Packets to devices without NETIF_F_SCTP_CSUM (including NETIF_F_NO_CSUM)
should be properly checksummed because the packets can be diverted or
rerouted after construction. This still leaves packets diverted from
NETIF_F_SCTP_CSUM-enabled devices with broken checksums. Fixing this
needs implementing software offload fallback in networking core.
For users of sctp_checksum_disable, skb->ip_summed should be left as
CHECKSUM_NONE and not CHECKSUM_UNNECESSARY as per include/linux/skbuff.h.
Signed-off-by: Michał Mirosław <mirq-linux@xxxxxxxxxxxx>
---
net/sctp/output.c | 19 ++++++++-----------
1 files changed, 8 insertions(+), 11 deletions(-)
diff --git a/net/sctp/output.c b/net/sctp/output.c
index b4f3cf0..08b3cea 100644
--- a/net/sctp/output.c
+++ b/net/sctp/output.c
@@ -500,23 +500,20 @@ int sctp_packet_transmit(struct sctp_packet *packet)
* Note: Adler-32 is no longer applicable, as has been replaced
* by CRC32-C as described in <draft-ietf-tsvwg-sctpcsum-02.txt>.
*/
- if (!sctp_checksum_disable &&
- !(dst->dev->features & (NETIF_F_NO_CSUM | NETIF_F_SCTP_CSUM))) {
- __u32 crc32 = sctp_start_cksum((__u8 *)sh, cksum_buf_len);
+ if (!sctp_checksum_disable) {
+ if (!(dst->dev->features & NETIF_F_SCTP_CSUM)) {
+ __u32 crc32 = sctp_start_cksum((__u8 *)sh, cksum_buf_len);
- /* 3) Put the resultant value into the checksum field in the
- * common header, and leave the rest of the bits unchanged.
- */
- sh->checksum = sctp_end_cksum(crc32);
- } else {
- if (dst->dev->features & NETIF_F_SCTP_CSUM) {
+ /* 3) Put the resultant value into the checksum field in the
+ * common header, and leave the rest of the bits unchanged.
+ */
+ sh->checksum = sctp_end_cksum(crc32);
+ } else {
/* no need to seed pseudo checksum for SCTP */
nskb->ip_summed = CHECKSUM_PARTIAL;
nskb->csum_start = (skb_transport_header(nskb) -
nskb->head);
nskb->csum_offset = offsetof(struct sctphdr, checksum);
- } else {
- nskb->ip_summed = CHECKSUM_UNNECESSARY;
}
}
--
1.7.5.4
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