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tcp, udp: Don't initialise IPv6/IPv4 sockets if IPv4/IPv6 are not enabled

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If we disable a given IP version automatically (no corresponding
default route on host) or administratively (--ipv4-only or
--ipv6-only options), we don't initialise related buffers and
services (DHCP for IPv4, NDP and DHCPv6 for IPv6). The "tap"
handlers will also ignore packets with a disabled IP version.

However, in commit 3c6ae62510 ("conf, tcp, udp: Allow address
specification for forwarded ports") I happily changed socket
initialisation functions to take AF_UNSPEC meaning "any enabled
IP version", but I forgot to add checks back for the "enabled"
part.

Reported by Paul: on a host without default IPv6 route, but IPv6
enabled, connect, using IPv6, to a port handled by pasta, which
tries to send data to a tap device without initialised buffers
for that IP version and exits because the resulting write() fails.

Simpler way to reproduce: pasta -6 and inbound IPv4 connection, or
pasta -4 and inbound IPv6 connection.

Reported-by: Paul Holzinger <pholzing@redhat.com>
Fixes: 3c6ae62510 ("conf, tcp, udp: Allow address specification for forwarded ports")
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
This commit is contained in:
Stefano Brivio 2022-11-09 18:21:44 +01:00
parent 6533a4a07b
commit 817eedc28a
2 changed files with 4 additions and 4 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

4
tcp.c
View file

@ -3213,9 +3213,9 @@ static void tcp_sock_init6(const struct ctx *c, int ns,
void tcp_sock_init(const struct ctx *c, int ns, sa_family_t af, void tcp_sock_init(const struct ctx *c, int ns, sa_family_t af,
const void *addr, const char *ifname, in_port_t port) const void *addr, const char *ifname, in_port_t port)
{ {
if (af == AF_INET || af == AF_UNSPEC) if ((af == AF_INET || af == AF_UNSPEC) && c->ifi4)
tcp_sock_init4(c, ns, addr, ifname, port); tcp_sock_init4(c, ns, addr, ifname, port);
if (af == AF_INET6 || af == AF_UNSPEC) if ((af == AF_INET6 || af == AF_UNSPEC) && c->ifi6)
tcp_sock_init6(c, ns, addr, ifname, port); tcp_sock_init6(c, ns, addr, ifname, port);
} }

4
udp.c
View file

@ -1129,7 +1129,7 @@ void udp_sock_init(const struct ctx *c, int ns, sa_family_t af,
c->udp.fwd_in.f.delta[port]); c->udp.fwd_in.f.delta[port]);
} }
if (af == AF_INET || af == AF_UNSPEC) { if ((af == AF_INET || af == AF_UNSPEC) && c->ifi4) {
if (!addr && c->mode == MODE_PASTA) if (!addr && c->mode == MODE_PASTA)
bind_addr = &c->ip4.addr; bind_addr = &c->ip4.addr;
else else
@ -1162,7 +1162,7 @@ void udp_sock_init(const struct ctx *c, int ns, sa_family_t af,
} }
} }
if (af == AF_INET6 || af == AF_UNSPEC) { if ((af == AF_INET6 || af == AF_UNSPEC) && c->ifi6) {
if (!addr && c->mode == MODE_PASTA) if (!addr && c->mode == MODE_PASTA)
bind_addr = &c->ip6.addr; bind_addr = &c->ip6.addr;
else else