In csum forwarding mode, software UDP/TCP csum calculation only takes
the first segment into account while using the whole packet length so
the calculation will read invalid memory region with multi-segments
packets and will get wrong value.
This patch fixes this issue.

Fixes: af75078fece3 ("first public release")
Cc: sta...@dpdk.org

Signed-off-by: Xiaoyun Li <xiaoyun...@intel.com>
---
v3:
 * Use rte_raw_cksum() for multi-segs case instead of copying the whole
 * packet.
v2:
 * Use static stack memory instead of dynamic allocating in datapath
---
 app/test-pmd/csumonly.c | 68 ++++++++++++++++++++++++++++++++---------
 1 file changed, 53 insertions(+), 15 deletions(-)

diff --git a/app/test-pmd/csumonly.c b/app/test-pmd/csumonly.c
index 090797318a..f3e60eb3c3 100644
--- a/app/test-pmd/csumonly.c
+++ b/app/test-pmd/csumonly.c
@@ -91,12 +91,41 @@ struct simple_gre_hdr {
 } __rte_packed;
 
 static uint16_t
-get_udptcp_checksum(void *l3_hdr, void *l4_hdr, uint16_t ethertype)
+get_udptcp_checksum(void *l3_hdr, struct rte_mbuf *m, uint16_t l4_off,
+                   uint16_t ethertype)
 {
+       uint16_t off = l4_off;
+       uint32_t cksum = 0;
+       char *buf;
+
+       while (m != NULL) {
+               buf = rte_pktmbuf_mtod_offset(m, char *, off);
+               cksum += rte_raw_cksum(buf, m->data_len - off);
+               off = 0;
+               m = m->next;
+       }
        if (ethertype == _htons(RTE_ETHER_TYPE_IPV4))
-               return rte_ipv4_udptcp_cksum(l3_hdr, l4_hdr);
+               cksum += rte_ipv4_phdr_cksum(l3_hdr, 0);
        else /* assume ethertype == RTE_ETHER_TYPE_IPV6 */
-               return rte_ipv6_udptcp_cksum(l3_hdr, l4_hdr);
+               cksum += rte_ipv6_phdr_cksum(l3_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
+        * (the equivalent in one's complement arithmetic).
+        */
+       if (cksum == 0 && ethertype == _htons(RTE_ETHER_TYPE_IPV4) &&
+           ((struct rte_ipv4_hdr *)l3_hdr)->next_proto_id == IPPROTO_UDP)
+               cksum = 0xffff;
+
+       if (cksum == 0 && ethertype == _htons(RTE_ETHER_TYPE_IPV6) &&
+           ((struct rte_ipv6_hdr *)l3_hdr)->proto == IPPROTO_UDP)
+               cksum = 0xffff;
+
+       return (uint16_t)cksum;
 }
 
 /* Parse an IPv4 header to fill l3_len, l4_len, and l4_proto */
@@ -455,7 +484,7 @@ parse_encap_ip(void *encap_ip, struct testpmd_offload_info 
*info)
  * depending on the testpmd command line configuration */
 static uint64_t
 process_inner_cksums(void *l3_hdr, const struct testpmd_offload_info *info,
-       uint64_t tx_offloads)
+       uint64_t tx_offloads, struct rte_mbuf *m)
 {
        struct rte_ipv4_hdr *ipv4_hdr = l3_hdr;
        struct rte_udp_hdr *udp_hdr;
@@ -463,6 +492,7 @@ process_inner_cksums(void *l3_hdr, const struct 
testpmd_offload_info *info,
        struct rte_sctp_hdr *sctp_hdr;
        uint64_t ol_flags = 0;
        uint32_t max_pkt_len, tso_segsz = 0;
+       uint16_t l4_off;
 
        /* ensure packet is large enough to require tso */
        if (!info->is_tunnel) {
@@ -505,9 +535,15 @@ process_inner_cksums(void *l3_hdr, const struct 
testpmd_offload_info *info,
                        if (tx_offloads & DEV_TX_OFFLOAD_UDP_CKSUM) {
                                ol_flags |= PKT_TX_UDP_CKSUM;
                        } else {
+                               if (info->is_tunnel)
+                                       l4_off = info->l2_len +
+                                               info->outer_l3_len +
+                                               info->l2_len + info->l3_len;
+                               else
+                                       l4_off = info->l2_len + info->l3_len;
                                udp_hdr->dgram_cksum = 0;
                                udp_hdr->dgram_cksum =
-                                       get_udptcp_checksum(l3_hdr, udp_hdr,
+                                       get_udptcp_checksum(l3_hdr, m, l4_off,
                                                info->ethertype);
                        }
                }
@@ -520,9 +556,14 @@ process_inner_cksums(void *l3_hdr, const struct 
testpmd_offload_info *info,
                else if (tx_offloads & DEV_TX_OFFLOAD_TCP_CKSUM) {
                        ol_flags |= PKT_TX_TCP_CKSUM;
                } else {
+                       if (info->is_tunnel)
+                               l4_off = info->l2_len + info->outer_l3_len +
+                                       info->l2_len + info->l3_len;
+                       else
+                               l4_off = info->l2_len + info->l3_len;
                        tcp_hdr->cksum = 0;
                        tcp_hdr->cksum =
-                               get_udptcp_checksum(l3_hdr, tcp_hdr,
+                               get_udptcp_checksum(l3_hdr, m, l4_off,
                                        info->ethertype);
                }
                if (info->gso_enable)
@@ -548,7 +589,7 @@ process_inner_cksums(void *l3_hdr, const struct 
testpmd_offload_info *info,
 /* Calculate the checksum of outer header */
 static uint64_t
 process_outer_cksums(void *outer_l3_hdr, struct testpmd_offload_info *info,
-       uint64_t tx_offloads, int tso_enabled)
+       uint64_t tx_offloads, int tso_enabled, struct rte_mbuf *m)
 {
        struct rte_ipv4_hdr *ipv4_hdr = outer_l3_hdr;
        struct rte_ipv6_hdr *ipv6_hdr = outer_l3_hdr;
@@ -602,12 +643,9 @@ process_outer_cksums(void *outer_l3_hdr, struct 
testpmd_offload_info *info,
        /* do not recalculate udp cksum if it was 0 */
        if (udp_hdr->dgram_cksum != 0) {
                udp_hdr->dgram_cksum = 0;
-               if (info->outer_ethertype == _htons(RTE_ETHER_TYPE_IPV4))
-                       udp_hdr->dgram_cksum =
-                               rte_ipv4_udptcp_cksum(ipv4_hdr, udp_hdr);
-               else
-                       udp_hdr->dgram_cksum =
-                               rte_ipv6_udptcp_cksum(ipv6_hdr, udp_hdr);
+               udp_hdr->dgram_cksum = get_udptcp_checksum(outer_l3_hdr,
+                                       m, info->l2_len + info->outer_l3_len,
+                                       info->outer_ethertype);
        }
 
        return ol_flags;
@@ -942,7 +980,7 @@ pkt_burst_checksum_forward(struct fwd_stream *fs)
 
                /* process checksums of inner headers first */
                tx_ol_flags |= process_inner_cksums(l3_hdr, &info,
-                       tx_offloads);
+                       tx_offloads, m);
 
                /* Then process outer headers if any. Note that the software
                 * checksum will be wrong if one of the inner checksums is
@@ -950,7 +988,7 @@ pkt_burst_checksum_forward(struct fwd_stream *fs)
                if (info.is_tunnel == 1) {
                        tx_ol_flags |= process_outer_cksums(outer_l3_hdr, &info,
                                        tx_offloads,
-                                       !!(tx_ol_flags & PKT_TX_TCP_SEG));
+                                       !!(tx_ol_flags & PKT_TX_TCP_SEG), m);
                }
 
                /* step 3: fill the mbuf meta data (flags and header lengths) */
-- 
2.25.1

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