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_gso_ok(skb, features | NETIF_F_GSO_ROBUST)) {
39 /* Packet is from an untrusted source, reset gso_segs. */
40
41 skb_shinfo(skb)->gso_segs = DIV_ROUND_UP(skb->len, mss);
42
43 /* Set the IPv6 fragment id if not set yet */
44 if (!skb_shinfo(skb)->ip6_frag_id)
45 ipv6_proxy_select_ident(dev_net(skb->dev), skb);
46
47 segs = NULL;
48 goto out;
49 }
50
51 if (skb->encapsulation && skb_shinfo(skb)->gso_type &
52 (SKB_GSO_UDP_TUNNEL|SKB_GSO_UDP_TUNNEL_CSUM))
53 segs = skb_udp_tunnel_segment(skb, features, true);
54 else {
55 const struct ipv6hdr *ipv6h;
56 struct udphdr *uh;
57
58 if (!(skb_shinfo(skb)->gso_type & SKB_GSO_UDP))
59 goto out;
60
61 if (!pskb_may_pull(skb, sizeof(struct udphdr)))
62 goto out;
63
64 /* Do software UFO. Complete and fill in the UDP checksum as HW cannot
65 * do checksum of UDP packets sent as multiple IP fragments.
66 */
67
68 uh = udp_hdr(skb);
69 ipv6h = ipv6_hdr(skb);
70
71 uh->check = 0;
72 csum = skb_checksum(skb, 0, skb->len, 0);
73 uh->check = udp_v6_check(skb->len, &ipv6h->saddr,
74 &ipv6h->daddr, csum);
75 if (uh->check == 0)
76 uh->check = CSUM_MANGLED_0;
77
78 skb->ip_summed = CHECKSUM_UNNECESSARY;
79
80 /* If there is no outer header we can fake a checksum offload
81 * due to the fact that we have already done the checksum in
82 * software prior to segmenting the frame.
83 */
84 if (!skb->encap_hdr_csum)
85 features |= NETIF_F_HW_CSUM;
86
87 /* Check if there is enough headroom to insert fragment header. */
88 tnl_hlen = skb_tnl_header_len(skb);
89 if (skb->mac_header < (tnl_hlen + frag_hdr_sz)) {
90 if (gso_pskb_expand_head(skb, tnl_hlen + frag_hdr_sz))
91 goto out;
92 }
93
94 /* Find the unfragmentable header and shift it left by frag_hdr_sz
95 * bytes to insert fragment header.
96 */
97 err = ip6_find_1stfragopt(skb, &prevhdr);
98 if (err < 0)
99 return ERR_PTR(err);
100 unfrag_ip6hlen = err;
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
125 out:
126 return segs;
127 }
128
udp6_gro_receive(struct sk_buff ** head,struct sk_buff * skb)129 static 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
148 skip:
149 NAPI_GRO_CB(skb)->is_ipv6 = 1;
150 return udp_gro_receive(head, skb, uh, udp6_lib_lookup_skb);
151
152 flush:
153 NAPI_GRO_CB(skb)->flush = 1;
154 return NULL;
155 }
156
udp6_gro_complete(struct sk_buff * skb,int nhoff)157 static 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, udp6_lib_lookup_skb);
171 }
172
173 static 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
udpv6_offload_init(void)181 int udpv6_offload_init(void)
182 {
183 return inet6_add_offload(&udpv6_offload, IPPROTO_UDP);
184 }
185
udpv6_offload_exit(void)186 int udpv6_offload_exit(void)
187 {
188 return inet6_del_offload(&udpv6_offload, IPPROTO_UDP);
189 }
190