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_connmark.c | 28 +++++++++++++++++++++++++--- 1 file changed, 25 insertions(+), 3 deletions(-) (limited to 'net/netfilter/xt_connmark.c') diff --git a/net/netfilter/xt_connmark.c b/net/netfilter/xt_connmark.c index ad3c033db64e..4277084de2e7 100644 --- a/net/netfilter/xt_connmark.c +++ b/net/netfilter/xt_connmark.c @@ -151,7 +151,7 @@ static struct xt_target connmark_tg_reg[] __read_mostly = { { .name = "CONNMARK", .revision = 1, - .family = NFPROTO_UNSPEC, + .family = NFPROTO_IPV4, .checkentry = connmark_tg_check, .target = connmark_tg, .targetsize = sizeof(struct xt_connmark_tginfo1), @@ -161,13 +161,35 @@ static struct xt_target connmark_tg_reg[] __read_mostly = { { .name = "CONNMARK", .revision = 2, - .family = NFPROTO_UNSPEC, + .family = NFPROTO_IPV4, .checkentry = connmark_tg_check, .target = connmark_tg_v2, .targetsize = sizeof(struct xt_connmark_tginfo2), .destroy = connmark_tg_destroy, .me = THIS_MODULE, - } + }, +#if IS_ENABLED(CONFIG_IP6_NF_IPTABLES) + { + .name = "CONNMARK", + .revision = 1, + .family = NFPROTO_IPV6, + .checkentry = connmark_tg_check, + .target = connmark_tg, + .targetsize = sizeof(struct xt_connmark_tginfo1), + .destroy = connmark_tg_destroy, + .me = THIS_MODULE, + }, + { + .name = "CONNMARK", + .revision = 2, + .family = NFPROTO_IPV6, + .checkentry = connmark_tg_check, + .target = connmark_tg_v2, + .targetsize = sizeof(struct xt_connmark_tginfo2), + .destroy = connmark_tg_destroy, + .me = THIS_MODULE, + }, +#endif }; static struct xt_match connmark_mt_reg __read_mostly = { -- cgit v1.2.3