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