ip_frag: fix IPv6 when MTU sizes not aligned to 8 bytes

The same issue was fixed on for the ipv4 version of this routine in
commit 8d4d3a4f7337 ("ip_frag: handle MTU sizes not aligned to 8 bytes").
Briefly, the size of an ipv6 header is always 40 bytes.  With an MTU of
1500, this will never produce a multiple of 8 bytes for the frag_size
and this routine can never succeed. Since RTE_ASSERTS are disabled by
default, this failure is typically ignored.

To fix this, round down to the nearest 8 bytes and use this when
producing the fragments.

Fixes: 0aa31d7a5929 ("ip_frag: add IPv6 fragmentation support")
Cc: stable@dpdk.org
Signed-off-by: Chas Williams <chas3@att.com>
Acked-by: Luca Boccassi <bluca@debian.org>
Acked-by: Konstantin Ananyev <konstantin.ananyev@intel.com>

diff --git a/lib/librte_ip_frag/rte_ip_frag.h b/lib/librte_ip_frag/rte_ip_frag.h
index a4ccaf9..04fd9df 100644 (file)
--- a/lib/librte_ip_frag/rte_ip_frag.h
+++ b/lib/librte_ip_frag/rte_ip_frag.h
@@ -115,6 +115,7 @@ struct rte_ip_frag_tbl {
 #define        RTE_IPV6_EHDR_MF_MASK                   1
 #define        RTE_IPV6_EHDR_FO_SHIFT                  3
 #define        RTE_IPV6_EHDR_FO_MASK                   (~((1 << RTE_IPV6_EHDR_FO_SHIFT) - 1))
+#define        RTE_IPV6_EHDR_FO_ALIGN                  (1 << RTE_IPV6_EHDR_FO_SHIFT)
 
 #define RTE_IPV6_FRAG_USED_MASK                        \
        (RTE_IPV6_EHDR_MF_MASK | RTE_IPV6_EHDR_FO_MASK)

diff --git a/lib/librte_ip_frag/rte_ipv6_fragmentation.c b/lib/librte_ip_frag/rte_ipv6_fragmentation.c
index 62a7e4e..b9437eb 100644 (file)
--- a/lib/librte_ip_frag/rte_ipv6_fragmentation.c
+++ b/lib/librte_ip_frag/rte_ipv6_fragmentation.c
@@ -77,11 +77,14 @@ rte_ipv6_fragment_packet(struct rte_mbuf *pkt_in,
        uint32_t out_pkt_pos, in_seg_data_pos;
        uint32_t more_in_segs;
        uint16_t fragment_offset, frag_size;
+       uint64_t frag_bytes_remaining;
 
-       frag_size = (uint16_t)(mtu_size - sizeof(struct ipv6_hdr));
-
-       /* Fragment size should be a multiple of 8. */
-       RTE_ASSERT((frag_size & ~RTE_IPV6_EHDR_FO_MASK) == 0);
+       /*
+        * Ensure the IP payload length of all fragments (except the
+        * the last fragment) are a multiple of 8 bytes per RFC2460.
+        */
+       frag_size = RTE_ALIGN_FLOOR(mtu_size - sizeof(struct ipv6_hdr),
+                                   RTE_IPV6_EHDR_FO_ALIGN);
 
        /* Check that pkts_out is big enough to hold all fragments */
        if (unlikely (frag_size * nb_pkts_out <
@@ -111,6 +114,7 @@ rte_ipv6_fragment_packet(struct rte_mbuf *pkt_in,
                /* Reserve space for the IP header that will be built later */
                out_pkt->data_len = sizeof(struct ipv6_hdr) + sizeof(struct ipv6_extension_fragment);
                out_pkt->pkt_len  = sizeof(struct ipv6_hdr) + sizeof(struct ipv6_extension_fragment);
+               frag_bytes_remaining = frag_size;
 
                out_seg_prev = out_pkt;
                more_out_segs = 1;
@@ -130,7 +134,7 @@ rte_ipv6_fragment_packet(struct rte_mbuf *pkt_in,
 
                        /* Prepare indirect buffer */
                        rte_pktmbuf_attach(out_seg, in_seg);
-                       len = mtu_size - out_pkt->pkt_len;
+                       len = frag_bytes_remaining;
                        if (len > (in_seg->data_len - in_seg_data_pos)) {
                                len = in_seg->data_len - in_seg_data_pos;
                        }
@@ -140,11 +144,11 @@ rte_ipv6_fragment_packet(struct rte_mbuf *pkt_in,
                            out_pkt->pkt_len);
                        out_pkt->nb_segs += 1;
                        in_seg_data_pos += len;
+                       frag_bytes_remaining -= len;
 
                        /* Current output packet (i.e. fragment) done ? */
-                       if (unlikely(out_pkt->pkt_len >= mtu_size)) {
+                       if (unlikely(frag_bytes_remaining == 0))
                                more_out_segs = 0;
-                       }
 
                        /* Current input segment done ? */
                        if (unlikely(in_seg_data_pos == in_seg->data_len)) {