1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * IPV6 GSO/GRO offload support
4 * Linux INET6 implementation
5 *
6 * UDPv6 GSO support
7 */
8#include <linux/skbuff.h>
9#include <linux/netdevice.h>
10#include <linux/indirect_call_wrapper.h>
11#include <net/protocol.h>
12#include <net/ipv6.h>
13#include <net/udp.h>
14#include <net/ip6_checksum.h>
15#include "ip6_offload.h"
16#include <net/gro.h>
17#include <net/gso.h>
18
19static struct sk_buff *udp6_ufo_fragment(struct sk_buff *skb,
20 netdev_features_t features)
21{
22 struct sk_buff *segs = ERR_PTR(error: -EINVAL);
23 unsigned int mss;
24 unsigned int unfrag_ip6hlen, unfrag_len;
25 struct frag_hdr *fptr;
26 u8 *packet_start, *prevhdr;
27 u8 nexthdr;
28 u8 frag_hdr_sz = sizeof(struct frag_hdr);
29 __wsum csum;
30 int tnl_hlen;
31 int err;
32
33 if (skb->encapsulation && skb_shinfo(skb)->gso_type &
34 (SKB_GSO_UDP_TUNNEL|SKB_GSO_UDP_TUNNEL_CSUM))
35 segs = skb_udp_tunnel_segment(skb, features, is_ipv6: true);
36 else {
37 const struct ipv6hdr *ipv6h;
38 struct udphdr *uh;
39
40 if (!(skb_shinfo(skb)->gso_type & (SKB_GSO_UDP | SKB_GSO_UDP_L4)))
41 goto out;
42
43 if (!pskb_may_pull(skb, len: sizeof(struct udphdr)))
44 goto out;
45
46 if (skb_shinfo(skb)->gso_type & SKB_GSO_UDP_L4)
47 return __udp_gso_segment(gso_skb: skb, features, is_ipv6: true);
48
49 mss = skb_shinfo(skb)->gso_size;
50 if (unlikely(skb->len <= mss))
51 goto out;
52
53 /* Do software UFO. Complete and fill in the UDP checksum as HW cannot
54 * do checksum of UDP packets sent as multiple IP fragments.
55 */
56
57 uh = udp_hdr(skb);
58 ipv6h = ipv6_hdr(skb);
59
60 uh->check = 0;
61 csum = skb_checksum(skb, offset: 0, len: skb->len, csum: 0);
62 uh->check = udp_v6_check(len: skb->len, saddr: &ipv6h->saddr,
63 daddr: &ipv6h->daddr, base: csum);
64 if (uh->check == 0)
65 uh->check = CSUM_MANGLED_0;
66
67 skb->ip_summed = CHECKSUM_UNNECESSARY;
68
69 /* If there is no outer header we can fake a checksum offload
70 * due to the fact that we have already done the checksum in
71 * software prior to segmenting the frame.
72 */
73 if (!skb->encap_hdr_csum)
74 features |= NETIF_F_HW_CSUM;
75
76 /* Check if there is enough headroom to insert fragment header. */
77 tnl_hlen = skb_tnl_header_len(inner_skb: skb);
78 if (skb->mac_header < (tnl_hlen + frag_hdr_sz)) {
79 if (gso_pskb_expand_head(skb, extra: tnl_hlen + frag_hdr_sz))
80 goto out;
81 }
82
83 /* Find the unfragmentable header and shift it left by frag_hdr_sz
84 * bytes to insert fragment header.
85 */
86 err = ip6_find_1stfragopt(skb, nexthdr: &prevhdr);
87 if (err < 0)
88 return ERR_PTR(error: err);
89 unfrag_ip6hlen = err;
90 nexthdr = *prevhdr;
91 *prevhdr = NEXTHDR_FRAGMENT;
92 unfrag_len = (skb_network_header(skb) - skb_mac_header(skb)) +
93 unfrag_ip6hlen + tnl_hlen;
94 packet_start = (u8 *) skb->head + SKB_GSO_CB(skb)->mac_offset;
95 memmove(packet_start-frag_hdr_sz, packet_start, unfrag_len);
96
97 SKB_GSO_CB(skb)->mac_offset -= frag_hdr_sz;
98 skb->mac_header -= frag_hdr_sz;
99 skb->network_header -= frag_hdr_sz;
100
101 fptr = (struct frag_hdr *)(skb_network_header(skb) + unfrag_ip6hlen);
102 fptr->nexthdr = nexthdr;
103 fptr->reserved = 0;
104 fptr->identification = ipv6_proxy_select_ident(net: dev_net(dev: skb->dev), skb);
105
106 /* Fragment the skb. ipv6 header and the remaining fields of the
107 * fragment header are updated in ipv6_gso_segment()
108 */
109 segs = skb_segment(skb, features);
110 }
111
112out:
113 return segs;
114}
115
116static struct sock *udp6_gro_lookup_skb(struct sk_buff *skb, __be16 sport,
117 __be16 dport)
118{
119 const struct ipv6hdr *iph = skb_gro_network_header(skb);
120 struct net *net = dev_net_rcu(dev: skb->dev);
121 struct sock *sk;
122 int iif, sdif;
123
124 sk = udp_tunnel_sk(net, is_ipv6: true);
125 if (sk && dport == htons(sk->sk_num))
126 return sk;
127
128 inet6_get_iif_sdif(skb, iif: &iif, sdif: &sdif);
129
130 return __udp6_lib_lookup(net, saddr: &iph->saddr, sport,
131 daddr: &iph->daddr, dport, dif: iif,
132 sdif, tbl: net->ipv4.udp_table, NULL);
133}
134
135INDIRECT_CALLABLE_SCOPE
136struct sk_buff *udp6_gro_receive(struct list_head *head, struct sk_buff *skb)
137{
138 struct udphdr *uh = udp_gro_udphdr(skb);
139 struct sock *sk = NULL;
140 struct sk_buff *pp;
141
142 if (unlikely(!uh))
143 goto flush;
144
145 /* Don't bother verifying checksum if we're going to flush anyway. */
146 if (NAPI_GRO_CB(skb)->flush)
147 goto skip;
148
149 if (skb_gro_checksum_validate_zero_check(skb, IPPROTO_UDP, uh->check,
150 ip6_gro_compute_pseudo))
151 goto flush;
152 else if (uh->check)
153 skb_gro_checksum_try_convert(skb, IPPROTO_UDP,
154 ip6_gro_compute_pseudo);
155
156skip:
157 if (static_branch_unlikely(&udpv6_encap_needed_key))
158 sk = udp6_gro_lookup_skb(skb, sport: uh->source, dport: uh->dest);
159
160 pp = udp_gro_receive(head, skb, uh, sk);
161 return pp;
162
163flush:
164 NAPI_GRO_CB(skb)->flush = 1;
165 return NULL;
166}
167
168INDIRECT_CALLABLE_SCOPE int udp6_gro_complete(struct sk_buff *skb, int nhoff)
169{
170 const u16 offset = NAPI_GRO_CB(skb)->network_offsets[skb->encapsulation];
171 const struct ipv6hdr *ipv6h = (struct ipv6hdr *)(skb->data + offset);
172 struct udphdr *uh = (struct udphdr *)(skb->data + nhoff);
173
174 /* do fraglist only if there is no outer UDP encap (or we already processed it) */
175 if (NAPI_GRO_CB(skb)->is_flist && !NAPI_GRO_CB(skb)->encap_mark) {
176 uh->len = htons(skb->len - nhoff);
177
178 skb_shinfo(skb)->gso_type |= (SKB_GSO_FRAGLIST|SKB_GSO_UDP_L4);
179 skb_shinfo(skb)->gso_segs = NAPI_GRO_CB(skb)->count;
180
181 __skb_incr_checksum_unnecessary(skb);
182
183 return 0;
184 }
185
186 if (uh->check)
187 uh->check = ~udp_v6_check(len: skb->len - nhoff, saddr: &ipv6h->saddr,
188 daddr: &ipv6h->daddr, base: 0);
189
190 return udp_gro_complete(skb, nhoff, lookup: udp6_lib_lookup_skb);
191}
192
193int __init udpv6_offload_init(void)
194{
195 net_hotdata.udpv6_offload = (struct net_offload) {
196 .callbacks = {
197 .gso_segment = udp6_ufo_fragment,
198 .gro_receive = udp6_gro_receive,
199 .gro_complete = udp6_gro_complete,
200 },
201 };
202 return inet6_add_offload(prot: &net_hotdata.udpv6_offload, IPPROTO_UDP);
203}
204
205int udpv6_offload_exit(void)
206{
207 return inet6_del_offload(prot: &net_hotdata.udpv6_offload, IPPROTO_UDP);
208}
209

source code of linux/net/ipv6/udp_offload.c