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https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
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136 lines
3.8 KiB
C
136 lines
3.8 KiB
C
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// SPDX-License-Identifier: GPL-2.0-only
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/* Support nat functions for openvswitch and used by OVS and TC conntrack. */
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#include <net/netfilter/nf_nat.h>
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/* Modelled after nf_nat_ipv[46]_fn().
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* range is only used for new, uninitialized NAT state.
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* Returns either NF_ACCEPT or NF_DROP.
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*/
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static int nf_ct_nat_execute(struct sk_buff *skb, struct nf_conn *ct,
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enum ip_conntrack_info ctinfo, int *action,
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const struct nf_nat_range2 *range,
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enum nf_nat_manip_type maniptype)
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{
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__be16 proto = skb_protocol(skb, true);
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int hooknum, err = NF_ACCEPT;
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/* See HOOK2MANIP(). */
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if (maniptype == NF_NAT_MANIP_SRC)
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hooknum = NF_INET_LOCAL_IN; /* Source NAT */
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else
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hooknum = NF_INET_LOCAL_OUT; /* Destination NAT */
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switch (ctinfo) {
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case IP_CT_RELATED:
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case IP_CT_RELATED_REPLY:
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if (proto == htons(ETH_P_IP) &&
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ip_hdr(skb)->protocol == IPPROTO_ICMP) {
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if (!nf_nat_icmp_reply_translation(skb, ct, ctinfo,
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hooknum))
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err = NF_DROP;
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goto out;
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} else if (IS_ENABLED(CONFIG_IPV6) && proto == htons(ETH_P_IPV6)) {
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__be16 frag_off;
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u8 nexthdr = ipv6_hdr(skb)->nexthdr;
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int hdrlen = ipv6_skip_exthdr(skb,
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sizeof(struct ipv6hdr),
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&nexthdr, &frag_off);
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if (hdrlen >= 0 && nexthdr == IPPROTO_ICMPV6) {
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if (!nf_nat_icmpv6_reply_translation(skb, ct,
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ctinfo,
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hooknum,
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hdrlen))
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err = NF_DROP;
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goto out;
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}
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}
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/* Non-ICMP, fall thru to initialize if needed. */
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fallthrough;
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case IP_CT_NEW:
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/* Seen it before? This can happen for loopback, retrans,
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* or local packets.
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*/
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if (!nf_nat_initialized(ct, maniptype)) {
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/* Initialize according to the NAT action. */
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err = (range && range->flags & NF_NAT_RANGE_MAP_IPS)
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/* Action is set up to establish a new
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* mapping.
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*/
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? nf_nat_setup_info(ct, range, maniptype)
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: nf_nat_alloc_null_binding(ct, hooknum);
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if (err != NF_ACCEPT)
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goto out;
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}
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break;
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case IP_CT_ESTABLISHED:
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case IP_CT_ESTABLISHED_REPLY:
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break;
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default:
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err = NF_DROP;
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goto out;
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}
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err = nf_nat_packet(ct, ctinfo, hooknum, skb);
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if (err == NF_ACCEPT)
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*action |= BIT(maniptype);
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out:
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return err;
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}
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int nf_ct_nat(struct sk_buff *skb, struct nf_conn *ct,
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enum ip_conntrack_info ctinfo, int *action,
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const struct nf_nat_range2 *range, bool commit)
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{
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enum nf_nat_manip_type maniptype;
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int err, ct_action = *action;
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*action = 0;
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/* Add NAT extension if not confirmed yet. */
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if (!nf_ct_is_confirmed(ct) && !nf_ct_nat_ext_add(ct))
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return NF_DROP; /* Can't NAT. */
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if (ctinfo != IP_CT_NEW && (ct->status & IPS_NAT_MASK) &&
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(ctinfo != IP_CT_RELATED || commit)) {
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/* NAT an established or related connection like before. */
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if (CTINFO2DIR(ctinfo) == IP_CT_DIR_REPLY)
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/* This is the REPLY direction for a connection
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* for which NAT was applied in the forward
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* direction. Do the reverse NAT.
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*/
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maniptype = ct->status & IPS_SRC_NAT
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? NF_NAT_MANIP_DST : NF_NAT_MANIP_SRC;
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else
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maniptype = ct->status & IPS_SRC_NAT
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? NF_NAT_MANIP_SRC : NF_NAT_MANIP_DST;
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} else if (ct_action & BIT(NF_NAT_MANIP_SRC)) {
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maniptype = NF_NAT_MANIP_SRC;
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} else if (ct_action & BIT(NF_NAT_MANIP_DST)) {
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maniptype = NF_NAT_MANIP_DST;
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} else {
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return NF_ACCEPT;
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}
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err = nf_ct_nat_execute(skb, ct, ctinfo, action, range, maniptype);
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if (err == NF_ACCEPT && ct->status & IPS_DST_NAT) {
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if (ct->status & IPS_SRC_NAT) {
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if (maniptype == NF_NAT_MANIP_SRC)
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maniptype = NF_NAT_MANIP_DST;
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else
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maniptype = NF_NAT_MANIP_SRC;
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err = nf_ct_nat_execute(skb, ct, ctinfo, action, range,
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maniptype);
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} else if (CTINFO2DIR(ctinfo) == IP_CT_DIR_ORIGINAL) {
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err = nf_ct_nat_execute(skb, ct, ctinfo, action, NULL,
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NF_NAT_MANIP_SRC);
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}
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}
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return err;
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}
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EXPORT_SYMBOL_GPL(nf_ct_nat);
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