When we receive an ARP request or NDP neigbor solicitation over
the tap interface for a host on the local network segment attached
to the template interface, we respond with that host's real MAC
address.
The local host, which is acting as a proxy for the default gateway,
is still exempted from this rule.
Signed-off-by: Jon Maloy
---
arp.c | 9 +++++++++
fwd.c | 38 ++++++++++++++++++++++++++++++--------
fwd.h | 1 +
inany.c | 1 +
ndp.c | 9 +++++++++
5 files changed, 50 insertions(+), 8 deletions(-)
diff --git a/arp.c b/arp.c
index fc482bb..c37867a 100644
--- a/arp.c
+++ b/arp.c
@@ -29,6 +29,7 @@
#include "dhcp.h"
#include "passt.h"
#include "tap.h"
+#include "netlink.h"
/**
* arp() - Check if this is a supported ARP message, reply as needed
@@ -39,6 +40,7 @@
*/
int arp(const struct ctx *c, const struct pool *p)
{
+ union inany_addr tgt;
unsigned char swap[4];
struct ethhdr *eh;
struct arphdr *ah;
@@ -72,6 +74,13 @@ int arp(const struct ctx *c, const struct pool *p)
memcpy(am->tha, am->sha, sizeof(am->tha));
memcpy(am->sha, c->our_tap_mac, sizeof(am->sha));
+ /* Respond with true MAC address if remote host is on
+ * the template interface's network segment
+ */
+ inany_from_af(&tgt, AF_INET, am->tip);
+ if (!fwd_inany_nat(c, &tgt))
+ nl_neigh_mac_get(nl_sock, &tgt, c->ifi4, am->sha);
+
memcpy(swap, am->tip, sizeof(am->tip));
memcpy(am->tip, am->sip, sizeof(am->tip));
memcpy(am->sip, swap, sizeof(am->sip));
diff --git a/fwd.c b/fwd.c
index 250cf56..55bf5f2 100644
--- a/fwd.c
+++ b/fwd.c
@@ -331,20 +331,29 @@ static bool fwd_guest_accessible(const struct ctx *c,
*
* Only handles translations that depend *only* on the address. Anything
* related to specific ports or flows is handled elsewhere.
+ *
+ * Return: true if there was a translation, otherwise false
*/
-static void nat_outbound(const struct ctx *c, const union inany_addr *addr,
- union inany_addr *translated)
+static bool nat_outbound(const struct ctx *c, const union inany_addr *addr,
+ union inany_addr *translated)
{
- if (inany_equals4(addr, &c->ip4.map_host_loopback))
+ if (inany_equals4(addr, &c->ip4.map_host_loopback)) {
*translated = inany_loopback4;
- else if (inany_equals6(addr, &c->ip6.map_host_loopback))
+ return true;
+ } else if (inany_equals6(addr, &c->ip6.map_host_loopback)) {
*translated = inany_loopback6;
- else if (inany_equals4(addr, &c->ip4.map_guest_addr))
+ return true;
+ } else if (inany_equals4(addr, &c->ip4.map_guest_addr)) {
*translated = inany_from_v4(c->ip4.addr);
- else if (inany_equals6(addr, &c->ip6.map_guest_addr))
+ return true;
+ } else if (inany_equals6(addr, &c->ip6.map_guest_addr)) {
translated->a6 = c->ip6.addr;
- else
- *translated = *addr;
+ return true;
+ }
+
+ *translated = *addr;
+ return false;
+
}
/**
@@ -554,3 +563,16 @@ uint8_t fwd_nat_from_host(const struct ctx *c, uint8_t proto,
return PIF_TAP;
}
+
+/** fwd_inany_nat - Find if a remote IPv[46] address is subject to NAT
+ * @c: Execution context
+ * @addr: IPv[46] address
+ *
+ * Return: true if translated, false otherwise
+ */
+bool fwd_inany_nat(const struct ctx *c, const union inany_addr *addr)
+{
+ union inany_addr addr_nat;
+
+ return nat_outbound(c, addr, &addr_nat);
+}
diff --git a/fwd.h b/fwd.h
index 65c7c96..c8d485d 100644
--- a/fwd.h
+++ b/fwd.h
@@ -56,5 +56,6 @@ uint8_t fwd_nat_from_splice(const struct ctx *c, uint8_t proto,
const struct flowside *ini, struct flowside *tgt);
uint8_t fwd_nat_from_host(const struct ctx *c, uint8_t proto,
const struct flowside *ini, struct flowside *tgt);
+bool fwd_inany_nat(const struct ctx *c, const union inany_addr *addr);
#endif /* FWD_H */
diff --git a/inany.c b/inany.c
index 65a39f9..7680439 100644
--- a/inany.c
+++ b/inany.c
@@ -16,6 +16,7 @@
#include "ip.h"
#include "siphash.h"
#include "inany.h"
+#include "fwd.h"
const union inany_addr inany_loopback4 = INANY_INIT4(IN4ADDR_LOOPBACK_INIT);
const union inany_addr inany_any4 = INANY_INIT4(IN4ADDR_ANY_INIT);
diff --git a/ndp.c b/ndp.c
index 3e15494..9912f80 100644
--- a/ndp.c
+++ b/ndp.c
@@ -32,6 +32,7 @@
#include "passt.h"
#include "tap.h"
#include "log.h"
+#include "netlink.h"
#define RT_LIFETIME 65535
@@ -196,6 +197,7 @@ static void ndp_send(const struct ctx *c, const struct in6_addr *dst,
static void ndp_na(const struct ctx *c, const struct in6_addr *dst,
const struct in6_addr *addr)
{
+ union inany_addr tgt;
struct ndp_na na = {
.ih = {
.icmp6_type = NA,
@@ -215,6 +217,13 @@ static void ndp_na(const struct ctx *c, const struct in6_addr *dst,
memcpy(na.target_l2_addr.mac, c->our_tap_mac, ETH_ALEN);
+ /* Respond with true link-layer address if remote host is on
+ * the template interface's network segment
+ */
+ inany_from_af(&tgt, AF_INET6, addr);
+ if (!fwd_inany_nat(c, &tgt))
+ nl_neigh_mac_get(nl_sock, &tgt, c->ifi6, na.target_l2_addr.mac);
+
ndp_send(c, dst, &na, sizeof(na));
}
--
2.50.1