diff options
Diffstat (limited to 'net/netfilter/ipvs/ip_vs_xmit.c')
| -rw-r--r-- | net/netfilter/ipvs/ip_vs_xmit.c | 1380 |
1 files changed, 1380 insertions, 0 deletions
diff --git a/net/netfilter/ipvs/ip_vs_xmit.c b/net/netfilter/ipvs/ip_vs_xmit.c new file mode 100644 index 000000000..19986ec5f --- /dev/null +++ b/net/netfilter/ipvs/ip_vs_xmit.c @@ -0,0 +1,1380 @@ +/* + * ip_vs_xmit.c: various packet transmitters 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: + * + * 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 <linux/kernel.h> +#include <linux/slab.h> +#include <linux/tcp.h> /* for tcphdr */ +#include <net/ip.h> +#include <net/tcp.h> /* for csum_tcpudp_magic */ +#include <net/udp.h> +#include <net/icmp.h> /* for icmp_send */ +#include <net/route.h> /* for ip_route_output */ +#include <net/ipv6.h> +#include <net/ip6_route.h> +#include <net/ip_tunnels.h> +#include <net/addrconf.h> +#include <linux/icmpv6.h> +#include <linux/netfilter.h> +#include <linux/netfilter_ipv4.h> + +#include <net/ip_vs.h> + +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.saddr = (rt_mode & IP_VS_RT_MODE_CONNECT) ? *saddr : 0; + 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); + } + return ret; +} + +/* 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); + if (!local) { + skb_forward_csum(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) { + skb_forward_csum(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 + + 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 <Virtual IP Address> 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 |