1/*
2 *	IPV6 GSO/GRO offload support
3 *	Linux INET6 implementation
4 *
5 *	This program is free software; you can redistribute it and/or
6 *      modify it under the terms of the GNU General Public License
7 *      as published by the Free Software Foundation; either version
8 *      2 of the License, or (at your option) any later version.
9 *
10 *      UDPv6 GSO support
11 */
12#include <linux/skbuff.h>
13#include <linux/netdevice.h>
14#include <net/protocol.h>
15#include <net/ipv6.h>
16#include <net/udp.h>
17#include <net/ip6_checksum.h>
18#include "ip6_offload.h"
19
20static struct sk_buff *udp6_ufo_fragment(struct sk_buff *skb,
21					 netdev_features_t features)
22{
23	struct sk_buff *segs = ERR_PTR(-EINVAL);
24	unsigned int mss;
25	unsigned int unfrag_ip6hlen, unfrag_len;
26	struct frag_hdr *fptr;
27	u8 *packet_start, *prevhdr;
28	u8 nexthdr;
29	u8 frag_hdr_sz = sizeof(struct frag_hdr);
30	__wsum csum;
31	int tnl_hlen;
32
33	mss = skb_shinfo(skb)->gso_size;
34	if (unlikely(skb->len <= mss))
35		goto out;
36
37	if (skb_gso_ok(skb, features | NETIF_F_GSO_ROBUST)) {
38		/* Packet is from an untrusted source, reset gso_segs. */
39		int type = skb_shinfo(skb)->gso_type;
40
41		if (unlikely(type & ~(SKB_GSO_UDP |
42				      SKB_GSO_DODGY |
43				      SKB_GSO_UDP_TUNNEL |
44				      SKB_GSO_UDP_TUNNEL_CSUM |
45				      SKB_GSO_TUNNEL_REMCSUM |
46				      SKB_GSO_GRE |
47				      SKB_GSO_GRE_CSUM |
48				      SKB_GSO_IPIP |
49				      SKB_GSO_SIT) ||
50			     !(type & (SKB_GSO_UDP))))
51			goto out;
52
53		skb_shinfo(skb)->gso_segs = DIV_ROUND_UP(skb->len, mss);
54
55		/* Set the IPv6 fragment id if not set yet */
56		if (!skb_shinfo(skb)->ip6_frag_id)
57			ipv6_proxy_select_ident(dev_net(skb->dev), skb);
58
59		segs = NULL;
60		goto out;
61	}
62
63	if (skb->encapsulation && skb_shinfo(skb)->gso_type &
64	    (SKB_GSO_UDP_TUNNEL|SKB_GSO_UDP_TUNNEL_CSUM))
65		segs = skb_udp_tunnel_segment(skb, features, true);
66	else {
67		const struct ipv6hdr *ipv6h;
68		struct udphdr *uh;
69
70		if (!pskb_may_pull(skb, sizeof(struct udphdr)))
71			goto out;
72
73		/* Do software UFO. Complete and fill in the UDP checksum as HW cannot
74		 * do checksum of UDP packets sent as multiple IP fragments.
75		 */
76
77		uh = udp_hdr(skb);
78		ipv6h = ipv6_hdr(skb);
79
80		uh->check = 0;
81		csum = skb_checksum(skb, 0, skb->len, 0);
82		uh->check = udp_v6_check(skb->len, &ipv6h->saddr,
83					  &ipv6h->daddr, csum);
84
85		if (uh->check == 0)
86			uh->check = CSUM_MANGLED_0;
87
88		skb->ip_summed = CHECKSUM_NONE;
89
90		/* Check if there is enough headroom to insert fragment header. */
91		tnl_hlen = skb_tnl_header_len(skb);
92		if (skb->mac_header < (tnl_hlen + frag_hdr_sz)) {
93			if (gso_pskb_expand_head(skb, tnl_hlen + frag_hdr_sz))
94				goto out;
95		}
96
97		/* Find the unfragmentable header and shift it left by frag_hdr_sz
98		 * bytes to insert fragment header.
99		 */
100		unfrag_ip6hlen = ip6_find_1stfragopt(skb, &prevhdr);
101		nexthdr = *prevhdr;
102		*prevhdr = NEXTHDR_FRAGMENT;
103		unfrag_len = (skb_network_header(skb) - skb_mac_header(skb)) +
104			     unfrag_ip6hlen + tnl_hlen;
105		packet_start = (u8 *) skb->head + SKB_GSO_CB(skb)->mac_offset;
106		memmove(packet_start-frag_hdr_sz, packet_start, unfrag_len);
107
108		SKB_GSO_CB(skb)->mac_offset -= frag_hdr_sz;
109		skb->mac_header -= frag_hdr_sz;
110		skb->network_header -= frag_hdr_sz;
111
112		fptr = (struct frag_hdr *)(skb_network_header(skb) + unfrag_ip6hlen);
113		fptr->nexthdr = nexthdr;
114		fptr->reserved = 0;
115		if (!skb_shinfo(skb)->ip6_frag_id)
116			ipv6_proxy_select_ident(dev_net(skb->dev), skb);
117		fptr->identification = skb_shinfo(skb)->ip6_frag_id;
118
119		/* Fragment the skb. ipv6 header and the remaining fields of the
120		 * fragment header are updated in ipv6_gso_segment()
121		 */
122		segs = skb_segment(skb, features);
123	}
124
125out:
126	return segs;
127}
128
129static struct sk_buff **udp6_gro_receive(struct sk_buff **head,
130					 struct sk_buff *skb)
131{
132	struct udphdr *uh = udp_gro_udphdr(skb);
133
134	if (unlikely(!uh))
135		goto flush;
136
137	/* Don't bother verifying checksum if we're going to flush anyway. */
138	if (NAPI_GRO_CB(skb)->flush)
139		goto skip;
140
141	if (skb_gro_checksum_validate_zero_check(skb, IPPROTO_UDP, uh->check,
142						 ip6_gro_compute_pseudo))
143		goto flush;
144	else if (uh->check)
145		skb_gro_checksum_try_convert(skb, IPPROTO_UDP, uh->check,
146					     ip6_gro_compute_pseudo);
147
148skip:
149	NAPI_GRO_CB(skb)->is_ipv6 = 1;
150	return udp_gro_receive(head, skb, uh);
151
152flush:
153	NAPI_GRO_CB(skb)->flush = 1;
154	return NULL;
155}
156
157static int udp6_gro_complete(struct sk_buff *skb, int nhoff)
158{
159	const struct ipv6hdr *ipv6h = ipv6_hdr(skb);
160	struct udphdr *uh = (struct udphdr *)(skb->data + nhoff);
161
162	if (uh->check) {
163		skb_shinfo(skb)->gso_type |= SKB_GSO_UDP_TUNNEL_CSUM;
164		uh->check = ~udp_v6_check(skb->len - nhoff, &ipv6h->saddr,
165					  &ipv6h->daddr, 0);
166	} else {
167		skb_shinfo(skb)->gso_type |= SKB_GSO_UDP_TUNNEL;
168	}
169
170	return udp_gro_complete(skb, nhoff);
171}
172
173static const struct net_offload udpv6_offload = {
174	.callbacks = {
175		.gso_segment	=	udp6_ufo_fragment,
176		.gro_receive	=	udp6_gro_receive,
177		.gro_complete	=	udp6_gro_complete,
178	},
179};
180
181int __init udp_offload_init(void)
182{
183	return inet6_add_offload(&udpv6_offload, IPPROTO_UDP);
184}
185