From 0bfcb7b71e735560077a42847f69597ec7dcc326 Mon Sep 17 00:00:00 2001 From: Florian Westphal Date: Mon, 7 Oct 2024 11:28:16 +0200 Subject: netfilter: xtables: avoid NFPROTO_UNSPEC where needed syzbot managed to call xt_cluster match via ebtables: WARNING: CPU: 0 PID: 11 at net/netfilter/xt_cluster.c:72 xt_cluster_mt+0x196/0x780 [..] ebt_do_table+0x174b/0x2a40 Module registers to NFPROTO_UNSPEC, but it assumes ipv4/ipv6 packet processing. As this is only useful to restrict locally terminating TCP/UDP traffic, register this for ipv4 and ipv6 family only. Pablo points out that this is a general issue, direct users of the set/getsockopt interface can call into targets/matches that were only intended for use with ip(6)tables. Check all UNSPEC matches and targets for similar issues: - matches and targets are fine except if they assume skb_network_header() is valid -- this is only true when called from inet layer: ip(6) stack pulls the ip/ipv6 header into linear data area. - targets that return XT_CONTINUE or other xtables verdicts must be restricted too, they are incompatbile with the ebtables traverser, e.g. EBT_CONTINUE is a completely different value than XT_CONTINUE. Most matches/targets are changed to register for NFPROTO_IPV4/IPV6, as they are provided for use by ip(6)tables. The MARK target is also used by arptables, so register for NFPROTO_ARP too. While at it, bail out if connbytes fails to enable the corresponding conntrack family. This change passes the selftests in iptables.git. Reported-by: syzbot+256c348558aa5cf611a9@syzkaller.appspotmail.com Closes: https://lore.kernel.org/netfilter-devel/66fec2e2.050a0220.9ec68.0047.GAE@google.com/ Fixes: 0269ea493734 ("netfilter: xtables: add cluster match") Signed-off-by: Florian Westphal Co-developed-by: Pablo Neira Ayuso Signed-off-by: Pablo Neira Ayuso --- net/netfilter/xt_connbytes.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'net/netfilter/xt_connbytes.c') diff --git a/net/netfilter/xt_connbytes.c b/net/netfilter/xt_connbytes.c index 93cb018c3055..2aabdcea8707 100644 --- a/net/netfilter/xt_connbytes.c +++ b/net/netfilter/xt_connbytes.c @@ -111,9 +111,11 @@ static int connbytes_mt_check(const struct xt_mtchk_param *par) return -EINVAL; ret = nf_ct_netns_get(par->net, par->family); - if (ret < 0) + if (ret < 0) { pr_info_ratelimited("cannot load conntrack support for proto=%u\n", par->family); + return ret; + } /* * This filter cannot function correctly unless connection tracking -- cgit v1.2.3-70-g09d2