From 18c38eda39bb8162ddce9acc4de4d6e4bbf48ef0 Mon Sep 17 00:00:00 2001 From: Kristof Provost Date: Mon, 13 May 2024 12:06:47 +0200 Subject: [PATCH] if_ovpn: cope with loops User misconfiguration may lead to routing loops where we try to send the tunnel packet into the tunnel. This eventually leads to stack overflows and panics. Avoid this using if_tunnel_check_nesting(), which will drop the packet if we're looping or we hit three layers of nested tunnels. MFC after: 1 week Sponsored by: Rubicon Communications, LLC ("Netgate") (cherry picked from commit 59a6666ec91d71f97aaae5195bbfafd9d422db2e) --- sys/net/if_ovpn.c | 9 +++++++++ tests/sys/net/if_ovpn/if_ovpn.sh | 8 ++++++++ 2 files changed, 17 insertions(+) diff --git a/sys/net/if_ovpn.c b/sys/net/if_ovpn.c index 1b5d419fe58..7af669c6951 100644 --- a/sys/net/if_ovpn.c +++ b/sys/net/if_ovpn.c @@ -255,6 +255,7 @@ static const char ovpnname[] = "ovpn"; static const char ovpngroupname[] = "openvpn"; static MALLOC_DEFINE(M_OVPN, ovpnname, "OpenVPN DCO Interface"); +#define MTAG_OVPN_LOOP 0x6f76706e /* ovpn */ SYSCTL_DECL(_net_link); static SYSCTL_NODE(_net_link, IFT_OTHER, openvpn, CTLFLAG_RW | CTLFLAG_MPSAFE, 0, @@ -1858,6 +1859,14 @@ ovpn_transmit_to_peer(struct ifnet *ifp, struct mbuf *m, if (af != 0) BPF_MTAP2(ifp, &af, sizeof(af), m); + if (__predict_false(if_tunnel_check_nesting(ifp, m, MTAG_OVPN_LOOP, 3))) { + if (_ovpn_lock_trackerp != NULL) + OVPN_RUNLOCK(sc); + OVPN_COUNTER_ADD(sc, lost_data_pkts_out, 1); + m_freem(m); + return (ELOOP); + } + len = m->m_pkthdr.len; MPASS(len <= ifp->if_mtu); diff --git a/tests/sys/net/if_ovpn/if_ovpn.sh b/tests/sys/net/if_ovpn/if_ovpn.sh index bbaffa0bce7..88df430aead 100644 --- a/tests/sys/net/if_ovpn/if_ovpn.sh +++ b/tests/sys/net/if_ovpn/if_ovpn.sh @@ -95,6 +95,10 @@ atf_test_case "4in4" "cleanup" echo 'foo' | jexec b nc -u -w 2 192.0.2.1 1194 atf_check -s exit:0 -o ignore jexec b ping -c 3 198.51.100.1 + + # Test routing loop protection + jexec b route add 192.0.2.1 198.51.100.1 + atf_check -s exit:2 -o ignore jexec b ping -t 1 -c 1 198.51.100.1 } 4in4_cleanup() @@ -386,6 +390,10 @@ atf_test_case "6in6" "cleanup" atf_check -s exit:0 -o ignore jexec b ping6 -c 3 2001:db8:1::1 atf_check -s exit:0 -o ignore jexec b ping6 -c 3 -z 16 2001:db8:1::1 + + # Test routing loop protection + jexec b route add -6 2001:db8::1 2001:db8:1::1 + atf_check -s exit:2 -o ignore jexec b ping6 -t 1 -c 3 2001:db8:1::1 } 6in6_cleanup()