Pileus Git - ~andy/linux/blob - net/ipv4/udp_offload.c

   1 /*
   2  *      IPV4 GSO/GRO offload support
   3  *      Linux INET 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  *      UDPv4 GSO support
  11  */
  12
  13 #include <linux/skbuff.h>
  14 #include <net/udp.h>
  15 #include <net/protocol.h>
  16
  17 static DEFINE_SPINLOCK(udp_offload_lock);
  18 static struct udp_offload_priv __rcu *udp_offload_base __read_mostly;
  19
  20 struct udp_offload_priv {
  21         struct udp_offload      *offload;
  22         struct rcu_head         rcu;
  23         struct udp_offload_priv __rcu *next;
  24 };
  25
  26 static int udp4_ufo_send_check(struct sk_buff *skb)
  27 {
  28         if (!pskb_may_pull(skb, sizeof(struct udphdr)))
  29                 return -EINVAL;
  30
  31         if (likely(!skb->encapsulation)) {
  32                 const struct iphdr *iph;
  33                 struct udphdr *uh;
  34
  35                 iph = ip_hdr(skb);
  36                 uh = udp_hdr(skb);
  37
  38                 uh->check = ~csum_tcpudp_magic(iph->saddr, iph->daddr, skb->len,
  39                                 IPPROTO_UDP, 0);
  40                 skb->csum_start = skb_transport_header(skb) - skb->head;
  41                 skb->csum_offset = offsetof(struct udphdr, check);
  42                 skb->ip_summed = CHECKSUM_PARTIAL;
  43         }
  44
  45         return 0;
  46 }
  47
  48 static struct sk_buff *udp4_ufo_fragment(struct sk_buff *skb,
  49                                          netdev_features_t features)
  50 {
  51         struct sk_buff *segs = ERR_PTR(-EINVAL);
  52         unsigned int mss;
  53         int offset;
  54         __wsum csum;
  55
  56         if (skb->encapsulation &&
  57             skb_shinfo(skb)->gso_type & SKB_GSO_UDP_TUNNEL) {
  58                 segs = skb_udp_tunnel_segment(skb, features);
  59                 goto out;
  60         }
  61
  62         mss = skb_shinfo(skb)->gso_size;
  63         if (unlikely(skb->len <= mss))
  64                 goto out;
  65
  66         if (skb_gso_ok(skb, features | NETIF_F_GSO_ROBUST)) {
  67                 /* Packet is from an untrusted source, reset gso_segs. */
  68                 int type = skb_shinfo(skb)->gso_type;
  69
  70                 if (unlikely(type & ~(SKB_GSO_UDP | SKB_GSO_DODGY |
  71                                       SKB_GSO_UDP_TUNNEL |
  72                                       SKB_GSO_IPIP |
  73                                       SKB_GSO_GRE | SKB_GSO_MPLS) ||
  74                              !(type & (SKB_GSO_UDP))))
  75                         goto out;
  76
  77                 skb_shinfo(skb)->gso_segs = DIV_ROUND_UP(skb->len, mss);
  78
  79                 segs = NULL;
  80                 goto out;
  81         }
  82
  83         /* Do software UFO. Complete and fill in the UDP checksum as
  84          * HW cannot do checksum of UDP packets sent as multiple
  85          * IP fragments.
  86          */
  87         offset = skb_checksum_start_offset(skb);
  88         csum = skb_checksum(skb, offset, skb->len - offset, 0);
  89         offset += skb->csum_offset;
  90         *(__sum16 *)(skb->data + offset) = csum_fold(csum);
  91         skb->ip_summed = CHECKSUM_NONE;
  92
  93         /* Fragment the skb. IP headers of the fragments are updated in
  94          * inet_gso_segment()
  95          */
  96         segs = skb_segment(skb, features);
  97 out:
  98         return segs;
  99 }
 100
 101 int udp_add_offload(struct udp_offload *uo)
 102 {
 103         struct udp_offload_priv __rcu **head = &udp_offload_base;
 104         struct udp_offload_priv *new_offload = kzalloc(sizeof(*new_offload), GFP_KERNEL);
 105
 106         if (!new_offload)
 107                 return -ENOMEM;
 108
 109         new_offload->offload = uo;
 110
 111         spin_lock(&udp_offload_lock);
 112         rcu_assign_pointer(new_offload->next, rcu_dereference(*head));
 113         rcu_assign_pointer(*head, new_offload);
 114         spin_unlock(&udp_offload_lock);
 115
 116         return 0;
 117 }
 118 EXPORT_SYMBOL(udp_add_offload);
 119
 120 static void udp_offload_free_routine(struct rcu_head *head)
 121 {
 122         struct udp_offload_priv *ou_priv = container_of(head, struct udp_offload_priv, rcu);
 123         kfree(ou_priv);
 124 }
 125
 126 void udp_del_offload(struct udp_offload *uo)
 127 {
 128         struct udp_offload_priv __rcu **head = &udp_offload_base;
 129         struct udp_offload_priv *uo_priv;
 130
 131         spin_lock(&udp_offload_lock);
 132
 133         uo_priv = rcu_dereference(*head);
 134         for (; uo_priv != NULL;
 135                 uo_priv = rcu_dereference(*head)) {
 136
 137                 if (uo_priv->offload == uo) {
 138                         rcu_assign_pointer(*head, rcu_dereference(uo_priv->next));
 139                         goto unlock;
 140                 }
 141                 head = &uo_priv->next;
 142         }
 143         pr_warn("udp_del_offload: didn't find offload for port %d\n", ntohs(uo->port));
 144 unlock:
 145         spin_unlock(&udp_offload_lock);
 146         if (uo_priv != NULL)
 147                 call_rcu(&uo_priv->rcu, udp_offload_free_routine);
 148 }
 149 EXPORT_SYMBOL(udp_del_offload);
 150
 151 static struct sk_buff **udp_gro_receive(struct sk_buff **head, struct sk_buff *skb)
 152 {
 153         struct udp_offload_priv *uo_priv;
 154         struct sk_buff *p, **pp = NULL;
 155         struct udphdr *uh, *uh2;
 156         unsigned int hlen, off;
 157         int flush = 1;
 158
 159         if (NAPI_GRO_CB(skb)->udp_mark ||
 160             (!skb->encapsulation && skb->ip_summed != CHECKSUM_COMPLETE))
 161                 goto out;
 162
 163         /* mark that this skb passed once through the udp gro layer */
 164         NAPI_GRO_CB(skb)->udp_mark = 1;
 165
 166         off  = skb_gro_offset(skb);
 167         hlen = off + sizeof(*uh);
 168         uh   = skb_gro_header_fast(skb, off);
 169         if (skb_gro_header_hard(skb, hlen)) {
 170                 uh = skb_gro_header_slow(skb, hlen, off);
 171                 if (unlikely(!uh))
 172                         goto out;
 173         }
 174
 175         rcu_read_lock();
 176         uo_priv = rcu_dereference(udp_offload_base);
 177         for (; uo_priv != NULL; uo_priv = rcu_dereference(uo_priv->next)) {
 178                 if (uo_priv->offload->port == uh->dest &&
 179                     uo_priv->offload->callbacks.gro_receive)
 180                         goto unflush;
 181         }
 182         goto out_unlock;
 183
 184 unflush:
 185         flush = 0;
 186
 187         for (p = *head; p; p = p->next) {
 188                 if (!NAPI_GRO_CB(p)->same_flow)
 189                         continue;
 190
 191                 uh2 = (struct udphdr   *)(p->data + off);
 192                 if ((*(u32 *)&uh->source != *(u32 *)&uh2->source)) {
 193                         NAPI_GRO_CB(p)->same_flow = 0;
 194                         continue;
 195                 }
 196         }
 197
 198         skb_gro_pull(skb, sizeof(struct udphdr)); /* pull encapsulating udp header */
 199         pp = uo_priv->offload->callbacks.gro_receive(head, skb);
 200
 201 out_unlock:
 202         rcu_read_unlock();
 203 out:
 204         NAPI_GRO_CB(skb)->flush |= flush;
 205         return pp;
 206 }
 207
 208 static int udp_gro_complete(struct sk_buff *skb, int nhoff)
 209 {
 210         struct udp_offload_priv *uo_priv;
 211         __be16 newlen = htons(skb->len - nhoff);
 212         struct udphdr *uh = (struct udphdr *)(skb->data + nhoff);
 213         int err = -ENOSYS;
 214
 215         uh->len = newlen;
 216
 217         rcu_read_lock();
 218
 219         uo_priv = rcu_dereference(udp_offload_base);
 220         for (; uo_priv != NULL; uo_priv = rcu_dereference(uo_priv->next)) {
 221                 if (uo_priv->offload->port == uh->dest &&
 222                     uo_priv->offload->callbacks.gro_complete)
 223                         break;
 224         }
 225
 226         if (uo_priv != NULL)
 227                 err = uo_priv->offload->callbacks.gro_complete(skb, nhoff + sizeof(struct udphdr));
 228
 229         rcu_read_unlock();
 230         return err;
 231 }
 232
 233 static const struct net_offload udpv4_offload = {
 234         .callbacks = {
 235                 .gso_send_check = udp4_ufo_send_check,
 236                 .gso_segment = udp4_ufo_fragment,
 237                 .gro_receive  = udp_gro_receive,
 238                 .gro_complete = udp_gro_complete,
 239         },
 240 };
 241
 242 int __init udpv4_offload_init(void)
 243 {
 244         return inet_add_offload(&udpv4_offload, IPPROTO_UDP);
 245 }