[v2,3/4] net: introduce functions to verify L4 checksums
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Commit Message
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 <olivier.matz@6wind.com>
Acked-by: Morten Brørup <mb@smartsharesystems.com>
---
drivers/net/tap/rte_eth_tap.c | 7 +-
lib/net/rte_ip.h | 127 +++++++++++++++++++++++++++-------
2 files changed, 107 insertions(+), 27 deletions(-)
@@ -369,11 +369,12 @@ 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;
}
@@ -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;
@@ -374,16 +364,65 @@ 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 (uint16_t)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).
*/
if (cksum == 0 && ipv4_hdr->next_proto_id == IPPROTO_UDP)
cksum = 0xffff;
- return (uint16_t)cksum;
+ return cksum;
+}
+
+/**
+ * Validate the IPv4 UDP or TCP checksum.
+ *
+ * In case of UDP, the caller must first check if udp_hdr->dgram_cksum is 0
+ * (i.e. no 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.
+ */
+__rte_experimental
+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;
}
/**
@@ -448,6 +487,25 @@ 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 (uint16_t)cksum;
+}
+
/**
* Process the IPv6 UDP or TCP checksum.
*
@@ -464,16 +522,10 @@ 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 = rte_raw_cksum(l4_hdr, l4_len);
- cksum += rte_ipv6_phdr_cksum(ipv6_hdr, 0);
+ cksum = ~cksum;
- 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
@@ -482,7 +534,34 @@ rte_ipv6_udptcp_cksum(const struct rte_ipv6_hdr *ipv6_hdr, const void *l4_hdr)
if (cksum == 0 && ipv6_hdr->proto == IPPROTO_UDP)
cksum = 0xffff;
- return (uint16_t)cksum;
+ return cksum;
+}
+
+/**
+ * Validate the IPv6 UDP or TCP checksum.
+ *
+ * In case of UDP, the caller must first check if udp_hdr->dgram_cksum is 0:
+ * this is either invalid or means no checksum in some situations. 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.
+ */
+__rte_experimental
+static inline int
+rte_ipv6_udptcp_cksum_verify(const struct rte_ipv6_hdr *ipv6_hdr,
+ const void *l4_hdr)
+{
+ uint16_t cksum = __rte_ipv6_udptcp_cksum(ipv6_hdr, l4_hdr);
+
+ if (cksum != 0xffff)
+ return -1;
+
+ return 0;
}
/** IPv6 fragment extension header. */