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90017accff
SCTP has this pecualiarity that its packets cannot be just segmented to
(P)MTU. Its chunks must be contained in IP segments, padding respected.
So we can't just generate a big skb, set gso_size to the fragmentation
point and deliver it to IP layer.
This patch takes a different approach. SCTP will now build a skb as it
would be if it was received using GRO. That is, there will be a cover
skb with protocol headers and children ones containing the actual
segments, already segmented to a way that respects SCTP RFCs.
With that, we can tell skb_segment() to just split based on frag_list,
trusting its sizes are already in accordance.
This way SCTP can benefit from GSO and instead of passing several
packets through the stack, it can pass a single large packet.
v2:
- Added support for receiving GSO frames, as requested by Dave Miller.
- Clear skb->cb if packet is GSO (otherwise it's not used by SCTP)
- Added heuristics similar to what we have in TCP for not generating
single GSO packets that fills cwnd.
v3:
- consider sctphdr size in skb_gso_transport_seglen()
- rebased due to 5c7cdf339a ("gso: Remove arbitrary checks for
unsupported GSO")
Signed-off-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Tested-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
99 lines
2.4 KiB
C
99 lines
2.4 KiB
C
/*
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* sctp_offload - GRO/GSO Offloading for SCTP
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*
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* Copyright (C) 2015, Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/kernel.h>
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#include <linux/kprobes.h>
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#include <linux/socket.h>
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#include <linux/sctp.h>
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#include <linux/proc_fs.h>
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#include <linux/vmalloc.h>
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#include <linux/module.h>
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#include <linux/kfifo.h>
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#include <linux/time.h>
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#include <net/net_namespace.h>
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#include <linux/skbuff.h>
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#include <net/sctp/sctp.h>
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#include <net/sctp/checksum.h>
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#include <net/protocol.h>
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static __le32 sctp_gso_make_checksum(struct sk_buff *skb)
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{
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skb->ip_summed = CHECKSUM_NONE;
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return sctp_compute_cksum(skb, skb_transport_offset(skb));
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}
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static struct sk_buff *sctp_gso_segment(struct sk_buff *skb,
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netdev_features_t features)
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{
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struct sk_buff *segs = ERR_PTR(-EINVAL);
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struct sctphdr *sh;
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sh = sctp_hdr(skb);
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if (!pskb_may_pull(skb, sizeof(*sh)))
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goto out;
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__skb_pull(skb, sizeof(*sh));
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if (skb_gso_ok(skb, features | NETIF_F_GSO_ROBUST)) {
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/* Packet is from an untrusted source, reset gso_segs. */
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struct skb_shared_info *pinfo = skb_shinfo(skb);
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struct sk_buff *frag_iter;
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pinfo->gso_segs = 0;
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if (skb->len != skb->data_len) {
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/* Means we have chunks in here too */
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pinfo->gso_segs++;
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}
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skb_walk_frags(skb, frag_iter)
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pinfo->gso_segs++;
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segs = NULL;
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goto out;
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}
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segs = skb_segment(skb, features | NETIF_F_HW_CSUM);
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if (IS_ERR(segs))
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goto out;
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/* All that is left is update SCTP CRC if necessary */
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if (!(features & NETIF_F_SCTP_CRC)) {
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for (skb = segs; skb; skb = skb->next) {
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if (skb->ip_summed == CHECKSUM_PARTIAL) {
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sh = sctp_hdr(skb);
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sh->checksum = sctp_gso_make_checksum(skb);
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}
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}
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}
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out:
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return segs;
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}
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static const struct net_offload sctp_offload = {
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.callbacks = {
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.gso_segment = sctp_gso_segment,
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},
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};
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int __init sctp_offload_init(void)
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{
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return inet_add_offload(&sctp_offload, IPPROTO_SCTP);
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}
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