1// SPDX-License-Identifier: GPL-2.0-or-later
  2/*
  3 * sctp_offload - GRO/GSO Offloading for SCTP
  4 *
  5 * Copyright (C) 2015, Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
  6 */
  7
  8#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  9
 10#include <linux/kernel.h>
 11#include <linux/kprobes.h>
 12#include <linux/socket.h>
 13#include <linux/sctp.h>
 14#include <linux/proc_fs.h>
 15#include <linux/vmalloc.h>
 16#include <linux/module.h>
 17#include <linux/kfifo.h>
 18#include <linux/time.h>
 19#include <net/net_namespace.h>
 20
 21#include <linux/skbuff.h>
 22#include <net/sctp/sctp.h>
 23#include <net/sctp/checksum.h>
 24#include <net/protocol.h>
 25
 26static __le32 sctp_gso_make_checksum(struct sk_buff *skb)
 27{
 28	skb->ip_summed = CHECKSUM_NONE;
 29	skb->csum_not_inet = 0;
 30	/* csum and csum_start in GSO CB may be needed to do the UDP
 31	 * checksum when it's a UDP tunneling packet.
 32	 */
 33	SKB_GSO_CB(skb)->csum = (__force __wsum)~0;
 34	SKB_GSO_CB(skb)->csum_start = skb_headroom(skb) + skb->len;
 35	return sctp_compute_cksum(skb, skb_transport_offset(skb));
 36}
 37
 38static struct sk_buff *sctp_gso_segment(struct sk_buff *skb,
 39					netdev_features_t features)
 40{
 41	struct sk_buff *segs = ERR_PTR(-EINVAL);
 42	struct sctphdr *sh;
 43
 44	if (!skb_is_gso_sctp(skb))
 45		goto out;
 46
 47	sh = sctp_hdr(skb);
 48	if (!pskb_may_pull(skb, sizeof(*sh)))
 49		goto out;
 50
 51	__skb_pull(skb, sizeof(*sh));
 52
 53	if (skb_gso_ok(skb, features | NETIF_F_GSO_ROBUST)) {
 54		/* Packet is from an untrusted source, reset gso_segs. */
 55		struct skb_shared_info *pinfo = skb_shinfo(skb);
 56		struct sk_buff *frag_iter;
 57
 58		pinfo->gso_segs = 0;
 59		if (skb->len != skb->data_len) {
 60			/* Means we have chunks in here too */
 61			pinfo->gso_segs++;
 62		}
 63
 64		skb_walk_frags(skb, frag_iter)
 65			pinfo->gso_segs++;
 66
 67		segs = NULL;
 68		goto out;
 69	}
 70
 71	segs = skb_segment(skb, (features | NETIF_F_HW_CSUM) & ~NETIF_F_SG);
 72	if (IS_ERR(segs))
 73		goto out;
 74
 75	/* All that is left is update SCTP CRC if necessary */
 76	if (!(features & NETIF_F_SCTP_CRC)) {
 77		for (skb = segs; skb; skb = skb->next) {
 78			if (skb->ip_summed == CHECKSUM_PARTIAL) {
 79				sh = sctp_hdr(skb);
 80				sh->checksum = sctp_gso_make_checksum(skb);
 81			}
 82		}
 83	}
 84
 85out:
 86	return segs;
 87}
 88
 89static const struct net_offload sctp_offload = {
 90	.callbacks = {
 91		.gso_segment = sctp_gso_segment,
 92	},
 93};
 94
 95static const struct net_offload sctp6_offload = {
 96	.callbacks = {
 97		.gso_segment = sctp_gso_segment,
 98	},
 99};
100
101int __init sctp_offload_init(void)
102{
103	int ret;
104
105	ret = inet_add_offload(&sctp_offload, IPPROTO_SCTP);
106	if (ret)
107		goto out;
108
109	ret = inet6_add_offload(&sctp6_offload, IPPROTO_SCTP);
110	if (ret)
111		goto ipv4;
112
113	crc32c_csum_stub = &sctp_csum_ops;
114	return ret;
115
116ipv4:
117	inet_del_offload(&sctp_offload, IPPROTO_SCTP);
118out:
119	return ret;
120}