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TOMOYO Linux Cross Reference
Linux/net/ipv6/udp_offload.c

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  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 
 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 
117 static struct sk_buff **udp6_gro_receive(struct sk_buff **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 
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 
169 int udpv6_offload_init(void)
170 {
171         return inet6_add_offload(&udpv6_offload, IPPROTO_UDP);
172 }
173 
174 int udpv6_offload_exit(void)
175 {
176         return inet6_del_offload(&udpv6_offload, IPPROTO_UDP);
177 }
178 

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