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
18 static struct sk_buff *udp6_ufo_fragment(struct sk_buff *skb,
19 netdev_features_t features)
20 {
21 struct sk_buff *segs = ERR_PTR(-EINVAL);
22 unsigned int mss;
23 unsigned int unfrag_ip6hlen, unfrag_len;
24 struct frag_hdr *fptr;
25 u8 *packet_start, *prevhdr;
26 u8 nexthdr;
27 u8 frag_hdr_sz = sizeof(struct frag_hdr);
28 __wsum csum;
29 int tnl_hlen;
30 int err;
31
32 if (skb->encapsulation && skb_shinfo(skb)->gso_type &
33 (SKB_GSO_UDP_TUNNEL|SKB_GSO_UDP_TUNNEL_CSUM))
34 segs = skb_udp_tunnel_segment(skb, features, true);
35 else {
36 const struct ipv6hdr *ipv6h;
37 struct udphdr *uh;
38
39 if (!(skb_shinfo(skb)->gso_type & (SKB_GSO_UDP | SKB_GSO_UDP_L4)))
40 goto out;
41
42 if (!pskb_may_pull(skb, sizeof(struct udphdr)))
43 goto out;
44
45 if (skb_shinfo(skb)->gso_type & SKB_GSO_UDP_L4)
46 return __udp_gso_segment(skb, features, true);
47
48 mss = skb_shinfo(skb)->gso_size;
49 if (unlikely(skb->len <= mss))
50 goto out;
51
52 /* Do software UFO. Complete and fill in the UDP checksum as HW cannot
53 * do checksum of UDP packets sent as multiple IP fragments.
54 */
55
56 uh = udp_hdr(skb);
57 ipv6h = ipv6_hdr(skb);
58
59 uh->check = 0;
60 csum = skb_checksum(skb, 0, skb->len, 0);
61 uh->check = udp_v6_check(skb->len, &ipv6h->saddr,
62 &ipv6h->daddr, csum);
63 if (uh->check == 0)
64 uh->check = CSUM_MANGLED_0;
65
66 skb->ip_summed = CHECKSUM_UNNECESSARY;
67
68 /* If there is no outer header we can fake a checksum offload
69 * due to the fact that we have already done the checksum in
70 * software prior to segmenting the frame.
71 */
72 if (!skb->encap_hdr_csum)
73 features |= NETIF_F_HW_CSUM;
74
75 /* Check if there is enough headroom to insert fragment header. */
76 tnl_hlen = skb_tnl_header_len(skb);
77 if (skb->mac_header < (tnl_hlen + frag_hdr_sz)) {
78 if (gso_pskb_expand_head(skb, tnl_hlen + frag_hdr_sz))
79 goto out;
80 }
81
82 /* Find the unfragmentable header and shift it left by frag_hdr_sz
83 * bytes to insert fragment header.
84 */
85 err = ip6_find_1stfragopt(skb, &prevhdr);
86 if (err < 0)
87 return ERR_PTR(err);
88 unfrag_ip6hlen = err;
89 nexthdr = *prevhdr;
90 *prevhdr = NEXTHDR_FRAGMENT;
91 unfrag_len = (skb_network_header(skb) - skb_mac_header(skb)) +
92 unfrag_ip6hlen + tnl_hlen;
93 packet_start = (u8 *) skb->head + SKB_GSO_CB(skb)->mac_offset;
94 memmove(packet_start-frag_hdr_sz, packet_start, unfrag_len);
95
96 SKB_GSO_CB(skb)->mac_offset -= frag_hdr_sz;
97 skb->mac_header -= frag_hdr_sz;
98 skb->network_header -= frag_hdr_sz;
99
100 fptr = (struct frag_hdr *)(skb_network_header(skb) + unfrag_ip6hlen);
101 fptr->nexthdr = nexthdr;
102 fptr->reserved = 0;
103 fptr->identification = ipv6_proxy_select_ident(dev_net(skb->dev), skb);
104
105 /* Fragment the skb. ipv6 header and the remaining fields of the
106 * fragment header are updated in ipv6_gso_segment()
107 */
108 segs = skb_segment(skb, features);
109 }
110
111 out:
112 return segs;
113 }
114
115 static struct sock *udp6_gro_lookup_skb(struct sk_buff *skb, __be16 sport,
116 __be16 dport)
117 {
118 const struct ipv6hdr *iph = skb_gro_network_header(skb);
119
120 return __udp6_lib_lookup(dev_net(skb->dev), &iph->saddr, sport,
121 &iph->daddr, dport, inet6_iif(skb),
122 inet6_sdif(skb), &udp_table, NULL);
123 }
124
125 INDIRECT_CALLABLE_SCOPE
126 struct sk_buff *udp6_gro_receive(struct list_head *head, struct sk_buff *skb)
127 {
128 struct udphdr *uh = udp_gro_udphdr(skb);
129 struct sock *sk = NULL;
130 struct sk_buff *pp;
131
132 if (unlikely(!uh))
133 goto flush;
134
135 /* Don't bother verifying checksum if we're going to flush anyway. */
136 if (NAPI_GRO_CB(skb)->flush)
137 goto skip;
138
139 if (skb_gro_checksum_validate_zero_check(skb, IPPROTO_UDP, uh->check,
140 ip6_gro_compute_pseudo))
141 goto flush;
142 else if (uh->check)
143 skb_gro_checksum_try_convert(skb, IPPROTO_UDP,
144 ip6_gro_compute_pseudo);
145
146 skip:
147 NAPI_GRO_CB(skb)->is_ipv6 = 1;
148
149 if (static_branch_unlikely(&udpv6_encap_needed_key))
150 sk = udp6_gro_lookup_skb(skb, uh->source, uh->dest);
151
152 pp = udp_gro_receive(head, skb, uh, sk);
153 return pp;
154
155 flush:
156 NAPI_GRO_CB(skb)->flush = 1;
157 return NULL;
158 }
159
160 INDIRECT_CALLABLE_SCOPE int udp6_gro_complete(struct sk_buff *skb, int nhoff)
161 {
162 const struct ipv6hdr *ipv6h = ipv6_hdr(skb);
163 struct udphdr *uh = (struct udphdr *)(skb->data + nhoff);
164
165 /* do fraglist only if there is no outer UDP encap (or we already processed it) */
166 if (NAPI_GRO_CB(skb)->is_flist && !NAPI_GRO_CB(skb)->encap_mark) {
167 uh->len = htons(skb->len - nhoff);
168
169 skb_shinfo(skb)->gso_type |= (SKB_GSO_FRAGLIST|SKB_GSO_UDP_L4);
170 skb_shinfo(skb)->gso_segs = NAPI_GRO_CB(skb)->count;
171
172 if (skb->ip_summed == CHECKSUM_UNNECESSARY) {
173 if (skb->csum_level < SKB_MAX_CSUM_LEVEL)
174 skb->csum_level++;
175 } else {
176 skb->ip_summed = CHECKSUM_UNNECESSARY;
177 skb->csum_level = 0;
178 }
179
180 return 0;
181 }
182
183 if (uh->check)
184 uh->check = ~udp_v6_check(skb->len - nhoff, &ipv6h->saddr,
185 &ipv6h->daddr, 0);
186
187 return udp_gro_complete(skb, nhoff, udp6_lib_lookup_skb);
188 }
189
190 static const struct net_offload udpv6_offload = {
191 .callbacks = {
192 .gso_segment = udp6_ufo_fragment,
193 .gro_receive = udp6_gro_receive,
194 .gro_complete = udp6_gro_complete,
195 },
196 };
197
198 int udpv6_offload_init(void)
199 {
200 return inet6_add_offload(&udpv6_offload, IPPROTO_UDP);
201 }
202
203 int udpv6_offload_exit(void)
204 {
205 return inet6_del_offload(&udpv6_offload, IPPROTO_UDP);
206 }
207
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