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authorKevin Mitchell <kevmitch@arista.com>2022-04-30 06:40:27 +0300
committerPablo Neira Ayuso <pablo@netfilter.org>2022-05-13 19:56:28 +0300
commit4f9bd53084d18c2f9f1ec68fa56587b99a2cef00 (patch)
tree287511e3eef2de3ab09b254d707966341b92b3d3 /net/ipv4
parent3412e16418286bdc12561827cbd22f94cb8af5e1 (diff)
downloadlinux-4f9bd53084d18c2f9f1ec68fa56587b99a2cef00.tar.xz
netfilter: conntrack: skip verification of zero UDP checksum
The checksum is optional for UDP packets. However nf_reject would previously require a valid checksum to elicit a response such as ICMP_DEST_UNREACH. Add some logic to nf_reject_verify_csum to determine if a UDP packet has a zero checksum and should therefore not be verified. Signed-off-by: Kevin Mitchell <kevmitch@arista.com> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Diffstat (limited to 'net/ipv4')
-rw-r--r--net/ipv4/netfilter/nf_reject_ipv4.c10
1 files changed, 7 insertions, 3 deletions
diff --git a/net/ipv4/netfilter/nf_reject_ipv4.c b/net/ipv4/netfilter/nf_reject_ipv4.c
index 4eed5afca392..918c61fda0f3 100644
--- a/net/ipv4/netfilter/nf_reject_ipv4.c
+++ b/net/ipv4/netfilter/nf_reject_ipv4.c
@@ -80,6 +80,7 @@ struct sk_buff *nf_reject_skb_v4_unreach(struct net *net,
struct iphdr *niph;
struct icmphdr *icmph;
unsigned int len;
+ int dataoff;
__wsum csum;
u8 proto;
@@ -99,10 +100,11 @@ struct sk_buff *nf_reject_skb_v4_unreach(struct net *net,
if (pskb_trim_rcsum(oldskb, ntohs(ip_hdr(oldskb)->tot_len)))
return NULL;
+ dataoff = ip_hdrlen(oldskb);
proto = ip_hdr(oldskb)->protocol;
if (!skb_csum_unnecessary(oldskb) &&
- nf_reject_verify_csum(proto) &&
+ nf_reject_verify_csum(oldskb, dataoff, proto) &&
nf_ip_checksum(oldskb, hook, ip_hdrlen(oldskb), proto))
return NULL;
@@ -311,6 +313,7 @@ EXPORT_SYMBOL_GPL(nf_send_reset);
void nf_send_unreach(struct sk_buff *skb_in, int code, int hook)
{
struct iphdr *iph = ip_hdr(skb_in);
+ int dataoff = ip_hdrlen(skb_in);
u8 proto = iph->protocol;
if (iph->frag_off & htons(IP_OFFSET))
@@ -320,12 +323,13 @@ void nf_send_unreach(struct sk_buff *skb_in, int code, int hook)
nf_reject_fill_skb_dst(skb_in) < 0)
return;
- if (skb_csum_unnecessary(skb_in) || !nf_reject_verify_csum(proto)) {
+ if (skb_csum_unnecessary(skb_in) ||
+ !nf_reject_verify_csum(skb_in, dataoff, proto)) {
icmp_send(skb_in, ICMP_DEST_UNREACH, code, 0);
return;
}
- if (nf_ip_checksum(skb_in, hook, ip_hdrlen(skb_in), proto) == 0)
+ if (nf_ip_checksum(skb_in, hook, dataoff, proto) == 0)
icmp_send(skb_in, ICMP_DEST_UNREACH, code, 0);
}
EXPORT_SYMBOL_GPL(nf_send_unreach);