1/*
  2 * sctp_offload - GRO/GSO Offloading for SCTP
  3 *
  4 * Copyright (C) 2015, Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
  5 *
  6 * This program is free software; you can redistribute it and/or modify
  7 * it under the terms of the GNU General Public License as published by
  8 * the Free Software Foundation; either version 2 of the License, or
  9 * (at your option) any later version.
 10 *
 11 * This program is distributed in the hope that it will be useful,
 12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 14 * GNU General Public License for more details.
 15 */
 16
 17#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 18
 19#include <linux/kernel.h>
 20#include <linux/kprobes.h>
 21#include <linux/socket.h>
 22#include <linux/sctp.h>
 23#include <linux/proc_fs.h>
 24#include <linux/vmalloc.h>
 25#include <linux/module.h>
 26#include <linux/kfifo.h>
 27#include <linux/time.h>
 28#include <net/net_namespace.h>
 29
 30#include <linux/skbuff.h>
 31#include <net/sctp/sctp.h>
 32#include <net/sctp/checksum.h>
 33#include <net/protocol.h>
 34
 35static __le32 sctp_gso_make_checksum(struct sk_buff *skb)
 36{
 37	skb->ip_summed = CHECKSUM_NONE;
 38	skb->csum_not_inet = 0;
 39	return sctp_compute_cksum(skb, skb_transport_offset(skb));
 40}
 41
 42static struct sk_buff *sctp_gso_segment(struct sk_buff *skb,
 43					netdev_features_t features)
 44{
 45	struct sk_buff *segs = ERR_PTR(-EINVAL);
 46	struct sctphdr *sh;
 47
 48	if (!skb_is_gso_sctp(skb))
 49		goto out;
 50
 51	sh = sctp_hdr(skb);
 52	if (!pskb_may_pull(skb, sizeof(*sh)))
 53		goto out;
 54
 55	__skb_pull(skb, sizeof(*sh));
 56
 57	if (skb_gso_ok(skb, features | NETIF_F_GSO_ROBUST)) {
 58		/* Packet is from an untrusted source, reset gso_segs. */
 59		struct skb_shared_info *pinfo = skb_shinfo(skb);
 60		struct sk_buff *frag_iter;
 61
 62		pinfo->gso_segs = 0;
 63		if (skb->len != skb->data_len) {
 64			/* Means we have chunks in here too */
 65			pinfo->gso_segs++;
 66		}
 67
 68		skb_walk_frags(skb, frag_iter)
 69			pinfo->gso_segs++;
 70
 71		segs = NULL;
 72		goto out;
 73	}
 74
 75	segs = skb_segment(skb, features | NETIF_F_HW_CSUM | NETIF_F_SG);
 76	if (IS_ERR(segs))
 77		goto out;
 78
 79	/* All that is left is update SCTP CRC if necessary */
 80	if (!(features & NETIF_F_SCTP_CRC)) {
 81		for (skb = segs; skb; skb = skb->next) {
 82			if (skb->ip_summed == CHECKSUM_PARTIAL) {
 83				sh = sctp_hdr(skb);
 84				sh->checksum = sctp_gso_make_checksum(skb);
 85			}
 86		}
 87	}
 88
 89out:
 90	return segs;
 91}
 92
 93static const struct net_offload sctp_offload = {
 94	.callbacks = {
 95		.gso_segment = sctp_gso_segment,
 96	},
 97};
 98
 99static const struct net_offload sctp6_offload = {
100	.callbacks = {
101		.gso_segment = sctp_gso_segment,
102	},
103};
104
105static const struct skb_checksum_ops crc32c_csum_ops = {
106	.update  = sctp_csum_update,
107	.combine = sctp_csum_combine,
108};
109
110int __init sctp_offload_init(void)
111{
112	int ret;
113
114	ret = inet_add_offload(&sctp_offload, IPPROTO_SCTP);
115	if (ret)
116		goto out;
117
118	ret = inet6_add_offload(&sctp6_offload, IPPROTO_SCTP);
119	if (ret)
120		goto ipv4;
121
122	crc32c_csum_stub = &crc32c_csum_ops;
123	return ret;
124
125ipv4:
126	inet_del_offload(&sctp_offload, IPPROTO_SCTP);
127out:
128	return ret;
129}