net: sctp: fix checksum marking for outgoing packets (b73c43f8) · Commits · 戴 / test

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@rere.qmqm.pl> Signed-off-by:

David S. Miller <davem@davemloft.net>

net/sctp/output.c

+8 −11

Original line number	Diff line number	Diff line
		@@ -500,8 +500,8 @@ 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		* Note: Adler-32 is no longer applicable, as has been replaced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))) {
		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
		@@ -509,14 +509,11 @@ int sctp_packet_transmit(struct sctp_packet *packet)
		*/
		sh->checksum = sctp_end_cksum(crc32);
		} else {
		if (dst->dev->features & NETIF_F_SCTP_CSUM) {
		/* 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;
		}
		}

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