[PATCH AUTOSEL 5.1 183/219] netfilter: Fix remainder of pseudo-header protocol 0

Sasha Levin
2019-07-15T14:15:04Z

From: He Zhe <zhe.he@windriver.com>

[ Upstream commit 5d1549847c76b1ffcf8e388ef4d0f229bdd1d7e8 ]

Since v5.1-rc1, some types of packets do not get unreachable reply with the
following iptables setting. Fox example,

$ iptables -A INPUT -p icmp --icmp-type 8 -j REJECT
$ ping 127.0.0.1 -c 1
PING 127.0.0.1 (127.0.0.1) 56(84) bytes of data.
— 127.0.0.1 ping statistics —
1 packets transmitted, 0 received, 100% packet loss, time 0ms

We should have got the following reply from command line, but we did not.
From 127.0.0.1 icmp_seq=1 Destination Port Unreachable

Yi Zhao reported it and narrowed it down to:
7fc38225363d ("netfilter: reject: skip csum verification for protocols that don't support it"),

This is because nf_ip_checksum still expects pseudo-header protocol type 0 for
packets that are of neither TCP or UDP, and thus ICMP packets are mistakenly
treated as TCP/UDP.

This patch corrects the conditions in nf_ip_checksum and all other places that
still call it with protocol 0.

Fixes: 7fc38225363d ("netfilter: reject: skip csum verification for protocols that don't support it")
Reported-by: Yi Zhao <yi.zhao@windriver.com>
Signed-off-by: He Zhe <zhe.he@windriver.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/netfilter/nf_conntrack_proto_icmp.c | 2 +-
net/netfilter/nf_nat_proto.c | 2 +-
net/netfilter/utils.c | 5 +++--
3 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/net/netfilter/nf_conntrack_proto_icmp.c b/net/netfilter/nf_conntrack_proto_icmp.c
index 9becac953587..71a84a0517f3 100644
--- a/net/netfilter/nf_conntrack_proto_icmp.c
+++ b/net/netfilter/nf_conntrack_proto_icmp.c
@@ -221,7 +221,7 @@ int nf_conntrack_icmpv4_error(struct nf_conn *tmpl,
/* See ip_conntrack_proto_tcp.c */
if (state->net->ct.sysctl_checksum &&
state->hook == NF_INET_PRE_ROUTING &&
- nf_ip_checksum(skb, state->hook, dataoff, 0)) {
+ nf_ip_checksum(skb, state->hook, dataoff, IPPROTO_ICMP)) {
icmp_error_log(skb, state, "bad hw icmp checksum");
return -NF_ACCEPT;
}
diff --git a/net/netfilter/nf_nat_proto.c b/net/netfilter/nf_nat_proto.c
index 62743da3004f..0b0efbb953bf 100644
--- a/net/netfilter/nf_nat_proto.c
+++ b/net/netfilter/nf_nat_proto.c
@@ -567,7 +567,7 @@ int nf_nat_icmp_reply_translation(struct sk_buff *skb,

if (!skb_make_writable(skb, hdrlen + sizeof(*inside)))
return 0;
- if (nf_ip_checksum(skb, hooknum, hdrlen, 0))
+ if (nf_ip_checksum(skb, hooknum, hdrlen, IPPROTO_ICMP))
return 0;

inside = (void *)skb->data + hdrlen;
diff --git a/net/netfilter/utils.c b/net/netfilter/utils.c
index 06dc55590441..51b454d8fa9c 100644
--- a/net/netfilter/utils.c
+++ b/net/netfilter/utils.c
@@ -17,7 +17,8 @@ __sum16 nf_ip_checksum(struct sk_buff *skb, unsigned int hook,
case CHECKSUM_COMPLETE:
if (hook != NF_INET_PRE_ROUTING && hook != NF_INET_LOCAL_IN)
break;
- if ((protocol == 0 && !csum_fold(skb->csum)) ||
+ if ((protocol != IPPROTO_TCP && protocol != IPPROTO_UDP &&
+ !csum_fold(skb->csum)) ||
!csum_tcpudp_magic(iph->saddr, iph->daddr,
skb->len - dataoff, protocol,
skb->csum)) {
@@ -26,7 +27,7 @@ __sum16 nf_ip_checksum(struct sk_buff *skb, unsigned int hook,
}
/* fall through */
case CHECKSUM_NONE:
- if (protocol == 0)
+ if (protocol != IPPROTO_TCP && protocol != IPPROTO_UDP)
skb->csum = 0;
else
skb->csum = csum_tcpudp_nofold(iph->saddr, iph->daddr,
--
2.20.1