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#include <net/gso.h>
26
27static __le32 sctp_gso_make_checksum(struct sk_buff *skb)
28{
29	skb->ip_summed = CHECKSUM_NONE;
30	skb->csum_not_inet = 0;
31	/* csum and csum_start in GSO CB may be needed to do the UDP
32	 * checksum when it's a UDP tunneling packet.
33	 */
34	SKB_GSO_CB(skb)->csum = (__force __wsum)~0;
35	SKB_GSO_CB(skb)->csum_start = skb_headroom(skb) + skb->len;
36	return sctp_compute_cksum(skb, skb_transport_offset(skb));
37}
38
39static struct sk_buff *sctp_gso_segment(struct sk_buff *skb,
40					netdev_features_t features)
41{
42	struct sk_buff *segs = ERR_PTR(-EINVAL);
43	struct sctphdr *sh;
44
45	if (!skb_is_gso_sctp(skb))
46		goto out;
47
48	sh = sctp_hdr(skb);
49	if (!pskb_may_pull(skb, sizeof(*sh)))
50		goto out;
51
52	__skb_pull(skb, sizeof(*sh));
53
54	if (skb_gso_ok(skb, features | NETIF_F_GSO_ROBUST)) {
55		/* Packet is from an untrusted source, reset gso_segs. */
56		struct skb_shared_info *pinfo = skb_shinfo(skb);
57		struct sk_buff *frag_iter;
58
59		pinfo->gso_segs = 0;
60		if (skb->len != skb->data_len) {
61			/* Means we have chunks in here too */
62			pinfo->gso_segs++;
63		}
64
65		skb_walk_frags(skb, frag_iter)
66			pinfo->gso_segs++;
67
68		segs = NULL;
69		goto out;
70	}
71
72	segs = skb_segment(skb, (features | NETIF_F_HW_CSUM) & ~NETIF_F_SG);
73	if (IS_ERR(segs))
74		goto out;
75
76	/* All that is left is update SCTP CRC if necessary */
77	if (!(features & NETIF_F_SCTP_CRC)) {
78		for (skb = segs; skb; skb = skb->next) {
79			if (skb->ip_summed == CHECKSUM_PARTIAL) {
80				sh = sctp_hdr(skb);
81				sh->checksum = sctp_gso_make_checksum(skb);
82			}
83		}
84	}
85
86out:
87	return segs;
88}
89
90static const struct net_offload sctp_offload = {
91	.callbacks = {
92		.gso_segment = sctp_gso_segment,
93	},
94};
95
96static const struct net_offload sctp6_offload = {
97	.callbacks = {
98		.gso_segment = sctp_gso_segment,
99	},
100};
101
102int __init sctp_offload_init(void)
103{
104	int ret;
105
106	ret = inet_add_offload(&sctp_offload, IPPROTO_SCTP);
107	if (ret)
108		goto out;
109
110	ret = inet6_add_offload(&sctp6_offload, IPPROTO_SCTP);
111	if (ret)
112		goto ipv4;
113
114	crc32c_csum_stub = &sctp_csum_ops;
115	return ret;
116
117ipv4:
118	inet_del_offload(&sctp_offload, IPPROTO_SCTP);
119out:
120	return ret;
121}
122