diff options
| author | Kevin Mitchell <kevmitch@arista.com> | 2022-04-29 20:40:27 -0700 |
|---|---|---|
| committer | Pablo Neira Ayuso <pablo@netfilter.org> | 2022-05-13 18:56:28 +0200 |
| commit | 4f9bd53084d18c2f9f1ec68fa56587b99a2cef00 (patch) | |
| tree | 287511e3eef2de3ab09b254d707966341b92b3d3 /include/net/netfilter | |
| parent | 3412e16418286bdc12561827cbd22f94cb8af5e1 (diff) | |
| download | lwn-4f9bd53084d18c2f9f1ec68fa56587b99a2cef00.tar.gz lwn-4f9bd53084d18c2f9f1ec68fa56587b99a2cef00.zip | |
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 'include/net/netfilter')
| -rw-r--r-- | include/net/netfilter/nf_reject.h | 21 |
1 files changed, 17 insertions, 4 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; |