->len, sizeof(_pt), &_pt); if (p == NULL) goto tx_error; ip_vs_conn_fill_cport(cp, *p); IP_VS_DBG(10, "filled cport=%d\n", ntohs(*p)); } was_input = rt_is_input_route(skb_rtable(skb)); local = __ip_vs_get_out_rt(cp->af, skb, cp->dest, cp->daddr.ip, IP_VS_RT_MODE_LOCAL | IP_VS_RT_MODE_NON_LOCAL | IP_VS_RT_MODE_RDR, NULL, ipvsh); if (local < 0) goto tx_error; rt = skb_rtable(skb); /* * Avoid duplicate tuple in reply direction for NAT traffic * to local address when connection is sync-ed */ #if IS_ENABLED(CONFIG_NF_CONNTRACK) if (cp->flags & IP_VS_CONN_F_SYNC && local) { enum ip_conntrack_info ctinfo; struct nf_conn *ct = nf_ct_get(skb, &ctinfo); if (ct && !nf_ct_is_untracked(ct)) { IP_VS_DBG_RL_PKT(10, AF_INET, pp, skb, 0, "ip_vs_nat_xmit(): " "stopping DNAT to local address"); goto tx_error; } } #endif /* From world but DNAT to loopback address? */ if (local && ipv4_is_loopback(cp->daddr.ip) && was_input) { IP_VS_DBG_RL_PKT(1, AF_INET, pp, skb, 0, "ip_vs_nat_xmit(): " "stopping DNAT to loopback address"); goto tx_error; } /* copy-on-write the packet before mangling it */ if (!skb_make_writable(skb, sizeof(struct iphdr))) goto tx_error; if (skb_cow(skb, rt->dst.dev->hard_header_len)) goto tx_error; /* mangle the packet */ if (pp->dnat_handler && !pp->dnat_handler(skb, pp, cp, ipvsh)) goto tx_error; ip_hdr(skb)->daddr = cp->daddr.ip; ip_send_check(ip_hdr(skb)); IP_VS_DBG_PKT(10, AF_INET, pp, skb, 0, "After DNAT"); /* FIXME: when application helper enlarges the packet and the length is larger than the MTU of outgoing device, there will be still MTU problem. */ /* Another hack: avoid icmp_send in ip_fragment */ skb->ignore_df = 1; rc = ip_vs_nat_send_or_cont(NFPROTO_IPV4, skb, cp, local); rcu_read_unlock(); LeaveFunction(10); return rc; tx_error: kfree_skb(skb); rcu_read_unlock(); LeaveFunction(10); return NF_STOLEN; } #ifdef CONFIG_IP_VS_IPV6 int ip_vs_nat_xmit_v6(struct sk_buff *skb, struct ip_vs_conn *cp, struct ip_vs_protocol *pp, struct ip_vs_iphdr *ipvsh) { struct rt6_info *rt; /* Route to the other host */ int local, rc; EnterFunction(10); rcu_read_lock(); /* check if it is a connection of no-client-port */ if (unlikely(cp->flags & IP_VS_CONN_F_NO_CPORT && !ipvsh->fragoffs)) { __be16 _pt, *p; p = skb_header_pointer(skb, ipvsh->len, sizeof(_pt), &_pt); if (p == NULL) goto tx_error; ip_vs_conn_fill_cport(cp, *p); IP_VS_DBG(10, "filled cport=%d\n", ntohs(*p)); } local = __ip_vs_get_out_rt_v6(cp->af, skb, cp->dest, &cp->daddr.in6, NULL, ipvsh, 0, IP_VS_RT_MODE_LOCAL | IP_VS_RT_MODE_NON_LOCAL | IP_VS_RT_MODE_RDR); if (local < 0) goto tx_error; rt = (struct rt6_info *) skb_dst(skb); /* * Avoid duplicate tuple in reply direction for NAT traffic * to local address when connection is sync-ed */ #if IS_ENABLED(CONFIG_NF_CONNTRACK) if (cp->flags & IP_VS_CONN_F_SYNC && local) { enum ip_conntrack_info ctinfo; struct nf_conn *ct = nf_ct_get(skb, &ctinfo); if (ct && !nf_ct_is_untracked(ct)) { IP_VS_DBG_RL_PKT(10, AF_INET6, pp, skb, 0, "ip_vs_nat_xmit_v6(): " "stopping DNAT to local address"); goto tx_error; } } #endif /* From world but DNAT to loopback address? */ if (local && skb->dev && !(skb->dev->flags & IFF_LOOPBACK) && ipv6_addr_type(&rt->rt6i_dst.addr) & IPV6_ADDR_LOOPBACK) { IP_VS_DBG_RL_PKT(1, AF_INET6, pp, skb, 0, "ip_vs_nat_xmit_v6(): " "stopping DNAT to loopback address"); goto tx_error; } /* copy-on-write the packet before mangling it */ if (!skb_make_writable(skb, sizeof(struct ipv6hdr))) goto tx_error; if (skb_cow(skb, rt->dst.dev->hard_header_len)) goto tx_error; /* mangle the packet */ if (pp->dnat_handler && !pp->dnat_handler(skb, pp, cp, ipvsh)) goto tx_error; ipv6_hdr(skb)->daddr = cp->daddr.in6; IP_VS_DBG_PKT(10, AF_INET6, pp, skb, 0, "After DNAT"); /* FIXME: when application helper enlarges the packet and the length is larger than the MTU of outgoing device, there will be still MTU problem. */ /* Another hack: avoid icmp_send in ip_fragment */ skb->ignore_df = 1; rc = ip_vs_nat_send_or_cont(NFPROTO_IPV6, skb, cp, local); rcu_read_unlock(); LeaveFunction(10); return rc; tx_error: LeaveFunction(10); kfree_skb(skb); rcu_read_unlock(); return NF_STOLEN; } #endif /* When forwarding a packet, we must ensure that we've got enough headroom * for the encapsulation packet in the skb. This also gives us an * opportunity to figure out what the payload_len, dsfield, ttl, and df * values should be, so that we won't need to look at the old ip header * again */ static struct sk_buff * ip_vs_prepare_tunneled_skb(struct sk_buff *skb, int skb_af, unsigned int max_headroom, __u8 *next_protocol, __u32 *payload_len, __u8 *dsfield, __u8 *ttl, __be16 *df) { struct sk_buff *new_skb = NULL; struct iphdr *old_iph = NULL; #ifdef CONFIG_IP_VS_IPV6 struct ipv6hdr *old_ipv6h = NULL; #endif ip_vs_drop_early_demux_sk(skb); if (skb_headroom(skb) < max_headroom || skb_cloned(skb)) { new_skb = skb_realloc_headroom(skb, max_headroom); if (!new_skb) goto error; if (skb->sk) skb_set_owner_w(new_skb, skb->sk); consume_skb(skb); skb = new_skb; } #ifdef CONFIG_IP_VS_IPV6 if (skb_af == AF_INET6) { old_ipv6h = ipv6_hdr(skb); *next_protocol = IPPROTO_IPV6; if (payload_len) *payload_len = ntohs(old_ipv6h->payload_len) + sizeof(*old_ipv6h); *dsfield = ipv6_get_dsfield(old_ipv6h); *ttl = old_ipv6h->hop_limit; if (df) *df = 0; } else #endif { old_iph = ip_hdr(skb); /* Copy DF, reset fragment offset and MF */ if (df) *df = (old_iph->frag_off & htons(IP_DF)); *next_protocol = IPPROTO_IPIP; /* fix old IP header checksum */ ip_send_check(old_iph); *dsfield = ipv4_get_dsfield(old_iph); *ttl = old_iph->ttl; if (payload_len) *payload_len = ntohs(old_iph->tot_len); } return skb; error: kfree_skb(skb); return ERR_PTR(-ENOMEM); } static inline int __tun_gso_type_mask(int encaps_af, int orig_af) { if (encaps_af == AF_INET) { if (orig_af == AF_INET) return SKB_GSO_IPIP; return SKB_GSO_SIT; } /* GSO: we need to provide proper SKB_GSO_ value for IPv6: * SKB_GSO_SIT/IPV6 */ return 0; } /* * IP Tunneling transmitter * * This function encapsulates the packet in a new IP packet, its * destination will be set to cp->daddr. Most code of this function * is taken from ipip.c. * * It is used in VS/TUN cluster. The load balancer selects a real * server from a cluster based on a scheduling algorithm, * encapsulates the request packet and forwards it to the selected * server. For example, all real servers are configured with * "ifconfig tunl0 up". When the server receives * the encapsulated packet, it will decapsulate the packet, processe * the request and return the response packets directly to the client * without passing the load balancer. This can greatly increase the * scalability of virtual server. * * Used for ANY protocol */ int ip_vs_tunnel_xmit(struct sk_buff *skb, struct ip_vs_conn *cp, struct ip_vs_protocol *pp, struct ip_vs_iphdr *ipvsh) { struct net *net = skb_net(skb); struct netns_ipvs *ipvs = net_ipvs(net); struct rtable *rt; /* Route to the other host */ __be32 saddr; /* Source for tunnel */ struct net_device *tdev; /* Device to other host */ __u8 next_protocol = 0; __u8 dsfield = 0; __u8 ttl = 0; __be16 df = 0; __be16 *dfp = NULL; struct iphdr *iph; /* Our new IP header */ unsigned int max_headroom; /* The extra header space needed */ int ret, local; EnterFunction(10); rcu_read_lock(); local = __ip_vs_get_out_rt(cp->af, skb, cp->dest, cp->daddr.ip, IP_VS_RT_MODE_LOCAL | IP_VS_RT_MODE_NON_LOCAL | IP_VS_RT_MODE_CONNECT | IP_VS_RT_MODE_TUNNEL, &saddr, ipvsh); if (local < 0) goto tx_error; if (local) { rcu_read_unlock(); return ip_vs_send_or_cont(NFPROTO_IPV4, skb, cp, 1); } rt = skb_rtable(skb); tdev = rt->dst.dev; /* * Okay, now see if we can stuff it in the buffer as-is. */ max_headroom = LL_RESERVED_SPACE(tdev) + sizeof(struct iphdr); /* We only care about the df field if sysctl_pmtu_disc(ipvs) is set */ dfp = sysctl_pmtu_disc(ipvs) ? &df : NULL; skb = ip_vs_prepare_tunneled_skb(skb, cp->af, max_headroom, &next_protocol, NULL, &dsfield, &ttl, dfp); if (IS_ERR(skb)) goto tx_error; skb = iptunnel_handle_offloads( skb, false, __tun_gso_type_mask(AF_INET, cp->af)); if (IS_ERR(skb)) goto tx_error; skb->transport_header = skb->network_header; skb_push(skb, sizeof(struct iphdr)); skb_reset_network_header(skb); memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt)); /* * Push down and install the IPIP header. */ iph = ip_hdr(skb); iph->version = 4; iph->ihl = sizeof(struct iphdr)>>2; iph->frag_off = df; iph->protocol = next_protocol; iph->tos = dsfield; iph->daddr = cp->daddr.ip; iph->saddr = saddr; iph->ttl = ttl; ip_select_ident(net, skb, NULL); /* Another hack: avoid icmp_send in ip_fragment */ skb->ignore_df = 1; ret = ip_vs_tunnel_xmit_prepare(skb, cp); if (ret == NF_ACCEPT) ip_local_out(skb); else if (ret == NF_DROP) kfree_skb(skb); rcu_read_unlock(); LeaveFunction(10); return NF_STOLEN; tx_error: if (!IS_ERR(skb)) kfree_skb(skb); rcu_read_unlock(); LeaveFunction(10); return NF_STOLEN; } #ifdef CONFIG_IP_VS_IPV6 int ip_vs_tunnel_xmit_v6(struct sk_buff *skb, struct ip_vs_conn *cp, struct ip_vs_protocol *pp, struct ip_vs_iphdr *ipvsh) { struct rt6_info *rt; /* Route to the other host */ struct in6_addr saddr; /* Source for tunnel */ struct net_device *tdev; /* Device to other host */ __u8 next_protocol = 0; __u32 payload_len = 0; __u8 dsfield = 0; __u8 ttl = 0; struct ipv6hdr *iph; /* Our new IP header */ unsigned int max_headroom; /* The extra header space needed */ int ret, local; EnterFunction(10); rcu_read_lock(); local = __ip_vs_get_out_rt_v6(cp->af, skb, cp->dest, &cp->daddr.in6, &saddr, ipvsh, 1, IP_VS_RT_MODE_LOCAL | IP_VS_RT_MODE_NON_LOCAL | IP_VS_RT_MODE_TUNNEL); if (local < 0) goto tx_error; if (local) { rcu_read_unlock(); return ip_vs_send_or_cont(NFPROTO_IPV6, skb, cp, 1); } rt = (struct rt6_info *) skb_dst(skb); tdev = rt->dst.dev; /* * Okay, now see if we can stuff it in the buffer as-is. */ max_headroom = LL_RESERVED_SPACE(tdev) + sizeof(struct ipv6hdr); skb = ip_vs_prepare_tunneled_skb(skb, cp->af, max_headroom, &next_protocol, &payload_len, &dsfield, &ttl, NULL); if (IS_ERR(skb)) goto tx_error; skb = iptunnel_handle_offloads( skb, false, __tun_gso_type_mask(AF_INET6, cp->af)); if (IS_ERR(skb)) goto tx_error; skb->transport_header = skb->network_header; skb_push(skb, sizeof(struct ipv6hdr)); skb_reset_network_header(skb); memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt)); /* * Push down and install the IPIP header. */ iph = ipv6_hdr(skb); iph->version = 6; iph->nexthdr = next_protocol; iph->payload_len = htons(payload_len); memset(&iph->flow_lbl, 0, sizeof(iph->flow_lbl)); ipv6_change_dsfield(iph, 0, dsfield); iph->daddr = cp->daddr.in6; iph->saddr = saddr; iph->hop_limit = ttl; /* Another hack: avoid icmp_send in ip_fragment */ skb->ignore_df = 1; ret = ip_vs_tunnel_xmit_prepare(skb, cp); if (ret == NF_ACCEPT) ip6_local_out(skb); else if (ret == NF_DROP) kfree_skb(skb); rcu_read_unlock(); LeaveFunction(10); return NF_STOLEN; tx_error: if (!IS_ERR(skb)) kfree_skb(skb); rcu_read_unlock(); LeaveFunction(10); return NF_STOLEN; } #endif /* * Direct Routing transmitter * Used for ANY protocol */ int ip_vs_dr_xmit(struct sk_buff *skb, struct ip_vs_conn *cp, struct ip_vs_protocol *pp, struct ip_vs_iphdr *ipvsh) { int local; EnterFunction(10); rcu_read_lock(); local = __ip_vs_get_out_rt(cp->af, skb, cp->dest, cp->daddr.ip, IP_VS_RT_MODE_LOCAL | IP_VS_RT_MODE_NON_LOCAL | IP_VS_RT_MODE_KNOWN_NH, NULL, ipvsh); if (local < 0) goto tx_error; if (local) { rcu_read_unlock(); return ip_vs_send_or_cont(NFPROTO_IPV4, skb, cp, 1); } ip_send_check(ip_hdr(skb)); /* Another hack: avoid icmp_send in ip_fragment */ skb->ignore_df = 1; ip_vs_send_or_cont(NFPROTO_IPV4, skb, cp, 0); rcu_read_unlock(); LeaveFunction(10); return NF_STOLEN; tx_error: kfree_skb(skb); rcu_read_unlock(); LeaveFunction(10); return NF_STOLEN; } #ifdef CONFIG_IP_VS_IPV6 int ip_vs_dr_xmit_v6(struct sk_buff *skb, struct ip_vs_conn *cp, struct ip_vs_protocol *pp, struct ip_vs_iphdr *ipvsh) { int local; EnterFunction(10); rcu_read_lock(); local = __ip_vs_get_out_rt_v6(cp->af, skb, cp->dest, &cp->daddr.in6, NULL, ipvsh, 0, IP_VS_RT_MODE_LOCAL | IP_VS_RT_MODE_NON_LOCAL); if (local < 0) goto tx_error; if (local) { rcu_read_unlock(); return ip_vs_send_or_cont(NFPROTO_IPV6, skb, cp, 1); } /* Another hack: avoid icmp_send in ip_fragment */ skb->ignore_df = 1; ip_vs_send_or_cont(NFPROTO_IPV6, skb, cp, 0); rcu_read_unlock(); LeaveFunction(10); return NF_STOLEN; tx_error: kfree_skb(skb); rcu_read_unlock(); LeaveFunction(10); return NF_STOLEN; } #endif /* * ICMP packet transmitter * called by the ip_vs_in_icmp */ int ip_vs_icmp_xmit(struct sk_buff *skb, struct ip_vs_conn *cp, struct ip_vs_protocol *pp, int offset, unsigned int hooknum, struct ip_vs_iphdr *iph) { struct rtable *rt; /* Route to the other host */ int rc; int local; int rt_mode, was_input; EnterFunction(10); /* The ICMP packet for VS/TUN, VS/DR and LOCALNODE will be forwarded directly here, because there is no need to translate address/port back */ if (IP_VS_FWD_METHOD(cp) != IP_VS_CONN_F_MASQ) { if (cp->packet_xmit) rc = cp->packet_xmit(skb, cp, pp, iph); else rc = NF_ACCEPT; /* do not touch skb anymore */ atomic_inc(&cp->in_pkts); goto out; } /* * mangle and send the packet here (only for VS/NAT) */ was_input = rt_is_input_route(skb_rtable(skb)); /* LOCALNODE from FORWARD hook is not supported */ rt_mode = (hooknum != NF_INET_FORWARD) ? IP_VS_RT_MODE_LOCAL | IP_VS_RT_MODE_NON_LOCAL | IP_VS_RT_MODE_RDR : IP_VS_RT_MODE_NON_LOCAL; rcu_read_lock(); local = __ip_vs_get_out_rt(cp->af, skb, cp->dest, cp->daddr.ip, rt_mode, NULL, iph); if (local < 0) goto tx_error; rt = skb_rtable(skb); /* * Avoid duplicate tuple in reply direction for NAT traffic * to local address when connection is sync-ed */ #if IS_ENABLED(CONFIG_NF_CONNTRACK) if (cp->flags & IP_VS_CONN_F_SYNC && local) { enum ip_conntrack_info ctinfo; struct nf_conn *ct = nf_ct_get(skb, &ctinfo); if (ct && !nf_ct_is_untracked(ct)) { IP_VS_DBG(10, "%s(): " "stopping DNAT to local address %pI4\n", __func__, &cp->daddr.ip); goto tx_error; } } #endif /* From world but DNAT to loopback address? */ if (local && ipv4_is_loopback(cp->daddr.ip) && was_input) { IP_VS_DBG(1, "%s(): " "stopping DNAT to loopback %pI4\n", __func__, &cp->daddr.ip); goto tx_error; } /* copy-on-write the packet before mangling it */ if (!skb_make_writable(skb, offset)) goto tx_error; if (skb_cow(skb, rt->dst.dev->hard_header_len)) goto tx_error; ip_vs_nat_icmp(skb, pp, cp, 0); /* Another hack: avoid icmp_send in ip_fragment */ skb->ignore_df = 1; rc = ip_vs_nat_send_or_cont(NFPROTO_IPV4, skb, cp, local); rcu_read_unlock(); goto out; tx_error: kfree_skb(skb); rcu_read_unlock(); rc = NF_STOLEN; out: LeaveFunction(10); return rc; } #ifdef CONFIG_IP_VS_IPV6 int ip_vs_icmp_xmit_v6(struct sk_buff *skb, struct ip_vs_conn *cp, struct ip_vs_protocol *pp, int offset, unsigned int hooknum, struct ip_vs_iphdr *ipvsh) { struct rt6_info *rt; /* Route to the other host */ int rc; int local; int rt_mode; EnterFunction(10); /* The ICMP packet for VS/TUN, VS/DR and LOCALNODE will be forwarded directly here, because there is no need to translate address/port back */ if (IP_VS_FWD_METHOD(cp) != IP_VS_CONN_F_MASQ) { if (cp->packet_xmit) rc = cp->packet_xmit(skb, cp, pp, ipvsh); else rc = NF_ACCEPT; /* do not touch skb anymore */ atomic_inc(&cp->in_pkts); goto out; } /* * mangle and send the packet here (only for VS/NAT) */ /* LOCALNODE from FORWARD hook is not supported */ rt_mode = (hooknum != NF_INET_FORWARD) ? IP_VS_RT_MODE_LOCAL | IP_VS_RT_MODE_NON_LOCAL | IP_VS_RT_MODE_RDR : IP_VS_RT_MODE_NON_LOCAL; rcu_read_lock(); local = __ip_vs_get_out_rt_v6(cp->af, skb, cp->dest, &cp->daddr.in6, NULL, ipvsh, 0, rt_mode); if (local < 0) goto tx_error; rt = (struct rt6_info *) skb_dst(skb); /* * Avoid duplicate tuple in reply direction for NAT traffic * to local address when connection is sync-ed */ #if IS_ENABLED(CONFIG_NF_CONNTRACK) if (cp->flags & IP_VS_CONN_F_SYNC && local) { enum ip_conntrack_info ctinfo; struct nf_conn *ct = nf_ct_get(skb, &ctinfo); if (ct && !nf_ct_is_untracked(ct)) { IP_VS_DBG(10, "%s(): " "stopping DNAT to local address %pI6\n", __func__, &cp->daddr.in6); goto tx_error; } } #endif /* From world but DNAT to loopback address? */ if (local && skb->dev && !(skb->dev->flags & IFF_LOOPBACK) && ipv6_addr_type(&rt->rt6i_dst.addr) & IPV6_ADDR_LOOPBACK) { IP_VS_DBG(1, "%s(): " "stopping DNAT to loopback %pI6\n", __func__, &cp->daddr.in6); goto tx_error; } /* copy-on-write the packet before mangling it */ if (!skb_make_writable(skb, offset)) goto tx_error; if (skb_cow(skb, rt->dst.dev->hard_header_len)) goto tx_error; ip_vs_nat_icmp_v6(skb, pp, cp, 0); /* Another hack: avoid icmp_send in ip_fragment */ skb->ignore_df = 1; rc = ip_vs_nat_send_or_cont(NFPROTO_IPV6, skb, cp, local); rcu_read_unlock(); goto out; tx_error: kfree_skb(skb); rcu_read_unlock(); rc = NF_STOLEN; out: LeaveFunction(10); return rc; } #endif