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-rw-r--r--net/netfilter/nf_nat_proto.c343
1 files changed, 343 insertions, 0 deletions
diff --git a/net/netfilter/nf_nat_proto.c b/net/netfilter/nf_nat_proto.c
new file mode 100644
index 000000000000..f83bf9d8c9f5
--- /dev/null
+++ b/net/netfilter/nf_nat_proto.c
@@ -0,0 +1,343 @@
+/* (C) 1999-2001 Paul `Rusty' Russell
+ * (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#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 <net/netfilter/nf_nat_core.h>
+#include <net/netfilter/nf_nat_l3proto.h>
+#include <net/netfilter/nf_nat_l4proto.h>
+
+static void
+__udp_manip_pkt(struct sk_buff *skb,
+ const struct nf_nat_l3proto *l3proto,
+ 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) {
+ l3proto->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,
+ const struct nf_nat_l3proto *l3proto,
+ unsigned int iphdroff, unsigned int hdroff,
+ const struct nf_conntrack_tuple *tuple,
+ enum nf_nat_manip_type maniptype)
+{
+ struct udphdr *hdr;
+ bool do_csum;
+
+ if (!skb_make_writable(skb, hdroff + sizeof(*hdr)))
+ return false;
+
+ hdr = (struct udphdr *)(skb->data + hdroff);
+ do_csum = hdr->check || skb->ip_summed == CHECKSUM_PARTIAL;
+
+ __udp_manip_pkt(skb, l3proto, iphdroff, hdr, tuple, maniptype, do_csum);
+ return true;
+}
+
+static bool udplite_manip_pkt(struct sk_buff *skb,
+ const struct nf_nat_l3proto *l3proto,
+ 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_make_writable(skb, hdroff + sizeof(*hdr)))
+ return false;
+
+ hdr = (struct udphdr *)(skb->data + hdroff);
+ __udp_manip_pkt(skb, l3proto, iphdroff, hdr, tuple, maniptype, true);
+#endif
+ return true;
+}
+
+static bool
+sctp_manip_pkt(struct sk_buff *skb,
+ const struct nf_nat_l3proto *l3proto,
+ 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_make_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,
+ const struct nf_nat_l3proto *l3proto,
+ 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_make_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;
+
+ l3proto->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,
+ const struct nf_nat_l3proto *l3proto,
+ 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_make_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;
+
+ l3proto->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,
+ const struct nf_nat_l3proto *l3proto,
+ unsigned int iphdroff, unsigned int hdroff,
+ const struct nf_conntrack_tuple *tuple,
+ enum nf_nat_manip_type maniptype)
+{
+ struct icmphdr *hdr;
+
+ if (!skb_make_writable(skb, hdroff + sizeof(*hdr)))
+ return false;
+
+ hdr = (struct icmphdr *)(skb->data + hdroff);
+ 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,
+ const struct nf_nat_l3proto *l3proto,
+ unsigned int iphdroff, unsigned int hdroff,
+ const struct nf_conntrack_tuple *tuple,
+ enum nf_nat_manip_type maniptype)
+{
+ struct icmp6hdr *hdr;
+
+ if (!skb_make_writable(skb, hdroff + sizeof(*hdr)))
+ return false;
+
+ hdr = (struct icmp6hdr *)(skb->data + hdroff);
+ l3proto->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,
+ const struct nf_nat_l3proto *l3proto,
+ 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_make_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;
+}
+
+bool nf_nat_l4proto_manip_pkt(struct sk_buff *skb,
+ const struct nf_nat_l3proto *l3proto,
+ 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, l3proto, iphdroff, hdroff,
+ tuple, maniptype);
+ case IPPROTO_UDP:
+ return udp_manip_pkt(skb, l3proto, iphdroff, hdroff,
+ tuple, maniptype);
+ case IPPROTO_UDPLITE:
+ return udplite_manip_pkt(skb, l3proto, iphdroff, hdroff,
+ tuple, maniptype);
+ case IPPROTO_SCTP:
+ return sctp_manip_pkt(skb, l3proto, iphdroff, hdroff,
+ tuple, maniptype);
+ case IPPROTO_ICMP:
+ return icmp_manip_pkt(skb, l3proto, iphdroff, hdroff,
+ tuple, maniptype);
+ case IPPROTO_ICMPV6:
+ return icmpv6_manip_pkt(skb, l3proto, iphdroff, hdroff,
+ tuple, maniptype);
+ case IPPROTO_DCCP:
+ return dccp_manip_pkt(skb, l3proto, iphdroff, hdroff,
+ tuple, maniptype);
+ case IPPROTO_GRE:
+ return gre_manip_pkt(skb, l3proto, iphdroff, hdroff,
+ tuple, maniptype);
+ }
+
+ /* If we don't know protocol -- no error, pass it unmodified. */
+ return true;
+}
+EXPORT_SYMBOL_GPL(nf_nat_l4proto_manip_pkt);
Copyright © 1996 – 2023 Jason A. Donenfeld. All Rights Reverse Engineered.