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conf, tcp, udp: Add --no-map-gw to disable mapping gateway address to host

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Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
This commit is contained in:
Stefano Brivio 2021-10-14 05:26:37 +02:00
parent 3bb859c505
commit f45891cf26
5 changed files with 15 additions and 5 deletions
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2
conf.c
View file

@ -600,6 +600,7 @@ static void usage(const char *name)
info( " --no-ndp Disable NDP responses");
info( " --no-dhcpv6 Disable DHCPv6 server");
info( " --no-ra Disable router advertisements");
info( " --no-map-gw Don't map gateway address to host");
info( " -4, --ipv4-only Enable IPv4 operation only");
info( " -6, --ipv6-only Enable IPv6 operation only");
@ -776,6 +777,7 @@ void conf(struct ctx *c, int argc, char **argv)
{"no-dhcpv6", no_argument, &c->no_dhcpv6, 1 },
{"no-ndp", no_argument, &c->no_ndp, 1 },
{"no-ra", no_argument, &c->no_ra, 1 },
{"no-map-gw", no_argument, &c->no_map_gw, 1 },
{"ipv4-only", no_argument, &c->v4, '4' },
{"ipv6-only", no_argument, &c->v6, '6' },
{"tcp-ports", required_argument, NULL, 't' },

7
passt.1
View file

@ -207,6 +207,11 @@ namespace will be silently dropped.
Disable Router Advertisements. Router Solicitations coming from guest or target
namespace will be ignored.
.TP
.BR \-\-no-map-gw
Don't remap TCP connections and untracked UDP traffic, with the gateway address
as destination, to the host.
.TP
.BR \-4 ", " \-\-ipv4-only
Enable IPv4-only operation. IPv6 traffic will be ignored.
@ -635,7 +640,7 @@ address corresponding to the default gateway will have their destination address
translated to a loopback address, if and only if a packet, in the opposite
direction, with a loopback destination or source address, port-wise matching for
UDP, or connection-wise for TCP, has been recently forwarded to guest or
namespace.
namespace. This behaviour can be disabled with \-\-no\-map\-gw.
.SS Handling of local traffic in pasta

2
passt.h
View file

@ -130,6 +130,7 @@ enum passt_modes {
* @no_dhcpv6: Disable DHCPv6 server
* @no_ndp: Disable NDP handler altogether
* @no_ra: Disable router advertisements
* @no_map_gw: Don't map connections, untracked UDP to gateway to host
* @low_wmem: Low probed net.core.wmem_max
* @low_rmem: Low probed net.core.rmem_max
*/
@ -188,6 +189,7 @@ struct ctx {
int no_dhcpv6;
int no_ndp;
int no_ra;
int no_map_gw;
int low_wmem;
int low_rmem;

5
tcp.c
View file

@ -1845,9 +1845,10 @@ static void tcp_conn_from_tap(struct ctx *c, int af, void *addr,
tcp_sock_set_bufsize(c, s);
if (af == AF_INET && addr4.sin_addr.s_addr == c->gw4)
if (af == AF_INET && addr4.sin_addr.s_addr == c->gw4 && !c->no_map_gw)
addr4.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
else if (af == AF_INET6 && !memcmp(addr, &c->gw6, sizeof(c->gw6)))
else if (af == AF_INET6 && !memcmp(addr, &c->gw6, sizeof(c->gw6)) &&
!c->no_map_gw)
addr6.sin6_addr = in6addr_loopback;
if (af == AF_INET6 && IN6_IS_ADDR_LINKLOCAL(&addr6.sin6_addr)) {

4
udp.c
View file

@ -933,7 +933,7 @@ int udp_tap_handler(struct ctx *c, int af, void *addr,
udp_tap_map[V4][src].ts = now->tv_sec;
if (s_in.sin_addr.s_addr == c->gw4) {
if (s_in.sin_addr.s_addr == c->gw4 && !c->no_map_gw) {
if (!udp_tap_map[V4][dst].ts_local ||
udp_tap_map[V4][dst].loopback)
s_in.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
@ -951,7 +951,7 @@ int udp_tap_handler(struct ctx *c, int af, void *addr,
sa = (struct sockaddr *)&s_in6;
sl = sizeof(s_in6);
if (!memcmp(addr, &c->gw6, sizeof(c->gw6))) {
if (!memcmp(addr, &c->gw6, sizeof(c->gw6)) && !c->no_map_gw) {
if (!udp_tap_map[V6][dst].ts_local ||
udp_tap_map[V6][dst].loopback)
s_in6.sin6_addr = in6addr_loopback;