diff options
Diffstat (limited to 'net/netfilter/ipvs/ip_vs_nfct.c')
-rw-r--r-- | net/netfilter/ipvs/ip_vs_nfct.c | 280 |
1 files changed, 280 insertions, 0 deletions
diff --git a/net/netfilter/ipvs/ip_vs_nfct.c b/net/netfilter/ipvs/ip_vs_nfct.c new file mode 100644 index 000000000..08adcb222 --- /dev/null +++ b/net/netfilter/ipvs/ip_vs_nfct.c @@ -0,0 +1,280 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * ip_vs_nfct.c: Netfilter connection tracking support for IPVS + * + * Portions Copyright (C) 2001-2002 + * Antefacto Ltd, 181 Parnell St, Dublin 1, Ireland. + * + * Portions Copyright (C) 2003-2010 + * Julian Anastasov + * + * Authors: + * Ben North <ben@redfrontdoor.org> + * Julian Anastasov <ja@ssi.bg> Reorganize and sync with latest kernels + * Hannes Eder <heder@google.com> Extend NFCT support for FTP, ipvs match + * + * Current status: + * + * - provide conntrack confirmation for new and related connections, by + * this way we can see their proper conntrack state in all hooks + * - support for all forwarding methods, not only NAT + * - FTP support (NAT), ability to support other NAT apps with expectations + * - to correctly create expectations for related NAT connections the proper + * NF conntrack support must be already installed, eg. ip_vs_ftp requires + * nf_conntrack_ftp ... iptables_nat for the same ports (but no iptables + * NAT rules are needed) + * - alter reply for NAT when forwarding packet in original direction: + * conntrack from client in NEW or RELATED (Passive FTP DATA) state or + * when RELATED conntrack is created from real server (Active FTP DATA) + * - if iptables_nat is not loaded the Passive FTP will not work (the + * PASV response can not be NAT-ed) but Active FTP should work + */ + +#define KMSG_COMPONENT "IPVS" +#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt + +#include <linux/module.h> +#include <linux/types.h> +#include <linux/kernel.h> +#include <linux/errno.h> +#include <linux/compiler.h> +#include <linux/vmalloc.h> +#include <linux/skbuff.h> +#include <net/ip.h> +#include <linux/netfilter.h> +#include <linux/netfilter_ipv4.h> +#include <net/ip_vs.h> +#include <net/netfilter/nf_conntrack_core.h> +#include <net/netfilter/nf_conntrack_expect.h> +#include <net/netfilter/nf_conntrack_seqadj.h> +#include <net/netfilter/nf_conntrack_helper.h> +#include <net/netfilter/nf_conntrack_zones.h> + + +#define FMT_TUPLE "%s:%u->%s:%u/%u" +#define ARG_TUPLE(T) IP_VS_DBG_ADDR((T)->src.l3num, &(T)->src.u3), \ + ntohs((T)->src.u.all), \ + IP_VS_DBG_ADDR((T)->src.l3num, &(T)->dst.u3), \ + ntohs((T)->dst.u.all), \ + (T)->dst.protonum + +#define FMT_CONN "%s:%u->%s:%u->%s:%u/%u:%u" +#define ARG_CONN(C) IP_VS_DBG_ADDR((C)->af, &((C)->caddr)), \ + ntohs((C)->cport), \ + IP_VS_DBG_ADDR((C)->af, &((C)->vaddr)), \ + ntohs((C)->vport), \ + IP_VS_DBG_ADDR((C)->daf, &((C)->daddr)), \ + ntohs((C)->dport), \ + (C)->protocol, (C)->state + +void +ip_vs_update_conntrack(struct sk_buff *skb, struct ip_vs_conn *cp, int outin) +{ + enum ip_conntrack_info ctinfo; + struct nf_conn *ct = nf_ct_get(skb, &ctinfo); + struct nf_conntrack_tuple new_tuple; + + if (ct == NULL || nf_ct_is_confirmed(ct) || + nf_ct_is_dying(ct)) + return; + + /* Never alter conntrack for non-NAT conns */ + if (IP_VS_FWD_METHOD(cp) != IP_VS_CONN_F_MASQ) + return; + + /* Never alter conntrack for OPS conns (no reply is expected) */ + if (cp->flags & IP_VS_CONN_F_ONE_PACKET) + return; + + /* Alter reply only in original direction */ + if (CTINFO2DIR(ctinfo) != IP_CT_DIR_ORIGINAL) + return; + + /* Applications may adjust TCP seqs */ + if (cp->app && nf_ct_protonum(ct) == IPPROTO_TCP && + !nfct_seqadj(ct) && !nfct_seqadj_ext_add(ct)) + return; + + /* + * The connection is not yet in the hashtable, so we update it. + * CIP->VIP will remain the same, so leave the tuple in + * IP_CT_DIR_ORIGINAL untouched. When the reply comes back from the + * real-server we will see RIP->DIP. + */ + new_tuple = ct->tuplehash[IP_CT_DIR_REPLY].tuple; + /* + * This will also take care of UDP and other protocols. + */ + if (outin) { + new_tuple.src.u3 = cp->daddr; + if (new_tuple.dst.protonum != IPPROTO_ICMP && + new_tuple.dst.protonum != IPPROTO_ICMPV6) + new_tuple.src.u.tcp.port = cp->dport; + } else { + new_tuple.dst.u3 = cp->vaddr; + if (new_tuple.dst.protonum != IPPROTO_ICMP && + new_tuple.dst.protonum != IPPROTO_ICMPV6) + new_tuple.dst.u.tcp.port = cp->vport; + } + IP_VS_DBG_BUF(7, "%s: Updating conntrack ct=%p, status=0x%lX, " + "ctinfo=%d, old reply=" FMT_TUPLE "\n", + __func__, ct, ct->status, ctinfo, + ARG_TUPLE(&ct->tuplehash[IP_CT_DIR_REPLY].tuple)); + IP_VS_DBG_BUF(7, "%s: Updating conntrack ct=%p, status=0x%lX, " + "ctinfo=%d, new reply=" FMT_TUPLE "\n", + __func__, ct, ct->status, ctinfo, + ARG_TUPLE(&new_tuple)); + nf_conntrack_alter_reply(ct, &new_tuple); + IP_VS_DBG_BUF(7, "%s: Updated conntrack ct=%p for cp=" FMT_CONN "\n", + __func__, ct, ARG_CONN(cp)); +} + +int ip_vs_confirm_conntrack(struct sk_buff *skb) +{ + return nf_conntrack_confirm(skb); +} + +/* + * Called from init_conntrack() as expectfn handler. + */ +static void ip_vs_nfct_expect_callback(struct nf_conn *ct, + struct nf_conntrack_expect *exp) +{ + struct nf_conntrack_tuple *orig, new_reply; + struct ip_vs_conn *cp; + struct ip_vs_conn_param p; + struct net *net = nf_ct_net(ct); + + /* + * We assume that no NF locks are held before this callback. + * ip_vs_conn_out_get and ip_vs_conn_in_get should match their + * expectations even if they use wildcard values, now we provide the + * actual values from the newly created original conntrack direction. + * The conntrack is confirmed when packet reaches IPVS hooks. + */ + + /* RS->CLIENT */ + orig = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple; + ip_vs_conn_fill_param(net_ipvs(net), exp->tuple.src.l3num, orig->dst.protonum, + &orig->src.u3, orig->src.u.tcp.port, + &orig->dst.u3, orig->dst.u.tcp.port, &p); + cp = ip_vs_conn_out_get(&p); + if (cp) { + /* Change reply CLIENT->RS to CLIENT->VS */ + IP_VS_DBG_BUF(7, "%s: for ct=%p, status=0x%lX found inout cp=" + FMT_CONN "\n", + __func__, ct, ct->status, ARG_CONN(cp)); + new_reply = ct->tuplehash[IP_CT_DIR_REPLY].tuple; + IP_VS_DBG_BUF(7, "%s: ct=%p before alter: reply tuple=" + FMT_TUPLE "\n", + __func__, ct, ARG_TUPLE(&new_reply)); + new_reply.dst.u3 = cp->vaddr; + new_reply.dst.u.tcp.port = cp->vport; + goto alter; + } + + /* CLIENT->VS */ + cp = ip_vs_conn_in_get(&p); + if (cp) { + /* Change reply VS->CLIENT to RS->CLIENT */ + IP_VS_DBG_BUF(7, "%s: for ct=%p, status=0x%lX found outin cp=" + FMT_CONN "\n", + __func__, ct, ct->status, ARG_CONN(cp)); + new_reply = ct->tuplehash[IP_CT_DIR_REPLY].tuple; + IP_VS_DBG_BUF(7, "%s: ct=%p before alter: reply tuple=" + FMT_TUPLE "\n", + __func__, ct, ARG_TUPLE(&new_reply)); + new_reply.src.u3 = cp->daddr; + new_reply.src.u.tcp.port = cp->dport; + goto alter; + } + + IP_VS_DBG_BUF(7, "%s: ct=%p, status=0x%lX, tuple=" FMT_TUPLE + " - unknown expect\n", + __func__, ct, ct->status, ARG_TUPLE(orig)); + return; + +alter: + /* Never alter conntrack for non-NAT conns */ + if (IP_VS_FWD_METHOD(cp) == IP_VS_CONN_F_MASQ) + nf_conntrack_alter_reply(ct, &new_reply); + ip_vs_conn_put(cp); + return; +} + +/* + * Create NF conntrack expectation with wildcard (optional) source port. + * Then the default callback function will alter the reply and will confirm + * the conntrack entry when the first packet comes. + * Use port 0 to expect connection from any port. + */ +void ip_vs_nfct_expect_related(struct sk_buff *skb, struct nf_conn *ct, + struct ip_vs_conn *cp, u_int8_t proto, + const __be16 port, int from_rs) +{ + struct nf_conntrack_expect *exp; + + if (ct == NULL) + return; + + exp = nf_ct_expect_alloc(ct); + if (!exp) + return; + + nf_ct_expect_init(exp, NF_CT_EXPECT_CLASS_DEFAULT, nf_ct_l3num(ct), + from_rs ? &cp->daddr : &cp->caddr, + from_rs ? &cp->caddr : &cp->vaddr, + proto, port ? &port : NULL, + from_rs ? &cp->cport : &cp->vport); + + exp->expectfn = ip_vs_nfct_expect_callback; + + IP_VS_DBG_BUF(7, "%s: ct=%p, expect tuple=" FMT_TUPLE "\n", + __func__, ct, ARG_TUPLE(&exp->tuple)); + nf_ct_expect_related(exp, 0); + nf_ct_expect_put(exp); +} +EXPORT_SYMBOL(ip_vs_nfct_expect_related); + +/* + * Our connection was terminated, try to drop the conntrack immediately + */ +void ip_vs_conn_drop_conntrack(struct ip_vs_conn *cp) +{ + struct nf_conntrack_tuple_hash *h; + struct nf_conn *ct; + struct nf_conntrack_tuple tuple; + + if (!cp->cport) + return; + + tuple = (struct nf_conntrack_tuple) { + .dst = { .protonum = cp->protocol, .dir = IP_CT_DIR_ORIGINAL } }; + tuple.src.u3 = cp->caddr; + tuple.src.u.all = cp->cport; + tuple.src.l3num = cp->af; + tuple.dst.u3 = cp->vaddr; + tuple.dst.u.all = cp->vport; + + IP_VS_DBG_BUF(7, "%s: dropping conntrack for conn " FMT_CONN "\n", + __func__, ARG_CONN(cp)); + + h = nf_conntrack_find_get(cp->ipvs->net, &nf_ct_zone_dflt, &tuple); + if (h) { + ct = nf_ct_tuplehash_to_ctrack(h); + if (nf_ct_kill(ct)) { + IP_VS_DBG_BUF(7, "%s: ct=%p deleted for tuple=" + FMT_TUPLE "\n", + __func__, ct, ARG_TUPLE(&tuple)); + } else { + IP_VS_DBG_BUF(7, "%s: ct=%p, no conntrack for tuple=" + FMT_TUPLE "\n", + __func__, ct, ARG_TUPLE(&tuple)); + } + nf_ct_put(ct); + } else { + IP_VS_DBG_BUF(7, "%s: no conntrack for tuple=" FMT_TUPLE "\n", + __func__, ARG_TUPLE(&tuple)); + } +} + |