From 995cba5a0c9659e623b910429222ac2831a2ecca Mon Sep 17 00:00:00 2001 From: Kristof Provost Date: Tue, 15 Feb 2022 11:49:39 +0100 Subject: [PATCH] netinet: allow UDP tunnels to be removed udp_set_kernel_tunneling() rejects new callbacks if one is already set. Allow callbacks to be cleared. The use case for this is OpenVPN DCO, where the socket is opened by userspace and then adopted by the kernel to run the tunnel. If the DCO interface is removed but userspace does not close the socket (something the kernel cannot prevent) the installed callbacks could be called with an invalidated context. Allow new functions to be set, but only if they're NULL (i.e. allow the callback functions to be cleared). Reviewed by: tuexen MFC after: 3 weeks Sponsored by: Rubicon Communications, LLC ("Netgate") Differential Revision: https://reviews.freebsd.org/D34288 --- sys/netinet/udp_usrreq.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/sys/netinet/udp_usrreq.c b/sys/netinet/udp_usrreq.c index ad5a2df7d4aa..f216e993b4f3 100644 --- a/sys/netinet/udp_usrreq.c +++ b/sys/netinet/udp_usrreq.c @@ -1555,8 +1555,8 @@ udp_set_kernel_tunneling(struct socket *so, udp_tun_func_t f, udp_tun_icmp_t i, KASSERT(inp != NULL, ("udp_set_kernel_tunneling: inp == NULL")); INP_WLOCK(inp); up = intoudpcb(inp); - if ((up->u_tun_func != NULL) || - (up->u_icmp_func != NULL)) { + if ((f != NULL || i != NULL) && ((up->u_tun_func != NULL) || + (up->u_icmp_func != NULL))) { INP_WUNLOCK(inp); return (EBUSY); }