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netfilter: nf_reject_ipv4: don't send tcp RST if the packet is non-TCP 

In iptables, if the user add a rule to send tcp RST and specify the
non-TCP protocol, such as UDP, kernel will reject this request. But
in nftables, this validity check only occurs in nft tool, i.e. only
in userspace.

This means that user can add such a rule like follows via nfnetlink:
  "nft add rule filter forward ip protocol udp reject with tcp reset"

This will generate some confusing tcp RST packets. So we should send
tcp RST only when it is TCP packet.

Signed-off-by: Liping Zhang <liping.zhang@spreadtrum.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This commit is contained in:
Liping Zhang 2016-06-20 21:26:28 +08:00 committed by Pablo Neira Ayuso
parent 9847371a84
commit e1dbbc5907
1 changed files with 3 additions and 0 deletions
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3
net/ipv4/netfilter/nf_reject_ipv4.c
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@ -24,6 +24,9 @@ const struct tcphdr *nf_reject_ip_tcphdr_get(struct sk_buff *oldskb,
if (ip_hdr(oldskb)->frag_off & htons(IP_OFFSET))
return NULL;
if (ip_hdr(oldskb)->protocol != IPPROTO_TCP)
return NULL;
oth = skb_header_pointer(oldskb, ip_hdrlen(oldskb),
sizeof(struct tcphdr), _oth);
if (oth == NULL)