From 76afcbb52492f9b3e72ee7d4c4ed0a54c25e1c48 Mon Sep 17 00:00:00 2001 From: Kristof Provost Date: Thu, 13 Jul 2023 10:25:49 +0200 Subject: [PATCH] pf: handle multiple IPv6 fragment headers With 'scrub fragment reassemble' if a packet contains multiple IPv6 fragment headers we would reassemble the packet and immediately continue processing it. That is, we'd remove the first fragment header and expect the next header to be a final header (i.e. TCP, UDP, ICMPv6, ...). However, if it's another fragment header we'd not treat the packet correctly. That is, we'd fail to recognise the payload and treat it as if it were an IPv6 fragment rather than as its actual payload. Fix this by restarting the normalisation on the reassembled packet. If there are multiple fragment headers drop the packet. Reported by: Enrico Bassetti bassetti@di.uniroma1.it (NetSecurityLab @ Sapienza University of Rome) MFC after: instant Sponsored by: Rubicon Communications, LLC ("Netgate") --- sys/netpfil/pf/pf_norm.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/sys/netpfil/pf/pf_norm.c b/sys/netpfil/pf/pf_norm.c index 6dda410d832..d3fb5dcc00a 100644 --- a/sys/netpfil/pf/pf_norm.c +++ b/sys/netpfil/pf/pf_norm.c @@ -1254,6 +1254,8 @@ pf_normalize_ip6(struct mbuf **m0, struct pfi_kkif *kif, if (sizeof(struct ip6_hdr) + IPV6_MAXPACKET < m->m_pkthdr.len) goto drop; +again: + h = mtod(m, struct ip6_hdr *); plen = ntohs(h->ip6_plen); /* jumbo payload option not supported */ if (plen == 0) @@ -1322,6 +1324,8 @@ pf_normalize_ip6(struct mbuf **m0, struct pfi_kkif *kif, return (PF_PASS); fragment: + if (pd->flags & PFDESC_IP_REAS) + return (PF_DROP); if (sizeof(struct ip6_hdr) + plen > m->m_pkthdr.len) goto shortpkt; @@ -1339,7 +1343,7 @@ pf_normalize_ip6(struct mbuf **m0, struct pfi_kkif *kif, return (PF_DROP); pd->flags |= PFDESC_IP_REAS; - return (PF_PASS); + goto again; shortpkt: REASON_SET(reason, PFRES_SHORT);