From 79cff40588effab037c463c7c1661baea5764c36 Mon Sep 17 00:00:00 2001 From: Olivier Matz Date: Tue, 27 Apr 2021 09:59:38 +0200 Subject: [PATCH] net: introduce functions to verify L4 checksums Since commit d5df2ae0428a ("net: fix unneeded replacement of TCP checksum 0"), the functions rte_ipv4_udptcp_cksum() and rte_ipv6_udptcp_cksum() can return either 0x0000 or 0xffff when used to verify a packet containing a valid checksum. Since these functions should be used to calculate the checksum to set in a packet, introduce 2 new helpers for checksum verification. They return 0 if the checksum is valid in the packet. Use this new helper in net/tap driver. Signed-off-by: Olivier Matz --- drivers/net/tap/rte_eth_tap.c | 5 +- lib/net/rte_ip.h | 116 +++++++++++++++++++++++++++------- 2 files changed, 96 insertions(+), 25 deletions(-) diff --git a/drivers/net/tap/rte_eth_tap.c b/drivers/net/tap/rte_eth_tap.c index 71282e8065..843dbc5a1f 100644 --- a/drivers/net/tap/rte_eth_tap.c +++ b/drivers/net/tap/rte_eth_tap.c @@ -365,11 +365,10 @@ tap_verify_csum(struct rte_mbuf *mbuf) return; } } - cksum = rte_ipv4_udptcp_cksum(l3_hdr, l4_hdr); + cksum_ok = !rte_ipv4_udptcp_cksum_verify(l3_hdr, l4_hdr); } else { /* l3 == RTE_PTYPE_L3_IPV6, checked above */ - cksum = rte_ipv6_udptcp_cksum(l3_hdr, l4_hdr); + cksum_ok = !rte_ipv6_udptcp_cksum_verify(l3_hdr, l4_hdr); } - cksum_ok = (cksum == 0) || (cksum == 0xffff); mbuf->ol_flags |= cksum_ok ? PKT_RX_L4_CKSUM_GOOD : PKT_RX_L4_CKSUM_BAD; } diff --git a/lib/net/rte_ip.h b/lib/net/rte_ip.h index 8c189009b0..7a18f2c7fb 100644 --- a/lib/net/rte_ip.h +++ b/lib/net/rte_ip.h @@ -344,20 +344,10 @@ rte_ipv4_phdr_cksum(const struct rte_ipv4_hdr *ipv4_hdr, uint64_t ol_flags) } /** - * Process the IPv4 UDP or TCP checksum. - * - * The IP and layer 4 checksum must be set to 0 in the packet by - * the caller. - * - * @param ipv4_hdr - * The pointer to the contiguous IPv4 header. - * @param l4_hdr - * The pointer to the beginning of the L4 header. - * @return - * The complemented checksum to set in the IP packet. + * @internal Calculate the non-complemented IPv4 L4 checksum */ static inline uint16_t -rte_ipv4_udptcp_cksum(const struct rte_ipv4_hdr *ipv4_hdr, const void *l4_hdr) +__rte_ipv4_udptcp_cksum(const struct rte_ipv4_hdr *ipv4_hdr, const void *l4_hdr) { uint32_t cksum; uint32_t l3_len, l4_len; @@ -374,9 +364,32 @@ rte_ipv4_udptcp_cksum(const struct rte_ipv4_hdr *ipv4_hdr, const void *l4_hdr) cksum += rte_ipv4_phdr_cksum(ipv4_hdr, 0); cksum = ((cksum & 0xffff0000) >> 16) + (cksum & 0xffff); - cksum = (~cksum) & 0xffff; + + return cksum; +} + +/** + * Process the IPv4 UDP or TCP checksum. + * + * The IP and layer 4 checksum must be set to 0 in the packet by + * the caller. + * + * @param ipv4_hdr + * The pointer to the contiguous IPv4 header. + * @param l4_hdr + * The pointer to the beginning of the L4 header. + * @return + * The complemented checksum to set in the IP packet. + */ +static inline uint16_t +rte_ipv4_udptcp_cksum(const struct rte_ipv4_hdr *ipv4_hdr, const void *l4_hdr) +{ + uint16_t cksum = __rte_ipv4_udptcp_cksum(ipv4_hdr, l4_hdr); + + cksum = ~cksum; + /* - * Per RFC 768:If the computed checksum is zero for UDP, + * Per RFC 768: If the computed checksum is zero for UDP, * it is transmitted as all ones * (the equivalent in one's complement arithmetic). */ @@ -386,6 +399,27 @@ rte_ipv4_udptcp_cksum(const struct rte_ipv4_hdr *ipv4_hdr, const void *l4_hdr) return (uint16_t)cksum; } +/** + * Validate the IPv4 UDP or TCP checksum. + * + * @param ipv4_hdr + * The pointer to the contiguous IPv4 header. + * @param l4_hdr + * The pointer to the beginning of the L4 header. + * @return + * Return 0 if the checksum is correct, else -1. + */ +static inline int +rte_ipv4_udptcp_cksum_verify(const struct rte_ipv4_hdr *ipv4_hdr, const void *l4_hdr) +{ + uint16_t cksum = __rte_ipv4_udptcp_cksum(ipv4_hdr, l4_hdr); + + if (cksum != 0xffff) + return -1; + + return 0; +} + /** * IPv6 Header */ @@ -448,6 +482,25 @@ rte_ipv6_phdr_cksum(const struct rte_ipv6_hdr *ipv6_hdr, uint64_t ol_flags) return __rte_raw_cksum_reduce(sum); } +/** + * @internal Calculate the non-complemented IPv4 L4 checksum + */ +static inline uint16_t +__rte_ipv6_udptcp_cksum(const struct rte_ipv6_hdr *ipv6_hdr, const void *l4_hdr) +{ + uint32_t cksum; + uint32_t l4_len; + + l4_len = rte_be_to_cpu_16(ipv6_hdr->payload_len); + + cksum = rte_raw_cksum(l4_hdr, l4_len); + cksum += rte_ipv6_phdr_cksum(ipv6_hdr, 0); + + cksum = ((cksum & 0xffff0000) >> 16) + (cksum & 0xffff); + + return cksum; +} + /** * Process the IPv6 UDP or TCP checksum. * @@ -464,16 +517,10 @@ rte_ipv6_phdr_cksum(const struct rte_ipv6_hdr *ipv6_hdr, uint64_t ol_flags) static inline uint16_t rte_ipv6_udptcp_cksum(const struct rte_ipv6_hdr *ipv6_hdr, const void *l4_hdr) { - uint32_t cksum; - uint32_t l4_len; + uint16_t cksum = __rte_ipv6_udptcp_cksum(ipv6_hdr, l4_hdr); - l4_len = rte_be_to_cpu_16(ipv6_hdr->payload_len); + cksum = ~cksum; - cksum = rte_raw_cksum(l4_hdr, l4_len); - cksum += rte_ipv6_phdr_cksum(ipv6_hdr, 0); - - cksum = ((cksum & 0xffff0000) >> 16) + (cksum & 0xffff); - cksum = (~cksum) & 0xffff; /* * Per RFC 768: If the computed checksum is zero for UDP, * it is transmitted as all ones @@ -485,6 +532,31 @@ rte_ipv6_udptcp_cksum(const struct rte_ipv6_hdr *ipv6_hdr, const void *l4_hdr) return (uint16_t)cksum; } +/** + * Validate the IPv6 UDP or TCP checksum. + * + * The function accepts a 0 checksum, since it can exceptionally happen. See 8.1 + * (Upper-Layer Checksums) in RFC 8200. + * + * @param ipv6_hdr + * The pointer to the contiguous IPv6 header. + * @param l4_hdr + * The pointer to the beginning of the L4 header. + * @return + * Return 0 if the checksum is correct, else -1. + */ +static inline int +rte_ipv6_udptcp_cksum_verify(const struct rte_ipv6_hdr *ipv6_hdr, const void *l4_hdr) +{ + uint16_t cksum; + + cksum = __rte_ipv6_udptcp_cksum(ipv6_hdr, l4_hdr); + if (cksum != 0xffff) + return -1; + + return 0; +} + /** IPv6 fragment extension header. */ #define RTE_IPV6_EHDR_MF_SHIFT 0 #define RTE_IPV6_EHDR_MF_MASK 1 -- 2.20.1