From b4220bf387e62f59d73308f122f5eea887a59d58 Mon Sep 17 00:00:00 2001 From: Bartlomiej Grzesik Date: Fri, 24 Sep 2021 10:25:53 +0200 Subject: [PATCH] ipsec: If no PMTU in hostcache assume it's equal to link's MTU If we fail to find to PMTU in hostcache, we assume it's equal to link's MTU. This patch prevents packets larger then link's MTU to be dropped silently if there is no PMTU in hostcache. Differential revision: https://reviews.freebsd.org/D31770 Obtained from: Semihalf Sponsored by: Stormshield --- sys/netipsec/ipsec_output.c | 22 ++++++++++++++++++---- 1 file changed, 18 insertions(+), 4 deletions(-) diff --git a/sys/netipsec/ipsec_output.c b/sys/netipsec/ipsec_output.c index 50bbd72f0589..c4e34665b8f5 100644 --- a/sys/netipsec/ipsec_output.c +++ b/sys/netipsec/ipsec_output.c @@ -352,15 +352,29 @@ ipsec4_check_pmtu(struct mbuf *m, struct secpolicy *sp, int forwarding) key_freesav(&sav); pmtu = tcp_hc_getmtu(&inc); - /* No entry in hostcache. */ - if (pmtu == 0) - return (0); + /* No entry in hostcache. Use link MTU instead. */ + if (pmtu == 0) { + switch (dst->sa.sa_family) { + case AF_INET: + pmtu = tcp_maxmtu(&inc, NULL); + break; +#ifdef INET6 + case AF_INET6: + pmtu = tcp_maxmtu6(&inc, NULL); + break; +#endif + } + if (pmtu == 0) + return (0); + + tcp_hc_updatemtu(&inc, pmtu); + } hlen = ipsec_hdrsiz_internal(sp); if (m_length(m, NULL) + hlen > pmtu) { /* * If we're forwarding generate ICMP message here, - * so that it contains pmtu and not link mtu. + * so that it contains pmtu substraced by header size. * Set error to EINPROGRESS, in order for the frame * to be dropped silently. */