From: Pablo Neira Ayuso <pablo@netfilter.org>
To: netfilter-devel@vger.kernel.org
Cc: davem@davemloft.net, netdev@vger.kernel.org, kuba@kernel.org
Subject: [PATCH net-next 17/17] netfilter: conntrack: skip verification of zero UDP checksum
Date: Tue, 10 May 2022 14:21:50 +0200 [thread overview]
Message-ID: <20220510122150.92533-18-pablo@netfilter.org> (raw)
In-Reply-To: <20220510122150.92533-1-pablo@netfilter.org>
From: Kevin Mitchell <kevmitch@arista.com>
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>
---
include/net/netfilter/nf_reject.h | 21 +++++++++++++++++----
net/ipv4/netfilter/nf_reject_ipv4.c | 10 +++++++---
net/ipv6/netfilter/nf_reject_ipv6.c | 4 ++--
3 files changed, 26 insertions(+), 9 deletions(-)
diff --git a/include/net/netfilter/nf_reject.h b/include/net/netfilter/nf_reject.h
index 9051c3a0c8e7..7c669792fb9c 100644
--- a/include/net/netfilter/nf_reject.h
+++ b/include/net/netfilter/nf_reject.h
@@ -5,12 +5,28 @@
#include <linux/types.h>
#include <uapi/linux/in.h>
-static inline bool nf_reject_verify_csum(__u8 proto)
+static inline bool nf_reject_verify_csum(struct sk_buff *skb, int dataoff,
+ __u8 proto)
{
/* Skip protocols that don't use 16-bit one's complement checksum
* of the entire payload.
*/
switch (proto) {
+ /* Protocols with optional checksums. */
+ case IPPROTO_UDP: {
+ const struct udphdr *udp_hdr;
+ struct udphdr _udp_hdr;
+
+ udp_hdr = skb_header_pointer(skb, dataoff,
+ sizeof(_udp_hdr),
+ &_udp_hdr);
+ if (!udp_hdr || udp_hdr->check)
+ return true;
+
+ return false;
+ }
+ case IPPROTO_GRE:
+
/* Protocols with other integrity checks. */
case IPPROTO_AH:
case IPPROTO_ESP:
@@ -19,9 +35,6 @@ static inline bool nf_reject_verify_csum(__u8 proto)
/* Protocols with partial checksums. */
case IPPROTO_UDPLITE:
case IPPROTO_DCCP:
-
- /* Protocols with optional checksums. */
- case IPPROTO_GRE:
return false;
}
return true;
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);
diff --git a/net/ipv6/netfilter/nf_reject_ipv6.c b/net/ipv6/netfilter/nf_reject_ipv6.c
index dffeaaaadcde..f61d4f18e1cf 100644
--- a/net/ipv6/netfilter/nf_reject_ipv6.c
+++ b/net/ipv6/netfilter/nf_reject_ipv6.c
@@ -31,7 +31,7 @@ static bool nf_reject_v6_csum_ok(struct sk_buff *skb, int hook)
if (thoff < 0 || thoff >= skb->len || (fo & htons(~0x7)) != 0)
return false;
- if (!nf_reject_verify_csum(proto))
+ if (!nf_reject_verify_csum(skb, thoff, proto))
return true;
return nf_ip6_checksum(skb, hook, thoff, proto) == 0;
@@ -388,7 +388,7 @@ static bool reject6_csum_ok(struct sk_buff *skb, int hook)
if (thoff < 0 || thoff >= skb->len || (fo & htons(~0x7)) != 0)
return false;
- if (!nf_reject_verify_csum(proto))
+ if (!nf_reject_verify_csum(skb, thoff, proto))
return true;
return nf_ip6_checksum(skb, hook, thoff, proto) == 0;
--
2.30.2
next prev parent reply other threads:[~2022-05-10 12:24 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-10 12:21 [PATCH net-next 00/17] Netfilter updates for net-next Pablo Neira Ayuso
2022-05-10 12:21 ` [PATCH net-next 01/17] netfilter: ecache: use dedicated list for event redelivery Pablo Neira Ayuso
2022-05-11 2:20 ` Jakub Kicinski
2022-05-11 5:46 ` Florian Westphal
2022-05-11 7:26 ` Pablo Neira Ayuso
2022-05-10 12:21 ` [PATCH net-next 02/17] netfilter: conntrack: include ecache dying list in dumps Pablo Neira Ayuso
2022-05-10 12:21 ` [PATCH net-next 03/17] netfilter: conntrack: remove the percpu dying list Pablo Neira Ayuso
2022-05-10 12:21 ` [PATCH net-next 04/17] netfilter: cttimeout: decouple unlink and free on netns destruction Pablo Neira Ayuso
2022-05-10 12:21 ` [PATCH net-next 05/17] netfilter: remove nf_ct_unconfirmed_destroy helper Pablo Neira Ayuso
2022-05-10 12:21 ` [PATCH net-next 06/17] netfilter: extensions: introduce extension genid count Pablo Neira Ayuso
2022-05-10 12:21 ` [PATCH net-next 07/17] netfilter: cttimeout: decouple unlink and free on netns destruction Pablo Neira Ayuso
2022-05-10 12:21 ` [PATCH net-next 08/17] netfilter: conntrack: remove __nf_ct_unconfirmed_destroy Pablo Neira Ayuso
2022-05-10 12:21 ` [PATCH net-next 09/17] netfilter: conntrack: remove unconfirmed list Pablo Neira Ayuso
2022-05-10 12:21 ` [PATCH net-next 10/17] netfilter: conntrack: avoid unconditional local_bh_disable Pablo Neira Ayuso
2022-05-10 12:21 ` [PATCH net-next 11/17] netfilter: conntrack: add nf_ct_iter_data object for nf_ct_iterate_cleanup*() Pablo Neira Ayuso
2022-05-10 12:21 ` [PATCH net-next 12/17] netfilter: nfnetlink: allow to detect if ctnetlink listeners exist Pablo Neira Ayuso
2022-05-10 12:21 ` [PATCH net-next 13/17] netfilter: conntrack: un-inline nf_ct_ecache_ext_add Pablo Neira Ayuso
2022-05-10 12:21 ` [PATCH net-next 14/17] netfilter: conntrack: add nf_conntrack_events autodetect mode Pablo Neira Ayuso
2022-05-10 12:21 ` [PATCH net-next 15/17] netfilter: prefer extension check to pointer check Pablo Neira Ayuso
2022-05-10 12:21 ` [PATCH net-next 16/17] netfilter: flowtable: nft_flow_route use more data for reverse route Pablo Neira Ayuso
2022-05-10 12:21 ` Pablo Neira Ayuso [this message]
2022-05-13 21:43 [PATCH net-next 00/17] Netfilter updates for net-next Pablo Neira Ayuso
2022-05-13 21:43 ` [PATCH net-next 17/17] netfilter: conntrack: skip verification of zero UDP checksum Pablo Neira Ayuso
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