From: Stefano Brivio <sbrivio@redhat.com>
To: passt-dev@passt.top
Cc: Paul Holzinger <pholzing@redhat.com>,
David Gibson <david@gibson.dropbear.id.au>
Subject: [PATCH v2 3/3] udp: Check for answers to forwarded DNS queries before handling local redirects
Date: Thu, 3 Nov 2022 07:33:41 +0100 [thread overview]
Message-ID: <20221103063341.401251-4-sbrivio@redhat.com> (raw)
In-Reply-To: <20221103063341.401251-1-sbrivio@redhat.com>
Now that we allow loopback DNS addresses to be used as targets for
forwarding, we need to check if DNS answers come from those targets,
before deciding to eventually remap traffic for local redirects.
Otherwise, the source address won't match the one configured as
forwarder, which means that the guest or the container will refuse
those responses.
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
---
udp.c | 22 +++++++++++-----------
1 file changed, 11 insertions(+), 11 deletions(-)
diff --git a/udp.c b/udp.c
index fca418d..42a17a7 100644
--- a/udp.c
+++ b/udp.c
@@ -678,9 +678,13 @@ static void udp_sock_fill_data_v4(const struct ctx *c, int n,
src_port = ntohs(b->s_in.sin_port);
- if (IN4_IS_ADDR_LOOPBACK(&b->s_in.sin_addr) ||
- IN4_IS_ADDR_UNSPECIFIED(&b->s_in.sin_addr)||
- IN4_ARE_ADDR_EQUAL(&b->s_in.sin_addr, &c->ip4.addr_seen)) {
+ if (!IN4_IS_ADDR_UNSPECIFIED(&c->ip4.dns_fwd) &&
+ IN4_ARE_ADDR_EQUAL(&b->s_in.sin_addr, &c->ip4.dns[0]) &&
+ src_port == 53) {
+ b->iph.saddr = c->ip4.dns_fwd.s_addr;
+ } else if (IN4_IS_ADDR_LOOPBACK(&b->s_in.sin_addr) ||
+ IN4_IS_ADDR_UNSPECIFIED(&b->s_in.sin_addr)||
+ IN4_ARE_ADDR_EQUAL(&b->s_in.sin_addr, &c->ip4.addr_seen)) {
b->iph.saddr = c->ip4.gw.s_addr;
udp_tap_map[V4][src_port].ts = now->tv_sec;
udp_tap_map[V4][src_port].flags |= PORT_LOCAL;
@@ -691,10 +695,6 @@ static void udp_sock_fill_data_v4(const struct ctx *c, int n,
udp_tap_map[V4][src_port].flags |= PORT_LOOPBACK;
bitmap_set(udp_act[V4][UDP_ACT_TAP], src_port);
- } else if (!IN4_IS_ADDR_UNSPECIFIED(&c->ip4.dns_fwd) &&
- IN4_ARE_ADDR_EQUAL(&b->s_in.sin_addr, &c->ip4.dns[0]) &&
- src_port == 53) {
- b->iph.saddr = c->ip4.dns_fwd.s_addr;
} else {
b->iph.saddr = b->s_in.sin_addr.s_addr;
}
@@ -770,6 +770,10 @@ static void udp_sock_fill_data_v6(const struct ctx *c, int n,
if (IN6_IS_ADDR_LINKLOCAL(src)) {
b->ip6h.daddr = c->ip6.addr_ll_seen;
b->ip6h.saddr = b->s_in6.sin6_addr;
+ } else if (!IN6_IS_ADDR_UNSPECIFIED(&c->ip6.dns_fwd) &&
+ IN6_ARE_ADDR_EQUAL(src, &c->ip6.dns[0]) && src_port == 53) {
+ b->ip6h.daddr = c->ip6.addr_seen;
+ b->ip6h.saddr = c->ip6.dns_fwd;
} else if (IN6_IS_ADDR_LOOPBACK(src) ||
IN6_ARE_ADDR_EQUAL(src, &c->ip6.addr_seen) ||
IN6_ARE_ADDR_EQUAL(src, &c->ip6.addr)) {
@@ -794,10 +798,6 @@ static void udp_sock_fill_data_v6(const struct ctx *c, int n,
udp_tap_map[V6][src_port].flags &= ~PORT_GUA;
bitmap_set(udp_act[V6][UDP_ACT_TAP], src_port);
- } else if (!IN6_IS_ADDR_UNSPECIFIED(&c->ip6.dns_fwd) &&
- IN6_ARE_ADDR_EQUAL(src, &c->ip6.dns[0]) && src_port == 53) {
- b->ip6h.daddr = c->ip6.addr_seen;
- b->ip6h.saddr = c->ip6.dns_fwd;
} else {
b->ip6h.daddr = c->ip6.addr_seen;
b->ip6h.saddr = b->s_in6.sin6_addr;
--
@@ -678,9 +678,13 @@ static void udp_sock_fill_data_v4(const struct ctx *c, int n,
src_port = ntohs(b->s_in.sin_port);
- if (IN4_IS_ADDR_LOOPBACK(&b->s_in.sin_addr) ||
- IN4_IS_ADDR_UNSPECIFIED(&b->s_in.sin_addr)||
- IN4_ARE_ADDR_EQUAL(&b->s_in.sin_addr, &c->ip4.addr_seen)) {
+ if (!IN4_IS_ADDR_UNSPECIFIED(&c->ip4.dns_fwd) &&
+ IN4_ARE_ADDR_EQUAL(&b->s_in.sin_addr, &c->ip4.dns[0]) &&
+ src_port == 53) {
+ b->iph.saddr = c->ip4.dns_fwd.s_addr;
+ } else if (IN4_IS_ADDR_LOOPBACK(&b->s_in.sin_addr) ||
+ IN4_IS_ADDR_UNSPECIFIED(&b->s_in.sin_addr)||
+ IN4_ARE_ADDR_EQUAL(&b->s_in.sin_addr, &c->ip4.addr_seen)) {
b->iph.saddr = c->ip4.gw.s_addr;
udp_tap_map[V4][src_port].ts = now->tv_sec;
udp_tap_map[V4][src_port].flags |= PORT_LOCAL;
@@ -691,10 +695,6 @@ static void udp_sock_fill_data_v4(const struct ctx *c, int n,
udp_tap_map[V4][src_port].flags |= PORT_LOOPBACK;
bitmap_set(udp_act[V4][UDP_ACT_TAP], src_port);
- } else if (!IN4_IS_ADDR_UNSPECIFIED(&c->ip4.dns_fwd) &&
- IN4_ARE_ADDR_EQUAL(&b->s_in.sin_addr, &c->ip4.dns[0]) &&
- src_port == 53) {
- b->iph.saddr = c->ip4.dns_fwd.s_addr;
} else {
b->iph.saddr = b->s_in.sin_addr.s_addr;
}
@@ -770,6 +770,10 @@ static void udp_sock_fill_data_v6(const struct ctx *c, int n,
if (IN6_IS_ADDR_LINKLOCAL(src)) {
b->ip6h.daddr = c->ip6.addr_ll_seen;
b->ip6h.saddr = b->s_in6.sin6_addr;
+ } else if (!IN6_IS_ADDR_UNSPECIFIED(&c->ip6.dns_fwd) &&
+ IN6_ARE_ADDR_EQUAL(src, &c->ip6.dns[0]) && src_port == 53) {
+ b->ip6h.daddr = c->ip6.addr_seen;
+ b->ip6h.saddr = c->ip6.dns_fwd;
} else if (IN6_IS_ADDR_LOOPBACK(src) ||
IN6_ARE_ADDR_EQUAL(src, &c->ip6.addr_seen) ||
IN6_ARE_ADDR_EQUAL(src, &c->ip6.addr)) {
@@ -794,10 +798,6 @@ static void udp_sock_fill_data_v6(const struct ctx *c, int n,
udp_tap_map[V6][src_port].flags &= ~PORT_GUA;
bitmap_set(udp_act[V6][UDP_ACT_TAP], src_port);
- } else if (!IN6_IS_ADDR_UNSPECIFIED(&c->ip6.dns_fwd) &&
- IN6_ARE_ADDR_EQUAL(src, &c->ip6.dns[0]) && src_port == 53) {
- b->ip6h.daddr = c->ip6.addr_seen;
- b->ip6h.saddr = c->ip6.dns_fwd;
} else {
b->ip6h.daddr = c->ip6.addr_seen;
b->ip6h.saddr = b->s_in6.sin6_addr;
--
2.35.1
prev parent reply other threads:[~2022-11-03 6:33 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-03 6:33 [PATCH v2 0/3] Fixes and workarounds for pasta with Podman in Google Cloud Stefano Brivio
2022-11-03 6:33 ` [PATCH v2 1/3] conf: Consistency check between configured IPv4 netmask and gateway Stefano Brivio
2022-11-03 6:33 ` [PATCH v2 2/3] conf: Split the notions of read DNS addresses and offered ones Stefano Brivio
2022-11-03 7:10 ` Stefano Brivio
2022-11-03 6:33 ` Stefano Brivio [this message]
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