From 8aab74c0b93952ba58fef140fc897d5dc83b9bc1 Mon Sep 17 00:00:00 2001 From: Michael Pfeiffer Date: Fri, 13 Nov 2020 15:03:32 +0100 Subject: [PATCH] net/tap: allow all-zero checksum for UDP over IPv4 Unlike TCP, UDP checksums are optional and may be zero to indicate "not set" [RFC 768] (except for IPv6, where this prohibited [RFC 8200]). Add this special case to the checksum offload emulation in net/tap. Signed-off-by: Michael Pfeiffer Reviewed-by: Ferruh Yigit --- drivers/net/tap/rte_eth_tap.c | 18 ++++++++++++++++-- 1 file changed, 16 insertions(+), 2 deletions(-) diff --git a/drivers/net/tap/rte_eth_tap.c b/drivers/net/tap/rte_eth_tap.c index 2f8abb12c5..2542de3065 100644 --- a/drivers/net/tap/rte_eth_tap.c +++ b/drivers/net/tap/rte_eth_tap.c @@ -303,6 +303,7 @@ tap_verify_csum(struct rte_mbuf *mbuf) uint16_t cksum = 0; void *l3_hdr; void *l4_hdr; + struct rte_udp_hdr *udp_hdr; if (l2 == RTE_PTYPE_L2_ETHER_VLAN) l2_len += 4; @@ -349,10 +350,23 @@ tap_verify_csum(struct rte_mbuf *mbuf) /* Don't verify checksum for multi-segment packets. */ if (mbuf->nb_segs > 1) return; - if (l3 == RTE_PTYPE_L3_IPV4) + if (l3 == RTE_PTYPE_L3_IPV4) { + if (l4 == RTE_PTYPE_L4_UDP) { + udp_hdr = (struct rte_udp_hdr *)l4_hdr; + if (udp_hdr->dgram_cksum == 0) { + /* + * For IPv4, a zero UDP checksum + * indicates that the sender did not + * generate one [RFC 768]. + */ + mbuf->ol_flags |= PKT_RX_L4_CKSUM_NONE; + return; + } + } cksum = ~rte_ipv4_udptcp_cksum(l3_hdr, l4_hdr); - else if (l3 == RTE_PTYPE_L3_IPV6) + } else if (l3 == RTE_PTYPE_L3_IPV6) { cksum = ~rte_ipv6_udptcp_cksum(l3_hdr, l4_hdr); + } mbuf->ol_flags |= cksum ? PKT_RX_L4_CKSUM_BAD : PKT_RX_L4_CKSUM_GOOD;