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