When we receive an ARP request or NDP neigbour 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, if available.
Signed-off-by: Jon Maloy
---
v3: - Added helper function to find out if a remote ip address is subject
to NAT. This filters out local host addresses which should be
presented with the passt/pasta local MAC address 9a:55:9a:55:9a:55 even
though it is on the local segment.
- Adapted to the change in nl_mac_get() function, so that we now consider
only the template interface when checking the ARP/NDP table.
v4: - Moved NAT check into the function nat_outbound() to obtain more
precise criteria for when NAT is used. We may in theory
have NAT even if original and translated addresses are equal, and
we want to catch this case.
- I chose to keep the wrapper funtion inany_nat(), but moved it to
fwd.h/fwd.c and renamed it to fwd_inany_nat().
v5: - Simplified criteria for when we do ARP/NDP lookup. Now, we
just try with the potentially translated address after an
attempted NAT check.
- Using the new ARP/NDP cache table instead of using netlink
directly.
v6: - Fixes after feedback from David:
- Renamed nat_outbound() to fwd_nat_outbound()
- Eliminated unnecessary temporary variable in arp.c::arp()
v12: - Some minor changes after feedback from Stefano
v13: - Removed call to nat_outbound() before MAC resolution, as
we are now handling guest-side visible addresses only.
v14: - Removed obsolete memcpy() in ndp.c::ndp_na()
---
arp.c | 8 ++++++--
inany.c | 1 +
ndp.c | 4 +++-
3 files changed, 10 insertions(+), 3 deletions(-)
diff --git a/arp.c b/arp.c
index ad088b1..b4a686f 100644
--- a/arp.c
+++ b/arp.c
@@ -69,6 +69,7 @@ static bool ignore_arp(const struct ctx *c,
*/
int arp(const struct ctx *c, struct iov_tail *data)
{
+ union inany_addr tgt;
struct {
struct ethhdr eh;
struct arphdr ah;
@@ -102,8 +103,11 @@ int arp(const struct ctx *c, struct iov_tail *data)
resp.ah.ar_hln = ah->ar_hln;
resp.ah.ar_pln = ah->ar_pln;
- /* ARP message */
- memcpy(resp.am.sha, c->our_tap_mac, sizeof(resp.am.sha));
+ /* MAC address to return in ARP message */
+ inany_from_af(&tgt, AF_INET, am->tip);
+ fwd_neigh_mac_get(c, &tgt, resp.am.sha);
+
+ /* Rest of ARP message */
memcpy(resp.am.sip, am->tip, sizeof(resp.am.sip));
memcpy(resp.am.tha, am->sha, sizeof(resp.am.tha));
memcpy(resp.am.tip, am->sip, sizeof(resp.am.tip));
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 588b48f..7e2ae2a 100644
--- a/ndp.c
+++ b/ndp.c
@@ -196,6 +196,7 @@ 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,
@@ -213,7 +214,8 @@ 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);
+ inany_from_af(&tgt, AF_INET6, addr);
+ fwd_neigh_mac_get(c, &tgt, na.target_l2_addr.mac);
ndp_send(c, dst, &na, sizeof(na));
}
--
2.50.1