From ee586bbc28fb7128133457cf711880d13a3b7ce4 Mon Sep 17 00:00:00 2001 From: Florian Westphal Date: Mon, 16 Feb 2015 18:54:04 +0100 Subject: netfilter: reject: don't send icmp error if csum is invalid tcp resets are never emitted if the packet that triggers the reject/reset has an invalid checksum. For icmp error responses there was no such check. It allows to distinguish icmp response generated via iptables -I INPUT -p udp --dport 42 -j REJECT and those emitted by network stack (won't respond if csum is invalid, REJECT does). Arguably its possible to avoid this by using conntrack and only using REJECT with -m conntrack NEW/RELATED. However, this doesn't work when connection tracking is not in use or when using nf_conntrack_checksum=0. Furthermore, sending errors in response to invalid csums doesn't make much sense so just add similar test as in nf_send_reset. Validate csum if needed and only send the response if it is ok. Reference: http://bugzilla.redhat.com/show_bug.cgi?id=1169829 Signed-off-by: Florian Westphal Signed-off-by: Pablo Neira Ayuso --- net/netfilter/nft_reject_inet.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) (limited to 'net/netfilter/nft_reject_inet.c') diff --git a/net/netfilter/nft_reject_inet.c b/net/netfilter/nft_reject_inet.c index 7b5f9d58680a..92877114aff4 100644 --- a/net/netfilter/nft_reject_inet.c +++ b/net/netfilter/nft_reject_inet.c @@ -28,14 +28,16 @@ static void nft_reject_inet_eval(const struct nft_expr *expr, case NFPROTO_IPV4: switch (priv->type) { case NFT_REJECT_ICMP_UNREACH: - nf_send_unreach(pkt->skb, priv->icmp_code); + nf_send_unreach(pkt->skb, priv->icmp_code, + pkt->ops->hooknum); break; case NFT_REJECT_TCP_RST: nf_send_reset(pkt->skb, pkt->ops->hooknum); break; case NFT_REJECT_ICMPX_UNREACH: nf_send_unreach(pkt->skb, - nft_reject_icmp_code(priv->icmp_code)); + nft_reject_icmp_code(priv->icmp_code), + pkt->ops->hooknum); break; } break; -- cgit v1.2.3