Currently, outbound forwards (-T, -U) are handled by sockets bound to the
loopback address. Typically we create two sockets, one for 127.0.0.1 and
one for ::1.
This has some disadvantages:
* The guest can't connect to these services using its global IP address,
it must explicitly use 127.0.0.1 or ::1 (bug 100)
* The guest can't even connect via 127.0.0.0/8 addresses other than
127.0.0.1
* We can't use dual-stack sockets, we have to have separate sockets for
IPv4 and IPv6.
The restriction exist for a reason though. If the guest has any interfaces
other than pasta (e.g. a VPN tunnel) external hosts could reach the host
via the forwards. Especially combined with -T auto / -U auto this would
make it very easy to make a mistake with nasty security implications.
We can achieve both goals, however, if we don't bind the outbound listening
sockets to a particular address, but _do_ use SO_BINDTODEVICE to restrict
them to the "lo" interface.
Link: https://bugs.passt.top/show_bug.cgi?id=100
Signed-off-by: David Gibson
---
pif.c | 6 ------
tcp.c | 18 ++----------------
udp.c | 27 ++++++++++-----------------
3 files changed, 12 insertions(+), 39 deletions(-)
diff --git a/pif.c b/pif.c
index 592fafaa..84e3ceae 100644
--- a/pif.c
+++ b/pif.c
@@ -87,12 +87,6 @@ int pif_sock_l4(const struct ctx *c, enum epoll_type type, uint8_t pif,
ASSERT(pif_is_socket(pif));
- if (pif == PIF_SPLICE) {
- /* Sanity checks */
- ASSERT(!ifname);
- ASSERT(addr && inany_is_loopback(addr));
- }
-
if (!addr)
return sock_l4_sa(c, type, &sa, sizeof(sa.sa6),
ifname, false, data);
diff --git a/tcp.c b/tcp.c
index a62c8df1..c3500f5e 100644
--- a/tcp.c
+++ b/tcp.c
@@ -2596,20 +2596,6 @@ int tcp_sock_init(const struct ctx *c, uint8_t pif,
return r4 < 0 ? r4 : r6;
}
-/**
- * tcp_ns_sock_init() - Init socket to listen for spliced outbound connections
- * @c: Execution context
- * @port: Port, host order
- */
-static void tcp_ns_sock_init(const struct ctx *c, in_port_t port)
-{
- ASSERT(!c->no_tcp);
-
- if (c->ifi4)
- tcp_sock_init_one(c, PIF_SPLICE, &inany_loopback4, NULL, port);
- if (c->ifi6)
- tcp_sock_init_one(c, PIF_SPLICE, &inany_loopback6, NULL, port);
-}
/**
* tcp_ns_socks_init() - Bind sockets in namespace for outbound connections
@@ -2629,7 +2615,7 @@ static int tcp_ns_socks_init(void *arg)
if (!bitmap_isset(c->tcp.fwd_out.map, port))
continue;
- tcp_ns_sock_init(c, port);
+ tcp_sock_init(c, PIF_SPLICE, NULL, "lo", port);
}
return 0;
@@ -2809,7 +2795,7 @@ static void tcp_port_rebind(struct ctx *c, bool outbound)
if ((c->ifi4 && socks[port][V4] == -1) ||
(c->ifi6 && socks[port][V6] == -1)) {
if (outbound)
- tcp_ns_sock_init(c, port);
+ tcp_sock_init(c, PIF_SPLICE, NULL, "lo", port);
else
tcp_sock_init(c, PIF_HOST, NULL, NULL, port);
}
diff --git a/udp.c b/udp.c
index 7f5faf20..1984bb80 100644
--- a/udp.c
+++ b/udp.c
@@ -1132,26 +1132,16 @@ int udp_sock_init(const struct ctx *c, uint8_t pif,
}
if ((!addr || inany_v4(addr)) && c->ifi4) {
- const union inany_addr *a = addr ?
- addr : &inany_any4;
-
- if (pif == PIF_SPLICE)
- a = &inany_loopback4;
-
- r4 = pif_sock_l4(c, EPOLL_TYPE_UDP_LISTEN, pif, a, ifname,
+ r4 = pif_sock_l4(c, EPOLL_TYPE_UDP_LISTEN, pif,
+ addr ? addr : &inany_any4, ifname,
port, uref.u32);
socks[V4][port] = r4 < 0 ? -1 : r4;
}
if ((!addr || !inany_v4(addr)) && c->ifi6) {
- const union inany_addr *a = addr ?
- addr : &inany_any6;
-
- if (pif == PIF_SPLICE)
- a = &inany_loopback6;
-
- r6 = pif_sock_l4(c, EPOLL_TYPE_UDP_LISTEN, pif, a, ifname,
+ r6 = pif_sock_l4(c, EPOLL_TYPE_UDP_LISTEN, pif,
+ addr ? addr : &inany_any6, ifname,
port, uref.u32);
socks[V6][port] = r6 < 0 ? -1 : r6;
@@ -1219,9 +1209,12 @@ static void udp_port_rebind(struct ctx *c, bool outbound)
continue;
if ((c->ifi4 && socks[V4][port] == -1) ||
- (c->ifi6 && socks[V6][port] == -1))
- udp_sock_init(c, outbound ? PIF_SPLICE : PIF_HOST,
- NULL, NULL, port);
+ (c->ifi6 && socks[V6][port] == -1)) {
+ if (outbound)
+ udp_sock_init(c, PIF_SPLICE, NULL, "lo", port);
+ else
+ udp_sock_init(c, PIF_HOST, NULL, NULL, port);
+ }
}
}
--
2.51.0