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-rw-r--r--net/netfilter/nf_nat_proto.c1103
1 files changed, 1103 insertions, 0 deletions
diff --git a/net/netfilter/nf_nat_proto.c b/net/netfilter/nf_nat_proto.c
new file mode 100644
index 000000000..48cc60084
--- /dev/null
+++ b/net/netfilter/nf_nat_proto.c
@@ -0,0 +1,1103 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* (C) 1999-2001 Paul `Rusty' Russell
+ * (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org>
+ */
+
+#include <linux/types.h>
+#include <linux/export.h>
+#include <linux/init.h>
+#include <linux/udp.h>
+#include <linux/tcp.h>
+#include <linux/icmp.h>
+#include <linux/icmpv6.h>
+
+#include <linux/dccp.h>
+#include <linux/sctp.h>
+#include <net/sctp/checksum.h>
+
+#include <linux/netfilter.h>
+#include <net/netfilter/nf_nat.h>
+
+#include <linux/ipv6.h>
+#include <linux/netfilter_ipv6.h>
+#include <net/checksum.h>
+#include <net/ip6_checksum.h>
+#include <net/ip6_route.h>
+#include <net/xfrm.h>
+#include <net/ipv6.h>
+
+#include <net/netfilter/nf_conntrack_core.h>
+#include <net/netfilter/nf_conntrack.h>
+#include <linux/netfilter/nfnetlink_conntrack.h>
+
+static void nf_csum_update(struct sk_buff *skb,
+ unsigned int iphdroff, __sum16 *check,
+ const struct nf_conntrack_tuple *t,
+ enum nf_nat_manip_type maniptype);
+
+static void
+__udp_manip_pkt(struct sk_buff *skb,
+ unsigned int iphdroff, struct udphdr *hdr,
+ const struct nf_conntrack_tuple *tuple,
+ enum nf_nat_manip_type maniptype, bool do_csum)
+{
+ __be16 *portptr, newport;
+
+ if (maniptype == NF_NAT_MANIP_SRC) {
+ /* Get rid of src port */
+ newport = tuple->src.u.udp.port;
+ portptr = &hdr->source;
+ } else {
+ /* Get rid of dst port */
+ newport = tuple->dst.u.udp.port;
+ portptr = &hdr->dest;
+ }
+ if (do_csum) {
+ nf_csum_update(skb, iphdroff, &hdr->check, tuple, maniptype);
+ inet_proto_csum_replace2(&hdr->check, skb, *portptr, newport,
+ false);
+ if (!hdr->check)
+ hdr->check = CSUM_MANGLED_0;
+ }
+ *portptr = newport;
+}
+
+static bool udp_manip_pkt(struct sk_buff *skb,
+ unsigned int iphdroff, unsigned int hdroff,
+ const struct nf_conntrack_tuple *tuple,
+ enum nf_nat_manip_type maniptype)
+{
+ struct udphdr *hdr;
+
+ if (skb_ensure_writable(skb, hdroff + sizeof(*hdr)))
+ return false;
+
+ hdr = (struct udphdr *)(skb->data + hdroff);
+ __udp_manip_pkt(skb, iphdroff, hdr, tuple, maniptype, !!hdr->check);
+
+ return true;
+}
+
+static bool udplite_manip_pkt(struct sk_buff *skb,
+ unsigned int iphdroff, unsigned int hdroff,
+ const struct nf_conntrack_tuple *tuple,
+ enum nf_nat_manip_type maniptype)
+{
+#ifdef CONFIG_NF_CT_PROTO_UDPLITE
+ struct udphdr *hdr;
+
+ if (skb_ensure_writable(skb, hdroff + sizeof(*hdr)))
+ return false;
+
+ hdr = (struct udphdr *)(skb->data + hdroff);
+ __udp_manip_pkt(skb, iphdroff, hdr, tuple, maniptype, true);
+#endif
+ return true;
+}
+
+static bool
+sctp_manip_pkt(struct sk_buff *skb,
+ unsigned int iphdroff, unsigned int hdroff,
+ const struct nf_conntrack_tuple *tuple,
+ enum nf_nat_manip_type maniptype)
+{
+#ifdef CONFIG_NF_CT_PROTO_SCTP
+ struct sctphdr *hdr;
+ int hdrsize = 8;
+
+ /* This could be an inner header returned in imcp packet; in such
+ * cases we cannot update the checksum field since it is outside
+ * of the 8 bytes of transport layer headers we are guaranteed.
+ */
+ if (skb->len >= hdroff + sizeof(*hdr))
+ hdrsize = sizeof(*hdr);
+
+ if (skb_ensure_writable(skb, hdroff + hdrsize))
+ return false;
+
+ hdr = (struct sctphdr *)(skb->data + hdroff);
+
+ if (maniptype == NF_NAT_MANIP_SRC) {
+ /* Get rid of src port */
+ hdr->source = tuple->src.u.sctp.port;
+ } else {
+ /* Get rid of dst port */
+ hdr->dest = tuple->dst.u.sctp.port;
+ }
+
+ if (hdrsize < sizeof(*hdr))
+ return true;
+
+ if (skb->ip_summed != CHECKSUM_PARTIAL) {
+ hdr->checksum = sctp_compute_cksum(skb, hdroff);
+ skb->ip_summed = CHECKSUM_NONE;
+ }
+
+#endif
+ return true;
+}
+
+static bool
+tcp_manip_pkt(struct sk_buff *skb,
+ unsigned int iphdroff, unsigned int hdroff,
+ const struct nf_conntrack_tuple *tuple,
+ enum nf_nat_manip_type maniptype)
+{
+ struct tcphdr *hdr;
+ __be16 *portptr, newport, oldport;
+ int hdrsize = 8; /* TCP connection tracking guarantees this much */
+
+ /* this could be a inner header returned in icmp packet; in such
+ cases we cannot update the checksum field since it is outside of
+ the 8 bytes of transport layer headers we are guaranteed */
+ if (skb->len >= hdroff + sizeof(struct tcphdr))
+ hdrsize = sizeof(struct tcphdr);
+
+ if (skb_ensure_writable(skb, hdroff + hdrsize))
+ return false;
+
+ hdr = (struct tcphdr *)(skb->data + hdroff);
+
+ if (maniptype == NF_NAT_MANIP_SRC) {
+ /* Get rid of src port */
+ newport = tuple->src.u.tcp.port;
+ portptr = &hdr->source;
+ } else {
+ /* Get rid of dst port */
+ newport = tuple->dst.u.tcp.port;
+ portptr = &hdr->dest;
+ }
+
+ oldport = *portptr;
+ *portptr = newport;
+
+ if (hdrsize < sizeof(*hdr))
+ return true;
+
+ nf_csum_update(skb, iphdroff, &hdr->check, tuple, maniptype);
+ inet_proto_csum_replace2(&hdr->check, skb, oldport, newport, false);
+ return true;
+}
+
+static bool
+dccp_manip_pkt(struct sk_buff *skb,
+ unsigned int iphdroff, unsigned int hdroff,
+ const struct nf_conntrack_tuple *tuple,
+ enum nf_nat_manip_type maniptype)
+{
+#ifdef CONFIG_NF_CT_PROTO_DCCP
+ struct dccp_hdr *hdr;
+ __be16 *portptr, oldport, newport;
+ int hdrsize = 8; /* DCCP connection tracking guarantees this much */
+
+ if (skb->len >= hdroff + sizeof(struct dccp_hdr))
+ hdrsize = sizeof(struct dccp_hdr);
+
+ if (skb_ensure_writable(skb, hdroff + hdrsize))
+ return false;
+
+ hdr = (struct dccp_hdr *)(skb->data + hdroff);
+
+ if (maniptype == NF_NAT_MANIP_SRC) {
+ newport = tuple->src.u.dccp.port;
+ portptr = &hdr->dccph_sport;
+ } else {
+ newport = tuple->dst.u.dccp.port;
+ portptr = &hdr->dccph_dport;
+ }
+
+ oldport = *portptr;
+ *portptr = newport;
+
+ if (hdrsize < sizeof(*hdr))
+ return true;
+
+ nf_csum_update(skb, iphdroff, &hdr->dccph_checksum, tuple, maniptype);
+ inet_proto_csum_replace2(&hdr->dccph_checksum, skb, oldport, newport,
+ false);
+#endif
+ return true;
+}
+
+static bool
+icmp_manip_pkt(struct sk_buff *skb,
+ unsigned int iphdroff, unsigned int hdroff,
+ const struct nf_conntrack_tuple *tuple,
+ enum nf_nat_manip_type maniptype)
+{
+ struct icmphdr *hdr;
+
+ if (skb_ensure_writable(skb, hdroff + sizeof(*hdr)))
+ return false;
+
+ hdr = (struct icmphdr *)(skb->data + hdroff);
+ switch (hdr->type) {
+ case ICMP_ECHO:
+ case ICMP_ECHOREPLY:
+ case ICMP_TIMESTAMP:
+ case ICMP_TIMESTAMPREPLY:
+ case ICMP_INFO_REQUEST:
+ case ICMP_INFO_REPLY:
+ case ICMP_ADDRESS:
+ case ICMP_ADDRESSREPLY:
+ break;
+ default:
+ return true;
+ }
+ inet_proto_csum_replace2(&hdr->checksum, skb,
+ hdr->un.echo.id, tuple->src.u.icmp.id, false);
+ hdr->un.echo.id = tuple->src.u.icmp.id;
+ return true;
+}
+
+static bool
+icmpv6_manip_pkt(struct sk_buff *skb,
+ unsigned int iphdroff, unsigned int hdroff,
+ const struct nf_conntrack_tuple *tuple,
+ enum nf_nat_manip_type maniptype)
+{
+ struct icmp6hdr *hdr;
+
+ if (skb_ensure_writable(skb, hdroff + sizeof(*hdr)))
+ return false;
+
+ hdr = (struct icmp6hdr *)(skb->data + hdroff);
+ nf_csum_update(skb, iphdroff, &hdr->icmp6_cksum, tuple, maniptype);
+ if (hdr->icmp6_type == ICMPV6_ECHO_REQUEST ||
+ hdr->icmp6_type == ICMPV6_ECHO_REPLY) {
+ inet_proto_csum_replace2(&hdr->icmp6_cksum, skb,
+ hdr->icmp6_identifier,
+ tuple->src.u.icmp.id, false);
+ hdr->icmp6_identifier = tuple->src.u.icmp.id;
+ }
+ return true;
+}
+
+/* manipulate a GRE packet according to maniptype */
+static bool
+gre_manip_pkt(struct sk_buff *skb,
+ unsigned int iphdroff, unsigned int hdroff,
+ const struct nf_conntrack_tuple *tuple,
+ enum nf_nat_manip_type maniptype)
+{
+#if IS_ENABLED(CONFIG_NF_CT_PROTO_GRE)
+ const struct gre_base_hdr *greh;
+ struct pptp_gre_header *pgreh;
+
+ /* pgreh includes two optional 32bit fields which are not required
+ * to be there. That's where the magic '8' comes from */
+ if (skb_ensure_writable(skb, hdroff + sizeof(*pgreh) - 8))
+ return false;
+
+ greh = (void *)skb->data + hdroff;
+ pgreh = (struct pptp_gre_header *)greh;
+
+ /* we only have destination manip of a packet, since 'source key'
+ * is not present in the packet itself */
+ if (maniptype != NF_NAT_MANIP_DST)
+ return true;
+
+ switch (greh->flags & GRE_VERSION) {
+ case GRE_VERSION_0:
+ /* We do not currently NAT any GREv0 packets.
+ * Try to behave like "nf_nat_proto_unknown" */
+ break;
+ case GRE_VERSION_1:
+ pr_debug("call_id -> 0x%04x\n", ntohs(tuple->dst.u.gre.key));
+ pgreh->call_id = tuple->dst.u.gre.key;
+ break;
+ default:
+ pr_debug("can't nat unknown GRE version\n");
+ return false;
+ }
+#endif
+ return true;
+}
+
+static bool l4proto_manip_pkt(struct sk_buff *skb,
+ unsigned int iphdroff, unsigned int hdroff,
+ const struct nf_conntrack_tuple *tuple,
+ enum nf_nat_manip_type maniptype)
+{
+ switch (tuple->dst.protonum) {
+ case IPPROTO_TCP:
+ return tcp_manip_pkt(skb, iphdroff, hdroff,
+ tuple, maniptype);
+ case IPPROTO_UDP:
+ return udp_manip_pkt(skb, iphdroff, hdroff,
+ tuple, maniptype);
+ case IPPROTO_UDPLITE:
+ return udplite_manip_pkt(skb, iphdroff, hdroff,
+ tuple, maniptype);
+ case IPPROTO_SCTP:
+ return sctp_manip_pkt(skb, iphdroff, hdroff,
+ tuple, maniptype);
+ case IPPROTO_ICMP:
+ return icmp_manip_pkt(skb, iphdroff, hdroff,
+ tuple, maniptype);
+ case IPPROTO_ICMPV6:
+ return icmpv6_manip_pkt(skb, iphdroff, hdroff,
+ tuple, maniptype);
+ case IPPROTO_DCCP:
+ return dccp_manip_pkt(skb, iphdroff, hdroff,
+ tuple, maniptype);
+ case IPPROTO_GRE:
+ return gre_manip_pkt(skb, iphdroff, hdroff,
+ tuple, maniptype);
+ }
+
+ /* If we don't know protocol -- no error, pass it unmodified. */
+ return true;
+}
+
+static bool nf_nat_ipv4_manip_pkt(struct sk_buff *skb,
+ unsigned int iphdroff,
+ const struct nf_conntrack_tuple *target,
+ enum nf_nat_manip_type maniptype)
+{
+ struct iphdr *iph;
+ unsigned int hdroff;
+
+ if (skb_ensure_writable(skb, iphdroff + sizeof(*iph)))
+ return false;
+
+ iph = (void *)skb->data + iphdroff;
+ hdroff = iphdroff + iph->ihl * 4;
+
+ if (!l4proto_manip_pkt(skb, iphdroff, hdroff, target, maniptype))
+ return false;
+ iph = (void *)skb->data + iphdroff;
+
+ if (maniptype == NF_NAT_MANIP_SRC) {
+ csum_replace4(&iph->check, iph->saddr, target->src.u3.ip);
+ iph->saddr = target->src.u3.ip;
+ } else {
+ csum_replace4(&iph->check, iph->daddr, target->dst.u3.ip);
+ iph->daddr = target->dst.u3.ip;
+ }
+ return true;
+}
+
+static bool nf_nat_ipv6_manip_pkt(struct sk_buff *skb,
+ unsigned int iphdroff,
+ const struct nf_conntrack_tuple *target,
+ enum nf_nat_manip_type maniptype)
+{
+#if IS_ENABLED(CONFIG_IPV6)
+ struct ipv6hdr *ipv6h;
+ __be16 frag_off;
+ int hdroff;
+ u8 nexthdr;
+
+ if (skb_ensure_writable(skb, iphdroff + sizeof(*ipv6h)))
+ return false;
+
+ ipv6h = (void *)skb->data + iphdroff;
+ nexthdr = ipv6h->nexthdr;
+ hdroff = ipv6_skip_exthdr(skb, iphdroff + sizeof(*ipv6h),
+ &nexthdr, &frag_off);
+ if (hdroff < 0)
+ goto manip_addr;
+
+ if ((frag_off & htons(~0x7)) == 0 &&
+ !l4proto_manip_pkt(skb, iphdroff, hdroff, target, maniptype))
+ return false;
+
+ /* must reload, offset might have changed */
+ ipv6h = (void *)skb->data + iphdroff;
+
+manip_addr:
+ if (maniptype == NF_NAT_MANIP_SRC)
+ ipv6h->saddr = target->src.u3.in6;
+ else
+ ipv6h->daddr = target->dst.u3.in6;
+
+#endif
+ return true;
+}
+
+unsigned int nf_nat_manip_pkt(struct sk_buff *skb, struct nf_conn *ct,
+ enum nf_nat_manip_type mtype,
+ enum ip_conntrack_dir dir)
+{
+ struct nf_conntrack_tuple target;
+
+ /* We are aiming to look like inverse of other direction. */
+ nf_ct_invert_tuple(&target, &ct->tuplehash[!dir].tuple);
+
+ switch (target.src.l3num) {
+ case NFPROTO_IPV6:
+ if (nf_nat_ipv6_manip_pkt(skb, 0, &target, mtype))
+ return NF_ACCEPT;
+ break;
+ case NFPROTO_IPV4:
+ if (nf_nat_ipv4_manip_pkt(skb, 0, &target, mtype))
+ return NF_ACCEPT;
+ break;
+ default:
+ WARN_ON_ONCE(1);
+ break;
+ }
+
+ return NF_DROP;
+}
+
+static void nf_nat_ipv4_csum_update(struct sk_buff *skb,
+ unsigned int iphdroff, __sum16 *check,
+ const struct nf_conntrack_tuple *t,
+ enum nf_nat_manip_type maniptype)
+{
+ struct iphdr *iph = (struct iphdr *)(skb->data + iphdroff);
+ __be32 oldip, newip;
+
+ if (maniptype == NF_NAT_MANIP_SRC) {
+ oldip = iph->saddr;
+ newip = t->src.u3.ip;
+ } else {
+ oldip = iph->daddr;
+ newip = t->dst.u3.ip;
+ }
+ inet_proto_csum_replace4(check, skb, oldip, newip, true);
+}
+
+static void nf_nat_ipv6_csum_update(struct sk_buff *skb,
+ unsigned int iphdroff, __sum16 *check,
+ const struct nf_conntrack_tuple *t,
+ enum nf_nat_manip_type maniptype)
+{
+#if IS_ENABLED(CONFIG_IPV6)
+ const struct ipv6hdr *ipv6h = (struct ipv6hdr *)(skb->data + iphdroff);
+ const struct in6_addr *oldip, *newip;
+
+ if (maniptype == NF_NAT_MANIP_SRC) {
+ oldip = &ipv6h->saddr;
+ newip = &t->src.u3.in6;
+ } else {
+ oldip = &ipv6h->daddr;
+ newip = &t->dst.u3.in6;
+ }
+ inet_proto_csum_replace16(check, skb, oldip->s6_addr32,
+ newip->s6_addr32, true);
+#endif
+}
+
+static void nf_csum_update(struct sk_buff *skb,
+ unsigned int iphdroff, __sum16 *check,
+ const struct nf_conntrack_tuple *t,
+ enum nf_nat_manip_type maniptype)
+{
+ switch (t->src.l3num) {
+ case NFPROTO_IPV4:
+ nf_nat_ipv4_csum_update(skb, iphdroff, check, t, maniptype);
+ return;
+ case NFPROTO_IPV6:
+ nf_nat_ipv6_csum_update(skb, iphdroff, check, t, maniptype);
+ return;
+ }
+}
+
+static void nf_nat_ipv4_csum_recalc(struct sk_buff *skb,
+ u8 proto, void *data, __sum16 *check,
+ int datalen, int oldlen)
+{
+ if (skb->ip_summed != CHECKSUM_PARTIAL) {
+ const struct iphdr *iph = ip_hdr(skb);
+
+ skb->ip_summed = CHECKSUM_PARTIAL;
+ skb->csum_start = skb_headroom(skb) + skb_network_offset(skb) +
+ ip_hdrlen(skb);
+ skb->csum_offset = (void *)check - data;
+ *check = ~csum_tcpudp_magic(iph->saddr, iph->daddr, datalen,
+ proto, 0);
+ } else {
+ inet_proto_csum_replace2(check, skb,
+ htons(oldlen), htons(datalen), true);
+ }
+}
+
+#if IS_ENABLED(CONFIG_IPV6)
+static void nf_nat_ipv6_csum_recalc(struct sk_buff *skb,
+ u8 proto, void *data, __sum16 *check,
+ int datalen, int oldlen)
+{
+ if (skb->ip_summed != CHECKSUM_PARTIAL) {
+ const struct ipv6hdr *ipv6h = ipv6_hdr(skb);
+
+ skb->ip_summed = CHECKSUM_PARTIAL;
+ skb->csum_start = skb_headroom(skb) + skb_network_offset(skb) +
+ (data - (void *)skb->data);
+ skb->csum_offset = (void *)check - data;
+ *check = ~csum_ipv6_magic(&ipv6h->saddr, &ipv6h->daddr,
+ datalen, proto, 0);
+ } else {
+ inet_proto_csum_replace2(check, skb,
+ htons(oldlen), htons(datalen), true);
+ }
+}
+#endif
+
+void nf_nat_csum_recalc(struct sk_buff *skb,
+ u8 nfproto, u8 proto, void *data, __sum16 *check,
+ int datalen, int oldlen)
+{
+ switch (nfproto) {
+ case NFPROTO_IPV4:
+ nf_nat_ipv4_csum_recalc(skb, proto, data, check,
+ datalen, oldlen);
+ return;
+#if IS_ENABLED(CONFIG_IPV6)
+ case NFPROTO_IPV6:
+ nf_nat_ipv6_csum_recalc(skb, proto, data, check,
+ datalen, oldlen);
+ return;
+#endif
+ }
+
+ WARN_ON_ONCE(1);
+}
+
+int nf_nat_icmp_reply_translation(struct sk_buff *skb,
+ struct nf_conn *ct,
+ enum ip_conntrack_info ctinfo,
+ unsigned int hooknum)
+{
+ struct {
+ struct icmphdr icmp;
+ struct iphdr ip;
+ } *inside;
+ enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
+ enum nf_nat_manip_type manip = HOOK2MANIP(hooknum);
+ unsigned int hdrlen = ip_hdrlen(skb);
+ struct nf_conntrack_tuple target;
+ unsigned long statusbit;
+
+ WARN_ON(ctinfo != IP_CT_RELATED && ctinfo != IP_CT_RELATED_REPLY);
+
+ if (skb_ensure_writable(skb, hdrlen + sizeof(*inside)))
+ return 0;
+ if (nf_ip_checksum(skb, hooknum, hdrlen, IPPROTO_ICMP))
+ return 0;
+
+ inside = (void *)skb->data + hdrlen;
+ if (inside->icmp.type == ICMP_REDIRECT) {
+ if ((ct->status & IPS_NAT_DONE_MASK) != IPS_NAT_DONE_MASK)
+ return 0;
+ if (ct->status & IPS_NAT_MASK)
+ return 0;
+ }
+
+ if (manip == NF_NAT_MANIP_SRC)
+ statusbit = IPS_SRC_NAT;
+ else
+ statusbit = IPS_DST_NAT;
+
+ /* Invert if this is reply direction */
+ if (dir == IP_CT_DIR_REPLY)
+ statusbit ^= IPS_NAT_MASK;
+
+ if (!(ct->status & statusbit))
+ return 1;
+
+ if (!nf_nat_ipv4_manip_pkt(skb, hdrlen + sizeof(inside->icmp),
+ &ct->tuplehash[!dir].tuple, !manip))
+ return 0;
+
+ if (skb->ip_summed != CHECKSUM_PARTIAL) {
+ /* Reloading "inside" here since manip_pkt may reallocate */
+ inside = (void *)skb->data + hdrlen;
+ inside->icmp.checksum = 0;
+ inside->icmp.checksum =
+ csum_fold(skb_checksum(skb, hdrlen,
+ skb->len - hdrlen, 0));
+ }
+
+ /* Change outer to look like the reply to an incoming packet */
+ nf_ct_invert_tuple(&target, &ct->tuplehash[!dir].tuple);
+ target.dst.protonum = IPPROTO_ICMP;
+ if (!nf_nat_ipv4_manip_pkt(skb, 0, &target, manip))
+ return 0;
+
+ return 1;
+}
+EXPORT_SYMBOL_GPL(nf_nat_icmp_reply_translation);
+
+static unsigned int
+nf_nat_ipv4_fn(void *priv, struct sk_buff *skb,
+ const struct nf_hook_state *state)
+{
+ struct nf_conn *ct;
+ enum ip_conntrack_info ctinfo;
+
+ ct = nf_ct_get(skb, &ctinfo);
+ if (!ct)
+ return NF_ACCEPT;
+
+ if (ctinfo == IP_CT_RELATED || ctinfo == IP_CT_RELATED_REPLY) {
+ if (ip_hdr(skb)->protocol == IPPROTO_ICMP) {
+ if (!nf_nat_icmp_reply_translation(skb, ct, ctinfo,
+ state->hook))
+ return NF_DROP;
+ else
+ return NF_ACCEPT;
+ }
+ }
+
+ return nf_nat_inet_fn(priv, skb, state);
+}
+
+static unsigned int
+nf_nat_ipv4_pre_routing(void *priv, struct sk_buff *skb,
+ const struct nf_hook_state *state)
+{
+ unsigned int ret;
+ __be32 daddr = ip_hdr(skb)->daddr;
+
+ ret = nf_nat_ipv4_fn(priv, skb, state);
+ if (ret == NF_ACCEPT && daddr != ip_hdr(skb)->daddr)
+ skb_dst_drop(skb);
+
+ return ret;
+}
+
+#ifdef CONFIG_XFRM
+static int nf_xfrm_me_harder(struct net *net, struct sk_buff *skb, unsigned int family)
+{
+ struct sock *sk = skb->sk;
+ struct dst_entry *dst;
+ unsigned int hh_len;
+ struct flowi fl;
+ int err;
+
+ err = xfrm_decode_session(skb, &fl, family);
+ if (err < 0)
+ return err;
+
+ dst = skb_dst(skb);
+ if (dst->xfrm)
+ dst = ((struct xfrm_dst *)dst)->route;
+ if (!dst_hold_safe(dst))
+ return -EHOSTUNREACH;
+
+ if (sk && !net_eq(net, sock_net(sk)))
+ sk = NULL;
+
+ dst = xfrm_lookup(net, dst, &fl, sk, 0);
+ if (IS_ERR(dst))
+ return PTR_ERR(dst);
+
+ skb_dst_drop(skb);
+ skb_dst_set(skb, dst);
+
+ /* Change in oif may mean change in hh_len. */
+ hh_len = skb_dst(skb)->dev->hard_header_len;
+ if (skb_headroom(skb) < hh_len &&
+ pskb_expand_head(skb, hh_len - skb_headroom(skb), 0, GFP_ATOMIC))
+ return -ENOMEM;
+ return 0;
+}
+#endif
+
+static unsigned int
+nf_nat_ipv4_local_in(void *priv, struct sk_buff *skb,
+ const struct nf_hook_state *state)
+{
+ __be32 saddr = ip_hdr(skb)->saddr;
+ struct sock *sk = skb->sk;
+ unsigned int ret;
+
+ ret = nf_nat_ipv4_fn(priv, skb, state);
+
+ if (ret == NF_ACCEPT && sk && saddr != ip_hdr(skb)->saddr &&
+ !inet_sk_transparent(sk))
+ skb_orphan(skb); /* TCP edemux obtained wrong socket */
+
+ return ret;
+}
+
+static unsigned int
+nf_nat_ipv4_out(void *priv, struct sk_buff *skb,
+ const struct nf_hook_state *state)
+{
+#ifdef CONFIG_XFRM
+ const struct nf_conn *ct;
+ enum ip_conntrack_info ctinfo;
+ int err;
+#endif
+ unsigned int ret;
+
+ ret = nf_nat_ipv4_fn(priv, skb, state);
+#ifdef CONFIG_XFRM
+ if (ret != NF_ACCEPT)
+ return ret;
+
+ if (IPCB(skb)->flags & IPSKB_XFRM_TRANSFORMED)
+ return ret;
+
+ ct = nf_ct_get(skb, &ctinfo);
+ if (ct) {
+ enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
+
+ if (ct->tuplehash[dir].tuple.src.u3.ip !=
+ ct->tuplehash[!dir].tuple.dst.u3.ip ||
+ (ct->tuplehash[dir].tuple.dst.protonum != IPPROTO_ICMP &&
+ ct->tuplehash[dir].tuple.src.u.all !=
+ ct->tuplehash[!dir].tuple.dst.u.all)) {
+ err = nf_xfrm_me_harder(state->net, skb, AF_INET);
+ if (err < 0)
+ ret = NF_DROP_ERR(err);
+ }
+ }
+#endif
+ return ret;
+}
+
+static unsigned int
+nf_nat_ipv4_local_fn(void *priv, struct sk_buff *skb,
+ const struct nf_hook_state *state)
+{
+ const struct nf_conn *ct;
+ enum ip_conntrack_info ctinfo;
+ unsigned int ret;
+ int err;
+
+ ret = nf_nat_ipv4_fn(priv, skb, state);
+ if (ret != NF_ACCEPT)
+ return ret;
+
+ ct = nf_ct_get(skb, &ctinfo);
+ if (ct) {
+ enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
+
+ if (ct->tuplehash[dir].tuple.dst.u3.ip !=
+ ct->tuplehash[!dir].tuple.src.u3.ip) {
+ err = ip_route_me_harder(state->net, state->sk, skb, RTN_UNSPEC);
+ if (err < 0)
+ ret = NF_DROP_ERR(err);
+ }
+#ifdef CONFIG_XFRM
+ else if (!(IPCB(skb)->flags & IPSKB_XFRM_TRANSFORMED) &&
+ ct->tuplehash[dir].tuple.dst.protonum != IPPROTO_ICMP &&
+ ct->tuplehash[dir].tuple.dst.u.all !=
+ ct->tuplehash[!dir].tuple.src.u.all) {
+ err = nf_xfrm_me_harder(state->net, skb, AF_INET);
+ if (err < 0)
+ ret = NF_DROP_ERR(err);
+ }
+#endif
+ }
+ return ret;
+}
+
+static const struct nf_hook_ops nf_nat_ipv4_ops[] = {
+ /* Before packet filtering, change destination */
+ {
+ .hook = nf_nat_ipv4_pre_routing,
+ .pf = NFPROTO_IPV4,
+ .hooknum = NF_INET_PRE_ROUTING,
+ .priority = NF_IP_PRI_NAT_DST,
+ },
+ /* After packet filtering, change source */
+ {
+ .hook = nf_nat_ipv4_out,
+ .pf = NFPROTO_IPV4,
+ .hooknum = NF_INET_POST_ROUTING,
+ .priority = NF_IP_PRI_NAT_SRC,
+ },
+ /* Before packet filtering, change destination */
+ {
+ .hook = nf_nat_ipv4_local_fn,
+ .pf = NFPROTO_IPV4,
+ .hooknum = NF_INET_LOCAL_OUT,
+ .priority = NF_IP_PRI_NAT_DST,
+ },
+ /* After packet filtering, change source */
+ {
+ .hook = nf_nat_ipv4_local_in,
+ .pf = NFPROTO_IPV4,
+ .hooknum = NF_INET_LOCAL_IN,
+ .priority = NF_IP_PRI_NAT_SRC,
+ },
+};
+
+int nf_nat_ipv4_register_fn(struct net *net, const struct nf_hook_ops *ops)
+{
+ return nf_nat_register_fn(net, ops->pf, ops, nf_nat_ipv4_ops,
+ ARRAY_SIZE(nf_nat_ipv4_ops));
+}
+EXPORT_SYMBOL_GPL(nf_nat_ipv4_register_fn);
+
+void nf_nat_ipv4_unregister_fn(struct net *net, const struct nf_hook_ops *ops)
+{
+ nf_nat_unregister_fn(net, ops->pf, ops, ARRAY_SIZE(nf_nat_ipv4_ops));
+}
+EXPORT_SYMBOL_GPL(nf_nat_ipv4_unregister_fn);
+
+#if IS_ENABLED(CONFIG_IPV6)
+int nf_nat_icmpv6_reply_translation(struct sk_buff *skb,
+ struct nf_conn *ct,
+ enum ip_conntrack_info ctinfo,
+ unsigned int hooknum,
+ unsigned int hdrlen)
+{
+ struct {
+ struct icmp6hdr icmp6;
+ struct ipv6hdr ip6;
+ } *inside;
+ enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
+ enum nf_nat_manip_type manip = HOOK2MANIP(hooknum);
+ struct nf_conntrack_tuple target;
+ unsigned long statusbit;
+
+ WARN_ON(ctinfo != IP_CT_RELATED && ctinfo != IP_CT_RELATED_REPLY);
+
+ if (skb_ensure_writable(skb, hdrlen + sizeof(*inside)))
+ return 0;
+ if (nf_ip6_checksum(skb, hooknum, hdrlen, IPPROTO_ICMPV6))
+ return 0;
+
+ inside = (void *)skb->data + hdrlen;
+ if (inside->icmp6.icmp6_type == NDISC_REDIRECT) {
+ if ((ct->status & IPS_NAT_DONE_MASK) != IPS_NAT_DONE_MASK)
+ return 0;
+ if (ct->status & IPS_NAT_MASK)
+ return 0;
+ }
+
+ if (manip == NF_NAT_MANIP_SRC)
+ statusbit = IPS_SRC_NAT;
+ else
+ statusbit = IPS_DST_NAT;
+
+ /* Invert if this is reply direction */
+ if (dir == IP_CT_DIR_REPLY)
+ statusbit ^= IPS_NAT_MASK;
+
+ if (!(ct->status & statusbit))
+ return 1;
+
+ if (!nf_nat_ipv6_manip_pkt(skb, hdrlen + sizeof(inside->icmp6),
+ &ct->tuplehash[!dir].tuple, !manip))
+ return 0;
+
+ if (skb->ip_summed != CHECKSUM_PARTIAL) {
+ struct ipv6hdr *ipv6h = ipv6_hdr(skb);
+
+ inside = (void *)skb->data + hdrlen;
+ inside->icmp6.icmp6_cksum = 0;
+ inside->icmp6.icmp6_cksum =
+ csum_ipv6_magic(&ipv6h->saddr, &ipv6h->daddr,
+ skb->len - hdrlen, IPPROTO_ICMPV6,
+ skb_checksum(skb, hdrlen,
+ skb->len - hdrlen, 0));
+ }
+
+ nf_ct_invert_tuple(&target, &ct->tuplehash[!dir].tuple);
+ target.dst.protonum = IPPROTO_ICMPV6;
+ if (!nf_nat_ipv6_manip_pkt(skb, 0, &target, manip))
+ return 0;
+
+ return 1;
+}
+EXPORT_SYMBOL_GPL(nf_nat_icmpv6_reply_translation);
+
+static unsigned int
+nf_nat_ipv6_fn(void *priv, struct sk_buff *skb,
+ const struct nf_hook_state *state)
+{
+ struct nf_conn *ct;
+ enum ip_conntrack_info ctinfo;
+ __be16 frag_off;
+ int hdrlen;
+ u8 nexthdr;
+
+ ct = nf_ct_get(skb, &ctinfo);
+ /* Can't track? It's not due to stress, or conntrack would
+ * have dropped it. Hence it's the user's responsibilty to
+ * packet filter it out, or implement conntrack/NAT for that
+ * protocol. 8) --RR
+ */
+ if (!ct)
+ return NF_ACCEPT;
+
+ if (ctinfo == IP_CT_RELATED || ctinfo == IP_CT_RELATED_REPLY) {
+ nexthdr = ipv6_hdr(skb)->nexthdr;
+ hdrlen = ipv6_skip_exthdr(skb, sizeof(struct ipv6hdr),
+ &nexthdr, &frag_off);
+
+ if (hdrlen >= 0 && nexthdr == IPPROTO_ICMPV6) {
+ if (!nf_nat_icmpv6_reply_translation(skb, ct, ctinfo,
+ state->hook,
+ hdrlen))
+ return NF_DROP;
+ else
+ return NF_ACCEPT;
+ }
+ }
+
+ return nf_nat_inet_fn(priv, skb, state);
+}
+
+static unsigned int
+nf_nat_ipv6_in(void *priv, struct sk_buff *skb,
+ const struct nf_hook_state *state)
+{
+ unsigned int ret;
+ struct in6_addr daddr = ipv6_hdr(skb)->daddr;
+
+ ret = nf_nat_ipv6_fn(priv, skb, state);
+ if (ret != NF_DROP && ret != NF_STOLEN &&
+ ipv6_addr_cmp(&daddr, &ipv6_hdr(skb)->daddr))
+ skb_dst_drop(skb);
+
+ return ret;
+}
+
+static unsigned int
+nf_nat_ipv6_out(void *priv, struct sk_buff *skb,
+ const struct nf_hook_state *state)
+{
+#ifdef CONFIG_XFRM
+ const struct nf_conn *ct;
+ enum ip_conntrack_info ctinfo;
+ int err;
+#endif
+ unsigned int ret;
+
+ ret = nf_nat_ipv6_fn(priv, skb, state);
+#ifdef CONFIG_XFRM
+ if (ret != NF_ACCEPT)
+ return ret;
+
+ if (IP6CB(skb)->flags & IP6SKB_XFRM_TRANSFORMED)
+ return ret;
+ ct = nf_ct_get(skb, &ctinfo);
+ if (ct) {
+ enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
+
+ if (!nf_inet_addr_cmp(&ct->tuplehash[dir].tuple.src.u3,
+ &ct->tuplehash[!dir].tuple.dst.u3) ||
+ (ct->tuplehash[dir].tuple.dst.protonum != IPPROTO_ICMPV6 &&
+ ct->tuplehash[dir].tuple.src.u.all !=
+ ct->tuplehash[!dir].tuple.dst.u.all)) {
+ err = nf_xfrm_me_harder(state->net, skb, AF_INET6);
+ if (err < 0)
+ ret = NF_DROP_ERR(err);
+ }
+ }
+#endif
+
+ return ret;
+}
+
+static unsigned int
+nf_nat_ipv6_local_fn(void *priv, struct sk_buff *skb,
+ const struct nf_hook_state *state)
+{
+ const struct nf_conn *ct;
+ enum ip_conntrack_info ctinfo;
+ unsigned int ret;
+ int err;
+
+ ret = nf_nat_ipv6_fn(priv, skb, state);
+ if (ret != NF_ACCEPT)
+ return ret;
+
+ ct = nf_ct_get(skb, &ctinfo);
+ if (ct) {
+ enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
+
+ if (!nf_inet_addr_cmp(&ct->tuplehash[dir].tuple.dst.u3,
+ &ct->tuplehash[!dir].tuple.src.u3)) {
+ err = nf_ip6_route_me_harder(state->net, state->sk, skb);
+ if (err < 0)
+ ret = NF_DROP_ERR(err);
+ }
+#ifdef CONFIG_XFRM
+ else if (!(IP6CB(skb)->flags & IP6SKB_XFRM_TRANSFORMED) &&
+ ct->tuplehash[dir].tuple.dst.protonum != IPPROTO_ICMPV6 &&
+ ct->tuplehash[dir].tuple.dst.u.all !=
+ ct->tuplehash[!dir].tuple.src.u.all) {
+ err = nf_xfrm_me_harder(state->net, skb, AF_INET6);
+ if (err < 0)
+ ret = NF_DROP_ERR(err);
+ }
+#endif
+ }
+
+ return ret;
+}
+
+static const struct nf_hook_ops nf_nat_ipv6_ops[] = {
+ /* Before packet filtering, change destination */
+ {
+ .hook = nf_nat_ipv6_in,
+ .pf = NFPROTO_IPV6,
+ .hooknum = NF_INET_PRE_ROUTING,
+ .priority = NF_IP6_PRI_NAT_DST,
+ },
+ /* After packet filtering, change source */
+ {
+ .hook = nf_nat_ipv6_out,
+ .pf = NFPROTO_IPV6,
+ .hooknum = NF_INET_POST_ROUTING,
+ .priority = NF_IP6_PRI_NAT_SRC,
+ },
+ /* Before packet filtering, change destination */
+ {
+ .hook = nf_nat_ipv6_local_fn,
+ .pf = NFPROTO_IPV6,
+ .hooknum = NF_INET_LOCAL_OUT,
+ .priority = NF_IP6_PRI_NAT_DST,
+ },
+ /* After packet filtering, change source */
+ {
+ .hook = nf_nat_ipv6_fn,
+ .pf = NFPROTO_IPV6,
+ .hooknum = NF_INET_LOCAL_IN,
+ .priority = NF_IP6_PRI_NAT_SRC,
+ },
+};
+
+int nf_nat_ipv6_register_fn(struct net *net, const struct nf_hook_ops *ops)
+{
+ return nf_nat_register_fn(net, ops->pf, ops, nf_nat_ipv6_ops,
+ ARRAY_SIZE(nf_nat_ipv6_ops));
+}
+EXPORT_SYMBOL_GPL(nf_nat_ipv6_register_fn);
+
+void nf_nat_ipv6_unregister_fn(struct net *net, const struct nf_hook_ops *ops)
+{
+ nf_nat_unregister_fn(net, ops->pf, ops, ARRAY_SIZE(nf_nat_ipv6_ops));
+}
+EXPORT_SYMBOL_GPL(nf_nat_ipv6_unregister_fn);
+#endif /* CONFIG_IPV6 */
+
+#if defined(CONFIG_NF_TABLES_INET) && IS_ENABLED(CONFIG_NFT_NAT)
+int nf_nat_inet_register_fn(struct net *net, const struct nf_hook_ops *ops)
+{
+ int ret;
+
+ if (WARN_ON_ONCE(ops->pf != NFPROTO_INET))
+ return -EINVAL;
+
+ ret = nf_nat_register_fn(net, NFPROTO_IPV6, ops, nf_nat_ipv6_ops,
+ ARRAY_SIZE(nf_nat_ipv6_ops));
+ if (ret)
+ return ret;
+
+ ret = nf_nat_register_fn(net, NFPROTO_IPV4, ops, nf_nat_ipv4_ops,
+ ARRAY_SIZE(nf_nat_ipv4_ops));
+ if (ret)
+ nf_nat_unregister_fn(net, NFPROTO_IPV6, ops,
+ ARRAY_SIZE(nf_nat_ipv6_ops));
+ return ret;
+}
+EXPORT_SYMBOL_GPL(nf_nat_inet_register_fn);
+
+void nf_nat_inet_unregister_fn(struct net *net, const struct nf_hook_ops *ops)
+{
+ nf_nat_unregister_fn(net, NFPROTO_IPV4, ops, ARRAY_SIZE(nf_nat_ipv4_ops));
+ nf_nat_unregister_fn(net, NFPROTO_IPV6, ops, ARRAY_SIZE(nf_nat_ipv6_ops));
+}
+EXPORT_SYMBOL_GPL(nf_nat_inet_unregister_fn);
+#endif /* NFT INET NAT */
generated by cgit v1.2.3 (git 2.39.1) at 2024-06-09 16:44:31 +0000